In SituControlled Promotion of Catalyst Surfaces via NEMCA: The Effect of Na on the Pt-Catalyzed NO Reduction by H₂

Author： Marina O.A. Yentekakis I.V. Vayenas C.G. Palermo A. Lambert R.M.

ISSN： 0021-9517

Source： Journal of Catalysis, Vol.166, Iss.2, 1997-03, pp. : 218-228

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Abstract

It was found that the catalytic activity and selectivity of Pt for NO reduction by H₂can be markedly and reversibly affected by depositing polycrystalline Pt films on β^′′-Al₂O₃, a Na⁺conductor, and applying external currents or potentials to supply or remove Na to or from the Pt catalyst surface. The increase in the rate of NO reduction to N₂is typically 10³–10⁵times larger than the rate of supply of Na and up to 30 times larger than the umpromoted rate. The use of the β^′′-Al₂O₃support permits precisein situcontrol of the Na coverage on the Pt surface. Sodium coverages of 0.06 cause up to 1450% increases in the total rate of NO reduction and enhance the selectivity to N₂from 30 to 75%. The promotional effect of Na is due to enhanced NO chemisorption and dissociation on the Pt surface.