Electrochemical Promotion of CO₂ Hydrogenation Using Rh Catalysts Supported on O²⁻ Conducting Solid Electrolyte

Abstract

Electrochemical promotion was used to modify the activity and selectivity of a Rh catalyst electrode in the CO2 hydrogenation reaction. The experiments were carried out in a temperature range of 350–430 °C at ambient pressure and at different CO2 to H2 gas feeding ratios (1:2 to 4:1). The only reaction products observed were CO and CH4, both under open- and closed-circuit conditions. The CH4 formation rate was found to increase with both positive and negative potential or current application. The CO formation rate followed the opposite trend. The selectivity to CH4 increased under high values of hydrogen partial pressure and decreased at high pressures of CO2. The results demonstrate how electrochemical promotion can be used to finely tune activity and selectivity for a reaction of high technical and environmental importance.

Keywords

• electrochemical promotion of catalysis (EPOC)
• non-faradaic electrochemical modification of catalytic activity (NEMCA)
• CO₂ hydrogenation
• rhodium (Rh)
• YSZ
• XPS