Supplementary Material
Hydrothermal Carbonization (HTC) of Selected Woody and Herbaceous
Biomass Feedstocks
S. Kent Hoekmana*, Amber Brocha, Curtis Robbinsa, Barbara Zielinskaa, and Larry Felixb
a
Division of Atmospheric Sciences, Desert Research Institute
2215 Raggio Parkway, Reno, NV (USA) 89512
b
Gas Technology Institute
1500 First Ave. North, Birmingham, AL (USA) 35203
* Corresponding Author: Kent.Hoekman@dri.edu; phone (775) 674-7065; fax (775) 674-7016
These supplementary materials include figures that illustrate details of analytical methodologies;
figures depicting important relationships among HTC process temperature, product yields, and
product compositions; and tables providing detailed analytical results from measurements of
organic acids and sugars after HTC treatment of biomass feedstocks. A list of all supplementary
figures and tables is provided below.
Figure S-1. GC plumbing arrangement for analysis of gaseous products from HTC.
Figure S-2. GC analysis of gaseous products from HTC treatment of biomass.
Figure S-3. HPLC/RI analysis of aqueous by-products from HTC treatment of loblolly pine.
Figure S-4. Oxygen balance of HTC process for six feedstocks at six temperatures.
Figure S-5. Average mass balance of all HTC experiments from 175°C to 295 ºC.
Figure S-6. Energy densification of hydrochar vs. HTC reaction temperature.
Figure S-7. Mass yield of hydrochar vs. HTC reaction temperature.
Figure S-8. Energy yield of hydrochar vs. HTC reaction temperature.
Figure S-9. Van Krevelen diagram of hydrochars from woody and herbaceous biomass.
Figure S-10. Atomic N/C ratio in hydrochar vs. HTC reaction temperature.
Figure S-11. CO2 production vs. HTC reaction temperature.
Figure S-12. Non-volatile residue (NVR) in aqueous products vs. HTC reaction temperature.
Figure S-13. Total Organic Carbon (TOC) in aqueous products vs. HTC reaction temperature.
Figure S-14. Total sugars and organic acids from HTC treatment of biomass.
Figure S-15. Total sugars and organic acids compared to TOC and NVR contents of HTC
aqueous products.
Table S-1: Organic acids measured in HTC aqueous products, as % of starting dry feedstock.
Table S-2: Sugars in HTC aqueous products, expressed as % of starting dry feedstock.
(A)
(B)
Figure S-1: GC plumbing arrangement for analysis of gaseous products from HTC. (A) Valve
position for loading sample, (B) valve position for injecting sample.
Propene
Acetylene
H2
CO
CH4
Ethane
B
Ethene
CO2
CO
O2
N2
CO2
A
0
5
10
15
20
Retention Time, min.
Figure S-2. GC analysis of gaseous products from HTC treatment of biomass. (A) HTC of loblolly
pine at 255°C; (B) calibration standard.
2
Levoglucosan
Galactose, Xylose, Mannose
Fructose, Inositol, Arabinose
Erythritol
Mannitol, Glycerol
Arabitol
Glucose-Pinitol
Sucrose- Trehalose
Figure S-3. HPLC/RI analysis of aqueous by-products from HTC treatment of loblolly pine at
215°C.
Figure S-4. Oxygen balance of HTC process for six feedstocks at six temperatures.
3
Figure S-5: Average mass balance of all HTC experiments from 175 °C to 295 ºC.
Energy Densification vs. Average Reaction Temperature
1.6
Energy Densification
1.5
Tahoe Mix
Loblolly Pine
Pinyon/ Juniper
Rice Hulls
Corn Stover
Sugarcane Bagasse
1.4
1.3
1.2
1.1
1.0
0.9
0
150
175
200
225
250
o
Average Reaction Temperature, C
Figure S-6. Energy densification of hydrochar vs. HTC reaction temperature.
4
275
300
Mass Yield
95
90
Tahoe Mix
Loblolly Pine
Pinyon/ Juniper
Rice Hulls
Corn Stover
Sugarcane Bagasse
85
Percent Mass Yield
80
75
70
65
60
55
50
45
40
35
30
160
180
200
220
240
260
280
300
o
Average Reaction Temperature, C
Figure S-7. Mass yield of hydrochar vs. HTC reaction temperature.
