Biomass pretreatment
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Is it feasible to first treat lignin with an alkali, and then treat cellulose and hemicellulose with an acid during the pretreatment of biomass for fuel ethanol production? What impact does it have on subsequent processes?
It is feasible, but the process is too complicated and the cost is too high. . After removing lignin, it can be directly saccharified, either by enzymatic methods or with acid catalysis.
The main methods for raw material pretreatment currently are chemical and enzymatic methods. The chemical method generally uses acid hydrolysis. The sugars and acids in the acid-hydrolyzed cellulose material were separated using an acid-resistant membrane (20% HCl, 60% H2SO4). On the one hand, sugars produced by cellulose degradation were obtained, and on the other hand, hydrochloric acid and sulfuric acid were recovered. Using this technology, the cost of producing glucose from the acid hydrolysis of wood is roughly the same as the cost of producing glucose from starch hydrolysis. The key to enzymatic hydrolysis is the cost of cellulase. In 2001, the American company IOGEN made a significant breakthrough in the development of cellulase, building the world’s largest cellulose processing facility. This facility is capable of processing 12,000 to 15,000 tons of cellulose per year, with an output of 2 million to 4 million liters of fuel ethanol per year.