Study On CO₂ Adsorption Performances And Kinetics Of Novel Amino Solid Adsorbents

In order to further improve the stability and CO2 adsorption performance of amino modified solid adsorbents,while reducing its regenerative energy consumption and utilization costs,this paper will break through the traditional inorganic materials combined with organic amines model,the selection of natural clay minerals as the substrate of adsorbent research and development,and in addition to the selection of traditional organic amine as amino load compounds,but also the use of amino acid-type ion liquid as amino load materials,in order to achieve the combination of porous solid materials and amino compounds.In recent years,the use of ionic liquid to capture CO2 has attracted widespread attention from researchers.Ionic liquid is an environmentally friendly material with high CO2 absorption capacity and excellent recycling properties.The structure of ionic liquid has the characteristic of strong controllability,which also provides theoretical feasibility for the development of new ion liquid materials and the improvement of their CO2 capture performance.In order to improve the utilization efficiency of ionized liquid and effectively reduce the cost of ionic liquid,this paper combines ionic liquid with porous solid material and applies it to the adsorption process of CO2.In this paper,two natural clay minerals,hydrotalcite and attapulgite,are used as the matrix,and two different organic amines(PEI and APS)and a new type of ionic liquid[P4442]2[IDA]are used as the source of amino groups,and three different amino modified solid adsorbents were designed and prepared by physical impregnation method and chemical grafting method,and applied in the process of CO2 adsorption.At the same time,a series of comparative studies were carried out for different amino loading and CO2 adsorption temperature.Combining TGA,N2 adsorption and desorption experiments,XRD,SEM,FT-IR and other characterization methods,the physical and chemical properties of the adsorbent and its principle of action were explored.The CO2 adsorption capacity and recycling performance of the adsorbent in a pure CO2 atmosphere have been systematically studied.By studying the thermodynamics and kinetics of the adsorbent,the CO2 adsorption performance of the adsorbent is discussed and the CO2 adsorption mechanism of the adsorbent is simply studied.The results are as follows:(1)The adsorbent bcHT-PEI-X was prepared by physical impregnation method from PEI and lithium-aluminum hydrotalcite and was applied to the adsorption of CO2.The results show that when the PEI loading is 40%and the adsorption temperature is 323K,the maximum CO2 adsorption capacity of the adsorbent bcHT-PEI-40%is 1.72 mmol/g.After 7 adsorption and desorption cycles,the CO2 adsorption capacity of the adsorbent bcHT-PEI-40%has attenuated by about 10%,showing a general recycling performance.The calculated regeneration energy consumption of the adsorbent is 63.20 kJ/mol.The Freundlich adsorption isotherm model can well fit the adsorption isotherm curve of this adsorbent for CO2 adsorption;the adsorption heat of adsorption process is 57.49 kJ/mol.This result shows that both physical adsorption and chemical adsorption play an important role in the adsorption of CO2.(2)The adsorbent xAPS-HcAT was prepared from APS and attapulgite by chemical grafting method and applied to the adsorption of CO2.The results show that when the APS loading is 30%and the adsorption temperature is 313K,the maximum CO2 adsorption capacity of the adsorbent 30%APS-HcAT is 1.81 mmol/g.After 10 cycles of adsorption and desorption,the CO2 adsorption capacity of this adsorbent was attenuated by only three percentage points,showing excellent recycling performance.The Freundlich adsorption isotherm model can fit well the adsorption isotherm curve of this adsorbent for CO2 adsorption;the adsorption heat of the adsorption process is 72.63 kJ/mol.This result shows that chemical adsorption plays a more critical role in the adsorption process.(3)The adsorbent HcAT-PI-X was prepared by physical impregnation method from ionic liquid[P4442]2[IDA]and attapulgite and was applied to the adsorption of CO2.The results show that when the load of the ionic liquid[P4442]2[IDA]is 30%and the adsorption temperature is 303K,the maximum CO2 adsorption capacity of the adsorbent HcAT-PI-30%is 1.53 mmol/g,which compared with the same quality of pure ionic liquids,the CO2 capture performance has been increased by as much as three times,which proves that the utilization efficiency of ionic liquids has been significantly improved.After 10 cycles of adsorption and desorption,the CO2 adsorption capacity of this adsorbent hardly decayed,showing excellent cycle regeneration performance,which proved the stability of the connection between the ionic liquid molecule and the carrier.Reflects the extremely weak volatilization characteristics of the ionic liquid[P4442]2[IDA].The Freundlich adsorption isotherm model can fit well the adsorption isotherm curve of this adsorbent adsorbing CO2 at 303K temperature;the isothermic adsorption heat of adsorption process is 80.68 kJ/mol.It shows that chemical adsorption occupies a key position in the adsorption process.In addition,for the three different CO2 solid adsorbents studied in this paper,a variety of different kinetic models are used to fit their experimental data and explore the CO2 adsorption mechanism.The fitting results show that the Avrami kinetic model can well fit the dynamic adsorption curve of these three adsorbents.It is shown that there is a simultaneous effect of physical adsorption and chemical adsorption in the adsorption process,which is consistent with the results obtained by the experimental research institute.