JP2012197355A - Gas oil composition and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas oil composition that excellently maintains oxidation stability without excessively adding an additive for antioxidation and in which the sulfur content is at most 10 mass ppm.SOLUTION: The gas oil composition is characterized as follows. The density is 0.810-0.825 g/cmat 15°C, based on the total amount of the composition, the total sulfur content is at most 10 mass ppm, the one ring naphteno benzenes content (ionic strength%) is 4.0-8.0, the two ring naphteno benzenes content (ionic strength%) is at most 4.0, the isoparaffins content (ionic strength%) is 30.1-80.0, the naphthalenes content (ionic strength%) is 0.1-1.5, and the induction period is 68-100 minutes.

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 light oil base materials, increase in natural gas, asphalt, coal, etc. as raw materials, increase in synthetic light oil base materials obtained by chemical synthesis, increase in biomass-derived base materials from the viewpoint of reducing CO2 emissions, etc. It is expected to diversify.
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 becoming more demanding to improve the oxidation stability of diesel oil than ever before due to the increased pressure of fuel injection by the common rail due to stricter exhaust gas regulations, increasing the thermal load on diesel oil. Thus, in order to improve the oxidation stability of light oil, for example, it is conceivable to add an antioxidant additive, and it is proposed to add an antioxidant to light oil whose sulfur content is reduced to 10 mass ppm or less. (See Patent Document 1). A method of adding kerosene to which an antioxidant is added to light oil is also conceivable. However, the method of adding an antioxidant additive varies the additive effect of the additive due to the change in the composition of the light oil at the time of manufacture. . Moreover, when an additive is added excessively, it will become easy to precipitate an additive by temperature fall. In addition, if the additive amount is too small, after the antioxidant effect of the additive is exhausted during oxidation, the oxidation stability of the light oil will be significantly deteriorated, causing adverse effects such as engine cleanliness and corrosion of metal materials. . In addition, it has been proposed to maintain oxidation stability without adding an antioxidant additive by setting the content of aromatic components and naphthene components in light oil within a specific range (see Patent Document 2). Although the method for preparing this diesel oil composition is effective, the invention described in Patent Document 2 focuses on fluorenes and naphthenobenzenes as substances having poor oxidative stability, and these contents and oxidative stability are good. Balances with the content of naphthalene, a substance. However, when a cracked light oil base is treated in a high-temperature and high-pressure environment, naphthenobenzenes having poor oxidation stability are likely to be produced in the produced oil. In the invention described in Patent Document 2, naphthenobenzenes are highly concentrated. No mention is made of a method for preparing a light oil composition when present in

JP 2004-225000 A JP 2006-137922 A

"Peroxide Formation in Low Sulfur Automotive Diesel Fuels", SAE920826

  The present invention solves the above-mentioned problems, and by making substances that significantly affect oxidation stability into a specific range, the oxidation stability is improved without excessive addition of antioxidant additives. It is an object to provide a gas oil composition having a sulfur content of 10 mass ppm or less.

  As a result of diligent research, the present inventor has obtained a relatively low concentration of a light oil base material and naphthenobenzenes having poor oxidation stability in a specific property range, such as a high concentration of naphthenobenzenes, and Mixing with a light oil base containing a lot of isoparaffins and good oxidation stability, and limiting the content of monocyclic and bicyclic naphthenobenzenes, isoparaffins, and naphthalenes within the specified ratio range Thus, it was found that there is a significant improvement in oxidation stability. In addition, the present inventors have found that the oxidation stability can be improved without mixing many light oil bases having good oxidation stability and without adding an excessive amount of an antioxidant due to the effect of improving oxidation stability. did.

That is, according to the present invention, the density at 15 ° C. is 0.810 to 0.825 g / cm ³ , and the total sulfur content is 10 mass ppm or less based on the total amount of the composition, the content of monocyclic naphthenobenzenes (ionic strength%) ) Is 4.0 to 8.0, bicyclic naphthenobenzene content (ionic strength%) is 4.0 or less, isoparaffin content (ionic strength%) is 30.1 to 80.0, naphthalene content It is a light oil composition having an amount (ionic strength%) of 0.1 to 0.5 and an induction period of 68 to 100 minutes.

