FIRST-PRINCIPLES ANALYSIS OF ELEMENTARY STEPS IN THE CATALYTIC DECOMPOSITION OF NO BY CU-EXCHANGED ZEOLITES

First-principles quantum calculations are potentially of great value f or assessing the plausibility of proposed catalytic reaction mechanism s. The present analysis of reaction pathways and energetics for key el ementary steps in the catalytic decomposition of NO to N-2 + O-2 by Cu -exchanged zeolites yields novel insights into this widely studied rea ction. We find evidence for a pathway involving two successive O-atom transfers to an isolated, zeolite-bound Cu+ center, initiated by forma tion of a short-lived and difficult to detect isonitrosyl intermediate , and yielding sequentially N2O and Cu-bound O followed by N-2 and Cu- bound O-2. The calculations allow us to identify a complete catalytic cycle with reasonable energetics.