School of Chemical and Minerals Engineering
Faculty of Engineering
School of Chemical and Minerals Engineering
Hydrotreament of bio-oil from spent coffee
grounds to produce renewable diesel
Completed by:
AR de Melim
25063502
North-West University Potchefstroom Campus
Supervisor:
Dr R. Venter
6 November 2017
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School of Chemical and Minerals Engineering
ABSTRACT
The main focus for this study was the hydrotreatment of bio-oil that was extracted from spent
coffee grounds to produce a good quality transportation fuel. The spent coffee grounds used
for the extraction process was collect from various coffee shops in Potchefstroom. The
alternative transportation fuels or bio-hydrocarbons were produced by hydrotreating the
extracted coffee bio-oil in the presence of 2 different hydrotreating catalysts. The effect of the
catalyst choice as well as the reaction temperature on the feed conversion, fuel product boiling
range distribution and the liquid product composition, yield and calorific values was evaluated.
The feasibility of using spent coffee grounds as an alternative feedstock for transportation fuel
production was evaluated. The coffee bio-oil was extracted from the spent grounds by means
of soxhlet extraction and 2 different solvents, namely polar methanol and non-polar hexane.
The highest recorded oil extracted yield of 17.55 % was obtained by using the non-polar
solvent hexane. This is due to the lower molecular charges that the non-polar solvents has,
which provides a better penetration into the feed matrix. Due to a higher amount of oil being
extracted through the non-polar solvent. It is therefore concluded that the fatty acid oil in the
SCG mostly consists of triglycerides.
A reaction temperature range of 350 °C to 410 °C with a 20 °C increment was chosen in this
study. The hydrotreating catalysts, NiMo-Al2O3 and CoMo-Al2O3 have been evaluated in every
set of the chosen reaction conditions. The initial hydrogen pressure, reaction time and amount
of feedstock was kept constant at 90 bar, 60 minutes and 40 g respectively. The reactor vessel
was purged with nitrogen to eliminate all oxygen present and the catalysts were activated by
pre-sulphuring with H2S/ Ar.
It was found that the most appropriate temperature in terms of diesel selectivity, liquid product
composition, calorific value and liquid product yield were obtained at a reaction temperature
of 390 °C for catalysts. It was found that in terms of feed conversion, calorific values, and liquid
product yield both the NiMo-Al2O3 and CoMo-Al2O3 catalyst produced values within the
experimental error margin, indicating that the two catalysts produced the same results.
However, in the case of the fuel yield and liquid product composition, a clear difference was
seen.
The NiMo-Al2O3 catalyst produced a higher qualitative liquid product with lower amounts of
cyclic compounds, aromatics and oxygenates in its composition and less heavy fuel oils being
produced. Due to its better qualitative value, the liquid product produced in the presence of
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School of Chemical and Minerals Engineering
NiMo-Al2O3 at 390 °C was deemed the most appropriate liquid product to compare to the
diesel standard of South Africa.
Analysis of this liquid fuel showed that the fuel has a sulphur content of less than 1 ppm, a
water content of 30.3 mg/kg and an oxidation stability of larger than 12 hours. It also recorded
a T90 temperature of 305 °C at which 90 weight percentage of the product has been distillated.
All of the mentioned results fell well within the SANS 342 diesel standards. However, a low
flashpoint of 35.8 °C has been recorded as well as a high cloud point temperature of 16 °C.
These results do not satisfy the diesel standards, however these shortcoming could be
improved. The lighter components present in the liquid product may be flashed off to increase
the overall flash point. Isomerization processes may also be conducted on the liquid product
to increase the isomer content in order to improve the cloud point temperature, which will result
in a high quality transportation fuel produced from spent coffee grounds. The more appropriate
temperature in terms of diesel selectivity and liquid product composition was at 390 ° and the
better catalyst was found to be NiMo-Al2O3 due to the higher qualitative liquid product that was
produced.
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DECLARATION OF AUTHORSHIP
I declare that this report is a presentation of my own original work.
Whenever contributions of others are involved, every effort was made to indicate this clearly,
with due reference to the literature.
No part of this work has been submitted in the past, or is being submitted, for a degree or
examination at any other university or course.
Signed on this, 6 day of November in Potchefstroom.
_________________________________
INITIALS AND SURNAME
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ACKNOWLEDGEMENTS
“Press forward. Do not stop, do not linger in your journey, but strive for the mark set before
you.”
George Whitefield
I would like to thank my family and friends for supporting me and most of all I would like to
thank God for giving me the strength to continue through the most difficult days.
I as the author of this dissertation would like to thank the following people for their support
and help in completing this project:

Dr. Roelf Venter for being there no matter the time for guidance and advice.

Dr. Sanjay Karmee for his guidance and advice.

Mr. Jan Kroeze and Mr. Adriaan Brock for their technical support during my
experimental processes.

Mr. Gideon van Rensburg for his guidance and advice in the laboratory during my
experimental and analytical procedures.

Mr. Nico Lemmer for his assistance in and analysis using the bomb calorimeter.

All the personnel and students from the School of Chemical Engineering for all the
support and advice to complete my project.
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TABLE OF CONTENTS
1.
2.
Introduction .................................................................................................................... 1
1.1
Background and motivation..................................................................................... 1
1.2
Problem statement .................................................................................................. 2
1.3
Aim and objective ................................................................................................... 2
1.4
Scope of the dissertation......................................................................................... 2
1.5
Study outline ........................................................................................................... 3
Literature Review ........................................................................................................... 5
2.1
Introduction ............................................................................................................. 5
2.2
Renewable Feedstock ............................................................................................ 6
2.3
Bio-oil Extraction Processes ................................................................................... 9
2.3.1
Supercritical CO2 Extraction ............................................................................. 9
2.3.2
Soxhlet Extraction .......................................................................................... 10
2.4
Renewable Diesel Processes ............................................................................... 10
2.4.1
3.
Hydrotreatment .............................................................................................. 10
2.5
Modern Hydrotreatment ........................................................................................ 20
2.6
Hydrotreatment Problems ..................................................................................... 20
2.7
Concluding Remarks............................................................................................. 21
Experimental Method ................................................................................................... 23
3.1
Materials and Reagents ........................................................................................ 23
3.1.1
Materials ........................................................................................................ 23
3.1.2
Gasses and chemicals ................................................................................... 24
3.2
Soxhlet extraction ................................................................................................. 26
3.2.1
Experimental Setup........................................................................................ 26
3.2.2
Experimental method ..................................................................................... 27
3.3
Hydrotreatment process ........................................................................................ 30
3.3.1
Experimental setup ........................................................................................ 30
3.3.2
Experimental method ..................................................................................... 32
3.4
Analytical equipment and methodology ................................................................. 36
3.4.1
Oil extracted yield .......................................................................................... 36
3.4.2
Produced Hydrotreatment Liquid product yield............................................... 36
3.4.3
Triglycerides analysis..................................................................................... 37
3.4.4
Bomb Calorimeter .......................................................................................... 37
3.4.5
GC-MS........................................................................................................... 38
3.4.6
ICP-OES Analysis .......................................................................................... 40
3.4.7
Eralystics ERAFLASH .................................................................................... 41
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3.4.8
4.
Cloud point .................................................................................................... 42
Results and Discussion ................................................................................................ 43
4.1
Oil extraction from SCG ........................................................................................ 43
4.1.1
Effect of solvent used for extraction process on the bio-oil yield .................... 43
4.1.2
Effect of solvent used for extraction process on the bio-oil composition ......... 45
4.1.3
Effect of solvent used for extraction process on the bio-oil calorific value ...... 46
4.2
Hydrotreatment of oil extracted from spent coffee grounds ................................... 47
4.2.1
Ni/Mo hydrotreating catalyst ........................................................................... 47
4.2.2
Co/Mo catalyst results.................................................................................... 56
4.2.3
Catalyst comparison ...................................................................................... 63
4.2.4
Produced liquid product comparison with SANS342 ...................................... 67
5.
Conclusion and recommendations ............................................................................... 75
6.
References .................................................................................................................. 78
Appendix A- SCG extraction calculation .............................................................................. 86
Experimental error calculations for various solvent extractions ........................................ 86
Calculation of weight percentage of FFA present in the extracted SCG bio-oil ................ 86
Experimental error calculation for calorific values ............................................................ 87
Appendix B- Catalyst comparison ....................................................................................... 89
Appendix C- Calculations of hydrotreated SCG bio-oil in the presence of both NiMo/Al2O3 and
CoMo/Al2O3 ......................................................................................................................... 91
Experimental error calculations for the feed conversion ................................................... 91
Experimental error calculations for the liquid product yield .............................................. 92
Experimental error calculation for calorific values ............................................................ 92
Selectivity calculations for the product liquid .................................................................... 93
Appendix D- Simulation distillation graphs .......................................................................... 94
Appendix E- Analytical results ........................................................................................... 101
Highest calorific values obtained for both catalysts ........................................................ 101
Flash point of most appropriate liquid product ............................................................... 103
GC-MS chromatograms ................................................................................................. 104
Oxidation stability .......................................................................................................... 108
Method for GC-MS analysis........................................................................................... 109
Appendix F- ECSA exit level outcomes (ELO’s) ................................................................ 110
ELO 1: Problem solving ................................................................................................. 110
ELO 2: Application of scientific and engineering knowledge .......................................... 110
ELO 3: Engineering Design ........................................................................................... 111
ELO 4: Investigations, experiments and data analysis ................................................... 111
ELO 5: Engineering methods, skills and tools, including Information Technology .......... 112
ELO 6: Professional and technical communication ........................................................ 112
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ELO 7: Sustainability and impact of engineering activity ................................................ 113
ELO 8: Individual, team and multidisciplinary working ................................................... 113
ELO 9: Independent learning ability ............................................................................... 114
ELO 10: Engineering Professionalism ........................................................................... 114
ELO 11: Engineering Management................................................................................ 114
TABLE OF FIGURES
Figure 1. 1- Carbon dioxide cycle of coffee bio-oil. ............................................................... 1
Figure 1. 2- Study outline. .................................................................................................... 3
Figure 2. 1- Effect of recycling rate of paper on production energy and CO2 emissions. ...... 7
Figure 2. 2- Coffee consumption worldwide in 2010. ............................................................ 7
Figure 2. 3- Deoxygenation pathways during hydrotreatment. ............................................ 12
Figure 2. 4- Methanation side-reaction during hydrotreatment. ........................................... 13
Figure 3. 1- Display of Soxhlet extractor set up. ................................................................. 26
Figure 3. 2- Pictorial view of experimental setup within the wet bench ............................... 27
Figure 3. 3- Summary of experimental extraction procedure. ............................................. 28
Figure 3. 4- Rotary evaporator apparatus. .......................................................................... 30
Figure 3. 5- Pictorial view of the hydrotreating reactor after complete setup. ...................... 32
Figure 3. 6- Summary of hydrotreatment experimental process. ........................................ 33
Figure 3. 7- Pictorial display of the removal of the produced hydrotreatment liquid product.35
Figure 3. 8- Pictorial display of produced clean liquid product. ........................................... 35
Figure 3. 9- Pictorial view of the Bomb Calorimeter. ........................................................... 38
Figure 3. 10- Pictorial view of the GC-MS........................................................................... 39
Figure 3. 11- Pictorial view of the ICP-OES machine.......................................................... 40
Figure 3. 12- Pictorial view of the ERAFLASH. ................................................................... 41
Figure 3. 13- Pictorial view of the cloud point analyses. ..................................................... 42
Figure 4. 1- Average extraction yield calculated for desired solvent. .................................. 44
Figure 4. 2- Quantitative results of free fatty acids present in bio-oil extracted by means of
different solvents. ................................................................................................................ 45
Figure 4. 3- Calorific values of extracted bio-oils from different extraction solvents. ........... 47
Figure 4. 4- Hydrotreating experimental repeats at a temperature of 390 °C in the presence
of NiMo/Al2O3..................................................................................................................... 48
Figure 4. 5- Effect of temperature on the feed conversion in the presence of NiMo/Al2O3. 48
Figure 4. 6- Temperature effect on liquid product composition in the presence of a
NiMo/Al2O3 catalyst ........................................................................................................... 50
Figure 4. 7- Hydrotreating experimental repeats at a temperature of 390 °C in the presence
of NiMo/Al2O3..................................................................................................................... 51
Figure 4. 8- Hydrotreating experimental repeats at a temperature of 390 °C in the presence
of NiMo/Al2O3..................................................................................................................... 52
Figure 4. 9- Liquid product produced in the presence of NiMo/Al¬2O3. .............................. 53
Figure 4. 10- Liquid product weight yield in the presence of NiMo/Al2O3. ............................ 53
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Figure 4. 11- Calorific values of liquid products at different temperatures in the presence of
NiMo/Al2O3. ....................................................................................................................... 54
Figure 4. 12- The temperature effect on the liquid fuel boiling range distribution from
hydrotreated coffee bio-oil in the presence of NiMo/Al2O3. ................................................. 56
Figure 4. 13- Effect of temperature on the feed conversion in the presence of CoMo/Al2O3.
........................................................................................................................................... 57
Figure 4. 14- Influence that temperature has on the liquid product fuels produced from
hydrotreating coffee bio-oil in the presence of CoMo/Al2O3. ............................................... 58
Figure 4. 15- Liquid fuel produced in the presence of CoMo/Al2O3. ................................... 59
Figure 4. 16- Liquid product weight yield in the presence of CoMo/Al2O3. ......................... 60
Figure 4. 17- Calorific values of liquid products at different temperatures in the presence of
CoMo/Al2O3. ...................................................................................................................... 61
Figure 4. 18- The temperature effect on the liquid fuel boiling range distribution from
hydrotreated coffee bio-oil in the presence of CoMo/Al2O3................................................. 62
Figure 4. 19- Comparison of liquid fuel’s feed conversion and production yield percentage in
the presence of different catalysts at an optimal temperature of 390 °C. ............................. 63
Figure 4. 20- Comparison of calorific values in the presence of different catalysts at an optimal
temperature of 390 °C. ........................................................................................................ 64
Figure 4. 21- Comparison of liquid fuel’s composition in the presence of different catalysts at
an optimal temperature of 390 °C. ...................................................................................... 65
Figure 4. 22- Simulation distillation of most appropriate liquid product produced at 390 °C in
the presence of NiMo/Al2O3. .............................................................................................. 70
Figure 4. 23- Chromatogram of the product liquid produced at 390 °C in presence of
NiMo/Al2O3. ....................................................................................................................... 72
Figure A. 1- Calculation of the experimental errors for the different extracted bio-oils extraction
yields by means of standard deviation. ............................................................................... 86
Figure A. 2- Quantitative calculation of FFA present in solvent extracted bio-oils. .............. 87
Figure A. 3- Calculation of the experimental errors for the different extracted bio-oils caloric
values by means of standard deviation. .............................................................................. 88
Figure B. 1- Summary of all hydrotreating procedures done with the catalyst choice and
reaction temperature as reaction variables.......................................................................... 89
Figure B. 2- Calculations of all hydrotreated procedures feed conversion. ......................... 90
Figure C. 1- Calculation of the experimental errors of the feed conversion for the hydrotreated
SCG bio-oil in the presence of NiMo/Al2O3 at 390 °C. ........................................................ 91
Figure C. 2- Calculation of the experimental errors of the feed conversion for the hydrotreated
SCG bio-oil in the presence of CoMo/Al2O3 at 390 °C........................................................ 91
Figure C. 3- Calculation of the experimental errors of the liquid product produced and yield
percentage for the hydrotreated SCG bio-oil in the presence of NiMo/Al2O3 at 390 °C. ..... 92
Figure C. 4- Calculation of the experimental errors of the liquid product produced and yield
percentage for the hydrotreated SCG bio-oil in the presence of CoMo/Al2O3 at 390 °C. .... 92
Figure C. 5- Calculation of the experimental errors of the produced liquid products by means
of standard deviation for both catalytic hydrotreating procedures. ....................................... 93
Figure C. 6- Demonstration for the calculation of each component’s selectivity in the case of
all produced liquid products................................................................................................. 93
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Figure D. 1- Simulation distillation graph of the liquid product produced in the presence of
NiMo/Al2O3 at 350 °C. ........................................................................................................ 94
Figure D. 2- Simulation distillation graph of the liquid product produced in the presence of
NiMo/Al2O3 at 370 °C. ........................................................................................................ 95
Figure D. 3- Simulation distillation graph of the liquid product produced in the presence of
NiMo/Al2O3 at 390 °C. ........................................................................................................ 95
Figure D. 4- Simulation distillation graph of the liquid product produced in the presence of
NiMo/Al2O3 at 410 °C. ........................................................................................................ 96
Figure D. 5- Simulation distillation graph of the liquid product produced in the presence of
CoMo/Al2O3 at 350 °C........................................................................................................ 96
Figure D. 6- Simulation distillation graph of the liquid product produced in the presence of
CoMo/Al2O3 at 370 °C........................................................................................................ 97
Figure D. 7- Simulation distillation graph of the liquid product produced in the presence of
CoMo/Al2O3 at 390 °C........................................................................................................ 97
Figure D. 8- Simulation distillation graph of the liquid product produced in the presence of
CoMo/Al2O3 at 410 °C........................................................................................................ 98
Figure D. 9- Simulation distillation graph of the liquid product produced in the presence of
NiMo/Al2O3 at 390 °C experimental repeat #1. ................................................................... 98
Figure D. 10- Simulation distillation graph of the liquid product produced in the presence of
NiMo/Al2O3 at 390 °C experimental repeat #2. ................................................................... 99
Figure D. 11- Simulation distillation graph of the liquid product produced in the presence of
CoMo/Al2O3 at 390 °C experimental repeat #1................................................................... 99
Figure D. 12- Simulation distillation graph of the liquid product produced in the presence of
CoMo/Al2O3 at 390 °C experimental repeat #2................................................................. 100
Figure E. 1- Pictorial view of best-recorded calorific value in the presence of NiMo/Al2O3
obtained from the liquid product produced at 390 °C. ........................................................ 101
Figure E. 2- Pictorial view of best-recorded calorific value in the presence of CoMo/Al2O3
obtained from the liquid product produced at 390 °C. ........................................................ 102
Figure E. 3- Pictorial view of flash point obtained from most appropriate produced liquid
product in the presence of NiMo/Al2O3 at 390 °C. ............................................................ 103
Figure E. 4- Chromatogram of extracted SCG bio-oil by using the non-polar hexane as the
solvent. ............................................................................................................................. 104
Figure E. 5- Chromatogram of extracted SCG bio-oil by using the polar methanol as the
solvent. ............................................................................................................................. 105
Figure E. 6- Chromatogram of produced liquid product in the presence of NiMo/Al2O3 at 390
°C...................................................................................................................................... 106
Figure E. 7- Chromatogram of produced liquid product in the presence of CoMo/Al2O3 at 390
°C...................................................................................................................................... 107
Figure E. 8- Pictorial view of the oxidation stability results obtained from the liquid product
produced in the presence of NiMo/Al2O3 at 390 °C. ......................................................... 108
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TABLE OF TABLES
Table 2. 1- Recorded calorific values of fatty acids according to (Demirbas, 2016). .............. 9
Table 3. 1- Properties of the SCG. ...................................................................................... 24
Table 3. 2- Gasses and chemical used during extraction of coffee bio-oil and hydrotreatment
of coffee bio-oil.................................................................................................................... 25
Table 4. 1- Comparison between produced renewable diesel against SANS 342 standards.
........................................................................................................................................... 68
Table E. 1- Method for GC-MS analytical machine. .......................................................... 109
LIST OF ABBREVIATIONS
µ
Micro
g
Gram
GC-FAME
Gas chromatographic quantifier of fatty acid methyl esters
GC-MS
Gas chromatography–mass spectrometry
h
Hours
HDC
Hydro decarbonylation and decarboxylation
HDN
Hydrodenitrogenation
HDO
Hydrodeoxygenation
HDS
Hydrodesulphurization
HTL
Hydrothermal Liquefaction
ICP-OES
Inductively coupled plasma optical emission spectrometry
kg
Kilogram
L
litre
m
Meter
min
Minutes
mL
Millilitre
mm
Millimetre
PPM
Parts Per Million
SCG
Spend coffee grounds
WFOME
Waste Frying Oil Methyl Esters
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1. INTRODUCTION
1.1
Background and motivation
Since the discovery that coal may be used as a primary energy source during the Industrial
Revolution in the 18th century, the usage thereof has increased dramatically throughout the
years (Moore, 2016). In the modern age, the need for fossil fuels to fulfill the human’s day-today life has become one of the most important needs in our life. The global consumption rate
for oil in fossil fuels yearly is estimated to be over 11 billion tones (Smith, 2011). Due to the
realizing threat of the depletion of fossil fuels, an alternative method for the production of fuels
is needed.
Between the years of 1893 to 1899, Rudolf Diesel proposed and designed a diesel engine that
would operate solely from bio-oils. The production of an engine that operates solely from biooils was the origin for the alternative methods to produce fuels (Jääskeläinen, 2013). The
production of commercialized biofuels, namely biodiesel and bio-ethanol, are produced from
food crops by means of transesterification and fermentation. However, the production of
biodiesel by means of transesterification is an alternative solution for fossil fuels, it has certain
limitations. These limitations include low oxidative stability, inefficient cold flow properties and
low energy content compared to petroleum diesel (Shadid & Jamal, 2011). By means of
hydrotreating the bio-oil, bio-hydrocarbons are produced which is more efficient compared to
biodiesel (Shadid & Jamal, 2011).
The bio-oil that is used in the production of renewable diesel may be extracted from beans
and seeds. In South Africa alone, more than 20 000 tons of coffee is consumed per annum
(Sakuragi, et al., 2016). Thus if these spent coffee ground can be used in the production of
renewable diesel, it will provide a healthy and green cycle for the production and consumption
of carbon dioxide as illustrated by Figure 1. 1.
Coffee plant
produces
coffee
beans
Coffee plant
uses CO2 to
grow
Renewable
diesel is
burned and
CO2 is
releashed
Bio-oil is
extracted
from the
coffee
beans
Bio-oil is
used to
produce
renewble
diesel
Figure 1. 1- Carbon dioxide cycle of coffee bio-oil.
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1.2
Problem statement
The usage of biofuels in 2014 provided 4% of the world road transport fuel and it is expected
to increase in the up and coming years (Williams & Jones, 2015). The production of renewable
diesel from bio-oil is a worldwide used method for “green-diesel”, although the effect of
reaction conditions for a NiMo/γ–Al2O3 and CoMo/γ–Al2O3 catalyst on the product yield and
composition have not been compared using bio-oil that is extracted from a spent coffee ground
feedstock
1.3
Aim and objective
The aim for the project is to assess the quality and yield of the biofuel that is produced by the
hydrotreament of oil, which was extracted from spent coffee grounds.
In order to fulfill the aim, set for the project the following objectives must be met:

