JP3365660B2 - Impregnation liquid for producing ruthenium catalyst and method for producing ruthenium catalyst - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an impregnating solution for producing a ruthenium catalyst. More specifically, it can support a ruthenium component on a catalyst carrier in a highly dispersed state and with good thermal stability by a very simple operation. The present invention relates to an impregnating liquid for producing a ruthenium catalyst.

The present invention also relates to a method for producing a ruthenium catalyst, and more specifically, it exhibits high activity and high selectivity in various reactions and has a high activity per contained ruthenium and is suitable for use as an industrial catalyst. The present invention relates to a method for efficiently producing various high-performance supported ruthenium-based catalysts that can be produced by a simple operation by using the impregnating liquid of the present invention.

[0003]

Ruthenium is used in, for example, hydrogenation of unsaturated compounds such as carbonyl compounds and aromatic compounds, ammonia synthesis, reduction of nitrogen compounds, steam reforming of hydrocarbons, Fischer-Tropsch synthesis (FT synthesis) and the like. It becomes an effective catalyst or catalyst component for various reactions.
It is known to show higher activity and higher selectivity than base metals such as nickel and cobalt or, in some cases, other noble metals such as platinum and palladium. However, since ruthenium is expensive, it is rarely used industrially, although it has better activity and selectivity than many metals such as iron, nickel, and cobalt. Therefore, in order to obtain a practical ruthenium-based catalyst with sufficiently high activity and no problems in terms of cost, the ruthenium component should be supported as effectively as possible in a highly dispersed state as a suitable carrier, and the activity per contained ruthenium is greatly improved. Is required to be made. In addition, it is often practically important to carry well so that the highly dispersed state can be stably maintained even when firing, pretreatment, reaction, regeneration and the like are performed at high temperature as well as at low temperature.

However, it is generally difficult to support ruthenium in a sufficiently highly dispersed state by the conventional general-purpose catalyst preparation method. On the other hand, a special ruthenium compound is used as a raw material or a special preparation method is used. Although a technique for improving the dispersibility of ruthenium has also been proposed, in these cases, the raw material ruthenium compound itself is expensive, or the dispersion stability is poor, and particularly agglomeration occurs at high temperature, or, There are various problems such as complicated preparation operation, and it is not practical.

[0005] For example, ruthenium chloride is the cheapest of various ruthenium compounds, is easily available, and exhibits water solubility. Therefore, ruthenium chloride is used as a raw material for preparing a supported ruthenium catalyst.
Most commonly used. However, the aqueous solution
The stability is poor in the presence of basic hydroxyl groups, and ruthenium hydroxide can be obtained by impregnating and supporting by contacting with a carrier that generates or releases basic hydroxyl groups in the presence of water such as alumina, magnesia, and zinc oxide. Since a black precipitate is generated, ruthenium is aggregated, which makes it difficult to support ruthenium in a highly dispersed state. Further, even in the case of a general carrier, when the pH of the liquid increases due to the action of other coexisting components and additives, the change of the composition of the impregnating liquid during preparation, and the like, the same problem occurs.

Therefore, in order to improve the dispersibility of ruthenium, various techniques using special raw materials and preparation means have been proposed.

For example, Japanese Unexamined Patent Publication No. 50-14594 discloses a catalyst preparation method using a ruthenium chelate compound. However, in this method, since the chelate compound is expensive, there is a limit to the reduction of the catalyst cost in the end, and in general, the chelate complex structure is destroyed at a high temperature of 400 ° C. or higher, so that the dispersibility of ruthenium at high temperature is high. Is difficult to maintain.

[0008] In addition, a method of adding an acid such as hydrochloric acid to an aqueous solution of a general-purpose ruthenium compound such as ruthenium chloride to suppress an increase in pH and suppress the formation of a precipitate such as ruthenium hydroxide, or is relatively stable even in the basic condition. A method using an aqueous solution of a simple ammine complex salt is also often used. However, also in these cases, the dispersion stability of the ruthenium component after loading is poor, and the aggregation of ruthenium in a high temperature atmosphere is significant.

That is, as described above, according to the conventional method of simply using a specific ruthenium compound such as a chelate compound or an ammine complex salt or adjusting the pH by adding an acid, ruthenium is supported at low temperature with good dispersibility. Even if it is possible, ruthenium will eventually aggregate if it is subjected to pretreatment such as calcination with air or the like, hydrogen reduction or the like, used for reaction, or regenerated at high temperature.

Further, Japanese Patent Laid-Open No. 2-71849 discloses that
A method of obtaining a highly dispersed ruthenium catalyst by supporting a complex salt of ruthenium on a carrier and then heating it in vacuum is disclosed. However, in this case, since a high vacuum is required, it is not suitable as an industrial catalyst preparation method. Also in this case, since the dispersibility is maintained by firing at a low temperature, it is expected that the dispersibility will be lowered when used or regenerated at a high temperature.

