Ni/Al2O3 promoted by CeO2, CeO2-La2O3, and CeO2-ZrO2 supported on cordierite monoliths for methane steam reforming

Promotion of Ni-based catalysts supported on cordierite monoliths was investigated for methane steam reforming. First, cordierite was coated by ɣ-Al₂O_3, and then the catalyst components were deposited by successive wet impregnation, obtaining: NiAl/cordierite; NiCeAl/cordierite; NiCeLaAl/cordierite and NiCeZrAl/cordierite. The monolithic catalysts were characterized by adherence test, Scanning Electron Microscopy with Energy-Dispersive X-ray Spectroscopy (SEM-EDX), N₂ physisorption, Temperature-Programmed Reduction (TPR), CO chemisorption, as well as by in situ and operando Raman spectroscopy. The catalyst layer showed very good adherence and distribution of the components over the cordierite surface. The catalysts presented high activity between 600 and 800 °C at a H₂O/CH₄ molar ratio=1.5, except for NiCeAl/cordierite, which obtained lower methane conversion, associated with its lower nickel dispersion. The catalysts showed high stability under extreme conditions for carbon deposition (600 °C and H₂O/CH₄=1), over 90 h on stream. Raman spectroscopy revealed the presence of oxygen vacancies, which may be increased during ceria reduction, highlighting the potential of these catalysts to enhance the resistance to deactivation by carbon deposition in long-term tests.