Static and dynamic hydrogen adsorption on Pt/AC and MOF-5

Hydrogen adsorption has been studied by static and dynamic methods on activated carbon (AC), platinum/activated carbon (Pt/AC), metal organic frameworks (MOF-5), and Pt/AC_MOF-5.The static method showed that all of adsorbents used in this study exhibited a Langmuir (type I) adsorption isotherm at 77 K and a linear function of hydrogen partial pressure at 298 K. The dynamic method produced breakthrough curves, indicating (i) slow rate of hydrogen diffusion in the densely packed activated carbon and Pt/AC beds and (ii) high rate of hydrogen diffusion in the loosely packed bed with large MOF-5 crystallites. Temperature variable adsorption resulted in the higher hydrogen uptake on Pt/AC than other adsorbents. The results suggested that temperature variable adsorption enhanced the hydrogen storage process by (i) initiating hydrogen dissociation at high temperature and (ii) facilitating spillover at low temperature on Pt/AC.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► The dynamic method produced breakthrough curves of which slopes reflected H2 diffusion rate. ► The temperature variable adsorption enhanced the H2 dissociative at high temperature and facilitated the subsequent spillover during cooling.