The Formation of Combustion Generated Particles: Using In situ Electron Microscopy to Advance our Understanding and Modeling

燃烧产生的颗粒的形成：利用原位电子显微镜促进我们的理解和建模

• 批准号: RGPIN-2020-06136
• 负责人: Thomson, Murray
• 金额: $ 5.54万
• 依托单位: University of Toronto
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2021
• 资助国家: 加拿大
• 起止时间: 2021-01-01 至 2022-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=740711
• 关键词: Formation; Combustion; Generated; Particles; Using

The formation of combustion-derived nanoparticles is important both as a pollutant such as soot and as a material such as carbon black. Recently I have been able to translate my soot expertise to the material synthesis of carbon black. Carbon black (CB), which is essentially a pure form of soot, has a wide range of applications such as in composites, rubbers, plastics, batteries and paints. The aggregate and internal structure of these nanoparticles is important as they determine the health effects and material properties of soot and carbon black, respectively. The long-term goals of this research program are to develop a fundamental understanding of the combustion-generated growth of carbon particles, to use this understanding to develop detailed predictive models and to apply these models to solve practical problems such as predicting particle size and aggregate structure of carbon black and soot. This proposal will be based on our deep experience in soot formation and our recent success in pioneering the use of an Environmental Transmission Electron Microscope (ETEM) to visualize, in real time, nanoscale carbon particles, with a sub-nanometer resolution, as they oxidize due to an introduced gas and/or as their internal structure transforms due to heating; this work recently won two awards. This proposal will pioneer the use of the ETEM to explore the effect of particle growth on bridging and enveloping the primary particles. Current models ignore this effect, overestimating the surface area by assuming point contact of growing particles. The particles placed into the ETEM will be obtained from our flame or from carbon black producers. The ETEM can image individual aggregates of nanoparticles as they react to introduced hydrocarbon gases in the electron microscope. It is believed that no one has used an ETEM to study the growth of soot or carbon black particles. Also, a TOF-SIMS (Time of flight secondary ion mass spectrometry) will provide a new method to identify the molecular structure of the species reacting or adsorbed on the soot surface. The short term objectives are we will: (1) use ETEM to look at how particle growth processes both affect and are affected by the particle aggregate and molecular structure; (2) measure the molecular structure of the surface of particles sampled from our coflow flame or our ETEM reactor using a TOF-SIMS; (3) improve our particle formation models by incorporating the findings of the first and second objectives. The models will better predict the particle's growth and surface properties; they will then be further validated with experimental data from flames. The multidisciplinary nature of combustion-derived nanoparticles formation makes it excellent training for students in the thermo-sciences research area. All my recent graduated PhD students have gone on to challenging positions related to their thesis research and three of my PhD students have recently begun tenure track professor positions.

燃烧衍生的纳米颗粒的形成既是烟灰等污染物，又是碳黑色等材料。最近，我能够将我的烟灰专业知识转化为炭黑的材料合成。碳黑色（CB）本质上是一种纯净的烟灰形式，具有广泛的应用，例如复合材料，橡胶，塑料，电池和油漆。这些纳米颗粒的骨料和内部结构很重要，因为它们分别确定了烟灰和黑色的健康效应和材料特性。该研究计划的长期目标是对碳颗粒的燃烧产生的生长有基本的理解，以这种理解来开发详细的预测模型，并应用这些模型来解决实用问题，例如预测粒度和碳黑色和烟灰的总体结构。 该提案将基于我们在烟灰形成方面的深刻经验以及我们最近在开创了使用环境传输电子显微镜（ETEM）的成功方面的成功，以实时可视化纳米级碳颗粒，并以亚纳米的分辨率，因为它们由于引入的气体而导致的内部结构而氧化，因为它们由于供热而导致其内部结构变化；这项工作最近获得了两个奖项。该提案将开创ETEM的使用来探索颗粒生长对桥接和包裹主要颗粒的影响。当前模型忽略了这种效果，通过假设生长颗粒的点接触高估了表面积。放入ETEM的颗粒将从我们的火焰或碳黑色生产者获得。 ETEM可以对纳米颗粒的单个聚集体进行反应，以对电子显微镜中引入的烃类气体反应。据信，没有人使用ETEM研究烟灰或碳黑色颗粒的生长。同样，TOF-SIM（飞行次级离子质谱时间）将提供一种新方法，以识别烟灰表面反应或吸附的物种的分子结构。短期目标是我们将：（1）使用ETEM来研究粒子生长过程如何影响并受到粒子骨料和分子结构的影响； （2）使用TOF-SIMS测量从我们的Coflow Flame或我们的ETEM反应器中采样的颗粒表面的分子结构； （3）通过合并第一和第二目标的发现来改善我们的粒子形成模型。模型将更好地预测粒子的生长和表面特性。然后，将通过火焰中的实验数据进一步验证它们。燃烧衍生的纳米颗粒形成的多学科性质使其对热学院研究领域的学生进行了出色的培训。我最近所有毕业的博士生都一直担任与论文研究有关的具有挑战性的职位，而我的三名博士生最近开始任职教授职位。