不同烟气组分对粉状活性焦吸附汞的影响机理
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摘要
在模拟燃煤热烟气为热源和介质条件下,以准东褐煤为原料,通过一维沉降炉进行炭化活化(一步法)制备粉状活性焦,考察了活性焦对Hg~0的吸附能力,探索了SO_2、H_2O、O_2、CO_2、H_2O+O_2、SO_2+O_2及H_2O+SO_2+O_2气氛对活性焦吸附Hg~0的影响机理。结果表明:一步法获得的活性焦对Hg~0具有较高的吸附性能。N_2气氛作对比,H_2O、H_2O+O_2、CO_2和SO_2气氛下抑制活性焦对Hg~0的吸附;O_2、SO_2+O_2和H_2O+SO_2+O_2促进活性焦对Hg~0的吸附。通过Hg 4f的XPS分析证明了不同气氛组成对活性焦吸附Hg~0的抑制和促进机理。H_2O覆盖在活性焦活性位上和堵塞孔隙而抑制活性焦对Hg~0的吸附;SO_2与Hg~0在活性焦上发生竞争吸附而抑制对Hg~0的吸附;CO_2吸附在活性焦微孔上而抑制对Hg~0的吸附;O_2气氛下主要形成了HgO, SO_2+O_2气氛下Hg~0被氧化成HgSO_3,进一步氧化成HgSO_4; H_2O+SO_2+O_2气氛下,Hg~0被氧化成HgO和HgSO_4。
Under the condition of simulating coal-fired hot flue gas as heat source and medium, quasi-east lignite was used as raw material to carry out carbonization activation(one-step method) to prepare powdery activated coke by one-dimensional settling furnace, and the adsorption capacity of activated coke to Hg~0 was investigated. Further,the effects of SO_2, H_2O, O_2, CO_2, H_2O+O_2, SO_2+O_2 and H_2O+SO_2+O_2 on Hg~0 removal efficiency were examined in flue gas. The results indicate that the coke has high adsorption performance for Hg~0 removal. The N2 atmosphere was used as comparison, the O_2, SO_2+O_2 and H_2O+SO_2+O_2 are beneficial for Hg~0 removal, while the H_2O, CO_2, SO_2 and H_2O+O_2 have inhibiting effect on Hg~0 removal. Furthermore, the spectra of Hg 4 f were determined by XPS, in order to explore the mechanism of inhibition and promotion of Hg~0 adsorption by activated coke under different flue gas.H_2O can inhibit the adsorption of active coke on Hg~0 via covering the active coke sites and blocking the pores, SO_2 can inhibit the adsorption through the competitive adsorption of SO_2 and HgO on the active coke, and CO_2 that adsorbed on the active coke micropore also can inhibit the adsorption of active coke on Hg~0. In the atmosphere of O_2 and SO_2+O_2, the Hg~0 is oxidized into HgO and HgSO_3, separately. And the HgSO_3 further oxidized into HgSO_4 by O_2.Besides, in the atmosphere of H_2O+SO_2+O_2, Hg~0 is oxidized into HgO and HgSO_4.
Under the condition of simulating coal-fired hot flue gas as heat source and medium, quasi-east lignite was used as raw material to carry out carbonization activation(one-step method) to prepare powdery activated coke by one-dimensional settling furnace, and the adsorption capacity of activated coke to Hg~0 was investigated. Further,the effects of SO_2, H_2O, O_2, CO_2, H_2O+O_2, SO_2+O_2 and H_2O+SO_2+O_2 on Hg~0 removal efficiency were examined in flue gas. The results indicate that the coke has high adsorption performance for Hg~0 removal. The N2 atmosphere was used as comparison, the O_2, SO_2+O_2 and H_2O+SO_2+O_2 are beneficial for Hg~0 removal, while the H_2O, CO_2, SO_2 and H_2O+O_2 have inhibiting effect on Hg~0 removal. Furthermore, the spectra of Hg 4 f were determined by XPS, in order to explore the mechanism of inhibition and promotion of Hg~0 adsorption by activated coke under different flue gas.H_2O can inhibit the adsorption of active coke on Hg~0 via covering the active coke sites and blocking the pores, SO_2 can inhibit the adsorption through the competitive adsorption of SO_2 and HgO on the active coke, and CO_2 that adsorbed on the active coke micropore also can inhibit the adsorption of active coke on Hg~0. In the atmosphere of O_2 and SO_2+O_2, the Hg~0 is oxidized into HgO and HgSO_3, separately. And the HgSO_3 further oxidized into HgSO_4 by O_2.Besides, in the atmosphere of H_2O+SO_2+O_2, Hg~0 is oxidized into HgO and HgSO_4.
