In this work

porous carbon materials were prepared by using starch as carbon source. The starch first went through polymerization under hydrothermal condition and followed by a KOH activation. Their structures and adsorption performances for CO2 and CH4 were characterized and tested. The isosteric heat of adsorption and the selectivity toward CO2/CH4 were estimated based on the adsorption isotherms

and the effect of carbon material structure on its adsorption properties was also discussed. The results showed that the specific surface area and pore volume of the prepared materials increased as more KOH was used

and the pore size distribution also became wider. The derived carbon material had a high specific surface area of 2972 m2·g-1

the H2O adsorption isotherms of the materials showed an IV-typed isotherm. It was found that the CO2 adsorption capacity of the materials mainly depended on the cumulative pore volume with pore size less than 0.8 nm. That is

the larger the ultramicro pore volume(Vd < 0.8 nm) of the material

the greater the CO2 adsorption capacity at 298 K and 101325 Pa. The CO2 adsorption amount on the C-KOH-1 was 4.2 mmol·g-1 in our work

and the isosteric heat of CO2 adsorption was higher than that of CH4

the selectivity toward CO2/CH4 is in the range of 3.7-4.26. At the same time

the water adsorption isotherms of the materials were also examined and the results showed that the materials were mainly hydrophobic

which can be a potential adsorbent being used in the reality.