Solvay (societe Anonyme)

Solvay Interox (societe Anonyme)

Solvay Interox Sa

Solvay Sa

Robert Owen

Alun P James

Graham R Horne

Manfred Mathes

Richard Roesler

Romano Pardini

Soraya Parvaneh

Lido Signorini

Stefano Bigini

Pier-Luigi Deli

Uwe Droste

Michael Sell

Andrew Willson

Juergen Bosse

Javier Diaz-Maroto Carpintero

Jürgen Bosse

Nuno Formiga

Process for the purification of aqueous peroxygen solutions comprising the treatment of an aqueous peroxygen solution with (a) at least one membrane purification step, (b) optionally at least one ion exchange purification step, (c) optionally at least one dilution step, and (d) at least one other purification step, all of which can be conducted in any sequence. Aqueous peroxygen solutions having a TOC level of less than 1 mg/kg can be obtained by this process. They can be used in the manufacture of semiconductors.

Process for the purification of aqueous peroxygen solutions, solutions obtainable thereby and their use

Sodium percarbonate is traditionally made in a crystallization process from aqueous hydrogen peroxide and sodium carbonate with recycle of mother liquor in the presence of a substantial concentration of a salting out agent, conventionally sodium chloride. The invention provides a process intended to be conducted without addition of chloride salting-out agent in which the dissolution step is controlled to restrict the sodium carbonate concentration to below 95%, preferably 60 to 90% of its saturated concentration at a temperature preferably controlled to at most 35C. and the mole ratio of hydrogen peroxide:sodium carbonate in the reaction vessel is controlled to between 0.7 to 1.2:1, and preferably about 1:1. In some embodiments at least a fraction of the mother liquor introduced into the dissolution tank is obtained by extraction from the reaction vessel and in other embodiments a fraction of the sodium percarbonate is introduced in solution in the mother liquor and a fraction is introduced in particulate form directly into the reaction vessel. Large particle sodium percarbonate is provided which has a 7 day aged heat emission at 40C. of not more than 3 &mgr;W/g measured in a microcalorimeter over 16 hours that is lower than the heat emission from conventionally produced sodium percarbonate employing a chloride salting-out agent.

Sodium percarbonate and process for producing sodium percarbonate

Sodium percarbonate is traditionally made in a crystallization process from aqueous hydrogen peroxide and sodium carbonate with recycle of mother liquor in the presence of a substantial concentration of a salting-out agent, conventionally sodium chloride. The invention provides a process intended to be conducted without addition of chloride salting-out agent in which the dissolution step (,) is controlled to restrict the sodium carbonate concentration to below 95%; preferably 60 to 90% of its saturated concentration at a temperature preferably controlled to at most 35&deg; C. and the mole ratio of hydrogen peroxide: sodium carbonate in the reaction vessel is controlled to between 0.7 to 1.2:1, and preferably about 1:1. In some embodiments at least a fraction of the mother liquor introduced into the dissolution tank (,) is obtained by extraction from the reaction vessel (,) and in other embodiments a fraction of the sodium percarbonate (,) is introduced in solution in the mother liquor (,) and a fraction is introduced in particulate form (,) directly into the reaction vessel (,). Large particle sodium percarbonate is provided which has a 7 day aged heat emission at 40&deg; C. of not more than 3 &mgr;W/g measured in a microcalorimeter over 16 hours that is lower than the heat emission from conventionally produced sodium percarbonate employing a chloride salting-out agent.

Process for producing sodium percarbonate

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Brussels, Belgium

Robert Owen