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

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.