| 摘要 |
<p>An auxiliary catalyst for purifying exhaust gas, characterized as comprising a granular aluminum oxide carrier and, carried thereon, a composite oxide comprising (a) cerium and (b) at least one element selected from the group consisting of zirconium, yttrium, strontium, barium and a rare earth element, and having a specific surface area of 40 m2/g or more as measured after firing, an oxygen storage capacity at 400°C of 10 micromoles or more and the capacity at 700°C of 100 micromoles or more. The utilization of cerium oxide used in conventional auxiliary catalysts as a cerium-containing composite oxide has been found to improve the resistance to heat and suppress the lowering of performance capabilities owing to the deterioration by heat. Further, the above auxiliary catalyst can withstand the usage for a long period of time as a practical catalyst, as it exhibits great values as specified above for specific surface area and oxygen storage capacity.</p> |
