Phenolic resin-coated NH2-UiO-66-based mixed matrix membranes for high-efficiency natural gas purification

Under industrially conditions (pressures ≥10 bar), polymer membranes usually exhibit poor CO 2 /CH 4 separation performance and limited stability, severely restricting their practical application. Here, we present a materials engineering strategy, in which phenolic resin is in-situ polymerized on the surface of NH 2 -UiO-66 to engineer the MOF-polymer interface, thereby enabling high CO 2 /CH 4 separation performance and excellent structural stability for mixed matrix membranes. The phenolic resin forms a uniform coating (∼10 nm thick) on the porous MOF surface, providing a high-density CO 2 active sites that accelerate CO 2 transport. In addition, due to favorable interfacial interactions between the phenolic resin shell and the polyetherimide matrix, the resulting MMMs exhibit excellent stability under high pressures. Compared to the pristine PEI membranes, the CO 2 permeability and CO 2 /CH 4 selectivity of the optimized 30-RF@NH 2 -UiO-66-PEI membranes are enhanced by 8550% and 1500%, respectively. Under simulated industrial conditions (10/90 CO 2 /CH 4 mixture at 10 bar and 50 °C), the engineered membranes maintain a CO 2 permeability of 6105 Barrer and a CO 2 /CH 4 selectivity of 30.5, demonstrating excellent separation performance. More importantly, the 30-RF@NH 2 -UiO-66-PEI membrane exhibits both scalability (readily extendable to the square-meter level) and cost-effectiveness (∼55 USD per square meter). This work highlights the potential of phenolic resin-modified MOF fillers to enable efficient CO 2 /CH 4 separation under realistic industrial conditions.