JP2008013758A - Method for producing fatty acid alkyl ester - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for efficiently producing a high-quality fatty acid alkyl ester while effectively removing water. <P>SOLUTION: The method for producing a fatty acid alkyl ester from an oil-and-fat raw material comprises the addition of a second component reactive with water to a reaction system for converting the oil-and-fat raw material to the fatty acid alkyl ester. A high-quality fatty acid alkyl ester can be produced by the method in high efficiency because the second component reacts with water existing in the oil-and-fat raw material and/or water formed in the reaction system, and the material formed by the reaction of the second component with water is used in the reaction to form the fatty acid alkyl ester or is separable from the fatty acid alkyl ester. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing a fatty acid alkyl ester (also referred to as “fatty acid ester”). More specifically, the present invention relates to a method for producing a fatty acid alkyl ester used as a biodiesel fuel.

  Diesel engines (vehicles, ships, machinery, etc.) using light oil as fuel are good in fuel efficiency, but their exhaust gas has an adverse effect on the environment and has recently become a problem. On the other hand, biodiesel fuel (hereinafter referred to as “BDF fuel”) has attracted attention as an alternative fuel for light oil.

  The BDF fuel is a method of transesterifying fatty acid triglyceride (also referred to as “fatty acid glyceride”), which is a main component of vegetable oil, animal oil or waste oil (for example, waste edible oil), with alcohol, It is a fuel comprising a fatty acid alkyl ester obtained by a method of esterifying a fatty acid obtained by hydrolyzing triglyceride or the like with an alcohol. Since the BDF fuel is derived from biomass resources, it is expected to be an alternative to fossil fuels because it does not disturb the global carbon balance and can reduce the environmental burden.

  In addition, as a method for industrially producing fatty acid alkyl esters from fats and oils, there are a supercritical method, an alkali catalyst method, an acid catalyst method, a lipase enzyme method, and the like. The supercritical method is a method of obtaining a fatty acid alkyl ester by performing a transesterification reaction or an esterification reaction using a raw oil or fat as a solvent with a supercritical or subcritical alcohol. Since this method allows the reaction to proceed without a catalyst, a highly pure fatty acid alkyl ester can be obtained.

  The alkali catalyst method is a method in which a fatty acid triglyceride is transesterified in the presence of an alkali metal catalyst in the vicinity of the boiling point of alcohol or at room temperature. Since this method does not need to be performed at high temperature and high pressure, and the catalytic activity in the transesterification reaction is higher than that of the acid catalyst method, the transesterification can be performed relatively easily. Therefore, although the alkali catalyst method requires a catalyst for the reaction, it is important as an industrial method for producing BDF fuel.

  The acid catalyst method is a method in which a fatty acid is esterified in the presence of an acid catalyst. This method has problems such as a decrease in catalytic function due to water in the raw oil and fat and a slow reaction rate. The lipase enzyme method is a method of converting raw material fats and oils to fatty acid alkyl esters by the catalytic action of the lipase enzyme. In this method, control of the amount of methanol added is essential, and there are problems such as a slow reaction rate and high cost.

  For these production methods, the present inventor has proposed a technique for producing a fatty acid alkyl ester under non-catalytic conditions. For example, Patent Document 1 proposes a technique for producing a fatty acid alkyl ester without a catalyst by performing a transesterification reaction and an esterification reaction using a supercritical or subcritical alcohol as a solvent. ing.

  The inventor of the present application has proposed an improved technique of Patent Document 1 in Patent Document 2 and Non-Patent Document 1. More specifically, the first step of obtaining fatty acid and glycerin from the fatty acid triglyceride by hydrolyzing in the presence of a raw oil and fat containing fatty acid triglyceride and water, adding alcohol to the product of the first step, A second process (that is, an esterification process) for converting the fatty acid in the product into a fatty acid alkyl ester under temperature and pressure conditions, and a production method (hereinafter referred to as “two-stage process”) is proposed. ing.

  According to the two-stage method, after the first step, by separating and removing glycerin, the reverse reaction in the second step can be effectively prevented, and by removing water in the fatty acid obtained from the first step, The esterification reaction in the second step can proceed more preferentially. The two-stage method is particularly useful as an industrial process for obtaining fatty acid alkyl esters from raw oils and fats such as waste oil containing water and free fatty acids.

