Method for producing fatty acid alkyl ester and production system

Abstract

To provide a novel method for producing a fatty acid alkyl ester for biodiesel fuel that allows efficient and low-cost production within a short period of time.SOLUTION: A method for producing a fatty acid alkyl ester, comprising performing transesterification of a feed oil with a lower alkyl alcohol composed of methanol and / or ethanol in the presence of a catalyst within a homogeneous phase system with addition of an organic solvent selected from the group consisting of methyl ethyl ketone, diethyl ketone, and a mixture thereof.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a novel method and system for producing fatty acid alkyl esters for use in biodiesel fuels efficiently and at low cost in a short period of time. [Background technology]

[0002] In recent years, there has been a movement to introduce biodiesel fuels made from plant-derived oils such as palm oil and waste cooking oil, from the perspectives of preventing global warming, recycling resources, and taking environmental measures.

[0003] Biodiesel fuel is produced by transesterification of monoglycerides, diglycerides, or triglycerides, which are the main components of fats and oils, with lower alkyl alcohols such as methanol or ethanol. For example, Patent Document 1 describes a method of transesterifying waste cooking oil using methanol in the presence of sodium hydroxide. Related prior art documents include Patent Documents 2 to 4. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 7-197047 [Patent Document 2] Japanese Patent Application Laid-Open No. 2004-156022 [Patent Document 3] Japanese Patent Application Laid-Open No. 2009-40979 [Patent Document 4] International Publication No. 2010 / 106985 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the method described in Patent Document 1 requires that the transesterification reaction be carried out under heating with stirring for about a day, which increases the production cost. Furthermore, the use of sodium hydroxide results in the production of fatty acid sodium salts, i.e., soap, as a side reaction. Once soap is produced, it takes about a day to separate the biodiesel fuel from the by-product glycerin. Furthermore, once soap is produced, the glycerin and soap, which are originally commercially valuable, must be disposed of. This creates new environmental problems.

[0006] To solve these problems, the present inventors proposed a method in which the transesterification reaction is carried out while stirring with ultrasound, and the biodiesel fuel and glycerin are separated using ultrasound (see, for example, Patent Document 2). This method does not require heating for the transesterification reaction, and the reaction time is shorter than in conventional methods. In addition, the reaction proceeds even with a small amount of added alkali catalyst, and soap is less likely to be produced.

[0007] However, this method requires equipment for ultrasonic agitation and separation, which increases production costs. Furthermore, although the separation time between biodiesel fuel and glycerin is shorter than with previous production methods, soap is still produced, which makes it difficult to obtain high-quality glycerin.

[0008] In order to solve these problems, attempts have been made to carry out transesterification in a homogeneous phase system by adding a solvent to the reaction system. For example, Patent Document 3 describes a method of improving the reaction rate of the transesterification reaction by adding dimethyl ether to the reaction system.

[0009] However, when dimethyl ether is added to the reaction system, the unreacted lower alkyl alcohol becomes more soluble in glycerin, inhibiting the progress of the transesterification reaction and resulting in a low yield of fatty acid alkyl esters. Furthermore, because the lower alkyl alcohol dissolves in both the fatty acid alkyl ester phase and the glycerin phase, separation of the two phases takes time, and soap is produced during the separation process. Furthermore, dimethyl ether has an extremely low boiling point of -23.6°C, so special equipment such as a pressure-resistant cell is required to keep it in the reaction system.

[0010] Furthermore, Patent Document 4 describes a method of adding acetone or isopropanol to a homogeneous phase transesterification reaction. This method can increase the yield of fatty acid alkyl esters and also allows separation of the fatty acid alkyl ester phase and the glycerin phase in a short time. Furthermore, since acetone and isopropanol are liquid at room temperature, they have the advantage of not requiring special equipment like dimethyl ether.

[0011] However, because acetone has a low boiling point, when biodiesel fuel is produced using this method in hot regions, for example, the amount of acetone evaporated during the transesterification reaction increases, resulting in problems such as reduced biodiesel fuel production efficiency, reduced acetone recovery, and increased production costs. There are also concerns about the adverse effects of evaporated acetone on the health of workers.

