JP2002155024A - Fatty acid ester prepared from soy sauce oil and use thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for preparing a fatty acid ester from a soy sauce oil and using the resultant fatty acid ester as a fuel for diesel automobiles. SOLUTION: This fatty acid ester is obtained by reacting the soy sauce oil with an alcohol in the presence of an acidic catalyst. The fuel comprises the fatty acid ester.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to the preparation of a fatty acid ester from soy sauce and to use it as a fuel for diesel vehicles.

[0002]

2. Description of the Related Art Mineral oils such as heavy oil and light oil are generally used as fuel for diesel vehicles. The exhaust gas of diesel vehicles using this mineral oil contains harmful nitrogen oxides and the like, and is regarded as a major cause of air pollution. One solution to this problem is to prepare a fatty acid ester from used edible oil (waste edible oil) instead of mineral oil, and use it alone or as a mixed oil of heavy oil with diesel fuel (partly). Is also called "biodiesel").
Attention has been paid to recycling and prevention of air pollution (see JP-A-7-197047, JP-A-10-17875, etc.).

[0003] On the other hand, soy sauce is obtained as a by-product during the production of soy sauce, and although its use has been conventionally studied in many ways, a part of it is used as a raw material of flavors due to various causes such as coloring and odor. Most of them are currently incinerated except for those that have been incinerated.

[0004]

Conventionally, as a method for preparing a fatty acid ester, which is a fuel for a diesel engine, from waste cooking oil, a method using an alkali as a catalyst (Japanese Patent Application Laid-Open Nos. 7-97047, 9-235573, 9-235573, 10-182518) and a method utilizing a reaction in a supercritical state (see JP-A-2000-143586).
Although two methods were known, a method using an alkali capable of producing a fatty acid ester at low cost as a catalyst without using a special apparatus was considered to be a practical method.

[0005] However, soy sauce contains free fatty acids, glycerol, salt, cyclic compounds (such as isoflavones), insolubilized substances and the like in addition to fatty acid ethyl esters. The following problems had to be solved when trying to produce fuel for industrial use. (1) Compared with other waste cooking oils, soy sauce oil has a free fatty acid content of 15% or more, and therefore, the acid value of soy sauce oil is as high as 20 to 35. Since this free fatty acid reacts with the metal oxide and corrodes the metals, it was necessary to esterify or remove the free fatty acid.

(2) Esterification of a free fatty acid is generally carried out by reacting an oil or fat with an alcohol such as methanol using an alkali catalyst such as sodium hydroxide. In the case of soy sauce oil, an acid value is high. Since the amount of free fatty acids is large, the esterification reaction using an alkali catalyst does not proceed smoothly. (3) The method of removing (deoxidizing) free fatty acids is generally a method in which fats and oils are treated with an alkali such as sodium hydroxide to remove them as alkali metal salts of fatty acids (so-called soap). In this case, since the acid value is high and the amount of free fatty acids is large, the efficiency of removing free fatty acids is low as in the esterification reaction.

(4) Soy sauce contains tens to thousands of ppm of salt, and if soy sauce is heated and incinerated under inappropriate conditions while containing salt, harmful substances may be produced. There is also. (5) Insolubles (predominantly unsaponifiable substances such as sterols and isoflavones) which precipitate at relatively low temperatures are present in soy sauce oil, so as to improve handling. Need to be removed.

[0008]

The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have found that even when soy sauce oil is used as a raw material by using an acid catalyst instead of an alkali catalyst, an ester is used. The present inventors have found that the chemical reaction proceeds favorably and can produce a fuel for a diesel engine, and have completed the present invention. That is, the present invention relates to a fatty acid ester obtained by reacting soy sauce and alcohol in the presence of an acid catalyst, and a fuel containing the same.

[0009]

DETAILED DESCRIPTION OF THE INVENTION The soy sauce used in the present invention may be any fat or oil obtained as a by-product during the production of soy sauce, and is not limited by the method or raw material for producing soy sauce. For example, any soy sauce derived at the time of manufacturing soy sauce using whole soybeans or defatted soybeans can be used as a suitable soy sauce in the present invention. Furthermore, not only such a soy sauce oil alone, but also a mixed fat and oil of a used edible oil and fat (waste edible oil) in order to reduce the production cost may be used. The blending ratio may be appropriately selected from soy sauce: other fats = 1: 10 to 10: 1.

