Hydrogen adsorption in mesoporous carbons
Department of Chemical and Biomolecular Engineering, Tulane University, New Orleans, Louisiana, United States Applied Physics Letters
(Impact Factor: 3.3).
12/2004; 85(21):4887 - 4889. DOI: 10.1063/1.1827338
The hydrogen adsorption of mesoporous carbon materials with different mesostructures, surface areas, and pore volumes has been investigated. Experimental results indicate that the hydrogen adsorption capacities are dominantly related to their surface areas. A hydrogen adsorption capacity of 1.78 wt % was obtained at 77 K and ambient pressure of 850 mm Hg (0.11 MPa) for the mesoporous carbon with a surface area of 2314 m 2/ g .
Available from: Kaisheng Xia
- "As for the hydrogen storage at 77 K, physisorption mechanism is dominant and H 2 uptake is governed by the structures of host material. Several literatures showed that a tight relationship existed between total surface area and hydrogen adsorption density of porous material   . At the same time, many studies revealed that the micropores (<2 nm) or the even smaller pores are essential for hydrogen storage [3,12,13,21–24]. "
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ABSTRACT: Activation of mesoporous carbon CMK-3 with CO2 for hydrogen storage was studied. Huge structure and texture changes emerged for the activated CMK-3 based on the characterization by using XRD, TEM and nitrogen adsorption at 77 K. The ordered mesoporous structure of CMK-3 gradually became disorder and its specific surface area and volume of pores especially micropores were enhanced remarkably. Hydrogen sorption measurement showed that the activation led to an obvious increase of the H2 sorption capacity of CMK-3. The maximum H2 uptake of 2.27 wt% at 77 K and 1 bar was obtained for the sample activated at 1223 K for 8 h. The small pores with the diameter smaller than 1 nm contributed greatly to the H2 uptake, and were confirmed more effective than other pores for hydrogen storage.
Available from: Keith Mark Thomas
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ABSTRACT: There is considerable interest in hydrogen adsorption on carbon nanotubes and porous carbons as a method of storage for transport and related energy applications. This investigation has involved a systematic investigation of the role of functional groups and porous structure characteristics in determining the hydrogen adsorption characteristics of porous carbons. Suites of carbons were prepared with a wide range of nitrogen and oxygen contents and types of functional groups to investigate their effect on hydrogen adsorption. The porous structures of the carbons were characterized by nitrogen (77 K) and carbon dioxide (273 K) adsorption methods. Hydrogen adsorption isotherms were studied at 77 K and pressure up to 100 kPa. All the isotherms were Type I in the IUPAC classification scheme. Hydrogen isobars indicated that the adsorption of hydrogen is very temperature dependent with little or no hydrogen adsorption above 195 K. The isosteric enthalpies of adsorption at zero surface coverage were obtained using a virial equation, while the values at various surface coverages were obtained from the van't Hoff isochore. The values were in the range 3.9-5.2 kJ mol(-1) for the carbons studied. The thermodynamics of the adsorption process are discussed in relation to temperature limitations for hydrogen storage applications. The maximum amounts of hydrogen adsorbed correlated with the micropore volume obtained from extrapolation of the Dubinin-Radushkevich equation for carbon dioxide adsorption. Functional groups have a small detrimental effect on hydrogen adsorption, and this is related to decreased adsorbate-adsorbent and increased adsorbate-adsorbate interactions.
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