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.