JPH08196907A - Production of ruthenium catalyst and steam reforming method for hydrocarbon employing the catalyst - Google Patents

Abstract

PURPOSE: To carry a ruthenium component near a zirconium component in a highly dispersed state by a simple process by bringing a solution containing a ruthenium compound, a zirconium compound, and compounds of alkaline earth metal or rare earth element into contact with a carrier. CONSTITUTION: A ruthenium-based catalyst is produced by bringing a solution containing a ruthenium compound, a zirconium compound, and at least one kind of compounds selected from alkaline earth metal compounds and rare earth metal compounds into contact with a carrier. The ruthenium-based catalyst is employed for steam reforming of hydrocarbons. Additionally, a compound selected from among nickel compounds and cobalt compounds is added to the solution. Ruthenium chloride may be used as the ruthenium compound and an oxychloride of zirconium may be used as the zirconium compound. Mg or Ca may be used as the alkaline earth metal and Y or La is used as the rare earth metal. On the other hand, alumina is used as the carrier.

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 ruthenium catalyst, more specifically, a ruthenium component can be supported in a highly dispersed state on a catalyst carrier by a simple operation.
The present invention relates to a method capable of producing a ruthenium catalyst having excellent activity per contained ruthenium and also excellent heat resistance. The present invention also relates to a hydrocarbon steam reforming method using a ruthenium catalyst obtained by the above-mentioned production method, and more specifically, it is suitably applied to various hydrogen production processes, particularly hydrogen production processes incorporated in fuel cells. The present invention relates to a steam reforming method for hydrogen.

[0002]

2. Description of the Related Art Recently, a steam reforming catalyst for ruthenium-containing hydrocarbons has a high catalytic activity such as high activity and excellent carbon deposition resistance even under a low steam / carbon operating condition. It is widely used in fuel cells that require a long-life steam reforming catalyst under steam / carbon ratio operating conditions. In recent years, in the fuel cell, in order to effectively utilize the exhaust heat, it is necessary to further reduce the steam / carbon ratio (to be 3 or less) as compared with the conventional one, and the carbon deposition can be performed even under such a condition that carbon is easily deposited. The development of a catalyst that does not occur is desired.

On the other hand, since ruthenium is a noble metal, the catalyst containing it is generally expensive. Therefore, in order to popularize the industrial use of the ruthenium-containing catalyst, it is necessary to reduce not only the catalyst performance but also the catalyst price. For that purpose, it is necessary to make the catalyst highly active, to reduce the amount of the catalyst used, to reduce the raw material cost used for the catalyst production, and to simplify the production process.

Regarding the ruthenium-containing catalyst, JP-A-2-
Japanese Patent No. 2879 and Japanese Patent Application Laid-Open No. 3-202151 disclose a catalyst in which ruthenium is supported on a zirconia carrier. In the catalyst obtained by the preparation method described in these, the dispersibility of ruthenium is insufficient, and since a large amount of zirconia, which is expensive as compared with alumina and the like, is used as a carrier, the catalyst price is expensive. Has become.

Further, JP-A-5-220397 discloses a catalyst comprising alumina as a carrier, zirconia having a zirconia sol as a precursor supported as a co-catalyst, and ruthenium as an active component. Has been done. However, it is not described here how ruthenium is distributed. In addition, since the zirconia sol is supported on an alumina carrier, dried and calcined, the ruthenium component is impregnated, dried, and calcined, which makes the catalyst preparation process complicated and increases the manufacturing cost. There is.

[0006]

DISCLOSURE OF THE INVENTION An object of the present invention is to allow expensive ruthenium to be supported on various catalyst carriers, particularly oxide carriers, in a highly dispersed state by a simple operation and with good thermal stability. Production of a ruthenium catalyst, which has a significantly improved activity per supported ruthenium, and which can maintain a high activity even at high temperature during calcination or reaction, at a low cost and easily To provide a method.

Further, according to the present invention, the ruthenium catalyst obtained by the above-mentioned method is used, and even under an operating condition of a low steam / carbon ratio, carbon is less likely to be deposited, and the operation can be economically and stably performed for a long time. It is also an object to provide a steam reforming method for hydrocarbons that can be performed.

The ruthenium catalyst obtained by the present invention is used as a steam reforming catalyst for hydrocarbons, as well as a selective hydrogenation catalyst for carbonyl compounds, aromatic compounds, unsaturated compounds such as olefins and dienes, 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 purification catalysts, low temperature complete oxidation catalysts,
It can be used as an optical semiconductor catalyst, an electrode catalyst and the like.

[0009]

Means for Solving the Problems As a result of intensive studies for achieving the above-mentioned object, the present inventors have found that when preparing a ruthenium catalyst, a ruthenium compound, a zirconium compound and a compound of an alkaline earth metal or a rare earth element are used. By bringing the contained solution into contact with the carrier, the ruthenium component can be supported on the carrier in the vicinity of the zirconium component in a highly dispersed state by a simple operation, and further, deterioration of dispersibility is sufficiently suppressed even in a high temperature atmosphere. Based on this finding, the present invention has been completed.

That is, the present invention is characterized in that a solution containing at least one compound selected from a ruthenium compound, a zirconium compound and a compound of an alkaline earth metal and a compound of a rare earth element is brought into contact with a carrier. The present invention provides a method for manufacturing the same.

Further, when the present inventors carry out a steam reforming reaction of hydrocarbons using the ruthenium catalyst obtained by the above-mentioned method of the present invention, operating conditions with a low steam / carbon ratio such as 3 or less. However, it has been found that the steam reforming reaction can be stably and economically carried out without causing carbon deposition and maintaining high activity of the catalyst, and based on this finding, the present invention has been completed.