To assess the effect of different solvents on the oil’s quality and quantity during soxhlet
extraction (thus to produce sufficient bio-oil)

To determine the optimum fuel yield for different reaction conditions during the
hydrotreatment of oil extracted from SCG

To compare the liquid product composition at different reaction conditions for the
selected catalysts of NiMo/γ–Al2O3 and CoMo/γ–Al2O3
1.4
Scope of the dissertation
The study consists out of two experimental procedures namely the extraction of bio-oil from
SCG and the hydrotreament of the bio-oil at different reaction conditions.
The extraction of the bio-oil from the SCG is done by means of a soxhlet extractor. Different
solvents namely a polar Methanol and a non-polar Hexane is used as the extraction liquid.
After the soxhlet extraction process is complete, the remaining liquid is collected and the
used solvent is boiled off safely and the remaining liquid is the bio-oil.
The obtained bio-oil from the soxhlet extractor method will undergo various analyses’ for
yield, quality and energy content. The analyses are as follow:

Yield analysis: Weight based calculations

Quality analysis: Gas chromatography

Energy content analysis: Bomb calorific meter
The obtained bio-oil is then used in the production of renewable diesel by means of
hydrotreating the bio-oil. As mentioned in section 1.3, the optimum fuel yield for different
reaction conditions during the hydrotreamnet of the bio-oil is required. Thus, the hydrotreating
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process will undergo 6 sub-experiments where different temperatures and catalysts is tested.
Two catalyst types namely NiMo/ γ –Al2O3 and CoMo/ γ –Al2O3 will be used at different
temperature ranges of 370°C, 390°C and 410°C. After each hydrotreating process, the liquid
that remains in the reactor is the produced renewable diesel.
The renewable diesel produced from the hydrotreated bio-oil will undergo various analyses’ to
obtain the mention aim in section 1.3. The analyses’ are as follow:

Yield analysis: Weight based calculations

Quality analysis: Gas chromatography

Energy content analysis: Bomb calorific meter

ASTM diesel standard analysis:
1.5
o
Viscosity
o
Flash point
o
Cold flow properties
Study outline
The layout of this study is illustrated by Figure 1. 2 as:
Chapter
1
Introduction
Chapter
2
Literature Review
Chapter
3
Experimental
procedure
Chapter
4
Results
Discussion
Chapter
5
Conclusions
Recommendations
Figure 1. 2- Study outline.
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The study outline is thus done in five chapters, where each chapter has a crucial piece of
information. The study outline is further expanded as follow:

Chapter 1: This section is thus the introduction section of the study. It gives an
important background about the problem statement and derives an aim for the study
with a scope for the execution of the aim.

Chapter 2: This section gives a literature background about previous recorded data
and experiments that has similarity and is deemed as important to this study.

Chapter 3: This section is the practical part of the study where the experiments are
performed. A detailed experimental setup and procedure is explained and given on the
execution of the study’s experiments

Chapter 4: This section is where the experimental data that was recorded during the
procedures is illustrated and discussed.