[0012] The present invention provides a novel industrially advantageous method for producing fatty acid alkyl esters by transesterification in a homogeneous phase, which can solve the above-mentioned problems. [Means for solving the problem]

[0013] In order to solve the above problems, the present inventors have investigated solvents to be used in transesterification reactions in homogeneous phases and have completed the present invention.

[0014] The method for producing fatty acid alkyl esters of the present invention is a method for producing fatty acid alkyl esters by subjecting a feedstock oil to a transesterification reaction with a lower alkyl alcohol consisting of methanol and / or ethanol in the presence of a catalyst, and the transesterification reaction is carried out in a homogeneous phase system by adding an organic solvent selected from methyl ethyl ketone (IUPAC name: 2-butanone), diethyl ketone (IUPAC name: 3-pentanone), and mixtures thereof. [Effects of the Invention]

[0015] In the present invention, an organic solvent selected from methyl ethyl ketone, diethyl ketone, and mixtures thereof is used to produce fatty acid alkyl esters by transesterification in a homogeneous phase. This method results in a high yield of fatty acid alkyl esters. Furthermore, the fatty acid alkyl ester phase and the glycerin phase can be separated in a short time, allowing for the recovery of nearly pure glycerin. Furthermore, these organic solvents used in the present invention are liquid at room temperature and have boiling points above 75°C. They remain in the reaction system at room temperature, resulting in minimal volatilization during the transesterification reaction. Furthermore, since the boiling points of these organic solvents are similar to or lower than the boiling point of water, the recovery of these organic solvents does not require significant heating energy. Furthermore, cooling can be performed using tap water, for example. Therefore, the recovery of the organic solvent is easy and efficient, and no special equipment is required. This is industrially advantageous in terms of production cost. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a graph showing the yield of fatty acid methyl esters from the start of the reaction up to 1 hour when methyl ethyl ketone, diethyl ketone, acetone, isopropanol, or tetrahydrofuran is used as a solvent, or when no solvent is used. DETAILED DESCRIPTION OF THE INVENTION

[0017] The methyl ethyl ketone and diethyl ketone used in the present invention have a density of 830 kg / m at 25°C. 3 On the other hand, the density of glycerin is 1260 kg / m 3 The density of the resulting fatty acid alkyl ester is 1 kg / m 3 Furthermore, since methyl ethyl ketone and diethyl ketone are miscible with the fatty acid alkyl ester phase along with lower alkyl alcohols, when methyl ethyl ketone or diethyl ketone is used as a solvent, the density of the fatty acid alkyl ester phase is close to 1 kg / m 3 The resulting particles become smaller, and the fatty acid alkyl ester phase and the glycerin phase are rapidly separated. Furthermore, by using these organic solvents, the unreacted lower alkyl alcohol does not dissolve in the by-produced glycerin, so the yield of the fatty acid alkyl ester produced can be increased. Furthermore, by using these solvents, even if a small amount of water is contained in the reaction system, the transesterification reaction can be carried out without removing water from the reaction system.

[0018] The raw material oil is preferably a vegetable oil.

[0019] The catalyst may be any of an alkaline catalyst, an acid catalyst, an enzyme, and a solid catalyst made of an ion exchange resin, with the alkaline catalyst being preferred.

[0020] The transesterification reaction is preferably carried out by a mixing step in which a solution containing a raw material oil and an organic solvent is mixed with a solution containing a lower alkyl alcohol and a catalyst. By mixing in this manner, a uniformly mixed reaction system can be easily obtained. Furthermore, the amounts of the lower alkyl alcohol and the catalyst used can be reduced.

[0021] Furthermore, the mixing of the solutions may be carried out by adding the solution containing the lower alkyl alcohol and the catalyst in multiple stages. When the solution containing the lower alkyl alcohol and the catalyst is added all at once, the unreacted lower alkyl alcohol dissolves in the produced glycerin. When the solution containing the lower alkyl alcohol and the catalyst is added in multiple stages, the added lower alkyl alcohol is quickly used in the transesterification reaction. This prevents the lower alkyl alcohol from dissolving in the produced glycerin. As a result, the yield of fatty acid alkyl esters can be increased.

