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CO2 separation from CH4 by using mixed matrix membranes has received great attention due to its higher separation performance compared to neat polymeric membrane. However, Robeson’s trade-off between permeability and selectivity still remains a major challenge for mixed matrix membrane in CO2/CH4 separation. In this work, we report the preparation, characterization and CO2/CH4 gas separation properties of mixed matrix membranes containing 6FDA-durene polyimide and ZIF-8 particles functionalized with different types of amine groups. The purpose of introducing amino-functional groups into the filler is to improve the interaction between the filler and polymer, thus enhancing the CO2 /CH4 separation properties. ZIF-8 were functionalized with three differents amino-functional group including 3-(Trimethoxysilyl)propylamine (APTMS), N-[3-(Dimethoxymethylsilyl)propyl ethylenediamine (AAPTMS) and N1-(3-Trimethoxysilylpropyl) diethylenetriamine (AEPTMS). The structural and morphology properties of the resultant membranes were characterized by using different analytical tools. Subsequently, the permeability of CO2 and CH4 gases over the resultant membranes were measured. The results showed that the membrane containing 0.5 wt% AAPTMS-functionalized ZIF-8 in 6FDA- durene polymer matrix displayed highest CO2 permeability of 825 Barrer and CO2/CH4 ideal selectivity of 26.2, which successfully lies on Robeson upper bound limit.

Membrane technology, particularly polymeric membranes, is utilized in major industrial ethylene recovery owing to the very convenient and robust process. Thus, in this paper, a composite membrane (CM) comprising SAPO-34 and Pebax-1657 was employed to conduct a separation performance under two operating conditions, including temperatures and pressures, ranging from 25.0–60.0 °C and 3.5–10.0 bar, respectively. CO2 permeability and CO2/C2H4 ideal selectivity values that ranged from 105.68 to 262.86 Barrer and 1.81 to 3.52, respectively, were obtained via the experimental works. The separation of carbon dioxide (CO2) from ethylene (C2H4) has then been optimized using response surface methodology (RSM) by adopting a central composite design (CCD) method. As a result, the ideal operational conditions were discovered at a temperature of 60.0 °C and pressure of 10.0 bar with the maximum CO2 permeability of 233.62 Barrer and CO2/C2H4 ideal selectivity of 3.22. The typical discrepancies between experimental and anticipated data for CO2 permeability and CO2/C2H4 ideal selectivity were 1.67% and 3.10%, respectively, demonstrating the models’ validity. Overall, a new combination of Pebax-1657 and SAPO-34 composite membrane could inspire the latest understanding of the ethylene recovery process.

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Carbon dioxide (CO2 ) separation is necessary for natural gas purification to enhance the calorific value of methane gas (CH4 ), besides reducing the corrosion risk in pipelines with the presence of water or moisture. This work focuses on the development of new combination of composite membrane materials containing titanium-based metal organic frameworks (MOFs) and 6FDA-based polymer for CO2 and CH4 gases permeation. The composite membranes were successfully fabricated by incorporating 0.5, 1.0, 3.0 and 5.0 wt% of MIL-125 (Ti) fillers into 6FDA-durene polymer by using solvent evaporation method. The resultant fillers and composite membranes were characterized by using different analytical tools including XRD, FESEM and EDX. Then, the permeability test was conducted by using single gas of CO2 and CH4. The results showed that composite membrane loaded with 5wt% of MIL-125(Ti) showed the highest CO2 permeability of 814.9 Barrer, and CO2/CH4 ideal selectivity of 18.1 compared to pure 6FDA-durene membrane with CO2 permeability of 510.3 Barrer and CO2/CH4 ideal selectivity of 8.6. It was found that the incorporation of fillers, MIL-125 (Ti) into 6FDA-durene polymer matrix led to the enhancement of gas permeation performance due to good compatibility between fillers and polymer matrix. Besides, the presence of organic ligand in MIL-125 (Ti) filler has potentially reduced the interfacial voids between the filler and polymer.