JP2006137729A - METHOD FOR PRODUCING alpha,beta-UNSATURATED CARBOXYLIC ACID - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To produce an α,β-unsaturated carboxylic acid from an olefin in high selectivity by using a noble metal-containing catalyst in the presence of molecular oxygen in liquid phase. <P>SOLUTION: A noble metal-containing catalyst is washed with a washing liquid containing at least an organic solvent and the washed catalyst containing noble metal is used in the production of an α,β-unsaturated carboxylic acid. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing an α, β-unsaturated carboxylic acid from an olefin using a noble metal-containing catalyst.

  A method for producing an α, β-unsaturated carboxylic acid by liquid phase oxidation of olefin with molecular oxygen using a noble metal-containing catalyst has been studied extensively, and α, β-unsaturated with high selectivity. Several methods have been reported for producing a noble metal-containing catalyst capable of producing a carboxylic acid.

Patent Document 1 describes a method in which a palladium salt or palladium metal is reduced under appropriate conditions in a water-containing organic solvent to form an amorphous palladium catalyst. Patent Document 2 describes a method in which a noble metal is supported on activated carbon having a specific surface area of 100 m ² / g or more and 1000 m ² / less. Patent Document 3 describes a method of reducing a compound containing a palladium atom in an oxidized state at −5 ° C. to 50 ° C.
International Publication WO02 / 083299 Pamphlet JP 2004-141828 A JP 2004-141863 A

  However, when liquid phase oxidation of olefin was performed using the noble metal-containing catalyst produced by the method described in Patent Documents 1 to 3, it was found that the selectivity of α, β-unsaturated carboxylic acid may be lowered. did.

  Accordingly, an object of the present invention is to provide a method for producing an α, β-unsaturated carboxylic acid from an olefin with high selectivity.

  The present invention relates to a method for producing an α, β-unsaturated carboxylic acid from an olefin using a noble metal-containing catalyst in a liquid phase in the presence of molecular oxygen, wherein the noble metal-containing catalyst is prepared by a cleaning liquid containing at least an organic solvent. A method for producing an α, β-unsaturated carboxylic acid, comprising washing and performing a reaction for producing an α, β-unsaturated carboxylic acid using the washed noble metal-containing catalyst.

  According to the present invention, α, β-unsaturated carboxylic acid can be produced with high selectivity.

  The present invention relates to a process for producing an α, β-unsaturated carboxylic acid from an olefin using a noble metal-containing catalyst (hereinafter sometimes simply referred to as “catalyst”) in the liquid phase in the presence of molecular oxygen. In which a noble metal-containing catalyst is washed with a washing solution containing at least an organic solvent, and an α, β-unsaturated carboxylic acid production reaction is carried out using the washed noble metal-containing catalyst. It is a manufacturing method of carboxylic acid. By adopting such a method, it is possible to produce α, β-unsaturated carboxylic acid with high selectivity.

  For cleaning the noble metal-containing catalyst, a cleaning liquid containing at least an organic solvent is used. As the organic solvent, alcohols, ketones, carboxylic acids, carboxylic acid esters, hydrocarbons and the like can be used. Examples of alcohols include methanol, ethanol, tertiary butanol, tertiary amyl alcohol, and cyclohexanol. Examples of ketones include acetone, methyl ethyl ketone, diethyl ketone, methyl isobutyl ketone, di-n-propyl ketone, and diisopropyl ketone. Examples of carboxylic acids include acetic acid, propionic acid, n-valeric acid, isovaleric acid and the like. Examples of carboxylic acid esters include ethyl acetate and methyl propionate. Examples of the hydrocarbons include hexane, cyclohexane, and toluene. Among these, ketones having 3 to 6 carbon atoms, tertiary butanol, and tertiary amyl alcohol are preferable. The solvent may be one type or a mixed solvent of two or more types.

  It is also preferable to select a solvent used in the production reaction of the α, β-unsaturated carboxylic acid as the cleaning liquid. In this case, the production reaction of the α, β-unsaturated carboxylic acid can be stably performed from the initial stage.