[0022] It is preferable to include a separation step in which the reaction solution is allowed to stand after the transesterification reaction in the mixing step, and separated into a fatty acid alkyl ester phase containing a fatty acid alkyl ester, a lower alkyl alcohol, and an organic solvent, and a glycerin phase. In the production method of the present invention, when the feedstock oil, the lower alkyl alcohol, the organic solvent, and the catalyst are uniformly stirred, the transesterification reaction occurs rapidly. When the solution after this reaction is allowed to stand, it quickly separates into a fatty acid alkyl ester phase and a glycerin phase.

[0023] The production method of the present invention preferably includes a recovery step of recovering a lower alkyl alcohol and an organic solvent from the fatty acid alkyl ester phase. In the production method of the present invention, the fatty acid alkyl ester phase contains a lower alkyl alcohol and an organic solvent. The boiling points of the lower alkyl alcohol and the organic solvent are lower than the boiling point of the fatty acid alkyl ester. Therefore, the lower alkyl alcohol and the organic solvent can be easily recovered simultaneously by subjecting the fatty acid alkyl ester phase to a reduced pressure treatment or the like.

[0024] The recovered lower alkyl alcohol and organic solvent can be added to a solution containing the raw material oil and the organic solvent, which is efficient because the unreacted lower alkyl alcohol can be reused in the transesterification reaction.

[0025] The fatty acid alkyl ester production system of the present invention comprises a fatty acid alkyl ester production means for carrying out an ester exchange reaction between a raw material oil and a lower alkyl alcohol in a homogeneous phase system to which an organic solvent has been added in the presence of a catalyst to produce a fatty acid alkyl ester, and a separation means for allowing the fatty acid alkyl ester phase containing the produced fatty acid alkyl ester, the organic solvent, and the lower alkyl alcohol to stand and separate from a glycerin phase.

[0026] The method may further include a recovery means for recovering the organic solvent and the lower alkyl alcohol from the fatty acid alkyl ester phase separated by the separation means. Furthermore, the method may further include a return means for returning the recovered organic solvent and the lower alkyl alcohol to the feedstock oil. Here, the feedstock oil includes a solution of the feedstock oil and the organic solvent.

[0027] The present invention will be described in detail below. The method for producing a fatty acid alkyl ester of the present invention is a method for producing a fatty acid alkyl ester by subjecting a feedstock oil to a transesterification reaction with a lower alkyl alcohol consisting of methanol and / or ethanol in the presence of a catalyst, and the transesterification reaction is carried out in a homogeneous phase system by adding an organic solvent selected from methyl ethyl ketone, diethyl ketone, and a mixture thereof to the reaction system.

[0028] [catalyst] The catalyst that can be used in the present invention includes catalysts that are commonly used in transesterification reactions. Examples include alkali catalysts such as sodium hydroxide and potassium hydroxide, acid catalysts such as hydrochloric acid, sulfuric acid, and hydrofluoric acid, enzymes such as lipase, inorganic substances such as calcium oxide, and solid catalysts such as ion exchange resins such as cation exchange resins and anion exchange resins. From the viewpoint of production cost, an alkali catalyst or an acid catalyst is preferably used. It is more preferable to use an alkali catalyst. Furthermore, a single catalyst may be used, or multiple catalysts may be used in combination. The alkali catalyst or acid catalyst can be prepared as an aqueous solution according to a commonly known method, but it is preferable to use it as a solution of the lower alkyl alcohol used in the transesterification reaction.

[0029] The use of an alkaline catalyst is preferable because it is less expensive than a solid catalyst and the transesterification reaction can be carried out in a short time. However, if the feedstock oil contains free fatty acids, soap may be produced.

[0030] On the other hand, when an acid catalyst is used, the transesterification reaction proceeds without producing soap, even when the feedstock oil contains a high concentration of free fatty acids. However, the transesterification reaction proceeds more slowly than when an alkali catalyst is used. Therefore, the catalyst should be selected depending on the type of feedstock oil.

[0031] The amount of catalyst used in the method for producing fatty acid alkyl esters of the present invention may be adjusted appropriately depending on the type of catalyst used, the amount of fatty acids and / or fats and oils in the feedstock, the scale of the reaction system, and the like. Specifically, an amount that allows the transesterification reaction to proceed satisfactorily without decreasing the rate of transesterification and that allows the catalyst to be separated in the refining step may be appropriately determined. For example, when an alkali catalyst is used, the amount of alkali catalyst used is 0.03 to 1.2 mass % of the feedstock, preferably 0.1 to 1.0 mass %, and more preferably 0.3 to 0.8 mass %. The production method of the present invention can carry out a sufficient amount of transesterification reaction in a short time, even using such an extremely small amount of catalyst.

