O2对燃煤烟气中As2O3均相反应生成途径影响研究  

Influence of O2 on the formation of As2O3 by homogeneous reaction with As and AsO in the coal-fired flue gas

作　　者：闫傲 张月[1] 王春波[1] 白涛 赵斌 YAN Ao;ZHANG Yue;WANG Chun-bo;BAI Tao;ZHAO Bin(School of Energy,Power Engineering and Mechanical Engineering,North China Electric Power University,Baoding 071003,China;Department of Power Engineering,Shanxi University,Taiyuan 030013,China)

机构地区：[1]华北电力大学能源动力与机械工程学院,河北保定071003 [2]山西大学动力工程系,山西太原030013

出　　处：《燃料化学学报》2020年第1期11-17,I0001,共8页Journal of Fuel Chemistry and Technology

基　　金：国家自然科学基金(51906070);山西省重点研发计划(201803D31027);中央高校基本科研业务(2018ZD03,2019MS093);高效清洁协同利用劣质煤发电的关键基础问题研究(LLEUTS-201702)资助~~

摘　　要：应用量子化学密度泛函理论研究了燃煤烟气中As和AsO与O 2均相生成As 2O 3的反应机理。首先计算确定了各反应物、中间体、过渡态和产物的结构和能量,然后运用热力学和动力学方法对As 2O 3均相生成过程进行分析。结果表明,由As和AsO与O 2均相生成As 2O 3的最大反应能垒分别为32.9和157.2 kJ/mol,在烟气中由As转化为As 2O 3更为容易进行。在500-1900 K下,各反应的正逆反应速率常数均随温度的提高而增大,但不同反应过程受温度影响的程度不同。As与O 2反应生成AsO和AsO 2的两个反应过程的平衡常数在所研究的温度范围内均大于105,能完全反应,可以认为是单向反应。AsO与O 2反应生成AsO 2的过程平衡常数在所研究的温度范围内小于105,反应不完全,转化率低。AsO与AsO 2生成As 2O 3(D3H)构型的平衡常数极低,反应难以进行,而生成As 2O 3(GAUCHE)构型反应能垒低,可自发进行。The reaction mechanism for the formation of As 2O 3 by the homogeneous reaction of O 2 with As and AsO in the coal-fired flue gas was investigated by the quantum chemical density functional theory.The structure and energy of each reactant,intermediate,transition state and product were determined and the thermodynamic and kinetic analysis was carried out to explore the reaction mechanism.The results show that the maximum reaction energy barriers for the formation of As 2O 3 from As and AsO are 32.9 and 157.2 kJ/mol,respectively.The forward and reverse reaction coefficients all increase with an increase of the reaction temperature in the range of 500-1900 K,although the influence extent of temperature varies with different reactions.For the oxidation of As,the equilibrium constants of two reactions are always greater than 105,indicating that the oxidation of As can be carried out completely and regarded as an irreversible reaction.In contrast,for the oxidation of AsO,the equilibrium constants are always less than 105,indicating that the oxidation of AsO is an incomplete reaction.The equilibrium constant of the As 2O 3(D3H)configuration is extremely low;however,the formation of the As 2O 3(GAUCHE)configuration is a spontaneous process.

关 键 词：烟气砷 煤燃烧 均相氧化 反应机理 热力学 动力学 

分 类 号：X511[环境科学与工程—环境工程]