JP2008081730A - Biodiesel fuel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a biodiesel fuel with low clogging point and applicable in cold districts even in case of using a waste edible oil containing such as an animal fat as a raw material and further excellent in storage stability and combustion characteristics. <P>SOLUTION: The biodiesel oil containing methyl palmitate and methyl stearate contained in animal fat at rates of 10-25% makes excellent low-temperature characteristics, storage stability and combustion characteristics in a range of practical use, and a method for manufacturing it is provided. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to biodiesel fuel. In particular, the present invention relates to a biodiesel fuel having a clogging point lower than the original clogging point of animal fats and oils, starting from animal fats and oils. Moreover, it is related with the method of estimating the clogging point of the fuel derived from animal fats and oils.

In recent years, biodiesel fuel (hereinafter sometimes simply referred to as “BDF”) has attracted attention as an alternative fuel for oil in the face of fear that the oil will be depleted for about 40 years.
BDF is a fatty acid methyl ester obtained by transesterifying triacylglyceride, which is a main component of fats and oils, with methanol (hereinafter sometimes simply referred to as FAME). BDF is promising as a diesel fuel because it has a physical property similar to that of light oil and similar to calorific value, and has the feature of significantly reducing SOx and black smoke emissions compared to light oil. Currently, large-scale BDF production using virgin vegetable oils as raw materials is being put into practical use mainly in Europe. On the other hand, in Japan, not only virgin vegetable oils and fats but also BDF production methods using waste food oil as a raw material are being studied, but vegetable waste food oil is mainly used. As for the manufacturing method of BDF from most animal fats and oils, sufficient examination has not been made yet.
In addition, when waste food oil containing animal fats and oils is used as a raw material, the fuel properties of the manufactured BDF are uneven due to the variety of raw materials, and there are still problems in putting it into practical use as an alternative fuel for petroleum. It was. Therefore, it is necessary to construct a BDF production process that makes fuel properties uniform with respect to waste food oil containing animal fats and oils. The present inventors have heretofore confirmed that animal fats and oils have been used for existing vegetable fats and oils B
It has been reported that BDF can be produced in substantially the same yield as vegetable oil by the DF production method (Non-patent Document 1).
Hideki Nakamori, Katsumi Hirano et al., Proceedings of the 16th Annual Meeting of the Waste Society, p702-704 (2005)

As a result of comparing the fuel properties of animal fat BDF and vegetable fat BDF, it was found that animal fat BDF has a high clogging point and cannot be used in cold regions. In view of this problem, the object of the present invention is to provide a BDF having a certain property, particularly a low clogging point, even when waste food oil containing animal fat is used as a raw material. And
Another object is to provide animal fats and oils BDF excellent in practical combustion characteristics and storage stability.

As a result of intensive studies focusing on the coagulation process of animal and vegetable fats and oils BDF in order to solve the above problems, the present inventors surprisingly summed methyl palmitate and methyl stearate contained in animal fats and oils. The present inventors have found that there is a certain correlation between the content rate and the clogging point, and completed BDF excellent in low temperature characteristics.
In addition, as a result of examining the combustion characteristics and storage stability of animal fats and oils BDF, a practical BDF is completed by setting the total content of methyl palmitate and methyl stearate within a predetermined range. I was able to.
That is, the present invention relating to the BDF has the following configuration.
1) Biodiesel fuel containing fatty acid ester obtained by animal esterification using animal fats and oils as a raw material, and the total content of methyl palmitate and methyl stearate in the biodiesel fuel is 25% by weight or less Biodiesel fuel characterized by that.
2) A biodiesel fuel containing a fatty acid ester obtained by animal esterification using animal fats and oils, and having a clogging point of 5 ° C. or less.
3) Biodiesel fuel containing fatty acid ester obtained by animal esterification using animal fats and oils as a raw material, and the total content of methyl palmitate and methyl stearate in the biodiesel fuel is 10% by weight or more The biodiesel fuel as described in 1) above.
4) The biodiesel fuel according to any one of 1) to 3), further comprising light oil.
5) A biodiesel fuel characterized by adjusting the total content of methyl palmitate and methyl stearate in a biodiesel fuel in a method for producing biodiesel fuel by transesterification of animal fats with methanol. Manufacturing method.
6) The method for producing a biodiesel fuel as described in 5) above, wherein the adjustment of the total content of methyl palmitate and methyl stearate is performed by crystallization or mixing with other components.
7) For biodiesel fuel containing fatty acid esters obtained by methyl esterification using animal fats and oils as raw materials, measure each content of methyl palmitate and methyl stearate in the biodiesel fuel and determine the total content The method of predicting a clogging point by substituting into the following formula (1).