[0032] [Raw oil] The raw oil used in the present invention is not particularly limited as long as it contains fats and oils, and may contain fatty acids. The fats and oils are not particularly limited and may be triglycerides, diglycerides, monoglycerides, etc., but triglycerides are preferred. The constituent fatty acids of monoglycerides, diglycerides, and triglycerides may be saturated fatty acids, unsaturated fatty acids, branched fatty acids, hydroxyl fatty acids, etc., and may include one or more fatty acids selected from C12 to C28 fatty acids. Examples include lauric acid, myristic acid, pentadecylic acid, palmitic acid, palmitoyl acid, stearic acid, linoleic acid, linolenic acid, and arachidonic acid. The fats and oils mentioned above include fatty oils that are liquid at room temperature and fats that are solid at room temperature. Specific examples of fatty oils that are liquid at room temperature include vegetable oils (e.g., soybean oil, sesame oil, rapeseed oil, rice oil, bran oil, camellia oil, safflower oil, palm oil, palm shell oil, coconut oil, cottonseed oil, sunflower oil, perilla oil, olive oil, peanut oil, almond oil, avocado oil, hazelnut oil, walnut oil, grapeseed oil, etc.) and animal oils (fish oil, cod liver oil, shark oil, etc.). Examples of fats that are solid at room temperature include lard (pork fat), beef tallow, chicken oil, schmaltz, shortening, butter, margarine, cocoa butter, and hardened oil. In addition, non-edible vegetable oils such as jatropha and syringa can also be used as raw material oils. Furthermore, waste oils from these vegetable oils can also be used. These raw oils may be used alone or in combination. Of the raw oils, fatty oils that are liquid at room temperature are preferred. Particularly preferred are vegetable oils that do not contain sulfur (i.e., do not require a sulfur removal step).

[0033] In addition to the liquid feedstock oils described above, solid, gel, muddy, and other feedstock oils, as well as low-quality feedstock oils such as oils and fats containing water and free fatty acids, can also be used in the production method of the present invention by subjecting them to appropriate pretreatment. Examples of low-quality feedstock oils include waste oils and fats (including water-containing waste oils and fats) and trap grease (mud-like oil-containing material floating on the surface of wastewater in an interceptor installed before public sewerage discharge).

[0034] Furthermore, when the feedstock oil is one containing a large amount of free saturated fatty acids (e.g., stearic acid, palmitic acid, etc.) (for example, waste fish oil (e.g., catfish oil)), these free saturated fatty acids exist in a solid state and may not react even if used as is in the production method of the present invention, remaining in the fatty acid lower alkyl ester phase. Therefore, the feedstock oil can be dissolved in advance in the organic solvent used in the present invention, and then, if necessary, the free saturated fatty acids can be separated and removed by filtration or the like. Alternatively, pretreatment with a lower alkyl alcohol in the presence of an acid catalyst may be carried out, as described below.

[0035] Similarly, when the raw material oil contains solid matter, the solid matter can be removed by dissolving it in the organic solvent used in the production method of the present invention, and then filtering or the like.

[0036] Furthermore, some raw oils contain water-soluble reaction-interfering substances (e.g., saponin) that interfere with the implementation of the production method of the present invention. For example, jatropha oil is an example of a raw oil containing saponin. When using a raw oil containing water-soluble reaction-interfering substances, the water-soluble reaction-interfering substances can be removed in advance before using the production method of the present invention. Specifically, the raw oil is washed with warm water to remove the water-soluble reaction-interfering substances in advance. The production method of the present invention can also be implemented using a raw oil containing a small amount of water.

[0037] Furthermore, in the production method of the present invention, raw material oils that are not liquid (for example, waste oils and fats that have been gelled or solidified by a fatty acid-based solidifying agent) can also be used by dissolving them in an amount of organic solvent that can dissolve them.

