JP2002265986A - Method for producing fatty acid alkyl ester and glycerin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for efficiently producing a purified fatty acid alkyl ester and glycerin in simple facilities by the transesterification reaction between fats and oils and an alcohol with the use of an alkali as the catalyst. SOLUTION: The method for producing a fatty acid alkyl ester and glycerin by subjecting fats and oils and an alcohol to transesterification reaction comprises a step of adding an alkali-containing alcohol solution having a water content of <=1 wt.% to fats and oils to effect transesterification reaction at a reaction temperature of 10-65 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method of esterifying a fat or oil (fatty oil and / or fat) with an alcohol,
The present invention relates to a method for producing a fatty acid alkyl ester and glycerin. According to the present invention, a fatty acid alkyl ester useful as a cutting oil, a lubricating oil, a petroleum alternative energy, or the like can be efficiently produced from a vegetable oil, an animal oil, a waste edible oil, or the like as a raw material. Further, the production method of the present invention relates to a method for producing glycerin, which includes a step of separating and recovering glycerin by-produced during esterification of fats and oils.

[0002]

2. Description of the Related Art When a fat or oil such as a vegetable oil is transesterified with an alcohol, a fatty acid alkyl ester is formed, and glycerin is by-produced. The fatty acid alkyl ester esterified using methanol or ethanol as the alcohol has a molecular weight of about 1/3 lower than that of the original fat and oil, and has a lower flash point and lower viscosity. This fatty acid alkyl ester exhibits properties such as viscosity and calorific value close to light oil, high volatility, good spraying properties in the engine, and carbon deposits are suppressed,
It is attracting attention as an alternative energy source to petroleum such as automotive fuel.

[0003] Further, fatty acid alkyl esters produced by the transesterification method are well wetted by metals and can lower the interfacial tension. Therefore, they can be used alone or, if necessary, mixed with a surfactant. It can be used as cutting oil or lubricating oil.

[0004] On the other hand, glycerin is mainly recovered and purified from a waste liquid in a soap production process, or is synthesized from propylene as a raw material by an epichlorohydrin method, an acrolein method, a peracetic acid method, or the like. However, all of these methods require complicated steps, have low yields, and are limited in reducing the cost of glycerin. for that reason,
Glycerin by-produced during the esterification of fats and oils has attracted attention.

[0005] Conventionally, as a method of esterifying oils such as vegetable oils, for example, a method of transesterifying vegetable oils with methanol has been known. This transesterification produces fatty acid methyl esters and glycerin. The reaction temperature is from normal temperature to about 130 ° C., and the reaction pressure is generally normal pressure (1 atm). The reaction time is usually about several hours. As raw material fats and oils, animal oils, waste oils (eg, waste cooking oils), and the like have been studied in addition to various vegetable oils. In addition to methanol, lower alcohols such as ethanol have been studied as alcohols. In the transesterification reaction, usually, sodium hydroxide,
An alkali such as potassium hydroxide has been used as a catalyst. A method of performing a transesterification reaction at a high temperature and high pressure of 200 ° C. and a reaction pressure of 50 atm without an alkali catalyst has also been proposed.

[0006] Among these conventional esterification methods, high temperature
The method of reacting at high pressure requires special expensive equipment. The method using an alkali as a catalyst has excellent characteristics as an esterification method of fats and oils, but has the following problems. That is, when an oil is transesterified with an oil and a fat using an alkali as a catalyst, a reaction mixture containing an unreacted alcohol, an alkali, a fatty acid alkali metal salt, and the like is obtained in addition to the fatty acid alkyl ester of the reaction product and glycerin. Therefore, complicated steps are required to separate and purify each component, and the energy efficiency is not good.

More specifically, when a transesterification reaction is carried out between an oil and a fat and an alcohol, a fatty acid alkyl ester and glycerin are produced, but they are separated into a phase containing the fatty acid alkyl ester and a phase containing glycerin in the reactor. .
When the reaction mixture is allowed to stand, these phases are separated into upper and lower layers, and the upper layer becomes the fatty acid alkyl ester phase. Each of these phases contains unreacted alcohol, residual alkali, fatty acid alkali metal salts of by-products, and the like.

In the prior art, the residual alkali in the reaction mixture is neutralized if necessary and then removed by washing with a large amount of water. The washing step is repeatedly performed by a batch operation. By washing, alkalis and fatty acid alkali metal salts contained in the fatty acid alkyl ester phase move to the glycerin phase together with water. After the washing, the separated glycerin phase is diluted with a large amount of water. Therefore, water is separated and removed by a distillation operation to recover purified glycerin. Alcohol is also recovered by distillation. Therefore, a multi-stage distillation process is often arranged. In order to remove water by a distillation operation, a large amount of energy is required, and the larger the amount of washing water mixed, the more energy is required.

When the glycerin phase is neutralized, the fatty acid alkali metal salt becomes a fatty acid and separates on the glycerin phase. The fatty acid phase can be separated by decantation, but if the glycerin phase contains a large amount of water, it tends to be difficult to separate the fatty acid.

When a large amount of water is contained in raw materials such as fats, alcohols, and alkalis, not only the transesterification reaction becomes insufficient, but also a fatty acid alkali metal salt is easily formed. Since the fatty acid alkali metal salt acts as a surfactant in the presence of oil and water, it inhibits the phase separation between the fatty acid alkyl ester and glycerin. As the amount of water in the reaction system increases, such a problem becomes more remarkable, resulting in a complicated apparatus and a lower yield.

Furthermore, when the amount of water in the reaction system increases,
Since it is difficult to uniformly dissolve the raw material fat and oil and the alcohol, a stirring operation is indispensable, and a reaction by a batch system is indispensable. For mass production of fatty acid alkyl esters and glycerin, production in a continuous production process is desirable. As described above, the conventional method for esterifying fats and oils using an alkali as a catalyst requires a complicated production process, does not necessarily have a high yield, and consumes a large amount of energy.

[0012]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for efficiently producing a purified fatty acid alkyl ester and glycerin by simple equipment by subjecting a fat or oil to a transesterification reaction with an alcohol using an alkali as a catalyst. Is to do.

The present inventor has conducted intensive studies to achieve the above object. As a result, the transesterification reaction was carried out under substantially anhydrous conditions by adding an alkali-containing alcohol solution having a water content of 1% by weight or less to fats and oils. After the reaction, a method was found in which the reaction mixture was phase-separated into a fatty acid alkyl ester phase and a glycerin phase while maintaining a substantially anhydrous state or in the presence of a very small amount of water after the reaction.

According to this method, the glycerin phase can be separated from the reaction mixture without being diluted with a large amount of washing water. The separated glycerin phase can be purified by distillation after neutralizing the residual alkali. However, since the amount of water is small, the energy consumed for distillation can be suppressed.

After the fatty acid alkyl ester phase is separated, the remaining glycerin and alkali can be removed by adding a small amount of water. If a small amount of residual water is suspended in the fatty acid alkyl ester,
After maintaining the temperature at 35 to 70 ° C., by cooling, the water can be settled and separated. The method of the present invention is also suitable for a continuous method for producing fatty acid alkyl esters.

