Study On The Synthesis Of Heteropoly Acid Salt Catalyst By Ionic Liquid Thermal Synthesis And Its Catalytic Performance

Heteropoly compounds are called green,economical,efficient,non-corrosive and non-toxic catalysts due to their acidity,redox properties,thermal stability,and"quasi-liquid phase"or"pseudo-liquid phase"behavior,and become green catalyst research hotspots in the field.However,the heteropoly compounds also have the problems of complicated preparation process and unsafety,because the raw materials of different components need to be added gradually during the preparation process,and the acid-base reagent is needed to adjust the solution to a specific pH after each step.Therefore,it is necessary to find a simple and safe preparation method.Ionothermal synthesis is a new method for synthesizing advanced catalyst materials compared with traditional hydrothermal synthesis.By reducing the steps,the preparation process is more convenient and safe,which conforms to the concept of green catalysis.In this paper,we select ionothermal synthesis synthesis method to prepare a highly efficient heteropoly acid salt catalyst by adjusting the synthesis conditions,and take the cyclohexanol oxidation reaction as test reaction to obtain its catalytic reaction data.The main research contents are as follows:1.Preparation of heteropoly phosphotungstate catalystBy using ammonium metatungstate and ammonium paratungstate as tungsten sources,phosphoric acid as phosphorus source,cesium carbonate as cesium source,cesium phosphorus metatungstate heteropoly acid salt and phosphorus paratungstate cesium hetero poly acid salt are prepared in different proportions of mixed solution of ionic liquid?1-Butyl-3-methylimidazolium Bromide?and water,and the two types of hetero poly acid salt were analyzed by FT-IR,XRD,SEM and BET to confirm structure,morphology and pore size distribution of heteropoly acid salt.The results show that both of catalysts are mesoporous materials,and the organic ligand[Bmim]⁺of brominated 1-n-butyl-3-methylimidazole?[bmim]Br?was successfully introduced.The acid salt exhibits a sheet-like morphology,and the phosphorus cesium tungstate heteropoly acid salt exhibits a prismatic morphology.2.Study on the catalysis of cyclohexanol to cyclohexanone by phosphorus metatungstate cesium heteropoly acid saltPhosphorus metatungstate cesium heteropoly acid salt is used to catalyze the oxidation of cyclohexanol to cyclohexanone.The effects of the catalyst type,temperature,n?30%H₂O₂?/n?cyclohexanol?ratio,time and the catalyst amount on the reaction are investigated.The optimal conditions of the catalytic reaction:0.2 g CsPW-80 catalyst,acetonitrile is 5 ml,n?30%H₂O₂?:n?cyclohexanol?is 4,temperature is70?,time is 5 h,conversion rate of cyclohexanol is 72.64%,selectivity of cyclohexanone is over 99.99%.3.Study on the catalysis of cyclohexanol to cyclohexanone by phosphorus paratungstate cesium heteropoly acid saltPhosphorus paratungstate cesium heteropoly acid salt is used to catalyze the oxidation of cyclohexanol to cyclohexanone.The effect s of the catalyst type,the temperature,n?30%H₂O₂?/n?cyclohexanol?ratio,time and the catalyst amount on the reaction are investigated.The optimal conditions of the catalytic reaction:0.2 g CsPW'-80 catalyst,acetonitrile is 5 ml,n?30%H₂O₂?:n?cyclohexanol?is 4,temperature is70?,time is 8 h,conversion rate of cyclohexanol is over 99.99%,selectivity of cyclohexanone is 98.46%.