JPH07310090A - Production of fatty acid methyl ester - Google Patents

Abstract

PURPOSE:To provide a method for safely and efficiently producing a fatty acid methyl ester from an oil and fat raw material. CONSTITUTION:This method for producing a fatty acid methyl ester is composed of the first process for adding methanol in an amount of >=15wt.% based on 100wt.% oil and fat and an alkali in an amount of 0.2-1.5wt.% based on 100wt.% of oil and fat to oil and fat raw material and then stirring these components at 50-64 deg.C, the second process for removing the resultant precipitate after allowing to stand the product or by centrifugation, the third process for heating the supernatant to a boiling point of methanol or above and evaporating and removing methanol, the fourth process for adding water thereto and adding an acid thereto while heating to 70-90 deg.C to neutralize the material and separating and removing water phase among two phases separated into oil phase and water phase, the fifth process for adding water to oil phase, washing the oil phase with water under heating at 70-90 deg.C and separating and removing the water phase and the final process for adding clay to the oil phase while heating to 100-140 deg.C and stirring the mixture and then obtaining purified fatty acid methyl ester.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a fatty acid methyl ester from an oil and fat raw material, and more particularly to a method for safely and efficiently purifying a crude fatty acid methyl ester in a short time.

[0002]

2. Description of the Related Art Conventionally, a method for producing a fatty acid methyl ester from a raw material of fats and oils is known. For example, there is a method of reacting oil and fat (fatty acid triglyceride) with methanol in the presence of an acid or an alkali to obtain a crude fatty acid methyl ester, which is then purified by washing with water or the like. In such a conventional method, there is a method in which the reaction is carried out at a temperature equal to or higher than the boiling point of methanol, or a method in which the reaction product needs to be left standing overnight.

However, in the method of reacting at a temperature above the boiling point of methanol, methanol evaporates during the progress of the reaction,
Operationally dangerous. Further, in the method in which the reaction product needs to be allowed to stand for a whole day and night, it takes a long time for the treatment, and there are inconveniences such as poor productivity.

[0004]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a method capable of safely and efficiently producing a fatty acid methyl ester from an oil / fat raw material. The fatty acid methyl ester produced by the method of the present invention is
It is suitable for use alone or as a mixture with light oil or kerosene as a fuel for a diesel engine.

[0005]

In order to solve such a problem, the method for producing a fatty acid methyl ester of the present invention is characterized by comprising the following steps. (1) 15% by weight or more of methanol as a raw material for fats and oils and 0.2 to 100% by weight of fats and oils.
First step of adding 1.5% by weight of alkali and stirring at a temperature of 50 to 64 ° C. (2) After leaving the product obtained in the first step still or by centrifuging, remove the generated precipitate. Second step (3) The supernatant obtained in the second step is heated to a temperature above the boiling point of methanol to evaporate and remove the methanol. Third step (4) Water is added to the product obtained in the third step. , 70-
After neutralizing by adding an acid while heating at 90 ° C., the fourth phase (5) the oil phase obtained by the fourth step in which the aqueous phase is separated and removed from the two phases separated into the oil phase and the aqueous phase. Add water to 70-90
Fifth step of separating and removing the aqueous phase after washing with water under heating at ℃ (6) Clay was added to the oil phase obtained at the fifth step while heating at 100 to 140 ° C, and the mixture was stirred, filtered and purified. Sixth step of obtaining a modified fatty acid methyl ester

Detailed Description of the Invention The reaction for obtaining a fatty acid methyl ester from a raw material of fats and oils is shown in Chemical formula 1 below .

[Chemical 1] Wherein, R _1, R ₂ and R ₃ are the same or different carbon atoms 14 to 20, predominantly 16 to 18 saturated or unsaturated aliphatic hydrocarbon group.

Specific examples of such fats and oils include corn oil, cottonseed oil, olive oil, soybean oil, sunflower oil, linseed oil, cutting oil, rapeseed oil, peanut oil and sesame oil, or two or more thereof. A mixture of These oil / fat raw materials are not limited to clean ones, and may be waste oil. If waste oil is used, it is suitable as a recycling method.

In the above chemical reaction formula, fatty acid triglyceride which is a raw material of fats and oils reacts with methanol in the presence of an alkali catalyst to produce fatty acid methyl ester which is an ester of fatty acid and methanol and glycerin, and a catalyst residual An alkaline soap is produced. The reaction is carried out under heating. The alkali used as the catalyst is N
Examples thereof include aOH, KOH, Ca (OH) _{2 and the} like.

