JPH01230425A - Heat-resistant multiple oxide and production thereof - Google Patents

Abstract

PURPOSE:To obtain the title multiple oxide useful as a carrier for catalysts to be used at high temperatures, by mixing an aluminum alkoxide with specific complex of beta-diketone in the presence of oxygen-contg. organic compound(s) followed by calcination of the resultant gel. CONSTITUTION:Firstly, (A) an aluminum alkoxide and (B) at least one kind of complex compound from a metal (selected from barium, lanthanum and cerium) and beta-diketone of the formula R1-CO-CH2-CO-R2 (R1 and R2 are each alkyl or alkoxy) are mixed with each other into a homogeneous solution. Thence, this solution is hydrolyzed to form a sol followed by gelation, and the resultant gel is dried and calcined, thus obtaining the objective complex oxide. Use of said beta-diketone for incorporating barium, lanthanum and/or cerium allows the objective heat-resistant alumina complex oxide to be obtained safely at low cost.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a heat-resistant composite oxide useful as a heat-resistant functional material 1'4, particularly a heat-resistant composite used as a support for a catalyst used at high temperatures. This invention relates to oxides and methods for producing the same.

(Prior Art) Recently, research has been actively conducted to apply combustion catalyst technology to boilers, gas turbines, etc. to make them low NO power sources. These combustion catalysts reach high temperatures of over 1000°C due to the combustion of fuel such as methane on the catalyst.
No catalyst has been found so far that can be used stably in such a high temperature range. In order to develop such a highly heat-resistant catalyst, it is first necessary to develop a heat-resistant carrier that maintains a high surface area even in such a high temperature range. Conventionally, a heat-resistant oxide such as activated alumina has been used as a support for this combustion catalyst, but at high temperatures of 1000°C or higher, this alumina transforms into α-alumina, which has a small specific surface area. It cannot be used as a catalyst support.

In addition, automobile exhaust purification catalysts have been used as a combustion catalyst technology for medium temperatures of around 800°C, but in recent years the rise in engine exhaust temperature and the need to install catalysts in areas with high exhaust gas temperatures near the engine have become more and more important. Due to efforts to increase the reaction activity of catalysts and reduce the amount of precious metals such as platinum and rhodium used in catalysts, there is a demand for high-temperature durability of around 1000"C. However, conventional automobile exhaust Purification catalysts also use activated alumina as a carrier and support precious metals such as platinum, rhodium, and haladium as catalysts, so at high temperatures of around 1000°C,
Activated alumina transforms into α-alumina and the specific surface area of the carrier decreases, and the supported noble metals agglomerate, making it impossible to maintain sufficient catalytic activity.

For this reason, various attempts have been made to increase heat resistance and suppress the decrease in specific surface area by adding other metal oxides to alumina.
4600) or barium oxide (Bad)
(Japanese Unexamined Patent Publication No. 1590) is said to be effective.

(Problems to be Solved by the Invention) However, although the heat resistance of the carrier was improved in the above proposal, in the case of a catalyst in which a noble metal is supported as a catalytically active component, the noble metal fine particles agglomerate at high temperatures. Sufficient catalytic activity cannot be maintained, and the catalyst as a whole does not necessarily have sufficient heat resistance.

Therefore, the present invention overcomes the problems of the prior art, does not cause a decrease in the specific surface area of the carrier even at high temperatures, and further suppresses the aggregation of the noble metal supported as a catalytically active component, thereby achieving sufficient catalytic activity. It is an object of the present invention to provide a heat-resistant composite oxide used to form a heat-resistant support that can be maintained and a method for producing the same.

(Means for Solving the Problems) In order to achieve the above object, the present inventors have developed compositions of various heat-resistant composite oxides, reduction of specific surface area at high temperatures, agglomeration suppressing effects of supported noble metal fine particles, and catalyst As a result of intensive research on activity, it has been found that adding cerium to certain alumina composite oxides to form a composite can maintain catalytic activity even at high temperatures, suppressing the decrease in the specific surface area of the support and the aggregation of the supported precious metals. I found the facts.

