An overview of Molecular Simulations Studies in Mixed Matrix Membranes for Gas Separation Processes

Industrial gas separation demands and environmental concerns have motivated the development of membrane technology with a large and evolving variety of novel and advanced materials. In particular, Mixed Matrix Membranes (MMMs), where a combination of a polymer and a filler occurs, can be prepared by infinite combinations between them to benefit from the advantageous properties of polymers and fillers. However, not all the pairs lead to obtain an enhanced membrane material. To reduce and optimize the experimental effort, the use of high-throughput screening computational studies has become an important assessment tool to evaluate the introduction of novel fillers inside different polymers and their modifications. Furthermore, the use of molecular simulations adds an attractive source of phenomenological atomical-level understanding of the modeled system and separation, being possible to test multiple potential gas separations with the same simulated membrane. In this review, an analysis of the current state-of-the-art and emerging trends of atomistic studies applied to MMMs for gas separation processes is presented. Simultaneously, it aims to help the reader to understand and distinguish the different alternatives to gather the desired phenomenological information and how to approach atomistic studies from experimental data for MMMs, presenting their advantages and limitations. Future perspectives and methodologies linked to non-ideal MMMs behavior will be also addressed. The most recent and trending advances in this topic can be highlighted as the transition to newer fillers, the incorporation of a third material in the membrane system, and the defect engineering at the interphase.