JP2559715B2 - Heat resistant catalyst for catalytic combustion reaction and method for producing the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to a heat-resistant catalyst, particularly a catalyst used in a reaction such as catalytic combustion, and a method for producing the same.

(Prior Art) Currently used catalysts have a working temperature of, for example, usually 200 to 600 ° C in a petrochemical process, and about 750 ° C in a steam reforming process used at the highest temperature.
Is. A catalytic converter has come to be used for automobile exhaust gas purification, but in this case it is controlled at about 850 ° C. Even in the future, there are methanation reaction and catalytic combustion reaction that have recently attracted attention, and in some cases, the catalyst must maintain its activity even at a temperature exceeding 1000 ° C. Under these circumstances, it has been desired to develop a catalyst having high heat resistance (high activity, capable of maintaining high specific surface area even at high temperature).

In particular, the catalytic combustion method, which promotes the reaction of fuel and oxygen using a catalyst, is (1) capable of complete combustion at a low temperature, and (2) has a wide range of fuel / air ratios as compared with conventional combustion methods. It has been attracting attention because of its features such as complete combustion with (3) little generation of thermal NOx.

On the other hand, in order to establish the technology of the catalytic combustion method, it is indispensable to develop a catalyst that is active at a low temperature and can withstand a high temperature, and efforts are being made at various places for that purpose. Moreover, since the adoption of a heat-resistant catalyst carrier is the most effective means for developing a heat-resistant catalyst, the search for a heat-resistant carrier is also of particular interest today.

Among the catalyst carriers used so far, alumina has the highest heat resistance. γ-alumina is about
It has a specific surface area of 200m ² / g, and even if it is baked at about 1000 ℃, it is about 5
It maintains a high specific surface area of 0 m ² / g or more, but when baked at about 1200 ° C, the transition from γ-alumina to α-alumina and rapid sintering occur, and the specific surface area becomes about 5 m ² / g or less. I will end up. When fired at 1300 ℃, the specific surface area is 1m ² / g.
The following is no longer valid as a carrier. Therefore, for the purpose of increasing the heat resistance of alumina at high temperatures,
Attempts have been made to add the second component to alumina and further to form a composite.

It is known to improve the catalyst by adding an oxide of an alkaline earth metal to a nickel supported catalyst having alumina as a carrier. For example, Japanese Examined Patent Publication No. 44-17737 discloses "UK Patent 96963.
In No. 7, the proportion of the alkali compound added is preferably 0.7 to 8.6% calculated as metal with respect to the total weight of nickel and alumina, and the proportion of the alkali compound is larger than the proportion of alumina in the catalyst. I'm teaching. "
Furthermore, "the applicant has found that a particularly effective catalyst is obtained when the alkaline compound used is a higher proportion of alkaline earth metal than that of the above-mentioned patent specification." , "Alkaline earth metals that can be used are barium, strontium, calcium and magnesium, but barium is preferable", "a particularly preferable ratio is 10 to 20 barium metal based on the total weight of nickel, alumina and barium. % By weight. ”

This particularly preferable ratio of 10 to 20% by weight of barium metal corresponds to catalysts 3, 4 and 5 of JP-B-44-17737, and when the amount of barium metal is converted to 100 mol of alumina, it is about 30%, respectively. Corresponds to moles, 44.5 moles, 74 moles. Moreover, the purpose of adding the alkaline earth metal compound is
It is clear that the purpose is not to improve the heat resistance, but to aim at the co-catalyst effect for preventing the deposition of carbon on the catalyst. Further, the operating temperature is limited to 600 ° C or lower, which is a problem of the present invention.
It is not intended for products with heat resistance at operating temperatures exceeding 00 ° C.

(Problems to be solved by the invention) Generally, an alumina carrier or the like having a large specific surface area is used as a catalyst carrier for catalytic combustion or the like, and is being studied. In that case, there is a drawback that the specific surface area is sharply reduced, and therefore the activity of the catalyst using the alumina carrier is lost, especially the activity at low temperature. Therefore, the retention rate of the specific surface area is high even under high temperature conditions, and therefore the activity is less reduced, and no embrittlement occurs (hereinafter,
Such properties are referred to as "good heat resistance" or "excellent heat resistance" or "excellent heat resistance") catalysts or supports for such catalysts have been sought.

As means for improving the heat resistance of the alumina carrier, for example,
U.S. Reissue Patent No. 30608, addition of silica as described in U.S. Pat.Nos. 4013587 and 4013590, addition of rare earth oxides described in JP-A-48-14600, etc. Although proposed, none of them can prevent the transition to α-alumina at 1200 ° C or higher,
Therefore, it was difficult to avoid a decrease in activity and embrittlement of the catalyst particles.

(Means for Solving the Problems) An object of the present invention is to provide a heat-resistant support which has aluminum oxide and metal oxide MeO as main components and which has remarkably excellent heat resistance as a catalyst support, and a catalytically active component for catalytic combustion reaction. The present invention is to provide a heat resistant catalyst carrying such substances.

