JP3293846B2 - Method for producing spherical Raney alloy for catalyst - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a spherical Raney alloy for a catalyst and a method for producing a Raney catalyst by expanding the obtained spherical Raney alloy. The present invention relates to a method for producing a catalyst suitably used for a fluidized bed reaction.

[0002]

2. Description of the Related Art Conventionally, Raney catalysts have been widely used as powder catalysts for reduction. However, generally, an alloy powder is produced by a pulverizing method for pulverizing an ingot of a Raney alloy and an atomizing method, and these are made of an alkaline solution. It is developed and developed.

[0003] However, the pulverization method is slightly different depending on the pulverization means, but generally the particle size distribution of the pulverized particles is wide,
A large amount of fine powder is also formed. Fines are a significant disadvantage in the activation process, as they can be bothersome and lost in fluidized beds. Therefore, sieving is usually carried out to obtain the desired particle size range, but not only takes time but also the yield is low, and since the individual powder particles are irregularly shaped, the Raney-catalyst is used. Is not always satisfactory. In particular, it is substantially difficult to apply the pulverization method to alloys having ductility.

[0004] For example, the Raney alloy particles formed by the atomizing method as disclosed in Japanese Patent Application Laid-Open No. 2-126940 have a somewhat controlled particle size and particle size distribution as compared with the pulverizing method. However, it is an irregularly-shaped curved body in which a sphere is crushed or elongated, and the particle diameter spread is still considerably large. In particular, a narrow particle size range, such as poor sedimentation as a Raney catalyst for fluidized bed reactions and the like, which easily causes troubles such as clogging of transport piping due to uneven distribution of catalyst particles, and often requires sieving. It is required that the particles be adjusted to be as spherical as possible.

[0005]

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a method for forming Raney alloy particles which are controlled to a desired narrow particle size range without the need for sieving. Another object of the present invention is to provide a catalyst alloy particle having a substantially spherical shape and a catalyst which is highly desirable for a fluidized bed reaction by development.

[0006]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors have repeatedly studied various technical factors regarding a method for directly pulverizing a Raney alloy for a catalyst. It has been found that spheroidization using is preferred, and practically extremely desirable results can be obtained, leading to the present invention.

That is, according to the present invention, a melt of an alloy containing a catalytically active metal containing aluminum or silicon is dropped on the upper surface of a disk of a high-speed rotating body and scattered by centrifugal force to form fine droplets in an inert gas atmosphere. A method for producing a controlled catalyst-shaped spherical Raney alloy having a particle size characterized by being cooled and solidified in a medium, and a method for producing a Raney catalyst suitable particularly for a fluidized bed reaction by developing the same. It is a proposal.

[0008] The catalyst alloy according to the method of the present invention comprises:
Alloys comprising a catalytically active metal or, if necessary, a small amount of a promoter metal containing aluminum or silicon which are eluted during development. Representative examples of the catalytically active metal constituting the alloy include metals having catalytic ability, for example, metals such as nickel, cobalt, iron, copper, silver, ruthenium, and palladium.
Examples of the promoter metal include chromium, iron, molybdenum, tungsten, and tin. These catalyst metal and cocatalyst metal are preferably contained in proportions of 30 to 60% by weight and 0 to 10% by weight, respectively, based on the alloy, and the remainder is aluminum or silicon which is developed and eluted.

As the above-mentioned catalytic metals, one or more metals having catalytic activity according to the intended organic chemical reaction or the like are selected. It is not preferable because the strength of the powdery and granular porous catalyst formed by the above becomes insufficient, and if it exceeds 60% by weight, the surface area of the porous material as the catalyst becomes insufficient and the catalytic activity is reduced, which is inappropriate. The promoter metal is usually a metal component that promotes the catalytic activity of the catalyst metal. Generally, a small amount of about 10% by weight or less of the catalyst metal is preferably used. Further, aluminum or silicon constituting the remainder of the alloy is used to form a porous body of a catalytic metal having a large surface area and particle strength by expanding the aluminum or silicon. Usually, the alloy particles are treated with an alkali solution. It is a component that is dissolved and removed as a result. Its content is on the order of about 30-70% by weight based on the alloy.

In the method of the present invention, a desired amount of the selected catalytically active metal, cocatalyst metal and eluting metal is mixed, heated and melted, and the melt is rotated at a high speed. It is dripped on the upper surface of the body. Usually, the melt of the alloy is heated and held in a temperature range higher by about 50 to 150 ° C. than its melting point. If the temperature is too low, the melt may solidify before centrifugal scattering, which is disadvantageous.If the temperature is too high, the centrifugally scattered melt droplets cannot be cooled and solidified during the fall, and the inner wall of the chamber cannot be cooled. It is not preferable because it collides with and deforms.