[0010] As the alcohol to be reacted with soy sauce,
Any material having an alkyl having 5 or less carbon atoms may be used. Specifically, methanol, ethanol, isopropanol,
Isobutanol can be exemplified, and methanol is particularly common. As the acid catalyst used when reacting soy sauce oil and alcohol, aryl sulfonic acid, especially p
-Toluenesulfonic acid. According to the study of the present inventor, general acids such as hydrochloric acid and sulfuric acid can be used as a catalyst, but the reaction efficiency is poor or a special device having acid resistance (eg, a device subjected to a glass lining treatment). Arylsulfonic acid was the most suitable acid catalyst.

The reaction between soy sauce and alcohol using such an acid catalyst is carried out in an amount of 0.01 to 10% (w
/ W) The reaction can be carried out by stirring and reacting at 40 to 100 ° C. for about 0.1 to 10 hours using a corresponding arylsulfonic acid and an excess amount of alcohol. After the reaction, after removing the alcohol, washing, deacidification (alkali treatment using sodium hydroxide or the like), washing with water, and drying are repeated as appropriate to efficiently remove unreacted free fatty acids, salt, insolubles, and the like. Then, a fatty acid ester suitable as a fuel can be obtained.

A specific example of a method for preparing a fatty acid methyl ester from soy sauce can be shown by a flowchart. Soy sauce (1,000 ml) Methanol (120 ml) p-Toluenesulfonic acid (3.6 g) ↓ Esterification reaction (60 ° C, 1 hour stirring) ↓ Methanol removal (70-90 ° C, 1 hour stirring) ↓ Rinse with water (200 ml of water) ↓ Stand still (10 minutes) ↓ Deoxidize (20% aqueous sodium hydroxide solution 10 ml, stirring for 15 minutes) ↓ Stand still (10 minutes) ↓ Rinse with water (200 ml of water) ↓ Stand still (10 minutes) ↓ Dried ↓ fatty acid methyl ester

The fatty acid ester thus prepared can be used as it is as a fuel for a diesel engine, or may be mixed with a conventional fuel for a diesel engine such as heavy oil or light oil to form a mixed fuel.

[0014]

It has been found for the first time by the present inventors that a fuel for a diesel engine can be prepared by a simple method and at a low cost from soy sauce oil, which has been mostly incinerated in the past, as a raw material. It is a very practical method for effective utilization of. Further, the fatty acid ester prepared by such a method and the fuel containing the same are safer than conventional fuels for diesel engines and contribute to the prevention of pollution, and their future use is greatly expected. You.

[0015]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited thereto. Example 1 120 ml of a 3% (w / v) solution of p-toluenesulfonic acid in methanol was added to 1 L (liter) of soy sauce and stirred at 60 ° C. for 1 hour. After the temperature was further raised to 80 ° C., the mixture was stirred for 1 hour to remove methanol, and 200 ml of water was added.
(W / v) 10 ml of an aqueous sodium hydroxide solution was added, and the mixture was stirred at room temperature for 15 minutes. The aqueous layer was removed, washed twice with 200 ml of water, and dried to obtain about 820 ml of fatty acid methyl ester. As a result of measuring the salt content, the presence or absence of insoluble matter, and the free fatty acid content of the soy sauce oil as the raw material, the soy sauce oil after methanol removal and the obtained fatty acid methyl ester, as shown in Table 1, the fatty acid ester of the present invention showed No salt, insolubles and free fatty acids were detected.

[0016]

[Table 1] Salt: Atomic absorption spectrophotometry Free fatty acids: Gas chromatography

Example 2 Using 120 ml of a 3% (w / v) p-toluenesulfonic acid ethanol solution, the reaction was carried out in the same manner as in Example 1 to obtain a fatty acid ethyl ester. Table 2 shows the analysis results.

[Table 2] Salt: Atomic absorption spectrophotometry Free fatty acids: Gas chromatography

Claims (9)

[Claims] 1. A fatty acid ester obtained by reacting soy sauce with an alcohol in the presence of an acid catalyst. 2. The fatty acid ester according to claim 1, wherein the acid catalyst is an aryl sulfonic acid. 3. The fatty acid ester according to claim 1, wherein the acid catalyst is p-toluenesulfonic acid. 4. The fatty acid ester according to claim 1, wherein the alcohol has an alkyl having 5 or less carbon atoms. 5. The fatty acid ester according to claim 1, wherein the alcohol is selected from methanol, ethanol, isopropanol and isobutanol. 6. The fatty acid ester according to claim 1, wherein the alcohol is methanol and the fatty acid ester is a fatty acid methyl ester. 7. A fuel comprising the fatty acid ester according to claim 1. 8. The fuel according to claim 7, which is a fuel for a diesel engine. 9. The fuel according to claim 7, further comprising heavy oil or light oil.