According to the present invention, even when animal fats and oils are included as raw materials, BDF excellent in low-temperature characteristics can be produced as in the case of using vegetable fats and oils as raw materials. Moreover, even if the raw material is as diverse as waste food oil, it is possible to produce a fuel having a certain level of properties and promote the reuse of waste food oil in Japan. Furthermore, by controlling the total content of methyl palmitate and methyl stearate, it is possible to produce a fuel having a desired clogging point, and to provide a BDF that meets different standards in Japan or the world it can.
Further, according to the present invention, it is possible to provide a practical BDF that takes advantage of the excellent fuel characteristics inherent in animal fats and oils and that is also excellent in storage stability.

Vegetable oils and fats, animal fats and oils, and mixtures thereof can be used as the oil and fat materials used in the present invention. Further, not only virgin oil but also waste food oil can be used. In particular, if the present invention is used for waste food oil that is a mixture whose clogging point is unknown as it is, it can lead to reuse of the waste food oil and a great effect can be expected.

Animal fats and oils as used in the present invention refers to animal fats and oils, for example, fats and oils that are constituents of pigs, cows, chickens, etc., and animal fats and oils are used as they are or as they are physically or chemically treated. In addition, it is intended to include those in which the composition of the components is changed. Fatty acid methyl ester is obtained from the animal oil-derived component by a reaction of transesterification with methanol under alkaline conditions. Fatty acid methyl ester derived from animal fats is equivalent to light oil in density, cetane number, and calorific value.
Can be used as an alternative oil

The biodiesel fuel (BDF) referred to in the present invention is used as a fuel by itself or by mixing with other fuels such as light oil, and those that are derived from animal or vegetable oils and fats are particularly preferably used. It is done. In the present specification, BDF produced using animal fats and oils as raw materials may be simply referred to as animal fats and oils BDF. The ratio in the case of mixing with other fuel is not particularly limited as long as it satisfies the performance required as a fuel.

The present invention is based on the finding that there is a certain correlation between the total content of methyl palmitate and methyl stearate contained in BDF and the clogging point. Initially,
The cause of clogging at a low temperature was examined by considering the change in kinematic viscosity accompanying a decrease in temperature, but from the examples described later, the change in kinematic viscosity accompanying a decrease in temperature was observed in both animal oil BDF and soybean oil BDF. It was found that the cause of clogging was not the deterioration of fluidity.
The components of BDF derived from animal fats are methyl myristate (C14Me), methyl palmitate (C16Me), methyl palmitate (C16: 1Me), methyl margarate (C17Me), methyl stearate (C18Me), oleic acid Methyl (C18
: 1Me), methyl linoleate (C18: 2Me), methyl linolenate (C18: 3Me)
), Methyl docosenoate (C22: 1Me), etc., of which methyl palmitate (
It was found that the following relational expressions (1) and (2) hold between the total content of C16Me) and methyl stearate (C18Me) and the clogging point. Here, Expression (1) is obtained by transforming Expression (2) into an expression of the solidification start temperature T. In the following formula, the solid concentration corresponds to the total content of C16Me and C18Me. Since the clogging point of the BDF has a high correlation with the temperature at which solidification starts, the solidification start temperature is used as an index for the clogging point in the present application.
In the following formula, the activity coefficient of the solid phase is a so-called correction coefficient for adjusting the theoretical formula to the actual measurement value, and 0.75 was appropriate in the present invention from the test described later. The heat of fusion of pure component s is C1
The heat of fusion of 6Me 55350 J / mol, the heat of fusion of C18Me 64430 J / mol (edited by the Japan Oil Chemists' Society, 4th edition, Petrochemical Handbook, (Maruzen), p278 (2001)) is the component ratio of solid phase C16Me : C18Me = 57.5: A value obtained by arithmetic averaging at 42.5,
58969.80 J / mol (same as above). The solidification start temperature of the pure component s is C16Me:
The measured value of the solidification start temperature of the sample adjusted at a ratio of C18Me = 57.5: 42.5 (24.
8 ° C. + 273.15 = 297.95K).

