Current research field of hydrogen storage is aimed at synthesis of
materials that would meet the criteria proposed by National Department of
Energy of USA [1].
The active carbons (AC) represent a broad class of adsorbents that are
widely studied for the processes of hydrogen storage [2]. The attractiveness of
AC is explained by large surface area and volume of micropores, possibility of
controlling their structure and low production price.
Microporous AC was prepared by impregnating the nut shells with KOH
in a 1:4 wt./wt. ratio and subsequent microwave activation. The microwave
activation was performed at 700 W for 5 minutes in nitrogen atmosphere.
Adsorption of gases (nitrogen and hydrogen) was measured at 77K. The
activated carbon (AC-2) possesses the best adsorption features with a maximum
capacity of retaining hydrogen of 3.82 wt. %.
To appreciate the specific surface area (S) of activated carbons, BET and
Langmuir models were used. As shown in Table 1, both BET and Langmuir
model, give similar results for nitrogen adsorption.
BET model showed lower values for the parameters obtained from the
adsorption isotherms of hydrogen, while Langmuir model is in a good
agreement with the results obtained from the nitrogen adsorption isotherms.
Table 1. Structure parameters of the activated carbons (AC) obtained by microwave
treatment.

The research leading to these results has received funding from the People Programme
(Marie Curie Actions) of the European Union's Seventh Framework Programme FP7/2007-
2013/ under REA grant agreement no. PIRSES-GA-2013-612484.
1. D.J. Durbin, C. Malardier-Jugroot. International Journal of Hydrogen Energy 38(34) (2013) 14595.
2. Y. Xia, Z. Yang, Y. Zhu. J. Mater. Chem. A 1 (2013) 9365.