A new preparation method of Au/ferric oxide catalyst for low temperature CO oxidation

A new preparation method of Au/α-Fe₂O₃ catalyst for CO oxidation reaction was proposed in this paper. The method includes only a simple modification of the conventional coprecipitation method, adding HAuCl₄ solution after the growth of iron hydroxide grain to a certain size, but significantly influenced the catalytic activity in the reaction. In the characterization study, XRD (X-ray diffractometer) analysis, TEM (transmission electron microscope) observation, and N₂ adsorption measurement showed similar results among the samples calcined at the same temperature, but the effect of the preparation method appeared in the CO adsorption measurement among the samples calcined at 200 °C. Catalysts having high CO adsorption ability also performed well in CO oxidation tests. The CO adsorption and oxidation studies indicated that the proposed preparation method results in stable and effective loading of Au, compared to the conventional coprecipitation method. In the CO oxidation test, the catalyst prepared by the proposed mixing scheme achieved complete CO conversion for more than 3000 h at 25 °C, space velocity 100,000 h^-1, and 500 ppm CO. The selectivity for the CO oxidation was confirmed using reformed gas containing excess H₂. In addition, the NO reduction reaction was favored over CO oxidation by the catalyst. Thus, we were able to load Au on the α-Fe₂O₃ effectively and demonstrate its potential as an environmental catalyst.