Recent advances in tuning molecular transport properties in metal-organic frameworks and covalent-organic frameworks for few sorption related applications: A mini review

Transport properties of metal-organic frameworks (MOFs) and covalent-organic frameworks (COFs) play important roles in their performance in various applications. This Mini Review discusses how transport properties, e.g., diffusivity and transport resistance, might be manipulated in these materials for optimal performance. We focused on three applications, e.g., membrane separation, adsorption, and catalysis. For membrane separation, examples will be given to illustrate different strategies applied to address the limited diffusion selectivity issues, high transport resistance from thick membranes, and the challenges for scaling up high-performance membranes. For adsorption, strategies will be explained on how to achieve ultrahigh adsorption selectivity (molecular sieving), leveraging kinetic selectivity for separations with low equilibrium adsorption selectivity, and addressing the slow adsorption kinetics issues. The importance of pore size engineering will be discussed for applying MOFs and COFs either as the catalysts or catalyst supports. Last, how computational chemistry and machine learning for accelerating materials research will also be touched. This article will give readers a general idea of recent progress on tuning the transport properties of MOFs and COFs and how innovative strategies could be leveraged to achieve the desirable process outcomes.