JP2016204329A - Method for producing diene compound - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for efficiently producing corresponding diene from 1,3-diol type raw material reduced in the generation of by-products (impurities) in which reuse as raw material.SOLUTION: Provided is a method of successively performing the first dehydration step where, to 1,3-diol type raw material, using the oxide of rare earth elements as a catalyst, an unsaturated alcohol compound is produced; and a second dehydration step where the dehydration reaction of the unsaturated alcohol is simultaneously performed in the presence of at least one kind of dehydration catalyst selected from metal phosphate, metal condensed phosphate, metal sulfate, metal hydrochloride, metal oxide and inorganic acid to produce a diene compound represented by formula (3): (R1 to R6 respectively independently denote H, a 1 to 5C alkyl group or a 6 to 12C aryl group).SELECTED DRAWING: None

Description

  The present invention relates to an efficient method for producing a diene compound by a dehydration reaction of a diol, particularly a 1,3-diene compound typified by butadiene. More specifically, the present invention relates to a method for producing a diene compound in which a diol dehydration reaction is performed in two stages in the presence of a specific catalyst.

  Diene monomers such as 1,3-butadiene and isoprene have high industrial value as resin raw materials such as synthetic rubbers and plastics, and their efficient production methods are required.

  Conventionally, the diene monomer is obtained as a fraction by distilling and separating a thermal decomposition product of a naphtha pyrolysis furnace (cracker). However, in this method of fraction purification, even when it is desired to selectively obtain a diene monomer, the profitability including other monomer fractions (ethylene, propylene, etc.) must be taken into consideration, and industrial production. The degree of freedom was low.

  Therefore, a method for producing a diene monomer using a low molecular weight compound such as ethylene, which is easily available, as a raw material has been studied. For example, Patent Document 1 and Patent Document 2 disclose a production method in which a lower olefin is dimerized and then subjected to oxidative dehydrogenation in the presence of a Mo-Bi-X catalyst. However, in this method, there is a risk of explosion due to the use of oxygen, and incidental equipment for separating unreacted butene is required, resulting in an increase in the size of the entire equipment.

  As another method, a production method by dehydration reaction of 1,3-diol such as 1,3-butanediol can be mentioned. Such a method for producing 1,3-diol is disclosed in Patent Document 3, for example.

  I. G. In the method disclosed by Farbenindustrie (Patent Document 4), it is reported that butadiene can be obtained in a yield of 85% or more when a sodium phosphate catalyst is used with respect to 1,3-butanediol. However, as a result of actual studies by the present inventors, it has been found that butadiene is obtained and a considerable amount of impurities such as propylene and butyraldehyde are produced.

  Recently, a method for obtaining butadiene from 1,3-butanediol by an enzymatic reaction has been disclosed (Patent Document 5). However, this method has problems that it is difficult to control the production amount and that it is necessary to add a consumer other than the substrate for the enzyme to work.

JP 2010-120933 A JP 2011-006395 A JP-A-6-329664 German Patent No. 610371 US Patent Application Publication No. 2013/0187753

  The object of the present invention is to solve the conventional technical problems, produce less by-products (impurities) that cannot be reused as raw materials, and efficiently produce the corresponding dienes from 1,3-diol type raw materials. Is to provide a method.

As a result of intensive studies, the inventors of the present invention have obtained from the diol represented by the general formula (1) to the general formula (2) -1 and the diol represented by the general formula (1) by using a rare earth element oxide as a catalyst. The first dehydration step for producing the unsaturated alcohol represented by the general formula (2) -2 and the dehydration reaction of the unsaturated alcohol are simultaneously performed in the presence of the dehydration catalyst to produce the diene compound represented by the general formula (3). By carrying out the second dehydration step in order, it was found that the corresponding diene can be produced with high selectivity, and the present invention has been completed.