The present invention contains aluminum oxide and metal oxide MeO as main components and contains metal oxide MeO in a ratio of about 3 to 25 mol, particularly about 5 to 20 mol, based on 100 mol of aluminum oxide Al ₂ O ₃ , and Me is B
a, a metal selected from the group consisting of Ca and Sr,
The present invention provides a heat-resistant carrier in which a catalytically active component is carried on a carrier having extremely excellent heat resistance, which is particularly suitable as a catalyst carrier such as a catalytic combustion catalyst exposed to a high temperature exceeding 0 ° C.

The present invention further provides a method for producing a heat-resistant catalyst by preparing a heat-resistant carrier of the present invention using a composite or mixed alkoxide of a metal represented by aluminum and Me as a raw material, and carrying a catalytically active component on the support. . According to this alkoxide method, it becomes possible to provide a catalyst having heat resistance superior to that obtained by a method generally used for producing a catalyst such as a solid mixing method or a precipitation method from an aqueous solution.

The support for the heat-resistant catalyst of the present invention is mainly composed of aluminum oxide Al ₂ O ₃ and a metal oxide represented by MeO, and is selected from the group consisting of barium oxide, calcium oxide and strontium oxide. It does not depart from the scope of the present invention to include a small amount of a third component such as silica, a rare earth oxide and an alkali metal oxide in the heat resistant carrier in addition to the metal oxide MeO.

The starting material for the aluminum oxide contained as a support component for the heat-resistant catalysts of the present invention is preferably alumina, commonly known as transitional alumina, by the solid state mixing method. For transferable alumina, chi, kappa, gamma,
Six types of eta, theta, and delta are known, but all of these types of alumina are unstable as they are, and when exposed to high temperatures, they transform into α-alumina and are active in catalysts. Is caused and the catalyst particles are embrittled.

As a starting material for aluminum oxide, a water-soluble compound such as aluminum nitrate, aluminum sulfate or sodium aluminate can be usually used in the precipitation method.

Hereinafter, the MeO according to the present invention will be described with reference to barium oxide, but the same applies to calcium oxide and strontium oxide.

Various barium compounds such as barium oxide, barium hydroxide, barium carbonate, barium nitrate, and barium sulfate can be used as a starting material for barium oxide as another main component of the carrier for the heat-resistant catalyst of the present invention. .

As a method for adding the barium compound to the aluminum oxide, various methods usually used in the production of a carrier or a catalyst such as a precipitation method such as a coprecipitation method, a mixing method, a kneading method and an impregnation method can be used.

The present invention proposes an alkoxide method as a special method for producing a heat-resistant catalyst, especially its support. The raw materials for aluminum oxide and barium oxide in this alkoxide method are alkoxides of aluminum and barium. The alkoxide is preferably an alkoxide having 1 to 4 carbon atoms such as methoxide, ethoxide, isopropoxide and butoxide. These alkoxides may be commercially available ones, but they can also be prepared using metal aluminum and metal barium and alcohols.

The content of barium oxide in the heat-resistant catalyst of the present invention is about 3 to 25 mol, especially 5 to 20 mol based on 100 mol of aluminum oxide.
A molar ratio is desirable. Outside this range, the effect of addition of barium oxide on the heat resistance is small, and addition of excess barium oxide rather lowers the heat resistance.

The shape of the heat-resistant catalyst or carrier of the present invention may be powder as it is, but any shape commonly used as a catalyst or catalyst carrier such as tablets, rings, spheres, extrusion molds, honeycombs and the like can be adopted.

The heat-resistant catalyst or carrier of the present invention is usually made into a product through a final step or an intermediate step of drying and / or calcination, but calcination is not always necessary, and sometimes this is not performed. However, in the case of catalysts or catalyst supports, especially in the case of catalysts for catalyst combustion or catalyst supports, calcination at temperatures around the maximum temperature of use is an important operation for obtaining thermally stable compositions. For example, when the heat resistant catalyst of the present invention is a catalyst for catalytic combustion, it is naturally expected that it will be exposed to a high temperature exceeding 1300 ° C. during use. In this case, 1300 ℃
Alternatively, it is preferable to calcine the carrier and / or catalyst at a temperature higher than that. At such a high calcination temperature, a catalyst not according to the present invention, for example, a catalyst using a carrier to which a heat resistance improver such as γ-alumina carrier, silica-alumina carrier, rare earth or alkali is added, is converted to α-alumina. Therefore, a remarkable decrease in the specific surface area and the accompanying decrease in activity, especially low temperature activity, cannot be avoided.

In producing the heat-resistant catalyst of the present invention or a carrier thereof,
Normally, it is preferable to fire at a temperature of 900 ° C or higher, but when firing at a temperature higher than 1300 ° C, the correlation between the firing temperature and the specific surface area is measured in advance, and the specific surface area is set within an appropriate range. For example, about 2 m ² /
It is necessary to keep the specific surface area above g.

