Method for producing unsaturated alcohol

Abstract

To provide a method for the continuous production of an unsaturated alcohol from an unsaturated fatty acid alkyl ester as the raw material, the method enabling reduction of by-product formation and applicability on an industrial scale.SOLUTION: A method for producing an unsaturated alcohol by performing reduction of an unsaturated fatty acid alkyl ester in the presence of a catalyst, comprises a step of charging an unsaturated fatty acid alkyl ester (where the alkyl group of the alkyl ester has 1 to 4 carbon atoms) and an aliphatic alcohol having 1 to 4 carbon atoms into a reaction column, and a step of supplying hydrogen to the reaction column to obtain the unsaturated alcohol through a reduction reaction.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for producing an unsaturated alcohol. [Background technology]

[0002] A well-known method for producing unsaturated alcohols is to obtain unsaturated alcohols from 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 obtain an unsaturated alcohol. For example, Patent Document 1 discloses a method for producing unsaturated alcohols, which is characterized by using a catalyst having a specific range of strength and reacting an unsaturated fatty acid alkyl ester with hydrogen gas under conditions in which a specific range of amount of liquid phase is maintained on the surface of the catalyst.

[0003] Patent Document 2 discloses a method for producing liquid vegetable unsaturated alcohols, in which a zinc-based catalyst having a copper content of 30 ppm or less is used as the catalyst to carry out a reduction reaction using a fixed-bed continuous reaction system under high temperature and pressure. The working examples shown in Patent Document 2 describe a reduction reaction carried out 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 having 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. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] WO2004 / 048297 publication [Patent Document 2] WO2003 / 089393 publication Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide a method for continuously producing unsaturated alcohols using unsaturated fatty acid alkyl esters as a raw material, which method suppresses the generation of by-products, is applicable on an industrial scale, and allows for the continuous production of unsaturated alcohols. [Means for solving the problem]

[0006] The production method according to the present disclosure 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 column" and "supplying hydrogen to the reaction column and obtaining an unsaturated alcohol by a reduction reaction." [Effects of the Invention]

[0007] According to the production method of the present disclosure, in the production of unsaturated alcohols using unsaturated fatty acid alkyl esters as raw materials, the generation of by-products is suppressed, and a method for continuously producing unsaturated alcohols that can be applied on an industrial scale is provided. [Brief explanation of the drawings]

[0008] [Figure 1] 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. [Figure 2] 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. [Figure 3] 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. DETAILED DESCRIPTION OF THE INVENTION

[0009] [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, "A to B" representing a numerical range means "A or more and B or less."

[0010] The production method according to the present disclosure 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 column, and supplying hydrogen to the reaction column and obtaining the unsaturated alcohol by a reduction reaction.

[0011] 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 for obtaining unsaturated alcohols with good liquid retention and low cloud points have also been investigated. Meanwhile, there is a need for a method that can produce unsaturated alcohols of sufficient quality at a practical cost even when the laboratory scale is expanded to an industrial production scale (e.g., production volume of 10 t / day or more).

[0012] The inventors recognized that impurities (products other than the target product) generated during the process of reducing unsaturated fatty acid alkyl esters are hydrocarbons further generated from the alcohol produced from the esters and saturated alcohols generated 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 aliphatic groups. As a result, they discovered that by adding an aliphatic alcohol having 1 to 4 carbon atoms along with the raw material unsaturated fatty acid alkyl ester, the generation of by-products can be suppressed and unsaturated alcohols of stable quality can be produced with excellent production efficiency. One of the features of the production method disclosed herein is that a commonly used raw material aliphatic alcohol having 1 to 4 carbon atoms is added in addition to the raw material unsaturated fatty acid alkyl ester. The production method disclosed herein does not require special processes or materials and can be implemented industrially without increasing costs.

[0013] Without being bound by theory, it is believed that by charging an aliphatic alcohol having 1 to 4 carbon atoms together with the raw material unsaturated fatty acid alkyl ester, the unsaturated alcohol produced in the reaction system is prevented from being adsorbed back onto the catalyst, thereby preventing side reactions and over-reactions.

[0014] In the 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 or more and 10 or less, and the aliphatic alcohol having 1 to 4 carbon atoms may be methanol.

