Low-Temperature H₂S Removal from Gas Streams over γ-FeOOH, γ-Fe₂O₃, and α-Fe₂O₃: Effects of the Hydroxyl Group, Defect, and Specific Surface Area

Samples of γ-FeOOH, γ-Fe2O3, and α-Fe2O3 were prepared by calcining a γ-FeOOH precursor at selected temperatures and tested for low-temperature H2S removal. The prepared materials were characterized by powder X-ray diffraction, N2 adsorption–desorption measurement, transmission electron microscopy, and in situ Fourier transform infrared spectroscopy of pyridine adsorption. The results suggested that the oxygen vacancies, specific surface areas, and surface hydroxyl groups of the iron oxides have significant influence on the desulfurization performance at room temperature. In H2S adsorption experiments, the sample calcined at 250 °C (FE-250) showed the highest performance, reaching 53% of the maximum sulfur capacity, and desulfurization precision at 25 °C.