Rhone-poulenc Chimie

Rhodia Chimie

Pierre Macaudiere

Denis Huguenin

Thierry Chopin

Thierry Seguelong

Philippe Barthe

Sylvain Busnot

Olivier Touret

Catherine Hedouin

Yvette Pescher

Alain Tressaud

Maryline Aubert

Jorge Morros

Rachid Mahiou

Jean-Michel Tourre

An improved material in the form of rare-earth borate, its precursor(s) and a luminophore made thereof is provided. The material is characterizable as comprising spherical, cubic or parallelepipedal particles having an average particle size not more than 10 &mgr;m, over a narrow particle size distribution (dispersion index not greater than 0.8). The material may comprise a rare earth element having that lacks luminescence in combination with a dopant.

Rare earth borate, its precursor, and luminophore made thereof

The present invention relates to a process for treating gases to reduce emissions of oxides of nitrogen. This process is of the type in which a catalytic composition is used which comprises a catalytic phase on a support and is characterized in that the support is based on silica and titanium oxide in an atomic proportion Ti/Ti&plus;Si of between 0.1 and 15%. The process of the invention applies more particularly to the treatment of the exhaust gases from diesel engines or from lean burn engines.

Method for treating gases to reduce nitrogen oxide emissions

The present invention relates to a compound of the LaMO3 type, M being aluminum, gallium or indium, in the form of a powder or in sintered form, its process of preparation and its use as an oxygen conductor. The compound in powder form is capable of achieving, by pressureless sintering, a density of at least 93% of the theoretical density and of giving a sintered compound substantially free of any electrically active secondary phase of the grain boundaries. The compound in powder form is obtained by the reaction of the salts of lanthanum and of the element M with a base, and then the separation and calcining of the precipitate obtained. It may also be obtained by mixing, in a liquid medium, salts of lanthanum, and of the element M and, optionally, of a base, and then spray-drying and calcining the precipitate obtained. The sintered compound may be used in any application requiring an oxygen-conducting material in oxide form, such as solid-oxide fuel cells.

LaMO3 type composition, M being aluminium, gallium or indium, in powder or sintered form, method of preparation and use as conductor of oxygen

The composition is based on a samarium sesquisulphide, it exhibits a samarium purity with respect to other rare earth metals of greater than 99% and it comprises at least one alkali metal or alkaline earth metal element, at least a portion of which is included in the crystal lattice of the said sesquisulphide. According to another embodiment, the composition is based on a sesquisulphide of samarium and of at least one rare earth metal which is solely trivalent and it comprises at least one alkali metal or alkaline earth metal element, at least a portion of which is included in the crystal lattice of the said sesquisulphide. According to a third embodiment, the composition exhibits a samarium purity such that the cerium content is less than 1%. The process consists in reacting samarium, trivalent rare earth metal and alkali metal or alkaline earth metal compounds with a gaseous mixture of hydrogen sulphide and of carbon disulphide.

Composition based on samarium sesquisulphide, preparation method and use as coloring pigment

The present invention provides a process for preparing a rare earth borate by reacting together at least one rare earth salt, boric acid and a base. The process is characterized in that the reaction is carried out using an excess of acid with respect to the stoichiometry and under conditions such that the pH of the reaction medium at the end of the reaction is in the range of 6 to 8. The precipitate formed is then recovered and calcined. The phase purity of the borate obtained is good and it can be used as a luminophore.

Process for preparing a rare earth borate by reacting together at least one rare earth salt, boric acid and a base

Inorganic rare earth pigments/colorants and synthesis/applications thereof

Rare-earth borate and its precursor, preparation processes and use of borate as luminophore

The present invention concerns a sulfide of a rare earth and an alkali, a process for its preparation and its use as a colored pigment. The sulfide is characterized in that it has the formula ABS,where A represents at least one alkali and B represents at least one rare earth and in that it is constituted by grains with an average size of 1.5 &mgr;m at most. The preparation process for the sulfide is characterized in that at least one rare earth carbonate or hydroxycarbonate is brought into the presence of at least one gas selected from hydrogen sulfide or carbon disulfide. The product obtained is optionally deagglomerated. The sulfide can be used as a pigment in plastics, paints, finishes, rubbers, ceramics, glazes, paper, inks, cosmetics, dyes, laminated coatings and materials based on or obtained from at least one inorganic binder.

Rare-earth and alkali sulphide, method for preparing same and use thereof as a pigment

Storage-stable colloidal organic sols comprise suspended tetravalent metal oxide particulates in an organic diluent medium, notably cerium dioxide particulates, the tetravalent metal oxide particulates having a particle size d,no greater than 200 nanometers and being complexed with at least one amphiphilic organic acid, and either said tetravalent metal oxide particulates comprising agglomerates of crystallites, the d,of which being no greater than 5 nanometers and at least 90% of said agglomerates comprising from 1 to 5 crystallites, and/or said at least one amphiphilic organic acid has from 11 to 50 carbon atoms and is branched in at least one of the &agr;-, &bgr;-, &ggr;- or &dgr;-positions relative to the atom bearing the acidic hydrogen.

Colloidal organic sols comprising tetravalent metal oxide/organic acid complexes

The present invention relates to a compound based on an alkaline-earth metal, on sulphur and on aluminium, on gallium or indium, to its process of preparation and to its use as luminophore. The compound of the invention corresponds to the formula AB,S,, in which A represents an alkaline-earth metal and B aluminum, gallium, or indium and it is characterized in that it is provided in the form of a powder with a residual oxygen content of not more that 1.5% and composed of particles with a mean size of not more than 10 &mgr;m. This compound is obtained by a process which contains the following stages: a solution or a suspension comprising salts of the elements A and B is formed, the solution or the suspension is dried by atomization and the product obtained in the preceding stages is reacted with carbon disulphide or with a mixture of hydrogen sulphide and or carbon disulphide. The compound of the invention can be used as a luminophore, in particular in cathodoluminescence.

Compound with base of an alkaline-earth, sulphur and aluminium, gallium or indium, method of preparing same and use as luminophore

Sulphur compounds coated with a zinc compound for use as pigments

Unique colorant compositions, well suited for the pigmentation of a wide variety of coatings and substrates, e.g., cosmetics, plastics, paints and rubbers, comprise (1) at least one crystalline rare earth metal sulfide or sesquisulfide, for example cubic cerium sesquisulfide Ce.sub.2 S.sub.3, and (2) a dopant amount of at least one alkali metal, and wherein the at least one rare earth metal sulfide or sesquisulfide comprises whole (unground) monocrystalline grains thereof having a mean particle size of at most 1.5 .mu.m.

Very finely divided rare earth sulfide colorant compositions

Alkaline-earth metal-, copper- and optionally titanium-based silicates,

Oxygen-rich exhaust gases, for example those emanating from internal combustion engines, e.g., diesel engines, are catalytically treated/converted to reduce emissions of NO.sub.x, in the presence of a catalytically effective amount of a spinel mass oxide essentially having the formula ZnAl.sub.2 O.sub.4 which was prepared by forming a solution or suspension of the salts of the constituent elements of the mass oxide, drying by atomizing the solution or suspension and calcining the salts of the constituent elements of the mass oxide so as to result in the spinel mass oxide.

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Asnieres sur Seine, France

Pierre Macaudiere