초록 ▼

Spheroidal alumina particles have a combination of high macroporosity, surface area, crush strength and low attrition loss and bulk density. The particles are prepared by an improved external gelation oil-drop process. In the process a slurry of alumina, preferably a microcrystalline boehmite-pseudo

Spheroidal alumina particles have a combination of high macroporosity, surface area, crush strength and low attrition loss and bulk density. The particles are prepared by an improved external gelation oil-drop process. In the process a slurry of alumina, preferably a microcrystalline boehmite-pseudoboehmite intermediate, is prepared in an acidic aqueous medium and droplets of the slurry are passed through air into a column containing an upper body of water-immiscible liquid and ammonia and a lower body of aqueous coagulating agent. Catalysts employing the particles as a support and having catalytic agents distributed at controlled depths in the particle have excellent initial and sustained activity and durability, especially for eliminating pollutants in automotive exhaust streams.

대표청구항 ▼

A process for preparing spheroidal alumina particles comprising: (a) commingling a precipitated alumina and an acidic aqueous medium to provide a slurry; (b) forming droplets of the slurry; (c) passing the droplets downwardly through air into an upper body of water-immiscible liquid and ammonia and

A process for preparing spheroidal alumina particles comprising: (a) commingling a precipitated alumina and an acidic aqueous medium to provide a slurry; (b) forming droplets of the slurry; (c) passing the droplets downwardly through air into an upper body of water-immiscible liquid and ammonia and into a lower body comprising aqueous ammonia to form spheroidal particles; (d) aging the particles in aqueous ammonia; and (e) drying and calcining the aged particles.