JP2003055299A - Method for producing fatty acid ester and fuel containing fatty acid ester - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a fatty acid ester, by which the fatty acid ester can be produced from a fat or oil and a monohydric alcohol in a high yield without using sodium hydroxide as a catalyst, and to provide a fuel or the like containing the fatty acid ester. SOLUTION: This method for producing the fatty acid ester is characterized by reacting the fat or oil with the monohydric alcohol in the presence of a catalyst containing one or more compounds selected from the group consisting of manganese oxide and molybdenum oxide in a state where the fat or oil and/or the monohydric alcohol are changed into supercritical states. A Diesel fuel contains a fatty acid ester produced by the above-production method.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a fatty acid ester by reacting fats and oils with a monohydric alcohol, and a fuel, a lubricating oil and a fuel oil additive containing the fatty acid ester obtained by the production method.

[0002]

2. Description of the Related Art Fatty acid esters of fatty acids and monohydric alcohols (hereinafter sometimes simply referred to as "fatty acid esters").
Is used as an industrial raw material, a raw material for pharmaceuticals, and a fuel. In particular, it is used as a diesel fuel as a fuel, and is also used as a lubricating oil that replaces the conventional mineral oil.

The production of fatty acid ester is carried out by transesterification reaction of a monohydric alcohol with an oil or fat whose main component is an ester of fatty acid called glycerin triglyceride.

As a method for producing a fatty acid ester, for example, Japanese Patent Laid-Open No. 7-197047 discloses a method for producing a fatty acid ester used as diesel fuel by reacting waste cooking oil with methanol using caustic soda as a catalyst. Is disclosed. In the publication, the transesterification reaction is carried out at 50 ° C. to 70 ° C. under atmospheric pressure using caustic soda.
It is described that it is carried out at a temperature of ° C. However, since fats and oils react with caustic soda to form soaps, it is necessary to separate the fats and oils in a post-treatment.

Further, in JP-A-61-254255, sodium carbonate and sodium hydrogencarbonate are used as catalysts to heat a fat and an oil and methanol at a boiling point of methanol under normal pressure to react with each other to produce a fatty acid ester. The method of doing is proposed. However, the yield of the fatty acid ester after the reaction for 2 hours was about 75%, and there was a problem that the yield was insufficient.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a fatty acid ester in a high yield from a fat and oil and a monohydric alcohol without using caustic soda as a catalyst, a fuel containing the fatty acid ester, and a lubricant. To provide oil, fuel oil additive.

[0007]

[Means for Solving the Problems]
A method for producing a fatty acid ester by reacting with a polyhydric alcohol, and a catalyst containing at least one selected from the group consisting of manganese oxide and molybdenum oxide, continuing intensive research on fuels, lubricating oils, and fuel oil additives containing fatty acid esters. It was found that a fatty acid ester can be obtained in high yield without using caustic soda as a catalyst if the reaction is carried out under the condition that the oil and fat and / or the monohydric alcohol become a supercritical state in the presence of Came to.

That is, according to the present invention, the oil and fat and / or the monohydric alcohol are brought into a supercritical state in the presence of a catalyst containing at least one selected from the group consisting of manganese oxide and molybdenum oxide. A method for producing a fatty acid ester to be reacted under the following conditions is provided. The present invention also provides a fuel containing the fatty acid ester produced by the production method described above. The present invention also provides a lubricating oil containing the fatty acid ester produced by the production method described above. The present invention also provides a fuel oil additive containing a fatty acid ester produced by the production method described above.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below. In the production method of the present invention, the oil and fat and / or the monohydric alcohol are brought into a supercritical state in the presence of a catalyst containing at least one selected from the group consisting of manganese oxide and molybdenum oxide. React under the following conditions. In the production method of the present invention, oils and fats are mainly fatty acid triglycerides which are esters of fatty acids and glycerin. The phrase "mainly composed of fatty acid triglyceride" means that the fatty acid triglyceride is contained in 50% by weight or more of the fat or oil.

