Catalyst – solid sorbent – or support therefor: product or process – Catalyst or precursor therefor – Organic compound containing
Reexamination Certificate
2000-07-27
2002-10-15
Bell, Mark L. (Department: 1755)
Catalyst, solid sorbent, or support therefor: product or process
Catalyst or precursor therefor
Organic compound containing
C502S309000, C502S350000, C502S527240, C428S221000, C428S372000, C428S373000, C428S365000, C428S364000, C428S357000, C162S141000, C162S146000, C162S157300, C528S184000
Reexamination Certificate
active
06465389
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a heat resistant catalyst sheet, and a process for producing same. More specifically, the present invention relates to a heat resistant catalyst sheet, whose catalytic activity can be retained for a long period of time, because a catalyst component contained therein hardly leaves from the catalyst sheet, and which is superior in its heat resistance and its processability, and relates to a process for producing said heat resistant catalyst sheet. The heat resistant catalyst sheet in accordance with the present invention can be used preferably for, for example, reduction of nitrogen oxides, oxidation of organic substances such as organic solvents, agricultural chemicals and surfactants, and decomposition of dioxin.
BACKGROUND OF THE INVENTION
As a heat resistant catalyst sheet, JP-B 7-22709 discloses a nitrogen oxide removal catalyst sheet. Said catalyst sheet is obtained by supporting vanadium oxide on solid-carrying paper, which is obtained by impregnating ceramics paper with a mixture of titania sol and silica sol, followed by drying and calcining, wherein said ceramics paper is made from a silica-alumina based ceramics fiber, or an alumina based ceramics fiber.
Further, as another heat resistant catalyst sheets, Japanese Patent No. 2562077 discloses a nitrogen oxide removal catalyst sheet. Said catalyst sheet is obtained by adsorbing and supporting vanadium oxide on solid-carrying paper, which is obtained by impregnating ceramics paper with TiO
2
sol, followed by drying and calcining, and further impregnating the resulting paper with SiO
2
sol, followed by drying, wherein said ceramics paper is made from a ceramics fiber containing SiO
2
sol.
Each of the references referred to above is incorporated herein by reference in its entirety.
However, each of the catalyst sheets disclosed in the above-mentioned publications has problems such that (i) a catalyst component contained therein easily leaves from the catalyst sheet, (ii) its processability is not excellent, and (iii) it does not exhibit enough catalyst performance.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide a catalyst sheet, whose catalytic activity can be retained for a long period of time, because a catalyst component contained therein hardly leaves from the catalyst sheet, and which is superior in its heat resistance and its processability, and a process for producing said catalyst sheet.
The present inventors have undertaken extensive studies to develop a heat resistant catalyst sheet. As a result, it has been found that a catalyst sheet obtained by combining an aramid fiber and a catalyst component-containing titania fiber can accomplish the object of the present invention, and thereby the present invention has been obtained.
The present invention provides a heat resistant catalyst sheet comprising an aramid fiber and a catalyst component-containing titania fiber.
Further, the present invention provides a process for producing a heat resistant catalyst sheet, which comprises the step of making paper from a mixture of an aramid fiber and a catalyst component-containing titania fiber.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
DETAIL DESCRIPTION OF THE INVENTION
A catalyst component-containing titania fiber used in the present invention is not particularly limited. As examples of the catalyst component-containing titania fiber, those disclosed in JP-A 11-5036 and Japanese Patent Application No. 10-333786 are enumerated. Each of the references referred to above is incorporated herein by reference in its entirety. Here, the term, “titania fiber”, means a fiber containing a TiO
2
component.
Specific examples of the catalyst component-containing titania fiber used in the present invention are those satisfying the following conditions (1) to (7):
(1) titanium oxide is contained in an amount of not less than about 50% by weight, provided that the weight of the catalyst component-containing titania fiber is assigned to be 100% by weight,
(2) a fiber length is not less than about 50 &mgr;m, which length is not an average fiber length, but a length of respective fibers,
(3) a fiber diameter is within a range of from about 2 to about 100 &mgr;m,
(4) a specific surface area measured by a BET method is not less than about 10 m
2
/g, and preferably from about 20 to about 300 m
2
/g,
(5) a pore volume measured by a nitrogen adsorption method is not less than about 0.05 cc/g,
(6) a pore volume having a pore radius of not less than 10 Å is not less than about 0.02 cc/g, and
(7) a pore radius peak is from about 10 to about 300 Å, and preferably from about.10 to about 100 Å.
A catalyst component used in the present invention is not particularly limited, and may be appropriately determined depending on uses of the catalyst sheet. Examples of the catalyst component usually used are at least one metal selected from the group consisting of V, W, Al, As, Ni, Zr, Mo, Ru, Mg, Ca, Fe, Cr and Pt, at least one metal oxide selected from the group consisting of oxides of said metals, and at least one composite oxide selected from the group consisting of composite oxides of said metals.
When the catalyst sheet in accordance with the present invention is used for reducing nitrogen oxides, it is recommendable to use, as the catalyst component, at least one preferred metal selected from the group consisting of V, W and Mo, or at least one metal oxide selected from the group consisting of oxides of said preferred metals, or at least one composite oxide selected from the group consisting of composite oxides of said preferred metals.
An amount of the catalyst component contained in the catalyst sheet is not particularly limited, and may be determined depending on uses of the catalyst sheet. The amount of the catalyst component is usually from about 0.001 to about 50% by weight in terms of metal oxide, provided that said metal contained in the catalyst sheet is converted into its metal oxide, and the weight of the catalyst component-containing titania fiber is assigned to be 100% by weight.
A process for producing the catalyst component-containing titania fiber is not particularly limited. As examples of the production process thereof, those comprising steps mentioned in the following Process-1 and Process-2 are enumerated. It is necessary to carry out respective steps of from Step-1 to Step-4, through which a precursor fiber is obtained, under atmosphere of an inert gas such as nitrogen gas. However, the obtained fiber precursor can be handled in the air.
Process-1
Step-1 of dissolving a titanium alkoxide in an alcohol such as isopropyl alcohol to obtain a solution,
Step-2 of hydrolyzing the obtained solution to obtain a slurry,
Step-3 of dissolving a vanadium compound in the slurry to obtain a spinning solution,
Step-4 of spinning the spinning solution to obtain a precursor fiber, and
Step-5 of calcining the precursor fiber to obtain a titania fiber.
Process-2
Step-1 of dissolving a titanium alkoxide and a vanadium compound in an alcohol such as isopropyl alcohol,
Step-2 of hydrolyzing the obtained solution to obtaining a slurry,
Step-3 of adding a solvent to the slurry, followed by mixing, and then further adding a silica compound thereto to obtain a spinning solution,
Step-4 of spinning the spinning solution to obtain a precursor fiber, and
Step-5 of calcining the precursor fiber to obtain a titania fiber.
A unit weight of the catalyst component-containing titania fiber present in the catalyst sheet in accordance with the present invention is not particularly limited, and may be determined depending on uses o
Koike Hironobu
Oki Yasuyuki
Takeuchi Yoshiaki
Bell Mark L.
Hailey Patricia L.
Sumitomo Chemical Company Limited
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