JP7784651B2 - Method for producing unsaturated alcohol - Google Patents

Description

The present invention relates to a method for producing unsaturated alcohols.

One well-known method for producing unsaturated alcohols is to use unsaturated fatty acid alkyl esters as a raw material. This method involves reacting an unsaturated fatty acid alkyl ester with hydrogen in the presence of a catalyst to produce the unsaturated alcohol. Patent Document 1, for example, discloses an example of this type of technology, which involves using a catalyst with a specific range of strength and reacting an unsaturated fatty acid alkyl ester with hydrogen gas under conditions that maintain a specific range of liquid phase on the surface of the catalyst.

Patent Document 2 discloses a method for producing liquid vegetable unsaturated alcohols, in which a zinc-based catalyst with a copper content of 30 ppm or less is used as the catalyst, and a reduction reaction is carried out using a fixed-bed continuous reaction system under high temperature and pressure. The working examples in Patent Document 2 describe a reduction reaction using unsaturated fatty acid methyl esters obtained by methyl-esterifying 10 kg of unsaturated fatty acids derived from palm kernel oil as a raw material, in the presence of a zinc-based catalyst with a copper content of 5 ppm, under conditions of a reaction pressure of 20 MPa, a reaction temperature of 290°C, and a superficial velocity of the raw material feed of 0.3 m/h.

WO2004/048297 publication WO2003/089393 publication

The present invention aims to provide a method for continuously producing unsaturated alcohols using unsaturated fatty acid alkyl esters as a raw material, which suppresses the generation of by-products and is applicable on an industrial scale.

The production method disclosed herein is a method for producing an unsaturated alcohol by reducing an unsaturated fatty acid alkyl ester in the presence of a catalyst. The production method includes the steps of "charging an unsaturated fatty acid alkyl ester (wherein the alkyl ester has 1 to 4 alkyl carbon atoms) and an aliphatic monoalcohol having 1 to 4 carbon atoms into a reaction tower" and "supplying hydrogen to the reaction tower and obtaining an unsaturated alcohol by a reduction reaction."

The production method disclosed herein provides a method for continuously producing unsaturated alcohols using unsaturated fatty acid alkyl esters as a raw material, suppressing the generation of by-products, and being applicable on an industrial scale.

FIG. 1 is a schematic diagram showing the configuration of a manufacturing facility suitable for carrying out the manufacturing method according to the present disclosure. FIG. 2 is a cross-sectional schematic diagram showing the configuration of a reaction tower suitable for carrying out the production method according to the present disclosure. FIG. 3 is a schematic diagram showing the shape of a catalyst and the flow of a reaction system suitable for carrying out the production method according to the present disclosure.

[Outline of the embodiment]
First, embodiments of the method for producing an unsaturated alcohol according to the present disclosure will be listed and described. In this specification, unless otherwise specified, the numerical range "A to B" means "A or more and B or less."

The production method disclosed herein is a method for producing an unsaturated alcohol by reducing an unsaturated fatty acid alkyl ester in the presence of a catalyst. The production method includes the steps of charging a reaction tower with an unsaturated fatty acid alkyl ester (wherein the alkyl ester has 1 to 4 alkyl carbon atoms) and an aliphatic monoalcohol having 1 to 4 carbon atoms, and supplying hydrogen to the reaction tower and obtaining the unsaturated alcohol through a reduction reaction.

In the past, in methods for producing unsaturated alcohols by reducing unsaturated fatty acid alkyl esters, appropriate catalyst compositions, forms, reaction conditions, etc. have been investigated to improve productivity. Furthermore, production methods have been developed to obtain unsaturated alcohols with good liquid retention and low cloud points. Meanwhile, there is a demand for methods that can produce unsaturated alcohols of sufficient quality at practical costs, even when the laboratory scale is expanded to industrial production scale (e.g., production volume of 10 t/day or more).

The inventors recognized that the impurities (products other than the target product) generated during the process of reducing unsaturated fatty acid alkyl esters are hydrocarbons further produced from the alcohol produced from the esters, and saturated alcohols produced by overreaction. They then conducted extensive research into a technology for reducing only the esters to alcohol without reducing the double bonds in the unsaturated fatty groups. As a result, they discovered that by adding a fatty alcohol having 1 to 4 carbon atoms along with the raw material unsaturated fatty acid alkyl ester, it is possible to suppress the generation of by-products and produce unsaturated alcohols of stable quality with excellent production efficiency. One of the features of the production method disclosed herein is that, in addition to the raw material unsaturated fatty acid alkyl ester, a commonly used raw material fatty alcohol having 1 to 4 carbon atoms is added. The production method disclosed herein does not require special processes or materials and can be implemented industrially without increasing costs.

