煤燃烧过程中砷与氮氧化物的反应机理
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摘要
应用量子化学密度泛函理论B3LYP方法,研究了砷与氮氧化物(N_2O、NO_2和NO)的反应机理。全参数优化了各反应物、中间体、过渡态和产物的几何构型,通过频率分析证实中间体和过渡态的真实性,并通过内禀反应坐标(IRC)计算以进一步确定过渡态。为了得到更精确的能量信息,在B2PLYP水平下计算各结构的单点能,并通过动力学参数深入分析其反应机理。结果表明,砷与三种氮氧化物(N_2O、NO_2和NO)的反应能垒分别为78.45、2.58、155.85 k J/mol。在298-1800 K,各反应速率随温度的升高而增大。由于砷与NO_2的反应能垒较低,其反应速率大于1012cm3/(mol·s),说明该反应容易发生且速率极快。砷与N_2O和NO的反应,在298-900 K,反应速率随温度的升高明显增加;当温度进一步升高,其增加的趋势有所减缓。
The reaction mechanism between arsenic and nitrous oxides( N_2O,NO_2and NO) was investigated by applying density functional theory in quantum chemistry. The geometries of reactants, intermediates,transition states and products for each reaction were optimized. Frequency analysis was applied to verify those geometries,and the authenticity of transition states were confirmed by intrinsic reaction coordinate analysis( IRC). The stationary points of the single point energy were calculated at B2 PLYP level,and the kinetic analysis was conducted to further reveal the reaction mechanism. Results showthat the energy barrier of the reactions between arsenic and nitrous oxides( N_2O,NO_2and NO) is 78.45,2.58 and 155.85 k J/mol,respectively. The reaction rate increases in the range of 298-1800 K and keeps at a high level( >1012cm3/( mol·s)),although the temperature has a tiny impact on the reaction of arsenic with NO_2 as a result of a lowenergy barrier,indicating that the reaction is easy to take place. Furthermore,it is found that the rate of reaction between arsenic and N_2O or NO has a rapid increase at 298-900 K,and then the rate increment becomes less with the further increase of temperature.
The reaction mechanism between arsenic and nitrous oxides( N_2O,NO_2and NO) was investigated by applying density functional theory in quantum chemistry. The geometries of reactants, intermediates,transition states and products for each reaction were optimized. Frequency analysis was applied to verify those geometries,and the authenticity of transition states were confirmed by intrinsic reaction coordinate analysis( IRC). The stationary points of the single point energy were calculated at B2 PLYP level,and the kinetic analysis was conducted to further reveal the reaction mechanism. Results showthat the energy barrier of the reactions between arsenic and nitrous oxides( N_2O,NO_2and NO) is 78.45,2.58 and 155.85 k J/mol,respectively. The reaction rate increases in the range of 298-1800 K and keeps at a high level( >1012cm3/( mol·s)),although the temperature has a tiny impact on the reaction of arsenic with NO_2 as a result of a lowenergy barrier,indicating that the reaction is easy to take place. Furthermore,it is found that the rate of reaction between arsenic and N_2O or NO has a rapid increase at 298-900 K,and then the rate increment becomes less with the further increase of temperature.
引文
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[17] AWUAHA J B,DZADE N Y,TIA R,ADEI E,KWAKYE-AWUAHAD B,CATLOW C R A,DE LEEUW N H. A density functional theory study of arsenic immobilization by the Al(iii)-modified zeolite clinoptilolite[J]. Phys Chem Chem Phys,2016,18(16):11297-11305.
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[25]王鹏乾,王长安,杜勇博,张龙飞,车得福. O2/CO2燃烧条件下NO2还原特性的实验研究[J].西安交通大学学报,2017,51(5):16-22.(WANG Peng-qian,WANG Chang-an,DU Yong-bo,ZHANG Long-fei,CHE De-fu. Experimental investigation on the NO2reduction property under O2/CO2combustion condition[J]. J Xi'an Jiaotong Univ,2017,51(5):16-22.)
[26] JIAO A,ZHANG H,LIU J,SHEN J,JIANG X. The role of CO played in the nitric oxide heterogeneous reduction:A quantum chemistry study[J]. Energy,2017,141:1538-1546.
[2] WANG C,LIU H,ZHANG Y,ZOU C,ANTHONY E J. Review of arsenic behavior during coal combustion:Volatilization,transformation,emission and removal technologies[J]. Prog Energy Combust,2018,68:1-28.
[3] LIU H,PAN W,WANG C,ZHANG Y. Volatilization of arsenic during coal combustion based on isothermal thermogravimetric analysis at 600-1500℃[J]. Energy Fuels,2016,30(8):6790-6798.
[4] LIU H,WANG C,ZOU C,ZHANG Y,WANG J. Simultaneous volatilization characteristics of arsenic and sulfur during isothermal coal combustion[J]. Fuel,2017,203:152-161.
[5] TANG Q,LIU G J,ZHOU C C,SUN R Y. Distribution of trace elements in feed coal and combustion residues from two coal-fired power plants at Huainan,Anhui,China[J]. Fuel,2013,107:315-322.
[6] ZHAO Y,ZHANG J,HUANG W,WANG Z,LI Y,SONG D,ZHAO F,ZHENG C. Arsenic emission during combustion of high arsenic coals from Southw estern Guizhou,China[J]. Energy Convers M anage,2008,49(4):615-624.
[7] ZIELINSKI R A,FOSTER A L,MEEKER G P,BROWNFIELD I K. Mode of occurrence of arsenic in feed coal and its derivative fly ash,Black Warrior Basin,Alabama[J]. Fuel,2007,86(4):560-572.
