Study On Design And Properties Of Immobilized Heteropoly Acid

Heteropoly acids (HPA) have great utilities in many fields because of their strong acidity and oxidation-reduction properties. Nevertheless, HPA have many drawbacks, such as lower specific surface area, easy deactivation, difficult callback and poor thermal stability. Therefore, the appropriate supports are desirable. To support HPA, keep and improve its activities by the means of organic-inorganic or inorganic-inorganic hybrid.In the work, H3PMo12O40-polymer composite film catalyst was prepared, and then it was characterized by DSC, FT-IR and SEM. The heteropoly acid supported by polymer was synthesized conveniently by organic-inorganic blend, and the catalyst can be callbacked and regenerated easily after reaction. Used it as catalyst, ethanol and acetic acid were esterified as ethyl acetate. It was found that the yield of ethyl acetate can reach 70.5% under the optimized conditions.The nano composite materials such as H3PW12O40/TiO2, H6P2W18O62/TiO2 and H3SiW12O40/TiO2 were prepared by solvothermal method. The products obtain under different conditions were characterized by means of XRD, TEM, FT-IR, UV-Vis. The influences of various solvothermal conditions including reaction time, temperature and pH were investigated. The HPA/TiO2 particles exhibited a uniform anatase structure. The Keggin structure of heteropoly anion kept well. The photocatalytic activity of catalysts was tested with methyl orange as the objective decomposition substance. The effect of the solution pH, catalyst quantity and the initial concentration of the methyl orange on decolorizing efficiency of the solution were discussed in detail. The results show that the HPA/TiO2 has a higher photocatalytic activity than purchased P-25 particles.Phosphotungstic acid with Dawson structure acted as acceptor of electrons and polyvinyl pyrrolidone acted as donor of electrons, photochromic complex of system was prepared. Their photochromic properties were investigated by XRD, FT-IR, UV-Vis spectra. The UV-Vis spectra showed that this type of system had an excellent photochromic behavior.