JPH08196914A - Plate-shaped catalyst and its manufacture - Google Patents

Abstract

PURPOSE: To increase the strength of resistance to release by improving the fluidity of a catalyst paste at the time of manufacturing a plate-shaped catalyst. CONSTITUTION: Ammonium molybdate and vanadyl sulfate are blended with titanium oxide (average diameter of 1.5μm and with given particle diameter distribution) of a catalyst composition component, to which alumina silica fiber of average diameter of 2.5μm and average length of 250mm are added twice, and the fiber diameter of the alumina silica fiber added first is made to fine pieces to be in the range of equal to ten times or less to the average particle diameter of a catalyst component and also the fiber length of 100 times or less of the average particle diameter. Then alumina silica fiber of the same quantity as first is added and kneaded to prepare a catalyst paste and a catalyst is manufactured through a coating process. The apparent particle diameter distribution of the catalyst component is widened by the arrangement to improve the fluidity of the paste and the catalyst of high strength of resistance to release is manufactured by being mixed with reinforcing fiber added thereafter.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flue gas denitration catalyst, and more particularly to a plate-shaped catalyst in which a catalyst composition is supported on a metal substrate, especially a metal lath, and a method for producing the same.

[0002]

2. Description of the Related Art As a method for removing nitrogen oxides in exhaust gas, a method in which a catalyst is selectively reduced with ammonia is the mainstream, and these denitration catalysts are generally titanium oxide (TiO ₂ ) There is used a catalyst obtained by molding a catalyst composition comprising an oxide of molybdenum (Mo), vanadium (V), tungsten (W), etc. into a granular shape, a plate shape, a honeycomb shape or the like. Among them, the plate catalyst is a combination of catalyst plates parallel to the gas flow, has less pressure loss and less accumulation of dust, etc. than other types, and it is easy to stack other catalyst elements. Is excellent at.

FIG. 6 is a plan view showing the structure of a general metal lath substrate.

It is common to use a substrate as a plate catalyst for holding a catalyst component and maintaining its shape. A metal lath substrate 1 formed by metal lath processing a metal thin plate as shown in this figure, a wire mesh, and an inorganic fiber are used. Various base materials such as woven cloth are used. As a known example of this metal lath substrate, Japanese Patent Application No. 63-3
There is a publication of 0591.

These catalysts are generally pastes prepared by kneading and adding water and inorganic reinforcing fibers to the catalyst components (hereinafter,
A catalyst paste) is supported on a base material, molded into various shapes, and dried and fired to produce the film.

FIG. 7 is an explanatory view showing a method for producing a plate catalyst using a general metal lath substrate.

In the conventional catalyst supporting method of the catalyst using the metal lath base material 1, the metal lath base material 1 and the catalyst paste 2 are simultaneously inserted into the rolling roll 3 as shown in FIG. The paste 2 is applied by the application sheet 4 (referred to as an application process). The fibers added to the catalyst paste 2 improve the strength of the portion made of the catalyst component so that the catalyst component does not easily fall off from the metal lath base material 1 and suppress the shrinkage when drying from the paste state to suppress the metal lath. The adhesion to the substrate 1 is not impaired, the pore volume of the catalyst component is increased, and the peel resistance of the catalyst and the denitration performance are improved.

[0008]

However, the addition of fibers to the catalyst component in the above-mentioned conventional techniques may impair the fluidity of the catalyst paste and hinder the application. Specifically, a portion where the catalyst component is not supported is generated, or water is separated from the catalyst paste to make the catalyst support non-uniform. The cause is that the flowability of the paste due to only the catalyst component is originally poor, therefore the dispersion of the fibers is poor, and the addition of fibers with poor dispersion causes the entangled parts of the fibers to deteriorate the deformability of the paste. Doing so, discharging the excess water contained in the entangled portion of the fibers at the pressure at the time of application, and increasing the pressure at the time of application due to poor fluidity. The poor fluidity of the paste composed of the catalyst component is due largely to the particle size of the raw material powder, and the particle size of the main raw material titanium oxide that is usually used for the denitration catalyst is 1
If it is on the order of 0 to ¹ to 10 ¹ μm, when the particle size distribution is narrow, a dilatant property appears in the paste and the fluidity is poor.

FIG. 8 is a particle size distribution chart when the particle size distribution of general catalyst component particles is narrow.

