In-situ activated ultramicroporous carbon materials derived from waste biomass for CO2 capture and benzene adsorption

With the development of economy and the improvement of environmental protection awareness, more pollutants such as CO2 and benzene in coal-fired fuel gas need be controlled. Here, a novel preparation strategy of in-situ activated porous carbons based on tobacco stem was proposed. The C-OOH and C-OH groups in tobacco stem could coordinate with zinc ions through hydrothermal process to form Zn-hydrochars. The presence of Zn in Zn-hydrochars (MPC-1) provides an additional 144% ultramicropore volume, contributing to superior CO2 uptake capacity of 209 and 146 mg g(-1) under 1 bar at 0 and 25 C respectively. The selectivity of CO2/N-2 on MPCs is 16.4-26.6 at 1 bar and 25 C. Based on experimental data and molecular simulation, we found that CO2 uptake and separation decreasing with the pore widths increasing. The oxygen and nitrogen atoms can increase electronegativity of carbon framework and provide more CO2 active sites, thereby enhancing CO2 capture and selectivity. Besides, the MPC-1 exhibits superior benzene adsorption capacities of 97 mg g(-1) and 202 mg g(-1) at concentration of 10 ppm and 50 ppm, respectively. The molecular simulation shows that MPCs facilitate the benzene adsorption at a low concentration, even in environments/indoor environments with the sub-ppm range.