【作者】 田振玉；

【导师】 齐飞；

【作者基本信息】 中国科学技术大学 ， 同步辐射及应用， 2008， 博士

【摘要】 本论文利用真空紫外单光了电离和分子束质谱技术系统地研究了不同含氮体系化合物的火焰，其中包括掺杂体系（甲烷掺杂氨气）、硝基类（硝基甲烷）、胺类（正／异丙胺）及杂环体系（吡咯和吡啶）。本论文共分为六章，主要集中于不同含氮体系火焰中燃烧中间体的定性和定量分析；讨论了NO_X在不同含氮体系火焰中的形成路径；并对掺杂体系和硝基甲烷火焰进行了动力学模拟。在第一章中，我们首先简述了燃烧研究的发展和应用，并说明了含氮化合物燃烧研究的重要性和必要性，接着回顾了NO_X的形成机理，概述了含氮体系的分类以及研究概况，然后介绍了燃烧研究的一些基本概念，最后阐明了本文研究的目标、方法和意义。在第二章中，我们详细介绍了理论方法、燃烧实验装置、实验过程以及数据处理过程。其中描述了本论文所用的国家同步辐射实验室真空紫外光束线和燃烧实验站的基本构造，并对分子束和反射式飞行时间质谱的结构和原理作了简单的描述。本论文采用的分子束质谱结合可调谐同步辐射真空紫外单光子电离技术与其他燃烧诊断技术相比具有如下优势：信噪比高、软电离以及波长在宽范围内连续可调，这使得近阈值电离成为可能，通过扫描光电离效率谱，可以区分异构体；可以检测到活性中间体如自由基等。第二章研究了11个低压预混氨气掺杂甲烷／氧气／氩气火焰。通过测量质谱和光电离效率谱，对燃烧中间体和产物进行了鉴别。通过计算得到了火焰物种的摩尔分数。用Chemkin 2．0 Premix模块和MB、GRI 3．0以及本文机理对掺杂比（[NH₃]／[CH₄]）R=0．5火焰进行了理论模拟。实验结果表明：随着掺杂比的增加，反应区变宽；在同一炉子位置H₂O，NO和N₂的摩尔分数呈上升趋势，而H₂，CO，CO₂和NO₂则呈相反趋势。计算结果表明MB和GRI 3．0机理过低地预测了NO的形成量。用本文机理模拟的产物以及中间体的浓度曲线与实验值符合得比较好。第四章研究了燃烧当量为1．39的低压预混硝基甲烷／氧气／氩气火焰。通过扫描光子能量和燃烧炉位置，对火焰中所有物种，包括Ar、反应物、中间体以及产物作了定性和定量分析。实验结果表明：N₂和NO是主要的含氮产物，峰值摩尔分数大于1．0×10^-3的含氮中间体有HCN，HNO，CH₃CN，HNCO／HCNO，H₂C=NH=O和HONO。另外，根据本次工作中观察到的一些新的燃烧中间体，我们提出了一个由68个物种307个反应组成的动力学模型，模拟的结果与实验结果具有很好的一致性。第五章研究了燃烧当量均为1．70的正丙胺和异丙胺火焰。实验共探测和鉴别了约50种燃烧物种。通过选择光子能量扫描燃烧炉位置，得到了绝大多数物种的摩尔分数曲线。正丙胺和异丙胺中的N燃烧后主要转化为HCN和N₂。由于二者互为同分异构体，组成元素相同，燃烧时生成了很多相同的中间体，如甲基自由基、氨气、乙炔、乙烯、乙基自由基、胺甲烯、一氧化氮、炔丙基自由基、丙炔、丙二烯、1，3-丁二炔、乙烯基乙炔、2-丁烯和1，3-环戊二烯等。但二者结构的不同使得它们在燃烧过程中也生成了很多不同的中间体，如亚胺甲烯、乙烯醇／乙醛、甲酰胺、2-丙烯-1-亚胺／环丙基亚胺、2-丙烯基胺、正丁胺和甲苯等只出现在正丙胺火焰中，而甲胺、乙烯酮、1-丁烯、1-甲基乙烯基胺、戊基自由基／3-戊基自由基、1，3-环己二烯、环己烯等只在异丙胺火焰中出现。讨论了正丙胺和异丙胺火焰中NO_X的形成和N的转化路径。最后一章研究了吡咯和吡啶分别在贫燃和富燃条件下的四个火焰。通过扫描光电离质谱和光电离效率谱，鉴别了这些火焰中的燃烧中间体。通过扫描燃烧炉位置，得到了选定光子能量下主要物种以及中间体的离子信号强度随燃烧炉位置的变化曲线，进而推导出了这些物种的摩尔分数曲线。在吡咯火焰中，N₂，NO和NO₂是主要的含氮产物，最富集的几个含氮中间体为HCN，HNCO和C₃H₃N。此外，我们对吡咯燃烧的反应路径进行了分析，并着重讨论了几个主要含氮中间体的消耗路径。实验结果表明：1，3-丁二炔，1，3-丁二烯，1，3-己二烯，2-甲基呋喃，氮宾，苯腈，4-甲苯基自由基，2-乙烯基吡啶和中氮茚／间甲苯腈等物种只出现在富燃火焰中；而甲酰胺，甲酸，1，2-丁二烯，异丁基自由基，2-戊炔-4-酮，1，2，3，6-四氢吡啶，2，4-二甲基（?）唑，环己胺和N-苯基胺甲烯等物种只在贫燃火焰中形成。而且，富燃火焰中的C₂H₂和HCN的浓度比贫燃中的相应值要高，而HNCO则相反。HCN的可能消耗反应有C₂H₂加成、氢脱除以及异构化。HNCO主要参与自由基加成和消去反应，丰要生成产物为NO，CO和CO₂。C₃H₃N则主要转化为C₂H₂和HNCO。在吡啶火焰中，实验鉴别了约60种质量数范围从15到156的含氮、含氧和碳氢化合物燃烧中间体的结构。结果表明吡啶在燃烧过程N主要是通过如下路径转化的：（1）N转化过程主要以脱氢和加氧反应开始，形成的初始产物为氧化吡啶、2-吡啶醇和邻位C₅H₄N自由基，然后这些物种经过一系列的反应生成最终含氮产物NO、NO₂和N₂；（2）吡啶的初始含氮中间体与小的不饱和碳氢化合物反应形成双环物种，包括中氮茚（C₈H₇N），喹啉（C₉H₇N）和1，8-二氮萘啶（C₈H₆N₂）等。此外，实验结果证实了在吡啶火焰中很难形成大质量数（三环及三环以上）的芳香化合物。这些结果将有助于更加深入地理解含氮燃料的燃烧过程。更多还原

【Abstract】 This dissertation is to investigate the nitrogen-containing compounds flames, including doped systems （NH₃-doped CH₄ flames）, nitro compounds （nitromethane）, amines （propylamine and isopropylamine） and heterocycles （pyrrole and pyridine）, with vacuum ultraviolet single-photon ionization combined with molecular beam mass spectrometry techniques. This dissertation consists of six chapters. It mainly focuses on the identification and quantification of the combustion intermediates formed in the different nitrogen-containing compounds flames. Moreover, it discusses the formation pathways of NO_X in different nitrogen-containing systems and models the doped systems and nitromethane flames.In Chapter 1, the progress and application of combustion study are briefly described. The purpose and necessity for the combustion study of nitrogen-containing compounds are explained. The