Study Of CO₂ Adsorption In Flue GAS On Activated Carbon

Global warming, which is mainly caused by CO2, has had a serious effect on our life. Currently we can take a series of measures to control the emission of CO2, including energy structure, energy efficiency and CO2 capture and storage. According to our national conditions and energy structure, CO2 capture may be the practicable and effective method to control CO2 emission. Now, the main methods for CO2 capture are absorption, adsorption and membranes. Among all of the feasible means, adsorption has been widely used because of easy operation, low energy consumption and wide adaptability. Adsorbents used in adsorption are activated carbon, molecular sieves and alumina. Activated carbon has been researched extensively due to its rich source, well-developed pore structure, convenience to regeneration and good adsorption capacity. In this paper, on the dynamic apparatus,263-293 K, 0.5-7.0 MPa, the work aims to study correction of Kelvin equation which is used to describe pore filling and to verify the universality of the corrected Kelvin equation, kinetics model for CO2 adsorption, relationship between adsorption rate and pore structure, effect of SO2 and O2 on CO2 adsorption capacity. Main conclusions of the study are as follows:(1) The experimental data were further confirmed the universality of the corrected Kelvin equation which was corrected by Guojun Yin. And the critical pore size was extended to 0.55-1.44 nm. The results provide theoretical supports for Kelvin equation when it is used to describe CO2 adsorption on activated carbon.(2) Pseudo-first order model, Pseudo-second order model, Elovich model and Avrami model were employed to simulate CO2 adsorption on different activated carbons. The results showed CO2 adsorption kinetics was found to follow Avrami model. What’s more, CO2 adsorption on activated carbon followed physical adsorption and was controlled by film diffusion according to the calculated activation energy Ea and the simulation of W-M model.(3) By exploring the relationship between adsorption rate and pore structure, we concluded that micropore and macropore had some effects on the CO2 adsorption rate, but it was not the crucial factor for the adsorption process. In other words, in the adsorption process, intraparticle diffusion was not the key factor.(4) Through studying the influences of different atmospheres on CO2 adsorption, the results showed that competitive adsorption among CO2, SO2 and O2, led to the descrease of CO2 adsorption capacity.