Abstract: Apparatus for preparing spherical, submicronic, monodispersed, and non-agglomerated particles of metal oxides by reacing with steam a gaseous stream containing an aerosol of liquid particles of a hydrolyzable metal compound. The apparatus is characterized in that into a duct, in which an inert gas stream containing vapors of a hydrolyzable metal compound flows, there is fed through a nozzle a cold inert gas stream, the temperatures and flows of the two gaseous streams being such as to establish in the duct a temperature lower than the condensation temperature of the metal compound; the mixed gaseous streams having a turbulent flow in the duct, with a Reynolds number equal to or higher than 1800. At the duct outlet, the aerosol of metal compound liquid particles, which has formed in the duct, is caused to react with steam, wherefore solid particles of hydrated metal oxide form, which are subsequently calcined to the oxide.

Abstract: Spherical, submicronic, monodispersed, and non-agglomerated particles of metal oxides by reacting with steam a gaseous stream containing an aerosol of liquid particles of a hydrolyzable metal compound. Into a duct, in which an inert gas stream containing vapors of a hydrolyzable metal compound flows, there is fed through a nozzle a cold inert gas stream, the temperatures and flows of the two gaseous streams being such as to establish in the duct a temperature lower than the condensation temperature of the metal compound; the mixed gaseous streams having a turbulent flow in the duct, with a Reynolds number equal to or higher than 1800. At the duct outlet, the aerosol of metal compound liquid particles, which has formed in the duct, is caused to react with steam, wherefore solid particles of hydrated metal oxide form, which are subsequently calcined to the oxide.