Catalyst for reducing of nitrogen oxide in smoke and process for its preparation

The catalytic activity of a conventional DeNOx catalyst which is used to decrease the nitrogen oxides in flue gas sharply decreases with falling operating temperature, so that at operating temperatures below 250@C, a relatively large catalyst volume is required to achieve a predetermined degree of reduction of NOx. To increase the catalytic activity of a DeNOx catalyst in the low temperature range, according to the invention it is provided that on the catalyst (8) surface facing the flue gas, a layer (52) of particularly high adsorption capacity for ammonia and nitrogen oxides is provided. As a result, the diffusion of the ammonia and the nitrogen oxides from the gas phase to the surface and into the pores of the DeNOx catalyst is improved, which leads to an increased catalytic conversion of ammonia and nitrogen oxides on the catalytically active centres of the DeNOx catalyst. The DeNOx catalyst according to the invention can be used in principle in any plant for decreasing the nitrogen oxides in flue gas, in particular in the low temperature range.