Moreover, this invention is the light oil composition of the said description whose following formula S2 calculated by isoparaffin content (ionic strength%) and bicyclic cycloparaffin content (ionic strength%) is 80 or more.
S2 = 100 × C / (C + D)
(C: Isoparaffin content (ionic strength%), D: Bicyclic cycloparaffin content (ionic strength%))

  In the present invention, a light oil base material 1 having an induction period of 30 minutes or more and less than 68 minutes is mixed with a light oil base material 2 having an induction period of 80 minutes or more and less than 120 minutes in an amount of 5% by volume or more. It is a manufacturing method of the light oil composition which manufactures the light oil composition of the said description.

  The light oil composition of the present invention has an oxidation stability in order to improve the oxidation stability more than the simple synthesis calculation of the oxidation stability of the light oil base material by the mixing volume ratio by setting the light oil properties within a specific range. The production restriction by mixing many high light oil bases, the production cost associated therewith, and the extra effect of reducing the addition cost of the antioxidant can be achieved. In addition, since the total sulfur content is 10 ppm by mass or less, the bad odor and environmental load based on sulfurous acid gas generated by combustion is reduced, and oxidation polymerization due to thermal load received by high pressure injection in storage or diesel engine As a result, there is no need to add excessive additives used for these improvements.

The light oil composition according to the present invention has a density at 15 ° C. of 0.810 g / cm ³ or more, preferably 0.811 g / cm ³ or more, more preferably 0.814 g / cm ³ or more, particularly preferably from the viewpoint of reducing fuel consumption. 0.816 g / cm ³ or more. Further, 0.825 g / cm ³ in terms of exhaust emissions of soot and nitrogen oxides or less, preferably 0.823 g / cm ³ or less, particularly preferably 0.820 g / cm ³ or less. The total sulfur content is 10 mass ppm or less, preferably 5 mass ppm or less, from the viewpoint of reducing fuel consumption. Further, in order to enhance the effect of improving oxidation stability, the content of monocyclic naphthenobenzenes (ionic strength%) is 4.0 or more, preferably 5.0 or more, more preferably 6.0 or more, particularly preferably 7. 0 or more. In addition, if the content of unicyclic naphthenobenzenes (ionic strength%) is too large, the effect of improving oxidation stability is reduced, and the effect of addition of antioxidants is reduced. The ionic strength%) is 8.0 or less, preferably 7.8 or less, more preferably 7.7 or less, and particularly preferably 7.6 or less. If the bicyclic naphthenobenzene content (ionic strength%) is too large, the effect of improving the oxidative stability is reduced, so 4.0 or less, preferably 3.0 or less, more preferably 2.6 or less, particularly preferably. 2.3 or less. Further, since the effect of improving the oxidative stability is reduced when the isoparaffin content (ionic strength%) is small, the isoparaffin content (ionic strength%) is 30.1 or more, preferably 40.0 or more, more preferably 50.0 or more, particularly preferably 60.0 or more. Further, if the content of isoparaffins (ionic strength%) is large, the cetane number decreases and the ignitability tends to deteriorate, so that it is 80.0 or less, preferably 77.0 or less, more preferably 76.0 or less, especially Preferably it is 75.0 or less. When the naphthalene content (ionic strength%) is small, the effect of improving the oxidative stability becomes small, so 0.1 or more, preferably 0.2 or more, more preferably 0.3 or more, particularly preferably 0.4. That's it. If the content of naphthalenes (ionic strength%) is large, the ignitability deteriorates and soot is easily generated during combustion.

  In addition, if the induction period is short, the fuel injection nozzle of the engine is likely to be clogged, the output is reduced, and the metal material such as the fuel tank is corroded. Therefore, the induction period is 68 minutes or more, preferably 70 minutes or more. More preferably, it is 73 minutes or more, Most preferably, it is 75 minutes or more. In addition, if the induction period is long, many light oil bases having good oxidation stability are used, and the production cost increases due to an increase in the amount of the antioxidant added. Min or less, more preferably 90 min or less, and particularly preferably 85 min or less.