In addition, although it is not clear whether this is a technique for improving dispersibility, Japanese Patent Application Laid-Open No. 49-125289 discloses that
A catalyst composition comprising ruthenium dioxide and metal oxides (oxides of titanium, zirconium, hafnium, etc.) that form stable mixed oxides with ruthenium dioxide is disclosed. However, this publication does not describe the dispersibility of ruthenium at all, nor does it predict the effective pH of the impregnating solution of the present invention. In fact, in the examples of the publication, a ruthenium-containing impregnating liquid having a pH of 8 is used. Therefore, the present inventors prepared a supported ruthenium catalyst according to the examples of the publication and evaluated the dispersibility of ruthenium and the like in the obtained catalyst.
As a result, it was found that the dispersibility of ruthenium was insufficient.

[0012]

SUMMARY OF THE INVENTION The first object of the present invention is to support expensive ruthenium on a wide variety of catalyst supports, especially oxide supports, in a highly dispersed state and with good thermal stability by a simple operation. A variety of highly active and highly selective supported ruthenium-based catalysts [eg, carbonyl compounds, aromatic compounds, olefins and dienes, etc.] that have significantly improved activity per supported ruthenium by being impregnated and supported on a suitable carrier. A selective hydrogenation catalyst for unsaturated compounds,
Ammonia synthesis catalyst, FT synthesis catalyst, CO and CO ₂ methanation catalyst, CO and CO ₂ hydrogenation catalyst, nitro compound hydrogenation catalyst, hydrocarbon hydrocracking catalyst, aromatic amine Various hydrogenation catalysts such as selective hydrogenation catalysts, NO _x reduction and purification catalysts, steam reforming catalysts such as hydrocarbons, low-temperature complete oxidation catalysts, optical semiconductor catalysts, electrode catalysts, etc.] at low cost and easily Another object of the present invention is to provide an impregnating liquid for producing a ruthenium catalyst, which is extremely useful in practice and can be obtained.

Further, according to the present invention, ruthenium is supported on various carriers in a highly dispersed state and with good thermal stability, the activity per ruthenium is high, and a small ruthenium content is sufficient for various reactions as described above. An excellent supported ruthenium-based catalyst exhibiting high activity and selectivity, that is, various high-performance ruthenium-based catalysts that can be suitably used as industrial catalysts can be efficiently used by a simple operation by using the impregnating solution of the present invention. It is also an object to provide a method of manufacturing well.

[0014]

Means for Solving the Problems In order to make the most effective use of ruthenium, which is an expensive metal from a practical point of view, the present inventors carried it on various predetermined catalyst supports with good dispersibility, For the purpose of easily preparing various excellent supported ruthenium-based catalysts having a high activity and exhibiting high activity and high selectivity for various reactions as described above and which can be industrially advantageously used, by a simple operation. About how
Diligently studied. As a result, for example, at least one periodic table IV with a ruthenium compound such as ruthenium chloride
When an aqueous solution containing a compound of a group a element (zirconium, titanium, hafnium) and having a specific composition and physical properties adjusted to pH 3 or less is used as the impregnating liquid, the ruthenium component can be easily added to various catalyst carriers. It was found that it can be supported in a highly dispersed state by various operations, and further, the deterioration of dispersibility can be sufficiently suppressed even in a high temperature atmosphere, and therefore the above-mentioned object can be easily achieved. Based on this, the present invention has been completed.

That is, the present invention provides an aqueous solution containing a ruthenium compound and a compound of Group IVa of the periodic table,
Is 3 or less, and an impregnating solution for producing a ruthenium catalyst is provided.

Further, the present invention provides a method for easily obtaining various excellent supported ruthenium-based catalysts effective for various desired reactions using the above impregnating solution of the present invention by a simple operation. And at least part or all of the ruthenium component contained in the impregnating solution and part or all of the periodic table group IVa element component are supported on the carrier, and the ruthenium-supporting composition is dried and then calcined. A method for producing a ruthenium catalyst is also provided.

I. Impregnation liquid for producing ruthenium catalyst and preparation thereof The impregnation liquid of the present invention is an aqueous solution containing at least one or more ruthenium compounds and one or more compounds of Group IVa elements of the periodic table. And pH
Is 3 or less. This impregnating liquid
For example, a ruthenium component contained in the impregnating solution on the surface or in the pores of the catalyst support is impregnated into the catalyst support by impregnating it with a predetermined compound such as alumina or the like, and a suitable compound together with a component of Group IVa element of the periodic table. Can be supported evenly with good dispersibility in the form of, and after that, even if pretreatment such as firing or reduction at a high temperature that is usually carried out, the highly dispersed state of ruthenium can be maintained sufficiently stable. As a result, various desired high-performance supported ruthenium-based catalysts in which at least ruthenium is stably supported in the form of an active component such as a metal or an oxide with good dispersibility can be easily obtained.