The main reaction of the production method of the present invention is represented by the following reaction formula (2). And / or the monohydric alcohol is reacted under the condition that the supercritical state is reached. In the production method of the present invention, oils and fats are mainly fatty acid triglycerides which are esters of fatty acids and glycerin. The phrase "mainly composed of fatty acid triglyceride" means that the fatty acid triglyceride is contained in 50% by weight or more of the fat or oil.

The main reaction of the production method of the present invention is represented by the following reaction formula (2). (In the formula, R ₁ , R ₂ and R ₃ each independently represent a carbon chain of a fatty acid. The carbon number of R _{1 to} R ₃ differs depending on the type of fat and oil. R ₄ is substituted with a hydrocarbyloxyl group. The optional hydrocarbyl group is shown.)

The fats and oils used in the production method of the present invention may be natural fats and oils or synthetic fats and oils, and typical examples thereof include lard fat, chicken fat, butter fat, beef fat, cocoa butter fat,
Corn oil, peanut oil, cottonseed oil, soybean oil, rapeseed oil, coconut oil, olive oil, safflower oil, linseed oil, coconut oil, oak oil, almond oil, apricot kernel oil, kenaf seed oil, beef bones Fat, black walnut oil, castor oil, taiko oil, cinnabar oil, cod liver oil, cottonseed stearin, sesame oil, deer oil, dolphin oil, sardine oil, mackerel oil,
Examples thereof include, but are not limited to, horse fat, pork fat, bone oil, sheep fat, neatsfoot oil, palm oil, palm kernel oil, porpoise oil, shark oil, sperm whale oil, tung oil and whale oil. Further, a mixture of a plurality of these fats and oils, a fat and oil containing diglyceride and a monoglyceride, and a fat and oil partially modified by oxidation, reduction and the like can also be used. Also,
Unrefined oils and fats that may contain free fatty acids, water, etc., or may be waste edible oil discarded from restaurants, food factories, general households, etc., but appropriate pretreatment may be performed if necessary. preferable. For example, when applying the production method of the present invention to waste oil such as waste cooking oil, if an insoluble solid is mixed with fats or oils, it may cause blockage of the booster pump or pressure control valve, which may hinder production. It is preferable to remove insoluble solids from the oil and fat with a wire net, a filter or the like before supplying to the preheater.

Components other than the fatty acid triglyceride may be mixed in the fats and oils. Specifically, crude oil, heavy oil, light oil, mineral oil, essential oil, coal, fatty acid, sugar, metal powder, metal salt, protein, amino acid, hydrocarbon, flavor, pigment compound, enzyme, perfume, alcohol, fiber, resin, Examples thereof include, but are not limited to, rubber, paint, cement, detergent, aromatic compound, aliphatic compound, soot, glass, earth and sand, nitrogen-containing compound, sulfur-containing compound, phosphorus-containing compound and halogen-containing compound.

The above substances contained in fats and oils may be involved in the reaction, for example, may inhibit the reaction, or may cause blockage of the pipe used in the manufacturing apparatus. When it is a solid having properties, it is preferable to remove it by a technique such as filtration or distillation before the reaction. Examples of the distillation method include, but are not limited to, vacuum distillation, steam distillation, molecular distillation and extractive distillation. In the present invention, as the fats and oils, waste fats and oils or waste edible oils can be used, and from the viewpoint of recycling of wastes, the use of waste fats and oils and waste edible oils is preferable.

The monohydric alcohol used in the production method of the present invention is represented by the general formula R-OH (1) (R is a hydrocarbyl group having 1 to 10 carbon atoms, or a hydrocarbyl group having 2 to 10 carbon atoms and is hydrocarbyloxy. Group represented by the formula (1) represented by (1)
Polyhydric alcohols are preferred.

Examples of the hydrocarbyl group having 1 to 10 carbon atoms in R include an alkyl group, an aralkyl group, an alkenyl group and an alkynyl group.