[0011] In order to form such Raney alloy particles according to the present invention, it is important to rotate the disk at a high speed in order to scatter such a liquid mixture by centrifugation. The rotation speed is
It is selected depending on the viscosity of the melt or the like and the desired fine particle diameter of 200 μm or less, for example, about 10,000 to 50,000 revolutions per minute (rpm). Is practically included. When the molten alloy liquid is dropped little by little, for example, from 2 cm to 20 cm above the horizontal circular upper surface of the rotating body rotating at such a high speed, the control corresponding to the melt viscosity and the rotating speed in each case is performed. The particles of a narrow size range are centrifugally scattered. The particle size decreases as the viscosity of the melt decreases and as the rotation speed of the rotating body increases, and these conditions are selected and controlled as appropriate according to the desired particle size to be prepared.

The disk-shaped rotating body used in the method of the present invention is not particularly limited as long as it is a material having sufficient heat resistance to the temperature of the molten alloy, but has a heat-resistant temperature higher than the melting points of various alloys. Materials with good wear resistance, for example ceramics such as titanium nitride, boron nitride, silicon carbide and tungsten carbide, are advantageously used. In addition, the particle size of the spherical fine-grained alloy depends not only on the operating conditions, but also on the roughness of the surface of the disk-shaped rotating body, the sharpness of the peripheral edge, the edge angle, and the like.
In order to obtain a material having a narrow particle size range, it is desirable that the surface of the disk-shaped rotating body is polished with, for example, diamond abrasive grains to reduce the roughness to Rmax 1 μm or less. The angle is desirably selected according to the desired average particle size range. The conditions of the disk-shaped rotator can be easily selected and determined by a simple experiment or the like.

[0013] The method of the present invention is typically operated in a closed chamber, as the centrifuged liquid is scattered, and the solidified particles are collected at the bottom of the chamber. At this time, it is extremely important that the fine-grained molten liquid be cooled and solidified before coming into contact with the chamber wall, and for the cooling, an inert gas controlled to a moderately low temperature is continuously introduced into the chamber. Is blown in. Such inert gases include, for example, nitrogen, argon or helium. In the method of the present invention, these inert gases may be used alone, but it is practically desirable to select two or more kinds of the inert gases and to utilize the thermal conductivity of the mixed gas in a favorable manner to select cooling conditions.

The method of the present invention will be described with reference to the drawings. FIG.
FIG. 1 is a schematic cross-sectional view for explaining an example of an apparatus for producing spherical Raney alloy particles by the method of the present invention. Cover of a large chamber 1 having an inverted conical shape in which the upper part is covered in a dome shape.
At the center of the part, a holding furnace 2 equipped with a heating mechanism is mounted so as to penetrate through the cover wall.
Is held. A high-speed rotating disk 5 which is driven to rotate by a motor 6 is arranged at the upper center in the chamber-1. The melt 3 in the holding furnace is continuously dropped onto a central part of a disk 5 rotating at a high speed from a molten droplet preparation hole 4 formed in the center of the bottom of the furnace. The melt that has fallen into contact with the surface of the high-speed rotating disk is repelled to the outer periphery by the centrifugal force of the disk to form fine spherical droplets.

A circulating fan 7 rotated by a motor 6 'and a cylindrical gas guide plate 8 arranged so as to surround the circulating fan 7 are installed in a substantially central portion of the chamber 1 in a vertical direction. An inert gas controlled to a predetermined temperature is continuously introduced from a cooling gas introduction port 9 provided at an appropriate position on the chamber wall. The introduced gas descends on the wall side of the chamber, rises in the guide plate 8 by the circulation fan 7, and provides a stable cooling gas flow toward the disk 5 rotating at a high speed. The fine spherical alloy droplets thus flicked to the outer periphery solidify before falling into contact with the inclined wall of the chamber and fall along the inclined wall, and fall down along the inclined wall.
And is continuously taken out from the spherical particle outlet 10. In addition, the inert gas continuously introduced from the gas inlet 9 is continuously extracted from the spherical particle outlet 10, for example.

[0016]

According to the method of the present invention, a fine spherical alloy having a uniform and fine structure free from the possibility of oxidative modification and having no segregation can be obtained effectively. When developing the obtained spherical alloy, a porous body having a controlled particle size in a narrow range and a large specific surface area is easily formed,
A Raney catalyst having excellent catalytic activity and suitable for a fluidized bed is prepared.

