Hydrogen Sulfide-Resistant Bifunctional Catalysts for the Steam Reforming of Methane: Activity and Structural Evolution

Results are presented from studying an iron–nickel catalyst for the steam reforming of methane, synthesized by epitaxial coating on the surface of spherical pellets of commercial γ-Al₂O₃. It is shown the catalyst is resistant to the presence of hydrogen sulfide in a steam–gas mixture. The degree of conversion of methane during reforming is close to equilibrium at a pressure of 2.0 MPa, a temperature of 800°C, a ratio of Н₂О: СН4 = 2: 1, a feedstock hourly space velocity (FHSV) of 6000 h^?1, and a H₂S concentration of 30 ppm. The structural evolution and phase state of the active components of the system are studied via X-ray diffraction analysis, transmission electron microscopy (TEM), and Mössbauer spectroscopy. The formation of paramagnetic iron oxide clusters tightly bound to the structure of the support, and of FeNi₃ iron–nickel alloy particles on the surface of the catalyst, is responsible for the polyfunctional properties of the catalyst, which displays high activity in both the steam reforming of methane and the oxidative decomposition of hydrogen sulfide to elemental sulfur.