Hoechst Aktiengesellschaft

Hoechst Aktiengesellchaft

Reinhard Gradl

Gunther R Schimmel

Gero Heymer

Klaus Schrodter

Klaus-Peter Ehlers

Friedrich Kolkmann

Herbert Ressel

G/u/ Nther Schimmel

Werner Krause

Heinz Erpenbach

Wolfgang Scheibitz

Erhard Jagers

Thomas Staffel

Norbert Weferling

Gunter Roscher

Hans-Werner Stephan

Helmold Von Plessen

Peter Prinz

Werner Kowalski

Klaus Eichler

Andreas Seidel

Peter Horstermann

Michael Kotzian

Hilmar Roszinski

Martin Schott

Horst Langner

Karl-Heinz Schmidt

Wolfgang Becker

Gregor Fucker

For the preparation of crystalline sodium silicates having a sheet structure and an SiO.sub.2 /Na.sub.2 O molar ratio of 1.9:1 to 3.5:1 from waterglass solutions having a solids content of 20 to 65% by weight, the waterglass solutions are first treated in a spray-drying zone. This gives a pulverulent amorphous sodium silicate having a maximum ignition loss of 20% by weight, while the waste gas leaving the spray-drying zone is at a temperature of at least 140.degree. C. Thereafter, the spray-dried sodium silicate is heated in an ignition zone containing an agitated solid bed at temperatures of 500.degree. to 800.degree. C. for 1 to 60 minutes in the presence of at least 10% by weight of recycled material. This recycled material was obtained by mechanical comminution of crystalline sodium silicate discharged from the ignition zone.

Process for the preparation of crystalline sodium silicates having a

To prepare crystalline sodium silicates having a layer structure and the formula Na.sub.2 Si.sub.x O.sub.2x+1, in which x is between 2 and 3, sand and soda are first fused in a molar ratio of SiO.sub.2 /Na.sub.2 O of 2 to 3.5 at temperature of 1200.degree. to 1400.degree. C. The water-glass obtained in pieces after the melt has cooled is ground to particle sizes of less than 2 mm before it is treated at temperatures of 600.degree. to 800.degree. C. for 10 to 120 minutes in an elongated reaction zone with mechanical circulation. Finally, the material leaving the reaction zone is ground to a particle fineness of less than 1 mm.

Process for the preparation of crystalline sodium silicates

A process for inhibiting and destroying peroxides in dialkyl ethers having the general formula R.sub.1 OR.sub.2 in which R.sub.1 and R.sub.2 are alkyl groups having 1 to 6 carbon atoms, which comprises adding, as inhibitor, a quaternary alkyl iodide of the general formula

Process for inhibiting and destroying peroxides in dialkyl ethers

For producing substantially water-insoluble, chain-type ammonium polyphosphate, equimolar quantities of diammonium phosphate and phosphorus pentoxide are reacted at temperatures from 170.degree. to 350.degree. C. in a zone, which effects continuous mixing, kneading and comminution, in the presence of a stream of ammonia gas. In this process, the water is separated from the ammonia gas which leaves the zone and contains water vapor, and the dried ammonia gas is caused to flow again through the zone. A plant for producing substantially water-insoluble, chain-type ammonium polyphosphate can comprise a reactor (1) into which an ammonia feed pipe (8) and pipes for feeding phosphorus pentoxide (6) and diammonium phosphate (7) lead and from which an ammonium polyphosphate discharge pipe (9) and an exit gas pipe (10) start. The exit gas pipe (10) leads into a condenser (13) which is flow-connected via a pump (14) to a heat exchanger (15). An exit gas line (18) which leads into the ammonia feed pipe (8) starts from the heat exchanger (15).

Process for producing ammonium polyphosphate

A process for removing metallic corrosion products from carbonylation reactions which are carried out under anhydrous conditions and in which methyl acetate and/or methanol and/or dimethyl ether are reacted over a noble metal catalyst system which comprises a noble metal of group VIII of the periodic table of the elements, a co-catalyst, such as iodide or bromide, in particular methyl iodide, and a promoter, such as an organophosphonium or organoammonium salt, and if appropriate a lithium salt, to give acetic acid and/or acetic anhydride is described, the process comprising

