MOFs for the Storage of Oxygen

Oxygen storage is vital for many applications including medical devices, emergency first responders, space and sea exploration, semiconductor fabrication, and scientific laboratory uses.  In many of these areas, there is a desire to increase the amount of oxygen storage without greatly increasing the pressure or volume required.  Metal-organic frameworks have been widely studied for the storage of gases such as hydrogen and CO₂ but very little has been done for oxygen storage.  Oxygen isotherms from 1 to 30 bar were measured at various temperatures on several MOFs.  A Toth isotherm model fit the data well and was used to determine isosteric heats of adsorption.  High-pressure oxygen isotherms up to 140 bar at 25 °C showed much higher adsorbed quantities for some MOFs when compared to the zeolite NaX and a high surface area carbon.  After undergoing 50 adsorption and desorption cycles, the MOFs showed no loss in oxygen adsorption capacity.  Based on the high capacities and oxygen stability, MOFs are promising adsorbents for the storage of oxygen.