Study of the Reaction Pathways for the Hydrogenation of Quinoline over Nickel Phosphide Catalysts

The nickel phosphide catalysts (Ni2P) were prepared using mesoporous molecular sieves as supports by isobaric co-impregnation. The Ni2P catalysts with different loading were characterized, which showed that the active phase on the surface of the catalysts was mainly Ni2P and the catalysts still retained the mesoporous structural characteristics of the supports. The catalysts were evaluated using a 10 mL fixed bed hydrogenation unit. The results showed that the nickel phosphide catalysts had a higher hydrogenation capacity than the sulphide catalysts and were able to preferentially hydrogenate and saturate most of the quinolines to decahydroquinolines, reduce the conversion of 1,2,3,4-tetrahydroquinoline to o-propylaniline and reduce the inhibition of reactivity due to competitive adsorption. The effect of catalyst on the path selectivity of quinoline hydrogenation was investigated, and the products of quinoline hydrogenation and denitrogenation consisted mainly of propylbenzene and propylcyclohexane, and propylcyclohexane accounted for 91.7% and propylbenzene for 4.8% under the conditions of nickel phosphide catalysts.