Operation Pretreatment Process of Textile Pretreatment Process of Textile Materials.
Alkaline pretreatment of wheat strawweb.abo.fi/.../11_Hamburg_presentation_Gosselink.pdf ·...
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Alkaline pretreatment of wheat straw “Analytical methods for non-wood raw materials and their products and processes” COST FP0901 meeting, 19-21 August 2010, Hamburg Richard Gosselink , Hans van der Kolk, Paulien Harmsen, Robert Bakker
Transcript of Alkaline pretreatment of wheat strawweb.abo.fi/.../11_Hamburg_presentation_Gosselink.pdf ·...
Alkaline pretreatment of wheat straw
“Analytical methods for non-wood raw materials and their products and processes”
COST FP0901 meeting, 19-21 August 2010, Hamburg
Richard Gosselink, Hans van der Kolk, Paulien Harmsen, Robert Bakker
Outline presentation
� Wheat straw biorefinery
� Alkaline pretreatment
� Analytical tools
� Highlights results
� Available samples for Round Robin COST PF0901
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Wheat straw biorefinery concept
Clark et al. 2006
S L
3
Pretreatment
� Goal� Fractionation of lignocellulosic to cellulose, hemicellulose and
lignin � Make cellulose and hemicellulose fractions more accessible for
enzymatic hydrolysis� Make lignin available for higher-valued products
� Numerous processes � Mechanical, chemical, enzymatic� Acids, alkaline, organic solvents � Combinations thereof
4
Alkaline pretreatment (high pH)
� Alkali induces swelling of biomass, leading to increase of internal surface area
� Disruption of lignin structure (lignin removal)� Reduction of cellulose crystallinity
� Results in improved accessibility of cellulose and hemicellulose towards enzymatic hydrolysis
5
Alkaline pretreatment
� Common alkaline pretreatment route� Base as catalyst (NaOH, Ca(OH)2, ammonia); T<120 °C� Carried out under (close to) atmospheric conditions� Long reaction times (hours)� Need for chemical recycling
� Improve alkaline pretreatment� Apply milder process conditions
• Less formation of degradation products (e.g. inhibitors)• Lower operational costs
� Improve accessibility of sugars to enzymes� Obtain lignin of high purity
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From wheat straw to fermentable sugars
Wheat straw
PretreatmentEnzymatic hydrolysis
Fermentation
Lignin
Ethanol or
ABE
Polymeric sugars
Monomeric sugars
� Pretreatment efficiency� Properties of solid fraction (cellulose-rich)
• Biochemical composition
� Properties of liquid fraction
• Sugars, organic acids and lignins in solution
• Recovery of lignin
� Enzymatic hydrolysis� Conversion of solid fraction
• Glucan to glucose• Xylan to xylose
� Standard procedure
• 50 °C, 120h
• Excess of enzyme (GC220)
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Experimental setup
Base case: 4h alkaline pretreatment in stirred reactor
� Preliminary experiments (2 L, 70 °C)� Base case� Effect NaOH-concentration
� Main experiments (200 L, 90 °C)� Base case � Extrusion� Refining
8
Analytical tools (selection)� Biochemical composition untreated & pretreated straw (solids)
� Extraction (ASE)
� Carbohydrates (HPAEC-PAD)
� Lignin (AIL by weight, ASL by UV)� Ash (TGA, ignition)
� Proteins (N by Kjehldahl or Dumas, AA by UPLC)
� Morphology (SEM)
� Cellulose cristallinity (WAXS)� Liquids
� Carbohydrates (monomers, oligomers)
� Lignin� Fermentation inhibitors (phenolics, organic acids by LC)
� Isolated lignin
� FT-IR � Impurities (carbohydrates, proteins, ash)
� MWD (alkaline SEC)1
� Functional groups (31P NMR)1
0.0 10.0 20.0 30.0 40.0 50.0-100
0
100
200
300
400
500 RG070918 #27 [modified by User, 5 peaks manually assigned] ECD_1nC
min
1 - fucose - 5.2172 - Rhamnose - 12.0003 - Arabinose - 12.800
4 - Galactose - 17.033
5 - Glucose - 19.733
6 - Xylose - 24.0507 - Mannose - 25.6508 - 32.6839 - 34.033
SampleName: Organosolv lignin ARD 1 SampleName: Organosolv lignin ARD 2
3934
- 2
0.1
21
AU
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
Minutes
0.00 2.00 4.00 6.00 8.00 10.00 12.00 14.00 16.00 18.00 20.00 22.00 24.00 26.00 28.00 30.00 32.00 34.00
