JPH0324458B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing fatty acids by hydrolyzing fatty acid lower alcohol esters.
The following methods are generally known as methods for producing fatty acids by hydrolyzing oil and fat esters. Pressure hydrolysis method Currently, this is the most commonly used method for hydrolyzing large amounts of fats and oils.
It is a method to obtain fatty acids and glycerin by reacting oil and fat with water in the presence of a catalyst (such as zinc oxide) at a temperature of 15 to 55 kg/cm ² G, or in a continuous or batch manner without a catalyst. Saponification and acid decomposition method This is a method in which esters (oils and fats) are saponified with an alkali such as sodium hydroxide, decomposed into soap and alcohol (glycerin), and then the soap is converted into fatty acids with an inorganic acid such as sulfuric acid or hydrochloric acid. Toitziel decomposition method This method has been known for a long time as a method of hydrolyzing fats and oils, in which 20 to 100% water is added to fats and oils, approximately 1% of a decomposing agent such as phenolstearosulfonic acid or naphthalenestearosulfonic acid, and 0.5% of sulfuric acid are added. This method involves reacting in the presence of ~2% with steam stirring for about 20 hours to obtain fatty acids. On the other hand, hydrolysis of fatty acid lower alcohol esters can be carried out in accordance with the above-mentioned hydrolysis method of oil and fat esters, but this method has industrial value in terms of decomposition rate and reaction conditions. The current situation is that there is no. That is, the above-mentioned pressure hydrolysis method has problems such as the decomposition rate not increasing due to the dissolution of the lower alcohol into the fatty acid, and the need for a large amount of water. Next, the saponification acid decomposition method has problems such as a large amount of auxiliary raw materials being required, a large amount of inorganic salts being discharged as by-products, and a large amount of water being used. Furthermore, the Toitziel decomposition method requires a special oil-soluble decomposition agent, which causes problems such as difficulty in removing the residual decomposition agent from decomposed fatty acids, which causes deterioration of fatty acid quality, and low decomposition rate. As a result of intensive studies to solve the above-mentioned problems in the hydrolysis of fatty acid lower alcohol esters, the present inventors found that water-soluble compounds such as short-chain alkylbenzene sulfonic acids and sulfuric acids, which have very small catalytic effects when used in aqueous solutions, We have found that the catalytic effect is significantly enhanced by using a highly concentrated sulfonic acid as a catalyst in a system without an aqueous layer, and esters can be easily hydrolyzed. Therefore, these acid catalysts are added to the ester, water is continuously added from outside the system, and the generated alcohol and excess water are continuously distilled out of the system, without creating a water layer in the reaction system. The inventors have discovered that fatty acids can be easily obtained at a high decomposition rate by hydrolysis using only dissolved water, and have thus arrived at the present invention. That is, in the present invention, when a fatty acid lower alcohol ester is hydrolyzed in the presence of an acid catalyst to produce a fatty acid, water is continuously added from outside the system, and the unreacted lower alcohol and the added water are removed by distillation. This invention relates to a method for producing a fatty acid from a fatty acid lower alcohol ester, which is characterized in that the reaction is carried out by continuously extracting water from the reaction mixture and preventing the formation of an aqueous layer by separating water from the reaction mixture. In the fatty acid production method of the present invention, the catalyst can be recovered and removed from the obtained crude fatty acid by a simple operation such as washing with water, and the recovered catalyst can be reused. By distilling the removed crude fatty acids, it is possible to produce fatty acids with good yield and quality. In the case of unsaturated fatty acids, part of the catalyst is attached to the double bonds, so the catalyst cannot be completely removed from the crude fatty acid after hydrolysis by washing with water alone, and if the fatty acid is distilled directly after washing with water, the quality may deteriorate. However, high quality fatty acids can be obtained by treating with alkaline earth metal carbonates or hydroxides, such as CaCO ₃ and BaCO ₃ after washing with water. The fatty acid lower alcohol ester in the present invention preferably has a fatty acid portion corresponding to a fatty acid having 6 to 26 carbon atoms, and an alcohol portion corresponding to a fatty acid having 1 to 4 carbon atoms.
