Efficient epimerization of highly concentrated glucose to mannose over electronic structure-modulated Mo/NC catalyst

The catalytic conversion of concentrated glucose to mannose is of considerable interest due to the latter's therapeutic value, yet it is constrained by low catalytic efficiency. Herein, a Mo/NC-300 catalyst was constructed by introducing active Mo species into a nitrogen-doped carbon (NC) matrix via pyrolysis. The resulting catalyst demonstrated outstanding activity in the epimerization of high-concentration glucose (50 wt%) to mannose, achieving a high yield of 33.4 % and selectivity of 94.6 %, alongside an excellent productivity of 123.7 mmol·g cat −1 ·h −1 . Catalyst characterizations and density functional theory calculations revealed that the NC layer modulates the electronic structure of Mo species, shifting the d-band center upwards. This preferentially enhances glucose adsorption and lowers the epimerization energy barrier. Isotope labeling experiments further confirmed the reaction follows an intramolecular 1,2‑carbon shift mechanism. The catalyst also exhibited excellent stability and reusability, primarily attributed to the hydrophobicity imparted by the NC layer. This work not only provides a catalytic system that simultaneously overcomes the challenges of concentration, stability, and efficiency, but also offers insights into the role of electronic metal-support interaction in glucose epimerization.