JP2009144039A - Stabilizer for biodiesel fuel and biodiesel fuel composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stabilizer for a biodiesel fuel that improves production stability of a biodiesel fuel containing a fatty acid methyl ester, and to provide a biodiesel fuel composition containing the stabilizer. <P>SOLUTION: The stabilizer for the biodiesel fuel contains a fatty acid methyl ester expressed by general formula (1). In the formula, R represents a 11-20C straight-chain aliphatic hydrocarbon group; and n represents 0 or 1. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a stabilizer for biodiesel fuel having excellent stability and lubricity, and a fuel composition containing the same.

  Fossil fuels such as gasoline, light oil, and oil are mainly used as fuel oil, but when these fuels are consumed, carbon dioxide is released into the atmosphere, which is a major cause of environmental problems such as global warming. It is considered that. For these reasons, various methods have been considered to reduce the release of carbon dioxide into the environment.

  One method has been proposed to use biofuel. Biofuel is fuel oil obtained mainly from plants, and is used as fuel for automobiles or the like by mixing ethanol, methanol, fatty acid methyl ester, etc. with 100% or fossil fuel. Because biofuel is made from plants that consume carbon dioxide in the atmosphere, even if biofuel is released into the atmosphere as carbon dioxide by combustion, new plants that are the source of biofuel consume that carbon dioxide , Atmospheric carbon dioxide does not increase. Such biofuels have been started in various forms as described above, but can be directly applied to existing engine systems and do not require engine improvements. The study of biodiesel fuel containing the biofuel is most advanced (for example, see Patent Document 1).

  A specific additive may be added to such biodiesel fuel to improve filter clogging (see, for example, Patent Document 2). However, these additives have some effect on lowering the pour point, but precipitation or cloudiness may occur in biodiesel fuel due to long-term storage or storage in cold regions, which may cause problems with product stability. was there. If there is a problem with product stability, it cannot be distributed as a product and it will be difficult to spread biodiesel fuel widely.

JP 2007-016089 A JP-A-2005-350629

  Accordingly, the problem to be solved by the present invention is to provide a stabilizer for improving the product stability of a biodiesel fuel containing a fatty acid methyl ester, and to provide a biodiesel fuel composition containing the stabilizer. There is to do.

Accordingly, the present inventors have intensively studied, and found a stabilizer that improves the product stability of biodiesel fuel containing a fatty acid methyl ester, resulting in the present invention.
That is, the present invention provides the following general formula (1)

（式中、Ｒは炭素数１１〜２０の直鎖脂肪族炭化水素基を表し、ｎは０又は１を表す。）
で表される、脂肪酸メチルエステルを含有するバイオディーゼル燃料用の安定化剤である。

(In the formula, R represents a linear aliphatic hydrocarbon group having 11 to 20 carbon atoms, and n represents 0 or 1.)
It is the stabilizer for biodiesel fuel containing fatty acid methyl ester represented by these.

  The present invention suppresses precipitation and white turbidity generated in biodiesel fuel containing a fatty acid methyl ester, and improves product stability.

  The stabilizer of the present invention is represented by the following general formula (1).

（式中、Ｒは炭素数１１〜２０の直鎖脂肪族炭化水素基を表し、ｎは０又は１を表す。）

(In the formula, R represents a linear aliphatic hydrocarbon group having 11 to 20 carbon atoms, and n represents 0 or 1.)

  R in the general formula (1) is a linear aliphatic hydrocarbon group having 11 to 20 carbon atoms, such as an undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group. And alkyl groups such as nonadecyl group and eicosyl group; alkenyl groups such as undecenyl group, dodecenyl group, tridecenyl group, tetradecenyl group, pentadecenyl group, hexadecenyl group, heptadecenyl group, octadecenyl group, nonadecenyl group and eicosenyl group. Among these groups, when the value of n is 0, R is preferably the alkyl group, more preferably a linear alkyl group having 13 to 15 carbon atoms, and even more preferably a tridecyl group or a pentadecyl group. Moreover, when the value of n is 1, the said alkenyl group is preferable, a C15-C17 linear alkenyl group is more preferable, and a heptadecenyl group is the most preferable. When the carbon number of R is less than 11, the effect of stabilizing the biofuel is small, and when the carbon number exceeds 20, the solubility in the biofuel may be deteriorated or the effect of stabilizing the biofuel may be decreased.

