等离子体辅助甲烷燃烧的主要反应路径/通道

摘要

Experiment and simulation were carried out in this paper to study the main elementary reactions of plasma assisted methane combustion.In the experiment,the emission spectra of different parts of plasma assisted methane com-bustion flame were measured,and the important species involved in the process were obtained.In the simulation,based on the density functional theory,several important elementary reactions in methane combustion,including O2+H→OH+O,CH4+OH/O/H→CH3+H2O/OH/H2,CH3+O→CH2O+H,and CH2O+OH/O/H→CO+H2O/(H+H2O)/(H+H2), were studied,and the possible reaction paths/channels were found and analyzed at the B3LYP/6-311++G** level.On this basis,the change of each reaction path/channel in discharge was compared and analyzed,and the conclusions were as follows:The mechanism of plasma assisted methane combustion should be improved based on the mechanism of meth-ane combustion by adding *2HO (v),O(1D)and CH4(v)and other excited state components and through splitting or merging some elementary reactions,and then the activation energies of each reaction were recalculated.Those excited state species promoted the reaction potential energy surface,reduced the activation energy and accelerated the reaction process.In the reaction of CH2O and O/OH/H,HCO could be directly decomposed in discharge,thus reducing the consumption of H atoms by HCO and releasing a H atom,which was beneficial to the combustion process.%通过实验和模拟的方法,对等离子体辅助甲烷燃烧主要基元反应进行了研究.实验测量了等离子体辅助甲烷燃烧火焰不同位置的发射光谱图,得到了参与该过程的重要组分;模拟过程中,基于密度泛函理论,研究了甲烷燃烧反应中 O2+H→OH+O、CH4+OH/O/H→CH3+H2O/OH/H2、CH3+O→CH2O+H、CH2O+OH/O/H→CO+H2O/(H+H2O)/(H+H2)等几个重要基元反应,在 B3LYP/6-311++G**水平找到了各反应可能的反应路径/通道,并进行分析.在此基础上,对比分析了放电等离子体作用下各反应路径/通道的变化,结果表明,在研究等离子体辅助甲烷燃烧机理时,应基于甲烷燃烧机理进行完善,通过加入 *2HO (v)、O(1D)、CH4(v)等激发态组分,并对一些基元反应进行拆分或合并,重新计算各反应活化能;生成的激发态组分会提升反应势能面,降低活化能,加速反应进程;在CH2O与O/OH/H的反应中,放电等离子体可将生成的HCO直接分解,降低了HCO对H原子的消耗,同时还会释放一个H原子,有利于燃烧反应的进行.