（式中、Ｒ^１〜Ｒ^６はそれぞれ独立に水素原子、炭素数１〜５のアルキル基、又は炭素数６〜１２のアリール基を示す。）

（式中、Ｒ^１〜Ｒ^６は一般式（１）と同一のものを示す。）

（式中、Ｒ^１〜Ｒ^６は一般式（１）と同一のものを示す。）
脱水触媒の存在下、前記一般式（２）−１及び一般式（２）−２で示される不飽和アルコールの脱水反応を同時に行い、一般式（３）で示されるジエン化合物を製造する第二脱水工程

（式中、Ｒ^１〜Ｒ^６は一般式（１）と同一のものを示す。）
［２］
第一脱水工程で用いる前記希土類元素がＬａ、Ｃｅ、Ｔｂ、Ｄｙ、Ｈｏ、Ｙ、Ｅｒ、Ｔｍ、Ｙｂ、Ｌｕ、及びＳｃからなる群より選ばれる少なくとも一種である［１］に記載のジエン化合物の製造方法。
［３］
第一脱水工程で用いる前記希土類元素がＣｅである［１］に記載のジエン化合物の製造方法。
［４］
第一脱水工程で用いる前記希土類元素の酸化物が酸化セリウム（ＣｅＯ_２）である［１］に記載のジエン化合物の製造方法。
［５］
第二脱水工程の前記脱水触媒が金属リン酸塩、金属縮合リン酸塩、金属硫酸塩、金属塩酸塩、金属酸化物、及び無機酸からなる群より選ばれる少なくとも一種である［１］〜［４］のいずれかに記載のジエン化合物の製造方法。
［６］
前記金属リン酸塩、金属縮合リン酸塩、金属硫酸塩、又は金属塩酸塩の金属がアルカリ金属、アルカリ土類金属、Ｔｉ、Ｚｒ、Ｈｆ、Ｎｂ、Ｔａ、Ａｌ、Ｂ、及びＳｎからなる群より選ばれる少なくとも一種である［５］に記載のジエン化合物の製造方法。
［７］
前記金属酸化物がシリカ、アルミナ、マグネシア、チタニア、ジルコニア、ニオビア、シリカアルミナ、シリカマグネシア、及びゼオライトからなる群より選ばれる少なくとも一種である［５］に記載のジエン化合物の製造方法。
［８］
第二脱水工程の前記脱水触媒が担体に担持された触媒である［５］〜［７］のいずれかに記載のジエン化合物の製造方法。
［９］
一般式（１）のＲ^１〜Ｒ^６がすべて水素原子である［１］〜［８］のいずれかに記載のジエン化合物の製造方法。
［１０］
第一脱水工程での副生物である３−ブテン−１−オールの選択率が５．０％以下である［９］に記載のジエン化合物の製造方法。 That is, the present invention relates to the following [1] to [10].
[1]
The manufacturing method of the diene compound characterized by including the following 2 processes at least.
First dehydration step of producing unsaturated alcohol represented by general formula (2) -1 and general formula (2) -2 from diol represented by general formula (1) using rare earth element oxide as catalyst

(In the ^formula, each of R 1 to R ⁶ independently represent a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or an aryl group having 6 to 12 carbon atoms.)

(In the formula, R ^{1 to} R ⁶ are the same as those in the general formula (1).)

(In the formula, R ^{1 to} R ⁶ are the same as those in the general formula (1).)
A second process for producing a diene compound represented by the general formula (3) by simultaneously carrying out a dehydration reaction of the unsaturated alcohol represented by the general formula (2) -1 and the general formula (2) -2 in the presence of a dehydration catalyst. Dehydration process

(In the formula, R ^{1 to} R ⁶ are the same as those in the general formula (1).)
[2]
The diene compound according to [1], wherein the rare earth element used in the first dehydration step is at least one selected from the group consisting of La, Ce, Tb, Dy, Ho, Y, Er, Tm, Yb, Lu, and Sc. Manufacturing method.
[3]
The method for producing a diene compound according to [1], wherein the rare earth element used in the first dehydration step is Ce.
[4]
The method for producing a diene compound according to [1], wherein the rare earth element oxide used in the first dehydration step is cerium oxide (CeO ₂ ).
[5]
The dehydration catalyst in the second dehydration step is at least one selected from the group consisting of metal phosphates, metal condensed phosphates, metal sulfates, metal hydrochlorides, metal oxides, and inorganic acids [1] to [1] 4] The manufacturing method of the diene compound in any one of.
[6]
The metal phosphate, metal condensed phosphate, metal sulfate, or metal hydrochloride metal is made of alkali metal, alkaline earth metal, Ti, Zr, Hf, Nb, Ta, Al, B, and Sn The method for producing a diene compound according to [5], which is at least one selected from the group consisting of:
[7]
The method for producing a diene compound according to [5], wherein the metal oxide is at least one selected from the group consisting of silica, alumina, magnesia, titania, zirconia, niobia, silica alumina, silica magnesia, and zeolite.
[8]
The method for producing a diene compound according to any one of [5] to [7], wherein the dehydration catalyst in the second dehydration step is a catalyst supported on a carrier.
[9]
Method for producing a diene compound according to any one of ^R 1 to R ⁶ in the general formula (1) are all hydrogen atoms [1] to [8].
[10]
The method for producing a diene compound according to [9], wherein the selectivity for 3-buten-1-ol as a by-product in the first dehydration step is 5.0% or less.

