Effect of ZrO2 in Ni2P/ZrO2–Al2O3 catalysts on hydrotreating reactions

Abstract

Catalysts 60% Ni/Al₂O₃ and 60% Ni/4% ZrO₂–Al₂O₃ were prepared, and it was found that the addition of ZrO₂ promoted reduction while maintaining the high dispersion of supported nickel. Upon phosphidation by triphenylphosphine (PPh₃) in the liquid phase, the two catalysts were converted into corresponding Ni₂P/Al₂O₃ and Ni₂P/ZrO₂–Al₂O₃ catalysts with highly dispersed Ni₂P particles (6.3 and 6.8 nm, respectively), high CO uptakes (305 and 328 μmol g⁻¹, respectively) and thus high activities for the hydrodesulfurization (HDS) of dibenzothiophene (DBT) and hydrogenation of tetralin to decalin. In particular, the Ni₂P/ZrO₂–Al₂O₃ was found to be significantly more active than the Ni₂P/Al₂O₃ for the HDS of DBT and hydrogenation of tetralin to decalin. Although the presence of ZrO₂ did not affect the heat of adsorption of CO on Ni₂P, it significantly increased the heat and uptake of adsorption of H₂ on Ni₂P, which might account for the increased activity of Ni₂P promoted by ZrO₂.