Bulk and surface characterization and isomerization activity of Pt/WO 4 2− /ZrO 2 catalysts of different preparations

The texture, phase and surface composition and acidity of impregnated and precipitated Pt/WO 4 2− /ZrO 2 catalysts have been investigated with XRD, XPS, FTIR spectroscopy, and BET measurements. It has been shown that increasing the tungstate ion concentration in hydrated zirconium oxide results in an increase in the t -ZrO 2 fraction in the catalysts following high temperature activation. While a fraction of W 6+ and W 5+ cations forms a solid solution with zirconia, the remaining W ions are stabilized on the catalysts surface as (–WO x –) n clusters. The catalytic activity in n -heptane isomerization seems to correlate with catalyst surface acidity to reach the greatest value at the WO 4 2− concentration in the range of 12.9–17.6 mol %.