In Figure we report as an example the simplified reaction network of CO 2 hydrogenation on Pd(111) neglecting the formation of methane, involving 21 elementary steps, 16 intermediates, and 5 gas-phase species (labelling at Table ). The network starts with the adsorption and dissociation of H 2 (i1) on the surface (i0). Then, CO 2 is adsorbed (i2), and the reaction evolves through the oxygen hydrogenation of CO 2 , resulting in COOH * (i3), leading to the dissociation of i3 into CO * and OH * fragments, and the posterior elimination of OH * via water formation and desorption (intermediates i5 and i6) . At this point, the reaction can evolve towards two different path-ways: CO * desorption (i6 to CO (g) and i0), culminating the RWGS reaction, or CO * sequential hydrogenation to generate methanol (from i7 to i8 or i13).