CO2 adsorption onto synthetic activated carbon: Kinetic, thermodynamic and regeneration studies

An activated carbon for CO2 adsorption from flue gas was synthesized using an industrial by-product (coal tar pitch) and furfural. The produced activated carbon possesses a well-developed pore structure and an alkaline character, as testified by the presence of different oxygen containing functional groups on the carbon surface. Adsorption tests have been carried out in lab-scale fixed-bed column, at different temperatures and CO2 concentrations, in order to investigate both kinetic and thermodynamic aspects. Moreover, regeneration studies have been conducted in order to verify the possibility of activated carbon reutilization, to determine its CO2 adsorption capacity within consecutive cycles of adsorption-desorption and to assess the optimal operating conditions for CO2 recovery by desorption. It was established that the synthesized activated carbon has a good CO2 adsorption capacity, likely related to its surface area and composition, as well as to the intrinsic nature of the solid. Adsorption rate increases with CO2 concentration and temperature, even if an increase in temperature significantly reduces the adsorption capacity. Experimental results confirmed that CO2 adsorption is a reversible process and that desorption temperature is the main controlling parameter. It was demonstrated that the regenerated carbon can be used in consecutive adsorption-desorption cycles without any significant loss in its CO2 adsorption capacity. Finally, the most suitable operating set parameters for CO2 recovery has been defined.