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 CoNPs@Co-N-C core–shell structured catalyst where Co nanoparticles (CoNPs) are encapsulated tightly by nitrogen-doped graphitic carbon shells (NG), while Co single atoms (CoSA) 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 CoNP and CoSA 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 CoNP-NG-CoSA composite sites on regulating the hydrogenation active centers and provide a guideline for the further development of highly efficient acid-resistant hydrogenation catalysts.