WO2010061702A1

WO2010061702A1 - Method for producing fatty acid ester

Info

Publication number: WO2010061702A1
Application number: PCT/JP2009/068197
Authority: WO
Inventors: 淳安孫子; 真上山
Original assignee: 国立大学法人京都工芸繊維大学
Priority date: 2008-11-28
Filing date: 2009-10-22
Publication date: 2010-06-03
Also published as: JPWO2010061702A1

Abstract

A method for producing a fatty acid ester, wherein a fatty acid can be efficiently produced at low cost by having a transesterification reaction proceed at a high reaction rate under mild conditions without requiring a catalyst separation process. In the method, wherein a fatty acid ester is produced by a transesterification reaction between an alcohol and a fat or oil, a hydrogen sulfate of an organic onium compound is used as a catalyst. Since the hydrogen sulfate can produce a fatty acid ester more efficiently using sulfuric acid as a starting material, the production cost can be reduced when compared with the conventional triflate salts.

Description

Method for producing fatty acid ester

The present invention relates to a method for producing a fatty acid ester by transesterification using fats and oils as a raw material.

Fatty acid esters synthesized by transesterification reaction between fats and alcohols are attracting attention as biodiesel fuels. Biodiesel fuel, compared to conventional petroleum diesel fuel (light oil),
(1) The exhaust gas when burned is about 75% cleaner,
(2) 10-20% reduction in emissions of carbon monoxide, hydrocarbons, particulate matter, etc.
(3) The exhaust gas does not contain sulfur oxides or sulfates,
(4) It has many advantages such as high lubrication performance.

Biodiesel fuel uses natural fats and oils derived from animals and plants, so even if it is used as a fuel, it has zero load for carbon dioxide production and is an environmentally friendly fuel. This fuel has the advantage that it can be used as it is without modification to any diesel engine. Moreover, since waste edible oil that contributes to environmental pollution can also be used as a raw material, it is a biomass raw material that can double the environmental burden. In the United States and Europe, we have already started using 1 to 20% biodiesel fuel mixed with petroleum-based diesel fuel, and that alone reduces the load on the engine due to its high lubricity and is environmentally friendly. It has been reported that the burden on health and health has also been reduced.

In recent years, the movement to actively use biodiesel fuel, which is superior to petroleum diesel fuel in all respects, has been gradually increasing in recent years, but at a cost two to three times that of petroleum diesel fuel. There is a big problem. This is because the current biodiesel fuel production process uses a homogeneous alkali catalyst such as potassium hydroxide, and the alkaline catalyst dissolves uniformly in the reaction solution, so that these alkali catalysts are separated and removed during commercialization. Due to the additional cost. Natural fats and oils generally contain a large amount of free fatty acids. If an alkali catalyst is used with a large amount of free fatty acids, fatty acid soap is produced as a by-product and a large amount of alkali catalyst is required, or the fatty acid soap produced makes it difficult to separate the fatty acid ester layer from the glycerin layer. There is also a problem. Therefore, a highly active heterogeneous solid catalyst that does not require a catalyst separation process and does not produce fatty acid soap has been studied.

For example, a method using a composite oxide having a perovskite type structure such as CaTiO ₃ and CaMnO ₃ as a heterogeneous solid catalyst for direct production of biodiesel fuel (Patent Document 1), alcohol in a supercritical state Alternatively, a method using alkaline earth metal oxide, hydroxide or carbonate in a subcritical state (Patent Document 2), a method using quick lime or bitter lime (Patent Document 3), calcium hydroxide or calcium oxide A method to be used (Patent Document 4) has been proposed. However, these methods have problems such as requiring high temperature and high pressure, difficulty in regenerating the catalyst, expensive catalyst, and insufficient reaction rate.

On the other hand, apart from the production of biodiesel fuel, a method for producing a fatty acid ester from triglyceride and alcohol has been known for a long time. For example, the method (patent document 5) which makes alcohol and the solvent as needed to a triglyceride, and makes it contact with basic ion exchange resin (anion exchange resin) is mentioned. However, in this method, the triglyceride serving as a substrate is preferably diluted with respect to alcohol, and there is a problem that the amount of fatty acid ester produced per ion exchange resin is not sufficient.

