Rhodia Operations

Anan Kasei Co., Ltd.

Eisaku Suda

Manabu Yuasa

Bernard Pacaud

Takao Sekimoto

Olivier Larcher

Emmanuel Rohart

Naotaka Ohtake

Stephan Verdier

Réka Toth

Toshihiro Sasaki

Lauriane Dalencon

Hirofumi Takemori

The present invention relates to cerium-based particles and their use as a component of a composition for polishing. The present invention also relates to the method of preparation of the cerium-based particles.

Cerium based particles

The present invention relates to a suspension of cerium oxide particles in a liquid phase, in which said particles comprise secondary particles comprising primary particles, and a process for preparing said liquid suspension in which the cerium IV/total cerium molar ratio before precipitation is comprised between 1/10000 and 1/500000 and that the thermal treatment is being carried out under an inert atmosphere.

Liquid suspension of cerium oxide particles

The present invention concerns a process for the production of metal doped cerium compositions comprising a cerium oxide and a metal oxide by precipitation. The invention also concerns metal doped cerium compositions providing high crystallites size and exhibiting high thermal stabilities, which may be used as a catalytic support or for polishing applications.

Metal doped cerium oxide compositions

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

The invention provides a cerium based composite oxide and its production method, which hardly forms aggregates, is composed of particular acicular particles providing sinterable ceramic materials, has a sharp particle size distribution, and inhibited from aggregating. The composite oxide contains 0.1&#x2013;50 mol % of metal such as Y, Sc, or rare earth elements excluding Ce and Pm, in terms of oxides, and 50 to 99.9 mol % of cerium in terms of oxides, wherein the composite oxide takes the acicular primary particle form having an average aspect ratio of 1.05&#x2013;10.0, or secondary particle form, aggregates of the primary particles. The composite oxide containing the primary and second particles have a BET specific surface area of 5 to 40 m/g, an average particle size of 0.1 to 0.5 &#x3bc;m, and a particle size distribution index represented by formula (1) of not higher than 1.6:Particle Size Distribution Index=(84&#x2212;16)/(2&#xd7;50).&#x2003;&#x2003;(1)

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Tokushima, Japan

Eisaku Suda