Here, the important point is that the impregnating solution of the present invention contains a compound of Group IVa element of the periodic table at the same time as the ruthenium compound, and the above-mentioned excellent effects are exhibited for the first time. . Thus, when the impregnating solution of the present invention in which the ruthenium compound and the compound of the group IVa element of the periodic table are simultaneously dissolved is used, as described above, the ruthenium component is highly dispersed in various carriers and the thermal stability is good. There are many unclear points at this stage regarding whether or not it can be carried successfully, but the following points are thought to be important factors.

First, since the impregnating solution of the present invention is adjusted to have a relatively strong acidity of pH 3 or less, it is a stable aqueous solution in which neither the ruthenium compound nor the compound of group IVa is easily precipitated by itself. . This is also important, but not only that, as shown below, a ruthenium compound and a compound of the IVa group of the periodic table react with each other to form a complex-like compound, which brings about the above excellent effects. it is conceivable that.

That is, the inventors of the present invention mixed an aqueous solution of a ruthenium salt such as ruthenium chloride with an aqueous solution of a compound of the group IVa group of the periodic table such as zirconium oxychloride to form a complex between the ruthenium and the group IVa element. Of such a complex-like compound, and when an aqueous solution forming such a complex-like compound is used as an impregnating liquid, a black ruthenium hydroxide precipitates in the case of an acidic solution of the ruthenium compound alone. It was found that the formation of such ruthenium hydroxide is not observed even when such a basic carrier is impregnated by contact, or even when the pH of the solution is slightly increased during impregnation and loading. As described above, in the case of the impregnating liquid of the present invention, it is extremely difficult to generate a hydroxide of ruthenium which is agglomerated or is likely to cause agglomeration, and ruthenium is stabilized by a compound of the group IVa element to form a complex-like compound. Since it is introduced into the carrier as a result, it can be understood that as a result, it is uniformly supported in a highly dispersed state. Moreover, at this time, since the complex-like compound is strongly immobilized on the carrier by the reaction between the group IVa element component in the compound and the hydroxyl group of the carrier, as a result, treatment such as baking at high temperature or hydrogen reduction is performed. It can be considered that the high dispersibility is stably maintained even if it is performed.

If the impregnating solution of the present invention is prepared in such a manner that the ruthenium compound and the compound of Group IVa element of the periodic table are dissolved in water or an aqueous solvent containing water as a main component at least at a pH of 3 or less. In general, as the ruthenium compound and the compound of the group IVa element of the periodic table, which are used as the raw materials for the preparation, generally any kind or form may be used.

That is, as the ruthenium compound used as a starting material, for example, various ruthenium halides such as ruthenium trichloride, various halogenated ruthenates such as potassium hexachlororuthenate, potassium tetraoxorthenate and the like are usually used. Various ruthenium salts, ruthenium tetraoxide, various ammine complex salts such as hexaammineruthenium trichloride, cyano complex salts such as potassium hexacyanoruthenate are preferably used, but are not limited to these, Not limited to those which are soluble in water, various types can be used as long as they can be sufficiently dissolved in a state of pH of 3 or less by the addition or coexistence of an acid or an acidic compound. Therefore,
For example, ruthenium oxide such as diruthenium trioxide or ruthenium hydroxide, or oxyhalide such as oxyhalide, which is insoluble or difficult to dissolve in water having a pH of about 7, may be used by appropriately adding an acid such as hydrochloric acid and dissolving it. Good.

Among these various starting ruthenium compounds, ruthenium chloride is particularly preferably used.

On the other hand, as the group IVa element of the periodic table,
Zirconium, titanium and hafnium can be mentioned, but zirconium is particularly preferable. Regarding these compounds of Group IVa elements of the periodic table, similarly, various kinds of materials that can be dissolved into an aqueous solution at a pH of 3 or less by adding an acid such as hydrochloric acid or an acidic compound should be selected as raw materials for preparation. Specifically, for example, various halides such as zirconium tetrachloride, titanium tetrachloride, titanium trichloride, hafnium tetrachloride and the like, or partial hydrolysis products thereof, zirconyl chloride (zirconium oxychloride), titanyl chloride ( Various oxyhalides such as titanium oxychloride), zirconyl sulfate, titanyl sulfate,
Zirconium nitrate, zirconyl nitrate, titanyl nitrate, various oxyacid salts such as hafnium nitrate, potassium tetraoxozirconate, sodium hexafluorozirconate, potassium hexachlorotitanate, various zirconates such as ammonium hexafluorotitanate,
Titanate and hafnate, zirconium acetate, zirconyl acetate, zirconyl oxalate, hafnium oxalate, potassium tetraoxalatozirconate, various organic acid salts or organic coordination compounds, and further zirconium, titanium, hafnium. Alkoxide, hydroxide,
Various complex salts and the like can be exemplified. Among these various compounds of Group IVa elements of the periodic table, zirconium oxychloride and the like are particularly preferable.

