Interaction between Ni promoter and Al2O3 support and its effect on the performance of NiMo/γ-Al2O3 catalyst in hydrodesulphurization

A series of NiMo/γ-Al2O3 catalysts with different NiO loadings were prepared and characterized by XRD, BET, 27Al-MAS NMR, Py-IR and HRTEM. The activity of these NiMo/γ-Al2O3 catalysts in the hydrodesulphurization (HDS) of dibenzothiophene (DBT) was evaluated in a high pressure micro reactor; the interaction between Ni promoter and γ-Al2O3 support as well as its effect on the nanostructure of active MoS2 phase and HDS performance was then investigated. The results indicate that Ni promoter prefers to interact with the tetra-coordinated unsaturated aluminum sites on the support surface. With the increase of NiO loading, the average number of stacking layers for the MoS2 clusters in the sulfided NiMo/γ-Al2O3 catalysts is increased at the expense of the average length. As the slim MoS2 clusters are more active for the HDS of DBT, the addition of Ni promoter is then effective to enhance the catalytic activity of NiMo/γ-Al2O3 in HDS, but may lead to a slight decrease in the hydrogenation selectivity.