Currently, owing to the valorization of carbon dioxide through CCU (carbon capture and utilization) processes, it is possible to mitigate the impact of greenhouse gases and decrease the use of fossil fuels by reducing the amount of CO2 through the use of solar fuels . In this work, the valorisation of CO2 into CO and CH4 was investigated using a hybrid catalytic approach as the photothermocatalysis and unconventional photocatalysts, i.e., modified commercial phyllosilicates, which was achieved using the montmorillonite K30. The modification of K30 with Ni and Ce was carried out using the hydrothermal method. The coatings with Mn and Cu oxides were created by means of the precipitation method. The catalytic tests were conducted in a cylindrical batch reactor at 120°C using a solar lamp for 5h of irradiation. The analysis of the reaction products was performed with GC-TCD/FID, and the samples were characterized by means of SEM, FT-IR, UV-DRS, Raman, CO2-TPD, and N2- physisorption. The best performance was obtained by K30-Ni/Ce@MnCuOx, with 76.7% of the CO2 being converted and 13.9 and 4.9 mmol/gcat•h CO and CH4, respectively. With this latter sample, we also conducted stability tests using a treatment in a H2 flow for the reactivation of the sample. The coating using noncritical mixed metal oxides improved the performance of the bare K30 and K30 that was modified with Ni and Ce. The photothermocatalysis also represents a greener strategy for mitigating the impact of CO2. The performance of this catalyst was also compared to “artificial clays”, such as MXenes. These compounds were modified with the addition of CeO2, TiO2, and SiO2 to further improve their photothermocatalytic activity due to their photothermal properties.
Acknowledgements: SAMOTHRACE CUP-E63C22000900006. R.F. thanks the CO2@photothermocat project PRIN 2022 PNRR CUP E53D23015700001