Examples of the monohydric alcohol in which R is an alkyl group include methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol and s.
Examples include ec-butanol, t-butanol, pentanol, hexanol, cyclohexanol, heptanol and the like.

Examples of the monohydric alcohol in which R is an aralkyl group include benzyl alcohol, α-phenethyl alcohol and β-phenethyl alcohol, and benzyl alcohol is preferable.

As the monohydric alcohol in which R is an alkenyl group, allyl alcohol, 1-methylallyl alcohol, 2-methylallyl alcohol, 3-butene-1-ol, 3-butene-2-ol, etc. And allyl alcohol is preferred.

The monohydric alcohol in which R is an alkynyl group includes 2-propyn-1-ol and 2-butyne-1-.
Examples include ole, 3-butyne-1-ole, 3-butyne-2-ole and the like.

As the monohydric alcohol in which R is a hydrocarbyl group having 2 to 10 carbon atoms and substituted with a hydrocarbyloxyl group, 2-methoxyethanol,
2-methoxypropanol, 3-methoxybutanol, etc. are mentioned.

Of these, as the monohydric alcohol, R is preferably an alkyl group having 1 to 4 carbon atoms. Specifically, methanol in which R is a methyl group, ethanol in which R is an ethyl group, propanol in which R is a propyl group, isopropanol in which R is an isopropyl group, n-butanol in which R is an n-butyl group, R Is an isobutyl group, and R is a t-butyl group, preferably t-butanol, more preferably methanol or ethanol, and most preferably methanol. The purity of the alcohol is not particularly limited, but it is preferably 95% or more, more preferably 98% or more. As the monohydric alcohol, one kind may be used, or two or more kinds may be mixed and used. In addition, the monohydric alcohol includes an optical isomer, when an optical isomer is present.

The supply weight of the monohydric alcohol is 1 to 100 of the theoretical supply weight of the monohydric alcohol calculated according to the following formula.
It is preferably double. (Theoretical supply weight of monohydric alcohol) = {(Supply weight of fat / oil) × (Saponification value of fat / oil) × (Molecular weight of monohydric alcohol)} / 56100 Here, the saponification value of fat / oil is 1 g of fat / oil. This is the value in mg of the amount of potassium hydroxide required for complete saponification. When the supply amount of the monohydric alcohol is less than 1 time the theoretical supply weight, the reaction yield is lowered, which is not preferable, and when it is more than 100 times, the apparatus may become too large, which is not preferable. .

Typical examples of the fatty acid ester produced by the production method of the present invention include valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, undecylic acid, lauric acid, tridecyl acid, Myristic acid, pentadecylic acid, palmitic acid, heptedicylic acid, stearic acid, nonadecanoic acid, arachidic acid, pepenoic acid, lignoceric acid, cerotic acid, heptacosanoic acid, montanic acid, mericinic acid, laxeric acid, crotonic acid, isocrotonic acid, undecylene Acid, oleic acid, elaidic acid, cetoleic acid, erucic acid, brassic acid,
Sorbic acid, linoleic acid, linolenic acid, arachidonic acid,
Examples thereof include, but are not limited to, esters of acids such as propiolic acid, stearolic acid, nervonic acid, ricinoleic acid, (+)-hydronocarbic acid, and (+)-chaulm-gric acid. The alcohol residue of the ester depends on the monohydric alcohol used. For example, when methyl alcohol is used as the monohydric alcohol, methyl ester is obtained, and when ethyl alcohol is used, ethyl ester is obtained. When the fatty acid residue has an optical isomer, the optical isomer is also included. In the production method of the present invention, glycerin is produced in addition to the fatty acid ester.

Next, the catalyst used in the present invention will be described. As the catalyst used in the present invention, at least one selected from the group consisting of manganese oxide and molybdenum oxide is preferable because of high yield. These can be mixed and used, or can be mixed and used with other solids. The amount of the catalyst used is from 0.001 parts by weight to 6 parts by weight with respect to 100 parts by weight of oil and fat.
It is preferably part by weight, more preferably 0.01 to 3 parts by weight.