[0038] [Lower alkyl alcohol] The lower alkyl alcohol that can be used in the present invention includes either methanol or ethanol, or a mixture of the two in an appropriate ratio. The transesterification reaction proceeds even when the amount of lower alkyl alcohol used is at least. However, if the amount is too small, not only does the transesterification reaction rate decrease, but the reaction does not proceed sufficiently. On the other hand, in the present invention, even if a certain amount of lower alkyl alcohol is used, the unreacted alcohol can be easily separated and reused. The amount of lower alkyl alcohol added can be 3 to 10 molar amounts, preferably 3 to 8 molar amounts, more preferably 3 to 7 molar amounts, and even more preferably 4 to 6 molar amounts, per 1 molar amount of feedstock oil.

[0039] [Organic solvents] The organic solvent used in the present invention is an organic solvent selected from methyl ethyl ketone, diethyl ketone, and mixtures thereof.

[0040] Methyl ethyl ketone, diethyl ketone, and mixtures thereof are organic solvents that are liquid at room temperature. As a result, in the method for producing a fatty acid alkyl ester of the present invention, transesterification can be carried out without special temperature control, and the reaction does not require a special reaction vessel or the like.

[0041] Furthermore, methyl ethyl ketone and diethyl ketone are organic solvents that are miscible with fatty acid alkyl esters and lower alkyl alcohols but are insoluble in glycerin, making it possible to easily separate the fatty acid alkyl ester phase from the glycerin phase.

[0042] Furthermore, methyl ethyl ketone, diethyl ketone, and mixtures thereof tend to dissolve raw oils (particularly vegetable oils) and form homogeneous phase systems.

[0043] In the production method of the present invention, the amount of organic solvent added may be 10% by mass or more relative to the feedstock oil. If the amount added is less than 10% by mass, the effect of adding the organic solvent will not be sufficient. As mentioned above, when using a feedstock oil that is poorly soluble in organic solvents, a large amount of organic solvent may be used. Usually, the amount added relative to the feedstock oil is 10% by mass to 50% by mass, preferably 15% by mass to 40% by mass, more preferably 18% by mass to 35% by mass, and even more preferably 20% by mass to 30% by mass.

[0044] [Manufacturing method] In the method for producing a fatty acid alkyl ester of the present invention, when a transesterification reaction of a raw material oil with a lower alkyl alcohol is carried out in the presence of a catalyst, the reaction is carried out in a homogeneous phase system by adding an organic solvent selected from methyl ethyl ketone, diethyl ketone, and a mixture thereof to the reaction system.

[0045] When a raw material oil having a low content of free fatty acids is used, fatty acid alkyl esters are produced, for example, as follows.

[0046] (Mixing process) First, a solution containing the feedstock oil and the organic solvent is mixed with a solution containing the lower alkyl alcohol and the catalyst to such an extent that the reaction system becomes a homogeneous phase system.

[0047] The solution containing the feedstock oil and the organic solvent is a mixture of at least the feedstock oil and the organic solvent. The two are dissolved in each other. The mixing ratio of the feedstock oil and the organic solvent is as described above. The solution containing the lower alkyl alcohol and the catalyst is preferably a liquid in which the alkali catalyst is dissolved in the lower alkyl alcohol.

[0048] In the present invention, the mixing step is carried out in a vessel equipped with a stirring means. A solution containing the raw material oil and the organic solvent and a solution containing the lower alkyl alcohol and the catalyst are placed in this vessel and mixed. The stirring means may be manual or may use a device, and any known stirring means may be used.

[0049] As used herein, a homogeneous phase system refers to a system in which the catalyst, organic solvent, fatty acid and / or fat, and lower alkyl alcohol form a single phase. Furthermore, as used herein, "carrying out a transesterification reaction in a homogeneous phase system" refers to a homogeneous phase system at least at the start of the transesterification reaction between a raw material oil such as fat or oil and a lower alkyl alcohol. For example, a case in which the homogeneous phase system becomes a heterogeneous phase system (two-phase system) after the start of the transesterification reaction due to glycerin or the like produced as a by-product by transesterification is also included in the "carrying out a transesterification reaction in a homogeneous phase system" of the present invention.

