JP3695623B2 - Method for producing composite metal oxide - Google Patents

Description

【００３５】
図２より、 800℃で焼成したものでは、実施例中で実施例３が最も比表面積が小さい。しかし実施例３のAl−Ti複合酸化物でも比較例１及び比較例３と同等の比表面積を有し、他の実施例のAl−Ti複合酸化物は比較例１及び比較例３より高い比表面積を有していることがわかる。また 900℃で焼成したものでは、実施例４を除いて実施例のAl−Ti複合酸化物が比較例より高い比表面積を示していることがわかる。
【００３６】
したがって本発明の製造方法によれば焼成温度が 800℃の場合には加熱温度を35℃以上とし、焼成温度が 900℃の場合には加熱温度を50℃以上とすることにより、従来の製造方法に比べて同等以上の比表面積をもつAl−Ti複合酸化物を製造できることがわかる。
図４では、各Al−Ti複合酸化物のいずれにもα-Al₂O₃のピークが観察される。α-Al₂O₃は普通のアルミナを加熱すると生成するものであるから、α-Al₂O₃の存在はAl−Ti複合酸化物となっていない遊離のアルミナの存在を証明している。しかしα-Al₂O₃のピーク強度は、実施例では加熱温度が上昇するにつれて小さくなり、実施例６で比較例２及び比較例４と同等のピーク強度となっている。したがってAl−Ti複合酸化物の均一性という観点からは、実施例６で比較例２，４と同程度であり、加熱温度が65℃及び82℃の実施例８及び実施例２では比較例２，４よりも高い均一性を有している。
【００３７】
つまり加熱温度を50℃以上とし、焼成温度を 900℃とすることにより、比較例に用いた従来の製造方法に比べて同等以上に均一なAl−Ti複合酸化物を製造することができる。これは図２の結果とも一致し、比表面積とα-Al₂O₃の含有量との間には密接な関係があることがわかるとともに、実施例の製造方法によれば比較例に比べて一層均一な組成のAl−Ti複合酸化物を確実に製造できることが明らかである。
【００３８】
一方、図３では、各Al−Ti複合酸化物のいずれにもα-Al₂O₃のピークは観察されず、 800℃までの焼成温度であれば加熱温度を35℃としても比較例と同等に均一なAl−Ti複合酸化物を製造できることが明らかである。
以上、本発明の実施例について説明したが、この本発明の実施例には特許請求の範囲に記載した技術的事項以外に次のような各種の技術的事項の実施態様を有するものであることを付記しておく。
（１）加水分解は35〜 150℃に加熱して行うことを特徴とする請求項１に記載の複合金属酸化物の製造方法。
（２）加水分解は40〜 100℃に加熱して行うことを特徴とする請求項１に記載の複合金属酸化物の製造方法。
（３）加水分解は50〜 82℃に加熱して行うことを特徴とする請求項２に記載の複合金属酸化物の製造方法。
【００３９】
【発明の効果】
すなわち本発明の製造方法によれば、均一な組成のAl−Ti複合酸化物を容易にかつ確実に製造することができる。したがって排ガス浄化用触媒の担体として極めて有用なAl−Ti複合酸化物を安定して供給することができる。
【図面の簡単な説明】
【図１】本発明の一実施例の製造方法の工程順序を示す説明図である。
【図２】実施例及び比較例で製造されたAl−Ti複合酸化物の比表面積を示す棒グラフである。
【図３】実施例及び比較例で製造されたAl−Ti複合酸化物のＸ線回折チャート図である。
【図４】実施例及び比較例で製造されたAl−Ti複合酸化物のＸ線回折チャート図である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing an Al—Ti composite oxide that is useful as a carrier for an exhaust gas purification catalyst for automobiles. According to the production method of the present invention, a very uniform Al—Ti composite oxide can be produced.
[0002]
[Prior art]
As a support for automobile exhaust gas purification catalysts, alumina (Al ₂ O ₃ ) having a large specific surface area and high activity is widely used. Also, in recent years, purifying nitrogen oxides (NO _x ) in exhaust gas in an oxygen-excess lean atmosphere has become a challenge, and NO _x consisting of alkali metals and alkaline earth metals as well as noble metals on carriers such as Al ₂ O _3. A catalyst supporting an occlusion material has been developed (JP-A-5-317652, etc.). According to this catalyst, NO _x is adsorbed by the NO _x storage material, and it is purified by reacting with a reducing gas such as HC, so that NO _x emission can be suppressed even in a lean atmosphere.
