JP3145382B2 - Inorganic fiber plate catalyst - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an inorganic fiber plate catalyst, and more particularly to an inorganic fiber plate catalyst in which a catalyst composition is supported on a network substrate made of inorganic fibers.

[Prior Art] Conventionally, a woven fabric or nonwoven fabric made of inorganic fiber has been used as a catalyst substrate for purifying exhaust gas, and a catalyst which is lightweight and excellent in impact resistance has been obtained. For example, JP-A-52-39256
The catalyst component is supported on a silica cloth disclosed in Japanese Patent Application Laid-Open No. 59-193139, and the ceramic component is impregnated in a ceramic paper disclosed in Japanese Patent Application Laid-Open No. 59-193139. However, these catalysts carry a catalyst component on a ceramic substrate at a low density and thus have insufficient strength, and are not suitable for applications requiring a large-capacity and large-sized catalyst such as an exhaust gas denitration catalyst. On the other hand, in Japanese Patent Application No. 01-162880 (Japanese Patent Application Laid-Open No. Hei 3-26318), as shown in FIG. The paste is stretched and applied to the base material while being compressed by using the pressure application roller 5, and a high-density catalyst is easily obtained, and a relatively high-strength catalyst is obtained.
At this time, the catalyst paste is prevented from adhering to the application roller 5 by interposing an adhesion preventing water supply paper 4 such as pulp paper outside the base materials 1 and 2.

[Problems to be solved by the invention]

However, the prior art shown in FIG. 4 does not give sufficient consideration to the improvement in rigidity due to the composite of the reticulated base material and the catalyst component. However, there remains a problem that the strength of the obtained catalyst varies greatly depending on the location.

SUMMARY OF THE INVENTION An object of the present invention is to provide a high-strength and uniform inorganic fiber plate catalyst which eliminates the above-mentioned problems of the prior art.

[Means for solving the problem]

The above object is achieved by forming the inorganic fiber net-like base material into at least two
In an inorganic fiber plate-like catalyst comprising a stack, a space between them and the space between the mesh-like base materials filled with a catalyst component, the pitch of the meshes of the upper and lower mesh-like base materials is different from each other. An inorganic fiber plate-like catalyst in which at least two upper and lower layers of inorganic fiber base material are stacked, and a space between them and a space between the network base materials is filled with a catalyst component, wherein the shape of the mesh of the network base material is rectangular. And an inorganic fiber plate-shaped catalyst characterized in that the longitudinal directions of the meshes of the upper and lower reticulated bases are perpendicular to each other, and at least two upper and lower reticulated bases made of inorganic fiber are overlapped. In the inorganic fiber plate catalyst in which the spaces between the mesh and the mesh of the mesh are filled with the catalyst component, the warp and the weft of the inorganic fibers constituting the mesh are oblique, and the directions of both yarns are the upper and lower meshes. Opposite to each other Is achieved by the inorganic fiber shaped catalysts, characterized in that the arranged such that the.

[Action]

The present inventors have examined the problem of the prior art shown in FIG. 4 in detail, and as a result, when the inorganic fiber network base material used up and down is geometrically homogeneous, the catalyst component paste roller is used. At the time of coating, the positions of the upper and lower substrates change little by little, and the states of FIGS. 2 (A) and 2 (B) occur in stripes as shown in FIG. 3, causing cutting of the substrates and variation in strength. I found it.

That is, in the state shown in FIG. 2 (A), the catalyst paste is connected so as to be integrated front and back through the meshes 8 of the upper and lower substrates, so that the rigidity is high. The yarn is cut by applying a large force to the woven yarn at the time of application, thereby lowering the tensile strength. Conversely, in the state (B), the upper and lower connecting portions 8 of the catalyst paste are small, and the rigidity is significantly reduced. Since these two states occur in a stripe pattern, when a large-sized catalyst such as an exhaust gas denitration catalyst is to be obtained, only a catalyst lacking rigidity and tensile strength as a whole can be obtained.

On the other hand, in the catalyst according to the present invention, the upper and lower substrates are geometrically deformed or anisotropic. For this reason, the occurrence of the stripes in the state shown in FIGS. 2A and 2B due to the interference between the upper and lower substrates, which causes the above-mentioned problem of the prior art, is remarkably reduced, and a high rigidity and high tensile strength can be obtained.

The relationship between the upper and lower substrates that greatly lowers the catalyst strength will be described more specifically.

When the size of the mesh is the same, when attention is paid only to the warp yarns, the probability of the state shown in FIGS. 2A and 2B is 1/2, and therefore, as shown in FIG. When the warp of the lower base material comes under and below the mesh, the state occurs in a wide range,
Weak parts will appear widely.

