Reactions of the precursors for spray-flame of nanoparticles during partial evaporation of the spray

喷雾部分蒸发过程中纳米颗粒喷雾火焰前体的反应

• 批准号: 375856814
• 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: Priority Programmes
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/375856814?language=en
• 关键词: Reactions; precursors; spray; flame; nanoparticles

Spray-flame synthesis is a promising option for the production of functional nanomaterials. The spray is used to introduce low-volatility precursors into the vapor phase. The thermal and chemical structure of the spray flames indicates that chemical reactions occur at substantially different reaction conditions in the different flame zones.The work in this project concentrates on the chemical transformations of the solvent and the precursor in the spray formation zone which is located in the center of the flame. In this zone, only moderate temperatures below 1000 °C are reached and the chemical matrix is dominated by oxygen, the solvent and small amounts of water and precursor. Spray formation and evaporation processes coincide with chemical transformations of the solvent and precursors. Open questions in this sub-process of spray flame synthesis are which reactions happen in the liquid phase and which reactions occur in the gas phase during spray evaporation. The reaction products of these reactions influence subsequent reaction pathways, including the formation pathways of nanoparticles. Those nanoparticles will typically be formed by two main reaction pathways, the droplet-to-particle route and the gas-to-particle route. In the second project period, three sub-processes will be investigated: Liquid phase reactions that occur during slow heating of the liquid solvent/precursor solution will be identified through a detailed chemical analysis of the composition of the solution by electrospray mass spectrometry and gas chromatography. This experiment will determine which precursors already react, i.e. hydrolyze or oxidize, in the liquid phase and are likely to react by the less favorable droplet-to-particle route. Reactions occurring during the partial evaporation of the spray will be investigated in a tubular reactor. In this simplified process, the thermal precursor reactions are separated from radical reactions in the flame by replacing the ignition of the spray and subsequent release of combustion heat by external heating of the reactor. These experiments provide information on how the precursor and solvent interact chemically during the evaporation of the spray and identify the intermediates resulting from the interactions that are present in the gas phase. Subsequent reactions of the intermediates formed from the precursors with flame gases will be investigated in a combined well-stirred and plug-flow reactor. These experiments identify the reaction patterns that lead from molecular intermediates to clusters and then nanoparticles. All experiments rely on mass spectrometric diagnostics for species identification and concentration measurements. A special sampling and transfer procedure will be used to identify charged species when sprays of salt solutions are used.The chemical insights from this project are used to formulate reaction mechanism and support the simulation of the global flame spray synthesis process within the SPP.

喷雾塑料合成是生产功能性纳米材料的希望选择。该喷雾用于将低挥发性前体引入蒸气相。喷火火焰的热和化学结构表明，化学反应发生在不同火焰区域中的根本不同的反应条件下。该项目中的工作集中于位于火焰中心的喷雾形成区域中溶液的化学转化和前体。在该区域中，仅达到低于1000°C的中等温度，化学基质由氧气，溶液和少量的水和前体主导。喷雾形成和蒸发过程与溶液和前体的化学转化一致。在这种喷火综合的子过程中，公开问题是在液相发生哪些反应，以及在喷雾经济过程中发生的反应发生在气相中。这些反应的反应产物会影响随后的反应途径，包括纳米颗粒的形成途径。这些纳米颗粒通常由两个主要反应途径形成，即液滴到颗粒路线和气体到粒子路线。在第二个项目期间，将研究三个子处理：将通过电喷雾质谱法和气相色谱法对溶液组成的详细化学分析来鉴定液体溶剂/前体溶液缓慢加热期间发生的液相反应。该实验将确定在液相中已经反应的前体已经反应，即水解或氧化物，并且很可能会通过较不利的液滴到粒子途径反应。在喷雾的部分经济期间，将在管状反应器中研究反应。在这个简单的过程中，通过替换喷雾剂的点火和随后的组合热量通过反应器的外部加热来代替火焰中的热反应，将热前体反应与火焰中的根部反应分开。这些实验提供了有关在喷雾剂经济过程中前体和溶剂在化学上如何相互作用的信息，并确定了由于气相中存在的相互作用而导致的中间体。随后由火焰气体形成的中间体的后续反应将在合并的良好且塞子流动反应器中研究。这些实验确定了从分子中间体到簇和纳米颗粒导致的反应模式。所有实验都依赖于物种鉴定和浓度测量的质谱诊断。当使用喷洒盐溶液时，将使用一种特殊的采样和转移程序来识别带电的物种。该项目的化学见解用于制定反应机制并支持SPP中全球火焰喷雾合成过程的模拟。