JPH1133412A - Production of metal-supporting catalyst - Google Patents

Abstract

PROBLEM TO BE SOLVED: To uniformly carry a metal having catalytic activity on a porous material by adjusting the pH of a solution containing the metal having catalytic activity to a specific range, adding a surfactant, dipping the porous material into the solution and treating with ultrasonic wave in the production of the metal-supporting catalyst. SOLUTION: In the production of the metal-supporting catalyst produced by carrying the metal having catalytic activity on the porous material as a catalyst for the hydrogenation of a hydrocarbon, the solution prepared by dissolving the metal to be carried as an aq. solution of the metallic salt such as the chloride and containing the metal having catalytic activity is adjusted to pH of 5-9 and after that, the surfactant is added. In the addition of the surfactant, a surfactant corresponding to the ionicity of the metallic salt is added. Next, the aq. solution, in which the porous material is dipped, is treated with ultrasonic wave. As a result, the infiltration of the metal having catalytic activity into inside of the porous material is accelerated. Then, the metal-supporting catalyst is dried and if necessary, fired to complete the desired catalyst.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a metal-supported catalyst, and more particularly to a method for producing a metal-supported catalyst by supporting a metal on a porous material by an impregnation method.

[0002]

2. Description of the Related Art As a catalyst for a complete oxidation reaction, a reforming reaction, a dehydrogenation reaction, and a hydrogenation reaction of a hydrocarbon, a porous material, particularly a metal oxide porous material, on which a metal having catalytic activity is supported. It's being used.

As a method for producing a metal-supported catalyst by supporting a metal on a porous material, an impregnation method, a coprecipitation method, and the like are known ("Chemical Review" No. 34, p. 29, 19).
(Edited by the Chemical Society of Japan in 1982, published by the Society Press).
Among these methods, the impregnation method is a method in which a porous material is immersed in a metal-containing solution containing a catalytic activity, generally, a metal-containing aqueous solution, and the metal is supported on the surface thereof. It is widely used because it has high performance.

[0004]

However, in such a method, the metal in the solution can be supported by physically adsorbing the metal on the surface. There is a problem that the amount of metal to be supported cannot be so large. In addition, it is difficult for the solution to enter the pores due to problems such as the surface tension of the solution. There was a problem that it could not be carried on. In addition, when the metal-containing solution is a strong acid solution, there is a problem in that when the solution is impregnated with a carrier having low acid resistance, the carrier is denatured.

[0005] Japanese Patent Publication No. 5-2372 discloses that when a platinum group element is supported on an inorganic fibrous laminate or molded article, a catalyst is prepared by impregnation using an aqueous solution of a platinum group element compound containing a surfactant. Although a production method is disclosed, it merely utilizes the permeation effect of a surfactant, and does not consider the ionicity of the carrier and the ionicity of a carrier or a catalyst metal salt.

The present invention is a method capable of supporting a large amount and uniformly of a metal having catalytic activity on a porous material. In particular, the present invention is applicable to a method of uniformly collecting a fibrous material which has been difficult by a conventional impregnation method. It is an object of the present invention to provide a method for producing a metal-supported catalyst that can be supported on a metal.

[0007]

Means for Solving the Problems The inventors of the present invention have made intensive studies to solve such problems, and as a result, added a surfactant to a metal-containing solution having catalytic activity, and added a porous material to the solution. It has been found that a metal having catalytic activity can be supported on a porous material in a large amount and uniformly by treating with ultrasonic waves in a state of immersion, and arrived at the present invention.

That is, according to the present invention, when a metal-supported catalyst is produced by supporting a metal on a porous material, the pH of a solution containing a metal having catalytic activity is adjusted to pH 5 to 9, and then a surfactant is added. It is another object of the present invention to provide a method for producing a metal-carrying catalyst, which comprises adding a porous material to the solution and treating the porous material with ultrasonic waves.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
Examples of the porous material used in the present invention include porous materials made of carbon (for example, activated carbon), metals, metal oxides, and ceramics. Among them, porous materials made of metal oxides and ceramics are preferable. As the metal oxide, at least one selected from the group consisting of silicon, aluminum, beryllium, magnesium, calcium, barium, cerium, titanium, zirconium, vanadium, manganese, copper, iron, chromium, cobalt, tin, zinc, niobium, and tungsten Oxides of one kind of metal are mentioned. The ratio of metal to oxygen in these metal oxides is
Although not particularly limited, a stoichiometric ratio is preferable. Further, a composite oxide represented by a composition ratio MxNyOz (where M and N are metal atoms, O is an oxygen atom, and X, Y and Z are numerical values representing the composition ratios) composed of a plurality of these metals. Can also be used, and in this case, the composition ratio is not particularly limited. Preferred oxides or composite oxides include Al ₂ O ₃ , SiO ₂ and Mn.
_{O 2, TiO 2, ZrO 2} , MgO, Al 2 O 3 -Si
O ₂ , TiO ₂ —Al ₂ O ₃ , TiO ₂ —SiO ₂ , T
The iO ₂ -ZrO _2, TiO ₂ -MgO, etc. can be exemplified.