  In the present invention, the above organic solvent can be used alone as the cleaning liquid, but the α, β-unsaturated carboxylic acid can be produced with high selectivity from the initial stage of the production reaction of the α, β-unsaturated carboxylic acid. Since it can do, it is preferable to use the water-containing organic solvent which is a mixed solvent of said organic solvent and water. Although the quantity of the water in the mixed solvent with water is not specifically limited, 2 mass% or more is preferable with respect to the total mass of a mixed solvent, and 5 mass% or more is more preferable. Moreover, 70 mass% or less is preferable, and 50 mass% or less is more preferable.

  Here, in the above-described cleaning liquid, it is preferable that the content of carboxylic acids is as small as possible. The content of carboxylic acids in the cleaning liquid is preferably 40% by mass or less, more preferably 20% by mass or less, and still more preferably 5% by mass or less with respect to the total mass of the cleaning liquid.

  The washing can be performed twice or more. In that case, the cleaning liquid used for the last cleaning should just satisfy | fill the above, and there is no restriction | limiting in particular in the cleaning agent used for the cleaning performed before it.

  The reason why the α, β-unsaturated carboxylic acid can be produced with high selectivity by washing with the above-described washing solution is estimated as follows. In noble metal-containing catalysts that can be used for liquid phase oxidation of olefins, impurities derived from catalyst raw materials, reducing agents, reducing solvents, etc. used in the production often remain. In particular, in the case of a noble metal-containing catalyst in which carboxylic acids remain as impurities, simultaneously with the progress of liquid phase oxidation of olefins, ester compounds derived from these carboxylic acids are by-produced, and α, β-unsaturation which is the target product It is thought that the phenomenon that the selectivity of carboxylic acid falls occurs. Therefore, as in the present invention, the noble metal-containing catalyst is washed with a washing solution containing at least an organic solvent, and then liquid phase oxidation of the olefin is performed, so that carboxylic acids remaining as impurities are reduced, and the target product is It is considered that the selectivity of a certain α, β-unsaturated carboxylic acid is increased.

  The cleaning method for the noble metal-containing catalyst is not particularly limited. For example, a method in which the manufactured noble metal-containing catalyst is filtered and then a cleaning liquid is added from above, and the noble metal-containing catalyst is dispersed in the cleaning liquid and then separated by filtration or centrifugation. The technique to do is mentioned. When performing the filtration, an operation in an inert gas stream is preferable. The amount of the cleaning solution used for the cleaning is preferably a cleaning solution having a mass of 3 times or more with respect to the mass of the noble metal-containing catalyst in order to sufficiently remove impurities that may hinder the reaction. It is more preferable. As the amount of the cleaning liquid increases, the effect increases. However, since a substantially sufficient effect can be obtained, it is preferable to use a cleaning liquid having a mass of 100 times or less.

  As the noble metal-containing catalyst before washing used in the present invention, a commercially available noble metal-containing catalyst or a noble metal-containing catalyst produced by bringing a compound containing a noble metal into contact with a reducing agent can be used. When using a commercially available catalyst, it is preferable to use a catalyst activated by bringing the catalyst into contact with a reducing agent.

  The noble metal in the noble metal-containing catalyst used in the present invention is palladium, platinum, rhodium, ruthenium, iridium, gold, silver, or osmium. Among them, palladium, platinum, rhodium, ruthenium, iridium, and gold are preferable, and palladium is particularly preferable.

  Hereinafter, the manufacturing method of the noble metal containing catalyst performed by making a noble metal compound contact with a reducing agent is demonstrated.

  The noble metal compound to be used is not particularly limited. For example, noble metal chlorides, oxides, acetates, nitrates, sulfates, tetraammine complexes and acetylacetonato complexes are preferable, and noble metal chlorides, acetates and nitrates are preferable. More preferred.

  The noble metal compound is reduced by contacting with a reducing agent, but the reduction is preferably performed in a liquid phase. Hereinafter, a method for performing the reduction in the liquid phase will be described.

  When producing an unsupported catalyst, a noble metal compound solution in which a noble metal compound is dissolved in a solvent is prepared. When producing a catalyst supported on a support, a support and a noble metal compound are added to a solvent in a desired order or simultaneously to prepare a noble metal compound solution in which the support is dispersed. The concentration of the noble metal compound is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, and particularly preferably 0.5% by mass or more. Moreover, 20 mass% or less is preferable, 10 mass% or less is more preferable, and 7 mass% or less is especially preferable. Next, a reducing agent is added to the liquid to reduce the noble metal compound, thereby obtaining a noble metal-containing catalyst.

