Biomimetic Catalysis for Hemicellulose Hydrolysis in Corn Stover

Abstract

Efficient and economical hydrolysis of plant cell wall polysaccharides into monomeric sugars is a significant technical hurdle in biomass processing for renewable fuels and chemicals. One possible approach to overcoming this hurdle is a biomimetic approach with dicarboxylic acid catalyst mimicking the catalytic core microenvironment in natural enzymes. This paper reports developments in the use of a dicarboxylic acid catalyst, maleic acid, for hemicellulose hydrolysis in corn stover. Hemicellulose hydrolysis and xylose degradation kinetics in the presence of maleic acid was compared to sulfuric acid. At optimized reaction conditions for each acid, maleic acid hydrolysis results in minimal xylose degradation, whereas sulfuric acid causes 3-10 times more xylose degradation. These results formed the basis for optimizing the hydrolysis of hemicellulose from corn stover using maleic acid. At 40 g/L dry corn stover solid-loading, both acid catalysts can achieve near-quantitative monomeric xylose yield. At higher solids loadings (150-200 g dry stover per liter), sulfuric acid catalyzed hydrolysis results in more than 30% degradation of the xylose, even under the previously reported optimal condition. However, as a result of minimized xylose degradation, optimized biomimetic hydrolysis of hemicellulose by maleic acid can reach approximately 95% monomeric xylose yields with trace amounts of furfural. Fermentation of the resulting unconditioned hydrolysate by recombinant S. cerevisiae results in 87% of theoretical ethanol yield. Enzyme digestibility experiments on the residual corn stover solids show that >90% yields of glucose can be produced in 160 h from the remaining cellulose with cellulases (15 FPU/g-glucan).

Kinetic modeling analysis of maleic acid‐catalyzed hemicellulose hydrolysis in corn stover

“…Depending upon the nature of the catalysts and the relative severity of the reaction conditions, hemicellulose is depolymerized primarily into either xylan oligomers or monomeric xylose or a mixture of both. We previously reported a new catalytic route for corn stover hemicellulose hydrolysis which employs maleic acid as the catalyst, where the difference in xylose degradation kinetics made maleic acid a superior catalyst to sulfuric acid at high solid-loading reaction conditions (Lu and Mosier, 2007). The preliminary study experimentally identified an optimal reaction condition for the maleic acid-catalyzed hemicellulose hydrolysis: over 90% xylose yield could be achieved with a maleic acid concentration of 0.2 M for 12 min at 1708C (Lu and Mosier, 2007).…”

“…We previously reported a new catalytic route for corn stover hemicellulose hydrolysis which employs maleic acid as the catalyst, where the difference in xylose degradation kinetics made maleic acid a superior catalyst to sulfuric acid at high solid-loading reaction conditions (Lu and Mosier, 2007). The preliminary study experimentally identified an optimal reaction condition for the maleic acid-catalyzed hemicellulose hydrolysis: over 90% xylose yield could be achieved with a maleic acid concentration of 0.2 M for 12 min at 1708C (Lu and Mosier, 2007). However, the additive effects of catalyst concentration, reaction temperature and time on the kinetics of this process had not yet been studied systematically.…”

Preparation of Core-Shell Structure Magnetic Carbon-Based Solid Acid and its Catalytic Performance on Hemicellulose in Corncobs

“…Acid can corrode equipment and requires neutralization treatment after the reaction (Mosier et al 2004). As for the enzymes, their high price, low reaction efficiency, and difficulties with recovery restrict their large-scale use (Wood and McCrae 1986;Lu and Mosier 2007). A solid acid catalyst is prepared via the loading of acid groups onto an inert carrier, which has the advantages of avoidance of corrosion equipment.…”

Comparison of Dilute Organic and Sulfuric Acid Pretreatment for Enzymatic Hydrolysis of Bamboo

“…Organic acid pretreatment increase accessible surface area of substrates, solubilization of hemicelluloses and lignin, and alteration of lignin structure (Zhao et al 2009). Dicarboxylic organic acids such as oxalic acid can hydrolyze β-(1, 4)-bonds more selectively than sulfuric acid (Mosier et al 2002;Lu and Mosier 2007). In this study, we compared the effectiveness of formic acid, acetic acid, and oxalic acid to that of sulfuric acid in the pretreatment of bamboo.…”