Title: Colloidal dispersion of particles of a rare earth vanadate or phosphovanadate
Application Number: 02820035 Application Date: 2002.09.10
Publication Number: 1568288 Publication Date: 2005.01.19
Approval Pub. Date: Granted Pub. Date:
International Classifi-cation: C01B25/45,C01G31/00,C09K11/82,C09K11/83,H05B33/14
Applicant(s) Name: Rhodia Electronics and Catalys Address:
Inventor(s) Name: Chane-ching Jean-yves
Attorney & Agent: long chuangong
Abstract:
     The invention concerns a vanadate or a phosphovanadate of at least a rare earth characterized in that it comprises either a complex-forming agent having a pK (cologarithm of the dissociation constant of the complex formed by the complex-forming agent and said rare earth) higher than 2.5, or an anion of a monovalent acid, soluble-in water and having a pKa ranging between 2.5 and 5. In the case of a vanadate dispersion, the particles have an average size of not more than 6 nm. The inventive dispersion is obtained by a method which consists in contacting a colloidal dispersion or a dispersion of initial complexes comprising at least a rare earth compound and at least a complex-forming agent or an anion of said monovalent acid and whereof the pH has been adjusted to a value of at least 7, with vanadate ions and, if required, with phosphate ions, then in adjusting the pH of the resulting medium to a value of at least 9 and heating.
Time: 9