Preparation of activated carbons and their adsorption properties for greenhouse gases: CH4 and CO2

Three kinds of activated carbons were prepared using coconut-shell s as carbon precursors and characterized by XRD, FT-IR and texture property test. The results indicate that the prepared activated carbons were mainly amorphous and only a few impurity groups were adsorbed on their surfaces. The texture property test reveals that the activated carbons displayed different texture properties, especially the micropore size distribution. The adsorption capacities of the activated carbons were investigated by adsorbing CH₄, CO₂, N₂ and O₂ at 25 °C in the pressure range of 0-200 kPa. The results reveal that all the activated carbons had high CO₂ adsorption capacity, one of which had the highest CO₂ adsorption value of 2.55 mmol/g at 200 kPa. And the highest adsorption capacity for CH₄ of the activated carbons can reach 1.93 mmol/g at 200 kPa. In the pressure range of 0-200 kPa, the adsorption capacities for N₂ and O₂ were increased linearly with the change of pressure and K-AC is an excellent adsorbent towards the adsorption separation of greenhouse gases.