Synthesis of Metal-Organic Framework-Based Composite Membranes for Carbon Dioxide Capture from Natural Gas Processing Plants in the Niger Delta

Carbon dioxide removal from natural gas streams in the Niger Delta's processing plants currently relies on amine absorption technology characterised by high regeneration energy penalties, solvent degradation, and corrosion concerns, creating industrial demand for next-generation membrane separation materials with superior CO2/CH4 selectivity and permeability combinations that existing polymeric membranes cannot simultaneously achieve. This study synthesises a family of mixed matrix membranes incorporating zeolitic imidazolate framework (ZIF-8, ZIF-67, and UiO-66) metal-organic framework nanoparticles as selective fillers dispersed in polymethylpentene and Pebax polymer matrices, targeting carbon dioxide capture from natural gas processing plant gas streams representative of Niger Delta field compositions. Metal-organic framework synthesis is performed by solvothermal and room-temperature methods, with crystal size, morphology, surface area, and pore size distribution controlled through precursor concentration and temperature optimisation. Mixed matrix membrane fabrication employs solution casting with controlled evaporation to minimise metal-organic framework agglomeration. Membrane characterisation includes gas permeability testing for CO2, CH4, N2, and H2S at relevant partial pressures and temperatures using a custom constant-volume permeation apparatus. Selectivity, permeability, and plasticisation resistance data are benchmarked against the Robeson upper bound. Interfacial adhesion between polymer matrix and metal-organic framework particles is characterised by scanning electron microscopy, atomic force microscopy, and positron annihilation lifetime spectroscopy. Molecular dynamics and grand canonical Monte Carlo simulations provide mechanistic insight into gas transport through composite membrane microstructure. An original permeability-selectivity trade-off model for metal-organic framework-polymer composites is developed. Keywords: metal-organic frameworks, mixed matrix membranes, carbon dioxide capture, natural gas processing, Niger Delta