Highly Acid-Resistant CoNPs@Co-N-C Catalyst for the Efficient Aqueous-Phase Hydrogenation of Maleic Acid to Succinic Acid

Aqueous-phase hydrogenation holds significance in achieving the large-scale green production of succinic acid, but the acidic reaction environment poses a considerable challenge in the design of highly active and stable catalysts. Herein, we report a spatial-confinement strategy to fabricate a Co-NPs@Co-N-C core-shell structured catalyst where Co nanoparticles (Co-NPs) are encapsulated tightly by nitrogen-doped graphitic carbon shells (NG), while Co single atoms (Co-SA) are distributed homogeneously on the shells, which exhibits remarkable efficiency and stability in the aqueous-phase hydrogenation of maleic acid for the production of succinic acid in an acidic medium. The catalyst achieves 100% conversion of maleic acid, more than 98% selectivity toward succinic acid, and high stability for seven cycles without significant deactivation. The combined characterizations and density functional theory (DFT) calculations further indicate that Co-NP and Co-SA can concurrently optimize the electronic structure of the NG and promote hydrogen dissociation on the surface of the carbon shells. These findings shed light on the unique function of Co-NP-NG-Co-SA composite sites on regulating the hydrogenation active centers and provide a guideline for the further development of highly efficient acid-resistant hydrogenation catalysts.