Catalyst for exhaust gas purification

A honeycomb catalyst 2 for exhaust gas purification comprising a honeycomb body, which has a fraction acting as a pollutant trap and/or a catalytically active fraction based on a catalytically active system comprising a base metal; and a catalytically inactive fraction. The catalytically inactive fraction is a thermally stable sulphate or sulphide component for reducing thermally induced shrinkage of the honeycomb body. The catalyst may be a vanadium oxide/metal oxide or a crystalline molecular sieve with a base metal promoter. The thermally stable component may be an alkali metal sulphate or sulphide, an alkaline earth metal sulphate or sulphide, or a transition metal sulphate or sulphide. Preferably the sulphate is lithium sulphate (LiSO4), calcium sulphate (CaSO4), barium sulphate (BaSO4) or titanium sulphate (TiO(SO4). The catalyst may also comprise a sheet silicate such as mica, where the ratio of mica to the thermally stable component is from 1:2 to 2:1. The thermally stable component is 2 to 10 wt% of the catalyst, and may be distributed homogeneously throughout the volume of the honeycomb body. The honeycomb catalyst may be extruded, and can be pressed within a housing 6 with the aid of an embedding mat 8.