First demonstration of in situ electrochemical control of a base metal catalyst: Spectroscopic and kinetic study of the CO plus NO reaction over Na-promoted Cu

WILLIAMS, F J; PALERMO, A; TIKHOV, M S; LAMBERT, R M

JOURNAL OF PHYSICAL CHEMISTRY B - (Print)

AMER CHEMICAL SOC

Año: 1999 vol. 103 p. 9960 - 9966

1520-6106

Controlled, reversible electrochemical promotion (EP) of a base metal catalyst has been demonstrated for the first time. Electropumping of Na from a 􏱆′′ alumina solid electrolyte to a Cu film catalyst results in large improvements in both activity and selectivity of the latter. In the catalytic reduction of NO by CO, the reactive behavior, surface composition, and response to EP are a strong function of the composition of the reactant gas. Electron spectroscopic data show that these effects are due to pumping of Na to the catalyst where, under reaction conditions, it is present as NaNO3 on an oxidized Cu surface. Taken together, the spectroscopic and reactor results show that Cu0 sites are not of significance and that the catalytically active surface is dominated by Cu+ and Cu2+ sites. They also suggest that Cu+ is of principal importance for the dissociative adsorption of NO and that EP is due to Na-induced enhancement of the adsorption and dissociation of NO at these sites.