The CO2 methanation (that is, Sabatier reaction), has been considered as a promising way to recycle and utilize CO2. However, the industrial Sabatier process is energy intensive and traditionally powered by fossil fuels. Harvesting solar energy for the conversion of CO2 into solar fuels offers a sustainable and green solution to alleviating energy and environmental issues. In this work, solar-driven CO2 methanation over nickel-based catalysts was investigated under concentrated solar irradiation. A CO2 conversion rate of approximately 87%, with 100% selectivity towards CH4 and a reaction rate of 380 mmol/gNi/h were achieved under concentrated UV-visible-IR irradiation at 350 °C on 15 wt% Ni/Al2O3. The temperature required to achieve maximum CO2 conversion for the nickel-based catalysts were 25 °C lower in the solar-driven process compared to conventional thermocatalytic process. Meanwhile, the apparent activation energy of the solar-driven reaction is 25% lower than that of the thermocatalytic reaction. Moreover, in-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) experiments were performed to gain an in-depth insight into the enhancement mechanisms of light in the solar-driven process. This study emphasizes the merits of utilizing concentrated solar energy for driving chemical reactions, revealing the promotion of the reaction by light and offering new insights into the reaction mechanism of solar-driven CO2 methanation over Ni-based catalysts.
Keywords solar fuel, CO2 methanation, concentrated solar, mechanism