Also known is a method (Patent Document 6) in which triglyceride and alcohol are reacted in the presence of a solid acid catalyst such as a composite metal compound, metal sulfate, heteropolyacid, synthetic zeolite, or ion exchange resin. However, the method of Patent Document 6 has an advantage that the fatty acid soap is not produced as a by-product without pretreatment of free fatty acids in fats and oils, but the activity of the acid catalyst for transesterification is lower than that of the alkali catalyst. There was a problem that the reaction rate was small and not practical.

JP 2002-294277 A JP 2002-308825 A JP 2004-35873 A JP 2001-271090 A JP-A-62-218495 JP-A-6-313188

However, at present, no industrially available method has been found in place of the conventional method using a soaking alkali catalyst.

Therefore, the present invention eliminates the need for a catalyst separation process, and allows the fatty acid ester to be produced efficiently and at low cost by allowing the ester exchange reaction to proceed at a high reaction rate under mild conditions. An object of the present invention is to provide a manufacturing method.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that the above-mentioned problems can be solved by using an organic onium hydrogensulfate as a catalyst. is there. That is, the method for producing a fatty acid ester according to the present invention is a method for producing a fatty acid ester by an ester exchange reaction between fats and oils and using an organic onium hydrogen sulfate as a catalyst. .

In the present invention, natural fats and oils, synthetic fats and oils, synthetic triglycerides, synthetic triglycerides containing monoglycerides and / or diglycerides, modified products thereof, or waste oils and fats containing these can be used as fats and oils.

In addition, alcohol having 1 to 8 carbon atoms or methyl cellosolve can be used as the alcohol.

In addition, ammonium, nitrogen-containing heterocyclic compounds, or phosphonium hydrogen sulfate can be used as the organic onium hydrogen sulfate. More preferably, either dichloroanilinium hydrogensulfate or trichloroanilinium hydrogensulfate can be used.

A triflate salt having a fluorine-containing sulfonic acid as an anion is known as a conventional organic onium salt, but it is expensive because a fluorine-containing sulfonic acid is used. In contrast, the organic onium hydrogensulfate used as a catalyst in the present invention uses a hydrogensulfate anion as an anion, and therefore can be produced using sulfuric acid as a raw material, so that it is produced at a lower cost than a triflate salt. be able to. Thereby, manufacture of biodiesel oil can be performed at lower cost.

In addition, the organic onium hydrogen sulfate of the present invention has the same performance as the conventional triflate salt. That is, the organic onium hydrogen sulfate salt of the present invention is used by dissolving in alcohol, but at the time of reaction, its catalytic action is expressed at the two-layer interface between fat and alcohol and dissolved in the glycerin produced after the reaction. Therefore, after recovering fatty acid ester, glycerin, and alcohol by distillation, they can remain in the reaction vessel as a residue. Therefore, the following reaction can be performed by adding a new fat and alcohol to the reaction vessel. This eliminates the need for a catalyst separation step, unlike the conventional soaking alkali catalyst method. Moreover, since an alkali catalyst is not used, fatty acid soap is not produced. Moreover, the production amount of fatty acid ester per time is large. Moreover, it is possible to use fats and oils at high concentration. Thereby, compared with the past, fatty acid ester can be manufactured more efficiently.

[1] Catalyst The organic onium salt used as a catalyst in the present invention comprises an organic onium cation and a hydrogen sulfate anion (X ⁻ = HSO ₄ ⁻ ), and is represented by the following formula (1).

An organic onium cation is a cation generated by coordination bonding of a proton or another cation to a lone electron pair in a compound containing an element having a lone electron pair. In the formula, R ₁ to R ₄ are each independently a hydrogen atom, or a linear or branched aliphatic hydrocarbon group, alicyclic hydrocarbon group, aromatic hydrocarbon which may have a substituent. Represents a group or a heterocyclic group. A represents a nitrogen atom or a phosphorus atom. _One to three of R ₁ to R ₄ may be a hydrogen atom. X ⁻ represents a hydrogen sulfate anion.