[0050] Since it is preferable to maintain a homogeneous phase system for a long period of time in the transesterification reaction, the yield of fatty acid alkyl esters can be improved by maintaining a homogeneous phase system for a long period of time by adding lower alkyl alcohol in multiple stages, such as by adding a portion of the required amount of lower alkyl alcohol to the reaction system to carry out the transesterification reaction and then adding the remainder or a portion of the lower alkyl alcohol.

[0051] The mixing step is preferably carried out at room temperature. In the present invention, the reaction proceeds in a short time, and generally, at 10 to 20°C, 80% or more of the reaction proceeds in 2 to 10 minutes. At higher ambient temperatures, the reaction proceeds more quickly. Preferably, the transesterification reaction occurs in a yield close to 100%.

[0052] Furthermore, as described above, the solution containing the lower alkyl alcohol and the catalyst can be added in multiple stages. There is no particular limitation on the number of stages, but since the reaction time is extremely short in the production method of the present invention, two stages are sufficient. An example of adding the solution containing the lower alkyl alcohol and the catalyst in two stages is to mix in the first stage so that 1 mole of triglyceride and 3 moles of lower alkyl alcohol are mixed, and in the second stage so that 1 mole of triglyceride and 2 moles of lower alkyl alcohol are mixed.

[0053] [Separation process] The reaction solution containing the biodiesel fuel obtained by the mixing step separates into a fatty acid alkyl ester phase (upper phase) containing the fatty acid alkyl ester, the lower alkyl alcohol, and the organic solvent, and a glycerin phase (lower phase) when allowed to stand. The organic solvent used in the present invention dissolves the fatty acid alkyl ester and the lower alkyl alcohol, but is poorly soluble in glycerin and has a lower density than the fatty acid alkyl ester, so separation of the fatty acid alkyl ester phase (upper phase) and the glycerin phase (lower phase) proceeds extremely quickly.

[0054] When the organic solvent of the present invention is used, unreacted lower alkyl alcohol does not dissolve in the glycerin phase, so that almost pure glycerin can be recovered.

[0055] [Recovery process] Next, the lower alkyl alcohol and the organic solvent are recovered from the fatty acid alkyl ester phase. The boiling points of the lower alkyl alcohols, methanol and ethanol, are 64.7°C and 78.4°C, respectively. The boiling points of the organic solvents, methyl ethyl ketone and diethyl ketone, are 79.6°C and 101.7°C, respectively. Therefore, the lower alkyl alcohol and the organic solvent can be easily recovered by distilling or vacuum distilling the fatty acid alkyl ester phase. This also allows for easy production of high-purity fatty acid alkyl esters.

[0056] The recovered lower alkyl alcohol and organic solvent can be added to a solution containing the raw material oil and the organic solvent without separation. Since no separation operation is required between the lower alkyl alcohol and the organic solvent, production costs can be reduced. In addition, the organic solvent and unreacted lower alkyl alcohol can be easily reused.

[0057] The resulting fatty acid alkyl esters can be washed with water or hot water and then dehydrated to produce high-quality biodiesel fuel. The by-product glycerin can also be used.

[0058] If the feedstock contains free fatty acids, it is preferable to convert the free fatty acids in the feedstock to lower alkyl esters using a lower alkyl alcohol in the presence of an acid catalyst as a pretreatment before the mixing step. This is because if a feedstock containing free fatty acids is subjected to a mixing step using an alkali catalyst, the free fatty acids may react with the alkali catalyst to produce fatty acid alkali metal salts (soaps). If low-quality waste oils and fats or waste oils and fats containing 40 to 100% free fatty acids are used as the feedstock, it is preferable to perform pretreatment. This pretreatment can be carried out appropriately using conventional methods. [Example]

[0059] The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

[0060] In the following experimental examples, the solution was allowed to stand after each reaction time had elapsed, and the fatty acid methyl ester phase was recovered and the fatty acid methyl ester concentration was measured by high performance liquid chromatography to determine the fatty acid methyl ester yield.