As long as a net-like base material is used, it is inevitable that such a phenomenon will occur to some extent, and it is necessary to select a combination with a small degree of interference and a combination with which the strength does not greatly decrease even if it appears. FIG. 1 (A) has the greatest effect. On the other hand, the combinations based on the idea based on the reason that the strength is low are shown in FIGS. 1B and 1C.

The reason why the base material interferes and the strength is reduced as shown in FIG. 5 (A) is because the communication between the upper and lower catalysts is cut off as shown in FIG. 5 (B). Is the direction described above.

In other words, even if interference of the base material occurs, the area of the hatched portion 8 in FIG. 5 (B) only needs to be large, and in order to realize this, it is necessary to reduce the probability of simultaneous interference in the upper and lower directions. become.

In FIG. 1 (B) showing one embodiment of the present invention, since the mesh is rectangular and the direction is changed by the upper and lower substrates, the probability of simultaneous interference in the vertical and horizontal directions is greatly increased. Less. Further, in FIG. 1 (C), even if interference occurs in the vertical direction, the horizontal direction is arranged at a fixed angle, so that only the reduction in intensity due to the interference in the vertical direction needs to be noted.

No matter what kind of mesh base material is used, the positional relationship as shown in (A) and (B) of FIG.
If it is possible to disperse so that one of the upper and lower arrangements (A) and (B) does not occur in a concentrated manner, there is no portion with extremely low intensity. From this viewpoint, the states shown in FIGS. 1B and 1C are also effective.

〔Example〕

The catalyst according to the present invention can be used as a glass substrate such as E glass, S glass or silica glass, or a net-like base material woven with twisted yarns such as silica-alumina-based ceramic fibers, or by increasing the strength and rigidity to apply the catalyst. For the purpose of facilitating the use of two upper and lower rigid bodies impregnated with inorganic fine particles such as silica and titania and / or an organic binder such as polyvinyl alcohol, the main component of which is titanium oxide which is a known adjusting method. A paste obtained by adding water to the resulting catalyst powder is applied by a method shown in FIG. 4 using a pressure roller. The obtained catalyst body is calcined at 400 to 600 ° C. after drying. Table 2 shows the compositions of the various glasses.

The substrate used here needs to be geometrically deformed or anisotropic in the upper and lower parts, and a combination as shown in FIG. 1 is used. FIG. 1 (A) shows that the upper and lower weave pitches are changed to change the aperture ratio, and FIG. 1 (B) shows that the weave is rectangular and the direction is perpendicular to the top and bottom. Things. FIG. 1 (C) shows an example in which a base material woven so that the weft is inclined with respect to the warp of the woven fabric is used by changing the vertical direction. These woven fabrics can usually be obtained by twisting 1,000 to 2,000 single fibers of about 9 μm in a plain weave with a pitch of about 1 mm to 3 mm. Further, the obtained woven fabric can be treated with an acid to impart acid resistance or heat resistance, or can be pretreated by heating.

The application of the catalyst component to the substrate is performed using a roller with a water content of 20 to
A method of applying a paste-like substance of about 30% is suitable for obtaining a high-density catalyst with less occurrence of cracks and obtaining a high-density catalyst.

In the case of FIG. 1 (A), the yarn pitches in the upper, lower, vertical and horizontal directions are different, and the occurrence of defects due to interference in both directions is prevented. In this case, the upper and lower pitches are preferably selected in the range of 1: 1.1 to 1: 2, and particularly preferably in the vicinity of 1: 1.3.

In FIG. 1 (B), the upper and lower textures are rectangular, and the longitudinal directions thereof are different from each other in the vertical direction, so that the interference of the upper and lower textures is greatly reduced. In addition, in the case of FIG. 1A, there is a problem that the rigidity with respect to the bending in the vertical direction is slightly different due to the difference in the aperture ratio between the upper and lower cloths. can get. In this case, when the long side and the short side of the weaving yarn pitch are close to 2: 1, the connection between the upper and lower pastes becomes good, and good results are obtained.

FIG. 1 (C) shows an example in which weft yarns are woven at a certain angle with respect to the warp yarns, and the weft yarns are turned upside down so that the directions are not aligned. This configuration can use a single base material and is suitable for mass production. In addition, FIG.
It also has the advantage of being stronger in the oblique direction than in the direction (B). Hereinafter, the present invention will be described in detail using specific examples.

Catalyst A 0.29 kg of ammonium metavanadate (NH ₄ VO ₃ ) and 0.72 kg of ammonium molybdate (3 (NH ₄ ) ₂ O.7MoO ₃ .4H ₂ O) were added to 20 kg of a metatitanate slurry (TiO ₂ content 30%). In addition, knead while evaporating water with a heating kneader,
A 40% paste was obtained. This paste was extruded and granulated into a column having a diameter of about 3 mmφ, dried at 150 ° C. using a fluidized bed drier, and further baked in air at 550 ° C. for 2 hours. The obtained granules were pulverized with a hammer mill to an average particle size of about 1 μm to obtain a catalyst powder. 1.3 kg of SiO ₂ / Al ₂ O ₃ fiber is added to 5 kg of this powder,
While gradually adding water, knead the mixture until it becomes clay-like.
A catalyst paste of 27% was obtained.