JP 2000-204392 A. PCT International Publication No. WO03 / 106604. Journal of the Japan Institute of Energy, Vol. 84, 413-419 (2005).

However, in order to obtain a high-quality fatty acid alkyl ester, water and the like mixed in the fatty acid alkyl ester must be surely removed, but this method is not easy. In order to offset the equilibrium of the reaction in the esterification direction in the two-stage method, it is necessary to reliably remove water. Moreover, since new water is by-produced with the esterification reaction of free fatty acid and alcohol, it is also necessary to remove this water. In particular, when formic acid (HCOOH) is generated as a free fatty acid, it may be decomposed into carbon monoxide (CO) and water (H ₂ O), so this decomposition reaction also makes complete removal of water more difficult. Yes. Therefore, in order to obtain a high-quality fatty acid alkyl ester, it is important how reliably water can be removed.

  Therefore, the main object of the present invention is to provide a method for producing a fatty acid alkyl ester that can efficiently and easily remove water and can efficiently obtain a high-quality fatty acid alkyl ester.

  The inventor of the present application pays attention to the transesterification reaction and esterification reaction that are frequently used in the production technology of fatty acid alkyl esters, how to efficiently use water present from the beginning of oil and fat raw materials and water generated from these reactions and the like. We have intensively studied whether it can be removed effectively. As a result, the present inventors have found a method for producing a fatty acid alkyl ester that can be used for a wide range of reactions and can efficiently and effectively remove water from a reaction system.

  First, in the present invention, a method for producing a fatty acid alkyl ester from an oil / fat raw material, wherein a second component that reacts with water is added to a reaction system that converts the oil / fat raw material into the fatty acid alkyl ester. The component reacts with water contained in the oil and fat raw material and / or water generated in the reaction system, and the product generated when the second component reacts with the water is used for the reaction to convert to the fatty acid alkyl ester. Alternatively, a method for producing a fatty acid alkyl ester that is separable from the fatty acid alkyl ester is provided.

  According to this production method, the water can be effectively separated from the fatty acid alkyl ester by adding the second component to the reaction system for converting the oil / fat raw material into the fatty acid alkyl ester. Moreover, when the product obtained by reacting the second component with the water is used for conversion to the fatty acid alkyl ester, the fatty acid alkyl ester can be obtained efficiently. Alternatively, when the product is separable from the fatty acid alkyl ester, the water can be effectively separated and removed from the fatty acid alkyl ester.

  Next, the present invention provides a method for producing a fatty acid alkyl ester, wherein the product is an alcohol. Thereby, a high-quality fatty acid alkyl ester can be obtained efficiently. Then, in this invention, the said 2nd component provides the manufacturing method of the fatty-acid alkylester containing the compound which has a carbon-carbon double bond or an epoxy ring at least. Thereby, it can be made to react with water efficiently. Furthermore, in the present invention, the second component provides a method for producing a fatty acid alkyl ester containing at least ethylene or ethylene oxide. Thereby, a high-quality fatty acid alkyl ester can be obtained efficiently.

  Moreover, in this invention, the said reaction which converts the said fats and oils raw material into the said fatty acid alkyl ester provides the manufacturing method to the fatty acid alkyl ester which adds alcohol to the said fats and oils raw material. Thereby, a high-quality fatty acid alkyl ester can be obtained efficiently.

  Furthermore, in this invention, the said alcohol added to the said oil-fat raw material provides the manufacturing method of the fatty-acid alkylester which is a supercritical state or a subcritical state. Thereby, conversion to a fatty acid alkyl ester can be performed even under non-catalytic conditions.

  In the present invention, “oil and fat” includes at least one of fatty acid glycerides (including fatty acid triglycerides, fatty acid diglycerides, and fatty acid monoglycerides) and fatty acids. That is, in this invention, the raw material fats and oils which contain any one or both of a free fatty acid and fatty-acid glyceride are made into wide object. “Fatty acid alkyl ester” means (1) free fatty acid originally contained in the raw oil and fat, (2) fatty acid produced by some reaction of the components in the raw oil and fat, and (3) in the raw oil and fat. Means a fatty acid ester obtained through an esterification reaction or a transesterification reaction.

