Chemical Compositions and Classification of Crude oil – type of

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Chemical Compositions and Classification of Crude oil – type of Ondo State bitumen exudate.
H.O. Ogunsuyi*, K.O. Ipinmoroti and O.O. Ajayi.
Department of Chemistry, Federal University of Technology, P.M. B. 704,
Akure, Nigeria
Abstract.
The chemical constituents of the maltene component of bitumen sample obtained from
Agbabu in Odigbo Local Government area of Ondo State were examined using GC – MS. Out of the
72 peaks recorded on the chromatogram (Fig.1.0), only 67 compounds were identified representing
96.82% of the total crude- oil. The major constituents were alicyclic hydrocarbon (44.59%), alkanes
(28.61%) and polar compounds (13.71%). The minor constituents were the
mono aromatic
hydrocarbons and the olefins which recorded 3.47% and 6.44% respectively. The different classes of
compounds so identified comfirmed that the bitumen shared close similarities with the conventional
crude oil. However, the classification of the bitumen into crude oil-type revealed that it is asphaltic –
resinous type of crude oil, unlike the conventional crude oil that are often times paraffinic in nature.
Hence, different refinery infrastrctures are required for the refining and upgrading of the bitumen
exudates. The varieties of chemical compounds constituting the bitumen exudate can be converted into
useful petrochemical products.
Key words. Bitumen exudate, Chemical constituents, crude oil –type classification.
*Author for correspondence: olayinkaogunsuyi @yahoo.com.
Introduction.
Petroleum samples obtained from reservoir rocks and bitumen extracted from fine-grained
rocks have many similarities, but they also exhibit many important differences. There is no doubt that
they are related; indeed, bitumen is almost universally accepted as the direct precursor for petroleum
(Stoneley, 1995). Both bitumen and petroleum exhibit a wide range of compositions and this has been
attributed to the source –rock facies and the composition of the kerogens that generated the bitumen.
The chemical composition of bitumen is complex and varies considerably depending upon the
geology of the sources, age and feedstock and this dictates the method of manufacture. It is essentially
of a hydrocarbon nature with great variety of hydrocarbons present, mostly of high molecular weight
together with complex molecules including a certain proportion of heteroatoms of nitrogen, oxygen
and sulphur. The most widely accepted concept of the constitution is that bitumen is made up of three
major components. The first is described as a mixture of asphaltenes, which are high molecular weight
complex molecules, insoluble in paraffinic hydrocarbons such as n-heptane and soluble in aromatic
hydrocarbon such as benzene. The second component is described as a mixture of resin and the third is
mineral oil (Allinson,1975). Among the several standard analytical techniques employed to
characterise hydrocarbon fraction of heavy crude oil
and petroleum products are: Gas
chromatography-simulated distillation; (ASTM D-2, 1976; ASTM D-2425,1989; Oluwole et al 1985,),
Gas chromatography- Mass spectrometry( Zeman and Bartl, 1978; Yu and Hites, 1981; Yergey and
Risby, 1982; Wang et al,1994), High performance - Liquid chromatography, (Altgelt and Gouw, 1975;
Altgelt et al, 1979), Single column adsorption chromatography (ASTM- D- 2007, 1989; Allula et al,
1989) e.t.c..Some of the reviewed work had shown that knowledge of composition of any crude oil is
an important tool in determininig the class of crude oil it belongs and this information is valuable to
refiner who intends to know the quantity of the successive distillates that can be obtained from the
crude oil (Kinghorn,1983).
Several classification methods based on both the physical and chemical classifications had
been reported
by previous workers among which are US Bureau of Mines classsification
(Smith,1966), Correlation index and Approximate summary (Gruse and Steven,1960), Chemical
classifications (Tissot and Welte’s, 1978 and Sachanen, 1950).
Previous researches conducted on some Nigerian bitumen samples had revealed that the
synthetic crude obtainable from the mineral oil could serve as refinery feedstock for the production of
motor fuel and fuel oil which are quite similar to those derivable from the conventional petroleum
(Ondo State Government, 1982 and Adegoke, et al 1991). However, none of the previous studies had
documented the classification of the heavy crude oil deposit in Odigbo Local Government area.. In
view of the fore–going the present study aims at classifying the bitumen exudate from Agbabu into
crude oil type on the basis of its chemical constituents following Tissot and Welte’s chemical
classification. This information would aid decisions on the best way to refine the heavy oil.
