Rhone-poulenc Specialites Chimiques

Rhone-poulenc Chimie

Rhone-poulenc Industries

Rhone-poulenc Specialties Chimiques

Rhone-poulenc Chimie De Base

Thann Et Mulhouse, Corp.

Groupement Franco-senagalais D'etudes Et De Recherches Industrielles

Claude Magnier

Bertrand Latourrette

Jean-Francois Colombet

Frederic Couffin

Claire David

Jean-Paul Bourgeois

Marie-Odile Lafon

Claire Gourlaouen

Anne Tugaye

Francoise Deneuve

Jean-Philippe Browaeys

Jean Grosbois

Regis Poisson

Patrick Dougier

Frederic Fabre

Jean-Paul Tognet

Jean-Claude Guelen

Alain Vesco

Finely divided, homogeneous and easily sintered superconducting powders of at least one rare earth element, e.g., yttrium and/or lanthanum, at least one alkaline earth metal, e.g., barium, calcium and/or strontium, and at least one transition metal, e.g., copper, nickel, manganese, cobalt and/or iron, and oxygen, are produced by (a) solubilizing, in water, the nitrates and/or acetates of at least one rare earth element, at least one alkaline earth metal, and at least one transition metal; (b) atomizing such solution to dryness; (c) calcining the dried product; and, optionally; (d) grinding the calcined material.

Production of superconductor materials using a helicoidal flow of hot

Finely divided, homogeneous and easily sintered superconducting powders of at least one rare earth element, e.g., yttrium and/or lanthanum, at least one alkaline earth metal, e.g., barium, calcium and/or strontium, and at least one transition metal, e.g., copper, nickel, manganese, cobalt and/or iron, and oxygen, are produced by (a) intimately admixing a sol of a rare earth element and an aqueous solution of at least one alkaline earth metal nitrate and of at least one nitrate of a transition metal, with the pH of the resulting mixture being adjusted to a value such that said nitrates remain solubilized therein; (b) drying the resulting mixture; (c) calcining the dried product; and, optionally; (d) grinding the calcined material.

Production of superconductor materials

Highly concentrated, aqueous colloidal dispersions of a cerium (IV) compound, adapted for the impregnation of catalyst supports, are prepared by reacting an aqueous solution of a cerium (IV) salt with a base, to precipitate a certain cerium hydroxynitrate, separating and washing said precipitate, and then dispersing the washed precipitate in an aqueous acid medium.

Colloidal dispersions of cerium (IV) compound

A neodymium hydroxynitrate, readily calcined into, e.g., neodymium oxide, Nd.sub.2 O.sub.3, has the formula (I):

Neodymium hydroxynitrate

Rare earth hydroxides are recovered from the rare earth ores, e.g., monazite, xenotime and/or bastnasite, by treating the ore with an aqueous solution of an alkali metal hydroxide, under agitation and essentially constant pressure, at a temperature of from about 100.degree. to 220.degree. C., and wherein the ratio by weight of alkali metal hydroxide/ore ranges from about 1.4 to 0.5, e.g., a weight ratio of sodium hydroxide/ore of from about 1 to 0.5, or a weight ratio of potassium hydroxide/ore of from about 1.4 to 0.7.

Processing of rare earth ores

Zeolites of type ZSM-5, well suited as absorbents/catalysts, are facilely prepared by (i) intimately admixing a source of alumina with a source of silica, in aqueous reaction medium having a pH ranging from 1 to 7 and wherein the molar ratio SiO.sub.2 /Al.sub.2 O.sub.3 ranges from 5 to 100, (ii) adding a source of alkali metal oxide to the reaction mixture resulting from said stage (i), said combined reaction mixture having a pH ranging from 8 to 12, and thence (iii) crystallizing a zeolite of type ZSM-5 therefrom.

Preparation of zeolites of type ZSM-5

Morphologically improved ceric oxide particulates have a BET specific surface, measured after calcination at a temperature of from 350.degree. to 450.degree. C., of at least 100 m.sup.2 /g, a total pore volume of at least 0.3 cm.sup.3 /g, and the pores of which having a mean diameter larger than 50 .ANG.. The improved ceric oxide particulates are prepared by reacting a cerium salt with a strong base in the presence of carboxylate ions, or a cerium carboxylate with a strong base; separating the precipitate of true cerium hydroxide thus produced; and washing, heat-treating, and calcining such precipitate.