  FIG. 5 shows a graph representing the relational expression (1). According to this figure, for example, in order to achieve the case where the solidification start temperature (T), which is the BDF standard of Kyoto City, is −5 ° C., the total content of C16Me and C18Me needs to be 15% or less. I understand that there is. In Europe, for example, the solidification start temperature of BDF is required to be −20 to 5 ° C. although it is not clear because there is a considerable temperature difference depending on the region. Therefore, it can be seen that the total content of C16Me and C18Me in this case needs to be 4% or less if it is −20 ° C. or less and 25% or less if it is 5 ° C. or less.

As described above, the present invention is characterized in that the total content of methyl palmitate and methyl stearate is adjusted so as to satisfy the low temperature characteristics required in the region where biodiesel fuel is used. In order to improve the low temperature characteristics, the total content is preferably, for example, 25% by weight or less, more preferably 15% by weight or less, and most preferably 10% by weight or less. When the total content is higher than 25% by weight, the solidification start temperature becomes higher than 5 ° C., which is not desirable from the viewpoint of low temperature characteristics.
In other words, the biodiesel fuel of the present invention preferably has a clogging point of 5 ° C. or lower, more preferably 0 ° C. or lower, and most preferably −5 ° C. or lower.

Although the BDF of the present invention can be used as a fuel as it is, it is a fuel having a liquid property without being solidified even in a low temperature range, and therefore can be used by mixing with other liquid fuels. Examples of other liquid fuels include light oil and heavy oil, which are commercially available fuels. Among them, light oil is preferably used as the fuel for the diesel engine.

In the BDF of the present invention, from the viewpoint of combustion characteristics, the total content of methyl palmitate and methyl stearate needs to be 10% or more, and more preferably 13% or more. This is because if the content is less than 10%, the ignitability deteriorates, and the higher the content, the better the ignitability.
Therefore, as a practical range satisfying both the low temperature characteristics and the combustion characteristics, the total content of methyl palmitate and methyl stearate is preferably 10% or more and 25% or less, and 13% or more and 25%. % Or less is more desirable, and 13% or more and 15% or less is most desirable.
In addition, it turned out that storage stability does not depend on the content rate which added the palm oil acid methyl and methyl stearate of animal fats and oils BDF. That is, it has been found that the storage stability is due to an increase in kinematic viscosity due to oxidation of methyl linolenate, but animal fats and oils BDF originally have a low absolute content of methyl linolenate. Therefore, by adjusting the total content of methyl palmitate and methyl stearate from the above-mentioned low temperature characteristics and combustion characteristics, a practical BDF excellent in storage stability, low temperature characteristics and combustion characteristics can be obtained.

The method for producing biodiesel fuel (BDF) according to the present invention is a method for producing fatty acid methyl ester (FAME) by transesterifying animal oil with methanol under alkaline conditions.
It is carried out by adjusting the total content of methyl palmitate and methyl stearate in DF to be 25% by weight or less. As described above, the total content of C16Me and C18Me in BDF varies depending on the required clogging point (solidification start temperature). To reduce the content, a method of diluting by mixing with other components Alternatively, a method of depositing and removing as a solid by crystallization may be used.
For dilution, for example, at the raw material stage, animal fats and oils are diluted with vegetable fats and oils, and these mixed fats and oils are transesterified with methanol to obtain a FAME that has fewer C16Me and C18Me than animal fats and oils alone. Can do. Or from animal fats and oils, FAM
After obtaining E, a method of mixing and diluting FAME other than C16Me and C18Me can be mentioned. The former diluting liquid includes vegetable oils such as soybean oil, rapeseed oil and sunflower oil, and the latter diluting liquid includes vegetable oil-derived BDF or light oil having a low content of C16Me and C18Me.
Crystallization is performed using, for example, a crystallizer configured such that the temperature can be independently controlled by a refrigerant in the center of the reaction vessel, with a stirring blade and the lower and upper portions of the vessel. By introducing BDF into the inside of this device and controlling the temperature of the upper part of the tank from 10 ° C. to −10 ° C., C16Me and C18Me
Can be deposited.