  According to the present invention, a 1,3-diene compound can be produced with high efficiency.

（式中、Ｒ^１〜Ｒ^６はそれぞれ独立に水素原子、炭素数１〜５のアルキル基、又は炭素数６〜１２のアリール基を示す。）
脱水触媒の存在下、不飽和アルコールの脱水反応によりジエン化合物を製造する第二脱水工程（式（５））

（式中、Ｒ^１〜Ｒ^６は式（４）と同一のものを示す。） The present invention includes at least the following two steps.
First dehydration step for producing unsaturated alcohol from diol using rare earth oxide as catalyst (formula (4))

(In the ^formula, each of R 1 to R ⁶ independently represent a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or an aryl group having 6 to 12 carbon atoms.)
Second dehydration step for producing diene compound by dehydration reaction of unsaturated alcohol in the presence of dehydration catalyst (Formula (5))

(In the formula, R ^{1 to} R ⁶ are the same as those in formula (4).)

<First dehydration process>
The rare earth element oxide used as a catalyst in the first dehydration step is not particularly limited. As the rare earth element, La, Ce, Tb, Dy, Ho, Y, Er, Tm, Yb, Lu, and Sc are suitable, and Ce is preferable. As the rare earth element oxide, cerium oxide (CeO ₂ ) is particularly preferably used. These may be used alone or in combination of two or more. The oxide of the rare earth element as the catalyst may be a composite of the oxide and an oxide of a metal other than the rare earth (for example, Al, Mg, Co, Ni, Fe, etc.).

When the rare earth element oxide is used in the first dehydration step, the selectivity of the compounds of the general formulas (2) -1 and (2) -2 is increased. Furthermore, the selectivity of δ-γ unsaturated alcohol which is one of by-products can be kept low. In order to reduce the generation of by-products in the second dehydration step, the selectivity of the δ-γ unsaturated alcohol in the first dehydration step is preferably 5.0% or less, and 1.0% or less. More preferably. When R ^{1 to} R ^{6 in} the general formula (1) are all hydrogen atoms, the reaction of the formula (4) mainly produces 3-buten-2-ol and crotyl alcohol (2-buten-1-ol). (See Japanese Patent No. 3800205). The δ-γ unsaturated alcohol is 3-buten-1-ol. When 3-buten-1-ol is further dehydrated, n-butyraldehyde, formaldehyde, propylene, and the like are by-produced in addition to the desired 1,3-butadiene, which makes purification difficult and selectivity as a whole reaction. Also decreases. In order to reduce the generation of by-products in the second dehydration step, the selectivity for 3-buten-1-ol in the first dehydration step is preferably 5.0% or less, and 1.0% or less. More preferably it is. If the selectivity of 3-buten-1-ol is 5.0% or less, a decrease in the selectivity of 1,3-butadiene in the second dehydration step can be suppressed.

  Commercially available products can be used as they are for the rare earth element oxide used as the catalyst in the first dehydration step of the present invention. Instead, a rare earth element precursor may be molded using a binder, if necessary, and then baked at high temperature to oxidize, a precursor solution impregnated and baked to oxidize, a neutralization reaction, etc. The catalyst can also be prepared by a method of firing and oxidizing after forming a precipitate. Rare earth element oxides can be used after being formed into pellets, tablets, disks, or the like, if necessary. A rare earth element oxide may be supported on a known carrier. As the cerium oxide, for example, a catalyst disclosed in Japanese Patent No. 3800205 or a commercially available product can be used.

  Examples of the carrier include silica, alumina, titania, zirconia, silica alumina, zeolite, activated carbon, graphite and the like, but are not particularly limited.

  The reactor used in the first dehydration step is preferably a continuous gas phase flow reactor. The catalyst may be either a fixed bed or a fluidized bed, and a fixed bed is desirable from the standpoint of maintenance.

