JP2004026738A - Method for manufacturing fatty acid ester - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for efficiently manufacturing a fatty acid lower alkyl ester having an acid value of a certain level or lower by a non-catalytic esterification of a fatty acid with a lower alcohol. <P>SOLUTION: The method for manufacturing the fatty acid lower alkyl ester by a non-catalytic esterification of a fatty acid with a lower alcohol comprises feeding the fatty acid into a reaction tank, continuously or intermittently introducing the lower alcohol in a gaseous or liquid state into the bottom part of the reaction tank, and effecting the esterification reaction under pressure while continuously or intermittently removing generated water together with the lower alcohol to the outside of the system, condensing the vapor of the fatty acid and/or the fatty acid lower alkyl ester in the mixed vapor of the lower alcohol and generated water by a partial condenser and circulating the recovered fatty acid and/or the fatty acid lower alkyl ester into the reaction system. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for producing a fatty acid lower alkyl ester by a non-catalytic esterification reaction between a fatty acid and a lower alcohol.
[0002]
[Prior art]
Conventionally, as a general catalyst, a fatty acid and a lower alcohol are subjected to an esterification reaction using a protic acid or a Lewis acid such as p-toluenesulfonic acid, hydrochloric acid, sulfuric acid, tin oxide, and alkoxy titanate to produce a fatty acid lower alkyl ester. Have been. However, these acids have a high catalytic activity, but have problems such as a complicated neutralization / washing step for separating and removing the catalyst after the completion of the reaction and a treatment of wastewater generated at that time.
[0003]
In addition, the fatty acid lower alkyl ester produced by the above-mentioned esterification reaction may have a trace amount of a catalyst remaining as an impurity, and therefore, it is not appropriate to use it directly in the field of foods and cosmetics. In addition, there arises a problem that such impurities become a catalyst poison when various lower alcohols are produced by hydrogenating a lower alkyl ester of a fatty acid.
[0004]
On the other hand, a production method by a self-acid catalysis method, commonly called a non-catalytic esterification reaction, which depends on an acidic proton of the fatty acid itself, is an effective method for solving the problems of the above-mentioned esterification method such as wastewater and catalyst poisons. . However, since the non-catalytic esterification reaction depends on the acidic proton concentration of the raw material itself, the reaction easily proceeds in a state where the acid value is large, but the reaction becomes extremely slow in a state where the acid value is small, and the acid reaction is slow. There is a problem that the price does not fall below a certain level.
[0005]
For example, US Pat. No. 5,349,075 discloses a non-catalytic esterification reaction of a C 2-24 fatty acid and a C 1-5 alcohol with a lower alcohol continuously in a gaseous state. The first step of obtaining a fatty acid lower alkyl ester crude product having a medium acid value by a method of continuously releasing an alcohol containing product water to the outside of the system by feeding the fatty acid of the present invention to a fatty acid, and catalyzing a sulfonic acid type ion exchange resin. A reaction method including a second step of completing the esterification reaction is disclosed.
[0006]
However, in the above disclosed technology, in the first stage of the non-catalytic esterification reaction, the acid value is 6 in the case of a batch reaction, and the acid value is 1. even in the case of using a countercurrent bubble column with the highest reaction efficiency. However, there are drawbacks such that it is necessary to complete the esterification reaction using an expensive sulfonic acid type ion exchange resin as a catalyst in order to reduce the acid value to 1 or less. At present, it cannot be said that this is a non-catalytic esterification reaction process.
[0007]
In the field of foods and cosmetics, there is a strong demand for fatty acid lower alkyl esters having an acid value of 1 or less, preferably 0.5 or less. However, lower alkyl esters of fatty acids having an acid value of 1 or less, preferably 0.5 or less, have not been obtained by a non-catalytic esterification method.
[0008]
[Problems to be solved by the invention]
An object of the present invention is to provide a process for efficiently producing a fatty acid lower alkyl ester having an acid value of a certain level or less by non-catalytic esterification of a fatty acid and a lower alcohol.
