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1
Auburn UniversityBiomass Refining CAFI
Corn stover
Corn stover
Wood chip
Bagasse
Rice straw
Sawdust
Biomass
Ethanol F
uel
2
Auburn UniversityBiomass Refining CAFI
0
5
10
15
20
25
30
35
0 5 10 15 20 25 30
% Xylan
% L
ign
in
Comparison among various feedstock
Lose lot of sugarsIn liquid stream/Low pretreatment yield
(considering solid only)
Very hard to treatOptimum
Corn StoverLow Lignin Hybrid PoplarHigh Lignin Hybrid Poplar
(Courtesy: US-DOE website)http://www.eere.energy.gov/biomass/progs/search1.cgi
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Auburn UniversityBiomass Refining CAFI
Substrate Dependency on the Effect of Pretreatment by Aqueous Ammonia
Rajesh Gupta, Tae Hyun Kim and Y. Y. LeeDepartment of Chemical Engineering
Auburn University
4
Auburn UniversityBiomass Refining CAFI
Outline
• Difference in physical & chemical features of biomass responsible for different results in pretreatment.
• Effect of xylanase supplementation on ARP treated biomass.
• How the cellulosic part in biomass affected during different pretreatment.
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Auburn UniversityBiomass Refining CAFI
Comparison among various feedstock
Low lignin Poplar seems the best choice among three feed stocks.
Composition of Untreated Biomass
36%
21%17%
21%
14%
29%
18%
45% 44%
0%
10%
20%
30%
40%
50%
Glucan Xylan Lignin
Component
co
mp
os
itio
n
Corn Stover
Low Lignin Poplar
High Lignin Poplar
6
Auburn UniversityBiomass Refining CAFI
Corn Stover
Low Lignin PoplarHigh Lignin Poplar
Comparison among various feedstock
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Auburn UniversityBiomass Refining CAFI
Processes with Ammonia
SAA(Soaking in Aqueous Ammonia)
• Batch Reactor
• Low Temperature
• Long Pretreatment time (several hours)
ARP(Ammonia Recycle Percolation)
• Flowthrough Reactor
• High Temperature
• Short Pretreatment time (several min.)
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Auburn UniversityBiomass Refining CAFI
Effect of SAA treatment
Treatment Conditions: 15% Ammonia, 1:6 S:L & 12 hrs soaking time
Temperature: 60'C
0
20
40
60
80
100
0 20 40 60 80
Time(hrs)
% G
luc
an
Dig
es
tib
ilit
y
Corn Stover
Enzyme Loading: Cellulase (15FPU/g glucan) + Cellobiase (30CBU/g glucan)
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Auburn UniversityBiomass Refining CAFI
Temperature: 120°C
0%
20%
40%
60%
80%
100%
0 20 40 60 80
Time(hrs)
Glu
can
Dig
esti
bil
ity
High Lignin Poplar
Low Lignin Poplar
Temperature: 150°C
0%
20%
40%
60%
80%
100%
0 20 40 60 80
Time(hrs)
Glu
can
Dig
esti
bil
ity
High Lignin Poplar
Low Lignin Poplar
Effect of SAA treatment
Treatment Conditions: 15% Ammonia, 1:10 S:L & 24hrs soaking time
Effective treatment temperature for SAA is much higher for Hybrid poplar
than Corn stover.
Enzyme Loading: Cellulase (15FPU/g glucan) + Cellobiase (30CBU/g glucan)
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Auburn UniversityBiomass Refining CAFI
Effect of SAA treatment
In comparison to Corn stover, higher delignification / xylan removal is required in case
of High lignin Poplar for attaining the good digestibility.
Corn Stover
21
181717
9
6
0
5
10
15
20
25
Untreated Case-1 Case-2
% X
yla
n/L
ign
in
Xylan
Lignin
High Lignin Poplar
1413
11
29
18
15
0
5
10
15
20
25
30
35
Untreated Case-1 Case-2
% X
ylan
/Lig
nin
Xylan
Lignin
~15-20% Xylan removal~50% Delignification
Corn Stover72hrs Glucan Digstibility
17
80
90
0
20
40
60
80
100
Untreated Case-1 Case-2
% D
iges
tibili
ty
High Lignin Poplar72hrs Glucan Digestibility
4
29 31
0
20
40
60
80
100
Untreated Case-1 Case-2
% D
iges
tibili
ty
Enzyme Loading: Cellulase (15FPU/g glucan) + Cellobiase (30CBU/g glucan)
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Auburn UniversityBiomass Refining CAFI
ARP (Ammonia Recycle Percolation) Treatment
Optimum chosen treatment condition:
Corn Stover:
Temperature : 170°C
Reaction time : 20min.