  As an example of the reaction apparatus, a straight pipe type reactor having a diol vaporizer as a reaction raw material at the upper part can be mentioned. The reactor is filled with a catalyst, and a raw material stream generated by evaporating the raw diol in a vaporizer is introduced into the reactor. The reaction product is cooled in a heat exchanger at the bottom of the reactor, and the target unsaturated alcohol and unreacted raw material are recovered. In order to suppress side reactions, the vaporized raw material diol may be diluted with an inert gas such as nitrogen or water vapor and used for the reaction.

  The reaction temperature in the first dehydration step is suitably in the range of 100 to 400 ° C. If it is 100 ° C. or higher, the reaction proceeds promptly. On the other hand, when the temperature is 400 ° C. or less, the influence of the selectivity reduction due to the side reaction is reduced.

  The amount of diol introduced per catalyst packing volume can be in the range of 0.1 to 20 kg / (h · L-cat), preferably 0.2 to 15 kg / (h · L-cat). Preferably, it is 0.5 to 10 kg / (h · L-cat). When the introduction amount is small, a sufficient production amount may not be obtained. In many cases, unreacted raw materials increase, and extra labor is required for separation and purification, and side reactions from the raw materials are likely to proceed.

The space velocity [SV] with respect to the catalyst filling volume of the raw material stream containing the diol raw material can be in the range of 100 to 40,000 h ⁻¹ , and 500 to 10000 h ⁻¹ is particularly preferable. When the space velocity is too low, by-products may be generated from the 1,3-diol raw material and the produced unsaturated alcohol due to an increase in contact time. If the space velocity is too high, the conversion rate decreases, the amount of unreacted raw material increases, and excessive cost may be required for the separation.

  The reactant containing the unsaturated alcohol obtained in the first dehydration step can be used as it is in the next second dehydration step, but after further purification and increasing the content of unsaturated alcohol, It can also be used for these processes. As a purification method, distillation, recrystallization, and other general purification methods can be applied. By removing the by-products at this time, it is possible to obtain a diene having a lower impurity content in the subsequent reaction.

<Second dehydration process>
The dehydration catalyst used in the second dehydration step is not limited as long as it exhibits the dehydration ability of the unsaturated alcohol represented by the general formulas (2) -1 and (2) -2. For example, a metal phosphate, a metal condensed phosphate, a metal sulfate, a metal hydrochloride, a metal oxide, an inorganic acid, etc. are mentioned. These catalysts may be used alone or supported on a carrier. For example, in an embodiment in which the shape retention of the dehydration catalyst is low, the catalyst supported on the carrier can be advantageously used as the dehydration catalyst.

  Examples of the carrier include silica, alumina, titania, zirconia, silica alumina, zeolite, activated carbon, graphite and the like, but are not particularly limited.

  Examples of the metal phosphate, metal condensed phosphate, metal sulfate, and metal hydrochloride include alkali metal, alkaline earth metal, Ti, Zr, Hf, Nb, Ta, Al, B, and Sn. It is done. Among these metals, Na, Mg, and Al are preferable.

  Examples of the metal oxide include silica, alumina, magnesia, titania, zirconia, niobia, silica alumina, silica magnesia, and zeolite.

  Examples of the inorganic acid include sulfuric acid, nitric acid, hydrochloric acid, phosphoric acid and the like.

  As the catalyst used in the second dehydration step, magnesium sulfate, aluminum phosphate, and sodium polyphosphate are more preferable because the target diene selectivity is high.

  As the reactor used in the second dehydration step, a continuous gas-phase flow reactor is suitable as in the first dehydration step. The catalyst may be either a fixed bed or a fluidized bed, and a fixed bed is desirable from the standpoint of maintenance.

  As an example of the reaction apparatus, a straight pipe type reactor having a vaporizer of unsaturated alcohol as a reaction raw material at the upper part can be mentioned. The reactor is filled with a catalyst, and a raw material stream generated by evaporating the raw material unsaturated alcohol with a vaporizer is introduced into the reactor. The reaction product is cooled in a heat exchanger at the bottom of the reactor, and the target diene compound and unreacted raw material are recovered. In order to suppress side reactions, the vaporized raw material unsaturated alcohol may be diluted with an inert gas such as nitrogen or water vapor and used for the reaction.

  The reaction temperature in the second dehydration step is suitably in the range of 200 to 500 ° C. If it is 200 ° C. or higher, the reaction proceeds promptly. When the temperature is 500 ° C. or less, the influence of the selectivity reduction due to the side reaction is reduced.

