Purification of effluent gases containing oxides of nitrogen as impurity

Abstract From the Canadian patent

The invention relates to the purification of gaseous effluents containing oxides of nitrogen by reduction of said oxides in the presence of a catalyst at raised temperatures. The catalysts used in this process contain iron as a major constituent, and may contain chromium or vanadium: these constitute 96 to 99.5% of the weight of the catalyst. Also present as promoters in, a total amount of 4.0 to 0.5% by weight of the catalyst are one or more rare earth metal oxides and a trace quantity of a platinum metal. The catalyst is prepared by a method which ensures a specific surface of 20-100 m2/g and pores having a maxim?? dimension between 100 and 5000 ?. Such a catalyst is particularly suitable …