JPH05220397A - Steam reforming catalyst for hydrocarbon - Google Patents

Abstract

PURPOSE:To obtain a catalyst having high activity and, at the same time, withstanding for use in a steam reforming reaction of a higher hydrocarbon by adding a zirconia sol to a Ru.Al2O3 series catalyst. CONSTITUTION:The catalyst is prepared by carrying a zirconia sol as a precursor of zirconia on an Al2O3 carrier, calcining, attaching ruthenium chloride and calcining, and as necessary an alkaline earth metal oxide may be added to the catalyst.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a catalyst for producing synthesis gas or hydrogen by steam reforming hydrocarbons.

[0002]

2. Description of the Related Art A reaction for reforming a hydrocarbon with steam is industrially carried out on a large scale as a reaction for producing synthesis gas or hydrogen. Nickel-based catalysts are generally used in this reaction, but when reforming higher hydrocarbons with steam, carbon precipitation is likely to occur, or the steam / carbon ratio is set to save energy. If the amount is reduced, carbon precipitation also becomes an obstacle, so improvements have been attempted.

On the other hand, noble metal catalysts are said to be less likely to cause carbon deposition, and attempts have been made to develop them as alternatives to nickel catalysts, and catalysts containing rhodium or ruthenium as the main component have been mainly studied and are particularly effective. Various ruthenium-based catalysts have been proposed.

Ruthenium is used by supporting a metal on a carrier for the reason that it is an expensive metal, or it is necessary to increase the surface area for its effective use. Alumina is used as the carrier. Zirconia or the like is used. Alumina is used as many catalyst carriers, and has a long history of industrial use as a nickel catalyst carrier for steam reforming of hydrocarbons. Although research has been conducted, its performance is the same level as nickel-based catalysts, and carbon precipitation prevention measures are required for use in steam reforming of higher hydrocarbons, and the addition of various promoter components is being considered. Has been done.

For example, as a co-catalyst component for forming a catalyst resistant to steam reforming of higher hydrocarbons, JP-A-56-081 has been used.
No. 392 discloses the addition of cerium oxide.
JP-A-038239 discloses the addition of barium oxide, and British Patent GB1301836 discloses the addition of an alkaline earth metal oxide as a co-catalyst component for producing a catalyst in which carbon precipitation is suppressed. -004232 proposes addition of alkali, alkaline earth metal oxides and silica, and JP-A-60-147242 proposes addition of lanthanum oxide and silver oxide, respectively. Inferior to the zirconia-supported catalyst.

On the other hand, zirconia has not been industrially used as a catalyst carrier, but it is said to have an action of activating H ₂ O, especially for fuel cells by steam reforming hydrocarbons. As a hydrogen production catalyst, various uses for a ruthenium catalyst carrier have been studied, and among them, various promoter components have been added to form a highly active catalyst, a catalyst that can withstand higher hydrocarbon steam reforming, or a catalyst that suppresses carbon deposition. For example, in European Patent EP-406896, addition of cobalt or manganese is added, in EP-414573, addition of yttrium oxide, and in JP-A-2-2879, addition of nickel, lanthanum and other metals. However, JP-A-2-43950 proposes the addition of yttrium oxide, magnesium oxide and cerium oxide, respectively. It is expensive, poor in moldability, there is a problem such that mechanical strength is low.

[0007]

Alumina has properties suitable for a hydrocarbon steam reforming catalyst carrier, such as low cost, high heat resistance, and excellent mechanical strength, and thus it can be used as a ruthenium catalyst carrier for reforming. However, its reforming activity is about the same level as nickel-based catalysts, and for practical use it is necessary to make it a catalyst with high activity that is suitable for its price. In order to make use of these characteristics to make a higher hydrocarbon steam reforming catalyst that can withstand actual use, it is necessary to make the catalyst more resistant to carbon precipitation.

[0008]

The inventor of the present application has been researching hydrocarbon steam reforming catalysts for some time, and as a part of this research, noble metal catalysts tend to cause carbon precipitation. While paying attention to the above, we have tried to put it into practical use, and tried to add various cocatalysts by selecting alumina as the carrier.