[0009]
[Means for Solving the Problems]
The present inventors have earnestly studied to solve the above-mentioned problems, and as a result, have obtained the following findings.
(1) A process for continuously removing water and lower alcohol produced while continuously introducing lower alcohol having a water content of a specific amount or less is effective.
[0010]
(2) The yield is improved by condensing the fatty acid and / or fatty acid ester vapor distilled together with the lower alcohol by a decomposer, returning the vapor to the reaction vessel and circulating the same.
[0011]
(3) In order to reduce the acid value to a specific level or lower, it is necessary to introduce a lower alcohol having a water content of the specific level or lower.
[0012]
(4) As the lower alcohol introduced into the reaction crude in the first half of the reaction, the lower alcohol recovered from the lower alcohol having a small water content introduced in the second half of the reaction can be reused as it is.
[0013]
The present invention has been completed based on such knowledge, and provides the following inventions.
Item 1. A method for producing a fatty acid lower alkyl ester by non-catalytic esterification reaction of a fatty acid and a lower alcohol, wherein the fatty acid is charged into a reaction vessel, and then the lower alcohol is continuously converted into a gaseous or liquid state. Alternatively, the fatty acid and / or fatty acid in the mixed vapor of the lower alcohol-produced water is intermittently introduced into the bottom of the reaction vessel, and the produced water is continuously or intermittently removed from the system together with the lower alcohol under pressure. A method for producing a fatty acid lower alkyl ester, comprising condensing vapor of a lower alkyl ester by a decomposer, returning the recovered fatty acid and / or lower fatty acid alkyl ester to the reaction system, and performing an esterification reaction while circulating. .
[0014]
Item 2 The method for producing a fatty acid lower alkyl ester according to Item 1, wherein a lower alcohol having a water content of 1.0% by weight or less is introduced.
[0015]
Item 3. The lower alkyl fatty acid according to Item 1 or 2, wherein a lower alcohol having a water content of 1.0% by weight or less is introduced after the acid value of the crude esterification reaction reaches 20 or less. Method for producing ester.
[0016]
Item 4. After the acid value of the esterification reaction crude reaches 20 or less, the recovered lower alcohol generated when a lower alcohol having a water content of 1.0% by weight or less is introduced into the esterification reaction crude as it is. Item 4. The process for producing a lower alkyl fatty acid ester according to any one of Items 1 to 3, wherein the method is introduced into the crude reaction product having a value of 20 or more.
[0017]
Item 5. The method according to any one of Items 1 to 4, wherein a lower alcohol having a water content of 0.2% by weight or less is introduced after the acid value of the crude esterification reaction reaches 5 or less. A method for producing a fatty acid lower alkyl ester.
[0018]
Item 6. The method for producing a lower alkyl fatty acid according to any one of Items 1 to 6, wherein 0.1 to 0.4 t / h is introduced with respect to 1 t of the crude esterification reaction of the lower alcohol. .
[0019]
Item 7 The method for producing a lower alkyl ester of a fatty acid according to any one of Items 1 to 7, wherein the reaction pressure is 0.2 to 5 MPa and the reaction temperature is 200 to 300 ° C.
[0020]
Item 8. The production of a fatty acid lower alkyl ester according to any one of Items 1 to 7, wherein the fatty acid is a saturated fatty acid having 8 to 36 carbon atoms and / or an unsaturated fatty acid, and the lower alcohol is methyl alcohol. Method.
[0021]
Item 9 A fatty acid methyl ester having an acid value of 1 or less obtained by the production method according to Item 8.
[0022]
BEST MODE FOR CARRYING OUT THE INVENTION
Manufacturing process <br/> present invention fatty acid esters, the non-catalytic esterification of fatty acids with lower alcohols, to a process for acid value to produce a certain level or less of a fatty acid lower alkyl esters efficiently.
