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US 5,712,218 AGranted
Cerium/zirconium mixed oxide catalysts having high/stable specific surface areas
AssigneeRhone-Poulenc Chimie
InventorsThierry Chopin, Olivier Touret
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AssigneeRhone-Poulenc Chimie
InventorsThierry Chopin, Olivier Touret
Estimating the term…
Cerium/zirconium mixed oxides (optionally including yttrium values), comprising solid solutions thereof, having contents of zirconium of up to 60 atom % and having thermally stable, very high specific surface areas at least greater than 80 m.sup.2 /g, preferably at least 100 m.sup.2 /g and more preferably at least 150 m.sup.2 /g, are well suited as catalysts and/or catalyst supports, notably for the treatment/conversion of vehicular exhaust gases; such Ce.sub.x Zr.sub.1-x O.sub.2 particulates are conveniently prepared by thermally treating an aqueous solution of soluble compounds of cerium and zirconium (and optionally yttrium), e.g. the nitrates thereof, present in the desired stoichiometric amounts, and thence recovering and, if appropriate, calcining the reaction product thus formed.
A cerium/zirconium mixed oxide presenting a pure, monophasic CeO.sub.2 cubic crystalline habit of the type CeO.sub.2 and having a specific surface area of at least 30 m.sup.2 /g after calcination at 800.degree. C. for 6 hours.
Particulates of a monophasic solid solution of a cerium/zirconium mixed oxide having the formula Ce.sub.x Zr.sub.1-x O.sub.2, in which x is a number ranging from 0.5 to less than 1 and retaining a specific surface area of at least 50 m.sup.2 /g when heated at 800.degree. C. for six hours, wherein the zirconium is incorporated in the crystalline lattice of the cerium oxide.
A cerium/zirconium mixed oxide having the formula Ce.sub.x Zr.sub.1-x O.sub.2 in which x is greater than 0.5 and less than 1, said mixed oxide having a specific surface area of at least 80 m.sup.2 /g and retaining a specific surface area of at least 50 m.sup.2 /g when heated at 800.degree. C. for six hours.
A cerium/zirconium mixed oxide presenting a pure, monophasic CeO.sub.2 cubic crystalline habit of the type CeO.sub.2, having the formula Ce.sub.x Zr.sub.1-x O.sub.2 in which x is a number ranging from 0.5 to 0.8 and having a specific surface area of at least 30 m.sup.2 /g after calcination at 800.degree. C. for 6 hours.
A composition based on cerium and zirconium which after heating at a temperature between 400.degree. and 800.degree. C., presents a pure monophasic CeO.sub.2 cubic crystalline habit and wherein zirconium is incorporated in the crystalline habit of the cerium oxide.
Dependencies are inferred from the claim text.