Hydrodenitrogenation and hydrodesulfurization of coal tar on Ni-W catalysts with different metal loadings

The γ-Al₂O₃ supported Ni-W catalysts with different metal contents for the hydroprocessing of low and middle-temperature coal tar were prepared and characterized by the X-ray diffractogram (XRD), X-ray photoelectron spectroscopy (XPS), temperature programmed desorption of NH₃ (NH₃-TPD), N₂ adsorption and high resolution transmission electron microscopy (HRTEM). The hydrodenitrogenation (HDN) and hydrodesulfurization (HDS) performances of the catalysts were evaluated by using low and middle temperature coal tar. The results show that the sulfidation degree of the catalysts increases with increasing metal content within a certain range, while the amount of total acid that mainly consists of intermediate acid decreases. The HDN activity of the catalysts with Ni/W atomic ratio of 0.786 increases initially and reaches an optimum value at 24% WO₃, and then decreases, while the HDS activity increases gradually.