  General formula (1) will be further described. The value of n in the general formula (1) is a number of 0 or 1. When n is 0, it becomes an alkyl or alkenyl diol, and when n is 1, it becomes an alkyl or alkenyl glycerol ester. Alkyl or alkenyl diol can be produced, for example, by oxidizing an olefin into an epoxy compound and then opening the epoxy ring, but all double bonds in the olefin are oxidized during olefin oxidation. Therefore, it is difficult to produce alkenyl diol with high yield. Therefore, an alkyl diol that is easy to produce is preferable, and an alkyl diol having 16 to 18 carbon atoms is more preferable because of its high effect of stabilizing biofuel.

  Any known method can be used as the alkyl or alkenyl glycerin ester, and examples thereof include esterification reaction between fatty acid and glycerin and transesterification reaction of fats and oils. Examples of the fatty acid used in the esterification reaction of fatty acid and glycerin include saturated fatty acids such as lauric acid, myristic acid, palmitic acid, stearic acid, eicosanoic acid; trauma acid, myristoleic acid, palmitoleic acid, oleic acid, petrothelin Examples thereof include unsaturated fatty acids such as acid, elaidic acid, linoleic acid, and linolenic acid. A monoester compound having a value of n of 1 can be obtained by subjecting these fatty acids and glycerin to an esterification reaction and purification by a known method, but the fatty acids may be mixed fatty acids. Moreover, the transesterification reaction of fats and oils can obtain the monoester compound which is a target object by mixing fats and oils (triglyceride), glycerol, and a catalyst, performing transesterification, and refine | purifying. As fats and oils, plant-based fats and oils such as beef tallow, pork tallow, milk fat, fish oil, and whale oil can be used. Among these production methods, since the target compound can be produced relatively freely, it is preferably produced by an esterification reaction between a fatty acid and glycerin.

  The obtained ester compound has a higher melting point when it is produced with a saturated fatty acid than when it is produced with an unsaturated fatty acid. A compound with a low melting point is easier to handle and more easily dissolved in biodiesel fuel, so ester compounds produced using unsaturated fatty acids are preferred, and those produced using oleic acid in consideration of performance. Is more preferable.

  The biodiesel fuel that can be used in the biodiesel fuel composition of the present invention will be described. Biodiesel fuel is a fuel containing light oil and fatty acid methyl ester. As light oil, it can be used for diesel engines such as No. 1 diesel oil, No. 2 diesel oil and No. 3 diesel oil standardized in JIS K2204. Any light oil can be used. Any fatty acid methyl ester can be used as long as it is made from natural oils and fats obtained from plants. Examples of plant-based natural fats and oils include, for example, linseed oil, eno oil, boar deer oil, olive oil, cacao butter, kapok oil, white mustard oil, sesame oil, rice bran oil, safflower oil, shea nut oil, cinnakiri oil, soybean oil, tea Examples include seed oil, camellia oil, corn oil, rapeseed oil, palm oil, palm kernel oil, castor oil, sunflower oil, cottonseed oil, coconut oil, tree wax, peanut oil, and mixtures thereof. Any known method for producing fatty acid methyl ester can be used. For example, the above-described natural fats and oils are heated in an alkali catalyst such as sodium hydroxide or potassium hydroxide to perform transesterification. And removing glycerin that is produced as an impurity.

  The blending ratio of the light oil and the fatty acid methyl ester may be blended so that the fatty acid methyl ester is 1 to 10% by mass, preferably 2 to 7% by mass with respect to the total amount of the biodiesel fuel. If the fatty acid methyl ester exceeds 10% by mass, the fuel is likely to deteriorate during storage, or a large amount of sludge is generated in the process of burning in a diesel engine, which is not preferable. In addition, if the fatty acid methyl ester is less than 1% by mass, it is insufficient to achieve the original purpose of reducing the amount of carbon dioxide emissions by reducing the amount of fossil fuel used, and the significance of biodiesel fuel is diminished. This is not preferable.