  According to the present invention, the second component that reacts with water is added to a reaction system that converts the oil / fat raw material to the fatty acid alkyl ester, thereby converting the water contained in the oil / fat raw material into the fatty acid alkyl ester. At this time, water and the like that are by-produced can be removed. Furthermore, the product obtained by the reaction of the second component with the water is used in the reaction for conversion to the fatty acid alkyl ester or is separable from the fatty acid alkyl ester, thereby efficiently and high-quality. Fatty acid alkyl esters can be obtained.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments for carrying out the invention will be described with reference to the accompanying drawings. In addition, each embodiment shown by drawing showed the typical embodiment example of the manufacturing method which concerns on this invention, and, thereby, this invention is not interpreted narrowly.

  In general, the raw material fats and oils used in the production method according to the present invention often contain fatty acid glycerides such as fatty acid triglycerides, fatty acid diglycerides, fatty acid monoglycerides, free fatty acids, water and the like. For example, in waste oils and fats such as waste cooking oil, fatty acid triglyceride is the main component, and in dark oil, free fatty acid is the main component. Furthermore, since the reaction in the supercritical state is a high temperature, some condensation reaction may occur as a side reaction and water may be generated in the reaction system.

  FIG. 1 is a basic conceptual diagram of a method for producing a fatty acid alkyl ester according to the present invention.

  FIG. 2 is a diagram showing a reaction example in which a substance having a carbon-carbon double bond is added as a second component to the esterification reaction of a fatty acid and an alcohol in the fat and oil raw material, and FIG. It is a figure which shows the reaction example which added ethylene as a 2nd component to esterification reaction of a fatty acid and alcohol. FIG. 4 is a diagram showing a reaction example in which a substance having an epoxy ring as a second component is added to the transesterification reaction between a fatty acid glyceride and an alcohol in an oil or fat raw material. FIG. 5 is a diagram showing a reaction example in which ethylene oxide is added as the second component to the transesterification reaction between the fatty acid glyceride and the alcohol in the oil and fat raw material.

Note that R ¹ , R ² , R ³ , R ⁴ , R ⁵ , and R ⁶ shown in Formulas 1 to 5 and FIGS. 2 to 5 represent hydrocarbon groups, and these hydrocarbon groups are different from each other. Or all or any of them may be the same kind of hydrocarbon group. In addition, these hydrocarbon groups are not limited in carbon number, and may be bonded to other functional groups such as alkoxy groups (the same applies hereinafter).

  A process of FIG. 1 is a process of converting fats and oils raw material into fatty acid alkyl ester. And B process is a process of making water and a 2nd component react. First, in general, fat and oil raw materials include fatty acid glycerides, free fatty acids, water and the like. In step A, the fatty acid glyceride, the free fatty acid and the like are converted into a fatty acid alkyl ester. However, water and the like are generated as impurities in addition to the fatty acid alkyl ester. Or as high temperature conditions like a supercritical state, water may produce | generate by the side reaction by condensation. The water must be reliably removed in order to obtain a high-quality fatty acid alkyl ester.

  Step B is a step of adding a second component that reacts with water to the reaction system. That is, in order to remove water existing in the step A, a second component having a property of reacting with water is added to the reaction system of the step A. When the second component reacts with the water, water present in the reaction system is removed. And according to the said B process, not only the water contained from the beginning in the said fats and oils raw material but the water by-produced by reaction of the said A process and the water formed by the condensation by another side reaction can also be removed. At that time, in the present invention, the timing for performing the step B is not particularly limited. For example, the second component may be added simultaneously with the start of the reaction in the step A, or the reaction in the step A proceeds to some extent. You may add it later.

And the product obtained by the said 2nd component reacting with the said water can be used for the said A process, or can be isolate | separated with the said fatty-acid alkylester (refer FIG. 1). When the product can be used in the step A, the fatty acid alkyl ester can be obtained more efficiently. In addition, when the product can be separated from the fatty acid alkyl ester, water can be efficiently removed by converting the supercritical or subcritical water easily mixed with the fatty acid alkyl ester into the product. . For example, the product can be separated and removed by dissolving in other impurities such as the glycerin without dissolving in the fatty acid alkyl ester. In this case, the product can be efficiently separated by being contained in the glycerin phase by stationary separation or the like.

