Hydrogen adsorption measurements have been carried out at different temperatures (298 K and 77 K) and high pressure on a series of chemically activated carbons with a wide range of porosities and also on other types of carbon materials, such as activated carbon fibers, carbon nanotubes and carbon nanofibers. This paper provides a useful interpretation of hydrogen adsorption data according to the porosity of the materials and to the adsorption conditions, using the fundamentals of adsorption. At 298 K, the hydrogen adsorption capacity depends on both the micropore volume and the micropore size distribution. Values of hydrogen adsorption capacities at 298 K of 1.2 wt.% and 2.7 wt.% have been obtained at 20 MPa and 50 MPa, respectively, for a chemically activated carbon. At 77 K, hydrogen adsorption depends on the surface area and the total micropore volume of the activated carbon. Hydrogen adsorption capacity of 5.6 wt.% at 4 MPa and 77 K have been reached by a chemically activated carbon. The total hydrogen storage on the best activated carbon at 298 K is 16.7 g H2/l and 37.2 g H2/l at 20 MPa and 50 MPa, respectively (which correspond to 3.2 wt.% and 6.8 wt.%, excluding the tank weight) and 38.8 g H2/l at 77 K and 4 MPa (8 wt.% excluding the tank weight).

Authors thank financial support from MCYT (Project PPQ2003-03884), Generalitat Valenciana (Project GV04A-608) and EU (HyTRAIN MC RTN-512443). F. Suárez-García thanks MCYT for his contract “Juan de la Cierva” and M. Jorda-Beneyto thanks MEC for her Ph.D. fellowship. Authors also thank Dr. F. Lamari-Darkrim for the measurement of hydrogen isotherm on sample KUA5 up to 50 MPa.

11 pages, 10 figures, 1 table.-- Available online on Nov 1, 2006.

Peer reviewed