Rhodia Operations

Magnesium Elektron, Inc.

Clare Jones

Emmanuel Rohart

Julien Hernandez

Rui Jorge Coelho Marques

Deborah Jayne Harris

Colin Norman

Mila Bortun

Gavin Edwards

Ian Chisem

Yasuhide Takao

Laure Bisson

Deborah Jane Harris

Rui Miguel Jorge Coelho Marques

Deborah Jayme Harris

Ian Mel Chemicals Chisem

Colin Mel Chemicals Norman

Gavin Mel Chemicals Edwards

A composition based on cerium, zirconium and tungsten is described. The composition has a content expressed as an oxide, of which cerium is from 5% to 30% of the composition, tungsten is from 2% to 17% of the composition, and the remainder of the composition is zirconium. After aging at 750&#xb0; C. under an air atmosphere including 10% water, it has a two-phase crystallographic structure having a tetragonal zirconia phase and a monoclinic zirconia phase, with no presence of a crystalline phase including tungsten. The composition can be used as a catalyst, especially in an SCR process.

Composition based on cerium, zirconium and tungsten, preparation process and use in catalysis

The invention relates to a method for treating a gas containing nitrogen oxides (NOx), in which an NOx-reduction reaction is carried out using a nitrogen-containing reducing agent, which invention is characterized in that the catalyst used for the reduction reaction is a catalytic system containing a composition comprising zirconium, cerium and niobium in the following percentages by weight, expressed in terms of the weight of oxide: 10-50% of cerium, 5-20% of niobium and the remainder consisting of zirconium.

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A method is described for treating a gas including nitrogen oxides (NO). The method can include conducting a reduction reaction of the nitrogen oxides with a nitrogen reducing agent. Further described, is a catalyst used for the reduction reaction which is a catalytic system including a composition based on cerium oxide and including niobium oxide in a proportion by a mass of from 2% to 20%.

Method for treating a gas containing nitrogen oxides (NOx), in which a composition comprising cerium oxide and niobium oxide is used as a catalyst

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

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Liverpool, United Kingdom

Clare Jones