Alumina-supported CuO–CeO₂–ZrO₂ Catalysts for CO Oxidation – Preparation and Characterization

Abstract

The effect of catalyst samples, prepared by different methods, having the composition (CuCe_5.17Zr_3.83O_x/γ-Al₂O₃ (20 wt%) was studied in the present work for carbon monoxide (CO) oxidation. Cu(NO₃)₂3H₂O was used as a precursor for the preparation of the catalysts. Catalysts were prepared by four methods: co-impregnation, citric acid sol–gel, urea nitrate combustion and urea gelation co-precipitation methods. Prepared catalysts were characterized by BET specific surface area, X-ray diffraction, thermogravimetic analysis/differential scanning calorimetry (TGA/DSC) and scanning electron microscopy (SEM) techniques. The oxidation of CO was carried out in a tubular fixed bed reactor at atmospheric pressure and at temperature ranging from ambient to 250°C. A fixed weight (100 mg) of the catalyst was taken and 2.5% CO in air at a total feed rate of 60 ml/min was used in the reactor. It was observed that the performance of the catalysts in CO oxidation was influenced by the preparation methods. The catalyst prepared by sol–gel method that calcined at 500°C exhibited excellent activity for CO oxidation with total conversion at 210°C. The ranking order of the alumina supporting CuO–CeO₂–ZrO₂ catalysts was as follows: sol–gel > co-impregnation > urea gelation > urea nitrate combustion. The four catalysts prepared did not show deactivation of catalytic activity for 50 h of continuous runs.

Key words:

• CO emission
• CO oxidation
• Catalytic activity
• Catalyst preparation methods