Au/FeOx-TiO2 Catalysts for the Preferential Oxidation of CO in a H2 Stream

A series of gold catalysts supported oil Fe2O3-TiO2 with various iron contents were prepared. A FeOx-TiO2 support was prepared via incipient-wetness impregnation with aqueous solution of Fe(NO3)(3) on TiO2. A gold catalyst with a nominal loading of 1 wt % was prepared by deposition-precipitation at pH 7 and 65 degrees C. The catalysts were characterized by X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. The catalytic performance of these catalysts were investigated by preferential oxidation of carbon monoxide in hydrogen stream (PROX). The reaction was conducted in a fixed-bed microreactor with a feed of CO:O-2:H-2:He = 1:1:49:49 (volume ratios). A limited amount of oxygen was used. Gold catalysts have been reported to be efficient catalysts for the PROX reaction to reduce CO concentration to <50 ppm. The Au/TiO2 catalyst had high CO and H-2 oxidation activity. However, CO conversion decreases obviously when the temperature reaches above 80 degrees C, because of the competition of hydrogen oxidation on the catalysts. In this study, FeOx was added to Au/TiO2 to suppress H-2 oxidation without sacrificing the activity for CO oxidation. Adding a suitable amount of Fe2O3 on Au/TiO2 could enhance CO conversion to a higher extent and suppress H-2 oxidation. In the highly active gold-supported catalysts, the amorphous nature of Fe2O3, along with TiO2, not only enhanced electronic interaction but also stabilized the nanosized gold particles, thereby enhancing the catalytic activity of CO oxidation toward a higher extent.