Tuned selectivity and enhanced activity of CO2 methanation over Ru catalysts by modified metal-carbonate interfaces

Carbonate-modified metal-support interfaces allow Ru/MnCO 3 catalyst to exhibit over 99% selectivity, great specific activity and long-term anti-CO poisoning stability in atmospheric CO 2 methanation. As a contrast, Ru/MnO catalyst with metal-oxide interfaces prefers reverse water–gas shift rather than methanation route, along with a remarkably lower activity and a less than 15% CH 4 selectivity. The carbonate-modified interfaces are found to stabilize the Ru species and activate CO 2 and H 2 molecules. Ru-CO* species are identified as the reaction intermediates steadily formed from CO 2 dissociation, which show moderate adsorption strength and high reactivity in further hydrogenation to CH 4 . Furthermore, carbonates of Ru/MnCO 3 are found to be consumed by hydrogenation to form CH 4 and replenished by exchange with CO 2 , which are in a dynamic equilibrium during the reaction. Modification with surface carbonates is proved as an efficient strategy to endow metal-support interfaces of Ru-based catalysts with unique catalytic functions for selective CO 2 hydrogenation.