Without being bound by theory, it is believed that by charging an aliphatic alcohol with 1 to 4 carbon atoms along with the raw material unsaturated fatty acid alkyl ester, the unsaturated alcohol produced in the reaction system is prevented from adsorbing back onto the catalyst, thereby preventing side reactions and over-reactions.

In the above-described production method, the unsaturated fatty acid alkyl ester may be an unsaturated fatty acid alkyl ester derived from an animal or plant and having an acid value of 0 to 10, and the aliphatic alcohol having 1 to 4 carbon atoms may be methanol.

In the above-described production method, the amount of the fatty alcohol charged relative to the unsaturated fatty acid alkyl ester may be 8 parts by mass or more and 15 parts by mass or less.

In the above-described production method, the reaction towers include a first reaction tower, a second reaction tower, a third reaction tower, and a fourth reaction tower connected to one another in this order, and each of the first reaction tower, the second reaction tower, the third reaction tower, and the fourth reaction tower may be a fixed-bed reaction tower packed with a granular zinc-based solid catalyst. The first reaction tower and the third reaction tower may be configured so that the unsaturated fatty acid alkyl ester, the aliphatic alcohol, and hydrogen gas flow downward in parallel, while the second reaction tower and the fourth reaction tower may be configured so that the unsaturated fatty acid alkyl ester, the aliphatic alcohol, and hydrogen gas flow upward in parallel.

In the above-described production method, the step of obtaining an unsaturated alcohol by the reduction reaction is carried out so that the reaction product obtained from a sampling line located downstream of the outlet end of the fourth reaction tower has a ketone value (SV) of 4.0 to 7.0, and a step of distilling the obtained reaction product may be carried out following the step of obtaining the unsaturated alcohol.

In the production method, the zinc-based solid catalyst may be a cylindrical solid catalyst having a diameter of 3 to 5 mm and a height of 3 to 5 mm, the first reaction tower, the second reaction tower, the third reaction tower, and the fourth reaction tower may each have a cylindrical reaction chamber having an inner diameter of 0.45 to 0.55 m and a height of 11 to 13 m, and the supply rate of hydrogen gas to the first reaction tower may be 3 to 21 m ³ /h.

In the above-described production method, the temperature difference between the inlet end temperature of the first reaction tower and the outlet end temperature of the second reaction tower may be 20 to 60°C, and the temperature difference between the inlet end temperature of the third reaction tower and the outlet end temperature of the fourth reaction tower may be 0 to 20°C.

The manufacturing method according to the present disclosure will be described in more detail below.
(Raw materials used in the manufacturing method)
The unsaturated alcohol according to the present disclosure is prepared from an unsaturated fatty acid alkyl ester, which may be obtained by esterifying an unsaturated fatty acid as a preliminary step in the production method according to the present disclosure.

The unsaturated fatty acids used as raw materials for the unsaturated fatty acid alkyl esters may be vegetable unsaturated fatty acids derived from coconut oil, palm kernel oil, palm oil, olive oil, soybean oil, low-erucic rapeseed oil, high-erucic rapeseed oil, safflower oil, corn oil, cottonseed oil, sunflower oil, rice bran oil, linseed oil, etc., and/or animal unsaturated fatty acids derived from beef tallow, lard, chicken oil, whale oil, fish oil, etc. These unsaturated fatty acids are typically mixtures of unsaturated fatty acids having 16 to 22 carbon atoms. One or more lower alkyl esters of these unsaturated fatty acids, particularly methyl esters, are preferably used as raw materials for the unsaturated alcohols. Specifically, for example, the unsaturated fatty acid alkyl esters include methyl oleate.

The aforementioned unsaturated fatty acids can be obtained by hydrolyzing fats and oils using conventional methods. The aforementioned unsaturated fatty acid alkyl esters can be obtained by esterifying the unsaturated fatty acids obtained by hydrolyzing fats and oils with a lower alcohol (for example, an aliphatic alcohol having 1 to 4 carbon atoms, such as methyl alcohol). They can also be obtained by transesterification of vegetable fats and oils with an aliphatic alcohol having 1 to 4 carbon atoms, such as methyl alcohol.

The iodine value of the unsaturated fatty acid alkyl ester used as a raw material is preferably 40 to 200. The acid value (residual acid value) of the unsaturated fatty acid alkyl ester is preferably 0 to 10.

