Catalyst – solid sorbent – or support therefor: product or process – Catalyst or precursor therefor – Metal – metal oxide or metal hydroxide
Reexamination Certificate
2000-07-27
2002-12-17
Silverman, Stanley S. (Department: 1754)
Catalyst, solid sorbent, or support therefor: product or process
Catalyst or precursor therefor
Metal, metal oxide or metal hydroxide
C502S242000, C502S507000
Reexamination Certificate
active
06495489
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an acid resistant catalyst sheet, and a process for producing the same, specifically, the present invention relates to an acid 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 acid resistance against gases such as SOx and HCl and in its processability, and a process for producing said catalyst sheet. The acid resistant catalyst sheet in accordance with the present invention can be used preferably for, for example, reduction of nitrogen oxides, oxidation of organic substances and decomposition of dioxin.
BACKGROUND OF THE INVENTION
As a catalyst sheet known in the art, JP-B 4-12183 discloses a catalyst sheet, which is obtained by forming a titania fiber so as to be interwoven with a glass fiber in a manner such that the glass fiber is impregnated with a titania hydrosol, and then, the hydrosol is frozen in one direction, followed by fusion of the frozen portion.
Further, as another catalyst sheet known in the art, JP-B 5-64745 disclosed a catalyst sheet, which is obtained by impregnating a honeycomb laminate with a mixed dispersing agent comprising catalyst particles, silica sol and the like to fix the catalyst particles between fiber gaps of the honeycomb laminate and on the surfaces of the honeycomb laminate, wherein the honeycomb laminate comprises paper made from a mixture of a glass fiber, mountain leather and a binder.
Each of the references referred to above is incorporated herein by reference in its entirety.
Although the catalyst sheet disclosed in said JP-B 4-12183 has some degree of acid resistance, it has a problem that the titania fiber contained therein leaves from the sheet when vibrated mechanically because of rigidity of the sheet. Said catalyst sheet also has a problem that an additional different catalyst component contained therein leaves easily from the catalyst sheet because of poor bonding strength between the different additional catalyst component and the fibers, wherein said catalyst sheet can be produced according to the process described in said JP-B 4-12183.
On the other hand, the catalyst sheet disclosed in said JP-B 5-64745 has the following problems: (1) use of said silica sol and the like deteriorate properties of the catalyst particles contained therein, and (2) the catalyst particles contained therein leaves easily from the catalyst sheet.
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 acid resistance against acid gases such as SOx and HCl and in its processability, and a process for producing said catalyst sheet.
The present inventors have undertaken extensive studies to develop an acid resistant catalyst sheet. As a result, it has been found that a catalyst sheet comprising a catalyst component-containing titania fiber, a glass fiber and a specific resin can solve the foregoing problems, and thereby the present invention has been obtained.
The present invention provides an acid resistant catalyst sheet comprising:
a catalyst component-containing titania fiber;
a glass fiber; and
at least one resin selected from the group consisting of an epoxy resin, a phenolic resin, a melamine resin, a furan resin, a polyimide resin, a silicone resin, a fluororesin, a polyphenylene sulfide resin and a polyether ether ketone resin.
Further, the present invention provides a process for producing an acid resistant catalyst sheet, which comprises he step of making paper from a mixture containing:
a catalyst component-containing titania fiber;
a glass fiber; and
at least one resin selected from the group consisting of an epoxy resin, a phenolic resin, a melamine resin, a furan resin, a polyimide resin, a silicone resin, a fluororesin, a polyphenylene sulfide resin and a polyether ether ketone resin.
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 micro 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 selected 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-prefer-red 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 the 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 under atmosphere of an inert gas such as nitrogen gas, through which steps a precursor fiber is obtained. However, the obtained precursor fiber 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 hy
Koike Hironobu
Oki Yasuyuki
Takeuchi Yoshiaki
Johnson Edward M.
Silverman Stanley S.
Sumitomo Chemical Company Limited
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