JP7329219B2 - Method for producing aldol condensate from aldehyde - Google Patents

Description

The present invention is a method for producing an aldol condensate using an aldol condensation reaction of aldehyde, comprising a step of contacting a gaseous aldehyde with at least one catalyst selected from silica, alumina and silica-alumina. Regarding the method.

Dioctyl phthalate (hereinafter abbreviated as DOP), which is used in large quantities as a plasticizer for vinyl chloride resins, is a representative of so-called phthalate plasticizers. 2-Ethylhexanol, which is a raw material for DOP, is industrially produced by hydrogenating 2-ethyl-2-hexenal, which is an aldol condensate of normal butyraldehyde. Aldol condensation of normal butyraldehyde usually uses a base catalyst such as sodium hydroxide or an anion exchange resin (Non-Patent Document 1). Each of these methods has the problem of generating wastewater with a high BOD load or the high cost of the catalyst. There is also an example of investigating the condensation reaction of aldehydes in the gas phase under the presence of a basic catalyst (Non-Patent Document 2), but this is only a study of the reaction, and the raw material conversion rate and target product selectivity are insufficient. It cannot be said that this is a reaction that can be applied to industrialization.

Although there are many examples of studies on aldol reactions in the gas phase, there are almost no examples showing examples in which ketones are used as raw materials and aldehydes are used as reaction raw materials, as in Patent Document 1. Chain aldehydes suggesting the difficulty of the gas-phase aldol condensation reaction of On the other hand, in Patent Document 2, although a chain aldehyde is studied in a fixed bed flow reaction in a liquid phase, the purpose is to produce alcohol, and the reaction results were not satisfactory.

JP-A-6-25065 Japanese Patent Publication No. 2011-517656

Industrial Organic Chemistry (K. Weissermel, H. J. Arpe Wiley VCH) Topics in Catalysis (2017), 60(19-20), 1522-1536.

An object of the present invention is to solve the above-mentioned conventional technical problems, and to provide a method for efficiently producing an aldol condensate from an aldehyde.

As a result of intensive studies, the present inventors have found that an aldol condensation product is efficiently produced from an aldehyde by performing an aldol condensation reaction in a gas phase using at least one selected from silica, alumina and silica-alumina as a catalyst. I found that it does, and came to complete the present invention.

The present invention includes the following.
[1] A method for producing an aldol condensate using an aldol condensation reaction of an aldehyde,
A production method comprising a step of contacting a gaseous aldehyde with at least one catalyst selected from silica, alumina and silica-alumina.
[2] The production method according to [1], wherein the catalyst has a BET specific surface area of 220 to 380 m ² g ^-1 .
[3] The production method according to [1], wherein the catalyst has a BET specific surface area of 250 to 350 m ² g ^-1 .
[4] The production method according to any one of [1] to [3], wherein the catalyst does not contain any component other than oxygen, aluminum or silicon.
[5] The production method according to any one of [1] to [3], wherein the catalyst is silica.
[6] The production method according to any one of [1] to [5], wherein the aldehyde is a linear aldehyde having 2 to 6 carbon atoms.
[7] The production method according to any one of [1] to [5], wherein the aldehyde is n-butyraldehyde.
[8] The method according to any one of [1] to [7], wherein the aldol condensate is 2-ethyl-2-hexenal.

According to the production method of the present invention, an aldol condensate can be efficiently produced from an aldehyde.

FIG. 1 is a schematic diagram of a fixed-bed atmospheric gas-phase flow reactor used in Examples.

The present invention is a method for producing an aldol condensate using an aldol condensation reaction of aldehyde, comprising a step of contacting a gaseous aldehyde with at least one catalyst selected from silica, alumina and silica-alumina. The method.

[About the catalyst]
(catalyst component)
As the catalyst in the present invention, silica (SiO ₂ ) simple substance, alumina (Al ₂ O ₃ ) simple substance, silica-alumina composite, and mixture thereof can be used.

The catalyst used in the present invention can be loaded with other metals, or can be composited with other oxides, but in the present invention, it does not contain other components (components other than oxygen, aluminum, and silicon). is preferred. Among silica, alumina, and silica-alumina composites, silica is more preferable. The silica-alumina composite can contain silica and alumina in any ratio, but it is preferable that the silica component is large.
Here, "not containing other components" means not intentionally containing other components, and unavoidable inclusion of other components is acceptable.

Although the specific surface area (BET specific surface area) of the catalyst used in the present invention is not particularly limited, it is preferably 220 to 380 m ² g ⁻¹ and 250 to 350 m 2 g −1 from the viewpoint of yield of aldol condensate. More preferably, it is ² g ^-1 .

(catalyst precursor)
The catalyst used in the present invention may be a commercially available product, a product obtained by calcining a commercially available product, a hydroxide of aluminum or silicon, or a product obtained by thermally decomposing an organoaluminum compound or an organosilicon compound, etc., and is particularly limited. not a thing
When other components are contained, they can be supported using conventional techniques such as impregnation, but as described above, silica, alumina, and silica-alumina catalysts containing no other components are preferred.

