活性炭表面含氧官能团对燃煤烟气氮氧化物脱除的影响
Effect of oxygen-containing functional groups on the removal of nitrogen oxides from coal-fired flue gas on activated carbon
-
摘要: 采用HNO3、H2SO4及H2O2对煤基活性炭进行氧化改性处理,研究低温(<250℃)下NH3为还原剂的选择催化还原(SCR)NOx的反应性能.通过元素分析、表面积和孔分布、Boehm滴定、TPD-MS、XPS分析对氧化前后活性炭表面物理化学性质进行分析,对表面含氧基团含量进行了定性定量研究.结果表明,与H2SO4及H2O2处理后相比,活性炭经HNO3氧化处理后表面羧基、酸酐和羟基含量明显增加,在考察温度范围内SCR活性明显提高,HNO3是最佳氧化剂.含氧基团含量与SCR活性的关联结果表明,羧基、酸酐和羟基等3种含氧基团对HNO3改性后活性炭样品的SCR活性提高发挥主要作用.Abstract: Coal-based activated carbon was oxidized by HNO3, H2SO4 and H2O2 and applied to the selective catalytic reduction (SCR) of NOx at low temperature (<250℃) with NH3 as a reducing agent. The physicochemical properties of activated carbon before and after oxidation treatment were characterized by elemental analysis, surface area and pore size distribution, Boehm titration, TPD-MS and XPS analysis, and the content of surface oxygen was studied qualitatively and quantitatively. Results showed that compared with the treatment of H2SO4 and H2O2, the content of carboxyl, anhydride and hydroxyl in the surface of activated carbon was significantly increased after the oxidation treatment of HNO3 and SCR activity was improved obviously in the reaction temperature, thus HNO3 was regarded as the best oxidant reagent. Furthermore, the correlation between the content of oxygen-containing groups and SCR activity indicated that three oxygen-containing groups of carboxyl, anhydride and hydroxyl were found to be mainly responsible for the promoted SCR activity of HNO3 modified AC.
-
[1] 赵永椿,马斯鸣,杨建平,等. 燃煤电厂污染物超净排放的发展及现状[J].煤炭转化, 2015, 40(11):2629-2640. ZHAO Y C, MA S M, YANG J P, et al. Development and current status of ultra-clean emissions of pollutants from coal-fired power plants[J].Coal Conversion, 2015, 40(11):2629-2640(in Chinese).
[2] 晋华东,景文,黄张根,等. 两种钒炭催化剂低温选择性催化还原脱硝性能比较及分析[J].环境化学, 2013, 32(10):1869-1873. JIN H D, JING W, HUANG Z G, et al, Comparison and analysisof the performance of two vanadium loaded carbon-based catalysts for the low temperature SCR of NO by ammonia[J].Environmental Chemistry, 2013, 32(10):1869-1873(in Chinese).
[3] 李雪飞,张文辉,杜铭华. 干法烟气脱硝综述[J].洁净煤技术, 2006, 12(3):43-46. LI X F, ZHANG W H, DU M H, Summary of dry flue gas denitrification[J]. Clean Coal Technology, 2006, 12(3):43-46(in Chinese).
