Catalytic Activity of Iron Oxides Supported on γ-Al₂O₃ for Methane Oxidation

Abstract

Three kinds of catalysts of goethites supported on γ-Al₂O₃ (Fe/γ-Al₂O₃), SiO₂-Al₂O₃ (Fe/SiO₂-Al₂O₃) and SiO₂ (Fe/SiO₂) were investigated in terms of the catalytic activity of methane oxidation. The specific surface areas of these catalysts were larger in common than the area of goethite with no supports. The Fe/γ-Al₂O₃ catalyst has the highest performance in the low-temperature activity of methane oxidation which started at 623 K and completed at 923 K. When the Fe-content in Fe/γ-Al₂O₃ was increased, the formation of goethite was observed by the X-ray analyses and the activity of this catalyst increased up to 6 mol%. After the catalytic methane oxidation at 823 K, it was observed that goethite in Fe/γ-Al₂O₃ transformed to hematite which has been known as an active iron oxide in methane oxidation. The activity of Fe/γ-Al₂O₃ was enhanced by the addition of sodium up to the Na-content of 5 mol% although it descended above the content due to the decrease of the specific surface area of the catalyst.