[0010] The pore size of the porous material present in the porous material used in the present invention is not particularly limited, and may be formed by fine pores inherent in the compound solid, or may be formed by aggregation of the compound fine particles. It may be due to voids formed between the fine particles.

The shape of the porous material is not particularly limited, and examples thereof include a particle shape, a fibrous shape, and a molded product thereof, such as a honeycomb shape. When the porous material is in the form of particles, the particle size range is 0.5 to 30 mm, preferably 1 to 10 mm, and the specific surface area is 10 to 50 mm.
0 m ² / g, preferably from 30~300m ² / g.

When the porous material is a fibrous material, the fiber has a diameter of 1 mm or less and a length of at least 10 times the aspect ratio of the diameter, preferably 0.5 mm or less and an aspect ratio of 20%. More than double is suitable. Examples of the fibrous aggregate include a nonwoven fabric shape, a woven fabric shape, and a roll shape.

The metal used in the present invention is not particularly limited as long as it is a metal having catalytic activity, but titanium, vanadium, chromium, cobalt, manganese, platinum, palladium, rhodium, ruthenium, nickel, etc. Are preferred, and particularly, a Group VIII metal represented by platinum, palladium, rhodium, nickel and the like. One of these metals may be supported, or two or more of these metals may be mixed and supported.

In the production method of the present invention, a metal-containing solution comprising the above-mentioned metal is first prepared. This solution is usually an aqueous solution, and can be prepared by dissolving the metal to be carried as a water-soluble metal salt in water. As the metal salt, general metal salts such as chloride, acetate, nitrate and chlorate can be used. Some metal salts are hardly soluble in water, so raise the temperature of the solution to increase the solubility of the metal salt, or convert inorganic acids such as hydrochloric acid and nitric acid and organic acids such as oxalic acid to 1 mole of metal salt. It can be dissolved by adding 0.1 to 2 moles, preferably 0.5 to 1 mole.

The concentration of the metal-containing solution is not particularly limited, but is preferably 0.1 to 300 m / g of the porous material.
g, preferably from 0.2 to 200 mg of metal. The volume of the metal-containing solution may be 2 to 10 times, preferably 3 to 6 times the apparent volume ratio of the porous material to be supported. When the amount of the metal contained in the metal-containing solution is smaller than this, the effect of the ultrasonic treatment tends to be reduced.

The metal-containing solution thus obtained can have various pH depending on the kind of the metal salt contained. In the present invention, it is necessary to adjust the pH of the metal-containing solution to near neutrality, and the range is 5 to 9. More preferably, the pH may be adjusted to 6 to 8. If the pH is out of the range of pH 5 to 9, the porous material has an adverse effect such as denaturation, and the catalyst metal cannot be uniformly and largely supported. Therefore, if it is out of this range, a pH adjusting solution is added so as to be within this range.

Examples of the pH adjusting solution used here include a weak acid aqueous solution such as an acetic acid aqueous solution, a weak base aqueous solution such as an ammonia water, and a pH buffer solution such as monopotassium phthalate, monopotassium citrate and acetic acid-sodium acetate. .

In the present invention, a surfactant is then added to the pH-adjusted metal-containing solution. At this time, it is desirable to add a surfactant according to the ionicity of the metal salt. For example, when the metal salt in the metal-containing solution is a negative ion, an anionic surfactant is added, and when the metal salt is a positive ion, a cationic surfactant is added. When the ionicity of the metal salt is opposite to the ionicity of the porous material, it is desirable to add a nonionic surfactant. Not limited to these examples, a plurality of different surfactants may be added. The nonionic surfactant is effective in many cases because it is hardly affected by the ionicity of the porous material and the ionicity of the metal salt to be supported due to its osmotic action. Further, the nonionic surfactant is particularly effective when the porous material shows basicity.

