Application Research And Preparation Of Dawson Type Multicomponent Heteropoly Compounds

Polyoxometalates(abbreviated as POMs), especially POMs containing vanadium, have been investigated extensively in catalytic field for their high catalytic performance and selectivity, moderate reaction conditions, non-corrosion, especially for their redox and acidic properties can be controlled at atomic or molecular levels by changing the chemical composition. Most of the research on POMs are molybdophosphoric and molybdovanadophosphoric one with Keggin-type structures. There are a few studies of the Wells-Dawson structures. The Wells-Dawson type POMs possess of unique properties for their especially physical structure:the double-functional property of acidity and redox, and the pseudoliquid-phase characteristic. Therefor, it has important research and industrial significance to develop their applied research in organic synthesis and catalytic field.Based on the investigation of literatures, this dissertation was focused on the research of some organic reactions catalyzed by molybdovanadophosphoric POMs catalytic systems.The main progress and research results have been obtained as follows:1.Preparation of cyclohexanol and cyclohexanone through Oxidation of Cyclohexane Over Cobalt Substitute for Dawson P-Mo-V as CatalystCyclohexane was oxidation to cyclohexanol and cyclohexanone under the condition with cyclohexane as raw material, H2O2 as oxidant and the Cobalt Substitute for Dawson P-Mo-V Heteropolyacid Salt as catalysts. The catalysts were characterized by FT-IR, XRD and 31P NMR. The reaction conditions such as the type of catalyst,the amount of catalyst and the H2O2, reaction time and temperature were investigated. Experimental results show that CO2H5P2MO15V3O62 have the highest activity of the catalysts, The conversion of cyclohexane was 88.35% and the yield to cyclohexanol and cyclohexanone was 16.32% under the conditions of the amount of Co2H5P2Mo15V3O62 catalyst 0.20 mmol,50% H2O2 amount 0.2mol, reaction time 10h, the reaction temperature 75℃.2.Preparation of benzaldehyde through Oxidation of toluene Over Dawson-type P-Mo-V Cobalt Heteropolyacid Salt The oxidation toluene of to benzaldehyde first used ComHn+2P2Mo18-nVnO62 as catalyst and 50% hydrogen peroxide as oxidant.The reaction conditions such as catalyst, solvent, reaction time, and temperature were investigated. The products were analysed by GC-MS and its mechanism was studied. At last, we acquired the optimal reaction conditions. In this system, The salt Co3H3P2Mo15V3O62 is the the best catalyst of oxidation of toluene. The catalyst system which Dawson-type Cobalt Substitute for Dawson P-Mo-V as catalyst and H2O2 as oxidant is base of oxidation of styrene.