Effects of MgO and CaO on properties of Ni/γ-Al₂O₃ catalyst for the reforming of methane and steam

Three Ni-based catalysts with or without MgO or CaO promoters were prepared by co-impregnation method and their properties for methane steam reforming to syngas were studied in a fixedbed reactor. Results showed that CaO promoter on Ni-based catalyst had the best performance with 96.95% methane conversion, 68.93% CO selectivity and 73.58% H₂ yield at the condition of n(H₂O)/n(CH₄)/n(N₂)=2.86/1/3.28 with a GHSV 1800h^－1 at 700℃. Results from XRD and H₂-TPR experiments showed that the addition of CaO enhanced the active component NiO, and had the best reducibility and dispersibility. The type of carbonaceous species Cγ, which may cause catalyst deactivation, wasn't found on the Ni-CaO/Al₂O₃ catalyst after 10h reaction by using TGA techniques.