Efficient CO2/CH4 Separation Using Polysulfone/NH2-MIL-125(Ti) Mixed Matrix Membranes.

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This study investigates the fabrication and optimization of mixed matrix membranes (MMMs) composed of NH2-MIL-125(Ti), a metal-organic framework (MOF), dispersed within a polysulfone (PSf) polymer matrix, for efficient CO2/CH4 separation. The MMMs were prepared by using a solution casting method, and their morphology and gas separation performance were systematically characterized. The effect of MOF addition into the polymer matrix, gas permeability, and selectivity were evaluated using a gas permeation setup. Results indicate that incorporating NH2-MIL-125(Ti) nanoparticles enhances the selectivity of the membranes for CO2 over CH4 compared to pure polymer membranes while maintaining acceptable permeability. The membrane morphology demonstrates the uniform distribution of the filler in the polymer matrix. The PSf/NH2-MIL-125(Ti)-15% membrane showed exceptional CO2 permeability and selectivity performance. Specifically, it achieved a CO2 permeability of 19.17 Barrer. Additionally, it exhibited a CO2/CH4 selectivity of 31.95, indicating its ability to effectively differentiate between the CO2 and CH4 gases, which is critical for applications such as natural gas purification and carbon capture. Furthermore, the MMMs produced in this study showed outstanding resistance to CO2 plasticization. The PSf/NH2-MIL-125(Ti)-15% membrane demonstrated superior pressure resistance, withstanding up to 14 bar without significant performance degradation compared to the pristine PSf membrane, which succumbed to plasticization at 4 bar. The enhanced plasticization resistance is attributed to incorporation of NH2-MIL-125(Ti) into the PSf matrix. The combination of high CO2 permeability, excellent selectivity, and robust plasticization resistance positions the PSf/NH2-MIL-125(Ti)-15% membrane as a highly effective solution for CO2 separation applications. The results underscore the potential of these MMMs to achieve significantly better performance metrics than traditional PSf membranes, making them a promising option for industrial gas separation processes.