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 o f 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 p erformance of Pt-film catalyst promoted electrochemically with Pt highly di spersed on large surface area carriers (e.g. gamma -Al2O3) promoted by conv entional means (impregnation). These similarities include (i) the overall k inetic behaviour acid (ii) the dependence of the activity and selectivity o n Na loading. Using both methods of Na-promotion, the catalytic reduction o f NO by propene over Pt exhibited rate enhancements as high as two orders o f magnitude accompanied by very pronounced increases of the system selectiv ity towards N-2. The results serve to validate further the interpretation o ffered for the EP (or NEMCA) phenomenon. More importantly, they demonstrate that the insight obtained from EP studies can be used to design convention al type effective catalyst formulations that were previously untried, thus opening up new areas for investigation in the frontiers between catalysis a nd electrochemistry. (C) 2000 Elsevier Science B.V. All rights reserved.