Modification strategies for metal-organic frameworks targeting at membrane-based gas separations

Abstract

Metal-organic frameworks (MOFs) hold great promises as membrane candidates for highly efficient separation applications, benefiting from the diversified structures, high surface areas and adjustable chemical functionalities. However, non-selective defects and framework flexibility are two main concerns which would attenuate the ultimate separation performance and stability. Modification helps to orientationally optimize the gas adsorption and diffusion behaviors via manipulation towards framework chemical components, aperture sizes, nanocages, and intercrystalline/intracrystalline defects, consequently promoting membrane separation performance and membrane stability. In view of recent progresses of modification on MOF-based membranes, two categories of modification strategies were summarized, namely post-synthetic modification and in situ modification. And the merits and demerits are elucidated. Furthermore, challenges and opportunities for the current modification strategies were discussed from our perspectives, with an expectation to provide guidelines to the future development of MOF-based membranes which were aspired to reach the commercially attractive performance region.

Keywords

• Metal-organic framework
• Modification
• Membrane
• Gas separation