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Transcript
Value Added Chemicals from Sugar Feedstocks Professor Ray Fort Department of Chemistry Based on “Top Value Added Chemical from Biomass Vol. 1: Results of Screening for Potential Candidates from Sugars and Synthesis Gas” Eds. T. Werpy and G. Petersen Pacific Northwest Laboratory And National Renewable Energy Laboratory Criteria for Selecting Chemicals Obtainable from sugars derived from cellulose, hemicellulose, or starch At least two functional groups [Potentially] convertible to high value chemicals Data on [potential] market value Potential to become super-commodity chemicals The Winners OH HO2C CO2H HO2C CO2H OH OH HO2C HO2C O CO2H CO2H Furan dicarboxylic acid OH OH Glucaric acid CO2H (S)-Malic acid Fumaric acid Succinic acid HO2C HO2C CO2H NH2 Glutamic acid The Winners HO HO2C HO2C CO2H O OH OH HO Hydroxybutyrolactone Levulinic acid Itaconic acid OH OH HO OH OH OH Glycerol OH Xylitol pseudochiral center OH HO2C OH OH Arabinitol OH OH OH HO OH HO Sorbitol OH O O Hydroxypropionic acid These compounds divide fairly well into two groups: Those with the same carbon number and carbon skeleton as the sugars Those with fewer carbons or altered carbon skeletons All of the first group are typically produced by simple chemical methodology. For example: Sorbitol by catalytic hydrogenation of glucose Levulinic acid by acid catalyzed dehydration of sugars Glucaric acid by oxidation of starch with nitric acid or hypochlorite Xylitol by catalytic hydrogenation of xylose With one exception, all of the second group are produced biologically. For example: Glycerol by yeast fermentation of sugars, (and by hydrolysis of fats and oils) Glutamic acid by fermentation of glucose or xylose with B. subtilis or genetically modified E. coli Hydroxypropionic acid by anaerobic fermentation of glucose OH HO2C CO2H Succinic acid HO2C Fumaric acid CO2H HO2C CO2H (S)-Malic acid Overexpression of succinate has been engineered in numerous strains of E. coli Knocking out other NADH consuming pathways increases yield, up to 130% Some strains will utilize xylose as well as glucose Purity of feedstock an issue when using biomass: phenolics from lignin inactivate bugs Flow systems with immobilized bacteria have been tested Primary Transformations of Succinic Acid H OH HO HO2C RNH2 CO2H N H2O R H H2O O O O O Biochemical Pathway to Itaconic Acid CO2 O2C Glucose Itaconate O2C CoAS CO2 O CH3 CH3 Pyruvate Acetyl CoA CO2 CO2 CO2 O2C CO2 O O2C Aconitate CO2 HO O2C Oxaloacetate Citrate CO2 CO2 H2O Itaconic acid secreted by fungi to acidify their environment Chief fungus employed is Aspergillus terreus With glucose substrate, yields are 40-60% Five-carbon sugars give only 15-30% Isomerization to the more stable citraconic acid is a problem HO2C CO2H Primary Transformations of Itaconic Acid Direct polymerization ? HO2C CO2H H RNH2 H2O HO OH R H H2O O O N O O Major Issues Startup requires large capital investment Petroleum-based competitors still relatively cheap Competition from biomass-to-fuel Heterogeneity, purity of feedstocks Relative fragility of bacteria, fungi Thanks to my colleagues Joe Genco and Barbara Cole for helpful discussions.