Each step will be specifically described below. First step: 15% by weight or more of methanol and 100 to 100% by weight of oil and fat, and 0.2 to 1.
It is a step of adding 5% by weight of alkali and stirring at a temperature of 50 to 64 ° C. In this step, the raw material of fats and oils reacts with methanol to produce a fatty acid methyl ester which is a target product. At the same time, glycerin and alkaline soap are produced as impurities, and unreacted methanol remains.

The amount of methanol added is 100% by weight of fats and oils.
15% by weight or more, preferably 15 to 25% by weight. The equivalent amount of methanol in the esterification reaction is about 10% by weight with respect to 100% by weight of fats and oils, but it is necessary to add an excessive amount of methanol in order to accelerate the reaction. If it is less than 15% by weight, the reaction is incomplete and monoglyceride or diglyceride remains.
On the other hand, even if added in excess of 25% by weight, methanol exists in the reaction system in a phase separated state and does not contribute to the reaction.

Alkali acts as a catalyst for the reaction, and its addition amount is 0.2 to 1.5% by weight, preferably 0.3 to 0.5% by weight, based on 100% by weight of the fat and oil. Is the range. If it is less than 0.2% by weight, the effect as a catalyst is insufficient and the reaction is slow. On the other hand, if it is added in an amount exceeding 1.5% by weight, a large amount of soap is produced, which adversely affects the subsequent operation, that is, the heating efficiency in the subsequent steps is deteriorated, the stirring efficiency is deteriorated, and washing with water is performed. It will be necessary to increase the number of times. Considering the balance between the reaction rate and the ease of washing with water, the range of 0.3 to 0.5% by weight is suitable.

The heating temperature is 50 ° C. or higher and lower than the boiling point of methanol, preferably 58 to 62 ° C. Fifty
When the temperature is lower than 0 ° C, the reaction is slow, while when the temperature is higher than the boiling point, methanol is easily vaporized and is highly flammable and dangerous, and the boiling causes boiling, which makes the operation difficult and brings about a stoichiometric ratio of the reaction. 5
The range of 8 to 62 ° C. is preferable because the reactivity is good and the safety is high. The stirring time is about 2 to 30 minutes. It becomes cloudy at the initial stage of the reaction, but becomes transparent when the reaction proceeds and the reaction is completed.

The following second and subsequent steps are the steps of separating and removing impurities from the crude fatty acid methyl ester produced by the reaction in the first step for purification.

The second step is a step of removing the formed precipitate after the product obtained in the first step is allowed to stand still or by centrifugation. Crude fatty acid methyl ester is obtained by such treatment.

The period of standing is not particularly limited, but is preferably about 30 minutes to 1 hour. If the standing time is too short, precipitation will not be sufficient, while if the standing time is too long, the reaction product will be cooled during that time, and the efficiency of the heat treatment in the next step will be poor. It is preferable to remove the precipitate by centrifugation because the operation can be performed in an extremely short time.

Third step In this step, the supernatant obtained in the second step is heated above the boiling point of methanol to evaporate and remove methanol. By this step, unreacted methanol added in excess is removed.

By heating to a temperature above the boiling point of methanol, the methanol dissolved in the supernatant liquid (oil phase) is removed by evaporation. At this time, it may be carried out under normal pressure, but it is preferable to carry out under reduced pressure of, for example, about 0.01 kgf / cm ² from the viewpoint of safety and thermal efficiency because it can be operated at a lower temperature. In addition, when carrying out under normal pressure, it is preferable to carry out at about 65 to 90 ° C., for example, from the viewpoint of safety in operation and thermal efficiency. Heating is continued until the vapor has no odor of methanol.

Fourth step Water is added to the product obtained in the third step to 70-90.
This is a step of neutralizing by adding an acid while heating at 0 ° C., and then separating and removing an aqueous phase of the two phases separated into an oil phase and an aqueous phase. By neutralizing under heating, extremely short time (5 to 5
Since the oil phase and the water phase are separated into two phases in about 10 minutes), the following water washing operation becomes extremely easy.

A proper amount of water added is 0.2 or more of water to 1 part of oil by volume. If the amount of water added is too small, the next neutralization efficiency will decrease. The heating temperature is 70-
The temperature is 90 ° C, preferably about 70 to 80 ° C. Below 70 ° C, even if neutralized, the two phases do not separate well. On the other hand, 9
If the temperature exceeds 0 ° C, it will boil and the operation will be difficult. Therefore, the temperature range is such that the two phases are easily separated and no bubbles are generated.
Heat to ~ 90 ° C. The neutralizing agent is not particularly limited and, for example, hydrochloric acid, sulfuric acid, nitric acid or the like is used.
The end point of neutralization may be known by a PH test paper or a PH meter, or may be detected by the increase in transparency. After the completion of the neutralization reaction, the mixture is allowed to stand for several minutes to separate and remove the aqueous phase.

