REACTIVE SITES ON MIXED-OXIDE SOLID ACID CATALYSTS - ISOMERIZATION OF1-BUTENE OVER ZIRCONIA-SILICA

The surface chemistry of zirconia-silica mixed oxides with varying com positions synthesized using the sol-gel method was examined using l-bu tene isomerization as a reactive probe. Their surfaces were also chara cterized using potentiometric titration. The catalytic activity was ob served to increase with zirconia content. The cis/trans ratio of the p roduct isomer was found to be near unity at all temperatures and catal yst compositions. Potentiometric titration of the mixed oxides generat ed pK spectra which were used to identify and characterize those speci fic surface Bites that catalyze the reaction. Only one specific site c ould be quantitatively related with the catalytic activity of the cata lysts. In all cases, a linear relationship was identified between the areal overall reaction rates and the population density of that partic ular site.