Acidity of tungstophosphoric acid-zirconia catalysts prepared by the sol-gel method

Zirconia was doped with tungstophosphoric acid (TPA) by co-geling the acid with zirconium n-butoxide. When samples were annealed at 400 degrees C, the ir specific BET areas were 164 and 74 m(2)/g for 15 and 25 wt % TPA, respec tively. From the X-ray diffraction analysis, nanocrystalline tetragonal zir conia and highly dispersed nanosized WO3 were identified. Pyridine adsorpti on was characterized by FTIR spectroscopy: bands at 1610 and 1442 cm(-1), w hich correspond to Lewis acidic sites, were observed. Pyridine desorption w as nat-complete at 400 degrees C, because the catalysts had strong Lewis ac id sites. The reaction for 2-propanol decomposition with the sample having 25 wt % TPA showed a large selectivity for isopropyl ether; when it was use d for chain isomerization of l-butene, isobutene and isobutane were importa nt products. ESR spectra had signals that corresponded to free electrons.