Comparative sugar recovery and fermentation data following pretreatment of poplar wood by leading technologies

Abstract

and the University of California at Riverside, leading pretreatment technologies based on ammonia fiber expansion, aqueous ammonia recycle, dilute sulfuric acid, lime, neutral pH, and sulfur dioxide were applied to a single source of poplar wood, and the remaining solids from each technology were hydrolyzed to sugars using the same enzymes. Identical analytical methods and a consistent material balance methodology were employed to develop comparative performance data for each combination of pretreatment and enzymes. Overall, compared to data with corn stover employed previously, the results showed that poplar was more recalcitrant to conversion to sugars and that sugar yields from the combined operations of pretreatment and enzymatic hydrolysis varied more among pretreatments. However, application of more severe pretreatment conditions gave good yields from sulfur dioxide and lime, and a recombinant yeast strain fermented the mixed stream of glucose and xylose sugars released by enzymatic hydrolysis of water washed solids from all pretreatments to ethanol with similarly high yields. An Agricultural and Industrial Advisory Board followed progress and helped steer the research to meet scientific and commercial needs.

Wood Based Lignin Reactions Important to the Biorefinery and Pulp and Paper Industries

“…No matter the pretreatment method employed or the wood composition, lignin is a major constituent that results in enzymes' decreased ability to hydrolyze plant cell walls (Chang and Holtzapple 2000;Chen and Dixon 2007;Dien 2009;Vermerris et al 2007;Wyman 2009). …”

Robustness of two-step acid hydrolysis procedure for composition analysis of poplar

“…The two step acid hydrolysis procedure is the benchmark for measuring the amounts of sugars in the form of cellulose and hemicellulose, and lignin in lignocellulosic biomass feedstocks and accounting for their fate as biomass progresses through pretreatment, enzymatic hydrolysis, fermentation, and other steps of biological processing of biomass Wyman et al, 2009). Furthermore, because sugar mass balances hinge on accurate compositional analysis, understanding uncertainties inherent in this procedure and factors that affect measured values can be valuable in interpreting the resulting compositional data .…”

Not Just Lumber—Using Wood in the Sustainable Future of Materials, Chemicals, and Fuels

“…16 In lignocellulosic biofuels research, resistance to saccharification is often termed ''recalcitrance.'' Treatments that expose the biomass to elevated temperatures and chemicals such as dilute sulfuric acid, 17 mixtures of organic solvents (such as methyl isobutyl ketone, ethanol, and water), which is also called organosolv, 18 and sulfite 19 have been shown to overcome recalcitrance and enhance saccharification yields of the resulting residues by increasing the accessibility of cellulose to enzymes. The solubilized sugar stream produced from enzymatic hydrolysis, called hydrolysate, is then subjected to additional biological or chemical catalytic upgrading to produce desired fuel molecules.…”