JPH11267523A - Inorganic fiber cloth for substrate of denitration catalyst substrate, manufacture thereof, and denitration catalyst - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inorganic fiber cloth for a denitration catalyst substrate having high durability (mechanical strength and corrosion resistance) even if the cloth is thin, and possible to be easily industrially manufactured to provide a method for manufacturing the cloth, and to provide a denitration catalyst. SOLUTION: (1) This inorganic fiber cloth for a denitration catalyst substrate is produced by successively forming a titanium oxide layer and an organic binder layer on an inorganic fiber cloth 3. (2) This method for manufacturing an inorganic fiber cloth for a denitration catalyst substrate includes processes of impregnating the inorganic fiber cloth 3 with a sol or a slurry of titanium oxide, drying the cloth, further impregnating the resultant cloth with an emulsion or a solution containing an organic binder containing at least one of vinyl acetate, acrylic amide, polyvinyl alcohol, and carboxymethyl cellulose, and drying again the cloth. (3) This denitration catalyst is produced by depositing a catalyst on the inorganic fiber cloth.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inorganic fiber woven fabric for a denitration catalyst substrate, a method for producing the same, and a denitration catalyst. More specifically, the present invention relates to an inorganic fiber woven fabric used as a substrate for a flue gas denitration plate catalyst. The present invention relates to a production method thereof and a denitration catalyst using the same.

[0002]

2. Description of the Related Art A plate catalyst is produced by rolling and coating a catalyst paste on a substrate. As the base material, a wire mesh inorganic fiber woven fabric (hereinafter, sometimes referred to as a woven fabric) containing silicon oxide (silica) and aluminum oxide (alumina) as main components is used. Various proposals have been made to impart mechanical strength, heat resistance and acid resistance as a material.

For example, Japanese Patent Application Laid-Open No. 3-65246 discloses that an intermediate layer comprising a sol-like substance such as titania sol, a stable oxide fine powder such as titania and an organic binder such as polyvinyl alcohol is formed on a woven fabric. Has been proposed. Also, JP-A-4-71642
In Japanese Patent Application Publication No. 2002-264, a method for producing a plate-shaped catalyst is proposed in which a woven fabric is impregnated with a reinforcing agent composed of titanium oxide, silica, and polyvinyl alcohol, and then dried to form a reinforcing screen, a catalyst paste is applied thereto, and dried and fired. ing.

[0004] By impregnating a woven fabric with a solution containing an organic binder and drying, the fibers constituting the woven fabric are bonded to each other to increase the rigidity as a yarn. The contact points of the fibers are restrained, the bending stiffness as a woven fabric is increased, and the handleability during catalyst production is improved. Since such an effect can be obtained even when the thickness of the coating film containing the organic binder is small, it is particularly important in recent years in which a thinner catalyst is required. However, when an organic binder is used, the organic binder is oxidized by baking during the production of the catalyst, so that the fibers are easily exposed to the catalyst components and atmospheric gas, and the strength of the woven fabric is reduced. Was. In addition, in the method of impregnating a woven fabric with a mixture of a sol or slurry of an inorganic oxide and an organic binder, the properties are liable to be unstable when these components are mixed, and thus lacks versatility as an industrial production method. There was a problem.

[0005] Also, Japanese Patent Application Laid-Open No. H5-222195 discloses that
An oxide of an alkaline earth metal contained in the inorganic woven fiber,
In order to prevent the catalytic component and the acidic component contained in the reaction gas from reacting and lowering the tensile strength of the woven fabric, the sol or slurry of an inorganic oxide such as silica, zirconia, or titanium oxide (titania) is used as an inorganic fiber. There has been proposed a method of impregnating a woven fabric and providing a coating film of an inorganic oxide on the surface of the fiber to improve the corrosion resistance of the fiber.

However, when only the inorganic binder and the inorganic oxide are coated on the inorganic fiber woven fabric, if the coating amount of these components is small, sufficient bonding between the fibers cannot be ensured, and sufficient woven fabric is not obtained. Rigidity cannot be obtained. Increasing the amount of coating increases the thickness of the woven fabric, which is contrary to the demand for a thin catalyst. In addition, the thickness of the woven fabric itself has been reduced due to the thinner catalyst, and the rigidity of the woven fabric itself has been reduced. There is a problem that the stiffness in the direction is reduced, and the handleability of catalyst production is greatly reduced.

