【作者】 张桂红；

【导师】 陶长元；

【作者基本信息】 重庆大学 ， 化学， 2010， 硕士

【摘要】 我国是一个煤炭大国,煤炭占我国能源结构的绝大部分,随着我国工业化的发展,煤炭燃烧所排放出来的氮氧化物越来越多,已经成为我国大气污染的一个主要组成部分。在世界上众多的脱硝技术中,选择性催化还原(SCR)技术是目前最为重要的烟气脱硝技术,而在SCR催化技术中催化剂成本所占比例比较大为40%-60%,国内外学者广泛致力于高效催化剂的研发。目前国内SCR催化剂研发存在以下两个方面的问题:(1)西方发达国家的研究比较成熟,而我国尚无自主研发的商用SCR催化剂;(2)大部分商用SCR催化剂制备工艺均为混捏法:即将所有成分的粉末混合到一起加入粘结剂、助挤剂等揉捏焙烧成型,这种方法TiO2重量占催化剂总重量的80%左右,存在成本高活性组分利用不充分的问题。本论文采用溶胶法制备催化剂载体Al2O3和TiO2,并通过常温浸渍法和超声波辅助浸渍法负载载体,通过加热浸渍法负载活性组分WO3和V2O5,制备了V2O5-WO3/TiO2,V2O5-WO3/TiO2/Al2O3(常温浸渍),V2O5-WO3/TiO2/Al2O3(超声波辅助浸渍)三个系列的催化剂,探讨了催化剂的前处理,载体负载,活性组分和助剂负载等制备工艺,并且在载体制备中创新性的引入超声波。结合SEM(扫描电镜),BET(比表面分析),XRD(X射线衍射)的表征结果,分析了催化剂制备中各因素的影响。结果发现:(1)前处理用15%的H2O2比用HNO3效果好,堇青石蜂窝陶瓷的比表面积有显著增加;(2)在载体负载工艺中:常温浸渍和超声辅助浸渍负载工艺优于水浴加热浸渍负载工艺;超声负载工艺大大缩短工艺时间;TiO2/Al2O3复合氧化物载体催化剂活性优于TiO2单氧化物载体催化剂活性;(3)在负载活性组分和助剂工艺中发现共浸和分浸对催化活性影响不大。在脱硝催化剂活性评价成套装置上进行了活性测定,研究了各种组分(V2O5,WO3,TiO2)和具体的催化反应条件(温度,O2浓度,氨氮比,空速)对其活性的影响。结果表明:(1)V2O5-WO3/TiO2催化剂中TiO2最佳负载量在16%~28%之间,WO3最佳负载量在4%~13%之间,V2O5负载量最佳值在1%~3%之间。(2)脱硝率随进口NO值的增加,空速的减少而增大,脱硝率在氨氮比为1.0-1.2,O2浓度为2.0-2.5%(NO=500ppm)比较高。在10000 h-1的空速下,催化剂脱硝率在350℃-450℃最高可达76%。更多还原

【Abstract】 China has lots of coal, coal accounted for the vast majority of China’s energy structure. With the development of China’s industrialization, more and more nitrogen oxides discharged into air, which come from coal combustion in the Coal-fired power plant and has become a major component of air pollution. There are many denitration technology in the world, selective catalytic reduction (SCR) NOx is the most important technology of flue gas denitrification, both at home and abroad dedicated to high-performance catalyst for a wide range of research and development, studies conducted in western countries more mature, has successfully achieved a commercial , while there is no independent research and development of China’s commercial SCR catalyst. Furthermore, most of the commercial SCR catalyst preparation are kneading method: all the ingredients were mixed together with help squeeze agent and binder, kneaded and baked to the finished. In this method, the weight of TiO2 accounted for 80% of the total catalyst weight, there are high costs and insufficient use of highly active component.In this paper, Al2O3 and TiO2 sol were prepared by the sol-gel method, the TiO2 /CC carrier and TiO2-Al2O3/CC were prepared with ultrasonic impregnation and static impregnation, respectively, and through the impregnation load active components WO3 and V2O5, three kinds catalysts of V2O5-WO3/TiO2, V2O5-WO3/TiO2/Al2O3 (ultrasonic impregnation), V2O5-WO3/TiO2/Al2O3(static impregantion) were prepared. Discussed the preparation process of catalyst pretreatment, carrier, other active components and additives load method. The preparation of the carrier introducted ultrasound innovativly. Combined the results of SEM, BET and XRD, the influenced factors of the catalyst preparation were analysed. The results showed that: (1) Pre-treatment with 15% H2O2 significantly increased surface area compared with HNO3; (2) In the supports load process: room temperature impregnation and ultrasonic assisted impregnation process were better than water bath heating impregnation process; ultrasound technology greatly reduced the load processing time; the activity with TiO2/Al2O3 double oxide carrier catalysts were better than catalyst of TiO2 single oxides catalysts; (3) In the active components and additives loading process, a total impregnation or step impregnation were found little effect on the catalytic activity.Catalyst activity in complete set of device evaluation activity assay was carried out to study the effect of its activity under various substances(V2O5, WO3, TiO2) and catalytic reaction conditions (temperature, O2 concentration, ammonia nitrogen ratio and space velocity). The results showed that: (1) the best loading content of TiO2 ranged within16% to 28%, optimal loading of WO3 ranged within 4% to 13%, the best loading of V2O5 ranged within 1% to 3%; (2) NO denitrification rate increases with the increase value of imports and the decrease of space velocity, denitrification rates in the conditions with ammonia ratio of 1.0-1.2 and O2 concentration of 2.0-2.5% (NO = 500ppm) were relatively higher. At 10000h-1 space velocity, catalyst denitration rate up to 76% of 350℃- 450℃.更多还原