[0015] In the production method, the amount of the aliphatic 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.

[0016] In the above-described production method, the reaction towers may include a first reaction tower, a second reaction tower, a third reaction tower, and a fourth reaction tower connected to each other 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 the hydrogen gas flow down in parallel, and the second reaction tower and the fourth reaction tower may be configured so that the unsaturated fatty acid alkyl ester, the aliphatic alcohol, and the hydrogen gas flow up in parallel.

[0017] In the production method, the step of obtaining an unsaturated alcohol by the reduction reaction may be carried out so that the reaction product obtained from a sampling line arranged downstream of the outlet end of the fourth reaction tower has a saponification value (SV) of 4.0 to 7.0, and the step of obtaining the unsaturated alcohol may be followed by a step of distilling the obtained reaction product.

[0018] 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, and each of the first reaction tower, the second reaction tower, the third reaction tower, and the fourth reaction tower may 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 may be used.

[0019] In the 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.

[0020] The manufacturing method according to the present disclosure will be described in more detail below. (Raw materials used in the manufacturing process) 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.

[0021] 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.

[0022] The unsaturated fatty acids can be obtained by hydrolyzing fats and oils according to a conventional method. The unsaturated fatty acid alkyl esters can be obtained by esterifying the unsaturated fatty acids obtained by hydrolysis of fats and oils with a lower alcohol (for example, an aliphatic alcohol having 1 to 4 carbon atoms, such as methyl alcohol). Alternatively, they can be obtained by transesterification of vegetable fats and oils with an aliphatic alcohol having 1 to 4 carbon atoms, such as methyl alcohol.

[0023] 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.

[0024] (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.

[0025] (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.

[0026] It is most preferable that the zinc-based catalyst is substantially free of copper. If it contains copper, the copper content is preferably 20 ppm or less, particularly 10 ppm or less. If the copper content is within the above range, the cloud point of the resulting unsaturated alcohol is prevented from becoming too high.

[0027] The zinc-based catalyst may be in the form of fine particles and may be supported on a carrier, such as silica, alumina, silica-alumina, titania, diatomaceous earth, clay, activated carbon, carbon, graphite, zeolite, clays such as montmorillonite, and alkaline earth silicates.

[0028] The carrier-supported zinc-based catalyst is not particularly limited and can be prepared by a conventionally known method such as an impregnation method, a coprecipitation method, etc. Also, a powder or paste containing the zinc-based catalyst and the carrier can be used as a raw material to form a molded catalyst into an appropriate shape using a conventionally known tablet press, granulator, extruder, etc.

[0029] The shape of the catalyst may be a cylinder, a hollow cylinder, a trilobe prism, a quadrilobe prism, a sphere, etc. Two or more catalysts of different shapes may be used in combination. The catalyst is preferably cylindrical.

[0030] The size of the catalyst may be such that its minimum length is approximately 1 to 10 mm, and preferably 3 to 5 mm. Here, "minimum length" refers to, for example, when the catalyst is a spherical catalyst with a diameter of 5 mm, the minimum length is 5 mm in diameter. When 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, when the catalyst is a hollow cylinder, for example, a hollow cylinder with an outer diameter of 3 mm (inner diameter of 2 mm) and a height of 5 mm, the minimum length is an outer diameter of 3 mm.

[0031] Regarding catalyst strength, catalysts with a catalyst strength of 1.0 kg or more per catalyst can be used. The catalyst strength is determined by measuring the minimum crushing strength of 100 catalysts individually, calculating the average value A and standard deviation value (σ), and then using the formula: A-2σ. The catalyst strength may be 1.0 kg or more, and preferably 1.5 to 4.0 kg.

[0032] The minimum crushing strength is measured in accordance with JIS Z-8841-1993, "3.1 Crushing Strength Test Method." The "minimum crushing strength" is 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 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, the crushing strength generally does not differ depending on the direction of compression, so the crushing strength measured in accordance with the above-mentioned JIS method is taken as the minimum crushing strength.

[0033] The catalyst may be used as it is after being packed into the reaction column, or it is preferable to subject it to an activation treatment before being subjected to the reaction. The activation treatment can be carried out by a known method, for example, by passing hydrogen gas through the reaction column packed with the catalyst.

