Rhodia Operations

Hirofumi Takemori

Emmanuel Rohart

Olivier Larcher

Stephan Verdier

Eisaku Suda

Bernard Pacaud

Catalyst compositions for the treatment of vehicular exhaust gases are based on zirconium and cerium oxides, have a cerium oxide content of at most 50% by weight, a level of reducibility of at least 95% after calcination in air at 600&#xb0;, and a specific surface area after calcination for 4 hours at 1100&#xb0; of at least 15 m/g; such compositions are prepared by forming an aqueous mixture containing zirconium and cerium compounds, by heating this mixture to at least 100&#xb0; and, after the heating, adjusting it to a basic pH, by adding a surfactant additive to the precipitate obtained from this mixture and by calcinating the precipitate in an inert gas or under vacuum at a temperature of at least 900&#xb0; and then in an oxidizing atmosphere at a temperature of at least 600&#xb0;.

Catalyst compositions for the treatment of vehicular exhaust gases comprise zirconium oxide and cerium oxide, and have a high reducibility and a stable specific surface area

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Tokushima, Japan

Hirofumi Takemori