Synthesis, Characterization And Catalytic Performance Of Keggin Type Multicomponent Heteropoly Compounds

The Keggin type of heteropoly compounds(HPC)is very common and possess of unique properties:the double-functional property of acidity and redox,and the pseudoliquid-phase characteristic.They have been investigated extensively in catalytic field and material chemistry for their high catalytic performance and selectivity,moderate reaction conditions,non-corrosion,their easy synthesis, low cost,good thermal stability,especially for their redox and acidic properties can be controlled at atomic or molecular levels by changing the chemical composition.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 thesis was focused on the research of some organic reactions catalyzed by Keggin type multicomponent HPC catalytic systems.The main progress and research results have been obtained as follows:1.Oxidation of benzyl alcohol to benzaldehyde over Keggin Type multicomponent heteropoly compoundsMulticomponent heteropoly compounds,(Cpyr)3+xPVxMoyW12-x-yO40·nH2O (in that Cpyr=(C16H32C5H4N)+,x=0,1,2,3)with Keggin structure were synthesized and proved by FTIR and X-ray spectroscopies.With 30% aqueous hydrogen peroxide as oxidant,benzyl alcohol was efficiently oxidized to benzaldehyde over reaction-controlled phase-transfer catalysts.Effects of the type of catalyst,the amount of catalyst and H2O2,the kind of solvent,reaction temperature and time were investigated.Under the optimal conditions,i.e.,with 0.1 mol of benzyl alcohol, 0.04mmol of (Cpyr)5PV2Mo5W5O40 catalyst and 0.1mol of H2O2(in mass concentration of 30%),100℃as reaction temperature,10mL of water as the solvent,88.51% conversion of benzyl alcohol and 96.06% selectivity for benzaldehyde were achieved within 8h.2.Catalytic Oxidation of Ethylbenzene to Acetophenone over Keggin Structure Molybdovanadophosphoric Heteropoly CompoundsA series of Keggin type heteropoly compounds,(Cpyr)3+xPMo12-xVxO40·nH2O (in that Cpyr=(C16H32C5H4N)+,x=0,1,2,3),were synthesized and proved by FTIR and X-ray spectroscopies.With 50% aqueous hydrogen peroxide as oxidant, ethylbenzene was efficiently oxidized to acetophenone over the prepared phase-transfer catalysts. The effects of catalyst type,amount of catalyst and H2O2, the kind of solvent,reaction temperature and time were investigated.Under the following optimal conditions as followed:25mmol of ethylbenzene,0.2mmol of (Cpyr)5PMo10V2O4o catalyst and 0.1mol of H2O2(in mass concentration of 50%), 70℃as reaction temperature,and 25 mL of acetic acid as the solvent,a conversion rate of 80.75% for ethylbenzene can be obtained winthin 8 hours with a selectivity of 81.46% for acetophenone.3.Synthesis of Acetophenone cylic ethylic ketal by the Keggin Type Multicomponent heteropoly acidsA series of multicomponent heteropoly acids,H3+xPVxMoyW12-x-yO40·nH2O(in that x=1,2,3)with Keggin structure were synthesized and proved by FT-IR and X-ray spectroscopies.Acetophenone cylic ethylic ketal was efficiently synthesized over catalysts.Effects of the type of catalyst,the kind of water-carrying agents,the amount of catalyst and the water-carrying agents,the molar ratio of ethylene glycol to acetophenone,reaction temperature and time were investigated.Under the optimal conditions,i.e.,with 0.1mol of acetophenone,0.14mol of ethylene glycol and 0.4mmol of H6PV3MoW8O40 catalyst,110℃as reaction temperature,15mL of cyclohexane as the water-carrying agents,84.10% conversion of acetophenone and 99.42% selectivity for acetophenone cylic ethylic ketal were achieved within 6h.