Catalyst – solid sorbent – or support therefor: product or process – Catalyst or precursor therefor – Nitrogen compound containing
Reexamination Certificate
2003-02-27
2003-09-16
Wood, Elizabeth D. (Department: 1755)
Catalyst, solid sorbent, or support therefor: product or process
Catalyst or precursor therefor
Nitrogen compound containing
C502S162000, C502S164000, C502S167000, C502S339000
Reexamination Certificate
active
06620761
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to the field of catalytic combustion, and provides a catalyst coating that adheres well to a metal strip used to construct a catalytic combustor.
The catalyst of the present invention is intended for use in promoting the combustion of methane to yield carbon dioxide and water, but it may also have other applications, such as in catalyzing a steam reforming reaction, and/or a water-gas shift reaction.
It has been known to combine palladium and zirconia in a catalyst formulation. The present invention provides an improved catalyst composition which includes palladium and zirconia, and which has high catalytic activity. The catalyst of the present invention also makes it possible to use palladium nitrate from a variety of sources.
SUMMARY OF THE INVENTION
The present invention comprises a catalyst composition which includes palladium and zirconium, and a method of making that composition. The method comprises combining a solution of palladium nitrate with a solution of an alkyl ammonium hydroxide, and mixing the result with a hydrous zirconium oxide so as to form a suspension. The alkyl ammonium hydroxide may be tetramethylammonium hydroxide or tetrabutylammonium hydroxide. More generally, the alkyl may be selected from the group consisting of tetraethyl, tetramethyl, tetrabutyl, and tetraethanol.
The invention also includes the composition made according to the above-described method.
It is preferred that the composition also include nitric acid, in an amount such that the number of mols of nitric acid is approximately equal to the number of mols of the alkyl ammonium hydroxide.
Also, the amount of alkyl ammonium hydroxide in the composition of the present invention is preferably such that the ratio of mols of alkyl ammonium hydroxide to mols of palladium is in the range of about 1 to about 6.
The ratio of weight of palladium to weight of zirconium, in the composition of the present invention, is preferably in the range of about 0.04 to about 0.20.
The invention therefore has the primary object of providing a catalyst composition, and a method of making the catalyst composition, for use in catalyzing combustion, and/or for use in catalyzing other reactions such as steam reforming and water-gas shift reactions.
The invention has the further object of providing a catalyst containing palladium and zirconium, wherein the catalyst adheres well to a metal surface.
The invention has the further object of providing a catalyst as described above, wherein the catalyst exhibits a high level of activity.
The invention has the further object of providing a catalyst containing palladium and zirconium, wherein the palladium can be derived from palladium nitrate obtained from a variety of sources.
The reader skilled in the art will recognize other objects and advantages of the present invention, from a reading of the following brief description of the drawings, the detailed description of the invention, and the appended claims.
REFERENCES:
patent: 5061464 (1991-10-01), Cordonna et al.
Catacel Corp.
Ellberg William H.
Wood Elizabeth D.
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