That is, the first invention of the present invention was achieved based on the above-mentioned knowledge, and the following general formula % formula % (MxOy in the formula is BaO or Lazy, , , z indicates 1.5 to 2) The content of MxOy in MxOy-Alz03 is 1 to 25% by weight, and the pore diameter showing the maximum value of the pore distribution is 50 to 200%. The present invention relates to a heat-resistant composite oxide characterized by the following. As mentioned above, the heat-resistant composite oxide of the present invention contains 1 to 25% by weight of barium oxide.
4- By further compounding 3 to 20% by weight of cerium to the alumina composite oxide containing at least one of lanthanum oxide and lanthanum oxide, the specific surface area of the support does not decrease even under high temperatures, and , aggregation of supported noble metals is also suppressed.

In the present invention, the content of barium oxide or lanthanum oxide is in the range of 1 to 25% by weight.The reason for this is that if the content is less than 1% by weight, α-alumina is likely to be generated at high temperatures, and as a result, This is because the specific surface area becomes small, and when the amount exceeds 25% by weight, the crystal growth of the two metal oxides becomes remarkable, and in this case also, the specific surface area decreases significantly.

In addition, the content of cerium is 3 to 20 parts by weight of the total weight.
Let the quantity be χ. When the cerium content is less than 3% by weight, the atomic ratio of cerium exposed on the surface of the composite oxide is small;
As a result, fewer cerium atoms interact with the supported noble metal, making it impossible to suppress agglomeration of the noble metal at high temperatures.

Furthermore, if the cerium content exceeds 20% by weight, the crystal growth of cerium oxide becomes significant at high temperatures, resulting in a significant decrease in the specific surface area.

Further, in order to improve the dispersion of the noble metal and form fine particles when impregnating and supporting the noble metal, it is preferable that the specific surface area of the carrier is large. If the heat resistance of the carrier is poor and its agglomeration progresses easily and the specific surface area decreases, the supported noble metal may become embedded in the carrier during agglomeration, or the distance between the dispersed noble metal fine particles may become shorter, causing the precious metal The paper collection will be progressing quickly. Therefore, the specific surface area of the carrier is substantially 1
00 m2/g, and in particular it is necessary to maintain this value even after exposure to high temperatures. In combustion catalysts such as automobile exhaust purification catalysts, especially 100
It is necessary to maintain this large specific surface area of 100 m27 g even after heat treatment for 3 hours at 0°C.

Further, the maximum distribution pore diameter indicating the maximum value of the pore distribution curve of the heat-resistant composite oxide of the present invention is set to 50 to 200. If the pore diameter is smaller than 50 pores, the diffusion of hydrocarbons in the pores will be slow, and the conversion rate of hydrocarbons by catalytic reaction will be low, which is not preferable for both combustion catalysts and automobile exhaust gas purification catalysts. In addition, the pore size is related to the specific surface area, and when the pore size exceeds 200 pores, the specific surface area decreases and the opportunity for contact between the reaction gas and the active sites of the catalyst decreases, resulting in a decrease in the catalytic reaction activity. It is not sufficient as a catalyst carrier because it causes deterioration. For this reason, it is preferable that the maximum distribution pore diameter showing the peak of the pore distribution curve is 50 to 200. In particular, it is important that this pore diameter is maintained even after high-temperature heat treatment at 1000'C.

Next, the second aspect of the present invention relates to a method for producing the heat-resistant composite oxide. Various methods are known for producing heat-resistant composite oxides. For example, a powder mixing method involves mixing a predetermined amount of oxides of aluminum, cerium, barium, and ranknium and repeating sintering and pulverization, or preparing a mixed aqueous solution of nitrates of the relevant elements and neutralizing them with a base such as aqueous ammonia. , a coprecipitation method in which a precipitate is simultaneously produced, and an alkoxide method in which a mixed solution of alkoxide compounds of the relevant element is hydrolyzed to produce a precipitate.

Among these, the powder mixing method uses a mixture of large particulate oxides that are far from the atomic and molecular level, so the composite oxide obtained cannot be expected to be mixed at the atomic and molecular level and is non-uniform. Also, since sintering is repeated, the specific surface area also decreases. Furthermore, even in the coprecipitation method, the pl+ that causes precipitation differs depending on the type of metal, so non-uniform precipitation tends to occur. In contrast, the alkoxide method is said to be the most preferred because it produces more uniform precipitation.

