Catalysts containing silicon dioxide based on the support material for purifying exhaust gas from an internal combustion engine

Catalyst has a catalytically active coating on an inert honeycomb body made from a ceramic or metal. The coating contains platinum, palladium, rhodium or iridium on a finely divided oxidic support material based on silicon dioxide. The support material has low porosity and is composed of aggregates of spherical primary particles having an average diameter of 7-60 nm. An Independent claim is also included for a process for the production of the catalyst comprising coating a honeycomb body with a suspension containing a platinum group metal deposited on an oxidic support material, in which the support material is in a spray-dried form having a tamped density or more than 200 g/l. Preferred Features: The support material has an average particle diameter of 20-50 nm and a pore radius distribution of more than 20 nm. The support material is doped with 0.05-1 wt.% aluminum oxide. The coating additionally contains a dealuminized zeolite, beta-zeolite or a ZSM-5 zeolite.