The heat-resistant catalyst of the present invention has an extremely high reaction temperature, such as steam reforming-like reaction and exothermic reaction.
It is suitable as a catalyst for a reaction in which a high temperature exceeding 1 is expected, for example, a reaction such as catalytic combustion. Therefore, V, Cr, Mn, Fe, Co, Ni, C, which have excellent oxidation activity
Compounds such as metals such as platinum group noble metals such as u, Mo, Ag, La, Ce, Pt, Ru, Rh and Pd, or oxides thereof, or complex oxides such as perovskite type are desirable. However, it is naturally conceivable to use a metal or a metal oxide other than the catalytically active component depending on the type of reaction, but such a catalyst does not depart from the scope of the present invention.

The carrier for the heat-resistant catalyst of the present invention is preferably a coprecipitant in an aqueous solution prepared by mixing a water-soluble aluminum salt and an aqueous barium salt in the range of 100: 3 to 25 calculated as the molar ratio of Al ₂ O ₃ : BaO. To form a mixed composition in the form of a coprecipitate, and the coprecipitate obtained by washing-filtering or evaporating to about 20
It is obtained by calcining at 0 to 500 ° C. and then baking at about 1200 to 1300 ° C. for about 5 to 30 hours or at about 1300 ° C. or higher for about 5 to 20 hours. In this case, the water-soluble aluminum compound includes aluminum nitrate, aluminum sulfate, aluminum chloride and the like. Examples of the water-soluble barium compound include barium nitrate and barium chloride. In this case, caustic soda, sodium carbonate, caustic potash, aqueous ammonia, etc. can be used as the coprecipitant. Further, as the water-soluble raw material, sodium aluminate, barium hydroxide and the like can be used, but in this case, acids such as nitric acid and carbonic acid are adopted as the coprecipitating agent. The preliminary calcination step may be omitted.

A more preferable method for producing the carrier for the heat-resistant catalyst of the present invention is an alkoxide method using a composite or mixed alkoxide of aluminum and barium as a raw material.
The generation of aluminum and barium oxides is preferably carried out through hydrolysis, but the method is not limited to hydrolysis, and methods such as thermal decomposition can also be used. Further, it is not necessary that all of these oxides are produced from alkoxide, and alumina, barium carbonate, etc. may be added to the decomposition product of alkoxide. In the case of hydrolysis, it is about
It is desirable to heat to 0 ° C. The effect of the pH of the water added for hydrolysis was not particularly observed, but the aging time after adding water has a large effect on the specific surface area of the heat-resistant carrier, and the longer the aging time, the more the specific surface area increases. . Therefore, the aging time is preferably at least 1 hour, and it is particularly desirable to set the aging time as long as possible within an economically acceptable range such as 5 to 10 hours. The specific surface area of the heat-resistant carrier of the present invention is also affected by the amount of water used for hydrolysis, but the amount of water necessary to hydrolyze the total amount of the complex or mixed alkoxide present to hydroxide and alcohol ( It has been found that an unexpectedly large specific surface area can be obtained even when the following water is used. The amount of water to be added may be equal to or less than the equivalent of water. On the other hand, it is not preferable to use an excessively large amount of water because it causes an excessive amount of processing equipment and energy consumption, and it is preferable to set the amount of water to about 10 equivalents or less from the economical viewpoint. Therefore, the amount of water used is usually about 0.5-10.
It is equivalent. However, the amount of water used is not limited to this range.

The carrier for the heat-resistant catalyst according to the alkoxide method of the present invention is, in a preferred production example, aluminum alkoxide and barium alkoxide in an Al ₂ O ₃ : BaO molar ratio of 100: 3 to.
It is dissolved in alcohol so that it exists in a ratio of 25, water in an amount in the range of about 0.5 to 10 in an equivalent ratio is added, hydrolysis is performed at a temperature in the range of 50 to 100 ° C, and aging for 5 to 10 hours. After that, the solvent is removed by evaporation to dryness, the resulting decomposition product mixture is calcined at about 200 to 500 ° C., and then calcined at a temperature of about 900 ° C. or higher for about 5 to 30 hours. The former calcination step may be omitted.

Next, with respect to the production of the catalyst of the present invention using the thus produced catalyst carrier, all the methods usually used in the production of supported catalysts can be applied. That is, all methods such as a powder mixing method, a kneading method, an impregnation method, a coating method, a spraying method, a precipitation method and the like can be adopted, but it is most common to carry a catalytically active component on a molded carrier by the impregnation method. This method is desirable and desirable.

