【作者】 章从根；

【导师】 郭锡坤；

【作者基本信息】 汕头大学 ， 工业催化， 2011， 硕士

【摘要】 自工业革命以来,化石能源在给人类带来前所未有的工业发展和物质财富的同时,也给人类造成了难以承受的气候变化和环境压力。从目前来看,机动车尾气排放问题日益突出,机动车排放的大气污染物对城市空气污染的分担率越来越高,已成为继城市煤烟污染之后的又一主要污染源。机动车尾气净化催化剂是控制机动车气排放减少污染的最有效手段,欧美国家机动车尾气净化催化剂大多采用Pt、Pd和Rh等贵金属做为催化剂的活性组分,已经实际应用于机动车尾气的治理,但其存在贵金属资源短缺和价格昂贵等问题,难以全面推广。因此,开发一种廉价、高效的非贵金属催化剂来替代贵金属催化剂有着非常重要的意义。在此研究背景的条件下,本文选用价格相对低廉且容易获取的Cu作为催化剂的活性组分,采用等体积浸渍法制备了以Ce-Zr-O、Ce-Zr-Bi-O及Mo/CeO₂-ZrO₂复合氧化物为载体的负载型非贵金属催化剂,然后在模拟机动车尾气主要组成的气氛下,通过活性测试分析催化剂性能,并结合XRD和SEM等表征手段考察各个条件对催化剂结构的影响。此外,对催化剂的结构与性能也进行了一定的关联。主要研究内容和实验结果如下:1.以NH₃·H₂O-（NH₄）2CO₃混合溶液作为沉淀剂,采用共沉淀法制备了Ce-Zr-Bi-O（CZB）系列复合氧化物,并以该复合氧化物为载体,研制负载非贵金属Cu的Cu/CZB催化剂。通过调节Ce/Zr比例,改变Bi的含量以及载体的制备方法,得出当CZB载体采用共沉淀法制备、Ce:Zr:Bi的摩尔比为0.65:0.35:0.06、Cu负载量为5%时,所制得的Cu/Ce0.65Zr0.35Bi0.06O₂具有较好的催化活性,能使NO和CO的起燃温度较低,分别为238和低于100 ,并且在175时CO达到完全转化,325时NO达到完全转化。Bi的加入能够形成具有单一稳定立方相结构的Ce-Zr-Bi固溶体,晶粒达到纳米级,同时不出现CuO在催化剂表面聚集的现象,从而提高了催化剂的性能。2.研究了Cu/Mo/CeO₂-ZrO₂复合金属氧化物催化剂性能。当Ce:Zr的摩尔比为0.65:0.35, Mo负载量为6%,Cu负载量为5%时,制得的Cu/Mo/CeO₂-ZrO₂催化剂具有较佳的催化性能和较宽的工作窗口,当空燃比为1.4时,能使CO、C₃H₆和NO的起燃温度T50分别为103、247和242 ,完全转化温度T90分别为189、429和315。XRD和SEM的测试结果表明:助剂Mo的添加可使Cu/Mo/CeO₂-ZrO₂催化剂的颗粒更加细化,且能够形成单一稳定的立方相固溶体结构,催化剂经高温老化后,颗粒分散均匀性仍较好。更多还原

【Abstract】 Since the industrial revolution, fossil energy bring unprecedented in the industrial development and material wealth, but also give human caused unbearable climate change and environmental pressures. In view of the existing conditions, motor vehicle exhaust emission problems have become increasingly prominent, in the urban air pollution, the pollution from exhaust emission is more and more serious, which has become the major source of pollution after soot pollution. Motor vehicle exhaust gas cleaning catalyst is the most effective means to control emissions and reduce pollution. The European and American catalysts are mostly used Pt, Pd, Rh and other precious metals as the active component, which has a actual application already. However, there are many existing problems to comprehensive promotion, such as shortage of resources and expensive precious metals. Therefore, it is important to develop a cheap and efficient non-noble metal catalysts to instead of noble metal catalyst.Under this background conditions, in this paper, we used Cu as a catalyst active component, which is relatively cheap and easy to acquire. The catalysts was prepared with the Ce-Zr-O, Ce-Zr-Bi-O and Mo/CeO₂-ZrO₂ composite oxides as the carrier by incipient-wetness impregnation method, their performance were investigated in a condition of a simulated motor vehicle exhaust, the catalysts structure were characterized with XRD and SEM means to study. In addition, the structure and properties of catalyst were linked in some extent. The main research contents and experimental results are as follows:、1. We used NH₃·H₂O-（NH₄）2CO₃ as the precipitator, the series of Ce-Zr-Bi-O（CZB） composite oxides were prepared by the co-precipitation method, and Cu/CZB catalysts was prepared with them as the carrier. The effects of different Ce, Zr and Bi molar ratio and preparation methods on the CZB composite oxides were investigated. The results showed: when CZB carrier was used co-precipitation method, the Cu/Ce0.65Zr0.35Bi0.06O₂ catalyst with Ce:Zr:Bi molar ratio of 0.65:0.35:0.06, and the content of Cu of 5% showed the better catalytic performance. The light-off temperatures for NO and CO were 238 and lower than 100 respectively, CO could be completely converted above 175 , and NO could be completely converted above 325 . Bi was added to form a single and stable cubic structure of the Ce-Zr-Bi solid solution, crystal size achieved a nanometer scale level, while highly dispersed CuO particles was formed on the surface of catalyst, so the performance of the catalyst has improved.2. Catalytic properties of Cu/Mo/CeO₂-ZrO₂ composite oxide catalyst was studied. The Cu/Mo/CeO₂-ZrO₂ catalyst with Ce:Zr molar ratio of 0.65:0.35,the content of Mo of 6% and the content of Cu of 5% showed high catalytic performance. When the air/fuel ratio was 1.4, the light-off temperatures for CO, C₃H₆ and NO were 103 , 247 and 242 respectively, CO, C₃H₆ and NO could be completely converted above 189 , 429 and 315 . The results of XRD and SEM characterization showed, Mo was added to make the catalyst particles be smaller and form a single and stable cubic structure of the solid solution. After aging at high temperature, the catalyst particles also have good dispersion and regular shape.更多还原