Hydrogenation of succinic acid to γ-butyrolactone (GBL) over palladium catalyst supported on alumina xerogel: Effect of acid density of the catalyst

Mesoporous alumina xerogel (AX) supports prepared by a sol–gel method were calcined at various temperatures to control their acid property. Palladium catalysts supported on mesoporous alumina xerogel (Pd/AX) were then prepared by an impregnation method. The Pd/AX catalysts were characterized by XRD, BET, NH3-TPD, N2 adsorption–desorption isotherm, and H2 chemisorption analyses. Liquid-phase hydrogenation of succinic acid to γ-butyrolactone (GBL) over Pd/AX catalyst was carried out in a batch reactor. The effect of acid property of Pd/AX catalyst on the catalytic performance was examined. In the hydrogenation of succinic acid, conversion of succinic acid and yield for GBL showed volcano-shaped curves with respect to calcination temperature of AX support. Selectivity for succinic anhydride (an intermediate product formed by acid catalysis) increased with increasing acid density of Pd/AX catalyst. Correlations between acid density of Pd/AX catalyst and catalytic performance also revealed that conversion of succinic acid and yield for GBL increased with increasing acid density of Pd/AX catalyst. Thus, acid density served as an important factor determining the catalytic performance of Pd/AX in the hydrogenation of succinic acid.