[0061] (Experimental Example 1) A mixture of rapeseed oil and an organic solvent (25% by volume (volume %) relative to the rapeseed oil, approximately 22% to 24% by mass) was mixed with a mixture of potassium hydroxide (1% by mass relative to the rapeseed oil) and methanol (4.5 times the molar amount relative to the rapeseed oil) while stirring. The reaction temperature was 25°C. As a control, no solvent was used, and as examples of the present invention, methyl ethyl ketone and diethyl ketone were used, and as comparative examples, acetone, isopropanol, and tetrahydrofuran (THF) were used. The yield (%) of fatty acid methyl esters was measured for each reaction system after 1 minute, 2 minutes, 5 minutes, 10 minutes, 20 minutes, 40 minutes, and 60 minutes. The results are shown in Table 1 and Figure 1.

[0062] [Table 1]

[0063] Figure 1 is a graph of Table 1. It shows the yield of fatty acid methyl esters when methyl ethyl ketone and diethyl ketone are used as examples of the present invention, and acetone, isopropanol, and tetrahydrofuran are used as comparative examples. In Figure 1, the horizontal axis represents the time (minutes) elapsed from the start of the reaction, and the vertical axis represents the yield (%) of fatty acid methyl esters. ● represents the case of no solvent, ◆ represents the case of acetone, ■ represents the case of methyl ethyl ketone, diethyl ketone, and isopropanol, and ▲ represents the case of tetrahydrofuran (THF). Note that methyl ethyl ketone, diethyl ketone, and isopropanol are represented by a single mark because their points overlap on the graph.

[0064] Table 1 and Figure 1 show that when methyl ethyl ketone and diethyl ketone were used as the organic solvent, fatty acid methyl esters were produced in a high yield of over 85% within 10 minutes of the start of the reaction, and nearly 100% fatty acid methyl esters were produced within 1 hour of the reaction.

[0065] (Experimental Example 2) In the above Experimental Example 1, when methyl ethyl ketone, diethyl ketone, or acetone was used as the organic solvent, the reaction mixture was allowed to stand 60 minutes after the start of the reaction, and the fatty acid alkyl ester phase was separated. The separated fatty acid alkyl ester phase was distilled under reduced pressure to recover the unreacted lower alkyl alcohol and organic solvent. The mixture of unreacted lower alcohol and organic solvent obtained by the reduced pressure distillation was analyzed by gas chromatography (detector: flame ionization detector) to calculate the mixture ratio and determine the recovery rate of the organic solvent. During this process, the temperature of the cooling water during the reduced pressure distillation was changed to examine the difference in the recovery rate of the organic solvent due to differences in cooling temperature. The results are shown in Table 2.

[0066] [Table 2]

[0067] When methyl ethyl ketone and diethyl ketone, which are organic solvents according to the production method of the present invention, were used, the recovery rate was much improved compared to when acetone was used.

[0068] From the above, it was found that when methyl ethyl ketone or diethyl ketone, which are organic solvents according to the production method of the present invention, are used, fatty acid methyl esters can be produced in a short time and in a high yield, and the organic solvent used in the reaction can be recovered with a high recovery rate.

[0069] <Embodiment> Examples of embodiments of the present invention are given below. [1] A method for producing fatty acid alkyl esters by transesterifying a raw material oil with a lower alkyl alcohol consisting of methanol and / or ethanol in the presence of a catalyst, The method for producing a fatty acid alkyl ester, wherein the transesterification reaction is carried out in a homogeneous phase system by adding an organic solvent selected from methyl ethyl ketone, diethyl ketone, and a mixture thereof. [2] The method for producing a fatty acid alkyl ester according to [1], wherein the raw material oil is a vegetable oil. [3] The method for producing a fatty acid alkyl ester according to [1] or [2], wherein the catalyst is any one of an alkali catalyst, an acid catalyst, an enzyme, and a solid catalyst comprising an ion exchange resin. [4] The method for producing a fatty acid alkyl ester according to any one of [1] to [3], wherein the transesterification reaction is carried out by a mixing step of mixing a solution containing a raw material oil and an organic solvent with a solution containing a lower alkyl alcohol and a catalyst. [5] The method for producing a fatty acid alkyl ester according to [4], wherein the mixing step is carried out by multi-stage addition of a solution containing a lower alkyl alcohol and a catalyst. [6] The method for producing a fatty acid alkyl ester according to any one of [1] to [5], further comprising a separation step of allowing the reaction solution to stand after the mixing step and separating it into a fatty acid alkyl ester phase containing the fatty acid alkyl ester, a lower alkyl alcohol, and an organic solvent, and a glycerin phase. [7] The method for producing a fatty acid alkyl ester according to any one of [1] to [6], further comprising a recovery step of recovering a lower alkyl alcohol and an organic solvent from the fatty acid alkyl ester phase. [8] The method for producing a fatty acid alkyl ester according to [7], wherein the recovered lower alkyl alcohol and organic solvent are added to a solution containing a raw material oil and an organic solvent. [9] A means for producing fatty acid alkyl esters by carrying out a transesterification reaction between a raw material oil and a lower alkyl alcohol consisting of methanol and / or ethanol in the presence of a catalyst in a homogeneous phase system to which an organic solvent selected from methyl ethyl ketone, diethyl ketone, and a mixture thereof is added, to produce fatty acid alkyl esters; a separation means for allowing the fatty acid alkyl ester phase containing the produced fatty acid alkyl ester, an organic solvent, and a lower alkyl alcohol to stand and separate from a glycerin phase; A system for producing a fatty acid alkyl ester comprising the compound.

