Precursor release in nanoparticle producing spray flames: Single droplet investigation of multicomponent mass transfer (within SPP 1980)

产生喷雾火焰的纳米粒子中的前体释放：多组分传质的单液滴研究（SPP 1980 内）

• 批准号: 373275335
• 负责人: Professor Dr.-Ing. Lutz Mädler
• 金额: --
• 依托单位: Fachgebiet Mechanische Verfahrenstechnik
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/373275335?language=en
• 关键词: Precursor; release; nanoparticle; producing; spray

The aim of the SPP is a fundamental understanding and theoretically modelling of the entire flame spray pyrolysis process. To develop such a predictive process model for the spray flame synthesis of nanoparticles requires the understanding of many aspects and mechanisms. These include the multicomponent mass transfer from the liquid droplet phase to the gas phase and particle growth that includes oxide formation, nucleation, condensation, coagulation, coalescence and sintering.In the first project phase we could demonstrate the importance of the droplet micro-explosion effect on the homogeneity of nanoparticle production using flame spray pyrolysis precursors. Micro-explosions were especially found to be a vital mechanism for utilizing cheap nitride precursors in industry. In the last project phase strong progress was achieved in single droplet experiments that show the great importance of micro-explosions for effective production of homogeneous nanoparticles. The combustion and particle synthesis of different precursor-solvent systems were experimentally investigated and conceptual mechanism of droplet micro-explosion were deduced. A new double droplet generator and a 3D measurement technique using two time-synchronized high-speed cameras were developed to study double droplet combustion and micro-explosions. Rainbow refractometry was used to measure droplet temperature and composition changes during single droplet combustion of precursor/solvent droplets. A multicomponent diffusion limited model was developed to infer the internal temperature and concentration profiles. The experimental setup of digital in-line holography was constructed. The hologram formation and numerical reconstruction of non-burning droplets were developed. Preliminary holography experiments on single droplet combustion of precursor solutions were conducted. For the first time the luminous flame position above the droplet surface (flame standoff ratio) of single isolated burning droplets with micro-explosions was measured. The primary goal of our project proposal is to study the mechanism and role of micro-explosions in effective synthesis of nanoparticles in the flame spray pyrolysis process using single droplet experiments. To achieve this goal, we will broaden our analysis tools and develop and integrate chemiluminescence, pyrometry, laser-induced fluorescence techniques for single droplet experiments. In close collaboration with other research groups of the SPP we will develop and provide validation data for multicomponent mass transfer models for the precursor release from droplets into the gas phase that includes precursor decomposition, bubble nucleation, shell formation, droplet micro-explosions and mass transfer into the gas phase.

SPP 的目的是对整个火焰喷射热解过程有基本的了解和理论建模。要开发这种纳米颗粒喷雾火焰合成的预测过程模型，需要了解许多方面和机制。其中包括从液滴相到气相的多组分传质以及颗粒生长，包括氧化物形成、成核、冷凝、凝结、聚结和烧结。在第一个项目阶段，我们可以证明液滴微爆炸效应的重要性使用火焰喷射热解前体生产纳米颗粒的均匀性。尤其发现微爆炸是在工业中利用廉价氮化物前体的重要机制。在项目的最后阶段，单液滴实验取得了巨大进展，表明微爆炸对于有效生产均质纳米颗粒具有重要意义。对不同前驱体-溶剂体系的燃烧和颗粒合成进行了实验研究，并推导了液滴微爆炸的概念机制。开发了一种新型双液滴发生器和使用两个时间同步高速相机的 3D 测量技术来研究双液滴燃烧和微爆炸。彩虹折射法用于测量前体/溶剂液滴的单液滴燃烧过程中的液滴温度和成分变化。开发了多组分扩散限制模型来推断内部温度和浓度分布。搭建了数字同轴全息实验装置。开发了非燃烧液滴的全息图形成和数值重建。对前驱体溶液的单液滴燃烧进行了初步的全息实验。首次测量了具有微爆炸的单个孤立燃烧液滴的液滴表面上方的发光火焰位置（火焰间隔比）。我们项目提案的主要目标是利用单液滴实验研究火焰喷雾热解过程中微爆炸在有效合成纳米颗粒中的机制和作用。为了实现这一目标，我们将拓宽我们的分析工具，开发和集成化学发光、高温测定、激光诱导荧光技术用于单液滴实验。通过与 SPP 的其他研究小组密切合作，我们将开发并提供前体从液滴释放到气相的多组分传质模型的验证数据，包括前体分解、气泡成核、壳形成、液滴微爆炸和传质进入气相。