According to the method of the present invention, fatty acid alkyl esters and glycerin can be produced relatively easily and inexpensively from fats and oils such as vegetable oils. The resulting fatty acid alkyl ester can be used alone or as a mixture with light oil as a light oil substitute fuel. When a mixture of fatty acid alkyl ester and light oil is used as a light oil substitute fuel, petroleum-based fine particles and black smoke in exhaust gas can be significantly reduced. Even if the fatty acid alkyl ester is used alone, the combustion efficiency does not decrease compared to light oil,
Petroleum-based fine particles and black smoke in exhaust gas can be further reduced. Fatty acid alkyl esters are also useful as cutting oils and lubricating oils.

[0017] Purified glycerin can be used as an inexpensive chemical. The by-produced fatty acid is a mixture of several kinds of fatty acids, which are fractionated and recovered as a single acid (for example, stearic acid, lauric acid, etc.), and are used as plasticizers and stabilizers for synthetic resins, metal soaps, synthetic rubbers. It can be used as a raw material of an emulsifier, a surfactant and the like. The present invention has been completed based on these findings.

[0018]

According to the present invention, there is provided a method for producing a fatty acid alkyl ester and glycerin by subjecting a fat or oil and an alcohol to a transesterification reaction.
(1) a step of adding an alkali-containing alcohol solution having a water content of 1% by weight or less to a fat and oil to cause a transesterification reaction at a reaction temperature of 10 to 65 ° C, and (2) containing a fatty acid alkyl ester and glycerin generated by the transesterification reaction. The reaction mixture is mixed with a crude fatty acid alkyl ester phase (A) and a crude glycerin phase containing glycerin and a fatty acid alkali metal salt.
(B) a step of separating the crude fatty acid alkyl ester phase (A) and the crude glycerin phase (B) from each other; (4) a separated crude fatty acid alkyl ester phase ( In the crude fatty acid alkyl ester obtained from A),
0.1 to 15% by volume of water is added to the fatty acid alkyl ester phase (A-1) and an aqueous phase containing glycerin and alkali remaining in the crude fatty acid alkyl ester.
(5) phase-separating the fatty acid alkyl ester phase (A-1) and the aqueous solution phase (A-2) into a fatty acid alkyl ester phase (A- Recovering fatty acid alkyl ester from 1), (6) step (3)
Neutralization by adding an acid to the crude glycerin obtained from the crude glycerin phase (B) separated in the above step or a mixture of the crude glycerin and the aqueous solution obtained from the aqueous phase (A-2) separated in the step (5). And then separating the glycerin phase (B-1) and the fatty acid phase (B-2), and (7) separating the phase-separated glycerin phase (B-1) and the fatty acid phase (B-2). And a method for producing a fatty acid alkyl ester and glycerin, comprising a step of separating an aqueous glycerin solution from the glycerin phase (B-1).

According to the present invention, there is further provided a method for producing a fatty acid alkyl ester and glycerin by subjecting a fat and an alcohol to a transesterification reaction, wherein (I) the fat and the fat and an alkali-containing alcohol solution having a water content of 1% by weight or less. A step of continuously supplying to the reactor and subjecting to a transesterification reaction at a reaction temperature of 10 to 65 ° C and a residence time of 5 minutes to 24 hours;
(II) a step of continuously extracting a reaction mixture containing the fatty acid alkyl ester and glycerin produced by the transesterification reaction from the reactor, and (III) applying a centrifugal force to the reaction mixture extracted from the reactor to obtain a crude fatty acid alkyl. A step of phase separation into an ester phase (A) and a crude glycerin phase (B) containing glycerin and a fatty acid alkali metal salt, and (I)
V) A continuous method for producing fatty acid alkyl esters and glycerin, comprising a series of steps comprising a step of separating a phase-separated crude fatty acid alkyl ester phase (A) and a crude glycerin phase (B) from each other.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Fats and oils In the present invention, vegetable fats and animal fats and oils can be used as fats and oils. As fats and oils, fat oils (vegetable oils, animal oils) and solid fats (solid fats) that are liquid at normal temperature can be used. These fats and oils can be used alone or
It can be used as a mixture of more than one species.

Examples of animal fats and oils include fats and oils having a fatty acid triglyceride molecular structure, such as beef tallow, lard, horse fat, fish oil and whale oil. Fish oils include not only fish but also oils and fats extracted from crabs, shrimp, offshore amy, amy, zooplankton, and the like. These animal fats and oils can also be used by mixing with vegetable fats and oils.

Examples of vegetable oils and fats include oils and fats having a fatty acid triglyceride structure, such as soybean oil, rapeseed oil, sunflower oil, cottonseed oil, coconut oil, sesame oil, peanut oil, and camellia oil. In addition, oils and fats extracted from fruit pulp and seeds such as apocad and olives, and various other vegetable oils and fats used as raw materials for soaps are also included. Most of the waste oil recovered from tempura oil and the like is derived from vegetable oils such as soybean oil and rapeseed oil, and such waste oil can also be used as a raw material. Edible nuts and oils from plant seeds can also be used.

The fats and oils can be used as raw materials as they are, but when they contain water, it is desirable to carry out heat dehydration beforehand. Heat dehydration treatment
It can be carried out by heating the fat or oil to 40 ° C. or higher, preferably 50 ° C. or higher, more preferably 65 ° C. or higher. The heat treatment temperature is not more than the thermal decomposition temperature of fats and oils. By the heat treatment, the water contained in the fat or oil evaporates. When the amount of water in the fat or oil is large and the heat treatment temperature is as low as 100 ° C. or lower, the water is separated by the heat treatment and accumulates in the lower layer of the fat and oil.

2. Alkali-containing alcohol solution In the present invention, the water content is 1% by weight or less, preferably 0.5% by weight or less.
The esterification of the fats and oils is carried out using an alkali-containing alcohol solution of up to 0.2% by weight, more preferably up to 0.2% by weight.

As the alkali used in the present invention, for example, potassium hydroxide (KOH), sodium hydroxide (N
aOH), calcium hydroxide [Ca (OH) ₂ ] and the like. Among them, potassium hydroxide is particularly preferable because the reaction rate is high and a uniform fatty acid alkyl ester layer is easily formed. These alkalis are usually dissolved in the alcohol as anhydrous solids such as flakes or pellets.

The alcohol is preferably a monohydric lower alcohol having 1 to 4 carbon atoms, such as methanol, ethanol, n-propanol, isopropanol and n-butanol, and more preferably methanol and ethanol. Methanol is particularly preferred from the viewpoints of reaction control, ease of phase separation, and properties of the resulting fatty acid alkyl ester. The alcohol is preferably of an anhydrous grade. An anhydrous grade means that the water content is usually 1% by weight or less,
Preferably 0.5% by weight or less, more preferably 0.2% by weight or less of alcohol is meant.

