(CTAB)_9[Sb_(1.0)W_9O_(33)]催化氧化环己醇制备环己酮

以柠檬酸为络合剂,采用溶胶-凝胶法制备了K9Sb1.0W9O33],再用十六烷基三甲基溴化铵(CTAB)对其改性,得到相转移催化剂(CTAB)9Sb1.0W9O33];以过氧化氢氧化环己醇制取环己酮为探针反应,考察了催化剂制备过程中n(Sb)∶n(W)以及n(过氧化氢)∶n(环己醇)、n((CTAB)9Sb1.0W9O33])∶n(环己醇+过氧化氢)、反应温度、反应时间等反应条件对氧化反应的影响。实验结果表明,当n(Sb)∶n(W)=1.0∶9时制得的(CTAB)9Sb1.0W9O33]催化剂活性最高;氧化反应的适宜条件为:n(过氧化氢)∶n(环己醇)=1.5、n((CTAB)9Sb1.0W9O33])∶n(环己醇+过氧化氢)=0.001 2、反应温度353K、反应时间2.0h;在此条件下,环己醇转化率为97.4%,环己酮选择性为99.7%。催化剂经XRD表征,揭示了(CTAB)9Sb1.0W9O33]的微观结构和内在规律性,搀杂少量CTAB,Sb1.0W9O33]9-保持原来的基本结构,Sb1.0W9O33]9-与CTAB+之间存在协同效应,有效提高了环己酮的选择性。

(CTAB)9 [ Sb1.0W9O33 ] Catalysts for Catalytic Oxidation of Cyclohexanol to Cyclohexanone

K9Sb1.0W9O33] was prepared by sol-gel method with citric acid as the complexing agent and then was modified with cetyltrimethylammonium bromide(CTAB) to obtain phase-transfer catalysts(CTAB)9Sb1.0W9O33].Catalytic oxidation of cyclohexanol with hydrogen peroxide to cyclohexanone over the(CTAB)9Sb1.0W9O33] was investigated.The effects of n(Sb): n(W) in the catalysts,n(H2O2) ∶n(cyclohexanol),n((CTAB)9Sb1.0W9O33]) ∶n(cyclohexanol+H2O2),reaction temperature and reaction time on the catalyst performance were studied.The results showed that under the optimal conditions of n(Sb) ∶n(W) 1.0 ∶9,n(H2O2) ∶n(cyclohexanol) 1.5,n((CTAB)9Sb1.0W9O33]) ∶n(cyclohexanol+H2O2) 0.001 2,reaction temperature 353 K and reaction time 2.0 h,conversion of cyclohexanol was 97.4% and selectivity to cyclohexanone reached 99.7%.The catalysts(CTAB)9Sb1.0W9O33] were characterized by means of XRD.Sb1.0W9O33]9-still maintained its original structure after the oxidation,possessing a cooperative effect with CTAB+ during the oxidation,which effectively heightened the selectivity to cyclohexanone.