According to the present invention, a method for evaluating or predicting the clogging point of BDF containing animal fat-derived components is performed as follows. First, the contents of methyl palmitate and methyl stearate are measured and summed, and the ratio to the total BDF, that is, the content is obtained.
2) The clogging point (solidification start temperature) is calculated by applying to 2) and evaluated or predicted.

[Test Example 1] Production of BDF Free fatty acid removal As samples, beef tallow reagent (manufactured by Wako Pure Chemical Industries, Ltd.), pork tallow (manufactured by Mikiya Shoten Co., Ltd.),
Soybean oil reagent (manufactured by Wako Pure Chemical Industries, Ltd.) was used. About these, the acid value analysis shown below was performed and the sodium hydroxide theoretical amount required for neutralization was computed. Sodium hydroxide, 1.1 times the acid value analysis value, was added to 10 ml of pure water, stirred with 150 g of sample at 80 ° C. for 30 seconds, centrifuged at 3000 rpm for 5 minutes, and the obtained upper layer was tested as follows. Used as a treatment oil.
2. Acid value analysis method 20 g of a sample was weighed into an Erlenmeyer flask, and 100 ml of neutral solvent (diethyl ether: 99
. Add 5 ml of phenolphthalein indicator to 5 vol% ethanol = 1: 1)
. What was neutralized with a 1 mol / L potassium hydroxide-ethanol solution was added and dissolved. In the case of a solid sample, the solvent was added after dissolving on a hot water bath. Titration was performed with a 0.1 mol / L potassium hydroxide standard solution, and the end point of neutralization was determined when the color change of the indicator continued for 30 seconds.
Acid value = (5.611 × A × F) / B (3)
However, A: 0.1 mol / L potassium hydroxide standard solution usage [ml]
F: Factor of 0.1 mol / L potassium hydroxide standard solution
B: Sample collection amount [g]

3. Production of Crude BDF 100 g of treated oil of each sample, 30 g of methanol, and 0.45 g of sodium hydroxide were put into a separable flask (manufactured by Shibata Kagaku Co., Ltd.), and heated and stirred at 60 ° C. for 30 minutes using a hot stirrer. At this time, a Dimroth cooler was provided on the top of the separable flask cover (manufactured by Shibata Kagaku Co., Ltd.) to reflux the volatile methanol. Immediately after completion of the reaction, the mixture was transferred to a separatory funnel and allowed to stand for 30 minutes. Methanol was distilled off from the obtained upper layer to obtain crude BDF.

4). Purification of crude BDF 50 wt% pure water was added to each crude BDF obtained above, and the mixture was heated and stirred at 70 ° C. for 5 minutes using a hot stirrer. Then, it moved to the separatory funnel, and left still and separated for 30 minutes, and it divided into the upper layer and the lower layer. The above operation was repeated once for the upper layer, and the obtained upper layer was designated as each BDF.

[Test Example 2] Low-temperature characteristic test Analysis of kinematic viscosity of each BDF Analysis of kinematic viscosity was performed according to JIS-K2283.
FIG. 1 shows a calculation method defined in “Method of Estimating Kinematic Viscosity and Mixing Ratio” in JIS-K2283 (edited by the Japanese Standards Association, JIS Handbook 25 Petroleum, (Japan Standards Association), p893-900 (2
005)) shows the relationship between the temperature and kinematic viscosity of each BDF. For reference, the BDF standards of Kyoto City are also shown.
From FIG. 1, it was found that the kinematic viscosities of beef tallow BDF and pork tallow BDF are within the standards of BDF in Kyoto City, and the change in kinematic viscosity accompanying a decrease in temperature is almost equivalent to that of soybean oil BDF. That is,
This test revealed that the cause of clogging was not the deterioration of fluidity.

