Tracing the influence of extra‐framework cations on N2 and O2 adsorption characteristics under plateau environment by GCMC simulations

Abstract

AbstractPressure swing adsorption (PSA) coupling with molecular sieves, especially the Li low silica X (Li‐LSX) zeolite, adsorption technology is widely used in O2 generator instrument under plateau environment. However, the studies of N2 and O2 adsorption and separation properties on zeolite under plateau environment are still obscure to date. In this work, the influence of N2 and O2 adsorptions on the LSX zeolites in harsh plateau environment (3000 ‐ 5000 m) was investigated by Grand Canonical Monte Carlo (GCMC) simulations. Three kinds of LSX zeolites including Li‐LSX, Ag‐LSX and LiCa‐LSX were taken into consideration. The simulation results indicate that the adsorption amount and affinity of both N2 and O2 elevate with the increasing altitude and following the order of Ag‐LSX > Li‐LSX > LiCa‐LSX. The N2 adsorption was dominated over all three LSX zeolites, leaving O2 much easier to permeate through the LSX zeolites. The isosteric adsorption heat and adsorption density results further proved that N2 and O2 have extremely different adsorption strategies. Moreover, the selectivity and separation coefficients based on ideal adsorption solution theory (IAST) were calculated from GCMC simulations, and the results indicate Ag‐LSX has the highest diffusion selectivity and the steadiest diffusion coefficient among the three LSX zeolites. These findings may contribute to the N2/O2 separation molecular sieves for plateau applications by tailoring the LSX zeolite with different extra‐framework cations.