Strategic Metal Doping in MnOx Catalysts Unlocks High-Yield 2,5-Furandicarboxylic Acid Production via Tailored Lattice Oxygen Activity and Oxygen Vacancies

2,5-Furandicarboxylic acid (FDCA), derived from the oxidation of 5-hydroxymethylfurfural (HMF), is emerging as a viable biomass-based monomer for bioplastic production, offering a sustainable alternative to a petroleum-derived monomer. This study systematically investigates lattice oxygen (OL) activation in Mn-based oxides through doping with transition metals (Ce, Zr, La, and Sm) to enhance the aerobic oxidation of HMF to FDCA. Among the prepared catalysts, Mn6Ce1Ox (Mn/Ce molar ratio of 6), with the highest surface oxygen vacancy (OV) concentration and activated OL, achieved a high FDCA yield of 97.2% with a generation rate of 1520 μmolFDCA gcat–1 h–1 under mild conditions (120 °C, 1 MPa O2, 8 h). Catalyst characterization results revealed that the metal dopants modulated the strength of Mn–O bonds, thereby influencing OL activity and OV concentration. Incorporating Ce ions into the MnOx lattice weakened Mn–O bond strength, enhancing OL mobility and promoting OV formation. This reactive OL, acting as the active oxygen species for HMF oxidation, could be efficiently regenerated via the Mars–van Krevelen mechanism. The abundant OV on Mn6Ce1Ox promoted the adsorption of both O2 and HMF. The synergistic roles of OV and OL contributed to the high activity of this catalyst in converting HMF to FDCA. This study provides critical insights into the strategic regulation of OL activity in Mn-based oxides, offering promising avenues for improving the efficiency and cost-effectiveness of biomass-based chemical production via catalytic oxidation.