Enhanced Basicity of MnOx‐Supported Ru for the Selective Oxidation of 5‐Hydroxymethylfurfural to 2,5‐Furandicarboxylic Acid

Abstract The present study focused on developing a stable basic MnOx support for Ru (RuMn) for the efficient oxidation of 5‐hydroxymethylfurfural (HMF) to 2,5‐furandicarboxylic acid (FDCA) in water in the absence of an external base. A series of MnOx supports, synthesized via hydrothermal approach using urea as precipitant, was prepared by thermal treatment at various temperatures (300–800 °C) before doping with Ru. The RuMn‐2 (1 wt % Ru, MnOx calcined at 400 °C) possessed a large number of basic sites (1.72 mmol g−1) based on CO2 temperature‐programmed desorption analysis, affording an FDCA yield of 87 % with a turnover frequency of 22 h−1. Transmission electron microscopy energy‐dispersive X‐ray spectroscopy elemental mapping of RuMn‐2 showed a high dispersion of Ru over the surface of MnOx, contributing to the efficient HMF oxidation. Moreover, X‐ray diffraction, X‐ray photoelectron spectroscopy, and H2 temperature‐programmed reduction indicated that the predominant MnO2 phase (ϵ‐MnO2) played a vital role in HMF oxidation. RuMn‐2 was recyclable for up to four runs without significant loss in the activity and retained its structural integrity.