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 Biological ways to produce ethanol Production of ethanol in the US Corn wet mills Corn dry mills US Department Of Energy goals: 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 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, fats, fatty acids, salts, minerals…

Bioethanol production process diagram Simplified fermentation reaction equation for glucose C6H12O6 2 CH3CH2OH + 2 CO2 Glucose Ethanol Carbon dioxide http://www1.eere.energy.gov/biomass/abcs_biofuels.html

Pretreatment methods Physical methods Physicochemical methods Chipping, milling, grinding Physicochemical methods Steam pretreatment, liquid hot-water pretreatment, ammonia fiber explosion (AFEX)… Biological methods 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 (H2SO4 or HCl) Used to break the internal lignin and hemicellulose bonds Dissolution of the hydrolyzed lignin Lignin is recovered in the organophilic phase Solubilization of most of the hemicellulose 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 MIBK/EtOH/H2O: 44/32/24 MIBK/EtOH/H2O: 16/34/50 H2SO4 conc: 0.025–0.1M Solvent bottles Extraction cell Collection bottle Dionex Accelerated Solvent Extraction system Process modeled after the NREL clean fractionation procedure

Expected results Phase separation of the insoluble MIBK component Addition of water to the liquor in a ratio of 1.3 parts water to 1 part liquor Two layers Organic phase (lignin) Aqueous phase (hemicellulose) Biomass residue (cellulose and extractives)

Lignin precipitated Lignin isolated after clean fractionation Organic phase Organic phase Aqueous phase Aqueous phase Lignin precipitated Lignin isolated after clean fractionation

Lignin distribution after fractionation

Hemicellulose distribution after fractionation

Biomass residue distribution after fractionation

LC characterization of sugars, byproducts and degradation products Column type Aminex HPX-87P Aminex HPX-87H Flow rate 0.6 ml/min Temperature 85°C 65°C Mobile phase Bidistilled H2O 0.005 N H2SO4 Detector RI Run time 26 minutes

Organophilic phase (Lignin) Prairiecord grass MIBK/EtOH/H2O : 44/32/24, [H2SO4 ]= 0.1M Aminex HPX-87 H column

Aqueous phase (Hemicellulose) Switchgrass MIBK/EtOH/H2O : 44/32/24, [H2SO4 ]= 0.1M Aminex HPX-87 H column

Aqueous phase cont’d (Hemicellulose) Switchgrass MIBK/EtOH/H2O : 44/32/24, [H2SO4 ]= 0.1M Aminex HPX-87 H column

Carbohydrates distribution (MIBK/EtOH/H2O:44/32/24) PCG SG Carbohy drates 0.025M H2SO4 0.05M H2SO4 0.1M H2SO4 DP4+ 1.093 3.061 13.268 1.051 2.796 20.588 Cellobiose Below dl 0.155 0.2155 0.103 0.268 Glucose 0.619 0.745 0.3685 0.344 0.365 0.8515 Xylose 1.006 1.6265 0.758 2.0335 Arabinose 518.076 473.577 1228.759 546.386 356.876 1266.436

Carbohydrates distribution (MIBK/EtOH/H2O:16/34/50) PCG SG Carbohydrates 0.1M H2SO4 DP4+ 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

Future work Optimization of the pretreatment Investigation of more liquor mixtures Study the components distribution after these various pretreatments Compositional analysis of all pretreated biomass residues Determination of the amount of carbohydrates present in biomass residues Enzymatic sacharification of preatreated 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