Oa. Marina et al., IN-SITU CONTROLLED PROMOTION OF CATALYST SURFACES VIA NEMCA - THE EFFECT OF NA ON THE PT-CATALYZED NO REDUCTION BY H-2, Journal of catalysis, 166(2), 1997, pp. 218-228
It was found that the catalytic activity and selectivity of Pt for NO
reduction by H-2 can be markedly and reversibly affected by depositing
polycrystalline Pt films on beta''-Al2O3, a Na+ conductor, and applyi
ng external currents or potentials to supply or remove Na to or from t
he Pt catalyst surface. The increase in the rate of NO reduction to N-
2 is typically 10(3)-10(5) times larger than the rate of supply of Na
and up to 30 times larger than the umpromoted rate. The use of the bet
a''-Al2O3 support permits precise in situ control of the Na coverage o
n 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 N-2
from 30 to 75%. The promotional effect of Na is due to enhanced NO che
misorption and dissociation on the Pt surface. (C) 1997 Academic Press
.