Method for producing 1,3-butanediol

Abstract

To provide a method for producing 1,3-butanediol by the hydrogenation of paraaldol in high yield and with economy.SOLUTION: Paraaldol is hydrogenated in the presence of a hydrogenation catalyst to give 1,3-butanediol. As a first reactor, a trickle bed-type reactor is used first and then, a liquid-phase circulation reactor is used as a second reactor. An example of the hydrogenation catalyst is a catalyst including nickel.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a method for producing 1,3 - butanediol.

Background Art

[0002] 1,3 - Butanediol is a viscous, colorless, transparent, and odorless water - soluble liquid with a boiling point of 207°C and is used as a raw material for various derivatives. For example, esters formed from long - chain carboxylic acids and 1,3 - butanediol are used as plasticizers. Also, due to its low biotoxicity and stability, 1,3 - butanediol is used as a cosmetic raw material. As a cosmetic raw material, 1,3 - butanediol has characteristics such as a moisturizing effect, antibacterial property, and low stickiness, and is thus used in a wide range of products such as shampoos and emulsions.

[0003] One of the main production methods of 1,3 - butanediol is to condense acetaldehyde to obtain acetaldol (3 - hydroxybutanal) and then hydrogenate it. However, acetaldol itself is unstable and difficult to handle as a single substance.

[0004] Therefore, in practice, acetaldehyde is condensed in the presence of a basic catalyst to obtain aldoxane (the common name for 2,6 - dimethyl - 1,3 - dioxane - 4 - ol), and the acetaldehyde generated by the thermal decomposition of aldoxane is distilled off to obtain para - aldol (the common name for 4 - hydroxy - α,6 - dimethyl - 1,3 - dioxane - 2 - ethanol), which is a dimer of acetaldol (Patent Document 1).

[0005] Then, this para - aldol is used as a raw material for the hydrogenation reaction to produce 1,3 - butanediol. Aldoxane may also be used as a raw material for the hydrogenation reaction. In this case, although ethanol is by - produced, 1,3 - butanediol can be produced.

[0006] Therefore, in the present disclosure, para-aldol and aldoxane are considered to be equivalents of acetaldol, and are collectively referred to as "acetaldols."

[0007] In the hydrogenation reaction of acetaldols, a sponge nickel catalyst is generally used as a catalyst, and a continuous suspension bubble column, which is a fluidized bed, is used as a reactor (Patent Document 2). [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Publication No. 62-212384 [Patent Document 2] JP 2001-213822 A Summary of the Invention [Problem to be solved by the invention]

[0009] An object of the present invention is to provide a method for producing 1,3-butanediol by hydrogenation of para-aldol, which has a high yield and is economical.

[0010] As a result of extensive research, the inventors have found that the above-mentioned problems can be solved by carrying out the hydrogenation reaction of para-aldol using at least two types of reactors, using a trickle-bed type reactor as the first reactor and a liquid-phase flow reactor as the second reactor, and have thus completed the present invention.

[0011] That is, the present invention includes the following [1] to [4]. [1] A method for producing 1,3-butanediol by hydrogenating para-aldol in the presence of a hydrogenation catalyst, comprising using a trickle-bed reactor as a first reactor and then using a liquid-phase flow reactor as a second reactor. [2] The method for producing 1,3-butanediol according to [1], wherein the hydrogenation catalyst in the first reactor and the second reactor is a catalyst containing nickel. [3] The method for producing 1,3-butanediol according to [2], wherein the nickel content in the hydrogenation catalyst is 5 to 90 mass %. [4] The method for producing 1,3-butanediol according to any one of [1] to [3], wherein the temperature of the liquid-phase flow reactor is set to 120° C. or lower. Effect of the Invention

[0012] According to the present invention, 1,3-butanediol can be produced in high yield and economically. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Preferred embodiments of the present invention will be described below, but it should be understood that the present invention is not limited to these embodiments and that various applications are possible within the spirit and scope of the present invention.

[0014] In one embodiment of the method for producing 1,3-butanediol, as shown in the following reaction formula, acetaldehyde is used as a starting material, and acetaldols are hydrogenated to obtain 1,3-butanediol.

