HETEROGENEOUS CATALYSTS

摘要

A silica-titania mixed oxide catalyst can be manufactured by producing a sol from optionally pre-hydrolyzed silicon alkoxide and from titanium alkoxide, the hydrolyzability of which is reduced by chelate formation, under acidic or basic hydrolysis conditions, gelling and ageing this sol, drying the thus-produced aged gel by extraction of the solvent used in the production of the sol and of the alcohol produced in the hydrolysis with super-critical carbon dioxide and, if desired, calcinating the aerogel resulting therefrom at temperatures up to 1000 DEG C in a gas stream containing oxygen. Such catalysts can be used especially to catalyse the epoxidation of olefinically unsaturated compounds with organic hydroperoxides.