Preparation And Investigation On Properties Of Copper Base Ceria-zirconia Composite Oxide Catalyst Of Bi Or Mo

Since the industrial revolution, fossil energy bring unprecedented in the industrial development and material wealth, but also give human caused unbearable climate change and environmental pressures. In view of the existing conditions, motor vehicle exhaust emission problems have become increasingly prominent, in the urban air pollution, the pollution from exhaust emission is more and more serious, which has become the major source of pollution after soot pollution. Motor vehicle exhaust gas cleaning catalyst is the most effective means to control emissions and reduce pollution. The European and American catalysts are mostly used Pt, Pd, Rh and other precious metals as the active component, which has a actual application already. However, there are many existing problems to comprehensive promotion, such as shortage of resources and expensive precious metals. Therefore, it is important to develop a cheap and efficient non-noble metal catalysts to instead of noble metal catalyst.Under this background conditions, in this paper, we used Cu as a catalyst active component, which is relatively cheap and easy to acquire. The catalysts was prepared with the Ce-Zr-O, Ce-Zr-Bi-O and Mo/CeO₂-ZrO₂ composite oxides as the carrier by incipient-wetness impregnation method, their performance were investigated in a condition of a simulated motor vehicle exhaust, the catalysts structure were characterized with XRD and SEM means to study. In addition, the structure and properties of catalyst were linked in some extent. The main research contents and experimental results are as follows:,1. We used NH₃·H₂O-(NH₄)2CO₃ as the precipitator, the series of Ce-Zr-Bi-O(CZB) composite oxides were prepared by the co-precipitation method, and Cu/CZB catalysts was prepared with them as the carrier. The effects of different Ce, Zr and Bi molar ratio and preparation methods on the CZB composite oxides were investigated. The results showed: when CZB carrier was used co-precipitation method, the Cu/Ce0.65Zr0.35Bi0.06O₂ catalyst with Ce:Zr:Bi molar ratio of 0.65:0.35:0.06, and the content of Cu of 5% showed the better catalytic performance. The light-off temperatures for NO and CO were 238 and lower than 100 respectively, CO could be completely converted above 175 , and NO could be completely converted above 325 . Bi was added to form a single and stable cubic structure of the Ce-Zr-Bi solid solution, crystal size achieved a nanometer scale level, while highly dispersed CuO particles was formed on the surface of catalyst, so the performance of the catalyst has improved.2. Catalytic properties of Cu/Mo/CeO₂-ZrO₂ composite oxide catalyst was studied. The Cu/Mo/CeO₂-ZrO₂ catalyst with Ce:Zr molar ratio of 0.65:0.35,the content of Mo of 6% and the content of Cu of 5% showed high catalytic performance. When the air/fuel ratio was 1.4, the light-off temperatures for CO, C₃H₆ and NO were 103 , 247 and 242 respectively, CO, C₃H₆ and NO could be completely converted above 189 , 429 and 315 . The results of XRD and SEM characterization showed, Mo was added to make the catalyst particles be smaller and form a single and stable cubic structure of the solid solution. After aging at high temperature, the catalyst particles also have good dispersion and regular shape.