Mixed Matrix Membranes with Surface Functionalized Metal–Organic Framework Sieves for Efficient Propylene/Propane Separation

Abstract

Membrane technology, regarded as an environmentally friendly and sustainable approach, offers great potential to address the large energy penalty associated with the energy-intensive propylene/propane separation. Quest for molecular sieving membranes for this important separation is of tremendous interest. Here, a fluorinated metal-organic framework (MOF) material, known as KAUST-7 (KAUST: King Abdullah University of Science and Technology) with well-defined narrow 1D channels that can effectively discriminate propylene from propane based on a size-sieving mechanism, is successfully incorporated into a polyimide matrix to fabricate molecular sieving mixed matrix membranes (MMMs). Markedly, the surface functionalization of KAUST-7 nanoparticles with carbene moieties affords the requisite interfacial compatibility, with minimal nonselective defects at polymer-filler interfaces, for the fabrication of a molecular sieving MMM. The optimal membrane with a high MOF loading (up to 45 wt.%) displays a propylene permeability of ≈95 barrer and a mixed propylene/propane selectivity of ≈20, far exceeding the state-of-the-art upper bound limits. Moreover, the resultant membrane exhibits robust structural stability under practical conditions, including high pressures (up to 8 bar) and temperatures (up to 100 °C). The observed outstanding performance attests to the importance of surface engineering for the preparation and plausible deployment of high-performance MMMs for industrial applications.

A roadmap to enhance gas permselectivity in metal–organic framework-based mixed-matrix membranes

“…Both the permeability and selectivity of the ZIF-67-IDip/6FDA-DAM membrane increased with the addition of a filler for propylene/propane separation. Utilizing a similar concept, filler dispersion could be improved for nondispersible KAUST-7 115 ([Ni(pyrazine) 2 ] 2+ square grid is connected with (NbOF 5 ) 2− pillar, 116 KAUST = King Abdullah University of Science and Technology) in 6FDA-DAM matrix.…”

Interior and Exterior Surface Modification of Zr-Based Metal–Organic Frameworks for Trace Benzene Removal

“…As a class of crystalline porous materials, metal−organic frameworks (MOFs) feature diverse structure, large surface area, tunable pore size, and tailorable pore surface, and thus show great potential in many applications, such as adsorption, 5,6 separation, 7,8 catalysis, 9,10 and sensing. 11,12 The removal of low-concentration harmful VOCs as well as other pollutants from ambient air has recently attracted much attention.…”

“…As a class of crystalline porous materials, metal–organic frameworks (MOFs) feature diverse structure, large surface area, tunable pore size, and tailorable pore surface, and thus show great potential in many applications, such as adsorption, , separation, , catalysis, , and sensing. , The removal of low-concentration harmful VOCs as well as other pollutants from ambient air has recently attracted much attention. Due to the inertness and nonpolarity of benzene, most MOFs show low benzene adsorption capacity at low vapor pressures at near room temperatures, although the uptakes could be high in high vapor pressures.…”

Atomistic Insight into the Interfacial Structuring of ZIF-67 MOF/Polymer Composites and Their Propylene–Propane Adsorption Properties

“…This can result in severe plasticization and/or dilation effects in many polymeric membranes, although there are exceptions, particularly in the case of fluoropolymers. 13 Mixed-matrix membranes (MMMs) consisting of a continuous polymer phase and dispersed inorganic or inorganic/organic fillers offer an effective alternative solution to overcome the disadvantages of polymer-based membranes. 14 Embedding fillers, e.g., zeolites and metal−organic frameworks (MOFs), among others, into polymers enables to combine the high gas permeability and selectivity of fillers and the good processability and mechanical robustness of polymeric membranes.…”

“…However, these polymeric membranes suffer from a permeability–selectivity trade-off, forming the so-called Robeson upper bound that prohibits the achievement of very high permeability (productivity) combined with excellent selectivity (efficiency). ,− Moreover, condensable gases, such as propylene and propane, have the potential to cause polymer chains to swell under relatively high gas pressure working conditions. This can result in severe plasticization and/or dilation effects in many polymeric membranes, although there are exceptions, particularly in the case of fluoropolymers . Mixed-matrix membranes (MMMs) consisting of a continuous polymer phase and dispersed inorganic or inorganic/organic fillers offer an effective alternative solution to overcome the disadvantages of polymer-based membranes .…”