| dc.description.abstract | Massive gold was a stable and precious metal; it is not an active catalyst. In nanosize scale,the nano-gold supported on the metal oxide could oxidize CO at low temperature and produced carbon dioxide. CO was a toxic, colorless and tasteless gas; it is produced by the fuel without complete oxidation. The most extensively studied reaction in the history of heterogeneous catalysis is becoming increasingly important in the context of cleaning air and lower automotive emissions. The reaction is important for environment protection. When gold is deposited as nanoparticles on metal oxides by impregnation, co-precipitation and deposition-precipitation (DP) techniques, it exhibits surprisingly high catalytic activity for CO oxidation at a temperature as low as 200 K. The activity of gold catalysts also depends on support, preparation method and condition. The promoters were added in Au/TiO2 to change the support properties, including electronic effect and geometric effect.
In this study, the effects of promoter such as Cu and Co were investigated. The support was prepared by incipient-wetness impregnation with aqueous solution of nitrate salt. TiO2 was supplied by Evonik-Degussa Company (P-25). A series of Au catalysts was prepared by deposition-precipitation (DP) method and the pH value was 7. The catalysts were characterized by inductively-coupled plasma-mass spectrometry (ICP-MS), temperature programming reduction (TPR), X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and X-ray photoelectron
spectroscopy (XPS). The reaction was carried out in a fixed bed reactor with a feed containing 1% CO in air at WHSV=120,000 ml/h g and WHSV=180,000 ml/h g.
High gold dispersion and narrow size distribution was obtained by DP method. Two different promoters were added in Au/TiO2, which were also enhanced the activity on CO
oxidation. Cu and Co have different promotive effect. Au/5% CuOx-TiO2 was the best catalyst in a series of Au/CuOx-TiO2 and the Au/3% CoOx-TiO2 was the best catalysts in a series of Au/CoOx-TiO2. Au/3% CoOx-TiO2 had better stability than Au/5% CuOx-TiO2 catalyst. In this
study, we have successfully prepared the catalysts at suitable content with very high activity on CO oxidation.
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