In the production method of the present invention, the oil and fat and the monohydric alcohol are reacted under the condition that the oil and fat and / or the monohydric alcohol are in a supercritical state. The supercritical state in the present invention means the following states. The substance has three states of gas, liquid, and solid, and further has a fluid phase that does not condense even when pressure is applied at a critical temperature or higher. This state is called a supercritical state. Fluids in the supercritical state exhibit properties different from the normal properties of liquids and gases. The density of supercritical fluid is close to that of liquid, its viscosity is close to that of gas, and its thermal conductivity and diffusion coefficient are intermediate properties of gas and liquid. The transesterification reaction is promoted.

In the manufacturing method of the present invention, the supercritical conditions include the following conditions (a)-(c). (A) Temperature conditions in which a mixture of fat and oil and a monohydric alcohol is in a supercritical state. (B) A temperature condition in which only the monohydric alcohol is in a supercritical state. (C) Temperature conditions in which only fats and oils are in a supercritical state. It is preferable to carry out the reaction under the conditions (a) or (b) above.

In the production method of the present invention, the yield is low under the temperature condition in which neither the oil or fat nor the monohydric alcohol is in the supercritical state. On the other hand, if it exceeds 420 ° C., a decomposition reaction of fats and oils may occur, which is not preferable. A more preferable reaction temperature range is a temperature range of 240 ° C. or higher and 400 ° C. or lower, and further preferably a temperature range of 250 ° C. or higher and 350 ° C. or lower.

As the condition (b), specifically, when methanol is used as the monohydric alcohol, the critical temperature of methanol is 240 ° C., so the reaction is carried out at a temperature of 240 ° C. or higher. When ethanol is used, the critical temperature of ethanol is 243 ° C, so the reaction is performed at a temperature of 243 ° C or higher. When n-propanol is used, the critical temperature of n-propanol is 264 ° C, so the reaction is performed at a temperature of 264 ° C or higher. When using n-butanol, n
-The critical temperature of butanol is 287 ° C, so the temperature is 287 ° C.
The reaction is performed as described above. When isopropanol is used, the critical temperature of isopropanol is 236 ° C, so the reaction is performed at a temperature of 236 ° C or higher. When t-butanol is used, the critical temperature of t-butanol is 233 ° C, so the reaction is performed at a temperature of 233 ° C or higher. When isobutanol is used, the critical temperature of isobutanol is 275 ° C, so the reaction is performed at a temperature of 275 ° C or higher.

The density of the monohydric alcohol in the reaction vessel when the oil or fat of the present invention is reacted with the monohydric alcohol is
The range of 0.01 g / cm ³ to 0.6 g / cm ³ is preferable, and the pressure condition is preferably 0.5 MPa to 25 MPa. More preferably, it is in the range of 8 MPa to 20 MPa. The time for reacting the oil or fat of the present invention with the monohydric alcohol is preferably in the range of 0.1 minutes to 180 minutes, more preferably in the range of 0.5 minutes to 120 minutes. More preferably 1 minute to 60
It is in the range of minutes.

This reaction can be carried out in various reaction modes. For example, the method may be a batch method or a distribution method. Further, in the present invention, the fat and oil and the monohydric alcohol may be uniformly mixed during the reaction, or may be separated into two layers as long as the reaction is possible. When the two layers are separated, for example, the reaction can be carried out more efficiently by increasing the contact area of the two layers by carrying out the reaction with stirring.

