Morphological characterization and transport properties of physically reconstructed chromatographic beds

定量的形态-输运关系在开发更高效的功能材料的挑战中起着关键作用。有针对性地优化效率需要了解多孔固体的制备、形态和质量传递是如何相关的。本项目的重点是物理重构吸附剂（固定床）的形态和传输特性的表征，这代表了小硅基颗粒（< 3µm）、硅基单体和有机聚合物单体的液相色谱的最新发展和问题（挑战）。三维重建是基于传统制备的颗粒床和整体固定床，包括颗粒床的填充工艺和整体固定床的合成方案。这方面很重要，因为它为项目所遵循的方法和获得的结果提供了透明度、独创性和独创性。直接在重建的孔隙空间中模拟流体流动和质量传递，可以基于材料的内在形态异质性和由此产生的流动不均匀分布来表征时空动力学——从微观孔隙尺度到宏观床层尺度。通过对孔隙空间的几何和拓扑分析提取参数，实现了形态非均质性的量化。我们分析了孔隙的形状、大小分布和连通性，其中流体流动和平流运输占主导地位，以及扩散运输和吸附占主导地位的空间域，如颗粒内部的停滞区域（或整体骨架）。本项目的目标是通过对无序孔隙空间的几何和拓扑分析，结合详细的流体和质量输运的孔隙尺度模拟，确定有效扩散输运的形态描述符，特别是色谱上更相关的水动力弥散。从扩散/吸附限制质量传递的空间域到流场占主导地位的区域，我们用形态描述符定量评估了它们的结构异质性。这在模拟扩散/吸附、流动和质量输运以及推导输运系数中也有类似的过程，反映了这种结构的非均质性。因此，色谱实践的核心运输性质可以与形态性质相关联，形态性质本身反映了吸附剂的包装过程或合成方案。这种互补的方法使我们能够识别敏感的形态描述符（通过详细的传输模拟验证），这将在未来指导材料性能的系统优化，从合成到基于物理重建的目标应用。

Quantitative morphology-transport relationships play a key role in the challenge to develop ever more efficient functional materials. Targeted optimization of efficiency requires knowledge on how preparation, morphology, and mass transport of a porous solid are related. In the focus of this project is the characterization of morphological and transport properties of physically reconstructed adsorbents (fixed beds), which represent the latest developments and problems (challenges) in liquid chromatography with small silica-based particles (< 3 µm), silica-based monoliths, and organic polymer-monoliths. The three-dimensional reconstructions are based on experimental particulate and monolithic fixed beds, which have been conventionally prepared regarding the packing process of the particulate beds and the synthesis protocol of the monoliths. This aspect is important as it provides transparency, originality, and genuity to the methodology followed in this project and the obtained results. Simulations of fluid flow and mass transport directly in the reconstructed pore spaces allow the characterization of spatiotemporal dynamics based on the intrinsic morphological heterogeneity of the materials and resulting flow maldistribution - from the microscopic pore scale up to the macroscopic bed scale. The quantification of morphological heterogeneity is achieved with parameters extracted from the geometrical and topological analysis of the pore spaces. We analyze shape, size distribution, and interconnectivity of the pores, in which fluid flow and advective transport dominate, as well as spatial domains, in which diffusive transport and adsorption prevail, like in stagnant regions inside the particles (or a monolith skeleton). The goal of this project is to identify morphological descriptors for effective diffusive transport and especially the chromatographically far more relevant hydrodynamic dispersion through the geometrical and topological analysis of the disordered pore spaces in combination with the detailed pore scale simulations of flow and mass transport. From spatial domains, in which diffusion/adsorption limit mass transport, to regions, in which the flow field dominates, we quantitatively assess their structural heterogeneity with morphological descriptors. This proceeds analogously in the simulations of diffusion/adsorption, flow, and mass transport and derived transport coefficients, which reflect this structural heterogeneity. Consequently, transport properties central to chromatographic practice can be correlated with morphological properties, which themselves reflect the packing process or synthesis protocol of an adsorbent. This complementary approach allows us to identify sensitive morphological descriptors (validated through the detailed transport simulations), which in the future will direct the systematic optimization of material properties from the synthesis to targeted applications based on physical reconstruction.