Energy Yield vs. Average HTC Reaction Temperature
100
Percent Energy Yield
90
80
70
60
50
40
160
Tahoe Mix
Loblolly Pine
Pinyon/ Juniper
Rice Hulls
Corn Stover
Sugarcane Bagasse
180
200
220
240
260
Average Reaction Temperature, oC
Figure S-8. Energy yield of hydrochar vs. HTC reaction temperature.
5
280
300
1.8
1.6
Biomass
Peat
Atomic H/C Ratio
1.4
1.2
1.0
0.8
Lignite
Tahoe Mix
Loblolly Pine
Pinyon/ Juniper
Rice Hulls
Corn Stover
Sugarcane Bagasse
Coal
0.6
0.4
0.2
Anthracite
0.0
0.0
0.2
0.4
0.6
0.8
Atomic O/C Ratio
Figure S-9. Van Krevelen diagram of hydrochars produced from HTC treatment of woody and
herbaceous biomass feedstocks. All experiments had 30-min. hold time at final temperature. With
increasing HTC temperature (from 175 to 295 °C), hydrochars progressed from “Biomass” to “Peat”
to “Lignite” regions of the chart.
Atomic N/C Ratio vs. Average Reaction Temperature
0.025
Tahoe Mix
Loblolly Pine
Pinyon/ Juniper
Rice Hulls
Corn Stover
Sugarcane Bagasse
Atomic N/C Ratio
0.020
0.015
0.010
0.005
0.000
0
150
175
200
225
250
275
300
280
300
Average Reaction Temperature, oC
Figure S-10. Atomic N/C ratio in hydrochar vs. HTC reaction temperature.
CO2 vs. Average Reaction Temperature
CO2, % of starting dry mass
18
16
Tahoe Mix
Loblolly Pine
Pinyon/ Juniper
Rice Hulls
Corn Stover
Sugarcane Bagasse
14
12
10
8
6
4
2
0
160
180
200
220
240
o
Average Reaction Temperature, C
Figure S-11. CO2 production vs. HTC reaction temperature.
260
Non-volatile residue in aqueous products
30
Tahoe Mix
Loblolly PIne
Pinyon/ Juniper
Rice Hulls
Corn Stover
Sugarcane Bagasse
NVR, % starting dry mass
25
20
15
10
5
0
160
180
200
220
240
260
280
300
o
Average Reaction Temperature, C
Figure S-12. Non-volatile residue (NVR) in aqueous products vs. HTC reaction temperature.
Total organic carbon in aqueous products
TOC, % starting dry mass
16
14
12
10
8
Tahoe Mix
Loblolly PIne
Pinyon/ Juniper
Rice Hulls
Corn Stover
Sugarcane Bagasse
6
4
2
0
160
180
200
220
240
260
280
300
o
Average Reaction Temperature, C
Figure S-13. Total Organic Carbon (TOC) in aqueous products vs. HTC reaction temperature.
8
Total sugars and organic acids in aqueous phase products
16
175oC
215oC
235oC
255oC
275oC
295oC
% Starting Dry Feedstock
14
12
10
8
6
4
Organic Acids
Sugars
2
0
TM LP PJ SC CS RH TM LP PJ SC CS RH TM LP PJ SC CS RH TM LP PJ SC CS RH TM LP PJ SC CS RH TM LP PJ SC CS RH
Feedstock
Figure S-14. Total sugars and organic acids in aqueous products from HTC treatment of biomass.
TM= Tahoe Mix; LP= Loblolly Pine; PJ= Pinyon/Juniper; SC= Sugarcane Bagasse; CS= Corn
Stover; RH= Rice Hulls.
Measurements of Aqueous Solution
Organic Acids
Percent starting dry mass
20
Sugars
TOC
NVR
15
10
5
Tahoe
175
215
235
255
275
295
Loblolly
175
215
235
255
275
295
Pinyon/ Juniper
175
215
235
255
275
295
Rice Hulls
175
215
235
255
275
295
Corn Stover
175
215
235
255
275
295
Sugarcane Bag.
175
215
235
255
275
295
0
Figure S-15. Total sugars and organic acids compared to TOC and NVR contents of HTC aqueous
products.
9
Table S-1: Organic acids measured in HTC aqueous products, expressed as % of starting dry feedstock.
Averages are shown for replicate experiments. All experiments had 30-min. hold times.
Set
Avg.
Temp.
Temp.
