Silica supported superacid isomerization catalysts

The dispersion of tungsten-zirconia, tungsten-titania, boron-zirconia and boron-titania over silica was accomplished by sequentially impregnating Zr and Ti organic compounds and W and B inorganic salts. Supported ZrO2 displayed the highest sintering resistance, crystallizing at 700 °C, while supported TiO2 crystallized at a lower temperature, 550 °C. As a consequence, only supported zirconia could match the range of activation of WOx species (700-800 °C) and a bimodal pattern of activity was found, with maxima at 550 and 750 °C when the W-ZrO2/SiO2 catalyst was used in the isomerization of cis-butene. W-TiO2/SiO2 was fairly inactive.