γ‐Al₂O₃‐Supported and Unsupported (Ni)MoS₂ for the Hydrodenitrogenation of Quinoline in the Presence of Dibenzothiophene

Abstract

Abstract Supported MoS 2 /γ‐Al 2 O 3 and Ni‐MoS 2 /γ‐Al 2 O 3 as well as unsupported Ni‐MoS 2 were investigated in the hydrodenitrogenation (HDN) of quinoline in the presence of dibenzothiophene (DBT). The supported oxide catalyst precursors had a well‐dispersed amorphous polymolybdate structure that led to the formation of a highly dispersed sulfide phase. In contrast, the unsupported catalyst precursor consisted of a mixture of nickel molybdate and ammonium nickel molybdate phases that formed stacked sulfide slabs after sulfidation. On all catalysts, the reaction pathway for the removal of N in quinoline HDN mainly followed the sequence quinoline→1,2,3,4‐tetrahydroquinoline→decahydroquinoline→propylcyclohexylamine→propylcyclohexene→propylcyclohexane. The hydrodesulfurization of DBT proceeded mainly by direct desulfurization towards biphenyl. For both processes, the activity increased in the order MoS 2 /γ‐Al 2 O 3 <Ni‐MoS 2 /unsupported<Ni‐MoS 2 /γ‐Al 2 O 3 . The promotion of the MoS 2 phase with Ni enhances the activity of the unsupported catalyst to a greater extent than the supported one. However, the multiply stacked unsupported Ni‐MoS 2 exhibited lower rates than Ni‐MoS 2 /γ‐Al 2 O 3 because of its lower dispersion.