JPH01203045A - Catalytic body and manufacture thereof - Google Patents

Abstract

PURPOSE:To increase reliability of catalyst at high temperature by forming a carrier layer consisting of inorganic oxide on woven cloth using silica filament as warp and alumina filament as weft and allowing the carrier layer to carry a catalytic component. CONSTITUTION:Woven cloth is formed using silica-contained filament as warp and alumina-contained as weft, and after immersion of said woven cloth in strong acid and subsequent removal of acid eluent, the woven cloth is heated at 800 deg.C or higher to prepare a base. On this base, a carrier layer containing at least one kind of inorganic oxide such as silica, alumina or zirconia is formed. Next, the aforementioned carrier layer is allowed to carry, on its sur face, a catalytic substance which contains at least, one kind of precious metal such as Pt, Pd, Rh, Os or Ir, or its oxide and of base metal such as Co, Cu, Mn, Mo, Ni, Cr, La or Y or its oxide, and thereby a catalytic body is manufac tured.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is applicable to heterogeneous catalysts that carry out catalytic reactions of gases under high space velocities, such as various combustion equipment, pots, heating furnaces in the chemical industry, etc. Catalyst bodies used for exhaust gas treatment, exhaust gas treatment that converts harmful components emitted from internal combustion engines of automobiles, motorcycles, ships, aircraft, etc. into harmless components, or for producing gas, etc., and their manufacturing method. It is related to.

Conventional technology Catalysts used in the above-mentioned industrial fields include granules made of gamma alumina as a base material or carrier, honeycomb-shaped monoliths made of dense cordierite, and gamma alumina etc. After surface treatment, platinum,
There are catalysts that support palladium or the like. In addition, there is a catalyst body obtained by using silica cloth as a base material, which has been technically established and commercialized by the present applicant, by attaching gamma alumina or the like to the surface of the silica cloth, and further supporting platinum, palladium, or the like.

Problems to be Solved by the Invention Catalysts based on the above-mentioned granules have the advantage of being inexpensive and can be used for general purposes, but they have a large pressure loss and are susceptible to mechanical vibrations. Honeycomb-shaped monolithic catalyst bodies have the advantages of low pressure loss and integrated structure, and have recently become widely used, but they are vulnerable to mechanical and thermal shocks, and countermeasures are not easy. Also, it has the weakness of being susceptible to local melting. Furthermore, the cross-shaped catalyst has the advantage of being resistant to mechanical vibrations and capable of maintaining a high conversion rate under high space velocities, and has come to be widely used in various fields.

However, there was a demand from users to increase the heat resistance limit to prevent damage even at high temperatures, and improvements were needed to ensure reliability at high temperatures. In this case as well, it needed to be mass-producible and inexpensive so that it could be used in large quantities industrially.

The present invention particularly aims to expand the advantages of the cross-shaped catalyst and provide a highly reliable catalyst with more excellent characteristics.

Means for Solving the Problems The present invention uses, as a base material, a fabric knitted as a woven fabric using long fibers containing silica as a main component in the warp and long fibers containing alumina as a main component in the weft. Long fibers containing silica as the main component are glass fibers used for electrical insulation with a low alkali content, or glass fibers containing as high a concentration of silica as is permitted for fiber production are twisted and used as warp threads. First, alumina long fibers obtained by synthesis or firing of organic components are knitted into a woven fabric as weft threads, and then immersed in hydrochloric acid or sulfuric acid at 30 to 100°C.
After being left to stand, a strong acid produces a woven fabric consisting of fibers containing only acid-insoluble components such as silica and alumina. This woven fabric is used as a base material for the catalyst body. Furthermore, after this strong acid treatment, the fiber is washed with water to remove the extraction residue on the fiber surface, and then treated at high temperature to create a hard recrystallized layer on the fiber surface. That is.

The catalyst body is silica and alumina on the surface of this base material.

Contains at least one oxide of high-temperature refractory ceramic materials such as zirconia, titania, and ceria to form a carrier layer, and further contains platinum and palladium.

Precious metals such as rhodium, osmium, and iridium, oxides of these precious metals, cobalt, copper, and manganese.

It is characterized by supporting a catalytic substance active in the reaction as a catalyst containing base metals such as molybdenum, nickel, chromium, lanthanum, and yttrium, and at least one type of oxide of these base metals.

