Effect of chemical functionalization groups on Zr₆-AzoBDC to enhance H₂, CH₄ storage and CO₂ capture: a theoretical investigation

Grand canonical Monte Carlo (GCMC) simulation combined with the ideal adsorbed solution theory (IAST) and a statistical method were utilized to investigate the effect of functional groups on zirconium oxide based metal-organic frameworks (MOFs) Zr₆-AzoBDC (Zr₆A) for the gases (H₂, CH₄) adsorption property and CO₂/CH₄ selectivity under low pressure. The results showed that phenyl groups containing nitrogen (pyridine, pyrimidine) and thiophene group enhance the gas affinity with MOFs, therefore increasing both gravimetric and volumetric uptake. In addition, this behavior can also cause significantly improved selective capture of CO₂ from CO₂/CH₄ gas mixtures. Among functional groups studied, the sulfonic acid group can potentially improve CH₄, CO₂ uptake and H₂ isosteric heat of adsorption. These findings would play a vital role in designing new materials toward gas adsorption properties. (paper)