By dissolving anhydrous solid alkali in anhydrous grade alcohol, the water content is 1% by weight or less, preferably 0.5% by weight or less, more preferably 0.1% by weight or less.
A 2% by weight or less alkali-containing alcohol solution is prepared. If a large amount of water is present in the solution, inconveniences such as a decrease in the catalytic activity of the alkali, formation of a fatty acid alkali metal salt, and a long reaction time are likely to occur.

In the alkali-containing alcohol solution, the concentration of the alkali is usually 1 to 12% by weight, preferably 1.
It is 5 to 10% by weight, more preferably 2 to 5% by weight.
If the alkali concentration of this solution is too high, the alkali is less likely to be dissolved in the alcohol, and further, the selectivity of the esterification reaction is deteriorated, and the fatty acid alkali metal salt is easily formed. If the alkali concentration of the solution is too low, the transesterification reaction requires a long time, and the phase separation between the fatty acid alkyl ester and glycerin tends to be insufficient.

3. Production Method The transesterification reaction between an oil and a fat and an alcohol may be a batch type or a continuous type. Hereinafter, the basic manufacturing process will be described, focusing on the batch type. In the step (1), an alkali-containing alcohol solution having a water content of 1% by weight or less is added to the fat or oil, and a transesterification reaction is performed at a reaction temperature of 10 to 65 ° C. It is preferable to use oils and fats that do not substantially contain dehydrated (preferably heat-dehydrated) water. The reaction is preferably carried out while uniformly stirring the fat or oil and the alkali-containing alcohol solution.

The reaction temperature is usually lower than the boiling point of the alcohol used, preferably 15 to 60 ° C, more preferably 20 to 50 ° C, and particularly preferably 25 to 40 ° C.
° C. If the reaction temperature is too high, the alcohol evaporates from the reaction system, the amount of by-products increases, or the phase separation (precipitation) of glycerin tends to be hindered. If the reaction temperature is too low, the reaction requires a long time and is not efficient. However, do not leave unreacted oils and fats,
Alternatively, the reaction temperature at or after the end of the reaction or at the end of the reaction may be raised to a temperature of 60 ° C. or higher and lower than the boiling point of the alcohol, for example, in order to promote the phase separation between the fatty acid alkyl ester and the glycerin after the reaction. preferable.

The reaction time varies depending on the alkali concentration of the alkali-containing alcohol solution used, the reaction temperature, etc., but is usually from 10 minutes to 24 hours, preferably from 15 minutes to 10 hours, more preferably from 20 minutes to 6 hours, particularly Preferably it is 25 minutes to 3 hours. Often three
The reaction is desirably performed for about 0 minute to 1 hour. The reaction time does not need to be unnecessarily long, and the reaction can be efficiently performed in a relatively short time by using an alkali-containing alcohol solution having a water content of 1% by weight or less.

This reaction can be carried out using a reactor equipped with a stirrer. If desired, each raw material can be continuously used using a continuous reactor such as a vertical reactor (for example, a pipe reactor). The reaction may be carried out by feeding the reaction product into the reactor and continuously extracting the reaction product.

When an alkali-containing alcohol solution having a water content of 1% by weight or less is added to the fat and oil and a transesterification reaction is performed at a reaction temperature of 10 to 65 ° C., a transesterification reaction occurs between the fat and oil (fatty acid triglyceride) and the alcohol,
Fatty acid alkyl esters and glycerin are produced. When a potassium hydroxide-containing methanol solution is used as the alkali-containing alcohol solution, fatty acid methyl esters and glycerin are generated, and fatty acid alkali metal salts are generated as by-products.

The alcohol is added to the reaction system as an alkali-containing alcohol solution. It is preferable to use the alcohol in a ratio that is in excess of the stoichiometric amount required for the transesterification reaction with the fat or oil. In particular,
In the step (1), the stoichiometric number of moles required for the transesterification reaction between the fat and oil and the alcohol is 3 to 15 or more.
It is preferred to add an alkali-containing alcohol solution containing a molar excess of alcohol. The number of excess moles is
More preferably 5 to 10 mol%, further preferably 6 to
8 mol%. If the proportion of the alcohol used is too small, unreacted fats and oils will remain and fatty acid alkali metal salts are likely to be produced. If the use ratio of alcohol is excessive, the amount of energy required for collecting and recycling alcohol increases.

In the step (2), the reaction mixture containing the fatty acid alkyl ester and glycerin produced by the transesterification reaction is mixed with the crude fatty acid alkyl ester phase (A),
The phase is separated into a crude glycerin phase (B) containing glycerin and a by-product such as a fatty acid alkali metal salt. After completion of the transesterification, the reaction mixture is cooled and allowed to stand to separate into a crude fatty acid alkyl ester phase (A) in the upper layer and a crude glycerin phase (B) in the lower layer. Using a centrifuge, etc.
The two can also be phase-separated by applying centrifugal force to the reaction mixture.

The phase separation can be carried out without adding water to the reaction mixture. However, when a small amount of water of about 0.01 to 5% by volume is added to the reaction mixture, the phase separation may be sometimes promoted. When a residual alkali is present in the crude fatty acid alkyl ester phase (A), a small amount of water is added, and the residual alkali dissolved in the water is transferred to the crude glycerin phase (B). However, if a large amount of water is added at this stage, the crude glycerin phase
Since the amount of water in (B) increases and a large amount of energy is required for the purification of glycerin by distillation, it is not preferable. When water is added to promote phase separation, the content is more preferably about 0.05 to 4% by volume, and still more preferably about 0.1 to 3% by volume.

The promotion of phase separation by the addition of a small amount of water and the removal of residual alkali from the crude fatty acid alkyl ester phase (A) can be carried out once or a plurality of times. Further, as water, the alcohol content is 50% by volume or less, preferably 3% by volume.
An alcohol aqueous solution of 0% by volume or less, more preferably 20% by volume or less can be used. It is not preferable that the amount of alcohol in the alcohol aqueous solution is large because the alcohol is phase-separated in the upper layer of the crude fatty acid alkyl ester phase (A) or suspended in the crude fatty acid alkyl ester phase (A).

In step (3), the crude fatty acid alkyl ester phase (A) and the crude glycerin phase (B) separated in phase (2)
Are separated from each other. According to the production method of the present invention, both phases are difficult to dissolve each other, so that clear phase separation is likely to occur. In order to separate them from each other, the reaction mixture is allowed to stand in a reactor or a settling tank to separate phases, and the crude glycerin phase (B) is withdrawn from the bottom or the crude fatty acid alkyl ester phase (from the upper or middle stage). A) can be extracted.
Each phase may be extracted as a separate stream while applying a centrifugal force to the reaction mixture to separate phases using a continuous centrifuge or the like.