引文
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[15] Li H, Zhu L, Wu S K, et al. Synergy of CuO and CeO2combination for mercury oxidation under low-temperature selective catalytic reduction atmosphere[J]. International Journal of Coal Geology,2017, 170:69-76.
[16]乔少华,晏乃强,陈杰,等. MnOx/a-Al2O3催化氧化燃煤烟气中Hg0的试验研究[J].中国环境科学, 2009, 29(3):237-241.Qiao S H, Yan N Q, Chen J, et al. Catalytic oxidation of elemental mercury in flue gas on MnOx/a-Al2O3[J]. China Environmental Science, 2009, 29(3):237-241.
[17] Zhang A C, Xing W B, Zhang Z H, et al. Promotional effect of SO2on CeO2/TiO2material for elemental mercury removal at low temperature[J]. Atmos. Pollut. Res., 2016, 7(5):895-902.
[18]李阳,朱玉雯,高继慧,等.活性焦孔结构演变规律及对脱硫性能的影响[J].化工学报, 2015, 66(3):1126-1132.Li Y, Zhu Y W, Gao J H, et al. Activated coke pore structure evolution and its influence on desulfuration[J]. CIESC Journal,2015, 66(3):1126-1132.
[19]华晓宇,周劲松,高翔,等.渗铈活性焦汞脱附性能实验研究[J].中国电机工程学报, 2011, 31(29):61-66.Hua X Y, Zhou J S, Gao X, et al. Experimental investigation of mercury desorption on CeO2impregnated activated coke[J].Proceedings of the CSEE, 2011, 31(29):61-66.
[20]熊银伍,杜铭华,步学鹏,等.改性活性焦脱除烟气中汞的实验研究[J].中国电机工程学报, 2007, 27(35):17-22.Xiong Y W, Du M H, Bu X P, et al. Experimental research of removing mercury from flue gas by modified activated coke[J].Proceedings of the CSEE, 2007, 27(35):17-22.
[21]陈传敏,贾文波,刘松涛,等. CuO改性商用选择性催化还原催化剂催化氧化单质汞性能[J].化工进展, 2018, 37(10):3903-3910.Chen C M, Jia W B, Liu S T, et al. Catalytic oxidation of elemental mercury over CuO2modified commercial SCR catalyst[J].Chemical Industry and Engineering Progress, 2018, 37(10):3903-3910.
[22]赵玉冰,郭淼,白中华,等.活性焦脱汞实验研究[J].洁净煤技术, 2013, 19(1):48-51.Zhao Y B, Guo M, Bai Z H, et al. Experimental research of mercury removal efficiency by activated coke[J]. Clean Coal Technology, 2013, 19(1):48-51.
[23] Scala F, Chirone R, Lancia A. Elemental mercury vapor capture by powdered activation carbon in a fluidized bed reactor[J]. Fuel,2010, 90:2077-2082.
[24] Brunauer S, Deming L, Deming W, et al. On a theory of the van der Waals adsorption of gases[J]. Journal of the American Chemical Society, 1940, 62(7):1723-1732.
