High Concentration Bioethanol Production from Corn Stalk Via Enhanced Pretreatment with Ionic Liquids

•The [BHEM]mesy- glycol system had high pretreatment efficiency with 93% lignin removal rate.•The pretreated corn stalk was easy to enzymolysis with 91% cellulose and lower crystallinity.•The viscosity of enzymolysis materials was the key factors limiting the efficiency of enzymolysis by rheometer.•By feed-batch method, the glucose concentration reached 250 g/L with the yield of 100 %. The ethanol concentration is 93 g/L with the yield of 70 %.