Ceric oxide with new morphological characteristics and method for obtaining same
AssigneeRhone-Poulenc Chimie
InventorJean-Luc Le Loarer
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Abstract
The object of the present invention is a ceric oxide with new morphological characteristics. The invention also relates to one of the methods for obtaining said oxide. The method of the invention is characterized by the fact that a ceric hydroxide, prepared by base precipitation using a solution of a cerium salt, undergoes a solvo-thermal treatment before the calcination operation. The ceric oxide obtained has a large specific surface at high temperatures.
Claims27
A method for obtaining a ceric oxide having a specific surface of at least 15 m.sup.2 /g, measured after calcination at a temperature of between 800.degree. and 900.degree. C., said method comprising preparing a ceric hydroxide precipitate by reacting a solution of cerium salt, a base, and optionally, an oxidizing agent, the amount of base being selected such that the pH of the resulting reaction medium is greater than 7;
- (ii) separating the ceric hydroxide precipitate;
- optionally (iii) washing the ceric hydroxide precipitate;
- (iv) placing the ceric hydroxide in suspension in water or in an aqueous solution of a decomposable base;
- (v) heating the suspension or solution in a closed chamber to a temperature and pressure lower than the critical temperature and critical pressure thereof;
- (vi) cooling the suspension or solution and returning it to about atmospheric pressure;
- (vii) separating the resulting ceric hydroxide;
- and (viii) calcining the separated ceric hydroxide.
Dependencies are inferred from the claim text.