Research progress of mercury adsorption and oxidation mechanism on modified coal-fired fly ash

doi:10.16085/j.issn.1000-6613.2016-2410

Abstract

Abstract: It is difficult to control the mercury pollution in coal-fired power plant, especially for elemental mercury. Thus, the development of mercury sorbent with high efficiency and low cost has been scientific and technological focus. Coal-fired fly ash modified with halide has low price and strong potential for mercury removal. However,the adsorption and oxidation mechanism of Hg⁰ on modified fly ash is unclear and still needs further study. This review systematically summarized the current state of knowledge associated with fly ash used as mercury sorbent on controlling flue gas mercury pollution. Then,the mercury removal behaviors on various factors were discussed, including physicochemical characteristics, flue gas components and halogen. The heterogeneous reaction on the surface active sites of unburned carbon and inorganic components was the key point of Hg⁰ oxidative removal. Furthermore, the merits and faults of unburned carbon and magnetosphere acted as carrier were analyzed. In addition, the influences of modifying agent and preparation method on direct modification of fly ash and the adsorption mechanisms on HBr-modified fly ash were discussed. Finally,future research directions were proposed,involving exploring the characteristics for Hg⁰ binding on the organic and inorganic portion of fly ash,and studying the reaction dynamic behaviors of Hg⁰ on the surface of multi-components through combination of quantum chemistry theory and macroscopic experimental investigation.

Key words: mercury pollution, sorbents, coal-fired fly ash, oxidation, surface reactivity, halogenated modification

摘要： 元素汞是燃煤电站汞污染防治工作的难点，研究开发高效价廉的汞吸附剂已被作为科技攻关重点方向。燃煤飞灰经卤化物改性后脱汞潜力强、成本低，但必须研究掌握其吸附氧化Hg⁰的作用机制。本文系统综述了飞灰作为脱汞材料在国内外燃煤烟气汞污染控制方面的研究进展。论述了物化特性、烟气组分、卤素等因素对飞灰脱汞性能的影响，指出未燃尽炭和无机矿物组分表面活性位上的非均相反应是Hg⁰氧化脱除的关键。分析了残炭和磁珠作为载体材料的优缺点，并讨论了不同改性剂和改性方法对飞灰直接改性的影响。总结了HBr改性飞灰对Hg⁰的吸附氧化机理，并提出利用量子化学理论与宏观实验研究相结合的方式探索Hg⁰在飞灰表面上的成键特征及反应动力学特性应作为今后的研究方向。

关键词: 汞污染, 吸附剂, 燃煤飞灰, 氧化, 表面活性, 卤化改性

CLC Number:

X511
X705

GU Yongzheng, WANG Shumin. Research progress of mercury adsorption and oxidation mechanism on modified coal-fired fly ash[J]. Chemical Industry and Engineering Progress, 2017, 36(11): 4257-4264.

顾永正, 王树民. 改性燃煤飞灰吸附氧化脱汞机理研究进展[J]. 化工进展, 2017, 36(11): 4257-4264.

