Effect of NO on the catalytic removal of N2O over FeZSM-5. Friend or foe

Selective catalytic reduction (SCR) of N2O with C3H8 over FeZSM-5 under excess oxygen is strongly inhibited by NO. The assistance of the hydrocarbon in N2O reduction vanishes at high partial NO pressures, approaching the activity of the N2O + NO system at molar NO/N2O ratios of 1.5–2, with N2O/C3H8=1. This effect differs from the NO promotion in direct N2O decomposition over Fe-zeolite catalysts. The negative effect of NO on the N2O reduction has a significant impact in the design and operation of catalytic reactors in tail-gases of nitric acid plants and other sources where NO comes along with N2O. [Copyright &y& Elsevier]