Ammonia Conc.: 15%
Liquid : Solid : 3.33 : 1
Hybrid Poplar:
Temperature : 185°C
Reaction time : 27.5min.
Ammonia Conc.: 15%
Liquid : Solid : 3.667 : 1
12
Auburn UniversityBiomass Refining CAFI
Effect of ARP Treatment
Xylan Removal
21%
18%
14%
10%
14%
10%
0%
5%
10%
15%
20%
25%
Corn Stover Low Lignin Poplar High Lignin Poplar
Feed stock
Treated Biomass
Lignin Removal
17%
21%
29%
5%
15%
18%
0%
5%
10%
15%
20%
25%
30%
35%
Corn Stover Low Lignin Poplar High Lignin Poplar
Feed stock
Treated Biomass
72hrs Glucan Digestibility
63%
88%90%
0%
20%
40%
60%
80%
100%
Corn Stover Low Lignin Poplar High Lignin Poplar
(15FPU + 30 CBU)
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Auburn UniversityBiomass Refining CAFI
Effect of Reaction time on Hybrid Poplar (High Lignin Poplar) during ARP treatment
Component Removal
5%
10%
15%
20%
0 20 40 60 80 100
Reaction time(min)
Xyl
an/L
ign
in R
emai
nin
g
Lignin Remaining
Xylan Remaining
Digestibility (15FPU+30CBU)
20%
25%
30%
35%
40%
45%
50%
55%
0 20 40 60 80 100
Reaction time(min)
Glu
can
/Xyl
an
Dig
esti
bil
ity
Glucan Digestibility
Xylan Digestibility
XRD Plots
0
500
1000
1500
2000
2500
3000
3500
4000
10 15 20 25 30 35 402 θ
Inte
nsi
ty(a
.u.)
Untreated(CrI: 64.41)
27.5min (CrI: 75.45)
82.5min (CrI: 76.32)
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Auburn UniversityBiomass Refining CAFI
Effect of Ammonia flow on Hybrid Poplar (High Lignin Poplar) during ARP treatment
Digestibility seems more sensitive towards xylan removal than delignification.
Component Removal
5%
10%
15%
20%
0 2 4 6 8
Flow rate(ml/min)
Xyl
an/L
ign
in
Rem
ain
ing
Lignin Remaining
Xylan Remaining
Digestibility( 15FPU+30CBU)
20%
25%
30%
35%
40%
45%
50%
55%
0 2 4 6 8
Flow rate(ml/min)
Glu
can
/Xyl
an
Dig
esti
bil
ity
Glucan Digestibility
Xylan Digestibility
XRD Plots
0
500
1000
1500
2000
2500
3000
3500
10 15 20 25 30 35 40
2 θ
Inte
ns
ity
(a.u
.)
Untreated(CrI: 64.41)
2ml/min (CrI: 75.45)
7.5ml/min (CrI: 70.43)
15
Auburn UniversityBiomass Refining CAFI
Effect of Temperature on Hybrid Poplar (High Lignin Poplar) during ARP treatment
Component Removal
5%
10%
15%
20%
165 170 175 180 185 190 195 200
Temperature('C)
Xyl
an/L
ign
in
Rem
ain
ing
Lignin Remaining
Xylan Remaining
Digestibility( 15FPU+30CBU)
20%
25%
30%
35%
40%
45%
50%
55%
165 170 175 180 185 190 195 200
Temperature('C)
Glu
can
/Xyl
an
Dig
esti
bil
ity
Glucan Digestibility
Xylan Digestibility
XRD Plots
0
500
1000
1500
2000
2500
3000
3500
10 15 20 25 30 35 402 θ
Inte
nsi
ty(a
.u.)
