Thermodynamic and Kinetic Analysis of the Aqueous Phase Hydrogenation of Maleic Anhydride to Succinic Acid over a Pd/C Catalyst

The synthesis of succinic acid (SA), one of the monomers of the biodegradable plastic polybutylene succinate, has become a crucial technology for the development of the industry. In this work, thermodynamic analysis and kinetic investigations were performed to elucidate the process of aqueous phase hydrogenation of maleic anhydride (MAN) to SA. Thermodynamic calculations indicate that the reduction of MAN hydrolysis product maleic acid (MA) and its isomerization product fumaric acid (FA) to SA are irreversible reactions, while the isomerization of MA to FA is a reversible reaction. For commercial irregular shaped Pd/C catalyst, the effects of internal and external diffusion on the reaction were analyzed, in which the external diffusion effects are negligible. Finally, based on thermodynamic calculations, a pseudo-first-order kinetic model including the isomerization product FA was established. The satisfactory agreement between experimental data and model calculations demonstrates the reliability of the kinetic model.