Hydrogen adsorption in metal- organic frameworks (MOFs): Effects of adsorbent architecture

Abstract

In this work, the effect of metal-organic framework (MOF) structure of MOF-5 was investigated in hydrogen adsorption based on the degree of solvent exploitation and/or sample preparation procedures. In this regard, the characterization analyses of FT-IR, BET and PXRD pattern of MOF-5 samples were used to compare their architectures with different specific surface area and porosity in hydrogen adsorption. The results show that the pore size distribution of samples is related to the main peaks in the micropores, mesopores and macropores regions. One can found that the adsorption of hydrogen at room temperature (296 K) is controlled by diffusion of adsorbed hydrogen inside the pores of the crystals. Larger diffusivities at a given pressure are expected due to diffusion in macroporous. The values of heats of adsorption on prepared sample are calculated as 3.68 and 12.45 kJ mol−1 for meso and macroporous regions, respectively. These results are suggesting that weak interactions between the adsorbed hydrogen molecules and MOF crystals is occur in mesoporous regions and the adsorption into macroprous which are filling in high temperature shows strong interaction.