Process for removing metallic corrosion products from carbonylation

Alkali metal phosphate solutions having a fluorine content of less than 20 ppm, based on P.sub.2 O.sub.5, are prepared by first digesting crude phosphate using sulfuric acid, and separating the calcium sulfate from the crude phosphoric acid. An alkali metal compound is then added to the crude phosphoric acid, and the precipitated solid is filtered off. The prepurified crude phosphoric acid is neutralized to a pH of at least 7, and the solid produced during this operation is separated off. The resultant alkali metal phosphate solutions having a P.sub.2 O.sub.5 content of from 10 to 30% by weight are adjusted to a pH of between 4.8 and 6.0 using phosphoric acid. The solutions are heated to from 60.degree. to 120.degree. C., and from 1 to 6% by weight, based on the weight of the solution, of an alkaline earth metal oxygen compound are added to the alkali metal phosphate solutions with stirring. Finally, the precipitated solid is filtered off from the alkali metal phosphate solutions after a residence time of from 0.5 to 4 hours.

Process for the preparation of alkali metal phosphate solutions

The invention relates to a process for the isolation of vinyl acetate which involves not combining the bottom product of the recylced gas washings with the water-saturated vinyl acetate but rather introducing it to further multiple distillation columns from the gas mixture formed in the reaction of ethylene with acetic acid and oxygen over catalysts containing palladium or palladium compounds in the gas phase.

Process for the isolation of vinyl acetate by distillation

Phosphoric acid substantially free from titanium is made from the organic extract obtained by subjecting crude phosphoric acid containing titanium to extractive purification with an organic solvent immiscible or only partially miscible with water. To this end, the organic extract is scrubbed in a scrubbing zone with a stage number of n&gt;4 by introducing the crude extract into stage 1 and scrubbing it countercurrently with an aqueous alkaline solution in one of stages 2 to n-2 and with pure scrubbing water in stage n.

Process for making phosphoric acid free from titanium

Crude phosphoric acid is made by subjecting crude phosphate ore containing sulfide to processing treatment with a mineral acid in a closed system comprised of a processing reactor, a filtering zone and an off-gas scrubbing zone. To this end, a soluble compound of a metal forming difficultly soluble sulfides in the respective acid medium is added either

Process for making crude phosphoric acid

Residue obtained upon the removal of heavy metal contaminants from crude phosphoric acid by means of a dialkyldithiophosphoric acid ester and adsorbent is worked up into ecologically reliable solid matter and into a heavy metal concentrate. The solid matter and heavy metal concentrate are separated from one another by successive mechanical and chemical treatment. The sequential order of these two operational steps can be inversed.

Process for working up heavy metal-containing residues originally from

Wet process phosphoric acid is freed from heavy metal ions, especially from ions of cadmium, copper, mercury, lead and arsenic and optionally also from organic compounds and sulfuric acid. To this end, the phosphoric acid is contacted with a diorganyldithiophosphoric acid ester and an adsorbent, if desired. Prior to or after said treatment with the ester, the phosphoric acid is admixed with a reductant. The adsorbent, if any is used alone or in combination with an alkaline earth metal compound soluble in phosphoric acid.

Process for purifying phosphoric acid

The reactivity of phosphorus pentoxide is reduced and its flow behavior improved. To this end, phosphorus pentoxide in the form of its hexagonal modification is annealed over a period of 0.5 to 8 hours at temperatures of 200.degree. to 390.degree. C.

Process for reducing the reactivity and improving the flow behavior of

Wet-process phosphoric acid is made by subjecting a phosphate ore to processing treatment with a mineral acid resulting in the formation of a processed suspension. The formation of silicofluorides is obviated by adding, either to the phosphate ore or the processed suspension, a quantity of an aluminum compound soluble in phosphoric acid sufficent for the processed suspension to present an aluminum concentration of 0.3 to 1.0 wgt %, based on P.sub.2 O.sub.5.

Process for making wet-process phosphoric acid

An aqueous alkali phosphate solution is made. An organic phase is countercurrently mixed with an aqueous phase, the two phases being used in a volume ratio larger than 1:1 and formed aqueous alkali phosphate solution is separated from the remaining organic phase. The two phases are mixed and reacted in a reaction zone comprised of a mixing and separating zone. The organic phase is continuously dispersed in the aqueous phase. A volume excess of aqueous phase is maintained in the mixing zone and the two phases are used in an overall quantity sufficient to provide a volume ratio of organic to aqueous phase of 4:6 to 2:8.

Process for making an alkali phosphate solution

Phosphoric acid solutions are dearsenified by treating them with a sulfide and separating the resulting precipitate from the purified solution. The sulfide is at least one compound of the general formula P.sub.4 S.sub.x in which x stands for a number of 3 to 10.

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Erftstadt, Germany

Reinhard Gradl