介孔金属氧化物的制备及其在CO催化氧化中的应用

发布时间：2018-01-12 04:35

本文关键词：介孔金属氧化物的制备及其在CO催化氧化中的应用　出处：《大连工业大学》2015年硕士论文　论文类型：学位论文

【摘要】：CO氧化与选择氧化涉及能源、环境、健康与安全等多个领域,具有重要的实际应用与基础研究价值。在诸多消除CO的方法中,催化氧化法是公认为最有效的途径之一,而催化剂是实现该过程的关键。尽管贵金属催化剂与其他非贵金属催化剂相比,有很好的催化活性,但是高昂的价格,低的抗卤素性限制了其大规模的应用。体相贱金属及其复合金属氧化物对CO氧化显示出了良好的催化性能,但较低的比表面积和不发达的孔道结构,使得这类催化剂催化活性受到影响。因此研究具有高比表面积和发达孔道结构的过渡金属氧化物催化剂有着重要的理论价值和实用价值。本文详细研究了不同孔道二氧化铈及其复合金属氧化物制备,它们的孔结构和物化性质通过XRD、BET、TEM、Raman、FTIR、XPS、H2-TPR等技术研究,评价了其CO氧化催化活性。取得的主要结果如下:1.制备了介孔、微孔和纳米三种不同孔道结构的CeO2纳米材料,介孔CeO2(mesoCeO2)和微孔CeO2(micro-CeO2)分别以介孔硅KIT-6和高硅ZSM-5(Si/Al=344.1)作为硬模板通过硬模板法制备。纳米CeO2(nano-CeO2)通过沉淀法制备。负载一定量的Pd在所制备的meso-CeO2、micro-CeO2和nano-CeO2上,评价了其对CO的催化活性。Pd/mesoCeO2展现出了优异的催化性能,完全转化温度仅为50oC。按照分析结果,Pd/meso-CeO2有一个好的催化性能不仅与meso-CeO2大的比表面积、小的晶粒尺寸和三维介孔结构有关,而且与催化剂表面活性氧物种有关。2.采用介孔硅KIT-6作为硬模板,通过纳米复制法制备了具有三维介孔的过渡金属(Co、Cu、Fe)掺杂CeO2。所有样品均具有很高的比表面积(120m2g-1)和有序的介孔结构。研究表明,Co、Cu和Fe物种的掺入能有效的增强CeO2表面的化学吸附氧浓度。与Co和Fe物种相比,Cu物种掺入有一个明显的增加。对所有的样品评估了CO催化活性,Cu掺杂的CeO2催化剂拥有最好的催化活性,其对CO氧化的完全转化温度仅为55 oC。3.通过用不同的水热合成温度制备的KIT-6作为硬模板,制备出了不同孔径的Cu掺杂CeO2。当KIT-6-50(水热合成温度为50oC)和KIT-6-100(水热合成温度为100oC)用作硬模板时Uncoupled结构形成,当KIT-6-130(水热合成温度为130oC)用作硬模板时Coupled结构形成。与Coupled结构的Cu掺杂CeO2相比较,Uncoupled结构的Cu掺杂CeO2拥有更大的比表面积和更开放的孔道结构。评价了三种催化剂对CO催化活性,用KIT-6-50作为硬模板制备的Cu掺杂CeO2催化剂有很好的CO催化活性,完全转化温度仅为53oC。结果表明,大的比表面积和更为开放的孔道结构有助于CO的催化氧化。
[Abstract]:Co oxidation and selective oxidation are related to many fields, such as energy, environment, health and safety, which have important practical application and basic research value. Catalytic oxidation is recognized as one of the most effective methods, and catalyst is the key to achieve this process. Although noble metal catalysts have good catalytic activity compared with other non-noble metal catalysts, but the high price. Low halogen resistance limits its large-scale application. Bulk base metals and their composite metal oxides exhibit good catalytic performance for CO oxidation, but lower specific surface area and underdeveloped pore structure. Therefore, the study of transition metal oxide catalysts with high specific surface area and developed pore structure has important theoretical and practical value. Preparation of cerium oxide and its composite metal oxide. Their pore structure and physicochemical properties were studied by means of the techniques such as XRDX BETTEMN Ramanian FT-IR, XPSH2-TPR and so on. The catalytic activity of CO oxidation was evaluated. The main results were as follows: 1. The mesoporous, microporous and nano-sized CeO2 nanomaterials with different pore structures were prepared. Mesoporous CEO _ 2 (mesoCeO _ 2) and microporous CEO _ (2) micro-CeO _ 2) were characterized by mesoporous KIT-6 and high silicon ZSM-5Si / Al / Al _ (344.1). As a hard template prepared by hard template nano-CeO2nano-CeO2) was prepared by precipitation method. A certain amount of PD was loaded on the prepared meso-CeO2. On micro-CeO2 and nano-CeO2, their catalytic activity for CO was evaluated. PD / mesoCeO2 showed excellent catalytic performance. The total conversion temperature is only 50 OC. According to the analysis results, PD / meso-CeO2 has a good catalytic performance not only with the large specific surface area of meso-CeO2. The small grain size is related to the three-dimensional mesoporous structure and the active oxygen species on the catalyst surface. 2. Mesoporous silicon KIT-6 is used as hard template. The transition metal (Cu) with three dimensional mesoporous structure was prepared by nano-replication method. All the samples have high specific surface area of 120m2g-1) and ordered mesoporous structure. The incorporation of Cu and Fe species can effectively enhance the chemisorbed oxygen concentration on the surface of CeO2, compared with Co and Fe species. There was a significant increase in the addition of Cu species. The CO catalytic activity of Cu-doped CeO2 catalyst was evaluated for all samples with the best catalytic activity. The total conversion temperature for CO oxidation is only 55oC.3.The KIT-6 prepared by hydrothermal synthesis at different temperatures is used as hard template. Cu-doped CEO _ 2 with different pore sizes was prepared. When KIT-6-50 (hydrothermal synthesis temperature is 50oC) and KIT-6-100 (hydrothermal synthesis temperature is 100oC). The Uncoupled structure is formed when used as a hard template. When KIT-6-130 (hydrothermal synthesis temperature is 130 OC) as hard template, Coupled structure is formed, which is compared with Cu-doped CeO2 in Coupled structure. Cu-doped CeO2 with Uncoupled structure has larger specific surface area and more open pore structure. The catalytic activity of three catalysts for CO was evaluated. Cu-doped CeO2 catalyst prepared by using KIT-6-50 as hard template has good CO catalytic activity, and the complete conversion temperature is only 53oC. the results show that Cu-doped CeO2 catalyst has good CO catalytic activity. Larger specific surface area and more open pore structure contribute to the catalytic oxidation of CO.
【学位授予单位】：大连工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：O643.36;TB383.4

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