That is, the present invention further provides a method for steam reforming a hydrocarbon, characterized by using the ruthenium catalyst obtained by the above method.

I. Method for producing ruthenium catalyst The solution to be brought into contact with the carrier by the method of the present invention is at least
A solution containing one or more ruthenium compounds, one or more zirconium compounds, and one or more compounds selected from alkaline earth metal compounds and rare earth element compounds. . By rubbing this solution into contact with various catalyst carriers such as alumina, the ruthenium component contained in the solution on the surface or in the pores of the catalyst carrier is changed to a component composed of an alkaline earth metal or a rare earth element. Along with the zirconium component, it can be evenly supported in the form of a suitable compound with good dispersibility, and after that, even if a pretreatment such as firing or reduction at a high temperature that is usually performed is performed, the ruthenium component And the zirconium component can be maintained in a sufficiently dispersed state, and as a result, ruthenium, zirconium, alkaline earth metals and rare earth elements are stably dispersed in the form of active components such as metals and oxides in the vicinity. A supported high-performance supported ruthenium-based catalyst can be easily obtained.

Here, the important point is that the solution used in the present invention simultaneously contains the zirconium compound and the alkaline earth metal compound or the rare earth element compound together with the ruthenium compound. Excellent effect is exhibited. The reason why such effects are exerted is unknown at this stage, but the following points are considered to be important factors.

First, the solution used in the present invention contains a ruthenium compound, a zirconium compound, an alkaline earth metal compound and a rare earth element compound, but it is desirable to adjust the solution to be acidic. At that time, the pH is preferably adjusted to 3 or less, more preferably pH 1.5 or less. This is because when the pH becomes high, the respective compounds tend to precipitate or aggregate in a gel state, which makes it difficult to carry out high dispersion. Further, as shown below, it is considered that the ruthenium compound and the zirconium compound react with each other to form a complex-like compound, which brings about the above excellent effects.

That is, when a solution of a ruthenium compound such as ruthenium chloride is mixed with a zirconium compound such as zirconium oxychloride, a chemical interaction occurs between ruthenium and zirconium to form a complex-like compound. When a solution forming such a complex-like compound is used for impregnating a carrier, ruthenium is converted to hydroxide, for example, up to about pH 3 even if the pH of the solution increases to some extent during impregnation. Does not aggregate. As described above, in the solution used in the present invention, the hydroxide of ruthenium, which is agglomerated or easily causes agglomeration, is extremely unlikely to be generated, and ruthenium is stabilized by the zirconium compound and becomes a complex-like compound in the carrier. Since it is introduced, it is presumed that it can be supported in the vicinity of the zirconium component in a highly dispersed state. Further, when a carrier having a surface hydroxyl group formed by adsorption of water such as alumina is used, the ruthenium and zirconium components are easily fixed in the carrier during impregnation, and expensive ruthenium and zirconium components are used more efficiently. be able to. It is considered that this is because the zirconium component reacts with the surface hydroxyl groups of the carrier to form a bond with the carrier. The present invention has been completed based on the above findings.

Furthermore, when the present inventors add a component selected from an alkaline earth metal compound and a rare earth element compound to the solution in addition to the ruthenium compound and the zirconium compound, the ruthenium supported in a highly dispersed state as described above. It has been found that the surface areas of the components and the zirconium component are maintained even at high temperatures during calcination and reaction, and as a result, deterioration of catalyst performance during the reaction is suppressed.

Although the effects of these alkaline earth metal components and rare earth element components are still unknown, the following can be considered.

Taking the case of using alumina as a carrier, for example,
It is considered that the reactivity between the zirconia component generated by the calcination and the alumina is low, and a bond between the two is almost no longer produced. Therefore, the zirconia component easily moves on the carrier due to the firing or reaction at high temperature (600 ° C. or higher), and it is easy to sinter with the neighboring ruthenium which is the active component. On the other hand, alkaline earth metals and rare earth elements are reactive with both zirconia and alumina. Therefore, by using the solution containing the compounds of these components as the impregnating liquid, an interaction occurs between the alumina-zirconia through an alkaline earth metal or a rare earth element, the zirconia component is immobilized on the carrier, and sintering is performed. It is thought that it is difficult to do so, and as a result, the highly dispersed state of the ruthenium component supported near the zirconia component may be maintained.

The solvent of the solution used in the present invention is, for example, water or an aqueous solvent containing water as a main component, or an organic solvent such as alcohol or ether, which is at least a ruthenium compound, a zirconium compound, and an alkaline earth metal. Any compound can be freely selected as long as it can dissolve a compound selected from a compound of a metal and a compound of a rare earth element. Among them, highly soluble water or an aqueous solvent containing water as a main component is preferably used. In addition, as each compound used as a raw material for its preparation, generally any kind or form may be used as long as it can be dissolved in a solvent.

That is, as the ruthenium compound used as a raw material for preparation, various ruthenium halides such as ruthenium trichloride and various halogenated ruthenium salts such as potassium hexachlororuthenate are usually used.
Various ruthenium salts such as potassium tetraoxorthenate, ruthenium tetroxide, various ammine complex salts such as hexaammineruthenium trichloride, cyano complex salts such as potassium hexacyanoruthenate are preferably used, but are not limited to these. However, it is not limited to those that are soluble in a certain solvent, and various types can be used as long as they can be sufficiently dissolved by the addition or coexistence of an acid or an acidic compound. Therefore, for example, ruthenium oxide such as diruthenium trioxide and ruthenium hydroxide,
Alternatively, even an oxyhalide or the like that is insoluble or difficult to dissolve in water having a pH of about 7 can be used by appropriately adding an acid such as hydrochloric acid and dissolving it.

