Mass spectrometric characterization of the precursor chemistry and particle growth in flame reactors

火焰反应器中前体化学和颗粒生长的质谱表征

• 批准号: 276027040
• 负责人: Professorin Dr. Tina Kasper
• 金额: --
• 依托单位: Lehrstuhl für Thermodynamik und Energietechnik (ThEt)
• 依托单位国家: 德国
• 项目类别: Research Units
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/276027040?language=en
• 关键词: Mass; spectrometric; characterization; precursor; chemistry

The generation of nanoparticles from gaseous precursors in flame reactors is governed by the complex interaction of flame chemistry and precursor chemistry. The particle size and other size-dependent properties of the particles can be influenced by the reaction conditions and the choice of different precursors. The goal of subproject TP2 is to investigate the conversion of precursor molecules to the intermediates responsible for nanoparticle growth during the flame synthesis of silica and iron oxide nanoparticles. Control variables for the process, such as temperature or radical concentrations, are identified by varying the flame conditions. In cooperation with TP1 and TP8, the data are used to develop and validate the reaction mechanisms needed for a controlled synthesis of complex nanoparticles with tailored properties in scalable processes.In TP2, the intermediates in the flames are identified using molecular beam mass spectrometry (MBMS). In the second funding period, the previously developed MBMS routines were systematically applied to study the influence of flame conditions on the decomposition of selected silicon-containing precursors. In addition, the flame ion MBMS technique was substantially improved. In this way, the progression of the oxidation state of iron intermediates formed in flames from Fe(CO)5 could be traced for the first time. Based on the experimental data, reaction mechanisms were developed. Based on the results and the knowledge gained so far, an expanded picture of how nanoparticles are formed in flames emerges, which in some aspects differs from the accepted view in the literature. In summary, it is observed that already along the reaction pathways of precursor decomposition and the reactions of small intermediate molecules with flame species, compounds with a very low vapor pressure can be formed that condense into particles. Evidence of this early particle formation is observed in both the iron and silicon systems. It differs from particle formation in later reaction steps described in the literature, where chemical reactions initially form clusters from small molecules that then further react or condense into particles. An overarching goal of FOR 2284 in the third project period is to stabilize these early particle phases by quenching and coating and to make them usable. The work in TP2 supports this goal by identifying the early particle formation zones or conditions and by obtaining kinetic data for precursors used in coatings. These include HMDSO, TEOS and tetramethyl tin. The ion MBMS technique is available for the measurement of molecules and clusters and it complements the measurements of the particle phase in TP3 and TP4. It will also be tested whether it is possible to terminate the particle formation reactions by a thermal quenching process.

在火焰反应器中从气态前体产生纳米颗粒是由火焰化学和前体化学的复杂相互作用控制的。颗粒的粒径和其他与尺寸相关的性质可能受到反应条件和不同前体的选择的影响。子项目 TP2 的目标是研究在二氧化硅和氧化铁纳米粒子的火焰合成过程中前体分子向负责纳米粒子生长的中间体的转化。通过改变火焰条件来确定过程的控制变量，例如温度或自由基浓度。与 TP1 和 TP8 合作，这些数据用于开发和验证在可扩展过程中受控合成具有定制特性的复杂纳米粒子所需的反应机制。在 TP2 中，使用分子束质谱法 (MBMS) 识别火焰中的中间体）。在第二个资助期间，系统地应用先前开发的MBMS程序来研究火焰条件对选定的含硅前驱体分解的影响。此外，火焰离子MBMS技术也得到了大幅改进。通过这种方式，首次可以追踪 Fe(CO)5 在火焰中形成的铁中间体的氧化态进程。根据实验数据，开发了反应机理。根据迄今为止获得的结果和知识，出现了纳米颗粒如何在火焰中形成的扩展图景，这在某些方面与文献中公认的观点不同。总之，观察到沿着前体分解的反应路径以及小中间分子与火焰物质的反应，可以形成具有非常低蒸气压的化合物，并凝结成颗粒。在铁和硅系统中都观察到了这种早期颗粒形成的证据。它与文献中描述的后续反应步骤中的颗粒形成不同，其中化学反应最初由小分子形成簇，然后进一步反应或凝结成颗粒。 FOR 2284 在第三个项目阶段的首要目标是通过淬火和涂层来稳定这些早期颗粒相并使其可用。 TP2 的工作通过识别早期颗粒形成区域或条件并获取涂料中使用的前体的动力学数据来支持这一目标。其中包括 HMDSO、TEOS 和四甲基锡。离子 MBMS 技术可用于分子和团簇的测量，它补充了 TP3 和 TP4 中颗粒相的测量。还将测试是否可以通过热淬火过程终止颗粒形成反应。