JP2003192632A - Method for producing mixture of unsaturated carboxylic acid ester with unsaturated carboxylic acid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a new method for producing a mixture of an unsaturated carboxylic acid ester and an unsaturated carboxylic acid by which the unsaturated carboxylic acid ester is produced using an unsaturated aldehyde and an alcohol as raw materials and the unsaturated carboxylic acid can simultaneously be obtained during a reaction so that the mixture of the unsaturated carboxylic acid ester and the unsaturated carboxylic acid having a low content of difficult- to-separate by-products can readily be purified into the high-purity unsaturated carboxylic acid ester and unsaturated carboxylic acid. <P>SOLUTION: This method for producing the mixture of the unsaturated carboxylic acid ester with the unsaturated carboxylic acid comprises reacting the unsaturated aldehyde with the alcohol in the presence of a noble metal catalyst and molecular oxygen in the liquid phase. In the method, water is present in the liquid phase and at least a part of the water is added before and/after starting the reaction. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a mixture of an unsaturated carboxylic acid ester and an unsaturated carboxylic acid.

[0002]

2. Description of the Related Art As a method for producing a carboxylic acid ester,
A method is known in which an aldehyde compound is used as a raw material, and this is reacted with an alcohol compound and molecular oxygen. For example, as an industrially useful method for producing methyl methacrylate or methyl acrylate, a method of forming an ester in one step from methanol and molecular oxygen using methacrolein or acrolein as a raw material has been attracting attention. Compared with the two-step method in which an aldehyde is converted to an acid and then to an ester, this method has shorter steps and a high yield, and can be said to be an industrially advantageous method.

However, this production method is useful when the carboxylic acid ester is mainly required, but when the carboxylic acid is also required to some extent, the obtained carboxylic acid ester is further hydrolyzed. Therefore, it is necessary to convert the carboxylic acid into a carboxylic acid, and it is necessary to additionally perform both the hydrolysis reaction and the purification step, which makes the manufacturing process very complicated.

Further, in the above-mentioned production method, acetal is liable to be produced as a side reaction product with the carboxylic acid ester, and generally the boiling point of the acetal is close to the boiling point of the carboxylic acid ester. Separation and purification are difficult by the purification method, and a complicated purification method is required to obtain a high-purity carboxylic acid ester.

[0005]

The main object of the present invention is to:
A method for producing an unsaturated carboxylic acid ester using an unsaturated aldehyde compound and an alcohol compound as raw materials,
An unsaturated carboxylic acid can be obtained at the same time during the reaction, and the obtained mixture of unsaturated carboxylic acid ester and unsaturated carboxylic acid has a small amount of by-products which are difficult to separate and has a high purity of unsaturated carboxylic acid. It is to provide a novel method for producing a mixture of an unsaturated carboxylic acid ester and an unsaturated carboxylic acid, which can be easily separated into an acid ester and an unsaturated carboxylic acid.

[0006]

The inventor of the present invention has conducted extensive studies in order to achieve the above object. As a result, in the method of producing an unsaturated carboxylic acid ester by reacting an unsaturated aldehyde compound, an alcohol compound and molecular oxygen, water is present in the reaction solution from the start of the reaction, or water is added during the reaction. When water is present in the reaction solution by addition, the unsaturated carboxylic acid ester can be produced simultaneously with the unsaturated carboxylic acid ester, and, surprisingly, the boiling point is close to that of the unsaturated carboxylic acid ester. It was found that the amount of acetal, which is a side reaction product, is extremely small, and it is possible to separate the highly pure unsaturated carboxylic acid ester and unsaturated carboxylic acid by a simple distillation method. The present invention has been completed.

That is, the present invention provides the following method for producing a mixture of an unsaturated carboxylic acid ester and an unsaturated carboxylic acid. 1. A method for producing a mixture of an unsaturated carboxylic acid ester and an unsaturated carboxylic acid by reacting an unsaturated aldehyde compound and an alcohol compound in a liquid phase in the presence of a noble metal catalyst and molecular oxygen, the method comprising: Is present, and at least a part of the water is water added before and / or after the start of the reaction, the method for producing a mixture of an unsaturated carboxylic acid ester and an unsaturated carboxylic acid. . 2. The method for producing a mixture of an unsaturated carboxylic acid ester and an unsaturated carboxylic acid according to item 1, wherein the amount of water present in the liquid phase is 4% by mass or more. 3. The noble metal catalyst is at least one catalyst selected from a catalyst in which ultrafine gold particles are supported on an inorganic oxide carrier, and a catalyst in which metal particles containing gold and another secondary element are supported on the carrier. 1. A method for producing a mixture of an unsaturated carboxylic acid ester and an unsaturated carboxylic acid according to 1 or 2.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The production method of the present invention is a method of reacting an unsaturated aldehyde compound and an alcohol compound in a liquid phase in the presence of a noble metal catalyst and molecular oxygen. Hereinafter, this method will be specifically described. Examples of the unsaturated aldehyde compound used as the raw material compound include α, β-unsaturated aldehydes having 3 to 10 carbon atoms such as acrolein, methacrolein, and crotonaldehyde; benzaldehyde, p-methoxybenzaldehyde, tolualdehyde, phthalaldehyde, and terephthalate. Examples include aromatic aldehydes having 6 to 20 carbon atoms such as aldehydes and furfural, and derivatives of these aldehydes.
Preferably, α, β-unsaturated aldehyde and the like can be used.
These aldehyde compounds may be used alone or in combination of two or more.