Untreated(CrI: 64.41)
175°C (CrI: 75.25%)
195°C(CrI: 73.70%)
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Auburn UniversityBiomass Refining CAFI
Effect of Temperature on Hybrid Poplar (Low Lignin Poplar) during ARP treatment
Component Removal
18%
16%
14%
21%
16%15%
0%
5%
10%
15%
20%
25%
Untreated 170'C 185'C
Xylan Remaining
Lignin Remaining
Enzyme Loading: Cellulase (15FPU/g glucan) + Cellobiase (30CBU/g glucan)
Increase of temperature from 170°C to 185°C does not affect xylan/lignin removal, but increases cellulase accessibility to cellulosic part in biomass
Digestibility
0%
74%
87%
0%
69%73%
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Untreated 170'C 185'C
72hrs Glucan Digestibility
72hrs Xylan Digestibility
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Auburn UniversityBiomass Refining CAFI
Effect of xylanase supplementation onARP treated Corn Stover
Enzyme Loading:C+β-G : Cellulase (15FPU/g glucan) + Cellobiase (30CBU/g glucan)C+ β-G +X : Cellulase (15FPU/g glucan) + Cellobiase (30CBU/g glucan) + Xylanase (31.3mg protein/g glucan)
Glucan Digestibility
0%
20%
40%
60%
80%
100%
0 10 20 30 40 50 60 70 80
Time(hr)
% G
luca
n E
quiv
alen
t
C+β-G C+β-G+X
Xylan Digestibility
0%
20%
40%
60%
80%
100%
0 10 20 30 40 50 60 70 80
Time(hr)%
Xyl
an E
qu
ival
ent
C+β-G C+β-G+X
Xylan DigestibilityGlucan Digestibility
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Auburn UniversityBiomass Refining CAFI
Effect of xylanase supplementation on Glucan Digestibilityof Hybrid Poplar
0%
20%
40%
60%
80%
100%
0 20 40 60 80
Time(hr)
% G
luca
n E
qu
ival
ent
C+β-G C+β-G+X
0%
20%
40%
60%
80%
100%
0 20 40 60 80
Time(hr)%
Glu
ca
n E
qu
iva
len
t
C+β-G C+β-G+X
High Lignin Poplar Low Lignin Poplar
Enzyme Loading:C+β-G : Cellulase (15FPU/g glucan) + Cellobiase (30CBU/g glucan)C+ β-G +X : Cellulase (15FPU/g glucan) + Cellobiase (30CBU/g glucan) + Xylanase (31.3mg protein/g glucan)
19
Auburn UniversityBiomass Refining CAFI
Enzyme Loading:C+β-G : Cellulase (15FPU/g glucan) + Cellobiase (30CBU/g glucan)C+ β-G +X : Cellulase (15FPU/g glucan) + Cellobiase (30CBU/g glucan) + Xylanase (31.3mg protein/g glucan)
0%
20%
40%
60%
80%
100%
0 10 20 30 40 50 60 70 80
Time(hr)
% X
ylan
Equ
ival
ent
C+β-G C+β-G+X
0%
20%
40%
60%
80%
100%
0 10 20 30 40 50 60 70 80
Time(hr)
% X
ylan
Eq
uiv
alen
t
C+β-G C+β-G+X
High Lignin Poplar Low Lignin Poplar
Effect of xylanase supplementation on Xylan Digestibilityof Hybrid Poplar
Near 100% Glucan & xylan digestibility can be achieved for ARP treated Low lignin Poplar with xylanase supplementation.
20
Auburn UniversityBiomass Refining CAFI
Effect of xylanase loading
72hrs Glucan Digestibility
0%
20%
40%
60%
80%
100%
0 10 20 30 40
Xylanase Loading(mg/g glucan)
Dige
stib
ility Low Lignin Poplar
High Lignin Poplar
72hrs Xylan Digestibility
0%
20%
40%
60%
80%
100%
0 10 20 30 40
Xylanase Loading(mg/g glucan)Di
gest
ibili
ty Low Lignin Poplar
High Lignin Poplar
Cellulase loading: 15FPU/g glucanβ-G loading : 30CBU/g glucan
In ARP treated Low lignin Poplar, there is some easily digestible xylan.
In High lignin Poplar, minimum amount of xylan removal is required for betteraccessibility of cellulase.
