Sodium percarbonate and process for producing sodium percarbonate

US6482385B2 · kind B2 · utility

Assignee

• Solvay Interox GmbH · GB

Inventors

• Alun P. James · Crosby, GB
• Graham R. Horne · Rawtenstall, GB
• Richard R. Roesler · Wexford, US
• Lido Signorini · Sìnnia/Sinnai, IT
• Robert Owen · Cowbridge, GB
• Soraya Parvaneh · Livorno, IT
• Romano Pardini · Rosignano Solvay, IT
• Stefano Bigini · Terni, IT
• Manfred Mathes · Homborn, DE
• Uwe Droste · Homborn, DE
• Pier-Luigi Deli · Forlì, IT

Key dates

• Filing date: Feb 28, 2001
• Grant date: Nov 19, 2002
• Expiry date: May 25, 2021

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C11D3/128
• WIPO field: Basic materials chemistry
• WIPO sector: Chemistry

Abstract

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 micro…