  Here, the example of reaction performed at the said A process is demonstrated. In addition, the reaction example shown below is only the illustration of reaction performed by this invention. First, the fatty acid glyceride in the raw oil and fat and the alcohol added from the outside are transesterified to produce a fatty acid alkyl ester (see Formula 1). This is a one-step reaction in which fatty acid glycerides are converted directly to fatty acid alkyl esters.

  In the one-step reaction, a large amount of glycerin is by-produced together with the fatty acid alkyl ester (see Formula 1). However, since the fatty acid alkyl ester phase and the glycerin phase are easily separated by standing and separating the reaction solution, the fatty acid alkyl ester and the glycerin can be easily separated.

  Next, fatty acid glycerides in the raw material fats and oils are hydrolyzed to produce free fatty acids (see Formula 2), and fatty acid alkyl esters are also produced by the esterification reaction between the free fatty acids and the alcohol (Formula 3). reference). This is a two-stage reaction in which fatty acid glycerides are converted to fatty acid alkyl esters via free fatty acids.

  In the two-stage reaction, water present from the beginning in the oil and fat raw material is used for the hydrolysis of the fatty acid glyceride, but new water is generated as a by-product by the esterification reaction (see Formula 3). Moreover, in order to obtain a fatty acid alkyl ester efficiently in the esterification reaction, it is necessary to offset the equilibrium of the esterification reaction in the positive reaction direction (esterification direction). For this purpose, it is necessary to remove the water from the reaction system (see Formula 3). Therefore, in particular, how to remove water from the reaction system in the esterification reaction in which new water is generated is an important issue.

  In addition, the fatty acid used for the reaction is not limited to the free fatty acid generated by the hydrolysis of the fatty acid glyceride (see Formula 2). For example, the fatty acid contained in the raw material fat or oil from the beginning, The component may be a fatty acid or the like produced by some kind of reaction.

  Moreover, in this invention, it is not limited to reaction of the said oil-fat raw material and the said alcohol, For example, you may produce | generate a fatty-acid alkylester by transesterification with the said free fatty acid and carboxylic acid ester (refer Formula 4). The carboxylic acid ester may be added from the outside, or may be present in the oil or fat raw material from the beginning.

Further, when the carboxylic acid ester is an alkyl formate such as methyl formate (HCOOCH ₃ ), formic acid (HCOOH) is generated as a free fatty acid. The formic acid is rapidly decomposed into carbon monoxide (CO ₂ ) and water (H ₂ O) depending on the reaction conditions of the esterification reaction and the transesterification reaction (see Formula 5). In this case, since the produced water remains in the reaction system, it is more difficult to remove the water.

  The reaction performed in the conversion step to the fatty acid alkyl ester in the present invention is not particularly limited, and may be a one-step reaction or a multi-step reaction. Therefore, the present invention can be applied to a wide range of reactions that can be converted from fat and oil raw materials to fatty acid alkyl esters, and even when formic acid (HCOOH) is present as the free fatty acid or the like, the formic acid is decomposed (see Formula 5). This is a method for producing a fatty acid alkyl ester that is also efficient because it can remove the generated water.

  Further, in the present invention, the amount of the second component added is not limited, and is suitably suitable in consideration of the composition of the oil / fat raw material to be used, the reaction conditions of the step A, and what kind of reaction proceeds. The amount added can be determined. In addition, the second component used in the present invention may not be one kind of substance, and an additive or the like may be appropriately used as necessary.

  FIG. 2 is a diagram showing a reaction example in which a second component having a carbon-carbon double bond is added as the second component to the esterification reaction of a fatty acid and an alcohol in an oil or fat raw material.

  In the step A, a reaction in which a fatty acid alkyl ester is obtained by esterification of a fatty acid and an alcohol a proceeds. At that time, a large amount of water is by-produced together with the fatty acid alkyl ester. It is necessary to remove the by-product water from the reaction system in order to obtain a high-purity fatty acid alkyl ester or to shift the equilibrium of the esterification reaction to a positive reaction (see Formula 2, Formula 3, etc.). . In addition to the esterification reaction, a transesterification reaction (see Formula 1 etc.) or the like may proceed as the step A.