As the surfactant used in the present invention, those commonly used in the field of the chemical industry can be used. Examples of the anionic surfactant include an anionic surfactant such as a sulfate ester salt, a sulfonate salt and a phosphate ester, and examples of the anionic surfactant include an aliphatic amine salt and a quaternary ammonium salt. Examples include cationic surfactants such as salts, and examples of nonionic surfactants include fatty acid esters of polyhydric alcohols, nonionic surfactants such as polyoxyalkylene condensates, and polyglycerin.

The amount of the surfactant used in the present invention is not particularly limited, but may be 0.05 to 50 per gram of the porous material.
0 mg, preferably 0.1 to 250 mg. If the amount is less than this, the effect of the addition is small, but if it is too large, the cost may increase.

In the production method of the present invention, the porous material is then immersed in a metal-containing solution to which a surfactant has been added. The temperature of the metal-containing solution at that time is not particularly limited, but is preferably in the range of 20 to 60C. After immersion, it is preferable to leave the porous material for one hour or more in order to adapt the metal-containing solution to the porous material. In order to more effectively infiltrate the solution into the inside of the porous material, the solution in which the porous material is immersed can be placed under reduced pressure.

Next, the aqueous solution in which the porous material is immersed is treated with ultrasonic waves. As the ultrasonic generator, a commercially available ultrasonic cleaner or the like can be used. As a general method, a tank of an ultrasonic cleaning machine is filled with water, and a beaker containing a porous material immersed in the tank and a metal-containing solution is placed therein and subjected to ultrasonic treatment. At this time, energy is added by treating with ultrasonic waves, and the energy is 0.1 to 10
W / cm ² are preferred, especially 0. 2~8W / cm ² preferably. When the added energy is lower than this, the effect of stirring or the like is reduced, and it becomes difficult to carry a large amount of metal having catalytic activity uniformly. On the other hand, if it is larger than this, the temperature of the metal-containing solution rises, so that it becomes difficult to control the amount of adsorption.

The duration of the sonication depends on the applied energy,
Although it depends on the structure of the porous material, the viscosity of the aqueous solution, the surface tension and the like, it is preferably 0.01 to 10 hours, particularly preferably 0.5 to 10 hours.
~ 5 hours are preferred. Further, the temperature of the metal-containing solution at this time is preferably from 40 to 90 ° C, particularly from 60 to 80 ° C.
C is preferred. By maintaining the temperature of the metal-containing solution in the above range, the time required for ultrasonic treatment can be shortened.

As described above, the metal having catalytic activity uniformly dispersed by the surfactant added in consideration of ionicity is further promoted by ultrasonic treatment to penetrate into the inside of the porous material. The addition of the agent alone or the ultrasonic treatment alone enabled the metal to be supported more uniformly than could be imagined.

According to the present invention, a metal-supported catalyst can be obtained, and after drying the obtained metal-supported catalyst,
A good catalyst can be obtained by calcining if necessary. The drying conditions are not particularly limited and may be performed under conditions that can remove moisture from the porous material.
The water is evaporated at 80 ° C. or higher, preferably 100 ° C. or higher. The firing conditions may be appropriately selected depending on the porous material and the supported metal.
1 to 5 hours at 50 to 500 ° C, preferably 300 to 40
It may be performed at 0 ° C. for 2 to 4 hours. If necessary, it can be reduced with hydrogen. By this sintering, the metal is baked on the porous material as metal particles, and a good catalytic function is exhibited.

[0026]

Next, the present invention will be described specifically with reference to examples. In addition, the combustion rate of toluene was measured as follows. [Toluene combustion rate] Sample 0.1 g, diluent 0.5 g
Is mixed well, packed in a reaction tube, and toluene
m was flowed under normal pressure at a flow rate of 200 cc / min, and the mixture was burned at 250 ° C. Methane before and after the reaction was detected by TCD using a gas chromatograph (GC-8A manufactured by Shimadzu Corporation) and calculated by the following equation. Burn rate (%) = (1-toluene concentration after reaction / toluene concentration before reaction) x 100