The following formula S2 calculated from the isoparaffin content (ionic strength%) and the bicyclic cycloparaffin content (ionic strength%) is preferably 80 or more, more preferably 82 or more, and still more preferably 85. Above, particularly preferably 86 or more. If S2 is less than 80, the oxidation stability improving effect is reduced, which is not preferable.
S2 = 100 × C / (C + D)
(C: Isoparaffin content (ionic strength%), D: Bicyclic cycloparaffin content (ionic strength%))

  In this diesel oil composition, the diesel oil base material 1 having an induction period of 30 minutes or more and less than 68 minutes is added to the diesel oil base substance 2 having an induction period of 80 minutes or more and less than 120 minutes so that the total volume of the diesel oil base is 5% by volume or more. It can be mixed and manufactured.

The induction period of the light oil base 1 is 30 minutes or more, preferably 33 minutes or more, more preferably 50 minutes or more, and particularly preferably 60 minutes or more. If the induction period of the light oil base material 1 is shorter than 30 minutes, the effect of improving the oxidation stability by the light oil base material 2 becomes small, which is not preferable. On the other hand, the induction period of the light oil base 1 is less than 68 minutes, preferably 66 minutes or less. When the induction period of the light oil base material 1 is longer than 68 minutes, the effect of improving the oxidation stability of the light oil base material 2 is reduced, which is not preferable.
Moreover, the induction period of the light oil base material 2 is 80 minutes or more, Preferably it is 83 minutes or more, More preferably, it is 85 minutes or more. If the induction period of the light oil base material 2 is shorter than 80 minutes, the oxidation stability improving effect is reduced, which is not preferable. On the other hand, the induction period of the light oil base 2 is less than 120 minutes, preferably 118 minutes or less, more preferably 115 minutes or less, and particularly preferably 110 minutes or less. When the induction period of the light oil base material 2 is longer than 120 minutes, the light oil base material 2 contains light oil oil in order to reduce components such as monocyclic naphthenobenzenes and bicyclic naphthenobenzenes that are not oxidatively stable. Since the purification cost of the base material 2 increases, it is not preferable.

  The ratio of the light oil base material 2 to be mixed with the light oil base material 1 is 5% by volume or more, preferably 10% by volume or more, and preferably 70% by volume or less. When the ratio of the light oil base material 2 is less than 5% by volume, the effect of improving the oxidation stability is reduced, which is not preferable.

  In the present invention, a monocyclic naphthenobenzene content (ionic strength%), a bicyclic naphthenobenzene content (ionic strength%), an isoparaffin content (ionic strength%), and a naphthalene content in the gas oil composition A gas oil composition having excellent oxidation stability is provided by adjusting the amount (ionic strength%) within a specific range. The effect of improving the oxidation stability by controlling such a composition will be described below.

  Tetralin, which is a compound representing 1-ring naphthenobenzenes, and normal-decylcyclohexane, which represents 1-ring cycloparaffins, heptamethylnonane, which represents tetralin and isoparaffins, and heptamethylnonane and 2-ring cycloparaffins Table 1, Table 2, and Table 3 show the differences between the induction periods, the induction periods of these mixed products, and the induction periods obtained by simple synthesis calculation. All of these compounds are reagents having a purity of 96% or more. From now on, by making the ratio of tetralin and normal decylcyclohexane, tetralin and heptamethylnonane, heptamethylnonane and decalin within a specific range, the difference from the induction period by simple synthesis calculation will be increased respectively, and further the induction period of a single unit It can be seen that the induction period of the mixed product can be made longer than that, and the effect of improving the oxidation stability is observed.

  Here, monocyclic naphthenobenzene content (ionic strength%), bicyclic naphthenobenzene content (ionic strength%), monocyclic cycloparaffins content (ionic strength%), bicyclic cycloparaffins contained The method for obtaining the amount (ionic strength%) and the naphthalene content (ionic strength%) 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 Aroma value described later, and the weight of the saturated component is the Saturate value 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 and saturated content of the silica gel chromatographic 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. Tricyclic naphthenobenzenes are regarded as naphthalenes, and 4-ring naphthenobenzenes are regarded as biphenyls. In addition, 5-ring naphthenobenzenes to 6-ring naphthenobenzenes have ionic strengths that are respectively added because there are those whose mass numbers overlap with those of two or more ring aromatics. 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, monocyclic naphthenobenzene content (ionic strength%), bicyclic naphthenobenzene content (ionic strength%), biphenyl content (ionic strength%) and naphthalene content (ionic strength%) ).
In addition, in the mass spectrum obtained as a result of GC-TOFMS analysis, the sum of the ionic strengths having the mass numbers of normal paraffins, isoparaffins and 1-cyclocycloparaffins to 6-cyclocycloparaffins for each carbon number is saturated. The total ionic strength of the minute.