AliphaticOH Internal std SyringylOH
GuaiacylOH
p-CoumarylOH
COOH
Cond. Arom.OH
1Gosselink, R.J.A. et al. Holzforschung 20109
Pretreatment efficiency Solid fraction
33 36 3844 41
2224 26
3027
20
23 18
1417
0
20
40
60
80
100
Wheatstraw
0% NaOH 6% NaOH 9% NaOH 12% NaOH
Bio
chem
ical
co
mp
osi
tio
n (
wt%
)Other
Ash (TGA)
Lignin
Hemicelluloses
Cellulose
NaOH-conc as wt% dry biomass
10
Pretreatment efficiency Liquid fraction
0,00
0,05
0,10
0,15
0,20
0,25
0,30
0,35
0,40
7009001100130015001700
Wavenumber (cm-1)
Ab
sorb
ance
Wheat straw lignin reference
0% NaOH
6% NaOH
9% NaOH
12% NaOHAromatic skeleton lignin
CO stretching carbohydrates
IR-spectra of lignins isolated from liquid fraction
11
Enzymatic hydrolysis Solid fraction
� Enhanced enzymatic degradability due to pretreatment� Structural changes of wheat straw (e.g. delignification)� Minimal formation of degradation products due to mild conditions
0
20
40
60
80
100
Wheatstraw
0 wt%NaOH
6 wt%NaOH
9 wt%NaOH
12 wt%NaOH
Pol
ysac
char
ide
conv
ersi
on (w
t%)
Glucose
Xylose
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� Pretreatment� Main action is delignification (max 50%)� Minimum degree of hemicellulose and cellulose hydrolysis� Solid fraction enriched with sugars due to pretreatment (from 60% to 75%)� Optimal NaOH concentration 9 wt%
� Lignin � Low purity
� Enzymatic hydrolysis� Conversion of glucan and xylan improved from < 20% to > 80%
� Input for further experiments� Increase T from 70 to 90 °C� NaOH concentration 6-9 wt% NaOH
Summary Base case (2L)
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Experimental setup
Base case: 4h alkaline pretreatment in stirred reactor
� Preliminary experiments (2 L, 70 °C)� Base case
� Main experiments (200 L, 90 °C)� Base case � Extrusion� Refining
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Base case
� Chopped wheat straw (1-2 cm)� 9 wt% NaOH based on dry straw� 4h at 90 °C
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Extrusion
1st DelignificationWhole wheat straw
6 wt% NaOH, 2h, 90°C
2nd Delignification6 wt% NaOH, 2h, 90 °C
� Transport of biomass to RSE (reversed screw element) � Accumulation and compression of material� High compression and shear forces� Material is dry and absorbs added chemicals very well (e.g. NaOH)
� Shortening of fibres and fibrillation
Steam
RSE
Chemicals
FilterSteam
RSE
Chemicals
FilterSteamSteam
RSERSE
Chemicals
Filter
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Refining
1st DelignificationChopped wheat straw
6 wt% NaOH, 2h, 90 °C
2nd Delignification6 wt% NaOH, 2h, 90°C
� Shear and compression forces� Increase of surface area� Shortening of fibres and fibrillation� Homogeneous, clean fibres
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Scanning Electron Microscopy
Refining
100 µm
Extrusion
100 µm
Base case
100 µm
Wheat straw
100 µm
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Pretreatment efficiency Solid fraction
33
4551 52
22
2726 2620
1211 9
0
20
40
60
80
100
Wheat straw Base case Extrusion Refining
Bio
hem
ical
co
mp
osi
tio
n (
wt%
)
Other
Ash (TGA)
Lignin
Hemicelluloses
Cellulose
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Pretreatment efficiency Liquid fraction
� Direct analysis of sugar monomers
� After acid hydrolysis, 3h, 100°C
� Substantial increase of sugars
� Liquid fraction� Sugars mainly present as
oligomers (total 6%)
Total sugar release
0%
1%
2%
3%
4%
5%
6%
0 1 2 3 4
Time (h)
Su
gar
s (w
t% d
ry s
traw
)
Alkaline: Oligomers and monomers
0.0
0.5
1.0
1.5
2.0
2.5
Rhamnose Arabinose Galactose Glucose Xylose Mannose
Co
nce
ntr
atio
n (
g/l)
Alk-1-L1
Alk-1-L2
Alk-1-L3
Alk-1-L4
Alkaline: Monomers
0.000
0.005
0.010
0.015
0.020
0.025
Rhamnose Arabinose Galactose Glucose Xylose Mannose
Co
nce
ntr
atio
n (
g/l)
Alk-1-L1
Alk-1-L2
Alk-1-L3
Alk-1-L4
20
Amounts 100x lower
Pretreatment efficiency Liquid fraction
� Liquid fraction� Acetic acid primary fermentation inhibitor� Lactic acid present� Phenolic compounds present at very low levels
Mel
kzuu
r -
8.56
8
Azi
jnzu
ur -
10.