[Method for producing aldol condensate]
(material)
The aldehyde used as a raw material is not particularly limited, but an aldehyde that is in a gaseous state within the reaction temperature range (for example, 200° C. to 400° C.) is preferred. The aldehyde may be either a straight-chain aldehyde or a branched aldehyde, but from the viewpoint of reaction yield, a straight-chain aldehyde is preferred, and a straight-chain aldehyde having 2 to 6 carbon atoms is more preferred. Specific examples include acetaldehyde, propionaldehyde, butyraldehyde, valeraldehyde, capronaldehyde and the like.

A single aldehyde may be used as the raw material aldehyde, or a plurality of aldehydes may be used. However, when the target aldol condensate is one, it is preferable to use a single aldehyde.

(Restrictions on raw materials)
The water content in the raw material aldehyde is not particularly limited, but is preferably in the range of 0 to 10% by weight. If the water content in the aldehyde exceeds 10% by weight, the reaction efficiency may decrease.

(raw material speed)
The amount of aldehyde to be supplied as a raw material is not particularly limited as long as it is sufficient to supply an aldol condensate, but for example, 0.1 to 3.0 spaces per unit time and unit catalyst volume. velocity (LHSV: Liquid Hourly Space Velocity unit h ⁻¹ ).

(product)
Moreover, the aldol condensate obtained from these raw materials is a compound obtained by the aldol condensation and dimerization of the aldehyde. The aldol condensate varies depending on the type of aldehyde used as a raw material. -Butyl-2-octenal and the like.

(Reactor)
The reactor used in the production of the aldol condensate of the present invention is not particularly limited as long as it can bring the gaseous aldehyde into contact with the catalyst. For example, an active catalyst layer may be formed in the gas phase flow reactor by placing a predetermined amount of catalyst in the gas phase flow reactor and activating it by a known method. It is possible to produce an aldol condensate by supplying the starting aldehyde here.

(reaction temperature)
The reaction temperature in the method for producing an aldol condensate of the present invention is preferably in the temperature range of 200° C. to 400° C., that is, the temperature at which the raw material aldehyde exists in a gaseous state. A temperature of 200° C. or higher is preferable for allowing the reaction to proceed sufficiently, and a temperature of 400° C. or less is preferable for maintaining good product selectivity. A more preferable temperature range is from 220°C to 300°C.

(reaction pressure)
Although the pressure of the aldol condensation reaction of the present invention is not particularly limited, it is preferably carried out under atmospheric pressure.

(carrier gas)
In the gas phase aldol condensation reaction of the present invention, a carrier gas can flow together with the raw materials. The type of carrier gas is preferably non-oxidizing gas. Hydrogen gas or a hydrogen-containing inert gas is more preferred, and hydrogen gas is even more preferred. Here, the inert gas means a gas that does not affect the reaction, and examples thereof include nitrogen gas and argon gas.
The flow rate of the carrier gas is not particularly limited, but if the residence time is long, a high-order aldol reaction may proceed. It is preferably about 0.01 to 100/min.
In addition, it is preferable to pre-treat the catalyst before charging the raw material. The pretreatment is performed by using the same carrier gas as the reaction and maintaining the same temperature as the reaction for 10 minutes to 10 hours, for example.

EXAMPLES The present invention will be further described with reference to examples below. In addition, the present invention is not limited to the examples.

(Reactor)
FIG. 1 shows the fixed-bed normal-pressure gas-phase flow reactor used in Examples and Comparative Examples. The inner diameter from the top of the reactor to the catalyst layer is about 17 mm, and the total length of the reactor is 300 mm. .

(catalyst)
The catalysts are silica (CARiACT Q-3, Q-6, Q-10, Q-15 manufactured by Fuji Silysia Chemical Co., Ltd.), alumina (catalyst society reference catalyst JRC-ALO-7), silica-alumina (N631HN manufactured by JGC Chemical Co., Ltd. ), ZrO ₂ (RSC-100 manufactured by Daiichi Kigenso Kagaku Kogyo Co., Ltd.), 3 wt% Li ₂ O/ZrO ₂ (catalyst prepared by impregnating and supporting lithium hydroxide in RSC-100 by a known method) was used.

(material)
As the starting material, n-butyraldehyde, a special grade reagent (manufactured by Wako Pure Chemical Industries, Ltd., special grade reagent) was used as it was without purification.

(Pretreatment of catalyst layer)
Hydrogen gas was passed through the reaction tube at a supply rate of 20 ml/min in a reaction apparatus in which a predetermined amount of catalyst shown in Tables 1 and 2 was set. After that, the reaction vessel was heated to the reaction temperature in an electric furnace, and pretreatment was performed by holding at that temperature for 1 hour.

