含氮焦炭异相还原NO反应机理的密度泛函理论研究  

Density functional theoretical study of heterogeneous reduction mechanism of NO on nitrogen-containing char surface

作　　者：张秀霞[1] 周志军[1] 周俊虎[1] 姜树栋[2] 刘建忠[1] 岑可法[1] 

机构地区：[1]浙江大学能源清洁利用国家重点实验室,浙江杭州310027 [2]中国电力工程顾问集团华北电力设计院工程有限公司,北京100120

出　　处：《化工学报》2011年第4期1048-1054,共7页CIESC Journal

基　　金：国家高技术研究发展计划项目(2008AA05Z304)~~

摘　　要：选用合理简化的含氮焦炭模型,使用密度泛函理论对含氮焦炭异相还原NO释放出N2的反应机理在分子水平上进行了研究。使用B3LYP/6-31G(d)方法优化得到了含氮焦炭模型、产物、中间体和过渡态的几何构型。在相同水平上计算得到了优化所得结构的单点能并进行了零点能校正,从而得到整个反应的势能面及各中间反应的活化能和反应热。NO吸附在含氮焦炭表面后N、O原子倾向于分离,吸附反应释放出98.1 kJ.mol-1的热量。吸附产物可分别经历最高能垒为87.7 kJ.mol-1和253 kJ.mol-1的路径释放出N2和CO。N2和CO由吸附产物中释放后,残留在焦炭表面的产物P1、P2可进一步分别释放出CO和N2。NO在含氮焦炭表面异相还原释放出N2和CO的整个反应共释放出约49.0 kJ.mol-1的热量。Heterogeneous reduction mechanism of NO on the surface of nitrogen-containing char was investigated at molecular level using density functional theory.The char model,products,stable intermediates and transition states were optimized at B3LYP/6-31G（d）level.The whole potential energy surface was obtained by calculating single point energies with zero point energy corrections for geometries.The results are as follows.The first step of the heterogeneous reduction is NO adsorption on the surface of nitrogen-containing char,releasing heat energy of 98.1 kJ·mol-1.N and O atoms tend to separate after chemisorption.N2 is desorbed with the production of P1 by a series of rearrangement reactions,in which the highest energy barrier is 87.7 kJ·mol-1.The highest energy barrier for CO desorption is 253 kJ·mol-1 and P2 is left on the char surface.Desorption of N2 and CO from reactions between NO and nitrogen-containing char are 187 kJ·mol-1 exothermic and 302 kJ·mol-1 endothermic,respectively.CO is further released from P1 with 138 kJ·mol-1 endothermic,and N2 is desorbed from P2 with 352 kJ·mol-1 released.About 49 kJ·mol-1 is released throughout the overall heterogeneous reduction of NO on the surface of nitrogen-containing char.

关 键 词：一氧化氮 含氮焦炭 异相还原 密度泛函理论 

分 类 号：TK16[动力工程及工程热物理—热能工程]