When preparing the impregnating solution of the present invention, there are no particular restrictions on the order and method of addition, mixing and dissolution of water-based solvents such as water, ruthenium compounds, compounds of Group IVa elements of the Periodic Table, acids and the like. Alternatively, for example, water or an aqueous solution of an acid to which an acid has been added in advance may be dissolved by adding predetermined components at the same time, or may be added stepwise and dissolved, or an aqueous solution of a ruthenium compound and a cycle. An aqueous solution of a compound of the group IVa element in Table IV may be separately prepared, and these solutions may be mixed, or the remaining compound may be dissolved in one aqueous solution.

As the acid to be added as necessary when improving the solubility and adjusting the pH, various acids such as inorganic acids such as hydrochloric acid, sulfuric acid and nitric acid, and organic acids such as acetic acid and oxalic acid are used. It may be appropriately selected and used.

In the impregnating liquid of the present invention, the ratio of the ruthenium component to be dissolved and contained and the IVa group element component of the periodic table is represented by the molar ratio (M / Ru) of the periodic table IVa group element (M) and the ruthenium atom (Ru). And the molar ratio (M / Ru) is
Usually, it is suitable to select the range of 1 to 40, preferably 1 to 20. Here, if the molar ratio (M / Ru) is less than 1, the proportion of the group IVa element M in the periodic table becomes too small, and a part of ruthenium cannot be a complex-like compound, which easily causes aggregation. The effect of improving the dispersibility is reduced. On the other hand, this molar ratio (M / Ru)
Even if the value is larger than 40, further improvement effect such as dispersibility corresponding to it is not recognized, and in some cases, the amount of ruthenium component exposed on the surface is decreased, or the original characteristics of the carrier are significantly changed. May cause problems such as damage.

At that time, the amount (concentration) of the ruthenium compound or the compound of the group IVa element of the periodic table dissolved in the impregnation liquid is not particularly limited, but the concentration of the ruthenium compound is usually the molar concentration of ruthenium atoms, 0.0
It is preferable to select 1 mol / l or more.

The impregnating solution of the present invention contains a ruthenium compound and a periodic table IV as long as the object of the present invention is not impaired.
A compound other than the compound of the group a element or the acid may be appropriately added.

It is important for the impregnating liquid of the present invention to have a pH of 3 or less as described above, at least before contact with the carrier, and it is preferable to set the pH to 2 or less in some cases. Here, if the pH of the impregnating liquid is higher than 3, the compound of Group IVa element of the periodic table is easily hydrolyzed, and a hydroxide-like sol or gel is easily formed. When such a hydroxide-like sol or gel form is generated in the solution, it becomes difficult to successfully support the ruthenium component as the complex-like compound as described above, and as a result, the desired effect of improving dispersibility and the like is obtained. It will not be fully achieved.

Generally, an aqueous solution of a titanium compound is
It is known that when the pH is higher than 2, a hydroxide-like sol is likely to be generated, and in the case of an aqueous solution of a zirconium compound, when the pH is higher than 3, a hydroxide-like gel is likely to be generated. There is. Therefore, it is generally preferable that the pH of the impregnating liquid is selected to be 2 or less as described above.

As described above, the impregnating solution of the present invention can easily and evenly disperse the ruthenium component in a highly dispersed state even on a carrier having or having a basic hydroxyl group, which cannot be easily dispersed and supported by the conventional method. It is an excellent impregnating liquid for producing a ruthenium catalyst that can be supported without any treatment. Of course, it can be similarly suitably applied to any other general carrier. Moreover, since the dispersion stability is good even in a high temperature atmosphere, even after carrying, pre-treatment such as baking at high temperature or hydrogen reduction, reaction at high temperature, or regeneration at high temperature, high dispersion The sex can be maintained sufficiently stable. Therefore, by using the impregnating solution of the present invention, an excellent supported ruthenium-based catalyst showing high activity and high selectivity for various catalytic reactions, particularly as an inexpensive industrial catalyst showing high activity even if the ruthenium content is small. A wide variety of suitable supported ruthenium-based catalysts can be easily obtained.

As will be described later, there are no particular restrictions on the type, composition or shape of the target carrier, the loading system, etc., and there is also no particular restriction on the target catalytic reaction.

II. Production of Ruthenium Catalyst By using the impregnating solution of the present invention, which is impregnated into a suitable carrier by contact, and supporting the ruthenium component together with the IVa group element component of the periodic table, at least the active component consisting of ruthenium is stable in a highly dispersed state. It is possible to easily prepare various highly active supported ruthenium-based catalysts supported with good properties.

That is, as a method for easily obtaining such a highly active-supported ruthenium-based catalyst by a simple operation, a carrier is brought into contact with the impregnating solution of the present invention, and at least a part or all of the impregnating solution is contained. A method for producing a ruthenium catalyst is characterized in that a ruthenium component and a part or all of the periodic table group IVa element components are supported on the carrier, and the resulting ruthenium-supported composition is dried and calcined. .

Hereinafter, this manufacturing method will be described in detail.

In this method, first, at least the ruthenium component is supported by contact-impregnating the impregnating liquid of the present invention with a suitable carrier.