(Gas phase aldol condensation reaction)
A raw material was supplied from the upper part of the reaction tube together with a carrier gas to the reactor in which the pretreated catalyst was set. Butyraldehyde as a raw material and hydrogen as a carrier gas were each supplied to the reactor at a predetermined flow rate. Aldehyde was moved downward by running along the wall of the reaction tube, heated by an electric furnace installed outside the reaction tube, evaporated inside the reaction tube, and brought into contact with the catalyst at the catalyst layer. The reactant reacted in the catalyst layer was cooled and liquefied with an acetone dry ice trap at the bottom of the reaction tube, and then recovered.
The product mixture was collected every hour from the start of supplying the raw materials, and the average value of the analysis results from the 0th hour to the 5th hour of the reaction time was taken as the reaction result.
The reaction product was analyzed using a capillary column (TC-WAX 60m, manufactured by GL Sciences) and a gas chromatograph (GC-14B, manufactured by Shimadzu Corporation) equipped with an FID detector. Analysis by gas chromatography is carried out by determining the conversion of butyraldehyde and the selectivity of 2-ethyl-2-hexenal (hereinafter abbreviated as 2E2H) after correcting the calibration curve. Selectivity (mol %) was determined.

Example 1
Gas-phase aldol condensation reaction of butyraldehyde was carried out using silica (CARiACT Q-10, BET specific surface area: 295 m ² /g, manufactured by Fuji Silysia Chemical). The reaction temperature was 200° C., the amount of catalyst was 0.5 g, butyraldehyde as a reaction raw material was 1.3 g/h, and hydrogen as a carrier gas was supplied to the reactor at a flow rate of 5 cm ³ /min. Table 1 shows the results.

Example 2
Example 1 was followed except that the amount of the catalyst used was changed to 2.0 g. Table 1 shows the results.

Example 3
Example 1 was followed except that the amount of the catalyst used was changed to 4.0 g. Table 1 shows the results.

Example 4
Example 1 was followed except that γ-alumina (Catalysis Society of Japan reference catalyst JRC-ALO-7 BET specific surface area 180 m ² /g) was used as a catalyst. Table 1 shows the results.

Example 5
Example 1 was followed except that another type of silica (CARiACT Q-3, BET specific surface area: 705 m ² /g, manufactured by Fuji Silysia Chemical Ltd.) was used as the catalyst. Table 1 shows the results.

Example 6
Example 1 was followed except that another type of silica (CARiACT Q-6, BET specific surface area: 401 m ² /g, manufactured by Fuji Silysia Chemical Ltd.) was used as the catalyst. Table 1 shows the results.

Example 7
Example 1 was followed except that another type of silica (CARiACT Q-15, BET specific surface area: 226 m ² /g, manufactured by Fuji Silysia Chemical Ltd.) was used as the catalyst. Table 1 shows the results. The conversion was not high, but the selectivity was high, which was found to contribute to the aldol condensation.

Example 8
Example 1 was followed except that silica-alumina (manufactured by Nikki Chemicals, N631HN, BET specific surface area: 397 m ² /g) was used as a catalyst. Table 1 shows the results.

Comparative example 1
Example 1 was followed except that zirconia (manufactured by Daiichi Kigenso Kagaku Kogyo Co., Ltd., RSC-100, BET specific surface area: 106 m ² /g) was used as a catalyst. Table 1 shows the results. The selectivity was low compared to silica and alumina.

Comparative example 2
Example 1 was followed except that lithium oxide-zirconia (a catalyst prepared by impregnating and supporting lithium hydroxide on zirconia RSC-100 by a known method) was used as a catalyst. Table 1 shows the results.

Example 9
Example 1 was followed except that the reaction temperature was 180°C. Table 2 shows the results.

Example 10
Example 1 was followed except that the reaction temperature was 220°C. Table 2 shows the results.

Example 11
Example 1 was followed except that the reaction temperature was 240°C. Table 2 shows the results.

Example 12
Example 1 was followed except that the reaction temperature was 260°C. Table 2 shows the results.

[Description of symbols]
1. Raw material (raw material inlet)
2. Carrier gas (carrier gas inlet)
3. thermocouple4. Thermocouple cover (there is a thermocouple inlet on the top)
5. reaction tube6. electric furnace7. catalyst layer8. glass wool9. Gas vent (product recovery)

Claims (8)

A method for producing an aldol condensate using an aldol condensation reaction of an aldehyde,
A production method comprising a step of contacting a gaseous aldehyde with a silica catalyst in the presence of hydrogen , and using only a linear aldehyde as a raw material . The process according to claim 1, wherein said catalyst has a BET specific surface area of 220 to 380 m ² g ^-1 . The production method according to claim 1, wherein the catalyst has a BET specific surface area of 250 to 350 m ² g ^-1 . 4. The manufacturing method according to any one of claims 1 to 3, wherein the catalyst does not contain components other than oxygen and silicon . 5. The production method according to any one of claims 1 to 4, wherein the aldehyde is a linear aldehyde having 2 to 6 carbon atoms. 5. The production method according to any one of claims 1 to 4, wherein the aldehyde is normal butyraldehyde. The production method according to any one of claims 1 to 6, wherein the aldol condensate is 2-ethyl-2-hexenal. The production method according to claim 1, wherein the step of contacting the aldehyde with the catalyst is carried out at 220°C or higher and 260°C or lower.