Synthesis of zeolite-casted microporous carbons and their hydrogen storage capacity

Zeolite-casted microporous carbons (ZMiPCs) were synthesized using the replica casting method. The ZMiPC were also treated chemically by H3PO4 (A-ZMiPC) or KOH (B-ZMiPC) impregnation, to investigate the effect of the acceptor-donor interaction on the hydrogen storage behaviors. The presence of functional groups of the modified ZMiPC surfaces was confirmed by X-ray photoelectron spectroscopy. The total acidity of the carbon surfaces was determined using the Boehm titration method. The microstructure was characterized by X-ray diffraction. The N-2/77 K adsorption/desorption isotherms were analyzed to characterize specific surface area, pore volume, and pore size distribution of the samples. The capacity of hydrogen adsorption was evaluated using a pressure-composition-temperature apparatus at 298 K/100 bar. From these results, the specific surface areas and micropore volume of ZMiPC increased more than two fold compared to the zeolite template. Meanwhile, the textural properties of A-ZMiPC and B-ZMiPC were decreased by the chemical treatments. Consequently, the largest hydrogen storage was obtained on A-ZMiPC, even though their textural properties had decreased, due to a charge induced dipole interaction between the modified carbon surface and hydrogen molecules. (C) 2012 Elsevier Inc. All rights reserved.