Structural and textural properties of Fe₂O₃/γ-Al₂O₃ catalysts and their importance in the catalytic reforming of CH₄ with H₂S for hydrogen production

Newer catalysts for the methane reforming with H₂S are designed, which are based on Fe₂O₃/γ-Al₂O₃, nanocrystalline γ-Al₂O₃ supports, and 1.0 to 6.0 wt% Fe. The main phases are identified as hematite and γ-Al₂O₃, with sizes of about 2-4 nm. The structural features are characterized by X-ray diffraction, Rietveld's Refinement and Radial Distribution Function analysis. The textural properties of these catalysts are determined by N₂ sorption and surface fractal dimension calculations. Also, the electronic states are inferred by Mössbauer and UV-Vis (diffuse reflectance) spectroscopies. The activity of Fe₂O₃/γ-Al₂O₃ catalysts in the methane reforming is tested in a fixed bed type reactor. Further calculations indicate that Fe₂O₃/γ-Al₂O₃ catalysts go through a charge transfer decrease, which depends on the iron content, i.e., from 1.08 to 0.88 eV; Mössbauer spectroscopy reveals that Fe³⁺ ions adopt a tetrahedral coordination, which coincides with their higher activity for hydrogen production, with respect to catalysts having octahedral coordination. The specific surface area of these catalysts is about 84 m² g^-1, with a mean pore diameter of 2.5 nm. A mechanism for the methane reforming with H₂S is proposed herein.