Of these various starting ruthenium compounds, ruthenium chloride is particularly preferably used because it is widely used industrially and is easily available. Note that these ruthenium compounds may be used alone or in combination of two or more.

Similarly, for the zirconium compound, one which is soluble in a certain solvent, or an acid such as hydrochloric acid or an acidic compound is dissolved in the solvent as an acidic solvent to form a solution. Various materials capable of producing can be used as a raw material for preparation. Specifically, for example, various halides such as zirconium tetrachloride or partial hydrolysis products thereof, various oxyhalides such as zirconyl chloride (zirconium oxychloride), various kinds of zirconyl sulfate, zirconium nitrate, zirconyl nitrate, etc. Oxygenates, potassium tetraoxozirconate, various zirconates such as sodium hexafluorozirconate, zirconium acetate, zirconyl acetate, zirconyl oxalate, various organic acid salts such as potassium tetraoxalatozirconate Coordination compounds, etc.
Furthermore, alkoxide of zirconium, hydroxide, various complex salts, etc. can be illustrated.

Of these various zirconium compounds, zirconium oxychloride is particularly preferable. For example, ZrOCl ₂ .nH ₂ O and ZrO (OH) Cl.n.
A hydrate represented by H ₂ O, a commercially available product in the form of a solution, and the like are preferably used because they easily form a complex-like compound with ruthenium. These zirconium compounds may be used alone or in combination of two or more.

Similarly, the alkaline earth metal compound and the rare earth element compound, which are soluble in a certain solvent, are dissolved by adding an acid such as hydrochloric acid or an acidic compound to form an aqueous solution. Various substances that can be used can be used as a preparation raw material. Usually, highly soluble compounds such as nitrates and chlorides are preferably used. Examples of the alkaline earth metal compound include compounds of beryllium, magnesium, calcium, strontium, barium and radium. Among them, compounds of magnesium, calcium, strontium and barium are preferable, and particularly, reaction with zirconium and alumina. Compounds of magnesium and calcium, which have high properties, are preferably used. Specifically, for example, magnesium nitrate, calcium nitrate, strontium nitrate, barium nitrate, magnesium chloride, calcium chloride, strontium chloride,
Examples thereof include barium chloride. Further, as the compound of the rare earth element, scandium, yttrium, lanthanum, cerium, praseodymium, neodymium,
Examples thereof include compounds of promethium, samarium, europium, cadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium and lutetium. Among them, yttrium, lanthanum and cerium compounds are preferable, and particularly zirconium,
Compounds of yttrium and lanthanum, which have high reactivity with alumina, are preferably used. Specific examples include yttrium nitrate, lanthanum nitrate, yttrium chloride, and lanthanum chloride.

Among these various alkaline earth metal compounds and rare earth element compounds, magnesium nitrate, yttrium nitrate, lanthanum nitrate and various hydrous salts thereof are particularly preferably used. These alkaline earth metal compounds and rare earth element compounds may be used alone or in combination of two or more.

When preparing the above-mentioned solution used in the present invention, the order and method of addition, mixing and dissolution of each component such as solvent, ruthenium compound, zirconium compound, alkaline earth metal compound, rare earth element compound and acid are described. There is no particular limitation. For example, a predetermined component may be simultaneously added and dissolved in a solvent or an acidic solution to which an acid has been added, or may be added stepwise and dissolved, or a solution of each component may be prepared separately. However, these solutions may be mixed, or a solution of some components may be prepared and then the remaining components may be dissolved in the solution. At this time, the liquid temperature is preferably about room temperature, but may be heated up to about 60 ° C. to promote dissolution.

As the acid added as necessary for improving the solubility and adjusting the pH, various acids such as inorganic acids such as hydrochloric acid, sulfuric acid and nitric acid, organic acids such as acetic acid and oxalic acid, and the like can be used. It may be appropriately selected and used. At this time, the pH is adjusted to a relatively strong acidity, preferably 3 or less, more preferably 1.5 or less. Adjust the pH to 3 or 1.
When it is higher than 5, various compounds described above may be precipitated.

In the solution used in the present invention, the ratio of the ruthenium component and the zirconium component to be dissolved and contained is
The molar ratio of the zirconium atom (Zr) to the ruthenium atom (Ru) (Zr / Ru) is (Zr / Ru).
Suitably, u) is selected to be 100 or less, preferably 1 to 20, more preferably 2 to 10. Here, if the molar ratio (Zr / Ru) is 1 or 2
If it is smaller, the proportion of zirconium will be too small, and a part of ruthenium will not be a complex-like compound and will be easily aggregated, and the effect of improving dispersibility will be reduced accordingly, and the ruthenium component can be supported in the vicinity of the zirconium component. It may run out. On the other hand, even if this molar ratio (Zr / Ru) is made larger than 100, 20 or 10, it is difficult to obtain a further improvement effect such as dispersibility and the like, and in some cases, the amount of the ruthenium component exposed on the surface. May decrease, or the original characteristics of the carrier may be significantly changed and impaired.

