4. Conclusion
At elevated temperatures, the mechanism of CO2 adsorption on the amine-impregnated AC was a combination between chemical and physical adsorption. The amine impregnation caused a reduction of micropore surface areas by 52% in the AC-MEA and 11% in the AC-DEA. The greater reduction in the micropore surface area of the AC-MEA suggested that MEA molecules caused more partial and full blockages of the inner pores of the AC than the DEA molecules. The greater reduction of pore surface area in the AC-MEA resulted in lower amounts of adsorbed CO2 and a lower
breakthrough capacity at all temperatures investigated. The increased blockage of the pores in the AC-MEA also resulted in more hindered mass transfer and longer desorption times. Even
though the desorption time can be reduced by increasing the desorption temperature, the desorption temperature for the C-MEA must be kept lower than 170 C because the MEA degraded
at this temperature. Therefore, AC-DEA is recommended over AC-MEA for CO2 adsorption at the elevated temperatures.