Aqueous dispersion of a rare earth phosphate, and a process for its preparation
US7569613B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Mar 27, 2007 |
| Grant date | Aug 4, 2009 |
| Priority date | — |
| Expiry date | Mar 27, 2027 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB01J13/0013
- WIPO fieldChemical engineering
- WIPO sectorChemistry
Abstract
The invention concerns an aqueous colloidal dispersion of isotropic particles of a phosphate of at least one rare earth and is characterized in that it comprises either a complexing agent with a pK (cologarithm of the dissociation constant of the complex formed by the complexing agent and said rare earth) of more than 2.5; or an anion of a monobasic acid, soluble in water and with a pKa in the range 2.5 to 5; or said complexing agent and/or said anion of a monobasic acid. In the case of cerium and lanthanum, the mean particle size is at most 20 nm. The dispersions can have a degree of colloid agglomeration of less than 40%.This dispersion can be prepared by forming an aqueous mixture comprising at least one rare earth salt and the complexing agent or monobasic acid anion; by adding a base then phosphate ions to the mixture formed; and heating the mixture obtained. A precipitate is obtained that is re-dispersed in water.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.