Mechanisms of Fullerene Synthesis in Flames

这项研究计划的主要重点是定量研究燃料碳在火焰中转化为高度对称、低熵的富勒烯化合物的详细机制。该项目包括三个主要部分：燃烧实验、分子轨道建模和动力学建模。在燃烧实验中，将收集关于富勒烯、富勒烯前体和其他物种的生产和消耗速度以及火焰参数的实验室数据。要测量的火焰特性包括稳定物种、富勒烯、富勒烯中间体和多环芳烃(PAH)的浓度分布，以及通过低压预混平焰的OH自由基和温度；这些测量将在不同的操作压力、冷气速度和进料组成下进行。富勒烯生产中涉及的一些关键中间体由于其瞬变性质，将无法在实验中观察到，因此将使用分子轨道模拟方法来估计它们的热力学性质。然后，这些信息将用于程序的最后一个组成部分、机理开发和动力学建模，以及测量的轮廓，以开发对富勒烯生产中涉及的步骤进行连贯、定量解释的方法，从而确定通过燃烧合成优化富勒烯生产的策略。在过去的几年里，人们对富勒烯(有时也被称为碳的第三种形式，与石墨和钻石并列)产生了相当大的兴趣。这些化合物的潜在用途才刚刚开始确定；这样的定义和随后的实际利用受到缺乏可用材料和其异常高的价格的限制。由于成本和放大的原因，燃烧合成富勒烯提供了一条潜在的有吸引力的路线(替代目前更广泛使用的电弧法生产富勒烯)。因此，了解富勒烯是如何在火焰中形成的，从而优化(在操作参数和设备配置方面)这些材料的燃烧合成，是非常有意义的。

The primary focus of this research program is the quantitative investigation of the detailed mechanisms responsible for conversion of fuel carbon into highly symmetrical, low entropy fullerene compounds in flames. The project includes three main components: combustion experiments, molecular orbital modeling, and kinetic modeling. In the combustion experiments, laboratory data on rates of production and consumption of fullerenes, fullerene precursors, and other species and flame parameters will be collected. The flame properties to be measured include profiles of concentrations of stable species, fullerenes, fullerene intermediates, and polycyclic aromatic hydrocarbons (PAH) along with OH radicals and temperature through a low-pressure premixed flat flame; these measurements will be made at various operating pressures, cold-gas velocities, and feed compositions. Some key intermediates involved in fullerene production will not be experimentally observable due to their transient nature, so their thermodynamic properties will be estimated using molecular orbital modeling methods. This information will then be used in the last component of the program, mechanism development and kinetic modeling, along with the measured profiles, for development of a coherent, quantitative explanation of the steps involved in fullerene production, leading to definition of strategies for optimization of fullerene production via combustion synthesis. Considerable interest in fullerenes (also referred to sometimes as the third form of carbon, alongside graphite and diamond), has developed over the past few years. Potential uses for these compounds are just beginning to be defined; such definition and subsequent actual utilization are limited by a lack of material with which to work and its extraordinarily high price. Combustion synthesis of fullerenes offers a potentially attractive route (alternative to the currently more widely used electric arc method of fullerene production) for cost and scale-up reasons. Thus, development of an understanding of how fullerenes are formed in flames, leading to optimization (in terms of operating parameters and apparatus configuration) of combustion synthesis of these materials, is of major interest.