As the alcohol compound, methanol,
Aliphatic alcohols having 1 to 10 carbon atoms such as ethanol, isopropanol, octanol; ethylene glycol,
Examples thereof include diols having 2 to 10 carbon atoms such as butanediol; aliphatic unsaturated alcohols having 3 to 10 carbon atoms such as allyl alcohol and methallyl alcohol; and aromatic alcohols such as benzyl alcohol. Preferably, the carbon number is 1 to
Ten aliphatic alcohols and the like can be preferably used. These alcohol compounds may be used alone or in combination of two or more.

In the production method of the present invention, the above-mentioned aldehyde compound and alcohol compound may be appropriately selected depending on the kind of the desired carboxylic acid ester. For example, when synthesizing methyl methacrylate, methacrolein may be used as the aldehyde and methanol as the alcohol. Noble metal catalyst In the production method of the present invention, a noble metal catalyst is used as the catalyst. As the noble metal, for example, gold, ruthenium, palladium, rhodium, platinum and the like can be preferably used. These noble metals may be used as alloys or mixtures with other metals.

The form of the noble metal catalyst is not particularly limited, and it can be used in various forms usually used as a catalyst. For example, it can be used as a powder, a granulated product, or the like, and may be used by being supported on various carriers.
The supported amount may be in the same range as that of a usual catalyst, and is, for example, 0.01 to 2 with respect to 100 parts by weight of the carrier.
It may be in the range of about 0 parts by weight.

In the present invention, in particular, a catalyst in which ultrafine gold particles are supported on an inorganic oxide carrier (hereinafter referred to as "gold ultrafine particle supported catalyst")
Or a catalyst in which metal particles containing gold and another secondary element are supported on a carrier (hereinafter, may be referred to as “second element-containing gold-supported catalyst”). These catalysts are catalysts having particularly high activity when used in the production method of the present invention, and by using them, the target product can be obtained in high yield with good selectivity. These catalysts may be used alone, or two or more different types may be mixed and used. Hereinafter, these catalysts will be specifically described. (1) Ultrafine gold particle supported catalyst: In the ultrafine gold particle supported catalyst,
Gold (Au) is preferably present as ultrafine particles having an average particle size of about 6 nm or less, and more preferably as ultrafine particles having an average particle size of about 5 nm or less. As described above, by using gold as ultrafine particles, a high catalytic activity is exhibited due to a synergistic effect with the inorganic oxide carrier. The lower limit of the average particle size of ultrafine gold particles is not particularly limited, but may be about 1 nm from the viewpoint of physical stability. The average particle size of the ultrafine gold particles is an arithmetic average value of 100 arbitrarily selected particle sizes when the ultrafine gold particles on the carrier are observed by a transmission electron microscope (TEM).

The carrier is not particularly limited as long as it can support the gold ultrafine particles described above, and a catalyst carrier used in the conventional carboxylic acid ester synthesis can also be used. For example, various carriers such as oxides, metal oxides, composite metal oxides, zeolites, mesoporous silicates, and activated carbon can be mentioned. Of these, oxides, metal oxides, composite oxides and the like can be preferably used. For example, an oxide containing at least one element of Si, Al, Ti and Z is preferable. Specifically, silica, alumina, titania, zirconia, magnesia, silica-alumina, titania-silica, silica-magnesia and the like can be preferably used as the carrier.

The carrier is preferably porous, and its specific surface area (BET method) is usually 50 m ² / g.
More preferably, it is more preferably 100 m ² / g or more. The shape and size of the carrier are not limited, and may be appropriately determined depending on the use of the final product.

The amount of ultrafine gold particles supported on the ultrafine gold particle-supported catalyst may be appropriately determined depending on the intended use of the final product, the type of carrier, etc. 01 to 20 parts by weight, especially 0.1 to 10
It is preferable to use parts by weight.

The method for producing the catalyst supporting ultrafine gold particles is not particularly limited as long as it is a method capable of supporting predetermined ultrafine gold particles. As the supporting method itself, a known method such as a coprecipitation method, a precipitation-precipitation method, an impregnation method, or a vapor deposition method can be used. Among these loading methods, a coprecipitation method, a precipitation-precipitation method and the like are preferable, and a precipitation-precipitation method is particularly preferable. When the catalyst is produced by using the precipitation method, for example, a gold ultrafine particle-supported catalyst is obtained by mixing an aqueous solution of a water-soluble compound containing gold and an inorganic oxide carrier and then calcining the recovered solid content. You can

The water-soluble compound containing gold is not limited as long as it is water-soluble. For example, tetrachloroaurate (III) acid “H [AuCl ₄ ]”, sodium tetrachloroaurate (III) “Na [AuCl ₄ ]”, potassium dicyanoaurate (I) “K [Au (CN) ₂ ]”. , Diethylamine gold (III)
Complex such as trichloride “(C ₂ H ₅ ) ₂ NH [AuCl ₃ ]”;
Gold compounds such as gold (I) cyanide can be mentioned. These compounds may be used alone or in combination of two or more.

The gold concentration of the above aqueous solution varies depending on the kind of the compound used and the like, but is usually 0.1 to 100 mmol.
It may be about 1 / l. Further, the pH of the above-mentioned aqueous solution may be set usually within the range of about 5 to 10, preferably within the range of 6 to 9. The pH of the aqueous solution can be adjusted with an alkali such as sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate or ammonia. Also,
If necessary, an acid such as hydrochloric acid can be used. If necessary, these alkalis or acids may be used in the form of an aqueous solution.

