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.

BACKGROUND Natural gas is essential for the world's supply of energy due to its economic viability and environmental sustainability in producing adequate amounts of clean energy. However, the removal of CO2 as an undesirable impurity remains challenging in natural gas purification. In this work, high performance dense mixed matrix membranes (MMMs) containing a low loading (<2 wt%) of zeolitic imidazolate framework 8 (ZIF‐8) and polysulfone (PSF) were prepared via simple solvent evaporation method and single solvent for the removal of CO2 from CH4. RESULTS Significant enhancements in CO2 permeability and CO2/CH4 ideal selectivity were obtained for the resultant MMMs as compared to the neat PSF membrane. The highest CO2 permeability of 33.57 Barrer and CO2/CH4 ideal selectivity of 39.03 were achieved for a PSF membrane loaded with 1 wt% of ZIF‐8; these values were 514% and 161% higher than those obtained for the neat PSF membrane, respectively. Furthermore, MMM embedded with 1 wt% of ZIF‐8 demonstrated CO2 plasticization pressure up to 16 bar, which is equivalent to an 100% increment of the value obtained for the neat PSF membrane. CONCLUSION Overall, MMMs fabricated in this work demonstrated a significant improvement of CO2 separation from CH4 compared to the PSF‐based MMMs reported in the literature, where most of the reported MMMs contain high loading of fillers up to 30 wt%. Therefore, the MMMs fabricated in this work are ready to be further exploited for application in gas separation industries. © 2021 Society of Chemical Industry (SCI).

This research work focuses on the fabrication of mixed matrix membranes (MMMs) for the enhancement of CO2 removal from CH4. Zeolitic imidazolate framework (ZIF-8) with a framework of 0.34 nm pore size which favours CO2 adsorption is used as filler in this work. Different loadings of ZIF-8 filler were incorporated into polysulfone (PSf) polymer matrix. From the EDX mapping, the morphology of the ZIF-8/PSf MMMs has shown compatibility between the polymer and filler phases. The MMMs demonstrated an increment of 8°C in glass transition temperature, Tg compared to the pure PSf. Based on the permeation results, MMM loaded with 1 wt% of ZIF-8 showed the highest performance with CO2 and CH4 permeability of 33.12 Barrer and 0.85 Barrer respectively, and CO2/CH4 ideal selectivity of 38.8. The development of this new type of MMM has great potential to be utilized in CO2/CH4 separation process.