Promoting Effect of TiO₂on the Hydrodenitrogenation Performance of Nickel Phosphide

TiO 2 -containing bulk Ni 2 P catalysts (Ti x -Ni 2 P) were prepared by coprecipitation and in situ H 2 temperature-programmed reduction (TPR), and characterized by XRD, CO chemisorption, TEM, XPS, TPR, and NH 3 -TPD. Their hydrodenitrogenation performances were studied by using quinoline and decahydroquinoline (DHQ) as the model molecules. Both the hydrogenation and C−N bond cleavage activities of Ni 2 P were improved by the introduction of TiO 2 . The TiO 2 species were mainly located separately on the surface of the catalysts and had strong interactions with surface Ni and P species. The reducibility of the precursors as well as the surface electronic properties of Ni 2 P catalysts were affected by the addition of TiO 2 . Ti x -Ni 2 P showed higher CO uptake but less acid sites than Ni 2 P. The promoting effect of TiO 2 was discussed by considering the electronic interactions between surface Ti and Ni 2 P species and changes in the adsorption geometries of quinoline, DHQ, as well as the partially hydrogenated intermediates over Ti x -Ni 2 P.