Abstract:
Two typical carbon based materials were employed to incorporate with metal organic frameworks (MOFs) for enhancing hydrogen adsorption performance. 1% activated carbon and graphene sheets were added within the solution for solvo-thermally synthesizing MIL-101(Cr) composites. Adsorption models and isosteric heat of hydrogen adsorption were studied through structural characterization, micromorphology observation and adsorption equilibrium of hydrogen. The results show that there are 41.1% and 17.4% increment of the maximum hydrogen adsorption capacity on sample (AM-01) incorporated with activated carbon AX-21 and GM-02 with graphene oxide (GO), respectively, when comparing those on MIL-101(Cr) under 77.15 -87.15 K and 0-6 MPa. The Toth equation had the highest accuracy when comparing with Langmuir equation and Langmuir-Freundlich equation. The mean relative errors between the experimental data on AM-01 and GM-02, and those predicted by Toth equation were 0.55% and 0.41% at 77.15 K, respectively. The isosteric heat of hydrogen adsorption on AM-01 and GM-02 were 2.96-8.64 kJ⋅mol
−1 and 3.06-8.57 kJ⋅mol
−1, respectively. These results indicate that adsorption capacity of hydrogen can be increased via incorporation GO or activated carbon with larger specific surface areas, and Toth equation is suitable for analyzing adsorption equilibrium.