The dilatant paste has a poor particle filling state, and when a fibrous material having a poorer dispersion than particles is added to such a paste and kneaded, the fluidity is extremely deteriorated under a sudden load. However, it does flow for moderate loads. By adding fibers to this paste, the dispersion of the fibers becomes poor, and the fibers that are more difficult to flow than the particles become entangled without being able to disperse. Often contains excess water. In the paste in such a state, when a large pressure is applied, for example, in a coating process, the fiber acts like a filter in the paste, water in the paste is squeezed out and moves into the fiber, and the paste is easily formed. Drains water from it. As a result, the fluidity between the particles is further deteriorated, and when the catalyst paste is finally applied to the base material, the above-mentioned phenomenon is caused and the catalyst component is easily dropped from the base material.

FIG. 9 is a particle size distribution chart in the case where the particle size distribution of general catalyst component particles is wide.

As a general method for improving the dilatant property of the paste, if powders having different particle sizes are added to adjust the particle size to widen the particle size distribution, the packed state of the particles will be good and the fluidity of the paste will be improved. Improves the quality, disperses the fibers well, reduces excess water, and consequently improves coatability, but this method complicates the process because it is necessary to prepare a powder that matches the particle size distribution of the catalyst raw material. There's a problem. Also, as a well-dispersed fiber, if a fiber having a short fiber length and no bundling or entanglement is added, the dispersion of the fiber is improved, but the function as a reinforcing fiber is reduced, and the loss of the catalyst component becomes relatively large. There is.

An object of the present invention is to improve the fluidity of the catalyst paste and increase the peel resistance during the production of the plate catalyst.

[0014]

Means for Solving the Problems The above object is to provide a plate-shaped catalyst having a base material obtained by processing a metal thin plate into a metal lath, and a catalyst component pressure-bonded to the lath surface of the base material and the through holes that are through holes. This is achieved by including two types of fiber groups having different lengths in the catalyst component.

The above-mentioned object is a plate-shaped catalyst having a base material obtained by processing a metal thin plate into a metal lath, and a catalyst component pressure-bonded to the lath surface of the base material and the lath which is a through hole, and the fiber diameter of the catalyst component is It is achieved by including a fiber group having a fiber length of 1 to 10 times the average particle size and a fiber length of 100 times or less the average particle size of the catalyst component.

[0016] The above object is a method for producing a plate-shaped catalyst in which a catalyst component and fibers are kneaded and pressure-bonded to the lath surface of a base material obtained by processing a metal thin plate into metal laths and the laths that are through holes, and the catalyst component and the fibers are Is added to make the fibers finer, and then the rest of the fibers are added and kneaded.

The above-mentioned object is a method for producing a plate-shaped catalyst in which a catalyst composition and fibers are kneaded and pressure-bonded to the lath surface of a base material obtained by processing a metal thin plate into a metal lath and the lath which is a through hole,
The catalyst component and a part of the fiber are added so that the fiber diameter is 1 to 10 times the average particle diameter of the catalyst component and the fiber length is 100 times or less the average particle diameter of the catalyst component. This is achieved by adding the rest of the fibers and kneading after the formation.

[0018]

[Function] By first refining the added fibers, the apparent particle size distribution of the catalyst component particles can be widened, the packing condition of the particles can be improved, and the paste fluidity can be improved and excess water can be reduced. To

Also, by adding more fiber, the fiber reinforcement provides a higher strength than if the fiber was added at one time combined with the effect of the fiber initially added.

[0020]

EXAMPLES Examples of the present invention will be described in detail below.

As a base material of the plate-shaped catalyst, a metal plate made of SUS430 and having a thickness of 0.2 mm is carved with a width of 0.6 mm, and a lath size shown in FIG. 6 is about 4.50 mm (Lw) and about 2.05 mm.
(Sw), a metal lath having a thickness of about 0.8 mm was used. Next, a specific manufacturing method will be described.

Embodiment 1 FIG. 1 is a flow chart for explaining the manufacturing process of an embodiment of the present invention.