[25] Clarkson C, Solano N, Bustin R, et al. Pore structure characterization of North American shale gas reservoirs using USANS/SANS, gas adsorption, and mercury intrusion[J]. Fuel,2013, 103:606-616.
[26]石佩佩.活性炭孔结构和改性对燃煤烟气脱汞的影响及机理研究[D].徐州:中国矿业大学, 2016.Shi P P. The effect of pore structure and modified of activated carbons on mercury removal in flue gas and adsorption mechanism[D]. Xuzhou:China University of Mining and Technology, 2016.
[27]沈彩琴.活性炭纤维表面吸附汞机理的密度泛函理论研究[D].杭州:浙江工业大学, 2015.Shen C Q. Density functional theory study on the mechanism of mercury adsorption by activated carbon fiber[D]. Hangzhou:Zhejiang University of Technology, 2015.
[28] Wang J, Yang J, Liu Z, et al. Gas-phase elemental mercury capture by a V2O5/AC catalyst[J]. Fuel Processing Technology,2010, 91:676–680.
[29]许绿丝.改性处理活性炭纤维吸附氧化脱除SO2/NOx/Hg的研究[D].武汉:华中科技大学.2007.Xu L S. Study on adsorption and oxidation removal of SO2/NOx/Hg at low-temperature by modified activated carbon fiber[D].Wuhan:Huazhong University of Science&Technology, 2007.
[30] Wang Y, Duan Y, Yang L, et al. Experimental study on mercury transformation and removal in coal-fired boiler flue gas[J]. Fuel Processing Technology, 2009, 90:643–651.
[31] Wei Z, Luo Y, Li B. Microwave assisted catalytic removal of elemental mercury from flue gas using Mn/zeolite catalyst[J].Atmospheric Pollution Research, 2015, 6(1):645-651.
[32] Cai J, Shen B, Li Z, et al. Removal of elemental mercury by clays impregnated with KI and KBr[J]. Chemical Engineering Journal,2014, 241:19-27.
[33]薛源,段钰锋,王卉,等.模拟富氧烟气中CO2对活性炭脱汞的实验研究[J].发电设备, 2017, 31(2):99-103.Xue Y, Duan Y F, Wang H, et al. Experimental research on mercury removal by activated carbon with CO2in simulated flue gas from oxy-fuel combustion[J]. Power Equipment, 2017, 31(2):99-103.
[2] Yan N Q, Liu S H, Chang S G, et al. Method for the study of gaseous oxidants for the oxidation of mercury gas[J]. Ind. Eng.Chem. Res., 2005, 44(15):5567-5574.
[3]周长松,孙路石,张安超,等.非均相类Fenton催化剂脱汞的实验与机理[J].化工学报, 2015, 66(4):1324-1330.Zhou C S, Sun L S, Zhang A C, et al.Catalytic removal of Hg0in flue gas by heterogeneous Fenton-like catalysts[J]. CIESC Journal, 2015, 66(4):1324-1330.
[4]沈伯雄,蔡记,陈建宏,等. KBr和KI改性黏土脱除模拟烟气中的单质汞[J].化工学报, 2014, 65(2):711-717.Shen B X, Cai J, Chen J H, et al. Removal of element mercury from simulated flue gas by clay modified with KBr and KI[J].CIESC Journal, 2014, 65(2):711-717.
[5]韩军,徐明厚,詹靖,等.煤燃烧过程汞排放的模拟[J].中国电机工程学报, 2003, 23(12):208-212.Han J, Xu M H, Zhan J, et al. Pridicting the emission of mercury during coal combustion[J]. Proceedings of the CSEE, 2003, 23(12):208-212.
[6] Zhou Z, Liu X, Hu Y. An efficient sorbent based on CuCl2loaded CeO2-ZrO2for elemental mercury removal from chlorine-free flue gas[J]. Fuel, 2018, 216:356-363.
