Study On Synthesis Of Keggin-type P-V-Mo-W Heteropoly Acid And Application Research

Heteropoly compounds were attracted much attentions because of their unique structureand excellent features, therefore they were widely used in the field of catalyst, biology,medicine, material etc. In recent, most studies about Binary and ternary heteropolyacid werereported while quaternary Heteropoly acid which have three coordination elements were lessreported.Five Keggin-type P-V-Mo-W heteropoly acids of H4PVMoW10O40·15H2O(markedKeggin-Mo1)H4PVMo2W9O40·33H2O(marked Keggin-Mo2), H4PVMo3W8O40·16H2O(markedKeggin-Mo3),H4PVMo4W7O40·20H2O(marked Keggin-Mo4),H4PVMo5W6O40·29H2O(markedKeggin-Mo5) were prepared by joining the materials step by step, acidizing step by step,circulating boiled and extracting with diethyl ether, and characterized by IR, XRD and TGsubsequently for researching their proterties of polymerization inhibitor or catalyst.The inhibition of effects of the five Keggin-type heteropoly acids were measured bydifferential scanning calorimetry (DSC).The results show that the polymerization rate ofMMA decreases as the amount of the heteropoly acids increasing in the same series and thepolymerization rate of MMA decrease as the increasing of molybdenum atom number in thedifferent series heteropoly acids. It’s concluded that the greater molybdenum atom numberin the Keggin-type heteropoly acid the better inhibition effect of the heteropoly acid.In the basis of the above inhibition experiment, H4PVMo5W6O40·29H2O is identified as acatalyst to esterification reaction and transesterification. At first, the influence of four factorsof catalyst dosage, molar ration of alcohol to acid, reaction time and volume of toluene wasdiscussed by designing orthogonal pilot program L9(34) in cinnamic acid and n-butylalcohol esterification. The optimum conditions which determined by orthogonal experimentwere: the mole ratio of n-butyl alcohol to cinnamic acid was1.3:1, the mass ratio of catalystto cinnamic acid was0.4%, reflux time is2.5h and the volume of toluene was6mL. Under thebest condition, the yield was about87%. The H4PVMo5W6O40·29H2O was also used tosynthesize α-butyl methacrylate ester by transesterification. The influence of four factors ofcatalyst dosage, molar ration of alcohol to ester, reaction temperature and reaction time wasdiscussed by designing orthogonal experiment L9(34). The results showed the optimum were:the mole ratio of α-alcohol methacrylate ester to n-butyl alcohol was1:1.2, the mass ratio ofcatalyst to ester was0.5%, reaction temperature was125℃and reaction time was7.5h. Finally, the five Keggin-type series heteropoly acids was used as the photocatalyst todegradation of the methyl orange solution measuring by UV-VIS spectrophotometry. In thesame reaction conditions, all the five series heteropoly acids have photocatalytic activity andthe best one is H4PVMo4W7O40·20H2O.The effect of the solution acidity, catalyst quantity andthe initial concentration of the methyl orange on degradation were discussed in detail. Theoptimum reaction condion is the concentration of methyl orange is10mg/L, solution pH is2and the concentration of heteropoly acid is0.4g/L under the ultraviolet radiation.