Magnesium Elektron, Inc.

Gavin Edwards

Colin Norman

Ian Chisem

Yasuhide Takao

Clare Jones

This invention relates to a process for preparing zirconium oxide, in its various forms, including zirconium-based mixed oxides. There is described a process for preparing a zirconium oxide in the absence of a cerium salt which comprises precipitating a zirconium hydroxide from an aqueous solution of a zirconium salt by reaction with an alkali in the presence of a controlled amount of sulphate anions at a temperature not greater than 50&#xb0; C. and then calcining the hydroxide to form an oxide, wherein the oxide thus formed is essentially sulphate free. Catalysts and ceramics can be produced from the product oxides having improved thermal stability and improved sinterability, respectively. A particular use of the product oxide is as a promoter or catalyst support in automobile exhaust systems.

Process for preparing zirconium oxides and zirconium-based mixed oxides

A process for preparing zirconium-cerium-based mixed oxides which comprises reacting an alkali with an aqueous solution of a zirconium salt containing 0.42-0.7 mole of sulphate anion (SO) per mole of zirconium cation at a temperature of not greater than 50&#xb0; C., in the presence of a cerium salt to form a cerium-zirconium mixed hydroxide, and then calcining the cerium&#x2014;zirconium mixed hydroxide to form a mixed oxide. The mixed oxides possess good thermal stability and are essentially single phase and are suitable as promoters and catalyst supports in, particularly, automobile exhaust systems.

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Swinton, United Kingdom

Gavin Edwards