  And in the said B process, the substance (alkene) which has a carbon-carbon double bond can be used as a 2nd component. The second component and the water react to produce alcohol b. By the addition reaction of the water with the second component, water newly generated by the esterification reaction can be efficiently removed. The substance having a carbon-carbon double bond (alkene) has high reactivity with water, and side reactions are unlikely to occur, and the reaction can be easily controlled. The fatty acid alkyl ester can be obtained.

  Furthermore, depending on the kind of the alcohol b, it can be used in the esterification reaction (step A) together with the alcohol a. Alternatively, when it is dissolved with glycerin by-produced by other transesterification reaction (see Formula 1) or the like, it can be separated from the fatty acid alkyl ester phase as a glycerin phase.

  Moreover, the kind of alcohol b to produce | generate changes with the substances used as said 2nd component. Therefore, depending on what kind of substance is used as the second component, it can be determined whether it can be used for the esterification reaction or can be removed together with the glycerin phase which is an impurity phase. For example, when the alcohol b is a monohydric alcohol having only one hydroxyl group, it can be used for the esterification reaction (step A). Alternatively, when the alcohol b has a structure having a plurality of hydroxyl groups, it can be efficiently removed by dissolving in an impurity phase such as glycerin.

  The structure of the carbon-carbon double bond (> C = C <) of the second component (alkene) is not limited, but preferably from the viewpoint of the type of fatty acid alkyl ester obtained, reactivity with water, and the like. Is preferably a structure having a small number of substituents of double bonds, more preferably ethylene. Hereinafter, a reaction example in which ethylene is added as the second component will be described.

  FIG. 3 is a diagram showing a reaction example in which ethylene is added as a second component to the esterification reaction between a fatty acid and an alcohol in an oil and fat raw material.

  By using ethylene as the second component, the ethylene reacts with water to produce ethanol (see FIG. 3). And this ethanol can be utilized for esterification reaction with a free fatty acid as it is. Further, in the present invention, the timing of adding the ethylene is not particularly limited. For example, it may be added directly to the oil or fat raw material before performing the step A, and appropriately added while the step A is in progress. May be. The ethylene can be appropriately added at a suitable time according to the reaction conditions of the step A. Moreover, in this invention, what is necessary is just the 2nd component containing at least ethylene, and a stabilizer, a reaction accelerator, etc. may be added suitably other than the said ethylene.

  And when the said ethylene is used as a 2nd component, the said ethanol is efficient also in the point from which the fatty acid ethyl ester generally used for the said BDF fuel is obtained by esterification. Furthermore, since ethylene is an industrially general-purpose substance and side reactions are unlikely to occur, reaction control is easy, so the production method according to the present invention can be used as an industrial production method for the BDF fuel.

  FIG. 4 is a diagram showing a reaction example in which a second component having an epoxy ring as a second component is added to a transesterification reaction between a fatty acid glyceride and an alcohol in an oil or fat raw material.

  As said A process, fatty-acid alkylester produces | generates by transesterifying with fatty-acid glyceride and alcohol a. At that time, a large amount of glycerin is by-produced together with the fatty acid alkyl ester. By allowing the reaction solution to stand after completion of the transesterification reaction, it can be divided into a fatty acid alkyl ester phase (upper layer) and a glycerin phase (lower layer). Therefore, the glycerin can be easily separated from the fatty acid alkyl ester. In addition to the transesterification reaction, an esterification reaction (see Formula 2, Formula 3, etc.) may also proceed.

  And in order to remove the water which exists in said A process, the substance (epoxide) which has an epoxy ring can be used as said 2nd component as said B process. The second component (epoxide) and water present in the reaction system react to produce 1,2-diol (dihydric alcohol) (see FIG. 4). The substance having an epoxy ring (epoxide) has high reactivity with water, and side reactions are unlikely to occur and the reaction control is easy. Therefore, the water can be effectively removed, and high-quality fatty acids can be efficiently removed. Alkyl esters can be obtained.