[4] 郭旸旸,李玉然,朱廷钰,等.活性炭吸附法同时脱硫脱硝[C]//第七届全国环境化学大会摘要集,2013. GUO Y Y, LI Y R, ZHU T Y, et al, Simultaneous desulfurization and denitrification by activated carbon adsorption[C]//Summary of the 7th National Conference on Environmental Chemistry,2013(in Chinese). [5] TSUJI K,SHIRAISHI I. Combined desulfurization,denitrification and reduction of air toxics using activated coke:Activity of activated coke[J]. Fuel,1997,76(6):549-553. [6] 赵德生.太钢450 m2烧结机烟气脱硫脱硝工艺实践[C]//全国烧结烟气脱硫技术交流会论文集, 2011, 8-15. ZHAO D S, Practice of flue gas desulfurization and denitrification process for 450 m2 [7] GARCIA -BORDEJE E, LAZARO M J, MOLINER R, et al. Vanadium supported on carbon coated honeycomb monoliths for the selective catalytic reduction of NO at low temperatures:Influence of the oxidation pre-treatment[J]. Carbon, 2006, 44(3):407-417. [8] BOYANO A, HERRERA C, LARRUBIA M A, et al. Vanadium loaded carbon-based monoliths for the on-board no reduction:Influence of temperature and period of the oxidation treatment[J]. Chemical Engineering Journal, 2010, 160(2):623-633. [9] TENG H, TU Y T, LAI Y C, et al. Reduction of NO with NH3 over carbon catalysts:The effects of treating carbon with H2SO4 and HNO3[J]. Carbon, 2001, 39(4):575-582. [10] ZHU L, HUANG B, WANG W, et al. Low-temperature SCR of NO with NH3 over CeO2 supported on modified activated carbon fibers[J]. Catalysis Communications, 2011, 12(6):394-398. [11] BOYANO A, GALVEZ M E, MOLINER R, et al. Carbon-based catalytic briquettes for the reduction of NO:Effect of H2SO4 and HNO3 carbon support treatment[J]. Fuel, 2008, 87(10/11):2058-2068. [12] GALVEZ M E, LAZARO M J, MOLINER R. Novel activated carbon-based catalyst for the selective catalytic reduction of nitrogen oxide[J]. Catalysis Today, 2005, 102-103:142-147. [13] HUANG M C, TENG H. Nitrogen-containing carbons from phenol-formaldehyde resins and their catalytic activity in NO reduction with NH3[J]. Carbon, 2003, 41(5):951-957. [14] AHMED S N, BALDWIN R, DERBYSHIRE F, et al. Catalytic reduction of nitric oxide over activated carbons[J]. Fuel, 1993, 72(3):287-292. [15] ZHU Z, LIU Z, LIU S, et al. NO reduction with NH3 over an activated carbon-supported copper oxide catalysts at low temperatures[J]. Applied Catalysis B:Environmental, 2000, 26(1):25-35. [16] SZYMANSKI G S, KARPINSKI Z, BINIAK S, et al. The effect of the gradual thermal decomposition of surface oxygen species on the chemical and catalytic properties of oxidized activated carbon[J]. Carbon, 2002, 40(14):2627-2639. [17] FIGUEIREDO J L, PERAIRA M F R, FREITAS M A, et al. Modification of the surface chemistry of activated carbons[J]. Carbon, 1999, 37(9):1379-1389. [18] 佟莉,徐文青,元昊, 等. 硝酸改性活性炭上氧/氮官能团对脱汞性能的促进作用[J].物理化学学报, 2015,31(3):512-518. TONG L, XU W Q, YUAN H, et al, Enhanced Effect of O/N groups on the Hg0 removal efficiency over the HNO3-modified activated carbon[J]. Acta Phys.-Chim. Sin, 2015,31(3):512-518(in Chinese).
[19] MORALES-TORRES S, SILVA T L S, PASTRANA-MARTINEZ L M, et al. Modification of the surface chemistry of singleand multi-walled carbon nanotubes by HNO3 and H2SO4 hydrothermal oxidation for application in direct contact membrane distillation[J]. Physical Chemistry Chemical Physics, 2014, 16(24):12237-12250. [20] ZHOU J H, SUI Z J, ZHU J, et al. Characterization of surface oxygen complexes on carbon nanofibers by TPD, XPS and FT-IR[J]. Carbon, 2007, 45(4):785-796. [21] SWIATKOWSKIi A, PAKULA M, BINIAK S, et al. Influence of the surface chemistry of modified activated carbon on its electrochemical behaviour in the presence of lead(Ⅱ) ions[J]. Carbon, 2004, 42(15):3057-3069.
计量
- 文章访问数: 2456
- HTML全文浏览数: 2456
- PDF下载数: 52
- 施引文献: 0