Effect of reduction temperature on the performance of Ni₂P/Ti-MCM-41 catalyst in hydrodesulfurization

The supported Ni₂P/Ti-MCM-41 catalyst is prepared by temperature-programmed reduction method with nickel chloride (NiCl₂·6H₂O) as the nickel precursor, ammonium hypophosphite (NH₄H₂PO₂) as the phosphorus precursor and Ti-MCM-41 as the support. The Ni₂P/Ti-MCM-41 catalyst was characterized by H₂-TPR, XRD, BET, XPS, and TEM; the effect of reduction temperature on its catalytic performance in hydrodesulfurization (HDS) was investigated by using dibenzothiophene (DBT) as a model compound. The results show that the precursors on the catalyst prepared in this way can be reduced at 318℃, which is at least 200℃ lower than that prepared by traditional methods. Pure Ni₂P phase can be obtained by reduction at 350-500℃; the low reduction temperature is in favor of forming small Ni₂ Pcrystallite size. The Ni₂P/Ti-MCM-41 catalyst obtained at a reduction temperature of 400℃ exhibits the highest surface area, the best dispersion of Ni₂P crystallite size, the lowest surface phosphorus content and the highest HDS activity; under 340℃, 3.0MPa, a H₂/oil ratio of 500 (volume ratio) and a weight hourly space velocity (WHSV) of 2.0h^-1, the conversion of DBT for HDS reaches 99.4%.