The main purpose of research in membrane gas separation is to develop membranes with high permeability and selectivity. Historically, the gas separation performance of polymeric membranes has been constrained to an upper performance limit. Hence, different methods have been investigated to prepare membranes that can exceed this limitation including the incorporation of inorganic materials into polymer matrices. Membranes formed by this method are called mixed matrix membranes (MMMs). The major challenge is toprepare a defect-free polymer/inorganic nanoparticles interfaces with enhanced separa-tion performance and mechanical and thermal stability. For this purpose, various types ofnanoparticles have been proposed and examined experimentally. This review is especiallydevoted to summarize the fundamental concepts that have to be considered to preparevarious types of MMMs, including considerations for the design novel MMMs that willeventually surpass the Robeson’s trade-off upper bound. In addition, it provides the prosand cons of various factors that affect the MMM preparation especially for CO2separationprocesses.
