Strategic Metal Doping in MnO<i><sub><i>x</i></sub></i> Catalysts Unlocks High-Yield 2,5-Furandicarboxylic Acid Production via Tailored Lattice Oxygen Activity and Oxygen Vacancies
Qing Liu, Yuan Gong, Jing Zeng, Yinghong Zhao, Jia Lv, Zhicheng Jiang, Changwei Hu, Yingdong Zhou
Abstract
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 (O L ) 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, Mn 6 Ce 1 O x (Mn/Ce molar ratio of 6), with the highest surface oxygen vacancy (O V ) concentration and activated O L, achieved a high FDCA yield of 97.2% with a generation rate of 1520 μmol FDCA g cat –1 h –1 under mild conditions (120 °C, 1 MPa O 2, 8 h). Catalyst characterization results revealed that the metal dopants modulated the strength of Mn–O bonds, thereby influencing O L activity and O V concentration. Incorporating Ce ions into the MnO x lattice weakened Mn–O bond strength, enhancing O L mobility and promoting O V formation. This reactive O L, acting as the active oxygen species for HMF oxidation, could be efficiently regenerated via the Mars–van Krevelen mechanism. The abundant O V on Mn 6 Ce 1 O x promoted the adsorption of both O 2 and HMF. The synergistic roles of O V and O L contributed to the high activity of this catalyst in converting HMF to FDCA. This study provides critical insights into the strategic regulation of O L activity in Mn-based oxides, offering promising avenues for improving the efficiency and cost-effectiveness of biomass-based chemical production via catalytic oxidation.