Biorefinery of Corn Stover for Fuel Ethanol

Corn stover was pretreated by moderate acid and then washed by water.The solid residue after filtration was hydrolyzated to monosaccharide with cellulase for further fermentation to ethanol,while the liquid fraction after filtration was detoxified with trialkylamine extraction to ferment to ethanol.The material balance was carried out in the whole process.The results showed that the optimal pretreatment conditions were temperature 100 ℃,sulfuric acid mass fraction 3 % and time 12 h.After 24 h fermentation of the condensed enzymatic hydrolyzate containing 138.72 g/L of glucose,the sugar utilization rate was 99.02 % and the ethanol mass concentration reached its peak value of 62.98 g/L,which corresponded to 89.90 % of the theoretical value.Prehydrolyzate was detoxified by trialkylamine extraction,72.73 % of acetic acid,42.86 % of 5-hydroxymethylfurfural and 100 % furfural could be removed.The fermentability of the detoxified prehydrolyzate was significantly improved.After 48 h fermentation of the detoxificated prehydrolyzate containing 7.80 g/L of glucose and 52.80 g/L of xylose,the sugar utilization rate was 93.17 %,and the ethanol concentration reached its peak value of 21.76 g/L,which corresponded to 82.34 % of the theoretical value.After materials balance,it required 6.8 t absolutely dry corn stover to produce one ton ethanol.The process of this study provided the reference to realize the industrialization of hexose and pentose fermentation separately.