The inorganic oxide carrier mixed with the above aqueous solution is
It may be used in any form such as a granular form or a granulated form. The amount of the carrier used may be appropriately set depending on the concentration of the aqueous solution, the type of carrier used, and the like. When mixing the aqueous solution and the inorganic oxide carrier, the aqueous solution may be heated if necessary. The temperature in this case is usually 10 to 10
It may be about 0 ° C. The mixing time of the aqueous solution and the carrier can be changed depending on the kind of the carrier, constituent elements, etc., but is usually about 1 minute to 24 hours, preferably 10 minutes to 3
It suffices to set the gold-containing precipitate as much as possible on the carrier within the range of time. The amount of the carrier to be used may be appropriately set so as to give a predetermined amount to be supported.

Subsequently, the inorganic oxide carrier is mixed with an aqueous solution of a water-soluble compound containing gold, and the solid content is recovered. The method for recovering the solid content is not limited, and it can be carried out, for example, by collecting the supernatant or by a known solid-liquid separation method. The collected solid content is preferably washed with deionized water or the like until the residual ions are substantially eliminated.

Then, the solid content (immobilized gold) is fired. If necessary, it may be dried by heating to a temperature of less than 150 ° C. in advance before firing. The firing temperature is usually about 150 to 800 ° C, preferably about 200 to 700 ° C, and most preferably about 250 to 600 ° C. The firing temperature may be appropriately set so that predetermined gold ultrafine particles are obtained within this temperature range. The firing atmosphere may be air (atmosphere) or an oxidizing atmosphere, or may be an inert gas atmosphere such as argon gas or helium, or a reducing atmosphere such as hydrogen gas. Moreover, the firing time may be appropriately determined depending on the firing temperature, the size of the solid content, and the like. The target catalyst for supporting ultrafine gold particles can be obtained by such calcination.

Particularly, in the case of a catalyst in which ultrafine gold particles are supported on a silica carrier or a carrier containing silica, the catalyst surface may be subjected to an organic silylation treatment. By such treatment, it is possible to improve the catalyst performance, the life stability, and the like. A known method can be applied to the organic silylation treatment itself, such as methoxytrimethylsilane, trimethylsilyl chloride,
It may be carried out by a gas phase method or a liquid phase method using a silylating agent such as hexamethyldisilazane. (2) Second element-containing gold-supported catalyst: The second element-containing gold-supported catalyst is a catalyst in which metal particles containing gold and other second elements are supported on a carrier.

In the second element-containing gold-supported catalyst, the metal particles supported on the carrier are mainly composed of Au as the first element and the second element. Also preferably contains both gold and the second element. Further, gold and the second element may form an alloy or an intermetallic compound as long as a predetermined effect can be obtained.

As the second element, it is preferable to use at least one element of 2B group, 3B group, 4B group, 5B group and 6B group of the fourth to sixth periods of the periodic table. In particular,
Zn, Cd, Hg as the 2B group (zinc group), Ga, In, Tl as the 3B group (boron group), Ge, Sn, Pb as the 4B group (carbon group), As as the 5B group (nitrogen group),
Sb, Bi, 6B group (oxygen group) as Se, Te, Po
Etc. can be illustrated. In the present invention, it is preferable that at least Pb is contained as the second element. For example, a catalyst in which metal particles containing Au and Pb are supported on a carrier can be preferably used.

In the second element-containing gold-supported catalyst, the particle size of the supported metal particles is not limited as long as a predetermined catalytic activity can be obtained, but the average particle size is preferably about 6 nm or less, It is more preferably about 5 nm or less. By setting the average particle diameter within this range, it is possible to more reliably obtain excellent catalytic activity. The average particle size of the metal particles is arbitrarily selected when the metal particles on the carrier are observed by a transmission electron microscope (TEM).
It is an arithmetic mean value of 0 particles.

In the second element-containing gold supported catalyst, the same carrier as the above-mentioned gold ultrafine particle supported catalyst can be used as the carrier.

Further, the second element-containing gold-supported catalyst may contain other components as long as the catalyst activity is not hindered.
For example, alkali metals (Na, K, etc.), alkaline earth metals (Ca, Mg, etc.), etc. may be contained.

The amount of gold supported on the second element-containing gold supported catalyst may be appropriately determined according to the intended use of the final product, the type of carrier, etc., but is usually 0.0 with respect to 100 parts by weight of the carrier.
The amount is preferably about 1 to 20 parts by weight, more preferably 0.1 to 10 parts by weight.

The amount of the second element supported on the second element-containing gold-supported catalyst may be appropriately determined according to the type of the second element, the type of the carrier, etc., but usually 100 parts by weight of the carrier are used. 0.01 to 20 parts by weight, preferably 0.1
It is preferably 10 to 10 parts by weight.

The supported ratio of gold and the second element is not particularly limited as long as it is within the above supported amounts, but usually, the atomic ratio of gold: second element = 1: 0.01 to 100, preferably. Is 1: 0.1-10, most preferably 1: 0.2-5
And By setting the amount within this range, it is possible to obtain a more excellent catalytic activity.

