Hydrogenation of Succinic Acid to γ-Butyrolactone (GBL) Over Palladium-Alumina Composite Catalyst Prepared by a Single-Step Sol-Gel Method

Mesoporous palladium-alumina (Pd-A) composite catalysts prepared by a single-step sol-gel method were calcined at various temperatures to control palladium surface area and acidity. The Pd-A catalysts were characterized by XRD, BET, N-2 adsorption-desorption isotherm, H-2 chemisorption, Al-27 MAS NMR, NH3-TPD, and HR-TEM analyses. Liquid-phase hydrogenation of succinic acid to gamma-butyrolactone (GBL) was carried out over Pd-A catalyst in a batch reactor. The effect of calcination temperature of Pd-A catalyst on the palladium surface area and catalytic performance was investigated. In the hydrogenation of succinic acid, conversion of succinic acid increased with increasing palladium surface area of Pd-A catalyst. Selectivity for GBL depended on the formation of succinic anhydride (an intermediate product formed by acid catalysis) and by-products (formed by hydrogenolysis). Nevertheless, yield for GBL also increased with increasing palladium surface area of Pd-A catalyst. Thus, palladium surface area played an important role in enhancing the catalytic performance of Pd-A catalyst in the hydrogenation of succinic acid to GBL.