Based On Multifunctional Fillers To Design And Fabricate Mixed Matrix Membranes For Intensifying CO₂ Separation

The most important thing for the effectively using of biological methane?mainly CH₄?is decarbonization.Among such amount of separation technologies,membrane separation technology is one of the most promising method due to its low-energy requirement,high efficiency,and environmental friendliness.Therefore,developing low-cost and high-performance membrane materials is the key step for the he application and promotion of membrane technology.In this paper,a commercial polyether-polyamide block copolymer?Pebax 1657?is used as a polymer matrix to prepare high-performance mixed matrix membranes?MMMs?.The multifunctional designed of the fillers can bring the multifunctional of the filler.The multifunctional are achieved by selecting the types of the carrier,controlling the pore diameter,and functional groups.Through these strategies,the MMMs can cooperate with the dissolution selection mechanism,diffusion selection mechanism,and reaction selection mechanism,increasing the CO₂ separation performance.The mainly research contents are as follows:?1?Design and prepare the multifunctional filler of ZIF-8/g-C₃N₄ to fabrication MMMs:The multifunctional of ZIF-8/g-C₃N₄ filler with net structure is prepared by ZIF-8 in-suit grown on the pore of the g-C₃N₄.The introduce of ZIF-8 decrease the pore diameter of g-C₃N₄,increasing the selectivity factor of MMMs for CO₂/CH₄.At the same time,the cooperation of ZIF-8 and g-C₃N₄ increase the dispersion and avoid the agglomeration.In addition,the introduced imidazole group which act as an affinity site for CO₂,not only strengthened the CO₂ dissolution selection mechanism,but also improved the interfacial compatibility between the filler and Pebax matrix.The prepared Pebax/ZIF-8/g-C₃N₄-9 MMM has excellent CO₂/CH₄ separation performance which was 97.7%higher of CO₂ permeability and 29%higher of CO₂/CH₄ separation factor,comparison with pure Pebax membrane.?2?Design and prepare the multifunctional filler of ZIF-8@AC to fabrication MMMs:The multifunctional of ZIF-8@AC filler with fixed carrier is prepared by coating AC on the surface of ZIF-8.After coating AC outside of ZIF-8,which increase the number of micropores,increasing the multi-sieve process and enhancing the separation factor.Besides,the ZIF-8@AC has smaller size comparison with ZIF-8,providing the contact area and enhancing the interface interaction between the filler and the Pebax matrix.In addition,the introduced imidazole group which act as an affinity site for CO₂,strengthened the CO₂ dissolution selection mechanism;and the amine group act as fixed carrier,enhancing the reaction mechanism.The prepared Pebax/ZIF-8@AC-7MMM has excellent CO₂/CH₄ separation performance which was 57%higher of CO₂ permeability and 27%higher of CO₂/CH₄ ideal factor,comparison with pure Pebax membrane.?3?Design and prepare the multifunctional filler of[Hmim][NTf₂]@LDHN to fabrication MMMs:The multifunctional of[Hmim][NTf₂]@LDHN filler with semi-fixed carrier is prepared by soaking LDHN into[Hmim][NTf₂].After introducing[Hmim][NTf₂],the pore diameter of LDHN is decreased,increasing the selectivity factor of MMMs for CO₂/CH₄.Besides,the cooperation of LDHN and[Hmim][NTf₂]increase the dispersion and avoid the agglomeration.In addition,the introduced imidazole,sulfone and fluorinated groups act as an affinity site for CO₂,strengthening the CO₂ dissolution selection mechanism;and the CO₃^2-group act as semi-fixed carrier,enhancing the reaction selection mechanism.And the inherent interlamellar spaces of LDHN act as the CO₂ transport channel.The prepared Pebax/[Hmim][NTf₂]@LDHN-6 MMM showed the highest CO₂ permeability of 644±25 Barrer and CO₂/CH₄ selectivity of 34±0.53.