The mechanism of additives to unsupported Ni-Mo hydrodesulphurization catalyst

A series of highly active unsupported Ni-Mo hydrodesulphurization catalyst prepared by coprecipitation method and characterized effect of additives Al₂O₃ on the structure performance by BET, and Py-IR tests. The results indicated the additives Al₂O₃ greatly increased the pore diameter and specific surface area and mechanical strength. And it increased the acid of L acid while formatted B acid sites. This paper also characterized the influence of phosphorus to the Ni-Mo catalyst. BET results show that phosphorus blocked the catalyst pore structure, specifically reduced the surface area of the Ni-Mo. But TPR, FT-IR studies have shown that phosphorus can form Al-P-O structure, weaken interaction between active phase and Al₂O₃, while the amount of tetrahedral Mo species was decreased and octahedral Mo species was increased.