JP2001205098A - Catalyst carrier and method for preparing catalyst carrier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a catalyst carrier with excellent corrosion resistance while a metal is used as a constitutional material and a method for preparing the catalyst carrier with excellent corrosion resistance. SOLUTION: This a catalyst carrier comprises a cylindrical base material consisting of a corrugated foil made of a metal and a spacer foil and with a crosssection of a honey-comb structure and a corrosion-resistant layer covering the surface of the above base material, and the corrosion-resistant layer consists of a glass including a crystalline glass. In addition, the catalyst carrier is prepared by a process wherein the corrugated foil made of a metal and the spacer foil are laminated to prepare the cylindrical base material with the crosssection of the honey-comb structure and after the cylindrical base material is immersed into a solution containing the crystalline glass, the cylindrical base material is heated to form the corrosion-resistant layer and in the process for forming the corrosion-resistant layer, a plurality of times of the processing are preferably performed while the amount of sticking of the solution onto the cylindrical base material is restricted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an exhaust gas purifying catalyst,
The present invention relates to a catalyst carrier used for a catalyst such as a deodorizing catalyst and a combustion catalyst, and a method for producing the same. In particular, the present invention relates to a catalyst carrier used for a catalyst used in a reaction system in which an object to be treated contains a corrosive substance.

[0002]

2. Description of the Related Art Catalysts are widely used not only for industrial applications such as petroleum refining and petrochemical production, but also for pollution control such as exhaust gas purification and deodorization and environmental purification. As a form of these catalysts, those in which a catalyst component is supported on a powder carrier or a pellet carrier have been conventionally used. However, in the case of an environmental purification catalyst such as an exhaust gas purification catalyst, in recent years, the pressure is low and the pressure loss is small. BACKGROUND ART Honeycomb catalysts in which a catalyst component is supported on a tubular base material having a honeycomb structure in cross section (generally, often referred to as a honeycomb or a monolith) are widely used.

[0003] Further, there has been a change in the form of the honeycomb used in the honeycomb catalyst, and the application of a metal honeycomb employing a metal as a constituent material from a ceramic honeycomb formed of ceramic such as alumina or cordierite is considered to be promising. ing. This is because the metal is elastic and has excellent toughness, so it is not easily damaged by impact.In addition, since the mechanical strength is high, the wall thickness of each cell can be reduced while ensuring the strength of the carrier. This is because the gas pressure loss can be further reduced. In addition, since the metal has good thermal conductivity, it is possible to shorten the heating time when heating to a predetermined reaction temperature, and it is also a feature of the metal honeycomb that the energy efficiency is good.

Incidentally, in a reaction system to which an environmental purification catalyst is applied, corrosive components are often contained. Further, the catalyst is usually used at a temperature of room temperature or higher,
In some cases, it is used at a considerably high temperature. Therefore, it is considered that the catalyst for environmental purification is often used in a considerably corrosive environment, and when a metal honeycomb is used as a carrier for such a catalyst, problems such as corrosion of the carrier and damage to the catalyst occur. it is conceivable that.

[0005]

As a countermeasure against such a corrosion problem, if a metal honeycomb is applied, it is conceivable to use a metal material having high corrosion resistance, that is, to improve the quality of the material. It is also conceivable to use a conventional ceramic honeycomb instead of a metal honeycomb.

[0006] However, the upgrading of the constituent materials leads to an increase in the price of the support and, in turn, the price of the catalyst, and is not a practically useful measure. Further, although the problem of corrosion of the carrier is solved by using the conventional ceramic honeycomb, it may be difficult to apply the ceramic honeycomb in consideration of the above-mentioned advantages of the metal honeycomb.

Accordingly, an object of the present invention is to provide a catalyst carrier having excellent corrosion resistance and a method for producing a catalyst carrier having excellent corrosion resistance while using metal as a constituent material.