The amount of the compound selected from the alkaline earth metal compound and the rare earth element compound to be dissolved and contained in the above solution is the sum of the atoms of the alkaline earth metal and the atoms of the rare earth element (A) and the zirconium atom of the zirconium compound. When expressed as a molar ratio (A / Zr) with respect to (Zr), the molar ratio (A / Zr) is usually 0.01 to 5, preferably 0.
It is preferable to select it in the range of 1 to 5, more preferably 0.1 to 1. Here, if the molar ratio (A
/ Zr) is less than 0.01 or 0.1, the proportion of the alkaline earth metal and the rare earth element is small, so that the effect of suppressing the decrease in the surface area of the supported component cannot be obtained and the effect of improving the heat resistance may be insufficient. There is. On the other hand, this molar ratio (A / Zr)
Even if is larger than 5 or 1, it is difficult to obtain the corresponding effect of improving heat resistance. Moreover, since the basicity of the obtained catalyst body tends to be strong, for example, when the contact between the carrier and the solution is divided into several times, when the carrier and the solution are contacted with each other after the second contact. Each component in the solution,
Mainly, the zirconium component gels before moving onto the carrier, which may make it impossible to support the carrier surface in a highly dispersed state.

The amount (concentration) of each compound to be dissolved in the above solution is not particularly limited, but the concentration of the ruthenium compound is usually the molar concentration of ruthenium atoms,
0.001 mol / l or more, preferably 0.01 to 10
It is preferable to select it so that it is mol / l, more preferably 0.1 to 5 mol / l.

The above solution used in the present invention contains a ruthenium compound, a zirconium compound, an alkaline earth metal compound, a rare earth element compound and an acid other than the acid for adjusting the solubility, as long as the object of the present invention is not impaired. You may add a component suitably.

For example, in the case of preparing a catalyst particularly suitable for steam reforming of hydrocarbons by the method of the present invention, the above-mentioned solution is used to prepare the above-mentioned ruthenium compound, zirconium compound, alkaline earth metal compound and rare earth element compound. By using a solution in which, in addition to the selected compound, at least one compound selected from nickel compounds and cobalt compounds is used, a catalyst having more excellent steam reforming activity can be obtained.

Similarly, as for these nickel compounds and cobalt compounds, those exhibiting solubility in a certain kind of solvent, acid such as hydrochloric acid, acidic compound, etc. are added to adjust the pH.
Various substances that can be dissolved by adjusting the above can be used as a preparation raw material. Usually, highly soluble compounds such as nitrates and chlorides are preferably used. Specifically, for example, nickel nitrate (II), basic nickel nitrate, primary cobalt nitrate, basic cobalt nitrate, nickel dichloride, cobalt dichloride, various hydrous salts of these and the like can be illustrated. Among them, nickel nitrate (I
I), cobaltous nitrate and the like are particularly preferably used. In addition, these nickel compounds and cobalt compounds may be used individually by 1 type, and may use 2 or more types together.

The amount of the compound selected from the nickel compound and the cobalt compound to be dissolved and contained in the above solution is the molar ratio (B / B) of the total of the nickel atom and the cobalt atom (denoted by B) and the ruthenium atom (Ru) of the ruthenium compound. R
When represented by u), the molar ratio (B / Ru) is usually 0.0
It is preferable to select it in the range of 1 to 30, preferably 0.1 to 30, and more preferably 0.1 to 10. Here, if the molar ratio (B / Ru) is less than 0.01 or 0.1, the proportion of nickel or cobalt decreases, and the effect of improving the activity by these components cannot be obtained as expected. is there. On the other hand, this molar ratio (B / R
Even if u) is set to be larger than 30 or 10, the amount of ruthenium becomes relatively small, and the carbon activity is high even if the ruthenium-containing hydrocarbon has a high activity as a steam reforming catalyst and the steam / carbon ratio is low. There is a risk that the effect of suppressing

The solution used in the present invention is usually prepared so as to uniformly dissolve each compound. However, in the present invention, it is important that a part of the ruthenium compound and the zirconium compound are simultaneously dissolved in the solution at the same time, and a part thereof is a hydroxide-like sol or gel. Even if there is, since it is possible to support uniformly according to the amount that is uniformly dissolved, it is not excluded from the scope of the present invention to use a solution in which each compound is not completely and uniformly dissolved. Absent.

As a method for uniformly dissolving each compound, it is usually possible to lower the pH of the solution. Specifically, it is desirable to adjust the pH to 3 or less, preferably 1.5 or less. Here, if the pH of the solution is higher than 3 or 1.5, the zirconium compound is easily hydrolyzed, and a hydroxide-like sol or gel is easily formed. The hydroxide-like sol or gel formed in such a solution is difficult to form the complex-like compound with the ruthenium component as described above, so that the effect of improving dispersibility and the like cannot be achieved as expected. There is a risk.

Using the above solution, the solution is contact-impregnated with a suitable carrier, and at least a part or all of the ruthenium component, zirconium component, alkaline earth metal component, rare earth element component, and other components contained in the impregnating solution are added. A ruthenium catalyst can be produced by supporting a nickel or cobalt component used accordingly on the carrier and drying and calcining the resulting carrier composition as appropriate.

As the carrier, for example, γ-alumina, α
-Alumina such as various alumina, silica, titania, zirconia, single metal oxide such as magnesia, alumina boria, silica alumina, zeolite, silica zirconia, silica titania, titania alumina, mixed or composite metal such as silica magnesia Examples thereof include oxide-based ones, but not limited to these, and generally, any type and composition can be selected as a target. Alumina, particularly α-alumina, is preferably used. Alumina, especially α
-When alumina is used as the carrier, the ruthenium component and the zirconium component are easily immobilized in the carrier when the solution and the carrier are in contact with each other. This is considered to be because the zirconium component reacts with the surface hydroxyl groups of alumina to form a bond with alumina, as described above.

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.

The impregnation-supporting operation by contacting the above-mentioned solution with the carrier can be carried out by a conventional method. For example, various commonly used impregnation methods (heat impregnation method, normal 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, or the like Any method such as a combination method may be used as long as the solution and the carrier are brought into contact with each other and supported. The series of operations of impregnating and supporting, drying and firing is performed at least once, but if necessary,
These operations may be divided into two or more and repeated multiple times.