There are two types of methods using this alkoxide method. One is to add alcohol such as ethanol, propatool, butanol as necessary to alkoxides such as ethoxides, propoxides, butoxides of aluminum, cerium, barium, and ranknium, mix them, make a homogeneous solution, and hydrolyze. This is a conventional alkoxide method in which the obtained precipitate is calcined. In this conventional alkoxide method, the rate of hydrolysis varies depending on the type of alkoxide, so the resulting precipitate also remains non-uniform.

The other is Japanese Patent Application No. 62-075719 and Abstracts of the 55th Autumn Annual Meeting of the Chemical Society of Japan, IBOL (1987
), the alkoxides are mixed in the presence of one or two oxygen-containing organic compounds having multiple functional groups such as ethylene glycol and hexylene glycol, made into a homogeneous solution, and heated. A reaction such as complex formation and ligand exchange between an oxygen-containing organic compound and a metal alkoxide is caused, and the hydrolysis reaction and dehydration condensation reaction of the alkoxide are controlled to produce a homogeneous gel, followed by drying and calcination. This is an improved alkoxide method. The latter improved alkoxide method is particularly preferred because the resulting precipitate is excellent in uniformity, and a support with excellent heat resistance and less decrease in specific surface area at high temperatures can be obtained.

However, the alkoxides of barium, ranknium, and cerium used as additive components of the heat-resistant composite oxide carrier are expensive because their raw materials are limited and difficult to manufacture.
If produced, the carrier would be extremely expensive. In addition, in this alkoxide method, for these minor components, the nitrate of the metal in question can be heated in the alcohol used to convert it into the alkoxide of the metal. However, if a large amount of nitrate and organic matter are combined It tends to remain in the kelp, which is a precursor of the oxide, and this can cause rapid ignition during firing. Therefore, if these carriers are to be provided in large quantities industrially, they are likely to explode during firing, making this method extremely dangerous.

Therefore, the present inventors further improved the method for producing heat-resistant composite oxides of various compositions by the improved alkoxide method, and produced heat-resistant composite oxides of various compositions by the improved alkoxide method. In this method, even if a β-sigetone complex of the metal, which is very easy to produce, inexpensive, and safe, is used in place of alcokit of the metal as part or all of the additive components, the β-diketone complex is not aluminum. Because a ligand exchange reaction or complex formation reaction occurs between the alkoxide or the polyfunctional oxygen-containing organic compound, a highly homogeneous mixed solution can be obtained. It was discovered that an oxide support can be obtained.

The second invention of the present invention is based on this knowledge, and in the presence of one oxygen-containing organic compound having a plurality of functional groups, an aluminum alkoxy 1- % (in the formula, R1 and R2 are the same or different and represent an alkyl group or an alkoxy group) and at least one selected from the butyric compounds of barium, ranknium and cerium of β-diketones. The method of the present invention is characterized in that the solution is mixed to form a homogeneous solution, then this solution is hydrolyzed to form a ``ζ sol'', which is then gelated (1), and the gel is dried and then calcined.The method of the present invention is inexpensive and safe. In addition, heat resistance and the effect of suppressing the aggregation of supported noble metal fine particles at high temperatures can be obtained.

β-Soge 1- in the β-diketone complex used in the method of the present invention
The compounds are represented by the formula % (in the formula, R1 and R2 are the same or different and represent an alkyl group or an alkoxy group), and specifically, β-diketones (IllI, I? β-ketoester 172, alkoxy group) and β-dicarboxylic acid ester (R1, R2; alkoxy group) can be used.

Although there are no particular restrictions on the number of carbon atoms in these alkyl groups and alkoxy groups, compounds with 1 to 4 carbon atoms are preferred since these compounds with a high carbon number are very expensive. More specifically, complexes of barium, ranknium, cerium such as acetylacetone (acac), dimethylmalonic acid, diethylmalonic acid, methyl acetoacetate, and ethyl acetoacetate can be used. These β-diketone complexes cause a ligand exchange reaction or complex formation reaction with aluminum alkoxides or polyfunctional oxygen-containing organic compounds, and therefore a highly homogeneous mixed solution equivalent to that obtained when using alkoxides can be obtained. Therefore, this mixed solution was controlled to be equivalent to the case where alkoxides were used as all of the added components.
Uniform hydrolysis and dehydration condensation reactions occur, resulting in a homogeneous, well-mixed alumina composite oxide support with excellent heat resistance.