Chapter 5: In this section is where the conclusions and recommendations of the study
is made. It is mentioned if the aim has been accomplished and if the study is plausible.
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2. LITERATURE REVIEW
2.1
Introduction
Due to the exponential usage of limited fossil fuels and the threat of the depletion thereof,
alternative energy feed stocks such as biomass is focused on. These biomasses may be
classified into four origin bases namely food crops, residues and waste obtained from
agricultures, forestry waste and industrial and human waste (Maity, 2015). These alternative
energy sources are classified as eco-friendly resources due to it being recyclable. In
Bangladesh, the usage of bio-energy sources is used due to the limiting amounts of the
country’s fossil fuels and through the usage thereof, the power generation has increased from
0.3 to 0.5 percent (Ahmed, et al., 2014). With a rapid growth rate of the earth’s human
population, the need for energy obtained from fossil fuels has also increased exponentially
and thus it has been predicted that fossil fuels will be depleted by the year 2088 (Lior, 2008).
By definition according to (Watson, et al., 1990), greenhouse gases are gases that contribute
in the absorbance of infrared radiation from the sun. In 2015, 27 percent of the total
greenhouse gases that were emitted in the annum was caused by means of transportation
(United States Enviromental Protection Agency, 2017). From 1990 to 2012, the total emission
of greenhouse gases per annum has increased by 41 percent and it is predicted that the
earth’s surface temperature will have increased between 1.1 to 6.4 °C at the end of the 2100
(Samimi & Zarinabadi, 2012). A study done by (Utlu & Kocak, 2008) reviewed the conclusion
that waste frying oil methyl esters may be used as a source for renewable energy. It was
further concluded that the chemical as well as the physical properties for the waste frying oil
methyl esters were similar to that of diesel fuel. In comparison to the diesel fuel, the WFOME
has resulted in a 17.14 percent CO and 1.45 percent NOx decrease in terms of emissions, a
14.34 percent higher consumption rate and a decreased exhaust temperature of 6.5 percent.
Promising alternatives for the production of transportation fuels have been produced from
biomass. These alternative bio-fuels include fatty acid methyl ester or FAME and this fuel is
more commonly revered to as biodiesel. This fuel however does not compare to well against
commercialized fossil fuel diesel due to its poor cold flow properties and storage stability
(Singaram, 2009). Along with the poor comparison the by-products are also consisted a
negative part of the production of biodiesel. The byproduct glycerol, although it may be sold
separately for the use by food industries, must firstly be pre-treated before obtaining the
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valuable product. This pre-treatment process is deemed an expensive process and will result
in an increase in the overall biodiesel production cost rate (Rehman, et al., 2008).
Alternatively, renewable diesel may be produced by means of hydrotreating the bio-oil instead
of transesterification of the bio-oil for the production of fatty acid methyl esters or FAME
biodiesel. As mentioned in section 1.1 by means of hydrotreating the bio-oil, bio-hydrocarbons
is formed. According to (Knothe, 2009) renewable diesel simulates petrodiesel , thus
renewable diesel compares better against its counterpart biodiesel in terms of its cold flow
properties and storage stability. Additionally for the production of renewable diesel, existing
infrastructures of petroleum refiners is used, thus no additional capital cost is needed for the
change of feed sources from fossil fuels to biomasses (Bezergianni & Kalogianni, 2009).
2.2
Renewable Feedstock
As mentioned in section
Introduction , for the production of alternative transportation fuels biomasses are used instead
of fossil fuels. Specifically for the production of transportation fuels the biomass bases used
for this is food crops, residues and waste obtained from agricultures. Large biomass industries
have been created to produce mass amounts of bio-oil, one of which is a large palm oil industry
located in Malaysia. They grow and extract palm oil from the fruit grown in palm trees to supply
it for the use as a biomass energy source (Yusoff, 2006).
Biomasses may be used as both food or energy sources and thus the problem arises that
which option has higher priority. A study done by (Pimentel, et al., 1988) states that both
energy and food are indeed a high priority for the human race and thus compromises must be
made to establish a stable balance between the two options. The use of bioenergy has multiple
advantages, such as lower carbon dioxide emission levels, less limiting source than fossil
fuels, etc., however large biomass industries reduces the available area for agricultural
productions and thus results in a reduction in the production of food resources (Ignaciuk, et
al., 2006). As stated by (Abbasi & Abbasi, 2010) the uprising of biomass industries for an
alternative energy supply has resulted in several environmental problems such as, 1.5%
annual rate of deforestation due to an increased need of palm oil in Malaysia, increased water
pollution in Arizona America due to water resources needed for biomass production, etc. Thus,
another solution must be developed for the use of biomass as an alternative energy source.
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In the production of paper, by means of using recovered paper as a feedstock lowers the
production energy use as well as the carbon dioxide emissions as can be seen in Figure 2.
1Error! Reference source not found. (Laurijssen, et al., 2010).
Figure 2. 1- Effect of recycling rate of paper on production energy and CO2 emissions.
The use of spent biomass as the feed source in the production of bio-oil may be considered
the needed compromise in the priority war between biomass as food or energy source. In
Costa Rica, the annual production rate for coffee alone is estimated to be around 2.05 tons of
60-kilogram bags in the year 2004 (Ricketts, et al., 2004). After use the spent coffee ground
still contains some lipids that when extracted is used in the production of bio-fuel. The amount
of lipids in the spent coffee grounds are relatively less than in the fresh coffee grounds,
however it is still useable for the production of bio-fuels (Vardon, et al., 2013). In Figure 2. 2
an illustration of the worldwide consumption of coffee in 2010 may be seen (Al-Hamamre, et
al., 2012).
Figure 2. 2- Coffee consumption worldwide in 2010.
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In 2008 a study was done by (Oliveira, et al., 2008) were the potential of coffee oil as a
feedstock for the production of biodiesel was experimented. Oil was extracted from a 25 kg
batch of fresh coffee beans by means of the Soxhlet extraction method with Hexane as
solvent. With healthy coffee beans it was determined that 81 percent of the bio-oil was
triglycerides, whereas with the defective coffee beans only 76 percent was determined to be
triglycerides. Thus, (Oliveira, et al., 2008) concluded that the use of coffee oil may be a
potential feedstock for alternatively produced diesel.
Biomasses may be use as an alternative transportation fuel due to the presence of
triglycerides and fatty acids within the biomass. According to (Demirbas, 2016), the
composition of the fatty acids, which are present within bio-oil, defines the total calorific value
of the bio-oil. For bio-oil, an average calorific value range of 24.29 to 41.20 MJ/kg may be
expected. A summary according to the study done by (Demirbas, 2016) of the calorific values
of various fatty acids are displayed in Table 2. 1.
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Table 2. 1- Recorded calorific values of fatty acids according to (Demirbas, 2016).
Fatty acid
2.3
Chemical
formula
Experimental
Unit
Butyric
C4H8O2
24.29 MJ/kg
Hexanoic
C6H12O2
29.76 MJ/kg
Caprylic
C8H16O2
33.04 MJ/kg
Decanoic
C10H20O2
35.18 MJ/kg
Lauric
C12H24O2
36.80 MJ/kg
Myristic
C14H28O2
37.97 MJ/kg
Palmitic
C16H32O2
38.80 MJ/kg
Stearic
C18H36O2
39.52 MJ/kg
Oleic
C18H34O2
39.02 MJ/kg
Linoleic
C18H32O2
38.32 MJ/kg
Linolenic
C18H30O2
37.57 MJ/kg
Arachidic
C20H40O2
40.15 MJ/kg
Arachidonic
C20H32O2
37.71 MJ/kg
Eicosapentaenoic C20H30O2
37.06 MJ/kg
Behenic
C22H44O2
40.67 MJ/kg
Erucic
C22H42O2
40.29 MJ/kg
Docosahexaenoic C22H32O2
37.30 MJ/kg
Lignoceric
41.14 MJ/kg
C24H48O2
Bio-oil Extraction Processes
As mentioned in section Renewable Feedstock, the extraction of bio-oil from spent coffee
grounds is thus plausible.
2.3.1 Supercritical CO2 Extraction
Supercritical carbon dioxide extraction is a method that is used for the extraction of bio-oil from
solid biomasses (Abbasi, et al., 2008). A container is filled with the desired biomass, while
liquid CO2 is pumped into the container, allowed to mix with the biomass. The liquid CO 2
carries oil molecules out of the biomass and transports the oil molecules to a separator where
CO2 and the oil is separated. The now CO2 gas is send to a condenser where it is condensed
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and recycled to the biomass container (Abbasi, et al., 2008). A study done by (Araujo & Sandi,
2007) concluded that supercritical extraction is an effective extraction method especially in the
case of using roasted coffee beans as biomass source. Although classic solvent extraction is
also declared an effective method, with supercritical extraction no organic solvents such as
Hexane is present in the extracted bio-oil.
2.3.2 Soxhlet Extraction
A Soxhlet apparatus may be used in an extraction process to obtain bio-oil from a biomass by
means of evaporation and condensation of the chosen solvent and allowing the solvent to
indirectly mix with the biomass (Al-Hamamre, et al., 2012). A sample size of the SCG is
measured and inserted into a thimble and is then inserted into the soxhlet extractor fitted with
a conical flask. A specified amount of polar or non-polar solvent is added to the flask and is
allowed to evaporate, condense, allowed to mix with the biomass to extract its bio-oil and then
be transported back to the starting flask without the presence of any biomass in the solventoil mixture.
Thus, the entire process is deemed as an indirect contact extraction process (Melo, et al.,
2014). It was concluded that the maximum oil yielded was 15.28% of the SCG biomass, which
was obtained by means of the non-polar solvent n-Hexane (Al-Hamamre, et al., 2012).
2.4
Renewable Diesel Processes
2.4.1 Hydrotreatment
Hydrotreatment is a catalytic petroleum producing process wherein stable hydrocarbons are
produced by means of hydrogenation of unsaturated hydrocarbons and thus removing
contaminating components such as oxygen, nitrogen, sulphur and metals namely nickel and
vanadium. This is done at high temperatures and pressures and by means of reacting with
hydrogen (Gary, et al., 2007). The chosen hydrotreating catalysts if firstly activated by means
heating the system in the presence of hydrogen sulphide at a specified pressure and
temperature. The bio-oil is then pumped to the reactor after activation of the catalyst where
hydrodesulphurisation (HDS), hydrodenitrogenation (HDN) and hydrodeoxygenation (HDO)
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takes place during the hydrotreating process. The main by-products that are formed includes
water, ammonia and hydrogen sulphide (Robinson & Samuel, 2006)
2.4.1.1
Reaction Kinetics
During hydrotreatment triglycerides, which are considered bio-oils, are deoxygenated through
any one or more reaction pathway namely hydrodeoxygenation, decarboxylation,
decarbonylation and hydrocracking (Mohammad, et al., 2013). Firstly, the double bonds of the
triglycerides are saturated to form single bonds during hydrogenation. Hydrogenation of
biomass, according to (Busetto, et al., 2011) is when triglycerides in the presence of a catalyst
are treated with hydrogen gas to saturate double carbon bonds to form single bonds. The
triglycerides are now hydrogenated triglycerides and still in the presence of hydrogen and a
catalyst, catalytic hydrocracking takes place wherein the long single bond triglycerides are
broken loose from the glycerol backbone of the triglyceride molecule (Anand & Sinha, 2012).
These shorter hydrocarbon molecules are known as free fatty acids and still have oxygen
bonds within the molecule. The presence in oxygen decreases potential energy within the fluid
as well as negatively affects the oxidation stability of the bio-fuel (Baskar & Kumar, 2017).
These oxygen atoms are released from the fatty acid through hydrodeoxygenation as water,
through decarboxylation as CO2 and through decarbonylation as CO. (Mohammad, et al.,
2013).
Hydrodeoxygenation results in the elimination of the oxygen bonds within the free fatty acid
and forms hydrocarbons with a chain length of the same magnitude as the number of carbons
as the free fatty acids, along with the byproducts of water and propane (Gary, et al., 2007).
Decarbonylation eliminates the oxygen bond, resulting in the formation of hydrocarbon chains
along with carbon monoxide and water as byproducts, whereas the same forms as a result of
decarboxylation only with carbon dioxide as a byproduct (Mohammad, et al., 2013). The
possible deoxygenation process pathways are illustrated in Figure 2. 3.
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Figure 2. 3- Deoxygenation pathways during hydrotreatment.
Due to the presence of three possible reactions that may take place, multiple studies have
been done to determine the dominance of these reactions mentioned above. These multiple
studies are discussed in section 2.4.1.6 where different reaction parameters are compared to
the obtained results. The dominance of the mentioned reactions will be determined by means
of the biomass feedstock, temperature and catalyst type used in the hydrotreating system
(Robinson & Samuel, 2006). It was concluded that in the production of hydrocarbons from
soya and gas oils in the presence of a NiMo-Al2O3 catalyst the hydrocarbons was diesel-like
of sort (Tiwari, et al., 2011). While under a temperature range of 350°C to 380°C,
decarboxylation and decarbonylation showed to be the dominant reaction pathway. According
to (Jęczmionek & Porzycka-Semczuk, 2014) while hydrotreating olive and corn oil concluded
that the decarboxylation and decarbonylation reactions depend on the on type of biomass
feedstock as well as the pressure of the system.
Depending on the reaction pathway that was dominant certain by-products such as propane,
carbon dioxide, carbon monoxide, etc. was produced. Additional side reactions may occur due
to the formed by-products. Methanation is a gas phase side reaction that produces methanol
and water due to reaction between the byproduct carbon dioxide or carbon monoxide and
hydrogen gas (Jęczmionek & Porzycka-Semczuk, 2014). Methanation side-reactions are
illustrated in Figure 2. 4.
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Figure 2. 4- Methanation side-reaction during hydrotreatment.
The formation of carbon dioxide and hydrogen gas due to the reaction between carbon
monoxide and water is also a side reaction during hydrotreatment. This side reaction is known
as the water-gas shift reaction (Veriansyah, et al., 2012). Due to these side reactions the
consumption of hydrogen gas is increased, thus complicating the gas product distribution
process and resulting in difficulty in predicting which reaction pathways will be followed.
2.4.1.2
Purging gas ratio
In order to form hydrocarbons with similar performance as that of diesel, oxygen must be
removed from the triglycerides during the hydrotreating process (Robinson & Samuel, 2006).
The system is purged with hydrogen sulfide to eliminate all oxygen present within the system
for
the
processes
hydrodesulphurisation
(HDS),
hydrodenitrogenation
(HDN)
and
hydrodeoxygenation (HDO) to occur (Mohammad, et al., 2013). It is thus during these
reactions where the oxygen within the triglycerides are removed. In order for the catalyst not
to be deactivated, a specific amount of hydrogen gas must be purged into the system. The
gas to oil ratio depends on the amount of hydrogen consumption, thus the gas to oil ratio must
be a minimal of four times the amount of hydrogen consumed (Gruia, 2006).
2.4.1.3
Reactor type
According to (Al-Dahhan, et al., 1997) the most widely used reactor for hydrotreating is the
trickle-bed reactor. Due to the trickle-bed reactors motionless of its catalyst bed, the Reynolds
number is significantly lower and thus the system may operate near a plug flow pattern. Thus,
this reactor is deemed superior to a slurry or fluidized bed reactors. A trickle-bed reactor may
be either a single-stage or a two-stage, wherein a two-stage sufficient amounts of hydrogen
sulfide is removed to effluent from the first stage prior to the effluent introduction to the
following stage (Tailleur, 2017). The trickle-bed reactor has a fixed catalyst bed with a
downward movement of a liquid and depending on if the reactor is co-current then the gas will
flow downward or counter-current where the gas will flow upwards (Mapiour, 2009).
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2.4.1.4
Hydrotreating Catalyst
As mentioned in the above sections, hydrotreatment is the deoxygenation, decarboxylation,
decarbonylation and hydrocracking of triglycerides or bio-oils in the presence of a catalyst to
produce a hydrocarbon diesel. A catalyst must be in its active state to perform efficiently and
consist of active sites, promoters and support (Gruia, 2006). The active component of a
catalyst is usually molybdenum that is promoted with nickel or cobalt, where a promoter is a
second metal other than the active metal. This promoter serves as a stabilizer and thus
increasing the overall catalyst activity (Mapiour, 2009). Depending on the desired product,
either nickel or cobalt will be the promoter. When denitrification is desired with the reduction
of aromatic contents then nickel is chosen as the promoter, whereas if desulphurization is
desired then cobalt is chosen (Senol, et al., 2005). Alumina is chosen as support to control
the dispersion of the promoter. This increases the average crystallite size of the promoter to
such an extent that it is greater than the average pore size (Esponoza, et al., 2009).
Catalyst deactivation is defined as the loss of catalytic activity over time due to catalytic decay,
coke deposition, metal deposition and sinking of the support (Bartholomew, 2001). Coke
formation reduces the accessibility of the catalyst’s active sites due to surface blockage. When
acidic and bifunctional catalysts are polyromantic and at high reaction temperatures,
carbonaceous deposits forms. These carbonaceous deposits are also known as coke (Guisnet
& Magnoux, 2001). Coke formation may be reduce by an increase hydrogen partial pressure
or is reversible by means of burning off the formed coke (Gruia, 2006). Metal deposition results
in pore blockage and thus can cause catalyst deactivation. Metals such as nickel and
vanadium that are found in petroleum feedstock are responsible for metal deposition
(Robinson & Samuel, 2006). Sintering, caused by high temperatures, is the collapse of the
catalyst pores, thus reducing surface area and resulting in catalytic deactivation (Gruia, 2006).
2.4.1.5
Environmental impact due to hydrotreatment
Air pollution is an attributing factor towards inflammation/oxidative stress and is associated
with various medical illnesses such as central nervous system effects, increased stroke
incidences, decreased cognitive functions ,Alzheimer’s and Parkinson’s disease (Levesque,
et al., 2011). By means of hydrotreating the contaminants concentrations that are present in
petroleum feedstock is removed or reduced. This is essential due to the possible threat of the
formation of pollutants such as sulfur monoxide and dioxide along with nitrogen monoxide and
dioxide (Mapiour, 2009). These pollutants may cause acid rain, eutrophication, haze, ozone
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depletion, crop and forest damage, global climate change and negative effects on animal and
marine life (Commonwealth of Massachusetts: Executive office of Energy and Enviromental
Affairs, 2012).
Due to Sulphur being one of the major contributors to pollution, regulations for the Sulphur
concentration present in petroleum or bio-fuel has been issued (United States Enviromental
Protection Agency, 2017). According to (United States Enviromental Protection Agency, 2017)
before EPA started to regulate diesel standards, Sulphur concentration in fuel was 5000 parts
per million (ppm), whereas since 2006 it is regulated at 15 ppm.
2.4.1.6
Reaction parameters
The reaction parameter has a direct influence on the product yield, reaction pathway and final
product quality during hydrotreatment (Robinson & Samuel, 2006). The biomass type that is
used as the petroleum feedstock influence the certain product quality of bio-fuel that will be
produced. Temperature and pressure are responsible for the saturation, along with the
breakdown of the fatty acids that are present within the biomass feed stock (Anand & Sinha,
2012). The catalyst, although not being a part of the reaction, lowers the needed activation
energy of the process and thus influencing the rate of reaction. The hydrogen is used to
saturate the hydrocarbons and due to specific side reactions that occur during the process, as
mentioned above, an excess amount of hydrogen is needed to ensure that the hydrogen is
not consumed completely during the side reactions (Mohammad, et al., 2013).
2.4.1.6.1
Temperature
Temperature is an important aspect during the hydrotreating reaction, thus the operating
temperature must be specifically set to obtain the desired product quality and conversion by
minimizing the temperature. This is done due to the exponential decrease in the catalytic
deactivation rate that high temperatures has on the catalyst (Gary, et al., 2007).
Temperature’s main effect on the hydrotreating process was on that of the product yield. It is
stated by (Bezergianni, et al., 2010) the yield of diesel product decreased in an increase of
temperature. The temperature was ranged between 330°C to 398°C with a steady decrease
in the diesel product yield. However, as the temperature increased yield percentage of
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gasoline yield increased, thus lighter molecules favour higher hydrotreating temperatures
(Bezergianni, et al., 2010).
By means of hydrotreating waste cooking oil, (Bezergianni, et al., 2010) concluded that the
formation of iso-parraffins are higher at increasing temperatures due to hydrocracking being
favoured at higher temperatures. The hydrotreatment of waste cooking oil resulted in to
conversion of triglycerides to C17 and C18 hydrocarbons. It was discovered that during the
hydrotreatment process the HDC reaction pathway was dominant over the HDO reaction
pathway by a factor of 3:1. It was recorded that the C18/C17 mass ratio decreased with an
increase of temperature, thus illustrating that HDO decreases as the temperature increases
for the hydrotreatment of waste cooking oil (Zhang, et al., 2014).
Heteroatom is any atoms excluding hydrogen and carbon such as sulphur, nitrogen, etc. and
these heteroatoms are present in most petroleum feedstock (Bezergianni, et al., 2010). As
mentioned in 2.4.1.4, the presence of these heteroatoms decrease the catalytic activity and
thus has negative effects on the produced product. According to (Bezergianni, et al., 2010)
the removal of sulphur from the feedstock were directly influenced by the hydrotreating
temperature. It was also concluded that with an increase of temperature the oxygen removal
increased along with the nitrogen detachment rate.
The hydrotreating temperature has a direct influence on the conversion of the process. Stated
by (Bezergianni, et al., 2010) with an increase of temperature the diesel fractions will
decrease, due to the cracking of heavy fractions into lighter fractions. The statement of
(Bezergianni, et al., 2010) is supported by (Sotelo-Boyas, et al., 2010) in his experiment with
rapeseed-oil, where he conclude that diesel yield decreases with an increase of temperature,
while the kerosene yield also increases.
2.4.1.6.2
Pressure
Pressurization of the reactor during hydrotreatment is a critical part of the process. It has a
strong effect on hydrogenation, isomerization and hydrocracking. The hydrotreating pressure
also influence the reaction pathway that the triglyceride will follow (Gruia, 2006). Hydrogen is
send into the reactor in excess to compensate for all possible reactions such as HDO, HDC
and side reaction mentioned in 2.4.1.1 . It was concluded by (Pindoria, et al., 1998) that with
an increase of pressure with a constant temperature and catalyst, die oxygen diffusion rate
within the reactor increase with pressure.
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The effect of hydrotreating pressure on the yield of diesel was done by (Bezergianni, et al.,
2011) and it was concluded that because the rate of hydrocracking increased as pressure
increased, the diesel production yield decreased. This is due to hydrocracking favouring higher
pressures and during hydrocracking heavy components are reduced to lighter components
(Sotelo-Boyas, et al., 2010). A similar experiment was done by (Srifa, et al., 2014) where he
produced biohydrogenated fuel from palm oil over a fixed bed reactor with a NiMoS2/γ-Al2O3
catalyst at a constant temperature of 300°C. He concluded that over a pressure range of 1.5
to 8 MPa the conversion rate was deemed incomplete at a pressure of 1.5MPa due to the
presence of palmitic and stearic acids in the product, where the HDO reaction pathway was
observed to be the dominant reaction at high pressures.
With a feedstock of C18 fatty acids, (Yang, et al., 2013) investigated the effect of hydrotreating
pressure on the conversion of the system. It was recorded that at a temperature of 380°C,
there was a 100% conversion of all fatty acids, however at lower temperatures it was noted
that the conversion increased with an increasing pressure.
2.4.1.6.3
Catalyst type
The catalyst choice is of utmost importance, due to the influence it has on the product quality
and compounds. The chosen catalyst will cause the saturation and breakage of double and
single carbon bonds, the removal of heteroatoms, cyclisation and isomerisation (Robinson &
Samuel, 2006).
A study by (Marafi, et al., 2006) was done to evaluate the effect of catalyst type on the
conversion and yield of the liquid product. Mo/Al2O3, which is a HDM catalyst, and Ni-Mo/
Al2O3, which is a HDS catalyst, were the two chosen hydrotreating catalyst. It was concluded
that the aromaticity and the degree of condensation of the polynuclear aromatic rings in the
product were higher in the Mo/Al2O3 catalyst compared to the Ni-Mo/ Al2O3 catalyst. In both
cases, the product oil became more purified and the asphaltenes present in the oil was
converted to saturate and resins.
In the effort of hydrotreating vegetable oils by means of using Pt/Zeolite and NiMo/Al 2O3 as
catalysts, liquid hydrocarbons mostly containing n-heptadecanes and n-octadecanes was
produced. Analysing the obtained results illustrated that the NiMo/ Al2O3 catalyst obtained a
higher liquid hydrocarbon yield in comparison to the Pt/Zeolite catalyst. This is due to the
NiMo/ Al2O3 catalyst promoting hydrocracking more effectively at lower temperatures and
pressures and its moderate acidity does not contribute to the iso-paraffins production. A better
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liquid hydrocarbon yield may be obtained from the Pt/Zeolite catalyst, but only at higher
severity (Sotelo-Boyas, et al., 2010).
(Kim, et al., 2013) hydrotreated soybean oil at various reaction parameters to recorded the
effect that said parameter has on the produced renewable diesel. Temperature, catalyst type
and pressure were the parameters that were changed. At a constant pressure and a
temperature range of 300°C to 440°C, the comparison between NiMo and CoMo catalysts
were analysed. It was recorded that at the presence of the Ni catalyst HDC was the dominate
reaction pathway, whereas HDO was the dominant pathway for the CoMo catalyst. Thus, the
conclusion was made that C-C scissions were more favourable with the transition metal
catalyst Ni, whereas C-O scissions were favourable with the CoMoSx catalyst.
2.4.1.6.4
2.4.1.6.4.1
Feedstock
Biomass Type
Normally chosen biomass feedstock’s has carbon atoms ranging from C14 to C20 with saturated
and unsaturated bonds alike. Hydrocarbons with one less or the same amount of carbon
atoms are produced by means of hydrotreating the chosen triglycerides (Robinson & Samuel,
2006). During hydrotreatment the reaction parameters, along with the catalyst will be
determined by the chosen feedstock biomass. This is due to the impurities within the feedstock
that will affect the rate of catalytic deactivation and the performance thereof. The feedstock
type will thus also determine the composition of the produced product by means of the
saturation level of the feedstock (Gruia, 2006).
In order to compare the effect of different biomass feedstock used during hydrotreatment,
(Han, et al., 2017) conducted a hydrotreating experiment using canola oil and used tire oil as
feedstock. It was concluded that with the canola oil the hydrogenation of the carbon double
bonds occurred predominantly, thus hydrocracking took place to form C18 and C17
hydrocarbons. However, it was recorded that when using the tire oil as feedstock, the
formation of C18 and C17 hydrocarbons decreased by 20%. It was thus further concluded that
tire oil, as feedstock is an excellent source for the production of naphthenics and aromatics,
whereas canola oil produced a higher yield of renewable diesel than the tire oil.
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A comparison was done between pure vegetable oil and a vegetable/heavy vacuum oil mixture
during hydrotreatment under a temperature range of 300°C to 450°C at a constant pressure
with a NiMo/ Al2O3 catalyst by (Huber, et al., 2007). It was recorded that produced renewable
diesel had 75% alkanes chains with a length of C15 to C18 when pure vegetable oil was used
the base feedstock, however this yield was improved to 87% when a sunflower oil mixed with
heavy vacuum oils were used as the base feedstock.
A same hydrotreatment biomass feedstock mixture experiment was done by (Sebos, et al.,
2009). Pure cottonseed oil was mixed with desulphurized petroleum diesel and was
hydrotreated at a constant pressure of 30 bar, in the presence of a CoMo/ Al2O3 hydrotreating
catalyst and in a temperature range of 305°C to 345°C. It was recorded that a triglyceride
conversion of 100% was obtained, due to added cetane numbers that the cottonseed oil has
added to the mixed feedstock.
2.4.1.6.4.2
Co-processing
As was mentioned above in section 2.4.1.6.1, there has been studies done on the coprocessing of both bio-oil and vacuum gas oils the evaluate a process’ feasibility. A study done
by (Lappas, et al., 2009) researched the effect of co-processing on the yield of bio-fuel
production. It was concluded that in the presence of the bio-oils, the production of gasoline
and diesel was favored although there was an increased on coke formation within the system.
It was further concluded that in the presence of sunflower oil, the inhibition of hydrocracking
conversion was recorded, however with this addition a better quality diesel may be produced.
(Jeczmionek & Porzycka-Semczukb, 2014) experimented the effect of co-processing different
vegetable oils, namely olive and corn oil, with a liquid paraffin on the heat effect of the system.
It was found that under a pressure range of 3 to 6 MPa, methanation was increased as 22
percent of the released carbon dioxide was converted to methane gas under 3 MPa pressure
and 27 percent was converted under 6 MPa pressure. It was concluded that the bio-oils
containing different triglycerides increased the total hydroconversion heat effect.
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2.5
Modern Hydrotreatment
As mentioned in section 2, due to the increasing threat of the depletion of fossil fuels the
attention of the world has severely increase on biomass as an alternative energy source.
Biomass as feedstock may be used for electrical generation, heating and transportation fuels
instead of the burning of fossil fuels that emits a large amount of polluting gasses. (Gruia,
2006). Hydrotreatment, which as mentioned in section 2.4.1 is the production of hydrocarbon
liquid fuel, which shares similar qualities with fossil petroleum diesel. Currently, the main
research focus of hydrotreatment is on a suitable feedstock and catalyst for the given process.
As mentioned in section 2.4.1.6.4Error! Reference source not found., experimentation on
he product quality and yield of several biomasses has been done and recently co-processing
of vegetable oils with produced petroleum feedstock is done to mitigate the blending quality
control of the feedstock. A recent study done by (Jensen, et al., 2016), through co-processing
created a new blend of bio-crude oil as feedstock for the hydrotreating process. The bio-crude
had a density of 970 kg/m3 with an element composition in weight percentage of 83.9 C, 10.4
H, 0.4 N, and 5.3 O at a temperature of 15.6°C. At 350°C, 95 bar and in the presence of a
NiMo/ Al2O3 catalyst it was recorded that exceptional HDO took place and a bio-feed with 0.3
weight percentage oxygen was obtained.
By means of fast pyrolysis (Gunawan, et al., 2013) produced bio-oil in a fixed-bed reactor at
a temperature of 500°C. In the presence of a Pd/C catalyst, the bio-oil was hydroprocessed
at 300°C to improve the quality of the oil further. The formation of propionic, butanoic and
pentanoic acids was recorded during the hydrotreating process, along with cycloalkanes and
certain alcohols that were hydrogenated into alkanes.
2.6
Hydrotreatment Problems
Hydrotreatment may be considered as a possible solution for the production of transportation
fuels to the arising fossil fuel depletion threat (Mikulec, et al., 2010). An issue with this solution
is the popular food versus energy debate that has been mentioned in section 2. This issue is
in favor of food due to the overall people in the world that are classified as undernourished is
approximated to be 1.02 billion people. Due to hunger and malnutrition approximately 6 million
children die each year, thus hunger is classified to be a major cause of death in the world (Nah
& Chau, 2015).
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For the production of renewable diesel, bio oils that are obtained from biomasses are required
where biomasses are considered a source of food. An alternative option for bio-oils are the
utilization of non-edible oils, however this results in another problem due to space and
resources that are needed for the growth of these oils (Ignaciuk, et al., 2006). Currently the
main focus for bio-oil used in the production of renewable diesel are non-edible of sorts and it
is discovered that corn stovers, micro-algal and jatropha are the most promising sources
(Mohammad, et al., 2013). Recently (Biswas, et al., 2017) by means of pyrolysis has used rice
straw, which is a recyclable biomass, to produce bio-oil and it was concluded that rice straw
may be a potential source for bio-oils. Alternatively, used biomasses have recently been used
to extract the remaining bio-oil that were still in the waste. (Phimsen, et al., 2016) has extracted
bio-oil from spent coffee grounds b means of using soxhlet extraction. It was concluded that
bio-oil from spent coffee grounds may be considered as a possible feedstock for the
production of renewable diesel due to a 13% yield that was obtained.
Another common problem with hydrotreatment is the deactivation thereof during catalytic
hydrotreatment. This is due to common catalysts such as NiMo and CoMo being a
presulphided catalyst and this contaminates the product with Sulphur (Tiwari, et al., 2011).
The catalyst deactivation rate is also increased due to the amount of oxygen in the triglycerides
that causes leaching on the surface of the catalyst (Sotelo-Boyas, et al., 2010).
2.7
Concluding Remarks
During the hydrotreating process the reaction parameter temperature, pressure, catalyst type
and biomass feedstock has a strong effect on the produced product yield and quality. By
means of using unsaturated feedstock more alkylbenzenes and cycloalkanes will be formed,
which results in shorter alkane chains in comparison with saturated feed stocks. The amount
of impurities within the feedstock must also be taking into consideration due to the negative
effect it has on the deactivation rate of the catalyst.
The reaction parameter temperature and pressure must be controlled strictly due to critical
environments having a negative effect on the quantity amount of diesel produced. This, as
mentioned in section 2.4.1.6.1 and 2.4.1.6.2, is due to hydrocracking being favored at higher
temperatures and pressures.
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The choice of these parameters must be considered crucially, due to the effect it has on the
amount of side reactions and reaction pathways it will cause. The composition of a catalyst is
critical, due to the effect it has on the reaction pathway that the reaction will follow. This is due
to its composition and its ability to control the amount of hydrotreating and hydrocracking that
will occur. The catalyst is also responsible for the amount of heteroatom removal and the feed
conversion. Thus, the quality and quant of the end product must always be considered in the
selection stages of the reaction parameters.
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3. EXPERIMENTAL METHOD
In this chapter, a brief description of the materials, methods and equipment that were used for
the extraction of bio-oil from SGC, along with the catalytic hydrotreatment of the extracted
coffee bio-oil is provided. A soxhlet extractor was utilised for the extraction of the bio-oil from
the SCG. A batch reactor was on the other hand utilised for the production of renewable diesel
at elevated pressures and temperatures from the extracted bio-oil. A description of the
materials and reagents used is provided in section 3.1, followed by the experimental setup of
the soxhlet extractor, along with the hydrotreating batch reactor in section 3.2 and section 3.3.
The analytical equipment and methodology thereof is provided in section 3.4.
3.1
Materials and Reagents
3.1.1 Materials
Spent coffee grounds were obtained from local coffee shops such as Stationary Coffee
Potchefstroom and Toro Potchefstroom. The collected SCG was then dried and stored in an
airtight container to avoid any moisture adsorption to occur.
The dried SCG were then utilized as the primary feedstock for the soxhlet extraction method
to obtain coffee bio-oil. The extracted coffee bio-oil was then also dried to eliminate any
presence of moisture. The extracted SCG bio-oil was then used as the secondary feedstock
in the hydrotreatment process for the production of renewable diesel.
Some properties of the gathered SCG from local coffee shops is shown in Table 3. 1.
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Table 3. 1- Properties of the SCG.
SCG
Value
Unit
Dry Matter
94.5
%
Ash
1.34
%
Protein (Nx6.25)
12.71
%
Fat (Ether extraction)
12.86
%
Carbohydrates
67.62
%
Neutral detergent fibre
66.11
%
Acid detergent fibre
31.14
%
Acid detergent lignin
11.88
%
Hemicellulose
34.97
%
Cellulose
19.26
%
Lignin
10.54
%
(calculated)
3.1.2 Gasses and chemicals
As mentioned in section 1.4, 2 hexane and methanol was used for the extraction of coffee biooil from the SCG. These 2 solvents were procured from ACE Chemicals, Johannesburg.
To obtain a close as possible oxygen-free atmosphere within the hydrotreating process,
nitrogen gas was used to purge the vessel. For the activation of the catalyst a mixture of
hydrogen sulfide and argon gas were used to pressurize the vessel. After the injection of the
coffee bio-oil, nitrogen and hydrogen gasses were used for the completion of the
hydrotreatment process.
The gasses used were produced and obtained from African Oxygen limited (Afrox). Additional
chemicals that were used during the preparation for analyses and used for optimal collection
of products are shown in Table 3. 2 along with the above mentioned chemicals and gasses.
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Table 3. 2- Gasses and chemical used during extraction of coffee bio-oil and hydrotreatment of coffee bio-oil
Component
Chemical formula
Supplier
Purity
Purpose
Nitrogen
N2
Afrox
99.99
Purging vessel
Hydrogen
H2
Afrox
99.99
Purging vessel
Reactant
Hydrogen
sulfide H2S + Ar
Afrox
and argon mixture
14.9 % volume H2S Catalyst activation
with balance of Ar
n-Hexane
C6H14
ACE
99.99
Solvent extraction
Methanol
CH3OH
ACE
99.99
Solvent extraction
Dichloromethane
CH2Cl2
ACE
99.99