[0003]
However, the exhaust gas contains SO ₂ resulting from sulfur contained in the fuel, which reacts with oxygen in a lean atmosphere on the noble metal to become SO _x such as SO ₃ . It is clear that this is easily converted to sulfuric acid by the water vapor contained in the exhaust gas, which reacts with the alkaline NO _x storage material to produce sulfite and sulfate, thereby reducing the function of the NO _x storage material. became. This phenomenon is called sulfur poisoning. In addition, since the porous carrier such as Al ₂ O ₃ has a property of easily adsorbing SO _x , there is a problem that the sulfur poisoning is promoted.
[0004]
On the other hand, since TiO ₂ does not adsorb SO ₂ , an experiment was conducted with the idea of using a TiO ₂ carrier. As a result, SO ₂ flows to the downstream as it is not adsorbed on the TiO _2, only SO ₂ in direct contact with the noble metal, it became clear that the degree of sulfur poisoning since only be oxidized less. However, it has also been clarified that the TiO ₂ carrier has a problem that the initial activity is low and the NO _x purification performance after the durability test remains low.
[0005]
In view of this, Japanese Patent Application Laid-Open No. 8-099034 proposes using a support made of a composite metal oxide such as TiO ₂ —Al ₂ O ₃ . Thereby, sulfur poisoning of the NO _x storage material is suppressed, and high NO _x purification ability can be secured even after the durability test.
As a method for producing such a composite metal oxide, for example, a production method disclosed in Japanese Patent Publication No. 2-033644 is known. In this production method, two or more kinds of oxygen-containing organometallic compounds are mixed in a solution containing a polar compound having multidentate or cross-linking coordination ability, gelled by hydrolysis, then dried and fired. It is a feature. According to this manufacturing method, a relatively uniform composite metal oxide can be easily manufactured.
[0006]
[Problems to be solved by the invention]
Japanese Examined Patent Publication No. 2-033644 exemplifies metal alkoxides as oxygen-containing organometallic compounds. Then, if it is going to utilize the said manufacturing method in order to manufacture Al-Ti complex oxide, it is possible to use aluminum alkoxide and titanium alkoxide.
[0007]
However, since the hydrolysis rate is different between aluminum alkoxide and titanium alkoxide, when an Al-Ti composite oxide is produced by the production method disclosed in Japanese Patent Publication No. 2-033644, as described later, a sufficiently uniform composition is obtained. It was difficult to obtain an Al—Ti composite oxide.
Therefore, in the catalyst using the Al-Ti composite oxide obtained by the production method disclosed in Japanese Patent Publication No. 2-033644 as a carrier, the sulfur poisoning suppression action by TiO ₂ becomes insufficient, and the NO _x after the durability test. The suppression of the reduction in the purification rate was insufficient.
[0008]
This invention is made | formed in view of such a situation, and it aims at enabling it to manufacture the Al-Ti complex oxide of a sufficiently uniform composition easily and stably.
[0009]
[Means for Solving the Problems]
The feature of the method for producing a composite metal oxide according to claim 1, which solves the above-mentioned problem, is that a substituted Al alkoxide in which at least one alkoxyl group of an aluminum alkoxide is substituted with a chelating agent, a salt of titanium, and an alkoxide The solution is to prepare a solution in which at least one of them is mixed in an organic solvent, hydrolyze the alkoxide in the solution, and then to dry and fire.
[0010]
The method for producing a composite metal oxide according to claim 2, further embodying the method for producing a composite metal oxide according to claim 1, is characterized in that at least one isopropoxyl of aluminum triisopropoxide. The solution is to prepare a solution in which a substituted Al propoxide whose group is substituted with ethyl acetoacetate and titanium tetraisopropoxide are mixed in an organic solvent, hydrolyze the alkoxide in the solution, and then dry and fire. .
[0011]
DETAILED DESCRIPTION OF THE INVENTION
The present inventors have studied to apply the production method disclosed in Japanese Patent Publication No. 2-033644 to the production of Al—Ti composite oxide. However, when an Al-Ti composite oxide was produced by this production method, it was clarified that the specific surface area decreased when the firing temperature was set to about 900 ° C, and that α-Al ₂ O ₃ was produced by firing. It was found that a large amount of free Al ₂ O ₃ not constituting the composite oxide remained in the Al-Ti composite oxide.
