Process for obtaining ceric oxide
AssigneeRhone-Poulenc Chimie
InventorJean-Luc Le Loarer
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Abstract
The present invention concerns a process for obtaining a ceric oxide having a large specific surface area. The process according to the invention consists of subjecting a ceric hydroxide prepared by hydrolysis of a cerium IV salt solution, to solvothermal treatment prior to calcination. The ceric oxide thus obtained has a large specific surface area at high temperature.
Claims30
A process for obtaining a ceric oxide having a specific surface area of at least 15 m.sup.2 /g, measured after calcination at a temperature of between 800.degree. and 900.degree. C., said process comprising (i) placing a ceric hydroxide in suspension in water or in a watery decomposable base solution to provide a medium, said ceric hydroxide being represented by formula (I):
- Ce(OH).sub.x (NO.sub.3).sub.y, pCeO.sub.2, NH.sub.2 O (I);
- wherein X=4-y, y ranges from 0.35 to 1.35, p ranges from 0 to 2.0, and n ranges from 0 to 20;
- (ii) heating the medium in a sealed chamber until a temperature and pressure are obtained which are less than the critical temperature and pressure of the medium;
- (iii) cooling the medium and bringing it back to atmospheric pressure;
- (iv) separating the resulting ceric hydroxide;
- and (v) calcining the ceric hydroxide.
A process for obtaining a ceric oxide having a specific surface area of at least 15 m.sup.2 /g, measured after calcination at a temperature of between 800.degree. and 900.degree. C., said process comprising (i) preparing a medium by placing a ceric hydroxide in suspension in water or in a watery decomposable-base solution, said ceric hydroxide being obtained by the hydrolysis of a watery cerium IV salt solution in an acidic medium, separating the resulting precipitate, and thermal treatment as necessary;
- (ii) heating the medium in a sealed chamber until a temperature or pressure are obtained which are less than the critical temperature and pressure of the medium;
- (iii) cooling the medium and bringing it back to atmospheric pressure;
- (iv) separating the resulting ceric hydroxide;
- and (v) calcining the ceric hydroxide.
Dependencies are inferred from the claim text.