formation mechanisms of NO_X are reviewed. The classification and research survey of nitrogen-containing systems are summarized. Some basic concepts are introduced. Moreover, the target, method and importance of the present research are illustrated.In Chapter 2, the theoretical methods, experimental setup and procedure of the combustion studies are demonstrated in detail. A detailed description of the data dealing processes is presented. Especially, the structure of the vacuum ultraviolet （VUV） beamline and combustion endstation, combined with the principles of molecular beam and reflectron mass spectrometry are presented. The powerful combination of molecular beam mass spectrometry （MBMS） with photoionization by tunable VUV synchrotron offers significant improvements over previous combustion diagnostics, including superior signal-to-noise, soft ionization, and tunability in a wide range. These advantages make threshold ionization possible, which can be used to identify isomers and detect active intermediates such as free radicals. In Chapter 3, 11 low-pressure premixed ammonia doped methane/oxygen/argon flames are studied. By measuring the photoionization efficiency （PIE） spectra, combustion intermediates and products are identified. The mole fractions of the flame species are deduced by scanning the burner positions at some selective photon energies. The flame with doped ratio [NH₃]/[CH₄] （R） = 0.5 are modeled with Chemkin 2.0 Premixed codes by using Miller-Bowman （MB）, GRI 3.0-Mech （GRI 3.0） and modified mechanisms in this work. The experimental results indicate that the reaction zone is widened with R increasing; the mole fraction profiles of H₂O, NO and N₂ ascend while those profiles of H₂, CO, CO₂ and NO₂ have reverse tendencies. The computational result shows that the MB and GRI 3.0 mechanisms tend to underpredict NO production. The modeling concentration profiles obtained by the present mechanism are in reasonable agreement with the experimental result.In Chapter 4, a low-pressure premixed nitromethane/oxygen/argon flame with equilavence ratio of 1.39 is studied. By scanning photon energies and burner positions, flame species, including Ar, reactants, intermediates and products are measured qulatively and quantitatively. N₂ and NO are found to be the major nitrogenous products, while HCN, HNO, CH₃CN, HNCO/HCNO, H₂C=NH=O, and HONO are nitrogenous intermediates with maximum mole fractions higher than 1.0×10^-3. Moreover, considering the new species identified in this work, a detailed kinetic model comprising 68 species and 307 reactions has been developed. The predictions by the present mechanism are in reasonable agreement with the experimental result.In Chapter 5, propylamine （PA） and isopropylamine （IPA） flames with the same equilavence ratio （φ=1.70） are investigated. About 50 flame species are detected and identified. By scanning burner position at some selective photon energies, mole fractioins of most of the species are deduced. Under flame conditions, N in PA and IPA is mainly converted to HCN and N₂. Since propylamine and isopropylamine have the same chemical composition, a lot of the combustion intermediates are the