Hindrance Factor Expression for Diffusion in Random Mesoporous Adsorbents Obtained from Pore-Scale Simulations in Physical Reconstructions
Hindrance Factor Expression for Diffusion in Random Mesoporous Adsorbents Obtained from Pore-Scale Simulations in Physical Reconstructions
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DOI：
10.1021/acs.iecr.7b04840
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发表时间：
2018-02-28
影响因子：
4.2
通讯作者：
Tallarek, Ulrich
中科院分区：
文献类型：
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作者：
Reich, Stefan-Johannes;Svidrytski, Artur;Tallarek, Ulrich
溶质的受阻扩散是许多过程中的限速步骤，其中随机多孔介质作为吸附或反应界面的提供者发挥核心作用。这些过程的优化布局的关键是了解总扩散阻碍因子H（λ）= λ（eff，H）（λ）/D-m，其量化了与在主体液体中的扩散（由D-m表示）相比，通过材料的扩散（由有效扩散系数D-eff，D-H表示）受到阻碍的程度，这取决于λ，溶质尺寸与平均孔径的比率。为了得到一个合适的无规介孔二氧化硅的阻碍因子表达式，我们使用电子断层扫描技术对三种大介孔二氧化硅整体材料的介孔空间进行了物理重构。样品在不同的平均特征尺寸下具有相同的一般中孔形状和拓扑结构，如通过形态学分析建立的，并且在受阻扩散的孔尺度模拟中用作现实模型。从0的D-eff、D-H（lambda）值的大集合
Hindered diffusion of solutes is the rate-limiting step in many processes for which random porous media play a central role as providers of adsorbing or reactive interfaces. The key to an optimized layout of these processes is the knowledge of the overall diffusive hindrance factor H(lambda) = lambda(eff,H)(lambda)/D-m, which quantifies the degree to which diffusion through a material (represented by the effective diffusion coefficient D-eff,D-H) is hindered compared with diffusion in the bulk liquid (represented by D-m) in dependence of lambda, the ratio of solute size to mean pore size. To arrive at an adequate hindrance factor expression for random mesoporous silica, we use electron tomography to physically reconstruct the mesopore space of three macro-mesoporous silica monoliths. The samples share the same general mesopore shape and topology at varied mean feature size, as established by morphological analysis, and serve as realistic models in pore-scale simulations of hindered diffusion. From a large set of D-eff,D-H(lambda) values for 0