反应详情

In general, we start with a wet cerium carbonate which is treated with acetic acid to form a cerium acetate. The cerium acetate is dried and calcined suitably at a temperature of about 425° C. to 450° C. to form a high surface area ceric oxide, CeO2 (HSA ceric oxide). A mixture of 70 mole percent high surface area cerium oxide and 30 mole percent of the cerium acetate is then prepared. This mixture is wet milled with alumina in proportions that will ultimately yield about 50 to 80 weight percent alumina and the balance cerium oxide. Small amounts of other materials such as known oxide stabilizers may be added if desired. The wet mixture is milled for a period of time so as to achieve a substantially uniform mixture of the ceric oxide and alumina and cerium acetate. Some of the cerium acetate dissolves in the water and the solution is adsorbed onto the alumina. Ultimately, a mixture of average particle size of about 0.5 to 1 micron is obtained. The viscosity of the milled slurry may be adjusted if necessary, and the material is then applied as a thin layer to the exhaust gas treatment surfaces of a ceramic or metal monolith configured for the treating of automotive engine exhaust gases.