On the other hand, zirconia is said to have a property of activating H ₂ O, and it was studied to add zirconia as a promoter.

Zirconyl nitrate is generally used as a raw material for zirconia. First, its addition to an alumina carrier was examined, but a highly active catalyst was not obtained. However, it was expected that an attempt was made to add zirconia sol to alumina. A catalyst exhibiting the above high activity was obtained. That is, a catalyst obtained by supporting zirconyl nitrate as a usual zirconia raw material on alumina, firing and then supporting ruthenium is not only low in activity for a hydrocarbon steam reforming reaction, but also at a reaction temperature. However, the catalyst obtained by adding ruthenium after adding zirconia sol and calcining shows high activity, and the activity of zirconia itself was increased. Not only does it have the same activity as the catalyst obtained by using it as a carrier, it also shows stable activity at high temperatures, and it has excellent performance in steam reforming of higher hydrocarbons. The present invention has been completed by confirming that the catalyst does not easily cause

The amount of zirconia sol added is 0.2 to 20.0 when expressed as zirconia based on the total weight of the carrier.
wt%, preferably 0.5 to 10.0 wt% is necessary. If the added amount is 0.2 wt% or less, the effect of the zirconia as a co-catalyst is insufficient, and 20.0 wt%.
If the content is more than 0.1%, not only the effect of the cocatalyst corresponding to the added amount cannot be expected, but also the carrier becomes expensive, and the exfoliation of the supported zirconia cannot be ignored.

Since the zirconia sol is added as a co-catalyst, it is preferable that the zirconia sol is present on the surface of the catalyst. Also, by selectively attaching the zirconia sol to the surface, the expensive zirconia sol can be effectively utilized, and therefore, the alumina carrier is used. Is preferably added by immersing in a zirconia sol, and as another addition method, zirconia sol addition is also possible by kneading alumina or alumina precursor powder with zirconia sol, and then molding, but practical It cannot be a preferred carrier.

The zirconia sol has a spherical particle shape, a shape in which spheres are connected in a straight line, or the like. Any shape sol can be used, but the latter sol is required. Is preferred, and the particle size is 5
0-2,000 Angstroms, preferably 100-
The PH region is 1,000 angstroms and the zirconia sol is stabilized. The PH region may be on the acidic side, neutral side or alkaline side.

The zirconia sol may be added to the carrier simply by immersing the carrier in the zirconia sol.
The wt% sol aqueous solution can be used as it is,
If necessary to adjust the amount of zirconia added, immersing the carrier in the sol may be repeated by adding a drying operation in the middle.If a small amount may be added, the zirconia sol should be diluted with pure water before use. After completion of the addition of a predetermined amount of zirconia sol, it is dried and then calcined at 400 to 900 ° C. for several hours.

As the carrier, a usual inorganic heat-resistant oxide other than alumina can be used, but an alumina carrier is preferred in consideration of price, industrial performance as a hydrocarbon steam reforming reaction catalyst carrier, etc. Although it is possible to use alumina having any crystal structure as long as it is a conventionally used alumina carrier, the structure does not change even at a high temperature, and α / alumina which is inactive is preferable, The carrier is used as a tablet, an extrudate or a spherical molded product.

The alkaline earth metal oxide as the second promoter component is an oxide of magnesium, calcium, barium or the like, preferably calcium or barium oxide, and the addition amount thereof is 2.0 to 50.0 wt. %, Preferably 5.0 to 30.0 wt%, 2.0 wt
%, The effect is insufficient, and 50.0 wt%
With the above, it is not possible to obtain a carrier having sufficient mechanical strength, and addition of an alkaline earth metal oxide to aluminum hydroxide which is a precursor thereof before forming an alumina carrier,
A method of adding and mixing an alkaline earth metal compound, or a method of immersing the carrier in an aqueous solution of alkaline earth metal compound before adding the zirconia sol to the carrier, or dissolving the alkaline earth metal compound in the sol aqueous solution when adding the zirconia sol. However, it is possible to use a method of simultaneously attaching to the alumina carrier, drying after completion of the attaching operation, and then 700 to 135
Bake for several hours at 0 ° C.

