Au/FeOx-TiO₂ catalysts for the preferential oxidation of CO in a H₂ stream

A series of gold catalysts supported on 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 °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:O₂:H2: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 H₂ 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, FeOx was added to Au/TiO₂ to suppress H₂oxidation 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 H₂ 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.