MOF-Derived Mn/N-Codoped Porous Carbon Enables Efficient and Rapid Oxidation of HMF to FDCA

Graphical This study develops a solid-state thermal (SST) synthesis method for the one-step preparation of MOF-derived Mn x @NC catalysts. Among these, the optimal catalyst (Mn 2.5 @NC) exhibits excellent activity, remarkable stability, and good recyclability for HMF oxidation to FDCA, achieving an FDCA yield of 94 % within 4 h at room temperature and maintaining its catalytic performance for five cycles without activity decay. Transforming the bio-based 5-hydroxymethylfurfural (HMF) into its oxidation product 2,5-furandicarboxylic acid (FDCA) offers an attractive route for synthesizing bioplastic monomers. However, significant challenges remain in developing efficient and stable non-precious metal catalysts. Here, we employed a solid-state thermal synthesis (SST) method to design and synthesize a series of metal-organic framework (MOF)-derived metal-nitrogen-carbon (M@NC) materials with gradient metal contents and low metal loadings, labeled as Mn x @NC, for converting HMF into FDCA through oxidation. Further investigations revealed that the amount of metal doping significantly influenced the catalyst structure, particularly in terms of defect quantity and specific surface area. The optimal catalyst, Mn 2.5 @NC, exhibited the largest specific surface area and the highest number of defects, achieving a 94 % FDCA yield within 4 h. Experimental results demonstrated that the recovered catalyst could be reintroduced into the reaction system and maintained selectivity comparable to that of the fresh catalyst for at least five cycles. Moreover, various characterizations of both fresh and recovered catalysts confirmed the great stability of Mn 2.5 @NC. This study provides advanced insights into the effective catalytic conversion of HMF to FDCA and highlights the importance of structural design and regulation in optimizing M@NC catalysts.