关键词:

吸附储氢, 等量吸附热, 密度泛函理论

Abstract: To evaluate the hydrogen adsorption performance of the typical carbon based adsorbents from the aspect of adsorption heat, nonlocal density functional theory（NDFT）,Carnahan-Starling, MBWR equations of state and the mean-field theory are used to determine the bulk density and density profiles of hydrogen molecules within the adsorption space.The adsorption density is obtained from the weighted average of the density profile calculated with NDFT in the width (or radial) direction of adsorption space. The maximum physical adsorption capacities of hydrogen molecules in the close-packing state are used to calculate the isosteric heat of adsorption. The adsorption isotherms at 77—297K with a step of 10K and 1—10MPa with a step of 1kPa are first determined,then,the isosteric heat of adsorption on three typical carbon based adsorbents are ascertained by the adsorbed phase volume and the bulk gas volume in thermodynamic equilibrium during the adsorption process.From the comparisons among the results from the NDFT calculation and experimental data,not only the isotherms of hydrogen adsorption on carbon [HJ]nanotubes have similar figure to those of activated carbon,but also the values of isosteric heat of adsorption on these adsorbents are within the same range.Finally,the measure that the accurate hydrogen adsorption experiments on pure carbon nanotubes should be carried out to verify their physical adsorption performance,and the effective measures for the management of adsorption heat should also be emphasized while considering the cryogenic adsorption of hydrogen in carbon nanotubes.

Key words:

吸附储氢, 等量吸附热, 密度泛函理论