It is preferable to form a compound with the alkaline earth metal oxide and alumina, and at a temperature of 700 ° C. or lower, it cannot be a good carrier because of insufficient compound formation, and at a temperature of 1350 ° C. or higher, alumina is sintered. Therefore, the surface area becomes too small to obtain a suitable carrier.

Ruthenium is then impregnated onto the alumina carrier to which zirconia and an alkaline earth metal compound have been added. It is essential for effective utilization that ruthenium as the catalytically active component is concentrated on the carrier surface. As the method, any method capable of supporting ruthenium on the surface such as an impregnation method, an immersion method or a spray method can be used, and the ruthenium raw material is a ruthenium halogen compound, ruthenium acid salt, etc. Any compound can be used as long as it is a water-soluble compound and does not leave a catalyst poison that does not remain in the catalyst after calcination.
It is baked at 700 ° C. for 2 to 4 hours, and the amount of ruthenium added is 0.02 to 5.0 wt%, preferably 0.05 to 2.0.
The content is required to be wt%, and if the amount is 0.02 wt% or less, the activity is insufficient, and if it is 5.0 wt% or more, it is an expensive catalyst which is more expensive than it is required to improve the activity, which is not economical.

The catalyst needs to be reduced before being used in the reaction, but it may be reduced in either liquid phase or gas phase. In the case of liquid phase reduction, an aqueous solution of potassium formate, formalin, hydrazine, sodium boron hydride, etc. is used. 40 ~
It can be reduced under heating at 80 ° C, and in the case of gas phase reduction, the catalyst can be kept at 100 to 600 ° C and hydrogen gas can be reduced while flowing.

The catalyst thus obtained was packed in an atmospheric pressure type reactor, and its performance was evaluated by a methane steam reforming reaction. As a result, it showed a very high activity, and was significantly superior to a catalyst using alumina itself as a carrier. The catalyst which was active and which contained the alkaline earth metal compound as the second component showed a higher activity, but when the reaction product was evaluated by changing it to a higher hydrocarbon, it was highly active and showed stable performance. While the increase in pressure loss during the reaction was not observed at all, the catalyst using alumina itself as a carrier had a considerably low activity and a slight increase in pressure loss during the reaction was observed, showing stable performance. Did not have.

[0021]

By adding a zirconia sol as a specific zirconia precursor to a Ru.Al ₂ O ₃ catalyst, its activity can be remarkably improved, and an alkaline earth metal as a second promoter component can be obtained. By adding an oxide, the performance can be further enhanced, and in addition, a catalyst having high activity even in the steam reforming reaction of higher hydrocarbons and having stable performance without showing an increase in pressure loss during the reaction can be obtained.

[0022]

EXAMPLES Next, the contents of the present invention will be specifically described by way of examples, but the performance evaluation described therein was carried out under the following conditions.

Methane steam reforming reaction performance evaluation conditions Catalyst usage amount 25 cc Catalyst size 3/16 in × 3/16 in (tabletting product) CH ₄ space velocity 1,200 hr ^-1 steam / CH ₄ 3.0 (molar ratio) Pressure Normal pressure Reaction temperature 550 to 750 ° C. Reaction time 2 hours at each measurement temperature CH ₄ conversion (%) showing the performance of the catalyst was calculated by the following formula.

[0024] n-Hexane steam reforming reaction performance evaluation conditions Catalyst usage 25 cc Catalyst size 3/16 in x 3/16 in (tablet) Outlet total gas space velocity 5,000 hr ^-1 steam / carbon 2.5 (molar ratio) Pressure Normal Pressure Reaction temperature 750 ° C. Reaction time 7 days CH ₄ conversion (%) showing the performance of the catalyst was calculated by the following formula.

[0025] Here, CO _out , CO concentration (%) C0 _{2 out at} the catalyst layer outlet side, C0 ₂ concentration (%) hexane _{out at} the catalyst layer outlet side, hexane concentration (%) CH _{4 out at} the catalyst layer outlet side, catalyst layer outlet CH ₄ concentration on the side (%) Further, in the n-hexane steam reforming reaction performance evaluation, hydrocarbon compounds were detected in addition to methane and hexane, but they were ignored because they were minute amounts.

