Methoxy-Modified MOF-5: A MOF-5 Framework Prepared by a Mixed Ligand Approach

In this paper, a series of MOF-5 frameworks based on a mixed diacid composition, i.e. 2-methoxyterephthalic acid and terephthalic acid, was synthesized by using a mixed-ligand approach. The MOF-5 structure remains intact when the 2-methoxyterephthalate concentration is in the range of 075 mol-%. By using this approach, the H2 uptake capacity of MOF-5, at 77 K and 1 bar, can be improved by 10% at a 2-methoxyterephthalate concentration of 75 mol-% (1.45 wt.-% vs. 1.32 wt.-% for MOF-5). This improvement is due to an enhanced isosteric heat of H2 adsorption on a statistically determined number of sites.