Here, the ratio of the carrier to the solution used is the target loading ratio of the active metal component, the concentration of the metal compound in the aqueous solution used, the type of the impregnation supporting system, the pore volume and the specific surface area of the carrier used, etc. Although it cannot be uniformly determined because it depends on the carrier, at least an amount of a solution that sufficiently wets the carrier to be supported is used.On the other hand, the upper limit of the amount of the solution used with respect to the carrier is not particularly limited, but is usually The amount of the solution used is selected to be 100 ml or less per 100 g of the dry weight of the carrier to be used, preferably, the solution is reduced to a water absorption amount close to the inherent water absorption amount of the carrier, and more preferably a volume corresponding to the water absorption amount. Use a solution.

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

As described above, each component such as ruthenium can be uniformly supported on the carrier. Incidentally, 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 solution used may be supported, and, for example, excess at any point after the contact. It is also possible to carry out only a part of the ruthenium component in the solution used by removing such a solution.

The final loading amount of each loading component depends on the type of the carrier.
Properties such as type and surface area, or use of catalyst, that is, target
Select as appropriate in consideration of various conditions such as the type and nature of the reaction
do it. In many cases, loading based on carrier weight
The ruthenium component is converted to ruthenium metal
In general, 0.05 to 2% by weight, preferably 0.05 to
1% by weight, more preferably 0.1 to 1% by weight, zirconium
The um component is an oxide₂), It is usually 0.
05-20% by weight, preferably 0.05-15% by weight,
More preferably 1.0 to 15% by weight, alkaline earth metal
Component and rare earth element component are oxides (BeO, MgO, C
aO, SrO, BaO, RaO, SrO, Y₂O₃, La
₂O₃, CeO₂, Pr₆O₁₁, Nd₂O₃, Pm₂O₃, Sm
₂O₃, Eu₂O₃, Gd₂O₃, Tb₂O₃, Dy₂O₃, Ho
₂O₃, Er₂O₃, Tm₂O₃, Yb ₂O₃, Lu₂O₃)
The total amount is usually 0.05 to 5% by weight, preferably
0.05-2% by weight, more preferably 0.1-2% by weight
It is preferable to select the range. Also, the nickel component
And, when supporting cobalt components, these components
Is converted to nickel metal and cobalt metal and
0.05 to 5% by weight, preferably 0.05 to 2% by weight
%, More preferably 0.1 to 2% by weight.
Is preferred.

Drying after contacting the solution with the carrier is not particularly limited, but usually 50 to 150 ° C., preferably 1
It is carried out in the range of 00 to 120 ° C for 1 to 6 hours. When air-dried at room temperature, it is performed for about one day (24 hours). However, depending on the impregnation-supporting method, a large amount of water evaporates and a considerably dried state can be obtained. Therefore, in such a case, a separate drying operation is not necessarily required.

The above-mentioned calcination can also be carried out according to a conventional method, usually 400 to 80 in air or in an air stream.
0 ° C, preferably 450 to 800 ° C, more preferably 4
It is preferably carried out in the temperature range of 50 to 600 ° C. In addition,
In addition to air, an oxygen-containing gas such as pure oxygen or oxygen-enriched air may be substituted or used together. The firing time is usually 1 to
24 hours is enough.

If desired, 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 carried out by a conventional method, and if necessary, a suitable binder component may be added.

The ruthenium component, the zirconium component, the alkaline earth metal component and the rare earth element component in the catalyst obtained by this calcination, and the nickel component and the cobalt component which are optionally added are usually oxides or complex oxides. It is carried in the form of a product in the vicinity of each component in a highly dispersed state.

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 the catalytic reaction. You may use. 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.

Incidentally, this dispersive metallization treatment by hydrogen reduction is carried out.
Is, for example, H at 500 to 850 ° C. ₂Consumption of
It is preferable to reduce until it disappears.

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

As an example of such a catalytic reaction, for example,
Selective hydrogenation reaction of unsaturated compounds such as carbonyl compounds, aromatic compounds, olefins and dienes, ammonia synthesis reaction, FT synthesis reaction, CO or CO ₂ methanation reaction, CO or CO ₂ alcohol or other Selective hydrogenation reaction to oxygen-containing compounds, Homologation of methanol with CO and hydrogen to ethanol, Hydrocarbonylation reaction of olefins, Selective hydrogenation reaction of nitro compounds to amines, Hydrocracking reaction of hydrocarbons , Various hydrogenation reactions such as selective hydrogenation reaction of aromatic amines, NO _x reduction purification reaction, steam reforming reaction of hydrocarbons, complete oxidation reaction at low temperature or partial oxidation reaction, photolysis of water A wide variety of reactions such as reactions can be mentioned.

By the way, among such catalytic reactions, there is also a reaction in which the catalyst is prepared by impregnating and supporting it, and even if it is not necessarily fired at a high temperature as described above, a catalyst having sufficient performance can be obtained by drying at a low temperature. is there. That is, as a general method for producing the catalyst of the present invention, calcination does not necessarily have to be performed.

II. Hydrocarbon steam reforming reaction The present invention provides a hydrocarbon steam reforming method in which the excellent properties of the ruthenium catalyst obtained by the method of the present invention are most effectively utilized among the various types of catalytic reactions described above. It is provided. That is, the hydrocarbon steam reforming method of the present invention is characterized by using the ruthenium catalyst produced as described above.