Before the reaction is started, the catalyst supplies H ₂ with space velocity,
While circulating at 500 hr ^-1 , it was reduced at 500 ° C for 2 hrs. On the other hand, the mechanical strength of the catalyst was measured by a Kiya type hardness meter.

Example 1 A suitable amount of pure water was added to 500 g of aluminum hydroxide, kneaded in a kneader and dried, and then 15 g of graphite was added to a crushed product of 10 mesh pass,
After mixing, the mixture was tabletted into a size of 3/16 in x 3/16 in.
This tablet was placed in an electric furnace at 1,100 ° C. × 4 hrs. A catalyst carrier was prepared by firing (designated as carrier A).

Separately, 30w stabilized on the acidic side
150% t% zirconia sol was weighed in a 300 cc beaker, and 60 g of carrier A was added to the sol for 1.5 hr.
After immersing for 10 seconds at 110 ° C. for 20 hrs.
Dry, and subsequently in an electric furnace at 500 ° C. × 1 hr. It was baked (designated as carrier B).

Separately, ruthenium chloride was dissolved in pure water to prepare an aqueous solution having a ruthenium metal concentration of 3.8 wt%, which was prepared in advance.
c to the carrier B by spraying 38 g, followed by drying at 110 ° C. for 20 hrs and then 500 ° C. for 1 hr. in an electric furnace. By calcination, the catalyst of Example 1 was obtained, but a part of the alumina was converted to α-alumina by X-ray.

This catalyst has the following composition after hydrogen reduction: Ru 0.48 wt% ZrO ₂ 3.20 〃 Al ₂ O ₃ BALANCE The methane steam reforming performance evaluation results and physical property measurement results are shown in Table 1. Shows the results of n-hexane steam reforming performance evaluation-
2 respectively.

Example 2 Preparation of carrier A in Example 1 was carried out using aluminum hydroxide 5
A catalyst of Example 2 was prepared by the same treatment method as in Example 1 except that 30 g of calcium carbonate was added in addition to 00 g and the baking temperature of the tableted product was set to 900 ° C. This catalyst has the following composition after hydrogen reduction: Ru 0.49 wt% ZrO ₂ 3.14 〃 CaO 5.32 Al ₂ O ₃ BALANCE The methane steam reforming performance evaluation results and physical property measurement results are shown in Table 1. , N-hexane steam reforming performance evaluation results-
2 respectively.

Example 3 Preparation of carrier A in Example 1 was carried out using aluminum hydroxide 5
A catalyst of Example 3 was prepared by the same treatment method as in Example 1 except that 146 g of calcium carbonate was added in addition to 00 g, and the baking temperature of the tableting product was 1,250 ° C. The compound has formed and the catalyst had the following composition after hydrogen reduction:

Ru 0.51 wt% ZrO ₂ 3.76 〃 CaO 20.83 Al ₂ O ₃ BALANCE The methane steam reforming performance evaluation results and physical property measurement results are shown in Table 1, and n-hexane steam reforming performance evaluation. Table of results
2 respectively.

Example 4 In the preparation of the carrier B in Example 1, the same treatment method as in Example 1 was used except that the zirconia sol diluted to 10 wt% was used in the operation of immersing the carrier A in the zirconia sol. The catalyst of 4 was prepared. This catalyst has the following composition after hydrogen reduction: Ru 0.47 wt% ZrO ₂ 0.97 〃 Al ₂ O ₃ BALANCE The methane steam reforming performance evaluation results and physical property measurement results are shown in Table 1. ..

Example 5 The catalyst of Example 5 was prepared by the same treatment method as in Example 1 except that 30 wt% concentration of zirconia sol stabilized on the alkaline side was used in the preparation of carrier B in Example 1. .. This catalyst has the following composition after hydrogen reduction: Ru 0.50 wt% ZrO ₂ 5.71 〃 Al ₂ O ₃ BALANCE The methane steam reforming performance evaluation results and physical property measurement results are shown in Table 1. ..

