CATALYTIC REDUCTION OF NITROGEN MONOXIDE BY PROPENE IN THE PRESENCE OF OXYGEN OVER CERIUM ION-EXCHANGED ZEOLITES .1. GENERAL-CHARACTERISTICS OF THE REACTION AND EFFECTS OF ALKALINE-EARTH METAL ADDITION

Catalytic reduction of dilute nitrogen monoxide by propene in the presence of excess oxygen was studied over various metal ion-exchanged zeolites. The presence of propene and oxygen was essential for the reaction. Ce-zeolites, particularly Ce-ZMS-5, showed a very high catalytic activity for the reduction of nitrogen monoxide. The high activity of Ce-ZSM-5 was attributed to its high selectivity (high efficiency of the use of propene for the reduction). The addition of alkaline ear-th metals to Ce-ZSM-5 enhanced the activity considerably and the Ce-ZSM-5 containing alkaline earth metals showed good performance even at a very high space velocity (CHSV=10(5) h-1).