The document discusses the use of metal-organic frameworks (MOFs), specifically MIL-100(Cr) and MIL-101(Cr), for the adsorption of CO2 and CH4, highlighting their advantages such as high surface area and tunable pore size. It provides a comparison of adsorption models, including Langmuir, Freundlich, and Temkin, indicating that Langmuir model parameters fit experimental data well. Additionally, it concludes that the synthesis method significantly impacts the maximum loading of MIL-101.

1. Jin Wai Goh, Yoona Choung, Aloysius Davin Oetomo
School of Chemical & Biomolecular Engineering, Georgia Institute of Technology
Linearization of Adsorption Models
Methods & Theories
Introduction
• CO2 and CH4 are most common greenhouse gases emitted.
• Adsorbing using zeolites and activated carbons, but cost of
regeneration process is expensive.
• Turn towards metal-organic frameworks (MOFs), particularly
MIL-100(Cr) and MIL-101(Cr)
• Extremely high surface areas
• Crystalline open structure
• Tunable pore size
• Catalysis, gas storage, liquid-phase separation
References
1. Llewellyn, P.L.; Bourrelly, S.; Serre, C.; Vimont, A.; Daturi, M.; Hamon, L.; De Weireld, G.; Chang, J.S.;
Hong, D.Y.; Kyu Hwang, Y.; Hwa Jhung, S. High Uptakes of CO2 and CH4 in Mesoporous Metal–
Organic Frameworks MIL-100 and MIL-101. Langmuir, 2008, 24(14), pp.7245-7250.
2. Dada, A.O.; Olalekan, A.P.; Olatunya, A.M.; Dada, O. Langmuir, Freundlich, Temkin and Dubinin–
Radushkevich isotherms studies of equilibrium sorption of Zn2+ unto phosphoric acid modified rice husk.
Journal of Applied Chemistry, 2012, 3(1), 38-45.
3. Temkin, M.I.; Pyzhev, V. Kinetics of ammonia synthesis on promoted iron catalysts. Acta physiochim.
URSS, 1940, 12(3), 327-356.
4. Aharoni, C.; Ungarish, M. Kinetics of activated chemisorption. Part 2.—Theoretical models. Journal of
the Chemical Society, Faraday Transactions 1: Physical Chemistry in Condensed Phases, 1977, 73, 456-
464.
5. Munusamy, K.; Sethia, G.; Patil, D.V.; Rallapalli, P.B.S.; Somani, R.S.; Bajaj, H.C. Sorption of carbon
dioxide, methane, nitrogen and carbon monoxide on MIL-101 (Cr): volumetric measurements and
dynamic adsorption studies. Chemical engineering journal, 2012, 195, 359-368.
6. Ruthven, D.M. Principles of adsorption and adsorption processes. John Wiley & Sons, 1984.
7. Zhang, Y.; Su, W.; Sun, Y.; Liu, J.; Liu, X.; Wang, X. Adsorption Equilibrium of N2, CH4, and CO2 on
MIL-101. Journal of Chemical & Engineering Data, 2015, 60(10), 2951-2957.
Results
Conclusions
Adsorption Isotherm Parameters
of CH4 and CO2 on MIL-100 and MIL-101
n=1 n=3
∆H(kJ/mol) 21.77 20.386
• Langmuir, Freundlich, and Temkin models described the adsorption of CO2 and CH4
on MIL-100(Cr) and MIL-101(Cr) relatively well (R2 > 0.97).
• The Langmuir model had the smallest distribution of deviation of the linearized
experimental loading to the fitted loading over the adsorption pressure.
• The uniform isosteric heat of adsorption supported the Langmuir model, which
assumed constant amount of energy of adsorption.
• The adsorption of CH4 and CO2 on MIL-100 and MIL-101 are monolayer
adsorption.
• In the Langmuir model, the synthesis method of MIL-101 has a greater effect on the
max loading parameter than the adsorption constant.
Langmuir Isotherm Parameters
CH4 CO2
MIL-
100
MIL-
101
MIL-
100
MIL-
101
nm
(mmol/g)
13.32 23.92 21.65 51.55
K (MPa-1) 0.3103 0.2072 0.7086 0.2891
R2 0.9944 0.9990 0.9907 0.9964
Freundlich Isotherm Parameters
CH4 CO2
MIL-
100
MIL-
101
MIL-
100
MIL-
101
K 2.844 3.976 7.737 11.09
m 1.460 1.434 1.870 1.566
R2 0.9872 0.9888 0.9795 0.9718
Temkin Isotherm Parameters
CH4 CO2
MIL-
100
MIL-
101
MIL-
100
MIL-
101
bT 837.1 514.6 490.6 236.7
AT 3.327 2.496 6.149 3.379
R2 0.9539 0.9678 0.9886 0.9833
Literature Langmuir Isotherm Parameters7
CH4 CO2
MIL-101 MIL-101
nm (mmol/g) 8.708 22.91
K (MPa-1) 0.257 0.349