Electrochemical Promotion of Catalysis

Abstract

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.

Low-temperature propene combustion over Pt/K-βAl2O3 electrochemical catalyst: Characterization, catalytic activity measurements, and investigation of the NEMCA effect

“…Nevertheless, the measured value of Pt dispersion, after long term treatment at high temperature, is close to the one obtained in a typical monolithic reactor [19]. Therefore, one could envisage the use of the impregnation technique to deposit a Pt porous catalyst film onto tubes or channels, leading to a cell configuration easily adaptable to the existing catalytic devices in which EPOC could be applied, as already done with other metals [20,21]. The variation of the Pt catalyst chemisorption properties at varying catalyst potential (V WR ) was also characterized via the isothermal titration technique.…”

Electrochemical Promotion by Potassium of Rhodium-Catalyzed Fischer−Tropsch Synthesis: XP Spectroscopy and Reaction Studies

“…Electrochemical control of the sample was by means of a potentiostat-galvanostat (Ionic Systems, PG1). Ex-situ scanning electron microscopy (SEM) was performed with a JEOL 6340 FEG microscope operated at 20 kV; the surface area of the Rh film, estimated by CO methanation, 24,25 was 250 cm 2 .…”

“…Electrochemical promotion (EP) is a strongly nonfaradaic phenomenon that combines heterogeneous catalysis with solid-state electrochemistry. , It enables controlled and reversible alteration of the behavior of thin film metal catalysts in contact with ionic conductors which act as electro-active supports from which mobile promoter species may be pumped to or from the catalyst surface under reaction conditions. It is this in situ tuning of catalytic behavior that makes EP unique.…”

Electrochemical promotion of copper nanoparticles for the reverse water gas shift reaction

“…14 It is used to describe the phenomenon where a catalytic reaction rate alternation is observed upon an application of current or potential across the catalyst that is deposited on solid electrolyte support. 15–17 Depending on the catalyst used, the EPOC effect has been proved to work well for a wide variety of reactions, such as oxidation, reduction, hydrogenation, epoxidation, 18–20 etc. using a variety of ionic conductors (O 2− , H + , Na + , K + , OH − ).…”