The raw material hydrocarbon used in the present invention is not particularly limited and, for example, methane, ethane, propane, butane, pentane, hexane, heptane, octane, nona, decane and the like having a carbon number of about 1 to 16 can be used. Chain or branched saturated aliphatic hydrocarbon, cyclohexane,
Various hydrocarbons such as alicyclic saturated hydrocarbons such as methylcyclohexane and cyclooctane, and monocyclic and polycyclic aromatic hydrocarbons are used. Also, a mixture of two or more of the above various hydrocarbons is used. Other preferable examples include various hydrocarbons having a boiling point range of 250 ° C. or lower, such as city gas, LPG, naphtha, and kerosene. Further, in general, when a sulfur content is present in these raw material hydrocarbons, the sulfur content is usually 1
It is desirable to carry out desulfurization until it reaches about ppm. This is because if the sulfur content in the raw material hydrocarbon exceeds about 1 ppm, the catalyst may be deactivated. The desulfurization method is not particularly limited, but hydrodesulfurization, adsorptive desulfurization and the like are performed.

There is no particular limitation on the steam that is reacted with the hydrocarbon.

When reacting a hydrocarbon with steam, the amount of hydrocarbon and the amount of steam are usually adjusted so that the steam / carbon ratio is 1.5 to 5, preferably 1.5 to 3, and more preferably 2 to 3. Is preferably determined. With such a steam / carbon ratio, a product gas having a high hydrogen content can be efficiently obtained. In the steam reforming method of the present invention, carbon precipitation can be suppressed even when the steam / carbon ratio is 3 or less, so that exhaust heat can be effectively used.

The reaction temperature is generally 400 to 900 ° C, preferably 600 to 900 ° C, more preferably 650 to 8 ° C.
It is 00 ° C.

The reaction pressure is usually 0 to 30 kg / cm ^2.
G, preferably 0 to 10 kg / cm ² G.

The reaction system may be either a continuous flow system or a batch system, but a continuous flow system is preferred.

When the continuous flow system is adopted as the reaction system
Gas velocity of mixed gas of hydrocarbon and water vapor (G
HSV) is usually 1,000 to 40,000 h^-1, Good
More preferably 2,000-40,000h^-1, More preferably
Is 2,000-20,000h ^-1Is.

The reaction system is not particularly limited and may be a fixed bed system, a moving bed system, a fluidized bed system or the like.
The form of the reactor is not particularly limited, and for example, a tubular reactor can be used.

A mixture of hydrogen, methane, carbon monoxide and the like can be obtained by reacting hydrocarbons and steam under the conditions as described above. The obtained mixture can be directly used for various purposes, or can be separated into each gas component and provided for each purpose. INDUSTRIAL APPLICABILITY The steam reforming method of the present invention is particularly suitable for a hydrogen production process of a fuel cell, and a mixture containing 50% by volume or more of hydrogen can be obtained.

[0066]

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: containing 38% Ru), zirconium oxychloride (ZrOCl)
₂ · 8H ₂ O) _6.54g and magnesium nitrate (Mg
(NO ₃₎ the ₂ · 6H ₂ O) 6.36g was dissolved in water 20
It was an aqueous solution of cc. This aqueous solution was stirred with a stirrer for 1 hour or more to obtain an impregnating solution. The color of the impregnating liquid at this time was reddish orange, and the pH was 0.5 or less.

Using 10 cc of this impregnating solution, α-
50 g of an alumina molded body carrier (5 mm diameter cylindrical type) was impregnated and supported by the pore filling method. The color of the carrier immediately after impregnation was orange. After carrying, it was dried at 120 ° C. for 5 hours, and the color of the carrier became green. Further, firing was performed in air at 500 ° C. for 2 hours. The color of the carrier after firing was gray.

Next, the remaining impregnating solution 10 cc was used to carry out impregnation, drying and calcination on the calcined carrier again in the same procedure as described above to obtain the final catalyst. The color change of the molded body after each step was the same as above.

The contents of ruthenium, zirconium and magnesium in the composition of the obtained catalyst were determined as Ru:
0.5% by weight, ZrO ₂ : 5.0% by weight, MgO: 2.
It was 0% by weight.

This catalyst 6 cc was filled in a quartz tube type reaction tube having an inner diameter of 20 mm. In a reaction tube, the catalyst is passed through a hydrogen stream (H ₂
GHSV of gas: 1000 h ⁻¹ ), after reduction treatment with hydrogen at 600 ° C. for 2 hours, reaction conditions, 650 ° C. (catalyst layer outlet temperature), n-butane GHSV: 1000
The steam reforming reaction of n-butane was carried out by introducing n-butane and steam under the conditions of h ⁻¹ and steam / carbon ratio (S / C) = 3.0. Table 1 shows the reaction results.

Further, this catalyst 6 cc was filled in a reaction tube similar to the above, the same hydrogen reduction treatment was carried out, and then the reaction condition 7
00 ° C (catalyst layer outlet temperature), GHSV of n-butane: 1
000h ^-1 , steam / carbon ratio (S / C) = 1.8
Under the condition of 5, n-butane and steam were introduced to carry out a steam reforming reaction of n-butane. The reaction results are shown in Table 2.

In any of the steam reforming reactions, the composition analysis of the produced gas was carried out by gas chromatography.

Example 2 Instead of magnesium nitrate, calcium nitrate (Ca (N
O ₃₎ performs the same operation as in Example 1 except for using ₂ · 4H ₂ O) _4.21g, to prepare a catalyst. As in Example 1, the color of the impregnating liquid was reddish orange and the pH was 0.5 or less. The contents of ruthenium, zirconium and calcium in the composition analysis of the obtained catalyst were Ru: 0.5% by weight, ZrO ₂ : 5.0% by weight, CaO: 2.0% by weight.
Met.