Example 6 210 g of calcium nitrate was dissolved in 100 cc of pure water in the middle of the operation for preparing carrier B from carrier A in Example 1, and 60 g of carrier A was immersed in an aqueous solution of calcium nitrate prepared in advance. , And then 110 ° C. × 20 hrs. After drying, 900 ° C. × 2 hrs. The catalyst of Example 6 was prepared by the same treatment method as in Example 1 except that it was calcined.

This catalyst has the following composition after hydrogen reduction: Ru 0.48 wt% ZrO ₂ 3.16 〃 CaO 14.34 〃 Al ₂ O ₃ BALANCE The methane steam reforming performance evaluation results and physical property measurement results are as follows. The results are shown in Table 1.

Example 7 Preparation of carrier A in Example 1 was carried out using aluminum hydroxide 5
The catalyst of Example 2 was prepared by the same treatment method as in Example 1 except that 20 g of barium carbonate was added in addition to 00 g.
This catalyst has the following composition after hydrogen reduction: Ru 0.49 wt% ZrO ₂ 3.17 〃 BaO 5.02 Al ₂ O ₃ BALANCE The methane steam reforming performance evaluation results and physical property measurement results are shown in Table 1. , N-hexane steam reforming performance evaluation results-
2 respectively.

Example 8 In Example 1, the concentration was changed to 1.5 wt% instead of the ruthenium chloride aqueous solution having a ruthenium metal concentration of 3.8 wt%.
% Example 1 except that a 1% ruthenium chloride aqueous solution was used.
The catalyst of Example 8 was prepared by the same treatment method as described above. This catalyst has the following composition after hydrogen reduction: Ru 0.19 wt% ZrO ₂ 3.12 Al ₂ O ₃ BALANCE The methane steam reforming performance evaluation results and physical property measurement results are shown in Table 1. ..

Comparative Example 1 The catalyst of Comparative Example 1 was prepared by the same treatment method as in Example 1 except that the operation of immersing the carrier A in the zirconia sol aqueous solution was not carried out. This catalyst has the following composition after hydrogen reduction: Ru 0.52 wt% Al ₂ O ₃ BALANCE The methane steam reforming performance evaluation results and physical property measurement results are shown in Table 1, and n-hexane steam reforming performance evaluation results. Table-
2 respectively.

Comparative Example 2 Preparation of Carrier A in Example 1 was carried out using aluminum hydroxide 5
In addition to 00g, 30g of calcium carbonate was added.
A catalyst of Comparative Example 2 was prepared by the same treatment method as that of Example 1 except that the operation of immersing the above in a zirconia sol aqueous solution was not performed. This catalyst shows the following composition after hydrogen reduction: Ru 0.50 wt% CaO 5.28 Al ₂ O ₃ BALANCE The methane steam reforming performance evaluation results and physical property measurement results are shown in Table 1, and n-hexane steam reformed. Table of quality performance evaluation results
2 respectively.

Comparative Example 3 In the preparation of carrier B in Example 1, instead of 150 cc of 30 wt% zirconia sol stabilized on the acidic side, a 15 wt% aqueous solution of zirconyl nitrate 1 converted to zirconia 1
The catalyst of Comparative Example 3 was prepared by the same treatment method as in Example 1 except that 50 cc was used.

This catalyst has the following composition after hydrogen reduction: Ru 0.50 wt% ZrO ₂ 3.53 〃 Al ₂ O ₃ BALANCE The methane steam reforming performance evaluation results and physical property measurement results are shown in Table 1. Met.

[0044]

[Table 1]

[0045]

[Table 2]

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[Procedure amendment]

[Submission date] June 22, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0007

[Correction method] Change

[Correction content]

[0007]

Alumina has properties suitable for a hydrocarbon steam reforming catalyst carrier, such as low cost, high heat resistance, and excellent mechanical strength, and thus it can be used as a ruthenium catalyst carrier for reforming. of but utilization has been studied, the reforming activity is Ri Oh at the same level and the nickel-based catalyst, for practical application is required to be formed with the catalyst having a high activity which attract each other in the price, also ruthenium To make a high-grade hydrocarbon steam reforming catalyst that can withstand the actual use by utilizing the characteristics of
It is required to form a catalyst that is less likely to cause carbon precipitation.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0008

[Correction method] Change

[Correction content]

[0008]

SUMMARY OF THE INVENTION The present inventors have come studied earlier than the hydrocarbon steam reforming catalyst, but the noble metal catalyst has a tendency to hardly cause carbon deposition as part I focused on and tried to put it into practical use,
Among them, alumina has been selected as a carrier, and attempts have been made to add various promoters.

