(554a) High-Purity Oxygen Production Using Silver Exchanged Titanosilicates (Ag-ETS-10)

High-purity (>99%) oxygen is required in many medical and industrial applications such as pharmaceutical and aerospace applications. Producing oxygen with purity of higher than 95% from atmospheric air (78% N₂, 21% O₂ and 1% Ar) is challenging because of similar physical properties of oxygen and argon such as the molecule size and the boiling point. Adsorption separation techniques are economically preferable to conventional cryogenic distillation of O₂/Ar for small and medium scale applications but a limited number of commercial adsorbents are selective toward O₂/Ar. Recent multi-component breakthrough experiments in our laboratory have shown that silver exchanged titanosilicates (Ag-ETS-10) have the potential to separate these gases based on their thermodynamic affinities. This opens up the possibility of developing processes for high purity O₂ separations.

In this work, adsorption isotherms of N₂, O₂, and Ar on Ag-ETS-10 extrudates have been measured utilizing a volumetric apparatus and described using a Langmuir isotherm. In order to validate the large-scale performance of the adsorbent, single, binary, and ternary breakthrough profiles were obtained using a laboratory scale dynamic column breakthrough apparatus. These experiments have been described by discretising mass and energy balances using the finite volume technique. The model could predict the experimental profiles to a high level of precision. Various Pressure/Vacuum swing adsorption (P/VSA) cycle configurations including simple Skarstrom cycle and more complicated VSA cycles were simulated using mathematical models to maximize O₂ purity and recovery. Both 95%/5% O₂/Ar and dry air feed were considered in the simulations and a rigorous multi-objective optimization was conducted to maximize O₂ purity and recovery which indicated the ability of Ag-ETS-10 to separate ultra-high purity O₂ with good recovery. Effect of different operating parameters on O₂ purity and recovery and rigorous multi-objective optimization results to maximize oxygen productivity and minimize energy consumption of the P/VSA cycles (while meeting the purity-recovery constraint) were studied. The comparison of the simulation results with single-column experiments will be presented.