Status of Catalyst Development for CO2 Hydrogenation to Platform Chemicals CH3OH and CO

To ensure sustainable development in the chemical industry, new catalytic materials and large-scale processes are required for minimizing the carbon footprint. Many efforts have been made in the valorization of carbon dioxide (CO2), the primary greenhouse gas, through thermo-, electro-, and photocatalysis over the past decades. Within this concept, the direct hydrogenation of CO2 with hydrogen (H2) produced on a CO2-free basis has been attracting a special attention due to its high efficiency to close carbon cycles. Among various products formed through CO2 hydrogenation, methanol (CH3OH) and carbon monoxide (CO) stand out due to their multiple applications as platform chemicals. The former is also used as a fuel with high energy density. This contribution critically analyzes the up-to now developed catalysts for CO2 hydrogenation to methanol or CO via thermo catalytic processes, with a special focus being put on the discussion of active phases/sites and structure–activity relationships reported in previous studies. The suggested reaction mechanisms considering both selective and side reactions over different catalysts have also been briefly reviewed.