  Obtain the ratio from the percentage of the total ionic strength of each type of ionic strength obtained for each carbon number, and further correct the sum of the percentages to the Saturate value. Ask for. By this method, normal paraffins (ionic strength%), isoparaffins (ionic strength%), and 1-ring cycloparaffins to 6-ring cycloparaffins (ionic strength%) can be obtained.

  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

  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 severer than ordinary hydrorefining Hydrodesulfurized diesel oil obtained; hydrocracked diesel oil obtained by hydrodesulfurization after mixing catalytic cracked diesel oil obtained from a fluid catalytic cracker alone or with straight run diesel oil; hydrocracking the above various diesel oil bases And hydrocracked diesel oil obtained in this way.

  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 vacuum kerosene; hydrorefined kerosene obtained by hydrorefining straight-run kerosene or vacuum kerosene; hydrodesulfurization of straight-run kerosene or depressurized kerosene in one or more stages under conditions severer than ordinary hydrorefining And hydrodesulfurized kerosene obtained by hydrocracking the above-mentioned various kerosene base materials.

  The light oil base 1 and the light oil base 2 used in the present invention can be either a petroleum light oil base or a petroleum kerosene base, but the light oil base 2 with generally good oxidation stability is a petroleum kerosene base. Because it is a hydrodesulfurized gas oil base material obtained by hydrodesulfurizing only straight-run gas oil, or a hydrocracked kerosene base material or hydrocracked light oil base material obtained by hydrocracking at high temperature and pressure, From the viewpoint of high production costs and jet fuel use, the mixing ratio of the light oil base material 2 is preferably 70% by volume or less, more preferably 60% by volume or less, and particularly preferably 50% by volume or less. Further, the mixing ratio of the light oil base 2 is 5% by volume or more, preferably 10% by volume or more, more preferably 15% by volume or more, and particularly preferably 30% by volume or more in order to obtain an effect of improving oxidation stability.

  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, and still more preferably 25 to 200 mg / L. 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. 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. When such a commercial product is added to the fuel oil composition of the present invention, it is necessary to add an 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 cetane index of the light oil composition of the present invention is not particularly limited, but is preferably 40.0 or more from the viewpoint of engine ignitability, more preferably 45.0 or more, and 50.0. More preferably, it is more preferably 55.0 or more.
Further, the cetane number of the light oil composition of the present invention is not particularly limited, but it is preferably 40.0 or more, more preferably 45.0 or more, from the viewpoint of engine ignitability, 50 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 50.0, particularly when the cetane index is less than 47.0, it is preferable to add a cetane number improver to make the cetane number 50.0 or more. . Even when the cetane index is 50.0 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 the start 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 distillation properties of the light oil composition of the present invention are not particularly limited, but desirably satisfy the following properties.
10 vol% distillation temperature: 200-290 ° C
50 vol% distillation temperature: 220-300 ° C
90 vol% distillation temperature: 250-340 ° 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 10% by volume distillation temperature (hereinafter abbreviated as T10) is preferably 200 ° C. or higher, more preferably 210 ° C. or higher, still more preferably 215 ° C. or higher, particularly preferably. It is 220 degreeC or more, Preferably it is 290 degrees C or less, More preferably, it is 270 degrees C or less, More preferably, it is 250 degrees C or less. When T10 is less than 200 ° C., some light fractions are vaporized, and the amount of unburned hydrocarbons in the exhaust gas increases as the spray range becomes wide in the engine of a diesel vehicle. As a result, the startability at high temperatures and the stability of engine rotation at idling tend to decrease. On the other hand, when T10 exceeds 290 ° C., the startability and drivability at low temperatures in a diesel vehicle tend to be reduced.

  The 50% by volume distillation temperature (hereinafter abbreviated as T50) of the light oil composition of the present invention is preferably 220 ° C. or higher, more preferably 250 ° C. or higher, still more preferably 270 ° C. or higher, particularly preferably 280 ° C. or higher. In addition, it is preferably 300 ° C. or lower, more preferably 290 ° C. or lower, and further preferably 288 ° C. or lower. When T50 is less than 220 ° C., 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 T50 exceeds 300 ° C., particulate matter (hereinafter referred to as PM) tends to increase in diesel vehicles.

