Small bead auto exhaust catalyst.

摘要

@ Alumina particle catalysts which can be used for auto emission control and especially as a three-way catalyst have increased performance. The alumina particles which are preferably spheroids have a low compacted bulk density of about 20 to 36 pounds per cubic foot and a smaller size on the order of less than 2.6 mm for the preferred spheroids. The spheroid embodiment also has a high crush strength. Because of the small size the ratio of the geometric surface area to the bulk volume (GSA/BV) is at least about 14 cm²/cm³. These alumina particles are impregnated with a catalytically-effective amount of one or more platinum group metals such as platinum, palladium or rhodium and additional promoters can also be added. In the preferred embodiment the alumina particles have a GSA/BV ratio of from about 17 to 25 cm²/cm³ for substantially improved performance.