KR20120022794A - Sintered mesh catalyst support and manufacturing method of reduction catalyst for ozone gas - Google Patents

Abstract

Conventional ceramic substrates are easily broken against impact, and are much more brittle when the opening is enlarged. On the other hand, stainless steel substrates are difficult to form small flow paths, and are not manufactured at low cost, and have a honeycomb shape. Because of the structure, the flow path is linear, and in order to increase the possibility of contact between the catalyst material and the reactant material, it is necessary to lengthen the flow path, which makes it difficult to reduce the structure.
In the ozone gas reduction catalyst carrier of the present invention, a porous body obtained by sintering a material consisting of one gold mesh or a material in which a plurality of gold meshes are laminated is used as a substrate for the catalyst carrier, and a catalyst of a platinum group metal or an oxide thereof is formed on the surface of the substrate. To form a thin alumina layer on which the materials are dispersed and supported.

Description

Production method and catalyst support for ozone gas reduction catalyst carrier {SINTERED MESH CATALYST SUPPORT AND MANUFACTURING METHOD OF REDUCTION CATALYST FOR OZONE GAS}

The present invention relates to a catalyst carrier for reducing ozone gas and a method of manufacturing the same.

Conventionally, especially the oxidation catalyst or the reduction catalyst which concerns on the purification process of the exhaust gas of automobiles is manufactured as shown to following patent documents 1-4, for example. That is, the base material for catalyst bodies of the honeycomb structure of the ceramic shape | molded or baked from the stainless steel plate is used. The catalyst substrate is supported by using alumina as a support on the substrate for the catalyst body. The gas containing the reaction substance is oxidized or reduced by passing through a straight flow path formed in a catalyst structure prepared as described above, as a typical example. In addition, the reduction of ozone gas was often performed by passing a gas containing ozone gas through a catalyst vessel filled with particulate manganese dioxide.

(Prior art document)

(Patent Document 1) Japanese Patent Application Laid-Open No. 62-237947

(Patent Document 2) Japanese Unexamined Patent Publication No. 2007-223856

(Patent Document 3) Japanese Unexamined Patent Publication No. 2005-254217

(Patent Document 4) Japanese Patent Publication No. 2006-41170

Patent Document 1 discloses the following. After roughening the surface of a metal, it binds microparticles | fine-particles which have a catalyst carrying activity on the said surface, and carry a catalyst material of ultra-fine particles. In addition, using a sponge metal.

Patent Documents 2 and 4 disclose the following. Use of the silica-alumina compound to which 2.5-10 mass% of silica was added based on the total mass. A gelation is produced by a gelling reaction from a metal alkoxide of aluminum and silicon with this silica-alumina compound. The gelled product is freeze-dried to obtain a porous structure.

Patent Documents 3 and 4 disclose the following. Using aqueous solutions or organic solvent solutions of nitrates or chlorides of palladium, platinum, and / or rhodium. Disperse | distribute the mixed conduction oxide of oxygen ion conduction and electron conduction in this organic solvent solution, and remove the said solvent by evaporation. After evaporating and removing the said solvent, it heat-processes at 600 degreeC or more, and obtains the catalyst material for nitrogen oxide removal.

Patent Literatures 1 to 4 can be said to disclose the following. It relates to the improvement of the contact area of a catalyst with a substance which is brought into contact with the catalyst for an oxidation or reduction reaction (hereinafter referred to as a reaction substance). Or preventing the bonding of the catalyst materials or refining the particles, homogeneously dispersing, or the like. However, Patent Documents 1 to 4 disclose the above, but no consideration has been given to the improvement of the substrate for the catalyst carrier.

That is, Patent Literatures 1 to 4 can grasp that the area of contacting the reactant with the catalyst is somewhat large. However, in patent documents 1-4, the flow path formed in a honeycomb structure is linear. Therefore, Patent Documents 1 to 4 need to lengthen the flow path in order to increase the contact efficiency between the catalyst material and the reaction material and to increase the reaction efficiency. From this, it was difficult for patent documents 1-4 to make the structure small.

As described above, Patent Documents 1 to 4 present a reaction substance in the fluid, and further, passes the fluid from one side to the other side. However, the honeycomb structure made of ceramics in Patent Literatures 1 to 4 has a problem in that it is basically insufficient in rigidity, very weak, and weak in impact. In addition, the honeycomb structural body made of stainless steel sheet in Patent Documents 1 to 4 has a problem in that it is difficult to form a flow path smaller than a certain size and the cost is high.