Materials and Method.
Sample collection.
Bitumen samples were collected from the borehole deposit located at Agbabu in Odigbo Local
Government area of Ondo State. The sample location lies within latitude 06o 35’ 556N to 060 39’ 169N
and Longitude 4o 49’ 769E to 40 53’ 409E. The exudate was drawn from the bulk deposit four times
and homogenized thoroughly to obtain its representative sample..
Solvent Extraction.
Soxhlet extraction method (Jacob and Filby, 1983) was adopted to extract the bitumen samples.
Eighty grams (80g) of the sample were placed in cellulose extraction thimble (Whatman 33mm x
94mm) and extracted with 250ml of toluene (Baker reagent) for 12 hours until the liquid siphoning to
the flask was clear. The toluene extract was vacuum evaporated using rotary evaporator (Buchi,
Rotavapor-RE, 218336) at 40oC to recover the crude bitumen extract. The extract was left open to
allow the solvent evaporate off completely.
Precipitation of asphaltene from the crude extract.
Ten grams (10g) of the crude extract were weighed inside a 250ml conical flask and 100ml npentane was added into the flask. The mixture was mixed with glass rod to ensure thorough mixing
and left to stand for 10mins. The asphaltene precipitated out of the saturated hydrocarbon solvent and
was recovered after centrifuging the mixture for 3 mins and decanting the solvent using a Pasteur
pipette. The asphaltene was rinsed with small portion of the solvent thrice until the solvent became
clear. To further ascertain that the maltene was rid off the precipitated asphaltene, the maltene was
filtered through filter paper with the aid of vacuum pump.
Identification of the maltene components.
The identification of the chemical constituents and various hydrocarbons embedded in the samples
were conducted by GC/MS using direct injection in the split mode under the following conditions;
1200MS Varian equipped with HP 5MS column: 30m x 0.25mm x 0.25. Hydrogen was used as carrier
gas at 1.0ml/min flow rate; Initial oven temperature was 500C then ramped at 2.50C/min to 3200C for
10mins The quantitative identification of different constituents was performed by comparison of their
retention times and fragmentation patterns with those of the library.
Classification of the crude oil.
The bitumen exudate was classified into crude oil types, following the classification method of Tissot
and Welte (Table 1.0). The classification was based on the concentrations of the various chemical
compounds identified in the samples.
TABLE: 1.0: Tissot and Welte’s crude oil classification.
Saturated
hydrocarbon
Aromatics
Saturated
hydrocarbon
Aromatics
>50%
<50%
≤50%
≥50%
Crude oil type
Sulphur ccontent
Paraffins
> naphthenes
Paraffinic
<1%
paraffins
> 0%
<1%
paraffins
<40%
paraffinicnaphthenic
naphthenes
<40%
Naphthenes
> paraffins
Naphthenic
<1%
naphthene
> 40%
>1%
paraffins
>10%
aromaticintermediate
Paraffins
≥10%
>1%
Naphthenes
≤25%
aromaticasphaltic
Paraffins
≥10%
<1%
Naphthenes
≥ 25%
aromaticnaphthenic
Source: Kinghorn (1983)
Results and Discussion.
The various chemical constituents identified in the maltene component of the bitumen sample are as
given in Table 2.0. These constituents were grouped into different classes of compounds as follows:
Normal alkanes (28.61%), olefins (6.44%), alicyclic compounds (44.59%), mono aromatic hydrocarbons
(3.47%) and heteroatomic compounds ( 13.71%).
Normal alkanes.
Most of the alkane compounds identified in the bitumen deposit were branched –chain alkanes (Table
3.0) Various isomers of n-heptane-tridecane (C7 - C13 ) were the predominant constituents of the light
hydrocarbon of the heavy crudes, while the medium - heavy hydrocarbons were within the range of C25C54, most of which were straight chain alkanes e.g. pentacosane(C25H52), hexacosane(C26H54) and
tetracontane(C40H82). The low molecular weight straight-chain alkanes component of the deposits are
viewed to make the crude a potential source of gasolene since, in conventional crude oil, alkanes
between C5 -C15 (pentane-pentadecane) are the chief constituents of straight –run (uncracked) gasolene
(Kinghorn, 1983).
