Metal–organic frameworks for one-step ethylene purification from multi-component hydrocarbon mixtures

Ethylene (C₂H₄) is extremely important as one of the world's largest chemical commodity. A variety of light hydrocarbon gases (C₁-C₃) and carbon dioxide (CO₂) coexist with C₂H₄ in the production, which need to be removed to produce polymer grade C₂H₄. Conventional thermal-driven distillation separation processes consume large amounts of energy, which has prompted the creation of energy-efficient adsorption separation techniques that utilize physical adsorbents. Metal-organic frameworks (MOFs) have great potential in the separation and purification of ethylene due to their vast surface area, large porosity and highly customizable pores. The purification of C₂H₄ from multi-component mixtures is more related to the real hydrocarbon industry than the extensively studied separation of ideal binary mixtures, but more challenging for the design of desirable MOFs. To date, there is a noticeable absence of a comprehensive discussion of advancements in the separation of ethylene from multi-component mixtures using MOF adsorbents. This review offers a detailed overview of the ongoing developments in the creation of MOFs for multi-component C₂H₄ purification applications, which include the purification of C₂H₄ from ternary, quaternary, quinary, senary, septenary and octary hydrocarbon mixtures. Ternary-component separations include C₂H₂/C₂H₄/C₂H₆ separation and C₂H₂/CO₂/C₂H₄ separation while quaternar-component separations include C₂H₂/C₂H₄/CO₂/C₂H₆ separation and C₂H₂/C₂H₄/C₃H₄/1-C₄H₆ separation. Particularly, the merits and innovations of MOFs in the single-step purification of C₂H₄ from complex mixtures will be examined. This includes insights into the mechanisms of separation and the overarching tactics devised to enhance the performance of the separation process. Moreover, this review will outline the possible hurdles faced when shifting MOFs from the domain of scholarly inquiry to practical industrial application, and to encapsulate the outlook for this swiftly progressing area of study.