Molecular insights into improved oxygen adsorption: Ag+ and Ce3+ doping in Li-LSX for air separation

Abstract

Pressure swing adsorption (PSA) is a cost-effective and efficient method for oxygen production. It is crucial to improve the adsorption capacity of zeolite adsorbent material to facilitate oxygen production for PSA. Based on the molecular simulation method, the Ag+ and Ce3+ were doped into Lithium-based Low Silica X (Li-LSX) zeolite to enhance the adsorption of O2. The developed adsorption model is in good agreement with the experimental results. Equilibrium parameters including adsorption capacity, heterogeneity, and N2/O2 selectivity were obtained by fitting with the Langmuir-Freundlich model. The results showed that the N2/O2 selectivity of AgLi-LSX with a 30% Ag+ exchange ratio was 3.2% higher compared with Li-LSX, while the adsorption capacity of CeLi-LSX with a 30% Ce3+ exchange ratio was 27.4% greater for O2 than Li-LSX. In addition, the isosteric adsorption heats and distributions of potential energy were simulated to reveal the mechanism of performance enhancement. The adsorption capacity for O2 exhibited a sustained increase trend as the exchange ratio of Ce3+ increased. The findings of this research can guide the development of oxygen-selective adsorbents and reduce the cost of PSA oxygen production.