[7]罗小雨,苏胜,向军,等.汞在MnOx-CeO2/γ-Al2O3催化剂表面的赋存形态分析[J].化工学报, 2015, 66(6):2082-2088.Luo X Y, Su S, Xiang J, et al.Speciation of mercury formed on MnOx-CeO2/γ-Al2O3catalyst surface[J].CIESC Journal, 2015, 66(6):2082-2088.
[8] Wang S, Zhang L, Li G, et al. Mercury emission and speciation of coal-fired power plants in China[J]. Atmospheric Chemistry and Physics, 2010, 10(3):1183-1192.
[9] Wu S, Li H, Li L, et al. Effects of flue-gas parameters on low temperature NO reduction over a Cu-promoted CeO2-TiO2catalyst[J]. Fuel, 2015, 159:876-882.
[10] Zhao Y, Zhang J, Liu J, et al. Experimental study on fly ash capture mercury in flue gas[J]. Science China-Technological Sciences, 2010, 53(4):976-983.
[11]丁峰,张军营,赵永椿,等.天然矿物材料吸附剂脱除烟气中单质汞的实验研究[J].中国电机工程学报, 2009, 29(35):65-70.Ding F, Zhang J Y, Zhao Y C, et al. Experimental study on natural mineral sorbents to remove element mercury in flue gas[J].Proceedings of the CSEE, 2009, 29(35):65-70.
[12] Xu W, Yusuf G, Liu Y, et al. Removal of elemental mercury from flue gas using CuOx and CeO2modified rice straw chars enhanced by ultrasound[J]. Fuel Processing Technology, 2018, 170:21–31.
[13]任建莉,周劲松,骆仲泱,等.钙基类吸附剂脱除烟气中气态汞的试验研究[J].燃料化学学报, 2006, 34(5):557-561.Ren J L, Zhou J S, Luo Z Y, et al. Ca-based sorbents for mercury vapor removal from flue gas[J]. Journal of Fuel Chemistry and Technology, 2006, 34(5):557-561.
[14]黄治军,段钰锋,王运军,等.改性氢氧化钙吸附脱除模拟烟气中汞的试验研究[J].中国电机工程学报, 2009, 29(17):56-62.Huang Z J, Duan Y F, Wang Y J, et al. Experimental investigation on absorption of Hg in simulated fuel gas by modified Ca(OH)2[J].Proceedings of the CSEE, 2006, 34(5):557-561.
[15] Li H, Zhu L, Wu S K, et al. Synergy of CuO and CeO2combination for mercury oxidation under low-temperature selective catalytic reduction atmosphere[J]. International Journal of Coal Geology,2017, 170:69-76.
[16]乔少华,晏乃强,陈杰,等. MnOx/a-Al2O3催化氧化燃煤烟气中Hg0的试验研究[J].中国环境科学, 2009, 29(3):237-241.Qiao S H, Yan N Q, Chen J, et al. Catalytic oxidation of elemental mercury in flue gas on MnOx/a-Al2O3[J]. China Environmental Science, 2009, 29(3):237-241.
[17] Zhang A C, Xing W B, Zhang Z H, et al. Promotional effect of SO2on CeO2/TiO2material for elemental mercury removal at low temperature[J]. Atmos. Pollut. Res., 2016, 7(5):895-902.
[18]李阳,朱玉雯,高继慧,等.活性焦孔结构演变规律及对脱硫性能的影响[J].化工学报, 2015, 66(3):1126-1132.Li Y, Zhu Y W, Gao J H, et al. Activated coke pore structure evolution and its influence on desulfuration[J]. CIESC Journal,2015, 66(3):1126-1132.
[19]华晓宇,周劲松,高翔,等.渗铈活性焦汞脱附性能实验研究[J].中国电机工程学报, 2011, 31(29):61-66.Hua X Y, Zhou J S, Gao X, et al. Experimental investigation of mercury desorption on CeO2impregnated activated coke[J].Proceedings of the CSEE, 2011, 31(29):61-66.