Fifth step In this step , water is added to the oil phase obtained in the fourth step, washed with water under heating at 70 to 90 ° C., and then the aqueous phase is separated and removed.
More specifically, an appropriate amount of water is added, and the mixture is stirred at a predetermined temperature to dissolve aqueous impurities dissolved in the oil phase, that is, soap, glycerin, etc., in the water phase, and the water phase is separated. This is a step of removing impurities in the oil phase. Such a water washing step may be performed a suitable number of times (for example, 2
Repeat)

The amount of water used for washing with water is suitably 0.2 or more and less than 1 with respect to 1 oil by volume. If the amount of water added is too small, the washing efficiency will be poor, while if it is too large, a large amount of heating energy will be required, which is not preferable. The heating temperature is about 70 to 90 ° C. The reason is the same as that described in the fourth step.

Sixth step In this step, clay is added to the oil phase obtained in the fifth step while heating at 100 to 140 ° C., stirred and filtered to obtain a purified fatty acid methyl ester. That is, it is a step of finally adsorbing and removing the impurities remaining in the oil phase.

The heating temperature is set to 100 to 140 ° C.
If the temperature is lower than 100 ° C., the white clay easily adsorbs water, and if it adsorbs water, the adsorption efficiency of impurities decreases, while if the temperature is too high, a large amount of heating energy is required and the oil deteriorates. This is because there is a risk. The operation may be performed under normal pressure, but is preferably performed under reduced pressure. If it is carried out under reduced pressure, the water adsorbed on the clay can be easily desorbed, and the water in the oil phase can also be boiled to remove the water in the oil phase. The amount of white clay added is about 0.5 to 3% by weight of white clay relative to 100% by weight of oil. If the amount is too small, the effect of removing impurities is insufficient. On the other hand, if the amount is too large, the filtration efficiency is reduced and the cost for disposing of the waste clay (white clay residue) increases, which is not preferable.

The purified fatty acid methyl ester obtained through the above steps has a density of 0.87 to 0.89 g / cm ^3.
(20 ° C.), the clay is a yellow to dark brown liquid having 4.0 to 7.0 cSt (50 ° C.).

[0025]

Example 1 500 g of soybean oil as a raw material for fats and oils was placed in a beaker, 63 g of methanol and 25 g of 10% sodium hydroxide methanol solution (total amount of methanol added was 85.5 g) were added, and the mixture was stirred at 60 ° C. for 30 minutes. To obtain a reaction product,
Let stand for a minute. Impurities of glycerin and sodium soap in the reaction product were precipitated as black precipitates, which were removed to obtain 495 g of a transparent brown-color crude fatty acid methyl ester solution.

Next, this crude fatty acid methyl ester solution was heated to 90 ° C. and continued to be heated until the smell of methanol disappeared. Then, 200 ml of water was added and the mixture was heated to 80 ° C. and 0.5 ml of 18% hydrochloric acid solution was added with stirring to neutralize. After neutralization, the mixture was allowed to stand for 5 minutes and separated into an oil phase and an aqueous phase 2
The aqueous phase was separated off. 200 water again in the oil phase
After adding ml and stirring while heating to 80 ° C., the mixture was allowed to stand for 5 minutes to separate into two phases, and the aqueous phase was removed and washed with water. The same water washing operation was repeated twice.

Next, clay (manufactured by Mizusawa Chemical Industry Co., Ltd.,
5 g (trade name: Galleon Earth NRS) was heated to 120 ° C. and added with stirring to adsorb and remove the final impurities remaining in the oil phase. This was filtered to obtain 460 g of a purified fatty acid methyl ester solution as a final product (yield 91
%). The purified fatty acid methyl ester thus obtained had a density of 0.88 g / cm ³ (20 ° C.) and clay of 4.9 cSt (50
(° C) was a brown liquid.

Example 2 53 g of methanol was added (total amount of methanol added was 75.
5 g) was treated in the same manner as in Example 1 to obtain 460 g of purified fatty acid methyl ester solution (yield 91%).
The purified fatty acid methyl ester thus obtained has a density of 0.
The liquid was a brown liquid with 88 g / cm ³ (20 ° C.) and clay of 4.9 cSt (50 ° C.).