2. Clogging point analysis of each BDF The clogging point analysis was performed according to JIS-K2288. FIG. 2 shows a DSC cooling curve for each BDF. For reference, the clogging points of each BDF are also shown.
From FIG. 2, it was found that each BDF starts to solidify at a temperature substantially equal to the clogging point. From the above, it was found that the cause of clogging was solid precipitation. From this test result, since the clogging point of BDF has a high correlation with the temperature at which solidification starts, the solidification start temperature is used as an index of the clogging point in the present application. FIG. 2 shows that each BDF has two coagulation peaks. This means that the solid-liquid equilibrium state of each BDF composed of multi-component FAME is a eutectic type in which there is no mutual dissolution in the solid phase. Conceivable.
(DSC analysis)
Each BDF is EXSTAR6100 DSC made by SII Nano Technology Co., Ltd.
Was used for differential scanning calorimetry. In addition, the temperature at which the peak began to appear in the DSC temperature decrease curve was defined as the solidification start temperature.
<Measurement conditions>
Measurement range -40 to + 40mW
Measurement sensitivity 0.2μW
Measurement conditions Nitrogen flow rate 50ml / min
Temperature drop rate 5 ℃ / min
Sampling frequency 3 times / second

3. Fatty acid composition analysis of each BDF The FAME composition was quantified in accordance with the fatty acid composition analysis (FID temperature rising gas chromatograph method) of the standard oil analysis test method of the Japan Oil Chemical Society.
The fatty acid composition (FAME composition) analysis result of each BDF is shown in FIG. For reference, F
The solidification start temperature of AME is also shown. From FIG. 3, saturated FAMEs having 14 or more carbon atoms are BDs.
Since the solidification start temperature was higher than that of F, the precipitated solids were assumed to be methyl palmitate (C16Me) and methyl stearate (C18Me), which are the main components of each BDF.

4). Preparation of added BDF To 1.6 g of beef tallow BDF, 0.4 g of methyl oleate (hereinafter, C18: 1Me, manufactured by Sigma Aldrich Japan Co., Ltd.) or methyl stearate (C18Me, manufactured by Tokyo Chemical Industry Co., Ltd.) is added, Beef tallow BD containing 20 wt% of FAME standard reagent
F was prepared. Furthermore, what changed the content rate of C18: 1Me or C18Me standard reagent from 20 wt% to 50 wt% and 80 wt% was prepared. These samples were stirred for 10 minutes under ultrasonic irradiation and subjected to DSC analysis. The results are shown in FIG. According to this, C18M
It can be understood that C18Me is the cause of solidification because the solidification start temperature increases as the addition rate of e increases. In contrast, as the addition rate of C18: 1Me increases, the solidification start temperature decreases, indicating that C18: 1Me is not the cause of solidification.

5. Relationship between the total content of C16Me and C18Me and the solidification start temperature FIG. 5 shows the relationship between the total content of C16Me and C18Me calculated from the FAME composition of each BDF and the solidification start temperature (actual measurement value) with a broken line and a plot. Each BDF here is
BDF and beef tallow BD produced from beef tallow, pork tallow, chicken tallow, soybean oil, mixed oil of beef tallow and soybean oil
BDF added by changing the mixing ratio of C18: 1Me to F.
For reference, the BDF standard of Kyoto City, the solid-liquid equilibrium relational expression in the eutectic type, assuming that the solid content is the total content of C16Me and C18Me, and the activity coefficient of the solid phase is 1. The calculated value of the solidification start temperature obtained from the equations (1) and (2) is shown by a solid line (supervised by the Chemical Engineering Society, separation, (Baifukan), p16-18 (1995)).
In the formula, the solid concentration corresponds to the total content of C16Me and C18Me. The activity coefficient of the solid phase is a so-called correction coefficient for adjusting the theoretical formula to the actually measured value, and 0.75 is appropriate in the present invention. The heat of fusion of the pure component s is the heat of fusion of C16Me 55350 J / mol, C18
Heat of fusion of 64430 J / mol (edited by Japan Oil Chemists' Society, 4th edition, Petrochemical Handbook, (Maruzen),
p278 (2001)) is the component ratio of the solid phase C16Me: C18Me = 57
. 5: The value obtained by arithmetic averaging at 42.5, which is 58969.80 J / mol (same as above).
The solidification start temperature of the pure component s is a measured value (24.8 + 273.15 = 297.95 K) of the solidification start temperature of the sample adjusted at a ratio of C16Me: C18Me = 57.5: 42.5.

Moreover, the said Formula (2) is deform | transformed into the formula of the solidification start temperature T, and is shown to following formula (1).

