Preparation Of Membrane Based On Microporous Polymers And Study On Gas Separation Performance

In order to meet the increasing industrial demand,the preparation of high separation performance gas separation membranes has become a hot topic.The ideal gas separation membrane should have high gas permeability and selectivity,good mechanical properties,excellent thermal stability and chemical stability.Polymeric membrane materials has received increasing attention in gas separation fields,as they has a number of advantages over other inorganic materials,e.g.,low price,good processability and chemical stability.Polymers with intrinsic microporosity?PIMs?is a novel class of polymeric microporous materials with high permeability,due to the rigid and contorted molecular structure in PIMs which disturbs the ordered packing of polymer chains.Tr?ger's base polymer having N-heterocycle moieties is another intrinsic microporosity polymer with higher gas selectivity and lower gas permeability.Therefore,preparation of blending membranes or crosslinked membranes by combining two polymers were an effective means to improve the gas separation performance of the polymer.On the basis of above consideration,the blending membranes and crosslinked membranes were prepared based on PIMs and Tr?ger's base,the performances of membranes were investigated.The main contents and conclusions are summarized as follows:1.Synthesis of PIM-1,PIM-M,PIM-Br-30%,and Tr?ger's base.The structure of these polymers is characterized ¹HNMR.2.Preparation of PIM-1@Tr?ger's base blending membranes.The structure of the membranes were characterized by FT-IR,XRD and SEM.The results showed that there is interaction between the PIM-1 and Tr?ger base,resulting in good compatibility between PIM-1 and Tr?ger's base.With increasing Tr?ger's base content,the gas permeability of the blending membranes decreases,but the selectivity presents an upward trend.For example,as the Tr?ger's base loading increased from 20wt%to 80wt%,permeabilities coefficient of H₂ decreased gradually from 3489 to 1032Barrer,with H₂/N₂ and CO₂/CH₄ selectivities from10.5,6.8 to 27.2,23.0.Compared to PIM-1 membranes,PIM-1@Tr?ger's base blending membrane showed better mechanical properties and anti-plastization,and have better gas selectivity at low temperatures.3.Preparation of PIM-Br-30@Tr?ger's base crosslinked membranes.The change of the value of the d-spacing was characterized by XRD.The results show that with the increase of Tr?ger's base content,the distance between the chains decreases gradually,which is good for gas separation.As the Tr?ger's base loading increases,the gas permeability of PIM-Br-30@Tr?ger'base crosslinked membranes decreases,however the selectivity significantly increases.For example,with the Tr?ger's base loading increases from 5wt%to 50wt%,the permeability of H₂ from 3260 Barrer to 922 Barrer,but the selectivity of H₂/N₂,H₂/CH₄ rises from 14.0,14.0 to 30.7 and 27.9.PIM-Br-30@Tr?ger's base exhibits better gas separation performance.At the same time,the separation performances of CO₂/N₂,CO₂/CH₄,H₂/N₂,H₂/CH₄,O₂/N₂ based on PIM-Br-30@Tr?ger's base crosslinked membranes approach or exceed the 2008 Robeson upper bound.4.The comparison of permeability and selectivity of the blending membrane and cross-linked membranes showed that Tr?ger's base as a macromolecular cross-linking agent can effectively improve the gas separation performance of PIMs and increase the gas selectivity.