【作者】 蔡贞玉；

【导师】 朱明乔；

【作者基本信息】 浙江大学 ， 化学工程， 2011， 硕士

【摘要】 环己烯氧化可以得到许多有用的产物,如：生产农药克螨特的环氧环己烷,生产邻苯二酚的邻环己二醇,以及生产醇酮类医药的环己烯醇和环己烯酮等,这四种产物常用∑C6来表示。随着精细化学工业的发展,∑C6的需求量越来越大。由于环己烯分子含有一个易发生氧化反应的不饱和C=C双键和多个活性α-H原子,导致发生氧化反应的选择性较差,且产物∑C6分布复杂。因此对温和条件下环己烯催化氧化具有高活性、高选择性催化剂的研究,引起了学术界和工业界的广泛关注。本论文分为六章。主要研究了活性炭负载纳米金催化剂,锰分子筛负载纳米金催化剂和埃洛石纳米管负载纳米金催化剂的制备、表征及催化性能。论文的具体内容如下：第一章为文献综述,概括了近十年环己烯氧化催化剂的研究进展,其中重点介绍了在温和条件下具有较高活性的纳米金催化剂。第二章总结了实验原料、实验设备的使用,以及表征手段和实验方法的确定,具体为：环己烯氧化反应在高压反应釜(容积：30 mL,最大承受压力6 MPa)中进行,以正庚烷为内标物用气相色谱对产物进行分析,内标法处理实验数据。采用ICP-AES、XRD、TEM、SEM、EDX、BET等手段对催化剂进行表征。第三章对活性炭负载的纳米金催化剂用于环己烯氧化进行了实验研究。采用浸渍还原法制备了催化剂Au/C,通过ICP-AES、XRD、TEM手段对其进行了表征。另外,Au/C经过AgNO3和Co(NO3)2·6H2O的改性可以得到双金属元素催化剂Au-Ag/C和Au-Co/C。在无溶剂环己烯氧化体系中对该系列催化剂进行活性评价,发现Au和Ag存在协同效应。在80℃、氧气压力0.4 MPa下反应12 h,在理论载金量为1.0(wt.)%、载银量为1.0(wt.)%的Au-Ag/C催化剂上,环己烯转化率为27.6%,∑C6产物的选择性为88.9%,特别是邻环己二醇的选择性达到了47.6%。第四章考察了无溶剂体系中环己烯在八面体锰分子筛负载的纳米金催化剂Au/OMS-2和Au/La-OMS-2上的氧化。Au/OMS-2和Au/La-OMS-2在负载量较低的情况下对环己烯氧化生成环己烯酮和环己烯醇有较好的催化效果。在80℃、氧气压力0.4 MPa下反应24 h,Au/La-OMS-2(0.24)催化剂上,环己烯转化率达到48.0%,环己烯醇和环己烯酮的选择性之和超过84%。该催化剂循环使用4次时,活性没有明显的降低。催化剂良好的活性和稳定性是由纳米金颗粒和La/OMS-2分子筛的特殊结构和组成共同决定的。第五章制备了埃洛石纳米管负载纳米金催化剂Au/HNTs。在无溶剂、氧气氧化环己烯反应体系中,该催化剂对环己烯醇和环己烯酮有较好的选择性和稳定性,发现Au/HNTs在环己烯氧化中存在纳米尺寸效应。第六章对本文的主要研究内容进行了归纳总结,对纳米金催化剂上环己烯氧化的研究发展提出了一些建议。更多还原

【Abstract】 Many useful products can be abtained from cyclohexene oxidation, such as cyclohexene oxide (raw material of agricultural chemical propargite), cyclohexane-1,2-diol (used to produce pyrocatechol),2-cyclohexene-1-ol and 2-cyclohexene-1-one (pharmaceutical intermediates), etc.. These four products mentioned above are collectively calledΣC6.The demands ofΣC6 increase a lot with the development of fine chemistry. However, as there is a C=C bound and fourα-H atoms in the cyclohexene molecule, the oxidation of cyclohexene is often inefficient because various products could be obtained at a time with unsatisfactory conversion or selectivity. Therefore, the research of heterogeneous catalysts for cyclohexene oxidation with good catalytic performance under mild conditions attracts the academic and industrial world.This theme includes six chapters, mainly reports carbon-supported gold catalyst, OMS-2 supported gold catalyst, HNTs supported gold catalyst, and their preparation methods, characterization and catalytic performance in cyclohexene oxidation. The theme is list in detail as follows:Chapter 1 gives a review about the progress of catalysts for cyclohexene oxidation in the last decade, mainly focusing on the nano gold catalysts, which has good catalytic performance under mild conditions.Chapter 2 introduces the experimental materials, experimental equipments, and the method of catalyst characterization and catalyst test. PTFE-lined autoclave (Capacity=30 mL, pressure maximum 6 MPa) was choosen for cyclohexene oxidation, n-heptane was used as internal standard for product analysis and catalysts were characterized by inductively coupled plasma-atomic emission spectrometry (ICP-AES), X-ray-diffraction (XRD), transmission electron microscope (TEM), scanning electron microscope (SEM), energy dispersive X-ray analysis (EDX) and Brunauer-Emmet-Teller (BET).Chapter 3 is about cyclohexene oxidation on carbon-supported gold catalysts. Carbon-supported gold catalysts Au/C were prepared by an impregnation-reduction method and characterized by ICP-AES, XRD and TEM. Au/C catalysts were modified by AgNO3 and Co(NO3)2·6H2O to obtain bi-metallic catalysts Au-Ag/C and Au-Co/C. Their catalytic performance was tested in the oxidation of cyclohexene in an autoclave without any solvent. The results showed that Ag doping can significantly enhance the catalytic performance of carbon-supported gold catalyst. Au(1.0 wt.%)-Ag(1.0 wt.%)/C has been found to be an efficient catalyst for the oxidation of cyclohexene with a conversion 27.6% at 80℃and 0.4 MPa for 12 h while selectivity forΣC6 products exceeding 88.9%, especially the selectivity of cyclohexane-1,2-diol up to 47.6%.Chapter 4 deals with solvent-free oxidation of cyclohexene over catalysts Au/OMS-2 and Au/La-OMS-2 with molecular oxygen. The OMS-2 supported gold catalyst with low gold loading and La doping has shown high efficiency for cyclohexene oxidation to 2-cyclocyhexene-1-ol and 2-cyclocyhexene-l-one. Au/La-OMS-2(0.24) was found to be an efficient catalyst for the oxidation of cyclohexene with a high conversion (48.0%). More than 84% selectivity for 2-cyclohexene-1-ol and 2-cyclohexene-l-one was obtained. The high activity and good stability of catalyst Au/La-OMS-2 is ascribed to both the effect of gold and the structure and composition of La-OMS-2.Chapter 5 deals with halloysite nanotubes (HNTs) supported gold catalyst. The selective oxidation of cyclohexene to 2-cyclohexene-1-ol and 2-cyclohexene-l-one has been investigated over Au/HNTs with molecular oxygen in a solvent-free system. The results show that the catalytic performance of Au/HNTs is well and the catalytic activity over recycled catalyst remains well. Moreover, the nano-size effect of gold is found for cyclohexene oxidation.Chapter 6 summarizes the main contents of the dissertation, and several research suggestions about cyclohexene oxidation on nano gold catalysts are proposed.更多还原