From FIG. 5, it can be seen that the actual measurement value (plot and broken line) and calculated value (solid line) of the solidification start temperature show the same tendency. Further, the calculated values almost coincided with the actually measured values when corrected assuming that the activity coefficient of the solid phase is 0.75. That is, from the formula (1), the solidification start temperature is C16Me and C1.
It is considered to be uniquely determined by the total content of 8Me. From the above, C16M
It was found that the clogging point depends on the total content of C16Me and C18Me because e and C18Me solidify and cause clogging. From the calculated value (with correction) of the solidification start temperature in FIG. 5, the clogging point can be lowered to −5 ° C. or less (Kyoto City BDF standard) by reducing the total content of C16Me and C18Me to 15% or less. It was.

6). FIG. 6 is a plot showing the relationship between the total content of C16Me and C18Me calculated from the FAME composition of each BDF and the solidification start temperature (actually measured value) in terms of the solidification start temperature for each additive type and the total content of C16Me and C18Me. . Each BDF here refers to BDF manufactured from beef tallow, pork tallow, chicken tallow, soybean oil, C18: 1Me, C18: 2Me, C18Me,
BDF added by changing the mixing ratio of light oil. The beef tallow model BDF refers to BDF in which a single standard reagent is mixed in accordance with the fatty acid composition of beef tallow BDF. According to this result, regardless of the type of fats and oils used as raw materials and the types of additives, all animal fats and oils are almost on the same straight line, and the total content of C16Me and C18Me and the start of solidification are obtained. It has been found that there is a certain relationship between the temperature and the temperature regardless of the types of additives and raw oils and fats.

[Test Example 3] Adjustment of total content of C16Me and C18Me Adjustment by dilution By adding C18: 1Me to BDF derived from animal fats and oils by the same method as in “Test Example 2, 4. Preparation of added BDF”, the concentrations of C18Me and C16Me can be diluted. It was.

2. Adjustment by crystallization FIG. 7 shows an example of a crystallization apparatus. A stirring blade is installed at the center of the 500 mL reaction tank, and a refrigerant is installed at the bottom. A refrigerant circulates outside the tank upper portion. BDF inside such a device
300 g was charged, the top of the tank was gradually cooled from 10 ° C. to −10 ° C., and the bottom of the tank was 10 ° C. to −5 ° C.
The mixture was stirred while controlling the temperature and reacted for 120 minutes to precipitate C16Me and C18Me. Table 1 shows FAME compositions before and after crystallization. C16Me was 24.6% before crystallization, but decreased to 5.0% after crystallization. C18Me was 18.0% before crystallization, but decreased to 4.1% after crystallization. As a result, the total content of these substances could be reduced from 42.6% to 9.1% by crystallization. When the same test was conducted on pork fat, the same results as in the case of beef tallow were obtained.

[Test Example 4] Mixing with other fuels Mixed beef tallow BDF and light oil Tallow BDF and No. 2 light oil were mixed so that the content of beef tallow BDF was 20 wt%, 50 wt% and 80 wt%. These samples were stirred for 10 minutes under ultrasonic irradiation and subjected to DSC analysis. The results are shown in FIG.
From this, beef tallow BDF alone has a solidification start temperature of about 10 ° C, but beef tallow light oil mixed B
In DF, the solidification start temperature decreased as the light oil content increased, and was approximately −5 ° C. for light oil 80% and beef tallow BDF 20%. C16Me and C18M of beef tallow BDF used here
The total content of e is 44.8%. Beef tallow BDF content is 20wt% and 50wt%
And 80 wt% are respectively 9.9 converted to the total content of C16Me and C18Me.
00, 22.41, 35.85%.

2. Mixing of beef tallow BDF and soybean oil BDF Beef tallow reagent and soybean oil reagent are previously mixed in a weight ratio of 2: 1 or 1: 2, and ~ 3. The same operation was performed to produce beef tallow soybean oil mixed BDF. DSC analysis was performed on this BDF. The results are shown in FIG.
Thus, beef tallow BDF alone has a solidification start temperature of about 10 ° C., but beef tallow soy mixed BDF decreases the coagulation start temperature as soybean BDF content increases, soy oil B
In DF100%, it was about -5 degreeC.

