本文主要研究内容
作者盛丽萍,马朝霞,陈思园,楼锦泽,李成业,李松达,张泽,王勇,杨杭生(2019)在《无氧条件下Pd/Ce O2催化剂表面NH3还原NO过程中N2O形成机理研究(英文)》一文中研究指出:氮氧化物(NOx,主要包括NO和NO2)是主要的大气污染物之一,造成酸雨,光化学烟雾和臭氧层破坏等环境问题,甚至直接危害人体健康.化石燃料燃烧和汽车尾气排放是NOx的主要来源,严格控制火力发电厂,大型锅炉,汽车尾气等污染源中NOx的排放刻不容缓.以NH3为还原剂选择性催化还原NOx(NH3-SCR)是目前公认的最有效的NOx脱除技术,然而在催化NOx还原为N2的过程中往往伴随着副产物N2O的生成,降低了催化剂的选择性,造成温室气体效应和破坏臭氧层等环境问题.因此充分理解NH3-SCR过程中N2O的形成机理对于抑制N2O的产生、提高催化剂的选择性十分重要.本文将高度分散的Pd纳米团簇负载在Ce O2纳米棒上制成Pd/Ce O2催化剂,结合NH3-TPD, NO-TPD和原位傅里叶转换红外光谱等表征手段研究了无氧条件下该催化剂上利用NH3催化还原NO过程中N2O的产生路径.结果表明, N2O的形成途径与反应温度和反应气体的浓度相关.当反应气体中NH3含量大于化学计量比时,在反应温度低于200°C时,由NH3活化产生的吸附态H·自由基与催化剂表面吸附的NO反应先生成中间产物HON,两个HON分子进一步反应生成N2O;过量的吸附态的H·自由基也可以与HON反应生成N2,所以低温下(<200°C)随着反应气氛中NH3的增加,解离生成的H·也随之增加,促进反应向着生成N2的方向进行,从而抑制了N2O的产生.随着反应温度增加, NH3解离产生的H·被CeO2表面的O捕获形成羟基,中间产物HON的生成被切断,从而阻断了N2O的生成.同时由于体系中含有大量的NH3,吸附态的NO会优先与活化态的NH3物种反应生成N2,阻碍了NO解离生成N2O这一过程的发生,因此NH3过量情况下在高温下观察不到N2O的产生,可获得100%的N2选择性.但是当反应气体中的NH3含量不足时,即体系中含有过量的NO,当反应温度高于250°C, NO可在催化剂表面解离生成吸附态的N·自由基和O·自由基, N·自由基可进一步与吸附态的NO反应生成N2O, NO的解离是N2O生成的速控步,还原性吸附物种对O·自由基的捕捉将有利于N2O的生成.当反应温度介于200–250°C, NH3解离产生的H·自由基既可以与NO结合生成HON中间产物,又能被CeO2表面的O捕获形成羟基,两个反应之间存在竞争,此时N2O产生与反应气体浓度之间的关系不再呈单调变化.
