Sstudy On Inhibition Effects Of Vanadium Substituted Heteropoly Acid (W,P) And Application Research

Heteropoly compounds are polynucler complexes with oxygen bridge, because they have unique molecular structure and they are easy to design and assemble, now it has widely used in new and efficient catalyst, Medicine, magnetic materials, high-quality sub-conductors, electrochromic materials, inorganic filler additives, selective electrode and fuel cell etc.This paper is to determine the inhibition effects of vanadium substituted heteropoly acid(W, P). Four novel vanadium atom substituted series of Dawson-type heteropoly acid (W, P) H7P2W17VO62·30H2O (marked Dawson-V1), H8P2O62·14H2O (marked Dawson-V2), H9P2W15V3O62·24H2O (marked Dawson-V3) and H10P2W14V4 O62·36H2O (marked Dawson-V4) and three novel vanadium atom substituted series of Keggin-type heteropoly acid (W, P) H4PW11V040·15H20 (marked Keggin-V1),H5PW 10V2O40·23H2O(marked Keggin-V2), H6PW9V3O40·24H2O (marked Keggin-V3) were prepared by joining the raw materials step by step, acidificating step by step, circumfluencing, boiling and extracting with diethyl ether. Their structure were determined by IR, XRD, TG.The inhibition effects of vanadium substituted Dawson-type and Keggin-type heteropoly acid (W, P) were measured by differential scanning calorimetry (DSC). The results show that the polymerization velocity of MMA decreases continuously as the amount of the heteropoly acids in the same series and the polymerization velocity decreases continuously as the increasing of vanadium atomic number in the different series heteropoly acids, i.e. the greater vanadium atom number in the heteropoly acid, the better inhibition effect of heteropoly acid. On the whole, the inhibition effects of Dawson-type heteropoly acid are better than Keggin-type heteropoly acid.In the basis of the above experiment, H8[P2W14V4O62H2]·36H2O is identified as a catalyst to synthesze a-alcohol methacrylate esters. The influence of four factors of catalyst concentration,reaction temperature,molar ration of alcohol to ester and reaction time on the esterification rate was discussed by developing orthogonal pilot program Lg(34). The optimum conditions which determined by orthogonal experiment were as follows:the molar ration ofα-Methyl methacrylate to n-butanol was 1.2:1, weight of heteropolyacid was 0.6% of total weight, reaction time was 8h, reaction temperature was 125℃. Under the optimum conditions, the yield was about 96.2%. H8[P2W14V4O62H2]·36H2O is also applized to catalyze the esterification between dodecanol and methacrylic acid. The influence of four factors of catalyst concentration,reaction time,molar ration of alcohol to acid and the volume of toluene on the esterification rate is discussed by developing orthogonal pilot program L9(34). The results show the best reaction conditions are that dodecanol and methacrylic acid molar ratio is 1.3:1, the mass fraction of catalyst is 0.4%, the volume of toluene is 10mL and reaction time is 2h. Under the optimum conditions, the yield was about 80%.