JP2008136968A - Method of manufacturing plate-like nox removal catalyst as well as metal substrate for catalyst - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an economical method in which a water-shedding film having a high heat resistance can be supported continuously in a small amount and effectively on a metal substrate. <P>SOLUTION: In the metal substrate-manufacturing method of metal lath processing a strip of metal substrate by using a cutting oil, a silicone resin is used by blending together with the cutting oil, and a heat defatting is carried out after the metal lath processing. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a catalyst metal substrate and a method for producing a plate-shaped denitration catalyst, and more particularly to a planar metal substrate such as a metal wire net or metal lath, and a method for producing a denitration catalyst for ammonia catalytic reduction using the same.

NOx in flue gas emitted from power plants, various factories, automobiles, etc. is a causative substance of photochemical smog and acid rain. As an effective removal method, selective use of ammonia (NH ₃ ) as a reducing agent The flue gas denitration method by catalytic reduction is widely used mainly in thermal power plants. As the catalyst, a titanium oxide (TiO ₂ ) -based catalyst containing vanadium (V), molybdenum (Mo) or tungsten (W) as an active component is used. In particular, vanadium which is one of the active components is active. The current denitration catalyst is mainly used because it is not only high but also has little deterioration due to impurities contained in the exhaust gas and can be used at a lower temperature (Patent Document 1). These titanium oxide-based denitration catalysts are often used by applying a catalyst component to a honeycomb or metal substrate. In particular, the latter plate-shaped catalyst is resistant to abrasion and accumulation due to soot, so denitration of oil and coal combustion exhaust gas. Widely used in

  A number of methods for producing a plate catalyst have been proposed, but a metal mesh-like metal lath base material obtained by placing slits (slits) with a predetermined pitch in a thin metal plate and applying a tensile force in a direction perpendicular to the slit Since a catalyst with excellent mass productivity and strong mechanical strength can be obtained, it has become the mainstream of plate catalysts in Japan and overseas.

On the other hand, in the United States, there is an increasing trend in boilers using coal types containing S, such as subbituminous coal (PRB coal) and bituminous coal. When the V-containing catalyst is used for such exhaust gas treatment, sulfur dioxide (SO ₂ ) in the exhaust gas is oxidized by the catalytic action of V to produce sulfur trioxide (SO ₃ ). (1) Causes corrosion, (2) reacts with leaked NH ₃ to produce ammonium sulfate, and clogs the downstream air heater. Therefore, there is a demand for a denitration catalyst having high denitration activity and a reduced oxidation rate of SO ₂ to SO ₃ . On the other hand, a method of reducing the SO ₂ oxidation activity by optimizing the catalyst composition such as the V content has been adopted. However, the method using the metal substrate has a problem in that the SO ₂ oxidation rate increases due to the catalytic action of the substrate metal element slightly dissolved during the production of the catalyst.

On the other hand, titanium oxide based on a sulfuric acid method is used as a titanium oxide-based denitration catalyst, which is inexpensive and provides high catalyst performance. In general, titanium oxide by the sulfuric acid method contains several weight percent of sulfate radicals, and most of them remain in the catalyst component even after steps such as addition and firing of the catalyst component. For this reason, in the case of a catalyst using a catalyst substrate, if a paste or slurry of the catalyst component is coated or applied to the substrate by a wet method, the metal substrate is dissolved by the residual sulfuric acid, and the substrate component moves into the catalyst component. This causes a problem. Among the suspension substrate components, elements such as iron (Fe), nickel (Ni), and chromium (Cr), when adsorbed on titanium oxide, can promote oxidation of SO ₂ more than V, which is a denitration catalyst component. It is known that a small amount of transition metal component dissolved during the catalyst production process hinders the reduction of the SO ₂ oxidation rate. As a method for preventing such corrosion of the metal substrate, for the purpose of preventing contact between the metal substrate and the catalyst component, a method of forming an inactivated film on the surface of the metal substrate, for example, a method of spraying metal aluminum (Patent Document 2). ), And a method for forming a film mainly composed of titanium oxide (Patent Document 3) has been proposed.

Another effective method is to form a thin silicone film on the surface of the metal substrate. Since the silicone film has water repellency, the residual sulfuric acid in the catalyst component can be prevented from coming into contact with the substrate, and since it has high heat resistance, it is excellent as a catalyst for exhaust gas treatment used at a high temperature of 300 ° C. or higher. On the other hand, various methods for forming a thin film on the surface of a substrate such as glass, paper, and resin are not limited to metal substrates, and various methods have been developed for each application (Non-Patent Document 1), such as a roll coater, a dip coater, and a spin coater. A method using a coating machine is generally used. However, in order to form a film on the catalyst substrate surface by this method, there are problems such as (1) an expensive coating machine is required, (2) an organic solvent is required, and (3) the amount of adhesion is large. . In particular, there is a problem that a large amount of silicone adhesion is not preferable because it adversely affects catalyst performance.
JP 50-128681 JP 52-14658 A Japanese Patent Laid-Open No. 06-246176 Complete collection of (ultra) precision coating and coating techniques, by the Technical Information Association

  An object of the present invention is to provide an economical method capable of supporting a water repellent film having high heat resistance on a metal substrate in a small amount and efficiently.

