改性多金属氧簇应用于环己醇选择性催化氧化制取环己酮

Selective Catalytic Oxidation of Cyclohexanol to Cyclohexanone Over Modified Polyoxomeatalate Catalysts

以柠檬酸为络合剂,采用溶胶-凝胶法制备了多金属氧簇K9[Sb1.0W9O33],再用十六烷基三甲基溴化铵(CTAB)对其改性,得到改性多金属氧簇(CTAB)9[Sb1.0W9O33];以过氧化氢氧化环己醇制取环己酮为探针反应,考察了制备催化剂的原料配比n(Sb)/n(W)以及n(H2O2)/n(Cyclohexanol)、n((CTAB)9[Sb1.0W9O33])/n(Cyclohexanol+H2O2)、反应温度、反应时间等反应条件对氧化反应的影响。结果表明,当n(Sb)/n(W)=0.11时制得的(CTAB)9[Sb1.0W9O33]催化剂活性最高;氧化反应的适宜条件为、n(H2O2)/n(Cyclohexanol)=1.5、n((CTAB)9[Sb1.0W9O33])/n(Cyclohexanol+H2O2)=0.0012、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)9[Sb1.0W9O33]的微观结构和内在规律性,掺入少量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。

K9[Sb1.0 W9O33 ] was prepared by sol-gel method with citric acid as complexing agent, which was modified with cetyltrimethylammonium bromide （CTAB） to obtain （CTAB）9 [-Sb1. 0 W9 O33 ]. Catalytic oxidation cyclohexanol to cyclohexanone by H2 02 over （CTAB） 9 [Sb1. 0 W9 O33 ] was used as a probe reaction to investigate the effects of atomic ratio n（Sb）/n（W） in preparation of catalyst, the reaction conditions of n （ H2 O2 ） /n （Cyclohexanol）, n （ （ CTAB ） 9 [- Sbl. 0 W9 033 -] ） /n （ Cyclohexanol ＋ H2O2 ）, reaction temperature（T）, reaction time（t）. The results showed that the optimum conditions were n（Sb）/n（W） =0. 11, n（ H2O2 ）/n （Cyclohexanol） = 1.5, n （（CTAB）9 [- Sb1. 0 W9 033 ]）/n （Cyclohexanol ＋ H2O2）=0.0012, T= 353 K, t=2.0 h, under which the conversion of cyclohexanol reached 97.4%, selectivity to cyclohexanone reached 99.7~. （CTAB）9 [Sb,.0W9033-] was detected by means of XRD, and its micro-structure and essence disciplinarian of were disclosed. [-Sb1. 0 W9 O33 ]9- still maintained its original structure, possessing a cooperative effect with CTAB＋ during the oxidation of cyclohexanol, resulting in the selectivity to cyclohexanone enhanced effectively.