Rhone-poulenc Industries

Rhone-poulenc Specialites Chimiques

Commissariat a L'energie Atomique

Aluminum Pechiney

Laurent Seigneurin

Roland Jacques

Michel Reppelin

Gilbert Bouge

Thierry Dupin

Regis Poisson

Max Michel

Georges Vrisakis

Pierre Bergez

Jean-Yves Derrien

Michel Pajot

Ramanadin

Michel Brunet

Alain Deguelte

Process for the production of anhydrous calcium fluosilicate from anhydrous calcium chloride and impure fluosilicic acid solution, a by-product of the acid treatment of phosphorus ores containing fluorine, characterized in that a calcium fluosilicate dihydrate is precipitated at low temperature and quantitatively by suitable adjustment of the fluosilicic acid concentration and the molar ratio CaCl.sub.2 /H.sub.2 SiF.sub.6 and that after filtration, washing and drying of the precipitate, an anhydrous calcium fluosilicate which can be easily decomposed by heat treatment is obtained to restore calcium fluoride and silicon tetrafluoride suitable for the manufacture of pure hydrofluoric acid and fluosilicic acid. For gravimetric concentrations of H.sub.2 SiF.sub.6 &gt;25% and molar concentration ratios CaCl.sub.2 /H.sub.2 SiF.sub.6 between 2 and 5, the yields of the anhydrous calcium fluosilicate obtained are greater than 94%.

Process for the preparation of calcium fluosilicate as a raw material

An improved fluorinated siliceous catalyst, well adapted for the catalytic synthesis of aromatic/aliphatic nitriles from their corresponding formamides, formanilides or amides, is comprised of a plurality of silica particulates, the specific surface of which ranging from about 200 to about 300 m.sup.2 /g, having a total pore volume ranging from about 1 to about 1.5 cm.sup.3 /g, with an average pore diameter ranging from about 100 to about 200 .ANG., having an exchange pH of less than about 3, and with the fluorine content thereof bonded to the silica, expressed in F.sup.31 , ranging from about 0.05 to about 2% by weight based upon the silica, and the sodium content thereof, expressed as Na.sub.2 O, being less than about 1% by weight, also based upon the silica.

Fluorinated silica catalyst and preparation of aromatic/aliphatic

A high specific surface hydrargillite, well adopted as filler material or primer particulates in the production of finely divided aluminum trihydroxide by decomposition of Bayer process aluminate liquors, is readily prepared by (i) reacting an alkali metal aluminate with hydrofluoric acid at a temperature ranging from about 5.degree. to 95.degree. C., the amount of said hydrofluoric acid ranging from about 25% to 90% of that amount stoichiometrically required for complete neutralization of the alkalinity of said aluminate, (ii) optionally treating the hydrargillite precipitate which results at a temperature of from about 5.degree. to 95.degree. C. for from about one-half to 10 hours, and thence (iii) recovering said hydrargillite precipitate, preferably by filtering, washing and drying.

High specific surface hydrargillite

A process for the preparation of porous products containing cobalt fluoride CoF.sub.2 or lead fluoride PbF.sub.2, wherein it comprises thermally decomposing lead fluosilicate or cobalt fluosilicate.

Process for the preparation of porous products based on cobalt fluoride

An improved fluorinated siliceous catalyst, well adapted for the catalytic synthesis of aromatic/aliphatic nitriles from their corresponding formamides, formanilides or amides, is comprised of a plurality of silica particulates, the specific surface of which ranging from about 200 to about 300 m.sup.2 /g, having a total pore volume ranging from about 1 to about 1.5 cm.sup.3 /g, with an average pore diameter ranging from about 100 to about 200 .ANG., having an exchange pH of less than about 3, and with the fluorine content thereof bonded to the silica, expressed in F.sup.-, ranging from about 0.05 to about 2% by weight based upon the silica, and the sodium content thereof, expressed as Na.sub.2 O, being less than about 1% by weight, also based upon the silica.

This invention relates to a continuous process for the preparation of trifluoromethylbenzenes from the corresponding trichloro- or tribromo-methylbenzenes with hydrofluoric acid. The process is characterized by passing an ascending stream of gaseous hydrofluoric acid, countercurrently through a plurality of mobile successive liquid layers of the trichloro- or tribromo-methylbenzenes.