  The amount of unsaturated alcohol introduced per catalyst filling volume can be in the range of 0.05 to 20 kg / (h · L-cat), preferably 0.1 to 10 kg / (h · L-cat). Most preferably, it is 0.2 to 5 kg / (h · L-cat). When the introduction amount is small, a sufficient production amount may not be obtained. In many cases, unreacted raw materials increase, and extra labor is required for separation and purification, and side reactions from the raw materials are likely to proceed.

The space velocity [SV] with respect to the catalyst filling volume of the raw material stream containing the unsaturated alcohol can be in the range of 100 to 40000 h ⁻¹ , and 500 to 10000 h ⁻¹ is particularly preferable. When the space velocity is too low, by-products may be generated from the unsaturated alcohol raw material and the produced diene compound due to an increase in contact time. If the space velocity is too high, the conversion rate decreases, the amount of unreacted raw material increases, and excessive cost may be required for the separation.

  The diene compound obtained from the second dehydration step can be further refined by a distillation column to obtain a diene compound having an increased purity.

  The method described above is one of the embodiments of the present invention, and in the light of its essence, other embodiments can be taken. However, they are all included in the scope of the present invention.

  Examples The effects of the present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

[Preparation of cerium oxide catalyst A]
Commercially available cerium oxide (special grade, manufactured by Wako Pure Chemical Industries, Ltd.) was placed in a vinyl chloride resin cell (10 mmφ) and pressed at a pressure of 15 MPa for 1 minute. The obtained disk-shaped cell (thickness 3 mm) was crushed, and 6.5 to 12 mm mesh was collected. The crushed material was calcined in air at 500 ° C. for 3 hours in a muffle furnace (ADVANTEC KM-280) to obtain a cerium oxide catalyst A.

[Preparation of magnesium sulfate-supported silica catalyst B]
An aqueous solution containing 0.4 g of magnesium sulfate anhydride (manufactured by Wako Pure Chemical Industries, Ltd.) is impregnated and supported on 20 g of Carrieract Q-15 (registered trademark, manufactured by Fuji Silysia Chemical Co., Ltd.) as a silica carrier. After removing a portion of the water, it was air-dried in an oven at 80 ° C. for 12 hours. Thereafter, the mixture was heated and calcined in a muffle furnace (KM-280 manufactured by ADVANTEC) in the air at 400 ° C. to 500 ° C. for a total of 5 hours to obtain a magnesium sulfate-supported silica catalyst B.

[Preparation of Aluminum Phosphate Catalyst C]
Aluminum phosphate (manufactured by Wako Pure Chemical Industries, Ltd.) was placed in a vinyl chloride resin cell (30 mmφ) and pressed at a pressure of 10 MPa for 1 minute. The obtained disk-shaped cell (thickness 3 mm) was crushed, and 6.5 to 12 mm mesh was collected. The crushed material was calcined at 600 ° C. for 5 hours in air in a muffle furnace (KM-280 manufactured by ADVANTEC) to obtain an aluminum phosphate catalyst C.

[Preparation of graphite-supported sodium polyphosphate catalyst D]
8.8 g of butylamine phosphate (prepared from 85% phosphoric acid and butylamine) was dissolved in 40 g of water, and 100 g of anhydrous sodium phosphate and 20 g of graphite powder (manufactured by Wako Pure Chemical Industries, Ltd.) were added while stirring. The mixture was evaporated to dryness with stirring to obtain a powder, and then air-dried in an oven at 80 ° C. for 12 hours. It put into the cell (30 mmphi) made from a vinyl chloride resin, and pressed it for 15 minutes with the pressure of 15 MPa. The obtained disk-shaped cell (thickness 3 mm) was crushed, and 6.5 to 12 mm mesh was collected. The crushed material was calcined at 300 ° C. for 2 hours in air in a muffle furnace (KM-280 manufactured by ADVANTEC) to obtain a graphite-supported sodium polyphosphate catalyst D.

[Reactor]
For the first dehydration step and the second dehydration step of the following examples, and the dehydration reactions of the comparative example and the reference example, a fixed-bed atmospheric pressure gas flow reactor was used. The reaction tube (made of stainless steel) has an inner diameter of 16 mm and a total length of 300 mm. The vaporizer for evaporating the raw material and the diluent (nitrogen gas) inlet are connected to the upper part, and the lower part is a cooler and a gas-liquid separator. Was installed. The gas and liquid produced by the reaction were separately collected and quantified by gas chromatography.

When 1,3-butanediol was used as the diol, the following formula was used to calculate the conversion rate and selectivity in the first dehydration step for producing the unsaturated alcohol.

