SPHEROIDAL ALUMINA PARTICLES AND CATALYSTS EMPLOYING THE PARTICLES AS A SUPPORT

摘要

ABSTRACT OF THE DISCLOSURESpheroidal alumina particles have a combinationof high macroporosity, surface area, crush strengthand low attrition loss and bulk density. The particlesare prepared by an improved external gelation oil-dropprocess. In the process a slurry of alumina, prefer-ably a microcrystalline boehmite-pseudoboehmiteintermediate, is prepared in an acidic aqueous mediumand droplets of the slurry are passed through air intoa column containing an upper body of water-immitcibleliquid and ammonia and a lower body of aqueous co-agulating agent. Catalysts employing the particlesas a support and having catalytic agents distributedat controlled depths in the particle have excellentinitial and sustained activity and durability,especially for eliminating pollutants in automotiveexhaust streams.