Important factors on carbon dioxide reforming of methane over nickel-based catalysts

Some factors such as catalyst, temperature, space velocity, feed CO ₂/CH₄ ratio, H₂O and/or O₂ addition, have been examined for stable operation of carbon dioxide reforming of CH ₄ (CDR) in a fixed-bed reactor under atmospheric pressure. The Ni/Ce-ZrO₂/ θ-Al₂O₃ catalyst showed high activity and stability under all the conditions employed compared with Ni/MgAl₂O₄. This seems to be due to strong interactions between NiO and support and relatively abundant mobile oxygen species in the Ce-ZrO₂ layer: the former would suppress carbon formation step and the latter would activate the carbon elimination step. The carbon deposition over the catalysts in CDR was drastically reduced with a slight increase of feed CO₂/CH₄ ratio or the addition of H₂O in feed. The oxidation of CH₄ and/or steam reforming of CH₄ occurred simultaneously with carbon dioxide reforming of CH₄, where drastic change of a H₂/CO ratio was observed, when the feed was composed of CH₄, CO₂, H₂O and/or O₂.