The method for producing the second element-containing gold-supported catalyst is not limited as long as the catalyst having the above-mentioned structure can be obtained.
For example, it can be obtained by heat-treating a carrier containing at least one of gold and its compound, and at least one of a second element and its compound. The gold compound and the compound of the second element are all hydroxides, chlorides,
It may be any of carboxylate, nitrate, alkoxide, acetylacetonate salt and the like.

Further, the order of supporting the gold and the second element on the carrier is not limited, and any of them may be carried out first or simultaneously. That is, any of the following manufacturing methods (A) to (C) can be used. That is, (A) a method of supporting gold on a carrier and then supporting a second element, and (B) a method of supporting a second element on a carrier,
A method of supporting gold and a method of simultaneously supporting (C) gold and a second element on a carrier can be applied. Hereinafter, each method will be described.

Manufacturing Method (A) The above method (A) is a method in which gold is supported on a carrier and then a second element is supported.

In this method, first, a gold carrier on which gold is supported is manufactured. The manufacturing method of the gold carrier is not limited,
For example, a conventional method such as a coprecipitation method, a precipitation-precipitation method, an impregnation method, or a vapor deposition method can be applied. Of these, the coprecipitation method and the precipitation-precipitation method are preferable, and the precipitation-precipitation method is particularly preferable.

When the precipitation-precipitation method is used, it is carried out in the same manner as the method for supporting gold in the catalyst for supporting ultrafine gold particles described above.
For example, a gold carrier can be obtained by allowing a carrier to coexist in an aqueous solution containing a gold compound, depositing a gold-containing precipitate on the surface of the carrier, and then calcining the carrier on which the gold-containing precipitate is deposited.

Next, at least one of the second element and its compound is supported on the gold carrier, and then heat-treated to combine gold and the second element.

The above-mentioned supporting method is not limited and can be carried out according to a conventional method. For example, an impregnation method, an ion exchange method, a vapor deposition method, etc. may be mentioned. Of these, the impregnation method can be preferably used. For example, the second element can be favorably supported by preparing a mixture of a solution in which a compound containing the second element is dissolved and the gold carrier, and then heat treating the solid content recovered from the mixture.

The compound containing the second element is not particularly limited, but it is an inorganic compound such as nitrate, sulfate, hydroxide or chloride, formate, acetate, acetylacetonate salt,
Organic compounds such as alkoxide can be exemplified. More specifically, lead acetate, zinc nitrate, bismuth nitrate and the like can be mentioned.

The solution in which the compound containing the second element is dissolved is
It can be prepared by using a combination of a compound containing the second element and a solvent in which it dissolves. The solvent is not particularly limited, but water, an organic solvent or the like can be used. The organic solvent is, for example, alcohol. Examples thereof include ketones, aromatic hydrocarbons, carboxylic acid esters, nitriles and the like. In particular, it is preferable to use at least one of water and alcohol (particularly methanol and ethanol). Therefore, it is preferable that the above-mentioned combination uses the above-mentioned compounds soluble in water or alcohol. For example, when Pb is used as the second element, a solution in which lead acetate (a hydrate may be used) is dissolved in methanol can be preferably used.

The concentration of the second element in the solution in which the compound containing the second element is dissolved can be appropriately determined according to the type of the above compound, the type of solvent, etc., but usually 0.01 to 10 mmol /
It may be about l.

The mixing ratio of the gold carrier and the solution in which the compound containing the second element is dissolved is
It can be appropriately determined depending on the desired amount of gold or the second element supported.

After preparing a mixture of the gold carrier and a solution in which the compound containing the second element is dissolved, the solid content is recovered from the mixture. The method for recovering the solid content is not limited, but for example, a compound containing the second element may be supported on the gold carrier. For example, it is preferable to remove the solvent by using an evaporator or the like.

Next, heat treatment of the solid content is carried out. The heat treatment temperature may be a temperature at which each metal particle obtained is composed of gold and the second element. That is, the heat treatment may be performed so that when the finally obtained metal-containing composition is used as a catalyst, the catalytic activity due to the composite of gold and the second element is exhibited.

The heat treatment temperature varies depending on the type of the second element and the like, but is generally about 50 to 800 ° C, preferably 100 to 600 ° C.

The heat treatment atmosphere is not particularly limited, and may be any of reducing atmosphere, oxidizing atmosphere, inert atmosphere and the like. In order to create a reducing atmosphere, for example, reducing gas such as hydrogen, carbon monoxide, alcohol, etc., or a mixed gas obtained by diluting these reducing gases with an inert gas such as nitrogen, helium, or argon can be used. good. Further, in order to obtain an oxidizing atmosphere, a gas containing oxygen, air, etc. may be used. To create an inert atmosphere, nitrogen, helium,
An inert gas such as argon may be used. In the present invention, a reducing atmosphere is particularly desirable. Alternatively, the heat treatment may be performed in an oxidizing atmosphere and then in a reducing atmosphere.

The heat treatment time can be appropriately changed depending on the temperature of the heat treatment and the like, but it is usually about 10 minutes to 24 hours.

Depending on the type of the second element, in order to further promote the complexation with gold, the solid content is subjected to a reduction treatment with a reducing agent such as formalin, hydrazine, sodium borohydride and formic acid prior to the above heat treatment. You may.

Method (B) In the method (B) , after the second element is supported on the carrier,
It is a method of supporting gold. The method of supporting the second element is not limited and, for example, the same method as the above (A) can be used. That is, first, the second element may be supported on the carrier by the same method as in the above (A). The raw material of the second element, the supporting conditions, etc. may be the same as those listed in (A) above.