It is an ester corresponding to a lower alcohol of
For example, caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, lignoceric acid, cerotic acid, valmitoleic acid, oleic acid, linoleic acid, gondoiic acid, erucic acid, and these Examples include mixtures of methanol, ethanol, propanol, isopropanol, normal butanol, secondary butanol, tertiary butanol, and esters with isobutanol. Acid catalysts are used in the present invention. Preferred are water-soluble, nonvolatile strong acids, and more preferred are those that are soluble in water and exhibit no surface activity. Examples of such substances include inorganic nonvolatile strong acids, sulfonic acids of aromatic hydrocarbons having 6 to 14 carbon atoms, and sulfonic acids of aliphatic hydrocarbons having 1 to 8 carbon atoms. When selecting an inorganic strong acid, one with PKa≦2 is preferable;
As long as there are no other inconveniences, the smaller the PKa, the better. Para-toluenesulfonic acid and sulfuric acid are good in terms of availability, and the amount is relative to the ester.
Approximately 0.5 to 5% by weight is preferable. The reaction pressure is not limited to normal pressure, but may be a reduced pressure system or a pressurized system, and the reaction temperature may be at least the melting point of the fatty acid obtained by decomposition.
For ease of reaction, a temperature of about 100 to 150°C at normal pressure is preferable. Although the water addition rate can be selected arbitrarily, it is 5 to 50% due to the relationship between the amount of water used and the time required to reach a certain decomposition rate.
Good against ester/time. Addition of water can be carried out by any means, such as by introducing into the reactor through pipes or by blowing in steam. Removal of catalyst from crude fatty acids after completion of hydrolysis reaction is 10 to 50% relative to ester in the case of saturated esters.
It can be easily removed by washing with water several times at a temperature above the melting point of the fatty acid. It is also possible to remove most of the catalyst with a small amount of water, for example 2 to 10% water, in the first washing, and then collect and reuse it in the reaction. On the other hand, in cases where unsaturated esters are contained, the catalyst cannot be completely removed by washing with water alone as mentioned above, so in order to improve the quality of the fatty acid, after removing most of the catalyst by washing with water, carbonates or hydroxides of alkaline earth metals are used. It needs to be treated with something. The treatment method is to add carbonate or hydroxide of an alkaline earth metal (e.g. CaCO ₃ , BaCO ₃ ) and water at 0 to 50% in a molar amount to 10 times the amount of catalyst remaining after washing with water.
After stirring at 100° C. for 30 to 60 minutes, the aqueous layer and the produced organic acid salt may be separated by ordinary separation means such as static separation or centrifugation. Examples and comparative examples of the present invention are shown below, but the present invention is not limited to these examples. Example 1 Using a Claisen flask equipped with a stirrer, thermometer, and dropping funnel as a reaction device, 100 parts of methyl caprylate and 1 part of para-toluenesulfonic acid as a catalyst were charged into the flask, and the contents were heated to 105°C in an oil bath. Water was dropped at a rate of 30 parts/hour from a dropping funnel whose tip was below the liquid surface. The generated methanol and excess water were continuously extracted from the system through the distillation tube so that no water layer existed in the system, and the reaction was carried out. As a result, the decomposition rate was 97% in a reaction time of 8 hours. The decomposition rate was measured by washing the reaction product with saturated saline and measuring the NV (neutralization value) and SV (saponification value). Comparative Example 1 100 parts of methyl caprylate and 1 part of para-toluenesulfonic acid were charged into the same equipment as used in Example-1, and 20 parts of water was added, and the mixture was heated to 105°C in an oil bath.
Add 30 parts of water from the dropping funnel while keeping the contents intact.
Dropped in hr. The generated methanol and excess water were continuously extracted from the distillation tube so that a 20 part water layer always existed in the system, and the reaction was carried out.