The above-mentioned subject is achieved by the following method.
(1) In the manufacturing method of the metal substrate which metal-lasers-processes a strip | belt-shaped metal base material using cutting oil, it mixes and uses a silicone resin with the said cutting oil, and heat degreasing | defatting is performed after metal lath processing. Manufacturing method.
(2) In a method of manufacturing a metal substrate in which a metal substrate is processed with a metal oil using a cutting oil, a metal substrate is processed with a metal oil using a cutting oil, then contacted with a silicone resin, and then heated and degreased. A metal substrate manufacturing method characterized by the above.
(3) The method according to (1) or (2), wherein a mixing ratio of the silicone resin to the cutting oil is in a range of 1: 0.2 to 1: 2 on a weight basis.
(4) A metal substrate obtained by the method according to any one of (1) to (3), titanium oxide, and an oxide of one or more elements selected from tungsten, molybdenum, and vanadium A method for producing a plate-shaped denitration catalyst comprising adhering a denitration catalyst component containing
(5) A denitration catalyst component comprising titanium oxide and an oxide of one or more elements selected from tungsten, molybdenum and vanadium is supported on the surface of the metal substrate on which the silicone resin film is formed. A denitration catalyst produced by (4).

  ADVANTAGE OF THE INVENTION According to this invention, the corrosion of the board | substrate in the denitration catalyst which uses a metal substrate for a support | carrier can be prevented, and the performance fall resulting from it, especially the raise of an oxidation rate can be prevented. In addition, according to the present invention, the corrosion of the substrate can be prevented with simple equipment or with conventional equipment, so that the cost reduction effect is also increased.

The term “silicone resin” as used in the present invention means dimethylsilicone oil in which a polymer organic compound (polymer) having a siloxane bond as a skeleton is substituted with a phenyl group for a part of methyl groups. The type of the silicone resin is not particularly limited, but a viscosity having a low to medium viscosity is easy to handle, and a kinematic viscosity at 25 ° C. is 100 mm ² / s or less, preferably 50 mm ² / s or less. When the viscosity exceeds 100 mm ² / s, there are problems in handling such as difficulty in draining when continuously supported on the metal lath surface. The cutting oil is not particularly limited as long as it is a lubricating oil generally used for cutting. The mixing ratio of the cutting oil and the silicone resin gives a good result when the weight ratio of the silicone resin to the cutting oil is in the range of 1: 0.1 to 1: 2, preferably 1: 0.5 to 1: 1. When the weight ratio of the silicone resin is less than 0.1, it is difficult to form a coating layer, and when it exceeds 2, the metal lath (cutting) process becomes difficult. Moreover, when there exists a possibility that the lifetime of a blade may be shortened by mixing a silicone resin, you may process using cutting oil and a silicone resin separately.

  After adhering cutting oil and silicone resin to the metal substrate, heat degreasing is performed at a decomposition temperature (250 ° C.) or higher of the silicone resin. Below this temperature, a silicon oxide film is not formed on the metal lath surface, which is not preferable. Further, considering the deterioration of the film and the deterioration of the substrate, 600 ° C. or lower is preferable. The heating time is appropriately selected in relation to the time during which the metal lath substrate is in the furnace. Also, a furnace for degreasing the cutting oil and a furnace for insolubilizing the silicone resin may be provided separately.

  In order to support the catalyst component on the metal substrate obtained by the above method, it is generally selected from titanium oxide, tungsten (W), molybdenum (Mo) and vanadium (V). A coating method of embedding a paste of a denitration catalyst composed of an oxide of one or more elements into a metal lath network as a base material or a method of coating these slurries is suitable, but the present invention is not limited thereto. Not too long.

