Study On Inhibition And Catalysis Properties Of Vanadium Substituted Heteropoly Acid(Si,Mo)

With time going by, Acidity Chemistry had played a decisive role in the field of inorganic chemistry and coordination chemistry. In recent years, it has attracted much attention because of its good performance in the field of catalysis, medical and material, especially the inhibitor performance which presented for the past few years. Heteropoly acid can be used as an inhibitor in the process of synthesis of unsaturated lipid, due to oxidizing elements and cage-like structure. Polyacids Si-Mo-V was a new type of heteropoly acid which silicon as the central atom, molybdenum and vanadium as coordinating atoms. Until now, there was a few of systemic research about the synthesis methods of Vanadium substituted heteropoly acid(Si,Mo), meanwhile almost no dissertation about its inhibition properties.In this paper, Keggin type and Dawson type heteropoly acid were synthesized by adding acid gradually and extracted by ethyl ether. The structures of heteropoly acid were confirmed by IR, XRD, ICP-MS, TG and so on. Structures were shown as following: H5 Si Mo11VO40·13H2O(marked K-V1), H6 Si Mo10V2O40·13H2O(marked K-V2), H7 Si Mo9V3O40·17H2O(marked K-V3), H8 Si Mo8V4O40·11H2O(marked K-V4), H9 Si Mo7V5O40·15H2O(marked K-V5). H9Si2Mo17V1O62·21H2O(marked D-V1), H10Si2Mo16V2O62·17H2O(marked D-V2), H11Si2Mo15V3O62·24H2O(marked D-V3), H12Si2Mo14V4O62·22H2O(marked D-V4), H13Si2Mo13V5O62·18H2O(marked D-V5).According to the results of DSC, The reaction rate constant of self-polymerization of methyl methacrylate was obtained when heteropoly acid was added in the reaction system. At the same time, according to the reaction rate constant of different types of heteropoly acid, we can obtain that reaction rate constant was inversely proportional to the inhibitor performance, which indicated that reaction rate constant and the mount of heteropoly acid show inverse ratio, conversely, shown direct ratio with inhibitor performance. For the same type of heteropoly acid, with the increase amount of vanadium, reaction rate constant was decreased moreover inhibition was enhanced. Above results indicated that Dawson type of heteropoly acid shown better inhibitor performance than Keggin type when they were substituted by vanadium.In the basis of the above inhibition experiment, H9 Si Mo7V5O40·15H2O(marked K-V5) and,H13Si2Mo13V5O62·18H2O(marked D-V5) are identified as a catalyst to esterification and transesterification reaction. The influence of four factors of catalyst dosage, molar ration of alcohol to acid, reaction time and reaction temperature were discussed by designing orthogonal pilot program L9(34) in Acrylic acid and n-butyl alcohol esterification with K-V5. Then the influence of four factors of catalyst dosage, molar ration of alcohol to acid, reaction time and volume of toluene were discussed by designing orthogonal pilot program L9(34) in cinnamic acid and ethanol esterification with D-V5. At last, D-V5 is applied to catalyze the transesterification between butanol and methyl methacrylate. The influence of three factors of catalyst dosage, molar ration of alcohol to ester and reaction time was discussed by developing orthogonal pilot program L9(33).