[20]熊银伍,杜铭华,步学鹏,等.改性活性焦脱除烟气中汞的实验研究[J].中国电机工程学报, 2007, 27(35):17-22.Xiong Y W, Du M H, Bu X P, et al. Experimental research of removing mercury from flue gas by modified activated coke[J].Proceedings of the CSEE, 2007, 27(35):17-22.
[21]陈传敏,贾文波,刘松涛,等. CuO改性商用选择性催化还原催化剂催化氧化单质汞性能[J].化工进展, 2018, 37(10):3903-3910.Chen C M, Jia W B, Liu S T, et al. Catalytic oxidation of elemental mercury over CuO2modified commercial SCR catalyst[J].Chemical Industry and Engineering Progress, 2018, 37(10):3903-3910.
[22]赵玉冰,郭淼,白中华,等.活性焦脱汞实验研究[J].洁净煤技术, 2013, 19(1):48-51.Zhao Y B, Guo M, Bai Z H, et al. Experimental research of mercury removal efficiency by activated coke[J]. Clean Coal Technology, 2013, 19(1):48-51.
[23] Scala F, Chirone R, Lancia A. Elemental mercury vapor capture by powdered activation carbon in a fluidized bed reactor[J]. Fuel,2010, 90:2077-2082.
[24] Brunauer S, Deming L, Deming W, et al. On a theory of the van der Waals adsorption of gases[J]. Journal of the American Chemical Society, 1940, 62(7):1723-1732.
[25] Clarkson C, Solano N, Bustin R, et al. Pore structure characterization of North American shale gas reservoirs using USANS/SANS, gas adsorption, and mercury intrusion[J]. Fuel,2013, 103:606-616.
[26]石佩佩.活性炭孔结构和改性对燃煤烟气脱汞的影响及机理研究[D].徐州:中国矿业大学, 2016.Shi P P. The effect of pore structure and modified of activated carbons on mercury removal in flue gas and adsorption mechanism[D]. Xuzhou:China University of Mining and Technology, 2016.
[27]沈彩琴.活性炭纤维表面吸附汞机理的密度泛函理论研究[D].杭州:浙江工业大学, 2015.Shen C Q. Density functional theory study on the mechanism of mercury adsorption by activated carbon fiber[D]. Hangzhou:Zhejiang University of Technology, 2015.
[28] Wang J, Yang J, Liu Z, et al. Gas-phase elemental mercury capture by a V2O5/AC catalyst[J]. Fuel Processing Technology,2010, 91:676–680.
[29]许绿丝.改性处理活性炭纤维吸附氧化脱除SO2/NOx/Hg的研究[D].武汉:华中科技大学.2007.Xu L S. Study on adsorption and oxidation removal of SO2/NOx/Hg at low-temperature by modified activated carbon fiber[D].Wuhan:Huazhong University of Science&Technology, 2007.
[30] Wang Y, Duan Y, Yang L, et al. Experimental study on mercury transformation and removal in coal-fired boiler flue gas[J]. Fuel Processing Technology, 2009, 90:643–651.
[31] Wei Z, Luo Y, Li B. Microwave assisted catalytic removal of elemental mercury from flue gas using Mn/zeolite catalyst[J].Atmospheric Pollution Research, 2015, 6(1):645-651.
[32] Cai J, Shen B, Li Z, et al. Removal of elemental mercury by clays impregnated with KI and KBr[J]. Chemical Engineering Journal,2014, 241:19-27.
[33]薛源,段钰锋,王卉,等.模拟富氧烟气中CO2对活性炭脱汞的实验研究[J].发电设备, 2017, 31(2):99-103.Xue Y, Duan Y F, Wang H, et al. Experimental research on mercury removal by activated carbon with CO2in simulated flue gas from oxy-fuel combustion[J]. Power Equipment, 2017, 31(2):99-103.
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