α-MnO₂supported Pd And Ru Catalyzed The Oxidation Of 5-HMF To 2,5 Furandicarboxylic Acid And 2,5 Furandiformaldehyde

The shortage of fossil energy and its environmental pollution are a major problem in the world today.Biomass energy is both sustainable and environmentally friendly and has attracted the attention of many researchers.5-Hydroxymethylfurfural（5-HMF）has a wide range of sources,is simple to prepare,and can connect biomass raw materials with high value-added products.It is a representative compound for the biomass conversion platform.2,5-furandicarboxylic acid（FDCA）and 2,5-furandiformaldehyde（DFF）prepared by selective oxidation of 5-hydroxymethylfurfural can be widely used in pharmaceutical intermediates,bio-based plastics and other polymer materials,Has extremely high utilization value.Aiming at the problems of low utilization rate of precious metal catalysts and easy aggregation or leaching of active components in the current selective oxidation process of5-HMF,this paper designed and developed a one-pot hydrothermal method for preparing monoatomic precious metal catalysts,and prepared two monoatomic precious metals Catalyst:Pd-MnO₂and Ru-MnO₂.Through characterization techniques such as HRTEM,XRD,XPS,XAS,H₂-TPR,O₂-TPD,the morphological and structural characteristics of the catalyst were studied,and the activity of the catalyst was also investigated.For the Pd-MnO₂ catalyst prepared by the hydrothermal method,the atomic Pd doping into MnO₂can create the largest interface site and induce the metal-support interaction.On the other hand,Pd doping into the MnO₂framework will generate abundant oxygen vacancies,which can effectively activate molecular oxygen.The synergistic interaction between atomic palladium and the sites around the MnO₂support can effectively promote the oxidation of HMF.After reacting at atmospheric pressure and 120°C for 4 hours,HMF can be completely converted,and the yield of FDCA reaches 88.1%.For Ru-MnO₂catalyst,atom Ru doping into MnO₂can form oxygen-rich vacancies and improve oxygen mobility,and produce more active Ru³⁺to catalyst HMF selectively generate DFF,react at 1.5MPaO₂,120°C for 1.5hours,The HMF conversion rate is 100%,and the DFF yield is>99%.At the same time,the strong interaction between Ru and the MnO₂carrier makes it difficult for Ru to aggregate or lose.After the catalyst is recycled for 5 times,the activity is not significantly reduced.