[Procedure 3]

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[Correction method] Change

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[0010] As the raw material of zirconia is zirconyl nitrate are generally first was examined added to the alumina support, whereas high activity catalyst was obtained, attempts to addition to the zirconia sol alumina As a result, a catalyst having a higher activity than expected was obtained. That is, a catalyst obtained by supporting zirconyl nitrate as a usual zirconia raw material on alumina, firing and then supporting ruthenium is not only low in activity for a hydrocarbon steam reforming reaction, but also at a reaction temperature. However, the catalyst obtained by adding ruthenium after adding zirconia sol and calcining shows high activity, and the activity of zirconia itself was increased. Not only does it have the same activity as the catalyst obtained by using it as a carrier, it also shows stable activity at high temperatures, and it has excellent performance in steam reforming of higher hydrocarbons. The present invention has been completed by confirming that the catalyst does not easily cause

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction content]

The amount of zirconia sol added is 0.2 to 20.0 when expressed as zirconia based on the total weight of the catalyst.
wt%, preferably 0.5 to 10.0 wt% is necessary. If the added amount is 0.2 wt% or less, the effect of the zirconia as a co-catalyst is insufficient, and 20.0 wt%.
If the content is more than 0.1%, not only the effect of the cocatalyst corresponding to the added amount cannot be expected, but also the carrier becomes expensive, and the exfoliation of the supported zirconia cannot be ignored.

[Procedure Amendment 5]

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[0013] zirconia sol as its particle shape is spherical, or ball has such a shape that linearly connected, is a sol of any shape can be used, it is sol of the latter shape Is preferred, and the particle size is 5
0-2,000 Angstroms, preferably 100-
The PH region is 1,000 angstroms and the zirconia sol is stabilized. The PH region may be on the acidic side, neutral side or alkaline side.

[Procedure correction 6]

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[Correction target item name] 0017

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The earth alkali metal oxide and preferably be a compound generate the alumina, the alumina at 700 ° C. without obtaining good carrier and talk insufficient to compound raw formed at a temperature below also 1350 ° C. or higher Due to the progress of sintering, the surface area becomes too small to obtain a suitable carrier.

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[0024] n-Hexane steam reforming reaction performance evaluation condition Catalyst usage amount 25CC Catalyst size 3/16 in x 3/16 in (tablet product) Outlet total gas space velocity 5,000 hr ^-1 steam / carbon 2.5 (molar ratio) Pressure Normal Pressure Reaction temperature 750 ° C. Reaction time 7 days The n-hexane conversion rate (%) showing the performance of the catalyst was calculated by the following formula.

Claims (5)

[Claims] 1. A carbonization comprising aluminum oxide containing alkaline earth metal aluminate or aluminum oxide itself as a carrier, zirconium oxide having zirconia sol as a precursor supported thereon as a co-catalyst, and ruthenium as an active ingredient. Hydrogen steam reforming catalyst. 2. A catalyst having a zirconium oxide content of 100%.
The catalyst according to claim 1, which is 0.2 to 20 parts by weight with respect to parts by weight. 3. The catalyst according to claim 1, wherein the ruthenium content is 0.02 to 5.0 parts by weight based on 100 parts by weight of the catalyst. 4. The alkaline earth metal component in the alkaline earth metal aluminate is one or more selected from calcium, barium and magnesium, and the alkaline earth metal is 2 in terms of oxide per 100 parts by weight of the carrier. The catalyst according to claim 1, which is from 0.0 to 50 parts by weight. 5. The method for producing a catalyst according to claim 1, wherein a zirconium sol is impregnated on an aluminum oxide or aluminum oxide support containing an alkaline earth metal aluminate, then a ruthenium compound is impregnated, and then calcined.