Surface treatment effects on CO oxidation reactions over Co, Cu, and Ni-doped and codoped CeO2 catalysts

• Co, Cu, and Ni-doped and codoped CeO2 catalysts were prepared.
• CO oxidation was tested over as-prepared and thermal-treated the catalysts.
• Cu-contained CeO2 commonly showed higher catalytic activity after thermal treatment in N2 atmosphere.
• Charge balance of doped metals appears to play a major role.

We doped (M) and codoped (MM’) Co, Cu, and Ni into CeO2 support, and tested their gas-phase CO oxidation performance by temperature-programmed reaction mass spectrometry for the as-prepared, thermal H2- and N2-treated samples. Additionally, fundamental characteristics of doped CeO2 were revealed by transmission electron microscopy, optical microscopy, X-ray diffraction crystallography, UV–visible absorption, Brunauer–Emmett–Teller (BET) surface area measurements, and temperature-programmed reduction experiments. The CO oxidation performance was greatly improved upon metal-doping and thermal pre-treatment in H2 and N2 condition. It was found that Cu-contained samples showed higher CO performance while Ni, Co and CoNi-doped samples showed poor performances. The T10% (the temperature at 10% CO conversion) was lowered by 140 °C upon Cu-doping. Upon N2 (or H2-thermal treatment), the T10% was lowered by 80 and 110 °C for Cu-doped and undoped CeO2 catalyst, respectively. Overall, this study provides deeper information of surface treatment effects useful to development of efficient catalysts.

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