Influence of hydrogen and oxygen on the initial steps of soot formation

碳纳米颗粒不仅是燃烧产生的污染物，也是重要的工业产品。因此，对它们形成路径的理解和建模具有很高的意义。特别是，氢和氧在潜在的反应中起着重要作用。然而，对其机理细节的系统研究却很少。因此，将在广泛的反应条件和建模下，通过实验的密切相互作用，研究分子氢和键合氢以及分子氧和含氧添加剂对颗粒诱导次数、颗粒形成速率、颗粒体积分数、颗粒形态以及导致烟灰的反应通道的影响。拟议的项目系统地、主题地、有条不紊地扩展了第一个项目期间开展的工作，并建立在第一个项目期间开发和展示的实验能力的基础上。作为前体体系，乙烯、乙炔和苯（有或没有添加氧合物甲醇、正丁醇和呋喃）将作为热解和轻度氧化条件下具有可变C/H比的代表性碳氢化合物类别进行研究。研究表明，含氧燃料和含氧燃料成分的混合物导致烟尘体积分数的降低和更小颗粒的产生的增加。与热解条件相比，在火焰条件下，分子氧和键合氧可以通过增加自由基浓度和初始热释放或通过烟尘前体和烟尘颗粒的氧化反应来影响烟尘的形成。因此，将使用互补技术，如激波管（热解和氧化）、燃烧气体流动反应器（热解）和麦肯纳燃烧器（氧化），研究有和没有添加剂的烟灰形成，这些技术涵盖了广泛的反应条件下的研究。通过这些组合方法，可以研究烟尘形成的所有阶段：激波管与现场、在线和离线技术相结合，提供了明确的反应条件，可以以超高时间分辨率确定气相组成、烟尘体积分数和粒径。燃烧气体流和麦肯纳反应器能够在更长的反应时间内对过程进行调查，并在烟灰形成的不同步骤中提供良好的采样可能性。所有的测量都将与理论研究和建模有关。这个项目是基于一个德国和一个俄罗斯研究小组之间的密切合作。后者将向俄罗斯方面申请额外的资金。

Carbon nanoparticles play an important role as combustion-generated pollutants as well as important industrial products. The understanding and modeling of their formation pathways, therefore, is of high interest. In particular, hydrogen and oxygen play an important role inthe underlying reactions. Systematic studies on the mechanistic details, however, are scarce. Therefore, the influence of molecular and bonded hydrogen as well as the influence of molecular Oxygen was as well as oxygenate additives on particle induction times, particle formation rates, particle volume fractions, particle morphology, as well as on reaction channels leading to soot will be studied using a close interaction of experiments under a wide range of reactionsconditions and modeling. The proposed project systematically extends thematically and methodically the work carried out in the first project period and builds on the experimental capabilities developed and demonstrated in the first period. As precursor systems, ethylene,acetylene, and benzene (with and without the addition of the oxygenates methanol, n-butanol and furans) will be studied as representative hydrocarbon classes with variable C/H ratios underpyrolytic and mildly oxidative conditions. Studies have shown that oxygenated fuels and the admixture of oxygenated fuel components leads to a reduction of the soot volume fraction and an increase in the production of smaller particles. At flame conditions, molecular andbonded oxygen can influence soot formation by increasing radical concentrations and initial heat release or by oxidation reactions of soot precursors and soot particles compared to pyrolysis conditions. Therefore, soot formation with and without additives will be studied byusing complementary techniques such as shock tubes (pyrolytic and oxidative), a burnt-gas flow reactor (pyrolytic) and a McKenna burner (oxidative) that cover studies under a wide range of reaction conditions. Through these combined approaches, all stages of soot formation can be investigated: shock tubes coupled with in situ, online, and offline techniques provide well-defined reaction conditions where the gas-phase composition and soot volume fractions andparticle sizes can be determined with ultra-high time resolution. The burnt-gas flow and McKenna reactors enable the investigation of processes on longer reaction times and provide good sampling possibilities throughout the different steps of the soot formation. Allmeasurements will be related to theoretical studies and modeling. This project is based on a close collaboration between a German and a Russian research group. The latter will apply for additional funding from the Russian side.