Inexpensive but Highly Efficient Co–Mn Mixed‐Oxide Catalysts for Selective Oxidation of 5‐Hydroxymethylfurfural to 2,5‐Furandicarboxylic Acid.

Abstract: A highly active and inexpensive Co–Mn mixed‐oxide catalyst was prepared and used for selective oxidation of 5‐hydroxymethylfurfural (HMF) into 2, 5‐furandicarboxylic acid (FDCA). Co–Mn mixed‐oxide catalysts with different Co/Mn molar ratios were prepared through a simple solid‐state grinding method—a low‐cost and green catalyst preparation method. The activity of these catalysts was evaluated for selective aerobic oxidation of HMF into FDCA in water. Excellent HMF conversion (99 %) and FDCA yield (95 % ) were obtained under the best reaction conditions (i.e., 120 °C, 5 h, Co–Mn mixed‐oxide catalyst with a Co/Mn molar ratio of 0.25 calcined at 300 °C (Co‐Mn‐0.25) and 1 MPa O₂). The catalyst could be reused five times without a significant decrease in activity. The results demonstrated that the catalytic activity and selectivity of the Co–Mn mixed‐oxide catalysts prepared through solid‐state grinding were superior to the same Co–Mn catalyst prepared through a conventional coprecipitation method. The high catalytic activity of the Co‐Mn‐0.25 catalyst was attributed to its high lattice oxygen mobility and the presence of different valence states of manganese. The high activity and low cost of the Co–Mn mixed‐oxide catalysts prepared by solid‐state grinding make it promising for industrial application for the manufacturing of polyethylene furanoate, a bioreplacement for polyethylene terephthalate, from sustainable bioresources. [ABSTRACT FROM AUTHOR]