JPH06114272A - Produciton of catalyst - Google Patents

Abstract

PURPOSE:To uniformly deposit an active component and to deposit even a component which is hardly dissolved in a solvent by subjecting a liquid containing the catalytic active component to ultrasonic treatment in the production of catalyst by impregnating a carrier with a catalytic active component. CONSTITUTION:In the production of catalyst to impregnate a carrier with a catalytic active component, the liquid for impregnation containing the catalytic active component is subjectred to ultrasonic treatment. By using ultrasonic, the catalytic active component can be freely selected from any states of elements or compds. without considering whether the component is dissolved or not in the solvent. Namely, even a component which does not dissolved in a proper solvent such as water can exist as fine particles in the liquid by ultrasonic treatment of the liquid for impregnation and can be deposited on the carrier by impregnation. Thus, the component can be deposited in a highly dispersed state on the carrier and the liquid after ultrasonic treatment can be introduced to the carrier.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing a catalyst. More specifically, the present invention relates to a method for uniformly supporting an active component on a carrier by subjecting an impregnating solution containing the catalytic active component to ultrasonic treatment when the catalytic active component is supported on the carrier by an impregnation method.

A noble metal is supported on a carrier such as a hydrocarbon reforming catalyst supporting platinum on alumina, a catalyst for synthesizing vinyl acetate supporting palladium on alumina, and a catalyst for synthesizing ethylene oxide supporting silver on alumina. The prepared catalyst is usually produced by an impregnation method. These catalysts contain various co-catalysts in addition to noble metals, but when these catalysts are industrially produced by the impregnation method, it is necessary to uniformly support the catalytically active component on the carrier to improve the catalytic performance. It is an important requirement to improve. The method of the present invention can be applied to the production of these catalysts, in particular to the production of ethylene oxide synthesis catalysts, to produce high performance catalysts.

[0003]

2. Description of the Related Art Little is known about a method for producing a catalyst using ultrasonic waves.
Japanese Patent No. 57126 discloses a method for catalytically decomposing nitrogen oxides using an iron-containing Y-type zeolite catalyst, and states that it is effective to use ultrasonic waves when catalytically treating Y-type zeolite with an aqueous iron salt solution. Has been.

Further, Japanese Patent Laid-Open No. 1-227360 discloses a catalyst for a fuel cell in which platinum fine particles are supported on a catalyst carrier, and ultrasonic waves are used to mix and disperse the catalyst carrier and chloroplatinic acid well. Is used.

Further, Japanese Patent Application Laid-Open No. 63-28706 discloses a propylene polymerization method using a catalyst in which titanium halide is supported on a specific carrier. Ultrasound is used when reacting with a Grignard reagent to produce a specific carrier.

However, regarding the ultrasonic treatment when the catalytically active component is loaded on a carrier such as alumina, silica, silica-alumina, or activated carbon by the impregnation method, including the example of the catalyst for synthesizing ethylene oxide, up to now. unknown.

[0007]

The catalyst for synthesizing ethylene oxide is an α-alumina carrier carrying silver and other promoters. It is difficult to uniformly load these active ingredients on the carrier, and therefore the catalytic performance is not yet sufficient. In addition, in the usual impregnation method, the component composition is limited because it is premised that the co-catalyst component to be supported is dissolved in an industrially usable solvent such as water.
An object of the present invention is to provide a novel method for producing a catalyst, which enables uniform loading of active ingredients and also loading of ingredients which are difficult to dissolve in a solvent.

[0008]

Means for Solving the Problems As a result of intensive studies to solve the above-mentioned problems, the present inventors have achieved high catalytic performance by applying ultrasonic treatment when impregnating an active ingredient. It was found that a catalyst was produced and the present invention was completed.

That is, the present invention provides a method for producing a catalyst by supporting a catalytically active component on a carrier by an impregnation method, wherein the impregnating liquid containing the catalytically active component is subjected to ultrasonic treatment. is there. Hereinafter, the method of the present invention will be specifically described.

(Catalyst and catalytically active component) As a catalyst to which the method of the present invention is applied, a catalyst produced by an impregnation method, for example, a catalyst in which a precious metal is supported on a carrier, specifically platinum on alumina is used. Examples include supported hydrocarbon reforming catalysts, catalysts for synthesizing vinyl acetate in which palladium is supported on alumina, and catalysts for synthesizing ethylene oxide in which silver is supported on alumina. Hereinafter, the method of the present invention will be described by taking an ethylene oxide synthesis catalyst as an example.