Examples of the linear or branched aliphatic hydrocarbon group include an alkyl group, an alkenyl group, and an alkynyl group. Examples of the alicyclic hydrocarbon group include a cycloalkyl group. Examples of the aromatic hydrocarbon group include an aryl group and an aralkyl group. Examples of the heterocyclic group include nitrogen-containing monocyclic or condensed ring compounds. Examples of the substituent such as the aliphatic hydrocarbon group include a halogen atom. Preferred is a fluorine atom.

Specific examples of organic onium cations include the following nitrogen cations. Tetraalkylammonium such as triethylammonium, triethylammonium, ethyldimethylammonium, diethylmethylammonium, tetramethylammonium, tetraethylammonium, tetra-n-propylammonium, tetraisopropylammonium, tetra-n-butylammonium, anilinium, diphenylammonium, tetra Aromatic ammonium such as phenylammonium, alicyclic ammonium such as N, N-dimethylpyrrolidinium, N, N-dimethylpiperidinium, N, N-dimethylmorpholinium, pyridinium, pyrazolium, N-methylimidazolium And nitrogen-containing heterocyclic compounds such as N-methylpyridinium. These nitrogen-containing heterocyclic compounds may contain a substituent such as an alkyl group, an aralkyl group, a halogen group, or an alkoxy group. Anilinium, pyrazolium and N-methylimidazolium are preferred. Furthermore, the anilinium is preferably a fluorine-substituted product or a chlorine-substituted product, specifically pentafluoroanilinium, dichloroanilinium or trichloroanilinium. More preferably, it is a chlorine substitution product, and is dichloroanilinium or trichloroanilinium.

Here, the reason why the chlorine substitution product of anilinium is preferable is as follows. When the reaction solution is cooled after completion of the reaction, it is separated into an upper layer containing glycerin and methanol and a lower layer containing a fatty acid ester. According to the knowledge of the present inventors, when an organic onium other than the chlorine-substituted product of anilinium is used, the organic onium salt is dissolved in the lower layer and both layers are in a cloudy state, thereby achieving two-layer separation. It took at least one day to complete. On the other hand, when the chlorine substitution product of anilinium is used, two-layer separation can be achieved in a short time of about 1 hour. Therefore, since recovery of the fatty acid ester from the reaction solution can be performed in a short time, the manufacturing cost can be further reduced.

Moreover, the following can be mentioned about a phosphorus cation.
Examples thereof include triarylphosphonium, aryldialkylphosphonium, diarylalkylphosphonium, and trialkylphosphonium. Preferred is triarylphosphonium, specifically triphenylphosphonium.

Since the organic onium salt used in the present invention catalyzes the transesterification reaction as a Brensted acid, the smaller the pKa (the stronger the acidity), the better. Therefore, hydrogen sulfate ions are used as anions.

The organic onium salt of the present invention is not particularly limited as long as it is a combination of the above-described nitrogen cation or phosphorus cation and a hydrogen sulfate anion, but preferably comprises dichloroaniline (regardless of the substitution position) and a hydrogen sulfate anion. It is a trichloroanilinium hydrogensulfate composed of dichloroanilinium hydrogensulfate, trichloroaniline (regardless of the substitution position) and a hydrogensulfate anion. More preferred are dichloroanilinium hydrogensulfate and trichloroanilinium hydrogensulfate, and more preferred are 2,4-dichloroanilinium hydrogensulfate and 2,5-dichloroanilinium hydrogensulfate.

