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CO2 Adsorption Behavior of Activated Coal Char Modified with Tetraethylenepentamine
- Wang, Xia, Guo, Qingjie
- Energy & Fuels 2016 v.30 no.4 pp. 3281-3288
- adsorption, carbon dioxide, climate, coal, greenhouse gas emissions, hydrochloric acid, industrial applications, models, power plants, silica gel, sorbents, temperature, water vapor
- The climate deterioration problem mainly caused by excessive CO₂ emission from coal-fired power plants has led to heightened concerns, and the reduction of the separation cost of CO₂ 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 CO₂ capture. The effects of the HCl concentration, coal type, adsorption temperature, and activation time of water vapor on CO₂ 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 CO₂ 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 CO₂ capture from coal-fired power plants but also reduced the CO₂ separation cost.