Perovskite catalysts and process for their preparation
AssigneeExxon Research & Engineering Co.
InventorKenneth S. Wheelock
Life of this patent
Estimating the term…
Abstract
A high surface area perovskite catalyst comprises a perovskite containing at least one transition metal composited with a spinel-coated metal oxide support. The catalyst is prepared by forming a surface spinel on a metal oxide and subsequently co-impregnating or co-depositing the appropriate perovskite precursor component on the spinel coated metal oxide, followed by calcination at a temperature of at least 540.degree. C. A preferred catalyst is LaCoO.sub.3 supported on a spinel-covered alumina.
Claims22
In a supported perovskite catalyst for hydrocarbon conversion and hydrocarbon treating processes which comprises a perovskite comprising at least one transition metal, the improvement which comprises:
- a support comprising a metal oxide and a spinel on the surface of said metal oxide, said spinel being selected from the group consisting of normal spinel and inverse spinel, said normal spinel having an empirical formula MY.sub.2 O.sub.4 wherein M and Y in said normal spinel formula are cations of different metals and wherein one of said cations of said normal spinel formula is the metal of said metal oxide, said inverse spinel having an empirical formula Y(XY)O.sub.4 wherein Y and X in said inverse spinel formula are cations of different metals, and wherein one of said cations of said inverse spinel formula is the metal of said metal oxide, said supported catalyst having a surface area of at least 65 m.sup.2 /g.
A supported perovskite catalyst which comprises a perovskite selected from the group consisting of LaCoO.sub.3, LaCrO.sub.3, CaThO.sub.3, AgNbO.sub.3 and SrZrO.sub.3, said perovskite being composited with a support comprising alumina and a spinel on the surface of said alumina, said spinel being MgAl.sub.2 O.sub.4.
A process for the preparation of a supported perovskite catalyst for hydrocarbon conversion and hydrocarbon treating processes, which comprises:
- a. treating a metal oxide having an initial surface area ranging from about 50 to about 250 m.sup.2 /g with at least one metal component such that the algebraic sum of the ionic charges of the metal of said metal oxide and the metal of said metal component corresponds to the algebraic sum of cations required for spinel formation, said spinel being selected from the group consisting of normal spinel and inverse spinel, said normal spinel having an empirical formula MY.sub.2 O.sub.4, wherein M and Y in said normal spinel formula are cations of different metals, said inverse spinel having an empirical formula Y(XY)O.sub.4, wherein Y and X in said inverse spinel formula are cations of different metals;
- b. calcining the treated metal oxide resulting from step (a) at a temperature sufficient to produce a spinel on at least a portion of the surface of said treated metal oxide;
- c. treating the calcined metal oxide having said surface spinel thereon resulting from step (b) with perovskite precursor metal components comprising at least one transition metal component;
- d. calcining at a temperature of at least 540.degree. C. the perovskite precursor treated-material resulting from step (c) to convert said perovskite precursors to a perovskite and thereby produce a supported perovskite catalyst.
A process for the preparation of a supported LaCoO.sub.3 persovkite catalyst which comprises:
- a. impregnating a gamma alumina gel having a surface area of about 185 m.sup.2 /g with Mg(NO.sub.2).sub.2 ;
- b. calcining the impregnated alumina alumina gel at a temperature of about 540.degree. C., thereby producing a surface coating of MgAl.sub.2 O.sub.4 spinel on said gamma alumina;
- c. impregnating the spinel-coated alumina resulting from step (b) with an equimolar solution of La(NO.sub.3).sub.3.6H.sub.2 O and Co(NO.sub.3).sub.2.6H.sub.2 0;
- d. calcining at a temperature of at least 540.degree. C. the impregnated material resulting from step (c) and
- e. recovering a supported LaCoO.sub.3 catalyst.
Dependencies are inferred from the claim text.