Facile preparation of SBA-15-supported niobic acid (Nb2O5•nH2O) catalyst and its catalytic activity

Hydrated niobium oxide (niobic acid) was effectively supported on mesoporous silica SBA-15 by HCl treatment of colloidal niobium oxide solution. The obtained Nb/SBA-15 exhibited high thermal stability, with no crystallization of niobium oxide. The number of generated Bronsted and Lewis acid sites increased with the Nb2O5 content. The catalytic activity of Nb/SBA-15 was evaluated to catalyze the hydrolysis of sucrose; Nb/SBA-15 exhibited higher sucrose conversion and TON than both bulk niobic acid and Nb/SBA-15-Oxa prepared according to a previously reported method. Moreover, we found that the choice of acid to be used in the preparation process influences catalytic activity. Nb/SBA-15 prepared by H3PO4 treatment yielded the highest sucrose conversion. (C) 2009 Elsevier B.V. All rights reserved.