Advances in modification of commercial activated carbon for enhancement of CO2 capture

A novel and inexpensive method of modification of textural properties of commercial activated carbons for enhancement of CO2 capture was investigated. The commercial activated carbons FPV, WG-12 and CWZ-22 were applied as a starting material, and KOH and K2CO3 were used as modification agents. The modification temperature was varied over the range of 600 degrees C to 850 degrees C, and the ratio of modification agent to carbon from 1 to 4 was studied. The adsorption of CO2 was examined on all the activated carbons at temperature 25 degrees C up to pressure of 1 bar. A close correlation between the CO2 adsorption and the pore size of activated carbons was revealed. The activated carbon exhibiting the CO2 adsorption of 5.8 mmol/g under pressure of 1 bar and temperature of 0 degrees C was successfully obtained as a result of modification by KOH. After selecting of the best sorbents, the adsorption of CO2 was performed in the temperature range from 25 degrees C to 160 degrees C and under pressure up to 35 bar. The measured adsorption isotherm of CO2 was fitted to the numerous adsorption equations. The Sips model was found to be the best. The isosteric heats of adsorption were also calculated.