[0008]

Means for Solving the Problems The present inventor has considered that the above problem can be solved by providing an anticorrosion layer on a conventional metal honeycomb. Then, the following conditions were required for the anticorrosion layer, and intensive studies were made. That is,
It must be inert to corrosive gases and have an excellent anticorrosion effect. In addition, it is necessary that a relatively small amount of adhesion, that is, a relatively thin coating has an anticorrosive effect. This is because the metal honeycomb has the advantage that the wall thickness can be reduced and the pressure loss of the flowing gas can be reduced, so that the thickness of the anticorrosion layer should be as small as possible. Furthermore, it is necessary that the base metal can be uniformly coated with no deviation even on an object having a complicated shape. In particular, the shape of the honeycomb is complicated, and the presence or absence of the anticorrosion layer and the thickness are likely to vary,
This condition is important because if not formed uniformly over the entire surface, corrosion will proceed from there.

[0009] Then, assuming that the above conditions are satisfied, it has been determined that it is appropriate to form a glass layer containing crystalline glass on a metal substrate as an anticorrosion layer. In other words, the invention according to claim 1 of the present application is a catalyst carrier comprising a tubular base material having a cross-section honeycomb structure made of a metal corrugated foil and a spacer foil, and a corrosion protection layer covering the surface of the base material. The layer is a catalyst support made of glass, including crystalline glass.

Crystalline glass is chemically stable, has low reactivity to corrosive components, and is dense and does not allow a reactive gas to pass therethrough. By forming a glass layer containing, the metal substrate of the base material can be protected. In addition, since crystalline glass has a high melting point and excellent heat resistance, it can be used for a catalyst used at a high temperature.

Further, as described later, the crystalline glass is dispersed in a liquid solvent so as to be in a liquid state, and the liquid is applied, whereby even a coating material having a complicated shape can be uniformly applied. Therefore, a uniform anticorrosion layer can be formed even on the honeycomb-shaped substrate of the present invention.

As a component of the crystalline glass forming the anticorrosion layer, the main crystal is anorthite (CaAl ₂ S).
i ₂ O ₈ ), throat site (SrAl ₂ Si)
₂ O ₈ ), 1 of celsian (BaAl ₂ Si ₂ O ₈ )
It is preferably a species or a mixture of two or more of these. This is because according to the trial of the present inventors, the glass layer containing these crystalline glasses is considered to have a particularly high anticorrosion effect.

In the present invention, as the constituent material of the tubular base material, a metal material used in a conventional metal honeycomb carrier can be used. Specifically, a heat-resistant alloy such as a stainless-based heat-resistant alloy material (Fe—Cr—Al alloy or the like) is used.

In a general catalyst, a carrier is coated with a porous inorganic material (generally called a washcoat) such as alumina or zirconia in order to enhance the dispersibility of the catalyst particles and improve the effective surface area. Then, the catalyst particles are supported thereon to produce. When producing a catalyst using a catalyst carrier having a crystalline glass layer of the present invention,
A wash coat can be coated on the glass layer to support and use a catalyst component, and no special care is required for handling.

Next, a method for producing a catalyst carrier according to the present invention will be described. The catalyst support according to the present invention, a metal corrugated foil and a spacer foil are laminated to produce a cylindrical substrate having a cross-sectional honeycomb structure, and the cylindrical substrate is immersed in a solution containing crystalline glass to form a solution. After being attached to the cylindrical substrate, the cylindrical substrate is heated to form an anticorrosive layer containing crystalline glass on the metal substrate.

Here, the corrugated foil refers to a metal foil to which a corrugated shape is previously given by a forming roll capable of corrugating, and the spacer foil refers to a flat metal foil. The thickness of these metal foils is 30 to 100 μm in consideration of the pressure loss of flowing gas. In manufacturing the base material, a corrugated foil and a spacer foil are laminated to form a base material having a honeycomb shape and a square cross section or a circular cylindrical shape. Note that a cylindrical base material can be easily formed by laminating a corrugated foil and a spacer foil and winding the laminated foil.

