Finally, the fact that similar trends are observed also in the subsequent subsequences indicates that the adsorbed species on the surface can partly desorb in the absence of H2/CO2/Ar pulses, i.e., under present reaction conditions they are reversibly adsorbed on a time scale of 5 min. These rather fast changes could not be resolved during standard kinetic studies of CO2 hydrogenation on different supported Ru catalysts (e.g., Ru/Al2O3, Ru/TiO2, Ru/ZrO2 [9, 49-50].