Synthesis of activated carbon from high-ash coal gasification fine slag and their application to CO2 capture

Abstract

Coal gasification fine slag (FS) is an inevitable by-product in the gasification process. The preparation of activated carbons (ACs) can realize the value-added utilization of FS. In this work, FS with about 70 % ash yield was prepared to ACs through KOH activation and then used to CO2 capture. The residual carbon (RC) obtained from acid-treatment of FS was also to fabricate ACs. The ACs had interconnected macropores and micro-mesopores structure. The ACs were characterized using adsorption of nitrogen, SEM, TEM, Raman spectra, XRD, and TG. The optimized FS-based AC had a specific surface area of 1187 m2/g and a pore volume of 0.89 cm3/g. Furthermore, at the same ash yield, the surface area of FS-based ACs was larger than that of RC-based ACs. Experimental evidence presented that abundant metallic elements were leached using the impregnation method to mix KOH and raw material. Additionally, they could react with the carbon matrix and catalyzed the activation reactions to promote the development of pore structure. The ACs showed well CO2 adsorption performance. FS2−800-60 exhibited a high CO2 capture of 4.01 and 2.53 mmol/g at 0 and 25 °C. Additionally, the ACs showed a high adsorption rate that CO2 adsorption uptake almost reached constant values within two minutes. All these results illustrate that ACs prepared from FS could be high efficiency and cost-effective adsorbent for CO2 capture.