[0023]
<Lower alcohol>
The lower alcohol according to the present invention is not particularly limited, but specifically, methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, iso-butyl alcohol Examples thereof include linear or branched saturated aliphatic alcohols having 1 to 4 carbon atoms, such as -butyl alcohol. Of these, methyl alcohol is particularly preferred.
[0024]
<fatty acid>
The fatty acid according to the present invention is not particularly limited, and examples thereof include organic carboxylic acids having 8 to 36 carbon atoms such as monocarboxylic acids, dicarboxylic acids, tricarboxylic acids, tetracarboxylic acids, and acid anhydrides thereof. .
[0025]
Specific examples of monocarboxylic acids include caprylic acid, nonanoic acid, capric acid, undecanoic acid, lauric acid, tridecanoic acid, myristic acid, pentadecanoic acid, palmitic acid, heptadecanoic acid, stearic acid, isostearic acid, nonadecanoic acid, and arachidine. Acids, heincic acid, behenic acid, lignoceric acid, cerotic acid, montanic acid, melicic acid, bubutsylic acid, caproleic acid, undecylenic acid, lindelic acid, tuzuic acid, fisthenic acid, myristoleic acid, palmitooleic acid, petroselinic acid , Oleic acid, elaidic acid, asclepic acid, vaccenic acid, gadolinic acid, gondronic acid, cetrenic acid, erucic acid, brassic acid, seracoleic acid, xymenic acid, lumecitric acid, sorbic acid, linoleic acid, hiragoic acid, eleostearin Acid, punicic acid, Saturated or unsaturated acids such as noreic acid, hexadecatetraenoic acid, moloctic acid, stearidonic acid, arachidonic acid, docosatetraenoic acid, eicosapentaenoic acid, succinic acid, nisinic acid, docosahexaenoic acid, and branched fatty acids having the same carbon number as these. Saturated fatty acids are exemplified.
[0026]
These fatty acids can be used alone or in combination of two or more.
[0027]
The vegetable fatty acids of the above mixture of fatty acids include coconut oil, palm kernel oil, palm oil, olive oil, soybean oil, rapeseed oil, safflower oil, corn oil, cottonseed oil, sunflower oil, rice bran oil, linseed oil, etc. And fatty acids obtained from these used frying oils and the like.
[0028]
Used frying oil is a type of vegetable oil that has been used by a collection company for a certain period of time in a restaurant kitchen, catering lunch box production, school lunch room, fast food store, snack confectionery factory, etc. Shows the oil that is being traded as a recycled oil.
[0029]
Examples of animal fatty acids include fatty acids made from fish oil such as beef tallow, lard, chicken fat, and sardine and orange luffy.
[0030]
As the fatty acids obtained from these vegetable or animal fats and oils, the saturated fatty acids and / or unsaturated fatty acids obtained by hydrolyzing the fats and oils may be used as they are, or may be subjected to distillation fractionation as required to obtain a predetermined fatty acid composition. May be used. For the purpose of obtaining a lower alkyl ester of unsaturated fatty acid, it is also possible to use a raw material having a fatty acid composition having a desired iodine value by subjecting the fatty acid to cooling solid fractionation.
[0031]
Further, tall oil fatty acids and petroleum naphthenic acids, which are distilled products of tall oil obtained from kraft pulp manufacturing waste liquid, can also be used.
[0032]
Further, as the fatty acid according to the present invention, a carboxylic acid commonly called a synthetic fatty acid can also be used. Specifically, a garbage reaction product of oxoaldehyde obtained by hydroformylating a linear or branched fatty acid having 8 to 20 carbon atoms and α-olefin obtained by liquid phase air oxidation of paraffin in the presence of carbon monoxide and hydrogen is oxidized. Examples thereof include fatty acids derived from the oxo method, such as 2-ethylhexanoic acid, isononanoic acid, and 3,5,5-trimethylheptanoic acid. Still further, aromatic carboxylic acids such as benzoic acid, toluic acid, dimethyl benzoic acid, and alkyl (2 to 12 carbon atoms) benzoic acid, and their hydrogenated carboxylic acids are exemplified.