same, such as methyl radical, ammonia, acetylene, ethylene, ethyl radical, methanimine, nitric oxide, propargyl radical, propyne, allene, 1,3-butadiyne, vinylacetylene, 2-butene, 1,3-cyclopentadiene etc. However, the chemical structures of PA and IPA are different, which leads to some difference of the intermediates pool. Methylene amidogen, ethenol/acetaldehyde, formamide, 2-pyopen-1-imine/cyclopropanimine, 2-propen-1-amine, 1-butanamine and toluene are formed only in the PA flame, while methylamine, ketene, 1-butene, 1-methylethenylamine, 1-pentyl radical/3-pentyl radical, 1,3-cyclohexadiene and cyclohexene are observed only in the IPA flame. Moreover, NO_X formation combined with N conversion pathways in the PA and IPA flames are discussed.In the last Chapter, four pyrrole and pyridine flames are studied under fuel lean and rich conditions. By scanning photoionization mass spectra and photoionization efficiency spectra, combustion intermediates in the flames are identified. By scanning burner positions at some selective photon energies, mole fraction profiles of major species and intermediates are obtained.In the pyrrole flames, N₂, NO and NO₂ are the major nitrogenous products while hydrogen cyanide, isocyanic acid and 2-propenenitrile are the most important nitrogen-containing intermediates. Reaction pathways involving the major species are proposed. The experimental results indicate that 1,3-butadiyne, 1,3-butadiene, 1,3-hexadiene, 2-methylfuran, phenylnitrene, benzonitrile, 4-methylbenzyl radical, 2-vinylpyridine, indolizine and m-tolunitrile exist only in the rich flame, while formamide, formic acid, 1,2-butadiene, isobutyl radical, 2-pentyn-4-one, 1,2,3,6-tetrahydropyridine, 2,4-dimethyloxazole, cyclohexanamine and N-phenyl methanimine are detected only in the lean flame. Moreover, concentrations of C₂H₂ and HCN in the rich flame are higher than that in the lean flame whereas HNCO is facile to be formed in the lean flame. The possible consumption reactions of HCN are acetylene-addition to the triple bond, hydrogen abstraction by OH, reaction with oxygen atom and isomerization to HNC. HNCO participates in radical addition and abstraction reactions and is mainly converted to NO, CO and CO₂. And the main products from C₃H₃N are C₂H₂ and HNCO. In the pyridine flames, about 60 flame species ranged from 15 to 156, including nitrogenous, oxygenated and hydrocarbon intermediates are identified. Under the flame conditions, N in pyridine is mainly converted via the following pathways: （1） N conversion is initiated with H abstraction and O addition, forming the primary products pyriding oxide, 2-pyridinol and o-C₅H₄N radical, and then these species finally convert to NO, NO₂ and N₂ after series of reactions; （2） two ring species, including indolizing, quinoline and 1,8-naphthyridine, are formed through the reactions of the primary nitrogenous intermediates and small unsaturated hydrocarbons. In addition, the results indicate that it is difficult to produce a tricyclic or larger species in pyridine flames. The experimental observations are useful for further insight into the combustion chemistry of nitrogen-containing fuels.更多还原