References

[1] 潘伟平,张永生,李文瀚,等.燃煤汞污染监测及控制技术[J].科技导报,2014,32:57-60. PAN W P,ZHANG Y S,LI W H,et al.Mercury monitoring and controlling technologies for coal power plants[J].Science & Technology Review,2014,32:57-60.
[2] 谭增强,牛国平.烟气汞脱除的研究进展[J].热力发电,2013,42(10):1-8. TAN Z Q,NIU G P.Research progress of mercury removal in flue gas[J].Thermal Power Generation,2013,42(10):1-8.
[3] 刘思妹,朱毅,郝睿.国内外汞污染现状及管理措施[J].环境科学与技术,2014,37(120):290-294. LIU S M,ZHU Y,HAO R.A review of mercury pollution and management in the domestic and overseas[J].Environmental Science & Technology,2014,37(120):290-294.
[4] The State of U.S. Mercury control in response to MATS[EB/OL].[2016-12-26].http://www.powermag.com/the-state-of-us-mercury-control-in-response-to-mats/.
[5] BLISSETT R S,ROWSON N A.A review of the multi-component utilisation of coal fly ash[J].Fuel,2012,97(7):1-23.
[6] PRESTO A A,GRANITE E J.Survey of catalysts for oxidation of mercury in flue gas[J].Environmental Science & Technology,2006,40(18):5601-5609.
[7] BALAJI K,HELBLE J J.Understanding mercury transformations in coal-fired power plants:evaluation of homogeneous Hg oxidation mechanisms[J].Environmental Science & Technology,2007,41(22):7870-7875.
[8] NIKSA S,FUJIWARA N.Predicting extents of mercury oxidation in coal-derived flue gases[J].Journal of the Air & Waste Management Association,2005,55(7):930-939.
[9] ZHOU J S,LUO Z Y,HU C X,et al.Factors impacting gaseous mercury speciation in postcombustion[J].Energy & Fuels,2006,21(21):491-495.
[10] PAN H Y,MINET R G,BENSON S W,et al.Process for converting hydrogen chloride to chlorine[J].Indengchemres,1994,33(12):2996-3003.
[11] GRANITE E J,PENNLINE H W,HARGIS R A.Novel sorbents for mercury removal from flue gas[J].Ind. Eng. Chem. Res.,2000,39(4):1020-1029.
[12] HE S,ZHOU J S,ZHU Y Q,et al.Mercury oxidation over a vanadia-based selective catalytic reduction catalyst[J].Energy & Fuels,2009,23(1):253-259.
[13] 孟素丽,段钰锋,黄治军,等.烟气成分对燃煤飞灰汞吸附的影响[J].中国电机工程学报,2009,29(20):66-73. MENG S L,DUAN Y F,HUANG Z J,et al.Effect of flue gas components on mercury adsorption by coal-fired fly ash[J].Proceedings of the CSEE,2009,29(20):66-73.
[14] 匡俊艳,徐文青,朱廷钰,等.粉煤灰物化性质对单质汞吸附性能的影响[J].燃料化学学报,2012,40(6):763-768. KUANG J Y,XU W Q,ZHU T Y,et al.Effect of physicochemical properties of fly ash on mercury adsorption performance[J].Journal of Fuel Chemistry and Technology,2012,40(6):763-768.
[15] 樊保国,贾里,李晓栋,等.电站燃煤锅炉飞灰特性对其吸附汞能力的影响[J].动力工程学报,2016,36(8):621-628. FAN B G,JIA L,LI X D,et al.Study on mercury adsorption by fly ash from coal-fired boilers of power plants[J].Journal of Chinese Society of Power Engineering,2016,36(8):621-628.
[16] 江贻满,段钰锋,杨祥花,等.ESP飞灰对燃煤锅炉烟气汞的吸附特性[J].东南大学学报(自然科学版),2007,37(3):436-440. JIANG Y M,DUAN Y F,YANG X H,et al.Adsorption characterization of coal fired flue gas mercury by ESP fly ashs[J].Journal of Southeast University (Natural Science Edition),2007,37(3):436-440.
[17] ZHONG L C,ZHANG Y S,LIU Z,et al.Study of mercury adsorption by selected Chinese coal fly ashes[J].Journal of Thermal Analysis & Calorimetry,2014,116(3):1197-1203.
[18] 李猛,刘晶,郑楚光.未燃尽炭表面吸附汞的机理研究[J].工程热物理学报,2007(5):882-884. LI M,LIU J,ZHENG C G.Studies on mercury adsorption mechanism on unburned carbon surface[J].Journal of Engineering Thermophysics,2007(5):882-884.
[19] ABAD-VALLE P,LOPEZ-ANTON M A,DIAZ-SOMOANO M,et al.The role of unburned carbon concentrates from fly ashes in the oxidation and retention of mercury[J].Chemical Engineering Journal,2011,174(1):86-92.
[20] LI J R,MAROTO-VALER M M.Computational and experimental studies of mercury adsorption on unburned carbon present in fly ash[J].Carbon,2012,50(50):1913-1924.
[21] HUGGINS F E,YAP N,HUFFMAN G P,et al.XAFS characterization of mercury captured from combustion gases on sorbents at low temperatures[J].Fuel Processing Technology,2003,82(2/3):167-196.
