Influence of the preparation method on Ni/SiO2 catalysts for selective hydrogenation of succinic anhydride to γ-butyrolactone

Selective hydrogenation of succinic anhydride (SAA) to gamma-butyrolactone (GBL) is a novel and efficient route to synthesize GBL. Highly efficient Ni/SiO2 catalysts with large specific surface area were prepared with three different methods and applied for selective hydrogenation of SAA to GBL. The preparation methods significantly affected the Ni species dispersion, surface properties and catalytic properties of Ni/SiO2 catalysts. Ni/SiO2 prepared with the ammonia evaporation method (Ni/SiO2-AE) had the largest specific surface area of 291 m(2) g(-1) and smallest Ni crystallite size of 8 nm, but the aggregation of Ni species during the reaction would result in decline of catalytic activity. Ni/SiO2 prepared with the oxalic acid precipitation method (Ni/SiO2-OP) and sodium carbonate precipitation (Ni/SiO2-SP) showed similar textural properties. However, the strong surface acidity of Ni/SiO2-OP would facilitate the formation of tetrahydrofuran (THF). XPS results indicated that largest Ni-0/Ni2+ ratio was observed in Ni/SiO2-SP, leading to the lowest THF selectivity and highest GBL selectivity. Under the conditions of 185 degrees C, 3.0 MPa, WHSV = 0.2 h(-1), and molar ratio of H-2/SAA = 50, Ni/SiO2-SP showed a SAA conversion of 89.7% with a GBL selectivity of 96.2% and excellent stability during the 50 h test.