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

摘要

Cesium salts of 12-tungstophosphoric acid,Cs_xH_(3-x)PW_(12)O_(40) (Cs_xPW),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_(12)O_(40) < Cs_(2.0)PW < Cs_(2.5)PW < 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.