[Test Example 5] Storage stability test Peroxide value (POV), kinematic viscosity measurement 60 g of each BDF was put into a 100 ml Erlenmeyer flask and allowed to stand for 0, 4, 8, 12, 16 weeks in an incubator at 40 ° C. (manufactured by Sansho Corporation, SIB-35). And stored. For each stored BDF, a peroxide value (POV) measurement (acetic acid-isooctane method) and a kinematic viscosity measurement based on the standard oil and fat analysis test method 2.5.2.1 were performed. Each stored BDF was dissolved in propanol / hexane (5: 4) and subjected to high performance liquid chromatography / mass spectrometry (LC-MS). The analysis conditions are shown below. Furthermore, mass spectrometry was performed by APCI method using a mass spectrometer (LCQ, manufactured by Thermo Electron). The results are shown in FIGS.
(LC-MS analysis conditions)
Apparatus: Waters, Alliance 2695
Column: L-column ODS (2.1 mm × 150 mm, particle diameter 5 μm)
Moving layer:
A: water, B: acetonitrile, C: propanol / hexane (5: 4)
Gradient was 30% A + 70% B for 0 minute, 100% B for 10 minutes, 50% B + 50% C for 20 minutes, and then held at 50% B + 50% C for 20 minutes.

2. Results FIG. 10 shows changes with time in kinematic viscosity in each BDF. In the figure, the Kyoto City BDF standard is also shown. From this, beef tallow BDF shows almost no generation of peroxide (POV) with time, and kinematic viscosity does not change and is almost constant. On the other hand, in the soybean oil BDF, a peroxide is generated after 4 weeks, and the kinematic viscosity is increased accordingly. Furthermore, the kinematic viscosity of soybean oil BDF is outside the BDF standard of Kyoto City after 16 weeks. From this, it is considered that the kinematic viscosity increased due to the peroxide generated from BDF. Therefore, it can be said that beef tallow BDF is superior in storage stability to soybean BDF.

  Next, further studies were made on POV generation. FIG. 11 shows total ion chromatograms obtained by performing LC-MS analysis at 0 weeks and 4 weeks after storage of soybean oil BDF. A new peak appears after 4 weeks (10 to 15 min), and FIG. 12 shows the results of mass spectrum analysis obtained by performing mass analysis on this new peak. From this, the detected spectrum was presumed to be a hydroperoxide or dihydroperoxide fragment ion of methyl linolenate (C18: 3Me). Methyl linolenate is known to be highly reactive because it has three double bonds (Ken Fujitani, Story of Oil), (Tatsukabo), p84-87 (1996)). It is thought that it was oxidized to hydroperoxide during a certain period.

  From the above, it was shown that the storage stability of BDF depends on the content of methyl linolenate (C18: 3Me). From Table 2, it was found that animal fats and oils BDF had a low content of methyl linolenate compared to vegetable fats and oils BDF and were excellent in storage stability. In addition, when C16Me and C18Me are reduced for improving the low-temperature characteristics, the methyl linolenate content is relatively increased, but the amount is very small, so it is considered that the storage stability is not affected.

[Test Example 6] Combustion characteristics evaluation test Measurement of calorific value The higher calorific value of BDF and diesel oil was measured using a Ikeno digital calorimeter (OSK100-5, manufactured by Ogawa Sampling Co., Ltd.). At this time, the amount of water generated was measured, and the lower heating value was calculated.
2. Actual machine performance test As a test engine, a vertical air-cooled four-cycle single-cylinder diesel engine (L48A) manufactured by Yanmar Diesel Co., Ltd. was used. Table 3 shows the engine specifications of the diesel engine. The test was performed at an engine speed of 3000 rpm and a constant fuel injection amount of 0.2 ml / s.

4). Results (1) Calorific Value FIG. 13 shows the lower calorific value of BDF, and Table 4 shows the elemental analysis values of BDF. For reference, the calorific value of light oil is also shown. From this, it can be seen that the lower calorific value of beef tallow BDF is almost the same as that of soybean oil BDF although it is slightly inferior to light oil. Moreover, from Table 4, since the elemental analysis value of beef tallow BDF and soybean oil BDF was substantially the same, it is thought that there is almost no change of the emitted-heat amount by FAME composition. Therefore, it was found that BDF has almost the same calorific value regardless of the type of raw material fat.

