Influence of Reduction Conditions on the Catalytic Activity of Ni2P/SiO2 for Gas-Phase Hydrodechlorination of Chlorobenzene

The silica-supported nickel phosphide, Ni2P/SiO2, was prepared by the temperature-programmed reduction method, and the influence of reduction conditions (H2 flow rate, reduction temperature, and time) on the textural properties of the catalyst was investigated. There was no remarkable difference in BET specific surface area, pore structure, and the Ni2P crystallites size for the catalysts prepared under different reduction conditions, whereas the P contents on the catalyst surface differed obviously. The catalysts showed an induction period for the hydrodechlorination, which might be due to the blocking of active sites by excess P. The induction period could be shortened by increasing the H2 flow rate, reduction temperature and reduction time during the catalysts preparation, indicating that reduction conditions influenced the surface properties of the catalysts. Ni2P/SiO2 showed excellent activity and stability for the hydrodechlorination of chlorobenzene. Under the conditions of 573 K, H2 flow rate of 75 ml/min, and chlorobenzene flow rate of 3 ml/h, the chlorobenzene conversion maintained above 99% during 130 h reaction over the Ni2P/SiO2 catalyst.