Using the obtained catalyst, hydrogen reduction of the catalyst and steam reforming reaction of n-butane were carried out in the same manner as in Example 1. The reaction results are shown in Tables 1 and 2.

Example 3 Yttrium nitrate (Y (N
O ₃₎ performs the same operation as in Example 1 except for using ₂ · 6H ₂ O) 0.71g, to prepare a catalyst. The impregnating liquid was reddish orange and had a pH of 0.5 or less. The contents of ruthenium, zirconium and yttrium in the composition of the obtained catalyst were Ru: 0.5% by weight, ZrO ₂ : 5.
It was 0% by weight and Y ₂ O ₃ : 1.0% by weight.

Using the obtained catalyst, hydrogen reduction of the catalyst and steam reforming reaction of n-butane were carried out in the same manner as in Example 1. The reaction results are shown in Tables 1 and 2.

Example 4 Instead of magnesium nitrate, lanthanum nitrate (La (NO
₃)₂・ 6H₂O) Example 1 except that 0.67 g was used
The same operation as above was performed to prepare a catalyst. Impregnation liquid is red-orange
And pH was 0.5 or less. The resulting catalyst set
Analysis of ruthenium, zirconium and lanthanum
The content is Ru: 0.5% by weight, ZrO ₂: 5.0 weight
%, La₂O₃Was 1.0% by weight.

Using the obtained catalyst, hydrogen reduction of the catalyst and steam reforming reaction of n-butane were carried out in the same manner as in Example 1. The reaction results are shown in Tables 1 and 2.

Example 5 In addition to the supporting component used in Example 1, cobalt nitrate was further added.
(Co (NO₃)₂・ 6H ₂O) water-soluble with 2.47 g added
Prepare 20 cc of liquid and stir with a stirrer for 1 hour or more.
The same operation as in Example 1 except that
Then, the catalyst was prepared. The impregnation liquid is reddish orange and has a pH of
It was 0.5 or less. The composition of the obtained catalyst was analyzed by
Of tenium, cobalt, zirconium and magnesium
The contents are Ru: 0.5% by weight, Co: 1.0% by weight,
ZrO₂: 5.0 wt%, MgO: 2.0 wt%
Was.

Using the obtained catalyst, hydrogen reduction of the catalyst and steam reforming reaction of n-butane were carried out in the same manner as in Example 1. The reaction results are shown in Tables 1 and 2.

Further, an X-ray micro analyzer (EPM
Fracture surface of the above catalyst after hydrogen reduction using A) (Fig. 1)
FIG. 2 shows the results of examining the distributions of Ru, Co, Zr, Mg, and Al. As can be seen from FIG. 2, the distribution of each component in the alumina carrier is extremely well matched, and it is presumed that each component is supported in the vicinity.

Example 6 In addition to the supporting component used in Example 1, nickel nitrate was further added.
(Ni (NO₃)₂・ 6H ₂O) water-soluble with 2.48 g added
Prepare 20 cc of liquid and stir with a stirrer for 1 hour or more.
The same operation as in Example 1 except that
Then, the catalyst was prepared. Color of impregnating liquid, pH,
The color and its change were the same as in Example 1. Got
Ruthenium, nickel, zirconium by composition analysis of catalyst
The content of um and magnesium is Ru: 0.5 wt.
%, Ni: 1.0 wt%, ZrO₂: 5.0% by weight, M
gO: 2.0% by weight.

Using the obtained catalyst, hydrogen reduction of the catalyst and steam reforming reaction of n-butane were carried out in the same manner as in Example 1. The reaction results are shown in Tables 1 and 2.

Example 7 Aqueous solution of zirconium oxychloride (ZrO (OH) Cl) marketed by Daiichi Rare Elements Industry Co., Ltd. (35% by weight in terms of zirconia; trade name: Zircosol ZC-2) 7. 10 g of ruthenium chloride (RuCl ₃
・ 0.66 g of nH ₂ O, magnesium nitrate (Mg (N
_{O 3) 2 · 6H 2 O} ) 6.36g and cobalt nitrate (Co
_{(NO 3) 2 · 6H 2} O) was dissolved 2.47 g,
The total amount of solution was 10 cc. This solution was stirred for 1 hour or more with a stirrer to obtain an impregnating solution. The color of the impregnating liquid at this time was reddish orange, and the pH was 0.5 or less.

This impregnating solution was impregnated and carried on 50 g of the same α-alumina carrier as used in Example 1 by the pore filling method. The color of the supporting carrier immediately after the impregnation supporting was orange. After supporting, it was dried at 120 ° C. for 5 hours, and the color of the supported catalyst became green. Further, it was calcined in air at 500 ° C. for 2 hours to obtain a final catalyst. The content of ruthenium, cobalt, zirconium and magnesium by the composition analysis of the obtained catalyst was Ru: 0.5% by weight, C
o: 1.0 wt%, ZrO ₂ : 5.0 wt%, MgO:
It was 2.0% by weight.

By using the above zirconium source, the concentration of the impregnating liquid could be increased, and as a result, the number of impregnations could be reduced to once.

Using the obtained catalyst, hydrogen reduction of the catalyst and steam reforming reaction of n-butane were carried out in the same manner as in Example 1. The reaction results are shown in Tables 1 and 2.

Comparative Example 1 Ruthenium chloride (RuCl ₃ .nH ₂ O) 0.66 g, zirconium oxychloride (ZrOCl ₂ .8H ₂ O) 6.5
4 g was dissolved in water to give a 20 cc aqueous solution. This aqueous solution was stirred with a stirrer for 1 hour or more to obtain an impregnating solution. At this time, the color of the impregnating liquid was reddish orange, and the pH was 0.1.
It was 5 or less.

