Effect of phosphorus modification on the coal tar hydrogenation activity of the Ni–Mo/γ-Al2O3 catalyst

In this study, a Ni–Mo/γ-Al2O3 catalyst was prepared by the saturated impregnation method, and the catalyst was modified by phosphorus. Through the model compound, hydrogenation experiments and the coal tar hydrogenation experiments, five kinds of Ni–Mo/γ-Al2O3 catalyst with different phosphorus addition were evaluated. The hydrogenation experiments were carried out for three compounds, quinoline, dibenzothiophene and phenol, and the conversion rules of these three compounds under the action of five kinds of catalyst were analyzed. Finally, the effect of HDS, HDN and HDO on coal tar was determined by comparing with the real fraction of coal tar. The results show that the different addition of phosphorus has different effects on the activity of coal tar hydrogenation. The appropriate amount of phosphorus can increase the activity of HDS, HDN and HDO of the catalyst, while the excessive phosphorus will inhibit the activity. By comparing the hydrogenation experimental results of model compounds and that of coal tar, it could be concluded that because the composition of coal tar is complex, various heteroatom compounds and various unsaturated hydrocarbons form competitive adsorption on the catalyst surface, resulting in the inhibition of the conversion of various heteroatom compounds. The phosphorus content of the Ni–Mo/γ-Al2O3 catalyst suitable for hydrogenation of coal tar is higher than that of the model compounds.