The increase of the specific surface area by the addition of barium oxide to alumina in the heat-resistant catalyst of the present invention or the carrier therefor is
It is thought that this is due to the formation of BaO · 6Al ₂ O ₃ . Al ₂ O ₃ and Me
In the case of the solid mixing method in which O is mixed, BaO.6Al ₂ O ₃ begins to appear at a firing temperature of the mixed composition of around 1200 ° C, and at 1450 ° C.
It becomes a single phase of BaO ・ 6Al ₂ O ₃ . After the formation of BaO · 6Al ₂ O _3, the specific surface area is hardly reduced even if the firing temperature is increased. On the other hand, when the alkoxide method is used, BaO
・ It is considered that 6Al ₂ O ₃ can be generated, which suppresses sintering of alumina and maintains the specific surface area at higher temperatures.

(Examples and Comparative Examples) Next, the present invention will be described in more detail by way of examples.

Example 1 and Comparative Examples 1 to 9 A ball mill using as starting materials two kinds of oxides or carbonates selected from oxides of constituent elements of aluminum, zirconium, magnesium, calcium, silicon and barium which are usually used as refractory materials. It was then fed into and pulverized and mixed for about 24 hours. The molar ratios of the two components of these mixtures were both 9: 1. Next, these mixtures were calcined at 1450 ° C. for 5 hours to obtain catalyst carriers of Example 1 and Comparative Examples 1-8. As a control, the pure alumina carrier (Comparative Example 9) was prepared by using the above aluminum oxide alone and performing the above treatment. The measurement results of the BET specific surface areas of various carriers thus obtained are shown in Table 1 below. The carrier of Example 1 composed of alumina and barium oxide has a remarkably large specific surface area as compared with the pure alumina carrier of Comparative Example 9 for comparison, and other Comparative Example 1
The specific surface area was remarkably higher than that of ~ 8.

Use Example 1 Various carriers prepared in Example 1 and Comparative Examples 1 to 8 (excluding the carrier of Comparative Example 9) were impregnated with cobalt acetate or manganese acetate and then calcined at 1300 ° C. for 10 hours to prepare a catalyst.
Next, using these 18 kinds of catalysts individually, a methane combustion activity test was carried out by an atmospheric fixed bed flow reactor.
The gas used in the test was a gas consisting of 1% by volume of methane and 99% by volume of air, and this gas was flowed through the catalyst layer at a flow velocity of space velocity of 48000 hr ^-1 .

The test results are shown in Table 1. Tconv 90% in the table
(° C.) means the temperature of the catalyst layer showing a methane conversion rate of 90%. The test results are shown in Table 1. The larger the specific surface area of the carrier used, the better the activity expressed by Tconv 90% (° C). The catalyst supporting Co ₃ O ₄ using the carrier of Example 1 containing alumina as a main component and barium oxide subcomponent shows a markedly higher activity than other catalysts using the carrier of Comparative Example. .

Examples 2 to 6 and Comparative Examples 10 to 11 A calcined carrier was prepared in the same manner as in Example 1 using aluminum oxide and barium carbonate as starting materials. The number of moles of barium oxide in these various carriers was 0 (Comparative Example 10), 5 (Example 2), 10 (Example 3), 14.3 (Example), with respect to the total number of moles of barium oxide and aluminum oxide, respectively. Example 4), 15 (Example 5), 20 (Example 6), 50 (Comparative Example)
11) It was defined as mol%.

The compositions and BET specific surface areas of the various carriers obtained are shown in Table 2 and FIG.

Furthermore, the crystal structure of the carrier containing 0, 10, 14.3, 15, and 50 mol% of barium oxide was examined by X-ray diffraction.
The results are shown in Fig. 2. ○ indicates α-Al ₂ O ₃ , ● indicates BaO ・
6Al ₂ O ₃ , ∇ indicates BaO · Al ₂ O ₃ . The carrier with a maximum specific surface area of 14.3 mol% barium oxide shows a structure of BaO ・ 6Al ₂ O ₃ , and the addition of barium oxide shows a small decrease in the specific surface area due to the formation of the BaO ・ 6Al ₂ O ₃ phase. It is thought to be due to.

Examples 7 to 12 and Comparative Examples 12 to 16 Using the same starting materials as in Example 1, and by the same pulverization and mixing method as in Example 1, an unfired mixture of (Al ₂ O ₃ ) _0.857 (BaO) _0.143 was prepared. did. This unfired mixture was mixed with γ-alumina for comparison containing no barium oxide at 1000 ° C., 11
5 at each temperature of 00 ℃, 1200 ℃, 1300 ℃, 1400 ℃, 1450 ℃
After firing for a period of time, carriers of Examples 7 to 12 and Comparative Examples 12 to 16 were obtained. The results of measuring the BET specific surface areas of these carriers are shown in Table 3 and FIG. 3 below.

The crystal structure of the carrier (Al ₂ O ₃ ) _0.857 (BaO) _0.143 obtained by firing at 1100 ° C., 1200 ° C., 1400 ° C. and 1450 ° C. was examined by X-ray diffraction. The results are shown in FIG. In the figure, ● indicates BaO ・ 6Al ₂ O ₃ and ▽ indicates BaO ・ Al ₂ O ₃ . From the figure, it is considered that sintering is suppressed in the case of firing at 1200 ° C. or higher because the composition is a high temperature heat resistant composition due to the formation of BaO.6Al ₂ O ₃ .

