EFFECT OF OXYGEN ON SELECTIVE CATALYTIC REDUCTION OF NO BY NH3 OVER COPPER-ION EXCHANGED MORDENITE-TYPE ZEOLITE CATALYST

The effect of oxygen on the selective catalytic reduction of NO by NH3 was examined over a copper exchanged mordenite type zeolite catalyst. The catalytic activity for NO reduction by NH3 in the presence of oxy gen was at least one order of magnitude higher than that in the absenc e of oxygen and it was fully reversible with respect to the presence o f oxygen in the feed gas stream. Based upon ESR, TPD, TPO and TPSR stu dies, the redox behavior of copper ions was closely related to the enh ancement of NO removal activity by the introduction of oxygen to the f eed gases.