Room‐Temperature Synthesis of Magnesium Incorporated Into OMS‐2 Enables Highly Selective Oxidation of 5‐Hydroxymethylfurfural to 2,5‐Diformylfuran

Abstract

Selective oxidation of biomass‐derived 5‐hydroxymethylfurfural (HMF) to 2,5‐diformylfuran (DFF) remains a challenge. Herein, we prepared magnesium intercalated into cryptomelane‐type OMS‐2 to achieve ultrafine Mg‐OMS‐2 nanorods via room‐temperature coprecipitation. The results confirm that Mg 2+ cations are incorporated into the MnO 6 octahedral lattice of OMS‐2. The Mg 9% ‐OMS‐2 with 9 wt% Mg exhibits high catalytic activity for aerobic oxidation of HMF with 91% conversion and 99.9% DFF selectivity at 120 °C within 1 h. Experimental results and characterization demonstrate that the reaction follows the Mars–van Krevelen redox mechanism. It involves a redox cycle by a reduction of high valence state of Mn ions combined with the participation of lattice oxygen, whereas surficial oxygen vacancies (O vac ) are continuously replenished by aerial soluble oxygen. The reaction rate equation of HMF oxidation is expressed dependent on O 2 pressure and HMF concentration. Moreover, the predicted activities agree well with the measured activities in wide ranges of HMF concentrations and O 2 pressures. Therefore, the ultrafine Mg 9% ‐OMS‐2 nanorods, featuring efficient catalytic performance, facile regeneration, insightful mechanism, and kinetics descriptions present a significant potential toward practical applications.