Function A woven fabric made of long fibers mainly composed of silica as the warp and long fibers mainly composed of alumina as the weft obtained by this process is used as the base material, a carrier layer is formed on the surface of this fabric, and an active catalyst substance is supported. The resulting catalyst has enhanced functionality as a cross-shaped catalyst and exhibits extremely high activity under high space velocities.

The catalyst is oxidation of carbon monoxide and various hydrocarbons, -nitrogen oxide, reduction of nitrogen dioxide and carbon monoxide, decomposition of nitrogen dioxide to nitrogen monoxide, -nitrogen oxide, reaction of nitrogen dioxide and ammonia, etc. Heating furnace in the chemical industry.

Shows properties that are effective for reactions in reactors, gas production catalysts, etc.

Example (Example 1) About 10 long electrically insulating glass fibers with a diameter of about 10 microns were
00 fibers are bundled, twisted, and two twisted long fibers are used as a warp unit, and the weft contains approximately 80% by weight of alumina, and other components include alumina, which mainly contains silica. A woven fabric was produced using the long fibers (alumina long fibers manufactured by Denki Kagaku Kogyo) as the weft.

The weight of the finished woven fabric was approximately 400 grams per square meter. Next, a tank of strong hydrochloric acid was prepared for this woven fabric, and 50 square meters of the woven fabric was immersed in the tank containing about 200 liters of residual hydrochloric acid and left for 48 hours. The temperature of the hydrochloric acid solution reached its maximum during the first 12 hours of the layer, and returned to approximately room temperature after 48 hours. Next, the woven fabric was placed in a water tank of approximately 2,000 liters, washed with water, and dried to form a base material. Next, alumina sol, silica sol, and zirconia sol are dissolved in ion-exchanged water to form a carrier layer of 20 weight percent alumina, 6 weight percent silica, and 10 weight percent Zircoeff on this base material, and the woven fabric is immersed in the solution.
After being lifted and left at room temperature for 30 minutes, it was dried at 120'C for about 4 hours, and further heated in the atmosphere at 700C for 12 hours to adhere the carrier to the base material. Next, chloroplatinic acid and rhodium chloride were dissolved in ion-exchanged water, and ammonia was added to prepare the solution, and then the carrier-attached base material was immersed. The saturated water content of the carrier-attached base material is determined in advance, and 41.0% of platinum is added per square meter in the amount of the solution to be saturated with water. The amount of chloride dissolved was adjusted so that 0.71% of rhodium was supported. The supported substrate was pulled out of the solution, left in the air at room temperature for 30 minutes, dried at 140°C for 4 hours, and heated in a hydrogen stream at eoo°C for 4 hours to obtain a catalyst supporting platinum and rhodium.

(Example 2) After immersion in a strong acid in the same manner as in Example 1, washing with water and further heat treatment at 950°C for about 2 minutes to form a recrystallized layer on the fiber surface of the base material. I let it happen. A catalyst was obtained using the same carrier and catalyst material as in Example 1.

(Examples 3 to 8) A base material was prepared in the same manner as in Example 1 or 2, and catalysts were obtained by varying the amount of one selected from silica, alumina, zirconia, titania, and ceria as the carrier layer.

(Examples 9 to 16) Furthermore, the weave shape of the base material was changed, and platinum was used as the catalyst metal.
Palladium, rhodium, iridium, osmium, cobalt, copper, manganese, molybdenum.

Metals and metal oxides of nickel, chromium, lanthanum, and yttrium were selected as catalyst materials. The starting materials for the catalyst materials are nitrates, ammonium salts, and chloride salts.

Inorganic salts and organometallic compounds such as ammonium nitrate and acetate were used.

The compositions of the above examples are shown in Table 1.

In order to investigate the characteristics of the above catalyst, Cos o PPM
.

Normal hexane 15PPM (C+ conversion), N02
1oo7 air containing 1.2PPM! This method calculates the conversion rate from the concentrations before and after the catalyst when the gas is passed every minute and the gas temperature is 500°C, and the measurement results at the initial stage and after heating at 900°C for 300 hours, as well as the flexibility of the catalyst in the initial state, are calculated. 1
The flexibility was evaluated by setting the degree of collapse by simply placing a weight of tsc)f7 on the catalyst as O. Heating is 1050
After 100 hours in °C atmosphere. These results are summarized in Table 2.

