【摘要】 基于密度泛函理论和过渡态原理,在M06-2X/6-311G(d)水平上研究了吡咯氮和两种不同结构吡啶氮的Zigzag煤焦模型热解过程含氮化合物迁移释放NOx前驱物的机理,其中"吡啶氮1模型"指的是N原子序号为28的模型,"吡啶氮2模型"指的是N原子序号为29的模型,所涉及的基元反应均寻找到了过渡态,并得到每一步反应的活化能.通过各反应的吉布斯自由能对比分析,找出容易进行的反应路径.结果表明,吡咯氮模型热解生成HCN的过程更易进行;吡啶氮1模型C—N键断开,然后C—C键重新成键形成中间体IM2的过程所需克服能垒为195.8 kJ/mol,小于其他两条路径所对应的能垒299.7 kJ/mol、296.6 kJ/mol,故此过程更易发生反应;吡啶氮2模型经过渡态TS1克服能垒370.2 kJ/mol,小于吡啶氮1模型第一步反应能垒,说明吡啶氮2模型热解路径更容易发生.更多还原

【Abstract】 Based on the density functional theory(DFT) and transition state theory,the mechanism of nitrogencontaining compounds migration and release of NOx precursors during the pyrolysis of zigzag coal char with pyrrole nitrogen and pyridine nitrogen with two different structures was studied at the M06-2 X/6-311 G(d) level. “Pyridine Nitrogen 1 Model” refers to the model with N atom number of 28,and “Pyridine Nitrogen 2 Model” refers to the model with N atom number of 29. The transition state for the mechanism involved in the elementary reaction is found,and the activation energy of each reaction step is obtained. Through the comparative analysis of Gibbs free energy of each reaction,the easy reaction path is found. The results show that the HCN is easier to be formed in the pyrrole nitrogen model;the C—N bond of Pyrrole Nitrogen 1 Model is broken,and then the C—C bond is rebonded to form intermediate IM2. The energy barrier to overcome is 195.8 kJ/mol,smaller than that in the other two cases,which are 299.7 kJ/mol and 296.6 kJ/mol,respectively,so reactions are easier to take place in this process;the Pyridine Nitrogen 2 Model overcomes the energy barrier 370.2 kJ/mol through the transition state TS1,which is smaller than the first reaction energy barrier of the Pyridine Nitrogen 1 Model,indicating that the Pyridine Nitrogen 2 Model pyrolysis pathway is more likely to occur.更多还原