Preparation Of Amino Acid-based Solid Sorbents Andperformance For CO₂ Adsorption

Solid amine adsorbent has been considered as efficient sorbents due to their great adsorption efficiency,low energy consumption for CO₂ capture,and easy-preparation.Amino acid ionic liquids?AAIL?are economic and environmental friendly CO₂ absorbents.Therefore,AAIL-enriched solid sorbents will present excellent CO₂ adsorption performance and thermal stability.In the thesis,the recent progress of techniques and sorbent materials for CO₂ capture was reviewed.We synthesized a series of amino acid ionic liquids and prepared AAIL-loaded PMMA adsorbents by depositing PMMA porous beads with AAILs.Then,HCP?St-DMDAAC?porous microspheres were synthesized and HCP?St-DMDAAC?-AA adsorbent were prepared by ion-exchanging reaction and subsequent acid-base reaction;finally,the effects of preparation factors on the porous structure and CO₂ adsorption performances of HCP?St-DMDAAC?and HCP?St-DMDAAC?porous microspheres were also studied.Firstly,choline chloride?CH?Cl??was transformed into its hydroxide?CH?OH??through ion-exchanging,then[CH][AA]was prepared through the neutralization with amino acid anions?Gly,His,Asp,Trp?,and then[CH][AA]-contained PMMA adsorbents were prepared by depositing[CH][AA]into PMMA porous beads under low pressure;The chemical structures of[CH][AA]and AAIL-loaded PMMA adsorbent were characterized by FTIR and¹H-NMR and the morphologies of the adsorbents were observed by SEM;the specific surface area and pore structure were characterized by the specific surface area and pore size analyzer.The results showed that the specific surface area of PMMA beads containing[CH][Gly]decreased with the increasing amine depositing,and the higher concentration of[CH][Gly]the higher the amine depositing of PMMA[CH][Gly].TG and BET analysis proved that the solid amine adsorbents had not only good chemical adsorption performance but also physical adsorption capacity;and the higher concentration of[CH][Gly]solution was used,the higher adsorption capacity of PMMA beads was.When the[CH][AA]loading content of[CH][AA]-contained PMMA adsorbent was 53.5±0.5%wt,the CO₂ adsorption capacity was up to 15%wt at 298K under an atmosphere pressure.We further fabricated porous microspheres and prepared solid amine porous adsorbents by immobilizing amino acid.P?St-DMDAAC?microspheres were synthesized by the copolymerization of Styrene?St?and Diallyl dimethyl ammonium chloride?DMDAAC?in alcohol&deionized water medium.HCP?St-DMDAAC?porous microspheres were then preparedbyFriedel-Craftsalkylationreaction.Aminoacid-contained HCP?St-DMDAAC?-AAadsorbents was prepared by ion exchanging reaction of HCP?St-DMDAAC?porous microspheres and subsequently acid-base neutralization reaction of amino acid and the HCP?St-DMDAAC?hydroxide microspheres.FTIR proved the successivesynthesisofHCP?St-DMDAAC?-AA,SEMandTEMshowedthat P?St-DMDAAC?microspheres presented smooth surface and uniform particle size ranging from 1.6um to 1.8um,while HCP?St-DMDAAC?microspheres showed rough surface and cross-linked structure.The specific surface area and pore structure of the microspheres were measured by BET analyzer.The specific surface area of HCP?St-DMDAAC?was 1153m²/g,which meant that the porous solid adsorbent was successfully prepared.We investigated the effects of fabrication factors on the morphologies and specific surface area and other properties.The adsorption capacities of HCP?St-DMDAAC?adsorbents and HCP?St-DMDAAC?-AA adsorbents werealso investigated.The morphologiesobservedbySEM.TheparticlesizeofP?St-DMDAAC?and HCP?St-DMDAAC?microspheres slightly decreased with the increase of monomer concentration or mole ratio of St to DMDAAC.There were no significant impact of monomer concentration on the specific surface areas of HCP?St-DMDAAC?microspheres while the molar ratio of two monomers affected.When the molar ratio of St to DMDAAC was 5:1,HCP?St-DMDAAC?microspheres presented the largest specific surface area up to 1153m²/g.The CO₂ adsorption performance of HCP?St-DMDAAC?and HCP?St-DMDAAC?-AA were analyzed by TG and BET analyzer,which showed that HCP?St-DMDAAC?microspheres had highadsorptioncapacitiesupto31wt%andtheadsorptioncapacityof HCP?St-DMDAAC?-Trp was as high as 60wt%,which indicated that these adsorbents had excellent CO₂ adsorption performance.In this paper,we developed a series of amino-acid-based solid adsorbent,which showed the advantages of easy available raw materials,simple operation,high absorption efficiency for CO₂ capture and low energy consumption.Therefore,the developed adsorbents could be very promising material in the field of gas adsorption.