The evaluation of whether it can be used even at high temperatures of 1000° C. or higher was expressed as ◎ and O1×. × indicates that it is considered difficult to use.

Based on these results, a woven fabric is made using the alumina-based long fibers and silica-based long fibers of the present invention, and these carriers and catalyst metals are used as a base material. It can be seen that the supported catalyst has a very large effect in terms of heat resistance. Prior to this invention, the two types of long fibers described in this application were woven in advance on a loom and considered as a base material, but both of these long fibers have low mechanical strength and cannot be woven on a loom. . Or even if it were applied, the yield would be extremely low and it was thought that mass production would be impossible on an industrial scale. However, synthesized silica long fibers with a strength of 1 OOkg/- or more are on sale, and can be run on a loom, and an effective base material can be obtained by combining them with long fibers whose main component is alumina. It turned out that. However, as a result of the study, the activity as a catalyst was found to be 10-30% lower after the catalyst was prepared, and a catalyst with superior properties was found to be based on a woven fabric in which silica obtained by so-called acid treatment is combined with long fibers as the main component. is obtained.

Various types of long fibers mainly composed of alumina have been developed and provided, but long fibers mainly composed of alumina do not exhibit heat resistance unless the alumina content is 50% by weight or more. It was discovered that it cannot be done. Also, 5
When the alkali is contained as a component even at 0 weight percent or more, it has not been possible to adopt a method of weaving a woven fabric and then subjecting it to acid treatment to obtain a base material. This was thought to be due to the dialkali component being eroded by the acid.

Effects of the Invention As described above, according to the present invention, a woven fabric is produced by using glass fibers with high mechanical strength as warp yarns and using long fibers mainly composed of alumina, which has relatively low strength, as weft yarns, and then acid-treated. By making the warp of the woven fabric into long fibers mainly composed of silica, we have developed a method for producing a catalyst body to obtain a base material, and the catalyst body obtained by this process can be produced stably, in large quantities, and at low cost for the first time. It is revolutionary in that it provides high quality products. The silica-based long fibers extracted with acid have pores that are effective for the catalyst, and are reinforced with alumina-based long fibers, resulting in a catalyst with completely new properties and a method for producing the same.

In addition, in explaining the present invention in detail, examples have been given, but these are not intended to limit the materials or manufacturing conditions.
It goes without saying that changes may be made within the scope defined in the claims as long as they do not interfere with the spirit of the invention.

Claims (4)

[Claims] (1) Long fibers mainly composed of silica are used as the warp of the woven fabric,
A carrier layer containing at least one oxide such as silica, alumina, zirconia, titania, ceria, etc. is formed on a woven fabric base material whose weft is long fibers mainly composed of alumina,
Supported catalyst material containing at least one noble metal or oxide such as platinum, palladium, rhodium, osmium, iridium, base metal or oxide such as cobalt, copper, manganese, molybdenum, nickel, chromium, lanthanum, yttrium, etc. A catalyst body characterized by: (2) Silica component of long fibers mainly composed of silica is 95%
The catalyst body according to claim 1, wherein the alumina component of the long fibers containing alumina as a main component is 50 weight percent or more. (3) A woven fabric is knitted using long glass fibers containing silica as warp threads and long fibers containing alumina as the main component as weft threads, and the woven fabric is immersed in strong acid to extract and remove acid-eluted components from the glass fiber woven fabric. The base material is a woven fabric whose warp yarns are mainly composed of silica and the weft yarns are mainly composed of alumina, and after the woven fabric is eluted with a strong acid, it is washed with water and then heated at 800°C or higher for 10 seconds or more. A carrier layer containing at least one oxide such as silica, alumina, zirconia, titania, ceria, etc. is formed on this woven fabric, and a carrier layer containing at least one oxide such as platinum, palladium, rhodium, osmium, iridium, etc. A method for producing a catalyst body, comprising supporting a catalyst substance containing at least one base metal or oxide such as oxide, cobalt, copper, manganese, molybdenum, nickel, chromium, lanthanum, and yttrium. (4) Silica component of long fibers mainly composed of silica is 95%
4. The method for producing a catalyst body according to claim 3, wherein the alumina component of the long fibers containing alumina as a main component is 50 weight percent or more.