高活性镍基催化剂的构建及其甲烷重整催化特性研究

发布时间：2018-02-21 09:59

本文关键词： 乙二醇柠檬酸钇甲烷重整合成气镍基催化剂　出处：《华南理工大学》2015年硕士论文　论文类型：学位论文

【摘要】：急速的工业发展和人口增长导致的石油过度消耗,引起了世界对全球变暖和有限石油储量消耗的关注。甲烷重整反应可以将甲烷转化为高附加值的合成气(H2和CO),然后合成气可以转变成各种化工产品,如甲醇、二甲醚和含氧化合物等。本论文从镍基催化剂的修饰和合成策略两个方面进行详细研究。合成以有机溶剂修饰的Ni基催化剂,并采用不同浸渍策略(分步浸渍和共浸渍)分别合成了二氧化硅和氧化铝负载的掺钇镍基催化剂,详细研究镍基体系催化剂在甲烷重整反应中的催化性能,通过X-射线粉末衍射(XRD)、氮气吸附-脱附曲线、程序升温还原(TPR)、透射电子显微镜(TEM)、傅里叶变换红外光谱(FT-IR)和热重分析技术(TG)等表征手段对催化剂结构进行详细解析,系统说明了有机助剂在提高催化性能中的关键作用;探讨含钇催化剂的合成策略(共浸渍法和分步浸渍法)对不同载体(Al2O3和Si O2)催化剂催化性能的影响,揭示了浸渍方法对于不同载体的影响,研究结果进一步阐明了对于镍基催化剂的助剂添加和载体修饰在催化剂结构和催化性能方面的优越性。本论文的研究成果对于完善现有镍基重整催化体系具有重要的指导意义。首先,合成了有机溶剂(乙二醇,柠檬酸)修饰的Ni CA-x/Si O2-EG催化剂,对Si O2载体通过不同醇类修饰,考察不同醇类有机助剂修饰Ni基催化剂对甲烷转化率的影响,获取修饰Si O2载体效果最好的醇类有机物;其次,考察不同含量的柠檬酸对Ni基催化剂物理化学特性的影响,获取添加柠檬酸的最佳含量;探索载体修饰和有机助剂添加对催化剂的协同作用。TPR结果表明随着柠檬酸添加量的增加,还原峰向高温方向移动,这归因于柠檬酸促进还原后催化剂形成较小的镍颗粒。TEM、XRD、FT-IR证实了添加有机助剂改性二氧化硅表面可以稳固金属镍物种,从而防止金属颗粒在高反应温度下聚合。最后,分别以Al2O3,Si O2为载体,采用不同的浸渍策略(共浸渍法和分步浸渍法)合成钇掺杂的镍基催化剂,研究了稀土元素钇对催化剂物理化学特性的改变,探讨了浸渍顺序对镍基催化剂结构和催化性能的影响。
[Abstract]:Excessive consumption of oil due to rapid industrial development and population growth, The world is concerned about global warming and consumption of limited oil reserves. Methane reforming can convert methane into high value-added syngas such as H _ 2 and CO _ 2, which can then be converted into a variety of chemical products, such as methanol, In this thesis, the modification and synthesis strategy of nickel based catalyst were studied in detail. The yttrium-doped nickel-based catalysts supported on silica and alumina were synthesized by different impregnation strategies (step-by-step impregnation and co-impregnation). The catalytic performance of nickel-based catalysts in methane reforming was studied in detail. The structure of the catalyst was characterized by X-ray powder diffraction (XRD), nitrogen adsorption-desorption curve, temperature programmed reduction (TPRT), transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TG). The key role of organic auxiliaries in improving catalytic performance was systematically explained, and the effects of synthesis strategies (co-impregnation and stepwise impregnation) of yttrium-containing catalysts on the catalytic performance of Al _ 2O _ 3 and Sio _ 2 catalysts with different supports were discussed. The influence of impregnation method on different carriers was revealed. The results further illustrate the advantages of additive addition and carrier modification in the structure and catalytic performance of nickel based catalysts. The research results in this paper are very important for the improvement of existing nickel based reforming catalytic systems. The guiding significance. First of all, Ni CA-x/Si O 2-EG catalyst modified by organic solvent (ethylene glycol, citric acid) was synthesized. The effect of different alcohols on methane conversion of Ni based catalyst modified by different alcohols was investigated. Secondly, the effects of citric acid on the physical and chemical properties of Ni based catalyst were investigated, and the optimum content of citric acid was obtained. The results showed that the reduction peak shifted to high temperature with the increase of citric acid content. This was attributed to the fact that citric acid promoted the formation of smaller nickel particles after reduction. TEMN XRDX FT-IR confirmed that the surface of silicon dioxide modified by organic additives could stabilize the metal nickel species and thus prevent metal particles from polymerizing at high reaction temperature. Yttrium doped nickel based catalysts were synthesized by different impregnation strategies (co-impregnation method and stepwise impregnation method) using Al _ 2O _ 3-Si _ 2O _ 2 as the carrier. The physical and chemical properties of the catalyst were studied by changing the rare earth element yttrium. The effect of impregnation order on the structure and catalytic performance of nickel-based catalyst was discussed.
【学位授予单位】：华南理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：O643.36;TE665.3

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