The β-diketone complex can be added by isolating and adding the β-diketone complex of the metal, or by adding the hydroxide, nitrate, etc. of the metal and β-diketones or their salts to a polyfunctional base oxygen Various methods can be used, such as a method in which an alcohol solution is prepared by reacting an organic compound or a monoalcohol such as ethanol, propatool, or butanol, and this alcohol solution is added.

The heat-resistant composite oxide of the present invention can be used as an exhaust purification catalyst for automobiles,
It can be used as a support for combustion catalysts, etc., and is particularly effective as a support for catalysts used at high temperatures. The shape and structure of such carriers include powder, pellets, and honeycomb structures. Further, the surface of a molded body made of a ceramic carrier such as cordierite or mullite or a metal carrier such as stainless steel may be coated with the thermal composite oxide (aspect of the present invention).

(Effects of the Invention) As described above, the cerium-containing BaO- of the present invention has 120. system and LazO3-AIzO:
The +-based heat-resistant synthetic oxide has a BaO or La, 03 content of 1 to 25% by weight, and a cerium content of 20% by weight.
As illustrated in Table 1, by the following, it is possible to maintain a high specific surface area even under high temperatures, and to have a pore diameter of 50 to 200 without showing the maximum value of pore distribution, and further,
By setting the cerium content to 3% by weight or less, even if the precious metal catalyst is heat-treated at 1000'C for 4 hours after preparation, it exhibits a high degree of noble metal dispersion, as shown in Table 1. However, it is possible to control the agglomeration of precious metals. Therefore, it is possible to provide carrier GJ according to the present invention, a heat-resistant carrier that can maintain sufficient catalytic activity even at high temperatures.

Furthermore, in the method of the present invention, by using β-diketones as a method for adding barium, lanthanium, and cerium, the heat-resistant alumina composite oxide can be obtained at low cost and safely.

In addition, in this method, Ba0-Al□ which does not contain cerium
03 series and 1, az03-AlzOz series heat-resistant composite oxides are also obtained in the same manner.

Additionally, cerium oxide has been known to have a cocatalytic effect that promotes the oxidation reaction of carbon monoxide and olefinic hydrocarbons on a platinum catalyst. In oxides, cerium oxide is contained in a highly dispersed state, so
Compared to cerium oxide, which is once retained on activated alumina by the impregnation method, it has a much better promoter effect even in a small amount.
Furthermore, since its aggregation at high temperatures is suppressed, the promoter effect of cerium oxide remains stable.

(Examples) Hereinafter, the present invention will be described in more detail based on Examples, Comparative Examples, and Reference Examples.

In a 500 ml beaker, add 60.4 g of aluminum 5ec-butoxide (AI(0-sBu)+), barium acedelacetonate and 25 g of hexylene glycol to 7J [IQO °
The mixture was stirred at C for 3 hours.

At the same time, add Ce (No: +) 3' to 300 sterile beakers.
Add 75g of 611201 and add 12g of ethanol to it.
After converting g, Ba(acac)2.21
2.23 g of 1z0 was added and stirred at 50°C for 3 hours. After cooling to room temperature, filtration was performed, and an ethanol solution of the cerium acetylacetone complex was prepared.
0mp. and added to the beaker.

The resulting mixture? After stirring the 8 liquid at 100° C. for 3 hours, 17 g of water was added to hydrolyze the mixture to form a gel, and the mixture was further left at the same temperature for 10 hours to form a solid. The resulting gel was dried under reduced pressure using a rotary evaporator and then incubated in air at 250 °C for 3 h and at 450 °C for 4 h.
4χCe-(5χ
BaO-Al□03) was obtained. The specific surface area of this powder is B
The pore distribution was measured by ET method and mercury intrusion method. The results are shown in Table 1.

-17= Sodium hydroxide 5.12 in a 500 ml beaker
g in 150 ml of water, then acetylacetate
Add 13.3 g of chlorine and stir to prepare an aqueous sodium salt solution of acetylacetone. Here, 15.0 g of cerium nitrate hexahydrate (Ce(NO3)3 ・6H20) was added to 10 g of water.
Add an aqueous solution of cerium nitrate prepared by dissolving cerium nitrate in 0 ml, and stir for 2 hours. The obtained precipitate was filtered and vacuum dried to obtain cerium acetylacetate (Ce).
acac) 3) A complex was obtained.