Process for the preparation of trifluoromethylbenzenes from the

Aromatic/aliphatic nitriles having the formula:

Preparation of aromatic/aliphatic nitriles

Aqueous suspensions of alumina particulates, at least a portion of which comprising ultrafine boehmite, are prepared by maintaining a pH&lt;9 aqueous formulation of poorly crystallized and/or amorphous activated alumina powder for such period of time as to effect the at least partial transformation of such alumina powder into ultrafine boehmite.

Process for preparing alumina particulates, at least a fraction of which

Spheroidal alumina particulates having bifold porosity are prepared by (i) intimately admixing, at a pH of less than about 7.5, (a) a sol of a member selected from the group consisting of ultrafine boehmite and pseudo-boehmite, said sol being devoid of amorphous alumina and the concentration by weight thereof, in content by weight of Al.sub.2 O.sub.3, being between 5 and 25%, with (b) from 30 to 95% by weight, based upon the total solids content of the admixture, of spheroidal alumina particulates essentially completely in at least one of the phases eta, gamma, delta and theta, such particulates having a micropore volume ranging from about 0.4 to 1 cm.sup.3 /g, a specific surface ranging from about 100 to 350 m.sup.2 /g, and particle diameters ranging from about 1 to 50 microns; (ii) prilling said intimate admixture into spheroidal particulates and gelling the same; and then, (iii) recovering, drying and calcining said gelled particulates at a temperature of from 550.degree. to 1100.degree. C. The resultant particulates having bifold porosity are useful as catalysts or catalyst supports.

Spheroidal alumina particulates having bifold porosity and process for

Nitrogen oxides, NO.sub.x, are depleted/removed from oxygen-containing gas streams comprising same, by contacting an admixture of ammonia and such gas streams, at elevated temperatures, with a catalyst which comprises a catalytically active metallic oxide deposited on a porous alumina support, said support comprising a volume of pores having diameters larger than 1000 A in excess of 25 cm.sup.3 /100 g, a volume of pores having diameters larger than 300 A in excess of 40 cm.sup.3 /100 g, a total pore volume of from about 80 cm.sup.3 /100 g to 120 cm.sup.3 /100 g, and a surface area of less than 160 m.sup.2 /g, said catalytically active metallic oxide being an oxide of a metal selected from the group consisting of vanadium, iron and cobalt, and said catalytically active metal oxide comprising from 0.5 to 20% by weight of the catalyst.

Catalyst for removing NO.sub.x from gas streams

The invention relates to a new highly reactive alumina and the method of preparing it. The alumina is characterized by an amorphous structure and a specific surface of greater than 600 m.sup.2 /g. It is prepared by thermal decomposition of the double carbonate of aluminum and ammonium of the formula AlNH.sub.4 CO.sub.3 (OH).sub.2 at a temperature of between about 200.degree. and 500.degree. C. Aluminum hydroxychlorides of the formula Al.sub.2 (OH).sub.x Cl.sub.6-x can be prepared from it.

Highly reactive alumina and process for the preparation thereof

A crystalline, alkali metal aluminosilicate of type 4A is prepared by reaction between an aqueous solution of an alkali metal silicate and an aqueous solution of an alkali metal aluminate, and includes the steps of (i) introducing a flow of at least a portion of at least one of said reactant solutions into a reaction zone; (ii) co-introducing with said flow (i) an in line flow of at least a portion of the other reactant solution into said reaction zone; (iii) thus establishing in said reaction zone a liquid mixture of said aqueous reactant solutions and said liquid admixture comprising a gel-formation medium; (iv) establishing gel-formation elevated temperatures within said gel-formation medium to effect formation of a mixture comprising an aluminosilicate gel-phase and a mother liquid; (v) recycling said gel-phase/mother liquor to said flow (i); (vi) maintaining said gel-phase comprising said gel-formation medium under such elevated temperatures for such period of time as to effect crystallization of the aluminosilicate, and whereby a suspension of aluminosilicate crystals of type 4A in liquid phase results; and (vii) thence recovering said aluminosilicate crystals from said resulting liquid phase. The resultant aluminosilicate crystals are useful, e.g., detergent additives.

Process for the preparation of crystalline, alkaline, aluminosilicate

The preparation of a material consisting essentially or largely of aluminum hydroxychlorides having the general formula Al.sub.2 (OH).sub.X Cl.sub.6.sub.-X, in which X is a value up to 5 or more and obtained by reacting active alumina, secured by partial dehydration of hydrates of alumina, with hydrochloric acid or aluminum chloride in which the active alumina has a specific surface area of at least 200 m.sup.2 /g.

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Salindres, France

Laurent Seigneurin