In the step (4), 0.1 to 15% by volume of water is added to the crude fatty acid alkyl ester obtained from the separated crude fatty acid alkyl ester phase (A),
The phase is separated into a fatty acid alkyl ester phase (A-1) and an aqueous solution phase (A-2) containing glycerin and alkali remaining in the crude fatty acid alkyl ester phase (A). The crude fatty acid alkyl ester phase (A) separated in the step (3) often contains a small amount of glycerin, alkali or the like as impurities. In particular, in a method in which a reaction mixture is allowed to stand and a phase is separated using a reactor or a sedimentation tank, it is difficult to avoid entry of a small amount of impurities.

In order to recover a high-purity fatty acid alkyl ester, the crude fatty acid alkyl ester has a
15% by volume of water is added. At this stage, a relatively large amount of water can be used because most of the added water is phase-separated into the lower layer. However, if the amount of water used is too large, it is not preferable because a large amount of energy is required for the distillation operation and the like in order to separate, purify, and recycle each component from the phase-separated aqueous phase.

In this step (4), water can be added as an aqueous solution containing 50% by volume or less of alcohol. When an aqueous solution containing alcohol is used,
It becomes easy to mix water into the crude fatty acid alkyl ester. However, a large amount of alcohol in the alcohol aqueous solution is not preferable because the alcohol is phase-separated in the upper layer of the crude fatty acid alkyl ester or suspended in the crude fatty acid alkyl ester. As the alcohol aqueous solution,
It is desirable to use an alcohol aqueous solution having an alcohol content of preferably 30% by volume or less, more preferably 20% by volume or less.

Water (including the case where it is added as an aqueous alcohol solution) is added to the separated crude fatty acid alkyl ester, and the mixture is stirred for about 30 minutes to about 1 hour. And alkali dissolve in water, and when left standing, phase separation occurs as an aqueous solution phase (A-2) in the lower layer. The upper layer contains the fatty acid alkyl ester phase (A
-1). The phase separation in this step can also be performed using a centrifugal separator, a cyclone, or the like, and utilizing centrifugal force. Washing by addition of water can be performed once or multiple times.

In the step (5), the fatty acid alkyl ester phase (A-1) and the aqueous solution phase (A-2) are separated from each other, and the fatty acid alkyl ester is recovered. Since the recovered fatty acid alkyl esters are sufficiently refined, they can be used for a wide range of applications such as petroleum alternative energy, cutting oil, and lubricating oil. The degree of alkali removal can be determined by examining the pH of the recovered fatty acid alkyl ester. If the pH shows neutrality, it can be determined that it is an alkali-free fatty acid alkyl ester.

In the fatty acid alkyl ester recovered in the step (5), an extremely small amount of water or water containing alcohol may be suspended. In such a case, it is preferable that the recovered fatty acid alkyl ester is allowed to stand at a temperature of 35 to 70 ° C. and then cooled to a temperature of less than 35 ° C. to remove residual moisture by settling. More preferably, the fatty acid alkyl ester recovered in step (5) is heated to 50 to 70 ° C. and held for about 30 minutes to 24 hours. If the holding temperature is too low, it becomes difficult to sufficiently separate the water, and the fatty acid alkyl ester may show weak alkalinity due to the alkali dissolved in the water. The water that has settled in the lower layer can be easily separated and removed by extracting it from the bottom of the reactor or the settling tank, or by performing a tilting operation.

In the step (6), the crude glycerin obtained from the crude glycerin phase (B) separated in the step (3) is neutralized by adding an acid or separated from the crude glycerin in the step (5). The aqueous solution obtained from the aqueous solution phase (A-2) is mixed, and the obtained mixture is neutralized by adding an acid. When an acid is added to the crude glycerin or the mixture, the residual alkali is neutralized, and the fatty acid alkali metal salt becomes a fatty acid, which is separated and precipitated. In this way, the mixture is phase-separated into a glycerin phase (B-1) and a fatty acid phase (B-2).

In the step (7), the phase-separated glycerin phase (B-1) and fatty acid phase (B-2) are separated from each other, and glycerin or an aqueous glycerin solution is recovered from the glycerin phase (B-1). . A mixture of the crude glycerin and the aqueous solution separated in the step (5) is neutralized with an acid and then phase-separated, and then the glycerin phase is separated to obtain an aqueous glycerin solution. On the other hand, fatty acids are recovered from the fatty acid phase (B-2). Since the fatty acids are a mixture, they can be fractionated to obtain a single fatty acid.

When the glycerin aqueous solution is passed through the activated clay layer, a decolorized transparent glycerin aqueous solution can be obtained. Glycerin can be obtained by distilling glycerin or an aqueous glycerin solution or a decolorized transparent glycerin aqueous solution. During this distillation, water and alcohol evaporate, leaving glycerin. By distilling the transparent glycerin aqueous solution from which the coloring substance has been removed through the activated clay layer, colorless and transparent glycerin can be obtained.

As the acid used in the step (6), an anhydrous acid such as hydrochloric acid gas or sulfuric anhydride is preferably used. Since alkali metal salts such as KCl are precipitated by neutralization with an anhydrous acid, it is preferable to carry out distillation after removing them. As the acid, an acid containing a small amount of water or an aqueous acid solution may be used. In this case, glycerin or an alkali metal salt such as KCl dissolved in the glycerin aqueous solution will precipitate at the bottom of the glycerin distillation column. When the acid contains water, it is separated into an aqueous glycerin solution (containing a neutral alkali salt) and a fatty acid, which facilitates separation, which may facilitate post-treatment. Alcohol is also recovered during the distillation. The collected alcohol can be recycled after dehydration treatment if necessary.

4. Continuous Production Method The production method of the present invention can be carried out continuously using a continuous reactor such as a pipe reactor. The preferred continuous production method of the present invention is as described above.
Hereinafter, a preferred continuous production method will be described in detail. In the step (I), a fat and oil and an alkali-containing alcohol solution having a water content of 1% by weight or less are continuously supplied to a reactor, and a transesterification reaction is performed at a reaction temperature of 10 to 65 ° C and a residence time of 5 minutes to 24 hours. The fats and oils and the alkali-containing alcohol solution may be mixed in advance and then continuously supplied to the reactor.
As the fat or oil, it is preferable to use a fat or oil that has been subjected to heat dehydration treatment in advance. The conditions of the heat dehydration treatment of fats and oils are as described above.

As the alkali-containing alcohol solution, it is preferable to use a substantially anhydrous solution obtained by dissolving anhydrous solid potassium hydroxide in anhydrous grade (water content of 1% by weight or less) methanol. In addition, the mixing ratio of the fat and oil to the alkali-containing alcohol solution is such that the amount of alcohol in the alkali-containing alcohol solution is 3 to 15 moles more than the stoichiometric mole number required for the transesterification reaction between the fat and oil and the alcohol. It is preferable to set the ratio so that the amount becomes excessive.

The oil and fat and the alkali-containing alcohol solution are conveyed by a pump as separate streams. The two are brought into contact with each other by a suction of a pump, and a uniform mixture is obtained by stirring and mixing in the pump. Is preferred. When a continuous reactor such as a pipe reactor is used as the reactor, the mixing in the reactor is not always sufficient because a stirrer may not be provided. Therefore, it is preferable that both are mixed and then continuously supplied to the reactor. Both form a homogeneous solution in a short time.

