Dynamic analysis of sorption of hydrogen in activated carbon

Hydrogen storage and adsorption studies in carbon materials have been of great concern in recent years. Hydrogen is thought to be an ideal energy source because of causing no pollutants or greenhouse gases during combustion unlike the fossil fuels. In this study, sorption characteristic of H2 and N2 gases in activated carbon having three different particle sizes were investigated in a temperature range of 303–473 K using a dynamic technique. The experimental procedure consist of introducing a pulse of H2 and N2 on the inlet of a column packed with activated carbon samples and measuring the concentration versus time response peak leaving the other end of the column. Adsorption equilibrium constants were evaluated using the moment analysis of the chromatographic peaks. At 473 K, the adsorption equilibrium constant for H2 on activated carbon having 4.76–0.85 mm particle size (ACI) was found to be 7.92×10-47.92×10-4, whereas it has value of 1.83×10-3m3/kg at 303 K. Heats of adsorption of H2 and N2 on ACI were determined as -4.8-4.8 and -11.6kJmol-1, respectively. The values of heat of adsorption obtained indicate physical adsorption of H2 and N2 gases on the activated carbon samples used.