Examples of the carrier include activated carbon, carbon black, silica, alumina, magnesia, calcia, titania and zirconia. Among them, activated carbon, silica and alumina are preferable. The specific surface area of the carrier cannot be generally described because the preferred range varies depending on the type of carrier and the like, but in the case of activated carbon, 100 m ² / g or more is preferable, and 300 m ² / g or more is more preferable. Moreover, 5000 m < ² > / g or less is preferable and 4000 m < ² > / g or less is more preferable. The smaller the specific surface area of the carrier, the more the catalyst with the useful component supported on the surface can be produced, and the larger the specific surface area, the more the catalyst with the useful component supported.

  In the case of using a carrier, the precious metal loading is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and further preferably 1% by mass or more with respect to the mass of the carrier before loading. Moreover, 40 mass% or less is preferable, 30 mass% or less is more preferable, and 20 mass% or less is further more preferable.

  As the solvent to be used, water is preferable, but ethanol, 1-propanol, 2-propanol, n-butanol, t-butanol may be used depending on the solubility of the noble metal compound and the reducing agent and the dispersibility of the carrier when the carrier is used. Alcohols such as acetone; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; carboxylic acids such as acetic acid, n-valeric acid and isovaleric acid; and organic solvents such as hydrocarbons such as heptane, hexane and cyclohexane alone Or it can be used in combination. A mixed solvent of these and water can also be used.

  The reducing agent to be used is not particularly limited. For example, hydrazine, formaldehyde, sodium borohydride, hydrogen, formic acid, formic acid salt, ethylene, propylene, 1-butene, 2-butene, isobutylene, 1,3-butadiene, 1- Examples include heptene, 2-heptene, 1-hexene, 2-hexene, cyclohexene, allyl alcohol, methallyl alcohol, acrolein, and methacrolein.

  When the reducing agent is a gas, it is preferably carried out in a pressurizing apparatus such as an autoclave in order to increase the solubility in the solution. At that time, the inside of the pressurizer is pressurized with a reducing agent. The pressure is preferably 0.1 MPa or more (gauge pressure; hereinafter, all pressure notations are referred to as gauge pressure notations). Moreover, it is preferable to set it as 1.0 Mpa or less.

  Moreover, when a reducing agent is a liquid, there is no restriction | limiting in the apparatus which reduces a noble metal compound, It can carry out by adding a reducing agent in a noble metal compound solution. The amount of the reducing agent used at this time is not particularly limited, but it is preferably 1 mol or more and 1 mol or less with respect to 1 mol of the noble metal compound.

  The temperature of the system and the reduction time during the reduction vary depending on the reduction method, the noble metal compound used, the solvent, the reducing agent, and the like, and thus cannot be generally stated. Moreover, 150 degrees C or less is preferable and 80 degrees C or less is more preferable. The reduction time is preferably 0.1 hour or longer, more preferably 0.25 hour or longer, and further preferably 0.5 hour or longer. Moreover, 4 hours or less are preferable, 3 hours or less are more preferable, and 2 hours or less are more preferable.

  After the reduction, the noble metal-containing catalyst is separated. The presence or absence of a noble metal in the solvent from which the catalyst is separated can be easily confirmed by adding a reducing agent such as hydrazine. The amount of noble metal in the solvent can be quantified by elemental analysis such as ICP. The noble metal contained in the reduced solvent is preferably 10 mg / l or less. This amount can be adjusted by the concentration of the noble metal compound before the reduction, the reduction conditions, and the like. The separated catalyst is subjected to the above-described catalyst washing and replacement treatment.

  And after washing | cleaning with a washing | cleaning liquid as mentioned above, (alpha), (beta)-unsaturated carboxylic acid is manufactured as follows.

  Next, a method for producing an α, β-unsaturated carboxylic acid by oxidizing an olefin as a raw material with molecular oxygen in a liquid phase will be described.

  Examples of the raw material olefin include propylene, isobutylene, 2-butene and the like. The α, β-unsaturated carboxylic acid to be produced is an α, β-unsaturated carboxylic acid having the same carbon skeleton as the olefin used as a raw material. Specifically, acrylic acid is obtained when the raw material is propylene, and methacrylic acid is obtained when the raw material is isobutylene.