Dilution of samples for
GC-MS analysis

Used
for
recovery
of
produced liquid product
from
hydrotreatment
reaction
Methyl nonanoate
CH3(CH2)7COOCH3
Sigma Aldrich
≥97
Internal
standard
for
GC
analysis of extracted bio-oil
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3.2
Soxhlet extraction
3.2.1 Experimental Setup
The extraction processes to obtain bio-oil from SCG were done within a soxhlet extractor. A
ball flask with a volume of 300 mL is connected to the bottom joint of the soxhlet extracted. A
semi-permanent thimble containing the dried SCG is place within the soxhlet extract. A
condenser is then placed on the top joint of the soxhlet extractor with 2 rubber tubes connected
to the condenser. The lower tube connection being the water inlet supply and the upper tube
connection being the water outlet. The completed connection of the soxhlet extractor is
clammed and placed inside a fume hood. A thermal pot containing sunflower oil is placed on
a heating mantel inside the hood. The soxhlet extractor is then place in the thermal pot,
submerging the ball flask in the oil.
The experimental setup is displayed in Figure 3. 1 and Figure 3. 2.
Figure 3. 1- Display of Soxhlet extractor set up.
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Figure 3. 2- Pictorial view of experimental setup within the wet bench
3.2.2 Experimental method
The experimental method for the extraction of coffee bio-oil is summarized in Figure 3. 3:
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Weight off 60 g of
SCG
Start timing the
reaction from the
first formation of a
condensate drop
Allow reaction to
occure for desired
time
Place weighted SCG
inside the thimble
Switch on the
heating mantel
Turn off heating
mantel
Measure 250 mL of
the desired solvent
Open the water
valve to allow the
flow of water through
the condenser
Remove bottom ball
flask containing
solvent and oil
mixture
Pour solvent into ball
flask
Connect soxhlet
apparatus as
explained in section
3.2.1
Evaporate solvent
Store bio-oil in dry
and cool place
Figure 3. 3- Summary of experimental extraction procedure.
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All equipment used for the preparation and setup of the soxhlet extractor was properly cleaned
and dried. 60 Grams dried SCG is weight and placed inside the thimble. 250 mL of the desired
solvent that is used for the extraction process is measured and poured into the bottom ball
flask. After the introduction of the SCG and solvent into the soxhlet apparatus, the
experimental setup as mentioned in section 3.2.1 is now implemented.
The water valve that is connected to the condenser is opened slightly to ensure a slow flow of
cool water through the condenser. The heating mantel is switch on at the power source.
As the temperature of the oil in the thermal pot starts to rise, the solvent in the ball flask also
starts to rise. When the solvent’s boiling point is reached, the solvent start to evaporate inside
the soxhlet extractor. The evaporated solvent starts to form condensate at the bottom of the
condenser and the condensate will then drip down into the thimble.
As more evaporated solvent condenses in the soxhlet extractor, the liquid level will rise
submerging the thimble. When the liquid level within the soxhlet extractor rises above the
highest level of the siphon arm, the solvent/oil mixture within the soxhlet extractor is drained
into the bottom ball flask.
As the thimble is being submerged in the condensed solvent, the solvents extracts the bio-oil
from the SCG and the extracted bio-oil is then drained back with the solvent into the ball flask.
The soxhlet extraction process is deemed as a continuous process and thus a specific process
time frame should be given.
Once the extraction process is deemed complete, the ball flask is removed from the soxhlet
apparatus and the solvent/oil mixture is then placed in a rotary evaporator as shown in Figure
3. 4.
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Figure 3. 4- Rotary evaporator apparatus.
In the rotary evaporator, a vacuum is drawn and the component with the lowest boiling point
evaporates, condenses and collects in a separate flask. Hence, the solvent and the extracted
bio-oil is successfully separated from one another.
The collected solvent is placed in a recycle container, whereas the bio-oil is weighted, dried
in an oven to remove additional moisture from the oil and stored in an air tight container for
further use.
3.3
Hydrotreatment process
3.3.1 Experimental setup
A high pressure autoclave type vessel/reactor manufactured from stainless steel 316 is used
for the hydrotreatment process. The vessel/reactor has a height of 12 cm, an inner diameter
of 5 cm and a wall thickness of 2 cm. The vessel/reactor is placed inside a heating jacket and
is equipped with a thermocouple for effective temperature control. For safety, the
vessel/reactor is equipped with a pressure relieve valve at a pressure of 150 bar and a
pressure gauge to assist with pressure control. For effective mixing within the reactor after the
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insertion of the catalyst and bio-oil, a magnetic coupled stirrer is equipped on top of the
vessel/reactor.
The vessel/reactor consists of 2 parts, the top part equipped with the magnetic coupled stirrer,
gas inlets and solvent/oil inlet valve and a bottom section consisting of as described above
with a working volume of 350 mL. The top and bottom section is connected with a copper
insulation gasket for effective pressure sealing. To ensure optimal pressure sealing and zero
gas leakage the 2 sections are screwed together.
The experimental setup of the hydrotreating reactor is shown in Figure 3. 5:
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Figure 3. 5- Pictorial view of the hydrotreating reactor after complete setup.
3.3.2 Experimental method
The experimental method for the hydrotreatment of the extracted coffee bio-oil for the
production of renewable diesel is summarized in Figure 3. 6:
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Weigh off 4 g of the
desired
experimantal
catalyst
Heat vessel to
400°C
Keep vessel at
400°C for 1 hr
Keep vessel at
desired
experimental
temperature for 1 hr
Insert weighted
catalyst into reactor
cup
Test for gas leakage
Allow vessel to cool
down to room
temperature
Heat up vessel to
desired
experimental
temperature
Setup reactor as
mentioned in
section 3.3.1
Pressurize vessel to
30 bar with H2S +
Ar
Depressurize vessel
Pressurize vessel to
90 bar with H2
Pressurize vessel
with nitrogen
Replace gas stream
from N2 with H2S +
Ar
Insert 40 g of bio-oil
into vessel
Test for gas leakage
Test for gas leakage
Purge vessel for 30
min with nitrogen
Purge vessel with
N2 for 30 min
Purge vessel with
H2 for 5 min
Allow vessel to cool
down to room
temperature
Figure 3. 6- Summary of hydrotreatment experimental process.
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All of the apparatus used and mentioned in section Error! Reference source not found. is
roperly cleaned and dried prior to the start of the experimental run. An amount of 4 g of the
desired experimental catalyst for the specific run is weighted off using a 3 decimal scale. The
weighted catalyst is placed inside the reactor cup and is then fitted into the bottom section of
the vessel. The top section of the reactor is now fitted and bolted onto the bottom section an
adjustable wrench.
Ensuring that the outlet gas valve of the vessel is closed, the inlet nitrogen valve is opened
and allowed to pressurize the vessel. By means of using a liquid leak detecting fluid the vessel
is tested for any gas leaks. If a gas leak is detected the vessel is depressurized to repair the
leak. If no gas leakages are detected the vessel is purged with nitrogen for 30 minutes to
eliminate all oxygen that is present within the vessel. After purging the outlet gas valve of the
vessel is closed along with the inlet nitrogen gas valve. The vessel is ten depressurized to a
pressure in the range of 1.1 bar to 1.5 bar. The inlet hydrogen sulphide/argon gas valve is now
opened and allowed to enter the vessel. To ensure all N2 gas within the vessel is eliminated,
the H2S/ Ar gas is allowed to be purged through the system for a brief period.
The vessel is then pressurized to 30 bar with the H2S/ Ar and is then heated to a temperature
of 400 °C. After reaching the desired temperature, the vessel temperature is maintained at
400 °C for a time frame of 1 hour for the activation of the catalyst. After the time frame the
vessel is allowed to cool down to room temperature.
The vessel is then depressurized to just above atmospheric pressure for the insertion of the
extracted coffee bio-oil. The bio-oil is then injected into the system by means of using a large
injection syringe. The vessel is once again purged with N2 for 20 minutes to eliminate any
oxygen that might have entered during the introduction of the oil. Next, the vessel is purged
with H2 gas for 5 minutes to eliminate all N2. The vessel is then pressurized with H2 gas at 90
bar.
The vessel is then heated to the desired experimental temperature and is maintained at that
temperature for 1 hour. After 1 hour, the vessel is allowed to be cooled down to room
temperature.
The produced liquid product is then removed from the vessel to be analysed. The removal of
the liquid product is displayed in Figure 3. 7 and the clean liquid product is displayed in Figure
3.8.
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Figure 3. 7- Pictorial display of the removal of the produced hydrotreatment liquid product.
Figure 3. 8- Pictorial display of produced clean liquid product.
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3.4
Analytical equipment and methodology
3.4.1 Oil extracted yield
The yield for the extracted coffee bio-oil from SCG is calculated by measuring the weight of
the dried SCG that has been used for the soxhlet extraction experiment, along with the weight
of the bio-oil that has been extracted. The extracted bio-oil yield from dried SCG was
calculated by using equation 1.
Soxhlet extraction yield =
weight of the extracted bio−oil
weight of the dried SCG
(1)
3.4.2 Produced Hydrotreatment Liquid product yield
As mentioned in section 3.3.2, after the completion of the hydrotreatment process the total
liquid product produced has been divided into a clean and dirty part. The clean liquid product
being the uncontaminated produced liquid within the vessel cup. This clean liquid product is
filtered by means of using a Buchner funnel to separate the produced liquid product from the
used catalyst. After the completion of the filtration, the clean liquid product is then placed in
an airtight container and is weighted.
The used apparatus during the hydrotreatment process is then rinsed with dichloromethane
to recycle and collect any liquid product that may have remained within the vessel cup, in the
vessel bottom section and on the electrical stirrer. The liquid product/Dichloromethane mixture
is then also filtered by means of a Buchner funnel to separate the liquid from the solid catalyst.
The liquid mixture is then heated for the total evaporation of all Dichloromethane present in
the mixture. The remaining liquid is then weighted and is labeled as the dirty liquid product.
For the calculation of the liquid product yield, equation 2 was used.
Liquid product yield =
( clean liquid product weight) + ( dirty liquid product weight)
Injected coffee oil weight
(2)
The calculated liquid product yield does not describe the conversion of the extracted bio-oil to
valuable renewable diesel, but describes the efficiency of the process by indicating the amount
of gas that has been produced.
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3.4.3 Triglycerides analysis
For the production of renewable diesel the feedstock, which in this case is the extracted coffee
bio-oil, contains a certain amount of free fatty acids and triglycerides. For this, an Agilent
7890A GC has been used to determine the amount of triglycerides present in the extracted
coffee bio-oil. The test method EN 14103 has been followed for this analysis and the
requirements thereof is the derivatization of the triglycerides to convert it to fatty acid methyl
esters. Afterwards the weight distribution of the fatty acid methyl ester was determined.
For the GC to analyze the methyl esters, an internal standard prior to the analyses is required.
A sample volume of 100 µL of the extracted coffee bio-oil has been placed into a sample vial
containing 100 µL of tri-methylsulphonium hydroxide solution (TMSH), 900 µL of iso-octane
and 400 µL of dichloromethane. Due to the high viscosity of the bio-oil an additional 100 µL of
the extraction solvent that was used for the monster bio-oil sample was added to reduce its
viscosity. The mixture within the sample vial is then vortexed followed by the addition of the
internal standard to the mixture, which in this case was methyl nonanoate. The mixture is then
analysed using the GC apparatus.
3.4.4 Bomb Calorimeter
For the analyses of the energy value of the extracted coffee bio-oil, a MC-1000, Mk 2 Modular
Calorimeter has been used. A sample of the extracted bio-oil and produced hydrotreated liquid
product were loaded respectively into the bomb calorimeter, where after the ignition of the
sample the temperature increase was measured. By means of using relevant software, the
temperature increase was converted into an energy content (MJ) per kilogram of sample. The
used bomb calorimeter is displayed in Figure 3. 9.
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Figure 3. 9- Pictorial view of the Bomb Calorimeter.
3.4.5 GC-MS
The produced clean liquid product, as mentioned in section 3.3.2, has been filtered and
qualified using the GC-MS located at the laboratory of the School of Chemical and Mineral
Engineering of the North-West University, Potchefstroom Campus. The GC-MS may be further
defined as an Agilent 7890A, 5975C inert MSD with triple axis detector, fitted with an Ht V5
column.
A 100 µL sample of the produced clean liquid product was placed in a sample vial and diluted
with 1000 µL of dichloromethane. The mixture is then inserted into the GC-MS for analyses.
The differences in boiling points of known n-alkanes is used in this analyses process as the
temperature increases. According to (Bachler, et al., 2010), the GC-MS is calibrated
accordingly to the method based on ASTM_Standard_D7213 by means of alkanes from C8 to
C40 being used as calibration standards. A simulated distillation (SimDist) curve for the
samples has been compiled to characterise the sample by means of its boiling point ranges.
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The calibration procedure for the GC is displayed in Appendix E- Analytical results under
Method for GC-MS analysis, along with the constructed simulated distillation curves. The GCMS used is shown in Figure 3. 10.
Figure 3. 10- Pictorial view of the GC-MS.
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3.4.6 ICP-OES Analysis
An Agilent Technologies 700 Series ICP-OES was used to determine the concentrations,
measured in parts per million (PPM), of the metals present within the extracted coffee bio-oil
as well as the sulphur content present in the produced liquid product obtained from
hydrotreatment. An inductively coupled plasma optical emission spectrometry (ICP-OES) is a
powerful analytical technique used to determine trace elements of myriad of samples types.
The ICP-OES combines a photodetector, along with a wavelength selection device at high
temperatures to identify the concentration of elements that are present in a sample (Suleiman,
et al., 2009).
To prepare the sample for the ICP-OES analysis, a monster sample of 1 mL was measured
and diluted to a 1 to 10 solution. The prepared sample was then loaded into the ICP-OES
machine. The ICP-OES analytical machine used is shown in Figure 3. 11.
Figure 3. 11- Pictorial view of the ICP-OES machine.
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3.4.7 Eralystics ERAFLASH
For the measurement of the flashpoint of the produced renewable diesel, an Eralystics ER 01
ERAFLASH was used. Using a pipette, the renewable diesel sample was filled up to the mark
in the cup of the ERAFLASH. The filled cup was then inserted into the ERAFLASH through
the front door of the instrument. The analysis took place after labelling the sample onto the
screen of the instrument. The ERAFLASH has a temperature range of 25 to 200 °C and an
analytical time of 15 to 20 minutes. The Eralystics ERAFLASH used for the analysis is
displayed in Figure 3. 12.
Figure 3. 12- Pictorial view of the ERAFLASH.
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3.4.8 Cloud point
For measuring the cloud points of the renewable diesel, a modified analytical setup is done. A
metal pot is filled with ice and water for the creation of an ice bath. A sample of the renewable
diesel is inserted into a glass vial and submerged into the ice bath. A thermocouple is inserted
into the renewable diesel sample to measure the temperature.
As the temperature decreases, the vial containing the renewable diesel sample was removed
from the ice bath and inspected thoroughly. For a rough estimation of the cloud point of the
sample, the temperature at which crystallization of the sample occurs is recorded. The
analysis is displayed in Figure 3. 13.
Figure 3. 13- Pictorial view of the cloud point analyses.
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4. RESULTS AND DISCUSSION
In this chapter, the results that were obtained from experiments are presented. The extraction
process of the oil from SCG is discussed in section 4.1 and the hydrotreatment of the extracted
oil is discussed in section 4.2. The hydrotreatment in the presence of a NiMo catalyst is
presented in section 4.2.1 and in the presence of a CoMo catalyst in section 4.2.2. The two
catalysts were compared in section 4.2.3. The most appropriate liquid product as mentioned
in section 4.2.3 is compared to the diesel standards according to the (SANS 342:Edition 5,
2014) in section 4.2.4.
4.1
Oil extraction from SCG
4.1.1 Effect of solvent used for extraction process on the bio-oil yield
A soxhlet apparatus was used for the extraction of bio-oil from a SCG feedstock to be used
as feedstock for the production of liquid fuel. A minimal number of 3 extractions has been done
with each of the chosen solvent as mentioned in section 0. This has been done to obtain an
average oil extraction yield, as shown in Figure 4. 1.
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20
18
16.09
Extraction yield (%)
16
14
12
10
8
5.81
6
4
2
0
Average extraction yield (%)
n-Hexane
Methanol
Figure 4. 1- Average extraction yield calculated for desired solvent.
It is recorded from Figure 4. 1 that by using n-Hexane (non-polar solvent) as the extraction
solvent during the soxhlet extraction process, the highest extracted bio-oil yield is obtained.
According to (Mwabueze & Okocha, 2008), this may be due to the lack of an O-H end that
would interfere with the extraction process. It is further stated by (Al-Hamamre, et al., 2012)
that due to the low charges that the non-polar solvent carries, the solvent is able to penetrate
into the matrix of the feed. This is due to the extraction process being based on Van der Waals
forces and due to the higher hydrogen bonds that polar components contain, this makes the
penetrating process into the feed matrix more difficult. Another possibility is due to the polarity
difference of the solvents, different bio-oils may be extracted. When a non-polar hexane
solvent is used, a higher amount of triglycerides is extracted from the biomass due to their
composition. In the case of a polar methanol solvent, the extraction of the cracked free fatty
acids present in the biomass is extracted. Due to a higher yield recorded form the use of the
non-polar hexane, a conclusion may be made that the amount of triglycerides are
exponentially higher than the free fatty acids in the biomass.
The recorded average oil extraction yield of 16.09 % is higher than the maximum yield of 15.28
% in the study done by (Al-Hamamre, et al., 2012), but lower than the maximum yield of 52.83
% in a study done by (Araujo & Sandi, 2007). In the cause of the study done by (Araujo &
Sandi, 2007), a fresh source of coffee beans are used which entail a higher percentage oil
content in comparison with a SCG feed source. According to (Al-Hamamre, et al., 2012), the
different brewing methods that has been practised on the coffee ground has a direct influence
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on the quality and quantity of the SCG. This may be a reason for the difference in the extraction
yield obtained from the study done by (Al-Hamamre, et al., 2012) and the data that has been
recorded in Figure 4. 1.
To extract sufficient amounts of oil from SCG for hydro-processing experimental work, nhexane has been chosen as the extraction solvent as it yields more oil compared to methanol.
The bio-oil yield for the remaining extraction runs using n-hexane as the solvent on a dry
weight basis was between 12.1 % and 17.55 %. A total of 821.907 g of coffee bio-oil has been