However, in some cases, as a preferable additional treatment for the subsequent gold supporting operation, the second element is burned at about 300 to 900 ° C. in an oxidizing atmosphere (in the presence of air or a gas containing oxygen). It can be firmly immobilized on a carrier. The gold can be carried on the second element carrier thus produced by the same method as in the above (A). That is, after depositing gold by a precipitation method or the like, drying and firing may be performed in the same manner as in the above (A).
Further, as in the case of (A) above, it is desirable to perform the heat treatment under a reducing atmosphere similar to that of (A) above in order to more sufficiently form the complex of gold and the second element. Further, if necessary, reduction treatment using a reducing agent can be combined.

Method (C) The above method (C) is a method of simultaneously supporting gold and the second element on a carrier. For example, gold and the second element can be simultaneously loaded on the carrier by a precipitation-precipitation method. Specifically, when gold is carried on the carrier by the precipitation-precipitation method in the above (A), both can be carried by coexisting a compound containing the second element in the system. Further, a material carrying both of them can be heat-treated in the same manner as in the above (A) and (B). Method for Producing Carboxylic Acid and Carboxylic Acid Ester Mixture The method for producing the method of the present invention is a method of reacting an unsaturated aldehyde compound and an alcohol compound in a liquid phase in the presence of the above-mentioned noble metal catalyst and molecular oxygen.

In this method, it is necessary to carry out the reaction between the unsaturated aldehyde compound and the alcohol compound in the liquid phase. As a specific method, a method in which an unsaturated aldehyde compound and an alcohol compound are dissolved in a solvent to carry out the reaction, or when the reaction is carried out under the condition that the alcohol compound can exist as a liquid, the alcohol compound is used as a solvent A method of carrying out the reaction in a state in which the unsaturated aldehyde compound is dissolved can be adopted.

In the method of carrying out the reaction in a solvent, the solvent that can be used may be any solvent which can dissolve both the unsaturated aldehyde compound and the alcohol compound and does not participate in the reaction. Specific examples of such a solvent include:
Saturated hydrocarbons such as pentane, hexane, cyclohexane and octane; aromatic hydrocarbons such as benzene and toluene; ethers such as diethyl ether and diisopropyl ether; esters such as methyl acetate and ethyl acetate. .

The concentration of the raw material compound in the solvent is not particularly limited, but normally, the concentration of the aldehyde compound is preferably about 1 to 60% by mass,
More preferably, it is about 40% by mass.

The ratio between the unsaturated aldehyde compound and the alcohol compound is not particularly limited, but the molar ratio of unsaturated aldehyde compound / alcohol compound is preferably about 10/1/200, and particularly preferably within the range of 1 / 2-1 / 50. More preferable. Within the above range, unsaturated carboxylic acid ester and unsaturated carboxylic acid can be efficiently synthesized.

When the unsaturated aldehyde compound is dissolved in the liquid alcohol compound to carry out the reaction, it is preferable that the alcohol compound is present in an amount equal to or more than equimolar to the unsaturated aldehyde compound. Aldehyde compound / alcohol compound molar ratio is 1 to 1/20
About 0 is preferable, and the range of 1/2 to 1/50 is particularly preferable.

In the production method of the present invention, it is necessary to carry out the reaction in a state where water is present in the liquid phase, and at least a part of the water present in the liquid phase is before or at the start of the reaction. It must be water added during the post-reaction or water added both before and after the start of the reaction. By carrying out the reaction in a liquid phase containing water added in this manner, an unsaturated carboxylic acid ester and an unsaturated carboxylic acid can be simultaneously formed,
In addition, it becomes possible to greatly reduce the amount of acetal, which is a by-product.

On the other hand, when the reaction is carried out without adding water, water is generated by the reaction between the unsaturated aldehyde compound and the alcohol compound, but the amount of water generated in this case is usually The amount is insufficient to suppress the generation of reaction products, and when an attempt is made to increase the concentration of aldehyde compounds to increase the amount of water generated, side reactions increase, which is the target product. The selectivity between unsaturated carboxylic acid ester and unsaturated carboxylic acid is greatly reduced.

The amount of water present in the liquid phase is, as the concentration in the liquid phase excluding the catalyst, suitably about 4% by mass or more, and about 5% by mass or more, at any time of the reaction. It is preferable that it is about 6 mass% or more. The presence of such an amount of water at any time during the reaction can greatly reduce the amount of acetal, which is a by-product, in particular. When the concentration of water in the liquid phase is in the range of about 4 to 25% by mass, the amount of acetal as a by-product is extremely small and the reaction rate and reaction efficiency are good. Can be demonstrated. In this case, the concentration of water in the liquid phase is
It is preferably within the range of about 4 to 25% by mass at the end of the reaction, and more preferably within the range of about 4 to 25% by mass at the start of the reaction.

As a method of adding water before the start of the reaction,
Usually, before starting the reaction, water may be added together with the unsaturated aldehyde compound and the alcohol compound which are the raw materials,
When the unsaturated aldehyde compound or alcohol compound as the raw material contains water, the water contained in the raw material is also supplied together with the raw material to be water added before the start of the reaction. For example, after the unsaturated carboxylic acid ester and the unsaturated carboxylic acid are produced by the method of the present invention, unreacted unsaturated aldehyde compound and alcohol compound are recovered, and when this is recycled as a raw material, a recovery tower for a recycled raw material is sufficient. If water is contained in the unsaturated aldehyde compound or alcohol compound that is the recycled raw material without being separated into, or if water is contained in this when using a new raw material, use these as raw materials. Thus, water is added to the liquid phase before the reaction starts. In the present invention, the water added before the start of the reaction includes both water supplied together with such raw materials and water supplied separately.

