还原石墨烯促进的铜—铈催化剂中协同效应对CO优先氧化性能的研究

发布时间：2018-03-17 09:13

本文选题：还原石墨烯　切入点：铜-铈催化剂　出处：《内蒙古大学》2017年硕士论文　论文类型：学位论文

【摘要】：现代工业技术的发展为人类提供了前所未有的高质量生活,但严峻的环境污染和频现的能源危机为此蒙上了挥之不去的阴影。氢气作为一种可再生的清洁能源,以质子交换膜电池(PEMFCs)形式使用日益受到青睐。然而,工业氢气中残留的少量CO(约1%)对燃料电池的电极有致命的毒害作用,需要经过纯化将其降低到10ppm以下。富氢气中一氧化碳优先氧化(CO-PROX)被认为是去除氢气中CO最有效、最直接的方法。传统的铜-铈催化剂虽然在高温端具有较好的催化活性和较宽的完全转化窗口,但是由于其具有较小的比表面积和较低的氧空位浓度而在低温端展现出一个较差的CO氧化性能。二维片状结构的石墨烯由于具有高电荷载体迁移率、高热导率、较大的比表面积以及较好的还原性能等优点。因此,我们希望采用在铜铈氧化物中引入石墨烯的策略,获得具有较好低温端催化性能的纳米复合材料催化剂。具体研究内容如下:1、采用水热法合成一系列铜铈摩尔比不同的具有片-片结构的RGO/CuxO-CeO2、RGO/CuxO以及RGO/CeO2纳米复合材料催化剂。研究发现,由于石墨烯的加入,在RGO/CuxO-CeO2纳米复合材料中拥有较多的被碳还原的铜物种以及较高浓度的氧空位。球形的铜纳米颗粒在催化剂中可作为空间隔层,阻止还原石墨烯的团聚。RGO/CuxO-CeO2-B催化剂具有较好的抗H20和CO2性能。2、分别采用原位沉淀法和水热法制备具有三维框架结构的RGO/MWCNTs/CuxO-CeO2纳米复合材料催化剂。研究发现,RGO和MWCNTs的加入提高了CuxO和CeO2的分散以及还原性能。相比只加入还原石墨烯的催化剂,RGO和MWCNTs的加入提高了催化剂中的氧空位浓度以及低温端的CO氧化性能。铜物种过度的还原对催化剂的催化性能有一个负面的影响。3、采用水热法合成出一系列具有不同铜铈摩尔比的、CeO2为棒状结构的RGO/CuxO-CeO2复合材料催化剂。。研发现,铜铈摩尔比为3:7时,,维棒状结构的CeO2有效地阻止了石墨烯的团聚。因此,RGO/CuxO-CeO2-A催化剂具有最大的比表面积和较好的低温端催化性能。
[Abstract]:The development of modern industrial technology has provided mankind with an unprecedented high quality of life, but the severe environmental pollution and frequent energy crisis have cast a lingering shadow over it. The use of PEMFCsin the form of proton exchange membrane cells (PEMFCs) is becoming more and more popular. However, a small amount of CO (about 1) remaining in industrial hydrogen has a deadly toxic effect on the electrode of the fuel cell. It needs to be purified and reduced below 10ppm. CO-PROX is considered to be the most effective way to remove CO from hydrogen. The most direct method. Although the traditional copper-cerium catalyst has better catalytic activity at the end of high temperature and wider complete transformation window, However, due to its small specific surface area and low oxygen vacancy concentration, it exhibits a poor CO oxidation performance at the low temperature end, and graphene with two-dimensional flake structure is characterized by high charge carrier mobility and high thermal conductivity. Therefore, we would like to adopt the strategy of introducing graphene into cerium oxide. Nanocomposite catalysts with good catalytic performance at low temperature were obtained. The main contents of this study are as follows: 1. A series of nanocomposites with different copper-cerium molar ratios, RGO- / CuxO-CeO2O and RGO/CeO2 nanocomposites with different molar ratios of copper and cerium were synthesized by hydrothermal method. Chemotherapeutic agents. The study found, Because of the addition of graphene, there are more carbon reduced copper species and higher oxygen vacancies in RGO/CuxO-CeO2 nanocomposites. The spherical copper nanoparticles can be used as spacer in the catalyst. The agglomeration of reductive graphene. RGO- / CuxO-CeO2-B catalyst has better resistance to H20 and CO2. In situ precipitation method and hydrothermal method have been used to prepare RGO/MWCNTs/CuxO-CeO2 nanocomposite catalysts with three-dimensional frame structure respectively. The addition of RGO and MWCNTs has been found. The dispersion and reduction properties of CuxO and CeO2 were improved, and the oxygen vacancy concentration in catalyst and CO oxidation at low temperature were increased compared with those of reductive graphene catalyst (RGo and MWCNTs). Excessive reduction of copper species was observed. A series of RGO/CuxO-CeO2 composite catalysts with different copper-cerium molar ratio were synthesized by hydrothermal method. When the copper-cerium molar ratio is 3: 7, the CeO2 with the dimensional rod structure can effectively prevent the agglomeration of graphene. Therefore, the RGO- / CuxO-CeO2-A catalyst has the largest specific surface area and better low-temperature terminal catalytic performance.
【学位授予单位】：内蒙古大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O643.36;TM911.4

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