Alkenes.
The alkenes within the heavy crude (Table 4.0) were very similar to those found in conventional crude
oil. Hexene, heptene, octene, and alicyclic alkenes had been identified in conventional crude oil
(Kinghorn, 1983). However, the analyzed bitumen samples contained higher molecular weight olefins
such as hexacosene, isomers of nonadecene and eicosene. Alkenes are quite reactive and unstable
hydrocarbons, therefore high –pressure hydrogenation process (Eq.1.0) can be employed to produce
more stable alkanes from them.
Catalyst
H (R) C=CH2 +H2
H2(R) C-CH3
(1.0)
Table 2.0: ldentified chemical compounds in the maltene component of borehole bitumen
S/N
Compound
Mol. Weight
Mol. Formula
Retention. Time
Conc. %(w/w)
1
Methane isocyanato
57
C2H3NO
6.44
0.0.008
2
Benzene
78
C6H6
6.73
0.0.009
3.
Methyl cyclopentane
84
C6H12
7.32
0.0.016
4
Cyclohexane
84
C6H12
10.29
0.0.019
5.
Toluene
92
C7H8
11.26
0.0.138
6
1,1-dimethyl cyclopentane
98
C7H14
11.47
0.0.169
7
1,3-dimethylcyclopentane
98
C7H14
14.82
0.0.179
8.
1,2-dimethyl-cis-cyclopentane
98
C7H14
17.05
1.1.253
9
Methyl cyclohexane
98
C7H14
17.89
1.1.393
10
1,3-dimethyl-cis-cyclopentane
98
C7H14
19.69
1.1.664
11
3,3-dimethyl pentane
100
C7H16
21.04
1.1.627
12
3-methyl hexane
(anteisoheptane)
100
C7H16
22.24
1.1.529
13
Ethyl benzene
106
C8H10
23.24
1.1.520
14
1,3-dimethyl benzene
106
C8H10
26.46
1.1.831
15.
P-xylene
106
C8H10
27.51
1.1.713
16.
1,2,3-trimethyl cyclopentane
112
C8H16
28.25
2.2.762
17.
1,2,4-trimethyl cyclopentane
112
C8H16
29.44
2.2.597
18.
1,4-dimethyl cyclohexane
112
C8H16
29.55
NN/Q
19.
1,1-dimethyl cyclohexane
112
C8H16
30.04
2.2.196
20
1,4-dimethyl-cis-cyclohexane
112
C8H16
31.45
2.2.050
21
1-ethyl-1-methyl-cyclopentane
112
C8H16
32.87
2.2.779
22
1-ethyl-3-methyl-cyclopentane
112
C8H16
35.36
1.1.891
23.
1,2-dimethyl-trans-cyclohexane
112
C8H16
35.98
1.1.939
24
1,4-dimethyl-trans-cyclohexane
112
C8H16
37.81
1.1.732
25
1,2-dimethyl-cis-cyclohexane
112
C8H16
NN/Q
26
Ethyl cyclohexane
112
C8H16
38.46
2.2.081
27
2-(1,1-dimethyl ethyl)-3-methyl
oxirane
114
C7H14O
40.02
1.1.624
28
3,4-dimethyl-hexane
114
C8H18
41.52
1.1.723
29
2,3,4-trimethyl-pentane
114
C8H18
43.25
1.1.688
30.
4-methyl heptanes
114
C8H18
42.82
1.1.847
31
3-methyl heptanes
114
C8H18
44.27
NN/Q
32
2-methyl-heptane
114
C8H18
46.10
1.1.745
33
3-propyl cyclohexene
124
C9H16
46.29
1.1.735
34
Methyl cyclooctane
126
C9H18
47.05
1.1.598
s35
1,1,4-trimethylcyclohexane
126
C9H18
48.16
1.1.796
36.
