Adsorption behavior of hydrogen sulfide in the channels of Li-ABW zeolite: A study using density functional theory

Abstract

H₂S is a highly toxic, flammable gas that poses risks to health, the environment, and industrial infrastructure. Zeolites, with their high porosity, offer a promising solution for its removal. This study employs density functional theory (DFT) to investigate the adsorption behavior of H₂S within the Li-ABW zeolite framework, focusing on the synergistic effect of co-adsorbed water molecules. Six distinct systems were modeled: empty Li-ABW zeolite, half and full filled Li-ABW with H₂O or H₂S molecules, and equally filled zeolite with H₂S and H₂O molecules. Detailed analysis of geometric, energetic, and electronic properties reveals that the presence of water significantly enhances H₂S adsorption in Li-ABW. Increased bond lengths between H₂S and the zeolite framework suggest possible dissociative adsorption, while weakened H₂S-zeolite interaction compared to H₂O-zeolite interaction indicates facile H₂S desorption. Furthermore, charge transfer analysis and HOMO/LUMO plots highlight stronger interactions and a more balanced electron distribution in the co-adsorbed system. Interestingly, the presence of water minimizes structural deformations of the zeolite framework while facilitating the formation of additional hydrogen bonds, potentially further promoting H₂S desorption through water extraction. These findings demonstrate that Li-ABW zeolite, particularly in conjunction with water molecules, exhibits remarkable potential for efficient and selective H₂S adsorption, offering promising avenues for practical applications in gas sweetening and industrial gas purification. In order to realize this potential, further investigation into the effects of solvents and cation exchange is necessary, which are outlined for future research.