118
26.6
19
AU
-0.002
0.000
0.002
0.004
0.006
0.008
0.010
0.012
0.014
0.016
0.018
0.020
0.022
Minutes2.00 4.00 6.00 8.00 10.00 12.00 14.00 16.00 18.00 20.00 22.00 24.00 26.00 28.00 30.00 32.00 34.00 36.00 38.00
AU
0 .00
0.01
0.02
0.03
0.04
Minutes
2 .00 4.00 6.00 8.00 10.00 12.00 14.00 16.00 18.00 20.00 22.00 24.00 26.00 28.00 30.00 32.00
Sy
rin
gic
Ac
id -
3.1
78
Sy
rin
ga
lde
hy
de
- 5
.96
7
Co
um
ari
c A
cid
- 7
.15
6
Fe
rulic
Ac
id -
10
.35
5
tra
ns
-Cin
na
mic
Ac
id I
S -
25
.82
0
21
Pretreatment efficiency Liquid fraction
0,00
0,05
0,10
0,15
0,20
0,25
0,30
0,35
0,40
6508501050125014501650
Wavenumber (cm-1)
Ab
sorb
ance
Wheat straw lignin Base caseExtrusionRefining
Aromatic skeleton lignin
CO stretching carbohydrates
IR-spectra of lignins isolated from liquid fraction
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Lignin: Chemical composition
� Formation of lignin carbohydrate complexes (LCC)?
1 2 1 2 110 7
13 13 18
75 8075 73 68
0
20
40
60
80
100
Ligninbase case
Ligninbase case(conical)
LigninExtrusion
(B)
Ligninrefining(atm P)
Ligninrefining(elev P)
Bio
chem
ical
co
mp
osi
tio
n (
wt%
)
Other
Ash (TGA)
Lignin
Hemicelluloses
Cellulose
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Lignin: MWD by alkaline SEC
321918810PD
28000170001800053008100Mw (Da)
8909001000690700Mn (Da)
Refining (elevP)
Refining (atmP)
ExtrusionBase case
Reference lignin1Parameter
� Depending on pretreatment method different lignins obtained
� Biomass more accessible due to mechanical pretreatment: less degradation of lignins?
1Soda wheat straw lignin supplied by Granit SA24
Lignin: Functional groups by 31P NMR
31P NMR analysis performed by VTT
IS = Endo-N-Hydroxy-5-norbornene-
2,3-dicarboximide
Amounts of different hydroxyl group species (mmol/g) in lignin Sample ID Aliphatic
OH Aromatic
OH S+C G H Carboxylic
acid Total OH
Base case 3,72 1,14 0,30 0,62 0,22 0,89 5,75 Refining (atmP) 4,00 0,49 0,03 0,37 0,09 0,57 5,05 Refining (elevP) 3,97 0,85 0,24 0,48 0,14 0,68 5,50 S + C = Syringyl + Condensed phenolic units, G = Guaiacyl phenolic units and H = p-Hydroxyphenyl phenolic units
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Pretreatment efficiency
20-30%20-30%<10%Sugars in liquid fraction
70-80%70-80%40-50%Delignification
60-65%60-65%70-75%Yield solid fraction
RefiningExtrusionBase case
� Extrusion and refining comparable results� Higher degree of delignification accompanied by loss of
sugars by hydrolysis
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Enzymatic hydrolysis Solid fraction
0
20
40
60
80
100
Wheat straw Base case Extrusion Refining
Po
lysa
cch
arid
e co
nve
rsio
n (
wt%
)
Glucose
Xylose
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Conclusions
� Alkaline pretreatment excellent for� Delignification (40-50%)� Improvement of enzymatic degradability (from 20 to 70-80%)
� Added value extrusion or refining� More delignification (70-80%)� Further improvement of enzymatic degradability (from 20 to 100%)
� Different lignins produced� Moderate purity (80%)� Molar mass relatively high
� Economic feasibility of combined mechanical/alkaline pretreatment depends on value of lignin produced
� Analytical tools suitable for process development
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Available samples for Round Robin
� Wheat straw (kg)
� Base case: Alkaline pretreated wheat straw (kg)� Neutralised + washed + stored @ -20°C
� Black liquor stored @ -20°C (kg)
� Isolated soda wheat straw lignin (100-200g, expectedearly September)
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Acknowledgements
� Biosynergy www.biosynergy.eu
� Biobutanol www.biobutanol.nl
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www.biosynergy.eu