1-ethyl-2-methyl- cis –
cyclohexane
126
C9H18
48.68
1.1.821
37
1, 2ß,,3, - trimethylcyclohexane
126
C9H18
49.42
1.1.749
38.
Trans-1, 2-diethyl cyclopentane
126
C9H18
50.50
1.1.411
39.
1-ethyl-4-methyl cyclohexane
126
C9H18
50.78
1.1.389
40
2-ethyl-hexanal
128
C8H16O
53.92
1.1.523
41
2,2,4-trimethyl hexane
128
C9H20
54.17
1.1.389
42
2,3,4-trimethyl hexane
128
C9H20
54.66
1.1.351
43.
3-methyl octane
128
C9H20
54.87
1.1.268
44
3-ethyl-3-hexanamine
129
C8H19N
55.54
1.1.288
45
Pentyl-cyclopentane
140
C10H20
57.31
1.1.351
46.
2,3,3-trimethyl octane
156
C11H24
59.02
1.1.602
47.
2-n-propythiolane,s,s dioxide
162
C7H14O2S
59.90
0.0.949
48.
Trans-2,4-dimethylthiane
s,s,dioxide
162
C7H14O2S
60.23
NN/Q
49
2-pentyl-i-heptene
168
C12H24
61.60
1.1.821
50
2,2,4,6,6 pentamethyl heptane
170
C12H26
61.94
2.2.048
51
1,2-dibutyl cyclopentane
182
C13H26
63.20
1.1.823
52.
2,2,3-trimethyl decane
184
C13H28
64.80
1.1.734
53
2,2-dimethyl undecane
184
C13H28
65.88
2.2.022
54
2,2,6-trimethyl decane
184
C13H28
67.92
2.2.168
55
2,2,9trimethyl decane
184
C13H28
68.06
2.2.021
56
1-fluoro dodecane
188
C12H25F
68.88
1.1.922
57
Cyclohexyl cyclooctane
194
C14H26
70.41
2.2.010
58
2-azido-2,4,4,6,6-pentamethyl
heptanes
211
C12H25N3
71.81
1.1.945
59
3-n-hexylthiolane s,s,dioxide
204
C10H20O2S
72.65
0.0.060
60
Trifluoroacetyl-di-tbutylphosphine
242
C10H18F3OP
74.78
1.1.824
61
2,2-dimethyl-propyl-2,2dimethyl-propanesulfinyl
sulfone
254
C10H22O3S2
76.06
0.0.945
62
2-methyl-1-octadecene
266
C19H38
78.78
1.1.399
63
Dichloroacetic acid, 6-
268
C12H22Cl2O2
83.56
1.1.623
Ethyl-3-octyl ester
64
3,7,11,15-tetramethyl-2hexadecene
280
C20H46
84.20
1.1.499
65
5-(7a-isopropenyl-4,5-dimethyl
octahydroinden-4-yl)-3-methyl
pent-2-en-1-ol
290
C20H34O
86.59
NN/Q
66
1-hexacosene
364
C26H52
87.71
1.1.487
67
Eicosyl-cyclohexane
364
C26H52
89.50
1.1.399
68
Baccharane
414
C30H54
89.68
511.151
69
Hexatriacontane
506
C36H74
92.52
0.0.906
70
Tetracontane
562
C40H82
95.56
0.0.729
71
Etratetracontane
618
C44H90
100.75
0.0.028
72
Tetrapentacontane
758
C54H110
103.78
0.0.013
Key: N/Q Not Quantified.
Table 3.0: Saturated hydrocarbons identified in the maltene fraction of the bitumen.
S/N
Compound name
Mol. Weight
Mol. formula
Conc.%(w/w)
1.
3,3-dimethyl pentane
100
C7H16
1.831
2.
3-methyl hexane
100
C7H16
1.529
3.
3,4-dimethyl hexane
114
C8H18
1.723
4.
4-methyl heptanes
114
C8H18
1.847
5.
2,3,4-trmethyl pentane
114
C8H18
1.688
6.
2-methyl heptanes
114
C8H18
1.745
7.
3-methyl heptanes
114
C8H18
1.735
8.