[0007]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the prior art, and has excellent durability (mechanical strength and corrosion resistance) even if it is thin, and can be easily manufactured industrially. An object of the present invention is to provide a possible inorganic fiber woven fabric for a denitration catalyst carrier, a method for producing the same, and a denitration catalyst.

[0008]

The invention claimed in the present application is as follows. (1) An inorganic fiber woven fabric for a denitration catalyst substrate, wherein a titanium oxide layer and an organic binder layer are sequentially formed on the inorganic fiber woven fabric. (2) After impregnating the inorganic fiber woven fabric with a sol or slurry of titanium oxide and drying, impregnating with an emulsion or solution of an organic binder comprising at least one of vinyl acetate, acrylamide, polyvinyl alcohol and carboxymethylcellulose. A method for producing an inorganic fiber woven fabric for a denitration catalyst substrate, comprising re-drying. (3) A denitration catalyst obtained by supporting a catalyst on the inorganic fiber woven fabric described in (1) or (2).

[0009]

According to the present invention, before forming a coating of an organic binder on an inorganic fiber woven fabric, the sol or slurry of titanium oxide is impregnated and dried, and the surface of the fiber constituting the woven fabric is made of titanium oxide having corrosion resistance. Form a layer. If the coating layer of the organic binder is formed before the titanium oxide layer, the organic binder is oxidized by baking during the production of the catalyst, and the fiber surface is not protected,
The mechanical strength of the woven fabric decreases. In addition, since the titanium oxide coating layer alone is easy to peel off from the fiber surface and has a weak function of filling the fibers, the woven fabric coated with titanium oxide is further impregnated with an emulsion or solution of an organic binder and dried. An organic binder layer is formed.

By adopting such a configuration and a manufacturing method, the circumference of the fiber can be covered with an organic binder layer having few defects and having high elasticity and ductility. A strong inorganic fiber woven fabric can be obtained. Further, the fibers in the horizontal direction and the vertical direction are sufficiently bonded to each other, and excellent rigidity against bending of the woven fabric can be obtained. Furthermore, even if the organic binder is oxidized by baking during the production of the catalyst, since the surface of the woven fabric is covered with the titanium oxide layer, the reaction with the catalyst component and the exhaust gas component can be prevented, and the strength of the woven fabric decreases. Nothing. Further, in the present invention, since the titanium oxide layer and the organic binder layer are formed in separate steps, the raw materials can be freely selected and the carrying amount of each component can be freely determined as compared with a case where these components are mixed and used. Can be prepared. Therefore, even when the required properties of the woven fabric are changed, it is possible to easily select the raw materials and optimize the manufacturing conditions and the like.

In the present invention, the titanium oxide layer is preferably formed as dense as possible from the viewpoint of improving the corrosion resistance to the catalyst component and the exhaust gas component. Therefore,
When using a titanium oxide slurry, it is preferable to use titanium oxide as fine particles as possible. There is no particular limitation on the layer thickness of the titanium oxide layer, but when the layer thickness is large, the corrosion resistance of the fiber is improved, but delamination occurs, the corrosion resistance is easily reduced, and a thin woven fabric cannot be obtained. It is preferable to select as appropriate according to the properties of the woven fabric. Adjustment of layer thickness
It can be carried out by adjusting the concentration of the titanium oxide sol or slurry. If the sol or slurry is used at a high concentration, the layer thickness becomes large.

For the formation of the organic binder layer, an emulsion or solution comprising at least one of vinyl acetate, acrylamide, polyvinyl alcohol and carboxymethyl cellulose is used. There is no particular limitation on the layer thickness of the organic binder layer, but when the layer thickness is large, the effect of filling between the fibers is improved, and the rigidity of the woven fabric in the bending direction can be increased. The thickness of the woven fabric becomes large and the fibers are easily cut, so that it is preferable to appropriately select the woven fabric in consideration of the required properties of the woven fabric and the external force applied during the production of the catalyst. The layer thickness of the organic binder can be adjusted according to the concentration of the organic binder. The inorganic fiber woven fabric used in the present invention is not particularly limited. However, from the viewpoint of production cost and the like, it is preferable that a glass fiber mainly composed of silicon oxide (silica) and aluminum oxide (alumina) is formed into a wire mesh. .

