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作为污染物如烟灰和作为材料如炭黑都是重要的。最近，我已经能够将我的烟灰专业知识转化为炭黑的材料合成。炭黑（CB）本质上是一种纯形式的烟灰，具有广泛的应用，例如在复合材料、橡胶、塑料、电池和油漆中。这些纳米颗粒的聚集体和内部结构非常重要，因为它们分别决定了烟灰和炭黑的健康影响和材料特性。该研究计划的长期目标是对燃烧产生的碳颗粒生长有一个基本的了解，利用这种了解来开发详细的预测模型，并应用这些模型来解决实际问题，如预测炭黑和烟灰的粒度和聚集体结构。 这项建议将基于我们在烟尘形成方面的丰富经验，以及我们最近成功地率先使用环境透射电子显微镜（ETEM），以真实的时间可视化纳米级碳颗粒，具有亚纳米分辨率，因为它们由于引入气体而氧化和/或由于加热而改变其内部结构;这项工作最近获得了两个奖项。该建议将开创性地使用ETEM来探索颗粒生长对桥接和包裹初级颗粒的影响。目前的模型忽略了这种影响，通过假设增长颗粒的点接触而高估了表面积。放入ETEM的颗粒将从我们的火焰或炭黑生产商处获得。ETEM可以在电子显微镜中对纳米颗粒与引入的碳氢化合物气体反应时的单个聚集体进行成像。据信，还没有人使用ETEM来研究烟灰或炭黑颗粒的生长。此外，TOF-SIMS（飞行时间二次离子质谱）将提供一种新方法来识别烟灰表面反应或吸附的物质的分子结构。我们的短期目标是：（1）使用ETEM来研究颗粒生长过程如何影响颗粒聚集体和分子结构以及颗粒生长过程如何受颗粒聚集体和分子结构的影响;（2）使用TOF-SIMS测量从我们的同向流火焰或我们的ETEM反应器中取样的颗粒表面的分子结构;（3）通过结合第一个和第二个目标的发现来改进我们的颗粒形成模型。该模型将更好地预测颗粒的生长和表面性质，然后将进一步验证火焰的实验数据。燃烧衍生的纳米颗粒形成的多学科性质使其成为热科学研究领域学生的优秀培训。我所有最近毕业的博士生都在从事与论文研究相关的具有挑战性的工作，我的三个博士生最近开始了终身教授的工作。