The reduction of 15N14NO by CO and by H2 over Rh/SiO2: A test of a mechanistic proposal

A literature proposal that the reduction of nitrous oxide by carbon monoxide over rhodium catalysts proceeds by cleavage of the Nsingle bondN bond has been tested through the use of 15N14NO as the reactant. The results disprove the suggestion in that 14N15N is the dominant product at temperatures from 336 °C to 356 °C with nitrous oxide conversions from 26% to >99%. Little, if any, 14N2 and 15N2 is formed, in contrast with the 25% of each expected for the model. Results for the corresponding reaction of 15N14NO with H2 are even more clear-cut in demonstrating the absence of Nsingle bondN bond cleavage. The activity of the Rh/SiO2 used here for the N2O/CO system fell within the rather wide of values reported in the literature for other Rh catalysts. However, activity for the reduction of N2O by H2 was approximately five times higher than the only previous result in the literature, that for a Rh/Al2O3 catalyst.