Activated carbons were produced from corn straw lignin using H3PO4 as activating agent. The optimal activation temperature for producing the largest BET specific surface area and pore volume of carbon was 500?degrees C. The maximum BET specific surface area and pore volume of the resulting carbon were 820?m2g1 and 0.8?cm3g1, respectively. The adsorption isotherm model based on the Toth equation together with the Peng-Robinson equation of state for the determination of gas phase fugacity provide a satisfactory representation of high pressure CO2, CH4 and N2 adsorption. The kinetic adsorption results show that the breakthrough difference between CO2 and CH4 is not obvious, indicating that its kinetic separation performance is limited.