This invention solves the said subject and achieves the following objectives. Instead of the honeycomb structure, producing a substrate for a catalyst carrier which is excellent in rigidity and further increases the possibility of contact between the catalyst material and the reactant material. Particulate manganese dioxide as a catalyst material is brittle, easily absorbs moisture, and has a property of liquefying when absorbed excessively.

The present invention employs a catalyst substrate having excellent rigidity and excellent economy, and a catalyst material having excellent durability and efficiency in place of manganese dioxide which is generally used for the reduction of ozone gas. In addition, the present invention provides a structure of a catalyst carrier for supporting the catalyst material using them. For this reason, in this invention, the porous body which sintered the raw material which consists of one sheet | seat of gold, or the material which laminated | stacked the several sheet | seat of gold | mesh is used as a base material of a catalyst support body. In addition, the present invention forms a thin alumina layer in which a catalyst substance is dispersed and supported on the surface of the substrate of the catalyst carrier to obtain a reduced catalyst carrier. In addition, this invention makes a platinum group metal or its oxide, or its mixture the said catalyst material.

(Effects of the Invention)

The effects of the present invention are as follows. This invention can ensure the surface area of the thin alumina layer used as a support body widely by using a porous base material. In addition, according to the present invention, the opening diameter can be freely selected to some extent depending on the amount of the reaction substance contained in the gas. In addition, the present invention can flexibly adjust the overall thickness by the number of gold meshes.

In particular, the present invention also has the advantage that a plate-like porous body can be obtained by diffusion bonding by using a sintered gold mesh for a substrate, and thus cutting and bending can be performed, thereby providing a high degree of freedom in molding. In addition, the present invention can change the amount of supported catalyst for each substrate, and it is possible to save expensive catalyst materials.

Therefore, as a synergistic effect of the above advantage by using this invention for the reduction process of ozone gas, the processing efficiency of ozone gas improves and it is excellent in economy.

1 (a) and (b) are diagrams showing experimental results for confirming the effect of the present invention.

In the method for producing an ozone gas reduction catalyst carrier of the present invention, the catalyst carrier is made of a porous body obtained by sintering a reduction catalyst carrier of ozone gas using a single metal mesh or a material in which a plurality of gold meshes are laminated. On the surface of the substrate, a thin alumina layer in which a platinum group metal, an oxide thereof, or a mixture thereof is dispersed and supported is formed to obtain an ozone gas reduction catalyst carrier. In the present invention, a catalyst material having a vanadium metal or an oxide alone or a mixture thereof as a catalyst material can be obtained in place of the above.

And the ozone gas reduction catalyst carrier of this invention uses a plurality of catalyst carriers as needed, for example, and carries out each of them through the gas containing ozone gas. By doing so, the ozone gas reduction catalyst carrier of the present invention efficiently reduces ozone gas.

An ozone gas reduction catalyst carrier having a thin alumina layer of the present invention is produced as follows. First, the solution which added the powder of the nitrate of the platinum group metal used as a catalyst material to the alumina sol solution is prepared. The solution is applied to the previously roughened substrate or the substrate is immersed in the solution to attach a catalyst material to form a thin alumina layer. Thereafter, the substrate is fired at a temperature of 600 ° C to 700 ° C. In addition, the ozone gas reduction catalyst carrier of the present invention is produced as follows. The solution which does not add the platinum group metal nitrate powder to the surface of the said substrate is apply | coated to a board | substrate, or the substrate is immersed in the said solution, and the thin alumina layer is formed in the same manner. The substrate is then immersed in a nitrate solution of the platinum group metal to attach the catalyst material. Thereafter, the substrate is fired at 600 to 700 ° C as described above.

The ozone gas reduction catalyst carrier prepared in the present invention is used as follows. For example, a catalyst carrier having a thin alumina layer in which a porous body sintered a plurality of gold mesh laminated materials is used as a substrate for a catalyst carrier and a platinum group metal is dispersed and supported on the surface of the substrate as necessary. Therefore, it installs in several containers. A gas containing ozone gas is made to pass through this container, and ozone gas harmful to a human body is reduced to harmless oxygen.

The reason for employing the sintered gold mesh in the present invention is that the degree of freedom of opening is high. For example, gold meshes readily available on the market have abundant openings ranging from 0.005 mm to more than 1 cm. Since these gold meshes have different openings, stiffnesses, and porosities, respectively, when combined and sintered, they become excellent materials.

