Advanced insights into the role of interfacial defect morphology in mixed matrix membrane gas transport

An important unresolved issue in synthesis and characterisation of Mixed Matrix Membranes (MMMs) is a predictive description of the influence of interfacial defects on the performance of the membranes. While theoretical models of transport have shown success in certain limiting conditions, when they fail to align with experimental observations, it becomes challenging to distinguish between the intrinsic limitations of the theory and unaccounted-for effects within the MMM sample. In this contribution, we employ the voxel-based finite element method (FEM) to develop a comprehensive computational model of gas transport in MMMs, featuring controlled defects. Using this model in application to CO 2 separation as a case study, we explore the intricate relationship between the geometrical features of interfacial defects, the arrangements of filler particles and the emerging transport pathways. We show that the perm-selectivity is directly influenced by the geometry of interfacial defects and filler particles, the configuration of defect regions, the spatial distribution of filler particles, and the gas permeability in each phase. These findings offer valuable insights for the detailed characterisation of interfacial defects, which are crucial for optimising the performance of MMMs. • Developed 3D voxel-based simulation to evaluate performance of non-ideal MMMs. • Explored the role of interfacial defect geometry on membrane performance. • Computed permeability and selectivity over a range of geometrical parameters. • Identified filler arrangement and defect overlap as key uncertainties in prediction.