Preparation of Cu-Al2O3-TiO2-Ti3C2/HZSM-5 Catalysts for Catalytic CO2 Hydrogenation to Dimethyl Ether

To develop efficient catalysts for CO2 hydrogenation to dimethyl ether, Cu-Al2O3-TiO2-Ti3C2/HZSM-5 bifunctional catalysts were prepared by the surfactant PVP-assisted coprecipitation. The influence of Ti3C2 on Cu-Al2O3-based catalysts was investigated. The characterization results revealed that slight oxidation of the Ti3C2 surface generated highly dispersed TiO2 nanoparticles that the doping of TiO2-Ti3C2 in the Cu-Al2O3 catalyst increased the specific surface area of the catalyst and promoted the formation and growth of Cu nanoparticles, and that strong interactions occurred between TiO2-Ti3C2 and the Cu components. The number of oxygen vacancies at the interface between TiO2-Ti3C2 and Cu increased by 17%, and the electronic kinetic energy of Cu-0 decreased by 0.1 eV, with the electron-rich oxygen vacancies transferring electrons to Cu2+ ions and maintaining more Cu species in lower oxidation states. Reactions were carried out at 260 degrees C and 3.0 MPa with a gaseous hourly space velocity (GHSV) of 1500 cm(3.)g(-1).h(-1) using Cu-Al2O3-TiO2-Ti3C2/HZSM-5 with 5.0 wt% Ti3C2 as the hydrogenation catalyst, which provided a CO2 conversion of 26.8% with 57.8% selectivity for DME.