喷雾热解过程中微纳多孔结构氧化铈颗粒形成机理及模拟研究

Cerium oxide with micro-nano porous structures has wide application prospects in the fields of exhaust gas treatment, fuel cells and biomedical. Conventional preparation methods are tedious and have low efficiencies, but spray pyrolysis can achieve short process and high efficiency preparation. However, in the process of preparing cerium oxide with micro-nano porous structures by spray pyrolysis, there are problems such as insufficient control over size, morphology, and structural characteristics of the cerium oxide particles. Aimed at addressing these problems, this project intended to quantitatively analyze the agglomeration and porous structure formation processes of cerium oxide particles based on the force balance model. Additionally, an analysis was conducted of the action law of the coupling force on the particles and inter-phase heat and mass transfers during pyrolysis using numerical simulations to determine the formation mechanism of cerium oxide particles by spray pyrolysis. Based on the results, “Production condition-coupling force-particles characteristics" was the study method chosen in this project. The forces were set to an intermediate variable, and a model was established for the relationship between preparation conditions (drop size, drop concentration, drop speed, and pyrolysis temperature) and particle characteristics (size, sphericity, and porosity). This allowed the ranges of the preparation condition parameters of the micro-nano porous cerium oxides to be determined. Based on the proposed model, the control of particle size, morphology, and porous structure of cerium oxides was achieved. The results of this project will provide a theoretical basis and technical support for technical updates and process improvements for the preparation of cerium oxides using spray pyrolysis.

微纳多孔结构氧化铈在尾气处理、燃料电池和生物医学等领域具有广泛的应用前景。传统制备方法步骤繁琐且效率低下，而喷雾热解法可实现短流程、高效率制备。喷雾热解制备微纳多孔氧化铈过程中存在氧化铈颗粒的尺寸、形貌及结构特征可控性不足的问题。针对此问题，本项目拟采用力平衡模型量化分析氧化铈颗粒的团聚过程和多孔结构形成过程，并采用数值模拟方法分析耦合作用力对颗粒的作用规律及热解过程相间传热传质规律，从而揭示喷雾热解过程中氧化铈颗粒的形成机理。在此基础上，提出“制备条件-耦合作用力-颗粒特征”的研究方法，以作用力为中间变量，建立制备条件（液滴尺寸、液滴浓度、液滴速度和热解温度）与颗粒特征（尺寸、球形度、孔隙率）之间的对应关系模型，确定微纳多孔结构氧化铈的制备条件的参数范围。基于该模型，实现了氧化铈颗粒尺寸、形貌和多孔结构的控制。本项目的成果将为喷雾热解制备氧化铈的技术更新和工艺改进提供理论基础和技术支持。

微纳多孔结构氧化铈具有广泛的应用前景。针对喷雾热解制备微纳多孔氧化铈过程中存在氧化铈颗粒的尺寸、形貌及结构特征可控性不足的问题，我们进行了雾化过程的实验及模拟研究、喷雾热解过程中氧化铈颗粒多孔结构形成机理研究、喷雾热解过程中多孔结构氧化铈颗粒尺寸、 形貌及结构的调控研究。采用VOF-to-DPM模型，应用力平衡模型理论优化液滴破碎和碰撞，模拟低气速、高气速、物料口溶液速度变化对雾化性能的影响。重点研究不同制备条件下文丘里反应器的起始雾化性能、完全雾化性能、雾化液滴粒径分布均匀性等重要雾化性能指标，从而优化反应器制备条件。通过蒸发相变、化学反应及流体流动耦合作用下氧化铈颗粒的力平衡模型与欧拉双流体模型的耦合计算，分析了蒸发速率、热解转化率对气相产物的影响规律，对颗粒尺寸、形貌及结构的影响规律，揭示了氧化铈多孔结构的形成机理。研究了液滴浓度、液滴尺寸、液滴速度、热解温度等制备条件对蒸发及化学反应的气相产物的影响规律，揭示了制备条件对氧化铈颗粒尺寸、形貌及结构的作用机制。通过回归分析方法，构建了产物颗粒尺寸、形貌及结构的调控方法。基于该模型实现了氧化铈颗粒尺寸、形貌和多孔结构的控制。本项目的成果将为喷雾热解制备氧化铈的技术更新和工艺改进提供理论基础。