二维蛭石基催化剂的制备及其在合成气甲烷化中的应用

发布时间：2018-01-07 11:32

本文关键词：二维蛭石基催化剂的制备及其在合成气甲烷化中的应用　出处：《石河子大学》2017年硕士论文　论文类型：学位论文

【摘要】：伴随着世界经济的迅速发展和人口的急剧增加,能源消费量不断增长,近年来石油燃料日益匮乏、天然气供不应求,加之我国能源结构特点为富煤、贫油、少气,煤的清洁利用技术对缓解我国的能源危机有重要意义,煤清洁化利用的一个重要途径是煤制天然气。煤制天然气的关键是催化剂,综合催化性能和催化剂的成本,Ni是最理性的催化剂活性组分,然而在甲烷化反应过程中催化剂活性组分易团聚烧结和积碳,造成催化剂的失活,采用合适的催化剂载体可抑制催化剂活性组分的团聚烧结并提升催化剂的抗积碳性能,从而提高催化剂的催化性能与稳定性。二维材料的研究自单层石墨烯被成功制备出来之后进入一个突飞猛进的时代,二维材料具有较大的比表面积,大量配位不饱和的表面原子,具有原子厚度的平面结构,以及确定的暴露晶面等性质被广泛应用于电催化、多相催化以及单原子催化中,在未来的多相催化领域二维材料将会有更广阔的应用前景。蛭石作为一种天然的二维材料,有良好的机械性能、阳离子交换、吸附性、膨胀性能等,且其层间距可调、吸附性能佳、阳离子交换容量大、机械强度大、耐磨性强等,很适合作为催化剂载体。甲烷化反应常用的催化剂载体为Al2O3,Mg O,Ti O2,Si O2,Zr O2等,蛭石作为一种天然的镁铝硅酸盐非金属矿石,拥有Mg,Al,Si,Ca,Fe,Ti等元素,适合作为甲烷化催化剂载体。新疆尉犁蛭石和煤储量丰富,以蛭石作为煤制天然气催化剂载体,可同时提高新疆尉犁蛭石的利用价值并实现煤的清洁化利用。一、二维膨胀蛭石负载Ni作为催化剂在甲烷化反应中的应用。以双氧水为膨胀剂将原蛭石膨胀制备出膨胀蛭石,并用做甲烷化反应催化剂载体,研究其甲烷化性能。由于蛭石比表面积较小,经过传统马弗炉焙烧所得到的催化剂催化Ni O颗粒比较大,且催化性能不理想。改变加热方式,使用微波炉700W加热4 min所制备的催化剂Ni O颗粒比较小且分散比较均匀,同时也表现出了良好的甲烷化性能。400 o C时微波辅助制备的催化剂达到99.6%CO转化率,93.8%的CH4选择性,远优于普通加热焙烧催化剂的催化性能。二、二维蛭石基Si O2纳米筛负载Ni作为催化剂在甲烷化反应中的应用。通过混合酸处理膨胀蛭石除去蛭石中的其他组分以制备二维Si O2纳米筛,并将其用作甲烷化催化剂载体,也是首次将二维的Si O2用于甲烷化反应。相比于三维MCM-41分子筛,二维Si O2纳米筛制备的催化剂有更好的甲烷化催化性能。主要是三维的MCM-41分子筛孔道容易被较大的Ni颗粒堵塞,导致在反应过程中处于孔道内的活性组分不能参与催化反应,而二维的Si O2为二维平面结构且表面有很多直径接近2 nm的小孔,能够固定住Ni颗粒,使其在甲烷化过程中不易团聚长大,从而有更好的催化性能。三、二维蛭石基水滑石负载Ni作为催化剂在甲烷化反应中的应用。通过混合酸处理膨胀蛭石的废液中含有大量的Mg2+,Al3+离子,并含有少量的Ca,Fe,Ti元素,将其制备成水滑石,该水滑石不仅含Mg,Al两种组分,而且还含有少量的Ca,Fe等元素,而Ca,Fe是甲烷化催化剂的良好助剂,能够减小活性组分金属的颗粒,提升活性金属组分的分散程度,并改善活性金属组分与催化剂载体之间的相互作用力。因此,这种含Ca,Fe等元素的蛭石基水滑石为载体所制备的催化剂比于纯Mg Al水滑石为载体所制备的催化剂有更好的甲烷化催化性能。
[Abstract]:Along with the rapid development of international economy and the increase of population, energy consumption increases in recent years, the increasing scarcity of fuel oil, natural gas demand, coupled with the characteristics of China's energy structure is rich in coal, oil, natural gas, clean coal utilization technology is of great significance to ease China's energy crisis, one of the most important the way of coal clean utilization of coal gas. The key of coal and natural gas is the catalyst, comprehensive catalytic performance and the cost of the catalyst, Ni catalyst is the most rational, but in the methanation catalyst in the reaction process of active components agglomerate sintering and carbon deposition, resulting in the deactivation of the catalyst. The catalyst carrier suitable sintering agglomeration can inhibit the active component of the catalyst and catalyst to enhance the resistance of carbon deposition, so as to improve the catalytic performance and stability of the catalyst. The research of single layer graphene is a two-dimensional material It was made into a rapid development era, the two-dimensional material has larger surface area, a large number of coordination unsaturated surface atoms, planar structures with atomic thickness, and determine the exposure of crystal surface properties has been widely used in electrocatalysis, multiphase catalysis and catalysis in a single atom, a more broad application prospects in the future in the field of heterogeneous catalysis. The two-dimensional material will be a natural vermiculite as two-dimensional material has good mechanical properties, cation exchange, adsorption, expansion properties, and its spacing is adjustable, adsorption performance, cation exchange capacity, high mechanical strength, strong