Basic Research On The Design And Application Of Functional Media For CO₂ Separation And Conversio

Carbon dioxide（CO₂）is a naturally abundant,cheap and non-toxic C1 resource that can be used as a base material for the synthesis of high value-added chemicals.However,the efficient utilization of CO₂ is limited by its kinetic inertness and thermodynamic stability.Effective CO₂ capture,storage and utilization（CCSU）technology is a crucial solution to address excessive carbon emissions.It has become an urgent scientific problem to develop efficient and green CO₂ adsorbent and catalyst to fix,store and convert CO₂ into high value-added chemicals.In this study,we focus on several potential functional materials for CO₂separation and conversion,then try to overcome and solved some scientific problems of them.The details of the research are as follows:（1）Ionic liquids and amine solution are the most commonly adsorbents in the field of CO₂ capture.However,there are still some disadvantages such as poor separation selectivity,easy volatilization loss of amines and low CO₂ capacity at high temperatures.In this paper,proton ionic liquids（PILs）-amine absorbent was constructed using the qualities of ionic liquid and amine,and the effects of temperature,CO₂ pressure and water content on CO₂absorption investigated in detail.As result,[DMAPAH][OAc]-EDA showed a high CO₂absorption capacity（6.71 mmol CO₂/g absorbent）at 50°C and 1 bar.FTIR and NMR spectroscopy studies showed that the synergistic interaction between ionic liquids and amines was the essential reason for achieving efficient absorption at high temperatures.The results of the study provided a promising solution for ionic liquids enhancing conventional organic amine CO₂ absorbers.（2）Amine-functionalized adsorbents are the most widely used separation media for the separation of exhaust CO₂ gas.While,the traditional preparation usually uses solvent impregnation method,which requires the consumption of large amounts of organic solvents,resulting in higher adsorbent costs.We studied a series of high-performance amine-modified Si O₂ by a simple,green and efficient mechanical grinding method.The amine loading,pore structure of adsorbents and CO₂ adsorption properties were investigated by characterization.The results suggested that this method has significant advantages for amine dispersion.Moreover,absorbers also had a high CO₂ capacity at high temperatures.Importantly,PEI/Si O₂ had almost unlimited IAST selectivity for CO₂/N₂（15:85）gas at high temperatures.The cyclic testing also demonstrated the excellent stability and regeneration of the adsorbent.（3）Under mild conditions,it was always challenging to fix CO₂ into cyclic carbonates.From the perspective of molecular activation,a series of hydroxy-functionalized proton ionic liquids were designed and synthesized in this paper.CO₂ was successfully converted into cyclic carbonate under mild conditions without solvents and additives.Furthermore,protic ionic liquid catalysts showed excellent substrate compatibility.The mechanism of hydroxyl groups in proton ionic liquids promoted the activation of epoxide molecules through hydrogen bonding was demonstrated.（4）In order to realize CO₂ adsorption and conversion,this study attempts to construct porous materials with both CO₂ adsorption and catalytic conversion.Based on the well-developed pore structure of ionic polymers,we designed and synthesized a series of hyper-cross-linked ionic polymers（HCIPs）with both adsorption and catalytic functions.HCIPs with a surface area of 1448 m²/g were obtained by adjusting the structure and proportion of the polymeric monomers.The results showed that these HCIPs have rich micro/mesoporous structure and abundant ion pair active centers,which not only show excellent CO₂ separation performance,but also can be used as metal-free catalysts for the cycloaddition reaction of CO₂ and epoxides,and successfully convert CO₂ to cyclic carbonate.