Ionic liquid-integrated MOF-808 for thiophene capture: Insights from Monte Carlo simulations and cyclic stability tests

Metal-organic frameworks (MOFs) have garnered significant attention in adsorption desulfurization due to their high density of adsorption sites and permanent porosity. However, despite the abundant adsorption sites in Zr-based MOF-808, its relatively large pore channels and volumes may limit the adsorption efficiency for smaller molecules such as thiophene. Incorporating room-temperature ionic liquids (rILs) into MOF structures offers a promising strategy to address a key limitation of rILs-their high viscosity at ambient conditions, which often restricts mass transfer rates during liquid-liquid extraction. In this study, an IL-modified MOF-808 was synthesized to assess its performance in desulfurization. Characterization results confirmed that the rILs successfully infiltrated the MOF-808 pores without changing its framework integrity. Adsorption properties for thiophene in ILs/MOF-808 composites were investigated through Grand Canonical Monte Carlo (GCMC) simulations alongside experimental adsorption measurements conducted at 298 K. Further Monte Carlo (MC) simulations demonstrated that the presence of ILs enhanced the affinity for thiophene and increased the number of accessible adsorption sites within the composite. The adsorption capacity of ILs/MOF-808–20 remained stable over four adsorption-regeneration cycles using n-octane as the solvent, providing a potentially feasible solution for deep desulfurization.