Reaction kinetics and mechanism of selective NO reduction on a CoZSM-5 catalyst as studied by SSITKA

The dynamics of C-13 transfer from methane to carbon dioxide was studied under the steady-state reaction conditions of selective NO reduction with methane on a CoZSM-5 catalyst at various reactant (NO, CH4, and O-2) concentrations and temperatures. It was found that the reaction occurs by a two-pathway mechanism with the participation of Co2+ sites (or CoOx clusters) and paired Co2+-OH sites localized at the boundary between the clusters and the zeolite; in this case, the rate of the reaction at boundary sites was higher by more than one order of magnitude. Based on the numerical simulation of isotopic response curves, the concentrations of intermediate compounds and the rate constants of particular steps were evaluated; differences in the kinetics via the above reaction pathways were found and analyzed.