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Preparation of TiO2–ZrO2 mixed oxides with controlled acid–basic properties

2004; Elsevier BV; Volume: 220; Issue: 2 Linguagem: Inglês

10.1016/j.molcata.2004.06.003

1873-314X

M.E. Manríquez, T. López, R. Gómez, J. Navarrete,

Zeolite Catalysis and Synthesis

Titania–zirconia mixed oxides with various ZrO2 content in TiO2 (10, 50 and 90 wt.%) were prepared by the sol–gel method. High specific surface areas (77–244 m2/g) were obtained. Acidity determined by NH3-TPD and FTIR-pyridine adsorption showed that in mixed oxides the number of acid sites is dramatically increased; it varies from 173 μmol NH3/g for TiO2 to 1226–1456 μmol NH3/g for the mixed oxides. FTIR-pyridine adsorption showed the presence of Lewis sites in the catalysts. Basic sites were identified by FTIR-CO2 adsorption, suggesting the formation of mixed oxides with acid–basic properties. XRD spectra identified anatase in the TiO2 rich region, amorphous material in the mixed oxide 50–50 TiO2–ZrO2 and tetragonal and monoclinic crystalline phases in the ZrO2 rich region. Activity in the isopropanol decomposition showed a good correlation between the acid–basic properties and the selectivity to propene, acetone and isopropyl ether. The latter was found as a product which mainly depends of the acid sites density.