Preparation Of Supported Heteropolyacid Salts And Its Application In Oxidation Of Cyclohexane

Selective oxidation of saturaced hydrocarbons is of great importancefrom a fundamental and applied point of view.Because of the high strengthand weak polarity of C-H bonds, the C-H bond activation is difficult andalkanes are relatively inert.Besides, due to the prodcucts is active than theraw material, the deep oxidation to carbon dioxide and water easilyoccurred. Therefore, to control alkane selective oxidation effectively, is achallenging problems. In this thesis, the development of selective oxidationof cyclohexane to KA oil on supported heteropoly acids using H₂O₂ asoxidant in liquid-phase were carried out.Selective oxidation of cyclohexane to cyclohexanol andcyclohexanone was performed over SiO2-supported Dawson cobaltsubstitute heteropolyacid salts catalysts synthesized by immersion methodand were characterted by FT-IR, XRD,BET. The effects of Coamount,hydrochloric acid concentration, catalysts loadings, differentsupports, support methods and reaction conditions were investigated.Intypical processes, 35%CoH7P2Mo15V3O62/SiO2 which was in ultrasonic afterthe SiO2 treated in 3mol/L HCl solution has the highest activity of catalysts.The conversion of cyclohexane was 56.22% and the total yield ofcyclohexanol and cyclohexanone was 17.19% under the conditions of theamount of 35% CoH₇P₂Mo₁₅V₃O₆₂/SiO₂ catalyst 0.2g, H₂O₂ with w (H₂O₂) =50% 13.6g(0.2mol)amounting to 0.1 mol, reaction time 10h, the temperature75℃.Heteropolyacid salts catalysts supported on silylated attapulgite wereprepared by incipient wetness impregnation and characterized by XRD,BET,FT-IR.The effects of cyclohexane oxidation was evaluated by the differentsupports, catalysts loadings, reaction conditions and recycling times.Theresults show that the supported on silylated attapulgite CoH₇P₂Mo₁₅V₃O₆₂has enhanced the capacity over cyclohexane oxidation. Recycle catalyst canbe directly reused after drying, catalytic activity not significantly reduced.Under the optimal conditions, theconversion of cyclohxane was 35.28 %and the total yield of cyclohexanol and cyclohexanone was 12.48%.Experimentsshow that the supported CoH₇P₂Mo₁₅V₃O₆₂ heteropolyacid salts is one kind of perspective catalyst, in order to separate from products, littleequipment and environmental pollution.