As a method of adding water after the start of the reaction, usually, water may be added during the reaction at a suitable time after the start of the reaction until the end of the reaction. In the case of successively adding later, water contained in the raw material is also supplied together with the raw material, and water is added to the liquid phase during the reaction. For example, if the recycled raw material contains water, or if it contains water when a new raw material is used, these may be added sequentially after the start of the reaction so that after the reaction is started, liquid is added during the reaction. Water will be added during the phase.

In the present invention, water may be added at any time before the start of the reaction or after the start of the reaction, and the form of the added water includes water in addition to water itself. As long as it is in any form.

In the production method of the present invention, the reaction form is not particularly limited, and any of continuous method, batch method and semi-batch method may be used.

The method of using the catalyst is not particularly limited, and any method may be used as long as the unsaturated aldehyde compound, the alcohol compound and the oxygen, which are the starting materials, can sufficiently contact the catalyst during the reaction.

For example, when the reaction is carried out in a batch system, generally, the catalyst is collectively charged in the liquid phase together with the raw materials,
The reaction may be performed under stirring. When the reaction is carried out in a continuous manner, the liquid phase is charged with the catalyst together with the raw material and continuously supplied to the reaction apparatus, or the catalyst is previously charged into the reaction apparatus and the raw material is contained therein. The liquid phase may be continuously supplied. When the catalyst is charged in the reactor, the reactor may be in any form such as a fixed bed, a fluidized bed and a suspension bed.

The amount of the catalyst used is not particularly limited and may be appropriately determined depending on the type of raw material, the type of catalyst, the type of polar solvent, the reaction conditions and the like. For example, the catalyst may be added in the liquid phase. In the case of charging, the amount of the catalyst used is not particularly limited, but usually, it is preferably about 0.01 to 50% by mass, and about 0.1 to 20% by mass based on the total amount of the solution. Is more preferable. Further, a method of continuously supplying a solution containing a raw material and hydrogen to a reactor charged with a catalyst,
For example, in a method of continuously supplying a solution containing a raw material and an oxygen-containing gas to a reactor in which a catalyst is fixed or filled, the average residence time or contact time of the solution in the catalyst layer is about 1 minute to 2 hours. Is preferable and about 3 minutes to 1 hour is more preferable.

As the molecular oxygen, in addition to pure oxygen gas, one diluted with an inert gas such as nitrogen gas, argon gas, helium gas or carbon dioxide gas may be used, or air may be used.

As a method of supplying molecular oxygen, when the reaction is carried out in a batch system, the total pressure by the oxygen-containing gas is 0.0
Oxygen or an oxygen-containing gas is supplied to the reactor so that the pressure is about 1 to 10 MPa, preferably about 0.1 to 5 MPa, and, if necessary, oxygen or an oxygen-containing gas is added so that the total pressure can be maintained during the reaction. Just add it. When the reaction is carried out in a continuous system, the total pressure due to the oxygen-containing gas is still 0.0
Oxygen or an oxygen-containing gas may be continuously supplied into the reactor so that the pressure is about 1 to 10 MPa, preferably about 0.1 to 5 MPa. As a method of supplying oxygen or an oxygen-containing gas into the reaction apparatus, it may be added from the gas phase portion of the reaction apparatus, or may be supplied by bubbling in the liquid phase.

Various conditions such as the reaction temperature may be appropriately determined depending on the combination of the unsaturated aldehyde compound and the alcohol compound, the kind of the catalyst and the like. For example, the reaction temperature is usually about 0 to 180 ° C, preferably 20 to 150 ° C. By setting the temperature within this range, the reaction can proceed efficiently.

The pH of the liquid phase is preferably about 6 to 9 from the viewpoint of suppressing by-products. For adjusting the pH, for example, an alkali metal compound or an alkaline earth metal compound (carboxylic acid salt) can be used as an additive to the reaction system.

The reaction time is not particularly limited and may be changed depending on various reaction conditions, but usually, it is 0.5 to 20 hours as a reaction time or an average residence time (retained liquid amount in reactor / liquid supply amount). It should be within the range.

According to the above method, a mixture of unsaturated carboxylic acid ester and unsaturated carboxylic acid can be obtained. The production ratio of the carboxylic acid ester and the carboxylic acid may vary depending on the type of raw material, the reaction conditions, the amount of water present, etc., but is usually unsaturated carboxylic acid / unsaturated carboxylic acid ester (molar ratio) = 0.01 to It is within the range of about 0.3. Within such a range, for example, the production ratio of carboxylic acid can be increased by increasing the amount of water present in the liquid phase. Therefore, the production ratio of both can be set by appropriately setting the conditions. It can be controlled.

After the reaction is carried out by the above-mentioned method, the catalyst is separated by a known solid-liquid separation method such as filtration and centrifugation, and then the unsaturated carboxylic acid produced is formed by a known separation and purification means. The ester and unsaturated carboxylic acid can be recovered.