The reaction temperature is preferably from 15 to 60 ° C, more preferably from 20 to 50 ° C, particularly preferably from 25 to 4 ° C.
0 ° C. The reaction time is preferably from 15 minutes to 10
Time, more preferably from 20 minutes to 6 hours, particularly preferably from 25 minutes to 3 hours. In many cases, the reaction is desirably performed for about 30 minutes to about 1 hour.

The reactor is not particularly limited as long as it is a continuous reactor, but a vertical reactor is used as the reactor.
In the step (I), a mixture of fats and oils and an alkali-containing alcohol solution is supplied from the lower part (lower part), and the next step (I
In I), it is preferable to extract the reaction mixture from the upper part (upper part). In the step (II), a reaction mixture containing the fatty acid alkyl ester produced by the transesterification reaction and glycerin is continuously withdrawn from the reactor.

In the step (III), a centrifugal force is applied to the reaction mixture extracted from the reactor in the step (II), and the crude fatty acid alkyl ester phase (A) and the crude glycerin phase containing glycerin and a fatty acid alkali metal salt are added. (B) and phase separation. To apply a centrifugal force to the reaction mixture, a centrifuge, a cyclone, or the like can be used. When a centrifuge or the like is used, the fatty acid alkyl ester and other components can be phase-separated without adding water to the reaction mixture. However, when a small amount of glycerin or alkali remains in the crude fatty acid alkyl ester phase (A), the reaction mixture is added to the reaction mixture in an amount of 0.01%.
-5% by volume, more preferably 0.05-4% by volume, even more preferably 0.1-3% by volume of water may be added and centrifuged.

In step (IV), the crude fatty acid alkyl ester phase (A) and the crude glycerin phase separated in step (III)
And (B) are separated from each other. The reaction mixture extracted in step (II) is supplied to a continuous centrifugal separator, and centrifugal force is continuously applied to the reaction mixture to separate the crude fatty acid alkyl ester phase (A) and the crude glycerin phase (B). Meanwhile, by continuously extracting the crude fatty acid alkyl ester phase (A) and the crude glycerin phase (B) as separate streams, the steps (III) and (IV) can be performed as a continuous step.

The crude fatty acid alkyl ester obtained by separating from the crude fatty acid alkyl ester phase (A) in the step (IV) is a fatty acid alkyl ester which has been purified to a considerable extent. Contained water may be suspended. In such a case, it is preferable that the recovered fatty acid alkyl ester is allowed to stand at a temperature of 35 to 70 ° C. and then cooled to a temperature of less than 35 ° C. to remove residual moisture by settling. More preferably, fatty acid alkyl ester is 50-70 ° C
And hold it for about 30 to 24 hours. If the holding temperature is too low, it becomes difficult to sufficiently separate the water, and the fatty acid alkyl ester may show weak alkalinity due to the alkali dissolved in the water. The water that has settled in the lower layer can be easily separated and removed by extracting it from the bottom of the reactor or the settling tank, or by performing a tilting operation.

In many cases, 0.1 to 15% by volume of water is added to the crude fatty acid alkyl ester obtained from the crude fatty acid alkyl ester phase (A) separated in the step (IV). It is preferable to arrange an additional step (V) for phase separation into the fatty acid alkyl ester phase (A-1) and the aqueous solution phase (A-2) containing glycerin and alkali remaining in the crude fatty acid alkyl ester. .

The fatty acid alkyl ester phase (A-1) and the aqueous solution phase (A-2) separated in step (V) are separated from each other,
It is preferable to arrange an additional step (VI) for recovering the fatty acid alkyl ester from the fatty acid alkyl ester phase (A-1). Then, after keeping the fatty acid alkyl ester recovered in the step (VI) at a temperature of 35 to 70 ° C. and standing,
It is preferable to arrange an additional purification step to cool to a temperature below 5 ° C. and settle and remove residual moisture.

On the other hand, the crude glycerin phase separated in step (IV)
The crude glycerin obtained from (B) is neutralized by adding an acid, or the crude glycerin is mixed with the aqueous solution obtained from the aqueous phase (A-2) separated in the step (V) to obtain a crude glycerin. The mixture was neutralized by adding an acid, and then the glycerin phase (B-1)
It is preferred to arrange an additional step (VII) for phase separation into the fatty acid phase (B-2). Then, the glycerin phase (B-1) and the fatty acid phase (B-2) separated in the step (VII) are separated from each other, and the glycerin or the glycerin aqueous solution is recovered from the glycerin phase (B-1). Step (VIII) is arranged.

When the glycerin aqueous solution recovered in the step (VIII) is passed through the activated clay layer and decolored, a transparent glycerin aqueous solution can be obtained. The glycerin or the glycerin aqueous solution collected in the step (VIII) or the glycerin aqueous solution collected in the step (VIII) is passed through an activated clay layer, and the decolorized transparent glycerin aqueous solution is distilled to collect glycerin. Distillation volatilizes the water and alcohol, leaving glycerin.

The continuous production method adopts a method in which an acid is added to the crude glycerin separated in the step (IV) to neutralize the residual alkali and to convert the fatty acid alkali metal salt into a fatty acid for precipitation. Even after the separation of fatty acids, glycerin having relatively high purity can be obtained.

As the acid, an anhydrous acid such as hydrochloric acid gas or sulfuric anhydride is preferably used. Since alkali metal salts such as KCl are precipitated by neutralization with an anhydrous acid, it is preferable to carry out distillation after removing them. As the acid, an acid containing a small amount of water or an aqueous acid solution may be used. In this case, glycerin or an alkali metal salt such as KCl dissolved in the aqueous glycerin solution precipitates at the bottom of the glycerin distillation column. When the acid contains water, it is separated into an aqueous glycerin solution (containing a neutral alkali salt) and a fatty acid, and the separation is facilitated, so that the post-treatment may be convenient. Alcohol is also recovered during the distillation. The collected alcohol can be recycled after dehydration treatment if necessary.

5. Fatty acid alkyl esters and uses The fatty acid alkyl esters produced by the method of the present invention can be used alone as a light oil substitute fuel, but a mixture of a fatty acid alkyl ester and gasoline, light oil or alcohol is also used as a petroleum substitute fuel. Can be used. Fatty acid alkyl esters have almost the same fuel efficiency as gasoline and gas oil, and are compatible with them. Alcohols such as methanol can be mixed with fatty acid alkyl esters up to about 20% by volume in the case of anhydrous grades.

Therefore, for example, even if light oil remains in the fuel tank of a diesel vehicle, if a fatty acid alkyl ester is added thereto, it acts as an alternative fuel and the diesel vehicle can be driven as it is. Without modifying the engine, a fatty acid alkyl ester alone or a mixed oil mixed with gasoline, light oil, alcohol or the like can be used as a petroleum alternative fuel.