Example 13 Using aluminum nitrate and barium nitrate, Al ₂ O ₃ : BaO
An aqueous solution having a molar ratio of 85.7: 14.3 was prepared, and sodium carbonate was added to the aqueous solution to adjust the pH to 8.

The coprecipitate obtained is filtered and washed, and the coprecipitate is washed at 200 ° C and 500 ° C respectively.
It was dried for an hour, calcined, and then calcined at 1450 ° C. for 5 hours to obtain the carrier of Example 13.

The BET specific surface area of this carrier was measured and found to be 5.5 m ² / g.

Examples 14-16 Using aluminum nitrate and barium nitrate, calcium nitrate or strontium nitrate, Al ₂ O ₃ : MeO molar ratio 85.7: 1
Make an aqueous solution to give 4.3, and add ammonia water to this aqueous solution until pH 8 and evaporate to dryness to give 2
After being calcined at 00 ° C. and 500 ° C. for 2 hours, respectively, it was calcined at 1450 ° C. for 5 hours to obtain the carriers of Examples 14, 15, and 16.

The results of measuring the BET specific surface area of this carrier are shown in Table 4.

As shown in Table 4, addition of calcium oxide or strontium oxide to alumina also enabled a high specific surface area at high temperatures.

Examples 17 to 18 and Comparative Example 17 An isopropyl alcohol solution containing barium isopropoxide and aluminum isopropoxide in a ratio of 1 mol to 12 mol was prepared, and water was added dropwise to this solution. Hydrolysis of isopropoxide was carried out at a temperature of 80 ° C. in a nitrogen atmosphere. The resulting hydrolyzate suspension was aged with stirring for 12 hours, and then dried under reduced pressure to obtain a powder after calcination of Example 17.

Meanwhile, barium carbonate and γ-alumina were placed in a ball mill.
The powder was pulverized and mixed for 24 hours to obtain an unburned powder of Example 18. In this case, the molar ratio of barium carbonate (BaCO ₃ ) and alumina (Al ₂ O ₃ ) was 1: 6.

The two kinds of powder thus obtained and the γ-alumina powder (Comparative Example 17) were calcined at 1000 ° C, 1100 ° C, 1200 ° C, 1300 ° C, 1450 ° C and 1600 ° C for 5 hours. BE of these baked powders
The T specific surface area was measured and the results are shown in FIG.

The specific surface area of γ-alumina (Comparative Example 17) was remarkably reduced at around 1200 ° C, and was about 1 m ² / g at 1400 ° C or higher. This decrease in specific surface area is accompanied by the transition of γ-alumina to the α phase. Therefore, this type of alumina is unsuitable for high temperature catalysts or catalyst supports. Examples obtained by powder mixing method
Even with 18 powders, the specific surface area began to decrease at 1200 ° C,
In addition, maintaining a specific surface area of 5 m ² / g even at 1400 ° C,
The specific surface area was about 4 times higher than that of Comparative Example 17. The specific surface area of the powder of Example 17 by the alkoxide method was further improved, and was always 2 to 3 times the specific surface area of Example 18, at 1600 ° C.
Even during calcination, the specific surface area exceeded 10 m ² / g. Therefore, the use of the alkoxide method clearly resulted in a significant improvement in specific surface area.

The X-ray diffraction pattern of the calcined powder of Example 17 was measured and the data is shown in FIG. In the figure, ● indicates BaO ・ 6
Indicates Al ₂ O ₃ . The alkoxide method enables direct production of BaO ・ 6Al ₂ O ₃ without passing through BaO ・ Al ₂ O ₃ as an intermediate product at 1200 ° C or higher, which suppresses the decrease in specific surface area at high temperatures of 1200 ° C or higher. It is thought that it is doing. Further, the alkoxide method enables treatment of the composite oxide at a low temperature, which is considered to provide a more stable and high specific surface area.

Examples 19 to 28 Using the same isopropoxides as in Example 17, various powders (Examples 19 to 28) were prepared. The conditions for hydrolysis of alkoxides and the specific surface areas of these powders after firing at 1300 ° C and 1450 ° C are shown in Table 6 below.

Among hydrolysis conditions, the aging time greatly affects the specific surface area, and the longer the aging time, the larger the specific surface area. The aging time is preferably at least 1 hour or more, more preferably 5 hours or more. No effect of water pH was observed. H ₂
When the O / MOPr ratio was in the range of 0.5 to 1, it tended to have a larger specific surface area as the product with a smaller H ₂ O / MOPr ratio when fired at 1300 ° C, but after firing at 1450 ° C Little difference was seen.

Use Example 2 A durability test at 1450 ° C. was carried out using the 1450 ° C. calcined powder (Examples 23 and 18). The test results are shown in Table 7 below.

