Optimum conditions for adsorptive storage

Bhatia, Suresh Kumar ; Myers, Alan L. (2006) Optimum conditions for adsorptive storage Langmuir, 22 (4). pp. 1688-1700. ISSN 0743-7463

Full text not available from this repository.

Official URL: http://pubs.acs.org/doi/abs/10.1021/la0523816

Related URL: http://dx.doi.org/10.1021/la0523816


The storage of gases in porous adsorbents, such as activated carbon and carbon nanotubes, is examined here thermodynamically from a systems viewpoint, considering the entire adsorption-desorption cycle. The results provide concrete objective criteria to guide the search for the "Holy Grail" adsorbent, for which the adsorptive delivery is maximized. It is shown that, for ambient temperature storage of hydrogen and delivery between 30 and 1.5 bar pressure, for the optimum adsorbent the adsorption enthalpy change is 15.1 kJ/mol. For carbons, for which the average enthalpy change is typically 5.8 kJ/mol, an optimum operating temperature of about 115 K is predicted. For methane, an optimum enthalpy change of 18.8 kJ/mol is found, with the optimum temperature for carbons being 254 K. It is also demonstrated that for maximum delivery of the gas the optimum adsorbent must be homogeneous, and that introduction of heterogeneity, such as by ball milling, irradiation, and other means, can only provide small increases in physisorption-related delivery for hydrogen. For methane, heterogeneity is always detrimental, at any value of average adsorption enthalpy change. These results are confirmed with the help of experimental data from the literature, as well as extensive Monte Carlo simulations conducted here using slit pore models of activated carbons as well as atomistic models of carbon nanotubes. The simulations also demonstrate that carbon nanotubes offer little or no advantage over activated carbons in terms of enhanced delivery, when used as storage media for either hydrogen or methane.

Item Type:Article
Source:Copyright of this article belongs to American Chemical Society.
ID Code:2749
Deposited On:08 Oct 2010 11:15
Last Modified:11 May 2012 11:31

Repository Staff Only: item control page