Selective Hydrogenation of Maleic Anhydride to Succinic Anhydride Over Nickel-palladium Catalysts

Hydrogenation of maleic anhydride (MA) to succinic anhydride (SA) over Ni-Pd bimetallic catalysts prepared by impregnation method has been studied at different Pd contents, pressures and temperatures. Catalytic activity was greatly influenced by the Pd content, pressure and temperature. Use of 5wt%Ni-0.02wt%Pd/clay catalyst, the 100% conversion for MA and 100% selectivity for SA were obtained for MA hydrogenation at normal pressure. The catalysts were characterized by an array of techniques, including X-ray diffraction (XRD) and H₂ temperature-programmed reduction (TPR). XRD and TPR studies showed that nickel was present as Ni²⁺ species on the support, and that there was no elemental nickel (Ni⁰) and Ni₂O₃ in the unreduced samples. XRD and TPR also showed that Pd was as amorphous existence on the catalysts.