JP2010168537A - Light oil fuel composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light oil fuel composition which has improved rubber swelling property while being composed of only paraffins. <P>SOLUTION: The light oil fuel composition does not include styrene compounds, diene compounds, and condense polycyclic aromatics in the main constitution, is practically composed of only paraffins, and has a content of 1-15C paraffins of 28 vol.% or higher and a content of 18≤C normal paraffins of 11 vol.% or lower. Compositions containing other than paraffins are allowed to be included as impurities. The rate of the content of 15≥C paraffins is preferably 40 vol.% or higher, more preferably 50 vol.% or higher. The rate of the content of 18≤C normal parafin is preferably is 8 vol.% or less, more preferably is 5 vol.% or less. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a light oil fuel composition used for a diesel engine or the like.

  In recent years, various studies have been conducted to use Fischer-Tropsch fuel (hereinafter referred to as FT fuel) as automobile fuel in Japan. FT fuel is a fuel obtained by synthesizing raw materials such as natural gas, coal and biomass by the Fischer-Tropsch method via carbon monoxide and hydrogen synthesis gas. Often used. For example, natural gas as a raw material is often called GTL, coal as a raw material is called CTL, and biomass as a raw material is often called BTL. On the other hand, the term GTL is sometimes used as a generic term for fuels obtained by the Fischer-Tropsch method. In the present invention, the term FT fuel is used as a generic term for fuels obtained by the Fischer-Tropsch method. It is assumed that GTL, CTL, BTL, etc. are included in the FT fuel.

  As described above, since this FT fuel is synthesized using natural gas, coal, biomass or the like as a raw material, it is used as an alternative fuel for petroleum, and since it does not contain sulfur or aromatic hydrocarbons, sulfur from the engine. It is expected to be used as an environment-friendly diesel fuel that suppresses the emission of oxides and particulate matter (PM). For example, as reported in “Regarding marketability of liquid fuel (GTL) from natural gas” (Non-Patent Document 1) in the November 2001 issue of the energy economy issued in 2001, Some areas have already been commercialized.

  On the other hand, however, some problems have been pointed out in using FT fuel as light oil fuel in Japan, and one of the problems is the influence on rubber materials. For example, in Non-Patent Document 1 described above, the rubber material is rich in paraffin and has a small aromatic content as a problem of FT light oil (of FT fuel, properties such as density and distillation properties correspond to light oil fuel). It has been pointed out that the swellability of seals such as these is low, but it has been proposed that this can be accommodated by changing the seal design. In addition, a method for solving this sealing problem without changing the design of the seal has been considered. For example, in Japanese Patent Application Laid-Open No. 2006-16541 (Patent Document 1), a total aromatic content is blended with GTL light oil. Thus, a fuel oil composition that is inferior in the function of swelling existing gas oil and rubber material (hereinafter referred to as rubber swelling property) has been proposed. In addition, in the Japanese Patent Application No. 2007-302892 (Patent Document 2), the inventors of the present invention are based on FT fuel by determining the blending ratio of FT light oil and fatty acid methyl ester (FAME) by a specific formula. It has been proposed to give rubber swelling properties to light oil fuel compositions.

JP 2006-16541 A Japanese Patent Application No. 2007-302892

Energy Economy November 2001 “Marketability of Liquid Fuel (GTL) from Natural Gas”

  However, one of the characteristics of FT gas oil is that it does not cause environmental problems related to aromatics and sulfur. This characteristic is attributed to the feature of being composed only of paraffin. In the conventional technology which corresponds to the property that the rubber swellability is poor by blending a fuel composition other than FT light oil, there is a problem that the original characteristics of this FT light oil are not fully utilized.

  Therefore, an object of the present invention is to provide a light oil fuel composition having improved rubber swellability while being substantially composed only of paraffin.

  The light oil fuel composition according to the present invention is substantially composed only of paraffin, and the ratio of the paraffin content having 15 or less carbon atoms is 28% by volume or more, and the ratio of normal paraffins having 18 or more carbon atoms is 11% by volume. It is as follows. The ratio of the content of paraffin having 15 or less carbon atoms is preferably 40% by volume or more, more preferably 50% by volume or more. The ratio of the normal paraffin having 18 or more carbon atoms is preferably 8% by volume or less, more preferably 5% by volume or less.

  The content of paraffin having 15 or less carbon atoms and normal paraffin having 18 or more carbon atoms was determined by ASTM D 2887 “Standard Test Method for Boiling Range Distribution of Petroleum Fractionation by Gas Chromatography”. It can be obtained by calculating the hydrocarbon content for each carbon number from the gram.

