The Imidazole Polyionic Liquids/mesoporous Alumina Composites:Synthesis,Characterization And CO₂ Capture

CO₂ is the most important component of greenhouse gases.Its massive emissions may cause serious environmental problems.However,CO₂ as an industrial raw material is a rare green energy source,therefore it is necessary to achieve efficiently CO₂ capture.Polyionic liquid is an excellent and designable CO₂ absorbing solvent,but its high viscosity limits further development.However,loading it on inorganic porous materials can not only increase the gas-solid contact area,but also reduce the amount of polyionic liquid,which is beneficial for CO₂ adsorption.Mesoporous alumina,owing to its high specific surface area and low price,has good applications in catalysis,adsorption and separation,so it can be used as an ideal carrier.This article aims to support the synthesis of target polyionic liquid on mesoporous alumina,so as to achieve efficiently CO₂ capture.The specific research contents are as follows:1. For the synthesis study of CO₂ adsorption by conventional polyionic liquids,the final products P[VPIm]BF₄,P[VBIm]BF₄ and P[VRIm]BF₄ were mainly obtained through a series of reactions such as ion exchange,autopolymerization and anion exchange.Among them,the prepared polyionic liquid was characterized and analyzed by FT-IR,¹H NMR and TGA to determine its structure and thermal stability;secondly,the polyionic liquid was loaded on mesoporous alumina by the ultrasonic immersion method.The obtained composite materials were tested for CO₂ adsorption performance under different loading ratios,pressures,temperatures and CO₂ flow rates,and the most suitable process conditions were determined:loading ratio 1/1,pressure 0.1 MPa,temperature 293 K and CO₂ flow rate 10m L/min.Under this condition,the maximum adsorption capacity reached 0.384 mmol/g,and the optimal composite material was tested for regeneration performance and simple kinetic analysis.The experimental results showed that after 5 times cycles of the composite material,the regeneration efficiency can reach 95.5%.After performing dynamic analysis,it was found that it conformed to the pseudo-first-order model.2. Based on the adsorption of CO₂ by conventional polyionic liquids,some functional polyionic liquids were carried out to design and synthesize for CO₂ adsorption.The polyionic liquids（P[VRIm]Cl,P[VEIm]Cl and P[VCIm]Cl）were synthesized successfully.The synthesized functional polyionic liquid was characterized by FT-IR,1H NMR,EA and TGA to verify its structure and thermal stability;secondly the composite materials obtained by ultrasonic dipping method were characterized by BET,XRD,SEM and TEM.And functional polyionic liquids composite materials for CO₂ adsorption performance were tested the adsorption performance under different loading ratios,pressures,temperatures and CO₂ flow rates,and the most suitable process conditions were determined:loading ratio 1/1,pressure0.1 MPa,temperature 313 K and CO₂ flow rate 10 m L/min.Under this condition,the maximum adsorption capacity of P[VCIm]Cl/MA was 0.562mmol/g.And the regeneration efficiency after 5 times cycles reached 94.8%.At the same time,it was found that it conformed to the pseudo second-order model after dynamic analysis.By comparing the amount of CO₂ adsorption,it was found that the functional polyionic liquid owned better CO₂adsorption performance than the composite material of conventional polyionic liquid.