Abstract: Hydrolysis is an important step for bioconversion of woody biomass to ethanol. Hydrolysis technology includes dilute acid hydrolysis, concentrated acid hydrolysis and enzymatic hydrolysis. Featured as selective attack, less degradation product, high recovery of glucose, low energy consumption, no demand on anti-corrosive reactor, enzymatic hydrolysis has been regarded as the potential breakthrough to lower the cost of ethanol production. Currently the cost of bioconversion of biomass to ethanol is higher than those of starch and sugar due to high cost of raw material pretreatment, expensive cellulase production, low cellulase activity, low efficiency of enzymatic hydrolysis, high cellulase loading and insufficient utilization of hemicellulose. Therefore, effective pretreatment technology should be developed to improve enzymatic digestibility of cellulose, selection of high-efficient cellulase and optimization of enzymatic hydrolysis should be conducted to raise the rate of enzymatic hydrolysis. Conversion of 5-carbon sugars into ethanol by means of genetically engineered microorganisms should be conducted to raise ethanol production.

Key words: ethanol, woody biomass, enzymatic hydrolysis, pretreatment