Bioethanol lignocellulosic biomass pretreatment

Corn stover, a well-known example of lignocellulosic biomass, is a potential renewable feed for bioethanol production. Dilute sulfuric acid pretreatment removes hemicellulose and makes the cellulose more susceptible to bacterial digestion. The rheologic properties of corn stover pretreated in such a manner were studied. The Power Law parameters were sensitive to corn stover suspension concentration becoming more non-Newtonian with slope n, ranging from 0.92 to 0.05 between 5 and 30% solids. The Casson and the Power Law models described the experimental data with correlation coefficients ranging from 0.90 to 0.99 and 0.85 to 0.99, respectively. The yield stress predicted by direct data extrapolation and by the Herschel-Bulkley model was similar for each concentration of corn stover tested. 

US 0.29/L and US 0.53/L, respectively (Balat, 2011). In 2011, NREL (Colorado, USA) published the detailed report Process Design and Economics for Biochemical Conversion of Lignocellulosic Biomass to Ethanol (Humbird et al.. Mar. 2011). The NREL process design converts corn stover to ethanol by dilute-acid pretreatment, enzymatic saccharification, and co-fermentation, and with a minimum ethanol selling price (MESP) of US 2.15/gal (US 0.57/L calculated) by 2012 conversion targets (Table 7.3). In the report, the biomass amount processed is 2205 dry ton/day at 76% theoretical ethanol yield (79 gal/dry ton). It is expected that this MESP will become the standard for the cost of cellulosic bioethanol. 

Mood, H. S., Hossein Golfeshan, A., Tabatabaei, M., Salehi Jouzani, G.,Najafi, G. H., Ghol-ami, M., Ardjmand, M. Lignocellulosic biomass to bioethanol, a comprehensive review with a focus on pretreatment Renewable and Sustainable Energy Reviews 2013, 27, 77-93. 

The production of fuel ethanol from renewable lignocellulosic material ("bioethanol") has the potential to reduce world dependence on petroleum and to decrease net emissions of carbon dioxide. The lignin-hemicellulose network of biomass retards cellulose biodegradationby cellulolytic enzymes. To remove the protecting shield of lignin-hemicellulose and make the cellulose more readily available for enzymatic hydrolysis, biomass must be pretreated (1). 

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