Adsorption Selectivity of CO2/N2 on Nanoporous Active Carbons

Some polymers, including waste polymers, are very good precursors for synthesis of porous carbons. Data for adsorption of CO2 and N-2 at temperatures in the range from 0 degrees C to 60 degrees C and pressures ranging from 0.005 to 1.2 bar and 0.001 to 1.2 bar for CO2 and N-2, respectively are presented for one ordered mesoporous and five microporous activated carbons obtained from polymers. Adsorption isotherms of CO2 and N-2 were approximated by means of virial equation and used to determine its coefficients. The first virial coefficient was used to determine the Henry's constants for CO2 and N-2 adsorption at temperatures from 0 degrees C to 60 degrees C, then applied for calculation of adsorption selectivity of CO2 over N-2 for the carbons studied. It was established that the value of Henry's constant for CO2 adsorption is an order of a magnitude larger than the corresponding value of Henry's constant for N-2 adsorption. High adsorption selectivity value obtained on the basis of these constants for CO2 compared to N-2 indicate much stronger interaction of CO2 with a carbon surface than that of N-2. This would indicate that the nanoporous carbons under studies can be readily applied for adsorption of CO2, including CO2 adsorption from a stream of flue gas containing nitrogen.