(alcohol)
In the production method according to the present disclosure, an aliphatic alcohol having 1 to 4 carbon atoms is charged into a reaction column together with the above-mentioned raw materials. The aliphatic alcohol having 1 to 4 carbon atoms may be one or more selected from the group consisting of methanol, ethanol, n-propanol, isopropanol, and butanol. Of these, it is preferable to use methanol.

(catalyst)
The catalyst used for ester reduction is preferably a zinc-based solid catalyst. Examples of zinc-based catalysts include zinc-chromium oxide, zinc-aluminum oxide, zinc-aluminum-chromium oxide, zinc-chromium-manganese oxide, zinc-iron oxide, and zinc-iron-aluminum oxide. These zinc-based solid catalysts can be suitably used in the reaction of reducing unsaturated fatty acid alkyl esters to unsaturated alcohols. Of these zinc-based catalysts, zinc-chromium oxide is particularly preferred. The zinc-based catalysts can be used alone or in combination of two or more.

It is most preferable that the zinc-based catalyst be substantially free of copper. If it contains copper, the copper content is preferably 20 ppm or less, and particularly 10 ppm or less. A copper content within this range prevents the cloud point of the resulting unsaturated alcohol from becoming too high.

The zinc-based catalyst may be in the form of fine particles and supported on a carrier. Examples of carriers include silica, alumina, silica-alumina, titania, diatomaceous earth, clay, activated carbon, carbon, graphite, zeolite, clays such as montmorillonite, and alkaline earth silicates.

Supported zinc-based catalysts can be prepared by conventional methods such as impregnation and coprecipitation, without any particular limitations. Furthermore, a powder or paste containing the zinc-based catalyst and the carrier can be used as the raw material and molded into a suitable shape using a conventional tablet press, granulator, extruder, or other machine.

The catalyst may be cylindrical, hollow cylindrical, trilobe prism, quadrilobe prism, spherical, or the like. Catalysts of two or more different shapes may be used in combination. It is preferable that the catalyst be cylindrical.

The size of the catalyst may be such that its minimum length is approximately 1 to 10 mm, with a minimum length of 3 to 5 mm being preferred. Here, "minimum length" refers to, for example, if the catalyst is a spherical catalyst with a diameter of 5 mm, the minimum length is 5 mm in diameter. If the catalyst is a cylindrical catalyst with a diameter of 3 mm and a height of 5 mm, the minimum length is 3 mm in diameter. Furthermore, in the case of a hollow cylinder, for example, a hollow cylinder with an outer diameter of 3 mm (inner diameter 2 mm) and a height of 5 mm, the minimum length is an outer diameter of 3 mm.

The catalyst strength can be 1.0 kg or more per catalyst. The catalyst strength is calculated by measuring the minimum crushing strength of 100 catalysts individually, calculating the average value A and standard deviation (σ), and then using the formula: A-2σ. The catalyst strength may be 1.0 kg or more, and is preferably 1.5 to 4.0 kg.

The minimum crushing strength is measured in accordance with JIS Z-8841-1993, "3.1 Crushing Strength Test Method." "Minimum crushing strength" refers to the smaller of the crushing strength measured when a catalyst having a shape such as a cylinder is compressed in the vertical direction (axial direction) and the crushing strength measured when it is compressed in the horizontal direction (radial direction, i.e., the direction perpendicular to the axial direction). For catalysts having a highly symmetrical shape such as a sphere or cube, there is generally no difference in crushing strength depending on the direction of compression, so the crushing strength measured in accordance with the aforementioned JIS method is taken as the minimum crushing strength.

The catalyst may be used as is after being packed into the reaction tower, or it is preferable to perform an activation treatment before using it in the reaction. Activation treatment can be performed by a known method, for example, by passing hydrogen gas through a reaction tower packed with the catalyst.

(manufacturing equipment)
FIG. 1 is a schematic diagram showing the configuration of a production facility suitable for carrying out the production method according to the present disclosure. In the following description, "upper" and "lower" refer to relative positions along the vertical direction. Referring to FIG. 1 , the production facility 1 includes four interconnected reaction towers: a first reaction tower 11, a second reaction tower 12, a third reaction tower 13, and a fourth reaction tower 14. A gas-liquid separator 31, a first distillation apparatus 32, and a second distillation apparatus 33 are provided downstream of the fourth reaction tower 14, in this order. The first reaction tower 11, the second reaction tower 12, the third reaction tower 13, and the fourth reaction tower 14 are reaction towers of the same shape and dimensions, and each is filled with a solid catalyst. The connection order of the reaction towers can be changed by rearranging the piping. In this specification, the reaction towers are referred to as the first reaction tower, the second reaction tower, the third reaction tower, and the fourth reaction tower, in order from the side closest to the raw material supply line. When rearrangement of the reaction columns is performed, as one embodiment of the rearrangement, the fourth reaction column before the rearrangement may be rearranged into the third reaction column after the rearrangement, and similarly, the third reaction column may be rearranged into the second reaction column, the second reaction column into the first reaction column, and the first reaction column into the fourth reaction column.