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Auburn UniversityBiomass Refining CAFI
Basis: 100g dry biomass
Enzyme LoadingWithout xylanase : Cellulase (15FPU/g glucan) + Cellobiase (30CBU/g glucan)With xylanase : Cellulase (15FPU/g glucan) + Cellobiase (30CBU/g glucan) + Xylanase (31.3mg protein/g glucan)
Yield from different ARP treated Biomass
* Processing of liquid stream is eliminated.* High fermentation efficiency due to absence of inhibitor/toxins
* There is a need to increase the xylanase activity in cellulase* Low pretreatment severity/Low pretreatment cost
GlucanXylan
Glucan Xylan
Sugar YieldWithout Xylanase With Xylanase Without Xylanase With Xylanase Without Xylanase With Xylanase
Glucan 31.38 32.88 29.42 43.23 19.96 28.45Xylan 7.51 8.89 8.99 12.90 4.91 7.05
Sugar Yield 84.72% 91.00% 66.24% 96.77% 49.30% 70.35%38.89 41.77 38.42 56.13 24.87 35.49
67.63% 72.64% 61.21% 89.43% 42.96% 61.31%
Corn Stover Low Lignin Poplar High Lignin Poplar
79.83% 92.42% 87.15%
Feed Stock36.1 44.91 43.821.4 17.85 14.09
After ARP treatment
35.6 44.5 40.8410.3 13.5 9.61
Overall Sugar YieldTotal Sugars(g)/100g biomass
After Enzymatic Hydrolysis
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Auburn UniversityBiomass Refining CAFI
Solid remaining after treatment
100% 99%92%
0%
20%
40%
60%
80%
100%
120%
Untreated Cotton ARP treated Cotton Sulfuric acid treatedCotton
Treatment Conditions :
ARP treatment: 15% NH3, 175°C & 20min Rx. Time (Flow through)
Acid treatment: 0.05% H2SO4, 175°C & 30min Rx Time (Batch)
How Cellulose is Affected in Pretreatment
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Auburn UniversityBiomass Refining CAFI
How Cellulose is Affected in Pretreatment
Enzyme loading: 15FPU Cellulase + 30CBU β-G
Glucan Digestibility
0%
20%
40%
60%
80%
0 25 50 75 100Time(hr)
% G
luc
an
Eq
uiv
ale
nt
Untreated Cotton
ARP treated Cotton
Sulfuric acid treatedCotton
24
Auburn UniversityBiomass Refining CAFI
Absorbance with DNS reagent
0.06750.0165
0.857
0
0.2
0.4
0.6
0.8
1
Untreated Cotton ARP treated Cotton Sulfuric acid treated Cotton
How Cellulose is Affected in Pretreatment
25
Auburn UniversityBiomass Refining CAFI
0
500
1000
1500
2000
2500
10 15 20 25 30 35 40
2θ
Inte
sit
yHow Cellulose is Affected in Pretreatment
Untreated Cotton(77.1)
ARP treated Cotton(83.4)
Acid treated Cotton(81.35)
XRD Plots
Lower Crystallinity More Endo glucanase action
Higher Digestibility
(a.u
.)
26
Auburn UniversityBiomass Refining CAFI
How Cellulose is Affected in Pretreatment
• Any pretreatment reagent( Ammonia/Acid) first attacks the amorphous part of cellulose & increase the crystallinity.
• Ammonia, being a weak base, cannot hydrolyse the crystalline part of cellulose and removes very little cellulose.
• H2SO4, being a strong acid, hydrolyze the crystalline cellulose as well and that’s why more cellulose is lost into liquid.
AmmoniaDoes not affect Cellulosic part
in biomass
Better sugar yieldin pretreatment
27
Auburn UniversityBiomass Refining CAFI
Summary
• Lignin/xylan content plays an important role in pretreatment of lignocellulosic biomass.
• Without xylanase supplementation, the overall sugar yield with ARP treatment is seen in the order: Corn Stover > Low-lignin poplar > High-lignin poplar (~68%) (~61%) (~43%)
• With xylanase supplementation, the overall sugar yield with ARP treatment is seen in the order:Low-lignin poplar> Corn Stover> High-lignin poplar
(~90%) (~73%) (~62%)
28
Auburn UniversityBiomass Refining CAFI
Summary
• Without xylanase supplementation, a certain degree of xylan/lignin removal is necessary in pretreatment to achieve acceptable level of digestibility.
• With xylanase supplementation, high digestibility and overall yield can be attained without removing much xylan/lignin during the ARP treatment.
• Higher xylanase activity in cellulase will improve the overall yield and economics of cellulosic ethanol process drastically.
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Auburn UniversityBiomass Refining CAFI
Future Work
• To compare the economics of following two bio-ethanol production processes using ARP pretreatment:* Severe pretreatment conditions/Processing of
liquid stream/No xylanase supplementation * Mild pretreatment conditions/No sugars in liquid
stream/ xylanase supplementation• To optimize the ARP pretreatment conditions for
different feedstocks with xylanase supplementation.• To characterize the changes in biomass during ARP
pretreatment using FTIR.
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Auburn UniversityBiomass Refining CAFI
Acknowledgements US Department of Energy Office of the Biomass
Program, Contract DE-FG36-04GO14017
CAFI Team:
* University of California, Riverside* Michigan State* Purdue* Texas A&M* University of British Columbia* National Renewable Energy Laboratory
Genencor International
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