  In the present invention, α, β-unsaturated aldehyde is often produced as a by-product. The by-product α, β-unsaturated aldehyde is an α, β-unsaturated aldehyde having the same carbon skeleton as the olefin used as a raw material. Specifically, when the raw material is propylene, acrolein is by-produced, and when the raw material is isobutylene, methacrolein is by-produced.

  The present invention is suitable for liquid phase oxidation for producing acrylic acid from propylene and methacrylic acid from isobutylene.

  The raw olefin may contain a small amount of saturated hydrocarbons as impurities.

  The solvent used for the liquid phase oxidation reaction is not particularly limited, and water, alcohols, ketones, carboxylic acid esters, hydrocarbons, and the like can be used. Examples of alcohols include methanol, ethanol, tertiary butanol, tertiary amyl alcohol, and cyclohexanol. Examples of ketones include acetone, methyl ethyl ketone, diethyl ketone, methyl isobutyl ketone, di-n-propyl ketone, and diisopropyl ketone. Examples of carboxylic acid esters include ethyl acetate and methyl propionate. Examples of the hydrocarbons include hexane, cyclohexane, and toluene. Among these, ketones having 3 to 6 carbon atoms, tertiary butanol, and tertiary amyl alcohol are preferable. The solvent may be one type or a mixed solvent of two or more types.

  Moreover, when using at least 1 sort (s) of alcohols, ketones, and organic acid esters, it is preferable to use it as a mixed solvent with water. The amount of water in the mixed solvent is not particularly limited, but is preferably 2% by mass or more and more preferably 5% by mass or more with respect to the mass of the mixed solvent. Moreover, 70 mass% or more is preferable and 50 mass% or less is more preferable. The mixed solvent is desirably uniform, but may be used in a non-uniform state.

  The liquid phase oxidation reaction may be carried out in either a continuous type or a batch type, but in view of productivity, the continuous type is preferred industrially.

  0.1 mass% or more is preferable with respect to the solvent which exists in the reactor, and, as for the quantity of the olefin in the reaction liquid which performs a liquid phase oxidation reaction, 0.5 mass% or more is more preferable. Moreover, 20 mass% or less is preferable and 10 mass% or less is more preferable.

  As the molecular oxygen source used in the liquid phase oxidation reaction, air is economical, but pure oxygen or a mixed gas of pure oxygen and air can also be used. If necessary, air or pure oxygen is mixed with nitrogen, dioxide. A mixed gas diluted with carbon, water vapor or the like can also be used. This gas such as air is usually supplied in a pressurized state into a reaction vessel such as an autoclave.

  The amount of molecular oxygen is preferably 0.1 mol or more, more preferably 0.3 mol or more, and further preferably 0.5 mol or more with respect to 1 mol of olefin. Moreover, 30 mol or less is preferable, 25 mol or less is more preferable, and 20 mol or less is further more preferable.

  Usually, the catalyst is used in a state suspended in the reaction solution, but may be used in a fixed bed. The amount of the catalyst used is preferably 0.1% by mass or more, more preferably 0.5% by mass or more as a catalyst present in the reactor with respect to the solution present in the reactor performing liquid phase oxidation. 1% by mass or more is more preferable. Moreover, 30 mass% or less is preferable, 20 mass% or less is more preferable, and 15 mass% or less is further more preferable.

  The reaction temperature and reaction pressure are appropriately selected depending on the solvent used and the reaction raw materials. The reaction temperature is preferably 30 ° C or higher, more preferably 50 ° C or higher. Moreover, 200 degrees C or less is preferable and 150 degrees C or less is more preferable. The reaction pressure is preferably 0 MPa or more, and more preferably 2 MPa or more. Moreover, it is 10 MPa or less, Preferably it is 7 MPa or less.

EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated more concretely, this invention is not limited to an Example. In the following Examples and Comparative Examples, “part” is part by mass, and analysis of raw materials and products was performed using gas chromatography. The reaction rate of olefin, the selectivity of α, β-unsaturated aldehyde, and the selectivity of α, β-unsaturated carboxylic acid are defined as follows.
Olefin reaction rate (%) = (B / A) × 100
Selectivity of α, β-unsaturated aldehyde (%) = (C / B) × 100
Selectivity of α, β-unsaturated carboxylic acid (%) = (D / B) × 100
Here, A is the number of moles of olefin supplied, B is the number of moles of reacted olefin, C is the number of moles of α, β-unsaturated aldehyde produced, and D is the mole of α, β-unsaturated carboxylic acid produced. Is a number.

