Flexible Dual Fe-based Catalyst: MIL-53(Fe) Loaded with Deep Eutectic Solvent for Discontinuous Selective Oxidation of H₂S

Deep eutectic solvent (DES) as the guest molecule and flexible Metal-organic framework (MOF) as the supporting material can be used to provide an efficient catalyst: flexible dual Fe-based DES@MOF, which can efficiently remove H₂S in discontinuous removal process (100–180°C). The materials were characterized by XRD SEM, FT-IR, BET, XPS, TG, CV and Py-FTIR. According to the result, MOF (MIL-53(Fe)) incorporating 30 wt% DES (ChCl/FeCl₃) exhibited the best H₂S removal performance at 180°C, with the H₂S removal capacity of 2527 mg mL⁻¹ (3744 mg g⁻¹). And the H₂S removal capacity reduced by 9% after two cycles of thermal regeneration. The process of desulfurization includes two stages: catalytic oxidation and adsorption, which are determined by the Fe³⁺ in DES and the structural characteristics, such as the aggregation of mesopores, respectively. For MIL-53(Fe), FeOOH as an intermediate and Lewis acid sites also played a catalytic role. Elemental sulfur was the predominant product with a small amount of sulfate. Both elemental sulfur and DES can induce the flexible deformation of MOF as the guest molecule to relieve the passivation of catalyst.