This synthesized Ce (acac) was added to a 500-year-old heater
Add 32, 28g and 80g of hexylene glycol 1
It was stirred at 20°C for 30 minutes. During this period, aluminum sec 1 oxide (8 l (O sec
73.9 g of -Bu)3) was added and further stirred at 140°C for 4 hours. Next, 3.14 g of barium n-bu)gicide (Ba (0-nl'lu)z) and 80 g of hexylene glycol were added, and the mixture was further stirred for 4 hours.

Next, a solution prepared by diluting 10 g of water with 50 g of ethanol was added to this solution to gel it with λ, and was further left at the same temperature for 10 hours to ripen it.

The resulting gel was dried under reduced pressure using a rotary evaporator and then incubated in air at 250 °C for 3 h at 45 °C.
Baked at 0°C for 4 hours and at 1000'C for 3 hours, 4χC
e-(10χBa0-Al□03) was obtained. The specific surface area of this powder was measured by the IIET method and is shown in Table 1. The straddling pore distribution was measured by mercury intrusion method, and the pore distribution curve is shown in FIG. 1, and the pore diameter showing the maximum value is shown in Table 1.

Fruit Dish 1 In Example 1, in addition to the 500 mp, capacity beaker, the amount of barium acetylacel-nate dihydrate used was 1.7.
Same as Example 1 except that 0g was changed to 5.10g,
4χCe-(14χBa0-AlzO3) was obtained. The specific surface area of this powder was measured by the BET method, and the pore distribution was measured by the mercury intrusion method. The results are shown in Table 1.

In Example 1, the amount of barium acetylacetonate dihydrate added to the 500 ml cracker was 1.70.
In the same manner as in Example 1 except that g was changed to 6.80 g,
4χCe-(18χBaO-Al2O) was obtained. The specific surface area of this powder was measured by the BET method, and the pore distribution was measured by the mercury intrusion method. The results are shown in Table 1.

Field trip 1 In a 500mρ beaker, 91.89 g of aluminum 1so-propoxide (Al(0-4Pr):+),
Barium acetylacetonate dihydrate (Ba(aca)
c)z ・211□0) 6.17g and 50g of hexylene glycol were added and stirred at 100°C for 3 hours.

At the same time, 300 ml cracker Ce (NO:+)
3' Put 611205.03g, add 150g of ethanol to it and dissolve it, then Ba(acac)z ・
06.47 g of 211z was added and stirred at 50°C for 3 hours. After cooling to room temperature, filter, prepare an ethanol solution of the cerium acetylacetone complex, and add this solution to the above-mentioned 5.
00ml beaker.

The resulting mixed solution was stirred at 100° C. for 3 hours, then 53 g of water was added to hydrolyze it into a gel, and it was further left at the same temperature for 10 hours to age. The resulting gel was dried under reduced pressure using a rotary evaporator and then calcined in air at 250°C for 3 hours, 450'C for 4 hours, and 1000'C for 3 hours to give 6XCe-(10χ
Ba0-Al. 03) was obtained. The specific surface area of this powder is B
The pore distribution was measured by ET method and mercury intrusion method. The results are shown in Table 1.

In Example 5, when preparing an ethanol solution of cerium acetylacetone complex, Ce (NOs): + 61
1206.73g, Ba(acac)z・211
8χCe-(10χBaO-A1203) was obtained in exactly the same manner as in Example 2 except that 8.64 g of zO was used. The specific surface area of this powder was measured by the BET method, and the pore distribution was measured by the mercury intrusion method. The results are shown in Table 1.

Disaster spot 1 500 ml cracker barium hydroxide octahydrate 3°15g, methyl acetoacetate 2.5h, ethyl acetate 20
, 8g was heated at 75°C for 30 minutes. 55.28 g of aluminum proboxoxide and 26 g of hexylene glycol were added thereto, and heated and stirred at 100"C for 3 hours. To this solution, 3.03 g of cerium nitrate hexahydrate and barium acetylacetone dihydrate were added. Salt 3.
Ce made in the same manner as in Example 1 using 89 g
- An ethanol solution of acetylacetone was added, and the mixture was further stirred at 100°C for 4 hours.

