Quantum Chemical Calculation And Experimental Study On CO₂ Capture By Multi-amino Functional Ionic Liquid

In recent years,with the development of society and the progress of industrialization,the global warming caused by the greenhouse effect is becoming much more serious.As one of the major greenhouse gases absorbent,organic amines have some disadvantages such as easy foaming,solvent volatilization and equipment corrosion,which are difficult to meet the needs of industrial development.Since ionic liquids?ILs?are found to be a new green CO₂ absorbent,which have low vapour pressure and stable performance.Utilizing the diversity of its anions and cations,functional group binding and suitability,designing and developing new highly efficient amino-functionalized ionic liquids?AAILs?has become a research hotspot in CO₂ capture.However,due to the infinite combination possibilities of anions and cations,only screen and synthesize a large number of substances pertinencely can study AAILs efficiently.In order to enhance the study efficiency,the quantum chemical calculation is introduced.This paper combines theoretical calculations with experimental synthesis and uses quantum chemistry calculations to assist in the development of novel AAILs for CO₂ capture.By performing quantum chemical calculations on various AAILs that have been synthesized in our lab,some relationships between the data of the quantum chemical calculations and the experiments results of the AAILs are obtained,and a series of the anions and cations and functionalized groups are screened according to the law.Subsequently,the novel AAILs are synthesized by the new cations and anions,and the theoretical accuracy are verified through experiments.Finally,the kinetic model for the capture of CO₂ by the novel AAILs is established to provide a theoretical basis for its industrial application.The study results of this article are as follows:?1?Through the quantum chemical calculation of the AAILs synthesized in our laboratory,it was found that for the AAILs,the CO₂ absorption capacity and viscosity was decreased with the increase of the interaction energy,while the number of amino groups in AAILs directly affected their absorption capacity.For the same type of cations,their chain length had a significant impact on the absorption and regeneration capacity and regeneration stability.The shorter the chain length,the higher the activation barrier,the lower the absorption capacity,regeneration efficiency and stability.?2?According to the above rules,four kinds of cations?TETA,DETA,DDA and BTA?were screened out for the synthesis of novel AAILs.At the same time,through the quantum chemistry calculation and simulation,[DETAH][Lys]and[TETAH][Lys]were chosen as the best new AAILs,and the predictions of their viscosity and regeneration efficiency followed[TETAH][Lys]>[DETAH][Lys],and the theoretically CO₂ loading were 2.50 and 2.00 mol CO₂/mol AAILs.The experimental results demonstrated the accuracy of quantum chemical predictions.The actual absorption capacity of[TETAH][Lys]and[DETAH][Lys]were 2.59 and 2.13 mol CO₂/mol AAILs,respectively.The regeneration efficiencies were 98.9%and 98.0%,respectively.Viscosity decreased with the increasing interaction energy,and the viscosity followed[TETAH][Lys]>[DETAH][Lys]under the same conditions.These results proved the accuracy of quantum chemistry calculations.?3?The calculation of kinetic data and the establishment of kinetic model provided practical data for the industrial application of novel AAILs.Because both[TETAH][Lys]and[DETAH][Lys]were in line with the zwitterionic mechanism,their mass transfer reaction of absorbing CO₂ was defined as a fast quasi-first order reaction.According to the Arrhenius equation,the logarithm?lnk₂?of CO₂ absorbed by the novel AAILs was linearly fitted to the reciprocal of temperature?1/T?.The Arrhenius relation of[DETAH][Lys]was k₂=9.2694×10¹⁵exp?-8287.7/T?,and the activation energy of chemical reaction was 68.90 kJ/mol.The Arrhenius relation of[TETAH][Lys]was k₂=8.5293×10¹⁴exp?-7469.4/T?,and the activation energy of chemical reaction was 62.10 kJ/mol.