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Multiscale Simulation of Diffusion in Porous Media: From Interfacial Dynamics to Hierarchical Porosity
The Journal of Physical Chemistry C ( IF 3.3 ) Pub Date : 2019-06-06 , DOI: 10.1021/acs.jpcc.9b03250
Ulrich Tallarek 1 , Dzmitry Hlushkou 1 , Julia Rybka 1 , Alexandra Höltzel 1
Affiliation  

We present a multiscale simulation approach to derive effective bed diffusion coefficients (Dbed) in hierarchically structured, macro/mesoporous materials employed as fixed beds for chromatographic separation and heterogeneous catalysis. The simulated Dbed values account for the solute dynamics at the interface between the pore surface and mobile phase as well as for the actual morphology of the material. Molecular dynamics simulations characterize interfacial solute dynamics through mesopore-level distributions of solute density and the diffusion coefficient parallel to the pore surface under explicit consideration of surface chemistry, solute properties, and mobile-phase elution strength. This information is incorporated into Brownian dynamics simulations of the effective diffusion coefficient Dmeso in the mesopore space morphology as physically reconstructed by scanning transmission electron microscopy. Mass transfer between pore space hierarchies is simulated using an effective homogeneous medium representation for the mesoporous domain in the macropore space morphology as physically reconstructed by confocal laser scanning microscopy. Dmeso and Dbed have immediate value as input parameters for fixed-bed models applied in separation and catalysis, which strengthens the basis for predictive modeling and removes ambiguity regarding adsorption and transport mechanisms. The simulation approach is sensitive to subtle changes in interfacial dynamics (e.g., as induced by adjusting the mobile-phase elution strength) and flexible regarding the employed bed morphologies.

中文翻译:

多孔介质中扩散的多尺度模拟:从界面动力学到分层孔隙度

我们提出了一种多尺度模拟方法,以得出在用作色谱分离和非均相催化固定床的分层结构,宏/中孔材料中的有效床扩散系数(D bed)。模拟d值说明了孔表面与流动相之间界面的溶质动力学以及材料的实际形态。在明确考虑表面化学,溶质性质和流动相洗脱强度的情况下,分子动力学模拟通过溶质密度的中孔水平分布和平行于孔表面的扩散系数来表征界面溶质动力学。该信息被纳入有效扩散系数D meso的布朗动力学模拟中通过扫描透射电子显微镜在物理上重建中孔空间形态。使用共聚焦激光扫描显微镜物理重建的大孔空间形态中介孔结构域的有效均质介质表示,模拟了孔隙空间层次之间的质量转移。D中D作为分离和催化中应用的固定床模型的输入参数,具有即时价值,这为预测模型奠定了基础,并消除了有关吸附和运输机理的歧义。该模拟方法对界面动力学的细微变化(例如,由于调节流动相洗脱强度而引起的变化)敏感,并且对于所采用的床层形态具有灵活性。
更新日期:2019-06-07
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