Successful application of electrochemical promotion to the design of effective conventional catalyst formulations

Electrochemical promotion (EP), discovered and developed by Vayenas and co-workers provides a novel in situ reversible and highly controllable means of catalyst promotion. We found that Pt-group metal catalysts exhibit strong EP by sodium during reactions related to emission control catalysis, such as NO reduction by hydrocarbons. Close similarities are found between the performance of Pt-film catalyst promoted electrochemically with Pt highly dispersed on large surface area carriers (e.g. gamma -Al2O3) promoted by conventional means (impregnation). These similarities include (i) the overall kinetic behaviour acid (ii) the dependence of the activity and selectivity on Na loading. Using both methods of Na-promotion, the catalytic reduction of NO by propene over Pt exhibited rate enhancements as high as two orders of magnitude accompanied by very pronounced increases of the system selectivity towards N-2. The results serve to validate further the interpretation offered for the EP (or NEMCA) phenomenon. More importantly, they demonstrate that the insight obtained from EP studies can be used to design conventional type effective catalyst formulations that were previously untried, thus opening up new areas for investigation in the frontiers between catalysis and electrochemistry. (C) 2000 Elsevier Science B.V. All rights reserved.