CO_2 Capture with Activated Carbons Prepared by Petroleum Coke and KOH at Low Pressure

摘要

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 CO_2 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, CO_2 adsorption capacity, and CO_2/N_2 selectivity of the activated products were investigated. It has been found that at 1 bar, the CO_2 adsorption capacity is determined by the micropore contribution, i.e., the ratio between mi- cropore surface area and Brunauer-Emmett-Teller (BET) surface area of the sorbents, while at 10 bar, CO_2 adsorption capacity is related to the BET surface area of the activated products. The maximum CO_2 adsorption uptake of 15.1 wt% together with CO_2/N_2 selectivity of 9.4 at 1 bar were obtained for a sample activated at 700 ℃ indicating its high potential in the capture of CO_2.