(506c) Analyzing the Diffusivity and Adsorption of Nitrogen and Oxygen in Lithiated Zeolite

Nitrogen is an omnipresent gas that is heavily used across a variety of industrial applications. The production of high purity nitrogen is critical for many fields and an important area of scientific research. Cryogenic distillation has been extensively used to separate nitrogen from oxygen based on the differences in their boiling points, however this method has significant production and capital costs. Membrane separations allow for the purification of nitrogen from oxygen via differences in molecular size, however, the molecules are too similar in size to achieve the necessary purity for many applications without a significant number of in-line separators. Adsorption-based separations are an attractive alternative and the focus of this work.

Lithiated zeolite was assessed for the adsorptive based separation of nitrogen from oxygen. Adsorption isotherms were collected and analyzed for both adsorptive uptake and selectivity determination. This data was then used to develop Ideal Adsorbed Solution Theory (IAST) predictions using a freely available software package to determine the spreading pressure and selectivity of nitrogen over oxygen in lithiated zeolite. Additionally, transient data was extracted from the collected adsorption isotherms to determine the diffusivity of nitrogen and oxygen in the adsorbent. This work provides an example of the capabilities of conventional adsorption equipment and how advanced techniques can be utilized to characterize adsorbent materials.