JPS5823139B2 - Method for producing catalysts supported on carrier systems - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention aims to uniformly and gradually increase the hydroxyl ion concentration of an aqueous solution of a salt of a catalytically active element in which a fine carrier material is suspended by hydrolyzing a hydroxyl ion-forming compound while stirring. After precipitating the insoluble compound of the catalytically active element onto the support material, the support loaded with the active element is separated from the liquid, washed, dried and, if necessary, calcined and/or reduced. It also relates to a method for producing a catalyst supported on a carrier system, which comprises carrying out the washing and drying as quickly as possible and at the lowest possible temperature.

It is well known that excellent catalysts can be obtained by depositing catalytically active metal ions from a homogeneous solution onto a support material suspended in this solution.

This precipitation is carried out by uniformly and gradually increasing the hydroxyl ion concentration of the solution/suspension.

In this case, metal ions are precipitated as hydroxides or hydrous oxides.

If necessary, the hydroxides or hydrous oxides can be converted to the corresponding oxides by calcination, or these compounds can be converted to the corresponding metals by reduction.

One of the most suitable methods for increasing the hydroxyl ion concentration uniformly and gradually is, for example, West German Patent No. 1767200.
However, the use of urea has problems with certain metal ions.

This problem is mainly due to the fact that the rate of hydrolysis of urea is not suitable for industrial use up to about 90°C.

At this temperature, the metal ions that precipitate often react with the support material.

This is notable for the often used silica supports.

As a result of this reaction, depending on the metal ion loading, all or part of the support is converted to the hydrosilicate of the metal in question.

It is difficult to convert metal ions in hydrosilicates into metal particles by reduction.

For this purpose, the reduction must be carried out at a temperature of, for example, 500°C.

When metal particles are formed from hydrosilicate, the size of the metal particles is set to 50 to 100 particles in order to achieve an industrially desirable filling rate of 50 particles by weight or more.

Typically, strict requirements are placed on the pore structure of heterogeneous catalysts.

The catalytically active surface must be accessible to the reactants.

On the other hand, reaction products must be recovered quickly.

The pore structure of support materials such as silica, alumina, etc. can be adjusted to a considerable extent.

It goes without saying that this structure must not be damaged when filled with catalytically active components.

It cannot be avoided that the use of urea and the high loading factor have a large effect on the pore structure of the large number of ions.

These drawbacks are also recognized in Dutch Patent No. 6917618.

It is therefore proposed to carry out the precipitation at 10 DEG to 50 DEG C., especially at room temperature.

In order to increase the pM value of the solution/suspension, an organic base that is substantially insoluble in the solution of the metal salt is utilized.

Examples of suitable organic bases include n-octylamine and n-occudecylamine and related compounds.

In order to increase the contact area between two types of immiscible liquids,
Large amounts of mechanical energy are required.

Furthermore, the above organic bases are relatively expensive.

Also, an emulsion is formed. It is therefore difficult to separate the carrier filled with catalytically active components from the liquid.

Therefore, it becomes necessary to add an organic solvent such as benzene or chloroform.

The object of the present invention is to provide the above-mentioned method for producing a catalyst supported on a catalyst system by (a) forming metal particles of 100λ or less in reducing a carrier filled with a catalytically active component;
b) retaining the pore structure of the FFEI material, i.e., suppressing the formation of metal hydrosilicates as much as possible); be.

According to the invention, this can be achieved by hydrolysis of cyanate ions to form hydroxyl ions at temperatures between 20 and 50°C.

Hydrolysis proceeds according to the reaction formula below.

3H20+CNO-+NH4+C02+20H The rate of this reaction can be reliably measured at temperatures of approximately 2.5<0>C, but for industrial applications it is preferred to utilize temperatures between 35 and 40<0>C.

Preferably, alkali cyanate or ammonium cyanate is utilized.

The starting amount of cyanate should be at least stoichiometric.

The precipitation process is completed more quickly if an excess amount of cyanate is used, for example 10 times the amount of cyanate.

Using 2 to 4 times the amount of cyanate is sufficient to achieve rapid and complete precipitation.

If fine, highly porous silica is used as a carrier,
The process of the invention is particularly useful for producing catalysts whose catalytically active components consist of at least one or more of the elements nickel, cobalt, iron and copper.

This also applies if the active substance consists of a combination of the above-mentioned elemental metals or a combination thereof with other metals.

Of course, other carrier materials such as A1□03+T i02 may also be used.

The novel catalyst can exhibit its advantages not only when the catalytically active component is present as a metal, but also when the corresponding metal oxide is the catalytic activator.

This is because no metal hydrosilicate is formed in either case.

In the case of the catalysts prepared according to the invention, calcination at low temperatures below 500° C. yields the desired metal oxides, but up to 90° C. to decompose the corresponding hydrosilicates.
A temperature of 0'C is required.

The catalytically active metal ions can be introduced into the solution as nitrates, hydrochlorides or sulfates or other highly soluble compounds.

Also, soluble cyanates of the metals can be used.

The concentration of metal ions depends on the desired loading of the carrier material.

In order to increase the filling rate, the solution may contain, for example, 15 parts by weight of metal ions.

The process of the invention can be carried out by charging the required ingredients to water at a temperature below 20°C.

After homogenizing the solution/suspension, the temperature is raised to initiate the reaction.

In this way, the method according to the invention can be adjusted very reliably.