[0034] (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 towers is performed, as one embodiment of the rearrangement, the fourth reaction tower before the rearrangement may be rearranged into the third reaction tower after the rearrangement, and similarly, the third reaction tower may be rearranged into the second reaction tower, the second reaction tower into the first reaction tower, and the first reaction tower into the fourth reaction tower.

[0035] The first reaction tower 11 is connected to a pipe 41, which is a raw material supply line connected to the raw material tank 21, and a pipe 51, which is a hydrogen supply line connected 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. The pipes 41 and 51 are connected to the upper part of the first reaction tower 11. That is, the raw material and hydrogen gas are supplied to the first reaction tower 41 from its upper part. The raw material is a liquid, and the raw material and hydrogen gas flow down and co-currently in the first reaction tower. The first reaction tower 11 is filled with a catalyst 91 (FIG. 3). The lower part of the first reaction tower 11 is connected to a pipe 42, which is a pipe connecting the first reaction tower 11 and the second reaction tower 12. The pipe 42 may be a pipe with an insulating jacket.

[0036] The pipe 42 is connected to the lower part of the second reaction tower 12. A pipe 43, which is a pipe connecting the second reaction tower 12 and the third reaction tower 13, is connected to the upper part 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 upward in parallel inside the second reaction tower 12 and are discharged from the pipe 43.

[0037] The pipe 43 is connected to the upper part of the third reaction tower 13. A pipe 44, which is a pipe connecting the third reaction tower 13 and the fourth reaction tower 14, is connected to the lower part 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 the pipe 44.

[0038] The pipe 44 is connected to the lower part of the fourth reaction tower 14. A pipe 45, which is a pipe connecting the fourth reaction tower 14 and the gas-liquid separator 31, is connected to the upper part 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 in parallel inside the fourth reaction tower 14 and are discharged from the pipe 45. The raw material, unsaturated fatty acid alkyl ester, undergoes ester reduction to form an unsaturated alcohol while moving from the first reaction tower 11 to the fourth reaction tower 14. That is, the first reaction tower 11 to the fourth reaction tower 14 constitute a reduction reaction apparatus, and the gas-liquid separator 31, the first distillation apparatus 32, and the second distillation apparatus 33 can be said to be facilities for separating and purifying the product, unsaturated alcohol, from the obtained reaction mixture.

[0039] The gas-liquid separator 31 is, for example, a high-pressure separator. A pipe 52, which is a return line for returning the hydrogen gas separated from the reaction mixture to the pipe 52, which is a hydrogen supply line, is connected to the gas-liquid separator 31. The gas-liquid separator 31 is connected to the first distillation apparatus 32 via a pipe 46. The first distillation apparatus 32 is an initial distillation column, and low-boiling-point components are distilled off in the first distillation apparatus 32. Although not shown, multiple connections from the pipe 46 to the first distillation apparatus 32 may be provided, spaced apart in the vertical direction. The liquid component (crude unsaturated alcohol containing unreacted raw materials) separated in the gas-liquid separator 31 is transferred to the first distillation apparatus 32 through the pipe 46. A transesterification catalyst is added during this process. The transesterification in the distillation stage will be described later.

[0040] The first distillation apparatus 32 is connected to the second distillation apparatus 33 via a pipe 47. The second distillation apparatus 33 is a so-called main fraction column. The second distillation apparatus 33 is connected to a product tank 34 and a 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 pitch, which is the distillation residue, is recovered in the pitch tank 35 and is reused as part of the reaction raw materials.

[0041] 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 includes a main body 71 having a cylindrical reaction chamber V1 therein, and covers 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 about 0.4 to 0.8 m, and preferably 0.45 to 0.55 m. The height of the reaction tower may be about 10 to 15 m, and preferably 11 to 13 m. The reaction chamber preferably has a ratio (H / D) of height (H(m)) to inner diameter (D(m)) of 10 to 40, and more preferably about 20 to 30. The reaction chamber V1 is filled with a solid catalyst.

[0042] 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 raw material supply piping is connected, and an insertion port 83 for a pressure gauge. The lid 73 is provided with fluid inlets and outlets 84 and 85 to which 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. The jackets 74, 75, and 76 are provided with valves 77, 78, and 79, respectively, and the amount of heat transfer medium circulating can be adjusted by adjusting the opening of the valves 77, 78, and 79.

