Selective catalytic hydrogenation of naphthalene to tetralin over a Ni-Mo/Al2O3 catalyst

Abstract

The selective catalytic hydrogenation of naphthalene to high-value tetralin was systematically investigated. A series of Al 2 O 3 catalysts containing different active metals (Co, Mo, Ni, W) were prepared by incipient wetness impregnation. The effects of different active metals forms (oxidation, reduction, sulfuration) and reaction conditions on naphthalene hydrogenation were investigated and the catalysts were characterized by XRD, XPS, BET, NH 3 -TPD and SEM. Especially, Ni-Mo/Al 2 O 3 was first used in this reactive system. The results show that the oxidative 4%NiO-20%MoO 3 /Al 2 O 3 is the best catalyst for the preparation of tetralin. The conversion of naphthalene and the selectivity of tetralin can reach 95.62% and 99.75% respectively at 200 °C, 8 h and 6 MPa. Compared with reduced and sulfureted 4%NiO-20%MoO 3 /Al 2 O 3 catalysts, oxidative 4%NiO-20%MoO 3 /Al 2 O 3 has a well dispersed and uniform monolayer of the active metals, larger pore volume and size, and larger total acidity. NiO-MoO 3 /Al 2 O 3 has a synergistic effect between NiO activity and MoO 3 selectivity. Reaction of naphthalene hydrogenation proceeds stepwise and not in consecutive steps. Ni/Al 2 O 3 has strong hydrogenation capability, resulting in the direct conversion of naphthalene to decalin, while Mo/Al 2 O 3 has a high selectivity for tetralin. NiO-MoO 3 /Al 2 O 3 has a synergistic effect between NiO activity and MoO 3 selectivity.