Example 3 103 g of methanol was added (total amount of methanol added was 12 g).
The same procedure as in Example 1 was carried out except that the amount of the purified fatty acid methyl ester solution was 460 g (yield 91).
%). The purified fatty acid methyl ester thus obtained had a density of 0.88 g / cm ³ (20 ° C.) and clay of 4.9 cSt (50
(° C) was a brown liquid.

Example 4 A 10% methanol solution of sodium hydroxide was added in an amount of 10
g, the amount of methanol added was 76.5 g (the total amount of methanol added was 85.5 g, the same as in Example 1), and the same procedure as in Example 1 was carried out to prepare the purified fatty acid methyl ester solution 4
50 g was obtained (89% yield). The purified fatty acid methyl ester thus obtained has a density of 0.88 g / cm ³ (20 ° C.),
The clay was a dark brown liquid of 4.9 cSt (50 ° C).

Example 5 The amount of sodium hydroxide 10% methanol solution added was 75
g, methanol was added in the same manner as in Example 1 except that the added amount of methanol was 18 g (the total added amount of methanol was 85.5 g as in Example 1), and the purified fatty acid methyl ester solution 445 was prepared.
g was obtained (yield 88%). The purified fatty acid methyl ester thus obtained was a brown liquid having a density of 0.88 g / cm ³ (20 ° C.) and clay of 4.9 cSt (50 ° C.).

Example 6 460 g of a purified fatty acid methyl ester solution was obtained in the same manner as in Example 1 except that the reaction temperature between the fat and oil raw material and methanol was 55 ° C. (yield 91%). The purified fatty acid methyl ester thus obtained has a density of 0.88 g / cm ³ (2
Clay was a brown liquid with 4.9 cSt (50 ° C.).

Comparative Example 1 The amount of methanol added was 28 g (the total amount of methanol added was 5 g).
The same treatment as in Example 1 was carried out except that the amount was changed to 0.5 g) to obtain 425 g of a fatty acid methyl ester solution (yield 84%).
The fatty acid methyl ester thus obtained has a density of 0.91.
It was a dark brown liquid with g / cm ³ (20 ° C.) and clay of 12 cSt (50 ° C.), the reaction was incomplete, a large amount of monoglyceride was contained, and the viscosity was high.

Comparative Example 2 The amount of 10% methanol solution of sodium hydroxide added was 5
g, the amount of methanol added was 81 g (the total amount of methanol added was 85.5 g), and the same treatment as in Example 1 was carried out. No reaction occurred in the first step and fatty acid methyl ester was not produced. It was

Comparative Example 3 The amount of sodium hydroxide 10% methanol solution added was 10
The treatment was carried out in the same manner as in Example 1 except that the amount was 0 g (the total amount of methanol added was 90 g). As a result, a gel-like substance was produced in the first step, stirring became impossible, and no further treatment was possible.

Comparative Example 4 When the same treatment as in Example 1 was carried out except that the reaction temperature of the oil and fat raw material and methanol was 45 ° C., the reaction in the first step did not occur and fatty acid methyl ester was not formed. .

The purified fatty acid methyl esters obtained in Examples 1 to 6 above were used as a fuel for a diesel engine (Nissan Diesel Ltd., LD20 type) alone or in combination with kerosene.
When mixed with No. 1 and used, the amount of black smoke generated in the exhaust gas was visually smaller than that when light oil fuel was used.

[0038]

EFFECTS OF THE INVENTION According to the method of the present invention, a fatty acid methyl ester can be produced from oils and fats with less danger during the treatment process, safe operation, less treatment time, and high efficiency. The fatty acid methyl ester obtained by the method of the present invention can be suitably used as a fuel for diesel engines.

Claims (1)

[Claims] 1. A method for producing a fatty acid methyl ester, comprising the following steps. (1) 15% by weight or more of methanol as a raw material for fats and oils and 0.2 to 100% by weight of fats and oils.
First step of adding 1.5% by weight of alkali and stirring at a temperature of 50 to 64 ° C. (2) After leaving the product obtained in the first step still or by centrifuging, remove the generated precipitate. Second step (3) The supernatant obtained in the second step is heated to a temperature above the boiling point of methanol to evaporate and remove the methanol. Third step (4) Water is added to the product obtained in the third step. , 70-
After neutralizing by adding an acid while heating at 90 ° C., the fourth phase (5) the oil phase obtained by the fourth step in which the aqueous phase is separated and removed from the two phases separated into the oil phase and the aqueous phase. Add water to 70-90
Fifth step of separating and removing the aqueous phase after washing with water under heating at ℃ (6) Clay was added to the oil phase obtained at the fifth step while heating at 100 to 140 ° C, and the mixture was stirred, filtered and purified. Sixth step of obtaining a modified fatty acid methyl ester