Influence of pre-oxidization on the characterizations of coal gasification fine slag-derived activated carbons for CO2 capture

Abstract

Coal gasification fine slag (FS)-based activated carbons (ACs) for CO2 capture provided a new method to realize the value-added utilization of FS. Furthermore, pre-oxidation treatment of carbonaceous materials is one of the most efficient possibilities to obtain developed pore structure of activated carbons to enhance the CO2 adsorption capacity. In this study, four types of oxidizing agents (HNO3, NaClO, H2O2, and air) carefully modified the coal gasification fine slag residual carbon (RC) to fix the oxygen content at about 12 wt%, 15 wt%, and 18 wt%. The samples were characterized by XPS, volumetric sorption analyzer, SEM, Raman spectroscopy, TEM, TG, and TGMS. Results suggested that the specific surface area and total pore volume of the ACs were observed to increase after oxidation. The types of oxygen-containing groups also affected the pore structure of the ACs. The results showed that the content of OCO groups were the most predominant factors for high surface area, and the CO group could hinder the development of pore structure. The ACs facilitated by RC oxidation by HNO3 had a high CO2 storage capacity of 12.4 % at 30 °C and a fast adsorption rate, around 86 % of CO2 uptake occurring in a span of 1 min.