Promoting 5-hydroxymethylfurfural production from cellulose and wheat straw via sulfonic acid group-grafted SBA-15 mesoporous silica embedded with iron phosphate
Siyu Zhou, Wanni Liu, Dongqi Liu, Xian Shi, Kai Huang, Feng Jiang, Hui Gao, Haian Xia, Ying Guan, Siquan Xu
Abstract
Efficient catalytic conversion of cellulose into 5-hydroxymethylfurfural (HMF) remains challenging and arouses concern. In this study, iron phosphate (FePO 4 ) was embedded into the SBA-15 mesoporous silica matrix as an available active phase via ultrasound-assisted implantation, and then the abundant silanol nests were utilized to graft sulfonic acid groups to construct an innovative FeP@SBA-15-S catalyst. Through a systematic analysis of the characteristics of crystal, texture, element valence, acidity, hydrophilicity, etc., it was reflected that FeP@SBA-15-S catalyst gave the active FePO 4 component porosity and exhibited bifunctional acidity. Without pretreatment and other acid additives, FeP@SBA-15-S catalyzed cellulose under optimal conditions provided a desired HMF yield of 52 %. More meaningfully, the cellulose and hemicellulose components in native wheat straw could be catalyzed simultaneously by FeP@SBA-15-S catalyst, yielding 61 % HMF and 60 % furfural in one-pot. The cyclability evaluation showed that the FeP@SBA-15-S catalyst still had considerable activity after six continuous runs, with a slight loss in activity attributed to the leaching of active components and pore coverage. A clear catalytic pathway was summarized by GC-MS and 13 C NMR spectrum as cellulose undergoing glucose monomer ring opening, isomerization to fructose, fructose ring closure and final dehydration, and the by-products were also detected as mainly C 3 -C 23 fragments and oligomers.