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 for assessing the plausibility of proposed catalytic reaction mechanisms. The present analysis of reaction pathways and energetics for key elementary steps in the catalytic decomposition of NO to N₂ + O₂ by Cu-exchanged zeolites yields novel insights into this widely studied reaction. We find evidence for a pathway involving two successive O-atom transfers to an isolated, zeolite-bound Cu⁺ center, initiated by formation of a short-lived and difficult to detect isonitrosyl intermediate, and yielding sequentially N₂O and Cu-bound O followed by N₂ and Cu-bound O₂. The calculations allow us to identify a complete catalytic cycle with reasonable energetics.