Mixed Matrix Membranes from a Microporous Polymer Blend and Nanosized Metal–Organic Frameworks with Exceptional CO₂/N₂ Separation Performance

Abstract

Most examples of mixed-matrix membranes (MMMs) involve one type of polymer and one type of inorganic filler particle. Here, both polymer blending and MMM approaches are combined to form exceptional three-component membranes for CO 2 /N 2 separation. Nano-sized amino-functionalized UiO-66 is added to a polymer blend of PIM-1 and an ether side chain functionalized polyphosphazene (MEEP80) to create a series of MMMs. Incorporation of UiO-66-NH 2 particles boosts the CO 2 permeability of the PIM-1/MEEP80 (75:25) blend from 3140 up to nearly 6000 Barrer, while maintaining its CO 2 /N 2 selectivity within the range of 22−25, placing it well above the 2008 Robeson upper bound. In addition, the compatibility of the component parts leads to improved mechanical flexibility and mitigated physical aging for more than 300 days. This unique strategy constitutes a facile MMM formulation approach for energy efficient carbon capture from flue gas.

Recent Developments in High-Performance Membranes for CO2 Separation

“…However, several studies overcame the trade-off by maintaining high CO 2 selectivity with significant CO 2 permeability [ 3 ]. While some membranes achieved this by crosslinking [ 33 ], others added a third component (another polymer) to create blend polymer-based MMMs [ 34 , 35 ]. More importantly, some of these membranes showed great improvement in decreasing the aging.…”

From Macro- to Nanoscale: Finite Size Effects on Metal–Organic Framework Switchability

“…Crystals with controlled size and morphology are also essential for biomedical applications (e.g., drug delivery [45][46][47]). The implementation of nanosized MOFs in membranes for separation processes is a timely topic [48][49][50][51][52]. Several groups have discussed nanosized MOFs in the context of electrochemical energy storage [53,54] such as batteries [55,56] and supercapacitors [57][58][59].…”

Synthesis, characterization and application of defective metal–organic frameworks: current status and perspectives

“…The characterization of defects, such as the defect concentration and spatial distribution, remains a signicant challenge. Several techniques and their combinations have been employed to detect structural defects in MOFs, such as powder X-ray diffraction (PXRD), 48,51,83 thermogravimetric analysis (TGA), 29,83,84 acid-base titration, 22,54,85,86 water sorption, 87,88 high-resolution nuclear magnetic resonance (NMR), 5,9,57,89 electron paramagnetic resonance (EPR), 11,37,90,91 positron annihilation lifetime spectroscopy (PALS), [92][93][94] and extended X-ray absorption ne structure (EXAFS). 33,90,95 These characterization techniques can be generally divided into two groups: spectroscopic and microscopic methods.…”

“…PALS, as an analytical tool, provides evidence of the inner pores in porous materials. [92][93][94] In a MOF, the main electron density is located at the framework. As a result, the lifetime of positrons is coupled to the pore size.…”