[0033]
Examples of the dicarboxylic acid include dicarboxylic acids having 4 or more carbon atoms, and more specifically, succinic acid, maleic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecandioic acid, Dodecane diacid, brassic acid, dimer acid of unsaturated fatty acid, trimer acid of unsaturated fatty acid, cyclohexanedicarboxylic acid, tetrahydrophthalic acid, phthalic acid, biphenyldicarboxylic acid, benzophenonedicarboxylic acid, oxybiphenyldicarboxylic acid, diphenylsulfondicarboxylic acid and Examples thereof include geometric isomers, positional isomers, and acid anhydrides thereof.
[0034]
Specific examples of tricarboxylic acids and tetracarboxylic acids include tricarboxylic acids such as tricarballylic acid, aconitic acid, methylcyclohexentricarboxylic acid, citric acid, and trimellitic acid, butanetetracarboxylic acid, cyclopentanetetracarboxylic acid, and tetrahydrofurantetracarboxylic acid. Diels-Alder of carboxylic acid, ene-adduct of methyltetrahydrophthalic acid and maleic acid, pyromellitic acid, biphenyltetracarboxylic acid, benzophenonetetracarboxylic acid, oxybiphenyltetracarboxylic acid, diphenylsulfonetetracarboxylic acid, styrene and maleic anhydride Examples thereof include tetracarboxylic acids such as a tetracarboxylic acid obtained by a reaction and an ene reaction, and acid anhydrides thereof.
[0035]
Among these fatty acids, saturated fatty acids or unsaturated fatty acids having 8 to 30 carbon atoms are preferable, and in particular, saturated fatty acids having 8 to 30 carbon atoms of plant or animal system which are suitable for use as higher alcohols and food and cosmetic raw materials Or unsaturated fatty acids are preferred.
[0036]
<Esterification reactor>
Hereinafter, the esterification reactor according to the present invention will be described in detail.
The ester reactor used in the present invention is not particularly limited as long as it is a pressurized container having a heat supply capacity capable of evaporating a lower alcohol, and examples thereof include a stirrer-equipped container and a column reactor. Is exemplified.
[0037]
The lower alcohol is introduced in a gaseous or liquid state continuously or intermittently from the inlet provided at the bottom of the reaction vessel, and as a result, the gaseous lower alcohol or boiling lower alcohol vapor and the vapor of the reaction product water flow from the bottom of the reaction vessel. The effect of the stirring action in the reaction system is also exerted by the rise of the bubble composed of
[0038]
In the case of a tower reactor having no stirrer in the reactor, stirring in the reaction system is performed only by rising bubbles. Therefore, it is recommended to employ a column reactor in which the gas linear velocity of the lower alcohol is usually about 2 to 10 cm / s.
[0039]
The reaction is promoted by continuously or intermittently removing the produced water from the upper part of the reaction vessel together with the lower alcohol out of the system. At this time, the vapor of the fatty acid and / or the fatty acid lower alkyl ester in the mixed vapor of the lower alcohol-produced water is condensed by a decomposer, and the recovered fatty acid and / or fatty acid lower alkyl ester is returned to the reaction system. Circulate. At this time, the mixed vapor of the lower alcohol and the produced water that has passed through the decomposer is cooled by the condenser, and the lower alcohol is recovered. Among them, the recovered lower alcohol having a water content of a certain amount or less can be reused.
[0040]
The condenser may be connected to a condenser independent of the reaction vessel by a pipe, or may be installed as an integral unit at the top of the reactor. In the case of a column reactor, a decompression zone may be set at the top of the column. These selections are not particularly limited as long as the effects of the present invention can be obtained. For example, if existing equipment is effectively used, a separate decomposer can be installed as appropriate.
[0041]
The temperature of the decompressor varies depending on the reaction pressure, but is usually preferably in the range of about 150 to 220 ° C. If the temperature is lower than 150 ° C., the condensed water in the circulating liquid returning to the reaction system increases, so that the reaction rate tends to decrease. If the temperature exceeds 220 ° C., the condensed amount of fatty acids and / or fatty acid esters decreases, There is a tendency for the yield to decrease.