The catalyst concentration with respect to fats and oils is 0.1 to 30 mol%, more preferably 0.1 to 10 mol%. The catalyst concentration affects the reaction temperature and reaction time, and can be appropriately selected within the above range. For example, when the catalyst is used at 10 mol% with respect to the fat and oil, methanol is used as the alcohol and the reaction temperature is 60 ° C., the conversion rate of the fat becomes 100% in 24 hours. %, When methanol is used as the alcohol and the reaction temperature is 130 ° C., the conversion of fats and oils becomes 100% in 4 hours. That is, since the reaction is a pseudo-primary reaction that completely depends on the amount of catalyst, the temperature and the time required for the reaction have an inversely proportional relationship. Here, the conversion rate of fats and oils is defined by the following formula.
Conversion rate = (1−Residual oil amount after reaction / Amount of oil and fat before reaction) × 100

[2] Reaction substrate The fats and oils used in the present invention are not particularly limited, and may be natural fats and oils, synthetic fats and oils, or a mixture thereof. For example, soybean oil, palm oil, palm oil, palm kernel oil, corn oil, peanut oil, sunflower oil, olive oil, safflower oil, coconut oil, oak oil, almond oil, black walnut oil, apricot oil, cocoa butter oil , Dairy oil, safflower oil, cinnamon oil, linseed oil, cottonseed oil, rapeseed oil, giraffe oil, castor oil, cottonseed stearin, sesame oil and other vegetable oils, lard oil, chicken oil, butter oil, cod liver oil, deer oil , Animal oils such as dolphin oil, sardine oil, mackerel oil, horse fat, pork fat, bone oil, sheep oil, cow leg oil, murine dolphin oil, shark oil, sperm whale oil, whale oil, beef fat, cow bone fat, Examples include vegetable oils discarded from restaurants, food factories, general households, and the like. Fats and oils containing these oils alone or mixed, fats and oils containing diglycerides and monoglycerides, synthesized triglycerides, synthetic triglycerides containing monoglycerides and / or diglycerides, and some of these fats and oils are modified by oxidation, reduction, etc. Modified oils and fats may be used. Or the fats and oils processed product which has these fats and oils as a main component can also be used as a raw material.

In fats and oils, components other than fats and oils may be mixed. Specifically, crude oil, heavy oil, light oil, mineral oil, essential oil, coal, fatty acid, sugar, metal powder, metal salt, protein, amino acid, hydrocarbon, cholesterol, flavor, pigment compound, enzyme, perfume, alcohol, fiber, Resins, rubbers, paints, cements, detergents, aromatic compounds, aliphatic compounds, soot, glass, earth and sand, nitrogen-containing compounds, sulfur-containing compounds, phosphorus-containing compounds, halogen-containing compounds, etc. It is not limited. These foreign components are preferably used after being removed by sedimentation, filtration, liquid separation or the like. In addition, about water | moisture content, a fatty acid, saccharides, an amino acid, and protein which may be contained in waste oil, it does not affect reaction in this invention.

[3] Alcohols The alcohols used in the present invention are not particularly limited, but are alcohols having a saturated linear or branched aliphatic hydrocarbon skeleton. Preferred are alcohols having 1 to 8 carbon atoms, more preferably 1 to 5 carbon atoms. Furthermore, you may have a halogen atom and an ether group as a substituent. For example, methanol, ethanol, n-propanol, isopropanol, n-butanol, t-butanol, n-pentanol, methyl cellosolve and the like can be mentioned. These alcohols can be used alone or in admixture of two or more. Preferably, any one of methanol, ethanol and methyl cellosolve is used. This is because it is easily available and the availability of the resulting fatty acid ester is high. In the present invention, alcohols act as a reaction substrate for subjecting fats and oils to alcoholysis (transesterification reaction), and also act as a solvent for adjusting the dilution and viscosity of fats and oils.

[4] Molar ratio of fats and oils and alcohols There is no particular limitation as long as the molar ratio of fats and fats and alcohols used as a reaction substrate (fats / alcohols) is 1/1 or more, but preferably 1 / 20 to 1/2, more preferably 1/15 to 1/3, and still more preferably 1/10 to 1/3. When the molar ratio of fats and alcohols is small (for example, 1/2), the reaction becomes a secondary reaction, the time required for the completion of the reaction becomes long, and when the molar ratio of fats and oils to alcohols is large (for example, 1/10) ) The reaction becomes a false primary reaction, and the reaction can be completed in a short time. In addition, fats and oils and alcohol should just exist as a mixture of both, and if sufficient stirring is made, it is not necessary to form a uniform phase in particular. In the present invention, unless otherwise specified, the molar ratio of fats and oils to alcohols is represented by the number of moles of alcohol per ester in the fats and oils.