  Furthermore, since the diol is well compatible with the glycerin, it can be efficiently separated from the fatty acid alkyl ester by being contained in the glycerin phase by stationary separation. Therefore, water originally present in the oil and fat raw material and water newly generated by various reactions are also separated from the fatty acid alkyl ester together with the glycerin by reacting with the second component and being converted into the diol. it can.

  In the present invention, the structure of the epoxy ring of the second component (epoxide) is not limited. However, from the viewpoint of reactivity with water, compatibility with glycerin, and the like, the number of substituents on the epoxy ring is preferably small. A chemical structure is desirable, and ethylene oxide is more desirable. Hereinafter, a reaction example in which ethylene oxide is added as the second component will be described.

  FIG. 5 is a diagram showing a reaction example in which ethylene oxide is added as the second component to the transesterification reaction between the fatty acid glyceride and the alcohol in the oil and fat raw material.

  By using ethylene oxide as the second component, the ethylene oxide reacts with water to produce ethylene glycol (ethylene glycerol) (see FIG. 5). Since the ethylene glycol (ethylene glycerol) is well compatible with the glycerin, it can be efficiently separated from the fatty acid alkyl ester phase by standing and separating the reaction solution after the transesterification reaction. Furthermore, since ethylene oxide is a general-purpose material industrially and side reactions are unlikely to occur, the reaction control is easy. Therefore, the production method according to the present invention is useful as an industrial production method for the BDF fuel. Moreover, in this invention, what is necessary is just the 2nd component containing at least ethylene oxide, and you may add a stabilizer, a reaction accelerator, etc. other than the said ethylene oxide suitably.

  Moreover, in the manufacturing method of this invention, you may perform the process of converting the said fats and oils raw material into the said fatty acid alkyl ester by adding alcohol to the said fats and oils raw material. Thereby, the one-stage reaction (transesterification reaction; see Formula 1 etc.) and the two-stage reaction (esterification reaction: see Formula 2, Formula 3 etc.) proceed respectively. Accordingly, fatty acid alkyl esters are obtained by the respective reactions, and water can be effectively removed from the fatty acid alkyl esters by the step B, which is efficient.

  In particular, the high-quality fatty acid alkyl ester can be obtained more efficiently by performing the step B in the esterification reaction (see Formula 2, Formula 3, etc.). That is, not only can a large amount of water by-produced by the esterification be efficiently removed, but also the equilibrium of the esterification reaction can be offset in the positive reaction direction (esterification direction), so that the reaction conditions can be relaxed and the efficiency This is because the fatty acid alkyl ester can be obtained well.

  And in this invention, it is not limited about the catalyst etc. which are used about reaction which converts the said fats and oils raw material into the said fatty-acid alkylester. For example, when performing the transesterification reaction, the esterification reaction, or the like, the alkali catalyst method using an alkali catalyst or the acid catalyst method using an acid catalyst may be used. Alternatively, a lipase enzyme method in which alcohol or the like is added may be used, or a plurality of these methods may be combined.

  That is, according to the production method of the present invention, at least water initially contained in the fat and oil raw material can be efficiently removed, so that it can be used for a wide range of reactions. And even if it is reaction which newly produces | generates water in a reaction system like the said alkali catalyst method etc., according to this invention, the newly produced | generated water can also be efficiently removed from a reaction system. Therefore, the present invention can be used for a wide range of reactions such as the alkali catalyst method, the acid catalyst method, the lipase enzyme method, etc., and even when water is newly generated in these reactions. be able to.

Furthermore, in the present invention, the step of converting the oil / fat raw material into the fatty acid alkyl ester is carried out in the presence of an alcohol in a supercritical state or a subcritical state, thereby obtaining a high-quality fatty acid alkyl ester more efficiently. Can do. By setting the supercritical state or the subcritical state, fatty acid alkyl esters can be obtained under non-catalytic conditions. In the present invention, the type of the alcohol is not limited, but is preferably a monohydric alcohol (R ² OH: see Formula 2 and the like). The type of the monohydric alcohol can be appropriately selected in consideration of the type of fatty acid alkyl ester to be produced, the reactivity with the oil and fat raw material, and the like. It is desirable that it is a monohydric alcohol having

  Here, the “supercritical state” of the alcohol as a solvent is a state in which the temperature in the reaction system is equal to or higher than the critical temperature (Tc) of the alcohol and the pressure is equal to or higher than the critical pressure (Pc) of the alcohol. That means. In addition, the “subcritical state” is a state in which the temperature in the reaction system is equal to or higher than the boiling point of the alcohol and approximately 150 degrees or higher, and the pressure is equal to or higher than the vapor pressure of alcohol at the reaction temperature and approximately 2.0 MPa or higher. Say.