  Biodiesel fuel containing 1 to 10% by weight of fatty acid methyl ester can be stored as a stable solution if stored at room temperature for a short period of time, but the product may become cloudy due to long-term storage or storage in a cold region. Separation may occur. When such a problem occurs, the fuel filter of an automobile is likely to be clogged, resulting in a failure. Therefore, in order to spread biodiesel fuel, it is essential to improve its product stability.

  The method for stabilizing a biodiesel fuel of the present invention includes adding the stabilizer of the present invention to a biodiesel fuel containing a fatty acid methyl ester, preferably 1 to 10% by mass of a fatty acid methyl ester, This is a method for stabilizing the biodiesel fuel. By this method, the biodiesel fuel composition of the present invention can be obtained, but the blending amount of the stabilizer is preferably 10 to 500 ppm by mass, more preferably 30 to 300 mass with respect to the biodiesel fuel composition. What is necessary is just to mix | blend so that it may become ppm. If it is less than 10 ppm by mass, the effect of stabilizing the biodiesel fuel composition is small, and if it exceeds 500 ppm by mass, the stabilizer may be separated or precipitated at a low temperature, so the original purpose of stabilization cannot be achieved. There is a case.

  In the biodiesel fuel composition of the present invention, a cetane number improver is preferably blended as necessary. As the cetane improver, various compounds known as cetane improvers for light oils can be arbitrarily used. For example, 2-chloroethyl nitrate, 2-ethoxyethyl nitrate, isopropyl nitrate, butylnite. Rate, primary amyl nitrate, secondary amyl nitrate, isoamyl nitrate, primary hexyl nitrate, secondary hexyl nitrate, n-heptyl nitrate, n-octyl nitrate, 2-ethylhexyl nitrate, cyclohexyl night Although a rate, ethylene glycol dinitrate, etc. are mentioned, C6-C8 alkyl nitrate is especially preferable. The content of the cetane number improver is preferably 500 to 1400 ppm by mass, more preferably 600 to 1250 ppm by mass, and still more preferably 700 to 1100 ppm by mass with respect to the total amount of the composition. When the content of the cetane number improver is less than 500 ppm by mass, a sufficient cetane number improving effect cannot be obtained, and PM, aldehydes, and further NOx in diesel engine exhaust gas tend not to be sufficiently reduced. Moreover, even if content of a cetane number improver exceeds 1400 mass ppm, the effect corresponding to it cannot be expected, but it becomes only economically disadvantageous.

  In the biodiesel fuel composition of the present invention, it is preferable to blend a detergent as necessary. Examples of the detergent include imide compounds; alkenyl succinimides such as polybutenyl succinimides synthesized from polybutenyl succinic anhydrides and ethylene polyamines; polyhydric alcohols such as pentaerythritol and polybutyls. Succinic acid esters such as polybutenyl succinic acid ester synthesized from tenyl succinic anhydride; copolymer polymers such as dialkylaminoethyl methacrylate, polyethylene glycol methacrylate, vinyl pyrrolidone and alkyl methacrylate copolymers, carboxylic acids and amines Ashless detergents such as reaction products of alkenyl succinic acid imide and reaction products of carboxylic acid and amine are preferred. These detergents can be used individually by 1 type or in combination of 2 or more types. The blending amount of the cleaning agent is not particularly limited, but in order to bring out the effect of blending the cleaning agent, specifically, the effect of suppressing the clogging of the fuel injection nozzle, the blending amount of the cleaning agent is set to 30 to the total amount of the composition. It is preferable to set it as 300 mass ppm, and it is more preferable to set it as 60-200 mass ppm or more. If the amount is less than 30 ppm by mass, the above effect may not appear. If the amount exceeds 300 ppm by mass, an effect commensurate with it cannot be expected. Conversely, NOx, PM, aldehydes, etc. in diesel engine exhaust gas are increased. There is a case.