Examples of the target carrier include various kinds of alumina such as γ-alumina and α-alumina, single metal oxides such as silica, titania, zirconia and magnesia, alumina boria, silica alumina, zeolite, Examples thereof include silica zirconia, silica titania, titania alumina, mixed metal oxides such as silica magnesia, and the like, but are not limited to these, and generally any kind and composition Can be selected as a target.

As in the conventional case, these carriers are appropriately selected and used according to the purpose of use.

As in the conventional case, such a carrier can be used as the one whose composition and physical properties are adjusted or controlled by addition of additives, execution of pretreatment or selection of preparation method. For example, chemical treatment such as acid treatment, base treatment, ion exchange treatment, etc. is performed to adjust the acidity, etc., water or OH content is adjusted by heating or baking, and further, by various means. The composition and properties of the catalyst carrier may be adjusted or improved by controlling the pore size and the pore size distribution and the surface area. Further, in some cases, a material containing or supporting an appropriate metal component in advance may be used. Further, these carriers may be those which have been previously dried or calcined, may be uncalcined or undried, or may be slurry-shaped such as sol prepared by hydrolysis or the like. Good.

The shape and size of the carrier are not particularly limited, and examples thereof include powder, beads, pellets, granules, those coated on a structure such as a monolith, fine particles, and ultrafine particles. Can be used.
That is, it may be granulated or molded, or may not be particularly treated.

In the method for producing a catalyst of the present invention, the predetermined impregnating liquid (impregnating liquid of the present invention) is contact-impregnated into the predetermined carrier to support a predetermined metal component on the carrier, and thus obtained. The supporting composition is dried and then calcined under appropriate conditions.

The impregnation-supporting operation by contacting the impregnating liquid with the carrier can be carried out by a conventional method. For example, various commonly used impregnation methods (heat impregnation method, room temperature impregnation method, vacuum impregnation method,
Normal pressure impregnation method, impregnation dry solidification method, pore filling method, etc., or any combination thereof), dipping method, light wetting method, wet adsorption method, wet kneading method, spray method, coating method, etc. Any method such as a combination method may be used as long as it is a method of bringing the impregnating liquid and the carrier into contact with each other to carry them. Further, the series of operations of impregnating, supporting, drying and firing is performed at least once, but if necessary, these operations may be repeated twice or more and repeated multiple times.

Here, the amount ratio of the carrier to be used and the impregnating liquid is the target active metal component loading rate, the concentration of the metal compound in the impregnating liquid to be used, the type of the impregnating and supporting system, the pore volume and the ratio of the carrier to be used. It cannot be uniformly determined because it depends on the surface area, etc., but at least the amount of impregnating liquid that sufficiently wets the carrier to be supported should be used, while the upper limit of the amount of impregnating liquid used on the carrier (the amount to be used) should be used. Is not particularly limited, but usually, the dry weight of the carrier used is 10
It is preferable to select the amount of the impregnating liquid to be used in an amount of 100 ml or less per 0 g.

This contacting operation (impregnation supporting operation) is carried out under atmospheric pressure or under reduced pressure (under reduced pressure exhaust) as in the conventional case.
The operating temperature at that time is not particularly limited, and it can be performed at or near room temperature, and heating or heating is performed as necessary, for example, at room temperature to about 80 ° C. It can be suitably performed.

As described above, the predetermined ruthenium component can be uniformly and uniformly loaded on the predetermined carrier. As can be seen from the characteristics of the impregnation supporting method shown above, depending on the case, all the ruthenium components contained in the impregnating solution used may be supported,
For example, only a part of the ruthenium component in the used impregnating liquid may be supported by removing the excess impregnating liquid at any time after the contact.

The final supported amount of the ruthenium component and the group IVa element of the periodic table is determined in consideration of properties such as the type and surface area of the carrier, or various conditions such as the use of the catalyst, that is, the type and properties of the target reaction. However, in many cases, the amount of ruthenium component converted to a ruthenium metal is usually 0.05 to 5% by weight, preferably 0.1 as the amount supported on a predetermined carrier. To 1% by weight, while the group IVa element component of the periodic table is converted to oxides (TiO ₂ , ZrO ₂ , HfO ₂ ) and is usually 0.05 to 20% by weight, preferably 1 .0-10
It is preferable to select in the range of weight%.

In the method for producing a catalyst of the present invention, the ruthenium-supporting composition obtained as described above is dried and then calcined at an appropriate temperature.

This drying is usually carried out at a temperature of 50 to 150 ° C., preferably 80 to 130 ° C.
However, depending on the impregnation support method, a large amount of water evaporates,
Since a considerably dried product can be obtained, in such a case, a separate drying operation may not necessarily be performed.

The above-mentioned calcination can also be carried out according to a conventional method, usually 300 to 70 in air or in an air stream.
It is suitably carried out in a temperature range of 0 ° C, preferably 400 to 600 ° C. In addition to air, an oxygen-containing gas such as pure oxygenated air or oxygen-enriched air may be substituted or used together.
A firing time of about 1 to 24 hours is usually sufficient.