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The method for producing a woven inorganic fiber fabric of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory diagram of an apparatus for manufacturing a woven inorganic fiber fabric according to an embodiment of the present invention. In FIG. 1, this apparatus is an impregnation tank 2 in which a strengthening liquid 1 is stored.
And a guide roller 4 for guiding the inorganic fiber woven fabric 3 into the impregnation tank.
And a sponge roller 5 provided on the woven fabric outlet side of the impregnation tank 2. In this apparatus, the inorganic fiber woven fabric 3 is guided by the guide roller 4, dipped in the reinforcing liquid 1, pulled up, and then guided by the pair of sponge rollers 5 to remove excess reinforcing liquid, and is not shown. It is led to a drying device and dried. The drying means and the like are not particularly limited, and are usually dried with hot air at a temperature of 100 to 200 ° C. For example, it is dried at a temperature of about 150 ° C. for about 30 minutes to 2 hours. Reinforcing liquid 1 comprises (1) titanium oxide sol or slurry,
Or (2) a solution or emulsion of an organic binder, and the inorganic fiber woven fabric 3 is treated with the reinforcing liquid of (1), dried, and then treated with the reinforcing liquid of (2). In addition, other components may be contained in the fortifying liquid 1 as long as the object of the present invention is achieved.

FIG. 2 is a diagram showing an example of a device for applying a catalyst paste. In FIG. 2, 2
The sheet of inorganic fiber woven fabric 8 has a catalyst paste 6 between the woven fabrics.
After being guided to a pair of rolling rollers 7 so as to sandwich it, and rolled, it is dried and calcined by a usual method to obtain a plate-like catalyst.

[0015]

The present invention will be described below with reference to examples, but the present invention is not limited to these examples. As the inorganic fiber woven fabric, a woven fabric obtained by twisting silica-alumina glass fibers (width 500 × length 500 mm, thickness 0.25 mm,
A fiber diameter of 6 μm and a fiber bundle interval of 2 mm) were used. The apparatus shown in FIG. 1 was used for impregnation with the reinforcing liquid, and drying was performed with hot air at 150 ° C. for 2 hours. The application of the catalyst paste was performed by the application device shown in FIG. After applying the catalyst paste and air drying, 5
It was calcined at 00 ° C. for 2 hours to obtain a catalyst. In the catalyst paste, titania powder (specific surface area: about 100 m ² / g), ammonium molybdate and ammonium metavanadate are weighed so that the atomic ratio (Ti / Mo / V) becomes 93/5/2, and the titania powder is added to the titania powder. After adding 60% by weight of water and kneading with a kneader for 30 minutes, silica alumina fibers were simultaneously added at a ratio of 15% by weight to the titania powder as a raw material and kneaded for another 30 minutes.

The bending strength and tensile strength in the examples were measured as follows. (1) Bending strength Bending method: 3-point support method Span distance: 20 mm Specimen width: 20 mm Load displacement speed: 2 mm / min (2) Tensile strength Specimen dimensions: 20 mm width, 60 mm length Tensile speed: 10 mm / min

Example 1 A woven fabric of silica-alumina glass fiber was immersed in a titania sol (solid content: 30% by weight), pulled up, and then dried by removing excess liquid. Next, after being immersed in a 1.6% by weight aqueous solution of polyvinyl alcohol (degree of polymerization: about 20,000), it was dried in the same manner to obtain a reinforced inorganic fiber woven fabric of the present invention. The woven fabric was coated with a catalyst paste, dried and fired to produce a plate catalyst.

Example 2 A reinforced inorganic fiber woven fabric was produced under the same conditions as in Example 1 except that the titania sol was used after diluting the concentration of the titania sol to 1/2. Similarly, a plate-like catalyst was obtained. Example 3 The same procedure as in Example 1 was repeated except that a fortifying solution obtained by mixing the titania sol and the titania slurry having a solid content of 50% by weight at a weight ratio of 1: 1 was used in place of the titania sol. A fiber woven fabric and a plate catalyst were obtained.

Example 4 A reinforced inorganic fiber woven fabric and a plate-like catalyst were used under the same conditions as in Example 1 except that an emulsion of vinyl acetate (containing 1.6% by weight) was used instead of polyvinyl alcohol. Obtained. Example 5 A reinforced inorganic fiber woven fabric and a plate catalyst were obtained under the same conditions as in Example 1 except that the titania sol was diluted to a concentration of 1% by weight and used. Example 6 The same procedure as in Example 1 was carried out except that the fortifying solution obtained by mixing the titania sol and the titania slurry having a solid content of 50% by weight at a weight ratio of 1: 1 was used in place of the titania sol. A fiber woven fabric and a plate catalyst were obtained.

