Preparation of supported nickel phosphide catalyst by solvothermal method and its hydrodesulfurization performance

The supported Ni₂P/MCM-41 catalyst was prepared by a solvothermal method using triphenylphosphine (TPP) as a cheap phosphorus material and tri-n-octylamine (TOA) as the coordinating liquid reaction system. The catalysts were characterized by X-ray diffraction (XRD), N₂-adsorption, CO uptake, X-ray photoelectronspectroscopy (XPS) and transmission electron microscopy (TEM). The solvothermal synthesis was performed at atmospheric pressure and 330 ℃, at least 300 ℃ lower than the temperature for preparing the corresponding catalysts by temperature-programmed reduction (H₂-TPR) method. The structure and hydrodesulfurization (HDS) performance of the as-prepared Ni₂P/MCM-41 catalyst are compared with those prepared by H₂-TPR, with dibenzothiophene (DBT) as a model compound. The results showed that the solvothermal method can decrease the aggregation of P species on the catalyst surface so as to achieve a Ni₂P catalyst with high surface area (690 m²/g) and then promote the formation of small and highly dispersed Ni₂P active phase. The catalyst from solvothermal synthesis exhibits distinctly a superior HDS performance to that prepared by H₂-TPR method. Under the conditions of 340 ℃, 3.0 MPa, a H₂/oil volume ratio of 500(volume ratio), and a weight hourly space velocity (WHSV) of 2.0 h^-1, the conversion of DBT reaches 96.8% over the catalyst from solvothermal synthesis, which is 10.6% higher than that over the catalyst prepared via H₂-TPR.