Effect of preparation methods on the structure and naphthalene hydrogenation performance of Ni₂P/SiO₂ catalyst

Ni₂P/SiO₂ catalysts were prepared by temperature-programmed reduction method and hypophosphite disproportionation method to investigate their naphthalene hydrogenation performance. The prepared catalysts were characterized by ICP-OES, X-ray diffraction, H₂ temperature-programmed reduction, N₂ adsorption-desorption method and transmission electron microscopy, etc. Results showed that Ni₂P/SiO₂ catalyst with pure Ni₂P crystal phase could be successfully prepared by the temperature-programmed reduction method and hypophosphite disproportionation method. When the naphthalene hydrogenation reaction was performed at 340℃, 4 MPa, H₂/oil volume ratio of 600, and a weight hourly space velocity (WHSV) of 20.8 h^-1, Ni₂P/SiO₂ catalyst prepared by the temperature-programmed reduction method possessed superior hydrogenation activity. This result was ascribed to the advantages of temperature-programmed reduction method. It not only installed the higher number of Ni₂P species (CO adsorption amount 21.6 μmol/g) over SiO₂, but also obtained more weak acid sites on the catalyst surface, which promoted the adsorption of aromatic hydrocarbons and subsequently resulted in the higher hydrogenation activity. Furthermore, when the temperature-programmed reduction method was used to prepare Ni₂P/SiO₂ catalyst, the lower Ni/P molar ratio was more beneficial to enhance the naphthalene hydrogenation activity of the as-prepared catalyst.