Catalytic performance of Co–Fe mixed oxide for NH3-SCR reaction and the promotional role of cobalt
Co-modified iron oxide (Co-FeOx) catalysts were prepared by a citric acid method for the low temperature NH3-SCR of NO in the presence of O2. The results show that the amount of Co obviously influences the activity and stability of the Co-FeOx catalyst for the NH3-SCR reaction, and when the molar ratio of Co/Fe is 0.2 (Co–Fe-0.2), NO is completely converted at 170 °C and the operation temperature window reaches 210 °C. After eight reaction cycles, the NO conversion and operation temperature window are hardly changed, and the presence of Co can markedly increase both its SO2 and H2O resistance ability. It was found that doping Co into α-Fe2O3 results in the formation of CoFe2O4 crystals, and increases the relative content of Fe3+, surface oxygen amount and oxygen activity. The Co–Fe-0.2 catalyst has the smallest particle size and the largest surface area, and possesses higher reducibility and catalytic activity for NO oxidation to NO2 than α-Fe2O3, resulting in an improvement of the “fast-SCR reaction”.