Connected to the first reaction tower 11 are pipe 41, a raw material supply line connecting to the raw material tank 21, and pipe 51, a hydrogen supply line connecting to the hydrogen tank 22. Although not shown, devices such as a preheating and temporary storage tank, a heater (heat exchanger), and a pump may be provided between the raw material tank 21 and the first reaction tower 11. Pipes 41 and 51 are connected to the top of the first reaction tower 11. That is, raw material and hydrogen gas are supplied to the first reaction tower 41 from its top. The raw material is a liquid, and the raw material and hydrogen gas flow down and co-currently within the first reaction tower. The first reaction tower 11 is filled with a catalyst 91 (Figure 3). Connected to the bottom of the first reaction tower 11 is pipe 42, a pipe connecting the first reaction tower 11 and the second reaction tower 12. Pipe 42 may be a pipe with an insulating jacket.

Pipe 42 is connected to the bottom of the second reaction tower 12. Pipe 43, which is a pipe connecting the second reaction tower 12 and the third reaction tower 13, is connected to the top of the second reaction tower 12. The raw material and hydrogen gas introduced into the second reaction tower 12 through the second pipe 42 flow up inside the second reaction tower 12 in a parallel upward flow and are discharged from pipe 43.

Pipe 43 is connected to the top of the third reaction tower 13. Pipe 44, which is a pipe connecting the third reaction tower 13 and the fourth reaction tower 14, is connected to the bottom of the third reaction tower 13. The raw material and hydrogen gas introduced into the third reaction tower 13 through the third pipe 43 flow down in parallel inside the third reaction tower 13 and are discharged from pipe 44.

Pipe 44 is connected to the bottom of the fourth reaction tower 14. Pipe 45, which connects the fourth reaction tower 14 to the gas-liquid separator 31, is connected to the top of the fourth reaction tower 14. The raw material and hydrogen gas introduced into the fourth reaction tower 14 through the fourth pipe 44 flow up concurrently inside the fourth reaction tower 14 and are discharged from pipe 45. As the raw material, unsaturated fatty acid alkyl ester, moves from the first reaction tower 11 to the fourth reaction tower 14, the ester is reduced to form an unsaturated alcohol. In other words, the first reaction tower 11 to the fourth reaction tower 14 constitute a reduction reaction apparatus, and the gas-liquid separator 31, first distillation apparatus 32, and second distillation apparatus 33 constitute equipment for separating and purifying the product unsaturated alcohol from the resulting reaction mixture.

Gas-liquid separator 31 is, for example, a high-pressure separator. Gas-liquid separator 31 is connected to pipe 52, a return line for returning hydrogen gas separated from the reaction mixture to pipe 52, a hydrogen supply line. Gas-liquid separator 31 is connected to first distillation apparatus 32 via pipe 46. First distillation apparatus 32 is an initial distillation column, and low-boiling-point components are distilled off in first distillation apparatus 32. Although not shown, multiple connections from pipe 46 to first distillation apparatus 32 may be provided, spaced apart vertically. The liquid component (crude unsaturated alcohol containing unreacted raw materials) separated in gas-liquid separator 31 is transferred to first distillation apparatus 32 via pipe 46. A transesterification catalyst is added during this process. Transesterification during the distillation stage will be described later.

The first distillation apparatus 32 is connected to the second distillation apparatus 33 via piping 47. The second distillation apparatus 33 is the so-called main fraction column. The second distillation apparatus 33 is connected to both the product tank 34 and the pitch tank 35. The unsaturated alcohol product is recovered as a distillate from the second distillation apparatus 33 and stored in the product tank 34. The distillation residue, pitch, is recovered in the pitch tank 35 and is reused as part of the reaction raw materials.

FIG. 2 is a cross-sectional schematic diagram showing the shape of the first reaction tower 11. The second reaction tower 12, the third reaction tower 13, and the fourth reaction tower 14 also have the same shape. Referring to FIG. 2, the first reaction tower 11 comprises a main body 71 having a cylindrical reaction chamber _V1 therein, and lids 72 and 73 disposed at both ends of the main body 71 in the longitudinal direction. The inner diameter _D1 of the main body 71 (i.e., the diameter of the reaction chamber _V1 ) is 0.5 m. The height _H1 of the reaction tower is 12 m. Naturally, the shape of the reaction tower is not limited to this, and the dimensions of each part can be changed. The inner diameter of the reaction chamber may be approximately 0.4 to 0.8 m, and preferably 0.45 to 0.55 m. The height of the reaction tower may be approximately 10 to 15 m, and preferably 11 to 13 m. The reaction chamber preferably has a ratio (H/D) of the height (H (m)) to the inner diameter (D (m)) of about 10 to 40, and more preferably about 20 to 30. The reaction chamber _V1 is filled with a solid catalyst.

