keggin型Sn单取代的杂多酸盐催化合成环己酮

Keggin-type Tin Mono-substituted Heteropolyacid Salt Catalyst in the Synthesis of Cyclohexanone

摘要:

以钨酸钠、乙酸钴、四氯化锡为原料，通过酸化法制备了Sn单取代的杂多酸钾盐K7MⅡW11SnⅣO39OH(M=Co,Fe,Ni,Zn，Mn)及季铵盐QHxCoⅡW11 SnⅣO39OH,采用傅里叶转换红外光谱（FTIR）、X射线衍射（XRD)及电感耦合等离子体原子发射光谱法(ICP-AES)对杂多酸盐进行了表征。以环己醇选择性氧化制备环己酮为探针反应，考察了杂多酸盐的催化性能。结果表明，在质量分数30%的过氧化氢水溶液为氧化剂，催化剂(C4H9)4NHxCoⅡW11SnⅣ为0.25mmol，反应温度85℃，反应时间2h，环己醇0.05mol,过氧化氢0.2mol,乙腈0.2mol的条件下，环己醇的转化率及环己酮的选择性分别可达95.68%，96.75%，并推断出了可能的反应机理，即过度金属Sn为催化反应的活性中心。

Abstract:

Using sodium tungstate﹑cobalt acetate and stannic chloride as raw materials, Sn-substituted heteropoly acid potassium salt K7MⅡW11SnⅣO39OH (M =Co,Fe,Ni,Zn,Mn) and quaternary ammonium salt were synthesized by the acidification method, and characterized by Fourier transform infrared (FTIR), X-ray diffraction (XRD) and Inductively Coupled Plasma-Atomic Emission Spectrometry(ICP-AES). Its catalytic activity was measured in the oxidation of cyclohexanol to cyclohexanone with mass fraction 30% aqueous hydrogen peroxide as an oxidant. The conversion of cyclohexanol and the selectivity of cyclohexanone were found to be as high as 95.68% and 96.75% under the optimum conditions which the quantity of catalyst (C4H9)4NHxCoⅡW11SnⅣ was 0.25mmol, cyclohexanol was 0.05 mol, hydrogen peroxide was 0.2 mol, acetonitrile was 0.2 mol at 85℃for 2 h, and a possible reaction mechanism of the oxidation of cyclohexanol was concluded that transition metal Sn was act as catalytic active center.