wear resistance so, it is suitable as a catalyst carrier. The catalyst carrier methanation reaction used for Al2O3, Mg O, Ti O2, Si O2, Zr O2, vermiculite as a natural aluminum magnesium silicate non metal ores, have Mg, Al, Si, Ca, Fe, Ti and other elements, As for the methanation catalyst carrier. Xinjiang Yuli vermiculite and abundant coal reserves, coal and natural gas by using vermiculite as catalyst carrier, can also improve the utilization value of Xinjiang Yuli vermiculite and implementation of clean coal utilization. A two-dimensional, vermiculite supported Ni as catalyst application in methane reaction using hydrogen peroxide as bulking agent. The original vermiculite prepared by expanded vermiculite, and used as methanation catalyst carrier, on the performance of methane. The vermiculite surface area is smaller, obtained through the traditional roasting in muffle furnace catalyst Ni O particles are relatively large, and the catalytic performance is not ideal. Change the heating mode, using microwave heating 700W 4 min Ni O catalyst particles prepared by relatively small and uniform dispersion, but also showed a good performance of.400 methanation catalyst o C was prepared by the microwave to reach 99.6%CO The rate of 93.8%, CH4 selectivity, catalytic performance is much better than conventional heating calcination. Two, load Ni as catalyst in the reaction of methane in the application of two-dimensional vermiculite based Si O2 nano sieve. The acid treated vermiculite to remove vermiculite in other components in the preparation of two-dimensional Si O2 nano sieve, and it is used as a methanation catalyst carrier, is the first time that the two dimensional Si O2 for methanation reaction. Compared to the three-dimensional MCM-41 molecular sieve, methane catalytic performance of 2D Si O2 nano catalyst preparation is better. The MCM-41 is the three main channels of the molecular sieve are easily Ni particles larger blockage, resulting in the active group the channel can not participate in the catalytic reaction in the reaction process, and the Si O2 for 2D planar structure and the surface has many small holes diameter of approximately 2 nm, can fix Ni particles, the cluster is not easy in the process of methane Grow, which has better catalytic performance. Three, two-dimensional vermiculite based hydrotalcite supported Ni as catalyst in the reaction by using methane. Through waste mixed acid treatment of expanded vermiculite containing large amounts of Mg2+, Al3+ ion, and contains a small amount of Ca, Fe, Ti elements, the preparation of hydrotalcite the hydrotalcite, not only containing Mg, Al two components, but also contains a small amount of Ca, Fe and other elements, and Ca, Fe is a good assistant of methanation catalyst, can reduce the active component of metal particles, enhance the degree of dispersion of active metal component, the interaction between groups and improve the activity of gold and the catalyst carrier. Therefore, the Ca, Fe and other elements of vermiculite based hydrotalcite as carrier catalyst prepared by Mg Al than in pure hydrotalcite as methane catalytic performance of the catalysts prepared by the better.

【学位授予单位】：石河子大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ426;TE665.3

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