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

A series of gold catalysts supported on Fe 2 O 3 −TiO 2 with various iron contents were prepared. A FeO x −TiO 2 support was prepared via incipient-wetness impregnation with aqueous solution of Fe(NO 3 ) 3 on TiO 2 . A gold catalyst with a nominal loading of 1 wt % was prepared by deposition−precipitation at pH 7 and 65 °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/TiO 2 catalyst had high CO and H 2 oxidation activity. However, CO conversion decreases obviously when the temperature reaches above 80 °C, because of the competition of hydrogen oxidation on the catalysts. In this study, FeO x was added to Au/TiO 2 to suppress H 2 oxidation without sacrificing the activity for CO oxidation. Adding a suitable amount of Fe 2 O 3 on Au/TiO 2 could enhance CO conversion to a higher extent and suppress H 2 oxidation. In the highly active gold-supported catalysts, the amorphous nature of Fe 2 O 3, along with TiO 2, not only enhanced electronic interaction but also stabilized the nanosized gold particles, thereby enhancing the catalytic activity of CO oxidation toward a higher extent.