In particular, the production method of the present invention is a method having an excellent feature that the amount of acetal which is a side reaction product is extremely small. Acetals generally have a boiling point close to that of the unsaturated carboxylic acid ester, and thus it may be difficult to separate by distillation, but in the method of the present invention, since the reaction product contains almost no acetal, it is simple. An unsaturated carboxylic acid ester and an unsaturated carboxylic acid can be separated by a distillation method, and a highly pure unsaturated carboxylic acid ester and unsaturated carboxylic acid can be easily obtained.

[0074]

The method of the present invention is a method for positively producing a mixture of an unsaturated carboxylic acid and an unsaturated carboxylic acid ester with almost no acetal having a boiling point close to that of the unsaturated carboxylic acid ester. According to this method,
It is possible to produce an unsaturated carboxylic acid and an unsaturated carboxylic acid ester by a one-step reaction, and it is possible to separate an unsaturated carboxylic acid and an unsaturated carboxylic acid ester of high purity by a simple separation means such as distillation. Become.

In particular, when using at least one catalyst selected from ultrafine gold-supported catalysts and second element-containing gold-supported catalysts, it is possible to obtain the desired unsaturated carboxylic acid with high selectivity and high yield. Unsaturated carboxylic acid esters can be produced.

[0076]

EXAMPLES The present invention will be described in more detail with reference to examples.

Catalyst Production Example 1 Preparation of Pb-Au / alumina catalyst 0.5 aqueous solution of tetrachloroauric acid having an Au supported concentration of 20 mmol / l
0.5 mol while keeping the liter at 65 to 70 ° C
PH of the above aqueous solution using a sodium hydroxide aqueous solution
Adjusted to 7. To this aqueous solution, 40 g of commercially available γ-alumina (trade name “AC-12R” manufactured by Sumitomo Chemical Co., Ltd.) was put under stirring, and stirring was continued for 1 hour while maintaining at 65 to 70 ° C.
After that, the supernatant liquid is removed by allowing to stand still, 0.8 liter of ion-exchanged water is added to the remaining gold-immobilized product, the mixture is stirred at room temperature for 5 minutes, and the supernatant liquid is removed. It was The gold-immobilized product obtained by filtration was used at 100 ° C for 1
It was dried for 0 hour, and further calcined in air at 400 ° C. for 3 hours to obtain a gold-supported material (Au / γ-alumina) in which gold was supported on γ-alumina. The amount of gold supported on this carrier was measured by fluorescent X-ray analysis, and it was 4.6% by mass based on the carrier.

10 g of the above gold-supported material was added to 30 ml of a methanol solution containing 0.74 g of Pb-complexed lead acetate trihydrate, and then methanol was distilled off at room temperature with an evaporator. 10m inside diameter of the remaining solid
It was filled in a glass tube of m, and a mixed gas consisting of 10% hydrogen and 90% argon was circulated at a flow rate of 6 liters / hour for 3 hours while heating the packed bed to 450 ° C. Thus, a catalyst (Pb-Au / alumina catalyst) in which metal particles containing gold and lead were supported on an alumina carrier was obtained. The amount of lead supported on this catalyst was measured by fluorescent X-ray analysis, and as a result, it was 4.0% by mass based on the carrier.

Further, the state analysis of the metal species of this catalyst was examined by a transmission electron microscope (TEM) (device name "HF-2000", Hitachi Ltd., accelerating voltage 200 kV (hereinafter the same)). As a result, the average particle size of the metal particles was about 3 nm. Furthermore, as a result of investigating the composition of each metal particle, both gold and lead components were detected in every metal particle.

Example 1 In a SUS stirring type 100 cc autoclave, 1 g of methacrolein (manufactured by Tokyo Chemical Industry Co., Ltd., reagent), 15 g of methanol (manufactured by Wako Pure Chemical Industries, Ltd., special grade reagent), 3 g of water
And the Pb-Au / alumina catalyst obtained in Catalyst Production Example 1.
After charging 5 g and purging with nitrogen, 0.2 MPa of nitrogen and 0.3 MPa of oxygen were added under pressure. The mixture was heated to 80 ° C. with stirring and maintained at the same temperature for 2 hours. After cooling, the package was opened and the contents were analyzed by gas chromatography. The results are shown in Table 1 below.

Comparative Example 1 Table 1 below shows the results obtained by carrying out the reaction in Example 1 without adding water both at the start of the reaction and during the reaction. When the amount of water in the liquid phase at the start of the reaction was measured by a Karl Fischer water content measuring device, the amount of water was less than 0.1% by mass, and it was found that the reaction was started in a state substantially containing no water. It could be confirmed.

As is clear from Table 1, as compared with Example 1 in which the reaction was carried out by adding water, the production ratio of methacrylic acid to methyl methacrylate was very small, and the side reaction product methacryl The selectivity of rain dimethyl acetal was high.

Example 2 10 g of methacrolein (manufactured by Tokyo Chemical Industry Co., Ltd., reagent), 47.5 g of methanol (manufactured by Wako Pure Chemical Industries, Ltd., special grade reagent) were placed in a 200 cc stirring type SUS autoclave.
4 g of water and 2 g of the Pb-Au / alumina catalyst obtained in Catalyst Production Example 1 were charged, and after nitrogen substitution, 0.2 MPa of nitrogen and 0.3 MPa of oxygen were added under pressure. The mixture was heated to 80 ° C. with stirring and maintained at the same temperature for 4 hours. After cooling, the package was opened and the contents were analyzed by gas chromatography. The results are shown in Table 1 below.

