Catalytic Oxidative Valorization of Biobased 5-Hydroxymethylfurfural over Multi-ligand Functionalized Polyoxovanadates

Abstract

The oxidative conversion of 5-hydroxymethylfurfural (HMF) to 2,5-diformylfuran (DFF) is an important reaction for the utilization of biomass resources. This process has garnered considerable research attention in both industry and academia, yet it still presents considerable challenges. To achieve an effective and mild oxidative upgrade of the HMF molecule, a multiorganic-ligand-functionalized polyoxovanadate catalyst, V₆O₆(OCH₃)₄(mIM)₆(C₆H₅PO₃)₄ (P₄V₆), has been successfully prepared by using both oxygen- and nitrogen-containing ligands. P₄V₆, characterized by its unique candy-like structure, demonstrates remarkable catalytic performance in converting HMF, achieving 95% conversion and 94% selectivity toward DFF under an O₂ atmosphere. Furthermore, P₄V₆ exhibits good stability and can be reused over five consecutive cycles without any substantial changes to its structure and catalytic performance. Comprehensive mechanistic investigations, supported by control experiments, kinetic studies, and spectral analyses, indicate a plausible four-step catalytic mechanism. This work provides a new perspective on the design of polyoxovanadate-based catalysts for biomass valorization.