Abstract: Corn stalk was pretreated by four kinds of pretreatment methods, namely, dilute acid, dilute acid refining, neutral steam explosion and dilute acid steam explosion. The effects of pretreatment on enzymatic hydrolysis and yield of fermentable su-gars were investigated. The components of pretreated corn stalk, sugars in pre-hydrolyzate, carbohydrate and lignin degradation products in pre-hydrolyate were also analyzed. After 100 g corn stalk was pretreated by dilute acid, dilute acid refining, neutral steam explosion and dilute acid steam explosion followed by washing, the cellulose content -dropped from 37.17g to 33.96, 33.54, 32.63 and 32.88 g, respectively; the xylan content declined from 22.84 g to 2.77, 2.47, 3.56 and 2.05 g respectively and lignin content reduced to 17.63, 17.42, 16.90 and 17.25 g from 18.76 g, respectively. When dilute acid steam explosion pretreated corn stalk was treated by 20 FPIU/g cellulose cellulase and 3 IU/g cellulose β-glucosidase for 48 h as the substrate concentration was 100g/L, the hydrolysis yield of cellulose was 75.91 % (based on corn stover). The yield of fermentable sugars was 44.93 % (based on corn stover) as the corn stover was pretreated by dilute acid steam explosion and enzymatic hydrolysis.

Key words: lignocellulose, pretreatment, steam explosion, bioethanol