The lids 72 and 73 are fixed to the main body 71 by means of bolts or the like. The lid 72 is provided with fluid inlets and outlets 81 and 82 to which the raw material supply piping is connected, and a pressure gauge insertion port 83. The lid 73 is provided with fluid inlets and outlets 84 and 85 to which the raw material removal piping is connected. Three upper and lower jackets 74, 75, and 76 are provided around the outer periphery of the main body 71. The temperature inside the reaction tower is controlled by circulating a heated heat transfer medium through the jackets 74, 75, and 76. Each of the jackets 74, 75, and 76 is provided with a valve 77, 78, and 79, and the amount of heat transfer medium circulating can be adjusted by adjusting the opening of the valves 77, 78, and 79.

FIG. 3 is a schematic diagram showing the shape of a catalyst and the flow of a reaction system suitable for carrying out the production method according to the present disclosure. FIG. 3 illustrates an embodiment in which the reaction raw materials and hydrogen gas flow upward in parallel in the second and fourth reaction towers. Referring to FIG. 3, catalyst 91 is a cylindrical solid catalyst. Catalyst 91 has a diameter d ₁ of 3.2 mm and a height h ₁ of 3.2 mm. The dimensions of the catalyst are not limited thereto, and the diameter may be approximately 3 to 5 mm, and the height may be approximately 3 to 5 mm. Catalyst 91 is packed in the aforementioned reaction chamber V _1. For example, when the reaction towers have the dimensions shown in FIG. 2, approximately 3,200 to 3,400 kg of catalyst can be packed in one reaction tower.

As mentioned above, in the second and fourth reaction towers, the reaction raw materials, unsaturated fatty acid alkyl esters and hydrogen gas, flow upward in parallel and come into contact with catalyst 91, causing the ester reduction reaction. In Figure 3, the flow of the reaction liquid (including unsaturated fatty acid alkyl esters, reaction products, and alcohol) is indicated by the open arrows. Hydrogen gas exists in the reaction liquid as bubbles and rises with the reaction liquid, as indicated by the black arrows.

(Manufacturing method)
The method for producing an unsaturated alcohol according to the present disclosure is preferably carried out in the above-mentioned production facility. The production method according to the present disclosure includes a charging step and a reduction reaction step, and preferably further includes a distillation step. The production method according to the present disclosure may be carried out continuously (continuous method) or batchwise (batch method), but production by a continuous method is preferred. In the case of a continuous method, the charging step, reduction reaction step, and distillation step are carried out continuously, so there may be no clear time division between each step.

The charging process involves charging raw materials and alcohol into a reaction tower packed with a catalyst. The amount of unsaturated fatty acid alkyl ester charged as raw material may be, for example, 20 to 22 tons per day, and the amount of methanol charged may be, for example, 2 to 2.5 tons per day. The amount of aliphatic alcohol charged relative to the unsaturated fatty acid alkyl ester may be 8 to 15 parts by mass. Within this range, the addition of aliphatic alcohol is effective in suppressing the generation of impurities and does not inhibit the reduction reaction of the ester. The unsaturated fatty acid alkyl ester is preferably preheated before being supplied to the reaction tower. In addition to the unsaturated fatty acid alkyl ester and alcohol, hydrogen gas is introduced into the reaction tower. The hydrogen gas is pre-pressurized in a compressor and then introduced into the reaction tower. The pressure of the hydrogen gas may be approximately 17 to 20 MPa.

The reduction reaction step is carried out following the charging step. The reduction reaction step is also called hydrogenation.
In the reduction reaction step, the unsaturated fatty acid alkyl ester, alcohol, and hydrogen gas (hereinafter, these may be collectively referred to as a raw material mixture) are transferred sequentially from the first reaction tower to the fourth reaction tower in the aforementioned production facility. During this time, the ester is reduced to produce an unsaturated alcohol.