[0012]
As a result of pursuing this cause, it became clear that aluminum alkoxide has a higher hydrolysis rate than titanium alkoxide. That is, when hydrolysis is performed in a state where aluminum alkoxide and titanium alkoxide coexist, aluminum alkoxide is hydrolyzed more rapidly, so that Al ₂ O _{3 which} is not complexed after firing remains. Since Al ₂ O ₃ thus released becomes α-Al ₂ O ₃ at a high temperature and the specific surface area is reduced, there is a problem that the activity is reduced when used for a catalyst.
[0013]
Therefore, in the production method according to claim 1, a substituted Al alkoxide in which at least one alkoxyl group of the aluminum alkoxide is substituted with a chelating agent is used. By using a substituted Al alkoxide, it is considered that aluminum and titanium combine via a chelating agent.
The hydrolysis rate of the substituted Al alkoxide is smaller than that of the aluminum alkoxide, and the hydrolysis rates of the substituted Al alkoxide and the titanium alkoxide are almost the same. And since substituted Al alkoxide exists stably in an organic solvent, the malfunction which aluminum alkoxide with a large hydrolysis rate liberates by dissociation of a chelating agent does not arise.
[0014]
For these reasons, it is suppressed that free Al ₂ O ₃ that does not constitute the composite oxide remains in the Al—Ti composite oxide, and an Al—Ti composite oxide having a large specific surface area and a uniform composition is obtained. It is done.
In the production method of claim 2, a substituted Al propoxide in which at least one isopropoxyl group of aluminum triisopropoxide is substituted with ethyl acetoacetate and titanium tetraisopropoxide are used. . Since the hydrolysis rates of the substituted Al propoxide and titanium tetraisopropoxide are very close to each other, the remaining free Al ₂ O ₃ not constituting the composite oxide is further suppressed, and the specific surface area is further increased. And the Al-Ti complex oxide of a uniform composition is obtained.
[0015]
Furthermore, since the substituted Al propoxide in which the isopropoxyl group is substituted with ethyl acetoacetate is dissolved in 2-propanol at room temperature, there is also an effect that the yield of the Al—Ti composite oxide is improved twice.
The aluminum alkoxide as the Al ₂ O ₃ source is preferably an alkoxide having 1 to 5 carbon atoms in the alkoxyl group from the viewpoint of easiness of drying and the like. Aluminum methoxide, aluminum ethoxide, aluminum propoxide, aluminum isopropoxide, aluminum Butoxide, aluminum isobutoxide, and the like can be used.
[0016]
In the production method of the present invention, a substituted Al alkoxide in which at least one of the alkoxyl groups of the aluminum alkoxide is substituted with a chelating agent is used. If all of the alkoxyl groups of the aluminum alkoxide are substituted with a chelating agent, the specific surface area of the resulting Al—Ti composite oxide may decrease. Therefore, a substituted Al alkoxide in which 1 to 2 of alkoxyl groups are substituted with a chelating agent is used, and among them, in which two alkoxyl groups are substituted with a chelating agent, the hydrolysis rate depends on the hydrolysis rate of titanium alkoxide. It is especially desirable because it is close.
[0017]
As a chelating agent, dimethylglyoxime, dithizone, oxine, ethyl acetoacetate, acetylacetone, glycine, EDTA, NTA and the like can be used.
As a salt of titanium which is a TiO ₂ source, a salt which is dissolved in an organic solvent to be used is used, and nitrate, chloride, acetate, ammonium titanate, titanium complex, or the like can be used.
[0018]
The titanium alkoxide as the TiO ₂ source is preferably an alkoxide having 1 to 5 carbon atoms in the alkoxyl group from the viewpoint of easiness of drying. Titanium methoxide, titanium ethoxide, titanium propoxide, titanium isopropoxide, titanium butoxide In addition, titanium isobutoxide can be used.
The mixing ratio of the Al ₂ O ₃ source and the TiO ₂ source is determined according to the composition of the target Al—Ti composite oxide. When used as a carrier for an exhaust gas purification catalyst, mixing is preferably performed so that Al ₂ O ₃ / TiO ₂ = 30/1 to 1/30.
[0019]
As the organic solvent, those that dissolve the compound to be mixed are used, and methanol, ethanol, 1-propanol, 2-propanol, butanol, isobutanol, sec-butanol, tert-butanol and the like can be used.
