JP3283593B2 - Method for producing catalyst body - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for equipment for heating, hot water supply, drying, cooking, refrigeration, air conditioning and the like, and has a function of removing odor components present in rooms, toilets, refrigerators, cookers and the like. The present invention relates to a method for manufacturing a medium.

[0002]

2. Description of the Related Art Heretofore, a method of arranging activated carbon in a room and adsorbing gaseous malodorous substances to deodorize them has been mainly used. Recently, a method has been proposed in which a device having an ozone generating function is disposed in a room and an odorous component is oxidatively decomposed by ozone gas. These malodorous substances are mainly ammonia, fatty acids, unsaturated hydrocarbons, sulfur-containing organic compounds, nitrogen-containing organic compounds, etc., which are generated by physiological actions such as sweat of living humans and decomposition of foods. is there.

[0003] However, in the conventional adsorption with activated carbon, there is a problem that the adsorption capacity varies depending on the type of odorous component, and that it is necessary to replace it when saturation adsorption is reached. In addition, the odor decomposition method using ozone requires that a special device be provided to control the optimum ozone generation concentration for decomposition and deodorization, that there are odorous components that are difficult to decompose by ozone, and that the ozone generator There is a problem such as having a long life.

Therefore, in order to solve the problems of the prior art, there has been proposed a deodorizing apparatus provided with a catalyst comprising a noble metal and zeolite or magnesium silicate and an inorganic binder, and a heating source for regeneration. As a result, various odor components in the room can be adsorbed and deodorized without variation, and can be used semi-permanently.

[0005] In this method, a heating source is intermittently energized, and when not heated, deodorization is performed by adsorbing malodorous components with zeolite or magnesium silicate contained in the catalyst,
When the adsorption capacity reaches saturation, the catalytic body is heated to activate the noble metal, which is a catalytic substance. In this method, the adsorbed odor substance is oxidized and decomposed to regenerate the adsorption ability of zeolite or magnesium silicate, and then deodorization is performed again at room temperature.

[0006]

The method of repeatedly performing adsorption and oxidative decomposition includes a method of coating the outer surface of a heating element such as a quartz tube heater with a catalyst film and a method of forming a granular, pellet, or honeycomb shape. There is a method of placing a heating element near the catalyst body.

Of these, a granular catalyst is used by sintering a sol obtained by mixing a platinum group salt or a metal oxide carrying a platinum group catalyst, zeolite or magnesium silicate, and silica sol. There is a method of pulverizing the body and selecting a substance having a predetermined particle size with a sieve, but in this case, there is a problem that many of the substances are crushed to a predetermined particle size or less, resulting in a large loss.

Further, in order to form a pellet or a honeycomb, a sol obtained by mixing a platinum group salt or a metal oxide carrying a platinum group catalyst, zeolite or magnesium silicate, and silica sol is dried. After gelling to viscosity, molding and firing method, or reducing the amount of silica sol, or using a silica sol with a small amount of water, a metal oxide carrying a platinum group salt or platinum group catalyst, There is a method of gelling by adding zeolite or magnesium silicate, kneading, molding and firing. However, the former method has a problem that an operation for drying and gelling the sol is required, and a predetermined viscosity cannot be obtained unless the drying conditions are fixed. Since it is gelled, it is difficult to mix uniformly, and therefore, there is a problem that an operation for mixing uniformly with a kneader or the like is required.

SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to form a catalyst for removing odor and harmful gas simply and by uniformly dispersing the components in the catalyst.

[0010]

The present invention provides a sol obtained by mixing a platinum group salt or a metal oxide carrying a platinum group, zeolite or magnesium silicate, and silica sol.
Water-soluble divalent or higher valent metal salt or low surfactant
Add at least one to allow gelation or pH 5
After the gel is formed by adjusting the pH at 7, the catalyst is manufactured by molding and firing.

[0011]

According to the present invention, first, a platinum group salt or a metal oxide carrying a platinum group, zeolite or magnesium silicate, and silica sol are mixed to form a sol. Here, the zeolite or magnesium silicate used in the present invention is used as an adsorbent, and can adsorb and deodorize various odor components in a room as compared with a general activated carbon as a conventional adsorbent, and have an adsorption performance. Has no variation.

As the platinum group salts, chloroplatinic acid, palladium chloride, rhodium nitrate and the like are used, and most of them are water-soluble, dissolved in silica sol, heated and thermally decomposed to form platinum, palladium or palladium, respectively. By heating the catalyst, these precious metals are activated by heating the catalyst, deodorizing the odorous substances in the air in contact with the catalyst by oxidative decomposition, and adsorbed on zeolite or magnesium silicate. It acts as a catalyst to oxidize and decompose odorous substances and regenerates the adsorption capacity of the adsorbent.

It is to be noted that those noble metal catalysts which are previously supported on the surface of a metal oxide such as alumina may be used. In particular, by supporting the catalyst on the alumina surface, a highly active catalyst can be adjusted.

