Alcoholysis of Ball-Milled Corn Stover: The Enhanced Conversion of Carbohydrates into Biobased Chemicals over Combination Catalysts of [Bmim-SO3H][HSO4] and Al2(SO4)3

A mild and efficient alcoholysis process for the conversion of ball milled corn stover was developed using Bronsted (B) acidic ionic liquid [Bmim-SO3H][HSO4] (SO3H-IL) and Lewis (L) acidic Al-2(SO4)(3) as catalysts. The alcoholysis performance of ball-milled corn stover and the roles of catalysts on the product selectivity were first investigated, followed by a comprehensive elucidation of the roadmap for the alcoholysis of biomass carbohydrates. The results revealed that the selectivity of the alcoholysis product was highly sensitive to the molar ratio of the catalyst SO3H-IL to Al-2(SO4)(3). Two dominant products ethyl levulinate and furfural were achieved in maximum yields at the catalyst molar ratio of 1.6:0.4. Al-2(SO4)(3) alone afforded a high ethyl-D-glycopyranoside yield, while SO3H-IL with strong B acidity facilitated levoglucosenone production. The highest total carbohydrates conversion of 88.1 mol % was achieved for ball-milled corn stover, which demonstrates that mechanical ball milling is an effective pretreatment for the alcoholysis of biomass carbohydrates to high-value chemicals.YY