CO2 Capture with Activated Carbons Prepared by Petroleum Coke and KOH at Low Pressure

In this study, high surface area porous carbons were synthesized by chemical activation using petroleum coke as the precursor and KOH as the activation agent. The pore structure of the as-synthesized activated carbons was characterized by nitrogen adsorption, and their CO2 sorption capacities were measured by a magnetic suspension balance at 1 and 10 bar, respectively. The effects of activated carbon preparation parameters (preheating temperature, preheating time, activation time, heating rate during the pyrolysis, and particle size of the precursor) on porous texture, CO2 adsorption capacity, and CO2/N-2 selectivity of the activated products were investigated. It has been found that at 1 bar, the CO2 adsorption capacity is determined by the micropore contribution, i.e., the ratio between micropore surface area and Brunauer-Emmett-Teller (BET) surface area of the sorbents, while at 10 bar, CO2 adsorption capacity is related to the BET surface area of the activated products. The maximum CO2 adsorption uptake of 15.1 wt% together with CO2/N-2 selectivity of 9.4 at 1 bar were obtained for a sample activated at 700 degrees C indicating its high potential in the capture of CO2.