[0043] 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 shows 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 of 13.2 mm and a height h of 13.2 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 V1. 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.

[0044] As described above, in the second and fourth reaction towers, the reaction raw materials, unsaturated fatty acid alkyl ester and hydrogen gas, flow upward in parallel and come into contact with the catalyst 91, causing the reduction reaction of the ester. In Figure 3, the flow of the reaction liquid (including unsaturated fatty acid alkyl ester, reaction product, and alcohol) is indicated by the open arrows. Hydrogen gas exists in the reaction liquid as bubbles and rises together with the reaction liquid, as indicated by the black arrows.

[0045] (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.

[0046] The charging step is a step of charging a raw material and an alcohol into a reaction tower packed with a catalyst. The amount of the raw material unsaturated fatty acid alkyl ester charged 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. When the amount is within this range, the addition of the aliphatic alcohol has the effect of 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 the alcohol, hydrogen gas is introduced into the reaction tower. The hydrogen gas is pre-pressurized by a compressor and introduced into the reaction tower. The pressure of the hydrogen gas may be approximately 17 to 20 MPa.

[0047] The reduction reaction step is carried out following the charging step. The reduction reaction step is also called hydrogenation. In the reduction reaction step, unsaturated fatty acid alkyl esters, alcohols, 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 esters are reduced to produce unsaturated alcohols.

[0048] The temperature of the first reaction tower may be adjusted to 230 to 250°C. The temperature difference between the inlet end temperature and the outlet end temperature of the first reaction tower may be 10 to 20°C. That is, the raw material is heated in the first reaction tower. The pressure of the first reaction tower may be 17 to 20 MPa. The flow rate of the raw material in the first reaction tower may be 400 kg / h to 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. The pressure and flow rate in the reaction towers may be approximately constant (with a fluctuation range of ±10% or less) from the first reaction tower to the fourth reaction tower.

[0049] The first and second reaction towers are connected via a pipe, and the raw material mixture withdrawn from the bottom of the first reaction tower is introduced into the second reaction tower from the bottom of the second reaction tower. 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 to 300°C, or may be adjusted to 270 to 280°C. The temperature difference between the inlet end temperature and the outlet end temperature of the second reaction tower may be 20 to 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 is 20 to 60°C higher than the temperature at the inlet end of the first reaction tower.

[0050] The raw material mixture is taken out 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 an external power source such as a pump is not required, but the raw material mixture may be transferred by a pump. The same applies to the movement from the second reaction tower to the third reaction tower and from the third reaction tower to the fourth reaction tower.

[0051] 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. In the third reaction tower, the raw material mixture flows down in parallel and contacts the catalyst packed in the reaction tower. The temperature of the third reaction tower may be adjusted to 270 to 280°C. The temperature difference between the inlet end temperature and the outlet end temperature of the third reaction tower may be 0 to 10°C. The raw material mixture is withdrawn from the bottom of the third reaction tower.

[0052] 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. In the fourth reaction tower, the raw material mixture flows upward in parallel and contacts the catalyst packed in the reaction tower. The temperature of the fourth reaction tower may be adjusted to 260 to 280°C. The temperature difference between the inlet end temperature and the outlet end temperature of the fourth reaction tower may be 0 to 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 (for example, with a fluctuation range of ±10% or less). The temperature change in the third and fourth reaction towers is small relative to the temperature change (temperature rise) in the first and second reaction towers. 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 10°C.

[0053] The progress of the reduction (hydrogenation) reaction can be confirmed, for example, by SV (saponification value). These can be used as process control values. For example, the reduction reaction step is preferably carried out so that the saponification 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.

[0054] The reaction time of the reduction reaction (the time from when the raw material mixture is charged into the first reaction tower until it reaches the outlet end of the fourth reaction tower) may be about 5 to 15 hours, and preferably about 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.

[0055] The raw material mixture that has undergone the reduction reaction step contains an unsaturated alcohol, which is the reaction product. It is preferable to carry out distillation following the reduction reaction in order to purify the unsaturated alcohol product. 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). The 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 the contamination of the unsaturated fatty acid alkyl ester, which is the unreacted raw material, with the target unsaturated alcohol can be suppressed.