The temperature of the first reaction tower may be adjusted to 230-250°C. The temperature difference between the inlet end temperature and the outlet end temperature of the first reaction tower may be 10-20°C. That is, the raw material is heated in the first reaction tower. The pressure of the first reaction tower may be 17-20 MPa. The flow rate of the raw material in the first reaction tower may be 400 kg/h-900 kg/h. Unsaturated fatty acid alkyl ester, alcohol, and hydrogen gas are supplied from the top of the first reaction tower. In the first reaction tower, the raw material mixture flows down in parallel and contacts the catalyst packed in the reaction tower. From the first reaction tower to the fourth reaction tower, the pressure and flow rate in the reaction towers may be approximately constant (with a fluctuation range of ±10% or less).

The first and second reaction towers are connected via piping, and the raw material mixture withdrawn from the bottom of the first reaction tower is introduced into the second reaction tower from its bottom. In the second reaction tower, the raw material mixture flows upward in parallel and contacts the catalyst packed in the reaction tower. The temperature of the second reaction tower may be adjusted to 270-300°C, or alternatively, 270-280°C. The temperature difference between the inlet end temperature and the outlet end temperature of the second reaction tower may be 20-50°C. The reduction reaction of the ester mainly proceeds in the second and fourth reaction towers, and it is believed that the reduction reaction of the ester mainly proceeds in the second reaction tower. Heat is generated during the reduction reaction, causing a temperature rise in the second reaction tower. Comparing the inlet end temperature of the first reaction tower with the outlet end temperature of the second reaction tower, it is preferable that the temperature at the outlet end of the second reaction tower be 20-60°C higher than the temperature at the inlet end of the first reaction tower.

The raw material mixture is removed from the top of the second reaction tower. The raw material mixture moves from the first reaction tower to the second reaction tower naturally, following the flow of hydrogen gas (gas flow) fed into the first reaction tower, and external power such as a pump is not required, although transfer using a pump or the like is acceptable. The same applies to transfer from the second reaction tower to the third reaction tower and from the third reaction tower to the fourth reaction tower.

The second and third reaction towers are connected via piping, and the raw material mixture withdrawn from the top of the second reaction tower is introduced into the third reaction tower from its top. Within the third reaction tower, the raw material mixture flows down in parallel and comes into contact with the catalyst packed within the reaction tower. The temperature of the third reaction tower may be adjusted to 270-280°C. The temperature difference between the inlet end temperature and outlet end temperature of the third reaction tower may be 0-10°C. The raw material mixture is withdrawn from the bottom of the third reaction tower.

The third and fourth reaction towers are connected via piping, and the raw material mixture withdrawn from the bottom of the third reaction tower is introduced into the fourth reaction tower from its bottom. Within the fourth reaction tower, the raw material mixture flows upward in parallel and contacts the catalyst packed within the reaction tower. The temperature of the fourth reaction tower may be adjusted to 260-280°C. The temperature difference between the inlet end temperature and the outlet end temperature of the fourth reaction tower may be 0-10°C. The raw material mixture is withdrawn from the top of the fourth reaction tower. The temperatures in the third and fourth reaction towers may be substantially constant (e.g., with a fluctuation range of ±10% or less). Compared to the temperature change (temperature rise) in the first and second reaction towers, the temperature change in the third and fourth reaction towers is small. The temperature difference between the inlet end temperature of the third reaction tower and the outlet end temperature of the fourth reaction tower may be 0-10°C.

The progress of the reduction (hydrogenation) reaction can be confirmed, for example, by the SV (Solvent Value). This can be used as a process control value. For example, the reduction reaction process is preferably carried out so that the Solvent Value (SV) of the reaction product obtained from a sampling line located downstream of the outlet end of the fourth reaction tower is 4.0 to 7.0.

The reaction time for the reduction reaction (the time it takes for the raw material mixture to reach the outlet end of the fourth reaction tower after being charged into the first reaction tower) may be approximately 5 to 15 hours, and preferably approximately 7 to 10 hours. The raw material mixture may be transferred continuously from the first reaction tower to the fourth reaction tower without residence time, or a predetermined residence time may be set in each reaction tower.

The raw material mixture that has undergone the reduction reaction step contains the reaction product, an unsaturated alcohol. In order to purify the unsaturated alcohol product, it is preferable to carry out distillation following the reduction reaction. Prior to distillation, the unreacted raw material, unsaturated fatty acid alkyl ester, may be converted to a longer-chain alkyl ester (e.g., a total of 20 to 40 carbon atoms). Conversion to a long-chain alkyl ester can be carried out by a transesterification reaction. By carrying out transesterification, the degree of purification by distillation can be improved and contamination of the unsaturated fatty acid alkyl ester, the unreacted raw material, with the desired unsaturated alcohol can be suppressed.

