选择性催化还原催化剂氧化脱除烟气中单质汞  

Oxidation and capture of elemental mercury over SCR catalyst in simulated flue gas

作　　者：陶莉[1] 张旭楠[2] 李彩亭[2] 车垚[1,3] 赵令葵 周艳明[1,3] 

机构地区：[1]国网湖南省电力公司电力科学研究院,长沙410007 [2]湖南大学环境科学与工程学院,长沙410082 [3]湖南湘电试验研究院有限公司,长沙410007

出　　处：《环境工程学报》2015年第6期2925-2932,共8页Chinese Journal of Environmental Engineering

基　　金：国家自然科学基金资助项目(51278177);国家高技术研究发展计划(863)项目(2011AA060803);国网湖南省电力公司电力科学研究院和湖南大学合作项目

摘　　要：以运用超声辅助浸渍法制备的V2O5-WO3/Ti O2系列催化剂样品作为研究参考,在150~400℃,分别考察了某燃煤电厂新鲜的及已运行长达26 000 h的商用SCR脱硝催化剂对模拟烟气中单质汞(Hg0)的氧化性能,并利用SEM、BET、XRD等手段对样品的理化性质进行了表征。结果表明,电厂商用SCR催化剂对于燃煤烟气中的Hg0具有一定的催化氧化作用,但在250℃最佳反应温度时,最大汞氧化效率在50%以下,相同实验条件下,自制的1%V2O5-9%WO3/Ti O2(V1W9Ti)能够获得68.18%的最大汞氧化效率;通过考察NO、NH3、SO2和水蒸气对汞的氧化的影响发现,在低浓度NO以及5%O2存在时,NO能够促进汞的氧化;SO2对汞的氧化有明显的抑制作用,而且其毒害作用具有一定的不可逆性;NH3在催化剂表面能够与Hg0发生竞争吸附,从而抑制了汞的氧化;水蒸气的存在容易导致催化剂的失活。此外,对催化剂氧化Hg0的机理进行了探讨。In the present study,elemental mercury( Hg0) oxidation activities of commercially used selective catalytic reduction( SCR) de-NOxcatalysts including both fresh and 26 000 h operation employed ones from a coal-fired power plant were investigated at 100 ~ 400℃ in simulated flue gas. And Ti O2-supported V2O5-WO3 catalysts prepared by an ultrasound-assisted impregnation method were used as the reference. Brunauer-EmmettTeller( BET),scanning electron microscope( SEM) and X-ray diffractometer( XRD) analyses were conducted to characterize the samples. The results showed that the commercially available SCR catalysts achieved less than 50%Hg0oxidation efficiency at the optimal 250℃,while the self-made 1% V2O5-9% WO3/ Ti O2( V1W9Ti) catalyst performed the best activity with an approximately 68. 18% efficiency under the same condition. Moreover,the effects of NO,SO2,NH3 and water vapor on the Hg0 oxidation were investigated. It was found that NO had a certain promoting effect on Hg0 oxidation when in its low concentration or in the presence of O2. SO2 observably inhibited the oxidation of Hg0,and its poisonous impact was irreversible to some extent. NH3 competed with the Hg0 on the surface of catalysts,resulting in a inhibiting effect on the oxidation reaction. Water vapor could lead to deactivation of the catalysts. In addition,the main reaction mechanism of catalytic oxidation of Hg0 was discussed.

关 键 词：单质汞 选择性催化还原催化剂 V2O5-WO3/TIO2 燃煤烟气 

分 类 号：X701[环境科学与工程—环境工程]