Effect of MnO2 Crystal Type on the Oxidation of Furfural to Furoic Acid

The base-free oxidation of furfural by non-noble metal systems has been challenging. Although MnO2 emerges as a potential catalyst application in conditions, its catalytic efficiency still needs to be improved. crystalline form is an important factor affecting the ability furfural. For this reason, four forms (?, ?, ?, and ?-MnO2) were selected. Their performance surface functional groups analyzed compared detail. Only ?-MnO2 exhibited excellent activity, achieving 99.04% conversion 100% Propo.FA (Only furoic acid was detected HPLC product) under while ?, ?-MnO2 below 10%. Characterization XPS, IR, O2-TPD other means revealed that most abundant active oxygen species hydroxyl groups, which are responsible for best ?-MnO2. This work achieves green efficient over catalysts.