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

纳米氧化钛负载的单原子钯催化剂用于苯乙炔选择性加氢

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 nanoscale 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).0.2 Pd-TiO2(150℃)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 0.2 Pd-TiO2 prepared by self-assembly strategy showed better catalytic performance than commercial 10%Pd/C and0.2 Pd-TiO2 synthesized by using impregnation method.

单原子催化剂(SACs)兼具均相和非均相催化剂的优点,具有独特的电子结构,在某些反应中呈现出优异的催化性能.本文采用自组装方法将单原子Pd分散于纳米级的TiO2载体上,采用N2吸附/解吸、XRD、TEM、XPS、DRIFT和XAS对催化剂的结构进行了表征.在苯乙炔选择加氢制苯乙烯中,催化剂表现出优异的活性和选择性.在室温条件下,单原子催化剂0.2 wt%Pd-TiO2(150℃)的TOF达8000 h^-1以上,苯乙烯选择性维持在90%以上.当Pd负载量增加到0.5 wt%和1.5 wt%时,Pd物种聚集形成纳米颗粒,从而使活性下降.该方法制备的单原子0.2Pd-TiO2催化剂催化性能显著高于商品化10%P d/C以及浸渍法制备的0.2Pd/TiO2催化剂.