Effect of Adsorbent History on Adsorption Characteristics of MIL-53(Al) Metal Organic Framework

Abstract

Structural transformation of MIL-53­(Al) metal organic framework from large pore to narrow pore form (lp → np) or vice versa is known to occur by adsorption of certain guest molecules, by temperature change or by applying mechanical pressure. In this work, we perform a systematic investigation to demonstrate that adsorbent history also plays a decisive role in the structural transitions of this material (and hence on its adsorption characteristics). By changing the adsorbent history, parent MIL-53­(Al) is tuned into its np domain at ambient temperature such that it not only exhibits a significant increase in CO₂ capacity, but also shows negligible uptake for CH₄, N₂, CO, and O₂ at subatmospheric pressure. In addition, for the high pressure region (1–8 bar), we propose a method to retain the lp form of the sample to enhance its CO₂ uptake