[0042]
The installation of such a condensing device involves condensing the fatty acid and / or the lower alkyl ester of the fatty acid in the mixed vapor of the lower alcohol and the produced water by the condensing device, and collecting the recovered fatty acid and / or the lower fatty acid alkyl ester. It is also preferable from the viewpoint that the yield can be improved by returning it to the reaction system and circulating it.
[0043]
<Esterification reaction>
The reaction pressure is generally recommended to be about 0.2 to 5 MPa, preferably about 0.5 to 0.9 MPa. If it is less than 0.2 MPa, the dissolved amount of lower alcohol is small and the reaction time tends to be long. If it exceeds 5 MPa, expensive pressure-resistant structural equipment is required, which is disadvantageous in cost.
[0044]
The reaction temperature is usually about 200-300 ° C, preferably about 220-260 ° C. If the temperature is lower than 200 ° C., the reaction rate becomes slow and lacks practicality, and if it exceeds 300 ° C., the fatty acid lower alkyl ester (for example, unsaturated fatty acid lower alkyl ester) tends to undergo thermal deterioration. Such a problem does not occur within the scope of the present invention. For example, in the case of oleic acid, methyl oleate showing the theoretical iodine value calculated from the iodine value of the raw material fatty acid is obtained.
[0045]
The method of introducing the lower alcohol may be either gaseous or liquid. The gaseous state is preferably introduced, for example, by installing a batch-type evaporator, a continuous multi-tube evaporator, or the like at an introduction site at the bottom of the reaction vessel.
[0046]
The introduction in the liquid state may be performed as it is, or it is preferable to install a batch-type can-type heater or a continuous-type tube-type heater in advance.
[0047]
The lower alcohol introduction temperature is usually in the range of room temperature to about 300 ° C, preferably about 100 to 260 ° C. If the reactor itself has sufficient heat supply capacity, low-temperature lower alcohol can be introduced.On the other hand, if there is not enough heat supply capacity, the reaction temperature or latent heat of vaporization of lower alcohol in the reactor is considered in advance. It is preferred to introduce at a temperature determined.
[0048]
In the present invention, the lower alcohol introduced continuously or intermittently is preferably a lower alcohol having a water content of 1.0% by weight or less.
[0049]
In particular, it is preferable to introduce a lower alcohol having a water content of 1.0% by weight or less after the acid value of the crude esterification reaction reaches 20 or less. When a lower alcohol having a water content of more than 1.0% by weight is introduced, the reaction becomes difficult to proceed, and a long time is required for the reaction. Therefore, the introduced amount of the lower alcohol increases, which is uneconomical.
[0050]
Further, after the acid value reaches 5 or less, it is preferable to introduce a lower alcohol having a water content of 0.2% by weight or less. When a lower alcohol having a water content of more than 0.2% by weight is introduced, the reaction becomes difficult to proceed, so that a long time is required for the reaction. Therefore, the introduced amount of the lower alcohol increases, which is uneconomical.
[0051]
The amount of the lower alcohol to be introduced is generally about 0.05 to 0.4 t / h, preferably about 0.1 to 0.3 t / h, based on 1 t of the crude esterification reaction. If it is less than 0.05 t / h, the reaction becomes slow and lacks practicality, and even if it exceeds 0.4 t / h, the reaction rate corresponding to the introduced amount cannot be improved, and unnecessary energy is consumed. It is uneconomical to consume.
[0052]
In the method of the present invention, after the acid value of the crude esterification reaction reaches 20 or less, the recovered lower alcohol generated when a lower alcohol having a water content of 1.0% by weight or less is introduced into the esterification reaction as it is. Since the crude product can be introduced into the reaction crude product having an acid value of 20 or more, the step of distilling and separating the lower alcohol and water can be omitted.