The following formula was used for calculation of the conversion rate and selectivity in the second dehydration step for producing 1,3-butadiene from unsaturated alcohol. “Unsaturated alcohol introduction amount” and “unsaturated alcohol consumption amount” are the total amount of 3-buten-2-ol, crotyl alcohol, and 3-buten-1-ol.

In calculating the by-product selectivity, the following formula was used in consideration of the difference in carbon number. “4” in the denominator means the carbon number of 1,3-butanediol, and “the number of carbon atoms in one molecule” means the carbon number of the by-product to be calculated.

Example 1
[First dehydration process]
Using cerium oxide catalyst A, dehydration reaction was carried out using 1,3-butanediol as a substrate and nitrogen gas as a diluent. The amount of 1,3-butanediol introduced was 6.32 g / mL of catalyst, the amount of nitrogen gas for dilution was 6.4 L / mL of catalyst, the vaporizer temperature was 260 ° C., and the temperature in the reactor was 325 ° C. (SV = 8000 h ⁻¹ ). The reaction results 2 hours after the start of the reaction were as follows. The gas phase contained almost no product.
1,3-butanediol conversion: 41.8%
3-Buten-2-ol selectivity: 58.0%
Crotyl alcohol selectivity: 38.3%
3-Buten-1-ol selectivity: 0.1%

[Distillation process]
Distillation operation was performed on 2250 g of the reaction liquid (condensate) obtained in the first dehydration step using an Oldershaw type distillation apparatus. Using McMahon packing as a filler, operation was performed under the conditions of 10 theoretical plates, reflux ratio R / R = 1, pressure 50 kPa, and 1285 g of unsaturated alcohol aqueous solution (3-buten-2-ol concentration 48.0% by mass). , Crotyl alcohol concentration 32.0 mass%, 3-buten-1-ol concentration 0.0 mass%, water concentration 20.2 mass%) and unreacted 1,3-butanediol 898 g (1,3- Butanediol concentration 97.0 mass%, water concentration 0.2 mass%) was recovered.

[Second dehydration process]
A magnesium sulfate-supported silica catalyst B was used, and an unsaturated alcohol aqueous solution obtained by the above procedure was used as a raw material, and a dehydration reaction was performed using nitrogen gas and water vapor as a diluent. The amount of unsaturated alcohol (total) introduced is 0.32 g / mL of catalyst, the amount of steam (gas) introduced is 0.30 L / mL of catalyst, and the amount of nitrogen gas introduced is 0.60 L / mL of catalyst. The reactor temperature was set to 120 ° C., and the reactor internal temperature was set to 350 ° C. (SV = 1000 h ⁻¹ ). The average reaction results from 7.5 hours after the start of the reaction were as follows.
Unsaturated alcohol conversion: 99.8%
1,3-butadiene selectivity: 95.0%

The main by-products were as follows. At this time, 1,3-butadiene total selectivity from 1,3-butanediol combined with the first dehydration step and the second dehydration step was 91.5%.
Propylene selectivity: 0.9%
Butene selectivity: 0.5%
n-Butyraldehyde selectivity: 0.3%

(Example 2)
After the first dehydration step of Example 1, an unsaturated alcohol aqueous solution after distillation (hereinafter referred to as “unsaturated alcohol aqueous solution of Example 1”) obtained by distillation purification is used as a raw material, and an aluminum phosphate catalyst as a catalyst. Using C, the dehydration reaction was performed in the same manner as in the second dehydration step of Example 1. The amount of unsaturated alcohol (total) introduced is 0.32 g / mL of catalyst, the amount of steam (gas) introduced is 0.30 L / mL of catalyst, and the amount of nitrogen gas introduced is 0.60 L / mL of catalyst. The reactor temperature was set to 120 ° C., and the reactor internal temperature was set to 350 ° C. (SV = 1000 h ⁻¹ ). The average reaction results from the start of the reaction to 4 hours later were as follows.
Unsaturated alcohol conversion: 99.7%
1,3-butadiene selectivity: 89.7%

The main by-products were as follows. At this time, the 1,3-butadiene total selectivity from 1,3-butanediol combined with the first dehydration step and the second dehydration step was 86.4%.
Propylene selectivity: 0.1%
Butene selectivity: 1.0%
n-Butyraldehyde selectivity: 0.4%

