Catalyst – solid sorbent – or support therefor: product or process – Catalyst or precursor therefor – Metal – metal oxide or metal hydroxide
Reexamination Certificate
1999-02-24
2001-04-24
Wood, Elizabeth D. (Department: 1755)
Catalyst, solid sorbent, or support therefor: product or process
Catalyst or precursor therefor
Metal, metal oxide or metal hydroxide
C502S302000, C502S303000, C502S304000, C502S325000, C502S328000, C502S329000, C502S330000, C502S333000, C502S334000, C502S339000, C502S340000, C502S341000, C502S344000, C502S349000, C502S350000, C502S351000, C502S352000, C502S355000, C502S439000
Reexamination Certificate
active
06221805
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a high heat-resistant catalyst support which is used in an exhaust-gas-purifying catalyst, a catalyst which uses the catalyst support, and a process for producing the same.
2. Description of the Related Art
For instance, Japanese Unexamined Patent Publication (KOKAI) No. 7-075,735 discloses a catalyst support. The catalyst support is composed of amorphous alumina as a major component, and contains an NO
x
storage element which is composed of an alkali metal, an alkaline-earth metal or a rare-earth element. According to the publication, in the support, the alumina and the NO
x
storage element do not form stable compounds in a temperature range where the amorphous alumina does not crystallize. Consequently, the catalyst support is inhibited from exhibiting a decreased NO
x
storage ability. Further, since the NO
x
storage element can be mixed in the amorphous alumina in a highly dispersed manner, the sulfates are less likely to grow granularly even when the NO
x
storage element reacts with sulfuric oxides to produce the sulfates. Thus, the decrease in the NO
x
storage ability (i.e., the sulfur poisoning), which is caused by the granular growth of the sulfates, is less likely to occur. Furthermore, since the generated sulfates are very fine, they are likely to be reduced in a reducing atmosphere. Hence, the catalyst support has an advantage in that the NO
x
storage ability of the NO
x
storage element can be recovered.
The aforementioned catalyst support is produced by a sol-gel method in which an alkoxide is used as a raw material. However, since the alkoxide is expensive, the resulting catalyst support is expensive as well. Further, since the support powder, which is prepared by the sol-gel method, is constituted by fine particles, there might arise a possibility that the catalyst support exhibits a reduced specific surface area by granular growth when it is used at elevated temperatures exceeding 1,000° C.
SUMMARY OF THE INVENTION
The present invention has been developed in view of the aforementioned circumstances. It is therefore an object of the present invention to provide a catalyst support, which can be produced without using an alkoxide, which is less expensive and which is good in heat resistance, and a catalyst which uses the catalyst support.
A first aspect of the present invention is a catalyst support, comprising:
a composite oxide powder produced by spraying and burning a W/O type emulsion, the W/O type emulsion including an aqueous solution dispersed in an organic solvent, the aqueous solution containing aluminum as a major component and at least one co-metallic element in addition to the aluminum.
In the catalyst support, the co-metallic element can preferably be at least one member selected from the group consisting of alkaline-earth metals and rare-earth elements. Moreover, magnesium can preferably be excluded.
A second aspect of the present invention is a first catalyst, comprising:
a composite oxide powder produced by spraying and burning a W/O type emulsion, the W/O type emulsion including an aqueous solution dispersed in an organic solvent, the aqueous solution containing aluminum as a major component and a noble metal element.
A third aspect of the present invention is a second catalyst, comprising:
a composite oxide powder produced by spraying and burning a W/O type emulsion, the W/O type emulsion including an aqueous solution dispersed in an organic solvent, the aqueous solution containing aluminum as a major component, at least one co-metallic element selected from the group consisting of elements of group IIa in the periodic table of the elements, elements of group IIIa therein, elements of group IVa therein, elements of group Va therein, elements of group VIa therein, elements of group VIIa therein, elements of group IIb therein, Ga, Si, Ge and Sn, and a noble metal element.
A fourth aspect of the present invention is a third catalyst, comprising:
a catalyst support including:
a composite oxide powder produced by spraying and burning a W/O type emulsion, the W/O type emulsion including an aqueous solution dispersed in an organic solvent, the aqueous solution containing aluminum as a major component and at least one co-metallic element selected from the group consisting of elements of group IIa in the periodic table of the elements, elements of group IIIa therein, elements of group IVa therein, elements of group Va therein, elements of group VIa therein, elements of group VIIa therein, elements of group IIb therein, Ga, Si, Ge and Sn; and
a noble metal loaded on the catalyst support.
A fifth aspect of the present invention is a fourth catalyst, comprising:
a catalyst support including:
a composite oxide powder produced by spraying and burning a W/O type emulsion, the W/O type emulsion including an aqueous solution dispersed in an organic solvent, the aqueous solution containing aluminum as a major component and at least one co-metallic element in addition to the aluminum; and
a structure, loaded on the catalyst support, in which a noble metal is loaded on at least one member selected from the group consisting of strontium oxide and barium oxide.
In the fourth catalyst, the co-metallic element can preferably be at least one member selected from the group consisting of alkaline-earth metals.
A sixth aspect of the present invention is a process for producing the catalyst support, comprising the steps of:
preparing a W/O type emulsion including an aqueous solution dispersed in an organic solvent, the aqueous solution containing aluminum as a major component and at least one co-metallic element in addition to the aluminum; and
spraying and burning the W/O type emulsion, thereby forming a composite oxide powder.
In the production process, the co-metallic element can preferably be at least one member selected from the group consisting of alkaline-earth metals and rare-earth elements. Moreover, magnesium can preferably be excluded.
A seventh aspect of the present invention is a process for producing the first catalyst, comprising the steps:
preparing a W/O type emulsion including an aqueous solution dispersed in an organic solvent, the aqueous solution containing aluminum as a major component and a noble metal element; and
spraying and burning the W/O type emulsion, thereby forming a composite oxide powder.
An eighth aspect of the present invention is a process for producing the second catalyst, comprising the steps:
preparing a W/O type emulsion including an aqueous solution dispersed in an organic solvent, the aqueous solution containing aluminum as a major component, at least one co-metallic element selected from the group consisting of elements of group IIa in the periodic table of the elements, elements of group IIIa therein, elements of group IVa therein, elements of group Va therein, elements of group VIa therein, elements of group VIIa therein, elements of group IIb therein, Ga, Si, Ge and Sn, and a noble metal element; and
spraying and burning the W/O type emulsion, thereby forming a composite oxide powder.
A ninth aspect of the present invention is a process for producing the third catalyst, comprising the steps:
preparing a W/O type emulsion including an aqueous solution dispersed in an organic solvent, the aqueous solution containing aluminum as a major component and at least one co-metallic element selected from the group consisting of elements of group IIa in the periodic table of the elements, elements of group IIIa therein, elements of group IVa therein, elements of group Va therein, elements of group VIa therein, elements of group VIIa therein, elements of group IIb therein, Ga, Si, Ge and Sn;
spraying and burning the W/O type emulsion, thereby forming a composite oxide powder; and
loading a noble metal on the composite oxide powder.
The loading of the noble metal can preferably be carried out without using water for diluting a noble-metal chemical liquid, but by using an organic solvent, such as alcohol.
A tenth aspect of the present invention is a p
Kamiya Nobuo
Kuno Oji
Miyoshi Naoto
Sugiyama Masahiko
Takatori Kazumasa
Oliff & Berridg,e PLC
Toyota Jidosha & Kabushiki Kaisha
Wood Elizabeth D.
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