Unravelling the Promotional Effect of La2 O3 in Pt/La-TiO2 Catalysts for CO2 Hydrogenation.

This work reports the preparation of a La2 O3 -modified Pt/TiO2 (Pt/La-TiO2 ) hybrid through an excess-solution impregnation method and its application for CO2 hydrogenation catalysis. The Pt/La-TiO2 catalyst is characterized by XRD, H2 temperature-programmed reduction (TPR), TEM, X-ray photoelectron spectroscopy (XPS), Raman, EPR, and N2 sorption measurements. The Pt/La-TiO2 composite starts to catalyze the CO2 conversion reaction at 220 °C, which is 30 °C lower than the Pt/TiO2 catalyst. The generation of CH4 and CO of Pt/La-TiO2 is 1.6 and 1.4 times greater than that of Pt/TiO2 . The CO2 temperature-programmed desorption (TPD) analysis confirms the strengthened CO2 adsorption on Pt/La-TiO2 . Moreover, the in situ FTIR experiments demonstrate that the enhanced CO2 adsorption of Pt/La-TiO2 facilitates the formation of the active Pt-CO intermediate and subsequently boosts the evolution of CH4 and CO. The cycling tests reveal that Pt/La-TiO2 shows reinforced stability for the CO2 hydrogenation reaction because the La species can prevent Pt nanoparticles (NPs) from sintering. This work may provide some guidance on the development new rare-metal-modified hybrid catalysts for CO2 fixation.