A. Palermo et al., ELECTROCHEMICAL PROMOTION BY NA OF THE PLATINUM-CATALYZED REACTION BETWEEN CO AND NO, Journal of catalysis, 161(1), 1996, pp. 471-479
The Pt-catalyzed reduction of NO by CO exhibits strong electrochemical
promotion (EP) by backspillover Na supplied from beta '' alumina unde
r appropriate conditions of temperature, gas composition, and catalyst
potential, At high CO partial pressures (P-CO) the EP effect is atten
uated by CO island formation and limited availability of chemisorbed N
O. At low P-CO, the CO + O reaction is limited by the low coverage of
CO and the EP effect is again relatively small. In the intermediate P-
CO regime, Na pumping strongly accelerates the reaction: rate gains of
up to 1300% for N-2 production, relative to the unpromoted rate are o
bserved, This can be understood in terms of Na-induced dissociation of
chemisorbed molecular NO, which is thought to be the reaction initiat
ing step. The overall kinetic behavior and the dependence of N-2/N2O s
electivity on catalyst potential are in good accord with this hypothes
is. Thus the EP system also provides direct information about the natu
re of the reaction mechanism under conditions of elevated pressure. (C
) 1996 Academic Press, Inc.