Different Approach to Estimation of Hydrogen-Binding Energy in Nanospace-Engineered Activated Carbons

Binding energy between adsorbent and adsorbate strongly affects the mechanism of adsorption. Porous systems are usually characterized by a distribution of this energy, which is not easy to determine experimentally. A coupled experimental-simulation procedure to estimate binding energy directly from experimental adsorption isotherms is proposed. This new approach combines experimental information (pore size distribution determined from nitrogen adsorption at 77 K) and numerical data (grand canonical Monte Carlo simulations of adsorption in pores) to explain an influence of binding energy on adsorption isotherms. The procedure has been validated by analysis of hydrogen adsorption in a series of carbons activated with KOH:C ratio varying from 3 to 6. These carbons show high capacity of hydrogen storage both at 80 and 303 K (115 gH2/kgC and 23 gH2/kgC at p = 100 bar, respectively, for carbon activated during 1 h at T = 790 C (T = 1361 K) with KOH:C ratio equal to 3, having the surface area above 2600 m2/g, 0....