Catalysts selective for the reduction of nitrogen oxides to nitrogen in an oxidizing medium, a process for their preparation and their use

摘要

A catalyst which is active and selective for the reduction of nitrogen oxides to molecular nitrogen by reducing agents in a medium which is superstoichiometric in oxidizing agents such as carbon monoxide, hydrogen, hydrocarbons, alcohols and other oxygen-containing organic compounds. The active phase of this catalyst is as follows: at least one inorganic refractory oxide; at least one rare earth element (A); at least one alkaline-earth element (B); at least one platinum group metal (C); and at least one silver or gold metal (D). Impregnation of (C) is advantageously followed by heat treatment in a reducing atmosphere.