Maleic anhydride was selectively hydrogenated to succinic anhydride over metallic nickel catalysts, such as Raney Ni and Ni nanoparticles, in liquid phase at reaction temperature lower than 130 degrees C. When the Raney Ni catalyst in solvents with different polarities catalyzed the hydrogenation of maleic anhydride to succinic anhydride, the solvent with high polarity favored the hydrogenation of maleic anhydride to succinic anhydride as compared to that with low polarity. When the hydrogenation reaction was catalyzed by Raney Ni catalyst at 100 degrees C and H-2 pressure of 2.5 MPa for 360 min in acetic anhydride, the conversion of maleic anhydride and the selectivity of succinic anhydride were 99.6% and 100%, respectively. In solvent-free reaction system, gamma-butyrolactone as a byproduct with the maximum selectivity of 14.8% was produced at 130 degrees C. All of the Ni nanoparticles with average diameters ranging from 8 to 313 nm showed higher catalytic activity than Raney Ni in liquid phase hydrogenation of maleic anhydride to succinic anhydride. When the Ni nanoparticles with an average diameter of 8 nm were used as the catalysts in the liquid phase hydrogenation at 80 degrees C and 2 MPa of H-2 for 150 min and the weight ratio of catalyst to maleic anhydride was 1:100, the conversion of maleic anhydride and the selectivity of succinic anhydride were 99.8% and 100%, respectively. The small particle size and the polycrystalline structure of Ni nanoparticles played important roles in the liquid phase selective hydrogenation of maleic anhydride to succinic anhydride. (C) 2012 Elsevier B.V. All rights reserved.