Quantitative evaluation of ball-milling effects on the hydrolysis of cellulose catalysed by activated carbon

Abstract

The synthesis of glucose from cellulose is a critical roadblock for establishing a new sustainable cycle of biorefinery to produce bio-based and environmentally-benign chemicals. We have previously demonstrated that the pre-treatment ball-milling of solid cellulose and a solid catalyst (mix-milling) drastically improves the yield of glucose and oligosaccharides; however, the effect of this type of ball-milling has not been quantitatively evaluated. In this study, we performed several model reactions and found that the mix-milling method drastically enhanced the solid–solid reactions, such as the hydrolysis of insoluble cellulose to soluble oligomers on the solid catalyst, but not liquid–solid reactions. The kinetic study indicated that the rate constant of hydrolysis of cellulose to oligomers using mix-milling was 13-fold higher than that using individual milling. Owing to the fast depolymerisation of cellulose, we achieved a 72% yield of glucose with 97% conversion of cellulose and 74% selectivity at 418 K.