Selective Gas-Phase Hydrogenation of CO₂ to Methanol Catalysed by Metal-Organic Frameworks

Large scale production of green CH₃ OH obtained from CO₂ and green H₂ is a highly wanted process due to the role of CH₃ OH as H₂ /energy carrier and for producing chemicals. Starting with a short summary of the advantages of metal-organic frameworks (MOFs) as catalysts in liquid-phase reactions, the present article highlights the opportunities that MOFs may offer also for some gas-phase reactions, particularly for the selective CO₂ hydrogenation to CH₃ OH. It is commented that there is a temperature compatibility window that combines the thermal stability of some MOFs with the temperature required in the CO₂ hydrogenation to CH₃ OH that frequently ranges from 250 to 300 °C. The existing literature in this area is briefly organized according to the role of MOF as providing the active sites or as support of active metal nanoparticles (NPs). Emphasis is made to show how the flexibility in design and synthesis of MOFs can be used to enhance the catalytic activity by adjusting the composition of the nodes and the structure of the linkers. The influence of structural defects and material crystallinity, as well as the role that should play theoretical calculations in models have also been highlighted.