Ag‐Functionalized Carbon Molecular‐Sieve Membranes Based on Polyelectrolyte/Polyimide Blend Precursors

We prepared dense flat‐sheet Ag‐functionalized carbon molecular‐sieve (CMS) membranes from blends of P84 co‐polyimide and a sulfonated poly(ether ether ketone) with a Ag⁺ counterion (AgSPEEK). These blends offer the possibility of producing new functionalized precursor structures, which were previously not possible, such as integrally skinned asymmetric hollow fibers. Membranes prepared at a pyrolysis end temperature of 800 °C showed a maximum permeability for all tested gases at a Ag content of approximately 2.5 wt.‐% (He permeability P_He = 465 Barrer (1 Barrer = 7.5 × 10^–18 m² s^–1 Pa^–1), Pequation/tex2gif-inf-2.gif = 366 Barrer, Pequation/tex2gif-inf-4.gif = 91.8 Barrer, Pequation/tex2gif-inf-6.gif = 10.3 Barrer). The maximum achieved selectivity for O₂ over N₂ with CMS membranes based on these blends was αequation/tex2gif-inf-10.gif = 13.5 (Ag content: 4.5 wt.‐%, Pequation/tex2gif-inf-14.gif = 52.7 Barrer). The CO₂ over N₂ selectivity reached a value of 48.9 (Ag content: 4.5 wt.‐%, Pequation/tex2gif-inf-18.gif = 191 Barrer). These observations are explained by the formation of selective bypasses around Ag nanoclusters in the CMS matrix.