The decomposition rate was 40% in hours. Incidentally, since the reaction proceeds as a pseudo-first-order reaction, in order to obtain a decomposition rate equivalent to that of Example-1, a reaction time of 55 to 60 hours is calculated. Example 2 1 part of sulfuric acid was added as a catalyst to 100 parts of methyl caprylate, and as in Example-1, water was added dropwise at 30 parts/Hr at 105°C to avoid the presence of an aqueous layer in the system. When methanol and excess water were continuously extracted from the system and the reaction was carried out, the decomposition rate was 93% in 12 hours. Comparative Example 2 100 parts of methyl caprylate and 1 part of sulfuric acid were added, and water was added dropwise at 105°C at a rate of 30 parts/Hr so that 20 parts of water was always present in the system as in Comparative Example-1. Methanol and excess water were continuously removed from the system and the reaction was carried out, resulting in a decomposition rate of 5% in 12 hours. Example 3 Add 1 part of para-toluenesulfonic acid to 100 parts of methyl caprylate, maintain the temperature at 120°C instead of 105°C in Example-1, and add 30 parts of water to 100 parts of methyl caprylate, keeping the temperature at 120°C so that there is no water layer in the system. The reaction was carried out by extracting the generated methanol and excess water from the system while dropping with Hr, and as a result, the decomposition rate was 98% in a reaction time of 6 hours. Example 4 In Example-3, m was added to 100 parts of methyl caprylate.
The reaction was carried out in the same manner except that 1 part each of -xylene sulfonic acid, β-naphthalene sulfonic acid, octyl sulfonic acid, and octylbenzenesulfonic acid were added as catalysts. That is, while maintaining the temperature of each at 120°C and adding water dropwise at a rate of about 30 parts/hour to ensure that no water layer exists in the system, the generated methanol and excess water are continuously extracted from the system to carry out the reaction. As a result, the decomposition rates were 98%, 97.5%, 97%, and 95%, respectively, after a reaction time of 6 hours. Example 5 Various fatty acid methyl esters shown in Table-1
Add part-toluenesulfonic acid as a catalyst in the amount shown in Table 1 to 100 parts, maintain the reaction temperature shown in Table 1, and under the normal pressure or increased pressure shown in Table 1, there is no aqueous layer in the system. While water was continuously added dropwise in this manner, the produced methanol and excess water were continuously extracted from the system, and the reaction was carried out under the conditions shown in Table 1. As a result, the decomposition rate was shown in Table 1. It was exactly as I expected.

【table】

[Table] Example 6 Add 1 part of para-toluenesulfonic acid to 100 parts of isopropyl myristate and heat at 120°C. While continuously adding water at 35 parts/hour so that there is no aqueous layer in the system, the resulting isopropanol and excess The water was extracted from the system and the reaction was carried out. As a result, the decomposition rate was 98.5% in a reaction time of 7 hours. Example 7 1 part of para-toluenesulfonic acid was added to 100 parts of n-butyl stearate, and the resulting n-butanol was heated at 120°C while continuously adding water at a rate of 30 parts/hour so that no aqueous layer existed in the system. As a result of removing excess water from the system and carrying out the reaction, the decomposition rate decreased after 11 hours of reaction time.
It was 94%.

Claims (1)

[Scope of Claims] 1. Fatty acid lower alcohol ester is selected from the group consisting of inorganic nonvolatile strong acids, sulfonic acids of aromatic hydrocarbons having 6 to 14 carbon atoms, and sulfonic acids of aliphatic hydrocarbons having 1 to 8 carbon atoms. When producing fatty acids by hydrolysis in the presence of one or more selected acid catalysts, water is continuously added from outside the system, and the lower alcohol produced and the unreacted portion of the added water are distilled. 1. A method for producing a fatty acid from a fatty acid lower alcohol ester, which comprises continuously extracting water from the reaction mixture and carrying out the reaction without separating water from the reaction mixture to form an aqueous layer. 2. The manufacturing method according to claim 1, wherein the acid catalyst is sulfuric acid or para-toluenesulfonic acid. 3. Claims 1 or 2, in which the fatty acid portion of the aliphatic lower alcohol ester corresponds to a fatty acid having 6 to 26 carbon atoms, and the alcohol portion corresponds to a monohydric alcohol having 1 to 4 carbon atoms. Manufacturing method described in section.