Automobile Exhaust Catalyst Coating Material

As the limitation for the automobile exhaust is getting stricter and stricter all over the world, more advanced activity and thermal stability of automotive catalyst is required to meet the new standard. In present dissertation, foundational studies on the relation among the preparation method, texture and properties of zirconia and ceria zirconia mixed oxides for automotive catalyst coatwash were carried out. The t-ZrO₂ can improved the oxidization activity of propane were observed for the first time. Hydrothermal refluxing method was first applied to prepare high specific surface area CeO₂-ZrO₂ mixed oxides. Systematical investigation on the effect of the preparation parameters on the structure and oxygen storage capacity of CeO₂-ZrO₂ mixed oxides was also made. It was confirmed that the higher pH is advantage to form uniform CeO₂-ZrO₂ solid solution, and improve its oxygen storage characteristics. Hydrothermal refluxing has two sides for ceria zirconia mixed oxides. Only the appropriate refluxing time can supply good oxygen storage capacity and dramatically optimized texture as well to perform its role. The effect of the mole ratio of Ce and Zr and the phase component and structure in the CeO₂-ZrO₂ mixed oxides on its oxygen storage characteristics was also explored. ZrO₂-rich t phase ceria zirconia solid solution was found to be more thermally stable, which make it to be a potential material for closed couple catalyst coatings. And compared to the other composition, 0.4CeO₂·0.6ZrO₂ possesses pure fluorite structure and the most effective capacity to utilize the oxygen storage characteristic of CeO₂. Basing on the results described above, both important coatwash materials for automotive catalyst were prepared and implied to monolith catalyst, which possesses higher activity at low temperature, better three way characteristic and more thermally stable comparing with the commercial catalyst. Combining with other controlling technology, it can meet the Low Emission Vehicle standards.