Comparative Example 1 A reinforced inorganic fiber woven fabric and a plate-like catalyst were obtained under the same conditions as in Example 1 except that the woven fabric was only immersed in the titania sol but not in the aqueous polyvinyl alcohol solution. . Comparative Example 2 A reinforced inorganic fiber woven fabric and a plate-like catalyst were obtained under the same conditions as in Example 1 except that the woven fabric was not immersed in the titania sol but was immersed directly in the aqueous polyvinyl alcohol solution.

Comparative Example 3 A reinforced inorganic fiber woven fabric and a woven fabric were prepared under the same conditions as in Example 1 except that the woven fabric was immersed in a mixture of a titania sol and a polyvinyl alcohol aqueous solution at a weight ratio of 1: 1. A plate catalyst was obtained. Comparative Example 4 Example 1 was repeated except that the woven fabric was immersed in an aqueous solution of polyvinyl alcohol and then immersed in a titania sol.
Under the same conditions as described above, a reinforced inorganic fiber woven fabric and a plate-like catalyst were obtained.

Comparative Example 5 A reinforced inorganic fiber woven fabric and a plate-like catalyst were obtained under the same conditions as in Example 1 except that silica sol (solid content: 20% by weight) was used instead of titania sol. Example 1
And the thickness of the reinforcing liquid component of the reinforced inorganic fiber woven fabric obtained in Comparative Examples 1 to 5, and the tensile strength and bending strength of the plate catalyst were measured.
It was shown to.

[0023]

[Table 1]

Table 1 shows that the use of the inorganic fiber woven fabric of the present invention makes it possible to easily obtain a plate catalyst having a small thickness and excellent bending strength and tensile strength.
Further, the results of Examples 1 to 3 show that when the concentration of titania sol or slurry is increased, the thickness of the catalyst is increased, the strength is improved, and the corrosion resistance of the woven fabric is also increased. Example 4
The results show that the same effect can be obtained when vinyl acetate is used as the organic binder. From the results of Example 5, when the concentration of the titania sol or the slurry is too low, the carrying amount of the reinforcing liquid component tends to decrease, and from the results of Example 6, when the titania concentration is too high, the plate thickness of the catalyst tends to increase. Is shown.

On the other hand, since only the titanium oxide layer is formed in Comparative Example 1 and only the organic binder layer is formed in Comparative Example 2, both the bending strength and the tensile strength are reduced. In particular, in Comparative Example 2, the bending strength was low, and the bonding of the fibers was insufficient. In Comparative Example 3, a mixed solution in which a titanium oxide sol and an organic binder were mixed was used. However, since the mixing caused gelation, it was difficult to control the amount of the reinforcing liquid component carried, and the thickness of the catalyst was increased. In Comparative Example 4, since the titanium oxide layer was formed after the polyvinyl alcohol layer was formed, the strength of the catalyst was reduced. Further, in Comparative Example 5, since a silica layer was formed instead of the titanium oxide layer,
Although the concentration was low, the thickness of a certain catalyst was increased, and a certain amount of fiber binding force was obtained, but the tensile strength was reduced.

[0026]

According to the inorganic fiber woven fabric and the method for producing the same of the present invention, even if the thickness is small, the inorganic fiber woven fabric has excellent durability and industrial production can be easily performed. Further, by using the inorganic fiber woven fabric of the present invention, a denitration catalyst having excellent denitration performance can be easily obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory view of an apparatus for producing an inorganic fiber woven fabric according to an embodiment of the present invention.

FIG. 2 is a diagram showing an example of a catalyst paste application device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Reinforcing liquid, 2 ... Impregnation tank, 3 ... Inorganic fiber woven fabric, 4 ... Guide roller, 5 ... Sponge roller, 6 ... Catalyst paste, 7
... rolling rollers, 8 ... reinforced inorganic fiber woven fabric.

Claims (3)

[Claims] 1. An inorganic fiber woven fabric for a denitration catalyst substrate, wherein a titanium oxide layer and an organic binder layer are sequentially formed on the inorganic fiber woven fabric. 2. An inorganic fiber woven fabric is impregnated with a sol or slurry of titanium oxide, dried and then impregnated with an emulsion or solution of an organic binder comprising at least one of vinyl acetate, acrylamide, polyvinyl alcohol and carboxymethylcellulose. A method for producing an inorganic fiber woven fabric for a denitration catalyst substrate, comprising drying and drying again. 3. A denitration catalyst comprising a catalyst supported on the woven inorganic fiber fabric according to claim 1.