  In the present invention, the term “substantially paraffin only” means that styrene compounds, diene compounds, and condensed polycyclic aromatics are not included in the main components, and a composition other than paraffin is included as an impurity. Is acceptable. FT gas oil in which the total mass or volume of isoparaffin and normal paraffin is 99% or more excluding a slight amount of impurities is a gas oil fuel composition of the present invention composed essentially of paraffin. In addition to the Fischer-Tropsch method, there is also a method for hydrotreating animal and vegetable fats and oils that are biomass raw materials as a method for producing a fuel composed only of paraffin. Among the fuels produced in this way, those corresponding to light oil are called second-generation biodiesel fuels, etc., but this second-generation biodiesel fuel is also only paraffin in the practice of the present invention. It is the light oil fuel composition comprised by these.

Addition of additives also does not prevent the diesel fuel composition from being substantially paraffin only. What added the additive as needed is also contained in the light oil fuel composition of this invention.
For example, a low-temperature fluidity improver can be added from the viewpoint of preventing transportation troubles due to precipitation of wax at low temperature and blocking of a filter installed in a fuel system of a vehicle. As the low temperature fluidity improver, any known low temperature fluidity improver can be used as long as it is compatible with paraffin. Typical low-temperature fluidity improvers include commercially available low-temperature fluidity improvers such as ethylene-vinyl acetate copolymer, ethylene-alkyl acrylate copolymer, alkenyl succinic acid amide, chlorinated polyethylene, and polyalkyl acrylate. . These compounds can be used alone or in combination of two or more. Among these, ethylene-vinyl acetate copolymer and alkenyl succinic acid amide are particularly preferable. The content of the low temperature fluidity improver can be appropriately blended so as to satisfy the pour point and clogging point specified in JIS K 2204, which is a JIS standard for light oil, for example, but is usually 50 to 1000 ppm. Here, the pour point means the pour point obtained by JIS K 2269 “Pour point of crude oil and petroleum products and the cloud point test of petroleum products”, and the clogging point is JIS K 2288 “Petroleum products—light oil—mesh”. It means the clogging point obtained by the “clogging point test method”.

  Further, a lubricity improver can be added to prevent wear of fuel supply pump parts and the like. As the lubricity improver, any known lubricity improver can be used as long as it is compatible with FT gas oil. Typical lubricity improvers include commercially available lubricity improvers such as acid-based fatty acid-based and glycerin mono-fatty acid ester-based ester-based compounds. These compounds can be used alone or in combination of two or more. The fatty acid used in these lubricity improvers is mainly composed of a mixture of unsaturated fatty acids having about 12 to 22 carbon atoms, preferably about 18 carbon atoms, that is, oleic acid, linoleic acid, linolenic acid, and the like. Is preferred. The lubricity improver may be added so that the wear trace of WS1.4 value in HFRR (High Frequency Reciprocating Rig) of the light oil fuel composition after addition of the lubricity improver is 500 μm or less, preferably 460 μm or less. The concentration is usually 50 to 1000 ppm. Here, WS1.4 value in HFRR means a value obtained by Petroleum Institute Standard JPI-5S-50-98 “Light Oil-Lubricity Test Method”.

  The light oil fuel composition according to the present invention has a distillation 10% distillation temperature of 250 ° C. or lower and a distillation 50% distillation temperature of 300 ° C. or lower, and a chemical shift of 1.00 to 1 in the proton nuclear magnetic resonance spectrum. The ratio of the peak total area of the peak group at a chemical shift of 1.45 to 2.25 ppm relative to the total peak area of the peak group at .45 ppm is preferably 2.5 or more, and the distillation 10% distillation temperature is More preferably, it is 200 ° C. or lower and the distillation 50% distillation temperature is 250 ° C. or lower.

Further, in the light oil fuel composition according to the present invention, the value Z represented by the following formula (1) is preferably larger than −3.5, and more preferably larger than −1.5.

  According to the present invention, the ratio of the paraffin content having 15 or less carbon atoms is 28% by volume or more, and the ratio of the normal paraffin having 18 or more carbon atoms is 11% by volume or less, so that it is substantially composed of only paraffin. However, a light oil fuel composition having improved rubber swellability can be obtained. Conventionally, paraffin was considered to have a property of inferior rubber swellability. According to experiments by the present inventors, the property of inferior rubber swellability is a characteristic of normal paraffin, and isoparaffin has rather rubber swellability. It was found that the tendency to be high and the tendency to swell isoparaffin rubber differed in carbon number. The present invention is based on this new finding by the present inventor.