The reduction rate of the specific surface area after carrying out a firing test at 1450 ° C. for 50 hours was 23% in Example 23 by the alkoxide method and 34% in Example 18 by the powder mixing method with the same composition, and was manufactured by the alkoxide method. The heat resistance of the product was remarkably excellent.

Examples 29-31 and Comparative Example 18 Powder of Example 23 calcined at 1300 ° C., Powder of Example 22 calcined at 1450 ° C. and Powder of Example 18 calcined at 1450 ° C. and γ-alumina calcined at 1450 ° C. Four calcined powders were suspended in a cobalt nitrate solution and then evaporated to dryness. This dry powder was calcined at 1300 ° C. to prepare four kinds of catalysts (Examples 29, 30 and 31 and Comparative Example 18). The supported amount of cobalt oxide was 10% by weight for each catalyst. Next, using these catalysts individually, an activity test was conducted by the same test method as described in Use Example 1. The results are shown in Table 8 below.

Only carbon dioxide and water were produced on all tested catalysts. The activity increased with increasing reaction temperature. The specific surface area of the carrier obviously affected the activity. The highest activity was obtained with the BaO.6Al ₂ O ₃ support by the alkoxide method.

Examples 32-38 Commercially available aluminum isopropoxide (356.8 g) and metal barium (20 g) under a nitrogen atmosphere and isopropyl alcohol 6
It was dissolved in 00 cc, and 1200 cc of water having a pH of 7 was added dropwise to the solution (the pH of the solution after adding water was 9) to perform hydrolysis. 12
After aging for a period of time, the resulting suspension was filtered to remove the solvent. After drying at 400 ° C and going through processes such as crushing and tableting,
The obtained 1/4 inch diameter 1/4 inch height tablet 1300
The mixture was calcined at 0 ° C. for 10 hours to obtain 111.4 g of a catalyst carrier (Example 32).

Further, six catalyst carriers (Examples 33 to 38) were obtained by the same operation as in Example 32. However, in order to see the influence of operating conditions on the surface area during production of these 6 catalysts, some conditions such as hydrolysis temperature, H ₂ O / MOPr ratio, aging time, and calcination time were changed.

The preparation conditions and specific surface area of the catalyst carrier are shown in Table 9 below.

The results of these tests show the following:

(1) The longer the aging time, the better.

(2) The higher the hydrolysis temperature, the better.

(3) The higher the H ₂ O / MOPr ratio, the better. However, considering economic aspects such as capital investment and energy consumption, this ratio should not be too large.

(4) No effect of pH of added water is seen.

Examples 39 to 42 and Comparative Examples 19 to 20 Powder-fired powders were prepared by the same procedure as in Examples 17 and 26 except that the ratio of barium isopropoxide and aluminum isopropoxide was changed, and the powders were heated at 1450 ° C for 5 hours. Firing was carried out for a period of time to obtain fired powders of Examples 39 to 42 and Comparative Examples 19 and 20.
The composition and specific surface area of these baked powders are shown in Table 10 below.

Examples 43 to 45 Using aluminum isopropoxide and barium isopropoxide, calcium isopropoxide and strontium isopropoxide each of which has one type of isopropoxide, the Al ₂ O ₃ : MeO molar ratio is 85.7: 14.3. Such a calcined powder was prepared in the same manner as in Example 41 to give Examples 43, 44 and
45 calcined powders were obtained.

The results of measuring these BET specific surface areas are shown in Table 11 below.

Example 46 Aluminum isopropoxide and barium metal which are calculated to have a molar ratio of Al ₂ O ₃ : MeO of 85.7: 14.3 are added to ethanol, and the mixture is reacted at about 70 ° C. for 5 hours while bubbling with dry nitrogen. Let The resulting solution was dried under reduced pressure to obtain a white transparent gel. Then apply this gel in air to 80
Calcination at 0 ° C for 5 hours, then at 1300 ° C for 5 hours,
A fired powder of Example 46 was obtained.

The specific surface area of the calcined powder of Example 46 was 17.0 m ² / g.
From this, it was found that a high specific surface area equivalent to that obtained by hydrolysis can be obtained by thermal decomposition of the alkoxide.

Examples 47-56 Aluminum oxide and barium carbonate were fed into a ball mill and ground and mixed for about 24 hours. The molar ratio Al ₂ O ₃ : BaCO ₃ of these two carrier raw materials was 85.7: 14.3. Then, the obtained mixture was calcined at 1450 ° C. for 5 hours to obtain a catalyst carrier. In charge of this catalyst, cobalt acetate, manganese acetate, nickel acetate,
Chromium nitrate, copper nitrate, iron nitrate, ammonium metavanadate, ammonium ammonium molybdate, silver nitrate, and cadmium nitrate were respectively impregnated and then calcined at 1300 ° C. for 10 hours to give Examples 47, 4
8,49,50,51,52,53,54,55,56 catalysts were obtained. The amount of each metal supported was 10% by weight of the catalyst carrier as each metal oxide.