In order to hydrolyze the alkoxide in the solution, moisture in the air can be used, but it is preferable to add water while stirring the solution at a predetermined temperature. The specific surface area of the resulting Al—Ti composite oxide can be further increased by causing the reaction to proceed rapidly.
[0020]
If the amount of water added is too small, it takes a long time for hydrolysis, and if it is too large, uniform hydrolysis becomes difficult and the composition of the Al—Ti composite oxide becomes non-uniform. Therefore, the amount of water added is preferably in the range of 0.5 to 20 in terms of molar ratio to the alkoxide used, and particularly preferably in the range of 1 to 10 in terms of molar ratio.
In order to further accelerate the hydrolysis reaction, it is also preferable to add a hydrolysis accelerator composed of an alkaline substance such as ammonia, ammonium carbonate or amines, or an acid such as formic acid, oxalic acid or tartaric acid.
[0021]
The heating temperature in this hydrolysis step is preferably in the range of 35 to 150 ° C. Below 35 ° C, the reaction rate is low and the reaction requires a long time. When the time is short, the residual amount of free Al ₂ O ₃ that does not complex increases. If the heating temperature exceeds 150 ° C, the alkoxide may decompose. A range of 40 to 100 ° C. is particularly desirable.
[0022]
After hydrolysis, the precipitate is dried to remove the solvent and the like, and then fired to obtain an Al—Ti composite oxide. Drying conditions are not particularly limited. Moreover, it is preferable that a calcination temperature shall be 500-1200 degreeC. If it is less than 500 degreeC, formation of the stable Al-Ti complex oxide will become difficult, and if it exceeds 1200 degreeC, the specific surface area of Al-Ti complex oxide will fall.
[0023]
【Example】
Hereinafter, the present invention will be described specifically by way of examples.
(Example 1)
An Al—Ti composite oxide was produced according to the schematic diagram shown in FIG.
First, 154.6 g of ethyl acetate aluminum diisopropylate (Al-EAA) (substituted Al alkoxide) as the Al ₂ O ₃ source and 40.1 g of titanium tetraisopropoxide (Ti (OiC ₃ H ₇ ) ₄ ) as the TiO ₂ source Was added to 423.4 g of 2-propanol and dissolved by stirring at 82 ° C. for 2 hours (FIG. 1A).
[0024]
Next, while maintaining the above solution at 82 ° C under reflux and stirring, 121.9 g of ion-exchanged water was added dropwise to hydrolyze the alkoxide, and the mixture was aged by continuing stirring at 82 ° C under reflux for 4 hours. (FIG. 1 (B)).
Thereafter, it was dried under reduced pressure to remove the solvent, and further dried at 120 ° C. for 12 hours (FIG. 1C). Thereafter, calcination was carried out at 480 ° C. for 4 hours, followed by baking in the air at 800 ° C. for 5 hours (FIG. 1D) to obtain an Al—Ti composite oxide of this example.
[0025]
The specific surface area of the obtained Al—Ti composite oxide was measured by the BET method, and the results are shown in FIG. Further, X-ray diffraction analysis was performed, and the chart is shown in FIG.
(Example 2)
An Al—Ti composite oxide of Example 2 was obtained in the same manner as Example 1 except that the firing temperature was changed to 900 ° C. instead of 800 ° C. The specific surface area was measured in the same manner as in Example 1, and the results are shown in FIG. An X-ray diffraction chart is shown in FIG.
[0026]
(Example 3)
An Al—Ti composite oxide of Example 3 was obtained in the same manner as in Example 1 except that the heating temperature during dissolution, hydrolysis, and aging was changed to 35 ° C. instead of 82 ° C. The specific surface area was measured in the same manner as in Example 1, and the results are shown in FIG. An X-ray diffraction chart is shown in FIG.
[0027]
(Example 4)
An Al—Ti composite oxide of Example 4 was obtained in the same manner as in Example 3 except that the firing temperature was changed to 900 ° C. instead of 800 ° C. The specific surface area was measured in the same manner as in Example 1, and the results are shown in FIG. An X-ray diffraction chart is shown in FIG.
(Example 5)
An Al—Ti composite oxide of Example 5 was obtained in the same manner as in Example 1 except that the heating temperature during dissolution, hydrolysis, and aging was changed to 50 ° C. instead of 82 ° C. The specific surface area was measured in the same manner as in Example 1, and the results are shown in FIG. An X-ray diffraction chart is shown in FIG.
