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Adsorption isotherms of CO2, CO, N2, CH4, Ar and H2 on activated carbon and zeolite LiX up to 1.0 MPa


The adsorption isotherms of CO2, CO, N2, CH4, Ar, and H2 on activated carbon and zeolite LiX were measured using a volumetric method. Equilibrium experiments were conducted at 293, 308, and 323 K and pressures up to 1.0 MPa. The adsorption isotherm and heat of adsorption were analyzed for two pressure regions of experimental data: pressures up to 0.1 MPa and up to 1.0 MPa. Each experimental isotherm was correlated by the Langmuir, Sips, Toth and temperature dependent Sips isotherm models, and the deviation of each model was evaluated. The Sips and Toth models showed smaller deviation from the experimental data of adsorbents than the Langmuir model. Isosteric heats of adsorption were calculated by the temperature dependent Sips model and are presented along with surface loading. From deviation analysis, it is recommended that the isotherm in the proper pressure range be used to appropriately design adsorptive processes.

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Langmuir, Sips, and Toth isotherm parameter (kPa−1)

DQaver :

Adsorbed amount average deviation (%)


Isotherm data number (dimensionless)

K1 :

1st parameters in the temperature dependence Sips model (mol kg−1)

K2 :

2nd parameters in the temperature dependence Sips model (mol kg−1 K−1)

K3 :

3rd parameters in the temperature dependence Sips model (kPa−1)

K4 :

4th parameters in the temperature dependence Sips model (K)

K5 :

5th parameters in the temperature dependence Sips model (dimensionless)

K6 :

6th parameters in the temperature dependence Sips model (K)


Number of data (dimensionless)

n :

Sips isotherm parameter (dimensionless)


Pressure (kPa)

Qst :

Isosteric heat of adsorption, (kJ mol−1)


Adsorbed amount moles, (mol kg−1)

qm :

Langmuir, Sips, and Toth isotherm parameter, (mol kg−1)


Ideal gas constant (J mol−1 K−1)


Temperature (K)


Toth isotherm parameter (dimensionless)


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This work was supported by POSCO (2013 × 037), the Korea Institute of Energy Technology Evaluation and Planning (KETEP: 20118510020030-12-1-000) and the Ministry of Trade, Industry & Energy (MOTIE).

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Correspondence to Chang-Ha Lee.

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Park, Y., Moon, DK., Kim, YH. et al. Adsorption isotherms of CO2, CO, N2, CH4, Ar and H2 on activated carbon and zeolite LiX up to 1.0 MPa. Adsorption 20, 631–647 (2014).

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  • Activated carbon
  • Zeolite LiX
  • Adsorption isotherm
  • Syngas
  • Reforming gas