The cylindrical base material thus formed is immersed in a solution containing crystal glass to attach the crystalline glass to the surface of the base material. The deposition of the crystalline glass can be performed by spraying the solution onto the substrate, but the crystalline glass is adhered to the substrate without deviation by immersion in the solution as described in claim 3. it can. Here, as the solution for immersing the base material, a solution in which only a crystalline glass powder is dispersed in a solvent or a solution in which a mixture of an amorphous glass powder and a crystalline glass powder is dispersed may be used.

After attaching the crystalline glass powder to the surface of the base material, heat treatment is performed at a predetermined temperature. This is because volatile components in the crystalline glass on the surface of the base material are escaped to completely crystallize, and the crystalline glass is sintered to form a strong anticorrosive layer. The heat treatment temperature at this time is preferably in the range of 830 to 950 ° C., which is a temperature above the softening point of the crystalline glass and at which the crystalline glass can be sintered.

A strong anticorrosion layer can be formed on the surface of the substrate by the above-described attachment of the crystalline glass and heat treatment.
As described in claim 3, this anticorrosion layer forming step comprises:
It is necessary to perform the treatment several times while limiting the amount of glass solution attached to the substrate. In other words, the amount of glass (thickness) required for protecting the base material is not applied at once, but the anticorrosion layer is formed a plurality of times by reducing the amount of glass applied per application. . This is because the glass layer shrinks during the heat treatment, and if all the required amount of glass is adhered and fired at a time, the glass layer may be peeled off or holes may be formed in the glass layer. The thickness of the glass layer to be formed is reduced to prevent the glass layer from peeling off, and this is repeated several times to form a required amount of the glass layer.

The mass of the glass solution to be adhered in this single anticorrosion layer forming step should be such that the mass of the glass layer to be formed is 0.3 mg / cm ² or less based on the surface area of the substrate. preferable. This is because the glass layer does not peel off even during the heat treatment at this level.
In addition, as a method of limiting the amount of the glass solution attached so that the mass of the formed glass layer is within the above range, the base material taken out after being immersed in the glass solution is sprayed with air, and the excess glass solution is applied. Is blown away.

At this time, the final mass of the anticorrosion layer (glass layer) is 0.4% based on the surface area of the substrate.
It is preferably about 0.8 mg / cm ² . 0.4
mg / cm ² or less in poor anti-corrosion layer is too thin anticorrosion effect to be formed, whereas, not only there is no difference in the corrosion protection even 0.8 mg / cm ² or more, the pressure of the catalyst to increase the wall thickness of the honeycomb This will affect the loss.

As described above, the handling of the catalyst carrier according to the present invention is not different from the conventional catalyst carrier. Therefore, when producing a catalyst from the catalyst carrier produced by the production method according to the present invention, the catalyst carrier completed by the above method is immersed and dried in a washcoat solution to laminate a washcoat, and further, The target catalyst can be obtained by immersing it in a solution containing a catalyst component.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings.

The manufacturing process of the catalyst carrier 1 according to this embodiment is schematically illustrated in FIG. 50 μm thick stainless steel heat resistant alloy material (Fe-20% Cr-5% Al-0.08%
By laminating a corrugated foil 2 and a flat foil 3 made of La) in multiple layers and winding them, a cylindrical base material 4 having a honeycomb cross section was manufactured. The dimensions of the substrate manufactured in the present embodiment are 158 mm in diameter and 75 mm in length.

Then, the substrate 4 was subjected to a heat treatment at 900 ° C. for 15 hours. This is because aluminum oxide whiskers are grown on the metal surface as anchors for increasing the adhesion strength between the carrier metal and the crystalline glass layer to be subsequently applied. Note that this heat treatment may be performed not only after the carrier is assembled from the foil as in the present embodiment, but also as a carrier after the foil is heat-treated first.