In the case of a catalyst for ethylene oxide synthesis, the catalyst is 5 to 50% by weight of silver, based on the total weight of the catalyst on the porous support.
Carry. In addition to silver, it also contains cesium in an amount of 50 to 10,000 ppm based on the total weight of the catalyst. Furthermore, as performance accelerators, bismuth, tin, tantalum, thallium,
An alkali metal such as molybdenum, tungsten, chromium, lithium, sodium, potassium or rubidium,
A metal promoter such as an alkaline earth metal such as magnesium, barium or calcium may be included in a promoting amount.

The silver compound used to form silver, which is the main component of the catalyst for synthesizing ethylene oxide, forms a complex with an amine in an aqueous solvent, and decomposes at a temperature of 500 ° C. or lower to produce silver. Those that precipitate are used. Examples thereof include silver oxide, silver nitrate, silver carbonate and silver acetate,
Examples include various silver carboxylates such as silver oxalate. Of these, silver oxalate is preferable. Examples of the amine as the complex-forming agent include pyridine, acetonitrile, ammonia, amines having 1 to 6 carbons, and the like. Among them, ammonia, pyridine, monoamines such as butylamine, alkanolamines such as ethanolamine, and polyamines such as ethylenediamine and 1,3-propanediamine are preferable.

The cesium compound used for the catalyst is, for example, nitrate, hydroxide, halide, carbonate,
Includes bicarbonates, oxalates, and carboxylates. The performance promoting component used in the catalyst is an element having a performance promoting action,
Any compound form can be used.

(Porous Carrier) A porous refractory material is used as the porous carrier. Examples of such a porous carrier include alumina, silicon carbide, titania, zirconia, magnesia and the like. It is preferable that the main component is α-alumina. There are various methods for impregnating the porous carrier with the compound as described above, but it is most practical to use the silver compound in the form of an aqueous solution with an amine.
However, it can also be used as an aqueous solution to which alcohol or the like is added.
The silver concentration in the impregnating solution is selected so that 5 to 50% by weight of silver is finally supported as a catalyst component.

(Ultrasonic treatment) The ultrasonic treatment is usually carried out on the impregnating solution containing the active ingredient for several minutes to several tens of minutes depending on the state of the active ingredient in the impregnating solution. If the active ingredient is precipitated in the impregnating solution, sonication is carried out until it becomes a homogeneous solution. These active ingredients can be freely selected regardless of selected element or compound form by using ultrasonic waves regardless of whether they are dissolved in a suitable solvent or not. That is, even if a component that does not dissolve in a suitable solvent such as water is present in the impregnating liquid as fine particles, it can be easily impregnated into the carrier by subjecting the impregnating liquid to ultrasonic treatment. It can be supported with high dispersion. The impregnating liquid after the treatment is introduced into the carrier. Out of this
Impregnation can be carried out by a method of immersing the carrier in the impregnating solution, a spraying method, or the like. Also, the ultrasonic treatment can be carried out with the carrier immersed in the impregnating liquid. The ultrasonic treatment can be performed by introducing a commercially available ultrasonic vibrator into the impregnating liquid. It is also possible to put a container containing the impregnating liquid in the ultrasonic vibration bath. The vibration frequency can be set to about 5 KHz to 800 KHz which is used in a commercially available device. Depending on the state of the impregnating liquid, it is possible to use frequencies outside this range.

The heat treatment after the (calcination) impregnation is carried out by selecting the temperature and time necessary for the silver to be deposited on the carrier, so that the silver is present on the carrier as uniformly as possible and in the form of fine particles. Most preferably, the conditions for precipitation are selected. In general, the heat treatment accelerates the agglomeration of the deposited silver particles as the heat treatment increases. A preferred heat treatment is 130 ° C to 3
Air (or an inert gas such as nitrogen) heated to 00 ° C. or heating steam is used for a short time of 5 to 30 minutes.

(Reaction conditions) The reaction of converting ethylene to ethylene oxide using the catalyst of the present invention can be carried out by a conventional operation. For example, the pressure is 1 to 35 kg / cm ² , and the temperature is 180 to 350 ° C, preferably 200 to 300 ° C. For the reaction, 1-40 vol% ethylene, 1-oxygen
At 20 vol% it is generally preferred to have a diluent, eg methane, present in a fixed proportion, eg 0-70 vol%. Oxygen can be supplied in the form of air or as industrial oxygen. The addition of ethylene dichloride, for example, as a reaction modifier can prevent the formation of hot spots in the catalyst and can greatly improve the performance of the catalyst, particularly the catalyst selectivity.

[0018]

EXAMPLES The present invention will now be described in more detail with reference to examples, but the present invention is not limited to these examples.

