Synergy of Photo- and Photothermal-catalytic Synthesis of Methyl Propionate from Ethylene and Carbon Dioxide over B–TiO₂/Ru

Using greenhouse gas CO2 as the carbonyl source, the preparation of methyl propionate (MP) via the synergistic effect of photo- and photothermal-catalysis instead of traditional thermal catalysis of ethylene hydroesterification was first proposed. Ru-loaded black TiO2 (B–TiO2/Ru) was selected as a photo- and photothermal-catalyst since Ru has been used as an excellent catalyst for hydroesterification, and black TiO2 with a high photothermal effect can reduce CO2 to more active CO in the hydroesterification reaction under light irradiation. The excellent photothermal effects from B–TiO2/Ru improve the yield of MP. A series of B–TiO2/Ru were successfully prepared and characterized by X-ray photoelectron spectroscopy, transmission electron microscopy, Fourier transform infrared, Raman spectroscopy, and X-ray diffraction. For the synergistic effect of photo- and photothermal-catalysis of ethylene carbonylation, higher oxygen vacancy density and photothermal effect of the B–TiO2/Ru catalyst lead to higher reaction efficiency. The ethylene hydroesterification reaction mechanism under full-spectrum Xe lamp illumination over the B–TiO2/Ru catalyst is discussed.