JP5464482B2 - Light oil composition - Google Patents

Description

The present invention relates to a light oil composition, and more specifically, satisfies all of the quality properties required as fuel oil for diesel engines, and in particular, the quality of a light oil composition and a light oil composition excellent in oxidation stability. The present invention relates to a management method, in particular, a method for determining oxidation stability. Moreover, according to this invention, the light oil composition suitable as a base fuel oil of biodiesel fuel oil can also be provided.

Pursuing the reduction of NOx and particulate matter (PM) emitted from diesel vehicles
It is an indispensable matter for environmental conservation measures now and in the future.
However, since the light oil fraction used as a diesel fuel for automobiles originally contains a sulfur content, and the sulfur content is a causative substance of particulate matter (PM) generated in exhaust gas by combustion, Reduction of sulfur content is required, and hydrodesulfurization of light oil fractions is generally performed. In order to further reduce the sulfur content to a lower content, deep hydrodesulfurization with severe hydrotreating conditions is performed.

However, according to the severe hydrodesulfurization under severe hydrotreating conditions, not only the removal of the sulfur content in the gas oil fraction, but also the natural substance that has an antioxidant action originally contained in the gas oil fraction. For example, since phenolic compounds, amine compounds and the like are also removed at the same time, although the sulfur content is removed in the gas oil fraction obtained by deep hydrodesulfurization, the oxidation stability is reduced,
Oxidation causes discoloration, formation of precipitates, peroxides, etc., leading to a reduction in commercial value.

In addition, biodiesel fuels mainly composed of light oil compositions, such as FAME mixed light oil, also generate sludge and acid due to oxidative degradation. Sludge causes poor sliding of automobile fuel pumps and injectors. Oxidation stability is a particularly important quality control item because it causes corrosion of metal parts.

Therefore, since the oxidation stability of the light oil composition is extremely important as a quality evaluation index of the light oil composition in the future from the above situation, the oxidation stability of the light oil composition is reduced under such circumstances. Development for improvement has been made, and various proposals have been made.

For example, according to Patent Document 1, a sulfur content is 5 mass ppm or less, and a distillation property with a distillation temperature of 220 ° C. or less is 8 vol% or less in a distillation property, and a monocyclic aromatic is 1.0 to 17.0 vol%. The fraction of the distillate fraction obtained by fractionating a fraction having a distillation temperature of 220 to 340 ° C. or higher into 5 pieces every 30 ° C. and 1
There has been proposed a light oil composition satisfying a parameter whose element is a ratio of aromatic content of 3 to 3 or more rings.

According to Patent Document 2, the total content of styrene compounds having a sulfur content of 10% by mass or less, C10 or more is 0.15% by mass or less, and the content of diene compounds having 15 or more carbons is the total. A diesel oil composition is proposed that satisfies the parameters of 2.00% by mass or less and styrene content, diene content, each content of bicyclic and tricyclic condensed polycyclic aromatic hydrocarbons .

Further, according to Patent Document 3, the sulfur content is 50 mass ppm or less, the sum of the contents of naphthenebenzenes and fluorenes is 8.0% by volume or less, and the content of naphthalenes is 0. There has been proposed a light oil composition that is not less than 0.5% by volume and not more than 3.0% by volume and satisfies the oxidation stability index obtained from parameters derived from the contents of fluorenes and naphthenebenzenes.

In view of such development status, the points that have been studied for improving the oxidation stability of light oil compositions have been to improve the oxidation stability by adding antioxidants, In terms of the composition, ingredients, properties, etc., the addition of antioxidants requires an oxidation stability test that takes 1-2 days to confirm the effect, so it is antioxidant. There is a problem that it takes a long time to grasp an appropriate amount of the agent added and to confirm the effect.

In addition, according to various quality controls focusing on the composition, components, properties, etc. of the light oil composition,
It takes a lot of time to analyze special components in light oil such as styrene, diene and fluorene.
Further, it has been pointed out that the content of such compounds is very difficult to control.

