Synthesis of composite membrane using Melamine modified Zeolitic imidazolate framework for CO2/CH4 separation

Abstract

The study involves cellulose acetate (CA) as the primary polymeric matrix, dissolved in acetone, and reinforced with melamine modified zeolitic imidazolate framework-8 ( ZIF-8 ) nanoparticles. Development and characterization of composite membranes for the separation of carbon dioxide (CO₂) from methane (CH₄), specifically tailored for enhanced gas separation performance. These composite membranes are supported on a robust Poly-sulfone ultrafiltration layer, which provides mechanical strength while allowing for selective gas permeation. The research focuses on varying the weight percentage of ZIF-8 nanoparticles within the CA matrix, examining concentrations ranging from 1% to 3% by weight. Performance was evaluated across a range of operational conditions by evaluating under different pressures (4 bar, 6 bar, and 8 bar).Permeability at low ZIF-8 loadings (1 wt%) is slightly higher than for the pure CA membrane, while exhibiting negligible effect on CH₄ permeability resulting in significant improvement in the selectivity of CO₂ over CH₄. CO₂ permeability increases with increasing ZIF-8 content and selectivity increases as densely packed ZIF-8 nanoparticles are formed as content increases to 2 wt% and 3 wt%. Membrane morphology and functional performance are analyzed by advanced characterization techniques involving scanning electron microscopy (SEM) and gas permeation testing. The contribution of this thesis to gas separation technology is to bring understanding in the way that metal organic framework (MOF) nanoparticles such as melamine modified ZIF-8 can further increase the gas separation ability of polymeric membranes while having excellent mechanical stability. We demonstrate that selectivity and efficiency of membranes for CO₂/CH₄ separation can be greatly improved through a favorable optimal loading of the nanoparticle, which may lead to more energy efficient membrane processes during natural gas purification and greenhouse gas management.