FRACTIONATION OF LIGNOCELLULOSIC BIOMASS FEEDSTOCKS Lisette Tenlep and
FRACTIONATION OF LIGNOCELLULOSIC BIOMASS FEEDSTOCKS Lisette Tenlep and Douglas Raynie Chemistry & Biochemistry South Dakota State University
From ethanol to cellulosic ethanol Ethanol is a potential fuel transportation Production of ethanol in the US Corn wet mills Corn dry mills US Department Of Energy goals: Biological ways to produce ethanol Make biobased ethanol practical and cost competitive by 20 12 Replace 30% of gasoline by 2030 Development of feedstocks to biofuel industry
Potential lignocellulosic biomass resources Crop residues Warm-season Grasses Cool-season Grasses Other crops Corn stover Switchgrass Intermediate Wheatgrass Forage sorghum Soybean Big bluestern Red canarygrass Sweet sorghum Wheat straw Indiangrass Smooth bromegrass Pearl millet Rye straw Little bluestern Timothy Sudangrass Barley straw Prairiecord grass
Understanding plant cell walls Components of cell walls Cellulose Hemicellulose Lignin Other Extractives Resins, fatty acids, salts, minerals…
Bioethanol production process diagram Simplified fermentation reaction equation for glucose C 6 H 12 O 6 Glucose 2 CH 3 CH 2 OH + 2 CO 2 Ethanol Carbon dioxide http: //www 1. eere. energy. gov/biomass/abcs_biofuels. html
Pretreatment methods Physical methods Physicochemical methods Steam pretreatment, liquid hot-water pretreatment, ammonia fiber explosion (AFEX)… Biological methods Chipping, milling, grinding Lignin-degrading microbes are applied to the lignocellulose materials. Chemicals methods Alkaline pretreatment, dilute acid pretreatment, organic or aqueous-organic solvent mixture
Organosolv processes background Organic or aqueous-organic solvent mixture Inorganic acid catalyst (H 2 SO 4 or HCl) Dissolution of the hydrolyzed lignin Lignin is recovered in the organophilic phase Solubilization of most of the hemicellulose Used to break the internal lignin and hemicellulose bonds Hemicellulose is recovered in the aqueous phase Cellulose is retained in the biomass residue
Organosolv process parameters Temperature: 140ºC Static time: 56 minutes Pressure: 1000 psi Weight ratio of liquor to biomass is 10: 1 Two liquor mixtures Solvent bottles Extraction cell MIBK/Et. OH/H 2 O: 44/32/24 MIBK/Et. OH/H 2 O: 16/34/50 H 2 SO 4 conc: 0. 025– 0. 1 M Collection bottle Dionex Accelerated Solvent Extraction system Process modeled after the NREL clean fractionation procedure
Expected results Phase separation of the insoluble MIBK component Two layers Addition of water to the liquor in a ratio of 1. 3 parts water to 1 part liquor Organic phase (lignin) Aqueous phase (hemicellulose) Biomass residue (cellulose and extractives)
Organic phase Aqueous phase Lignin precipitated Lignin isolated after clean fractionation
Lignin distribution after fractionation 100 90 MIBK/Et. OH/H 2 O: 44/32/24 70 60 50 PCG 40 SG 30 DDGS 20 10 0 0. 025 0. 0500000001 H 2 SO 4 concentrations (M) 0. 1100 90 MIBK/Et. OH/H 2 O: 16/34/50 80 Lignin content (%) 80 70 60 50 PCG 40 SG 30 DDGS 20 10 0 0. 025 0. 05 H 2 SO 4 concentrations (M) 0. 1
Hemicellulose distribution after fractionation MIBK/Et. OH/H 2 O: 44/32/24 120 100 80 PCG 60 SG 40 DDGS 20 100 0 0. 025 0. 05 H 2 SO 4 concentrations (M) 0. 1 Hemicellulose content (%) 140 90 MIBK/Et. OH/H 2 O: 16/34/50 80 70 60 50 PCG 40 SG 30 DDGS 20 10 0 0. 025 0. 05 H 2 SO 4 concentrations (M) 0. 1
Biomass residue distribution after fractionation 90 MIBK/Et. OH/H 2 O: 44/32/24 80 70 60 50 PCG 40 SG 30 DDGS 20 10 100 0 0. 025 0. 05 H 2 SO 4 concentrations (M) 0. 1 Biomass residues content (%) 100 90 MIBK/Et. OH/H 2 O: 16/34/50 80 70 60 50 PCG 40 SG 30 DDGS 20 10 0 0. 025 0. 05 H 2 SO 4 concentrations (M) 0. 1
LC characterization of sugars, byproducts and degradation products Column type Aminex HPX-87 P Aminex HPX-87 H Flow rate 0. 6 ml/min Temperature 85°C 65°C Mobile phase Bidistilled H 2 O 0. 005 N H 2 SO 4 Detector RI RI Run time 26 minutes
Organophilic phase (Lignin) Prairiecord grass MIBK/Et. OH/H 2 O : 44/32/24, [H 2 SO 4 ]= 0. 1 M Aminex HPX-87 H column
Aqueous phase (Hemicellulose) Switchgrass MIBK/Et. OH/H 2 O : 44/32/24, [H 2 SO 4 ]= 0. 1 M Aminex HPX-87 H column
Aqueous phase cont’d (Hemicellulose) Switchgrass MIBK/Et. OH/H 2 O : 44/32/24, [H 2 SO 4 ]= 0. 1 M Aminex HPX-87 H column
Carbohydrates distribution (MIBK/Et. OH/H 2 O: 44/32/24) PCG PCG SG SG SG Carbohy drates 0. 025 M H 2 SO 4 0. 05 M H 2 SO 4 0. 1 M H 2 SO 4 DP 4+ 1. 093 3. 061 13. 268 1. 051 2. 796 20. 588 Cellobiose Below dl 0. 155 0. 2155 Below dl 0. 103 0. 268 Glucose 0. 619 0. 745 0. 3685 0. 344 0. 365 0. 8515 Xylose Below dl 1. 006 1. 6265 Below dl 0. 758 2. 0335 Arabinose 518. 076 1228. 759 546. 386 356. 876 1266. 436 473. 577
Carbohydrates distribution (MIBK/Et. OH/H 2 O: 16/34/50) PCG SG Carbohydrates 0. 1 M H 2 SO 4 DP 4+ 3. 827 3. 715 Cellobiose 0. 071 0. 00465 Glucose 0. 551 0. 158 Xylose 0. 794 0. 7875 Arabinose 547. 0635 533. 8335
Arabinose distribution in organophilic phases 1400 1200 Arabinose content (g/l) 1000 800 600 400 200 0 liquor 1 PCG liquor 2 liquor 1 PCG SG organophilic phases / Biomass samples liquor 2 SG
Future work Optimization of the pretreatment Investigation of more liquor mixtures Compositional analysis of all pretreated biomass residues Study the components distribution after these various pretreatments Determination of the amount of carbohydrates present in biomass residues Enzymatic sacharification of preated biomass residues Breakdown of cellulose into glucose
Acknowledgments North Central Regional Sungrant Via funding from DOE, DOT, Verasun, ICM 2010 Center for Bioprocessing Research and Development (CBRD) at SDSU and SDSM&T Chemistry and Biochemistry Biology and Microbiology Agricultural and Biosystems Engineering
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