Development of highly permselective Mixed Matrix Membranes comprising of polyimide and Ln-MOF for CO₂ capture

Mixed Matrix Membranes (MMMs) with hybrid organic-inorganic characteristics offer a strong alternative to traditional polymer-based membranes to reduce the trade-off between gas permeability and selectivity. This work incorporated lanthanum-Metal Organic Frameworks in the Matrimid to fabricate MMMs. To understand the effects of nano-filler on membranes' morphology, porosity, thermal stability, and chemical composition, MMMs were fabricated with three different loadings of nano-filler, i.e., 10, 20 and 30 wt%. The selectivity and permeability of CH₄, CO₂, and N₂ gases through MMMs were investigated at 10 bar pressure and temperatures ranging from 25 to 55 °C. All MMMs exhibited enhanced CO₂ permeation with increased nano-filler loading because the porous nano-filler provided additional channels and fractional free volume in the polymer matrix. The 30 wt% loaded membrane showed a 183% increase in permeability of CO₂ than neat membrane. With increasing nano-filler loading, the selectivity of MMMs increased from 34.1 to 48.45 for CO₂/N₂ and from 36.2 to 54.67 for CO₂/CH₄, confirming the absence of membrane defects, improved filler/polymer interface, and excellent dispersion of nano-filler in the polymer matrix. The results proved that these membranes could be further used for gas separation industrial applications.