Abstract
dan yang hua wu (NOx,zhu yao bao gua NOhe NO2)shi zhu yao de da qi wu ran wu zhi yi ,zao cheng suan yu ,guang hua xue yan wu he chou yang ceng po huai deng huan jing wen ti ,shen zhi zhi jie wei hai ren ti jian kang .hua dan ran liao ran shao he qi che wei qi pai fang shi NOxde zhu yao lai yuan ,yan ge kong zhi huo li fa dian an ,da xing guo lu ,qi che wei qi deng wu ran yuan zhong NOxde pai fang ke bu rong huan .yi NH3wei hai yuan ji shua ze xing cui hua hai yuan NOx(NH3-SCR)shi mu qian gong ren de zui you xiao de NOxtuo chu ji shu ,ran er zai cui hua NOxhai yuan wei N2de guo cheng zhong wang wang ban sui zhao fu chan wu N2Ode sheng cheng ,jiang di le cui hua ji de shua ze xing ,zao cheng wen shi qi ti xiao ying he po huai chou yang ceng deng huan jing wen ti .yin ci chong fen li jie NH3-SCRguo cheng zhong N2Ode xing cheng ji li dui yu yi zhi N2Ode chan sheng 、di gao cui hua ji de shua ze xing shi fen chong yao .ben wen jiang gao du fen san de Pdna mi tuan cu fu zai zai Ce O2na mi bang shang zhi cheng Pd/Ce O2cui hua ji ,jie ge NH3-TPD, NO-TPDhe yuan wei fu li xie zhuai huan gong wai guang pu deng biao zheng shou duan yan jiu le mo yang tiao jian xia gai cui hua ji shang li yong NH3cui hua hai yuan NOguo cheng zhong N2Ode chan sheng lu jing .jie guo biao ming , N2Ode xing cheng tu jing yu fan ying wen du he fan ying qi ti de nong du xiang guan .dang fan ying qi ti zhong NH3han liang da yu hua xue ji liang bi shi ,zai fan ying wen du di yu 200°Cshi ,you NH3huo hua chan sheng de xi fu tai H·zi you ji yu cui hua ji biao mian xi fu de NOfan ying xian sheng cheng zhong jian chan wu HON,liang ge HONfen zi jin yi bu fan ying sheng cheng N2O;guo liang de xi fu tai de H·zi you ji ye ke yi yu HONfan ying sheng cheng N2,suo yi di wen xia (<200°C)sui zhao fan ying qi fen zhong NH3de zeng jia ,jie li sheng cheng de H·ye sui zhi zeng jia ,cu jin fan ying xiang zhao sheng cheng N2de fang xiang jin hang ,cong er yi zhi le N2Ode chan sheng .sui zhao fan ying wen du zeng jia , NH3jie li chan sheng de H·bei CeO2biao mian de Obu huo xing cheng qiang ji ,zhong jian chan wu HONde sheng cheng bei qie duan ,cong er zu duan le N2Ode sheng cheng .tong shi you yu ti ji zhong han you da liang de NH3,xi fu tai de NOhui you xian yu huo hua tai de NH3wu chong fan ying sheng cheng N2,zu ai le NOjie li sheng cheng N2Ozhe yi guo cheng de fa sheng ,yin ci NH3guo liang qing kuang xia zai gao wen xia guan cha bu dao N2Ode chan sheng ,ke huo de 100%de N2shua ze xing .dan shi dang fan ying qi ti zhong de NH3han liang bu zu shi ,ji ti ji zhong han you guo liang de NO,dang fan ying wen du gao yu 250°C, NOke zai cui hua ji biao mian jie li sheng cheng xi fu tai de N·zi you ji he O·zi you ji , N·zi you ji ke jin yi bu yu xi fu tai de NOfan ying sheng cheng N2O, NOde jie li shi N2Osheng cheng de su kong bu ,hai yuan xing xi fu wu chong dui O·zi you ji de bu zhuo jiang you li yu N2Ode sheng cheng .dang fan ying wen du jie yu 200–250°C, NH3jie li chan sheng de H·zi you ji ji ke yi yu NOjie ge sheng cheng HONzhong jian chan wu ,you neng bei CeO2biao mian de Obu huo xing cheng qiang ji ,liang ge fan ying zhi jian cun zai jing zheng ,ci shi N2Ochan sheng yu fan ying qi ti nong du zhi jian de guan ji bu zai cheng chan diao bian hua .
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论文作者分别是来自催化学报的盛丽萍,马朝霞,陈思园,楼锦泽,李成业,李松达,张泽,王勇,杨杭生,发表于刊物催化学报2019年07期论文,是一篇关于形成论文,还原论文,催化剂论文,原位红外论文,机理研究论文,催化学报2019年07期论文的文章。本文可供学术参考使用,各位学者可以免费参考阅读下载,文章观点不代表本站观点,资料来自催化学报2019年07期论文网站,若本站收录的文献无意侵犯了您的著作版权,请联系我们删除。