Example 3
A dehydration reaction was carried out in the same manner as in the second dehydration step of Example 1, using the unsaturated alcohol aqueous solution of Example 1 as a raw material and using graphite-supported sodium polyphosphate catalyst D as a catalyst. The amount of unsaturated alcohol (total) introduced is 0.31 g / mL of catalyst, the amount of steam (gas) introduced is 0.30 L / mL of catalyst, and the amount of nitrogen gas introduced is 0.62 L / mL of catalyst. The reactor temperature was set to 120 ° C., and the reactor internal temperature was set to 280 ° C. (SV = 1000 h ⁻¹ ). The reaction results 6 hours after the start of the reaction were as follows.
Unsaturated alcohol conversion: 99.8%
1,3-butadiene selectivity: 92.1%

The main by-products were as follows. At this time, the 1,3-butadiene total selectivity from 1,3-butanediol combined with the first dehydration step and the second dehydration step was 88.6%.
Propylene selectivity: 0.1%
Butene selectivity: 1.0%
n-Butyraldehyde selectivity: 0.3%

(Comparative Example 1)
A graphite-supported sodium polyphosphate catalyst D was used, and 1,3-butanediol was used as a substrate, and water vapor and nitrogen gas were used as diluents. The amount of 1,3-butanediol introduced was 0.081 g / mL of the catalyst, the amount of steam (gas) introduced was 0.025 L / mL of the catalyst, and the amount of nitrogen gas introduced was 0.140 L / mL of the catalyst. The reactor temperature was set to 260 ° C., and the reactor internal temperature was set to 270 ° C. (SV = 185 h ⁻¹ ). The reaction results 6 hours after the start of the reaction were as follows.
1,3-butanediol conversion rate: 100%
1,3-butadiene selectivity: 82.3%
3-Buten-2-ol selectivity: 0.0%
Crotyl alcohol selectivity: 0.0%
3-Buten-1-ol selectivity: 1.8%

The main by-products were as follows.
Propylene selectivity: 3.1%
Butene selectivity: 0.2%
n-Butyraldehyde selectivity: 5.3%

However, the following formula was used for the calculation of the conversion rate and the selectivity.

In addition, in calculating the by-product selectivity, the following formula was used in consideration of the difference in carbon number. “4” in the denominator means the carbon number of 1,3-butanediol, and “the number of carbon atoms in one molecule” means the carbon number of the by-product to be calculated.

(Comparative Example 2)
In the same manner as in Comparative Example 1, a dehydration reaction for producing 1,3-butadiene was carried out in one step using the graphite-supported sodium polyphosphate catalyst D. However, the amount of 1,3-butanediol introduced was changed to 0.485 g / mL of the catalyst, the amount of steam (gas) introduced was changed to 0.15 L / mL of the catalyst, and the amount of nitrogen introduced was changed to 0.84 L / mL of the catalyst. (SV = 1110 h ⁻¹ ). The reaction results 6 hours after the start of the reaction were as follows.
1,3-butanediol conversion: 99.9%
1,3-butadiene selectivity: 71.6%
3-Buten-2-ol selectivity: 0.0%
Crotyl alcohol selectivity: 0.1%
3-buten-1-ol selectivity: 12.2%

The main by-products were as follows.
Propylene selectivity: 2.6%
Butene selectivity: 0.1%
n-Butyraldehyde selectivity: 4.6%

(Reference Example 1)
A graphite-supported sodium polyphosphate catalyst D was used, and 3-buten-1-ol was used as a substrate, water vapor and nitrogen gas as diluents, and a dehydration reaction was performed under the same conditions as in Comparative Example 1. The reaction results 6 hours after the start of the reaction were as follows.
3-Buten-1-ol conversion: 96%
1,3-butadiene selectivity: 79.4%

(Reference Example 2)
A graphite-supported sodium polyphosphate catalyst D was used, and 3-buten-2-ol was used as a substrate, water vapor and nitrogen gas as diluents, and a dehydration reaction was performed under the same conditions as in Comparative Example 1. The reaction results 7 hours after the start of the reaction were as follows.
Conversion of 3-buten-2-ol: 99.9%
1,3-butadiene selectivity: 90.2%

(Reference Example 3)
A graphite-supported sodium polyphosphate catalyst D was used, and dehydration reaction was performed under the same conditions as in Comparative Example 1 using crotyl alcohol as a substrate and water vapor and nitrogen gas as diluents. The reaction results 7 hours after the start of the reaction were as follows.
Crotyl alcohol conversion: 99.9%
1,3-butadiene selectivity: 90.8%

  Based on the results of Reference Example 1 to Reference Example 3, unsaturated alcohol (3-buten-2-ol, crotyl alcohol, 3-buten-1-ol) recovered in Comparative Example was used to produce 1,3-butadiene. Assuming that it was used, the total selectivity of 1,3-butadiene from 1,3-butanediol combined with these components was 83.7% in Comparative Example 1 and 81.5% in Comparative Example 2. calculated.