Example 1 228 g of silver nitrate (AgNO ₃ ) and potassium oxalate (K
₂ C ₂ O ₄ · H ₂ O) (135 g) was dissolved in 1 liter of water each, and then gradually mixed in an aqueous solution while heating at 60 ° C.,
A white precipitate of silver oxalate was obtained. After filtration, the precipitate was washed with distilled water to remove potassium in the precipitate. The silver oxalate thus obtained (AgC ₂ O ₄ .water content 19.47)
%) A part (12.3 g) of ethylenediamine 3.42
g, propanediamine 0.94 g and water 4.54 g were gradually dissolved in an amine mixed aqueous solution to prepare a silver amine complex solution. To this silver amine complex solution, 1 ml of cesium nitrate (3.78 g wt% Cs) was added with stirring. Then, 1 ml of an aqueous solution of oxychlorobismuth (BiOCl) (2.37 wt% Bi) was added. An ultrasonic oscillator was placed in this impregnating solution, and ultrasonic waves of 20 KHz were applied for 10 minutes. This ultrasonically treated impregnating liquid was used as an α-alumina carrier (BET specific surface area 1.02 m ² / g, water absorption 3
4.54%, average pore diameter 1.9 μm, silica 3%, 8φ
X3φ × 8 mm ring-shaped) (50 g) and impregnated at room temperature under reduced pressure in an evaporator. Add this impregnated carrier to 25
A catalyst was prepared by heating with heated steam at 0 ° C. for 15 minutes at a flow rate of 2 m / sec. The loading rates of Ag, Cs, and Bi were 12%, 665 ppm, and 418 ppm, respectively.
The catalyst prepared by the above method is crushed into 6 to 10 mesh,
3 ml thereof was filled in a SUS reaction tube having an inner diameter of 7.5 mm, and a reaction gas (ethylene 30%, oxygen 8.5%, vinyl chloride 1.5 ppm, carbon dioxide 6.0%, residual nitrogen).
Was allowed to flow at GHSV4300h ⁻¹ and a pressure of 7 kg / cm ² G for reaction. Oxygen conversion is 4 after 1 week
Table 1 shows the reaction temperature T ₄₀ (° C., bath temperature) at 0% and the ethylene-based ethylene oxide selectivity S ₄₀ (%) at an oxygen conversion rate of 40%.

Comparative Example 1 A catalyst was prepared in the same manner as in Example 1 except that ultrasonic treatment was not performed. The reaction results are shown in Table 1.

Example 1 Instead of oxychlorobismuth, an aqueous solution of tin sulfate (1.
A catalyst was prepared in the same manner as in Example 1 except that 1 ml of 34 wt% Sn) was added. The reaction results are shown in Table 1.

Comparative Example 2 A catalyst was prepared in the same manner as in Example 2 except that ultrasonic treatment was not performed. The reaction results are shown in Table 1.

Example 3 A catalyst was prepared in the same manner as in Example 1 except that 1 ml of an aqueous potassium fluorotantalate solution (2.05% by weight Ta) was added instead of oxychlorobismuth. Table 1 shows the reaction results
Shown in.

Comparative Example 3 A catalyst was prepared in the same manner as in Example 3 except that ultrasonic treatment was not performed. The reaction results are shown in Table 1.

Example 4 A catalyst similar to that of Example 1 was prepared except that 1 ml of an aqueous thallium nitrate solution (2.32% by weight Tl) was added instead of oxychlorobismuth. The reaction results are shown in Table 1.

Comparative Example 4 A catalyst was prepared in the same manner as in Example 4 except that ultrasonic treatment was not performed. The reaction results are shown in Table 1.

[0027] Example 5 Instead para Moribun den of ammonium oxy-chloro bismuth _{(NH 4) 6 Mo 7 O} 24 · 4H 2 O aqueous solution (1.
A catalyst similar to that of Example 1 was prepared except that 1 ml of (09 wt% Mo) was added. The reaction results are shown in Table 1.

Comparative Example 5 A catalyst was prepared in the same manner as in Example 5 except that ultrasonic treatment was not performed. The reaction results are shown in Table 1.

[0029]

[Table 1]

[0030]

According to the method of the present invention, a catalyst active component can be uniformly loaded on a carrier in the production of a catalyst by an impregnation method, and a catalyst having improved activity and selectivity can be obtained.

Claims (2)

[Claims] 1. A method for producing a catalyst by supporting a catalyst active component on a carrier by an impregnation method, wherein the impregnating liquid containing the catalyst active component is subjected to ultrasonic treatment. 2. The production method according to claim 1, wherein the catalyst is a catalyst for synthesizing ethylene oxide.