Example 3 The catalyst was filtered off from the reaction solution obtained in Example 2, and the remaining solution was distilled under atmospheric pressure at a reflux ratio of 2 using a glass packed distillation column having 10 theoretical plates. The unreacted methacrolein and methanol were recovered. As a result, the total is 43.2g
The recovered liquid was obtained, and the recovered liquid contained methacrolein (3.8 g), methanol (33.9 g), methyl methacrylate (4.3 g) and water (1.2 g).

Next, this recovered liquid was charged into a SUS stirring type 200 cc autoclave, and methacrolein 10 was added.
g, methanol 47.5 g, methacrolein (manufactured by Tokyo Chemical Industry Co., Ltd., reagent) and methanol (manufactured by Wako Pure Chemical Industries, Ltd., special grade reagent) were newly added. Further, 2 g of the Pb-Au / alumina catalyst obtained in Catalyst Production Example 1
Was charged and the reaction was carried out under the same conditions as in Example 2.

After cooling, the package was opened and the contents were analyzed by gas chromatography. The results are shown in Table 1 below.

[0087]

[Table 1]

Catalyst Production Example 2 Preparation of Au / Zirconia Catalyst 6 ml of 500 ml of an aqueous solution of chloroauric acid having a concentration of 10 mmol / l was added.
While maintaining the temperature at 5 to 70 ° C., the pH of the aqueous solution was adjusted to 7 using 0.5N sodium hydroxide aqueous solution. To this aqueous solution, 10 g of commercially available zirconia (manufactured by Norton) was added with stirring, and stirring was continued for 1 hour while maintaining the temperature at 65 to 70 ° C and pH 7 to 8. After that, the supernatant liquid is removed by allowing to stand still, 0.8 liter of ion-exchanged water is added to the remaining gold-immobilized product, the mixture is stirred at room temperature for 5 minutes, and the supernatant liquid is removed. It was The gold-immobilized product obtained by filtration was dried at 100 ° C. for 10 hours, and further dried in air.
By firing at 00 ° C. for 3 hours, a gold-supported material (Au / zirconia) in which gold was supported on a zirconia carrier was obtained.

The amount of gold supported on this carrier was measured by fluorescent X-ray analysis, and it was 4.4% by mass based on the carrier. Further, the state analysis of the metal species of this supported material was examined by a transmission electron microscope (TEM). As a result, the average particle size of the gold particles was about 4 nm.

Example 4 2.5 g of acrolein (a reagent manufactured by Tokyo Kasei Kogyo Co., Ltd.) and hydrous ethanol (anhydrous ethanol manufactured by Wako Pure Chemical Industries, Ltd.) were added to a 100 cc stirring type stainless steel autoclave manufactured by SUS to contain water. 15 ml of a water amount of 3% by mass) and 1 g of the Au / zirconia catalyst obtained in Catalyst Production Example 2 were charged, and N
After _two substitutions, and the N ₂ was 0.3MPa each pressure added 0.2MPa with oxygen. While stirring, warm to 70 ° C and bring to the same temperature for 3
Maintained for hours. In this case, the water concentration in the liquid phase at the time of charging the raw materials was 2.5% by mass.

After cooling, the package was opened and the contents were analyzed by gas chromatography. The results are shown in Table 2 below.

Example 5 In place of the water-containing ethanol having a water content of 3% by mass used in Example 4, water was added to anhydrous ethanol manufactured by Wako Pure Chemical Industries, Ltd. to make the water content at 5% by mass. Was used and the reaction was performed in the same manner as in Example 4 except for the above. In this case, the water concentration in the liquid phase when the raw materials were charged was 4.2.
It was mass%.

After cooling, the package was opened and the contents were analyzed by gas chromatography. The results are shown in Table 2 below.

Example 6 In place of the water-containing ethanol having a water content of 3% by mass used in Example 4, water was added to anhydrous ethanol manufactured by Wako Pure Chemical Industries, Ltd. to make the water content 10% by mass. Was used and the reaction was performed in the same manner as in Example 4 except for the above.
In this case, the water concentration in the liquid phase when the raw materials were charged was 8.
It was 4% by mass.

After cooling, the package was opened and the contents were analyzed by gas chromatography. The results are shown in Table 2 below.

[0096]

[Table 2]

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) C07C 67/08 C07C 67/08 69/653 69/653 // C07B 61/00 300 C07B 61/00 300

Claims (3)

[Claims] 1. A method for producing a mixture of an unsaturated carboxylic acid ester and an unsaturated carboxylic acid by reacting an unsaturated aldehyde compound and an alcohol compound in a liquid phase in the presence of a noble metal catalyst and molecular oxygen. Water is present in the liquid phase, and at least part of the water is
Alternatively, the method for producing a mixture of an unsaturated carboxylic acid ester and an unsaturated carboxylic acid, which is water added after the start of the reaction. 2. The method for producing a mixture of an unsaturated carboxylic acid ester and an unsaturated carboxylic acid according to claim 1, wherein the amount of water present in the liquid phase is 4% by mass or more. 3. The noble metal catalyst is at least one selected from a catalyst in which ultrafine gold particles are supported on an inorganic oxide support, and a catalyst in which metal particles containing gold and other secondary elements are supported on the support. The method for producing a mixture of an unsaturated carboxylic acid ester and an unsaturated carboxylic acid according to claim 1 or 2, which is a catalyst.