Comparative Study of the Electrochemical Promotion of CO₂ Hydrogenation over Ru‐Supported Catalysts using Electronegative and Electropositive Promoters

Abstract

Abstract The kinetics and the electrochemical promotion of the hydrogenation of CO 2 over Ru‐catalyst electrodes deposited on yttria‐stabilized zirconia (YSZ) and (Na + )‐β“‐Al 2 O 3 solid electrolytes are investigated at temperatures between 200 and 340 °C and pressures up to 5 bar. In the case of both the O 2− conductor (YSZ) and the Na + conductor (β”‐Al 2 O 3 ), the selectivity for CH 4 production is enhanced significantly when using a positive potential by supplying of O 2− to, or removal of Na + from, the catalyst surface. The opposite effect is observed when using a negative applied potential, which suppresses CH 4 formation and enhances the production of CO through the reverse water–gas shift reaction. However, at low Na coverage, and under reducing conditions, both methanation and H 2 production are promoted by the application of a negative potential. The observed electrochemical promotion behavior in conjunction with the reaction kinetics is consistent with the rules of electrochemical and chemical promotion.