Abstract: The selective hydrogenation of phthalic anhydride to phthalide in liquid phase was studied with nickel catalysts supported on SiO2, TiO2,γ-Al2O3, TiO2-SiO2, and TiO2-Al2O3 carriers prepared by the incipient wetness impregnation method, using nickel nitrate as the nickel precursor. The results showed that the nickel catalyst supported on TiO2-SiO2 with well-dispersed active nickel species exhibited the highest activity and selectivity for phthalide. Then, a series of Ni/TiO2-SiO2 catalysts were prepared by sol-gel method through changing the preparation conditions. The sol-gel Ni/TiO2-SiO2 catalyst using water as the solvent had much better catalytic performance than the one using alcohol as solvent and the one prepared by the impregnation method. Improperly high calcination temperature and reduction temperature caused sintering of nickel species and reduced the catalytic activity. In addition, the nickel precursors obviously affected the performance of the catalysts. The catalyst prepared from nickel chloride showed higher activity and selectivity than the catalysts prepared from nickel sulfate and nickel nitrate. Over this catalyst, the conversion of phthalic anhydride was 100%, and the selectivity for phthalide was 88.5%.

Key words: sol-gel method, nickel, titania, silica, phthalic anhydride, hydrogenation, phthalide