The silica sol used as a binder of the catalyst loses its stability as a sol when the pH changes, an electrolyte is added, or the amount of water decreases.
It has the property of gelling and increasing viscosity. For this reason, gelation may occur during mixing of the metal oxide or the adsorbent carrying the platinum group. In such a case, it is necessary to knead using a kneader or the like in order to uniformly disperse.

Therefore, when the platinum group salt or the metal oxide carrying the platinum group and the adsorbent are mixed with the silica sol, the sol is low in viscosity and can be easily dispersed uniformly. It is desirable to gel the mixed metal oxide and adsorbent after mixing. Here, when the amount of the adsorbent or the metal oxide carrying the platinum group is large, the metal oxide or the adsorbent may gel during the addition to the silica sol, but in this case, the silica sol is diluted with water or the like in advance. By doing so, it is possible to prevent gelation.

The mixed sol thus prepared is mixed with a water-soluble divalent or higher-valent metal salt, a substance which is soluble in water and shows acidity,
After adding at least one of a group consisting of a substance showing a basic property by dissolving in water and a surfactant, gelling, and then molding and calcining, a catalyst is obtained. Here, the water-soluble divalent or higher valent metal salt is a divalent or higher valent such as nitrate, acetate, sulfate, chloride or the like of barium, magnesium, calcium, copper, nickel, cobalt, aluminum or the like. Use highly water-soluble salts.

This is because silica sol is hardly gelled even when a large amount of monovalent cation is added, and the charge balance of silica is lost due to the presence of polyvalent cation, and gelation easily occurs. I do. In addition, when trivalent cations are added rather than divalent, gelation can occur with a smaller amount. Further, an acid such as acetic acid or hydrochloric acid may be used as the gelling agent. This is because the silica sol is unstable at pH 4 to pH 7.

Further, the pH of the silica sol used is 2 to 4
In this case, the gel can be formed by adding a base such as sodium hydroxide or potassium hydroxide and raising the pH of the mixed sol to 5 to 7. Further, a surfactant such as an alkyl ammonium salt or an alkyl glycine may be used as the gelling agent. These surfactants dissolve in water to dissociate ions such as alkyl ammonium ions,
This causes the silica sol to gel. The gel that has been gelled to a predetermined viscosity is formed into a required shape such as a pellet or a honeycomb, and then dried and fired to obtain a catalyst.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As for the platinum group catalyst used in the present invention, it is desirable to add alumina previously supporting the platinum group catalyst to the silica sol. By supporting a platinum group catalyst on alumina,
The activity is higher than when a platinum group catalyst is supported on zeolite or magnesium silicate.

Further, the zeolite of the present invention has A type, X type and Y type.
Various zeolites, such as a type and a 10-membered ring type, can be used. Among them, copper ion-exchanged zeolite is particularly preferable because it has the best odor adsorption ability.

The magnesium silicate of the present invention is a composition in which magnesium oxide such as magnesium orthosilicate, magnesium metasilicate, talc, magnesium tetrasilicate, magnesium trisilicate, etc., silicon dioxide and water are combined at various ratios.

The content of the silica sol of the present invention is desirably 10% by weight or more of the solid content in the catalyst. If it is less than 10% by weight, a sufficient adhesion effect as a silica sol binder cannot be obtained.

It is desirable that the catalyst of the present invention contains cerium oxide. When cerium oxide is contained in the catalyst, the oxidative decomposition activity of the catalyst substance with respect to the hydrocarbon compound can be improved. Examples of the cerium oxide supporting method include a method in which cerium oxide is mixed in a metal oxide supporting a platinum group, and a method in which a catalyst body is molded, then impregnated with an aqueous cerium nitrate solution, and calcined to obtain cerium oxide.

The content of the cerium oxide is desirably 2 to 15% by weight of the solid content in the catalyst in terms of cerium oxide. If the content of cerium oxide exceeds 15 wt%, the oxidative decomposition characteristics of the catalyst begin to decrease, and 2 wt%
If the amount is less than the above, a sufficient effect of adding cerium oxide cannot be obtained.

It is desirable that the coating composition of the present invention contains barium oxide. By including barium oxide in the catalyst body,
The oxidative decomposition characteristics of the catalyst can be improved.

The content of barium oxide of the present invention is desirably 0.5 to 5 wt% of the solid content in the catalyst. If the content of barium oxide exceeds 5% by weight, the catalyst becomes brittle. If the content is less than 0.5% by weight, a sufficient effect of adding barium oxide cannot be obtained.

The same effect can be obtained by using barium carbonate instead of barium oxide of the present invention. The desirable amount of barium carbonate added is calculated in terms of barium oxide.
0.5 to 5% by weight.

It is desirable that the catalyst of the present invention contains titanium oxide. By including titanium oxide in the catalyst body,
It is possible to improve catalytic oxidation activity for nitrogen compounds such as ammonia.

The content of the titanium oxide of the present invention is desirably 3 to 15% by weight of the solid content in the catalyst. If the content of titanium oxide exceeds 15% by weight, the catalyst body becomes brittle.
If it is less than wt%, a sufficient effect of adding titanium oxide cannot be obtained.