[10] The system for producing a fatty acid alkyl ester according to [9], further comprising a recovery means for recovering an organic solvent and a lower alkyl alcohol from the fatty acid alkyl ester phase separated by the separation means.

[11] The system for producing a fatty acid alkyl ester according to

[10] , further comprising a return means for returning the recovered organic solvent and lower alkyl alcohol to the feedstock oil.

Claims

1. A method for producing fatty acid alkyl esters by transesterifying a feedstock oil with a lower alkyl alcohol comprising methanol and / or ethanol in the presence of a catalyst, The method for producing a fatty acid alkyl ester, wherein the transesterification reaction is carried out in a homogeneous phase system by adding an organic solvent selected from methyl ethyl ketone, diethyl ketone, and a mixture thereof.

2. The method for producing a fatty acid alkyl ester according to claim 1, wherein the raw material oil is a vegetable oil.

3. 2. The method for producing a fatty acid alkyl ester according to claim 1, wherein the catalyst is any one of an alkaline catalyst, an acid catalyst, an enzyme, and a solid catalyst comprising an ion exchange resin.

4. 2. The method for producing a fatty acid alkyl ester according to claim 1, wherein the transesterification reaction is carried out by a mixing step of mixing a solution containing a raw material oil and an organic solvent with a solution containing a lower alkyl alcohol and a catalyst.

5. 5. The method for producing a fatty acid alkyl ester according to claim 4, wherein the mixing step is carried out by adding a solution containing a lower alkyl alcohol and a catalyst in multiple stages.

6. 2. The method for producing a fatty acid alkyl ester according to claim 1, further comprising a separation step of allowing the reaction solution to stand after the mixing step and separating it into a fatty acid alkyl ester phase containing the fatty acid alkyl ester, the lower alkyl alcohol, and the organic solvent, and a glycerin phase.

7. 2. The method for producing a fatty acid alkyl ester according to claim 1, further comprising a recovery step of recovering the lower alkyl alcohol and the organic solvent from the fatty acid alkyl ester phase.

8. 8. The method for producing a fatty acid alkyl ester according to claim 7, wherein the recovered lower alkyl alcohol and organic solvent are added to a solution containing the raw material oil and the organic solvent.

9. a fatty acid alkyl ester producing means for producing fatty acid alkyl esters by carrying out a transesterification reaction between the feedstock oil and a lower alkyl alcohol comprising methanol and / or ethanol in the presence of a catalyst in a homogeneous phase system to which an organic solvent selected from methyl ethyl ketone, diethyl ketone, and a mixture thereof has been added; a separation means for allowing the fatty acid alkyl ester phase containing the produced fatty acid alkyl ester, an organic solvent, and a lower alkyl alcohol to stand and separate from a glycerin phase; A system for producing fatty acid alkyl esters comprising the compound (I).

10. The system for producing a fatty acid alkyl ester according to claim 9, further comprising a recovery means for recovering the organic solvent and the lower alkyl alcohol from the fatty acid alkyl ester phase separated by the separation means.

11. The system for producing a fatty acid alkyl ester according to claim 10, further comprising a return means for returning the recovered organic solvent and lower alkyl alcohol to the feedstock oil.

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