  Further, according to the experiments by the present inventors, it has been found that the rubber swellability of the light oil fuel composition substantially composed only of paraffin is influenced by the ratio of isoparaffin and the distillation properties. In the proton nuclear magnetic resonance spectrum showing the hydrogen atom isotope species in paraffin, the peak at a chemical shift of 1.45 to 2.25 ppm relative to the total peak area of the peak group at a chemical shift of 1.00 to 1.45 ppm If the ratio of the total peak area of the group and the distillation properties (10%, 50%, 90%, each distillation temperature) are within a predetermined range, the rubber swellability of the light oil fuel composition substantially composed only of paraffin is increased. Further, the rubber swellability of the light oil fuel composition that is substantially composed only of paraffin is a value obtained by a predetermined formula using the ratio of the total peak area and the distillation property as variables. The fact that becomes an index was found. The present invention is also based on these new findings.

  Prior to the description of the examples of the light oil fuel composition according to the present invention, first, the results of an experiment (hereinafter referred to as a confirmation experiment) showing the fact that isoparaffin has a high rubber swellability will be described.

In this confirmation experiment, three types of isoparaffin solvents A, B, and C having different distillation ranges shown in Table 1 and two types of normal paraffin solvents D and E having different distillation ranges were used for comparison.

The properties shown in Table 1 are based on the following measurement method.
<Density (@ 15 ℃)>
It is a density at 15 ° C. measured by JIS K 2249 “Crude oil and petroleum products—density test method and density / mass / volume conversion table”.
<Distillation properties>
Distillation properties obtained by JIS K 2254 "Petroleum products-Distillation test method".
<Content of normal paraffin and isoparaffin>
Using a gas chromatographic method in accordance with ASTM D 2887 “Standard Test Method for Boiling Range Distribution of Petroleum Fraction by Gas Chromatography”, the carbon content obtained from each carbon content was determined from the carbon content obtained by carbon chromatography. That is, the retention time was examined using a mixture of normal paraffins having different carbon numbers as a standard, and the content of normal paraffins was determined from the peak area value of normal paraffins. The sum of the chromatogram area values of the peaks between the normal paraffin peaks was determined as the content of isoparaffin having N carbon atoms. Since the gas chromatography detector is a flame ionization detector (FID), the measurement sensitivity is proportional to the carbon number of paraffin. Therefore, taking this sensitivity into consideration, the content molar ratio was determined from the area value, and finally each mass ratio was determined.
The type of column in the gas chromatograph method is HP5 (length: 30 m, inner diameter: 0.32 mm, liquid layer thickness: 0.25 μm), and each analysis condition is as follows.
Column tank temperature rising condition: 35 ° C. (5 minutes) → 10 ° C./minute (temperature rising) → 320 ° C. (11.5 minutes)
Sample vaporization chamber condition: constant 320 ° C. split ratio 150: 1
Detector section: 320 ° C

この実験結果を表３に示す。

And the test piece of hydrogenated nitrile butadiene rubber (HNBR) was immersed in these solvents A to E, and the volume change rate was measured. The immersion conditions are as shown in Table 2. This condition setting is based on the material compatibility evaluation test of synthetic light oil in the “Research and development of high-efficiency clean energy vehicles” conducted by the Japan Automobile Research Institute, commissioned by the New Energy and Industrial Technology Development Organization. New Energy and Industrial Technology Development Organization: 1999 R & D report on high-efficiency clean energy vehicles, Japan Automobile Research Institute (March 2000)).

The experimental results are shown in Table 3.

  As shown in Table 3, the test pieces immersed in solvent D and solvent E composed of normal paraffin had a reduced volume, whereas they were immersed in solvent A and solvent B composed of isoparaffin. The specimen is increasing in volume. In addition, although the test piece immersed in the solvent C comprised with the same isoparaffin has the volume reduced slightly, the amount of change is very small, and it can be said that it does not show a contraction tendency rather. From this result, it was confirmed that the property of poor rubber swellability is a characteristic of normal paraffin, and that isoparaffin tends to have high rubber swellability. In addition, these solvents were composed of the same isoparaffin or normal paraffin, but the results were different, so it was also confirmed that the influence on the rubber material was different depending on the carbon number. That is, it has been found that the normal paraffin and isoparaffin have better rubber swellability as the molecular weight is lower.

  Next, a light oil fuel composition comprising a mixed oil of normal paraffin and isoparaffin produced by a SMDS (Shell Middle Distillate Synthesis) process, and an adjusted mixed oil whose distillation properties and composition are adjusted using an isoparaffin solvent and a normal paraffin solvent. Got. Properties and composition of the obtained light oil fuel composition are shown in Tables 4-6. The SMDS process means partial oxidation of natural gas, synthesis of heavy paraffin by Fischer-Tropsch synthesis, and hydrocracking and distillation of the resulting heavy paraffin oil to obtain naphtha, kerosene, and light oil fractions. Is a process. Table 4 also shows the properties of FT gas oil already commercialized overseas as a reference example. However, the present invention is not limited to these examples.

In addition, among the properties shown in Tables 4 to 6, the density and distillation properties are the same as those in Table 1, but other properties are based on the following measurement methods.
<Cetane index>
It means a cetane index measured according to JIS K 2280 “Petroleum products—fuel oil—octane number and cetane number test method and cetane index calculation method 8. Method for calculating cetane index using 4-variable equation”. However, FT gas oil is outside the recommended application range for cetane index calculation, so it is shown as a reference value.
<Sulfur content>
Sulfur content obtained by JIS K 2541-2 "Crude oil and petroleum products-Sulfur content test method Part 2: Micro coulometric titration method".
<Paraffin content>
Paraffin content measured by JPI-5S-49-97 "Petroleum products-Hydrocarbon type test method-High performance liquid chromatograph method".
<Aromatic content>
Sum of 1-ring aromatics, 2-rings aromatics and 3 or more-rings aromatic hydrocarbons measured by JPI-5S-49-97 "Petroleum products-Hydrocarbon type test method-High performance liquid chromatograph method" .
<Peak total area ratio>
Proton nuclear magnetic resonance ( ¹ H-NMR) spectrum analysis is performed, and the obtained spectrum has a chemical shift of 1.45 to 2.25 ppm relative to the peak total area of the peak group at a chemical shift of 1.00 to 1.45 ppm. Percentage of the total peak area of the peak group at.

Next, the influence of these light oil fuel compositions on the rubber material was examined under the same conditions as in the above confirmation experiment. Table 7 shows the difference (Δvolume change rate) between the volume change rate after the immersion test of the rubber material in each light oil fuel composition and the volume change rate of the reference example together with the value Z obtained by the above equation (1). And in Table 8.

  As shown in Table 7 and Table 8, in Examples 1 to 12, the volume change rate is increased as compared with the reference example which is a conventional FT light oil. Therefore, from Tables 4 to 6 and these results, the ratio of the paraffin content having 15 or less carbon atoms is 28% by volume or more, and the ratio of the normal paraffin having 18 or more carbon atoms is 11% by volume or less. In particular, it was confirmed that even a light oil fuel composition composed only of paraffin can improve rubber swellability. In addition, although the ratio of the peak total area of Example 2, Example 3, and Example 12 is lower than a comparative example or a reference example, carbon number 15 or less paraffin content, carbon number 18 or more normal paraffin Since the content satisfies the conditions of the present invention, the volume change rate is higher than that of the comparative example or the reference example. That is, from the viewpoint of increasing the volume change rate, it is preferable that the ratio of isoparaffin is high as described above, but the ratio of the total peak area in the proton nuclear magnetic resonance spectrum of paraffin is lower than that of the comparative example or the reference example. However, if the ratio of the paraffin content having 15 or less carbon atoms and the ratio of the normal paraffin having 18 or more carbon atoms satisfy the conditions of the present invention, it was confirmed that the volume change rate was increased.

  In addition, it was confirmed that Examples 2 to 5 having a distillation 10% distillation temperature of 200 ° C. or less and a distillation 50% distillation temperature of 250 ° C. or less have a large increase in volume change rate and are more preferable.

  Furthermore, as shown in Table 9 and Table 10, the relationship between the distillation property and the ratio of the total peak area in the proton nuclear magnetic resonance spectrum satisfies that the Z value obtained by the above formula (1) is larger than −3.5. It can be confirmed that the volume change rate can be improved as compared with the conventional FT light oil.

Claims (5)

  Diesel fuel which is substantially composed only of paraffin and has a paraffin content ratio of 15 or less carbon atoms of 28% by volume or more and a ratio of normal paraffins of 18 or more carbon atoms to 11% by volume or less. Composition.   The chemical with respect to the total peak area of the peak group at a distillation 10% distillation temperature of 250 ° C. or less and a distillation 50% distillation temperature of 300 ° C. or less and a chemical shift of 1.00 to 1.45 ppm in the proton nuclear magnetic resonance spectrum. The light oil fuel composition according to claim 1, wherein the ratio of the total peak area of the peak group at a shift of 1.45 to 2.25 ppm is 2.5 or more.   The light oil fuel composition according to any one of claims 1 and 2, wherein a distillation 10% distillation temperature is 200 ° C or lower and a distillation 50% distillation temperature is 250 ° C or lower. The light oil fuel composition according to any one of claims 1 to 3, wherein a value Z represented by the following formula (1) is greater than -3.5.

The light oil fuel composition according to claim 4, wherein the value Z represented by the formula (1) is greater than -1.5.