Hereinafter, the present invention will be specifically described with reference to the drawings.
FIG. 1 is a production flow diagram of a catalyst provided with the minimum equipment necessary for carrying out the present invention. In FIG. 1, a metal strip 1 wound on a roll is slit by a metal lath processing machine 2 at a right angle to the longitudinal direction of the strip, and simultaneously stretched in the longitudinal direction to be processed into a so-called metal lath. In the figure, reference numeral 20 denotes a drive roller. At this time, in this invention, the liquid mixture 3 of cutting oil and silicone resin is used for the cutting oil used at the time of metal lath processing. The base material that has been subjected to metal lath cutting is drained with a blow 4 and then guided to a heating and degreasing furnace 5 where silicone is insolubilized simultaneously with the removal of the cutting oil. Thus, it becomes unnecessary to use a new silicone coating apparatus by mixing the silicone resin with the cutting oil. Further, in the conventional method, in order to carry the silicone resin thinly and uniformly on the substrate surface, an organic solvent is mixed in order to adjust the concentration and viscosity of the silicone resin. Since it plays the same role as an organic solvent, a thin and uniform silicone resin can be formed on the substrate surface without using an organic solvent. Further, at the time of oil draining or heat degreasing performed for removing the cutting oil after metal lath processing, the silicone resin can be drained and insolubilized by heating, so that there is an advantage that it is not necessary to use new equipment.

  Next, FIG. 2 is a flowchart showing an embodiment in which a silicone resin coating is performed after the metal lath processing of the substrate. In FIG. 2, the metal strip 1 is processed into a metal lath together with the cutting oil supplied from the cutting oil tank 16 by the metal lath processing machine 2, but only the cutting oil is used during the metal lath processing. Thereafter, the metal lath processed substrate is sent to the silicone resin coating apparatus 6. The silicone resin coating device 6 is provided with a silicone resin tank 7 through which the metal lath substrate passes. Then, after draining with the blow 4, it guide | induces to the heating degreasing furnace 5, and insolubilization of silicone is performed simultaneously with the removal of cutting oil. At this time, a certain amount of cutting oil adhering to the metal lath is always brought into the silicone resin tank 7, and a certain amount is always adhering to the metal lath and taken out, so the amount of cutting oil and the silicone resin in the tank 7 is always balanced. Has been. Therefore, only the silicone resin may be supplied into the tank 7 from the silicone oil supply tank 17. In this case, in order to make the liquid amount in the layer constant, a level meter 8 may be installed and a means for monitoring the liquid amount in the layer may be provided. Thus, also in this embodiment, a special organic solvent is not required, and the heating and degreasing furnace can also be used for insolubilization of the silicone resin.

FIG. 3 is a flowchart showing an embodiment in which the step of supporting the denitration catalyst is combined after the metal lath processing and the film formation step of FIG. Catalyst paste 10 obtained by adding and kneading water and inorganic fibers to a catalyst component composed of TiO ₂ and one or more oxides of W, Mo, and V prepared separately in the metal lath that has undergone the treatment process of FIG. The belt-like plate-shaped catalyst is obtained by pressure-bonding with a coating roller 11 so as to fill the eyes of the metal lath. The obtained band-shaped plate-shaped catalyst is further formed into a corrugated shape, a notch-shaped chevron, etc., to be used as a spacer by the hydraulic press 12, and then cut into a length of 300 to 1000 mm by the cutting machine 13 to form the catalyst element 14. The catalyst element 14 obtained in this way is air-dried and then stacked, or stacked and stored in the unit 15 as shown in FIG. 4, and calcined at 400 to 600 ° C.

Hereinafter, the present invention will be described in detail using specific examples.
Example 1
Using a liquid in which cutting oil (BA-905-2, manufactured by Nippon Tool Oil Co., Ltd.) and silicone resin (KF96-5, manufactured by Shin-Etsu Chemical Co., Ltd.) are mixed at a weight ratio of 1: 1, the apparatus shown in FIG. A stainless steel plate (SUS430, thickness 0.16 mm, width 500 mm) was subjected to metal lath processing, and a silicone resin was adhered. After draining, heat treatment was performed at 500 ° C. for 40 seconds in an insolubilization furnace to obtain a metal lath substrate of the present invention in which a film was formed on the surface of the metal lath. The weight increase at this time was 0.4 g / m ² .

Examples 2 and 3
A metal lath substrate was obtained in the same manner as in Example 1 except that the mixing ratio of the cutting oil and the silicone resin was changed to 1: 0.5 and 1: 2. The respective weight gains were 0.2 g / m ² and 0.7 g / m ² .

Comparative Example 1
In Example 1, a metal lath substrate was obtained in the same manner as in Example 1 except that the silicone resin was not mixed with the cutting oil.

Examples 4 and 5
Titanium oxide, ammonium tungstate, and ammonium metavanadate obtained by the sulfuric acid method were mixed in a raw material mixed at a Ti / W / V atomic ratio of 91/5 / 4atom%, and water and sulfuric acid were added and kneaded. After kneading, a silica alumina inorganic fiber was added to prepare a paste. At this time, the SO ₄ concentration in the dry paste was about 4% by weight.

  This catalyst paste was applied to each metal lath substrate obtained in Examples 1 to 3 with a roller type coater to obtain a plate-like catalyst. The obtained catalyst was molded into a mountain shape, air-dried in the atmosphere for 12 hours, and calcined at 500 ° C. for 2 hours.