[5] Other reaction conditions The reaction temperature is from room temperature to 200 ° C, more preferably from 60 to 130 ° C. The reaction is a secondary reaction or a pseudo-primary reaction depending on the molar ratio of fats and alcohols to be used. Therefore, the higher the reaction temperature, the faster the reaction rate can be obtained, but the reaction is preferably carried out at 60 to 130 ° C.

The reaction time (contact time) depends on the reaction temperature and the amount of catalyst used. For example, when the reaction temperature is 60 ° C., 10 mol% of the catalyst is used with respect to the fat and oil, and methanol is used as the alcohol, the conversion rate of the fat and oil becomes 100% in 24 hours. On the other hand, when the reaction temperature is 130 ° C., 1 mol% of the catalyst is used with respect to the oil and fat, and when methanol is used as the alcohol, the conversion of the oil and fat becomes 100% in 4 hours. Therefore, the reaction time can be appropriately selected depending on the catalyst concentration and the reaction temperature.

The reaction pressure is not particularly limited. Although it is convenient in terms of operation to carry out under normal pressure, the pressure may be increased to about 1 to 10 atm if necessary. When using a low-boiling point alcohol, it is desirable to carry out the reaction under pressure in a sealed container in order to ensure a desired reaction temperature.

* No reaction solvent is required. This is because alcohols used as a reaction substrate also serve as a solvent.

The type of reaction apparatus for carrying out the present invention is not particularly limited. Depending on the reaction method such as a batch method or a continuous method, the reaction can be performed using a stirring tank, a fluidized bed reactor, a shaking reactor, or the like.

[6] Post-treatment (separation, purification, catalyst reuse, etc.)
When a stirred tank reactor is used, it is cooled to a predetermined temperature, and the liquid phase is separated into a fatty acid ester layer (lower layer) and a glycerin layer (upper layer). Centrifugation can also be used. If necessary, the fatty acid ester layer can be commercialized by washing with water, washing with alkali, treating with an adsorbent, and removing alcohols. As the adsorbent, activated carbon, acid clay, diatomaceous earth, or the like can be used. On the other hand, the glycerin layer can be separated by the difference in specific gravity, and glycerin can be recovered by a known method.

Moreover, alcohols and glycerin can be recovered by direct distillation after completion of the reaction, and a fatty acid ester can be recovered without using a phase separation operation. The catalyst remains in the reaction vessel as a distillation residue. Thereby, new fats and oils and alcohols can be added and the next reaction can be performed, and the catalyst can be reused. The catalyst can be purified by recrystallization and reused as necessary.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples.

Synthesis Example 1 (Synthesis of 2,4-dichloroanilinium hydrogensulfate, 2,5-dichloroanilinium hydrogensulfate and trichloroanilinium hydrogensulfate)
Dichloroanilinium hydrogensulfate (2, 4, 2, 5) and trichloroanilinium hydrogensulfate (2, 4, 6) were synthesized by the methods described in the following documents.
Gurdip Singh, Jaya Srivastava, Jaspreet Kaur, Indian Journal of Chemical Technology, Vol 10, 510-518 (2003)

Synthesis Example 2 (Synthesis of triphenylphosphonium hydrogen sulfate)
Triphenylphosphine (13.2 g, 0.05 mol) was dissolved in dichloromethane (30 ml), and sulfuric acid (98%, 4.9 g) was added dropwise under ice cooling. After stirring for 30 minutes, the mixture was concentrated (˜10 ml) and ethyl acetate (50 ml) was added to precipitate hydrogen sulfate. The precipitate was collected by filtration and dried. Yield 13.7 g (75%).
(result of analysis)
¹ H-NMR (500 MHz) δ 7.65 (6H, m), 7.80 (3H, m), 7.93 (6H, m)
¹³ C-NMR (125 MHz) δ 119.0 (d, J = 69.8 Hz), 129.9 (d, J = 12.5 Hz), 134.4 (d, J = 9.4 Hz), 134.6 ( d, J = 3.4 Hz)
Melting point 173 ° C