Novel ceric oxide particulates and process of making

A fine powder of stabilized zirconia a process for its preparation and application of the powder in ceramic compositions to obtain good mechanical, thermomechanical and electrical properties. A zirconia hydrate sol having a pH between 0.5 and 5 and containing elementary acicular crystals having dimensions of from about 10 to 500 .ANG. which are agglomerated into submicron aggregates of from abuot 100 to 5000 .ANG. in diameter is mixed with a solution of a stabilizing agent, preferably yttrium; the suspension is dried; the dried suspension is calcined at a temperature of from about 700.degree. C. to 1,300.degree. C. for preferably from about 30 minutes to 24 hours; and if needed, the powder obtained is milled.

Stabilized zirconia a process for its preparation and its application in

Submicronic zirconia particulates containing stabilizing amounts of yttrium or cerium, well adapted for ceramics applications, are produced by (i) admixing an aqueous suspension of zirconium fluosulfate particles having a pH of from about 0 to 3 with an aqueous solution of a salt of yttrium or cerium, (ii) neutralizing the resulting mixture at a pH of at least 7, (iii) separating a mixture of zirconium/yttrium or zirconium/cerium hydroxides from the medium of neutralization, (iv) washing said mixture of hydroxides to eliminate sulfate and fluoride ions therefrom, and then (v) calcining said mixture of hydroxides.

Stabilized zirconia particulates

A fine powder of neodymium titanate or barium neodymium titanate, a process for its preparation and applications in ceramic compositions. A suspension of particles is formed by mixing a solution of neodymium nitrate or a solution of barium and neodymium nitrates with a sol of titania having a pH of from about 0.8 to 2.5 which contains elementary crystallites of TiO.sub.2 having a size of from about 10 to about 100 .ANG. in diameter which are agglomerated into submicron masses of from about 200 to about 1,000 .ANG. in diameter. The suspension obtained is dried, and the dried product is calcined at a temperature between 800.degree. C. and 1,300.degree. C., preferably for about 1 to 24 hours. If necessary, the powder obtained is milled. The fine powder obtained has a low fritting temperature and its density after heating for 2 hours at 1,300.degree. C. is greater than or equal to 95% of the theoretical density of the desired titanate powder.

Neodymium titanate and barium neodymium titanate, processes for their

Finely divided powders of alkaline earth metal titanates, well suited for the fabrication of, e.g., ceramic resistors and condensers, are facilely prepared by (i) admixing a solution of an alkaline earth metal nitrate with a titanium sol having a pH ranging from 0.8 to 2.5 and which comprises elementary crystallites of TiO.sub.2 having particle sizes ranging from 10 to 100 .ANG., agglomerated into submicronic masses having particle sizes ranging from 200 to 1000 .ANG., (ii) next drying the suspension which results, (iii) calcining said dried suspension at a temperature ranging from 700.degree. to 1300.degree. C. for from 30 minutes to 24 hours, under a NO.sub.x partial pressure decreasing from 1 to 0, and then (iv) optionally grinding the powder resulting from said step (iii).

Process of making finely divided powders of alkaline earth metal

A novel neodymium hydroxy/ammonium nitrate, readily calcined into, e.g., neodymium oxide, Nd.sub.2 O.sub.3, has the formula (I):

Neodymium hydroxy/ammonium nitrate

A catalyst support and process for preparing same are provided wherein a metal substrate is coated with a layer of adherent alumina with a layer of chromium interposed between the alumina catalyst support and the metal substrate. The catalyst supports of the invention are especially useful in catalytic converters for the purification and control of exhaust gas emissions from internal combustion engines by the active catalyst oxidation/reduction of carbon monoxide, unburned hydrocarbons and nitrogen oxides.

Catalyst support and process for preparing same

A novel anhydrous sodium tripolyphosphate, well adapted for detergency applications, has an X-ray diffraction pattern essentially characterizing a phase I sodium tripolyphosphate; a viscosity, in aqueous medium, characterizing a phase II sodium tripolyphosphate; a rate of hydration characterizing a phase I sodium tripolyphosphate; and which exhibits an ROH at 1 minute of greater than about 90.degree. C.

Anhydrous sodium tripolyphosphate

A novel anhydrous sodium tripolyphosphate, well adapted as an additive for foodstuffs and detergent compositions, has an Na/P ratio of essentially 1.667.+-.0.01, an apparent density of from 0.5 to 1.1, a mean agglomerate size of less than 100 microns, a phase I content ranging from 15 to 6% by weight, is devoid of insoluble fraction, and displays zero solidification or caking in a quiescent solvent medium.

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Paris, France

Claude Magnier