(°C)
(°C)
Tahoe Mix
155
161.5
175
177.6
195
196.0
215
215.6
235
237.2
255
257.5
275
275.8
295
295.2
Loblolly Pine
175
176.9
200
200.9
215
215.5
235
238.7
255
262.2
275
277.0
295
294.9
Pinyon/ Juniper
175
176.2
215
217.8
235
238.9
255
264.0
275
278.2
295
295.5
Sugarcane Bagasse
175
175.6
215
215.5
235
237.6
255
258.8
275
276.8
295
296.5
Corn Stover
175
178.3
215
215.9
235
239.5
255
261.3
275
277.3
295
296.2
Rice Hulls
175
178.6
215
216.8
235
236.2
255
257.4
275
275.8
295
296.3
Formic
Acid, %
Acetic
Acid, %
Levulinic
Acid, %
Lactic
Acid, %
Succinic
Acid, %
Glutaric
Acid, %
Others,*
%
Total,
%
0.11
0.22
0.44
0.83
1.02
0.89
0.18
0.06
0.14
0.40
1.29
2.11
2.71
3.74
3.96
4.56
0.00
0.00
0.03
0.06
0.11
0.18
0.23
0.31
0.02
0.09
0.22
0.21
0.34
1.47
1.61
1.98
0.02
0.02
0.04
0.08
0.10
0.09
0.20
0.26
0.01
0.01
0.02
0.04
0.08
0.09
0.14
0.13
0.03
0.03
0.05
0.07
0.08
0.14
0.30
0.24
0.34
0.78
2.09
3.41
4.44
6.62
6.63
7.53
0.23
0.42
0.67
0.90
0.70
0.26
0.05
0.40
1.46
1.99
3.42
3.51
5.20
4.71
0.00
0.03
0.06
0.14
0.17
0.31
0.32
0.06
0.19
0.33
0.58
1.17
1.53
1.38
0.04
0.06
0.06
0.07
0.14
0.12
0.10
0.02
0.04
0.06
0.07
0.18
0.12
0.13
0.03
0.07
0.07
0.10
0.16
0.20
0.26
0.79
2.27
3.24
5.28
6.03
7.75
6.96
0.34
1.07
0.95
0.81
0.15
0.24
0.66
2.55
4.37
4.97
5.83
5.36
0.01
0.08
0.17
0.25
0.34
0.37
0.09
0.39
0.77
1.63
1.81
2.60
0.08
0.11
0.12
0.16
0.21
0.25
0.03
0.06
0.11
0.20
0.16
0.27
0.02
0.55
0.13
0.23
0.21
0.43
1.23
4.81
6.63
8.23
8.72
9.52
0.21
1.02
0.82
0.39
0.17
0.06
1.15
3.78
6.05
5.57
8.11
7.47
0.01
0.11
0.24
0.27
0.48
0.52
0.25
0.68
0.82
2.26
2.31
2.00
0.04
0.10
0.06
0.21
0.22
0.14
0.02
0.08
0.10
0.25
0.26
0.18
0.11
0.12
0.15
0.22
0.30
0.46
1.79
5.89
8.24
9.16
11.85
10.84
0.15
1.43
0.84
0.57
0.09
0.04
0.79
4.81
5.81
6.61
8.43
8.01
0.01
0.15
0.23
0.33
0.50
0.55
0.19
0.55
0.63
1.51
1.66
1.41
0.65
0.73
0.07
0.35
0.37
0.25
0.06
0.20
0.20
0.38
0.24
0.25
0.03
0.16
0.16
0.23
0.30
0.36
1.88
8.04
7.95
9.98
11.59
10.87
0.17
0.79
0.74
0.88
0.13
0.26
0.76
2.70
4.17
4.42
6.51
4.82
0.01
0.08
0.17
0.22
0.38
0.33
0.05
0.31
0.49
0.95
1.61
2.37
0.01
0.12
0.07
0.12
0.21
0.28
0.02
0.05
0.08
0.14
0.16
0.29
0.11
0.08
0.11
0.21
0.25
0.40
1.12
4.13
5.82
6.93
9.26
8.75
* Others acids include maleic, malonic, methane sulfonic (MSA), and oxalic acids
10
Table S-2: Sugars in HTC aqueous products, expressed as % of starting dry feedstock. Averages are
shown for replicate experiments. All experiments had 30-min. hold times.
Set
Avg.
