Adsorption and Hydrogen Storage
|
|
|
Conventional storage of large amounts of hydrogen in its molecular form is difficult and expensive because it requires employing either extremely high pressures as a gas or very low temperatures as a liquid. The desire to store hydrogen with sufficient efficiency to allow its use in stationary and mobile fueling applications is spurring a worldwide effort in new materials development. The Department of Energy, in its Year 2010 guidelines, has set performance targets for on-board automobile storage systems to have densities of 60 mg H2/g (gravimetric) and 45 g H2/L (volumetric). Given that these are system goals, a practical material will need to have higher capacity when the weight of the tank and associated cooling or regeneration system is considered. The size and weight of these components will vary substantially depending on whether the material operates by a chemisorption or physisorption mechanism. In the latter case, metal-organic frameworks (MOFs) have recently been identified as promising adsorbents for H2 storage, although little data are available for their sorption behavior at saturation, a critical parameter for gauging the practicality of any material. We report sorption data collected for seven MOF materials at 77 K which leads to saturation at pressures between 25 and 80 bar with uptakes from 2.0 to 7.5 wt %. H2 saturation uptake in MOFs correlates well with surface area, and contrary to a widely held belief, viable volumetric densities in highly porous structures can indeed be achieved.
Recent Leading Publications:
Exceptional H-2 saturation uptake in microporous metal-organic frameworks,
A. G. Wong-Foy, A. J. Matzger, O. M. Yaghi, J. Am. Chem. Soc., 2006, 128, 3494-3495.
Determination of the hydrogen absorption sites in Zn4O(1,4-benzenedicarboxylate)3
by single crystal neutron diffraction, E. Spencer, J. A. K. Howard, G. McIntyre,
J. Roswell, O. M. Yaghi, Chem. Comm., 2006 (3), 278-280.
Characterization of H2 binding sites in prototypical metal-organic frameworks
by inelastic neutron scattering, J. L. C. Roswell, J. Eckert, O. M. Yaghi,
J. Am. Chem. Soc., 2005, 127, 14904-14910.
Gas adsorption sites in a large-pore metal-organic framework, J. L. C. Roswell,
E. Spenser, J. Eckert, J. A. K. Howard, O. M. Yaghi, Science, 2005, 309, 1350.
Metal-organic frameworks as new materials for hydrogen storage, N. Rosi, M.
Eddaoudi, D. Vodak, J. Eckert, M. O'Keeffe, O. M. Yaghi, Science, 2003, 300,
1127.
|
|
