Dissolution pretreatment of cellulose by using levulinic acid-based protic ionic liquids towards enhanced enzymatic hydrolysis. (1st October 2021) - He, Feng
Abstract: In this study, an economically competitive and sustainable levulinic acid-based protic ionic liquids were identified to be good solvents for the dissolution pretreatment of cellulose towards enhanced enzymatic hydrolysis. The influences of protic ionic liquids species, dissolution pretreatment time, and pretreatment temperature on the physico-chemical structures of cellulose were systematically investigated by various analytical techniques. The findings indicate that the pretreatment efficiency was correlated to the basicity of the organic bases, and the presence of ketone group in the levulinate anion with particular hydrogen bonding forming ability via keto–enol tautomerism. The DBN derived protic ionic liquids exhibited best performance at 100 °C in 1 h, as evidenced by a 94% glucose yield. This solvent system was also suitable for the dissolution pretreatment of corn stover-based lignocellulosic biomass for sugars production, although a higher temperature and longer pretreatment time was required. Furthermore, the solvent system could be recycled and reused. Graphical abstract: Levulinic acid, an inexpensive bio-based chemical derived from biomass, was used to prepare protic ionic liquids for the dissolution pretreatment of cellulose and lignocellulosic biomass towards enhanced enzymatic hydrolysis, and a 94% glucose yield from cellulose, 0.44 gg −1 glucose and 0.81 gg −1 of total reducing sugars yields from corn stover were obtained. Unlabelled Image Highlights: A sustainable levulinic acid-based protic ionic liquids was used for the dissolution pretreatment of cellulose. A 94% glucose yield was obtained when cellulose was pretreated for 1 h at 100 °C. The keto–enol tautomerism in the levulinate anion may contribute to the better performance. The [DBNH][Lev] protic ionic liquid solvents system can be recycled and reused.