Molecular design and experimental study of cellulose conversion to 5-hydroxymethylfurfural catalyzed by different ratios of Brønsted/Lewis acid ionic liquids

Abstract

Cellulose conversion into 5-hydroxymethylfurfural (5-HMF) is difficult because of the strong hydrogen bonding existed in cellulose chains. Brønsted/Lewis (B/L) biacidic functionalized ionic liquids (ILs) have great advantages in acid-catalyzed tandem reactions, but the catalytic effect of ILs differs considerably depending on B/L acid ratios. Therefore, this work designed a series of reactions with different proportions of biacidic ILs for the preparation of 5-HMF from cellulose. The tandem reaction is often performed in the presence of a solvent, and the activity of the catalyst is also affected by the solvent. Therefore, in this work, the solvation model density(SMD) model was introduced into the quantum chemical calculation method for molecular design to predict the catalytic effect and explore the catalytic mechanism. The calculation results and experiments jointly showed that [(HSO3-P)2im]Cl·ZnCl2 had the highest efficiency, with a 5-HMF yield of 65.66%. This study facilitates the directional optimization design of the catalyst.