[0053]
<Lower alkyl esters of fatty acids>
By the non-catalytic esterification reaction between the fatty acid and the lower alcohol of the present invention, it has become possible to efficiently produce a fatty acid lower alkyl ester having an acid value of a certain level or less. In particular, a lower alkyl ester of a saturated fatty acid or unsaturated fatty acid having an acid value of 1 or less, preferably 0.5 or less and having 8 to 36 carbon atoms, preferably 8 to 30 carbon atoms, which is suitable for use as a higher alcohol, food or cosmetic raw material, is efficiently used. It became possible to manufacture well.
[0054]
【Example】
Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples, but is not limited thereto. The acid value was measured according to JIS K0070.
[0055]
Example 1
The lower alcohol in the bottom of 8m ³ pressure vessel equipped with a stirrer was used to set up the inlet can be supplied. The lower alcohol was metered and supplied to a multitubular heater, and was introduced as a gas or a liquid into the reactor through an inlet at the bottom of the can. An independent condenser was connected to the upper part of the reaction vessel by a pipe and installed as a decomposer. The temperature of the condenser used as the decompressor was controlled using a heat medium. All the liquid condensed in the condenser was returned from the bottom of the condenser to the reactor and circulated.
[0056]
As a fatty acid, 4200 kg of lauric acid (trade name “lauric acid P”, manufactured by Nippon Rika Co., Ltd.) was charged into a reactor, the reaction temperature was set to 260 ° C., the pressure was set to 0.88 MPa, and water heated to 120 ° C. by a heater was used. Was introduced at 800 kg / h, and the reaction was carried out for 4 hours. The acid value of the crude esterification reaction at that time was 0.2. Under these conditions, the boiling point of methyl alcohol at a pressure of 0.88 MPa is 140 ° C., and the methyl alcohol introduced as a liquid boils and gasifies at 260 ° C. at the bottom of the reactor. The decompressor kept 180 ° C. After the completion of the reaction, the reaction solution was cooled to obtain 4,413 kg (molar yield: 98.2%) of lauric acid methyl ester having an acid value of 0.2.
[0057]
Comparative Example 1
The esterification reaction was carried out in the same manner as in Example 1 except that the lauric acid methyl ester and / or lauric acid condensed in the condensing device was not circulated to the reactor, and 3258 kg of lauric acid methyl ester having an acid value of 0.2 ( Molar yield 72.5%).
[0058]
Example 2
As a fatty acid, 4200 kg of beef tallow unsaturated fatty acid (manufactured by NOF CORPORATION, trade name “NAA-34”) was used, the decompressor was kept at 200 ° C., and methyl alcohol was introduced as described below. An esterification reaction was carried out in the same manner as in Example 1. At the start of the reaction, methanol having a water content of 3% by weight of methanol was introduced for 2 hours, and the acid value after 2 hours was 15. Then, the water content was switched to methyl alcohol of 0.05% by weight and the mixture was introduced for 2 hours to obtain 4394 kg (molar yield: 99.6% by weight) of oleic acid methyl ester having an acid value of 0.2.
[0059]
Example 3
Using 4200 kg of palm kernel oil-based oleic acid (manufactured by Acid Chem Co., Ltd., trade name "PALMAC 760"), the esterification reaction was carried out in the same manner as in Example 2 except that methyl alcohol was heated to 180 ° C. and supplied in a gaseous state. As a result, 4393 kg of a palm kernel oil-based oleic acid methyl ester having an acid value of 0.2 (molar yield: 99.6%) was obtained. The obtained oleic acid methyl ester showed 89.1, which was equal to the theoretical iodine value of oleic acid methyl ester calculated from the starting oleic acid.
[0060]
Example 4
The esterification reaction was carried out in the same manner as in Example 3 except that 4,200 kg of stearic acid (trade name “Stearic acid 300” manufactured by Shin Nippon Rika Co., Ltd.) was used, and 4395 kg of stearic acid methyl ester having an acid value of 0.2 (molar yield) 99.6%). At this time, the entire amount of methyl alcohol generated in the latter two hours was collected in the tank. The methyl alcohol was 1500 kg and the water content was 1.5% by weight.
