The direct hydrogenation of CO2 to methanol using hydrogen is regarded as a potential technology to reduce greenhouse gas emissions and the dependence on fossil fuels. For this technology to become feasible, highly selective and productive catalysts that can operate under a wide range of reaction conditions near thermodynamic conversion are required. Here we combine a CO-producing In oxide catalyst with a methane-producing Co catalyst to obtain In/Co catalyst for CO2 reduction to methanol. Density functional (DFT) simulations demonstrate that the charge transfer between Co support and In oxide film leads to enrichment of the surface of indium oxide with O vacancies, which serve as active sites for selective conversion of CO2 to methanol. Moreover, our simulations suggest that CO2 reduction on Co-supported In2O3-x films will 2 preferentially yield methanol, rather than CO and methane. As a result, the prepared In@Co catalysts produce methanol from CO2 with high selectivity (>80%) and productivity (0.86 gCH3OH.gcatalyst -1 .h -1 ) at conversion levels close to thermodynamic equilibrium, even at temperatures as high as 300 C and at moderate pressures (50 bar).

Highlights  Regardless preparation methods and Fe loading, Fe-Al2O3 catalysts showed the best CMD performance.  The selective formation of CNTs over Fe-Al2O3 catalysts is also speculated to be vital for their good CMD activity.  The graphite is proposed to be spurted out from an unstable over-stoichiometric iron carbide Fe3C1+x decomposition back to Fe3C and C.  At a low SV of 1.875 L/gcat•h, this catalyst showed a stable methane conversion of c.a. 70% for as long as 400 min.

The dynamic catalytic site on Mo/HZSM-5 for methane dehydroaromatization is formed during the initial phases of the reaction. Labelling experiments show that carbon from the carbidic active site is incorporated into the final products.