Direct air carbon capture based on metal carbonate modified solid amine adsorbent
Metal carbonate-doped and polyethyleneimine(PEI)functionalized composite adsorbents were prepared using SBA-15 molecular sieve as the carrier through the impregnation method.The adsorbents were characterized,and the effects of metal carbonate type and loading,as well as PEI loading on CO2 adsorption performance were investigated.The reusability of the composite adsorbents was also evaluated.The experimental results show that the optimal CO2 adsorption performance of the K5P50SBA adsorbent is achieved with K2CO3 loading of 5%(w)and PEI loading of 50%(w).After 180 min of adsorption,at a temperature of 35℃,CO2 volume fraction of 400×10-6,and air flow rate of 100 mL/min at atmospheric pressure,the CO2 adsorption capacity of K5P50SBA was 1.92 mmol/g.Doping a moderate amount of K2CO3 in SBA-15 helps enlarge the pore size of the adsorbent so that the diffusion of CO2 is accelerated within the adsorbent,Meanwhile,the alkaline sites on the surface of K2CO3 can synergistically interact with PEI,increasing the adsorption capacity for CO2.After 100 cycles of use,the adsorption capacity of K5P50SBA decreased to 1.61 mmol/g,9.03%lower than before,and exhibits good reusability.
direct air capturesolid amine adsorbentmetal carbonate modificationadsorption-desorption cycle
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