Synthesis of nickel phosphide nano-particles in a eutectic mixture for hydrotreating reactions

Abstract

Ni²⁺ and H₂PO₂⁻ with a molar ratio of 1/3 were heated at 423 K in a eutectic mixture composed of choline chloride and urea, resulting in the formation of a mesoporous and amorphous material with surface area of about 210 m² g⁻¹. Heat treatment of this material in H₂ at 673 K led to the formation of crystalline Ni₂P (25%) supported on amorphous and mesoporous Ni₃(PO₄)₂-Ni₂P₂O₇ (shortened as NiPO) with a surface area of about 130 m² g⁻¹. The NiPO was presumably produced from the reaction of unreduced Ni²⁺ with PO₄³⁻ formed from the oxidation of H₂PO₂⁻ in the eutectic mixture, which might also act as a template for the formation of mesopores in NiPO. The catalyst 25% Ni₂P/NiPO exhibited a quite high uptake for the adsorption of CO (38 μmol g⁻¹), and thus it is quite active for the hydrodesulfurization of dibenzothiophene, hydrodenitrogenation of quinoline and hydrogenation of tetralin in a model diesel.