Next, the pretreated base material 4
Was immersed in the crystalline glass solution 5. Crystalline glass solution
5 is an amorphous glass powder (SiO 2)₂: 54.9%, B₂
O: 35.0%, CaO: 7.4%, MgO: 2.5
%, PbO: 17.6%, Al ₂O₃: 8.4%, Na
₂O: 2.6%, K₂O: 1.6%) and heat-resistant oxide
(Al₂O₃) And ethyl cellulose α-turbineo
To the paste dispersed in
A crystalline glass powder (SiO ₂:
35.6%, B₂O: 3.1%, CaO: 16.9%,
ZnO: 19.2%, Al₂O₃: 11.3%, TiO
₂: 13.9%) and a glass paste mixed with
Mixed with propyl alcohol in a ratio of 1: 2
is there.

Then, the substrate 4 immersed in the glass solution was taken out, and the glass solution was blown off by blowing air to minimize the amount of glass adhered per process.

The substrate on which the glass was adhered was temporarily dried at 120 ° C. for 30 minutes to remove alcohol, and then completely dried at 250 ° C. for 1 hour. And it heated at 950 degreeC for 2 hours, and crystallized the glass of the base material surface, and formed the anticorrosion layer.

The above-mentioned immersion of the base material in the glass solution and the heat treatment step are performed twice, and the base material has a surface area of 0.52 m
g / cm ² of glass layer is finally formed to form the catalyst support 1
Was manufactured.

The catalyst carrier 1 according to this embodiment was coated with alumina as a wash coat, and further supported with catalyst particles (platinum) to produce a deodorizing catalyst.

When this deodorizing catalyst was attached to the exhaust pipe of a heat-drying toilet and subjected to an actual test, the catalyst did not corrode even if it was used for 6 months or more after the start of the test. I couldn't.

On the other hand, when a deodorizing catalyst manufactured using a conventional metal honeycomb not coated with crystalline glass was attached to the same exhaust pipe of a heat-drying toilet and a comparative test was performed, two months after the start of the test The carrier corroded and the catalyst collapsed.

[0033]

As described above, the catalyst carrier according to the present invention is excellent in corrosion resistance. Therefore, the catalyst produced by using the catalyst carrier according to the present invention can be used for a long period of time without being damaged by corrosion even when the object to be treated contains a corrosive component.

Further, since a metal is used as a constituent material, it has characteristics of a conventional metal honeycomb, that is, low pressure loss, high strength, and high thermal conductivity. A catalyst excellent in handleability and catalytic performance can be produced.

[Brief description of the drawings]

FIG. 1 is a view showing a manufacturing process of a catalyst carrier according to the present embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Catalyst support 2 Corrugated foil 3 Flat foil 4 Substrate 5 Glass solution

 ──────────────────────────────────────────────────続 き Continuing on the front page F term (reference) 3G091 AB01 BA00 GA06 GA08 GA16 GB01X GB06W GB16X GB17X 4D048 AA21 BA39X BA39Y BA48X BA48Y BB02 BB05 BB12 BC05 4G069 AA01 AA08 AA09 BA14A BA14B BA17 CA02 EA19 CA13 FA04 FB23 FC04

Claims (4)

[Claims] 1. A catalyst carrier comprising: a tubular base material having a cross-section honeycomb structure made of a metal corrugated foil and a spacer foil; and an anticorrosion layer covering a surface of the base material, wherein the anticorrosion layer is formed of a crystal. A catalyst support made of glass containing a functional glass. 2. The catalyst carrier according to claim 1, wherein the crystalline glass constituting the anticorrosion layer has a main crystal composed of one or more of anorthite, throatsite, and celsian, or a mixture of two or more thereof. 3. A base material manufacturing process for manufacturing a cylindrical base material having a honeycomb structure in section by laminating a metal corrugated foil and a spacer foil, and immersing the cylindrical base material in a solution containing crystalline glass. And then applying the solution to the cylindrical substrate by heating the cylindrical substrate to form an anticorrosion layer containing crystalline glass. A method for producing a catalyst carrier, wherein the layer forming step is performed a plurality of times while limiting the amount of solution adhering to the cylindrical substrate. 4. The adhesion amount of the solution according to claim 3, wherein the mass of the anticorrosion layer formed in one anticorrosion layer formation step is limited to 0.3 mg / cm ² or less based on the surface area of the base material. A method for producing a catalyst carrier.