extracted from the SCG.
4.1.2 Effect of solvent used for extraction process on the bio-oil
composition
For the study of the effect that different extraction solvents has on the composition of the
extracted bio-oil, a GC-FAME has been used to characterize the qualitative and quantitate
values of the fatty acids present in the extracted coffee bio-oil as mention in section 3.4.3. The
extracted bio-oils has been derivatized for the total breakdown of all fatty acids that were still
attached on a glycerol base and the free fatty acids were then recorded by the GC-FAME
analytical machine. A summary of the main free fatty acids present within the extracted coffee
bio-oil is shown in Figure 4. 2.
16.000
13.853
Weight percentage
14.000
12.000
10.000
8.140
8.000
6.000
3.474
4.000
1.947
2.000
0.000
C16:0
C18:0
C18:1
C18:2
Free fatty acids
Hexane
Methanol
Figure 4. 2- Quantitative results of free fatty acids present in bio-oil extracted by means of different solvents.
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The most occurring free fatty acid in terms of weight percentage has been recorded as C16:0
or palmitic acid. The presence of C18:1 or oleic acid is also recorded in Figure 4. 2. The
weight percentage calculation may be seen in Appendix A- SCG extraction calculation under
Calculation of weight percentage of FFA present in the extracted SCG bio-oil.
It is also shown that a higher weight percentage of free fatty acids has been recorded when
methanol was used as the extraction solvent. According to (Al-Hamamre, et al., 2012), the
higher percentage of free fatty acids (FFA) that are present in the bio-oil extracted with a polar
methanol solvent may have negative implications with further experimentation with that oil.
The higher percentage of FFA’s increases the oxidation rate of the oil and thus reduces the
overall stability of the oil and increases its degradation. The high amounts of FFA’s also may
form high amounts of unwanted soap by-products during catalytic reactions. A linear model
with the increase of FFA’s may describe the increase of viscosity, as stated by (Mwabueze &
Okocha, 2008).
Due to the hexane solvent obtaining the lowest amount of FFA’s, it contains a greater average
length of fatty acid carbon chains on the glycerol and the ester amount has a stoichiometric
lower percentage (Al-Hamamre, et al., 2012). An additional explanation for the higher weight
yield obtained from the non-polar solvent in comparison to the polar solvent may be the lower
amount of FFA’s present in its composition. According to (Al-Hamamre, et al., 2012), the
formation of complexes between the fatty acids and carbohydrate breakdown components
may be the result for the lower weight yield obtained from the polar solvent during the
extraction process.
4.1.3 Effect of solvent used for extraction process on the bio-oil calorific
value
As mentioned in section 4.1.1, due to the differences of the solvent’s electrical charges the
extraction process yields will differ. Along with the difference in yield percentages, the energy
values of the extracted bio-oils may also differ with a change in solvent compositions. A bomb
calorific analysis has been done on the extracted bio-oils from both possible solvent
components. The calorific values of the extracted bio-oils may be seen in Figure 4. 3.
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39.500
38.628
Calorific value (MJ/kg)
39.000
38.500
37.350
38.000
37.500
37.000
36.500
36.000
35.500
35.000
Hexane
Methanol
Solvents
Figure 4. 3- Calorific values of extracted bio-oils from different extraction solvents.
As can be seen from Figure 4. 3, a slightly higher gross calorific value is recorded for the biooil extracted with n-Hexane as solvent. However, due to both the obtained calorific values
being in the experimental error margin, both may be classified as equal.
The high calorific values of the obtained coffee bio-oils may be due to the higher quantity of
palmitic acids that are present. It may be seen in section 2.2, Table 2. 1, that the obtained
calorific values are more in the range of the palmitic fatty acid’s recorded calorific value.
4.2
Hydrotreatment of oil extracted from spent coffee grounds
4.2.1 Ni/Mo hydrotreating catalyst
4.2.1.1 Effect of temperature on the feed conversion
For the calculation of the conversion from SCG bio-oil to liquid product fuel, a simulation
distillation data was employed. Feed conversion has been defined as the mass of the
extracted SCG bio-oil that has been converted into liquid fuel with a boiling range of below
370°C.
A display of the repeated experimental procedures at a temperature of 390 °C to determine
the experimental error is shown in Figure 4. 4.
47
Feed conversion (%)
School of Chemical and Minerals Engineering
99.60%
99.40%
99.20%
99.00%
98.80%
98.60%
98.40%
98.20%
98.00%
97.80%
97.60%
99.43%
99.00%
98.34%
390
390
Temperature (°C)
390
Figure 4. 4- Hydrotreating experimental repeats at a temperature of 390 °C in the presence of NiMo/Al2O3.
As shown in Figure 4. 4, different values in terms of the feed conversions for each experiment
has been recorded. These values were used for the calculation of the experimental errors in
Figure 4. 5 below. The calculations for the experimental errors is shown in Appendix A- SCG
extraction calculation under Experimental error calculation for calorific values.
A display of the effect of temperature on the bio-oil conversion over a NiMo/Al2O3 catalyst at
a constant pressure is shown in Figure 4. 5.
100.00%
99.43%
99.36%
Feed convertion (%)
99.50%
98.64%
99.00%
98.50%
98.04%
98.00%
97.50%
97.00%
96.50%
350
370
390
Temperature (°C)
410
Figure 4. 5- Effect of temperature on the feed conversion in the presence of NiMo/Al2O3.
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It is recorded from Figure 4. 5 that the feed conversion of each hydrotreatment process at
different reaction temperatures may be allocated as follows; 390°C > 410°C > 370°C > 350°C.
Thus, a temperature of 390°C is recorded as the most appropriate temperature for the
maximum feed conversion for this experimental setup, whereas a temperature of 350°C is
recorded as the lowest. The constant increase of the conversion from a temperature of 350
°C to 390 °C is due to both the decarboxylation and decarbonylation reaction becoming the
more dominant reactions (Veriansyah, et al., 2012). The decrease of the conversion from a
temperature of 390 °C to 410 °C is according to (Kim, et al., 2013), due to the increased
production of water. During hydrotreating, the water gas shift reaction possibly contributes to
the production of water which result in the poisoning and finally the deactivation of the catalyst
and therefore a decrease in the feed conversion.
As can be noted in Figure 4. 5, the obtained feed conversion values at temperatures of both
390 °C and 410 °C falls within the experimental error margin. Thus, an absolute conclusion
regarding the most appropriate temperature for this experimental setup in terms of feed
conversion cannot be verified.
.
4.2.1.2 Effect of temperature on the liquid product composition
As stated by (Krar, et al., 2010), during the hydrotreating process various side reactions may
occur over the catalyst. The side reactions that may occur result in the formation of isomers,
olefins, aromatic compounds and cyclic compounds. The effect of various reaction
temperatures on the produced liquid fuel is displayed in Figure 4. 6.
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100%
Liquid composition
100%
99%
99%
98%
98%
97%
97%
96%
350
n-Alkanes
370
Iso-alkanes
Olefins
390
390
Temperature (°C)
Aromatics
390
Cyclic compounds
410
Oxygenate
Figure 4. 6- Temperature effect on liquid product composition in the presence of a NiMo/Al2O3 catalyst.
It may is noted from Figure 4. 6 that with an increase of temperature, there is a decrease in
the total percentage of n-alkanes present in the liquid fuel. The explanation thereof may be
due to hydrocracking taking place at higher temperatures, thus the heavier molecules are
cracked into lighter compounds (Khethane, 2016). With a decrease of n-alkanes, an increase
of iso-alkanes is also recorded. This addition is beneficial with the cold plug flow properties of
the produced liquid fuel, however due to a lack of sufficient iso-alkanes the produced liquid
fuel did not flow easily at temperature lower than 12°C, as can be seen below in section 4.2.4.
The presence of the unconverted oxygenates in the liquid product will lead to a lower oxidative
stability and lower calorific value. As can be seen in Figure 4. 6, the remaining oxygenates
from the hydrotreatment process are lower than 1% of the total liquid product mass and may
be deemed neglectable. It is also recorded that the percentage oxygenates present in the
liquid fuel decrease with an increase in reaction temperature. This is a result of an increase in
the efficiency of the hydrotreatment process with an increase of temperature leading to a better
conversion. As the reaction temperature increase, the deoxygenation reactions, namely
decarboxylation, decarbonylation and hydro deoxygenation starts to occur at a higher rate
(Tiwari, et al., 2011).
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4.2.1.3 Effect of temperature on the liquid product yield
A simple mass equation, as shown in section 3.4.2, has been used to calculate the total liquid
product yield. To calculate the experimental error in terms of liquid yields a repeat of the
hydrotreating process was done at a temperature of 390 °C. This temperature was chosen
due to the fact that it produced the highest diesel fuel yield and lower by-products, as can be
seen in section 4.2.1.5. A display of the experimental error is shown in Figure 4. 7 and Figure
4. 8.
36.00
34.80
Liquid product produced (g)
35.00
33.70
34.00
33.00
32.00
31.00
30.90
30.00
29.00
28.00
390
390
Temperature (°C)
390
Figure 4. 7- Hydrotreating experimental repeats at a temperature of 390 °C in the presence of NiMo/Al2O3.
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88.00
86.74
86.00
83.84
Yield percentage
84.00
82.00
80.00
78.00
77.66
76.00
74.00
72.00
390
390
Temperature (°C)
390
Figure 4. 8- Hydrotreating experimental repeats at a temperature of 390 °C in the presence of NiMo/Al2O3.
It is recorded in Figure 4. 7 that a liquid yield increase has occurred. This may be due to the
more perfect experimental producer has been followed in terms of human error.
The hydrotreating process yields and amount of liquid fuel produced is displayed in Figure 4.
9 and Figure 4. 10.
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40.00
Liquid product produced (g)
35.00
33.70
32.50
34.80
30.90
31.10
29.50
30.00
25.00
20.00
15.00
10.00
5.00
0.00
350
370
390
390
Temperature (°C)
390
410
Figure 4. 9- Liquid product produced in the presence of NiMo/Al2O3.
100.00
90.00
83.84
80.80
Yuield percentage
80.00
86.74
77.66
77.53
73.63
70.00
60.00
50.00
40.00
30.00
20.00
10.00
0.00
350
370
390
390
Temperature (°C)
390
410
Figure 4. 10- Liquid product weight yield in the presence of NiMo/Al2O3.
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The highest recorded liquid yield, as can be seen in Figure 4. 9 and Figure 4. 10, is recorded
as 86.74 % at a temperature of 390 °C. A liquid product yield decrease that is recorded as the
temperature increases from 390 °C to 410 °C is due to the occurrence of cracking. Cracking
is favoured at higher temperatures and results in the formation of lighter components, thus
increasing the gas yield and lowering the liquid yield.
As can be seen in Figure 4. 10, all of the obtained liquid product mass yields fall in the
experimental error margin, thus a temperature at which optimal liquid yield may be produced
cannot be verified. However, at a temperature of 370 °C and 410 °C a liquid yield below the
experimental error margin is recorded and thus may be classified as the worst performing
temperatures in terms of liquid yield.
4.2.1.4 Effect of temperature on the liquid product calorific value
Due to the oxygen molecules present within the bio-diesel composition, the calorific value will
be significantly lower than that of diesel which contains no oxygen molecule in its composition.
To analyse the efficiency of the hydrotreating process, a bomb calorific meter has been used
to record the produced liquid fuel’s calorific energy values at different temperature ranges.
The calorific values for the obtained liquid fuels at various temperature ranges are displayed
in Figure 4. 11.
47.000
46.146
Calorific value (MJ/kg)
46.500
46.000
45.000
45.500
45.000
45.023
44.295
44.500
44.000
43.500
43.000
42.500
350
370
390
Temperature (°C)
410
Figure 4. 11- Calorific values of liquid products at different temperatures in the presence of NiMo/Al2O3.
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As can be seen in Figure 4. 11, the calorific values of each hydrotreating process at different
temperature may be allocated as follow; 390 °C > 410 °C > 370 °C > 350 °C. A number of 3
repeats have been done on the bomb calorific meter to establish an experimental error. By
means of using this obtained data and standard deviation, an error bar has been added to
Figure 4. 11 for the deployment of the recorded experimental error. The calculation of the
experimental error may be seen in Appendix C- Calculations of hydrotreated SCG bio-oil in
the presence of both NiMo/Al2O3 and CoMo/Al2O3 under Experimental error calculation for
calorific values.
It is recorded that with an increase of temperature, an increase in the calorific value also
occurs. This is due to a higher amount of oxygenates present in the liquid product at lower
reaction temperature, and thus lowering the calorific value of the liquid fuel (Ramadhas, et al.,
2005). However, the highest recorded calorific value was recorded at a temperature of 390
°C. Due to the high value obtained, it was recorded outside the experimental error margin and
may thus be established as the most appropriate temperature in terms of caloric values.
This is due to a higher rate of n-alkanes in the liquid composition of the 390 °C liquid fuel in
compassion with the 410 °C liquid fuel, as can be seen in section 4.2.1.2. According to
(Sivasankar, 2008), n-alkanes has a significantly higher ignition quality and thus a higher
calorific value than iso-alkanes.
The obtained calorific values in the presence of NiMo/Al2O3 may be an indication of the
effectiveness of the hydrotreatment process. As can be seen in section 4.1.3, Figure 4. 3, the
calorific value from the feed source to the liquid product has increased significantly. This may
be an indication of successful deoxygenation, as the presence of oxygen molecules causes a
lower calorific values of a component.
4.2.1.5 Effect of temperature on the fuel yield
The fuel yields for the produced liquid product has been studied at a series of different reaction
temperatures. In this study it has been defined that naphtha has a boiling range between 75
°C to 150 °C, kerosene has a boiling range between 150 °C to 240 °C and diesel has a boiling
range between 240 °C to 370 °C according to the National Petroleum Refiners of South Africa
(NatRef). The effect of temperature on the liquid fuel boiling range distribution is displayed in
Figure 4. 12.
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School of Chemical and Minerals Engineering
0.008
0.007
0.019
0.024
Heavy Fuel Oils
0.9714
0.9758
0.9687
0.9671
Diesel
Keroseen
0.011
0.0091
0.0068
0.0044
Naphtha
0.0095
0.0078
0.006
0.0042
0
0.2
0.4
0.6
0.8
1
Selectivity
410
390
370
350
Figure 4. 12- The temperature effect on the liquid fuel boiling range distribution from hydrotreated coffee bio-oil in
the presence of NiMo/Al2O3.
It is obtained that the most appropriate temperature, which resulted in the highest diesel
selectivity from a coffee bio-oil feedstock for this experimental setup, is at 390 °C. A steady
increase in the production of naphtha is recorded with an increase in the reaction temperature.
A similar observation is made for the kerosene, as the production rate increases with an
increase in temperature. This is typically due to hydrocracking tacking place at higher
temperatures, cracking the heavy diesel molecules into lighter components.
The diesel selectivity’s at different temperatures differs slightly, where a steady incline is
recorded. The selectivity of diesel at a temperature of 410 °C slightly decreases, due to a
higher amount of hydrocracking taking place as mentioned above.
4.2.2 Co/Mo catalyst results
It is important to note that all the experimental errors done in section 4.2.2, is done in a similar
manner in comparison to section 4.2.1. The experimental error calculations of the section
below may be seen in Appendix C- Calculations of hydrotreated SCG bio-oil in the presence
of both NiMo/Al2O3 and CoMo/Al2O3.
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4.2.2.1 Effect of temperature on the feed conversion
Simulated distillation data, similar as in the case of the NiMo/Al2O3 catalyst, has been
employed for the calculation of the conversion of the hydrotreated coffee bio-oil in the
presence of a CoMo/Al2O3 catalyst. The effect of that temperature has on the feed conversion
of coffee bio-oil is displayed in Figure 4. 13.
Feed convertion
100.00%
99.50%
99.08%
99.23%
99.20%
99.00%
98.32%
98.50%
98.00%
97.50%
97.00%
350
370
390
Temperature (°C)
410
Figure 4. 13- Effect of temperature on the feed conversion in the presence of CoMo/Al2O3.
It is obtained that at a temperature of 390 °C, the highest conversion is recorded. The feed
conversion of the coffee bio-oil increases with an increasing temperature. This is due to the
dormancy of the decarboxylation and decarbonylation reactions taking place. Due to these
reactions being endothermic reactions, the conversion will increase with an increase in
reaction temperature (Kim, et al., 2013).
A decrease in the feed conversion is noted from 390 °C to 410 °C. This could be as a result
of the water gas shift reaction which produces water and deactivates the catalyst. With a larger
amount of water produced, the catalyst deactivation rate increases and thus the conversion
will decrease.
It should be noted that the obtained feed conversion values at the temperature 370 °C, 390
°C and 410 °C are all in the experimental error margin. Thus, a conclusion for the optimal
temperature in terms of feed conversion is not verified.
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4.2.2.2 Effect of temperature on the liquid product composition
Using the data generated from the GC-MS analysis of the hydrotreating experiments in the
presence of the CoMo catalyst, a semi-qualitative analysis based on peak areas obtained from
the GC-MS has been used to divide the produced liquid fuels into their existing components.
These components have formed as a result of deoxygenation products as well as side
reactions taking place during the hydrotreating process. The effect of temperature on the liquid
product fuel composition is displayed in Figure 4. 14.
100%
Liquid composition
100%
99%
99%
98%
98%
97%
350
n-Alkanes
370
Iso-alkanes
Olefins
390
390
Temperature (°C)
Aromatics
390
Cyclic compounds
410
Oxygenate
Figure 4. 14- Influence that temperature has on the liquid product fuels produced from hydrotreating coffee biooil in the presence of CoMo/Al2O3.
It may be recorded from Figure 4. 14, that with an increase in reaction temperature a decrease
in the remaining oxygenates are observed. As explained by (Bezergianni, et al., 2010), the
occurrence rate of the deoxygenation reactions, namely decarboxylation, decarbonylation and
hydro deoxygenation increase with an increase in temperature. This results in more oxygen
molecules being eliminated from the product as water, carbon monoxide or carbon dioxide
and thus less oxygenates being present in the liquid fuel. A higher percentage of iso-alkanes
is recorded in the liquid fuel produced at 410 °C. This observation may be due to the
isomerizing reaction occurring more in the experimental setup.
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4.2.2.3 Effect of temperature on the liquid product yield
As mentioned in section 3.4.2, a simply mass based equation is used for the calculation of the
total liquid product yield. The hydrotreating experiments done in the presence of CoMo/Al2O3
is displayed in Figure 4. 15 and Figure 4. 16.
34.50
33.50
Liquid product produced (g)
34.00
33.40
33.50
32.70
33.00
32.20
32.50
32.00
31.50
32.00
31.50
31.00
30.50
30.00
29.50
350
370
390
390
Temperature (°C)
390
410
Figure 4. 15- Liquid fuel produced in the presence of CoMo/Al2O3.
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86.00
83.67
82.99
84.00
81.30
Yield percentage
82.00
80.04
79.55
80.00
78.26
78.00
76.00
74.00
72.00
350
370
390
390
Temperature (°C)
390
410
Figure 4. 16- Liquid product weight yield in the presence of CoMo/Al2O3.
It is obtained from Figure 4. 16 that the total liquid product yield at temperatures 370 °C and
390 °C are in close proximities from one another. A yield decrease from 390 °C to 410 °C is
observed. This may be a result of cracking taking place, forming a higher amount of lighter