When the fatty acid alkyl ester obtained by the production method of the present invention is mixed with light oil, petroleum mist-like fine particles and black smoke in exhaust gas can be significantly reduced. When the fatty acid alkyl ester is used alone, not only the fuel efficiency is not reduced as compared with light oil, but also petroleum mist-like fine particles and black smoke in exhaust gas can be further reduced.

The fatty acid alkyl ester obtained by the production method of the present invention can be used as a cutting oil, a lubricating oil, a rust preventive oil, a cleaning oil, and the like. When used for these purposes, various additives such as a surfactant and a metal activator can be added as necessary.

Glycerin is purified and then used for various cosmetics,
Tobacco humectants, foodstuffs, solvents, printing inks, flavors, gunpowder, antifreeze, pharmaceuticals, confectionery, inks, pharmaceuticals, cellophane,
It can be effectively used as a transparent soap, a fiber lubricant, a bonding agent, a photographic paper, a polishing agent, a raw material such as an alkyd resin or a polyurethane.

Since the by-produced fatty acid is generally obtained as a mixture of several kinds of fatty acids, it is fractionated and converted into a single acid (eg, stearic acid, lauric acid, etc.) as a plasticizer or a stabilizer for a synthetic resin. It can be used as a metal soap, a synthetic rubber emulsifier, various surfactants, and the like.

[0069]

The present invention will now be described more specifically with reference to examples and comparative examples. The measuring method of each property is as follows. (1) Methanol solution of 0.1% phenolphthalein with pH 2
An equal amount of a specimen (fatty acid alkyl ester or glycerin, etc.) was added to three drops of water, and the mixture was stirred. Those that did not color were judged to be alkali-free (neutral: pH 7). (2) Fuel Efficiency as an Alternative Fuel to Light Oil The obtained fatty acid alkyl ester was used as a fuel for a passenger car equipped with a diesel engine and having a displacement of 2000 cc, and compared with light oil in fuel consumption when traveling a certain distance.

(3) Measurement of Automobile Exhaust Gas was measured by a filter paper method. Specifically, a fixed flow rate of exhaust gas was passed through a circular filter paper, and comparison was made based on the degree of coloring. (4) Fine Particles Containing Aromatic Compound A certain amount of engine exhaust gas was absorbed in n-hexane, and the amount of aromatic hydrocarbon was measured by gas chromatography. (5) Glycerin It was confirmed from gas chromatography and boiling point (290 ° C.).

[Example 1] Tempura oil was used as an oil or fat. As an alkali-containing alcohol solution, solid anhydrous potassium hydroxide (KOH) was dissolved in methanol having a water content of 0.2% by weight or less to prepare a solution having an alkali concentration of 4% by weight. To 100 g of tempura oil, 13 cc of an alkali-containing alcohol solution (a KOH-containing methanol solution having a water content of 0.2% by weight or less) was added, and the mixture was stirred at 40 ° C. for 30 minutes (0.5 hours) to perform a transesterification reaction. At the end of the reaction, the temperature of the reaction mixture was raised to 60 ° C. to complete the reaction.

To the obtained reaction mixture, 0.1% by volume of water was added, stirred, and allowed to stand. The reaction mixture rapidly separated into two layers, upper and lower. The lower layer (crude glycerin phase) was separated and removed, 10% by volume of water was added to the remaining upper layer liquid (crude fatty acid methyl ester phase), and the mixture was stirred.
It was left still. The aqueous solution that settled in the lower layer was separated and removed. The remaining liquid (fatty acid methyl ester) was heated to 60 ° C.
It was left for 8 hours. The precipitated water was removed to recover the purified fatty acid methyl ester. The purified fatty acid methyl ester had a neutral pH, was alkali-free, and was a transparent liquid.

The crude glycerol obtained from the crude glycerin phase was neutralized by blowing anhydrous hydrogen chloride gas. Fatty acids floating on the upper layer were separated and removed. After removing potassium chloride from the lower layer, glycerin was recovered by distillation. Except for alcohol and water, it was almost glycerin.

On the other hand, the crude glycerin from the crude glycerin phase was mixed with the aqueous solution separated during the purification of the fatty acid methyl ester, and the obtained mixture was neutralized by blowing anhydrous hydrogen chloride gas. Fatty acids floating on the upper layer were separated and removed.
After removing potassium chloride from the lower aqueous glycerin solution, the solution was passed through an activated clay layer to decolorize. The clear glycerin solution was distilled to recover a colorless clear glycerin.

[Examples 2 to 13, Comparative Examples 1 and 2] The transesterification reaction was carried out in the same manner as in Example 1 except that the starting materials, reaction conditions and post-treatment conditions were changed as shown in Table 1. Then, the fatty acid methyl ester and glycerin were recovered. Table 1 shows the results.

[0076]

[Table 1]

[Footnotes] (1) KOH: Flaky anhydrous potassium hydroxide, purity 98% or more. (2) NaOH: anhydrous sodium hydroxide in the form of pellets, purity of 99% or more. (3) MeOH: anhydrous methanol having a water content of 0.2% by weight or less.

[Consideration] As is clear from the results shown in Table 1, when an alkali-containing alcohol solution having a water content of 1% by weight or less is added to fats and oils to cause a reaction, a transesterification reaction occurs. By appropriate selection, purified fatty acid alkyl esters can be obtained (Examples 1 to 13). However, when it is kept at a low temperature of 25 ° C. in a post-treatment step for removing water from the fatty acid alkyl ester (Example 13), a small amount of water remains,
The fatty acid alkyl ester showed weak alkalinity due to the alkali dissolved therein.

On the other hand, a trace amount of alkali in the fatty acid alkyl ester is difficult to remove if the washing step is omitted (Comparative Example 1). If the reaction temperature of the transesterification reaction is too high, a side reaction (formation of a fatty acid alkali metal salt) is likely to occur, which not only hinders separation of glycerin, but also makes separation of alkali components difficult (Comparative Example 2).

The separated glycerin phase was neutralized with anhydrous hydrogen chloride, filtered under reduced pressure with a suction funnel using alkali as alkali chloride, and the filtrate was subjected to atmospheric distillation.
Most of the effluent was at 290 ° C., and most was glycerin as detected by gas chromatography.

Example 14 An experiment was conducted in the same manner as in Examples 1 to 13 except that anhydrous ethanol having a water content of 1% by weight or less was used instead of methanol. The same results as in Examples 1 to 13 were obtained. The experiment was carried out in the same manner as in Examples 1 to 13, except that the alkali concentration was varied between 1 and 12% by weight. Example 1 was carried out at a high alkali concentration, except that the alkali was hardly dissolved in methanol, and the reaction was fast and difficult to control.
~ 12 similar results were obtained. From the viewpoint of easy control of the reaction, about 2 to 7% by weight of potassium hydroxide is considered to be an appropriate concentration in anhydrous methanol.

