Experimental study of NO reduction by ethane over iron
-
摘要: 温度300~1 100 ℃时,由程序控温电加热水平陶瓷管反应器在N2气氛和模拟气氛下,对乙烷在金属铁表面还原NO的特性进行了实验研究。结果表明,乙烷在金属铁表面能够高效地还原NO。在N2气氛中,温度高于900 ℃时,乙烷在金属铁表面的脱硝效率超过95%。在模拟烟气条件下,当温度超过900 ℃,且过量空气系数小于1.0时,乙烷在金属铁表面还原NO的效率能够达到90%以上。相同条件下,乙烷在金属铁表面脱硝效率高于甲烷的脱硝效率。SO2对乙烷在金属铁表面还原NO的效率影响可以忽略。对反应后的铁样品的组分进行了XRD表征,在此基础上对反应机理进行了分析。结果表明,在模拟烟气条件下NO的还原通过乙烷的再燃脱硝和金属铁直接还原两个机理完成。金属铁直接还原NO时生成的氧化铁则被乙烷还原为金属铁,从而使得金属铁能够持续对NO进行直接还原。乙烷再燃还原NO的中间产物HCN被氧化铁氧化为N2,同时氧化铁也被HCN还原为金属铁。这一过程增强了NO的持续还原反应,同时避免了在燃尽时HCN二次氧化重新生成NO,从而保证了较高的NO还原效率。Abstract: NO reduction by ethane over iron was experimentally investigated in a one-dimensional temperature- programmed ceramic tubular reactor at 300~1 100 ℃ in nitrogen and simulated flue gas atmospheres. The results show that ethane can effectively reduce NO to N2 over the surface of metallic iron. In N2 atmosphere, more than 95% of NO is reduced by ethane over metallic iron when the temperature is higher than 900 ℃. In simulated flue gas atmosphere, more than 90% of NO is reduced by ethane over metallic iron above 900 ℃ when the excess air ratio is lower than 1.0. Under the same conditions, NO reduction by ethane over iron is higher than that by methane. The effect of SO2 in simulated flue gas on NO reduction can be ignored. The iron samples were characterized with respect to their composition by XRD after reaction, and on this basis the reaction mechanism was further analyzed. There are two mechanisms for NO reduction, i.e., the reburning of ethane and direct reduction by iron. The iron is oxidized to iron oxides after reducing NO and then ethane reduces the iron oxides to metallic iron, leading to the sustainable and durable reduction of NO by iron. Meanwhile, NO is reduced by ethane through reburning to from the intermediate HCN that could be oxidized to N2 by iron oxide, furthermore the iron oxides are reduced to iron simultaneously. This process enhances the NO reduction and prevents the additional NO formation due to the oxidization of HCN during burnout, leading to a high NO reduction efficiency.
-
Key words:
- NO reduction /
- ethane /
- iron
-
马风哪, 程伟琴. 国内火电厂氮氧化物排放现状及控制技术探讨[J]. 广州化工, 2011, 39(15): 57-59. (MA Feng-na, CHENG Wei-qin. The discharge status and controlling measures of nitrogen oxides of thermal power plants in China[J]. Guangzhou Chem Ind, 2011, 39(15): 57-59.) 环境保护部和国家质量监督检验检疫总局. 