Patent · US Expired

Production of Maddrell salt

US4162300A · kind A · utility

2Cited by

4References

4Claims

0Family size

Assignee

Hoechst GmbH · DE

Inventors

Renate Adrian · Hürth, DE
Raban von Schenck · Heidelberg, DE
Klaus Somme · Heidelberg, DE
Hermann Weber

Key dates

Filing date	Sep 25, 1978
Grant date	Jul 24, 1979
Priority date	—
Expiry date	Sep 25, 1998

Classification

Technology area (CPC C)Chemistry; Metallurgy
CPC primaryC01B25/445
WIPO fieldMaterials, metallurgy
WIPO sectorChemistry

Abstract

Pure Maddrell salt is produced by heating sodium phosphate to temperatures of 250.degree. to 420.degree. C. The sodium phospate used as starting material is sodium trimetaphosphate or a mixture of sodium trimetaphosphate with Maddrell salt, monosodium orthophosphate or disodium pyrophosphate, the mixture containing Na and P in a molar ratio of 1:1. Prior to heating the starting material, it is admixed with 0.5 to 5 weight% of orthophosphoric acid, polyphosphoric acid, phosphorus pentoxide or at least one salt of a volatile base forming polyphosphoric acid at the temperatures specified. The resulting mixture is calcined over the period necessary to transform the starting material to Maddrell salt.

Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.