茶梗基生物炭吸附气态单质汞的热力学分析
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摘要
燃煤电厂作为单质汞最大的排放源,其排放标准也日趋严格。新的火电厂排放标准已于2012年1月1日起正式实施,其中规定汞及其化合物的排放限值为0.03mg/m~3。以云南废弃普洱茶梗为碳源,利用超声等体积浸渍法制备了质量分数分别为4%CeO_2-4%CuO(CC)和4%CeO_2-4%MnO_2(CM)生物炭。在100～300℃范围内,模拟固定床选择性催化还原法(SCR)条件下进行单质汞和NO的联合去除实验。为了探究改性茶梗生物炭吸附气态单质汞的热力学特征和吸附机理,利用热力学方程对数据进行拟合,结果表明随着温度的逐步升高,化学反应发生机率降低,化学吸附随之减少。
Coal-fired power plants are the largest emission source of elemental mercury and the emission standards are also becoming stricter.The new coal-fired power plant emission standard has been official implemented since 1 January,2012,the emission limit of elemental mercury and its compounds in the standard is 0.03 mg/m~3.The waste Pu'er tea stem from Chinese Yunnan province was utilized as a carbon source to prepare biochar which were modified by 4% CeO_2-4% CuO and 4% CeO_2-4% MnO_2 by ultrasound assisted incipient impregnation.The simultaneous removal experiment of NO and Hg~0 by biochar which were donated as CC and CM respectively were investigated in a fixed bed system with simulated selective catalytic reduction(SCR)flue gas at 100～300℃.The data was fitted by the thermodynamic equationin order to explore the thermodynamic characteristic and the adsorption mechanism.The results showed that with the increase of temperature,the probability of chemical reaction reduced and then the chemical adsorption decreased.
Coal-fired power plants are the largest emission source of elemental mercury and the emission standards are also becoming stricter.The new coal-fired power plant emission standard has been official implemented since 1 January,2012,the emission limit of elemental mercury and its compounds in the standard is 0.03 mg/m~3.The waste Pu'er tea stem from Chinese Yunnan province was utilized as a carbon source to prepare biochar which were modified by 4% CeO_2-4% CuO and 4% CeO_2-4% MnO_2 by ultrasound assisted incipient impregnation.The simultaneous removal experiment of NO and Hg~0 by biochar which were donated as CC and CM respectively were investigated in a fixed bed system with simulated selective catalytic reduction(SCR)flue gas at 100～300℃.The data was fitted by the thermodynamic equationin order to explore the thermodynamic characteristic and the adsorption mechanism.The results showed that with the increase of temperature,the probability of chemical reaction reduced and then the chemical adsorption decreased.
引文
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[3]Presto A A,And E J G,Karash A.Further investigation of the impact of sulfur oxides on mercury capture by activated carbon[J].Industrial&Engineering Chemistry Research,2007,46(24):8273-8276.
[4]Granite E J,Freeman M C,Hargis R A,et al.The thief process for mercury removal from flue gas[J].Journal of Environmental Management,2007,84(4):628-634.
[5]Herbert G M J,Krishnan A U.Quantifying environmental performance of biomass energy[J].Renewable&Sustainable Energy Reviews,2016,59(2):292-308.
[6]Klasson K T,Lima I M,Jr L L B,et al.Feasibility of mercury removal from simulated flue gas by activated chars made from poultry manures[J].Journal of Environmental Management,2010,91(12):2466-2470.
[7]Li G,Shen B,Yi W,et al.Comparative study of element mercury removal by three bio-chars from various solid wastes[J].Fuel,2015,145(4):189-195.
[8]Zhu C,Duan Y,Wu C Y,et al.Mercury removal and synergistic capture of SO2/NO by ammonium halides modified rice husk char[J].Fuel,2016,172(4):160-169.
[9]Lopez-Anton M A,Ferrera-Lorenzo N,Fuente E,et al.Impact of oxy-fuel combustion gases on mercury retention in activated carbons from a macroalgae waste:effect of water[J].Chemosphere,2015,125(1):191-197.
[10]Klasson K T,Lima I M,Boihem L L.Poultry manure as raw material for mercury adsorbents in gas applications[J].Journal of Applied Poultry Research,2009,18(3):562-569.
[11]Skodras G,Diamantopoulou I,Zabaniotou A,et al.Enhanced mercury adsorption in activated carbons from biomass materials and waste tires[J].Fuel Processing Technology,2007,88(8):749-758.
[12]Mejía-Centeno I,Castillo S,Camposeco R,et al.SCR of NOx by NH3over model catalysts:the kinetic data-linear free energy relation[J].Catalysis Communications,2013,31(2):11-15.
[13]Liu C,Shi J W,Gao C,et al.Manganese oxide-based catalysts for low-temperature selective catalytic reduction of NOx with NH3:a review[J].Applied Catalysis A:General,2016,522(8):54-69.
[14]Arvelakis S,Crocker C,Folkedahl B,et al.Activated carbon from biomass for mercury capture:effect of the leaching pretreatment on the capture efficiency[J].Energy Fuels,2010,24(3):4445-4453.
[15]Li G,Wang S,Wu Q,et al.Mechanism identification of temperature influence on mercury adsorption capacity of different halides modified bio-chars[J].Chemical Engineering Journal,2017,315(1):251-261.
[16]Li G,Shen B,Li F,et al.Elemental mercury removal using biocharpyrolyzed from municipal solid waste[J].Fuel Processing Technology,2015,133(1):43-50.