The distillation process may be carried out in two stages in equipment equipped with a first distillation column and a main distillation column. The first distillation column may be equipped with multiple inlets for the raw material mixture spaced apart vertically. The low-boiling components distilled off can be controlled by changing the inlet for the raw material mixture used. The fraction from which the low-boiling components have been distilled off is introduced into the main distillation column, where further distillation is carried out. The product, unsaturated alcohol, is obtained as a distillate separated and recovered in the main distillation column. The distillation residue is recovered as pitch from the bottom of the main distillation column and may be temporarily stored in a pitch tank before being reused as a reaction raw material.

The method for producing unsaturated alcohols according to the present disclosure may further include a slight hydrogenation step. Slight hydrogenation refers to a process in which conjugated diene bonds are substantially selectively hydrogenated to monoene bonds, resulting in hydrogenation without causing an increase in the cloud point. When slight hydrogenation is performed, it is generally preferable to use a copper-containing catalyst as the slight hydrogenation catalyst. Examples of copper-containing catalysts include copper, copper-zinc, copper-chromium, copper-zinc-chromium, and oxides thereof, as well as modified catalysts containing these with the addition of molybdenum, tungsten, magnesium, barium, aluminum, calcium, zirconium, manganese, and oxides thereof.

When carrying out slight hydrogenation, the reaction method is not particularly limited, and methods such as batch suspension bed reaction, continuous suspension bed reaction, and fixed bed continuous reaction can be used. In the case of batch or continuous suspension bed reaction, the reaction temperature may be approximately 100 to 200°C. The reaction pressure may be approximately 1 MPa to atmospheric pressure. When carrying out slight hydrogenation reaction using a fixed bed continuous reaction, it is preferable to pack the formed catalyst into a reaction tower, activate the catalyst, and then carry out the reaction by flowing the unsaturated alcohol raw material and hydrogen in a downward or upward cocurrent manner. The reaction temperature may be approximately 50 to 150°C. The reaction pressure may be approximately 1 MPa to atmospheric pressure.

The method for producing unsaturated alcohols according to the present disclosure may further include deodorization. When deodorization is performed, the deodorization operation can be carried out after distillation or slight hydrogenation, etc. When deodorization is performed, it is most preferable to carry out the deodorization immediately before commercialization. As a deodorization method, a method known for deodorizing unsaturated alcohols and the like can be used. Such known methods include, for example, steam deodorization, reduced pressure topping, thin-film distillation, and activated carbon adsorption. Steam deodorization is particularly preferred. Steam deodorization can also be used in combination with other deodorization methods.

When performing steam deodorization, deodorization can be carried out by blowing steam into the unsaturated alcohol at a temperature of approximately 100 to 200°C and a pressure of approximately 0.1 to 70 kPa. The amount of steam blown in can be, for example, approximately 0.1 to 20% by mass, converted to the mass of water, relative to the unsaturated alcohol.

[Example 1]
1) Equipment
The production equipment shown in Figure 1 was used. As mentioned above, the first, second, third, and fourth reaction towers were all identical in shape, with the reaction chambers each having a diameter of 50 cm and a height of 12 m. The reaction chambers were filled with a catalyst. Each tower was filled with 3,200 to 3,400 kg of catalyst. The reaction towers were equipped with a heat transfer medium jacket on the outside. In each reaction tower, the heat transfer medium jacket was divided into three sections in the vertical direction, allowing for precise control of the temperature in the vertical direction of the reaction tower. The reaction towers were connected by piping with an insulating jacket.

2) Catalyst composition: Zn-Cr catalyst (manufactured by JGC Catalysts and Chemicals Co., Ltd.)
Diameter: 3.2 mm, length: 3.2 mm, cross-sectional shape: circular; Average crushing strength: 405 to 423 N/particle; Specific surface area: 41 to 44 m ² /g
Pore volume: 0.23 to 0.26 mL/g
・Catalyst charge amount: Approximately 3,200 to 3,400 kg per reactor
3) Raw materials
・Unsaturated fatty acid alkyl esters; palm oil-derived oleic acid methyl ester, methanol

