甲烷重整纳米催化材料的研究

发布时间：2018-07-08 10:37

本文选题：甲烷二氧化碳重整 + 双金属催化剂　；参考：《北京化工大学》2017年硕士论文

【摘要】：以甲烷二氧化碳干重整为手段进行甲烷间接转化,因兼具环境保护、解决能源问题以及资源综合利用的多重意义而备受关注。近年来Ni-Co双金属甲烷二氧化碳重整催化剂凭借其可调变的电子和几何结构、双金属之间的协同作用以及金属合金的生成等优势成为研究热点。本论文以提高催化剂的活性为前提,进一步减少催化剂的积碳量。主要对比了单双金属催化剂之间的不同、不同质量分数和不同种类助剂的影响,并对催化剂的制备方法进行了改进。本论文首先应用两步水热法得到催化剂。对比Ni-Co双金属催化剂与单金属催化剂的性能发现,前者的甲烷转化率高达91.14%。通过XRD表征发现,该催化剂的优势在于各组分分散度较高且粒径较小;BET表征表明,较大的比表面积有助于原料气在催化剂上的吸附和活化;SEM扫面电镜照片显示,双金属催化剂具有更规则的立体形貌,Co的添加对催化剂的生长有一定的导向作用;通过H2-TPR表征发现,Ni-Co双金属催化剂的还原峰向低温区移动并显示出更合适的不同形态的镍的比例,因此具有更好的还原性能;通过TG-DTA表征得到,两步水热法制备的催化剂积碳情况均较为严重。添加不同含量和不同种类的助剂对催化剂进行改性,结果表明,该方法制备的双金属催化剂中助剂的最佳负载量为10%,同时发现,助剂La2O3、CeO2、CaO可以不同程度的提高催化剂的性能,是较为理想的助剂,而K2O、MgO不适合作为该催化剂的助剂。其次,本论文对催化剂的制备方法进行了改进,采用改进水热浸渍法制备催化剂。活性评价和热重的表征结果表明,两种方法制备的催化剂具有相接近的活性,但前者具有更好的抗积碳性能,其表面碳的沉积量较后者减少36%;通过BET表征发现,水热浸渍法制备的催化剂具有高达223.367m2/g的表面积,较后者高53%;最后,对不同形式的活性组分负载形式和负载量进行对比,通过BET、TPR、TG等表征证明硝酸镍比氢氧化镍更适合进行负载,而最佳的活性组分的负载量为10%。
[Abstract]:The indirect conversion of methane by dry reforming of methane with carbon dioxide has attracted much attention because of its environmental protection, energy problems and the multiple significance of comprehensive utilization of resources. In recent years, Ni-Co bimetallic methane carbon dioxide reforming catalyst has become a research hotspot due to its adjustable electronic and geometric structure, the synergy between bimetallic metals and the formation of metal alloys. In this paper, the catalyst activity is improved, and the amount of catalyst carbon is further reduced. The effects of different monobimetallic catalysts, different mass fraction and different kinds of auxiliaries were compared, and the preparation method of the catalysts was improved. In this paper, a two-step hydrothermal method was used to obtain the catalyst. Compared with Ni-Co bimetallic catalyst and monometallic catalyst, the methane conversion of the former reached 91.14%. It was found by XRD that the advantages of the catalyst were higher dispersion of each component and smaller particle size. It was found that the larger specific surface area was helpful to the adsorption of the raw gas on the catalyst and the SEM scanning electron microscopy (SEM) photos of the activation of the catalyst. The addition of bimetallic catalyst has a more regular stereomorphology and Co has a certain guiding effect on the growth of the catalyst. It was found by H2-TPR that the reduction peak of Ni-Co bimetallic catalyst shifted to the low temperature region and showed a more suitable ratio of different forms of nickel, so it had better reduction performance, and obtained by TG-DTA characterization, the reduction peak of Ni-Co bimetallic catalyst shifted to low temperature region and showed more suitable ratio of different forms of nickel. The carbon deposition of the catalysts prepared by two-step hydrothermal method is serious. The catalyst was modified by adding different contents and different kinds of additives. The results showed that the optimum loading amount of promoter in the bimetallic catalyst was 10. At the same time, it was found that the promoter La _ 2O _ 3H _ 2O _ 2CaO _ (2) could improve the performance of the catalyst in varying degrees. K _ 2O _ 2 MgO is not suitable for this catalyst. Secondly, the preparation method of the catalyst was improved, and the modified hydrothermal impregnation method was used to prepare the catalyst. The results of activity evaluation and thermogravimetric analysis showed that the catalysts prepared by the two methods had similar activity, but the former had better resistance to carbon deposition, and the amount of carbon deposited on the surface of the catalysts was 36% less than that of the latter. The catalyst prepared by hydrothermal impregnation method has a surface area of up to 53% higher than that of the latter. Finally, the loading forms and amounts of different active components are compared, and the results show that nickel nitrate is more suitable for loading than nickel hydroxide by BET-TPR-TG. The optimum active component load is 10.
【学位授予单位】：北京化工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O643.36

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