Scale-up fabrication of MOF membranes toward olefin/paraffin separation
Olefin-paraffin separation is a critical and energy-intensive process in the petrochemical industry, with ethylene and propylene purification alone consuming 0.3% of global energy. Current distillation methods are energy-inefficient, and polymer membranes exhibit inadequate separation performance. Metal-organic frameworks (MOFs), particularly ZIF-8, offer precise molecular sieving due to their uniform pore aperture (~3.4 Å), which lies between the kinetic diameters of propylene and propane. Despite excellent lab-scale performance, ZIF-8 membranes face scalability challenges, with effective areas typically below 10 cm², far from the tens of thousands to millions of square meters required industrially. This paper reviews a recent breakthrough by Weihong Xing, Yichang Pan, and colleagues, who developed a micro-space transformation process (MSTP) for scalable fabrication of heterostructured ZIF-8 (HZIF-8) membranes. Using sealed inner lumens of tubular ceramic supports as confined reaction spaces, they achieved single-tube areas of ~200 cm² and total fabricated areas exceeding 4.6 m². The membranes demonstrated stable separation performance over 30 days at 17 bar and 55 °C with a feed flow of 20 Nm³ d⁻¹. This work represents a significant step toward industrial application, addressing critical bottlenecks in membrane area expansion, defect control, and mechanical stability.