Molecular insights into preferential N₂ adsorption on zeolite 13X via total neutron scattering

Abstract

Total neutron scattering (TNS) has emerged as a powerful experimental method for characterising structural properties of liquids confined at nanoscale in porous materials, yet its application to studying room-temperature gas adsorption remains relatively unexplored. This work investigates the feasibility and sensitivity of TNS in detecting subtle structural responses for adsorption of gases including N₂, O₂, simulated Air, and CO₂ in zeolite 13X, under conditions typical of pressure swing adsorption (1 and 5 bar) utilised in medical oxygen concentrators (MOCs). Experimental results illustrate the capability of TNS to detect minor structural alterations induced by gas adsorption, thereby validating its potential as an insightful analytical method. Although the observed changes confirm known molecular interactions and adsorption behaviours, the precise molecular-level interpretation and mechanistic insights will predominantly derive from subsequent advanced molecular simulations. Future research will prioritise the development of quantitative TNS approaches through refined modelling protocols, aiming to accurately describe the spatial distribution of adsorbed gas molecules within zeolite frameworks. Thus, this work positions TNS not merely as a supportive technique but as a critical approach for deepening our fundamental understanding of molecular interactions of fluids confined in porous systems.