Example 15 The water content was 0.2% by weight,
The procedure was performed in the same manner as in Example 1 except that methanol changed to 2% by weight and 2% by weight was used. Also, as the water content of the knol increased, the amount of the glycerin phase tended to increase. When the separated crude glycerin is neutralized by adding 1N hydrochloric acid, the fatty acid is separated into an upper layer and the aqueous glycerin solution is separated into a lower layer. When the fatty acid in the upper layer was separated and its amount was measured, assuming that the amount of fatty acid produced when the water content of methanol was 0.2% by weight was 1, it was approximately doubled when the water content was 1% by weight. In the case of 2% by weight, it increased about 3-fold. That is, if the reaction system has a large amount of water, the transesterification reaction is inhibited, and a side reaction is likely to occur.

Example 16 681 kg of waste tempura oil mixed with a little animal oil in a reaction vessel equipped with a stirrer having an internal volume of 1 m ^3.
Was added, and 103 L of an anhydrous methanol solution having a KOH concentration of 4% by weight was added while stirring at 40 ° C.
Stirred for 0 minutes. Next, 2.5% by volume of water was added to the reaction solution, and the mixture was stirred and allowed to stand for phase separation. The crude glycerin phase containing most of glycerin, unreacted alcohol and alkali was removed from the bottom of the kettle, and 2.5% by volume of water was further added to the remaining liquid (crude fatty acid alkyl ester phase) and allowed to stand. As a result, a phase was separated into a fatty acid alkyl ester phase and an aqueous solution phase. The aqueous phase containing a small amount of glycerin and alkali separated into the lower layer was removed, and the remaining fatty acid alkyl ester was heated to 60 ° C. and allowed to stand for 18 hours. The water separated from the lower layer was removed to recover about 640 liters of purified fatty acid methyl ester having a neutral pH. The crude glycerin phase was approximately 130 liters (including water and fatty acid alkali metal salts).

Example 17 Into a 1 m ³ reactor equipped with a stirrer, 681 kg of raw soybean oil which had been heated and dehydrated (heat treated at 80 ° C. for 1 hour and then water was removed) was charged.
103 L of an anhydrous methanol solution having a KOH concentration of 4% by weight was added while stirring at, and the mixture was stirred at 40 ° C. for 30 minutes.
The stirring was stopped, the reaction mixture was withdrawn from the bottom of the reactor, and transferred to the first settling tank.

After the first sedimentation tank was allowed to stand and the phases were separated, the fatty acid methyl ester phase was extracted from the middle stage and returned to the reaction vessel, and a 5% by volume aqueous solution containing methanol of 6% by volume was added thereto. . Next, the mixed solution was withdrawn from the bottom of the reactor and transferred to the second settling tank. The residence time in the reactor is 7
Minutes, the residence time in the first settling tank was 20 minutes, the residence time when passing through the reactor was 5 minutes, and the residence time in the second settling tank was 18 hours. The temperature of the second settling tank was raised to 60 ° C., and left standing for 18 hours. The fatty acid methyl ester phase in the upper layer was a transparent liquid having a neutral pH.

At the bottom of the second settling tank, about 50 liters of methanol (including water) had settled, and about 650 liters of fatty acid methyl ester could be recovered from the upper layer. On the other hand, about 110 liters of glycerin (including alkali metal salts of fatty acids) remained in the first settling tank.

Example 18 In Example 17, the reaction mixture extracted from the bottom of the reactor was transferred to a centrifugal separator instead of being transferred to the first settling tank, and 2,000 rpm.
A centrifugal force of pm was applied to separate the fatty acid methyl ester phase and the glycerin phase. The fatty acid methyl ester phase is separated, transferred again to the centrifuge, and 2,000 rpm
By applying a centrifugal force of m, the fatty acid methyl ester and other components were phase-separated. As a result, a purified purified fatty acid methyl ester having a neutral pH was obtained.

[Measurement of Fuel Efficiency as a Diesel Fuel Alternative Fuel] The fatty acid methyl ester obtained in each example was used as a fuel for a passenger car with a diesel engine equipped with a displacement of 2000 cc and traveled a certain distance for about one month. In terms of consumption, compared to light oil. In all cases, oil consumption was equivalent.

[Measurement of Automobile Exhaust Gas] The exhaust gas of a stopped passenger car was measured by a filter paper method (a fixed amount of exhaust gas was passed through a circular filter paper and compared by coloring degree). As a result, fatty acid methyl ester was used as a fuel. In this case, the carbon particles attached to the circular filter paper were less than half that of a passenger car driven with light oil. In addition, when a certain amount of engine exhaust gas was absorbed into n-hexane using fatty acid methyl ester as fuel and aromatic hydrocarbons were measured by gas chromatography, no aromatic hydrocarbons could be detected.

[Uses of Cutting Oil and Lubricating Oil] The fatty acid methyl ester obtained in each of the examples is easy to spread on the metal surface (low interfacial tension), and when used as a cutting oil, the cutting surface is smooth and the cutting edge is small. Also lasted longer, and the scraped surface was hard to rust. In addition, the metal bolts that were rusted and stuck and did not move were immersed in fatty acid methyl ester and started to move. In addition, fatty acid methyl esters are also useful as metal lubricating oils. When the fatty acid methyl ester and the surfactant are used in combination, the action as a cutting oil or a lubricating oil is further improved.

[Use of glycerin] The glycerin recovered by the production method of the present invention had a freezing point of -20 ° C or less, and could be used as an antifreeze.

[0092]

According to the present invention, fatty acid alkyl esters and glycerin purified from fats and oils can be produced by relatively simple and inexpensive treatment means. Fatty acid alkyl esters obtained by the method of the present invention do not contain fatty acid alkali metal salts or alkalis, can be used as a gas oil alternative fuel, and can significantly reduce harmful substances in combustion exhaust gas. Does not cause health hazards. Fatty acid alkyl esters are also useful as cutting oils, lubricating oils, rust preventive oils, cleaning oils, and the like. Glycerin produced simultaneously by the method of the present invention can be purified by simple means, and can be used for various purposes such as antifreeze.

Claims (24)