[0015] 1. Condensation process [ka]

[0016] 2.Pyrolysis process [ka]

[0017] 3. Hydrogenation process [ka]

[0018] 1. Condensation process The condensation step is a step of obtaining acetaldol or further aldoxane from acetaldehyde. The acetaldol is a raw material for hydrogenation reaction, and the method for producing it is not particularly limited. For example, it can be prepared by the following method.

[0019] By reacting acetaldehyde with a catalytic amount of base, two molecules of acetaldehyde react to obtain one molecule of acetaldol. As the base, for example, sodium hydroxide or potassium hydroxide can be used. Since the generated acetaldol is unstable, one molecule of acetaldol reacts with one molecule of acetaldehyde to generate one molecule of aldoxane. In the present disclosure, such a reaction to obtain acetaldol and further aldoxane from acetaldehyde is called a condensation reaction, and the process of performing the condensation reaction is called a condensation process.

[0020] Since the condensation reaction is an equilibrium reaction, the reaction progresses slowly as the equilibrium composition approaches. If a base is present in this state, acetaldol will further condense to produce high boiling components such as trimers, or acetaldol will dehydrate to produce crotonaldehyde. Therefore, an acid is added as necessary to neutralize the base and stop the reaction. For example, an organic acid such as acetic acid can be used as the acid.

[0021] The condensation reaction can be carried out in a liquid phase at a temperature of 20 to 50°C, a pressure of 0.1 to 0.2 MPaG (gauge pressure), and a reaction time of 2 to 20 minutes. The reaction atmosphere is preferably an inert gas such as nitrogen gas or argon. There are no limitations on the reactor used in the condensation reaction, and for example, a tank-type reactor can be used.

[0022] 2.Pyrolysis process 1,3-butanediol can also be obtained by hydrogenating the aldoxane obtained in the condensation step, but one molecule of aldoxane produces one molecule of ethanol along with one molecule of 1,3-butanediol. Therefore, if the co-production of ethanol is undesirable, the aldoxane can be converted to para-aldol by thermal decomposition of the aldoxane as necessary, and the resulting para-aldol can be hydrogenated. This allows 1,3-butanediol to be obtained without producing ethanol as a by-product.

[0023] When aldoxane is heated, one molecule of aldoxane decomposes into one molecule of acetaldol and one molecule of acetaldehyde through an equilibrium reaction. Then, under certain temperature and pressure conditions, acetaldehyde is vaporized and removed from the system. At this time, two molecules of acetaldol remaining combine to produce one molecule of para-aldol. The by-product acetaldehyde can be reused as a starting material. In this disclosure, such a reaction to obtain para-aldol and acetaldehyde from aldoxane is called a pyrolysis reaction, and the process of carrying out the pyrolysis reaction is called a pyrolysis process.

[0024] When one molecule of para-aldol is hydrogenated, two molecules of 1,3-butanediol can be obtained. Therefore, if the pyrolysis reaction is carried out to completely convert aldoxane to para-aldol, and then the hydrogenation reaction is carried out, no ethanol is produced at all. However, in the process of converting aldoxane to para-aldol, crotonaldehyde is produced by dehydration of acetaldol, and high boiling components are produced by polymerization of acetaldol, crotonaldehyde, etc. For this reason, in practice, the pyrolysis reaction of aldoxane is stopped at an appropriate conversion rate, and a mixture of aldoxane and para-aldol is obtained as the pyrolysis reaction liquid.

[0025] The thermal decomposition reaction can be carried out in a liquid phase at a temperature of 60 to 80° C., a pressure of 0.01 to 0.1 MPaG, and a reaction time of 20 to 90 minutes. The reaction atmosphere is preferably an inert gas such as nitrogen gas or argon.

[0026] In the next step, the hydrogenation step, the para-aldol and the aldoxane in the pyrolysis reaction liquid are separated, and then only the para-aldol may be used as the raw material for the hydrogenation reaction. Alternatively, since it is difficult to separate the two by a general separation method such as distillation, the mixture may be used as the raw material for the hydrogenation reaction without separation. The raw material for the hydrogenation reaction may contain not only crotonaldehyde or high boiling components generated in the pyrolysis step, but also salts generated by neutralization of the base used in the condensation step.

