Cobalt Nanocomposites as Catalysts for Carbon Dioxide Conversion to Methanol †

Abstract

Carbon capture and utilisation (CCU), has arisen as an alternative to the reduction of CO2 concentration in the 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 compared to noble metals. Cobalt and its oxides exhibit interesting electronic and magnetic properties and are being used as catalysts in a wide range of reactions. In this work, we present a systematic comparison of 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. For this purpose, a fixed bed reactor operating with continuous flow is used, under mild temperature (160–260 °C) and pressure (10–15 bar) conditions. Several parameters are measured to evaluate the efficiency of the catalysis: CO2 conversion; space–time yield (STY), which indicates the methanol production yield per mass unit of catalyst and reaction time, and methanol selectivity, which evaluates the production of reaction side products such as carbon monoxide. How the adsorption capacity provided by the porous supports can enhance the catalytic capacity of cobalt and cobalt oxide is confirmed, as well as how porous supports such as zeolite and graphene clearly improve this capacity compared with a non-porous support such as silicon dioxide.