Preparation of ultrasmall Ni2P nanoparticles with low P/Ni ratios supported on SiO2 and an Al2O3-B2O3 mixed oxide for dibenzothiophene hydrodesulfurization

Abstract

Ultrasmall Ni2P nanoparticles with dimensions around 3 ∼ 5 nm supported on SiO2 (Ni-P/SiO2) and an Al2O3-B2O3 mixed oxide (Ni-P/AB) were prepared by a temperature-programmed reduction method using mixtures of Ni(NO3)2 and H3PO3 as precursors. The minimum P/Ni ratios of the precursors needed for the formation of phase-pure Ni2P on SiO2 and Al2O3-B2O3 were as low as 0.8 and 0.7, respectively. The introduction of B2O3 to γ-Al2O3 inhibited the formation of AlPO4 during the reduction process. For such small particles, the effect of Ni2P-support interaction became significant, resulting in different properties of the Ni-P/SiO2 and Ni-P/AB catalysts as well as different performances in the hydrodesulfurization of dibenzothiophene. The ultrasmall Ni2P nanoparticles in the Ni-P/SiO2 catalysts that possess weak Ni2P-support interaction were as active as large Ni2P particles on SiO2 and a macro-mesoporous Al2O3. These catalysts were one order of magnitude more active than the Ni-P/AB catalysts with strong Ni2P-support interaction.