2,2,4-trimethyl hexane
128
C9H20
1.389
9.
2,3,4-trimethyl hexane
128
C9H20
1.351
10
3-methyl octane
128
C9H20
1.268
11.
2,3,3-trimethyl octane
140
C11H24
1.602
12.
2,2,4,6,6-pentamethyl
heptanes
170
C11H24
2..048
13.
2,2 dimethyl undecane
184
C13H28
2.022
14.
2,2,9-trimethyl decane
184
C13H28
2.021
15
2,2,3-trimethyl decane
184
C13H28
0.964
16
2,2,6-trimethyl decane
184
C13H28
2.168
17.
Hexatriacontane
506
C36H74
0.906
18
Tetracontane
562
C40H82
0.729
19.
Tetratetracontane
618
C44H90
0.028
20.
Tetrapentanecontane
758
C54H110
0.013
Total % composition
28.61%
Table 4.0: Unsaturated hydrocarbons identified in the maltene fraction of borehole bitumen
S/N
Compound name
Mol. Weight
Mol. formula
Conc. %(w/w)
1.
3-propyl cyclohexane
124
C9H16
1.735
2.
2-pentyl-1-heptene
168
C12H24
1.821
3.
2-methyl-1-octadecene
266
C19H38
1.399
4.
1-hexacosene
364
C26H52
1.487
Total % composition
6.44%
Alicyclic compounds or cycloparaffins
Alicyclic compounds identified in the deposit were predominantly methyl derivatives of
cyclopentane and cyclohexane (Table 5.0). These were very similar to alicyclic hydrocarbons
associated with conventional crude oil. The deposit contained relatively low percentages of bicyclic
and tetracyclic (baccharane) compounds. The concentration of the alicyclic compounds of the deposits
can be used to assess their maturation level. The tetra and pentacycloalkanes are most abundant in
young crude oil that is not yet fully developed (Kinghorn.1983). Since these compounds were not
predominant in the bitumen sample analysed, the deposit can be said to have reasonably mature for
exploitation. These constituents of the deposits could also be subjected to further cracking to yield
straight-chain alkanes.
Table 5.0: Alicyclic hydrocarbons identified in the maltene fraction of borehole bitumen
S/N
Compound name
Mol. Weight
Mol. Formula
Conc.%(w/w)
1
Methyl cyclopentane
84
C6H12
0.016
2
Cyclohexane
84
C6H12
0.019
3
1, 1-dimethyl cyclopentane
98
C7H14
0.169
4
1,3-dimethyl-cis-cyclopentane
98
C7H14
1.664
5
1,3-dimethyl cyclopentane
98
C7H14
0.179
6
1,2-dimethyl-cis-cyclopentane
98
C7H14
1.253
7
Methyl cyclohexane
98
C7H14
1.393
8
3,3-dimethyl pentane
100
C7H16
1.831
9.
1,2,3-trimethylcyclopentane
112
C8H16
2.768
10
1,2,4-trimethylcyclopentane
112
C8H16
2.597
11.
1,4-dimethyl–cis-cyclohexane
112
C8H16
2.050
12
1,4-dimethyl cyclohexane
112
C8H16
N/Q
13
1,1-dimethylcyclohexane
112
C8H16
2.196
14.
1-ethyl-3-methyl cyclopentane
112
C8H16
1.891
15.
I-ethyl-1-methyyl cyclopentane
112
C8H16
2.779
16.
1,2-dimethyl-trans cyclohexane
112
C8H16
1.939
17.
1,4-dimethyl-trans-cyclohexane
112
C8H16
1.732
18.
1,2-dimethyl-cis-cyclohexane
112
C8H16
N/Q
19
Ethyl cyclohexane
112
C8H16
2.081
20.
1,1,4-trimethyl cyclohexane
114
C9H18
1.796
21.
Trans-1,2-diethyl cyclopentane
126
C9H18
1.411
22.
1-ethyl-2-methyl-cis-cyclohexane
126
C9H18
1.821
23.
1,2ß,3–trimethyl cyclohexane
126
C9H18
1.749
24.
1,2,3–trimethyl cyclohexane
126
C9H18
N/Q
25.
