Ceria-supported Cobalt Catalyst for LowTemperature Methanation at Low Partial Pressures of CO2.

The direct catalytic conversion of atmospheric CO2 to valuable chemicals is a promising solution to avert negative consequences of a rising CO2 concentration. However, heterogeneous catalysts efficient at low partial pressures of CO2 still need to be developed. Here, we explore Co/CeO2 as a catalyst for methanation of diluted CO2 streams. This material displays an excellent performance at reaction temperatures as low as 175 °C and CO2 partial pressures as low as 0.4 mbar (the atmospheric CO2 concentration). To gain mechanistic understanding of this unusual activity, we employed in situ X-ray photoelectron spectroscopy and operando infrared spectroscopy. The higher surface concentration and reactivity of formates and carbonyls - key reaction intermediates - explain the superior activity of Co/CeO2 compared to a conventional Co/SiO2 catalyst. This work emphasizes the catalytic role of the cobalt-ceria interface and will aid in developing more efficient CO2 hydrogenation catalysts.