金催化剂对乙醇选择性氧化反应的催化性能研究

发布时间：2018-03-19 21:37

  本文选题：乙酸乙酯　切入点：金催化剂　出处：《昆明理工大学》2016年硕士论文　论文类型：学位论文

【摘要】：乙酸乙酯(Ethyl Acetate,简称EA),是一种环境友好型工业溶剂,同时它也是食用香料的合成香精之一。目前,国内较为成熟的生产乙酸乙酯的工艺为乙酸酯化法,但该法所采用的催化剂是腐蚀性极强的浓硫酸,这使得生产设备的腐蚀情况比较严重,并伴随着环境污染较大和后期处理困难等问题。与之相比,以新型催化剂的研发为核心的乙醇脱氢法只需以乙醇为原料即可完成生产,同时乙醇可以通过农作物发酵而来,不必完全依赖不可再生资源来制造。因此,若能开发出稳定、高效的催化剂来推动乙醇脱氢反应的工业化,就可以大幅提升乙醇脱氢法在乙酸乙酯生产中的竞争地位。本论文工作以人工合成的层状双羟基金属氢氧化物(简称LDHs)以及从天然膨润土经过提纯改型钠化的钠基蒙脱石(简称NaMMT)为载体,利用本课题组前期研究的金催化剂制备方法,获得了不同类型的层状载体负载的金催化剂,并将其首次应用于催化乙醇液相氧化反应,系统研究了包括载体的类型、金的负载量、催化剂的用量、催化剂的焙烧温度、以及乙醇液相反应条件(反应温度、反应压力、反应时间)等因素对催化活性的影响。实验研究结果表明：(1)按照金的理论负载量为2wt%,将纳米金分别负载在LDHs载体和蒙脱石载体上制备的金催化剂,在乙醇的液相氧化体系中表现出的催化性能差异较大,其中蒙脱石负载的催化剂基本不具有活性,而三种不同层板组成的LDHs负载的金催化剂的活性都比较高。(2)以金溶胶负载在LDHs载体上所制备的2wt%-Au-MgAl-LDHs为催化剂,通过单因素实验以及多因素的响应曲面分析法优化乙醇选择性氧化反应的条件(反应温度、反应压力和反应时间),得出的优化反应条件为：反应温度128℃,反应压力5MPa,反应时间7h,在此最适宜反应条件下,乙醇的转化率为58%,乙酸乙酯的选择性为87%。(3) 2wt%Au-MgAl-LDHs催化剂在多次利用后依然具有较高的活性,在128℃,5Mpa的反应条件下反应7h,重复使用4次后,该催化剂依然可以使乙醇的转化率达到50%,乙酸乙酯的选择性达到86%,表明该催化剂对乙醇液相选择氧化反应具有良好的稳定性。
[Abstract]:Ethyl Acetate (EAC) is a kind of environment-friendly industrial solvent, and it is also one of the synthetic flavours of edible spices. At present, the mature process of producing ethyl acetate in China is acetic acid esterification. However, the catalyst used in the method is highly corrosive concentrated sulfuric acid, which makes the corrosion of the production equipment more serious, and accompanied by the environmental pollution and the difficulty of post-treatment and other problems. The ethanol dehydrogenation process with the core of the research and development of the new catalyst can be completed by using ethanol as the raw material, and ethanol can be produced through the fermentation of crops without having to rely entirely on non-renewable resources to produce it. Therefore, if it can be developed steadily, Highly efficient catalysts to promote the industrialization of the dehydrogenation of ethanol, In this paper, the layered dihydroxyl metal hydroxides (LDHs) and sodium from natural bentonite were purified from natural bentonite, which can greatly enhance the competitive position of ethanol dehydrogenation in ethyl acetate production. Base montmorillonite (NaMMT) as carrier, Different kinds of layered supported gold catalysts were obtained by using the preparation method of gold catalysts previously studied by our research group. The catalysts were first applied to the liquid phase oxidation of ethanol. The types of supports were systematically studied. The amount of gold supported, the amount of catalyst used, the calcination temperature of catalyst, and the reaction conditions of ethanol liquid phase reaction (reaction temperature, reaction pressure, reaction pressure), The experimental results show that the gold catalyst prepared on the LDHs and montmorillonite supports is loaded on the LDHs and montmorillonite respectively according to the theoretical loading amount of gold at 2 wts. the effect of reaction time and other factors on the catalytic activity is studied. In the liquid phase oxidation system of ethanol, the catalytic performance of montmorillonite was different, and the catalyst supported on montmorillonite had little activity. The activity of the three kinds of gold catalysts supported on LDHs with different laminates was higher than that of the gold sol-supported gold catalysts. The gold sol supported on the LDHs support was used as the catalyst for the preparation of 2wt- Au-MgAl-LDHs. The conditions (reaction temperature, reaction pressure and reaction time) of ethanol selective oxidation reaction were optimized by single factor experiment and multi-factor response surface analysis. The optimum reaction conditions were obtained as follows: reaction temperature 128 鈩，

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