According to the invention, after filling the carrier material, it must be separated from the residual liquid, washed and dried as quickly as possible to suppress the formation of metal hydrosilicates.

Furthermore, even at temperatures below 50°C, the above-mentioned hydrosilicate is formed due to the presence of water, although very slowly.

For the same reason, support materials loaded with catalytically active components must be dried at the lowest possible temperature.

Therefore, it is preferable to carry out drying under reduced pressure.

The present invention will be explained below with reference to Examples, but the present invention is not limited thereto.

Ni, (NO3)2.66H2O37 and KCNO20 to make nickel catalyst on silica
g was dissolved in 900 ml of distilled water at a temperature of 15°C.

Next, 7.64 g of silica (trade name: AERO8IL 380V) having a surface area of about 4 ooms and 27 g was suspended in the resulting solution.

The temperature of the homogeneous solution/suspension was then adjusted to 37° C. with constant stirring.

The changes in pH value of the solution are shown in the attached drawing.

In this drawing, the horizontal axis represents time (minutes), and the vertical axis represents the p of the solution.
Represents H value.

Curve 1 shows the change in pH value over time at a working temperature of 37°C.

After 10 minutes, precipitation started at a pH value of 6.3 (measured by light scattering method).

After about 90 minutes, all the nickel was deposited on the support.

This was determined because the filtered sample of the solution contained no nickel.

The support material loaded with catalytically active components was then immediately filtered off and washed.

Filtration and washing took approximately 15 minutes.

The residue was then loaded into a vacuum dryer. After 3 hours the temperature was increased to 40°C and after 6 hours it was adjusted to 120°C.

The same experiment was repeated without adding silica.

Curve 2 in the accompanying drawing shows the change in pH value.

Precipitation started at a pH value of 6.45.

The fact that precipitation occurred at higher pH values indicates that the solubility of the nickel hydroxide formed in the first experiment was low due to interaction with the carrier material, and therefore precipitation occurred only on the carrier material.

The pore distribution of the dry support material loaded with the catalytically active components was determined by capillary condensation of nitrogen.

The carrier material contained only micropores (size 20 pores).

After reduction at 350° C. for 48 hours in a stream of hydrogen gas, the catalyst contained approximately 20 nickel metal particles in size as determined by electron microscopy.

Catalysts prepared in a similar manner, except that the precipitation with urea was carried out at 90°C, had grooved pores of size 30-400 (
5 lotted pores).

was.

Electron microscopy revealed that the support had been completely converted into plate-like nickel-hydrosilicate crystallites.

Reduction of this catalyst required a temperature of 500°C.

The size of the nickel particles was approximately 60.

In another embodiment, the same carrier material was loaded with an equal amount of nickel according to the method of the invention.

However, after the precipitation was completed, the suspension was maintained at 37° C. for 20 hours.

The acid solubility of the support material loaded with the catalytically active components indicated that a significant amount of nickel hydrosilicate had formed.

[Brief explanation of the drawing]

The accompanying drawing is a graph showing the change in pH value.

Claims (1)

[Scope of Claims] 1. The hydroxyl ion concentration of an aqueous solution of a salt of a catalytically active element in which a fine carrier material is suspended is uniformly and gradually increased with stirring by hydrolysis of the hydroxyl ion product, thereby increasing the hydroxyl ion concentration of the catalytically active element. After the insoluble compounds have been deposited on the support material, the element-loaded support is separated from the liquid, washed, dried and, if necessary, calcined and/or reduced, with the washing and drying being carried out as much as possible. A process for producing catalysts supported on support systems, which consists in carrying out rapidly and at the lowest possible temperature, homogeneously and gradually forming hydroxyl ions by hydrolysis of cyanate ions at temperatures between 20 and 50 °C. A method for producing a catalyst supported on a carrier system, characterized in that the precipitation is carried out by: 2. The method according to claim 1, characterized in that the precipitation is carried out at a temperature of 30 to 40°C. 3 Claims 1 to 2 characterized in that alkali cyanate or ammonium cyanate is used.
The method described in any one of the paragraphs. 4. Claims 1 to 3, characterized in that cyanate is used in an amount of 1 to 10 times the amount of metal ions.
The method described in any one of the paragraphs. 5. A method according to any one of claims 1 to 4, characterized in that 52 to 4 times the amount of cyanate is used. 6. Scope 1 of the patent, characterized in that the support material is fine, highly porous silica, and the catalytically active component consists of at least one or more of the elements nickel, cobalt, iron and copper as a metal or oxide. The method described in any one of Items 1 to 5. 7. The method according to any one of claims 1 to 6, wherein the catalytically active component is a metal oxide, the washing being filled with the metal oxide as the catalytically active component;
The above method, characterized in that the dry carrier is calcined at 200-500°C. 8. A method according to any one of claims 1 to 7, characterized in that the solution contains up to 15 parts by weight of metal ions. 9. A method according to any one of claims 1 to 8, characterized in that the metal ions are present in the form of soluble nitrates, soluble hydrochlorides or soluble sulfates. 10. Process according to any one of claims 1 to 9, characterized in that the metal ions are present in the form of soluble metal cyanate. 11. Any one of claims 1 to 10, characterized in that the reactant and the carrier material are introduced into water at a temperature below 20°C, and the temperature is raised after homogenization of the solution/suspension. The method described in section. 12. Process according to any one of claims 1 to 11, characterized in that the carrier material loaded with the catalytically active component is dried under reduced pressure.