氧化亚铜可控合成及其暴露晶面对CO-PROX催化性能影响的研究
发布时间：2018-11-28 07:20
【摘要】：氢能作为新世纪一种清洁、高效的战略能源,有望代替传统化石燃料以缓解当今能源危机。氢能的理想转化装置—燃料电池的研发和利用促进了氢能的发展,其中最具应用前景的为质子交换膜燃料电池。经处理后的重整气仍含有少量的CO会导致Pt电极中毒,因此CO的含量必须降到10 ppm以下。CO优先氧化被认为是消除CO最简便有效的方法之一。铜铈体系是CO-PROX领域中最具潜力的催化剂,具有较高的经济价值和研究意义。本论文系统研究了以不同形貌的氧化亚铜为载体负载氧化铈用于CO-PROX的催化性能,初步探讨了催化剂应用于CO-PROX体系的反应机理、关键铜物种及失活原因。同时考察了催化剂界面性质以及氧化亚铜载体对催化剂催化性能的影响。采用SEM、TEM、XRD、N2吸附-脱附、H2-TPR、in situ FTIR、XPS表征手段对铜铈催化剂的物相结构与性能进行了测试分析。具体研究内容如下：1.采用液相还原法合成星状Cu20载体,通过浸渍法制备了一系列CeO2/CuxO催化剂并应用于CO-PROX体系,研究发现CeO2/CuxO催化剂具有较好的CO-PROX的催化活性。CO-PROX反应发生在铜铈的接触界面处；CO化学吸附的中心位点是界面处被还原的Cu+物种；反应过程中催化剂表面吸附的碳酸盐、碳酸氢盐物种会引起催化剂失活。2.以浸渍法在星状Cu20载体上负载不同量的Ce02制得一系列CeO2/CuxO催化剂,通过表征手段和CO-PROX反应测试考察了CeO2含量对催化剂界面性质及其催化性能影响。研究发现,催化剂中CeO2的含量不同,其界面组成和性质有较大的差异。催化剂中大颗粒的CeO2会形成更长的界面接触周边长从而具有更多的活性位。而存在的小颗粒CuO易被还原成Cu+,促进了CeO2对CO的还原。3.采用液相还原法制备出暴露不同晶面的CCe2O载体,采用沉积沉淀法制备出一系列CeO2/CuxO催化剂。研究发现,立方体、六面体、多荚状和多面体的Cu2O主要暴露(100)、(110)、(111)和(311)晶面,高晶面指数的CeO2具有较大的悬键密度和较高的表观活化能,负载CeO2后表现出良好的CO催化剂活性。载体的暴露晶面对催化剂的织构性能和催化性能有较大的影响。
[Abstract]:Hydrogen energy, as a clean and efficient strategic energy source in the new century, is expected to replace traditional fossil fuels in order to alleviate the current energy crisis. The development and utilization of hydrogen energy is promoted by the research and utilization of fuel cell, the most promising of which is proton exchange membrane fuel cell (PEMFC). A small amount of CO in the treated reforming gas can lead to Pt electrode poisoning, so the content of CO must be reduced to less than 10 ppm. The preferential oxidation of CO is considered to be one of the most convenient and effective methods to eliminate CO. The copper-cerium system is the most potential catalyst in the field of CO-PROX, which has high economic value and research significance. In this paper, the catalytic properties of cerium oxide supported on different morphologies of cuprous oxide for CO-PROX were systematically studied. The reaction mechanism, key copper species and deactivation reasons of the catalysts applied to CO-PROX system were discussed. The interfacial properties of the catalyst and the effect of cuprous oxide support on the catalytic performance of the catalyst were also investigated. The phase structure and properties of copper-cerium catalyst were characterized by SEM,TEM,XRD,N2 adsorption desorption and H 2-TPRN situ FTIR,XPS characterization. The specific research contents are as follows: 1. The stellate Cu20 carrier was synthesized by liquid phase reduction method. A series of CeO2/CuxO catalysts were prepared by impregnation method and applied to CO-PROX system. It is found that CeO2/CuxO catalyst has better catalytic activity of CO-PROX. CO-PROX reaction takes place at the contact interface of Cu and ce. The central site of CO chemisorption is the reduced Cu species at the interface, and the carbonate species adsorbed on the surface of the catalyst during the reaction will cause the deactivation of the catalyst. 2. A series of CeO2/CuxO catalysts were prepared by impregnating different amounts of Ce02 on stellate Cu20 support. The effects of CeO2 content on the interfacial properties and catalytic properties of the catalysts were investigated by means of characterization and CO-PROX reaction tests. It was found that the interfacial composition and properties of the catalyst varied with the content of CeO2. The CeO2 of the large particles in the catalyst will form longer interface contact length and thus have more active sites. However, the existing small particle CuO was easily reduced to Cu, which promoted the reduction of CO by CeO2. CCe2O carriers exposed to different crystal planes were prepared by liquid phase reduction method and a series of CeO2/CuxO catalysts were prepared by deposition precipitation method. It is found that the Cu2O of cube, hexahedron, polypods and polyhedrons are mainly exposed to (100), (110), (111) and (311) faces. The CeO2 with high crystal face index has higher hanging bond density and higher apparent activation energy. After loading CeO2, the catalyst activity of CO was good. The texture and catalytic performance of the catalyst were greatly affected by the exposed crystal of the support.