[0017]

Next, the method of the present invention will be described in more detail with reference to specific examples.
This will be described in detail. Example 1Production of copper-aluminum spherical alloy  Dome-shaped camera as shown in Fig. 1 having an inner diameter of 3000mm
Using an inverted conical chamber device with a bar, copper and aluminum
Minium 100kg each alloy 50% by weight in a holding furnace
The melt heated and held at a temperature of about 650 ° C is passed through the lower hole of the melt droplet.
A bolus with a diameter of 50 mm provided in the chamber about 5 cm below
At the center of the top surface of a high-speed rotating disk made of
Was dripped. The rotation speed of the disk is about 30,000 rpm,
The inside of the chamber is filled with nitrogen gas for coagulation at 0.
It is kept under a pressure of 1 kg and its temperature is about 50 ° C.
Was. In this case, the dwell time of each particle is about 0.5 seconds.
Was.

The Raney alloy particles removed from the bottom of the chamber are all substantially spherical and their particle size is highly desirable, controlled within the range of about 20-100 μm. FIG. 2 shows the Raney obtained in this example.
FIG. 3 is a scanning electron micrograph showing the particle structure of the alloy powder, and FIG. 3 shows the particle size distribution (hereinafter, simply referred to as particle size distribution) by centrifugal sedimentation, which is included in each particle size range and each range. 5 is a bar graph showing the relationship with the weight% of alloy particles. FIGS. 4 (a) and 4 (b) show powders obtained by manufacturing an alloy having the same composition as in Example 1 by a pulverizing method and an atomizing method, which are typical methods for manufacturing conventional Raney-alloy powder, respectively. FIG. 5 (a) is a micrograph similar to FIG.
Figures and (b) are bar graphs of the same particle size distribution of each powder as in Figure 3.

EXAMPLE 2 40 g of the copper-aluminum Raney-alloy spherical particles obtained in Example 1 were used in an amount of 240 m of a 25% by weight aqueous sodium hydroxide solution.
The aluminum was eluted over about 1.5 hours while mixing under a heating condition of 55 ° C., and after being substantially completely developed, sufficiently washed with water to obtain about 20 g of a copper catalyst.

Embodiment 3Manufacture of nickel-aluminum based spherical alloy  Nickel 485g, Molybdenum 15g and Aluminum 500g
Is heated and melted at a temperature of about 1450 ° C in a holding furnace.
Then, the melt was centrifuged and dispersed as in Example 1, and
Alloy spherical particles were produced. Scanning electron microscope of the obtained particles
Micrographs and bar graphs of the particle size distribution are shown in FIGS. 6 and 7.
Show.

Embodiment 4Production of silver-aluminum spherical alloy  A melt of 2.5 kg of silver and 2.5 kg of aluminum was used as in Example 1.
Centrifugally scatter in the same manner to prepare Raney-alloy spherical particles.
Was. Scanning electron micrograph of the obtained particles and their particle size
An overview bar graph of the distribution is shown in FIGS. Silver-aluminum
Nitride alloys have ductility, so conventional pulverization methods require
Although termination was extremely difficult, according to the method of the present invention,
Spherical particles with a controlled particle size can be obtained easily and effectively.
You.

As is clear from the above micrographs and bar graphs, the Raney alloy produced by the method of the present invention is a true spherical particle whose particle size is controlled, whereas the conventional Raney alloy is a typical spherical particle. The alloy powder prepared by the pulverizing method or the atomizing method is extremely non-uniform in shape and has a wide particle size distribution, and particularly contains a large amount of fine powder which is inconvenient in the preparation and use of the catalyst, for example, fine particles of less than 10 μm. It turns out that it is extremely disadvantageous in practical use.

Example 5 The following various tests were carried out on the above copper catalyst prepared by the method of the present invention and the same copper catalyst prepared by the conventional pulverizing method and atomizing method, and the properties of each catalyst were evaluated. [Catalytic activity test] Raney-copper catalyst 7.0 previously deoxygenated
g, deoxygenated water 63.0 g and acrylonitrile 10.0 g
Then, after completely deoxidizing the inside of the flask, the temperature is increased, and the reaction is carried out under stirring conditions for 2 hours while maintaining the content at 70 ° C. After the reaction, the amount of acrylamide produced was measured, and the amount produced (g) per gram of copper was indicated as a catalytic activity value. The higher the value of the catalytic activity, the better the catalytic activity.

[Catalyst particle size distribution] The particle size of the catalyst was measured by a centrifugal sedimentation method, and the particle size distribution was displayed as a bar graph. In this particle size distribution, the finer particles have larger surface area and higher catalytic activity, but the smaller the number of fine particles less than 10 μm, the better the operability.