components and thus increasing the gas yield by decreasing the liquid yield.
It should also be noted that no optimal temperature in terms of liquid product yield may be
verified due to all of the obtained results, excluding those obtained at a temperature of 410°C,
falling within the calculated experimental error margin.
4.2.2.4 Effect of temperature on the liquid product calorific value
Oxygen within a component lower the total potential calorific value that the component may
possess, thus this value may be a method of calculating the efficiency of the hydrotreating
process. A summary of the gross calorific values obtained from hydrotreating coffee bio-oil at
different temperature ranges is displayed in Figure 4. 17.
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45.200
44.922
Calorific value (MJ/kg)
45.000
44.800
44.494
44.565
44.600
44.287
44.400
44.200
44.000
43.800
43.600
350
370
390
Temperature (°C)
410
Figure 4. 17- Calorific values of liquid products at different temperatures in the presence of CoMo/Al2O3.
As can be seen in Figure 4. 17, the calorific values obtained from the produced liquid fuel may
be allocated from largest to smallest in terms of temperature as follow; 390 °C > 370 °C > 350
°C > 410 °C. As mentioned in section 4.2.1.4, error bars has been implemented on Figure 4.
17 to establish an experimental error margin for the recorded data.
It is recorded that the liquid fuel produced at a temperature of 410 °C has the lowest calorific
energy value. This is due to that large amount of iso-alkanes that the liquid fuel possess, as
can be seen in section 4.2.2.2, due to a large amount of hydrocracking taking place during the
process. Iso-alkanes has a significantly lower calorific energy value than alkanes (Sivasankar,
2008), thus at 410 °C the lowest calorific value is obtained.
The highest calorific value is obtained at a temperature of 390 °C. Thus, 390 °C is the most
appropriate temperature in terms of caloric values, due to it being located outside the
experimental error margin of the other recorded data. This is due to higher amounts of
oxygenates are present at lower temperature ranges, due to less efficient deoxygenation
occurring. These higher amounts of oxygenates reduces the calorific value of the liquid fuel
(Ramadhas, et al., 2005), thus a lower calorific value is obtained at lower temperatures.
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4.2.2.5 Effect of temperature on the fuel yield
To establish the optimal diesel fuel yield, the effect of temperature on the produced liquid fuel’s
yields has been investigated. The effect of temperature on the fuel yield is displayed in Figure
4. 18.
0.0079
0.013
0.02
0.019
Heavy Fuel Oils
0.9573
0.9756
0.97
0.9733
Diesel
Keroseen
0.0168
0.0056
0.0049
0.0036
Naphtha
0.018
0.006
0.0053
0.0041
0
0.2
0.4
0.6
0.8
1
Selectivity
410
390
370
350
Figure 4. 18- The temperature effect on the liquid fuel boiling range distribution from hydrotreated coffee bio-oil in
the presence of CoMo/Al2O3.
According to Figure 4. 18 an optimal temperature is recorded at 390 °C, due to the highest
diesel selectivity being obtained at that temperature. A slight decrease in the amount of heavy
fuel oils are recorded as the temperature increases. This is a result of a higher conversion rate
that occurs due to sufficient heat being present for the bio-oils to react. However, the liquid
fuel produced at the highest temperature variable of 410 °C has delivered the lowest diesel
selectivity. This is due to the heavier diesel molecules cracking into lighter components as a
result of a higher amount of hydrocracking that occurred. A steady increase in the production
of both naphtha and kerosene is noted. This increasing rate is another indication of
hydrocracking taking place at higher temperatures.
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4.2.3 Catalyst comparison
The effectiveness of the saturation of the double bonds present within the triglycerides of the
oil depends, among other things, on the chosen process catalyst (Kim, et al., 2013). It was
recorded that in the presence of both NiMo/Al2O3 and CoMo/Al2O3, an increase of feed
conversion has been noted with an increase in temperature. The optimal temperature
recorded for the highest feed conversion in both cases has been obtained at 390 °C. The
NiMo/Al2O3 catalyst had a slightly higher feed conversion than the CoMo/Al2O3 catalyst, with
a 99.43 % and 99.23 % respectively. It may be noted that the NiMo/Al2O3 liquid fuel results in
a higher feed conversion in comparison with the CoMo/Al2O3 liquid fuel as can be seen in
Figure 4. 19 and Figure 4. 20.
100
99.23
99.43
86.74
82.99
Percentage
80
60
40
20
0
NiMo
Feed Conversion
CoMo
Liquid yield
Figure 4. 19- Comparison of liquid fuel’s feed conversion and production yield percentage in the presence of
different catalysts at an optimal temperature of 390 °C.
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47
46.146
Calorific value (MJ/kg)
46.5
46
44.922
45.5
45
44.5
44
43.5
43
NiMo
CoMo
Catalyst
Figure 4. 20- Comparison of calorific values in the presence of different catalysts at an optimal temperature of
390 °C.
A more appropriate temperature in terms liquid product yield and calorific values has also
been recorded at a temperature of 390 °C. In the presence of a NiMo/Al2O3 catalyst, the liquid
fuel obtained a maximum liquid product yield of 86.74 % and a maximum calorific value of
46.146 MJ/kg. The CoMo/Al2O3 catalyst produced a decent maximum liquid product yield of
82.99 % at 390 °C and a calorific value of 44.922 MJ/kg. Thus, in terms of liquid product yield
and calorific value, the NiMo/Al2O3 catalyst produced a liquid fuel with a higher qualitative
value as can be seen in Figure 4. 19 and Figure 4. 20.
However, it should be noted that the obtained data in terms of the compared feed conversions,
liquid yields and the calorific values all fall within the experimental error parameters calculated
in Appendix C- Calculations of hydrotreated SCG bio-oil in the presence of both NiMo/Al2O3
and CoMo/Al2O3. Thus, no clear differences between the 2 catalysts may be concluded in
terms of the feed conversion, liquid yield and calorific values of
A comparison between the liquid product produced in the presence of NiMo/Al2O3 and the
CoMo/Al2O3 is shown in Figure 4. 21.
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Heavy Fuel Oils
0.013
0.007
0.976
Diesel
Keroseen
naphtha
0.976
0.006
0.009
0.006
0.008
0.000
0.200
0.400
0.600
Selectivity
CoMo
0.800
1.000
NiMo
Figure 4. 21- Comparison of liquid fuel’s composition in the presence of different catalysts at an optimal
temperature of 390 °C.
In terms of the produced liquid fuel compositions, both the NiMo/Al2O3 and the CoMo/Al2O3
catalyst obtained the most desired compositions at a temperature of 390 °C. However, a
higher saturation and deoxygenation of the feed stock triglycerides is recorded with the
NiMo/Al2O3 produced liquid fuel. This is due to a relatively high amount of olefins and
oxygenates still being present in the CoMo/Al2O3 liquid fuel in comparison to the lower amount
in the NiMo/Al2O3 liquid fuel. It can be seen in sections 4.2.1.2 and 4.2.2.2 that for all
temperatures, the CoMo/Al2O3 liquid fuels has a higher recorded amount of olefins and
oxygenates in the fuel’s composition in comparison with the NiMo/Al2O3 liquid fuel.
For this process, the desired product was required to be a liquid fuel of which diesel is the
main component. This requirement is best evaluated by means of investigating the diesel
composition in both catalytic liquid fuels. An optimal temperature of 390 °C has been recorded
to produce a liquid fuel with the highest diesel selectivity of 0.976 in the case for the NiMo/Al2O3
catalyst, however a relative similar result for the case of the CoMo/Al2O3 catalyst has been
obtained. A diesel selectivity of 0.976 has also been recorded for the CoMo/Al 2O3 catalyst
liquid fuel at a temperature of 390 °C. Thus, in terms of diesel selectivity’s both catalyst
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produced almost equal results as can be seen in Figure 4. 21. However, it may be noted that
in the presence of NiMo/Al2O3 a higher amount of lighter components is produced whereas in
the presence of CoMo/Al2O3 a higher amount of heavy fuel oils are produced.
Thus, according to the compared results mention above it may be noted that in terms of diesel
selectivity and qualitative fuel production that the NiMo/Al2O3 catalyst received a higher
performance rate in comparison with the inferior CoMo/Al2O3 at a process temperature of 390
°C. This is mainly due to a higher amount of lighter components and a lower amount of heavy
fuel oils produced in the presence of NiMo/Al2O3. The higher amounts of lighter components
may be flashed off and even collected to sell as a by-product. In the case of liquid product
produced in the presence of CoMo/Al2O3, a higher amount of cyclic compounds and
oxygenates are present in the product, thus resulting in a more unstable product. In the case
of the liquid product produced in the presence of NiMo/Al2O3, a higher amount of alkanes and
isomers are recorded and thus makes it the more appropriate liquid product.
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4.2.4 Produced liquid product comparison with SANS342
As mentioned in section 4.2.3, the liquid fuel produced in the presence of a NiMo/Al2O3 catalyst
and at a temperature of 390 °C has been labelled as the better qualitative renewable diesel
that was produced. In order to analyses the quality of the produced renewable diesel, it has
been compared to the South African Nation Standard for Automotive fuels (SANS 342). The
results of the produced renewable diesel compared to some of the parameters of the SANS
342 is displayed in Table 4. 1.
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Table 4. 1- Comparison between produced renewable diesel against SANS 342 standards.
Produced
renewable diesel in
Property
Units
Requirement presence of
Test method
NiMo/Al2O3
catalyst @ 390 °C
Sulphur content for Standard
diesel 500 ppm, max.
mg/kg
500
<1
ASTM D2622
T90, max
°C
362
305 ASTM D86
Flash point
°C
55
35.8 ASTM D93
Winter max.
°C
6
16
ASTM D2500
Water content, max.
mg/kg
350
30.3
ASTM D4377
Oxidation stability, max.
minutes
20
>20
ASTM D2274
Distillation
Cloud point:
Summer, max.
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4.2.4.1
Sulfur content
The total sulphur content for a standard diesel, according to the (SANS 342:Edition 5, 2014),
should not exceed 500 ppm or 500 mg/kg. By means of using ICP-OES analysis, the sulphur
content for the liquid product was recorded as “not detectable”. It should be noted that the
sensitivity of the ICP-OES analytical machine is 1 ppm, thus the sulphur content in the liquid
product is less than 1 mg/kg.
It is known that the use of biomass for the production of transportation fuels is advantageous
from a sulphur content point of view. This is typically due to the low sulphur content of biomass.
It is important for a fuel to contain a specific amount of sulphur, due to sulphur being a
greenhouse gas and increasing the rate of global warming. A fuel with a higher amount of
sulphur thus results in a higher amount of unwanted gasses being released during
combustion.
4.2.4.2
Distillation
The diesel standard (SANS 342:Edition 5, 2014) stated that 90% of the fuel should fall in a
boiling range below 362 °C. This is to ensure that a liquid product with a high diesel selectivity
is produced.
A display of the simulated distillation of the liquid product produced by hydrotreating bio-oil
extracted from SCG in the presence of NiMo/Al2O3 at a temperature of 390 °C is shown in
Figure 4. 22.
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400
350
Temperature (°C)
300
250
200
150
100
50
0
0
20
40
60
80
Weight percentage
100
120
Figure 4. 22- Simulation distillation of most appropriate liquid product produced at 390 °C in the presence of
NiMo/Al2O3.
It may be noted in Figure 4. 22, that a weight percentage of 90 is achieved at a temperature
of approximately 305 °C. This indicates that a good quality liquid product has been produced
with a high diesel selectivity, due to a small range of the total weight percentage falling below
250 °C. The produced liquid product thus conforms to the specification in the standard.
4.2.4.3
Flash point
According to the (SANS 342:Edition 5, 2014), the lowest possible flash point which a diesel
fuel is allowed to possess is 55 °C. Using the Eralystics ER 01 ERAFLASH analyser, the
produced renewable diesel measured a flash point of 35.8 °C.
According to (Li, et al., 2005), the flash point of substance is the lowest possible temperature
at which it will ignite when exposed to an ignition source. The obtained flash point of 35.8 °C
of the produced renewable diesel falls below the (SANS 342:Edition 5, 2014) standards of 55
°C. Due to the lower flash point, some problems may be experienced in terms of shipping,
storage and precautionary handling and transporting of the fuel. Lighter compounds are
therefore present in the produced liquid product. The presence of these lighter components
may reduce the flash point of the overall liquid product, due the lighter components having a
lower ignition temperature than heaver diesel components. Pentadecane, which has 15
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carbons in its structural chain has a boiling point of 270.6 °C. Thus, the presence of lighter
components is seen in Figure 4. 23 left from the pentadecane peak.
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A b u n d a n c e
T IC : T o n y
2 8 .3
5 0
1 .66 2 6
3
a .D \ d a ta .m s
8 e + 0 7
Octadecan (C18)
7 .5 e + 0 7
Heptadecane (C17)
7 e + 0 7
6 .5 e + 0 7
2 3 .8 4 6
Hexadecan (C16)
6 e + 0 7
5 .5 e + 0 7
Pentadecan (C15)
5 e + 0 7
4 .5 e + 0 7
4 e + 0 7
3 .5 e + 0 7
3 e + 0 7
2 .5 e + 0 7
2 e + 0 7
3 4 .2 3 4
3 2 .3 2 7
1 .5 e + 0 7
1 e + 0 7
5 0 0 0 0 0 0
5 .4 4 6
0
5 .0 0
2 1 .1 0 6
9 . 0 3 10 2 . 5 11 75 . 6 11 83 . 4 4 9
1 7 .8 7 3
1 0 .0 0
1 5 .0 0
2 0 .0 0
9 9
3 3535.60. 5
. 00 94 9
4 9 .2 0 8
3 8 .4 4 0 4 3 .2 4 9
4 8 .9 2 4
4 1 .3 4 0
3
4
.
7
6
809
3
4
.
4
7
8
3
3
3
.
5
5
6
.
0
1
7
3
3
.
8
5
5
3
4
.
5
6
8
22
99
..9
2
9
.7
34 89
55 57
093
7533
0. 6
47
3. 3
26
6 .46
14
2
222 677 . ..9
5
. 8.4.47
5 72
8 31
1
6
4 44 . 55
48.9951 .140
5 44 0
7 71
3 .8.4
2
95
.02
22
6
2 5 .0 0
3 0 .0 0
3 5 .0 0
4 0 .0 0
4 5 .0 0
5 0 .0 0
5 6 .7 6 5
5 5 .0 0
6 16 . 2
7 .39 96 2
6 0 .0 0
T im e - - >
Figure 4. 23- Chromatogram of the product liquid produced at 390 °C in presence of NiMo/Al2O3.
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The flashpoint of the renewable diesel’ can be improved by distilling off the lighter compounds
shown in Figure 4. 23. By eliminating the lighter components the flash point of the remaining
liquid diesel fuel will be increased. Addition profit may be made by means of collecting and
selling the eliminated lighter components as naphthalene or kerosene products.
4.2.4.4
Cloud point
The cloud point of a solution is defined by (Mejia, et al., 2013), as the temperature at which
solid phases begins to form within the liquid. The cloud point of diesel, in a summer or
wintertime frame, must be according to the (SANS 342:Edition 5, 2014) a maximum of 6 °C.
As mentioned in section 3.4.8, a modified method was used to obtain an indication of the
produced renewable diesel’s cloud point. It has been recorded that the temperature at which
solid phases started to form in the liquid is 16 °C. This cloud point temperature is higher than
the specification (SANS 342:Edition 5, 2014) indicating a maximum temperature of 6 °C. Cold
filter plugging flow may be an issue with the produced liquid diesel fuel. The high cloud point
temperature may be caused due to a high amount of saturates that are present in the liquid
fuel. According to (Mejia, et al., 2013), the higher amount of saturates present within a liquid
fuel, the higher the cloud point of the liquid fuel will be.
4.2.4.5
Water content
As stated by (SANS 342:Edition 5, 2014), the maximum possible water content which is
allowed in any diesel produced should not exceed 350 mg/kg. As can be seen in Table 4. 1,
the water content from the produced renewable diesel has been recorded as 30.3 mg/kg. This
value falls within the specification and thus the water content of the produced renewable diesel
is acceptable. The water present in the diesel is formed due to the deoxygenation pathway
during hydrotreatment called hydrodeoxygenation, producing water by means of eliminating
oxygen molecules from the coffee bio-oil feedstock. It is critical for the water content not to be
above 350 mg/kg, due to the negative effect that water will have on the ignition and energy
value of the liquid product as well as corrosion that will take place in an engine.
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4.2.4.6
Oxidation stability
The oxidation stability of any transport fuel is important, as it describes the degradation
tendency of the fuel. When oxidation of the fuels occur, it mainly forms hydro peroxides and
peroxides. With further degradation, low molecular weight acids, ketones, aldehydes and
alcohols may be formed. The presence of acids may increase the acidity of the fuel and lead
to corrosion, whereas the presence of alcohols may lower the flash point of the fuel.
According to the fuel standard (SANS 342:Edition 5, 2014), a time period of at least 20 minutes
must past before the oxidation the fuel should be recorded. As can be seen in Appendix EAnalytical results under Oxidation stability, the oxidation stability of the liquid product stays
stabile for a time period of 12 hours. Thus, the produced liquid fuel has an exceptional high
oxidation stability and therefore conforms to the diesel standard.
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5. CONCLUSION AND RECOMMENDATIONS
It was discussed in section 2.1, that an extremely large amount of coffee is produced and
consumed yearly worldwide. These large amounts of spent coffee grounds contain significant
quantities of valuable ingredients such as lipids, proteins and lignocellulose materials, which
is being discarded after use at present.
It was demonstrated that these SCG might serve as a potential feedstock in the production of
alternative transportation fuels. By means of using a soxhlet extractor, the necessary bio-oils
still present within the SCG has been extracted. The use of 2 solvent types, namely a polar
methanol and a non-polar hexane was used during this extraction process. It was recorded
that hexane was the better choice in terms of extracted bio-oils from the SCG, due to it
producing a higher liquid weight yield in comparison with the methanol. The hexane produced
a liquid yield range of 12.1 % to 17.55 %, whereas the methanol only produced a liquid yield
range of 5.28 % to 6.29 %.
Due to the composition of triglycerides, it is more attracted to a non-polar component whereas
free fatty acids are more attracted to polar components. The spent coffee grounds used for
the extraction process mostly contains triglycerides in comparison to cracked free fatty acids.
This is due to a higher average oil extraction yield being obtained from the non-polar hexane
solvent.
The extracted bio-oil was catalytically hydrotreated with the goal to produce an alternative
transportation fuel. The reaction temperature and catalyst choice has been set as the reaction
parameter to investigate the optimal condition for the production of the best qualitative liquid
product according to the (SANS 342:Edition 5, 2014).
The optimal fuel yield in terms of temperature was obtained by means of varying the reaction
temperature from 350 °C to 410 °C. It is recorded that the amount of isomers present in the
liquid products increased as the reaction temperature of the process increased. This was due
to the occurrences of cracking taking place increase with temperature, thus the heavy diesel
molecules is cracked to lighter compounds.
It was found that more cyclic compounds, aromatics and olefins were formed in the presence
of CoMo/Al2O3, thus a lower saturation percentage is recorded in comparison to the
NiMo/Al2O3 catalyst. A larger amount of oxygenates still is present within the liquid products
produced in the presence of CoMo/Al2O3 in comparison to those in the presence of
NiMo/Al2O3.
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At a reaction temperature of 390 °C, the highest diesel selectivity was recorded for both
catalysts. The diesel selectivity was recorded as 0.976 for both catalysts, however in the
presence of CoMo/Al2O3 a higher amount of heavy fuel oils was noted in comparison to the
liquid products in the presence of NiMo/Al2O3. Higher amounts of kerosene and naphtha was
found in the NiMo/Al2O3 liquid products in comparison to the CoMo/Al2O3 liquid products.
The NiMo/Al2O3 liquid product was chosen the best fuel product, due to the lower amounts of
heavy fuel oils and the fact that lighter components may be eliminated more easily than the
mentioned heavy fuel oils. The eliminated kerosene and naphtha may also serve as an
additional profit if it is collected using a distillation process and sold as pure components.