As shown in the figure, titanium oxide (a raw material having an average particle size of 1.5 μm and a particle size distribution shown in FIG. 8) is used as the catalyst composition components, and ammonium monate molybdate and vanadyl sulfate are added.
Alumina-silica fibers (commercial name Kaowool) with an average diameter of 2.5 μm and an average length of 250 mm, which were compounded so that the atomic ratio of Ti / Mo / V = 90.5 / 5 / 4.5.
Is added in two separate steps, and the first alumina-silica fiber has a fiber diameter of 1 to 10 times the average particle diameter of the catalyst component and a fiber length of 100 times or less the average particle diameter of the catalyst component. The catalyst paste was made finer, and then the same amount of alumina-silica fiber as the first was added and kneaded to prepare a catalyst paste, and the catalyst was manufactured through the coating process of FIG. 7. It should be noted that the shape of the alumina-silica fiber added the second time hardly changes due to the kneading and has a function as a reinforcing fiber.

FIG. 2 is a chart for explaining the relationship between the average particle diameter of the catalyst component and the length of each fiber group in the example of the present invention.

As shown in the figure, there are two kinds of fiber groups having different fiber lengths in the catalyst paste, the fiber group 1 is the alumina silica fiber added first, and the fiber group 2 is the alumina silica added later. It is a fiber.

Example 2 The same conditions as in Example 1 were used except that the properties of the fibers added in two steps were different. First, the alumina-silica fibers of Example 1 were added to obtain the average particle size of the catalyst component. On the other hand, the fiber diameter is 1 to 10 times and the average fiber length is 1 of the average particle diameter of the catalyst component.
Finer to 100 times or less, then fiber diameter 10 μm
An E glass fiber having a length of 30 mm was added and kneaded in the same weight as the first to prepare a catalyst paste, and the catalyst was manufactured through the coating process of FIG. The shape of the E glass fiber added the second time hardly changed by kneading and has a function as a reinforcing fiber.

Comparative Example 1 FIG. 3 is a flow chart for explaining a catalyst manufacturing process of a comparative example.

As the catalyst component, a raw material titanium oxide having the same particle size distribution as in Example 1 and titanium oxide for particle size adjustment (a raw material having an average particle size of 0.5 μm and a particle size distribution shown in FIG. 9) were used. 8: 2, ammonium molybdate and vanadyl sulfate were mixed so as to have an atomic ratio of Ti / Mo / V = 90.5 / 5 / 4.5, and after kneading, the total amount of alumina-silica fiber of Example 1 Was added and kneaded to prepare a catalyst paste, and the catalyst was manufactured through the coating process of FIG.

Comparative Example 2 FIG. 4 is a flow chart for explaining the catalyst manufacturing process of the comparative example.

As shown in the figure, the catalyst composition components were titanium oxide (a raw material having an average particle size of 1.5 μm and a particle size distribution shown in FIG. 8), ammonium ammonium molybdate and vanadyl sulfate.
Ti / Mo / V = 90.5 / 5 / 4.5 was blended so as to have an atomic ratio, and the average diameter of Example 1 was 2.5 μ.
m, and the total amount of alumina-silica fibers having an average length of 250 mm were added and kneaded to prepare a catalyst paste, and the catalyst was manufactured through the coating process of FIG.

Comparative Example 3 FIG. 5 is a flow chart for explaining the catalyst manufacturing process of the comparative example.

As shown in the figure, titanium oxide (a raw material having an average particle size of 1.5 μm and a particle size distribution shown in FIG. 8) was used as the catalyst composition components, and ammonium monate molybdate and vanadyl sulfate were used.
Atomic ratio of Ti / Mo / V = 90.5 / 5 / 4.5 was mixed and kneaded, and the kneaded product was alumina silica of Example 1 having an average diameter of 2.5 μm and an average length of 250 mm. A catalyst paste was prepared by kneading the entire amount of the fibers, and the catalyst was manufactured through the coating process of FIG. 7.

Regarding the five kinds of catalysts of Examples 1 and 2 and Comparative Examples 1, 2 and 3, the fluidity of the paste, which is the object of improvement, was evaluated by the coating property in the coating process shown in FIG. Regarding the strength, a test piece with a width of 100 mm and a length of 250 mm cut out from a plate-shaped catalyst was repeatedly dropped 50 times from a height of 1 m so that the flat surface collided with the steel plate, and the amount of separation of the catalyst component at that time It was evaluated by. Table 1 shows the comparison results.