[22] OLSON E S,MILLER S J,SHARMA R K,et al.Catalytic effects of carbon sorbents for mercury capture[J].Journal of Hazardous Materials,2000,74(1/2):61-79.
[23] GOODARZI F,HOWER J C.Classification of carbon in Canadian fly ashes and their implications in the capture of mercury[J].Fuel,2008,87(10/11):1949-1957.
[24] ZHAO Y C,ZHANG J Y,LIU J,et al.Experimental study on fly ash capture mercury in flue gas[J].Science China (Technological Sciences),2010,53(4):976-983.
[25] 屈文麒,刘晶,袁锦洲,等.NO对未燃尽炭吸附汞影响的机理研究[J].工程热物理学报,2010,31(3):523-526. Qu W Q,LIU J,YUAN J Z,et al.Effect of nitric oxide on mercury adsorption capacity on unburned carbon[J].Journal of Engineering Thermophysics,2010,31(3):523-526.
[26] LIU J,QU W Q,SANG W J,et al.Effect of SO₂ on mercury binding on carbonaceous surfaces[J].Chemical Engineering Journal,2012,184(2):163-167.
[27] 中华人民共和国国家质量监督检验检疫总局,中国国家标准化管理委员会.用于水泥和混凝土中的粉煤灰:GBT1596-2005[S].北京:中国标准出版社,2005. General Administration of Quality Supervision,Inspection and Quarantine of the People's Republic of China,Standardization Administration of the People's Republic of China.Fly ash used for cement and concrete:GBT1596-2005[S].Beijing:Standards Press of China,2015.
[28] DUNHAM G E,DEWALL R A,SENIOR C L.Fixed-bed studies of the interactions between mercury and coal combustion fly ash[J].Fuel Processing Technology,2003,82(2):197-213.
[29] GHORISHI S B,LEE C W,JOZEWICZ W S,et al.Effects of fly ash transition metal content and flue gas HCl/SO₂ ratio on mercury speciation in waste combustion[J].Environmental Engineering Science,2005,22(2):221-231.
[30] ABAD-VALLE P,LOPEZ-ANTON M A,DIAZ-SOMOANO M,et al.Influence of iron species present in fly ashes on mercury retention and oxidation[J].Fuel,2011,90(8):2808-2811.
[31] 张锦红.燃煤飞灰特性及其对烟气汞脱除作用的实验研究[D].上海:上海电力学院,2013. ZHANG J H.The experimental study of fly ash properties and its effect on flue gas mercury removal[D].Shanghai:Shanghai University of Electric Power,2013.
[32] 张翼,杨建平,赵永椿,等.可循环磁珠脱除燃煤烟气中单质汞的性能与工艺路线研究[J].热力发电,2016,45(10):10-15. ZHANG Y,YANG J P,ZHAO Y C,et al.Mercury capture performance of recyclable magnetospheres catalyst for coal-fired flue gas and the process route study[J].Thermal Power Generation,2016,45(10):10-15.
[33] YANG J P,ZHAO Y C,ZHANG J Y,et al.Regenerable cobalt oxide loaded magnetosphere catalyst from fly ash for mercury removal in coal combustion flue gas[J].Environmental Science & Technology,2014,48(24):14837-14843.
[34] YANG J P,ZHAO Y C,ZHANG J Y,et al.Removal of elemental mercury from flue gas by recyclable CuCl₂ modified magnetospheres catalyst from fly ash.Part 1.Catalyst characterization and performance evaluation[J].Fuel,2015,164:419-428.
[35] XU W Q,WANG H R,ZHU T Y,et al.Mercury removal from coal combustion flue gas by modified fly ash[J].Journal of Environmental Sciences,2013,25(2):393-398.
[36] LIU M M,HOU L A,XI B D,et al.Synthesis,characterization,and mercury adsorption properties of hybrid mesoporous aluminosilicate sieve prepared with fly ash[J].Applied Physics Letters,2013,273(100):706-716.
[37] XING L L,XU Y L,ZHONG Q.Mn and Fe modified fly ash as a superior catalyst for elemental mercury capture under air conditions[J].Energy & Fuels,2012,26(8):4903-4909.
[38] CAO Y,DUAN Y F,KELLIE S,et al.Impact of coal chlorine on mercury speciation and emission from a 100MW utility boiler with cold-side electrostatic precipitators and low-NO_x burners[J].Energy & Fuels,2005,19(3):842-854.
[39] CAO Y,GAO Z Y,ZHU J S,et al.Impacts of halogen additions on mercury oxidation,in a slipstream selective catalyst reduction (SCR),reactor when burning sub-bituminous coal[J]. Environmental Science & Technology,2008,42(1):256-261.
