COPPER-EXCHANGED MORDENITES AS ACTIVE CATALYSTS FOR NO SELECTIVE CATALYTIC REDUCTION BY PROPENE UNDER OXIDIZING CONDITIONS - EFFECT OF SI AL RATIO, COPPER CONTENT AND BRONSTED ACIDITY/

CuMOR catalysts with different Si/Al ratios and copper contents, prepa red from the acid and sodium forms, were studied in NO reduction with propene in the presence of excess oxygen. It was observed that the inf luence of zeolite Si/Al ratio on CuMOR catalytic activity for NO SCR b y propene depends on the catalyst copper content, the reverse being al so true. For mordenites prepared from the acid form, it was shown that the most active catalyst must have similar to 60% of copper exchange, whereas for those prepared from the sodium form, the maximum catalyti c activity is obtained for catalysts with 20% of copper exchange. More over, it was observed that at low copper-exchange levels, the catalyst prepared from the sodium form exhibits much higher activity than thos e prepared from the acid form. Although, when the copper-exchange leve l increases, the effect of zeolite form is less pronounced. Thus, it w as indicated that Bronsted acidity does not promote the NO selective r eduction by propene. (C) 1997 Elsevier Science B.V.