Single-atom Pd dispersed on nanoscale anatase TiO2 for the selective hydrogenation of phenylacetylene

Abstract

Combining the advantages of both heterogeneous and homogeneous catalysts, single-atom catalysts (SACs) with unique electronic properties have shown excellent catalytic properties. Herein, we report single-atom Pd dispersed on na-noscale TiO2 prepared by self-assembly method as efficient and selective catalysts for the hydrogenation of phenylacetylene to styrene. The catalysts were characterized by N2 adsorption/desorption, X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and X-ray absorption spectroscopy (XAS). 0.2Pd-TiO2(150°C) possessing dominant single-atom Pd species, exhibited a turnover frequency (TOF) of over 8000 h-1 with 91% selectivity towards styrene at room temperature. Further increasing Pd loading from 0.2% to 0.5% and 1.5% resulted in the decrease of activity probably due to the formation of Pd nanoparticles. Besides, the 0.2Pd-TiO2 prepared by self-assembly strategy showed better catalytic performance than commercial 10%Pd/C and 0.2Pd-TiO2 synthesized by using impregnation method.