Electrochemical promotion of catalysis

Recent progress made in our laboratory in the field of electrochemical promotion of heterogeneous catalytic gas reactions is presented. The phenomenon consists of non-Faradaic modification of the catalytic reaction rate as the result of electrochemical polarization of the interface between the catalyst and the solid electrolyte support. Two main aspects are addressed, the description of the phenomenon and the development of bipolar cell configurations suitable for practical applications. It is shown that the necessary condition to achieve electrochemical promotion is the formation of a double layer at the catalyst/gas interface by mechanism of ion backspillover from the solid electrolyte support. Electrochemical promotion is only feasible in an adequate temperature range, limited by the mobility and the lifetime of the promoting ion, and it is favored by high porosity and low film thickness of the catalyst. On the application side, two new cell designs have been developed, a ring-shaped and a multiple-channel configuration, both operated in bipolar polarization mode. The ring-shaped cell is shown to be almost free of current bypass. Feasibility of electrochemical promotion is successfully demonstrated with both configurations. Realization of efficient bipolar cell configurations for electrochemical promotion is very promising in view of future applications in dispersed catalytic systems.