Rhone-poulenc Chimie

Lionel Bonneau

Olivier Touret

Thierry Chopin

Michele Pijolat

Marie Prin

Gabriel Vilmin

Michel Soustelle

The invention relates to new compositions based on ceric oxide having an improved oxygen storage capacity, these compositions being characterized in that they contain, besides ceric oxide, at least one oxide of another metallic element M chosen from the group consisting of iron, bismuth, nickel, tin and chromium or one of their mixtures, this oxide preferably being in solid solution with the abovementioned cerium oxide. The process of synthesis of these compositions consists in first of all preparing an intimate mixture between (i) a ceric oxide or a ceric hydroxide and (ii) at least one additive consisting of a hydroxide or a salt, thermally decomposable to an oxide, of the metallic element M, and in then calcining this mixture so as to obtain the desired composition based on oxides. The compositions according to the invention are particularly useful in the manufacture of catalysts and/or catalyst supports, especially those intended for treating exhaust gases from internal combustion engines.

Composition based on ceric oxide, preparation and use

Composition precursor and mixed cerium and zirconium oxide-based

Ceric oxide (ceria) particulates exhibiting a particularly small crystallite size, well suited for catalyst/catalyst carrier applications, include a specific surface-stabilizing amount of silicon values (preferably less than 1% by weight thereof, expressed as SiO.sub.2) and have a specific surface of at least 40 m.sup.2 /g after calcination at 800.degree. C. for 6 hours and of at least 20 m.sup.2 /g after calcination at 1,000.degree. C. for 6 hours; such CeO.sub.2 particulates are advantageously prepared by (a) suspending certain ceric hydroxides in a basic aqueous reaction medium containing a silicon compound, (b) autoclaving the resulting suspension, (c) cooling and depressurizing such medium of reaction, (d) separating a ceric hydroxide therefrom, and (e) calcining the ceric hydroxide thus separated.

B.E.T. specific surface-stabilized ceria

Thermally stable ceric oxide-based compositions, well suited as catalysts/catalyst supports for a wide variety of reactions, notably for the catalytic conversion of exhaust gases emanating from internal combustion engines, comprise particulates of immixture of a major amount of ceric oxide with at least one other metal oxide of magnesium, gallium, boron, scandium, or mixture thereof, and having a specific surface greater than 10 m.sup.2 /g after calcination at 800.degree. C.

Thermally stable ceric oxide-based compositions and process for their

Organotin fluorides, notably dialkyltin difluorides, well adpated for the manufacture of coated insulating glassware and having controlled morphology, are prepared by reacting a stannic compound, e.g., an organotin chloride, with a fluorinating agent, e.g., hydrofluoric acid or an ammonium fluoride, admixing the organotin fluoride thus produced in a solvent that is immiscible with the fluorinating agent but which solubilizes the organotin fluoride therein, subsequently or simutaneously heating the solvent medium to a temperature sufficient to release unreacted fluorinating agent therefrom, and cooling such solvent medium and thereby crystallizing therefrom an organotin fluoride having a controlled morphology, e.g., well defined platelets having a characteristic DTA spectrum.

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Angliers, France

Lionel Bonneau