Suppression of radical-cationic benzene oligomerization on sulfated zirconia

The effect of catalyst activation conditions on transformations of benzene cation radicals on sulfated zirconia has been studied by in situ ESR spectroscopy. After the catalyst activation at 300°C there was no oligomerization of the cation radicals to biphenyl and heavier products, which is observed after catalyst calcination at 500°C. It has been suggested that the oligomerization is suppressed by the presence of strong Br?nsted sites on the surface.