If necessary, the carrier composition may be molded into a predetermined shape and size at any suitable time before firing. When molding is carried out, this molding can be suitably carried out in accordance with a conventional method, and if necessary, a suitable binder component may be added.

As described above, various supported ruthenium-based catalysts (or precursors thereof) exhibiting high activity for a desired reaction in which a predetermined ruthenium component is uniformly supported in a predetermined supported amount in a highly dispersed state. ) Can be easily obtained.

The metal component in the catalyst obtained by this calcination is usually in the form of an oxide or a complex oxide, and the ruthenium component is also usually supported in the form of an oxide or a complex oxide in a highly dispersed state. Has been done.

The catalyst thus obtained can be used as it is as a catalyst or a catalyst component for a predetermined catalytic reaction, but if necessary, various suitable pretreatments are carried out to activate it before use in the catalytic reaction. May be. This pretreatment can be performed according to a conventional method. For example, it may be appropriately reduced with a reducing agent such as hydrogen to convert the ruthenium component into highly dispersed metallic ruthenium and used for the reaction.

The highly dispersed metallization treatment by hydrogen reduction can be suitably carried out, for example, at a temperature of 200 to 800 ° C.

Here, the kind of the target catalytic reaction is not particularly limited, and this production method can be applied to the production field of a catalyst suitable for all reactions in which a ruthenium-based catalyst is generally effective. it can.

Examples of such catalytic reaction include, for example, selective hydrogenation reaction of carbonyl compounds, aromatic compounds, unsaturated compounds such as olefins and dienes, ammonia synthesis reaction, FT synthesis reaction, CO and CO ₂ methanation reaction, selective hydrogenation reaction of CO or CO ₂ to alcohol or other oxygen-containing compound, homologation of methanol with CO and hydrogen to ethanol, hydrocarbonylation reaction of olefin, amine of nitro compound Hydrogenation reaction such as selective hydrogenation reaction to N, hydrogenolysis reaction of hydrocarbons, selective hydrogenation reaction of aromatic amine, etc., N
A wide variety of reactions such as a reduction purification reaction of O _x , a steam reforming reaction of hydrocarbons, a complete oxidation reaction at low temperature, a partial oxidation reaction, a photolysis reaction of water, and the like can be mentioned.

By the way, among such catalytic reactions, there is also a reaction in which a catalyst having sufficient performance can be obtained only by drying at a low temperature after the impregnating and supporting the catalyst without necessarily firing at a high temperature as described above. is there. That is, as a general method for producing a catalyst using the impregnating liquid of the present invention, calcination may not necessarily be performed.

[0059]

EXAMPLES The present invention will be described in more detail below with reference to Examples of the present invention and Comparative Examples thereof, but the present invention is not limited to these Examples.

Example 1 0.66 g of ruthenium chloride (RuCl ₃ .nH ₂ O) was dissolved in water to obtain a 40 cc aqueous solution, and 13.1 g of zirconium oxychloride (ZrOCl ₂ .8H ₂ O) was further dissolved to obtain an impregnating solution. did. The pH of the impregnating liquid at this time is 0.4,
No gel-like substance was found in the solution. When this impregnating solution is further diluted with water, it exhibits a green color, which is different from that when the ruthenium chloride aqueous solution is diluted (reddish brown), and it is speculated that ruthenium and zirconium complex-like compounds are formed in the solution. The aqueous solution containing only zirconium oxychloride was colorless and transparent.

Using this impregnating solution, 50 g of γ-Al ₂ O ₃ carrier pellets were loaded with ruthenium by the pore filling method. The color of the catalyst body immediately after impregnation was orange to brown, and formation of black ruthenium hydroxide was not observed. 1
After drying at 20 ° C. for 1 hour, firing was performed in air at 500 ° C. for 2 hours. The catalyst body after firing was green. The ruthenium content in this catalyst as determined by composition analysis was 0.5% by weight.

The catalyst body after calcination was further subjected to 800 times in a hydrogen stream.
Hydrogen reduction was carried out at ℃ for 4 hours. When the ruthenium particles of this reduced sample were observed with a transmission electron microscope at a magnification of 100,000-400,000 times, no ruthenium particles of 15 Å or more were observed, and extremely high dispersion was obtained despite reduction at high temperature. It was found that ruthenium was supported on.

[0063] Using the alpha-Al ₂ O ₃ as a second embodiment carrier pellets, 20cc of impregnation liquid 40cc prepared in the same manner as in Example 1 to the α-Al ₂ O ₃ carrier pellets by pore filling method After impregnation and drying at 120 ° C. for 1 hour, firing was performed at 500 ° C. for 2 hours. Further, the remaining 20 cc of the above impregnating liquid is impregnated,
After drying at 20 ° C. for 1 hour, firing was performed at 500 ° C. for 2 hours. Ruthenium content by composition analysis is 0.5% by weight
Met. Immediately after impregnation, the color of the catalyst body was green, and formation of black ruthenium hydroxide was not observed.

