Acidic cesium salts of 12-tungstophosphoric acid as catalysts for the dehydration of xylose into furfural

Abstract

Cesium salts of 12-tungstophosphoric acid, Cs x H 3− x PW 12O 40 (Cs x PW), in the bulk form or supported on medium-pore MCM-41 (3.7 nm) or large-pore (9.6 nm) micelle-templated silicas are active solid acid catalysts for the cyclodehydration of xylose into furfural, in a toluene/water solvent system (T/W) or in dimethyl sulfoxide (DMSO). The catalytic results are comparable to those obtained using sulfuric acid, under similar reaction conditions. The initial activities increase in the order H 3PW 12O 40 < Cs 2.0PW < Cs 2.5PW < silica-supported CsPW catalysts (15, 34 wt % PW). Higher HPA loadings, larger pore diameter of the parent silica support, and higher reaction temperatures lead to higher furfural yields. The stability and reusability of the MCM-41-supported CsPW is higher in DMSO than in T/W.