| China plans to peak carbon dioxide emission before 2030 and realize carbon neutral before 2060,which is of vital importance because it concerns climate change,energy security,industrial upgrading and international competitiveness of our country.CO2 capture,utilization and storage(CCUS)is effective method to reduce CO2 emission.Amine-functionalized solid sorbent has many advantages and is promising for CO2 capture.The further improvement of the performance of sorbents relies on increasing sorption and desorption rates.The present work aims to improve sorption and desorption rates by tailoring the structure of sorbents from three aspects:nano pore structure,amine assembly,and molecular structure of amine films.The influence of tailoring of structure on sorption and desorption rates is also established.The main contents are as following:PEI-MSN sorbents were prepared by impregnating polyethyleneimine(PEI)into supports with inverted-cone shaped pores.PEI is loaded in the narrower ends of inverted-cone shaped pores,and thus the open space at pore mouths is released.65PEI-MSN sorbent shows a sorption capacity of 214 mg g-1,maximum sorption and desorption rates of 90.5 mg g-1 min-1 and 46.7 mg g-1 min-1,average sorption and desorption rates of 32.0 mg g-1 min-1 and 13.9 mg g-1 min-1 at 80℃.Compared with the sorbents with cylindrical pores and similar amine loading,65PEIMSN sorbent shows improved maximum sorption rate by 27%,improved maximum desorption rate by 71%,improved average sorption rate by 52%,improved average desorption rate by 162%and improved working capacity by 58%at 80℃.At 30-80℃,the sorption and desorption rates of 50PEI-MSN and 65PEI-MSN sorbents are kinetically controlled,and increasing amine loading from 50 wt%to 65 wt%is beneficial for improving sorption rate.2N-CSD-4.78 sorbent with arranged amine assembly in pores was prepared via the directing of templates.2N-CSD-4.78 sorbent shows a sorption capacity of 79 mg g-1,maximum sorption and desorption rates of 60.5 mg g-1 min-1 and 12.1 mg g-1 min-1,average sorption and desorption rates of 12.8 mg g-1 min-1 and 10.6 mg g-1 min-1 at 30℃.Compared with 2N-SBA15G-4.29 sorbent prepared by post-grafting,2N-CSD-4.78 sorbent shows an increase of maximum sorption rate by 16%,average sorption rate by 73%,average sorption rate by 19%,comparable maximum desorption rate,together with 40%increased working capacity at 30℃.The tailoring of amine assembly mitigates the kinetic control of sorption and desorption rates,thus improving sorption and desorption rates at 30℃.PEI-MS sorbents were prepared by employing the cross-linking reaction of PEI and poly(ethylene glycol)diglycidyl ether in emulsion template.Reducing the particle size of PEI-MS sorbents together with appropriate amount of cross linker addition can promote sorption capacity.PEI-MS-0.4 sorbent shows a sorption capacity of 152 mg g-1,maximum sorption and desorption rates of 31.5 mg g-1 min-1 and 27.0 mg g-1 min-1,average sorption and desorption rates of 19.4 mg g-1 min-1 and 26.0 mg g-1 min-1 at 30℃.Compared to 50PEI-MSN sorbent with similar amine loading,PEI-MS-0.4 sorbent shows improved average sorption rate by 111%,improved maximum desorption rate by 123%,improved average desorption rate by 145%and improved working capacity by 129%at 30℃.PEI-MS-0.4 sorbent can achieve effective desorption under pure CO2 with desorption temperature of 120℃(desorption percentage>84%).Increasing the number of sorption sites at the surface of amine films is beneficial for improving maximum sorption rate. |
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