Galactose,
Fructose,
LevoGlucose,
5-HMF, Furfural, Erythritol, Others,*
Temp
Temp
Xylose,
Inositol,
glucosan,
Pinitol, %
%
%
%
%
(°C)
(°C)
Mannose, % Arabinose, %
%
Tahoe mix
155
161.5
0.03
0.48
1.13
0.00
0.01
0.04
0.00
0.18
175
177.6
0.13
2.20
1.18
0.02
0.10
0.30
0.03
0.36
195
196.0
1.25
4.37
1.12
0.14
1.62
1.49
0.06
0.03
215
215.6
0.91
0.55
0.32
0.36
3.86
2.00
0.07
0.21
235
237.2
0.53
0.05
0.17
0.45
3.64
1.40
0.17
0.22
255
257.5
0.14
0.03
0.09
0.46
2.43
0.82
0.29
0.10
275
275.8
0.02
0.02
0.04
0.19
0.28
0.20
0.17
0.06
295
295.2
0.01
0.01
0.01
0.02
0.09
0.03
0.04
0.10
Loblolly Pine
175
176.9
0.05
2.05
1.18
0.01
0.06
0.24
0.09
0.43
200
200.9
1.29
3.82
0.88
0.17
1.94
1.72
0.05
0.23
215
215.5
0.90
0.40
0.19
0.25
3.70
2.11
0.06
0.16
235
238.7
0.98
0.01
0.09
0.52
4.41
1.52
0.52
0.30
255
262.2
0.01
0.01
0.20
0.43
1.71
0.81
0.60
0.08
275
277.0
0.02
0.01
0.18
0.27
0.35
0.34
0.46
0.47
295
294.9
0.02
0.01
0.09
0.06
0.08
0.06
0.14
0.44
Pinyon/ Juniper
175
176.2
0.05
1.20
1.56
0.05
0.06
0.25
0.03
0.29
215
217.8
0.26
0.10
0.37
0.33
1.67
1.40
0.04
0.17
235
238.9
0.13
0.00
0.29
0.62
1.75
0.79
0.33
0.31
255
264.0
0.02
0.02
0.59
0.64
0.83
0.29
0.32
0.09
275
278.2
0.02
0.00
0.57
0.24
0.22
0.09
0.27
0.16
295
295.5
0.04
0.00
0.43
0.01
0.08
0.02
0.11
0.49
Sugarcane Bagasse
175
175.6
0.00
1.42
0.33
0.03
0.02
0.51
0.08
0.83
215
215.5
0.20
0.03
0.07
0.31
0.94
3.75
0.01
0.21
235
237.6
0.20
0.01
0.16
0.64
1.98
2.81
0.14
0.70
255
258.8
0.00
0.00
0.06
0.58
1.60
1.35
0.32
0.04
275
276.8
0.00
0.00
0.08
0.25
0.47
0.51
0.30
0.19
295
296.5
0.00
0.01
0.08
0.00
0.12
0.16
0.08
0.22
Corn Stover
175
178.3
0.00
0.57
0.68
0.09
0.04
0.32
0.02
0.52
215
215.9
0.09
0.02
0.08
0.34
0.68
2.17
0.04
0.26
235
239.5
0.03
0.00
0.16
0.52
0.56
0.66
0.19
0.94
255
261.3
0.01
0.00
0.17
0.47
0.47
0.17
0.28
0.69
275
277.3
0.01
0.00
0.15
0.10
0.15
0.02
0.26
0.46
295
296.2
0.00
0.02
0.11
0.06
0.08
0.01
0.07
0.87
Rice Hulls
175
178.6
0.09
0.43
0.45
0.03
0.03
0.23
0.02
0.18
215
216.8
0.23
0.06
0.10
0.28
0.89
2.68
0.02
0.20
235
236.2
0.21
0.00
0.18
0.63
1.71
1.68
0.20
0.56
255
257.4
0.05
0.03
0.11
0.78
1.79
0.83
0.26
0.03
275
275.8
0.00
0.00
0.14
0.40
0.35
0.26
0.25
0.27
295
296.3
NM
NM
NM
NM
NM
NM
NM
NM
* Other sugars include sucrose/ trehalose, maltitol, erythritol, mannitol/glycerol, and arabitol.
11
Total,
%
1.88
4.32
10.09
8.28
6.63
4.35
0.99
0.31
4.12
10.10
7.77
8.35
3.85
2.10
0.89
3.49
4.35
4.22
2.80
1.57
1.18
3.23
5.52
6.63
3.94
1.80
0.68
2.25
3.67
3.07
2.27
1.15
1.20
1.47
4.47
5.16
3.88
1.67
NM