Cobalt nanocomposites as catalysts for carbon dioxide conversion to methanol

Carbon capture and utilisation (CCU), has arised as one of the alternatives for the reduction of CO₂ concentration in atmosphere by converting it into value added products. CO₂ conversion to methanol presents certain drawbacks such as high pressure and temperature conditions, and to solve these issues new materials are being investigated. Among them, cobalt stands out due to its abundance and low price when compared to noble metals. Cobalt and its oxides exhibit interesting electronic and magnetic properties and are used as catalysts in a wide range of reactions. In this work we present a systematic comparison among different cobalt and cobalt oxide nanocomposites in terms of their efficiency as catalysts for CO₂ hydrogenation to methanol, and how porous and non porous supports can enhance their catalytic capacity. With this purpose a fixed bed reactor operating with continuous flow is used, under mild conditions of temperature (160-260 ºC) and pressure (10-15 bar). Several parameters are measured in order to evaluate the efficiency of the catalysis: CO₂ conversion; space time yield (STY), which indicates the metanol production yield per mass unit of catalyst and time of reaction, and methanol selectivity, which evaluates the production of side products of the reaction such as carbon monoxide. It is confirmed how the adsorption capacity provided by the porous supports can enhance the catalytic capacity of cobalt and cobalt oxide, and how porous supports such as zeolite and graphene clearly improve this capacity if compared with a non porous support such as silicon dioxide.