Methane synthesis from CO2 and H2O using a phosphate-based electrochemical cell at 210-270 °C with oxide-supported Ru catalysts

The conversion of electricity to chemical energy is a key technology for absorbing the fluctuations of electricity and utilizing solar and wind-powered electricities as chemical fuels. An electrochemical system equipped with a phosphate-based electrolyte has been reported as a promising method to efficiently obtain CH4 from CO2 and H2O in a single electrochemical cell. Electrochemical cells with 10 wt%-Ru/ZrO2, Ru/Al2O3, and Ru/TiO2 were examined for CH4 synthesis from CO2 and H2O at 210-270 degrees C and 10 mA cm(-2). Approximately 13 and 1 nmol s(-1) cm(-2) of CH4 and H-2, respectively, were formed using the Ru/ZrO2 cell at 270 degrees C, and the current efficiencies for CH4 and H-2 formation were 97 and 3%, respectively. The cells with Ru/Al2O3 and Ru/TiO2 produced lower CH4 yields. An H-permeable membrane (Pd-Ag) cathode cell, which was designed in a previous study, and a newly designed PTFE membrane filter cell was investigated with Ru/ZrO2. Both cells demonstrated similar formation rates and current efficiencies, which means that the Pd-Ag membrane is not essential for the synthesis of CH4 from CO2 and H2O. The catalysts were analyzed using transmission electron microscopy and temperature-programmed desorption of H-2.