Influence of cobalt on the performance of Pt/CeO2 for CO-PROX at low temperature: reducing the energy of the Pt–O–Ce bond

Abstract

Cerium oxide-supported platinum nanoparticles are widely used in the CO-PROX reaction. Due to expense and rarity, developing synthetic routes that reduce the platinum load and improve the performance of catalysts is essential. A rod-shaped ceria was used as the support, and a series of PtCo_x/CeO₂-r catalysts with constant low Pt loading of 0.21 wt% were prepared by a co-impregnation method. Combined with the performance using different atomic ratios and characterizations, the catalysts presented strong interaction among Pt, Co and Ce at Co/Pt = 9 and showed the best catalytic performance, making a CO conversion increase of 18.0% at 80 °C but a decrease in the best conversion temperature of 90 °C to 80 °C, as compared with the Pt/CeO₂-r catalysts. The enhanced activity of PtCo₉/CeO₂-r was attributed to the synergistic effect of Pt–Co–Ce and reducing the Pt–O–Ce bond energy, which promoted the redox cycle via the Mars–van Krevelen mechanism. It is helpful in reducing the reaction temperature, widening the temperature window and improving the selectivity of CO₂. When the concentration of CO was 10 000 ppm, and the WHSV was 30 000 mL g⁻¹ h⁻¹, the optimal conversion of the catalyst could reach 96.6%, and the optimal conversion temperature was 80 °C.