[0028]
(Example 6)
An Al—Ti composite oxide of Example 6 was obtained in the same manner as Example 5 except that the firing temperature was changed to 900 ° C. instead of 800 ° C. The specific surface area was measured in the same manner as in Example 1, and the results are shown in FIG. An X-ray diffraction chart is shown in FIG.
(Example 7)
An Al—Ti composite oxide of Example 7 was obtained in the same manner as in Example 1 except that the heating temperature during dissolution, hydrolysis, and aging was changed to 65 ° C. instead of 82 ° C. The specific surface area was measured in the same manner as in Example 1, and the results are shown in FIG. An X-ray diffraction chart is shown in FIG.
[0029]
(Example 8)
An Al—Ti composite oxide of Example 8 was obtained in the same manner as in Example 7 except that the firing temperature was changed to 900 ° C. instead of 800 ° C. The specific surface area was measured in the same manner as in Example 1, and the results are shown in FIG. An X-ray diffraction chart is shown in FIG.
Example 9
The Al—Ti of Example 9 was used in the same manner as in Example 1 except that 26.7 g of TiCl ₄ was used instead of 40.1 g of titanium tetraisopropoxide (Ti (OiC ₃ H ₇ ) ₄ ) as the TiO ₂ source. A composite oxide was obtained. The specific surface area was measured in the same manner as in Example 1, and the results are shown in FIG.
[0030]
(Example 10)
An Al—Ti composite oxide of Example 10 was obtained in the same manner as Example 9 except that the firing temperature was changed to 900 ° C. instead of 800 ° C. The specific surface area was measured in the same manner as in Example 1, and the results are shown in FIG.
(Comparative Example 1)
423.4 of aluminum triisopropoxide (Al (OiC ₃ H ₇ ) ₄ ) 115.1 g as an Al ₂ O ₃ source and 40.1 g of titanium tetraisopropoxide (Ti (OiC ₃ H ₇ ) ₄ ) as a TiO ₂ source g in 2-propanol and dissolved by stirring at 82 ° C. for 2 hours.
[0031]
Next, 28.2 g of 2,4-pentanedione (acetylacetone) was added dropwise while the solution was kept at 82 ° C. and stirred, and further stirred at 82 ° C. for 2 hours. Thereafter, while the solution was kept at 82 ° C. and stirred, 121.9 g of ion-exchanged water was added dropwise to hydrolyze the alkoxide, and the mixture was aged by continuing stirring at 82 ° C. for 4 hours.
Thereafter, it was dried under reduced pressure to remove the solvent, and further dried at 120 ° C. for 12 hours. Thereafter, the mixture was calcined at 480 ° C. for 4 hours and then calcined in the air at 800 ° C. for 5 hours to obtain an Al—Ti composite oxide of this comparative example. The specific surface area was measured in the same manner as in Example 1, and the results are shown in FIG. An X-ray diffraction chart is shown in FIG.
[0032]
(Comparative Example 2)
An Al—Ti composite oxide of Comparative Example 2 was obtained in the same manner as Comparative Example 1 except that the firing temperature was changed to 900 ° C. instead of 800 ° C. The specific surface area was measured in the same manner as in Example 1, and the results are shown in FIG. An X-ray diffraction chart is shown in FIG.
(Comparative Example 3)
An Al—Ti composite oxide of Comparative Example 3 was obtained in the same manner as Comparative Example 1 except that 36.7 g of ethyl acetoacetate was added dropwise instead of 28.2 g of 2,4-pentanedione (acetylacetone). The specific surface area was measured in the same manner as in Example 1, and the results are shown in FIG. An X-ray diffraction chart is shown in FIG.
[0033]
(Comparative Example 4)
An Al—Ti composite oxide of Comparative Example 4 was obtained in the same manner as Comparative Example 3 except that the firing temperature was changed to 900 ° C. instead of 800 ° C. The specific surface area was measured in the same manner as in Example 1, and the results are shown in FIG. An X-ray diffraction chart is shown in FIG.
(Evaluation)
Table 1 summarizes the types of chelating agents employed in the production of the Al-Ti composite oxides of each Example and Comparative Example, and the heating and firing temperatures during dissolution, hydrolysis and aging.