Hydrolysis was carried out using 35.5 g of water, and the same procedure as in Example 1 was carried out to obtain 8ICe-(10χBa0-A]zO+). The specific surface area of this powder was measured by the BET method, and the pore distribution was measured by the mercury porosimetry. The results are shown in Table 1.

Disaster relief ■ t-butyl acetoacetate instead of methyl acetoacetate 3.4
8χCe-(
10χBa0-Al□03) was obtained. The specific surface area of this powder was measured by the BET method, and the pore distribution was measured by the water root injection method. The results are shown in Table 1.

- Add 1.41 g of barium oxide, 2.4 g of dimethyl malonate, and 15 g of dioxane to a 100 mQ beaker.
The reaction was carried out at 0°C to synthesize barium dimethyl malonate. In a 300 m beaker, add 60.4 g of this barium dimethyl malonate and aluminum S-butoxide.
Add 40g of hexylene glycol and add 100g of hexylene glycol. The mixture was stirred at 'C for 4 hours.

To this solution, 3.75 g of cerium nitrate hexahydrate and 4.81 g of barium acetylacetone dihydrate were used to prepare the following Ce.acetylacetone 1-
An ethanol solution of 100% was added thereto, and the mixture was further stirred at 100°C for 4 hours.

Hydrolysis was carried out using 35.5 g of water, and 8χCe-(10χBa0-AIz03) was obtained in the same manner as in Example 1. The specific surface area of this powder was measured by the BET method, and the pore distribution was measured by the mercury porosimetry. The results are shown in Table 1.

Performance side I+ 1-0 8 in the same manner as in Example 9 except that 3.4 g of di-i-propyl malonate was used in place of dimethyl malonate.
χCe-(10χBa0-AI□oz) was obtained. The specific surface area of this powder was measured by the BET method, and the pore distribution was measured by the mercury porosimetry. The results are shown in Table 1.

Implementation ± 50 hours + barium hydroxide octahydrate salt 5,2 in 1 volume beaker
4g of diethylmalonic acid, 5.84g of diethylmalonic acid, and 50cc of hexylene glycol were added, and the mixture was heated at 80°C for 2 hours.

Add 110% of aluminum oxide to this solution.
8g was added and heated at 110°C for further 3 hours.

To this solution was added an ethanol solution of Ce/acetylacetone prepared in the same manner as in Example 1 using 6.73 g of cerium nitrate hexahydrate and 8.64 g of barium acetylacetone dihydrate, and the solution was further heated at 110 g for 3 hours. Stirred at ゛C.

Hydrolysis was carried out using 53 g of water, and 8χCe-(10XBaO-A]□O+) was obtained in the same manner as in Example 1. The specific surface area of this powder was measured by the BET method, and the pore distribution was measured by the mercury porosimetry. The results are shown in Table 1.

Implementation method ■ In Example 5, when preparing the ethanol solution of the cerium acetylacetone complex, Ce(NO*)+・6H2
010,59g, Ba(acac)2 ・2H2
12χCe-(10χBaO-^1□03) was obtained in exactly the same manner as in Example 5 except that 60 g of 013.013 was used.

The specific surface area of this powder was measured by the BET method, and the pore distribution was measured by the mercury intrusion method. The results are shown in Table 1.

141 Example■ In Example 5, when preparing an ethanol solution of cerium acetylacetone complex, Ce(NO:+):+6
112019.75 g, Ba(acac)z・
20XCe-(10χBa0-AIZ(h)) was obtained in exactly the same manner as in Example 5 except that 36 g of 2H2025 was used.The specific surface area of this powder was measured by the BET method, and the pore distribution was measured by the mercury intrusion method. The results are shown in Table 1.

Implementation ±■ In Example 5, when preparing the ethanol solution of the cerium acetylacetone complex, Ce(NO+): +・61
1206.73g, Ba(acac)z・2tl
8χCe-(10χBa0-Al□03) was obtained in exactly the same manner as in Example 2 except that 8.64 g of zO was used. The specific surface area of this powder was measured by the BET method, and the pore distribution was measured by the mercury intrusion method. The results are shown in Table 1.