To be classified as a high quality diesel fuel, it has to meet specific standards in terms of its
liquid composition and characteristics. As mentioned above, the NiMo/Al2O3 liquid product was
deemed the most appropriate to be compared to the diesel standards or the diesel standard
(SANS 342:Edition 5, 2014). With a sulphur content of less than 1 ppm, a distillation
temperature of 305 °C, a water content of 30.3 mg/kg and a oxidation stability of over 12 hours
it conforms to the standard with regard to the mentioned parameters. However, in terms of the
flash point and cloud point the standards was not met. The liquid product obtained a flash
point of 35.8 °C in comparison to the minimal required temperature of 55 °C. This is due to the
high amounts of lighter components present within the liquid, due to the occurrence of
cracking. The heavier produced diesel molecules was cracked into lighter carbon compounds
with lower boiling points. As mentioned above, the lighter components may be easily flashed
off due to their lower boiling points and thus the flash point of the liquid product will improve.
The high cloud point temperature is also deemed an imperfect aspect of the produced liquid
product. Due to the high cloud point of 16 °C of the liquid product, the product has a higher
crystallization temperature and thus is above the maximum cloud point temperature standard
of 6 °C. A higher cloud point temperature will directly influence the cold filter plugging point in
a negative manner. It is known that fuels produced from biomass produce good quality fuel,
however the cold filter plugging point and cloud point temperatures are usually above the
maximum standard for diesel fuel. The cloud point and cold filter plugging point temperature
may be improved if a further isomerizing reaction is performed on the liquid product. This
reaction will in turn increase the isomer content of the liquid product and thus decrease the
cloud and cold filter plugging point of the fuel. This reaction is done by means of using an
isomerization catalyst.
.Thus to conclude, bio-oil extracted from SCG may be hydrotreated in the presence of catalyst
to produce a good quality transportation fuel. The use of a non-polar solvent such as hexane
produces a higher quality bio-oil in terms of FFA’s. A higher quality liquid product in terms of
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diesel selectivity and liquid composition was produced in the presence of a NiMo/Al2O3 catalyst
at a reaction temperature of 390 °C. The produced liquid product compares with the diesel
standard (SANS 342:Edition 5, 2014) except for the flashpoint and cloud point. However,
standard procedures may be followed to improve these shortcomings and thus producing a
good quality transportation fuel from SCG.
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Suleiman, J., Hu, B., Peng, H. & Huang, C., 2009. Separation/preconcentration of trace
amounts of Cr, Cu and Pb in environmental samples by magnetic solid-phase extraction with
Bismuthiol-II-immobilized magnetic nanoparticles and their determination by ICP-OES.
Talanta, 77(5), pp. 1579-1583.
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Tailleur, R., 2017. Effect of hydrocarbon vaporization and gases solubility on performance and
cycle length of gas-phase – Trickle bed reactors system used for deep diesel hydrotreatment.
Fuel, Volume 199, pp. 299-323.
Tiwari, R. et al., 2011. Hydrotreating and hydrocracking catalysts for processing of waste soyaoil and refinery-oil mixtures. Catalysis Communications, 12(6), pp. 559-562.
United
States
Available
Enviromental
at:
Protection
Agency,
2017.
EPA.
[Online]
https://www.epa.gov/diesel-fuel-standards/diesel-fuel-standards-and-
rulemakings
[Accessed 12 July 2017].
Utlu, Z. & Kocak, M., 2008. The effect of biodiesel fuel obtained from waste frying oil on direct
injection diesel engine performance and exhaust emissions. Renewable Energy, 33(8), pp.
1936-1941.
Vardon, D. et al., 2013. Complete Utilization of Spent Coffee Grounds To Produce Biodiesel,
Bio-Oil, and Biochar. Fuel and Recycle, 10(1), pp. 1286-1294.
Veriansyah, B. et al., 2012. Production of renewable diesel by hydroprocessing of soybean
oil: Effect of catalysts. Fuel, Volume 94, pp. 578-585.
Watson, R., Rodhe, H., Oeschger, H. & Siegenthaler, U., 1990. Greenhouse Gases and
Aerosols . In: J. Houghton, G. Jenkins & J. Ephraums, eds. Climate Change. New York; Port
Chester; Melbourne; Sydney: Cambridge University Press, pp. 7-17.
Williams,
Available
B.
&
Jones,
at:
R.,
2015.
International
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[Online]
https://www.iea.org/topics/renewables/subtopics/bioenergy/
[Accessed 15 March 2017].
X. Li, V. S. T. K., 2014. Energy recovery potential analysis of spent coffee grounds pyrolysis
products. Journal of Analytical and Applied Pyrolysis, Volume 110, pp. 79-87.
Yang, L. et al., 2016. Hydrothermal liquefaction of spent coffee grounds in water medium for
bio-oil production. Biomass and Bioenergy, Volume 86, pp. 191-198.
Yang, Y. et al., 2013. Hydrotreating of C18 fatty acids to hydrocarbons on sulphided
NiW/SiO2–Al2O3. Fuel Processing Technology, Volume 116, pp. 165-174.
Yusoff, S., 2006. Renewable energy from palm oil – innovation on effective utilization of waste.
Journal of Cleaner Production, 14(1), pp. 87-93.
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Zhang, H. et al., 2014. Hydroprocessing of waste cooking oil over a dispersed nano catalyst:
Kinetics study and temperature effect. Applied Catalysis B: Environmental, Volume 150-151,
pp. 238-248.
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APPENDIX A- SCG EXTRACTION CALCULATION
Experimental error calculations for various solvent extractions
For the calculation of the experimental error, a number of 3 repeats of the extraction process for both solvents was done and the data was
recorded. The averages and standard deviations in the case of both solvents has been calculated as can be seen in Figure A. 1. The standard
deviation was then used in a excel function to insert the error bars for both solvents in terms of their calculated standard deviations.
Figure A. 1- Calculation of the experimental errors for the different extracted bio-oils extraction yields by means of standard deviation.
Calculation of weight percentage of FFA present in the extracted SCG bio-oil
The calculation of the quantities FFA’s present within the hexane solvent extracted bio-oil and the methanol solvent extracted bio-oil is
demonstrated in Figure A. 2. The area peaks recorded by the GC-FAME analytical machine was multiplied by the respective k-value of the FFA.
A standard k-value for each FFA has been used for this calculation.
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Figure A. 2- Quantitative calculation of FFA present in solvent extracted bio-oils.
Experimental error calculation for calorific values
For the calculation of the experimental error, both oils have been analyzed a number of 3 times by the bomb calorific meter and the results was
recorded. An average of the 2 different solvent extracted bio-oils was calculated along with each of the solvent extracted bio-oil’s standard
deviations. These calculated standard deviations were then used in the excel function which draws error bars by means of the data’s obtained
standard deviations. This calculation is shown in Figure A. 3.
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Figure A. 3- Calculation of the experimental errors for the different extracted bio-oils caloric values by means of standard deviation.
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APPENDIX B- CATALYST COMPARISON
Run
Catalyst
1 Ni-MO
2 Ni-MO
3 Ni-MO
4 Co-MO
5 Co-MO
6 Co-MO
7 Ni-MO
8 Co-MO
9 Ni-MO
10 Ni-MO
11 Co-MO
12 Co-MO
Temperature
(°C)
390
410
370
390
410
370
350
350
390
390
390
390
Bio-oil Injected Product fraction at
(g)
370 °C
39.789
40.114
40.065
40.250
40.227
40.038
40.222
40.231
40.195
40.120
40.222
40.244
0.993
0.992
0.982
0.990
0.990
0.989
0.976
0.979
0.980
0.989
0.987
0.987
Produced liquid
product
30.900
31.100
29.500
31.091
32.000
33.500
32.500
32.200
33.700
34.800
32.700
33.400
Produced
Heavy Fuel
Feed
Naphtha Naphtha Keroseen Keroseen Diesel Diesel Mass
Heavy Fuel
liquid product
Oils
Conversion Selectivity Mass (g) Selectivity Mass (g) Selectivity
(g)
oils Mass (g)
above 370 °C
Selectivity
0.226
0.258
0.546
0.311
0.320
0.368
0.790
0.676
0.667
0.400
0.412
0.431
99.43%
99.36%
98.64%
99.23%
99.20%
99.08%
98.04%
98.32%
98.34%
99.00%
98.98%
98.93%
0.008
0.010
0.006
0.006
0.018
0.005
0.004
0.004
0.013
0.008
0.008
0.008
0.241
0.295
0.177
0.183
0.571
0.178
0.137
0.132
0.448
0.275
0.271
0.267
0.009
0.011
0.007
0.006
0.017
0.005
0.004
0.004
0.014
0.009
0.009
0.009
0.281
0.336
0.201
0.176
30.392
0.164
0.143
0.116
0.485
0.310
0.301
0.294
0.976
0.971
0.969
0.976
0.957
0.970
0.967
0.973
0.953
0.972
0.970
0.970
30.152
30.211
28.577
30.731
30.392
32.488
31.431
31.340
32.099
33.815
31.716
32.408
0.007
0.008
0.019
0.013
0.008
0.020
0.024
0.019
0.020
0.012
0.013
0.013
Liquid
product
yield
0.226
0.258
0.546
0.410
0.251
0.670
0.790
0.612
0.667
0.400
0.412
0.431
77.66%
77.53%
73.63%
77.24%
79.55%
83.67%
80.80%
80.04%
83.84%
86.74%
81.30%
82.99%
Figure B. 1- Summary of all hydrotreating procedures done with the catalyst choice and reaction temperature as reaction variables.
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As can be seen in Figure B. 2, for the calculation of the feed conversion a simple conversion
equation is used.
Figure B. 2- Calculations of all hydrotreated procedures feed conversion.
The equation used for the calculation of the feed conversion may be further displayed in
equation 3.
Feed conversion % =
( Amount of oil injected − amount of liquid product produced)
× 100
Amount of oil injected
(3)
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APPENDIX C- CALCULATIONS OF HYDROTREATED SCG BIOOIL
IN
THE
PRESENCE
OF
BOTH
NIMO/AL2O3
AND
COMO/AL2O3
Experimental error calculations for the feed conversion
A number of 3 experimental procedures at a temperature of 390 °C has been done with the
purpose to calculate the average experimental error for the hydrotreatment procedure in the
presence of both NiMo/Al2O3 and CoMo/Al2O3 catalyst. As shown in Figure C. 1 and Figure
C. 2, the average of the 3 feed conversions that was calculated was obtained, as well as the
standard deviation of the data. The standard deviation was then used in a function in Excel to
add error bars in the data graphs in terms of the standard deviation.
Figure C. 1- Calculation of the experimental errors of the feed conversion for the hydrotreated SCG bio-oil in the
presence of NiMo/Al2O3 at 390 °C.
Figure C. 2- Calculation of the experimental errors of the feed conversion for the hydrotreated SCG bio-oil in the
presence of CoMo/Al2O3 at 390 °C.
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Experimental error calculations for the liquid product yield
A total of 3 experimental procedures in the cases of both catalysts individually has been done
for the calculation of an experimental error. The results for the experimental repeats were
recorded and an average and standard deviation has been calculated for both catalytic
hydrotreating procedures. By means of using the calculated standard deviation and the build
in excel function, error bars were drawn into the graphs displaying the experimental error. The
calculation for the standard deviations are displayed in Figure C. 3 and Figure C. 4.
Figure C. 3- Calculation of the experimental errors of the liquid product produced and yield percentage for the
hydrotreated SCG bio-oil in the presence of NiMo/Al2O3 at 390 °C.
Figure C. 4- Calculation of the experimental errors of the liquid product produced and yield percentage for the
hydrotreated SCG bio-oil in the presence of CoMo/Al2O3 at 390 °C.
Experimental error calculation for calorific values
For the calculation of the experimental error in terms of the calorific values that were obtained,
a liquid product sample was analysed a number of 3 times. The results were recorded and the
average and standard deviation were calculated for the analytical repeats. The calculated
standard deviation was then implied in the build in excel function to drawn error bars into the
recorded data in terms of the calculated standard deviation. These calculations are displayed
in Figure C. 5.
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Figure C. 5- Calculation of the experimental errors of the produced liquid products by means of standard
deviation for both catalytic hydrotreating procedures.
Selectivity calculations for the product liquid
For the calculation of each fuel composition’s selectivity, the construction of a simulation
distillation was done and used in the cases of both NiMo/Al2O3 and NiMo/Al2O3 catalyst. By
means of using the boiling ranges for naphtha, kerosene, diesel and heavy fuel oils
respectively, the weight percentage of each component was recorded from the constructed
simulation distillation graph. This weight percentage was then converted into a fractional value
and thus the selectivity of each component was calculated. This calculation was implemented
for every hydrotreatment procedure and is displayed in Figure C. 6.
Figure C. 6- Demonstration for the calculation of each component’s selectivity in the case of all produced liquid
products.
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APPENDIX D- SIMULATION DISTILLATION GRAPHS
600
Temperature ( °C)
500
400
300
200
100
0
0
20
40
60
Weight percentage
80
100
120
Figure D. 1- Simulation distillation graph of the liquid product produced in the presence of NiMo/Al2O3 at 350 °C.
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600
Temperature ( °C)
500
400
300
200
100
0
0
20
40
60
80
Weight percentage
100
120
Figure D. 2- Simulation distillation graph of the liquid product produced in the presence of NiMo/Al2O3 at 370 °C.
400
350
Temperature (°C)
300
250
200
150
100
50
0
0
20
40
60
80
Weight percentage
100
120
Figure D. 3- Simulation distillation graph of the liquid product produced in the presence of NiMo/Al2O3 at 390 °C.
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600
Temperature (°C)
500
400
300
200
100
0
0
20
40
60
80
100
120
Weight percentage
Figure D. 4- Simulation distillation graph of the liquid product produced in the presence of NiMo/Al2O3 at 410 °C.
600
Temperature (°C)
500
400
300
200
100
0
0
20
40
60
80
Weight percentage
100
120
Figure D. 5- Simulation distillation graph of the liquid product produced in the presence of CoMo/Al2O3 at 350 °C.
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600
Temperature (°C)
500
400
300
200
100
0
0
20
40
60
80
Weight percentage
100
120
Figure D. 6- Simulation distillation graph of the liquid product produced in the presence of CoMo/Al2O3 at 370 °C.
600
Temperature (°C)
500
400
300
200
100
0
0
20
40
60
80
Weight percentage
100
120
Figure D. 7- Simulation distillation graph of the liquid product produced in the presence of CoMo/Al2O3 at 390 °C.
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400
350
Temperature (°C)
300
250
200
150
100
50
0
0
20
40
60
80
Weight percentage
100
120
Figure D. 8- Simulation distillation graph of the liquid product produced in the presence of CoMo/Al2O3 at 410 °C.
600
Temperature (°C)
500
400
300
200
100
0
0
20
40
60
80
Weight percentage
100
120
Figure D. 9- Simulation distillation graph of the liquid product produced in the presence of NiMo/Al2O3 at 390 °C
experimental repeat #1.
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600
Temperature (°C)
500
400
300
200
100
0
0
20
40
60
80
Weight percentage
100
120
Figure D. 10- Simulation distillation graph of the liquid product produced in the presence of NiMo/Al2O3 at 390
°C experimental repeat #2.
600
Temeprature (°C)
500
400
300
200
100
0
0
20
40
60
80
Weight percentage
100
120
Figure D. 11- Simulation distillation graph of the liquid product produced in the presence of CoMo/Al2O3 at 390
°C experimental repeat #1.
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600
Temperature (°C)
500
400
300
200
100
0
0
20
40
60
80
Weight percentage
100
120
Figure D. 12- Simulation distillation graph of the liquid product produced in the presence of CoMo/Al2O3 at 390
°C experimental repeat #2.
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APPENDIX E- ANALYTICAL RESULTS
Highest calorific values obtained for both catalysts
Figure E. 1- Pictorial view of best-recorded calorific value in the presence of NiMo/Al2O3 obtained from the liquid
product produced at 390 °C.
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Figure E. 2- Pictorial view of best-recorded calorific value in the presence of CoMo/Al2O3 obtained from the
liquid product produced at 390 °C.
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Flash point of most appropriate liquid product
Figure E. 3- Pictorial view of flash point obtained from most appropriate produced liquid product in the presence
of NiMo/Al2O3 at 390 °C.
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GC-MS chromatograms
A b u n d a n c e
T IC : T o n y 4 .D \ d a ta .m s
4 2 .1 9 0
1 2 5 0 0 0 0
1 2 0 0 0 0 0
1 1 5 0 0 0 0
1 1 0 0 0 0 0
4 1 .2 4 4
1 0 5 0 0 0 0
1 0 0 0 0 0 0
9 5 0 0 0 0
4 2 .3 7 2
9 0 0 0 0 0
8 5 0 0 0 0
8 0 0 0 0 0
7 5 0 0 0 0
3 8 .1 0 3
7 0 0 0 0 0
5 0 .9 2 2
6 5 0 0 0 0
6 0 0 0 0 0
5 5 0 0 0 0
4 2 .7 5 9
5 0 0 0 0 0
4 5 0 0 0 0
4 2 .4 4 3
4 0 0 0 0 0
3 5 0 0 0 0
5 1 .9 3 1
3 0 0 0 0 0
2 5 0 0 0 0
2 9 .7 2 1
4 2 .8 9 3
2 0 0 0 0 0
44 33 .. 01 25 47
1 5 0 0 0 0
3 0 .9 7 1
3 3 .9 7 1
1 0 0 0 0 0
4 3 .7 0 2
4 9 .8 4 0
5 2 .0 2 7
5 1 .0 2 7
5 0 0 0 0
0
5 .0 0
1 0 .0 0
1 5 .0 0
2 0 .0 0
2 5 .0 0
3 0 .0 0
3 5 .0 0
4 0 .0 0
4 5 .0 0
5 0 .0 0
5 5 .0 0
6 0 .0 0
T im e - - >
Figure E. 4- Chromatogram of extracted SCG bio-oil by using the non-polar hexane as the solvent.
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A b u n d a n c e
T
I C :
T
o n y 3 . D
8 0 0 0 0 0
\ d a t a . m s
3 8 . 1 4 1
44 22 . .13 16 71
7 5 0 0 0 0
4 1 . 1 8 7
7 0 0 0 0 0
6 5 0 0 0 0
6 0 0 0 0 0
5 5 0 0 0 0
5 0 . 9 2 1
5 0 0 0 0 0
4 5 0 0 0 0
4 2 . 4 3 5
4 0 0 0 0 0
3 5 0 0 0 0
3 0 0 0 0 0
44 22 .. 78 29 06
2 5 0 0 0 0
4 9 . 8 4 4
2 0 0 0 0 0
5 1 . 9 2 6
1 5 0 0 0 0
4 1 . 9 1 8
2 1 . 9 5 8
1 9 . 5 6 0 2 4 . 2 4 0
1 0 0 0 0 0
4 3 . 1 4 5
2 9 . 6 6 0
3 8 . 2 8 7
5 1 . 0 2 8
5 2 . 0 2 8
2 6 . 4 1 2
5 0 0 0 0
0
5 . 0 0
T
im
1 0 . 0 0
1 5 . 0 0
2 0 . 0 0
2 5 . 0 0
3 0 . 0 0
3 5 . 0 0
4 0 . 0 0
4 5 . 0 0
5 0 . 0 0
5 5 . 0 0
6 0 . 0 0
e -->
Figure E. 5- Chromatogram of extracted SCG bio-oil by using the polar methanol as the solvent.
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A b u n d a n c e
T IC : T o n y
2 8 . 35 01 .66 2 6
3
a .D \ d a ta .m s
8 e + 0 7
7 .5 e + 0 7
7 e + 0 7
6 .5 e + 0 7
2 3 .8 4 6
6 e + 0 7
5 .5 e + 0 7
5 e + 0 7
4 .5 e + 0 7
4 e + 0 7
3 .5 e + 0 7
3 e + 0 7
2 .5 e + 0 7
2 e + 0 7
3 4 .2 3 4
3 2 .3 2 7
1 .5 e + 0 7
1 e + 0 7
5 0 0 0 0 0 0
5 .4 4 6
0
5 .0 0
2 1 .1 0 6
9 . 0 3 10 2 . 5 11 75 . 6 11 83 . 4 4 9
1 7 .8 7 3
1 0 .0 0
1 5 .0 0
2 0 .0 0
9 9
3 3535.60. 5
. 00 94 9
4 9 .2 0 8
3 8 .4 4 0 4 3 .2 4 9
4 8 .9 2 4
4 1 .3 4 0
3
4
.
7
6
809
3
4
.
4
7
8
..4.53
16
5.5. 062
22
99
..9
22 2
96
.7
7585.363
0
222 677 . ..9
5
.6587.4.847
5 72
8 31
1
6
4 44 . 556 .46147 712473 .8.42
48.9951 .140
5 44 0
95
.0234 8955 5709333 33333
2 5 .0 0
3 0 .0 0
3 5 .0 0
4 0 .0 0
4 5 .0 0
5 0 .0 0
5 6 . 7 6 5 6 16 . 27 .39 96 2
5 5 .0 0
6 0 .0 0
T im e - - >
Figure E. 6- Chromatogram of produced liquid product in the presence of NiMo/Al2O3 at 390 °C.
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A b u n d a n c e
T IC : T o n t 4
2 8 .5 3 4
8 .5 e + 0 7
a .D \ d a ta .m s
3 0 .6 0 9
8 e + 0 7
7 .5 e + 0 7
7 e + 0 7
2 3 .8 6 7
6 .5 e + 0 7
2 6 .1 8 7
6 e + 0 7
5 .5 e + 0 7
5 e + 0 7
4 .5 e + 0 7
4 e + 0 7
3 .5 e + 0 7
3 e + 0 7
2 .5 e + 0 7
2 e + 0 7
3 2 .3 3 2
3 4 .2 3 0
1 .5 e + 0 7
1 e + 0 7
3 35 5. 0. 61 08 7
5 0 0 0 0 0 05 . 4 8 8
0
5 .0 0
2 1 .1 0 4
9 . 0 6 18 2 . 5 31 35 . 6 11 88 . 4 5 0
1 0 .0 0
1 5 .0 0
2 0 .0 0
3 6 .0 4 5
2 7
9 6
.3 6 2
4 9 .1 9 9
2 7 .1
3 8 . 4 42 18 .43 33 . 32 4 0
4 8 .9 1 9
.45
7 6067421216
73
6.034 817 92033 33333.44.458
2.22.4
98
.0.3
22222
627777
.7.9
2
1
35213 7. 3
755.. 9
0.. 127.6
18. 5
5
3997
.678
90
.5
27
956
.92
190 662
.351171
448. 895055.371
44 444 .. 556 .45047 756472 .8.7
7 8.40 10 9
..26
2
96
.5
3
7 2
0 7
2 5 .0 0
3 0 .0 0
3 5 .0 0
4 0 .0 0
4 5 .0 0
5 0 .0 0
7 .60 72 8
5 6 . 7 6 0 6 16 . 3
5 5 .0 0
6 0 .0 0
T im e - - >
Figure E. 7- Chromatogram of produced liquid product in the presence of CoMo/Al2O3 at 390 °C.
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Oxidation stability
Figure E. 8- Pictorial view of the oxidation stability results obtained from the liquid product produced in the
presence of NiMo/Al2O3 at 390 °C.
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Method for GC-MS analysis
Table E. 1- Method for GC-MS analytical machine.
Parameter
Value
Column
Agilent 7890A GC system and 5975C MSD (
30 m length, 0.25 mm diameter, 0.1 µm film)
Carrier gas
Helium
Linear velocity
0.9 mL/min
Inlet
Split/splitless
Split ratio
10:1
Injection volume
1 µL
Inlet temperature
250 °C
Oven temperature

