Effect of Ion Exchange on the Adsorption of Steam Methane Reforming Off-Gases on Zeolite 13X

Abstract

In this study, we have modified a material with enhanced adsorption capacity and kinetics toward nitrogen to apply in a layered pressure swing adsorption (PSA) unit for separation of steam methane reforming (SMR) off-gases. The adsorption properties of the base zeolite 13X (sodium form) were modified by changing the cation with lithium, barium, and calcium. The best adsorbent was selected by determining the difference in adsorption capacity measured by breakthrough experiments with (0.01 and 0.25) bar of partial pressure of nitrogen (effective capacity in a PSA unit) and the crystal diffusivity [at (303 and 323) K]. The ion exchange of zeolite 13X with Ba2+ and Ca2+ will favor nitrogen adsorption, with the calcium-modified sample having better performance (higher adsorption capacity). Adsorption equilibrium and kinetics of N2, H2, CO, CH4, and CO2 on ion-exchanged zeolite 13X-Ca were studied at (303 and 323) K in the pressure range (0 to 7) bar. At 1 bar of N2, the loading of the 13X-Ca was 0.447 mol·kg−1...