Use Example 3 Using the catalysts of Examples 47 to 56, a methane combustion activity test was conducted in the same manner as in Use Example 1.

 The results of the tests are shown in Table 12 below.

The catalyst using manganese oxide, copper oxide, and iron oxide as the catalytically active component had higher activity in the low reaction rate region than the one using cobalt oxide, but the reaction curve started up slowly. It was On the other hand, the one using chromium oxide was less active than the one using cobalt oxide over the entire area. On the other hand, the one using nickel oxide and vanadium oxide showed the activity equal to or higher than that using cobalt oxide.

Examples 57 to 60 Catalysts of Examples 57 to 60 were prepared by supporting 1% by weight of platinum and palladium on the catalyst carriers obtained in Examples 47 to 56, respectively. In the case of supporting platinum, after impregnating with chloroplatinic acid, calcination is performed in a hydrogen stream at 500 ° C for 5 hours and then in a nitrogen stream.
It was baked at 300 ° C. for 5 hours. On the other hand, in the case of supporting palladium, palladium nitrate was used, and after calcining in a hydrogen stream at 500 ° C. for 5 hours, it was calcined in air at 1200 ° C. for 5 hours. Lanthanum and cerium oxide were impregnated with lanthanum nitrate and cerium nitrate so as to be 10 wt% with respect to the carrier.

Use Example 4 A methane combustion activity test was conducted in the same manner as in Use Example 1 using the catalysts of Examples 57-60.

 The results of the tests are shown in Table 13 below.

The platinum-loaded catalysts of Examples 57 and 59 showed about the same activity as the cobalt oxide-loaded catalysts, while the Pd-loaded catalysts of Examples 58 and 60 were much more active. It was

Examples 61 and 62 La: Sr: Co atomic ratio 0.8 on the catalyst support obtained in Examples 47-56:
Examples 61 and 62 were prepared by impregnating with each acetate mixture solution having an atomic ratio of 0.2: 1 or La: Sr: Mn of 0.6: 0.4: 1, calcining at 600 ° C. for 2 hours, and then calcining at 1300 ° C. for 5 hours. The catalyst was obtained. La _0.8 Sr _0.2 Co
The loading amounts of O ₃ and La _0.6 Sr _0.4 Mn O ₃ are both relative to the carrier.
It was set to 10 wt%.

Use Example 5 A methane combustion activity test was conducted in the same manner as in Use Example 1 using the catalysts of Examples 61 and 62.

 The results of the tests are shown in Table 14 below.

Perovskite type complex oxide La _0.8 Sr _0.2 Co O ₃ and La
_The example catalysts 61 and 62 supporting _0.6 Sr _0.4 Mn O ₃ both showed activity equivalent to that of the cobalt oxide-supported catalyst.

(Effect of the Invention) Thus, according to the present invention, it is possible to obtain a catalyst having extremely excellent heat resistance, which can be used at a high temperature which is extremely suitable as a catalyst. Therefore, the present invention is extremely useful industrially.

[Brief description of drawings]

Figure 1 shows (BaO) _x · (Al ₂ obtained by firing at 1450 ° C for 5 hours.
Fig. 2 shows the relationship between the specific surface area and the value of x of O ₃ ) _1-x , Fig. 2 is its X-ray diffraction diagram, and Fig. 3 is the firing temperature and the obtained carrier (BaO) _0.143・ (Al ₂ O
₃ ) A diagram showing the relationship with the specific surface area of _0.857 , Fig. 4 is an X-ray diffraction diagram of a part of the carrier of Fig. 3, and Fig. 5 is obtained by the powder mixing method and the alkoxide method (Ba
O) _0.14・ (Al ₂ O ₃ ) _0.86 Composition 1000 ℃, 1200 ℃, 1450
FIG. 3 is an X-ray diffraction pattern of a fired product at ℃ and 1600 ℃.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location B01J 23/58 B01J 23/58 M 23/66 23/66 M 23/74 23/74 23/78 23/78 M

Claims (18)

