Process for the removal from gases of nitrogen oxides NOx by selective catalytic reduction (SCR) using ammonia over zeolite catalysts not causing the formation of nitrogen protoxide
Résumé
Zeolites partially exchanged with copper, in particular faujasites, in which the copper does not largely occupy the small cages (for example the sodalite cages of the faujasites), are used as non-nitrogen-protoxide-generating SCR catalysts. Particular attention is drawn to certain mixed rare-earth/copper zeolites. The selectivity of the reduction of NOx to N2 is correlated with the TPR diagram of the catalysts.