New Condensed-Phase Approaches for Soot Formation, Aging, and Burnout

这个关于燃烧产生的烟尘的项目利用P.I.S实验室为其他碳材料开发的概念和工具，专注于火焰中存在的复杂的碳质凝聚相。这些新工具包括直接测量高温和短时间下的动态活性中心损失，使用分布式活化能公式来了解反应性损失(老化)和氧化并对其进行建模，以及使用原子对势模拟来研究更高级别的多环芳烃(PAH)相互作用。正在将新的分布位置动力学模型应用于烟尘氧化，以解决表观幂定律动力学领域中长期存在的悖论，并统一高温和低温下的动力学数据库。一个关键的建模概念是将凝聚相描述为聚合物玻璃相而不是固体或液体，而是具有可变纳米结构迁移率的聚合物玻璃相，它控制着从团聚到团聚的转变。该项目包括一项新颖的实验任务，使用由P.I.S实验室合成的新型富芳烃碳/氢纳米颗粒作为火焰中年轻碳烟颗粒的第一个物理化学模型。燃烧产生的烟尘是一种可呼吸的超细颗粒物质，含有已知的致癌物质和诱变剂，因此是一种关键的大气污染物。减少柴油发动机的烟尘排放对美国汽车制造商来说是一个特别具有挑战性的目标。减少车辆和炉子的烟尘排放的努力侧重于火焰化学和结构的控制，或者是颗粒的捕获和随后的低温氧化。对于这两种类型的烟尘控制措施的设计，需要更好地了解烟尘颗粒本身的结构、性质和反应性，从它们在火焰早期阶段作为可识别的浓缩有机物被首次检测到，到它们最终作为完全碳化和部分氧化的纳米颗粒的分形集合体释放。该项目应用碳科学中最现代的方法来理解和描述煤烟形成、演化和燃烧的各个阶段。

This project on combustion-generated soot focuses on the complex carbonaceous condensed phases present in flames using concepts and tools developed for other carbon materials in the P.I.'s laboratory. The new tools include direct measurement of dynamic active-site loss at high temperatures and short times, the use of distributed activation energy formulations to understand and model both reactivity loss (aging) and oxidation, and the use of atomic pair-potential simulations to investigate higher polycyclic aromatic hydrocarbon (PAH) interactions. New distributed-site kinetic models are being applied to soot oxidation to resolve the long-standing paradox in the field of apparent power-law kinetics and to unify the kinetic database at high and low temperatures. A key modeling concept is the description of the condensed phases not as solids or liquids, but as polymeric glassy phases with variable nanostructural mobility that governs the transition from coalescence to agglomeration. The project includes a novel experimental task employing new aromatic-rich C/H nanoparticles synthesized in the P.I.'s laboratory as the first physicochemical models for young soot particles in flames. Combustion-generated soot is a respirable, ultrafine particulate material that carries known carcinogens and mutagens and is thus a key atmospheric pollutant. The reduction of soot emissions from diesel engines is a particularly challenging goal for U.S. vehicle manufacturers. Attempts to reduce soot emission from vehicles and furnaces focus on control of the flame chemistry and structure or on capture of particulates and subsequent low-temperature oxidation. For the design of both types of soot-control measures, a better understanding is needed of the structure, properties, and reactivity of the soot particles themselves from their first detection as recognizable condensed organic matter in the early stages of flames to their final release as fractal aggregates of fully carbonized and partially oxidized nanoparticles. This project applies the most modern approaches in carbon science to the understanding and characterization of the various stages of soot formation, evolution, and burnout.