[0027] 3. Hydrogenation process The acetaldols obtained in the pyrolysis process are decomposed into hydrogen gas (H 2 ) in the presence of a hydrogenation catalyst, and converted to 1,3-butanediol. In this disclosure, the process of carrying out the hydrogenation reaction is referred to as the hydrogenation process.

[0028] Any hydrogenation catalyst can be used. Generally, an effective hydrogenation catalyst is a nickel-based catalyst. The nickel-based catalyst preferably contains 5 to 90 mass % of nickel. In particular, stabilized nickel in which nickel is supported on a support such as alumina or silica, and sponge nickel in which aluminum is dissolved from an alloy of nickel and aluminum are effective.

[0029] Two types of reactors are used in the hydrogenation process: a trickle-bed reactor as the first reactor and a liquid-phase flow reactor as the second reactor.

[0030] A trickle bed reactor is a reactor in which a reaction is carried out by passing gas and liquid through a fixed bed filled with a solid catalyst. In a trickle bed reactor, the reaction proceeds in a gas-liquid-solid three-phase, which increases the contact efficiency between hydrogen gas and acetaldols and the catalyst, and the hydrogenation reaction of acetaldols proceeds efficiently. On the other hand, in a trickle bed reactor, the amount of liquid held is small, so it may be insufficient to completely react the trace amounts of unreacted raw materials remaining.

[0031] A liquid-phase flow reactor is a reactor in which a reaction is carried out by flowing a liquid or a liquid in which a gas is dissolved through a catalyst filled with the reactor. In a liquid-phase flow reactor, the reaction proceeds in two phases, between the reaction raw material liquid in which hydrogen gas is dissolved and the catalyst, so the reaction efficiency is lower than that of a trickle-bed reactor. On the other hand, a liquid-phase flow reactor can hold a larger amount of liquid per reactor volume than a trickle-bed reactor, so that the contact time between the reaction raw material and the catalyst can be increased, and a small amount of reaction raw material can be sufficiently reacted.

[0032] By using a trickle bed reactor and then a liquid-phase flow reactor, the reaction can be efficiently carried out, and the amount of catalyst required can be reduced compared to the case where the trickle bed reactor and the liquid-phase flow reactor are each used alone.

[0033] The temperature at which the hydrogenation reaction is carried out using a trickle bed reactor can be 50 to 150° C., and is preferably 100 to 120° C. By setting the reaction temperature at 50° C. or higher, the hydrogenation reaction can be ensured to proceed, and by setting the reaction temperature at 150° C. or lower, side reactions such as hydrocracking reactions can be suppressed, and the yield of the target product, 1,3-butanediol, can be increased.

[0034] In the trickle-bed flow reactor, the pressure at which the hydrogenation reaction is carried out can be 1 to 4 MPaG, and preferably 2 to 3 MPaG. By setting the pressure at 1 MPaG or more, the hydrogenation reaction can be promoted, and by setting the pressure at 4 MPa or less, the cost required for increasing the hydrogen pressure and the equipment cost can be reduced.

[0035] The temperature at which the hydrogenation reaction is carried out using a liquid-phase flow reactor is preferably 120° C. or lower. Specifically, the temperature can be 50 to 120° C., and is preferably 70 to 100° C.

[0036] By setting the reaction temperature at 50°C or higher, the hydrogenation reaction can proceed reliably, and by setting the reaction temperature at 120°C or lower, side reactions such as hydrogenolysis reactions can be suppressed, thereby increasing the yield of the target product, 1,3-butanediol.

[0037] In the liquid-phase flow reactor, the pressure at which the hydrogenation reaction is carried out can be 1 to 15 MPaG, and preferably 2 to 12 MPaG. By setting the pressure at 1 MPaG or more, the hydrogenation reaction can be promoted, and by setting the pressure at 15 MPa or less, the cost required for increasing the hydrogen pressure and the equipment cost can be reduced. EXAMPLES

[0038] Hereinafter, the embodiment of the present invention will be described in detail, but the present invention is not limited to the examples.

