Reducing the Ni₂P Particle Size Through the Silicon–Aluminium Coordination for Efficient Hydrogenation Saturation of Naphthalene

Though alumina and silica are well-known and widely used supports, they have notable drawbacks, such as the formation of the AlPO₄ phase and inadequate metal–support interactions with nickel phosphide. This study investigates the synergistic effects of silica and alumina on the physicochemical properties and catalytic performance of nickel phosphide catalysts. Catalysts supported by alumina (Al₂O₃), silica (SiO₂), and a composite silica-alumina (ASA) have been simultaneously prepared using a straightforward isopyknic co-impregnation method in order to eliminate the influence of preparation conditions. The results indicated that Ni₂P/SiO₂ exhibited poor dispersion, while Ni₂P/Al₂O₃ showed a larger particle size along with the formation of the AlPO₄ phase. The coordination between silicon and aluminum facilitated the reduction of nickel phosphate to nickel phosphide (Ni₂P) and inhibited the formation of AlPO₄. Ni₂P/ASA demonstrated an improved dispersion and smaller particle size. Therefore, a comparative study of the Ni₂P/SiO₂, Ni₂P/ASA, and Ni₂P/Al₂O₃ performance revealed the superior catalytic efficacy of the SiO₂–Al₂O₃ supported Ni₂P in the naphthalene hydrogenation.