Influence of Si/Al molar ratio on the hydrogenation, isomerization and ring opening of naphthalene over silica-alumina supported Ni2P catalyst

Ni2P catalysts supported on amorphous silica-alumina (ASA) with various Si/Al molar ratios (n) of ∞, 3.40, 1.28, 0.57, 0.21, 0.10 and 0, were prepared using a co-impregnation method followed by temperature-programmed reduction. The resultant Ni2P/ASA-n catalysts were characterized by means of X-ray diffraction (XRD), N2 adsorption and desorption, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), temperature-programmed ammonia desorption (NH3-TPD) and FTIR spectroscopy of adsorbed pyridine (Py-IR). The catalytic properties were tested towards naphthalene hydrogenation, isomerization and ring opening in a fixed bed reactor under the following reaction conditions of P = 4 MPa, LHSV = 3 h−1, H2/oil = 600 volume ratio and T = 360 °C. It is found that the superior naphthalene hydrogenation ability was obtained over the Ni2P/ASA-0.57 catalyst, while higher isomerization and ring opening activity were achieved using Ni2P/ASA-0.21 as the catalyst. It is concluded that the high naphthalene hydrogenation capacity is relevant to the small Ni2P particle size and the isomerization and ring opening activity mainly depends on the acid amount of catalyst.