Further, there is an advantage that the sintered gold mesh is firmly fused with the wire rods which the individual wire rods come in contact with, and that the wire rods do not cause a displacement, that is, a stable opening state can be ensured even when stress is applied.

As for the gold net used for the base material of a catalyst support body, it is preferable to use a stainless material as a main material, for example. This is because it is easy to obtain because of excellent corrosion resistance and marketability. As a matter of course, copper or copper alloys other than stainless, or gold meshes such as nickel may be used, but other metals to be mixed are preferably made of a material considering corrosion resistance.

In addition, SV form according to the present invention, to install the catalyst carrier, and, for the example with respect to the process of passing the gas, divided by the response ability (m ³ / hour), the filtration amount of material (for example, 1 liter, etc.) It is preferable to carry out the value (l / h) at 1000-100000 l / h. This is because if it is less than 1000 l / h, the catalyst is excessive, the capacity cannot be used sufficiently, and if it is more than 100000 l / h, the catalyst capacity is exceeded and reduction is not likely to be performed sufficiently.

In addition, regarding the treatment in which the catalyst carrier is installed and the gas is passed, for example, the LV value (cm / sec) obtained by dividing the reaction capacity (m ³ / hour) by the area (m ² ) is 10? 20 cm /. It is preferable to carry out in sec. This is because if it is less than 10 cm / sec, the catalyst does not function sufficiently to lower the efficiency of the catalyst capacity, and if it is more than 200 cm / sec, the catalyst capacity is exceeded, making it difficult to process the whole amount.

Below, the experiment which was performed in order to confirm the effect by the reduction process method of the ozone gas of this invention is demonstrated.

(Example 1)

(Produce)

The description was as follows. Each of 1 sheet of 16, 20, 60, and 30 mesh made of SUS316 and 4 sheets of gold in total were laminated. The laminated gold meshes were vacuum sintered at about 1200 to 1300 ° C. under vacuum and pressure in a vacuum heat treatment furnace. The whole gold mesh after sintering became a porous body with a thickness of 1.8 mm, a minimum opening diameter of 0.25 mm (250 µm), and a porosity of about 60%. This was shape | molded into the disk shape of diameter 50mm, and used as the base material of a catalyst support body.

Subsequently, palladium nitrate was added to the alumina sol solution and the substrate for catalyst support was immersed in this solution. Then, it dried and baked at the temperature of about 650 degreeC in air | atmosphere atmosphere. As a result, a thin alumina layer was obtained on the surface of the substrate, and a catalyst carrier was prepared in which a palladium, a palladium oxide, or a mixture thereof as a catalyst material was dispersed and supported in the alumina thin layer. The catalyst carrier had an estimated thickness of the thin alumina layer of 0.005 mm, a palladium catalyst material particle diameter of about 10-20 nm, and a catalyst loading of about 1.7 g / liter of catalyst.

(practice)

For the catalyst carrier of the present invention prepared as described above, the ozone gas generated by the ozonizer was passed through the catalyst carrier as it is. At this time, the reduction rate was measured in the range of 5-60000 ppm (w) of ozone gas concentration. The measurement result is shown to FIG. 1 (a), (b).

In addition, the reduction rate was measured by changing SV value (l / h) in FIG. 1 (a), and changing LV value (cm / sec) in FIG. 1 (b).

From the results in FIG. 1 (a), it was found that 90% or more of the ozone gas can be reduced and decomposed by setting SV value, which is the inverse of the contact time with the catalyst, to 100Ol / h or less. Also, from the results in Fig. 1 (b), it was found that the LV value is 10-20 cm / sec, which enables reduction reduction of 90% or more of ozone gas.

Claims (3)

A porous alumina made of a material composed of one gold mesh or a material laminated with a plurality of gold meshes is used as a substrate for the catalyst carrier, and a thin alumina layer is formed on the surface of the substrate by dispersing and carrying a platinum group metal or an oxide thereof or a mixture thereof. Method for producing an ozone gas reduction catalyst carrier, characterized in that. The method of claim 1,
The method for producing an ozone gas reduction catalyst carrier, characterized in that the catalytic material is a palladium metal or an oxide thereof, or a mixture thereof. The catalyst support body manufactured by the manufacturing method of the ozone gas reduction catalyst support body of Claim 1 or 2.

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