Fabrication of Oriented Mixed-Matrix Metal-Organic Framework Membranes for Molecular Separation.

The quest for energy-efficient separations is of prime importance. Membrane-based separation can alleviate excessive energy penalties associated with separations. Mixed-matrix membranes (MMMs), combining easily processable polymers and highly selective adsorbents, offer great potential to translate remarkable adsorbent separation properties into the processable matrix. This manuscript describes the detailed methodology for the fabrication of oriented mixed-matrix metal-organic framework (MMMOF) membranes and their subsequent application in various industrially important and highly challenging gas mixture separations. The oriented MMMOF membrane was fabricated based on three essential and interlocked criteria: (i) a MOF molecular sieve filler possesses optimal pore size and shape, functionality, and host-guest interaction that selectively facilitated diffusion of the desired gas molecule over others; (ii) a mastered synthesis control of MOF crystal morphology in a predefined crystallographic direction into high-aspect-ratio nanosheets that ensure maximum accessibility of channels/pores and enhances nanosheets-polymer interface compatibility, enabling high nanosheets loading; and (iii) a conceivable controlled assembly (in-plane alignment) of MOF nanosheets in the polymer matrix to translate the distinct molecular sieving properties of MOF nanosheets into the processable matrix as a form of MMMOF membrane. The membrane exhibited unparalleled hydrogen sulfide and carbon dioxide separation from natural gas under high pressure and high temperature. The methods we presented here have a high potential for the development of various high-performing membranes to address key industrial separations.