Synthesis of microporous hollow spherical polystyrene carbons for the highly efficient CO2 adsorption and selectivity

Carbon materials with economic and high adsorption capacity attract much attention to reducing fossil fuel and industrial CO2 emissions. For this purpose, porous hollow spheres with high surface area and micropore volume, morphologically resembling fullerene or soccer balls, were first produced from the synthesized polystyrene by hydrothermal and conventional activation. The highest micropore volume and BET surface area were found in PS-hydroHCl with 0.61 cm3/g and 1481 m2/g, respectively. The CO2 adsorption capacities of PS-hydroHCl at 0 and 25 °C were relatively high and were obtained as 6.25 and 3.62 mmol/g, respectively. It was determined that all microporous spheres were influential in the isosteric heat of adsorption range of 17–26 kJ/mol, that is, typical CO2 physical adsorption. It has been found that hydrothermally synthesized PS-hydro and PS-hydroHCl contain higher amounts of oxygen than PS and PSHCl produced according to the conventional method. In addition, CO2/N2 selectivity at 25 °C, PS-hydroHCl, was three times more effective than PSHCl. As a result, it can be said that the synthesis of porous hollow microspheres is simple, and the starting material (polystyrene) is cheap and abundant; high CO2 adsorption and effective CO2/N2 selectivity will be promising for industrial applications.