Abstract: Efficiently enriching low-concentration CH₄ is pivotal for enhancing the utilization of unconventional energy sources and mitigating greenhouse gas emissions. This study focuses on modifying the overall performance of CH₄/N₂ separation membranes. A novel mixed matrix membrane (MMM) with a reinforced substrate structure was developed through a straightforward dip-coating technique. This MMM incorporates a polytetrafluoroethylene (PTFE) porous membrane as the supporting framework, while a composite of block polymer (styrene-butadiene-styrene) and metal-organic framework (Ni-MOF-74) forms the selective separation layer. Comprehensive characterization of Ni-MOF-74 and the fabricated membranes was conducted using X-rays diffraction, scanning electron microscope, Brunauer-Emmett-Teller analysis, and gas permeance tests. The findings indicate a robust integration of the PTFE porous support with the membrane layer, enhancing the mechanical stability of the MMM. Under optimal conditions, the mechanical strength of the PM20 membrane (containing 20% Ni-MOF-74) was observed to be 37.7 MPa, representing remarkable increase compared to the non-reinforced MMM. Additionally, the PM20 membrane exhibited an impressive CH₄ permeation rate of 92 barrer (1 barrer = 3.35×10^-16 mol·m·m^-2·s^-1·Pa^-1) alongside a CH₄/N₂ selectivity of 4.18. These results underscore the MMM's substantial performance and its promising potential in methane enrichment applications.

Key words: Mixed matrix membrane, CH₄/N₂ separation, MOF fillers, Porous skeleton

摘要： Efficiently enriching low-concentration CH₄ is pivotal for enhancing the utilization of unconventional energy sources and mitigating greenhouse gas emissions. This study focuses on modifying the overall performance of CH₄/N₂ separation membranes. A novel mixed matrix membrane (MMM) with a reinforced substrate structure was developed through a straightforward dip-coating technique. This MMM incorporates a polytetrafluoroethylene (PTFE) porous membrane as the supporting framework, while a composite of block polymer (styrene-butadiene-styrene) and metal-organic framework (Ni-MOF-74) forms the selective separation layer. Comprehensive characterization of Ni-MOF-74 and the fabricated membranes was conducted using X-rays diffraction, scanning electron microscope, Brunauer-Emmett-Teller analysis, and gas permeance tests. The findings indicate a robust integration of the PTFE porous support with the membrane layer, enhancing the mechanical stability of the MMM. Under optimal conditions, the mechanical strength of the PM20 membrane (containing 20% Ni-MOF-74) was observed to be 37.7 MPa, representing remarkable increase compared to the non-reinforced MMM. Additionally, the PM20 membrane exhibited an impressive CH₄ permeation rate of 92 barrer (1 barrer = 3.35×10^-16 mol·m·m^-2·s^-1·Pa^-1) alongside a CH₄/N₂ selectivity of 4.18. These results underscore the MMM's substantial performance and its promising potential in methane enrichment applications.

关键词: Mixed matrix membrane, CH₄/N₂ separation, MOF fillers, Porous skeleton