The reaction mixture after completion of the reaction contains fatty acid ester, glycerin and excess unreacted monohydric alcohol,
Furthermore, unreacted fats and oils and other impurities may be contained. From this reaction mixture, the fatty acid ester can be purified to the purity required for the respective application. The purification method is not particularly limited, and general methods such as distillation and extraction can be applied depending on the properties of the fatty acid ester produced. For example, when using methanol as the monohydric alcohol, excess (or unreacted) methanol can be vaporized and separated and collected, and then allowed to stand to separate into a light liquid and a heavy liquid. The catalyst used in the present invention is relatively easy to separate from the reaction solution as compared with the caustic soda catalyst, and the post-treatment of the reaction solution is simple. The light liquid contains methyl ester of fatty acid as a main component and can be used as a raw material of diesel fuel or a raw material of higher alcohol for surfactant. The heavy liquid containing glycerin as a main component can be used as a raw material for industrial glycerin.

The unreacted monohydric alcohol can be separated by a method commonly used in the industry. Besides distillation such as vacuum distillation, typical methods include mixer-settler extraction and liquid-liquid extraction. Examples include, but are not limited to, extraction using a pulse column, jet extraction, and Bodwierniak rotation extraction. Further, the monohydric alcohol may be completely separated and only the fatty acid ester may be taken out, or the monohydric alcohol may be recovered in the state where it remains.

The fatty acid ester produced by the production method of the present invention depends on the structure of the starting fat or oil, but when natural fat or oil is used, it is generally a mixture of several fatty acid esters. In this case, the mixture may be used as it is depending on the application, or if necessary, only the specific fatty acid ester may be separated and used by a general method such as distillation or extraction.

The fatty acid ester produced by the production method of the present invention may be used alone or in a mixture with other components in fuels such as diesel fuel, lubricating oils, fuel oil additives, etc., depending on the requirements of the application. Can be used.

New Edition Automotive Engineering Handbook (Incorporated Association)
According to the Society of Automotive Engineers of Japan, ignitability and viscosity are important when used as diesel fuel. If a fatty acid ester having a relatively low viscosity is used, it may cause abrasion or seizure. Therefore, it is necessary to use a fatty acid ester having a viscosity suitable for a diesel engine. Further, if the molecular weight is too high, it causes odor and smoke emission, and thus such fatty acid ester is not preferable. For example, fatty acid methyl ester, fatty acid ethyl ester, fatty acid isopropyl ester, fatty acid isobutyl ester and the like are preferably used as diesel fuel.

The viscosity is also important when used as a lubricating oil. For summer, a relatively high viscosity is desired in order to provide high lubricity, but a relatively low viscosity and high fluidity fatty acid ester is desired when used in winter or at low temperatures. Therefore, a wide range of fatty acid esters can be used as the lubricating oil.

When used as a fuel oil additive, a fatty acid ester is added to the fuel mainly for the purpose of reducing friction, so that it plays almost the same role as the lubricating oil, and the same properties as the lubricating oil are desired.

The fatty acid ester produced depends on the application.
Glycerin contained in the reaction mixture after completion of the reaction, excess unreacted monohydric alcohol, unreacted fats and oils, and other impurities may be contained, but under each condition of the present invention, by repeating the reaction, etc. The yield can be further improved.

[0039]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto. The mass of the product in the examples was determined from the peak area by size exclusion chromatography (SEC method). The production confirmation of the fatty acid ester was confirmed by gas chromatography mass spectrometer HP-6890 (gas chromatography analyzer: manufactured by Hewlett Packard) -HP-5.
973 (Mass spectrometer: manufactured by Hewlett-Packard)
Went by. The yield of methyl ester in the examples is (yield) = [{(yield of methyl ester obtained from SEC) / 296} / {3 × (weight of rapeseed oil charged) / 884}] × 100 (% ) Was calculated.

