Preparation of $$\hbox {TiO}_{2}$$ TiO 2 supported Au–Pd and Cu–Pd by the combined strong electrostatic adsorption and electroless deposition for selective hydrogenation of acetylene

Abstract

$$\hbox {TiO}_{2}$$ supported Au–Pd and Cu–Pd catalysts were prepared by strong electrostatic adsorption (SEA) of Pd followed by electroless deposition (ED) of a second metal with incremental surface coverages of Au or Cu. High dispersion of small Pd particles on the $$\hbox {Pd/TiO}_{2}$$ prepared by SEA led to the high amount of second metal deposition on Pd surface. The Cu addition by ED increased the relative ratio of linear CO adsorption mode indicating the presence of higher amount of isolated Pd atoms. The ensemble effect of the Cu–Pd/TiO $$_{2}$$ catalysts resulted in the improved catalytic performances in the selective hydrogenation of acetylene to ethylene. However, as revealed by the blue shift of CO-IR and XPS results, Au addition by ED rather exhibited the electronic modification. The highest catalytic activity was obtained on the 1.10% Au–Pd/TiO $$_{2}$$ catalyst; however, the Cu addition (0.12% Cu–Pd/TiO $$_{2}, \uptheta _{\mathrm{Cu}} = 0.37$$ ) showed interesting results as only a small amount of Cu was used to improve the catalyst performances. The bimetallic catalysts were also prepared by conventional impregnation for comparison purposes. These catalysts exhibited several drawbacks such as low Pd dispersion, formation of second metal aggregates, and blockage of isolated Pd atoms. Synopsis $$\hbox {TiO}_{2}$$ supported Au-Pd and Cu-Pd catalysts were prepared by using the combination of strong electrostatic adsorption for Pd and electroless deposition for second metal addition. The catalytic performances for selective hydrogenation of acetylene were improved due to the ensemble and electronic modifications of the Cu–Pd/TiO $$_{2}$$ and Au–Pd/TiO $$_{2}$$ , respectively.