The catalyst body after calcination was further subjected to 800 times in a hydrogen stream.
Hydrogen reduction was carried out at ℃ for 4 hours. When the ruthenium particles of this reduced sample were observed with a transmission electron microscope at a magnification of 100,000 to 400,000 times, ruthenium particles of 30 Å or more were not observed, and extremely high dispersion was obtained despite reduction at high temperature. It was found that ruthenium was supported on the.

Example 3 0.66 g of ruthenium chloride (RuCl ₃ .nH ₂ O) was dissolved in water to obtain a 40 cc aqueous solution, and 13.1 g of zirconium oxychloride (ZrOCl ₂ .8H ₂ O) was dissolved.

Further, 0.1 N ammonia water is added to 8.0 c.
When c was added, the pH became 2.4.

At this time, almost no gel-like substance was observed in the solution.

When this impregnating solution was further diluted with water, a green color was obtained, which was different from that when the aqueous ruthenium chloride solution was diluted (reddish brown). Therefore, it is presumed that ruthenium and zirconium complex-like compounds are formed in the solution. It

Using this impregnating solution, the same γ-A as in Example 1 was used.
Ruthenium was loaded on 50 g of the l ₂ O ₃ carrier pellet by the pore filling method. Immediately after impregnation, the color of the catalyst body was green, and formation of black ruthenium hydroxide was not observed. After drying at 120 ° C. for 1 hour, firing was performed in air at 500 ° C. for 2 hours. The catalyst body after this calcination was green. The ruthenium content in this catalyst was 0.5% by weight based on the composition analysis.

The catalyst body after firing was further subjected to 800 times in a hydrogen stream.
Hydrogen reduction was carried out at ℃ for 4 hours. When the ruthenium particles of the reduced sample were observed with a transmission electron microscope at a magnification of 100,000-400,000 times, no ruthenium particles of 15 Å or more were observed, and even though they were reduced at a high temperature, the dispersion became extremely high. It was found that ruthenium was supported.

Comparative Example 1 0.66 g of ruthenium chloride (RuCl ₃ .nH ₂ O) was dissolved in water to obtain a 40 cc aqueous solution, which was used as an impregnating solution. The impregnation liquid had a pH of 1.5.

Using this impregnating solution, the same γ-A as in Example 1 was used.
Ruthenium was loaded on 50 g of the l ₂ O ₃ carrier pellet by the pore filling method. Immediately after impregnation, the color of the catalyst body was black, and formation of ruthenium hydroxide was observed.

Then, after drying at 120 ° C. for 1 hour, 500
Firing was performed in air at 0 ° C. for 2 hours. The ruthenium content in this catalyst was 0.5% by weight based on the composition analysis.

The catalyst body after calcination was further treated in a hydrogen stream at 800
Hydrogen reduction was carried out at ℃ for 4 hours. When the ruthenium particles of the reduced sample were observed with a transmission electron microscope at a magnification of 100,000 to 400,000 times, the ruthenium particle diameter was 75 to 300Å, and the dispersibility of ruthenium was compared with that of the example. It is very inferior.

Comparative Example 2 0.66 g of ruthenium chloride (RuCl ₃ .nH ₂ O) was dissolved in water to prepare a 40 cc aqueous solution, which was used as an impregnating solution. The impregnation liquid had a pH of 1.5.

Using this impregnating solution, the same α-A as in Example 2 was used.
In the same manner as in Example 2, the impregnating liquid was divided into two portions and 50 g of the l ₂ O ₃ carrier pellets was loaded with ruthenium by the pore filling method. Immediately after impregnation, the color of the catalyst body was black, and formation of ruthenium hydroxide was observed.

Then, after drying at 120 ° C. for 1 hour, 500
Firing was performed in air at 0 ° C. for 2 hours. The ruthenium content in this catalyst was 0.5% by weight based on the composition analysis.

The catalyst body after firing was further subjected to 800 times in a hydrogen stream.
Hydrogen reduction was carried out at ℃ for 4 hours. When the ruthenium particles were observed with a transmission electron microscope at a magnification of 100,000 to 400,000 times with respect to the sample after the reduction, the ruthenium particle diameter was 75 to 300Å, and the ruthenium aggregated,
It can be seen that the dispersibility is extremely inferior to the examples.

Comparative Example 3 0.66 g of ruthenium chloride (RuCl ₃ .nH ₂ O) was dissolved in water to obtain a 40 cc aqueous solution, and 13.1 g of zirconium oxychloride (ZrOCl ₂ .8H ₂ O) was dissolved to obtain an impregnating solution. .

When ammonia water was gradually added, formation of a strong gel-like substance was observed at pH 3.5 or higher. This is due to the formation of zirconium hydroxide.

Using the above impregnating solution at pH 3.5,
Ruthenium was carried on 50 g of the same γ-Al ₂ O ₃ carrier pellet as in Example 1 by the pore filling method. At this time, almost no gel-like substance could penetrate into the inside of the carrier pellets, and after drying at 120 ° C. for 1 hour, a gel solid substance was formed separately from the pellets. In addition, after firing in air at 500 ° C. for 2 hours, only the pellets were extracted and the composition was analyzed. The ruthenium content in the carrier pellets was 0.1% by weight or less, and ruthenium was mostly contained in the carrier pellets. It could not be introduced.