(Example 1) 800 g of γ-alumina, 6 g of chloroplatinic acid as Pt, 3 g of palladium chloride as Pd
g and water (1500 g) were added, mixed thoroughly using a ball mill, calcined at 500 ° C. for 1 hour, and pulverized to prepare a noble metal-carrying alumina.

A mixed sol A was prepared by adding 175 g of the noble metal-supported alumina and 390 g of copper ion-exchanged zeolite to 1300 g of a pH 9 silica sol aqueous solution containing 20 wt% of silica and uniformly dispersing the mixture. In addition, aluminum nitrate 9 hydrate
After adding g and gelling, the mixture was formed into pellets with a pelletizer. Thereafter, the resultant was dried at 100 ° C. for 8 hours and calcined at 500 ° C. for 1 hour to prepare a catalyst A.

In addition, it took 8 to 12 hours to dry the mixed sol A at 60 ° C. to a viscosity at which molding was possible, and the drying time varied greatly depending on the humidity.

Further, in the mixed sol A, the amount of the silica sol was reduced to 700 g, and 175 g of noble metal-supported alumina and 390 g of copper ion-exchanged zeolite were added. If it was not used, it could not be uniformly dispersed, and the resulting catalyst body was more brittle than catalyst body A due to insufficient binder amount.

Example 2 175 g of γ-alumina, 390 g of copper ion-exchanged zeolite and 1.3 g of chloroplatinic acid as Pt were added to 1300 g of an aqueous solution of silica sol having a pH of 9 and containing 20 wt% of silica.
g, palladium chloride (0.65 g as Pd) was added and uniformly dispersed to prepare a mixed sol. Further, 16 g of aluminum nitrate nonahydrate was added to gel, and then formed into pellets by a pelletizer. Then, it was dried at 100 ° C. for 8 hours and calcined at 500 ° C. for 1 hour to prepare a catalyst.

Example 3 A mixed sol was prepared by adding 390 g of magnesium silicate in place of the copper ion-exchanged zeolite in Example 1, and 20 g of aluminum nitrate nonahydrate was prepared.
After gelation, the mixture was formed into pellets by a pelletizer. Then, it is dried at 100 ° C for 8 hours,
After calcination for a time, a catalyst body was prepared.

Example 4 In Example 1, various metal salts were added in place of aluminum nitrate nonahydrate, and the minimum required amount at which gelation occurred was determined. Sodium chloride, potassium nitrate, lithium nitrate trihydrate, magnesium nitrate 6
Water salt, calcium nitrate tetrahydrate, copper nitrate hexahydrate, iron nitrate 9
Water salt and cerium nitrate hexahydrate were used.
It is shown in (Table 1). When a monovalent metal salt such as sodium chloride, potassium nitrate or lithium nitrate trihydrate was added, no gelation occurred even when the addition was made until a saturated solution was reached.

As shown in Table 1, the use of a trivalent metal salt tends to cause gelation in a smaller amount than in the case of a divalent metal salt. In this example, the metal salt was added as it is, but the same effect can be obtained by dissolving the metal salt in water and adding the aqueous solution to the mixed sol.

[0038]

[Table 1]

Example 5 In Example 1, various acids were added in place of aluminum nitrate nonahydrate, and the effect of promoting gelation was examined. I examined hydrochloric acid, nitric acid and acetic acid.
In each case, gelation occurred at a pH of about 5 to 6.

(Example 6) In Example 3, the pH was 9
A mixed sol was prepared using a silica sol having a pH of 3 containing 20 wt% of silica instead of the silica sol. To the mixed sol were added various metal salts which were dissolved and showed basicity. When sodium hydroxide, potassium hydroxide, and lithium hydroxide were examined, in any case, gelation occurred at a pH of about 5 to 6. In the present embodiment, the metal salt that shows basicity when dissolved is added, but the same effect can be obtained by adding a basic aqueous solution to the sol.

Example 7 In Example 1, instead of aluminum nitrate nonahydrate, various surfactants were added to the mixed sol so as to have a concentration of 5 wt%. Alkyl glycine,
Three types of surfactants each containing alkyltrimethylammonium bromide and oxyethylene dodecylamine as main components were examined, and in all cases, gelling occurred.

[0042]

As described above , according to the method for producing a catalyst body of the present invention , a silica binder which is a general binder is used.
The catalyst can be used to form a homogeneously mixed catalyst body in a simple manner without heating the sol .

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ Identification code FI B01J 23/42 B01J 23/42 M (72) Inventor Kyoji Yamade 1006 Kadoma Kadoma, Kadoma, Osaka Matsushita Electric Industrial Co., Ltd. (56) References JP-A-63-91143 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B01J 21/00-38/74 B01D 53/86

Claims (1)

(57) [Claims] 1. A sol obtained by mixing a platinum group salt or a metal oxide carrying a platinum group, zeolite or magnesium silicate, and a silica sol, at least one of a water-soluble divalent or higher valent metal salt or a surfactant. Add one
Either by Le of, or after being <br/> pH adjusted to gelation at pH 5-7, molded, process for preparing a catalyst body, characterized in that fired to produce the catalyst.