1-ethyl-4-methyl cyclohexane
126
C9H18
1.389
26
Methyl cyclooctane
126
C9H18
1.598
27.
1,2,4-trimethyl cyclohexane
126
C9H18
1.690
28
Pentyl cyclopentane
140
C10H20
1.351
29
1,2-dibutyl cyclopentane
182
C13H26
1.823
30.
Cyclohexyl cyclooctane
194
C14H26
2.010
31
Eicosyl cyclohexane
364
C26H52
1.399
Total % composition
44.59%
Monoaromatic compounds.
The monoaromatic compounds identified in the maltene constituents of the bitumen samples
were benzene, toluene, ethylbenzene, P-xylene (Tables 6.0), These compounds were similar to
aromatic constituents of crude oil (Kinghorn, 1983). The percentage composition of aromatic
compounds in the samples was 3.47%.. This value was comparatively lower than the percentage
composition of saturated hydrocarbon in the sample. Hence, the ratio of aromatic hydrocarbon to the
saturated hydrocarbon was low i.e saturated hydrocarbon present in the sample was in sevenfold of its
aromatic counterpart. The decrease in this ratio had been attributed to increasing maturation due to
thermal cracking and generation of aliphatic hydrocarbon as compared with aromatic hydrocarbon
during thermal maturation (Kinghorn, 1983). The
aromatic fraction obtained fron the column
chromatography of the maltene fraction of the sample was analyzed for polyaromatic compounds with
gas chromatograph. This work was reported elsewhere.
Table 6.0: Monoaromatic hydrocarbons identified in the maltene fraction of borehole bitumen
S/N
Compound name
Mol. Weight
Mol. Formula
Conc.%
1.
Benzene
78
C6H6
0.009
2.
Toluene
92
C7H8
0.138
3.
Ethyl benzene
106
C8H10
1.530
4.
P-xylene
106
C8H10
1.793
Total % composition
3.47%
NSO compounds and other heteroatomic compounds (Polar compounds)
These are compounds containing Nitrogen, Sulphur and Oxygen. These and other heteroatomic
co mpounds containing chlorine, fluorine and phosphorus were identified in the maltene portion of the
bitumen sample.
Nitrogen containing compounds. Percentage composition of nitrogen compounds in the analyzed
sample was found to be 3.241% of the sample.
Nitrogen compounds are unwelcome in any crude oil, as they are responsible for catalyst poisoning
and formation of gum in fuel (Seifet, 1969). Consequently, it is necessary that these nitrogen
containing compounds are removed or chemically modified to other compounds that will not pose
threat to refining process. Usually, nitrogen containing compounds in crude oil are dislodged of their
nitrogen content by hydrodenitrogenation (Eq.2.0) process as follows:
H2
N
H2
N
H2
C5H11NH2
C5H12 + NH3
(2.0)
H
Sulphur containing compounds. The sulphur compounds are given in Tables (7.0) The percentage
composition of sulphur
N compounds in the samples was 1.95% of the total deasphaltened oil. The
presence of sulphur inHcrude oil is not desirous, since it influences the colour, odour, stability and
processing of the crude oil adversely (Oderinde, 1989). All sulphur compounds are foul-smelling and
lachrymatory. In addition, these compounds can give poisonous and obnoxious compounds in the
refined products, hence making the products corrosive and dangerous to end-users. (Gruse and Steven,
1960.)
Sulphur containing compounds could be desulphurized by subjecting them to high – pressure
hydrogenation process (Eq. 3.0)
high pressure
R2S + 2H2
2RH +H2S
(3.0)
Oxygen, fluorine and chlorine containing compounds.
The oxygen containing compounds identified in the samples were predominantly acids, alcohols,
aldehydes and esters, these constituted about 4.77% of the total deasphaltened oil.
The fluorine containing compounds of the sample constituted about 3.23% of the oil.