35 °C for 4 minutes

Ramp at 5 °C/min to 190 °C, hold for 5
minutes

Ramp at 10 °C/min to 420 °C, hold for 2
minutes
Solvent for needle washes
Dichloromethane
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APPENDIX F- ECSA EXIT LEVEL OUTCOMES (ELO’S)
ELO 1: Problem solving
Identify, formulate, analyse and solve complex engineering problems creatively and
innovatively.
ELO 1 is accomplished with the completion of this project. Throughout the project various
engineering problems manifested and thus solutions for these problems must have been
developed.
My competency for problem solving was mostly proven during the experimental procedures
that were done to obtain products as well as data. By means of using creative and innovating
thoughts, the present problems were solved.
ELO 2: Application of scientific and engineering knowledge
Apply knowledge of mathematics, natural sciences, engineering fundamentals and an
engineering speciality to solve complex engineering problems.
ELO 2 is mostly accomplished by processing the obtained raw experimental data to present it
in a professional and a knowledgeable matter. Mathematical competency was proven by
calculation various experimental yields, selectivity’s, conversion, etc. during data processing.
Competency in natural science and engineering fundamentals were proven by successfully
completing the experimental procedures as well as processing the obtained raw data into
valuable values and conclusions.
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ELO 3: Engineering Design
Demonstrate competence to perform creative, procedural and non-procedural design and
synthesis of components, systems, engineering works, products or processes.
ELO 3 is accomplished by the completion of this project. My competency for to perform
creative procedural and non-procedural designs is proven by the completions of my
experimental procedures. The experimental setup and procedure is a demonstration hereof
due to certain procedural methods being followed to complete the experiment, as well as nonprocedural methods being adapted into the experimental setup due to specific errors that
manifested.
Competency in the synthesis of engineering works and processes are also proven with the
completion of the experimental procedures, due to various products being obtained as result
of these procedures.
ELO 4: Investigations, experiments and data analysis
Demonstrate competence to design and conduct
My competency to design is proven with the completion of the written project. The designed
report layout is constructed for sinful deployment of the obtained knowledge throughout the
project. By means of processing the obtained raw data from the experimental procedures also
proves my competency to design and conduct various excel spreadsheets as well as graphs.
These spreadsheets and graphs has been design to display the processed result of the
experimental producers to ensure an accurate conclusion may be made.
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ELO 5: Engineering methods, skills and tools, including Information
Technology
Demonstrate competence to use appropriate engineering methods, skills and tools, including
those based on information technology.
For the completion of this project various engineering methods, skills and tools were used for
the successful completion of all the experimental procedures as well as the raw data
processing.
Informational technologies such as Microsoft excel and word has been used for data
processing and data presentation. Various analytical equipment has also been used to
analyses the produced products for knowledgeable conclusion to be made. Thus, competency
in informational technology and engineering methods is proven by the completion of all
analyzed data.
ELO 6: Professional and technical communication
Demonstrate competence to communicate effectively, both orally and in writing, with
engineering audiences and the community at large.
The project would not have been successfully completed without oral and written
communication. ELO 6 is thus completed by the successful completion of this project.
My competency to communicate in a written manner is proven by the sending of emails to
arrange meetings, as well as to book analytical equipment or ask for technical or procedural
help from my project leader, lab manager, etc.
Various meetings were also held throughout the year, which are proven with the completed
minutes of every meeting, for project progress reports, experimental producer demonstrations
and fundamentals, as well as for conformation of specific completed sections of the written
report. Various presentations has also been held throughout the project to ensure effective
time management as well as correct conclusion in terms of the processed results were made.
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ELO 7: Sustainability and impact of engineering activity
Demonstrate critical awareness of the impact of engineering activity on the social, industrial
and physical environment.
ELO 7 has been accomplished with the assistance of my lab manager and project leader.
Correct and effective disposal of chemical components that were used during experimental
producers were done, due to their corrosive impact on the environment. All safety methods
were always followed during the performance of any experimental procedure due to their
hazardous characteristics on humans and the environment. Prior to the start of all
experimental procedures, various lab safety courses were followed as well as the completion
of a Hazard Identification and Risk Assessment (HIRA) was done.
Thus, my awareness of the impact of the engineering activity on the social, industrial and
physical environment is proven.
ELO 8: Individual, team and multidisciplinary working
Demonstrate competence to work effectively as an individual, in teams and in multidisciplinary
environments.
ELO 8 is accomplished by the completion of this project, due to the fact that the project is
deemed as an individual project. All responsibilities for the completion of the experimental
procedures, written report, progress updates, etc. were solely on me.
However, I received the help of various people in the completion of this project. My project
leader helped with understanding the experimental procedures as well as data presentation
and my lab manager helped by means of analytical procedures, lab safety, etc. I as an
individual student also served as help with other students in the completion of these projects
by means of helping with various writing technics, experimental procedures, etc.
Thus, my competency to work as an individual as well as to receive and give out comments
and help is proven.
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ELO 9: Independent learning ability
Demonstrate competence to engage in independent learning through well-developed learning
skills.
ELO 9 is accomplished by the completion of this project. Due to the topic of this project being
something relative new to me, I demonstrated my ability to research and learn independently
with the goal to understand the various fundamentals thereof. During the experimental
producers, independent learning was also demonstrated by means of understanding how the
process works as well as the fundamentals for various aspects thereof.
ELO 10: Engineering Professionalism
Demonstrate critical awareness of the need to act professionally and ethically and to exercise
judgment and take responsibility within own limits of competence.
Due to this project being deemed as an individual project, full responsibility for the completion
of this project was taken upon me. With a vast amount of formal as well as informal meetings,
I demonstrated my ability to act and perform in a professional and ethical manner. If an
injustice was committed in the laboratories, for example bad hygiene during other students’
experimental procedures, I exercised my judgement to correct the matter.
ELO 11: Engineering Management
Demonstrate knowledge and understanding of engineering management principles and
economic decision-making.
For the successful completion of this project, indebt time planning was crucial. A week-byweek deadline has been set up for various smaller parts of the project to ensure sufficient time
management. My competency in engineering management is thus proven by planning the
events of the project toughly and ensuring that all deadlines are met.
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My economic competency is also proven by the use of the funds that were made available to
me for the completion of this project. Due to careful planning and consideration, my funds
were not exceeded and no extra funds was needed for the completion of my project.
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