Comparative Example 2
A catalyst was obtained in the same manner as in Example 4 except that the metal lath substrate of Comparative Example 1 was used.

Test example 1
A sample piece of 100 mm × 100 mm was cut out from the metal lath substrate obtained in Examples 1 to 3 and Comparative Example 1, and baked at 500 ° C. for 2 hours. Thereafter, each of the obtained sample pieces was immersed in water for 10 seconds and then left to stand for 24 hours in an atmosphere of 100% relative humidity at 30 ° C. (hereinafter, this operation is simply referred to as “moisture absorption treatment”). Thereafter, when the appearance of the sample pieces was observed, the appearance of the metal lath sample pieces of Examples 4 to 6 was not changed before and after the test, but rust was observed on the surface of the metal lath sample piece of Comparative Example 1 in some places. From this, it was found that the metal lath substrate treated according to the present invention has a high anticorrosion effect without generating rust even after the moisture absorption treatment.

Test example 2
Sample pieces of 100 × 100 mm were cut out from the catalysts obtained in Examples 4 and 5 and Comparative Example 2, and moisture absorption treatment was performed in the same manner as in Test Example 1. The catalyst was peeled off from the test piece before and after the moisture absorption treatment and pulverized in a mortar, and the SO ₄ amount and Fe ₂ O ₃ amount in the obtained powder were measured using a fluorescent X-ray measurement apparatus.

Table 1 shows the results of comparing the amounts of SO ₄ and Fe ₂ O _{3 in} the catalysts before and after the tests in the catalysts of Examples 4 and 5 and Comparative Example 2. It can be seen that the SO ₄ amount is almost equal between the example and the comparative example. On the other hand, in Examples 4 and 5, although the amount of Fe ₂ O ₃ in the catalyst almost no difference before and after the test, that in Comparative Example 2, are Fe ₂ O ₃ in the catalyst after the test has increased significantly I understand. From this, it can be seen that in the catalyst of Comparative Example 2, Fe moves from the base material into the catalyst by the moisture absorption treatment. From the above results, it was found that any of the catalysts of Examples could prevent the metal lath and the catalyst from contacting each other by the coating and prevent the movement of Fe from the metal lath.

Table 3 shows the results of measuring the SO ₂ oxidation rate before and after the moisture absorption test using the flow reactor in the conditions of Table 2 for the catalysts of Example 1 and Comparative Example 2. In the catalyst of Example 1, there is no change in the oxidation rate before and after the moisture absorption test, but in the catalyst of Comparative Example 2, the SO ₂ oxidation rate is high after the moisture absorption test. From this, it was found that, in the method of the present invention, the contact between the metal lath and the catalyst could be prevented, so that the increase in the SO ₂ oxidation rate due to the movement of Fe was prevented.

The manufacturing flow figure of the catalyst which arranged the minimum equipment required for implementing this invention. The flowchart which shows the Example which performs silicone resin coating after the metal lath processing of a board | substrate. The flowchart which shows the Example which combined the process which carry | supports a denitration catalyst after the metal lath processing and film formation process of FIG. The figure which shows the catalyst unit which accommodated the corrugated catalyst which becomes this invention in the frame.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Suspension strip 2 Metal lath processing machine 3 Cutting oil and silicone resin mixed liquid 4 Blow for oil removal 5 Heating degreasing furnace 6 Silicone resin coating apparatus 7 Silicone resin tank 8 Liquid level meter 10 Catalyst paste 11 Coating roller 12 Hydraulic press 13 Cutting Machine 14 Catalyst element 15 Catalyst unit 16 Cutting oil tank 17 Silicone oil tank 20 Drive roller

Claims (5)

A method for producing a metal substrate, wherein a metal substrate is processed with a cutting oil using a metal lath, and a silicone resin is mixed with the cutting oil and heat degreasing is performed after the metal lath processing. . In a metal substrate manufacturing method for metal lath processing of a band-shaped metal base material using cutting oil, the metal base material is metal lath processed using cutting oil, then contacted with a silicone resin, and then heated and degreased. A method for manufacturing a metal substrate. The method according to claim 1 or 2, wherein a mixing ratio of the silicone resin to the cutting oil is in a range of 1: 0.2 to 1: 2 on a weight basis. A denitration catalyst component comprising titanium oxide and an oxide of one or more elements selected from tungsten, molybdenum and vanadium on the metal substrate obtained by the method according to any one of claims 1 to 3. A method for producing a plate-shaped denitration catalyst, wherein 5. A denitration catalyst component comprising titanium oxide and an oxide of one or more elements selected from tungsten, molybdenum and vanadium is supported on the surface of the metal substrate on which the silicone resin film is formed. A denitration catalyst manufactured by

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