Superacid properties of alumina, silica-alumina and silica exposed to TiCl4
and HfCl4 vapour have been studied and compared with previously obtained r
esults for catalysts containing BF3, SbF5, AlCl3 and ZrCl4. It was found th
at the reaction of the vapour of metal halides of Lewis nature (MeXn) with
oxides like alumina, silica-aluminas and silica results in the formation of
the Bronsted superacid centres if acid strength of hypothetical acid MeXn.
XH is higher than that of sulphuric one. The Lewis superacid centres are f
ormed in the reaction of carrier containing alumina phase with metal halide
of strong electron acceptor ability.