Development And Characterization Of Amine-based Mesoporous Silica For Carbon Dioxide Capture

With the rapid development of the society,the concentration of carbon dioxide in atmosphere has increased sharply and triggered a series of climate problems,such as global warming.CO₂ capture,utilization and storage technology is an effective way to deal with this problem.CO₂ adsorption based on solid absorbents has shown its advantage in easier to installation and lower energy consumption.Recently,amine-based solid absorbents have obtained great highlight and they are considered as,a promising and novel solid absorbent.However there are rarely researches on the circulating capture process for amine-based solid absorbents.This paper,the CO₂capture efficiency of amine-based solid absorbents was studied systematically by the research on basic material property,theoretical calculation of VPSA process and experimental study of VPSA cycle.Firstly,using mesoporous silica as a support,a series of amine-based absorbents were prepared by impregnated with tetraethylenepentamine?TEPA?or polyethyleneimine?PEI?.The structure and CO₂ adsorption capacity of all the solid adsorbents were investigated to evaluate the influence of amine species and amine loading amount.MS-PEI600-30 exhibited highest CO₂ capture capacity of 1.97mmol/g at 25^oC and 1.0 bar owing to the optimal loadings to maintain the channel structure and provide sufficient amine sites for chemical adsorption.Then,based on the adsorption isotherm of mesoporous silica and MS-PEI600-30at 25 ^oC,VPSA cycle and calculation model were constructed to study the effects of three system parameters,including CO₂ concentration,vacuum pressure,pressurization proportion and percent of unused bed,on energy efficiency in terms of the second-law efficiency and processing capacity.Amine-based solid adsorbents have great advantages in terms of CO₂ adsorption capacity,but the energy efficiency of VPAS cycle of which is lower than that of mesoporous silica.Compared with mesoporous silica,the amine-based adsorbents had advantages in the case of lower CO₂ concentration or lower CO₂ partial pressure.Finally,by building vacuum pressure swing adsorption test system with a single tower and four cycle steps,the cyclic CO₂ capture performance of amine-based solid adsorbents was experimentally studied.It is found that the CO₂ capture performance of the amine-based adsorbents in VPSA process was not ideal,due to the limitation of the means of regeneration and the adsorption characteristics,and the working adsorption capacity was only 5.13 g-CO₂/kg.Reducing the intake flow or increasing the feed adsorption time could increase the working adsorption capacity of the amine-based adsorbents slightly.