Table 1 shows an example of the critical temperature (Tc) and critical pressure (Pc) of the monohydric alcohol.

  In the present invention, the reaction conditions and the like by the supercritical method are not limited, and suitable reaction conditions can be appropriately set in consideration of the oil and fat raw material, the second component, and the like. For example, an alkali catalyst may be added to the alcohol in the supercritical state or subcritical state, or other substances may be added to the reaction system.

  Furthermore, by performing the conversion step to the fatty acid alkyl ester in the presence of alcohol in a supercritical state or a subcritical state, in a one-step reaction (transesterification reaction: see Formula 1), the purity of the catalyst and water is not included. High glycerin is obtained. Therefore, the glycerin can be reused separately as a biodegradable plastic material or a wood liquefaction agent.

  Here, a comparative experiment was conducted for the purpose of confirming the effect of the present invention.

<Experiment method>
First, as an example, oleic acid (manufactured by Nacalai Tesque Co., Ltd.) and 0.7 mol / L ethylene oxide / methanol solution (manufactured by Tokyo Chemical Industry Co., Ltd.), oleic acid: methanol: ethylene oxide = 1: 42: After preparing so that it might become 1.2 molar ratio, it enclosed in a 5 mL batch type reaction tube, and it reacted at 300 degreeC, 27 Mpa, and 60 minutes. Next, as a comparative example, oleic acid and methanol were prepared in a molar ratio of 1:42, and then reacted under the same conditions as in the example.

<Evaluation method>
Evaluation of the processed products obtained in Examples and Comparative Examples was performed by measuring the acid value. The acid value is defined as the number of mg of potassium hydroxide required to neutralize free fatty acid contained in 1 g of a sample, and is evaluated by neutralization titration using potassium hydroxide. Table 2 shows the acid value of each of the examples and comparative examples.

<Discussion>
In the comparative example in which nothing was added as the second component, the acid value of the obtained processed product was 12.7 mg (KOH) / g. On the other hand, in the example in which ethylene oxide was added as the second component, the acid value of the obtained processed product was 5.9 mg (KOH) / g, and the acid value of the comparative example could be greatly reduced. From the above, it was suggested that a higher-grade fatty acid alkyl ester can be obtained by adding at least ethylene oxide as the second component to the reaction system.

  Next, an experiment was conducted for the purpose of verifying that alcohol was obtained by reacting with water by adding the second component to the reaction system. More specifically, ethylene was used as the second component, and it was verified whether or not the reaction in which ethylene reacts with water to obtain ethanol proceeds.

<Experiment method>
4 mL of distilled water (HPLC grade, manufactured by Nacalai Tesque Co., Ltd.) is put into a 5 mL batch reaction tube for gas filling, and liquefied ethylene (purity 99.9%) is sealed therein so that the pressure in the tube becomes 10 MPa, Reaction was performed at 230 ° C. to 300 ° C. for 40 minutes.

<Evaluation method>
After completion of the reaction, the product was filtered through a Cosmonis filter (0.45 μm × 4 mm, manufactured by Nacalai Tesque), followed by HPLC chromatography (mobile phase: water (1 mL / min), column: STR-ODSII ( 250 × 4.6 mm), detector: suggested refraction detector (RID), column temperature: 40 ° C.), the amount of ethanol produced was directly analyzed. The HPLC chromatogram of the reaction product after the reaction at each temperature is shown in FIG.

<Discussion>
As shown in FIG. 6, an ethanol peak was confirmed at a reaction temperature of 230 ° C. Moreover, the ethanol peak was confirmed also at each other reaction temperature, and it was confirmed that ethanol was produced under any conditions. From the above, by adding ethylene as the second component to the reaction system, ethanol can be removed without catalyst under a temperature and pressure conditions above a certain level and used for esterification with free fatty acids. It was suggested that

  Subsequently, it was verified whether or not alcohol could be obtained by adding the second component even in a system in which methanol was mixed in the reaction system. In detail, while using ethylene as said 2nd component, the behavior in the reaction conditions which mixed water and methanol were verified.

