Recently, researchers have suggested the use of membranes to separate gases. They found that using Pebax polymer was very suitable for gas separation. This polymer has good properties and good solubility for carbon dioxide absorption. One of the challenges for researchers is how to turn this polymer into a thin layer for usage as a membrane. Therefore, several methods and solvents have been used to make this membrane. Researchers have calculated the carbon dioxide permeability of this polymer and obtained different results. One of the reasons for the non-uniform permeability results for this gas could be the difference in the method of making the thin film. The use of different methods and solvents affects the physical and chemical properties of this polymer. Perhaps the most important parameters during membrane construction are temperature and drying time. In this research, we want to investigate the effect of these two parameters on the final performance. Thus, the membranes were evaluated by XRD, FT-IR, FESEM, and mechanical strength analyses. Finally, the effect of the parameters on the permeability of carbon dioxide and methane was calculated and compared by the Taguchi method.

Among the various types of Poly (ether block amides)، Pebax1657 shows excellent separation properties for polar or condensable gases such as carbon dioxide in comparison with other light gases. In this research، Pebax1657 as an organic phase and silver nanoparticles as an inorganic phase were considered for preparation of mixed matrix membranes. Moreover، in one side، silver nanoparticles as fillers could enter the polymer chains and enhance the gas permeability by increasing the fractional free volume of membranes. On the other side، partially positively polarized silver nanoparticles beside electron rich parts of PEO segment of the copolymer could increase the CO2 affinity of membranes، which results in increasing the permselectivity of the MMMs for CO2 over CH4 and N2. Also، permeability and selectivity of membranes were studied at different operating temperature and pressures. Moreover، (fabricated) membranes were characterized by FTIR، SEM، and XRD analyses. Obtained results revealed that Ag nanoparticles have decreased the membrane crystallinity and interacted with soft segment of the copolymer، which could enhance transport properties of the polar gases. In addition، the results of gas permeation have shown excellent improvement in permeability and selectivity at temperature of 35 ° C and pressure of 10 bar. For the optimum membrane in comparison with the neat one، CO2/CH4 and CO2/N2 selectivities have increased about 112 about 76 % respectively. On the other hand، an increase in the fractional free volume of the neat polymeric matrix has caused to enhance the CO2 permeability up to 141 %.

Hypothesis: One potential method for improving nanocomposite mixed matrix membranes is through the use of nanoparticles and compounds containing hydroxyl and carboxyl groups, which may aid in the penetration of CO2 gas. In this study, we investigated the selectivity and permeability of a polyether block amide/polyvinyl alcohol (Pebax/PVA) nanocomposite membrane containing magnesium oxide (MgO) nanoparticles. Previous research has shown that the addition of MgO to the Pebax/PVA matrix can increase CO2 permeability by creating an intermolecular space. Methods: Prepared a Pebax/PVA nanocomposite membrane with a weight ratio of 80: 20, containing 10% MgO nanoparticles, through a solution casting method. Evaluated the performance of the Pebax/PVA/MgO nanocomposite membrane for separating CH4 and CO2 gases using various tests. Findings: Characterized the membranes through Fourier transform infrared (FTIR), X-ray diffraction (XRD), and field emission scanning electron microscopy (FESEM) tests. FESEM images showed increased surface roughness with the addition of nanoparticles, and the nanoparticles were well dispersed within the polymer matrix. XRD analysis indicated that MgO nanoparticles had more interaction with PVA chains than with Pebax chains, and peaks at 42° and 62° regions were formed due to the placement of MgO nanoparticles among the polymer chains. We studied various parameters, including polyvinyl alcohol and MgO nanoparticle content, pressure, and temperature, as independent variables and examined their effects on the permeability of CH4 and CO2 gases. We measured the permeability of the constructed membranes and found that the addition of MgO significantly increased the permeability of CH4 and CO2.

In this research, pure polyether block amide (PEBA) membrane and PEBA membrane containing tween surfactant were made using molecular simulation and analyzed from a molecular point of view. In order to investigate the structure of the membranes, their density and free fraction volume were calculated. Also, the radial distribution function was plotted in order to investigate the interaction of CO2 gas with PEBA polymer chains and tween molecules, and the permeability and solubility coefficients against CO2 and N2 gases were obtained. Moreover, the selectivity of CO2 over N2 was calculated for the membranes. The results showed an increase in the solubility and diffusion coefficients of CO2, followed by an increase in the permeability of this gas by adding tween to the polymer matrix, while the selectivity of the membrane containing tween decreased due to the increase in the diffusion coefficient of N2 in this membrane compared to the pure membrane.

This study involved the synthesis of iron-doped macroporous TiO2 sheets, which were subsequently incorporated into a polyether block amide (PEBA) matrix. The investigation focused on various properties ofthe resulting membranes, including morphology, chemical structure, thermal behavior, crystallinity, mechanical strength, and separation characteristics. The findings indicated that the incorporation of FeTiO2 sheets enhanced the mechanical strength of the membranes by forming physical bonds with the polymer chains. Additionally, these sheets created facilitated transport mechanism through Lewis acid centers, resulting in an increase in CO2 permeability. However, the formation of hydrogen bonds led to a stiffening of the polymer matrix, which limited the enhancement of CO2 permeability to 12.4% in the optimal membrane compared to the pure membrane. Conversely, the increased stiffness of the polymer matrix reduced N2 permeability while enhancing CO2/N2 selectivity by 136% in the optimal membrane relative to the pure membrane, thereby allowing it to surpass the upper Robson line

In this research the separation of methane and carbon dioxide gases by using the Nano composite membrane including poly ether block amide and poly vinyl alcohol as polymers with multi wall carbon Nano tubes is investigated. The results of many studies show that the combinations of polyether block amide have great efficiency in making the polymeric membranes for separating gas. However, efforts are doing to improve the permeability and selectivity of such membranes. In this study made membrane was made by using the solution molding and combining the percentage of 80 to 20 for polyether block amide/poly vinyl alcohol and carbon Nano tube with the amount of 0. 5, 1 and 2 percent of weight is used. Morphology and structure of the membrane made by TGA, FE-SEM, XRD and FTIR were checked. Measuring the amount of permeability of the built membranes was done by using constant pressure-variable volume method. Total results showed that with the increase of pressure up to 8 bars, the amount of permeability of carbon dioxide and methane gases increases and the maximum amount of permeability for carbon dioxide and methane gases respectively are 4w6 and 36. 44 bar. The amount of selectivity for binary gases of carbon dioxide-methane increases with the increase of the amount of nanoparticle and the maximum amount in membrane contains 2percent of carbon nanotube and 8bar pressure with the amount of 11. 69.