Liquid-phase dehydration of D-xylose over silica-alumina catalysts with different alumina contents

The dehydration of d-xylose into furfural was examined using SiO2-Al2O3 catalysts with varying alumina contents to determine the effects of surface acidity on the catalytic performance. For comparison, SiO2 and Al2O3 catalysts were also examined. d-Xylose conversion increased with increasing alumina content in the SiO2-Al2O3 catalysts. Conversely, furfural selectivity at a similar d-xylose conversion decreased with increasing alumina content in the SiO2-Al2O3 catalyst. Lewis acid sites appeared to catalyze the isomerization of d-xylose into lyxose and xylulose, decomposition of d-xylose into C-1-C-3 products, and polymerization of d-xylose and furfural into humin.