Effect of H2S pre-treatment on structure and activity of Ni2P/SiO2 catalyst for hydrodechlorination of chlorobenzene

The effect of 10% H2S/H-2 treatment on the structure of Ni2P/SiO2 and its activity for the hydrodechlorination of chlorobenzene was investigated using X-ray diffraction, inductively coupled plasma atomic emission spectroscopy, X-ray photoelectron spectroscopy, CO chemisorption, H-2 temperature-programmed desorption, NH3 temperature-programmed desorption, and activity tests. The H2S/H-2 treatment did not change the Ni2P phase or crystallite size even at temperatures as high as 873 K. However, S species were incorporated in the surface of the Ni2P crystallites to form surface phosphosulfide (NiPxSy) species, which blocked the Ni sites and induced their further electron-deficiency. H2S/H-2 treatment also led to an increase of spilt-over hydrogen species. The treated Ni2P/SiO2 catalyst had higher turnover frequencies in the hydrodechlorination of chlorobenzene than the untreated catalyst. This was ascribed to the increased electron-deficiency of Ni site and a greater amount of spilt-over hydrogen species. (c) 2013, Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.