  In addition, in the biodiesel fuel composition of the present invention, other known fuel oil additives may be added alone or in combination of several kinds for the purpose of further improving the performance. Other additives include, for example, low-temperature fluidity improvers such as ethylene-vinyl acetate copolymer and alkenyl succinic acid amide; antioxidants such as phenols and amines; metal deactivators such as salicylidene derivatives; Anti-icing agents such as polyglycol ethers; corrosion inhibitors such as aliphatic amines and alkenyl succinic acid esters; antistatic agents such as anionic, cationic and amphoteric surfactants; colorants such as azo dyes; Antifoaming agents and the like. Although the addition amount of other additives can be arbitrarily determined, the addition amount of each additive is 0.001 to 0.5% by mass, more preferably 0.001 to 0.00%, based on the total amount of the composition. 2% by mass.

  Hereinafter, the present invention will be specifically described by way of examples. In the following examples and the like,% and ppm are based on mass unless otherwise specified.

<Additives>
(A-1) Glycerol monooleate (A-2) 1,2-octadecanediol (A-3) 1,2-hexadecanediol (A-4) Glycerol monostearate (B-1) Glycerol monocapryl Acid ester (B-2) Glycerol monodocosanoate (B-3) 1,2-decandiol (B-4) Erythritol monooleate (B-5) Sorbitan monooleate (B-6) Di Glycerol monooleate (B-7) Glycerol trioleate (B-8) Glycerol monoisostearate

(Production example): A-1
A 1000 ml flask equipped with a nitrogen inlet tube, a reflux tube, a stirrer, and a thermometer was charged with 92 g (1 mol) of glycerin, 298 g (1 mol) of oleic acid methyl ester and 0.4 g of sodium hydroxide as a catalyst. The temperature was raised to 0 ° C., and the pressure was gradually reduced to 10 kPa while removing methanol produced by the reaction. After reaching 10 kPa, the reaction was carried out at the same temperature for 5 hours. Thereafter, distillation was performed to obtain glycerol monooleate (A-1).
(A-2) The following compounds were also obtained in the same manner as (A-1). Specifically, 1 mol of a polyhydroxy compound such as glycerin and erythritol was reacted with 1 mol of a fatty acid methyl ester, and each compound was obtained by distillation.

<Stability test>
The said additive was adjusted with the mixing | blending shown in Table 1, and stability of biodiesel fuel was measured. That is, 50 ml of sample oil (a solution obtained by dissolving the above additives in a light oil containing 5% rapeseed methyl ester so as to have the addition amount shown in Table 1) is placed in a 100 ml screw mouth sample bottle. Was placed in a constant temperature bath at 20 ° C and 5 ° C. Three hours later, the state of the sample oil was visually confirmed. The results are shown in Table 1. Judgment criteria were expressed as “X” when the sample oil was separated or precipitated, “Δ” when the sample oil was uniform but turbid, and “◯” when the sample oil was clear and not turbid. The light oil used in the experiment was equivalent to No. 1 light oil standardized in JIS K2204.

  From Table 1, it can be seen that the product of the present invention has an effect of suppressing precipitation and white turbidity of biodiesel fuel containing fatty acid methyl ester. In addition, esters other than glycerin ester may not only be effective but may deteriorate stability. As described above, the product of the present invention is an additive excellent in improving the stability of biodiesel fuel.

Claims (5)

The following general formula (1)

(In the formula, R represents a linear aliphatic hydrocarbon group having 11 to 20 carbon atoms, and n represents 0 or 1.)
The stabilizer for biodiesel fuel containing fatty acid methyl ester represented by these.   2. The stabilizer according to claim 1, wherein n of the compound represented by the general formula (1) is 1 and RCOO is a group derived from oleic acid.   2. The stabilizer according to claim 1, wherein n of the compound represented by the general formula (1) is 0 and R is a linear alkyl group having 13 to 15 carbon atoms.   Biodiesel fuel characterized by containing 10 to 500 mass ppm of the stabilizer according to any one of claims 1 to 3 with respect to biodiesel fuel containing 1 to 10 mass% of fatty acid methyl ester. Composition.   The stabilization method of biodiesel fuel characterized by adding the stabilizer as described in any one of Claims 1-3 to the biodiesel fuel containing fatty acid methyl ester.