Example 1 Rapeseed oil 0.860 g as fats and oils mainly composed of fatty acid triglyceride and methanol 1.2 as monohydric alcohol
4 g, MnO ₂ (manufactured by Kojundo Chemical Co., Ltd.) as a catalyst 5.6 mg
Was weighed, filled in a stainless reaction tube (about 4.5 cm ³ ) and sealed. This reaction tube was put into a fluidized bed sand bath whose temperature was controlled to 300 ° C where methanol was in a supercritical state, heated and reacted, and then taken out 10 minutes later (sand bath feeding time 10 minutes) and immediately put into water. And cooled. The amount of methanol used in this reaction was about 13 times the stoichiometric amount required to completely methyl esterify the rapeseed oil. Moreover, when a thermocouple was installed on the wall of the reaction tube and the temperature was measured, it exceeded about 260 ° C after 2 minutes and about 3 after 10 minutes.
It was 00 ° C. The methanol density at the initial stage of the reaction calculated from the reaction volume was 0.28 g / cm ³ . When quantified by the above method, 730 mg of the target methyl ester was obtained, and the amounts of triglyceride, diglyceride and monoglyceride in the reaction solution were 6 mg and 2 respectively.
The amounts were 2 mg and 37 mg, and the yield was 85%.

Example 2 A reaction was carried out in the same manner as in Example 1 except that rapeseed oil 0.859 g, methanol 1.24 g and MoO ₃ (manufactured by Wako Pure Chemical Industries, Ltd.) 4.8 mg were weighed. The target methyl ester was determined to be 759 by the above method.
mg of triglyceride, diglyceride and monoglyceride in the reaction solution were 1 mg or less and 13 m, respectively.
g, 33 mg, and the yield was 88%.

Comparative Example 1 The reaction was carried out in the same manner as in Example 1 except that 0.863 g of rapeseed oil and 1.24 g of methanol were weighed and no catalyst was used. When quantified by the above method, 645 mg of the target methyl ester was obtained, and the amounts of triglyceride, diglyceride and monoglyceride in the reaction solution were 33 mg, 62 mg and 71 mg, respectively, and the yield was 74%.
Met.

Comparative Example 2 Rapeseed oil 0.877 g, methanol 1.59 g, and MnO ₂ 4.9 mg as a catalyst were weighed, and the fluidized bed sand bath was controlled at a temperature of 200 ° C. at which neither methanol nor rapeseed became supercritical. The reaction was carried out in the same manner as in Example 1 except that the temperature was lowered and the sand bath was charged for 20 minutes. When quantified by the above method, 174 mg of the target methyl ester was obtained, and the amounts of triglyceride, diglyceride and monoglyceride in the reaction solution were 430 mg and 1 respectively.
It was 40 mg and 49 mg, and the yield was 20%.

[0044]

According to the production method of the present invention, a fatty acid ester can be produced in a high yield from a fat and oil and a monohydric alcohol in a short reaction time without using caustic soda as a catalyst. Since the fatty acid ester can be suitably used as a fuel, a lubricating oil, and a fuel additive, the present invention is industrially useful.

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Claims (9)

[Claims] 1. A fat and / or a monohydric alcohol in the presence of a catalyst containing at least one member selected from the group consisting of manganese oxide and molybdenum oxide, under the condition that the fat and / or monohydric alcohol is in a supercritical state. A method for producing a fatty acid ester, which comprises reacting. 2. The production method according to claim 1, wherein the monohydric alcohol is reacted under the condition of becoming a supercritical state. 3. The production method according to claim 1, wherein the monohydric alcohol is represented by the following general formula (1). R-OH (1) (R represents a hydrocarbyl group having 1 to 10 carbon atoms, or a hydrocarbyl group having 2 to 10 carbon atoms and substituted with a hydrocarbyloxyl group.) 4. The method according to claim 3, wherein the monohydric alcohol is methanol. 5. The production method according to claim 1, wherein the fat or oil is waste fat or oil. 6. The production method according to claim 1, wherein the fat or oil is waste edible oil. 7. A fuel containing a fatty acid ester produced by the production method according to claim 1. 8. A lubricating oil containing a fatty acid ester produced by the production method according to claim 1. 9. A fuel oil additive containing a fatty acid ester produced by the production method according to claim 1.