Grand Canonical Monte Carlo Simulation Study of Hydrogen Storage in Ordered Mesoporous Carbons at 303 K

Abstract

Results of Grand Canonical Monte Carlo (GCMC) simulations of hydrogen storage at 303 K in ordered mesoporous carbons (OMCs) which are inverse replicas of cubic Im3m silica are presented. Of the ones investigated here, the highest gravimetric total storage of hydrogen (ca. 2 wt% at P = 22 MPa and 303 K) was observed for the OMC replica of the cubic Im3m material which was characterized by the largest lattice parameter and internal pore radius of the carbon sphere (a = 9.98 nm and Rint ≈ 3.0 nm). However, the corresponding volumetric density of hydrogen did not exceed 17 kg H2/m3. The highest excess storage was observed for a threshold value given approximately by a ≈ 7.98 nm and Rint ≈ 2.4 nm. Above this value, the excess storage and volumetric density of hydrogen did not change.The adsorption was dominated by the bulk storage, with the adsorbent serving as a tank whose storage properties were governed by the available space for hydrogen molecules (bulk storage) and not by physical adsorption (i.e. densifi...