Examples 1-4, Comparative Example 1 Magnesia (Kyowa Mag 150 manufactured by Kyowa Chemical Industry Co., Ltd., specific surface area 150 m ² /
g) 1 g was prepared. On the other hand, chloroplatinic acid (manufactured by Nacalai Tesque, Inc.) was prepared by adding 0.5 wt% of platinum to magnesia.
Since the pH of the aqueous chloroplatinic acid solution prepared by dissolving in water was adjusted to 2.0, ammonia water was added to adjust the pH to 6. Since the ionicity of magnesia is negative and the ionicity of aqueous chloroplatinic acid solution is negative, it is desirable to use an anionic surfactant or a nonionic surfactant. Therefore, for 100 ml of this chloroplatinic acid aqueous solution, 10 m of lauryl ether nonion (manufactured by Takemoto Yushi Co., Ltd.), which is a nonionic surfactant, is used.
g (Example 1), 100 mg (Example 3) and 10 mg (Example 2) of lauryltrimethylammonium chloride (manufactured by Takemoto Yushi Co., Ltd.) as an anionic surfactant.
100 mg (Example 4) were each added.

Next, magnesia was immersed in these aqueous solutions of chloroplatinic acid and left at room temperature for 6 hours. Next, the beaker containing the immersion liquid is placed in an ultrasonic cleaner (Ultrasonic Cleaner VS-100 manufactured by Iuchi Co., Ltd.), and 50 W of energy (0.3 W / cm ² ) is maintained at 60 ° C.
Was applied and ultrasonic treatment was performed for 2 hours to impregnate magnesia with an aqueous solution of chloroplatinic acid. After sonication, the solution was dried at 120 ° C. for 12 hours,
The catalyst was prepared by calcining at 0 ° C. for 2 hours and further in hydrogen at 300 ° C. for 3 hours. Table 1 shows the initial toluene burning rate and the toluene burning rate after 10 hours of the obtained catalyst.

[0029]

[Table 1]

For comparison, the same operation was carried out for a catalyst without the addition of a surfactant (Comparative Example 1) to prepare a catalyst. The toluene conversion is shown in Table 1, and it is clear that both the initial toluene conversion and the toluene conversion after 10 hours are inferior.

Example 5 Ceramic fiber cloth "Nextel AF40"
(3M Co., woven Schuss of continuous fibers of a fiber diameter of about 10 [mu] m, basis weight 854g / m ²⁾ 100g (width of about 10 cm ×
(Length 120cm x thickness 1cm) in air at 500 ° C
Baking was performed for a time to remove the binder. Chloroplatinic acid (manufactured by Nacalai Tesque) was dissolved in water to prepare an aqueous chloroplatinic acid solution such that the amount of platinum with respect to the ceramic fiber cloth was 1% by weight. The pH of this solution is adjusted to pH 6
Was prepared. The ionicity of the ceramic fiber cloth was positive, and the ionicity of the aqueous chloroplatinic acid solution was negative. To 200 ml of this aqueous solution of chloroplatinic acid, 200 mg of lauryl ether nonion (manufactured by Takemoto Yushi Co., Ltd.), which is a nonionic surfactant, was added.
Left for hours.

The above-mentioned ceramic fiber cloth was immersed in this solution and left at room temperature for 6 hours. Next, a beaker containing a ceramic fiber cloth and an aqueous solution of chloroplatinic acid was placed in an ultrasonic cleaner similar to that used in Examples 1 to 4, and an energy of 60 W (0.3 W / cm ² ) was applied to the beaker. Impregnated for hours. After the completion of the ultrasonic treatment, the solution was dried at 120 ° C. for 12 hours, and then calcined in air at 500 ° C. for 2 hours and further in hydrogen at 300 ° C. for 3 hours to prepare a catalyst. The obtained catalyst has a metal color on the entire surface of the fiber by visual observation, and it can be seen that the metal having catalytic activity is uniformly supported. In addition, the cloth had a uniform metal color even in the thickness direction of the cloth.

Comparative Example 2 A catalyst in which chloroplatinic acid was supported on a ceramic fiber cloth was prepared in exactly the same manner as in Example 5 except that no surfactant was used and no ultrasonic treatment was performed. In the obtained catalyst, even by visual observation, it can be seen that the ceramic fiber cloth has a mottled metallic color and the metal is unevenly supported. In the thickness direction of the cloth, there was a portion having no metal color inside.

[0034]

According to the present invention, a large amount of metal having catalytic activity can be uniformly supported on a porous material.
A catalyst having high reaction activity can be obtained.

Claims (1)

[Claims] When producing a metal-supported catalyst by supporting a metal on a porous material, the pH of a solution containing a metal having catalytic activity is adjusted to pH 5 to 9, and then a surfactant is added. A method for producing a metal-supported catalyst, comprising immersing a porous material in a solution and treating it with ultrasonic waves.