[0034]

[Table 1]

From the above, the fibers added first and cut into short pieces (Examples 1 and 2 and Comparative Example 2) have the same paste flowability as those obtained by adjusting the particle size of the powder (Comparative Example 1). It can be seen that the improvement effect is obvious, and Comparative Example 3 which is not so has poor coatability. Further, it has been shown that the peel resistance is improved by adding the fibers in two times after the particle size is adjusted, as compared with the particle size adjusting method using powder.

As described above, in this embodiment, the reinforcing fibers are used and the same or different fibers are added in two batches when the paste is kneaded. At this time, the fiber added previously has a fiber diameter of 1 to 10 times the average particle diameter of the target powder, and the fiber length during the kneading process is the average particle diameter of the target powder. On the other hand, when the length is shortened to 100 times or less, the apparent particle size distribution of the catalyst component becomes wider. Particle size adjustment with powder is a simple method to mix powder with a particle size larger or smaller than the target powder, but the point that particle size adjustment with fiber differs from powder preparation is that cut fiber Still has a shape longer than the fiber diameter so that it does not completely lose its function as a reinforcing fiber. However, as the fiber length becomes shorter, the original strength improvement, the suppression of drying shrinkage, and the effect of increasing the pore volume due to the addition of the fiber are alleviated. Therefore, when the fiber is added to the paste with improved fluidity after particle size adjustment, the original effect of fiber reinforcement is exerted, and when the fiber is added at one time together with the effect of the fiber added earlier. Higher strength can obtain the catalyst.

[0037]

EFFECTS OF THE INVENTION According to the present invention, in the production of a plate-shaped catalyst, fibers are added in two steps, and the fibers previously added are refined to broaden the apparent particle size distribution of the catalyst component. In addition to improving the fluidity of the paste, a catalyst having a high peeling resistance can be obtained in combination with the reinforcing fiber added later.

[Brief description of drawings]

FIG. 1 is a flow chart illustrating a manufacturing process according to an embodiment of the present invention.

FIG. 2 is a chart for explaining the relationship between the average particle diameter of the catalyst component and the length of each fiber group in the example of the present invention.

FIG. 3 is a flowchart illustrating a catalyst manufacturing process of a comparative example.

FIG. 4 is a flowchart illustrating a catalyst manufacturing process of a comparative example.

FIG. 5 is a flowchart illustrating a catalyst manufacturing process of a comparative example.

FIG. 6 is a plan view showing the structure of a general metal lath substrate.

FIG. 7 is an explanatory view showing a method for producing a plate catalyst using a general metal lath substrate.

FIG. 8 is a particle size distribution chart in the case where the particle size distribution of general catalyst component particles is narrow.

FIG. 9 is a particle size distribution chart in the case where the particle size distribution of general catalyst component particles is wide.

[Explanation of symbols]

 1 Metal lath base material 2 Catalyst paste 3 Rolling roll 4 Coating sheet

Claims (4)

[Claims] 1. A base material obtained by processing a metal thin plate with a metal lath,
A plate-like catalyst having a lath surface of the base material and a catalyst component pressure-bonded to the laths which are through holes, wherein the catalyst component contains two types of fiber groups having different lengths. . 2. A base material obtained by processing a metal thin plate with a metal lath,
In a plate-shaped catalyst having a lath surface of the base material and a catalyst component pressure-bonded to the lath which is a through hole, the fiber diameter is 1 to 10 times the average particle diameter of the catalyst component, and the fiber length is A plate-shaped catalyst comprising a fiber group having an average particle diameter of 100 times or less of a catalyst component. 3. A method for producing a plate-shaped catalyst in which a catalyst component and fibers are kneaded and pressure-bonded to a lath surface of a base material obtained by processing a metal thin plate into a metal lath and laths that are through holes, wherein one of the catalyst component and the fiber is And a kneading method in which the remaining portion of the fiber is added and kneaded. 4. A method for producing a plate-shaped catalyst in which a catalyst component and fibers are kneaded and pressure-bonded to the lath surface of a substrate obtained by processing a metal thin plate into a metal lath and to the laths that are through-holes. Part to make the fiber diameter 1 to 10 times the average particle size of the catalyst component and the fiber length to 100 times or less the average particle size of the catalyst component, and then the remaining part of the fiber. A method for producing a plate-shaped catalyst, which comprises adding and kneading.