【学位授予单位】：内蒙古大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ116.2;TQ426
[Abstract]:Hydrogen energy, as a clean and efficient strategic energy source in the new century, is expected to replace traditional fossil fuels in order to alleviate the current energy crisis. The development and utilization of hydrogen energy is promoted by the research and utilization of fuel cell, the most promising of which is proton exchange membrane fuel cell (PEMFC). A small amount of CO in the treated reforming gas can lead to Pt electrode poisoning, so the content of CO must be reduced to less than 10 ppm. The preferential oxidation of CO is considered to be one of the most convenient and effective methods to eliminate CO. The copper-cerium system is the most potential catalyst in the field of CO-PROX, which has high economic value and research significance. In this paper, the catalytic properties of cerium oxide supported on different morphologies of cuprous oxide for CO-PROX were systematically studied. The reaction mechanism, key copper species and deactivation reasons of the catalysts applied to CO-PROX system were discussed. The interfacial properties of the catalyst and the effect of cuprous oxide support on the catalytic performance of the catalyst were also investigated. The phase structure and properties of copper-cerium catalyst were characterized by SEM,TEM,XRD,N2 adsorption desorption and H 2-TPRN situ FTIR,XPS characterization. The specific research contents are as follows: 1. The stellate Cu20 carrier was synthesized by liquid phase reduction method. A series of CeO2/CuxO catalysts were prepared by impregnation method and applied to CO-PROX system. It is found that CeO2/CuxO catalyst has better catalytic activity of CO-PROX. CO-PROX reaction takes place at the contact interface of Cu and ce. The central site of CO chemisorption is the reduced Cu species at the interface, and the carbonate species adsorbed on the surface of the catalyst during the reaction will cause the deactivation of the catalyst. 2. A series of CeO2/CuxO catalysts were prepared by impregnating different amounts of Ce02 on stellate Cu20 support. The effects of CeO2 content on the interfacial properties and catalytic properties of the catalysts were investigated by means of characterization and CO-PROX reaction tests. It was found that the interfacial composition and properties of the catalyst varied with the content of CeO2. The CeO2 of the large particles in the catalyst will form longer interface contact length and thus have more active sites. However, the existing small particle CuO was easily reduced to Cu, which promoted the reduction of CO by CeO2. CCe2O carriers exposed to different crystal planes were prepared by liquid phase reduction method and a series of CeO2/CuxO catalysts were prepared by deposition precipitation method. It is found that the Cu2O of cube, hexahedron, polypods and polyhedrons are mainly exposed to (100), (110), (111) and (311) faces. The CeO2 with high crystal face index has higher hanging bond density and higher apparent activation energy. After loading CeO2, the catalyst activity of CO was good. The texture and catalytic performance of the catalyst were greatly affected by the exposed crystal of the support.
【学位授予单位】：内蒙古大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ116.2;TQ426
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