Y zeolite-supported niobium pentoxide catalysts for the glycerol acetalization reaction

Faujasite zeolite-supported niobium-based catalysts (with Nb2O5 amounts of 5 and 15 wt%) were prepared by impregnation of NaY, HY, and HUSY zeolites using a niobum(V) ammonium oxalate complex. These obtained Nb-containing catalysts were calcined and thoroughly characterized by different physico-chemical techniques. The characterization results revealed that niobium oxide was successfully loaded on the surface of the zeolite supports without any significant modification of the faujasite structure. Surface area and pore volume were found to decrease with the increase in the Nb content for all the prepared catalysts. The presence of Nb was proved to increase the hydrophobicity of the zeolites and to affect surface acidity. The catalytic activity of the Nb-containing samples was evaluated in the glycerol acetalization reaction, and the Nb-HUSY catalysts were found to show the best catalytic performance.