Fabrication Of Polyoxometalate Nanofiber Materials And Their Catalytic Activity In Oxidation Transformation

Polyoxometalates?POMs?have strong Br???nsted acidity and redox chemistry,especially the high multielectron transformation,which can be widely used in the field of photoelectrical materials and catalysis.POMs are easily soluble in water and organic solvents,low surface area and poor cycling performance of POMs,it has greatly limited the application of POMs in catalysis.As a result,how to improve the reusability and stability of POMs has gradually been a hot research in POMs catalysis.To develop novel synthesis strategies for solid POMs and achieve the high efficiency and stability are the goals pursued by scientists.Electrospinning is a commonly used method for constructing one-dimensional nano-materials,and it is also an effective means to immobilize POMs.Based on the electrospinning technology,this dissertation focuses on the synthesis,characterization and catalytic oxidation performance of one-dimensional nanocomposites of POMs.The details were as follows:?1?Fabrication of[Al₂O₃/Polymethylmethacrylate]/[H₅PMo₁₀V₂O₄₀/Polymethylmethacrylate]?[Al₂O₃/PMMA]/[HPMoV/PMMA]?catalyst through electro-spinning technique.“Janus"bifunctional nanofiber catalyst.The morphology of "Janus" nanofiber catalyst was proved by IR,31P NMR,SEM and other methods.In the process of oxidizing starch and HMF,it was found that the activity of the catalyst was related to the supporting dosage of H₅PMo₁₀V₂O₄₀.When the dosage was 20%,the optimal catalytic oxidation effect was obtained.The optimal reaction conditions for the hydrogen peroxide-oxidized starch are:1.0 g starch,5 mg catalyst,70?,10 h,and the content of oxidized carboxyl groups in the oxidized starch is 0.55 mol/100 g.The optimal conditions for HMF oxygen oxidation was:63mg HMF,40mg catalyst,100?,6 h,82.6%HMF conversion and 54.8%DFF yield.Moreover,the catalyst shows good stability,and the reactivity after repeated use does not decrease significantly.