[Precipitation of Catalyst Particles] 5 g of a catalyst was placed in a 50 ml graduated cylinder equipped with a stopper, and the volume was adjusted to 50 ml with water. The sedimentation distance for time (seconds) was measured and defined as the sedimentation velocity. The higher the sedimentation speed, the better, and the smaller the decrease in speed after each use, the better industrially.

The results of these evaluation tests are summarized in Table 1 below. In the particle size distribution, the particle sizes before and after the activity test were measured and shown in comparison.

[0027]

[Table 1]

As is clear from the above table, the spherical Raney catalyst produced and provided by the method of the present invention has a particle size of 10 μm compared to the conventional Raney catalyst obtained by the conventional pulverization method and the atomization method. It has the advantage that the amount of finely divided particles is extremely small and the sedimentation speed is extremely high. In addition, the spherical Raney alloy catalyst according to the present invention has a large particle size and a small surface area as compared with conventional ones, but is controlled mainly in a particle size range of 20 to 50 μm.
It has excellent practicality and operability, showing a much higher catalytic activity value than conventional products, and is remarkably improved as an organic chemical reduction catalyst over conventionally known Raney alloy catalysts. It can be understood that the catalyst has the same catalytic activity.

[0029]

According to the method of the present invention, it is possible to effectively obtain a catalytic alloy having a substantially spherical shape and a dense structure in which the diameter of the spherical particles is controlled to a high degree. The Raney catalyst obtained by developing this is particularly desirable for a fluidized bed, and therefore, the industrial utility of the present invention is extremely high.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view for explaining an example of an apparatus showing an embodiment of a method of the present invention.

FIG. 2 is an electron micrograph showing the particle structure of the Raney-copper alloy obtained in Example 1.

FIG. 3 is a bar graph of the particle size distribution (each particle size range and the weight% of alloy particles included in each range) of the Raney-copper alloy obtained in Example 1.

4 (a) and 4 (b) are micrographs similar to FIG. 2 of a Raney-copper alloy powder produced by a conventional pulverizing method and an atomizing method.

5 (a) and 5 (b) are bar graphs of the particle size distribution of each powder.

FIG. 6 is an electron micrograph showing the particle structure of a Raney-nickel alloy obtained in Example 3.

FIG. 7 is a bar graph of the particle size distribution of the Raney-nickel alloy obtained in Example 3.

FIG. 8 is an electron micrograph showing the particle structure of the Raney-silver alloy powder obtained in Example 4.

FIG. 9 is a bar graph of the particle size distribution of the Raney-Silver alloy obtained in Example 4.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Chamber 2 ... Holding furnace 3 ... Synthetic liquid 4 ... Melt droplet lower hole 5 ... Disk 6, 6 '... Motor 7 ... Circulation fan 8. ..Guide plate 9 ... Gas inlet 10 ... Spherical particle outlet

──────────────────────────────────────────────────続 き Continued on the front page (72) Minoru Nagasawa 1177-1 Kamiochiai, Yono-shi, Saitama Prefecture Twinell 2-405 (72) Inventor Katsunori Iwatani 1913-183, Daiza-Kotsumi, Sowa-cho, Sarushima-gun, Ibaraki Prefecture (56) References JP-A-4-169561 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B01J 21/00-37/36 B22F 9/10

Claims (3)

(57) [Claims] 1. A melt of an alloy in which aluminum or silicon is contained in a catalytically active metal is melted from the melting point of the alloy.
At a high temperature of 50 to 150 ° C, place it in the upper center of the chamber.
Drops from 2 to 20 cm above the placed disk onto the top surface of the rotating disk at high speed, and the rotating centrifugal force causes the outer periphery of the disk
Is scattered to the side, the fine droplets that scatter of particle size, characterized in that to cool solidify in an inert gas atmosphere control - Le catalyst for spherical Raney - manufacturing method of the alloy. 2. A cylindrical guide plate is mounted vertically below the disk in the chamber, and the inert gas is raised by a circulating fan disposed inside the disk, thereby stabilizing the disk toward a high-speed rotating disk. The method for producing a spherical Raney alloy for a catalyst according to claim 1, wherein a cooling gas flow is provided. 3. The alloy according to claim 1, wherein the alloy is nickel, cobalt, iron, copper,
30-60% by weight of at least one catalytically active metal selected from the group consisting of silver and ruthenium and 0-10% by weight of at least one promoter metal selected from the group consisting of chromium, iron, molybdenum, tungsten and tin 2. The method for producing a spherical Raney alloy for a catalyst according to claim 1, wherein the balance comprises aluminum or silicon.