[8] CONTRERAS M L,AROSTEGUI J M,ARMESTO L. Arsenic interactions during co-combustion processes based on thermodynamic equilibrium calculations[J]. Fuel,2009,88:539-546.
[9]刘迎晖,郑楚光,游小清,郭欣.燃煤过程中易挥发有毒痕量元素的相互作用[J].燃烧科学与技术,2001,7(4):243-247.(LIU Ying-hui,ZHENG Chu-guang,YOU Xiao-qing,GUO Xin. Interaction between most volatile toxic trace elements during coal combustion[J]. J Combust Sci Technol,2001,7(4):243-247.)
[10] URBAN D R,WILCOX J. A theoretical study of properties and reactions involving arsenic and selenium compounds present in coal combustion flue gases[J]. J Phys Chem A,2006,110(17):5847-5852.
[11] MONAHAN-PENDERGAST M,PRZYBYLEK M,LINDBLAD M,WILCOX J. Theoretical predictions of arsenic and selenium species under atmospheric conditions[J]. Atmos Environ,2008,42(10):2349-2357.
[12] URBAN D R,WILCOX J. Theoretical study of the kinetics of the reactions Se+O2→Se+O and As+HCl→AsCl+H[J]. J Phys Chem A,2006,110(28):8797-8801.
[13]雷鸣,黄星智,王春波.典型煤种O2/CO2/H2O气氛下中高温燃烧时NO的生成特性[J].动力工程学报,2017,37(6):432-439.(LEI Ming,HUANG Xing-zhi,WANG Chun-bo. NO emission characteristics of typical coals under O2/CO2/H2O atmosphere at intermediate and high temperatures[J]. J Chin Soc Pow er Eng,2017,37(6):432-439.)
[14]王春波,岳爽,许旭斌,李一鹏. O2/CO2气氛下煤焦恒温燃烧NOx释放特性[J].煤炭学报,2018,43(1):257-264.(WANG Chun-bo,YUE Shuang,XU Xu-bin,LI Yi-peng. NOxrelease of char in constant temperature combustion under O2/CO2atmosphere[J]. J China Coal Soc,2018,43(1):257-264.)
[15]肖海平,周俊虎,刘建忠,孙保民,叶力平.含硫物相对NO还原过程的影响[J].燃料化学学报,2008,36(3):381-384.(XIAO Hai-ping,ZHOU Jun-hu,LIU Jian-zhong,SUN Bao-ming,YE Li-ping. Effect mechanism of existence pattern of sulphur on reduction of NO[J]. J Fuel Chem Technol,2008,36(3):381-384.)
[16]刘晶,郑楚光,邱建荣.燃烧烟气汞反应的量子化学计算方法研究[J].工程热物理学报,2007,28(3):519-522.(LIU Jing,ZHENG Chu-guang,QIU Jian-rong. Study on quantum chemistry calculation method of mercury reactions in combustion flue gas[J]. J Eng Thermophys,2007,28(3):519-522.)
[17] AWUAHA J B,DZADE N Y,TIA R,ADEI E,KWAKYE-AWUAHAD B,CATLOW C R A,DE LEEUW N H. A density functional theory study of arsenic immobilization by the Al(iii)-modified zeolite clinoptilolite[J]. Phys Chem Chem Phys,2016,18(16):11297-11305.
[18] FRISCH M J,TRUCKS G W,SCHLEGEL H B. Gaussian 09,Revision D.01[J]. Gaussian,Inc.,Wallingford,CT,2009.
[19] ZHANG H,LIU J,SHEN J,JIANG X. Thermodynamic and kinetic evaluation of the reaction between NO(nitric oxide)and char(N)(char bound nitrogen)in coal combustion[J]. Energy,2015,82(C):312-321.
[20] SCHRDER B,SEBALD P,STEIN C,WESER O,BOTSCHWINA P. Challenging high-level ab initio rovibrational spectroscopy:The nitrous oxide molecule[J]. Z Phys Chem,2015,229(10/12):1663-1690.
[21] BORISENKO K B,KOLONITS M,ROZSONDAI B,HARGITTAI I. Electron diffraction study of the nitrogen dioxide molecular structure at294,480,and 691 K[J]. J M ol Struct,1997,413-414:121-131.
[22] MARSDEN C J,SMITH B J. AB initio force constants:A cautionary tale concerning nitrogen oxides[J]. J Mol Struct:Theochem,1989,187:337-357.
[23] EVENSON K M,WELLS J S,RADFORD H E. Infrared resonance of OH with the H2O laser:A galactic maser pump?[J]. Phys Rev Lett,1970,25(4):199-202.
[24] MIZUSHIMA M. Molecular parameters of OH free radical[J]. Phys Rev A,1972,5(1):143-157.
[25]王鹏乾,王长安,杜勇博,张龙飞,车得福. O2/CO2燃烧条件下NO2还原特性的实验研究[J].西安交通大学学报,2017,51(5):16-22.(WANG Peng-qian,WANG Chang-an,DU Yong-bo,ZHANG Long-fei,CHE De-fu. Experimental investigation on the NO2reduction property under O2/CO2combustion condition[J]. J Xi'an Jiaotong Univ,2017,51(5):16-22.)
[26] JIAO A,ZHANG H,LIU J,SHEN J,JIANG X. The role of CO played in the nitric oxide heterogeneous reduction:A quantum chemistry study[J]. Energy,2017,141:1538-1546.