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Simulations of the thermal effects during adsorption cycles are valuable tools for the design of efficient adsorption-based systems such as gas storage, gas separation and adsorption-based heat pumps. An analytical representation of the measured adsorption data over the wide operating pressure and temperature swing of the system is necessary for the calculation of complete mass and energy conservation equations. In Part 1, the Dubinin-Astakhov (D-A) model is adapted to model hydrogen, nitrogen, and methane adsorption isotherms on activated carbon at high pressures and supercritical temperatures assuming a constant microporous adsorption volume. The five parameter D-A type adsorption model is shown to fit the experimental data for hydrogen (30 to 293 K, up to 6 MPa), nitrogen (93 to 298 K, up to 6 MPa), and for methane (243 to 333 K, up to 9 MPa). The quality of the fit of the multiple experimental adsorption isotherms is excellent over the large temperature and pressure ranges involved. The model's parameters could be determined as well from only the 77 K and 298 K hydrogen isotherms without much reducing the quality of the fit.

We present a detailed comparison between experimental adsorption measurements and the excess adsorption predicted by the Ono−Kondo equations. The study was done for high-pressure adsorption of methane above the critical point on microporous adsorbents. The experimental adsorption isotherms of CH4 on the activated carbon CNS-201 as well as others are compared with theory over the temperature range 243−333 K and for pressures up to 16 MPa. Extension of the model to zeolites is also discussed.

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Hydrogen adsorption measurements on Al-, Cr-, and Zn-based metal-organic frameworks (MOFs) and single-walled carbon nanotubes (SWNTs) are presented. The measurements were performed at temperatures ranging from 77 to 300 K and pressures up to 50 atm using a volumetric approach. The maximum excess adsorption at 77 K ranges from 2.3 to 3.9 wt % for the MOFs and from 1.5 to 2.5 wt % for the SWNTs. These values are reached at pressures below 40 atm. At room temperature and 40 atm, modest amounts of hydrogen are adsorbed (<0.4 wt %). A Dubinin-Astakhov (DA) approach is used to investigate the measured adsorption isotherms and to retrieve energetic and structural parameters. The adsorption enthalpy averaged over filling is about 2.9 kJ/mol for the MOF-5 and about 3.6-4.2 kJ/mol for SWNTs.