Using 10 cc of this impregnating solution, 50 g of the same α-alumina carrier as used in Example 1 was impregnated and carried by the pore filling method. The color of the carrier immediately after impregnation is
It was orange. After carrying, it was dried at 120 ° C. for 5 hours, and the color of the carrier became green. Further, firing was performed in air at 500 ° C. for 2 hours. The color of the carrier after firing was gray.

Then, the remaining impregnating solution 10 cc was used to carry out impregnation, drying and calcination on the calcined carrier again in the same procedure as described above to obtain a final catalyst. The color change of the molded body after each step was the same as above.

The content of ruthenium and zirconium in the catalyst obtained by compositional analysis was Ru: 0.5% by weight, Z
rO ₂ : It was 5.0% by weight.

Using the obtained catalyst, hydrogen reduction of the catalyst and steam reforming reaction of n-butane were carried out in the same manner as in Example 1. The reaction results are shown in Tables 1 and 2.

Results of Reaction Evaluation Table 1 shows the results of the steam reforming reaction of n-butane at the initial stage of the reaction (5 hours after the start of the reaction) in each Example and Comparative Example under the reaction conditions shown in the table. The n-butane conversion rate is defined by the following equation. n-Butane conversion (%) = [(CO + CO ₂ + CH ₄ ) /
(CO + CO ₂ + CH ₄ + C ₂₊ )] × 100 As can be seen from Table 1, in Examples 1 to 6, C ₂₊ was not detected in the produced gas, and the n-butane conversion rate was 100%. On the other hand, in Comparative Example 1, C ₂₊ was detected and the n-butane conversion rate was 96%. As is clear from these results, in comparison with the catalyst of the example using a ruthenium component, zirconium and a component selected from alkaline earth metal components and rare earth element components as essential components in the catalyst preparation, the alkaline earth metal component and It can be seen that the catalyst of Comparative Example, which did not use any of the rare earth element components, has a low steam reforming activity of n-butane. In addition, in Examples 4 to 6 in which a cobalt or nickel component was further added to the above essential components in the catalyst preparation, the CH ₄ concentration in the produced gas was lower than that in Example 1 in which they were not added. Since it is close to the equilibrium composition at the same temperature, it is understood that the steam reforming activity of n-butane of the ruthenium catalyst is increased by adding the cobalt component or the nickel component.

Table 2 shows n values after 5 hours and 20 hours after the start of the reaction in each Example and Comparative Example under the reaction conditions shown in the table.
-Shows the results of the steam reforming reaction of butane.

As can be seen from Table 2, Comparative Example 1 using a ruthenium catalyst prepared without using an alkaline earth metal such as magnesium or a rare earth element such as yttrium.
In, the decrease of the n-butane conversion rate with time is recognized.
After the reaction, when each catalyst was examined and carbon deposition was not observed in any of them, it is presumed that this activity decrease in Comparative Example 1 is caused by thermal deterioration of the supported component. From these, it was confirmed that the introduction of the alkaline earth metal or the rare earth element not only improves the activity of the ruthenium catalyst, but also improves the heat resistance.

[0097]

[Table 1]

[0098]

[Table 2]

[0099]

According to the method for producing a ruthenium catalyst of the present invention, the ruthenium component can be effectively supported in a highly dispersed state on the carrier in the vicinity of the zirconium component in a highly dispersed state by a simple impregnation operation, It is possible to obtain a ruthenium catalyst whose activity is further improved by the presence of the alkaline earth metal component and the rare earth element component, and which maintains a highly dispersed state thereof stably even by calcination or reaction at high temperature.
Further, by using by adding a cobalt or nickel component as a supporting component in the production method of the present invention,
It is possible to obtain a highly activated ruthenium catalyst.
That is, according to the present invention, it is possible to obtain various kinds of ruthenium catalysts which have a high activity per the starting ruthenium component and the contained ruthenium and are excellent in heat resistance, and which sufficiently maintain the high activity even at a high temperature. The method for steam reforming of hydrocarbons of the present invention using the ruthenium catalyst produced by the above method is also extremely advantageous in terms of cost. Precipitation is suppressed, and the activity of the catalyst is sufficiently maintained, which enables stable and efficient operation.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a scanning direction of EPMA line analysis of a catalyst cross section.

FIG. 2 is a chart showing the EPMA analysis results of the catalyst of Example 4.

[Explanation of symbols]

 1 catalyst 2 cross section 3 actual scanned portion (on line) 4 EPMA line analysis scanning direction

Claims (8)

[Claims] 1. A method for producing a ruthenium catalyst, which comprises bringing a carrier into contact with a solution containing a ruthenium compound, a zirconium compound, and at least one compound selected from an alkaline earth metal compound and a rare earth element compound. 2. The method according to claim 1, wherein the ruthenium catalyst is a hydrocarbon steam reforming catalyst. 3. The method according to claim 1, wherein the solution further contains at least one compound selected from nickel compounds and cobalt compounds. 4. The method according to claim 1, wherein the ruthenium compound is ruthenium chloride and the zirconium compound is zirconium oxychloride. 5. The method according to claim 1, wherein the alkaline earth metal is Mg or Ca and the rare earth element is Y or La. 6. The method according to claim 1, wherein the support is alumina. 7. The ruthenium compound is ruthenium chloride, the zirconium compound is zirconium oxychloride, the alkaline earth metal is Mg or Ca, and the rare earth element is Y or La. Method. 8. A steam reforming method for hydrocarbons, which comprises using the ruthenium catalyst obtained by the method according to any one of claims 1 to 7.