Analysis ⁽¹ H-NMR ^(500MHz) spectrum measurement)
A BRUKERDRX500 spectrometer (manufactured by Bruker) was used. Using CDC1 ₃ containing 0.03Vol% tetramethylsilane (TMS) as the standard compound in a solvent.

Example 1.
Oil and fat (Nissin Food Formulation, 10.41 g), methanol (Wako Pure Chemical Grade 1, 30 ml), 2,4-dichloroanilinium hydrogensulfate catalyst [28.5 mg (1.14 mol%)] and stir bar It put into the reaction container (made by a pressure | voltage resistant industry company), and after the system inside was substituted with nitrogen, it sealed. While stirring with a magnetic stirrer, it was heated from outside the reaction vessel with a ribbon heater. The reaction was carried out at a system temperature of 130 ° C. for 5 hours, and the whole reaction vessel was quenched with running water. The contents were opened in a separatory funnel and left for 1 hour to separate the two layers. The lower layer (hereinafter referred to as FAME) was separated and the residual methanol was removed using an evaporator, and then the yield and conversion were analyzed by NMR. Yield 8.49 g (85%), conversion 100%, glycerin content <0.1%.

Example 2
The same procedure as in Example 1 was conducted, except that 26.2 mg (1.05 mol%) of 2,5-dichloroanilinium hydrogen sulfate was used. The two layers separated by standing for 1 hour. FAME was isolated and analyzed. Yield 6.35 g (63%), conversion 100%, glycerin content <0.1%.

Example 3 FIG.
The same procedure as in Example 1 was performed except that 2,4,6-trichloroanilinium hydrogen sulfate (33.0 mg, 1.15 mol%) was used. The two layers separated by standing for 1 hour. FAME was isolated and analyzed. Yield 5.03 g (50%), conversion 100%, glycerin content <0.1%.

Example 4
The same procedure as in Example 1 was conducted except that 40.0 mg (1.00 mol%) of triphenylphosphonium hydrogen sulfate was used as the catalyst. The two layers separated by standing for 1 hour. FAME was isolated and analyzed. Yield 7.34 g (73%), conversion 100%, glycerin content <0.1%.

Reference Example 1
The same procedure as in Example 1 was conducted except that 2,5-dichloroanilinium triflate (21.0 mg, 1.05 mol%) was used as the catalyst. The two layers separated by standing for 1 hour. FAME was isolated and analyzed. Yield 7.13 g (71%), conversion 100%, glycerin content <0.1%.

In all of Examples 1 to 4, the conversion rate was 100%, and the same high conversion rate as that obtained when the conventional triflate salt shown in Reference Example 1 was used as a catalyst was obtained.

Claims

A method for producing a fatty acid ester by a transesterification reaction between an oil and fat and an alcohol, wherein the method uses a hydrogen sulfate of organic onium as a catalyst.
The method for producing a fatty acid ester according to claim 1, wherein the fats and oils are natural fats and oils, synthetic fats and oils, synthetic triglycerides, synthetic triglycerides containing monoglycerides and / or diglycerides, modified products thereof, or waste oils and fats containing them.
The method for producing a fatty acid ester according to claim 1, wherein the alcohol is an alcohol having 1 to 8 carbon atoms or methyl cellosolve.
2. The method for producing a fatty acid ester according to claim 1, wherein the organic onium hydrogen sulfate is ammonium, a nitrogen-containing heterocyclic compound, or a phosphonium hydrogen sulfate.
The method for producing a fatty acid ester according to claim 4, wherein the organic onium hydrogen sulfate is dichloroanilinium hydrogen sulfate or trichloroanilinium hydrogen sulfate.