(2) Actual machine performance test / ignitability test FIG. 14 shows a diagram of acupressure of each BDF in a steady state (combustion chamber wall surface temperature: about 600 ° C.). For reference, a diagram of light oil acupressure is shown in the figure.
From the steady-state acupressure diagram, beef tallow BDF, chicken tallow BDF, and soybean oil BDF exhibit ignitability and output equivalent to or better than diesel oil, and are considered to function sufficiently as diesel fuel.
Here, the cetane number of FAME is shown in Table 5 (Knothe, G., Mathaeus, A., C., Ryan, T., W., III, Fuel, 82, 971-975 (2003)). As the degree of saturation increases, the cetane number decreases. This is because the unsaturated bond is considered to be unstable because the carbon-carbon bond is sterically planar with respect to the saturated bond. Therefore, beef tallow BDF, chicken tallow BDF, and soybean oil BDF have a high content of saturated FAME in this order (from Table 2). It can be estimated that there will be a difference in output.
And when examining how to rise in the steady-state acupressure diagram of each BDF in detail, soybean oil BDF and light oil show almost the same rise, but next, chicken fat BDF is the fastest, and beef tallow BDF is the first. It shows an early rise. These saturated fatty acid contents (C16Me + C18Me total contents) are 13.3%, 22.3%, and 42.6% for soybean oil BDF, chicken fat BDF, and beef tallow BDF, respectively. This is the same order as the difference in power and output, thus confirming that the above estimation is correct.
From the above, in order to obtain combustion characteristics equivalent to that of light oil, the total content of C16Me + C18Me needs to be 10% or more, and 13% or more is more desirable.

  According to the present invention, even when animal fats and oils are included as raw materials, fuel excellent in low-temperature characteristics can be provided as in the case of using vegetable fats and oils as raw materials. Moreover, even if the raw material is as diverse as waste food oil, it is possible to produce a fuel having a certain level of properties and promote the reuse of waste food oil in Japan.

It is a figure which shows the relationship between the temperature of each BDF, and kinematic viscosity. It is a figure which shows the DSC temperature fall curve of each BDF. It is a figure which shows the FAME composition of each BDF. It is a figure which shows the solidification start temperature change of the beef tallow BDF by FAME addition. It is a figure which shows the relationship between the total content rate of C16Me and C18Me, and a solidification start temperature. It is a figure which shows the coagulation start temperature according to each BDF and additive kind. It is a figure which shows the conceptual diagram of a crystallizer. It is a figure which shows the relationship between the mixing rate of beef tallow BDF and light oil, and the coagulation start temperature. It is a figure which shows the relationship between the mixing rate of beef tallow BDF and soybean oil BDF, and coagulation start temperature. It is a figure which shows POV and kinematic viscosity change accompanying storage period progress of each BDF. It is a figure which shows the total ion chromatogram of soybean oil BDF. It is a figure which shows the mass spectrum of the production | generation substance in soybean oil BDF after four-week progress. It is a figure which shows the low calorific value of BDF. It is a figure which shows the acupressure diagram of BDF in a steady state.

Explanation of symbols

1 Stirring blade 2 Refrigerant 3 Reaction tank 4 Crystallizer

Claims (7)

Biodiesel fuel containing fatty acid ester obtained by animal esterification using animal fats and oils as a raw material, and the total content of methyl palmitate and methyl stearate in biodiesel fuel is 25% by weight or less A featured biodiesel fuel. A biodiesel fuel containing a fatty acid ester obtained by animal esterification using animal fats and oils, and having a clogging point of 5 ° C or lower. A biodiesel fuel containing a fatty acid ester obtained by animal esterification using animal fats and oils as a raw material, wherein the total content of methyl palmitate and methyl stearate in the biodiesel fuel is 10% by weight or more. The biodiesel fuel according to 1. Furthermore, the biodiesel fuel in any one of Claims 1-3 containing a light oil. A method for producing biodiesel fuel by transesterification of animal fats with methanol, wherein the total content of methyl palmitate and methyl stearate in the biodiesel fuel is adjusted. Method. The method for producing a biodiesel fuel according to claim 5, wherein the adjustment of the total content of methyl palmitate and methyl stearate is performed by crystallization or mixing with other components. For biodiesel fuel containing fatty acid ester obtained by animal esterification using animal fats and oils as raw materials, each content of methyl palmitate and methyl stearate in biodiesel fuel is measured, and the total content is obtained, A method for predicting a clogging point by substituting it into equation (1).