Home >
News > Functionalized flexible MOFs as fillers in mixed matrix membranes for highly selective separation of CO₂ from CH₄ at elevated pressures
Functionalized flexible MOFs as fillers in mixed matrix membranes for highly selective separation of CO₂ from CH₄ at elevated pressures
Summary:
The authors from Universidad de Zaragoza and Delft University of Technology: developed NH₂-MIL-53(Al)@PSF mixed-matrix membranes with pressure-enhanced CO₂/CH₄ selectivity, achieving record selectivity up to 110 at 263 K and 9 bar for natural-gas upgrading.
Background:
1. To address the low selectivity and plasticization of polymeric membranes under high CO₂ pressure, previous researchers blended rigid zeolites or MOFs, yet interfacial voids and poor polymer–filler compatibility limited performance.
2. The authors proposed to embed a “breathing” amino-functionalized flexible MOF (NH₂-MIL-53(Al)) into polysulfone, exploiting hydrogen-bonded interface and framework expansion to obtain rising selectivity with pressure.
Research Content:
1. Synthesis:
The authors synthesized NH₂-MIL-53(Al) microcrystals (0.2 × 1 µm) under microwave irradiation (423 K, 30 min) and fabricated MMMs (8–40 wt % filler) via solution-casting in chloroform.
2. Characterizations:
1) High-pressure CO₂ adsorption shows stepped uptake; framework “breathing” shifted to higher pressure when embedded.
2) SEM cross-sections reveal homogeneous dispersion up to 40 wt % without agglomerates or voids.
3) DRIFTS exhibits red-shift of Al–OH–Al (3680 → 3672 cm⁻¹) and blue-shift of –NH₂ stretches, evidencing hydrogen bonding between MOF and PSF sulfone groups.
3. Application:
Single-gas and 1:1 CO₂/CH₄ mixture permeation at 308 K (ΔP = 3 bar) gave 2-fold selectivity increase (≈ 40 → 80) at 25 wt % filler; at 263 K and 9 bar selectivity reached 110 with CO₂ permeability 6 Barrer, outperforming all reported pure MOF membranes.
4. Mechanism:
External strain from rigid PSF delays MOF np → lp transition; beyond 5 bar CO₂ the expanded framework fills polymer free volume (“self-healing”), enlarging CO₂ diffusion path and enhancing size-sieving while CH₄ permeation drops, yielding unprecedented pressure-enhanced selectivity.
Outlook:
The work demonstrates that flexible MOFs can reverse the traditional selectivity-loss trend at high pressure, opening a practical route for robust, high-loading MMMs in pressurized natural-gas and biogas upgrading.
Functionalized flexible MOFs as fillers in mixed matrix membranes for highly selective separation of CO₂ from CH₄ at elevated pressures
Authors: Beatriz Zornoza, Alberto Martinez-Joaristi, Pablo Serra-Crespo, Carlos Tellez, Joaquin Coronas, Jorge Gascon, Freek Kapteijn
DOI: 10.1039/c1cc13431k
Link: https://pubs.rsc.org/en/content/articlelanding/2011/cc/c1cc13431k
The above review is for academic progress sharing. For any errors or copyright issues, please contact us for correction or removal.
