CO2 Adsorption Behavior of Activated Coal Char Modified with Tetraethylenepentamine

The climate deterioration problem mainly caused by excessive CO 2 emission from coal-fired power plants has led to heightened concerns, and the reduction of the separation cost of CO 2 is essential to realize the industrial application of adsorption technology. The activated char was obtained by passing water vapor through a reactor while pyrolyzing coal at 650 °C, which was further pore-expanded using HCl. Then, the pore-expanded activated char was impregnated with tetraethylenepentamine (TEPA) for the preparation of amine-modified solid sorbents for CO 2 capture. The effects of the HCl concentration, coal type, adsorption temperature, and activation time of water vapor on CO 2 adsorption were investigated in a fixed-bed reactor, and the regenerability, kinetics, and deactivation rate during the adsorption process for sorbents were also studied. The saturated adsorption capacity of 3.38 mmol/g was obtained for 10 wt % TEPA-modified Ordos coal activated char (PE6-E120-TEPA10%) at 60 °C. After 10 adsorption–desorption cycles, the adsorption capacity for PE6-E120-TEPA10% was 3.19 mmol/g, which was a drop of 5.6%. The experimental breakthrough curve for PE6-E120-TEPA10% was well-fitted by the Avrami–Erofeyev deactivation model, the deactivation rate of which was significantly slower than that of TEPA-modified MCM-41 and silica gel (Gel). At the initial breakthrough adsorption stage, the CO 2 adsorption rate for PE6-E120-TEPA10% was rapid and then the rate significantly decreased; the external diffusion adsorption was the rate-controlling step. PE6-E120-TEPA10% not only realized effective CO 2 capture from coal-fired power plants but also reduced the CO 2 separation cost.