[0039] The components were identified and quantified using a gas chromatography analyzer and an NMR spectrometer under the following analytical conditions:

[0040] (Gas Chromatography Analysis Conditions) GC device: Agilent 6850 (manufactured by Agilent) Column: Agilent DB-WAX (0.32 mm, 30 m) Injection temperature: 200℃ Column temperature: 40℃→200℃ Detector temperature: 200℃ Carrier gas: He Detector: FID

[0041] (NMR analysis conditions) Nuclear magnetic resonance apparatus: JNM-ECS400 (manufactured by JEOL Ltd.)

[0042] <Example 1> A trickle-bed reactor (first reactor, internal volume: 6 L) packed with 8.4 kg of sponge nickel catalyst (D-2311L, manufactured by Nikko Rica Corporation) was charged with H 2The gas was passed through at 1000 NL / h to adjust the pressure to 2.5 MPaG, and the reactor temperature to 120° C. As the hydrogenation raw material liquid, a 1,3-butanediol liquid containing 5 mass% para-aldol, 8 mass% ethanol, and 12 mass% water was prepared, and passed through the trickle bed reactor at 60 L / h to carry out the hydrogenation reaction until a steady state was reached.

[0043] The reaction solution obtained at steady state was 2 The gas was dissolved at a pressure of 8.0 MPaG and a temperature of 80°C, and the resulting liquid was passed through a liquid-phase flow reactor (second reactor, internal volume 10 mL) filled with 14 g of sponge nickel catalyst (D-2311L, manufactured by Nikko Rica Corporation) at a rate of 40 mL / h, and a hydrogenation reaction was carried out at a residence time of 15 min and a reactor temperature of 80°C.

[0044] <Comparative Example 1>, Only the hydrogenation reaction in the trickle-bed reactor (first reactor) in Example 1 was carried out.

[0045] <Comparative Example 2> A trickle-bed reactor (first reactor, internal volume: 6 L) packed with 8.4 kg of sponge nickel catalyst (D-2311L, manufactured by Nikko Rica Corporation) was charged with H 2 The gas was passed through at 1000 NL / h to adjust the pressure to 2.5 MPaG, and the reactor temperature to 120° C. As a hydrogenation raw material liquid, a 1,3-butanediol liquid containing 5 mass% para-aldol, 8 mass% ethanol, and 12 mass% water was prepared, and passed through a trickle bed reactor at 60 L / h to carry out the hydrogenation reaction until a steady state was reached, thereby obtaining a reaction liquid.

[0046] Next, H was added to a trickle-bed reactor (second reactor, internal volume: 6 L) packed with 8.4 kg of sponge nickel catalyst (D-2311L, manufactured by Nikko Rica Corporation). 2 Gas was circulated at 1000 NL / h to adjust the pressure to 2.5 MPaG and the reactor temperature to 120°C, and then the reaction liquid obtained in the first reactor was circulated at 60 L / h to carry out a hydrogenation reaction.

[0047] That is, in Comparative Example 2, a trickle-bed reactor was also used for the second-stage hydrogenation reaction, and the hydrogenation reaction was carried out under the same conditions as those for the first stage.

[0048] The results of the examples and comparative examples are shown in Table 1.

[0049] [Table 1]

[0050] As is clear from the results shown in Table 1, in Example 1, the catalyst mass (first reactor + second reactor) required per para-aldol mass to obtain the same molar yield of 1,3-butanediol can be reduced compared to Comparative Example 2. [Industrial Applicability]

[0051] The present invention provides an economical method for producing 1,3-butanediol, which can reduce the amount of catalyst used.

Claims

[Claim 1] A method for obtaining 1,3-butanediol by hydrogenating para-aldol in the presence of a hydrogenation catalyst, comprising using a trickle-bed reactor as a first reactor and then using a liquid-phase flow reactor as a second reactor, the hydrogenation catalyst in the first reactor and the second reactor is a catalyst containing nickel, and the nickel content of the hydrogenation catalyst is 5 to 90 mass%, The temperature of the trickle bed reactor is 50 to 150° C. and the pressure is 1 to 4 MPaG; The temperature of the liquid-phase flow reactor is set to 50 to 120° C., and the pressure is set to 1 to 15 MPaG.

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