Next, 4200 kg of stearic acid (manufactured by Nippon Rika Co., Ltd., trade name: "stearic acid 300") was charged, and the ester was recovered in the same manner as in Example 3 using methyl alcohol having a water content of 1.5% by weight. The acid value was 13 after 2 hours. Further, methyl alcohol having a water content of 0.05% by weight was introduced for 2 hours to obtain 4395 kg (molar yield: 99.6%) of stearic acid methyl ester having an acid value of 0.2.
[0061]
Example 5
The reaction was carried out in the same manner as in Example 1 except that methyl alcohol having a water content of 2.0% by weight and the introduction time of methanol was changed to 6 hours, and 4399 kg of lauric acid methyl ester having an acid value of 0.8 ( Molar yield 97.9%).
[0062]
Example 6
The reaction was carried out in the same manner as in Example 1, except that methyl alcohol having a water content of 0.5% by weight was used, and the methanol introduction time was changed to 4 hours. Yield 98.0%).
[0063]
Example 7
The reaction was carried out in the same manner as in Example 1 except that 4200 kg of sebacic acid was used as the fatty acid, to obtain 4706 kg of dimethyl sebacic acid having an acid value of 0.2 (molar yield: 98.4%).
[0064]
【The invention's effect】
According to the method of the present invention, a fatty acid lower alkyl ester having an acid value of a certain level or less can be efficiently obtained by non-catalytic esterification of a fatty acid and a lower alcohol.

Claims (9)

A method for producing a fatty acid lower alkyl ester by subjecting a fatty acid and a lower alcohol to a non-catalytic esterification reaction, wherein the fatty acid is charged into a reaction vessel, and then the lower alcohol is converted into a gaseous or liquid form, continuously or intermittently. The fatty acid and / or fatty acid lower alkyl in the mixed vapor of the lower alcohol-produced water while continuously or intermittently removing the produced water from the system together with the lower alcohol under pressure under pressure. A method for producing a fatty acid lower alkyl ester, comprising condensing ester vapor with a decomposer, returning the recovered fatty acid and / or fatty acid lower alkyl ester to the reaction system, and performing an esterification reaction while circulating. The method for producing a fatty acid lower alkyl ester according to claim 1, wherein a lower alcohol having a water content of 1.0% by weight or less is introduced. 3. The fatty acid lower alkyl ester according to claim 1, wherein a lower alcohol having a water content of 1.0% by weight or less is introduced after the acid value of the esterification reaction crude reaches 20 or less. Production method. After the acid value of the crude esterification reaction reaches 20 or less, the acid value of the crude esterification reaction product is reduced to the recovered lower alcohol generated when a lower alcohol having a water content of 1.0% by weight or less is introduced. The method for producing a lower alkyl ester of a fatty acid according to any one of claims 1 to 3, wherein the method is introduced into 20 or more of the reaction crude products. The lower fatty acid according to any one of claims 1 to 4, wherein a lower alcohol having a water content of 0.2% by weight or less is introduced after the acid value of the crude esterification reaction reaches 5 or less. A method for producing an alkyl ester. The method for producing a lower alkyl fatty acid ester according to any one of claims 1 to 6, wherein the lower alcohol is introduced in an amount of 0.1 to 0.4 t / h based on 1 t of the crude esterification reaction. The method for producing a fatty acid lower alkyl ester according to any one of claims 1 to 7, wherein the reaction pressure is 0.2 to 5 MPa and the reaction temperature is 200 to 300 ° C. The method for producing a fatty acid lower alkyl ester according to any one of claims 1 to 7, wherein the fatty acid is a saturated fatty acid having 8 to 36 carbon atoms and / or an unsaturated fatty acid, and the lower alcohol is methyl alcohol. A fatty acid methyl ester having an acid value of 1 or less obtained by the production method according to claim 8.