Shape engineering for improved gas separation: Computation-driven insights on harnessing platonic particles in mixed-matrix membranes

Abstract

Recently, there has been a growing focus on the significance of mixed matrix membranes (MMMs) in the domain of gas separation processes. It is well known that, the integration of structurally diverse porous materials into a polymeric matrix intensifies the influence of filler structural sensitivity during the performance evaluation of MMMs. In this study, a computational approach utilizing voxel-based finite element method (FEM) was employed for a systematic investigation of the impact of Platonic shapes used as fillers on the criteria that dictate the design of optimal membranes. The assessment of single gas transport in MMMs containing randomly distributed fillers has confirmed that filler particles with varying sphericity, but the same volume, can significantly influence the effective permeability of MMMs. A reduction in filler particle sphericity, such as in the case of a tetrahedral structure compared to a spherical one, results in a substantial enhancement of effective permeability, primarily due to the introduction of more interconnected pathways. This effect becomes increasingly pronounced at higher filler loading fractions and filler-to-polymer ratios. Furthermore, binary gas transport assessments of MMMs established that filler particle shapes have a considerable influence over the optimal filler–matrix combination, particularly in the context of phase gas transport compatibility, aimed at achieving maximal selectivity in gas mixtures. Filler particles with lower sphericity yield a higher maximum selectivity; however, this is achieved with a partially higher filler-to-polymer permeability for faster gas flow compared to spherical filler particles. This research offers valuable insights for the strategic enhancement of permeability and selectivity in MMMs through the integration of structurally diverse porous materials.