Catalytic role and location of Cs promoter in Cs–Au/TiO2 catalysts for propanol synthesis from CO2, C2H4 and H2

Abstract A series of Cs–Au/TiO 2 (anatase) catalysts with a Cs loading between 0 wt% and 13 wt% was synthesized by impregnation of Au/TiO 2 and tested for CO 2 conversion with C 2 H 4 into propanol in presence of H 2 . Cs loading was found to significantly influence the target selectivity, which passes over a maximum over the catalysts with 4 wt% and 7 wt% Cs. The results of catalysts characterization by various spectroscopic techniques (HAADF‑STEM, XPS, and UV–vis) revealed that Cs species are located on both the support and the Au NP and favor stabilization of Au δ + species. The presence of Cs was also established to increase the rate of CO insertion into C 2 H 4 ; thus, improving the selectivity to propanol. The positive effect disappears for the catalysts with Cs loading above 7 wt%, which possess larger Au NP (around 17 nm) than the selective catalysts (1–7 wt% Cs) with Au NP between 4.5 nm and 7 nm.