Preparation Of Porous Organic Polymers And Study Of Gas: Adsorption And Separation Properties

The carbon dioxide produced by the combustion of fossil fuels in production and life has caused many environmental problems.The flue gas emitted by combustion is composed of a variety of components,and the composition is complex.The most abundant is carbon dioxide,accounting for about 85%,followed by nitrogen,accounting for about 12%.In addition,natural gas is a necessary raw material for people’s production and life,but natural gas in nature is not pure and cannot be directly used in industrial production or daily use.Natural gas is mainly composed of about 50-85%CH₄,and the rest is mainly CO₂,N₂,H₂O and H₂S,among which the most impurity gases are CO₂and N₂.Therefore,it is urgent to design materials that can effectively separate CO₂,CH₄and N₂.Porous organic polymers（POPs）with high specific surface area,high physical and chemical stability,low density,simple synthesis,various synthesis methods,large-scale synthesis,adjustable pore environment,easy modification of synthetic materials and no precious metals,show environmental and safety reliability,and show great potential in various application fields such as sensing,gas storage and separation,optoelectronics,energy storage and catalysis.Therefore,this paper takes porous organic polymers as the research object,designs and synthesizes three kinds of porous organic polymer materials,and explores the structural properties of the synthetic materials by means of XRD,FT-IR,SEM and other characterization methods,and then tests the adsorption and separation performance of single component and mixed gas.This thesis consists of five chapters:In the first chapter,the separation strategy of CO₂and various adsorbent materials such as POPs that have been studied for CO₂adsorption and separation are summarized.In the second chapter,POPs materials SNW-1 and SNW-3 were rapidly synthesized by solvothermal method.The effects and differences of gas adsorption and separation were explored by comparing the structures of SNW-1 and SNW-3 with Schiff base network structure formed by the reaction of meta-aldehyde group（m-phthalaldehyde）and para-aldehyde group（p-phthalaldehyde）with melamine.The structure and morphology were characterized by XRD,FT-IR and SEM.Through gas adsorption test and IAST calculation,it was found that the selectivity of SNW-1 to mixed gas CO₂/CH₄and CO₂/N₂was higher than that of SNW-3.At 298 K and 1 bar,the selectivity of SNW-1 and SNW-3 to mixed gas CO₂/N₂（v/v=15/85）and CO₂/CH₄（v/v=50/50）was 131,131,95.43 and 7.22,respectively.The adsorption capacity of CO₂on SNW-3 is higher than that of SNW-1.At 273 K,the adsorption capacity of CO₂on SNW-1 is 53 cm³/g,and the adsorption capacity of CO₂on SNW-3 can reach 74 cm³/g.The breakthrough experiments of mixed gases CO₂/CH₄and CO₂/N₂show that SNW-1 and SNW-3 can successfully separate the two mixed gases,and the separation effect is excellent.In the third chapter,a new POPs material MA-TFBDC was designed and synthesized.The separation ability of CO₂/CH₄and CO₂/N₂mixtures was improved by using a large number of high polar atoms N and F in the material.The structure,microstructure and elemental analysis were determined by XRD,FT-IR and SEM.The gas adsorption test showed that the adsorption capacity of MA-TFBDC to CO₂was 53 cm³/g at 273 K.The selectivity of MA-TFBDC to mixed gas CO₂/N₂（v/v=15/5）and CO₂/CH₄（v/v=50/50）was 132 and 15,respectively.The breakthrough experiment of mixed gas CO₂/N₂showed that the separation effect of MA-TFBDC was excellent,and the separation time could reach 101 minutes.In the fourth chapter,a series of new POPs materials NAP-TPB were designed and synthesized by solvent weaving method.Through one-component adsorption test,it was found that the material NAP-TPB-23 had the highest CO₂adsorption capacity.At 273 K,the adsorption of CO₂by NAP-TPB-23 can reach 51.2 cm³/g.The structure was determined by XRD,FT-IR,etc.The selectivity of NAP-TPB-23 for CO₂/N₂（v/v=15/85）and CO₂/CH₄（v/v=50/50）was 139 and 18,respectively.The breakthrough experiments of mixed gases CO₂/CH₄and CO₂/N₂proved that NAP-TPB-23 can successfully separate the two mixed gases.In the fifth chapter,the advantages and disadvantages of the synthesized porous organic polymer materials SNW-1,SNW-3,MA-TFBDC and NAP-TPB were summarized and prospected.