4) 20 to 22 t/day of palm oil-derived methyl oleate as the raw material was supplied to the first reactor at a rate of 2 to 2.5 t/day of methanol. Hydrogen gas adjusted to 17.9 MPa using a compressor was also supplied to the first reactor. The pressure was nearly constant up to the fourth reactor. The hydrogen gas flow rate was 12.3 Nm ³ /h. The inlet temperature of the first reactor was 239.5°C, and the outlet temperature of the first reactor was 245.0°C. The raw material was heated in the first reactor. The raw material was heated by circulating a heat transfer medium through the heat transfer medium jacket in the first reactor. The inlet temperature of the second reactor was 268.9°C, and the outlet temperature of the first reactor was 293.8°C. The temperature in the second reactor rose due to the heat of reaction associated with the reduction reaction of the ester. The inlet temperature of the third reaction tower was 273.3°C, and the outlet temperature of the third reaction tower was 275.2°C. The inlet temperature of the fourth reaction tower was 263.8°C, and the outlet temperature of the fourth reaction tower was 261.2°C. The temperature was almost constant throughout the third and fourth reaction towers. The reaction time was 10 hours. The ketone value of the sample after the unsaturated reduction step was 6.0 to 6.7. After the unsaturated reduction step, a distillation step was carried out, and after methanol and the initial fraction were distilled off, the product unsaturated alcohol and pitch were separated in the main fraction column. The yield after distillation was 85 to 90%.

The embodiments disclosed herein are illustrative in all respects and should not be considered limiting in any way. The scope of the present invention is defined by the claims, and it is intended to include all modifications that are equivalent to and within the scope of the claims.

1 Manufacturing equipment, 11 First reaction tower, 12 Second reaction tower, 13 Third reaction tower, 14 Fourth reaction tower, 21 Raw material tank, 22 Hydrogen tank, 23 Transesterification catalyst, 31 Gas-liquid separator, 32 First distillation apparatus, 33 Second distillation apparatus, 34 Product tank, 35 Pitch tank, 41, 42, 43, 44, 45, 46, 47, 51, 52 Piping, 71 Main body, 72, 73 Cover, 74, 75, 76 Jacket, 77, 78, 79 Valve, 81, 82, 84, 85 Fluid inlet/outlet, 83 Pressure gauge insertion port, 91 Catalyst.

Claims (6)

A method for producing an unsaturated alcohol by reducing an unsaturated fatty acid alkyl ester in the presence of a catalyst, comprising:
a step of charging an unsaturated fatty acid alkyl ester (wherein the alkyl ester has 1 to 4 alkyl carbon atoms) and an aliphatic alcohol having 1 to 4 carbon atoms into a reaction column;
supplying hydrogen to the reaction column and obtaining an unsaturated alcohol by a reduction reaction;
Including,
the reaction towers include a first reaction tower , a second reaction tower, a third reaction tower, and a fourth reaction tower;
the first reaction tower, the second reaction tower, the third reaction tower, and the fourth reaction tower are connected to each other in this order;
each of the first reaction tower, the second reaction tower, the third reaction tower, and the fourth reaction tower is a fixed-bed reaction tower packed with a granular zinc-based solid catalyst;
In the first reaction tower and the third reaction tower, the unsaturated fatty acid alkyl ester, the aliphatic alcohol, and the hydrogen gas flow in parallel downward;
The second reaction tower and the fourth reaction tower are configured so that the unsaturated fatty acid alkyl ester, the aliphatic alcohol, and the hydrogen gas flow upward in parallel.
A method for producing unsaturated alcohols. The unsaturated fatty acid alkyl ester is an unsaturated fatty acid alkyl ester derived from an animal or plant and having an acid value of 0 or more and 10 or less,
The aliphatic alcohol having 1 to 4 carbon atoms is methanol.
The method for producing an unsaturated alcohol according to claim 1. The amount of the aliphatic alcohol charged relative to the unsaturated fatty acid alkyl ester is 8 parts by mass or more and 15 parts by mass or less.
The method for producing the unsaturated alcohol according to claim 1 or 2. the step of obtaining an unsaturated alcohol by the reduction reaction is carried out so that the reaction product obtained through a sampling line disposed downstream of the outlet end of the fourth reaction tower has a saturation value (SV) of 4.0 to 7.0;
A step of distilling the resulting reaction product is then carried out.
The method for producing the unsaturated alcohol according to claim 1 or 2. The zinc-based solid catalyst is a cylindrical solid catalyst having a diameter of 3 to 5 mm and a height of 3 to 5 mm,
each of the first reaction tower, the second reaction tower, the third reaction tower, and the fourth reaction tower comprises a cylindrical reaction chamber having an inner diameter of 0.45 to 0.55 m and a height of 11 to 13 m;
The supply rate of hydrogen gas to the first reaction tower is 3 to 21 m ³ /h.
The method for producing the unsaturated alcohol according to claim 1 or 2. the temperature difference between the inlet end temperature of the first reaction tower and the outlet end temperature of the second reaction tower is 20 to 60°C;
The temperature difference between the inlet end temperature of the third reaction tower and the outlet end temperature of the fourth reaction tower is 0 to 20°C.
The method for producing the unsaturated alcohol according to claim 1 or 2.