<Experiment method>
Changing the mixing ratio (volume ratio) of distilled water (HPLC grade, manufactured by Nacalai Tesque) and methanol (low moisture solvent, manufactured by Nacalai Tesque) to a total of 4 mL, 5 mL batch reaction tube for gas filling Put in. Liquefied ethylene (purity 99.9%) was enclosed here so that the pressure in a pipe | tube might be 10 Mpa, and reaction was performed at 270 degreeC for 40 minutes.

<Evaluation method>
After completion of the reaction, the product was filtered through a Cosmonis filter (0.45 μm × 4 mm, manufactured by Nacalai Tesque), followed by HPLC chromatography (mobile phase: water (1 mL / min), column: STR-ODSII ( 250 × 4.6 mm), detector: suggested refraction detector (RID), column temperature: 40 ° C.), the amount of ethanol produced was directly analyzed. The HPLC chromatogram after the reaction is shown in FIG.

<Discussion>
In any of the volume ratios of water to ethanol of 100: 0 and 75:25, the ethanol peak was confirmed as in Example 2. From this, it was confirmed that even in the presence of methanol, a reaction in which water is added to ethylene to produce ethanol proceeds.

  From the above, according to the method for producing a fatty acid alkyl ester according to the present invention, by adding the second component to the reaction system, it can be reacted with water contained in the oil raw material, water produced in the reaction system, and the like. It was suggested that the water can be removed efficiently and easily.

  The present invention can be used as a technique for producing a high-quality fatty acid alkyl ester that can be suitably used as a biodiesel fuel.

1 is a basic conceptual diagram of a method for producing a fatty acid alkyl ester according to the present invention. It is a figure which shows the reaction example which added the 2nd component which has a carbon-carbon double bond as a 2nd component to the esterification reaction of the fatty acid and alcohol in fats and oils raw material. It is a figure which shows the example of reaction which added ethylene as a 2nd component to the esterification reaction of the fatty acid in fats and oils and alcohol. It is a figure which shows the reaction example which added the 2nd component which has an epoxy ring as a 2nd component to the transesterification of the fatty-acid glyceride and alcohol in fats and oils raw material. It is a figure which shows the reaction example which added the ethylene oxide as a 2nd component to the transesterification reaction of the fatty acid glyceride and alcohol in fats and oils raw materials. It is a figure which shows the HPLC chromatogram of the reaction material after making ethylene and water react on each temperature conditions for 40 minutes. It is a figure which shows the HPLC chromatogram of the reaction material after making ethylene and water make 270 degreeC and 40 minute (s) in presence of methanol.

Explanation of symbols

Step A Step of converting fat / oil raw material into fatty acid alkyl ester Step B Step of adding the second component to the reaction system of Step A

Claims (6)

A method for producing a fatty acid alkyl ester from an oil and fat raw material,
By adding a second component that reacts with water to the reaction system that converts the oil raw material into the fatty acid alkyl ester,
The second component reacts with water contained in the oil raw material and / or water generated in the reaction system,
The product produced by the reaction of the second component with the water is used for the reaction to convert to the fatty acid alkyl ester or is separable from the fatty acid alkyl ester.   The method for producing a fatty acid alkyl ester according to claim 1, wherein the product is an alcohol.   The said 2nd component contains the compound which has a carbon-carbon double bond or an epoxy ring at least, The manufacturing method of the fatty-acid alkylester of Claim 2 characterized by the above-mentioned.   The method for producing a fatty acid alkyl ester according to claim 2, wherein the second component contains at least ethylene or ethylene oxide.   The method for producing a fatty acid alkyl ester according to any one of claims 1 to 4, wherein in the reaction for converting the oil or fat raw material to the fatty acid alkyl ester, an alcohol is added to the oil or fat raw material.   The method for producing a fatty acid alkyl ester according to claim 5, wherein the alcohol added to the fat and oil raw material is in a supercritical state or a subcritical state.