火电厂大气污染物排放标准(GB13223-2011)[S], 2011. (Ministry of Environment Protection & General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China. Emission standard of air pollutants for thermal power plants(GB13223-2011)[S], 2011) PARVULESCU V I, GRANGE P, DELMON B. Catalytic removal of NO[J]. Catal Today, 1998, 46(4) : 233-316. JANSSEN F, MEIJER R. Quality control of DeNOx catalysts performance testing, surface analysis and characterization of DeNOx catalysts[J]. Catal Today, 1993, 16(2): 157-185. ERKFELDT S, PALMQVIST A, PEIERSSON M. Influence of the reducing agent for lean NOx reduction over Cu-ZSM-5[J]. Appl Catal B: Environ, 2011, 102(3/4): 547-554. YANG T T, BI H T, CHENG X X. Novel fluidized bed reactor for integrated NOx adsorption-reduction with hydrocarbons[J]. Environ Sci Technol, 2009, 43(13): 5049-5053. YANG T T, BI H T, CHENG X X. Effects of O2, CO2 and H2O on NOx adsorption and selective catalytic reduction over Fe/ZSM-5[J]. Appl Catal B: Environ, 2011, 102(1/2): 163-171 IWAMOTO M. Zeolites in environmental catalysis[J]. Stud Surf Sci Catal, 1994, 84: 1395-1410. TABATA T, KOKITSU M, OKADA O. Study on patent literature of catalysts for a new NOx removal process[J]. Catal Today, 1994, 22(1): 147-169. TRAA Y, BURGER B, WEITKAMP J. Zeolite-based materials for the selective catalytic reduction of NOx with hydrocarbons[J]. Microporous Mesoporous Mater, 1999, 30: 3-41. 荆国华, 李俊华, 杨栋, 郝吉明. 分子筛类催化剂上甲烷选择性催化还原NOx研究进展.化工进展, 2009, 28(3): 504-510. (JING Guo-Hua, LI Jun-Hua, YANG Dong, HAO Ji-Ming. Progress of selective catalytic reduction of NOx with methane over zeolite-based catalysts[J]. Chem Ind Eng Prog, 2009, 28(3): 504-510.) ILIOPOULOU E F, EVDOU A P, LEMONIDOU A A, VASALOS I A. Ag /alumina catalysts for the selective catalytic reduction of NOx using various reductants[J]. Appl Catal A: Gen, 2004, 274(1/2): 179-189. KOTSIFA A, KONDARIDES D I, VERYKIOS X E. A comparative study of the selective catalytic reduction of NO by propylene over supported Pt and Rh catalysts[J]. Appl Catal B: Environ, 2008, 80(3/4) : 260-270. LIU Z, WANG K, ZHANG X, WANG J, CAO H, GONG M, CHEN Y. Study on methane selective catalytic reduction of NO on Pt /Ce0.67 Zr0.33 O2 and its application[J]. J Nat Gas Chem, 2009, 18(1) : 66-70. HYHURST A N, NINOMIYA Y. Kinetics of the conversion of NO to N2 during the oxidation of iron particles by NO in a hot fluidised bed[J]. Chem Eng Sci, 1998, 53(8): 1481-1489. HAYHURST A N, LAWRENCE A D. The reduction of the nitrogen oxides NO and N2O to molecular nitrogen in the presence of iron, its oxides, and carbon monoxide in a hot fluidized bed[J]. Combust Flame, 1997, 110: 351-365 GRADON B, LASEK J. Investigation of reduction of NO to N2 by reaction with Fe[J]. Fuel, 2010, 89(11): 3505-3509 苏亚欣, 苏阿龙, 成豪. 金属铁直接催化还原NO的实验研究[J]. 煤炭学报, 2013, 38(S1): 206-210. (SU Ya-xin, SU A-long, CHENG Hao. Experimental study on direct catalytic reduction of NO by metallic iron[J]. J China Coal Soc, 2013, 38(S1): 206-210) 苏亚欣, 苏阿龙, 成豪. CO对铁丝网卷还原NO的影响实验研究[J]. 应用基础与工程科学学报, 2013, 21(4): 638-646. (SU Ya-xin, SU A-long, CHENG Hao. Experimental study on effect of CO on NO reduction by iron mesh roll[J]. J Basic Sci Eng, 2013, 21(4): 638-646.) 