In a 500 mfl beaker, add aluminum diS-butoxy acetoacetate ethyl ester chelate (8 liters).
(0-Cdl,Oz) 2 (C61190:1)9
Add 0.6g and 20g of ethylene glycol and heat to 110°C.
The mixture was stirred for 3 hours.

Next, 8.1 g of water was slowly added at 110°C. After another 30 minutes, a solution prepared by diluting 5 g of water with 20 g of ethanol was added to form a gel, and the mixture was further left at the same temperature for 10 hours to ripen. The resulting gel was dried under reduced pressure using a rotary evaporator and then dried in air for 25 minutes.
3 hours at 0'C, 4 hours at 450'C, 1000°
It was calcined at C for 3 hours to obtain AhO3. The specific surface area of this powder was measured by the BET method, and the pore distribution was measured by the mercury intrusion method. The results are shown in Table 1.

Add 5.31 g of cerium ammonium nitrate ((NH4)zce(NO3)s) and 20 g of ethylene glycol to a 500 ml volume heater and stir at 120°C for 30 minutes, then add aluminum di-S-butoxy.・Acetoacetic ethyl ester chelate (AI(0-Cdl)
90.6 g of q(h)z(CJqO3) was added and stirred for further 3 hours.

Next, 8.1 g of water was slowly added at 110°C. After another 30 minutes, a solution prepared by diluting 5 g of water with 20 g of ethanol was added to form a gel, and the mixture was further left at the same temperature for 10 hours to form a gel. The resulting gel was dried under reduced pressure using a rotary evaporator and then dried in air for 25 minutes.
It was baked at 0°C for 3 hours, at 450°C for 4 hours, and at 1000°C for 3 hours to obtain ^1□03. The specific surface area of this powder was measured by the BET method, and the pore distribution was measured by the mercury intrusion method. The results are shown in Table 1.

In Example 5, in a 500 ml beaker, aluminum jso-propo kit (Al(Oi-Pr): +
)91.89g, barium acetylacetone-1/2
Water salt (lla(acac)z 2tlzO) 23.9
4g and 50g of hexylene glycol, and
Ce (N03) 3.6 tlz when making 8 cycles of 7 volumes of cerium acetylacetone 11)
O42,4g, Ba(acac)z 2t1203
30 in exactly the same manner as in Example 5 except that 7.2 g was used.
χCe-(30χBa0-A1□03) was obtained. The specific surface area of this powder was measured by the BET method, and the pore distribution was measured by the mercury intrusion method. The results are not shown in Table IQ.

↓ In a 500 volume beaker, 391.89 g of aluminum 1so-propoxide (AI (Oi-Pr)), barium acetylacetonate dihydrate (Ba (acac)
・211zO) 6.17g and hexylene glycol 50
g and stirred at 100"C for 3 hours.

53 g of water was added to the obtained viscous solution to cause hydrolysis and gelatinization, and the solution was further aged by leaving it at the same temperature for 10 hours. The resulting gel was dried under reduced pressure using a rotary evaporator, and then calcined in air at 250 °C for 3 hours, 450 °C for 4 hours, and 1000 °C for 3 hours.
10'' ABaO-AlzOz was obtained. The specific surface area of this powder was 180 m2/g, and the maximum distribution of pores was 82.

Add 6.06 g of sodium hydroxide to 100 ml of water in a 300 ml beaker and add 8 g of acetylacetone to this.
was added to neutralize and dissolve. Add 21% of lanthanum nitrate hexahydrate to this solution. , 67 g was added to synthesize a lanthanum acetylacetone complex.

Hereinafter, in place of barium acetylacetone in Comparative Example 4, this lanthanum acetylacetone complex 6.22
10χL in exactly the same manner as Comparative Example 4 except that g was used.
azO3-Al2O2 was obtained. The specific surface area of this powder is 1
50 m2/g, and the maximum distribution pore size was 94 people.

Kita-Kango 500mp. In a large beaker, add 73.9 g of aluminum/butoxide and 3.9 g of barium/n-butoxide. 14
g and 80 g of hexylene glycol were added and stirred at 120°C for 3 hours.

