Composition of the Surface Intermediate Species in Selective Catalytic Reduction of NO(subscript x) with Ethylene over Co-ZSM-5

A pretreatment-transient reaction product analysis method was applied to study the surface intermediate species in the selective catalytic reduction of NO(subscript x) with C2H4 over the Co-ZSM-5 catalyst. The reactions of the surface species NC(subscript a)O(subscript b)H(subscript c), formed by the pretreatment of Co-ZSM-5 in a NO/C2H4/O2 gas mixture at 275℃, with a NO/O2 flow produce much more N2 than that with a single NO or O2 flow. Apart from the oxygen content that cannot be determined under the experimental conditions, the average atomic ratio of N:C:H in the surface species was measured to he about 1.0:1.8:5.0 based on the product analysis by mass spectrometry, infrared absorption spectroscopy, and gas chromatography-mass spectrometry.