苏亚欣, 邓文义, 苏阿龙. 甲烷在氧化铁表面还原NO的特性与反应机理研究[J]. 燃料化学学报, 2013, 41(9): 1129-1135. (SU Ya-xin, DENG Wen-yi, SU A-long. NO reduction by methane over iron oxides and the mechanism[J]. J Fuel Chem Technol, 2013, 41(9): 1129-1135.) 苏亚欣, 苏阿龙, 任立铭, 邓文义. SO2对甲烷在金属铁表面还原NO的影响[J]. 燃料化学学报, 2014, 42(3): 377-384. (SU Ya-xin, SU A-long, REN Li-ming, DENG Wen-yi. Effect of SO2 on NO reduction by methane over iron[J]. J Fuel Chem Technol, 2014, 42(3): 377-384.) 周皞, 苏亚欣, 戚越舟, 陆哲惺, 邓文义.水蒸气对甲烷在金属铁表面还原NO的影响[J]. 燃料化学学报, 2014, 42(11): 1378-1386. (ZHOU Hao, SU Ya-xin, QI Yue-zhou, LU Zhe-xing, DENG Wen-yi. Effect of water vapor on NO reduction by methane over iron. J Fuel Chem Technol, 2014, 42(11): 1378-1386.) 苏亚欣, 任立铭, 苏阿龙, 邓文义. 甲烷在金属铁及氧化铁表面还原NO的实验研究[J]. 燃料化学学报, 2013, 41(11): 1393-1400. (SU Ya-xin, REN Li-ming, SU A-long, DENG Wen-yi. Experimental study on NO reduction by methane over iron and its oxides[J]. J Fuel Chem Technol, 2013, 41(11): 1393-1400.) 徐龙伢, 王昌东, 贾继飞, 杨力, 王德宝, 刘伟成, 王清遐, 林励吾. 乙烷与CO2制乙烯反应的热力学和动力学研究[J]. 催化学报, 1998, 19(6): 506-509. (XU Long-ya, WANG Chang-dong, JIA Ji-fei, YANG li, WANG De-bao, LIU Wei-cheng, WANG Qing-xia, LIN Li-wu. Analyses of thermodynamics and kinetics for C2H6 dehydrogenation with CO2 to C2H4[J]. Chin J Catal, 1998, 19(6): 506-509.) CHOUDHARY V R, MONDAL K C, MULLA S A R. Non-catalytic pyrolysis of ethane to ethylene in the presence of CO2 with or without limited O2[J]. J Chem Sci, 2006, 118(3): 261-267. JANAS J, ROJEK W, SHISHIDO T, DZWIGAJ S. Selective catalytic reduction of NO on single site FeSiBEA zeolite catalyst: Influence of the C1 and C2 reducing agents on the catalytic properties[J]. Appl Catal B: Environ, 2012, 123-124: 134-140. LECOMTE F, DAGAUT P, CHEVAILLER S, CATHONNET M. NO-reduction by ethane in a JSR at atmospheric pressure: experimental and kinetic modeling[J]. Combust Sci Technol, 2000, 150(1): 181-203. 苏亚欣, GATHITUB B, CHEN W Y. Fe2O3 控制再燃脱硝中间产物HCN的实验研究[J]. 环境科学学报, 2011, 31(6): 1181-1186. (SU Ya-xin, GATHITUB B, CHEN W Y. Experimental examination of HCN compound control by Fe2O3 during reburning processes[J]. Acta Scientiae Circumstantiae, 2011, 31(6): 1181-1186.) TAN H Z, WANG X B, NIU Y Q, LIU H Y, WANG C L, XU T M. Studies of intereaction mechanism between iron and HCN[J]. Asian J Chem, 2010, 22(5): 4017-4025. BILBAO R, MILLERA A, ALZUETA M U, PRADA L. Evaluation of the use of different hydrocarbon fuels for gas reburning[J]. Fuel, 1997, 76(14/15): 1401-1407. 胡大为, 秦永宁, 马智, 齐晓周, 张黎明. 负载型过渡金属氧化物催化剂上SO2 的还原[J]. 燃料化学学报, 2001, 29(6): 499-503. (HU Da-wei, QIN Yong-ning, MA Zhi, QI Xiao-zhou, ZHANG Li-ming. Reduction of sulfur dioxide over supported transition metal oxide[J]. J Fuel Chem Technol, 2001, 29(6): 499-503.)
点击查看大图
计量
- 文章访问数: 331
- HTML全文浏览量: 14
- PDF下载量: 442
- 被引次数: 0