[Example 1]
(Catalyst preparation)
1.1 parts of palladium acetate was added to 30.0 parts of acetic acid and dissolved by heating at 80 ° C. 10.0 parts of a silica carrier (specific surface area 450 m ^{2 /} g) was added to this solution for evaporation. Then, it baked at 450 degreeC in the air for 3 hours. The obtained solid was added to a mixed solvent of 20 parts of a 37% by mass aqueous formaldehyde solution and 20 parts of water, heated to 70 ° C., and kept in a stirred state for 2 hours. The obtained slurry was suction filtered under a nitrogen stream to separate black powder, thereby obtaining 10.5 parts of a silica-supported palladium-containing catalyst.

(Washing)
From above the silica-supported palladium-containing catalyst separated by filtration, 100 parts of tertiary butanol was washed as a cleaning liquid, and the resulting silica-supported palladium-containing catalyst was used for the next reaction evaluation.

(Reaction evaluation)
An autoclave with a gas inlet (hereinafter referred to as a reactor) was charged with 100 parts of a 75% by weight tertiary butanol aqueous solution, and 10.5 parts of the washed catalyst (and p-methoxyphenol as a radical trapping agent with respect to the reaction solvent). 200 ppm) and the reactor was sealed.

  Next, 2.7 parts of isobutylene was introduced, stirring (rotation speed: 1000 rpm) was started, and the temperature was raised to 90 ° C. After completion of the temperature increase, nitrogen was introduced into the reactor up to an internal pressure of 2.4 MPa, and then further pressurized with compressed air to an internal pressure of 4.8 MPa to initiate the reaction. Although the internal pressure decreased as the reaction proceeded, pure oxygen was added to an internal pressure of 4.8 MPa when the internal pressure decreased by 0.1 MPa (internal pressure 4.7 MPa). A total of 1.1 MPa of pure oxygen was added. The reaction was terminated by stirring for 60 minutes in this state.

  After completion of the reaction, the liquid in the reactor was cooled to about 10 ° C. in an ice bath. A gas collection bag was attached to the gas outlet of the reactor, and the gas outlet was opened to collect all gas components. A part of the reaction solution was collected from the reactor, and the catalyst and the reaction solution were separated using a membrane filter (pore size: 0.5 μm). Each component contained in the collected reaction liquid and gas was quantified by gas chromatography, and the reaction rate or selectivity of each component was calculated as a reaction evaluation. The evaluation results are shown in Table 1.

[Example 2]
(Catalyst preparation)
The same operation as in Example 1 was performed.

(Washing)
The same operation as in Example 1 was performed except that 100 parts of a 75% by mass tertiary butanol aqueous solution was used as the cleaning liquid.

(Reaction evaluation)
The same operation as in Example 1 was performed, except that 10.5 parts of the washed catalyst was used. The added pure oxygen was 1.1 MPa in total. The evaluation results are shown in Table 1.

[Example 3]
(Catalyst preparation)
The same operation as in Example 1 was performed.

(Washing)
The same operation as in Example 1 was performed except that 80 parts of acetone was used as the cleaning liquid.

(Reaction evaluation)
The same operation as in Example 1 was performed, except that 10.5 parts of the washed catalyst was used. The added pure oxygen was 1.1 MPa in total. The evaluation results are shown in Table 1.

[Comparative Example 1]
(Catalyst preparation)
The same operation as in Example 1 was performed.

(Washing)
The same operation as in Example 1 was performed except that pure water was used as the cleaning liquid.

(Reaction evaluation)
The same operation as in Example 1 was performed, except that 10.5 parts of the washed catalyst was used. The added pure oxygen was 1.1 MPa in total. The evaluation results are shown in Table 1.

  As described above, it was found that the selectivity of methacrylic acid was increased by using the washed palladium-containing catalyst.

Claims (1)

  In the method for producing an α, β-unsaturated carboxylic acid from an olefin using a noble metal-containing catalyst in a liquid phase in the presence of molecular oxygen, the noble metal-containing catalyst is washed with a washing liquid containing at least an organic solvent, A method for producing an α, β-unsaturated carboxylic acid, wherein a reaction for producing an α, β-unsaturated carboxylic acid is carried out using the noble metal-containing catalyst after washing.