Effectively catalytic hydrolysis of cellulose to glucose in the presence of pyrrolidonium-based acidic ionic liquids

A series of acidic ionic liquids (methylimidazolium-based acidic ionic liquids and pyrrolidonium-based acidic ionic liquids) were synthesized and characterized. The cellulose hydrolysis into glucose, in which ionic liquid 1-butyl-3-methylimidazolium ([Bmim]Cl) was used as the solvent, in the presence of the synthesized acidic ionic liquids was studied systematically. The influences of water content, procedure of adding water, kinds of catalyst, catalyst dosage, reaction temperature and reaction time on the conversion of cellulose and yield of glucode were investigated. It was shown that pyrrolidonium-based acidic ionic liquids were better in catalyzing the hydrolysis of cellulose into glucose than methylimidazolium-based acidic ionic liquids. Under the optimized reaction conditions, which were the reaction temperature of 110°C, n(Catalyst):n(Glucose unit in cellulose):n(H ₂O)=1:3:210, [Hnmp]CH ₃SO ₃ as catalyst, with the water addition of once per 10 min in 40 min, and the reaction time of 2 h, the glucose yield of cellulose hydrolysis was 68%.