[40] CAO Y,WANG Q H,CHEN C W,et al.Investigation of mercury transformation by HBr addition in a slipstream facility with real Flue gas atmospheres of bituminous coal and powder river basin coal[J].Energy & Fuels,2007,21(5):2719-2730.
[41] CAO Y,WANG Q H,LI J,et al.Enhancement of mercury capture by the simultaneous addition of hydrogen bromide (HBr) and fly ashes in a slipstream facility[J]. Environmental Science & Technology,2009,43(8):2812-2817.
[42] WANG S M,ZHANG Y S,GU Y Z,et al.Using modified fly ash for mercury emissions control for coal-fired power plant applications in China[J].Fuel,2016,181(1):1230-1237.
[43] 段威.飞灰基吸附剂在携带床反应器上对汞的吸附性能研究[D].北京:华北电力大学,2014. DUAN W.Research of fly ash sorbents on the mercury absorption characteristics in entrained-flow reactor[D].Beijing:North China Electric Power University,2014.
[44] GU Y Z,ZHANG Y S,LIN L R,et al.Evaluation of elemental mercury adsorption by fly ash modified with ammonium bromide[J].Journal of Thermal Analysis & Calorimetry,2015,119(3):1663-1672.
[45] 李晖.燃煤飞灰的改性和吸附机理研究[D].合肥:中国科学技术大学,2015. LI H.Modification and adsorption mechanism of coal fly ash[D].Hefei:University of Science and Technology of China,2015.
[46] HUTSON N D,ATTWOOD B C,SCHECKEL K G.XAS and XPS characterization of mercury binding on brominated activated carbon[J].Environmental Science & Technology,2007,41(5):1747-1752.
[47] YANG Y J,LIU J,SHEN F H,et al.Kinetic study of heterogeneous mercury oxidation by HCl on fly ash surface in coal-fired flue gas[J].Combustion & Flame,2016,168:1-9.
[48] LIU J,QU W Q,ZHENG C G.Theoretical studies of mercury-bromine species adsorption mechanism on carbonaceous surface[J].Proceedings of the Combustion Institute,2012,34(2):2811-2819.
[49] LOPEZ-ANTON M A,PERRY R,ABAD-VALLE P,et al.Speciation of mercury in fly ashes by temperature programmed decomposition[J]. Fuel Processing Technology,2011,92(3):707-711.
[50] LI W H,SONG N,ZHANG Y S,et al.Mercury sorption properties of HBr-modified fly ash in a fixed bed reactor[J].Journal of Thermal Analysis & Calorimetry,2015:1-7.
[51] ZHANG Y S,ZHAO L L,GUO R T,et al.Mercury adsorption characteristics of HBr-modified fly ash in an entrained-flow reactor[J].Journal of Environmental Sciences,2015,33(7):156-162.
[52] WILCOX J,ERDEM S,ABBY K,et al.Heterogeneous mercury reaction chemistry on activated carbon[J].Journal of the Air & Waste Management Association,2011,61(4):418-426.
[53] NIKSA S,FUJIWARA N,FUJITA Y,et al.A mechanism for mercury oxidation in coal-derived exhausts[J].Journal of the Air & Waste Management Association,2002,52(8):894-901.
[54] LI Y H,LEE C W,GULLETT B K.Importance of activated carbon's oxygen surface functional groups on elemental mercury adsorption[J].Fuel,2003,82(4):451-457.
[55] TAN Z Q,SUN L S,XIANG J,et al.Gas-phase elemental mercury removal by novel carbon-based sorbents[J].Carbon,2012,50(2):362-371.
[56] OLSON E S,AZENKENG A,LAUMB J D,et al.New developments in the theory and modeling of mercury oxidation and binding on activated carbons in flue gas[J].Fuel Processing Technology,2009,90(11):1360-1363.
[57] DIAMANTOPOULOU I,SKODRAS G,SAKELLAROPOULOS G P.Sorption of mercury by activated carbon in the presence of flue gas components[J].Fuel Processing Technology,2010,91(2):158-163.
[58] PRESTO A A,GRANITE E J.Noble metal catalysts for mercury oxidation in utility flue gas[J].Platinum Metals Review,2008,52(52):144-154.
[59] GU Y Z,ZHANG Y S,LIN J W,et al.Homogeneous mercury oxidation with bromine species released from HBr-modified fly ash[J].Fuel,2016,169:58-67.
[60] SONG N,TENG Y,WANG J W,et al.Effect of modified fly ash with hydrogen bromide on the adsorption efficiency of elemental mercury[J].Journal of Thermal Analysis & Calorimetry,2014,116(3):1189-1195.