Meanwhile, E glass 9μmφ long fiber yarn was 1400 present縒合10 / inch pitch, and the plain weave substrates were at a pitch of 12 / _{inch, SiO 2 10wt%, TiO 2} 50wt%,
130 after impregnating with 2wt% polyvinyl alcohol slurry
Dry at 30 ° C. for 30 minutes. The obtained reticulated base material was placed in 5 wt% hydrochloric acid for 6 hours.
After impregnation at 0 ° C. for 2 hours, the resultant was washed with water for 30 minutes and further dried at 130 ° C. to obtain a catalyst substrate.

Of the obtained base materials, those having a pitch of 10 / inch are arranged on the upper side, and those having a pitch of 12 / inch are arranged on the lower side. A plate-shaped catalyst body having a thickness of 1.2 mm was obtained. The formed body was air-dried and then calcined at 550 ° C. for 2 hours with ventilation to obtain a catalyst.

Catalysts B and C The opening shape of the base material of the catalyst A was 10 lines / inch-12 lines /
Inch, lower side 12 / inch-10 / inch rectangle, and the first and second are arranged so that the angle between warp and weft is 120 ° and 60 ° at a pitch of 10 lines / inch both up and down. A catalyst was prepared in the same manner except that the one having the shape shown in FIG.

Comparative Example A catalyst was prepared in the same manner using a substrate having a pitch of 12 / inch instead of the substrate of the catalyst A.

Cut the above catalyst 20mm in width and 50mm in length, 10 pieces each,
Tensile and flexural strengths were measured and average strength and maximum and minimum strengths were determined. Table 1 shows the results.

The catalyst according to the present invention has a high average strength, a small difference between the maximum and minimum strengths, and a small variation.

〔The invention's effect〕

According to the present invention, a plate catalyst excellent in tensile and bending strength can be obtained, and a large catalyst such as an exhaust gas denitration catalyst can be formed. In addition, since there is little variation due to the interference of the base material and high strength can be obtained, high-speed coating can be performed using a roller, and productivity can be significantly improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 (A to C) is an embodiment view showing a combination of substrates used for a catalyst according to the present invention, and FIGS. FIG. 3 is a distribution diagram showing how the state of FIG. 2 appears, FIG. 4 is a diagram showing a conventional method for producing a catalyst, and FIGS. It is a figure explaining relation of upper and lower base materials which lowers catalyst strength. DESCRIPTION OF SYMBOLS 1 ... Upper net-like base material, 2 ... Lower net-like base material, 3 ... Catalyst component, 4 ... Water absorbing paper, 5 ... Application roller, 6 ... Plate catalyst, 8 ... Catalyst communicating part.

────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-1-189314 (JP, A) JP-A-3-94839 (JP, A) JP-A-3-96527 (JP, U) (58) Survey Field (Int.Cl. ⁷ , DB name) B01J 21/00-37/36 B01D 39 / 00,53 / 86

Claims (5)

(57) [Claims] 1. An inorganic fiber plate-like catalyst comprising at least two upper and lower reticulated bases made of inorganic fiber which are overlapped with each other and a space between the reticulated bases with a catalyst component. An inorganic fiber plate-shaped catalyst characterized by having different pitches from each other. 2. The method of claim 1, wherein the ratio of the pitch of the meshes of the upper and lower net-like substrates is 1: 1.
The inorganic fiber slab catalyst according to claim 1, wherein the ratio is in the range of 1 to 1: 2. 3. An inorganic fiber plate-like catalyst comprising at least two upper and lower reticulated bases made of inorganic fibers which are overlapped with each other and a space between the reticulated bases with a catalyst component. An inorganic fiber plate-shaped catalyst having a rectangular shape and being arranged such that the longitudinal directions of the meshes of the upper and lower net-like substrates are perpendicular to each other. 4. The inorganic fiber plate catalyst according to claim 3, wherein the dimension ratio between the long side and the short side of the mesh of the inorganic fiber network substrate is about 2: 1. 5. An inorganic fiber plate-like catalyst comprising at least two upper and lower webs made of inorganic fiber which are overlapped with each other and a space between said meshes of the network, and a catalyst component. An inorganic fiber plate-shaped catalyst, wherein warp yarns and weft yarns of fibers are obliquely arranged and the directions of both yarns are opposite to each other between upper and lower mesh base materials.