  The 90% by volume distillation temperature (hereinafter abbreviated as T90) of the light oil composition of the present invention is preferably 250 ° C. or higher, more preferably 255 ° C. or higher, further preferably 260 ° C. or higher, particularly preferably 270 ° C. Further, it is preferably 340 ° C. or lower, more preferably 337 ° C. or lower, and further preferably 335 ° C. or lower. When T90 is less than 250 ° C., 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 T90 exceeds 340 ° C., PM emitted from the engine in a diesel vehicle tends to increase.

  In addition, T10, T50, and T90 here mean the value measured based on JISK2254 "petroleum product-distillation test method-atmospheric pressure method", respectively.

  The light oil composition of the present invention will be specifically described with reference to examples. In addition, although this invention is realizable if it implements like the following examples, it is not limited to a present Example.

The physical property measurement method and evaluation method used in the present invention are measured by the following methods.
1) Density: A method defined in JIS K 2249 “Crude oil and petroleum products—Density test method and density / mass / capacity conversion table”.
2) Distillation property: A method defined in JIS K 2254 “Petroleum products—Distillation test method”.
3) Sulfur content: The method specified in JIS K 2541-6 “Crude oil and petroleum products—Sulfur content test method (ultraviolet fluorescence method)”.
4) Aromatic content: Method specified in JPI-5S-49-97 "Petroleum products-Hydrocarbon type test method-High performance liquid chromatograph method"

[Examples 1-3 and Comparative Examples 1-3]
Gas oil base A obtained by hydrodesulfurizing straight-run middle distillate, kerosene base B obtained by hydro-desulfurizing straight-run kerosene fraction, cracking system obtained from thermal cracking device Oil base C obtained by mixing the middle distillate with a hydrodesulfurization unit, obtained by hydrocracking a heavy fraction obtained by distillation under reduced pressure and mixing with a hydrodesulfurization unit Light oil base E, light oil base E obtained by mixing the middle distillate and straight fraction middle distillate obtained from a fluid oil cracking unit with a hydrodesulfurization unit, commercially available GTL (Gas to Liquid ) And heptamethylnonane (a reagent having a purity of 96% or more) was used to prepare a light oil composition. In addition, heptamethylnonane (a reagent having a purity of 96% or more) was used for preparing a light oil composition containing a large amount of isoparaffins. Table 4 shows the properties of these light oil bases. Tables 5 and 6 show the compositions and properties of the prepared diesel oil compositions (Examples 1 to 3 and Comparative Examples 1 to 3).

  From Table 5 and Table 6, the induction period of Comparative Example 1, Comparative Example 2 and Comparative Example 3 is short, and the actual value of the induction period is shorter than the calculated value of the induction period calculated by combining the mixed capacity ratios. Recognize. Compared to these, the induction period of Example 1 to Example 3 is long, the actual measurement value of the induction period is longer than the calculated value, and the effect of improving the oxidation stability by mixing the base materials (the actual and simple calculated values It can be seen that the difference is good.

  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)

Density of 0.810 to 0.825 g / cm ^{3 at} 15 ° C., and based on the total amount of the composition, the total sulfur content is 10 mass ppm or less, and the monocyclic naphthenobenzene content (ionic strength%) is 4.0 to 8 0.0, bicyclic naphthenobenzene content (ionic strength%) is 4.0 or less, isoparaffin content (ionic strength%) is 30.1 to 80.0, naphthalene content (ionic strength%) is A light oil composition that is 0.1 to 0.5 and has an induction period of 68 to 100 minutes. The light oil composition according to claim 1, wherein the following formula S2 calculated from the content of isoparaffins (ionic strength%) and the content of bicyclic cycloparaffins (ionic strength%) is 80 or more.
S2 = 100 × C / (C + D)
(C: Isoparaffin content (ionic strength%), D: Bicyclic cycloparaffin content (ionic strength%))   The gas oil base material 1 having an induction period of 30 minutes or more and less than 68 minutes is mixed with a gas oil base material 2 having an induction period of 80 minutes or more and less than 120 minutes to mix 5% by volume or more of the light oil base material as a whole. The manufacturing method of the light oil composition which manufactures the gas oil composition of description.