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 PHe = 465 Barrer (1 Barrer = 7.5 × 10–18 m2 s–1 Pa–1), P = 366 Barrer, P = 91.8 Barrer, P = 10.3 Barrer). The maximum achieved selectivity for O2 over N2 with CMS membranes based on these blends was α = 13.5 (Ag content: 4.5 wt.‐%, P = 52.7 Barrer). The CO2 over N2 selectivity reached a value of 48.9 (Ag content: 4.5 wt.‐%, P = 191 Barrer). These observations are explained by the formation of selective bypasses around Ag nanoclusters in the CMS matrix.