(57) [Claims] 1. A supported type comprising a heat-resistant composition for catalytic combustion reaction, which comprises a metal oxide represented by aluminum oxide Al ₂ O ₃ and MeO as a main component, and a catalytically active component supported thereon. For heat-resistant catalysts, the carrier is aluminum oxide 100
The metal oxide MeO is contained in the range of about 3 to 25 mol per mol, Me is at least one metal selected from the group consisting of Ba, Ca and Sr, and the catalytically active component is supported on this carrier. A heat-resistant catalyst for catalytic combustion reaction, characterized by comprising: 2. Aluminum oxide and metal oxide in a carrier
The heat-resistant catalyst for catalytic combustion reaction according to claim 1, wherein a part or all of MeO is a decomposition product of a composite or mixed alkoxide of a metal represented by aluminum and Me. 3. The catalytic combustion according to claim 2, wherein a part or all of aluminum oxide Al ₂ O ₃ and metal oxide MeO in the carrier is a hydrolysis product or a thermal decomposition product of a complex or mixed alkoxide. Heat resistant catalyst for reaction. 4. The complex or mixed alkoxide has 1 to 4 carbon atoms.
The heat-resistant catalyst for catalytic combustion reaction according to claim 2 or 3, which is the alkoxide of. 5. The heat resistant catalyst for catalytic combustion reaction according to claim 1, 2, 3 or 4, which contains barium oxide in a ratio of about 5 to 20 mol per 100 mol of aluminum oxide Al ₂ O ₃ . 6. Aluminum oxide Al ₂ O ₃ and metal oxide MeO
The heat-resistant catalyst for catalytic combustion reaction according to claim 1, 2, 3, 4, or 5, which comprises a part or all of the above as MeO.6Al ₂ O ₃ . 7. A catalytically active component in a heat-resistant catalyst for catalytic combustion reaction is a metal mainly represented by Cm and / or an oxide of Cm, and Cm is V, Cr, Mn, Fe, Co, Ni, Cu. , Mo, Ag, Cd, La, Ce and P
Claims 1, 2, 3 which are at least one metal selected from the group consisting of platinum group noble metals such as t, Ru, Rh and Pd.
4. A heat resistant catalyst for catalytic combustion reaction according to 4, 5 or 6. 8. The method according to claim 1, wherein the catalytically active component is mainly a perovskite type oxide.
A heat resistant catalyst for the catalytic combustion reaction described. 9. The heat resistant catalyst for catalytic combustion reaction according to claim 1, 2, 3, 4, 5, 6, 7 or 8, which is a catalyst for catalytic combustion used at a temperature of about 1000 ° C. or higher. Heat resistant catalyst for catalytic combustion reaction. 10. A heat-resistant composition containing aluminum oxide Al ₂ O ₃ and a metal oxide represented by MeO as a main component as a carrier,
In producing a supported heat-resistant catalyst for catalytic combustion reaction, which carries a catalytically active component thereon, a water-soluble or alcohol-soluble aluminum compound and a water-soluble or alcohol-soluble barium compound, calcium compound and strontium compound A water-soluble or alcohol-soluble metal compound selected from the group consisting of Al ₂ O ₃ : MeO (Me is B
a, showing at least one metal selected from the group consisting of Ca and Sr), a coprecipitate or a hydrolysis product or a pyrolysis product from a solution mixed at a molar ratio of 100: 3 to 25,
A method for producing a heat-resistant catalyst for catalytic combustion reaction, which comprises supporting a catalytically active component on a carrier obtained by firing at a temperature of about 900 ° C or higher. 11. A composite or mixed alkoxide containing about 3 to 25 mol of an alkoxide of a metal represented by Me with respect to 200 mol of an aluminum alkoxide corresponding to 100 mol of Al ₂ O ₃ is hydrolyzed or pyrolyzed to obtain 900 products
11. The method for producing a heat resistant catalyst for catalytic combustion reaction according to claim 10, wherein the support is obtained by calcining at a temperature of not less than ° C. 12. The complex or mixed alkoxide has 1 to 10 carbon atoms.
The method for producing a heat-resistant catalyst for catalytic combustion reaction according to claim 11, which is the alkoxide of No. 4. 13. The amount of water used for hydrolysis is about 0.1 of the equivalent of water required to hydrolyze the total amount of alkoxide.
13. The method for producing a heat resistant catalyst for catalytic combustion reaction according to claim 11 or 12, which uses 5 times or more water. 14. The method for producing a heat-resistant catalyst for catalytic combustion reaction according to claim 11, 12 or 13, wherein the hydrolysis is carried out at a temperature in the range of about 50 to 100 ° C. 15. The method for producing a heat-resistant catalyst for catalytic combustion reaction according to claim 11, 12, 13 or 14, wherein aging is carried out for about 1 hour or more after addition of water for hydrolysis. 16. A heat resistant catalyst for catalytic combustion reaction according to claim 11, 12, 13, 14 or 15, wherein Me is barium and the ratio of barium alkoxide to 200 mol of aluminum alkoxide is about 5 to 20 mol. Manufacturing method. 17. A catalytically active component in a heat-resistant catalyst for catalytic combustion reaction is a metal mainly represented by Cm and / or an oxide of Cm, and Cm is V, Cr, Mn, Fe, Co, Ni, Cu. , Mo, Ag, Cd, La, Ce and at least one metal selected from the group consisting of platinum group noble metals. Claims 10, 11, 12, 13, 14, 15 or
16. The method for producing a heat resistant catalyst for catalytic combustion reaction according to 16. 18. The claim 10, 11, 12, 13, 14, 15 in which the catalytically active component is mainly a perovskite type oxide.
Or a method for producing a heat-resistant catalyst for catalytic combustion reaction according to item 16.