  The results of Examples 1 to 3 and Comparative Examples 1 and 2 are shown in Tables 1 to 3. The value of the total selectivity of 1,3-butadiene in Examples is higher than the total selectivity of 1,3-butadiene in Comparative Examples. In Examples 1 to 3, the distillation operation was performed after the first dehydration step, and Examples 1 to 3 are Comparative Example 1 although the impurities generated here are calculated as complete loss. And clearly show an advantage over 2. In addition, if the three unsaturated alcohols (3-buten-2-ol, crotyl alcohol, 3-buten-1-ol) by-produced in the comparative example are separated and subjected to a dehydration reaction, 1,3-butadiene is obtained. Although conversion is possible, it can be seen from Tables 2 and 3 that even if this operation is performed, the total selectivity of 1,3-butadiene in Examples 1 to 3 is higher. In the comparative example, the target diene compound can be produced in one step, but it is unexpected that the present invention (Examples) in which the two-step dehydration reaction is seemingly inefficient is conversely more efficient. Propylene, butene and n-butyraldehyde shown in Table 3 are by-products (impurities) of the dehydration reaction. These by-products can no longer be converted to 1,3-butadiene like the three unsaturated alcohols, which is a complete loss. Since these impurities are also less in the examples, it can be seen that the conversion of the diol to the target diene compound is highly selective by the method of the present invention.

Claims (10)

The manufacturing method of the diene compound characterized by including the following 2 processes at least.
First dehydration step of producing unsaturated alcohol represented by general formula (2) -1 and general formula (2) -2 from diol represented by general formula (1) using rare earth element oxide as catalyst

(In the ^formula, each of R 1 to R ⁶ independently represent a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or an aryl group having 6 to 12 carbon atoms.)

(In the formula, R ^{1 to} R ⁶ are the same as those in the general formula (1).)

(In the formula, R ^{1 to} R ⁶ are the same as those in the general formula (1).)
A second process for producing a diene compound represented by the general formula (3) by simultaneously carrying out a dehydration reaction of the unsaturated alcohol represented by the general formula (2) -1 and the general formula (2) -2 in the presence of a dehydration catalyst. Dehydration process

(In the formula, R ^{1 to} R ⁶ are the same as those in the general formula (1).)   The diene compound according to claim 1, wherein the rare earth element used in the first dehydration step is at least one selected from the group consisting of La, Ce, Tb, Dy, Ho, Y, Er, Tm, Yb, Lu, and Sc. Manufacturing method.   The method for producing a diene compound according to claim 1, wherein the rare earth element used in the first dehydration step is Ce. The method for producing a diene compound according to claim 1, wherein the rare earth element oxide used in the first dehydration step is cerium oxide (CeO ₂ ).   5. The dehydration catalyst in the second dehydration step is at least one selected from the group consisting of metal phosphates, metal condensed phosphates, metal sulfates, metal hydrochlorides, metal oxides, and inorganic acids. The manufacturing method of the diene compound as described in any one of these.   The metal phosphate, metal condensed phosphate, metal sulfate, or metal hydrochloride metal is made of alkali metal, alkaline earth metal, Ti, Zr, Hf, Nb, Ta, Al, B, and Sn The method for producing a diene compound according to claim 5, which is at least one selected from the group consisting of:   The method for producing a diene compound according to claim 5, wherein the metal oxide is at least one selected from the group consisting of silica, alumina, magnesia, titania, zirconia, niobia, silica alumina, silica magnesia, and zeolite.   The method for producing a diene compound according to any one of claims 5 to 7, wherein the dehydration catalyst in the second dehydration step is a catalyst supported on a carrier. All the R < ¹ > -R < ⁶ > of General formula (1) is a hydrogen atom, The manufacturing method of the diene compound as described in any one of Claims 1-8.   The method for producing a diene compound according to claim 9, wherein the selectivity for 3-buten-1-ol, which is a by-product in the first dehydration step, is 5.0% or less.