[0056] 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 separated from each other in the vertical direction. The low-boiling components to be 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 used again as a reaction raw material.

[0057] The method for producing unsaturated alcohols according to the present disclosure may further include a slight hydrogenation step. Slight hydrogenation refers to a step 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 usually 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 obtained by adding molybdenum, tungsten, magnesium, barium, aluminum, calcium, zirconium, manganese, and oxides thereof to these.

[0058] When slight hydrogenation is carried out, the reaction method is not particularly limited, and methods such as a batch suspension bed reaction, a continuous suspension bed reaction, and a fixed bed continuous reaction can be used. In the case of a batch or continuous suspension bed reaction, the reaction temperature may be about 100 to 200°C. The reaction pressure may be about 1 MPa to atmospheric pressure. When the slight hydrogenation reaction is carried out by a fixed bed continuous reaction, it is preferable to pack a formed catalyst into a reaction tower, activate the catalyst, and then carry out the reaction by flowing the unsaturated alcohol as raw materials and hydrogen in a downward or upward cocurrent manner. The reaction temperature may be about 50 to 150°C. The reaction pressure may be about 1 MPa to atmospheric pressure.

[0059] 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 the deodorization method, a method known as a method for deodorizing unsaturated alcohols and the like can be used. Examples of such known methods include 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.

[0060] When steam deodorization is performed, deodorization can be carried out by blowing steam into the unsaturated alcohol under conditions of a temperature of about 100 to 200°C and a pressure of about 0.1 to 70 kPa. The amount of steam blown in can be, for example, about 0.1 to 20% by mass, converted to the mass of water, relative to the unsaturated alcohol.

[0061] [Example 1] 1) Equipment The manufacturing 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 measuring 50 cm in diameter and 12 m in height. The reaction chambers were filled with 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 vertically, allowing for precise control of the temperature in the vertical direction of the reaction tower. The reaction towers were connected by piping with heat-insulating jackets.

[0062] 2) Catalyst Composition: Zn-Cr catalyst (manufactured by JGC Catalysts and Chemicals Co., Ltd.) Diameter 3.2mm, length 3.2mm, cross-sectional shape: circular Average crushing strength: 405-423N / grain ·Specific surface area: 41~44m 2 / g Pore ​​volume: 0.23~0.26mL / g Catalyst charge amount: Approximately 3200 to 3400 kg per reactor 3) Raw materials · Unsaturated fatty acid alkyl ester; palm oil-derived oleic acid methyl ester ·methanol

[0063] 4) Operation The raw material, palm oil-derived oleic acid methyl ester, was fed to the first reactor at a rate of 20-22 t / day and 2-2.5 t / day of methanol. Hydrogen gas adjusted to 17.9 MPa using a compressor was also fed to the first reactor. The pressure was almost constant up to the fourth reactor. The hydrogen gas flow rate was 12.3 Nm 3The flow rate was 1 / 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. In the first reactor, the raw material was heated by circulating a heat transfer medium through the heat transfer medium jacket. The inlet temperature of the second reactor was 268.9°C, and the outlet temperature of the first reactor was 293.8°C. In the second reactor, the temperature rose due to the heat of reaction associated with the reduction reaction of the ester. The inlet temperature of the third reactor was 273.3°C, and the outlet temperature of the third reactor was 275.2°C. The inlet temperature of the fourth reactor was 263.8°C, and the outlet temperature of the fourth reactor was 261.2°C. The temperature remained nearly constant throughout the third and fourth reactors. The reaction time was 10 hours. The ketone value of the sample after the unsaturation reduction step was 6.0 to 6.7. After the unsaturated reduction step, a distillation step was carried out, and after the methanol and initial fraction were distilled off, the product unsaturated alcohol and pitch were separated in the main distillation column. The yield after distillation was 85-90%.

[0064] The present invention is intended to cover a wide range of applications, including those related to the present invention, including those related to the present invention. [Explanation of symbols]

[0065] 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

1. 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.

2. 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.

3. 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.

4. 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.

5. 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 amount of hydrogen gas in the first reaction tower is 3 to 21 m ３ / h, The method for producing the unsaturated alcohol according to claim 1 or 2.

6. 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.

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