This review highlights advancements made in anion exchange membrane (AEM) head groups, polymer structures and membrane synthesis methods. Limitations of current analytical techniques for characterizing AEMs are also discussed. AEM research is primarily driven by the need to develop suitable AEMs for the high-pH and high-temperature environments in anion exchange membrane fuel cells and anion exchange membrane water electrolysis applications. AEM head groups can be broadly classified as nitrogen based (e.g. quaternary ammonium), nitrogen free (e.g. phosphonium) and metal cations (e.g. ruthenium). Metal cation head groups show great promise for AEM due to their high stability and high valency. Through “rational polymer architecture”, it is possible to synthesize AEMs with ion channels and improved chemical stability. Heterogeneous membranes using porous supports or inorganic nanoparticles show great promise due to the ability to tune membrane characteristics based on the ratio of polymer to porous support or nanoparticles. Future research should investigate consolidating advancements in AEM head groups with an optimized polymer structure in heterogeneous membranes to bring together the valuable characteristics gained from using head groups with improved chemical stability, with the benefits of a polymer structure with ion channels and improved membrane properties from using a porous support or nanoparticles.

Gas separation technologies for carbon-free hydrogen and clean gaseous fuel production must efficiently perform the following separations: (1) H₂/CO₂ (and H₂/N₂) for pre-combustion coal gasification, (2) CO₂/N₂ for post-combustion of coal, (3) CO₂/CH₄ for natural gas sweetening and biofuel purification, and (4) O₂/N₂ for oxy-combustion of coal. By utilizing a molecular simulation approach, Monte Carlo procedures, free volume analysis, and continuum modeling, we predict the intrinsic gas permeability and separation properties of several new Zeolitic Imidazolate Frameworks (ZIFs), a family of the Metal–Organic Frameworks (MOFs). The well defined pore sizes in conjunction with high surface areas make ZIFs prime candidates for molecular sieving. In this work, our calculated intrinsic properties are compared with current experimental results where ZIFs are either grown in dense layers to form pure inorganic membranes on porous supports or dispersed within a polymer phase to form mixed matrix membranes. Consequently, this paper assesses current membrane development according to industrial feasibility targets and highlights the achievable superior separation results for ideal membrane configurations. For example, ZIF-11 is discovered to be capable of sieving H₂ from all of its larger gas counterparts at a remarkable H₂/CO₂ selectivity of 262 and H₂ permeability of 5830 Barrer, well within the target area for efficient hydrogen production.