Comparative Example 4 Zirconium oxychloride (ZrOCl ₂ .8H ₂ O) 1
What melted 3.1 g in water and made a 40 cc aqueous solution,
50 g of the same γ-Al ₂ O ₃ carrier pellet as in Example 1 was impregnated by the pore filling method. After drying at 120 ° C for 1 hour,
Further, firing was performed in air at 500 ° C. for 2 hours. Then, ruthenium chloride (RuCl ₃ · nH
₂ O) 0.66 g was dissolved in water to obtain a 40 cc aqueous solution, which was impregnated by the pore filling method. The pH of the impregnating liquid used at this time was 1.5.

Immediately after impregnation, the color of the catalyst body was black, and formation of ruthenium hydroxide was observed. After drying at 120 ° C. for 1 hour, firing was performed in air at 500 ° C. for 2 hours. The ruthenium content in the catalyst as determined by composition analysis was 0.5% by weight.

The catalyst body after calcination was further treated in a hydrogen stream at 800
Hydrogen reduction was carried out at ℃ for 4 hours. When the ruthenium particles of the reduced sample were observed with a transmission electron microscope at a magnification of 100,000 to 400,000 times, the ruthenium particle diameter was 75 to 300Å, and the dispersibility of ruthenium was compared with that of the example. It is very inferior.

Evaluation of Experimental Results In Examples 1 to 3, by using an aqueous solution in which ruthenium having a pH of 3 or less and zirconium oxychloride were dissolved at the same time, it was found that ruthenium could be supported in a high dispersion even after high temperature reduction at 800 ° C. .

Even when the above solution is used, ruthenium can be introduced into the carrier because zirconium hydroxide (gel) is produced when the pH exceeds 3 as shown in Comparative Example 3. You can see it disappears.

In Comparative Examples 1 and 2, impregnation was carried out using an aqueous solution containing only ruthenium chloride. However, since the hydroxide of ruthenium was produced by the hydroxyl groups in the carrier, ruthenium was agglomerated and supported, and the dispersibility of ruthenium was greatly reduced. I understand that

In Comparative Example 4, first, zirconium was used as a carrier and then impregnated with an aqueous solution of ruthenium chloride. However, in the aqueous solution, a hydroxide of ruthenium is formed because hydroxyl groups are still formed in the carrier. For this reason, it can be seen that the dispersibility of ruthenium is greatly reduced as in Comparative Examples 1 and 2.

That is, when an aqueous solution in which a ruthenium compound and zirconium oxychloride are simultaneously dissolved is used as in Examples 1 to 3, a complex-like compound of ruthenium and zirconium is produced, so that ruthenium is present even in the presence of a hydroxyl group in the carrier. No hydroxide is formed. Even at higher temperatures,
Since the above-mentioned relationship between ruthenium and zirconium is maintained, it is presumed that the high dispersibility of ruthenium is maintained.

[0090]

INDUSTRIAL APPLICABILITY The impregnating solution for producing a ruthenium catalyst according to the present invention contains at least a ruthenium compound and a compound of Group IVa element of the periodic table (ie, zirconium, titanium, hafnium) dissolved therein and has a pH of 3 or less. Since it is an aqueous solution having composition and physical properties, it can be effectively impregnated in a highly dispersed state with a ruthenium component in a highly dispersed state by a simple operation by impregnating it with various carriers by contact and impregnated into a suitable carrier. By carrying out impregnation, it is possible to easily obtain various highly active and highly selective supported ruthenium-based catalysts whose activity per contained ruthenium is remarkably improved. Therefore, when this impregnating liquid is used, the ruthenium component can be effectively supported in a highly dispersed state, so that the content of ruthenium, which is an expensive metal, can be reduced, and it is inexpensive and industrially advantageous. A high-performance ruthenium-based catalyst can be easily obtained. Also,
This highly dispersed state is maintained sufficiently stable even when exposed to a high temperature atmosphere such as baking at high temperature, pretreatment such as hydrogen reduction, reaction at high temperature, regeneration, etc. It can also be suitably applied.

That is, according to the present invention, it is possible to provide a practically remarkably useful impregnating solution for producing a ruthenium catalyst, and a method for producing various supported ruthenium-based catalysts of high performance by a simple operation. it can.

Claims (2)

(57) [Claims] 1. An impregnating solution for producing a ruthenium catalyst, which is an aqueous solution containing a ruthenium compound and a compound of a group IVa element of the periodic table and has a pH of 3 or less. 2. A carrier is brought into contact with the impregnating liquid according to claim 1, the ruthenium component contained in the impregnating liquid and the periodic table IV.
A method for producing a ruthenium catalyst, which comprises supporting an a-group element component on the carrier, drying the resulting ruthenium-supporting composition, and then calcining the composition.