Table 7.0: The polar compounds identified in the maltene fraction of borehole bitumen
S/N
Compound name
Mol. Weight
Mol. Formula
Conc.%(w/w)
Nitrogen containing compounds
1 Methane isocyanato
57
C2H3NO
0.008
2 3-ethyl-3-hexanamine
129
C8H19N
1.288
3 2-azido-2,4,4,6,6-pentamethyl heptanes
211
C12H125N
1.945
Sulphur containing compounds
4 Trans-2,4-dimethyl thiane S,S dioxide
162
C7H14O2S
N/Q
5
6
2-n-propylthiolane,S,S dioxide
3-n-hexylthiolane S,S dioxide
162
204
C7H14O2S
C10H20O2S
0.949
0.060
7
2, 2-dimethyl propyl 2, 2-dimethyl
254
C10H22O3S2
0.945
propane sulfinyl sulfone.
Oxygen containing compounds
8
2-(1,1-dimethyl ethyl)-3- methyl oxirane
114
C7H14O
1.624
9
2-ethyl-hexanal
128
C8H116O
1.523
10. Dichloroacetic acid, 6-ethyl-3-octyl ester
268
C12H22Cl2O2
1.623
11
290
C20H34O
N /Q
5-(7a-isopropendyl-4,5-dimethyl octahydroinden -4-yl)-3-methyl pent-2-en-1-ol
Fluorine containing compounds
12
1-Fluoro-dodecane
186
C12H125F
1.922
13.
Trifluoroacetyl-di-t-butyl phosphine
242
C10H118F3OP
1.824
Total % composition
13.71%
The various chemical compounds identified in the bitumen sample were categorized into their
respective refinery products as shown in Table (8.0)
Table 8.0: The posssible refinery products obtainable from the bitumen exudate
Hydrocarbon
Refinery products
Uses
C7 - C11
Gasoline
Fuel for internal combustion engines
C11- C
Kerosene
For lighting purposes and jet fuels.
C15- C25
Gas-oil
Diesel fuel
C22 – C40
Lubricating –oil
Grease and wax for automobile engines.
Above C40
Asphalt
Furnace oil, road asphalt, binder, fillers and
water-insulating water.
Alkenes (Olefins)
Petrochemicals
Feed stocks for chemical industries. These
compounds are used for the production of
synthetic fibre and rubber, plastic, soaps,
detergents, paints, drugs and cosmetics
Alkanes:
Aromatics:
C6H6 (Benzene)
Basic feed stock required Agrochemicals, dyestuff and pharmaceutical
in the production of Linear
Alkyl Benzene (LAB) and
the production of basic
chemical in industries
Linear Alkyl Benzene
Heavy alkylate
Transformer oil, Special grease and- viscous
thermal fluid.
As an additive in the manufacture of lube-oil.
(NNPC,)Solvent makingHerbicides
Toluene
Chlorotoluenes:
Dye stuff industry
O-chlorotoluene
Raw material for terephthalic acid and
dimethyl terephthalate
P-Chlorobenzena
P-Chlorobenzaldehyde
Xylene
P-xylene
Conclusion
The characterization of the maltene fraction of bitumen samples from Odigbo Local government
area of Ondo State by GC-MS has been accomplished. The work revealed that chemical compositions
of bitumen are very similar to those identifiable in the conventional crude oil. Despite the close
similarities in their chemical compositions, the proportion of these compounds in the bitumen exudate
actually made it impossible to group it either as paraffinic or naphthenic type of crude oil . For any
crude oil to be paraffinic in- nature, the saturated hydrocarbon must be more than 50% and the sulphur
content must be less than 1% of the total crude oil (Table 1.0). In the same vein, for a crude oil to be
considered naphthenic, its aromatic component must be less than its alicylic counterparts and its
sulphur content must be less than 1% . Based upon the classification method employed, the bitumen
exudate under investigation has saturated and alicylic hydrocarbons of less than 50% and sulphur
content higher than 1%, hence, it can conveniently be classified as asphaltic crude oil. This implies
that the bitumen deposit may not be a suitable alternative source of gasoline grade crude oil due to its
higher sulphur content which is beyond the range of value (0.2 - 0.5% ) expected for a prospective
gasoline grade crude oi (Speight, 1980). Nevertheless, the bitumen contains other valuable chemical
compounds that are potential feedstocks for petrochemical industries.
Figure 1.0: Gas chromatogram of maltene component of borehole bitumen at Agbabu
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