[Claims] 1. A method for producing a fatty acid alkyl ester and glycerin by subjecting a fat and an alcohol to a transesterification reaction, wherein (1) an alkali-containing alcohol solution having a water content of 1% by weight or less is added to the fat and oil, and a reaction temperature of 10 to 10%. 6
(2) transesterifying at 5 ° C., (2) converting the reaction mixture containing the fatty acid alkyl ester and glycerin produced by the transesterification reaction into the crude fatty acid alkyl ester phase (A) and the crude glycerin phase containing glycerin and a fatty acid alkali metal salt ( (3) a step of separating the crude fatty acid alkyl ester phase (A) and the crude glycerin phase (B) from each other, and (4) a phase separation of the crude fatty acid alkyl ester phase (A). ) To the crude fatty acid alkyl ester obtained in (1), water at a ratio of 0.1 to 15% by volume is added to the fatty acid alkyl ester phase (A-1), and glycerin and alkali remaining in the crude fatty acid alkyl ester. (5) a phase separation into an aqueous phase (A-2) containing
A step of separating the fatty acid alkyl ester phase (A-1) and the aqueous solution phase (A-2) from each other and recovering the fatty acid alkyl ester from the fatty acid alkyl ester phase (A-1),
(6) Crude glycerin obtained from the crude glycerin phase (B) separated in the step (3), or a mixture of the crude glycerin and the aqueous solution obtained from the aqueous phase (A-2) separated in the step (5) To the glycerin phase (B
(1) a step of phase separation into a fatty acid phase (B-2) and (7)
Separating the phase-separated glycerin phase (B-1) and fatty acid phase (B-2) from each other, and recovering glycerin or an aqueous glycerin solution from the glycerin phase (B-1). Production method. 2. The production method according to claim 1, wherein in step (1), fats and oils previously subjected to heat dehydration treatment are used. 3. The method according to claim 1, wherein in the step (1), a solution in which solid alkali is dissolved in anhydrous grade alcohol at a ratio of 1 to 12% by weight is used as the alkali-containing alcohol solution. 4. The method according to claim 3, wherein the alkali-containing alcohol solution is a substantially anhydrous solution obtained by dissolving solid potassium hydroxide in methanol having a water content of 1% by weight or less. 5. An alkali-containing alcohol solution in the step (1) in an amount of 3-15 mol% of alcohol in excess of a stoichiometric number of moles required for transesterification of fats and alcohols with alcohol. The production method according to claim 1, which is added. 6. In step (2), 0.01 to 5% by volume of water is added to the reaction mixture to form a phase of a crude fatty acid alkyl ester phase (A) and a crude glycerin phase (B). The method according to claim 1, wherein the separation is promoted. 7. The method according to claim 1, wherein in step (4), water is added as an aqueous solution containing 50% by volume or less of alcohol. 8. The fatty acid alkyl ester recovered in step (5) is allowed to stand at a temperature of 35 to 70 ° C.
2. The process according to claim 1, comprising an additional purification step of cooling to a temperature below 5 [deg.] C. to settle and remove residual moisture. 9. The production method according to claim 1, further comprising an additional step of passing the aqueous glycerin solution recovered in the step (7) through the activated clay layer to decolorize the transparent glycerin aqueous solution. 10. An addition method in which glycerin or an aqueous glycerin solution recovered in step (7) or an aqueous glycerin aqueous solution recovered in step (7) is passed through an activated clay layer to distill a decolorized transparent aqueous glycerin aqueous solution to recover glycerin. 2. The method according to claim 1, further comprising the steps of: 11. A method for producing a fatty acid alkyl ester and glycerin by transesterifying an oil and a fat with an alcohol, wherein (I) the oil and the fat and an alkali-containing alcohol solution having a water content of 1% by weight or less are continuously fed into a reactor. Feeding and subjecting the mixture to a transesterification reaction at a reaction temperature of 10 to 65 ° C. and a residence time of 5 minutes to 24 hours. (II) A reaction mixture containing a fatty acid alkyl ester formed by the transesterification reaction and glycerin is continuously fed from the reactor. (III) A centrifugal force is applied to the reaction mixture extracted from the reactor to obtain a crude fatty acid alkyl ester phase (A) and a crude glycerin phase containing glycerin and a fatty acid alkali metal salt.
(B) and a fatty acid alkyl ester comprising a series of steps consisting of (IV) a step of separating the phase-separated crude fatty acid alkyl ester phase (A) and the crude glycerin phase (B) from each other; A continuous method for producing glycerin. 12. The production method according to claim 11, wherein in the step (I), an oil or fat which has been subjected to heat dehydration treatment in advance is used. 13. The process according to claim 11, wherein in the step (I), a substantially anhydrous solution in which solid potassium hydroxide is dissolved in methanol having a water content of 1% by weight or less is used as the alkali-containing alcohol solution. Method. 14. In the step (I), an alkali-containing alcohol solution is used in an amount of an alcohol in an amount of 3 to 15 mol% excess of a stoichiometric number of moles required for a transesterification reaction of an oil and fat with an alcohol. The production method according to claim 11, which is used. 15. A vertical reaction vessel is used as a reactor. In step (I), a mixture of an oil or fat and an alkali-containing alcohol solution is supplied from a lower portion of the vertical reaction vessel, and in step (II), The production method according to claim 11, wherein the reaction mixture is extracted from an upper part of the vertical reaction tank. 16. In step (III), 0.01 to 5% by volume of water is added to the reaction mixture to form a phase of a crude fatty acid alkyl ester phase (A) and a crude glycerin phase (B). The method according to claim 11, wherein the separation is promoted. 17. The reaction mixture extracted in the step (II) is supplied to a continuous centrifugal separator, and a continuous centrifugal force is continuously applied to the reaction mixture by the continuous centrifugal separator so that the crude fatty acid alkyl ester phase (A) and the crude glycerin The steps (III) and (IV) were continued by continuously extracting the crude fatty acid alkyl ester phase (A) and the crude glycerin phase (B) as separate streams while separating the phase into the phase (B). The production method according to claim 11, which is performed as a step. 18. The crude fatty acid alkyl ester obtained from the crude fatty acid alkyl ester phase (A) separated in the step (IV) is added with 0.1 to 15% by volume of water,
The method according to claim 11, further comprising an additional step (V) of phase separation into a fatty acid alkyl ester phase (A-1) and an aqueous solution phase (A-2) containing glycerin and alkali remaining in the crude fatty acid alkyl ester. Production method. 19. The fatty acid alkyl ester phase (A-1) and the aqueous solution phase (A-2) separated in the step (V) are separated from each other, and the fatty acid alkyl ester phase (A-1) is separated from the fatty acid alkyl ester phase (A-1). 19. The method according to claim 18, comprising an additional step (VI) of recovering the ester. 20. The fatty acid alkyl ester recovered in the step (VI) is allowed to stand at a temperature of 35 to 70 ° C.
20. The process according to claim 19, comprising an additional purification step of cooling to a temperature below 5C to settle and remove residual moisture. 21. Crude glycerin phase separated in step (IV)
The crude glycerin obtained from (B) or the mixture of the crude glycerin and the aqueous solution obtained from the aqueous solution phase (A-2) separated in the step (V) is neutralized by adding an acid, and then the glycerin phase is added. Additional step of phase separation into (B-1) and fatty acid phase (B-2)
19. The production method according to claim 18, comprising (VII). 22. The glycerin phase (B-1) and the fatty acid phase (B-2) separated in step (VII) are separated from each other, and glycerin or an aqueous glycerin solution is recovered from the glycerin phase (B-1). 22. The method according to claim 21, comprising an additional step (VIII). 23. The method according to claim 22, further comprising an additional step of passing the aqueous glycerin solution recovered in step (VIII) through an activated clay layer to decolorize the solution, thereby obtaining a transparent aqueous glycerin solution. 24. An addition method in which glycerin or an aqueous glycerin solution recovered in step (VIII) or an aqueous glycerin solution recovered in step (VIII) is passed through an activated clay layer to distill a decolorized transparent aqueous glycerin aqueous solution to recover glycerin. 23. The method according to claim 22, further comprising the steps of: