JP2012007023A - Light oil composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light oil composition improved in oxidation stability.SOLUTION: The light oil composition comprises 10 mass ppm or lower of sulfur content and 15-35 percents by volume of an aromatic content, based on the total of the composition. The contained amount of monocyclic naphthenobenzenes having the carbon number of 15 or lower is 8.0 percents by ionic strength or lower. Moreover, the ratio of the contained amount (percent by ionic strength) of alkyl benzenes to the contained amount (percent by ionic strength) of the monocyclic naphthenobenzenes having the carbon number of 15 or lower is 1.0 or larger.

Description

  The present invention relates to a light oil composition that ensures oxidation stability by appropriately controlling the composition of hydrocarbons in light oil.

Light oil fuels used in diesel engines are not limited to conventional straight-run middle distillates as the demand for heavy oil fuels has declined in recent years, but also cracking systems obtained from hydrocracking equipment and fluid catalytic cracking equipment. Increase in gas oil base materials, increase in natural gas, asphalt content, coal, etc. as raw materials, increase in synthetic light oil base materials obtained by chemically synthesizing this, and increase in biomass-derived base materials from the viewpoint of reducing CO ₂ emissions It is assumed that it will be diversified.
However, light oil bases other than conventional straight-run middle distillates, especially cracked light oil bases, are obtained by treating straight heavy heavy components in a high-temperature and high-pressure environment. Instable substances are easily generated, and stability is often deteriorated.

On the other hand, diesel engines are environmental pollutants such as PM (particulate matter), NOx (nitrogen oxides), HC (unburned hydrocarbons), and CO (carbon monoxide) as seen in the recent tightening of exhaust gas regulations. There is a need for significant reductions in emissions. About the light oil composition which can reduce PM and NOx, it is disclosed by patent documents 1-7.
In addition, in order to satisfy exhaust gas regulations, the fuel injection pressure of the common rail, which is a fuel injection device for diesel engines, is required to be further increased, which increases the thermal load on the light oil, which increases the stability of the light oil. There is a need for improvement.
However, although a study on substances affecting the oxidative stability of light oil is disclosed in Patent Document 8, as a means for solving the problem of improving the oxidative stability of ordinary light oil, the content of total aromatics is also included. It is insufficient because the rubber swellability cannot be ensured.
Moreover, in order to improve the oxidation stability of light oil, it is necessary to appropriately control the composition of hydrocarbons in light oil, but there is no literature disclosing a method related thereto.

JP 2001-303074 A JP 2001-303075 A JP 2001-303077 A JP 2005-023136 A Japanese Patent Laying-Open No. 2005-023137 JP 2005-023138 A Japanese Patent Laying-Open No. 2005-023139 JP 2009-167257 A

  As a means for improving the oxidation stability of light oil, there is a method of adding an antioxidant, which leads to an increase in production cost. Accordingly, an object of the present invention is to provide a light oil composition that ensures oxidation stability by appropriately controlling the content of hydrocarbons that affect the oxidation stability present in fuel oil.

  In order to solve the above-mentioned problems, the present inventors analyzed the composition of light oil using a gas chromatograph / time-of-flight mass spectrometer (hereinafter abbreviated as “GC-TOFMS”), and the composition was oxidized stable. The effect on the effect was examined. As a result, it has been found that the oxidation stability of light oil is improved by controlling the substances in the specific carbon number range contained in the aromatic content of light oil so as to satisfy a certain range, and the present invention is completed. It came to do.

  That is, according to the present invention, the content of monocyclic naphthenobenzenes having a sulfur content of 10 ppm by mass or less, an aromatic content of 15% by volume to 35% by volume, and a carbon number of 15 or less, based on the total amount of the composition. 8.0 ionic strength% or less and the content of alkylbenzenes (ionic strength%) / the number of monocyclic naphthenobenzenes having 15 or less carbon atoms (ionic strength%) is 1.0 or more. It relates to a light oil composition.

The present invention also relates to the light oil composition as described above, wherein the slow cooling cloud point is 0 ° C. or lower.
Furthermore, the present invention relates to the gas oil composition described above, wherein the peroxide value is 20 mass ppm or less.

  According to the present invention, it is possible to obtain a light oil composition capable of improving oxidation stability by appropriately controlling the composition of hydrocarbons in the light oil composition.

  Hereinafter, the present invention will be described in detail.

  In the light oil composition of the present invention, a monocyclic naphthenobenzene having 15 or less carbon atoms is 8.0 ionic strength% or less, and an alkylbenzene content (ionic strength%) and a single ring having 15 or less carbon atoms. The ratio to the naphthenobenzene content (ionic strength%), that is, the alkylbenzene content (ionic strength%) / the content of monocyclic naphthenobenzenes having 15 or less carbon atoms (ionic strength%) is 1.0 or more. It is characterized by being.

  If the monocyclic naphthenobenzene having 15 or less carbon atoms contained in the light oil composition of the present invention exceeds 8.0 ionic strength%, it is not preferable because the oxidation stability is lowered, and preferably 7.5 ionic strength% or less. 7.0 ionic strength% or less is more preferable.

  Further, the content of alkylbenzenes (ionic strength%) / the content of monocyclic naphthenobenzenes having 15 or less carbon atoms (ionic strength%) needs to be 1.0 or more, preferably 1.5 or more, 2.0 or more is more preferable. When the content of alkylbenzenes (ionic strength%) / the content of monocyclic naphthenobenzenes having 15 or less carbon atoms (ionic strength%) is less than 1.0, the proportion of alkylbenzenes having good oxidation stability decreases. Since the oxidation stability of light oil falls, it is not preferable.

Here, how to obtain the content (ionic strength%) of naphthenobenzenes and alkylbenzenes will be described.
First, the fuel composition is separated into an aromatic component and a saturated component by silica gel chromatography fractionation using diethyl ether and pentane. The weight of the aromatic component at this time is the value of Aroma described later.
Next, the GC-TOFMS method which combined the gas chromatograph and the mass spectrometry by FI ionization method was performed about the aromatic content of the silica gel chromatograph fraction. The analysis conditions are shown below.

(GC condition)
Apparatus: 6890N manufactured by Agilent
Column: Agilent DB-1MS (30 m × 0.25 mmf × 0.25 μm)
Oven temperature: 50 ° C. (5 min) − (5 ° C./min) 280 ° C.
Injection volume: 0.5 μL
Injection method: split (split ratio = 1: 10)
Injection part temperature: 320 ° C
GC interface temperature: 300 ° C
Carrier gas: He 1.2 mL / min (constant)

(MS conditions)
Device: JEOL Ltd. JMS-T100GC
Counter electrode voltage: -10 kV
Ionization method: FI (field ionization)
Ion source temperature: room temperature Mass number measurement range: m / z 35-500

In the mass spectrum obtained as a result of GC-TOFMS analysis, ionic strengths having mass numbers of 1-ring naphthenobenzenes to 6-ring naphthenobenzenes and alkylbenzenes for each carbon number, and The sum of the ionic strengths of the biphenyls and the aromatic masses of two or more rings is the total ionic strength of the aromatics. Note that tricyclic naphthenobenzenes to 6-ring naphthenobenzenes have mass numbers overlapping with biphenyls and aromatics having two or more rings, and thus have an added ionic strength. Obtain the percentage of the ionic strength by type for each carbon number obtained here from the percentage of the total ionic strength, and further correct the sum of the percentages to the value of Aroma. Ask for.
By this method, the content (ionic strength%) of monocyclic naphthenobenzenes having 15 or less carbon atoms (ionic strength%) and alkylbenzenes can be obtained.

  The sulfur content of the gas oil composition of the present invention is required to be 10 mass ppm or less based on the total amount of the composition in order to maintain the purification performance of the exhaust gas aftertreatment device of a diesel vehicle. Preferably it is 5 mass ppm or less, More preferably, it is 3 mass ppm or less, Most preferably, it is 1 mass ppm or less. In addition, content of a sulfur content here means the value measured based on JISK2541 "Crude oil and petroleum products-sulfur content test method."

  The aromatic content in the light oil composition of the present invention requires that the upper limit of the range be 35% by volume or less, preferably 30% by volume or less, more preferably from the viewpoint of suppressing the production of PM and the like. 25% by volume or less. In addition, it is necessary to set the lower limit of the range to 15% by volume or more, preferably 20% by volume or more from the viewpoint of securing the swelling property of the NBR rubber and suppressing fuel leakage from the sealing member at the joint portion such as a pipe. is there. The aromatic content mentioned here is based on the Petroleum Institute Standard JPI-5S-49-97 “Hydrocarbon Type Test Method—High Performance Liquid Chromatograph Method” issued by the Japan Petroleum Institute. It means the volume percentage (volume%) of the aromatic content to be measured.

The induction period of the light oil composition of the present invention is required to be 60 minutes or longer, preferably 65 minutes or longer, and more preferably 70 minutes or longer from the viewpoint of suppressing a decrease in engine output due to the generation of injector deposits.
Here, the method for measuring the induction period referred to in the present invention will be described. The metal container containing the test fuel is sealed, and oxygen is sealed therein to a predetermined pressure. Thereafter, the sealed container is heated to a predetermined temperature, the predetermined pressure is maintained from the maximum pressure point to the point where the pressure drops by 10%, and the time from the start of heating to the 10% pressure drop point is measured, That time is the induction period.

(Measurement condition)
Apparatus: PetroXY apparatus (manufactured by Petrotest)
Oxygen filling pressure: 700 kPa (gauge pressure)
Test temperature: 140 ° C
Test fuel volume: 5mL

  The slow cooling cloud point of the light oil composition of the present invention needs to be 0 ° C. or lower, preferably −2 ° C. or lower, more preferably −5 ° C. or lower, still more preferably −8 ° C. or lower, most preferably − It is 10 degrees C or less. If the slow-cooling cloud point is 0 ° C. or lower, even if wax adheres to the filter of the diesel vehicle fuel injection device, the wax tends to be easily dissolved. The “slow cooling cloud point” in the present invention means a value measured as follows. That is, a sample is put in a sample container whose bottom surface is an aluminum surface so that the thickness is 1.5 mm, and light is irradiated from a height of 3 mm from the bottom surface of the container. In this state, the temperature is gradually cooled at 0.5 ° C./min from a temperature 10 ° C. or more higher than the above cloud point, and the temperature at which the amount of reflected light becomes 7/8 or less of the irradiated light (gradual cooling cloud point) is 0. Detect in 1 ℃ unit.

  The clogging point of the light oil composition of the present invention is preferably 5 ° C. or lower, more preferably 0 ° C. or lower, and −5 ° C. or lower from the viewpoint of preventing filter blockage of a diesel vehicle. More preferably, it is -10 degrees C or less, Most preferably, it is -15 degrees C or less. The clogging point here means a value measured according to JIS K2288 "Petroleum products-light oil-clogging point test method".

  The peroxide value of the light oil composition of the present invention is required to be 20 mass ppm or less from the viewpoint of ensuring oxidation stability, preferably 15 mass ppm or less, more preferably 10 mass ppm or less, and still more preferably. It is 5 mass ppm or less. The peroxide value here means a value measured according to the Petroleum Institute Standard JPI-5S-46-96 “Test Method for Peroxide Value of Kerosene” published by the Japan Petroleum Institute. .

As the base material of the light oil composition of the present invention, a petroleum light oil base material and a petroleum kerosene base material can be used.
Specifically, as the petroleum-based light oil base material, for example, straight-run light oil obtained from a crude oil atmospheric distillation apparatus; straight-run heavy oil or residual oil obtained from an atmospheric distillation apparatus can be obtained by subjecting to a vacuum distillation apparatus Vacuum gas oil; hydrorefined gas oil obtained by hydrorefining straight-run gas oil or vacuum gas oil; hydrodesulfurization of straight-run gas oil or vacuum gas oil in one or more stages under conditions that are more severe than normal hydrorefining Hydrodesulfurized light oil obtained by hydrocracking; hydrocracked light oil obtained by hydrocracking the above various light oil bases.
Further, as the petroleum-based kerosene base, specifically, for example, straight-run kerosene obtained from a crude oil atmospheric distillation apparatus; straight-run heavy oil or residual oil obtained from an atmospheric distillation apparatus is subjected to a vacuum distillation apparatus. Obtained reduced kerosene; hydrorefined kerosene obtained by hydrorefining straight-run kerosene or reduced-pressure kerosene; straight-run kerosene or depressurized kerosene is hydrogenated in one or more stages under conditions severer than ordinary hydrorefining Examples include hydrodesulfurized kerosene obtained by desulfurization; hydrocracked kerosene obtained by hydrocracking the above various kerosene substrates.
In the present invention, a light oil composition satisfying a predetermined performance can be produced by arbitrarily mixing the petroleum-based light oil base and the petroleum-based kerosene base.

  The light oil composition of the present invention may contain a low temperature fluidity improver as necessary. The type of the low-temperature fluidity improver is not particularly limited. For example, ethylene-unsaturated ester copolymer represented by ethylene-vinyl acetate copolymer, alkenyl succinic acid amide, dibehenic acid ester of polyethylene glycol Linear compounds such as phthalic acid, ethylenediaminetetraacetic acid, nitriloacetic acid and the like, or polar nitrogen compounds consisting of reaction products of hydrocarbyl-substituted amines, alkyl fumarate or alkyl itaconate-unsaturated esters One kind or two or more kinds of low-temperature fluidity improvers such as a comb polymer made of a copolymer can be used. Among these, from the viewpoint of versatility, an ethylene-vinyl acetate copolymer additive can be preferably used. When the low temperature fluidity improver is added, the addition amount is preferably 50 to 500 mg / L, and particularly preferably 50 to 300 mg / L. In addition, since a commercial product referred to as a low temperature fluidity improver may be diluted with an appropriate solvent for an active ingredient that contributes to low temperature fluidity, such a commercial product may be used as the fuel oil composition of the present invention. In the case of adding to the above, the above-mentioned addition amount means the addition amount as an active ingredient.

  The light oil composition of the present invention may contain a lubricity improver from the viewpoint of ensuring lubricity in the injection pump. The type of the lubricity improver is not particularly limited, but one or more of the lubricity improvers such as ester, carboxylic acid, alcohol, phenol, and amine can be used. . Among these, from the viewpoint of versatility, it is preferable to use an ester-based or carboxylic acid-based lubricity improver. Furthermore, an ester-based lubricity improver is preferable from the viewpoint that the effect of addition with respect to the concentration of addition hardly reaches saturation and the WS1.4 value of HFRR can be further reduced, and the initial response of the effect of addition with respect to the concentration of addition is high. Carboxylic acid type lubricity improvers are preferred from the viewpoint that the amount of addition of can be reduced.

  Examples of the ester-based lubricity improver include glycerin carboxylic acid ester and the like. The carboxylic acid constituting the carboxylic acid ester may be one type or two or more types, and specific examples thereof include linoleic acid, oleic acid, salicylic acid, palmitic acid, myristic acid, hexadecenoic acid and the like. . Examples of the carboxylic acid-based lubricity improver include linoleic acid, oleic acid, salicylic acid, palmitic acid, myristic acid, hexadecenoic acid, and the like, and one or more of these can be used arbitrarily. is there. In addition, when a low temperature fluidity improver has a lubricity improvement effect, the low temperature fluidity improver and the lubricity improver can be combined to improve lubricity.

  When the lubricity improver is added, the addition amount is preferably 25 to 500 mg / L, more preferably 25 to 300 mg / L or less, and further preferably 25 to 200 mg / L or less. Thus, the WS1.4 value of HFRR is preferably 500 μm or less, more preferably 460 μm or less, still more preferably 420 μm or less, and most preferably 400 μm or less. Commercially available products called lubricity improvers are usually obtained in a state where the active ingredients that contribute to lubricity are diluted with a suitable solvent. In the case where such a commercial product is added to the fuel oil composition of the present invention, the above addition amount means the addition amount as an active ingredient.

  The light oil composition of the present invention can contain an antioxidant. The type of antioxidant is not particularly limited, but phenol-based, amine-based and other antioxidants are preferably used. For example, as a phenolic antioxidant, 4,4′-methylenebis (2,6-di-tert-butylphenol), 4,4′-bis (2,6-di-tert-butylphenol), 4,4 ′ -Bis (2-methyl-6-tert-butylphenol), 2,2'-methylenebis (4-ethyl-6-tert-butylphenol), 2,2'-methylenebis (4-methyl-6-tert-butylphenol), 4,4′-butylidenebis (3-methyl-6-tert-butylphenol), 4,4′-isopropylidenebis (2,6-di-tert-butylphenol), 2,2′-methylenebis (4-methyl-6) -Nonylphenol), 2,2'-isobutylidenebis (4,6-dimethylphenol), 2,2'-methylenebis (4-methyl) 6-cyclohexylphenol), 2,6-di-tert-butyl-4-methylphenol, 2,6-di-tert-butyl-4-ethylphenol, 2,4-dimethyl-6-tert-butylphenol, 2, 6-di-tert-α-dimethylamino-p-cresol, 2,6-di-tert-butyl-4 (N, N′-dimethylaminomethylphenol), 4,4′-thiobis (2-methyl-6) -Tert-butylphenol), 4,4'-thiobis (3-methyl-6-tert-butylphenol), 2,2'-thiobis (4-methyl-6-tert-butylphenol), bis (3-methyl-4- Hydroxy-5-tert-butylbenzyl) sulfide, bis (3,5-di-tert-butyl-4-hydroxybenzyl) sulfide 2,2′-thio-diethylenebis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], tridecyl-3- (3,5-di-tert-butyl-4-hydroxy Phenyl) propionate, pentaerythrityl-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) ) Propionate and the like, and amine-based antioxidants include phenyl-α-naphthylamine, alkylphenyl-α-naphthylamine, dialkyldiphenylamine and the like. The addition amount in the case of adding an antioxidant is preferably 1 to 500 mg / L, and particularly preferably 5 to 300 mg / L. Commercially available products referred to as antioxidants are usually obtained in a state where the active ingredients that contribute to the improvement of oxidation stability are diluted with a suitable solvent. In the case where such a commercial product is added to the fuel oil composition of the present invention, the above addition amount means the addition amount as an active ingredient.

  The light oil composition of the present invention can be appropriately blended with any additive other than the low temperature fluidity improver, the lubricity improver and the antioxidant. These additives include cetane improvers such as nitrate esters and organic peroxides typified by 2-ethylhexyl nitrate, alkenyl succinic acid derivatives, detergents such as amine salts of carboxylic acids, salicylidene derivatives, etc. Metal deactivators, anti-freezing 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, azo dyes, etc. And antifoaming agents such as silicon-based colorants. These additives can be added alone or in combination of several kinds. The addition amount is arbitrary, but the other additive total amount is an addition amount as an active ingredient, and is usually 0.5% by mass or less, preferably 0.2% by mass or less, based on the total amount of the fuel oil composition.

The kinematic viscosity at 30 ° C. of the light oil composition of the present invention is not particularly limited, but is preferably 1.7 to 6.0 mm ² / s. When the kinematic viscosity at 30 ° C. is less than 1.7 mm ² / s, there is a possibility of starting failure or unstable engine rotation during idling when used at a relatively high temperature. In addition, there may be a problem in the durability of the fuel injection pump. The kinematic viscosity at 30 ° C. is more preferably 2.7 mm ² / s or more, more preferably 3.0 mm ² / s or more from the viewpoint of ensuring startability at high temperatures, stability of engine rotation during idling, and ensuring durability of the fuel injection pump. Is more preferable. Moreover, since kinematic smoke will increase when dynamic viscosity in 30 degreeC becomes larger than 6.0 mm < ² > / s, it is not preferable. From the viewpoint of preventing increase in black smoke, the kinematic viscosity at 30 ° C. is more preferably 5.5 mm ² / s or less, further preferably 5.0 mm ² / s or less, and 4.5 mm ² / s or less. Most preferably it is. Here, the kinematic viscosity at 30 ° C. means a value measured by JIS K2283 “Crude oil and petroleum products—Kinematic viscosity test method and viscosity index calculation method”.

The density at 15 ° C. of the light oil composition of the present invention is not particularly limited, but is preferably 0.855 g / cm ³ or less from the viewpoint of preventing an increase in PM discharged from the engine, and 0.850 g / more preferably cm ³ or less, still more preferably 0.845 g / cm ³ or less, particularly preferably at 0.840 g / cm ³ or less, that is 0.838 g / cm ³ or less and most preferable. On the other hand, from the viewpoints of fuel consumption rate, engine output, startability at high temperature, and stability of engine rotation at idling, the density at 15 ° C. is preferably 0.810 g / cm ³ or more, and 0.815 g / cm more preferably cm ³ or more, further more preferably 0.820 g / cm ³ or more, and most preferably 0.822 g / cm ³ or more. The density at 15 ° C. here means a value measured according to JIS K 2249 “Crude oil and petroleum products—density test method and density / mass / capacity conversion table”.

The cetane index of the light oil composition of the present invention is not particularly limited, but is preferably 45.0 or more, more preferably 50.0 or more from the viewpoint of engine ignitability, and 52.0. More preferably, it is more preferably 55.0 or more.
The cetane number of the light oil composition of the present invention is not particularly limited, but is preferably 45.0 or more, more preferably 50.0 or more from the viewpoint of engine ignitability, and 52 Is more preferably 0.0 or more, and most preferably 55.0 or more. In particular, when the cetane index of the light oil composition is less than 45.0, particularly when the cetane index is less than 43.0, it is preferable to add a cetane number improver to make the cetane number 45.0 or more. . Even when the cetane index is 45.0 or more, by adding a cetane number improver, engine ignitability can be further improved, engine startability at low temperatures can be improved, and white smoke at start-up can be reduced. Can do. A cetane number and a cetane index here mean values measured and calculated according to JIS K 2280 “Petroleum products-fuel oil-octane number and cetane number test method and cetane index calculation method”.

  The flash point of the light oil composition of the present invention is preferably 50 ° C. or higher, and more preferably 60 ° C. or higher, from the viewpoint of ensuring safety during handling. The flash point here means a value measured according to JIS K 2265 “How to determine the flash point”.

  Regarding the lubricity of the light oil composition of the present invention, the WS1.4 value of HFRR is preferably 500 μm or less, more preferably 460 μm or less, still more preferably 420 μm or less, and particularly preferably 400 μm or less. When the WS1.4 value satisfies the above conditions, the lubricity in the injection pump in the diesel vehicle can be sufficiently ensured. The WS1.4 value of HFRR here is an indicator for determining the lubricity of light oil, and is the Petroleum Institute Standard JPI-5S-50-98 “Light Oil-Lubricity Test Method” issued by the Japan Petroleum Institute. Means a value measured according to

The distillation properties of the light oil composition of the present invention are not particularly limited, but desirably satisfy the following properties.
Initial boiling point (IBP): 150-185 ° C
10 vol% distillation temperature: 180-220 ° C
30% by volume distillation temperature: 220-260 ° C
50 volume% distillation temperature: 250-285 degreeC
70 vol% distillation temperature: 280-305 ° C
90 vol% distillation temperature: 300-340 ° C
End point (EP): 325-365 ° C

The distillation property of the light oil composition of the present invention will be further described in detail.
Regarding the distillation properties of the light oil composition of the present invention, the initial boiling point (hereinafter abbreviated as IBP) is preferably 150 ° C. or higher, more preferably 155 ° C. or higher, still more preferably 160 ° C. or higher, particularly preferably 165 ° C. Further, it is preferably 185 ° C. or less, more preferably 180 ° C. or less, further preferably 175 ° C. or less, and particularly preferably 170 ° C. or less. If the IBP is less than the lower limit, a part of the light fraction is vaporized, and the amount of unburned hydrocarbons in the exhaust gas increases with a wide spray range in the engine of the diesel vehicle. As a result, the startability at high temperatures and the rotational stability of the engine at idling tend to decrease. On the other hand, when IBP exceeds the upper limit value, the startability and drivability at low temperatures in a diesel vehicle tend to be reduced.

  The 10% by volume distillation temperature (hereinafter abbreviated as T10) of the light oil composition of the present invention is preferably 180 ° C. or higher, more preferably 185 ° C. or higher, further preferably 190 ° C. or higher, particularly preferably 195 ° C. or higher. And preferably 220 ° C. or lower, more preferably 215 ° C. or lower, still more preferably 210 ° C. or lower, and particularly preferably 205 ° C. or lower. When T10 is less than the lower limit, a part of the light fraction is vaporized, and the amount of unburned hydrocarbons in the exhaust gas increases as the spray range becomes wide in the engine of the diesel vehicle. As a result, the startability at high temperatures and the rotational stability of the engine at idling tend to decrease. On the other hand, when T10 exceeds the upper limit, the startability and drivability at low temperatures in a diesel vehicle tend to be reduced.

  The 30 vol% distillation temperature (hereinafter abbreviated as T30) of the light oil composition of the present invention is preferably 220 ° C or higher, more preferably 225 ° C or higher, further preferably 230 ° C or higher, particularly preferably 235 ° C or higher. Moreover, it is preferably 260 ° C. or lower, more preferably 255 ° C. or lower, and further preferably 250 ° C. or lower. When T30 is less than the lower limit, a part of the light fraction is vaporized, and the amount of unburned hydrocarbons in the exhaust gas increases as the spray range becomes wide in the engine of the diesel vehicle. As a result, the startability at high temperatures and the rotational stability of the engine at idling tend to decrease. On the other hand, when T30 exceeds the upper limit, the startability and drivability at low temperatures in a diesel vehicle tend to be reduced.

  The 50 vol% distillation temperature (hereinafter abbreviated as T50) of the light oil composition of the present invention is preferably 250 ° C or higher, more preferably 255 ° C or higher, still more preferably 260 ° C or higher, particularly preferably 265 ° C or higher. And preferably 285 ° C. or lower, more preferably 280 ° C. or lower, still more preferably 275 ° C. or lower, particularly preferably 270 ° C. or lower. When T50 is less than the lower limit value, the fuel consumption rate, engine output, startability at high temperatures, and engine rotation stability at idling tend to decrease in a diesel vehicle. On the other hand, when T50 exceeds the upper limit, particulate matter (hereinafter referred to as PM) discharged from the engine in a diesel vehicle tends to increase.

  The 70 vol% distillation temperature (hereinafter abbreviated as T70) of the light oil composition of the present invention is preferably 280 ° C or higher, more preferably 285 ° C or higher, still more preferably 290 ° C or higher, and preferably 305. ° C or lower, more preferably 300 ° C or lower, still more preferably 295 ° C or lower. If T70 is less than the lower limit value, the fuel consumption rate, engine output, startability at high temperatures, and stability of engine rotation at idling tend to decrease in a diesel vehicle. On the other hand, when T70 exceeds the upper limit, PM discharged from the engine in a diesel vehicle tends to increase.

  The 90% by volume distillation temperature (hereinafter abbreviated as T90) of the light oil composition of the present invention is preferably 300 ° C. or higher, more preferably 305 ° C. or higher, still more preferably 310 ° C. or higher, particularly preferably 315 ° C. Further, it is preferably 340 ° C. or lower, more preferably 335 ° C. or lower, further preferably 330 ° C. or lower, and particularly preferably 325 ° C. or lower. If T90 is less than the lower limit, the fuel consumption rate, startability at high temperatures, and stability of engine rotation at idling tend to decrease in a diesel vehicle. Moreover, when the light oil composition contains a low temperature fluidity improver, the improvement effect such as a clogging point due to the low temperature fluidity improver tends to be lowered. On the other hand, when T90 exceeds the upper limit, PM discharged from the engine in a diesel vehicle tends to increase.

  The end point (hereinafter abbreviated as EP) of the light oil composition of the present invention is preferably 325 ° C. or higher, more preferably 330 ° C. or higher, still more preferably 335 ° C. or higher, particularly preferably 340 ° C. or higher. The temperature is preferably 365 ° C. or less, more preferably 360 ° C. or less, still more preferably 355 ° C. or less, and particularly preferably 350 ° C. or less. If EP is less than the lower limit value, the fuel consumption rate in diesel vehicles, startability at high temperatures, and stability of engine rotation at idling tend to decrease. Moreover, when the light oil composition contains a low temperature fluidity improver, the improvement effect such as a clogging point due to the low temperature fluidity improver tends to be lowered. On the other hand, when EP exceeds the upper limit, PM discharged from the engine in a diesel vehicle tends to increase.

  Here, IBP, T10, T30, T50, T70, T90 and EP mean values measured in accordance with JIS K 2254 “Petroleum products—Distillation test method—Atmospheric pressure method”, respectively.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example at all.

[Examples 1-5, Comparative Examples 1-2]
In Examples 1 to 5 and Comparative Examples 1 and 2, light oil compositions having the compositions and properties shown in Table 2 were prepared. In addition, the sample of the light oil composition of Examples 1-5 and Comparative Examples 1-2 was prepared using the light oil base materials A, B, C, D, E, and F of Table 1.
That is, these gas oil compositions are prepared by using a gas oil base material A obtained by hydrodesulfurizing a straight-run middle distillate, a middle portion of a cracked middle distillate obtained from a fluid catalytic cracking apparatus, and the like. Gas oil base material B obtained by mixing the fractions with hydrodesulfurization equipment and light oil base materials C, D, E, and straight oil obtained by hydrocracking heavy fractions obtained by distillation under reduced pressure A kerosene base F obtained by hydrodesulfurizing a distillate kerosene fraction was blended and prepared.

The engine output reduction rate and the volume change rate of the NBR rubber listed in Table 2 were determined by the following measurement methods.
(1) Engine output reduction rate: Compliant with CEC F-98-08 "Direct Injection, Common Rail Diesel Engine Nozzle Coking Test."
(2) Volume change rate of NBR rubber: Conforms to JIS K 6258 "Vulcanized rubber and thermoplastic rubber-Determination of liquid resistance"

  From Table 2, it can be seen that Examples 1 to 5 are superior in oxidation stability because the values of the peroxide value and the engine output decrease rate are smaller than those of Comparative Example 1 and the induction period is long. In addition, it can be seen that Examples 1 to 5 have a higher total aromatic content than Comparative Example 2, have a large volume change rate of NBR rubber, and have less adverse effects on the members.

  According to the present invention, by appropriately controlling the composition of hydrocarbons in light oil, it is possible to obtain a light oil composition ensuring oxidative stability, which is extremely useful industrially.

Claims (3)

  Based on the total amount of the composition, the sulfur content is 10 mass ppm or less, the aromatic content is 15 volume% or more and 35 volume% or less, and the content of monocyclic naphthenobenzenes having 15 or less carbon atoms is 8.0 ionic strength%. A gas oil composition having an alkylbenzene content (ionic strength%) / monocyclic naphthenobenzene content (ionic strength%) having 15 or less carbon atoms of 1.0 or more.   The light oil composition according to claim 1, wherein the slow cooling cloud point is 0 ° C. or lower.   The light oil composition according to claim 1 or 2, wherein the peroxide value is 20 mass ppm or less.