[0034]
[Table 1]

[0035]
As shown in FIG. 2, the specific surface area of Example 3 is the smallest among those fired at 800 ° C. However, the Al—Ti composite oxide of Example 3 also has a specific surface area equivalent to that of Comparative Example 1 and Comparative Example 3, and the Al—Ti composite oxides of other Examples have a higher ratio than Comparative Examples 1 and 3. It can be seen that it has a surface area. Moreover, in what was baked at 900 degreeC, it turns out that the Al-Ti complex oxide of an Example has shown the specific surface area higher than a comparative example except Example 4. FIG.
[0036]
Therefore, according to the production method of the present invention, when the firing temperature is 800 ° C., the heating temperature is 35 ° C. or higher, and when the firing temperature is 900 ° C., the heating temperature is 50 ° C. or higher. It can be seen that an Al—Ti composite oxide having a specific surface area equal to or greater than that of can be produced.
In FIG. 4, an α-Al ₂ O ₃ peak is observed in each of the Al—Ti composite oxides. Since α-Al ₂ O ₃ is produced when ordinary alumina is heated, the presence of α-Al ₂ O ₃ proves the presence of free alumina that is not an Al-Ti composite oxide. However, the peak intensity of α-Al ₂ O ₃ decreases as the heating temperature increases in the example, and in Example 6, the peak intensity is the same as that of Comparative Example 2 and Comparative Example 4. Therefore, from the viewpoint of uniformity of the Al—Ti composite oxide, Example 6 is comparable to Comparative Examples 2 and 4, and the heating temperatures of 65 ° C. and 82 ° C. in Examples 8 and 2 are Comparative Example 2. , 4 has a higher uniformity.
[0037]
That is, by setting the heating temperature to 50 ° C. or higher and the firing temperature to 900 ° C., it is possible to manufacture an Al—Ti composite oxide that is equal to or more uniform than the conventional manufacturing method used in the comparative example. This agrees with the results in FIG. 2 and shows that there is a close relationship between the specific surface area and the content of α-Al ₂ O ₃ , and according to the production method of the example, compared to the comparative example. It is clear that an Al—Ti composite oxide having a more uniform composition can be reliably produced.
[0038]
On the other hand, in FIG. 3, no α-Al ₂ O ₃ peak is observed in any of the Al—Ti composite oxides, and the firing temperature up to 800 ° C. is equivalent to the comparative example even if the heating temperature is 35 ° C. It is clear that a uniform Al—Ti composite oxide can be produced.
Although the embodiments of the present invention have been described above, the embodiments of the present invention have embodiments of the following various technical matters in addition to the technical matters described in the claims. Is noted.
(1) The method for producing a composite metal oxide according to claim 1, wherein the hydrolysis is performed by heating to 35 to 150 ° C.
(2) The method for producing a composite metal oxide according to claim 1, wherein the hydrolysis is performed by heating to 40 to 100 ° C.
(3) The method for producing a composite metal oxide according to claim 2, wherein the hydrolysis is performed by heating to 50 to 82 ° C.
[0039]
【The invention's effect】
That is, according to the production method of the present invention, an Al—Ti composite oxide having a uniform composition can be produced easily and reliably. Therefore, it is possible to stably supply an Al—Ti composite oxide that is extremely useful as a carrier for an exhaust gas purification catalyst.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing a process sequence of a manufacturing method according to an embodiment of the present invention.
FIG. 2 is a bar graph showing specific surface areas of Al—Ti composite oxides produced in Examples and Comparative Examples.
FIG. 3 is an X-ray diffraction chart of Al—Ti composite oxides produced in examples and comparative examples.
FIG. 4 is an X-ray diffraction chart of Al—Ti composite oxides produced in examples and comparative examples.

Claims (4)

And at least one substituent Al alkoxide alkoxyl group is substituted with a chelating agent of the aluminum alkoxide, and at least one salt of titanium and alkoxide solution prepared by mixing in an organic solvent to prepare the alkoxide at solution of A method for producing a composite metal oxide, which comprises drying and firing after hydrolysis. And aluminum triisopropoxide substituted Al propoxide that at least one of isopropoxyl group is substituted with ethyl acetoacetate Sid, to prepare a solution of a mixture of titanium tetraisopropoxide in an organic solvent, the solution in A method for producing a composite metal oxide, which comprises hydrolyzing an alkoxide with, followed by drying and firing. Hydrolysis 35 ~  150 The method for producing a composite metal oxide according to claim 1, which is carried out by heating to ° C. Hydrolysis 50 ~ 82 The method for producing a composite metal oxide according to claim 2, which is carried out by heating to ° C.

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