| Gas separation is one of the key processes of clean energy production,environmental governance and production of high purity chemicals.However,traditional separation technologies mostly have such problems as high energy consumption,high cost and high pollution.Therefore,the development of highly selective separation materials is important for the development of energy-saving,environmentally friendly separation technologies.Anion-functional materials exhibit good gas separation performance owing their excellent molecular recognition ability.In this dissertation,based on poly(ionic liquid)s,two kinds of anion-functional materials were proposed,for the capture of atmospheric pollutants SO2 and C2H2/C2H4 separation.Separation performances and mechanisms were studied,in order to provide ideas for new materials design and promote the progress of the gas separation process.Porous adsorbents with large surface area provide suficient binding sites for targeted gas molecules.However,the micropores in adsorbents enhance simultaneously the interaction between the adsorbents and competitive gas molecules,reducing the selectivity.In this dissertation,highly crosslinked ionic xerogels and microgels were synthesized by self-polymerization of Gemini ionic liquids.Thesis materials showed unique "selective swelling" phenomenon for SO2 capture.The dense non-porous matrix of xerogels completely excluded the adsorption of most of gases,while SO2 molecules have a strong interaction with ionic moiety and swell in the polymer,leading to an exclusive adsorption.P(D[VImC6]Br)and P(D[VImC6]SCN)exhibited high SO2 capacities with the value up to 498,487 mg/g,respectively(298 K,1 bar).P(D[VIMC6]Br)showed the highest ideal SO2/CO2(614),SO2/CH4(1992)selectvities to date among all of materials.FTIR and molecular simulation indicated that dense polymer networks weaken the interaction between ionic motifs and SO2 moleculars,showing the moderate physical interaction.In the recycling test and fixed bed dynamic adsorption,ionic xerogels showed excellent reversibility and potential application in SO2 capture at low concentration.C2H2/C2H4 separation is the important process of the production of polymerization grade ethylene.In this dissertation,for the highly selective separation of C2H2 and C2H4,two kinds of anion-functional material with remarkable gas separation performance were blended,obtaining anion-pillared microporous materials/poly(ionic liquid)mixed matrix membranes(MMMs)with increased interfacial compatibility via ion-ion interaction.The influence of various factors in the synthesis process was systematically studied to obtain small size crystals for MMMs fabrication.The results showed that for SIFSIX-2-Cu-i crystals with rapid nucleation,modulating is suitable for size reduction,getting rod crystals of 164166 nm.While for ZRFSIX-2-Ni-i crystals with slow nucleation,cube crystals of 146±47 nm were synthesized in the presence of surfactant PVP/CTAC.The prepared MMMs using submicrometer sized crystals showed a good interfacial compatibility and no apparent interface gaps existed.In the C2H2/C2H4 membrane separation,different MOF loadings,ionic densities of polymer matrix and operating temperatures have an effect on the membrane permeability and selectivity.SIFSIX-2-Cu-i/P1-1 MMMs with 30 wt%MOF loading showed a remarkable permeability of C2H2(47.1 barrer)and C2H2/C2H4 selectivity(20.8),which were 220%and 38.0%increase over the pure polymer membrane.The selectivity improved with the increasing of ionic contents in the polymer matrix.Particularly,SIFSIX-2-Cu-i/02.1 MMMs with high ionic density showed a prominent C2H2/C2H4 selectivity(112±52.2)and apparent molecular sieving effect on C2H4.The mass transfer mechanism study based on the solution-diffusion model.indicated that the synergistic effect of anion-pillared microporous materials and poly(ionic liquid)as well as enhanced interfacial compatibility effectively improved the membrane separation performances. |
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