CO2 conversion by solar photothermo co-catalysis on montmorillonite-based catalysts

Nowadays thanks to the sustainable utilization of carbon dioxide, through its conversion into solar fuels, is possible to mitigate the impact of this greenhouse gas reducing at the same time the use of fossil fuels. In this work the conversion of the CO2 into CO and CH4 was investigated using a hybrid catalytic approach, the photothermo-catalysis, and non-critical catalysts, i.e., commercial montmorillonite (K30) modified with the intercalation of Ni and Ce and coated with Mn and Cu oxides. The best performance was obtained with the K30-Ni/Ce modified with both manganese and copper oxides that exhibited the 76.7% of CO2 conversion after 5 h of photothermo-catalytic test at 120 °C using a solar lamp, with the formation of 16.9 and 7.9 µmol/gcat h of CO and CH4 respectively. This catalyst showed also a good stability. The addition of Ni and Ce in the structure of the montmorillonite allowed to increase the CO2 adsorption and therefore to promote its activation, whereas the presence of the manganese and the copper oxides led to favour the harvesting of the solar light, enhancing the amount of oxygen vacancies, preferential sites on which the CO2 is adsorbed and activated. The synergisms exploited with this catalyst and the application of the photothermo-catalysis allowed to efficiently convert the CO2, paving the way to new solutions for the greenhouse gas mitigation with the contextual formation of solar fuels, thus promoting a sustainable circular carbon- based economy.