Hydrolysis was carried out using 25 g of water, and the same procedure as in Comparative Example 4 was carried out to obtain 10χBaO-A1203. The specific surface area of this powder was 1.83 m2/g, and the maximum distributed pore diameter was 82 mm.

The powders obtained in Examples 2, 5 to 14 and Comparative Examples 4 to 6 were used as carriers and impregnated with a nitric acid aqueous solution of dinitrodiammine platinum at a concentration of 1 g/l to support 1% by weight of platinum in each. A platinum catalyst was prepared. This catalyst is heated to 1000° in air.
After high-temperature heat treatment for 4 hours at
According to "metal surface area measurement method using rcO pulse method",
- Measured by carbon oxide adsorption method.

The results are also shown in Table 1.

Capacitor opening I Activated alumina manufactured by Condeia, SnA200. After supporting platinum in the same manner as in Reference Example 1, the temperature was increased to 1000°C.
A high-temperature heat treatment was performed for 4 hours, and then platinum dispersion measurement was performed. The results are also shown in Table 1.

Reference Example 3 Automobile exhaust purification was performed using the platinum catalyst prepared in Reference Example 1 using the composite oxides of Examples 2, 5, 6, 12 to 14, and Comparative Example 4, and the platinum catalyst prepared in Reference Example 2. The oxidation reaction of carbon monoxide (CO), which is a typical reaction of a catalyst, was carried out at a stoichiometric composition of C0.0.5χ, 0□;, 0.25χ.

Table 2 does not show the temperature T50 at which CO reacts with 50χ. This T
The lower the 5o, the higher the activity of the catalyst.

Reference source↓ In this example, the characteristics of a catalyst carrier made of the composite oxide of the present invention and a conventionally used activated alumina as a catalyst for automobile exhaust purification will be compared and explained.

The conventional catalyst is activated alumina manufactured by Condeia, 5BA200. used in Reference Example 2. was impregnated with cerium nitrate to a concentration of 3% by weight and fired, then 25% by weight of cerium oxide powder was added and coated on the cordierite honeycomb with disbural alumina, dried, fired, Next, it was impregnated with platinum and rhodium at a weight ratio of 10:1 so that the total amount of noble metals was 35 g/cf, and was further dried and fired.

In addition, the catalyst using the composite oxide of the present invention was added to 6XCe-(10χBa0-Al□03) of Example 5 at 25% by weight.
of cerium oxide was added thereto, and the catalyst was coated with disbural alumina. Thereafter, the catalyst was prepared in exactly the same manner as the conventional catalyst.

The thus obtained catalysts were subjected to high-temperature heat treatment at 980°C for 24 hours, and the high-temperature durability performance was compared.

A gas having the automobile exhaust gas composition shown in Table 3 is heated at a space velocity of 275
Table 4 shows the temperatures at which carbon monoxide, hydrocarbons, and -nitrogen oxide were each removed through a 90χ reaction. The lower the temperature at the wood surface, the better the catalytic activity.

table" Table-1

[Brief explanation of the drawing]

Figure 1 shows the 4χCe-(10″ABaO-
It is a pore distribution curve diagram of AlzO:+) powder. Patent applicant Institute of Technology Patent applicant Nissan Motor Co., Ltd.

Claims (1)

[Claims] 1. The following general formula CeO_z-M_xO_y-Al_2O_3 (M in the formula
_xO_y is BaO or La_2O_3, z is 1.5
2) containing 3 to 20% by weight of cerium, the content of M_xO_y in M_xO_y-Al_2O_3 is 1 to 25% by weight, and the pore diameter showing the maximum value of the pore distribution is 50 to 20% by weight. A heat-resistant composite oxide characterized by having a thickness of 200 Å. 2. In the presence of one or more oxygen-containing organic compounds having multiple functional groups, aluminum alkoxide and the following general formula R_1-CO-CH_2-CO-R_2 (R_1 and R_2 in the formula are the same) A homogeneous solution is obtained by mixing at least one β-diketone selected from complex compounds of barium, lanthanium and cerium, represented by β-diketones (representing an alkyl group or an alkoxy group), and then forming a homogeneous solution. A method for producing a heat-resistant composite oxide, which comprises hydrolyzing to form a sol and then gelling it, drying the gel, and then firing it.