Under such circumstances, it is possible to evaluate by a simple means, and development of a light oil composition having excellent oxidation stability that can be provided by using such means has been eagerly desired.
JP 2008-7675 A JP 2008-144156 A JP 2006-137922 A

Therefore, the problem of the present invention is in light of the development status of conventional light oil compositions with improved oxidation stability.
Predicting oxidation stability by means of easy-to-measure properties of light oil, adjusting oxidation composition to provide excellent oxidation stability and reducing particulate matter (PM) emissions when used in diesel vehicles Another object is to provide a light oil composition that is environmentally friendly.

The second problem of the present invention is to provide a method for quickly determining the oxidation stability of a light oil composition, and to provide a method for improving the oxidation stability based on the determination result.

Thus, in order to solve the above-described problems of the present invention, the present inventors have made extensive studies on the correlation between the oxidation stability of light oil and the properties of light oil, and the oxidation stability of light oil is determined by the distillation of light oil. Paying attention to the properties and concentration of polycyclic aromatic compounds, the distillation properties have a specific boiling range and oxidative stability by satisfying specific conditions of polycyclic aromatic compounds concentration The present inventors have found that it is possible to provide a light oil composition excellent in the present invention, and have arrived at the completion of the present invention based on such knowledge.

Thus, according to the present invention,
In quality evaluation of oxidation stability of light oil composition,
(A) The sulfur content is 10 mass ppm or less, (b) the flash point is 60 ° C or higher, (c) the residual carbon content of 10% residual oil is 0.03 mass% or less, ( d) Regarding the light oil composition in which the temperature difference between the 95% distillation temperature and the initial boiling point is 120 ° C. or more in the distillation properties, and (e) the concentration of polycyclic aromatic compounds having two or more rings is 6% by volume or less,
The following formula (1);
X = 0.064 × IBP + 0.08 × T50−0.131 × T95−0.035
× PAH + 9.66 (1)
(Where IBP; initial boiling point in distillation properties (° C)
T50: 50% distillation temperature (° C) in distillation properties
EP: End point (° C) in distillation properties
PAH; polycyclic aromatic content of 2 or more rings (volume%))
A method for determining the oxidation stability of a light oil composition is provided, wherein the oxidation stability is determined by comparing a value calculated using a gas oil oxidation parameter X represented by formula (1) with a reference value (−1.17). Is done.

Further, according to the method for determining the oxidation stability of the light oil composition,
In the distillation property, the temperature difference between the 95% distillation temperature and the initial boiling point is 140 ° C. or more,
The initial boiling point is 190 ° C or lower,
95% distillation temperature is 330 ° C or higher,
It is preferable to target a light oil composition having an end point of 360 ° C. or lower.

Moreover, according to the present invention,
(A) About the light oil composition whose sulfur content is 10 mass ppm or less,
(B) The flash point is 60 ° C. or higher,
(C) The residual carbon content of 10% residual oil is 0.03% by mass or less,
(D) In the distillation properties, the temperature difference between the 95% distillation temperature and the initial boiling point is 160 ° C. or less,
(E) About a light oil composition having a polycyclic aromatic concentration of 2 or more rings of 6 vol% or less,
(F) the following formula (1);
X = 0.064 × IBP + 0.08 × T50−0.131 × T95−0.035 ×
PAH + 9.66 (1)
(Where IBP; initial boiling point in distillation properties (° C)
T50: 50% distillation temperature (° C) in distillation properties
T95: 95% distillation temperature (° C) in distillation properties
PAH; polycyclic aromatic content of 2 or more rings (volume%))
For the light oil composition having a gas oil oxidation parameter X of more than −1.17 obtained by using NO, an antioxidant is added to the total acid before and after the accelerated oxidation test (115 ° C., 16 hours, oxygen blowing rate 3 liters / minute). There is provided a method for improving the oxidative stability of a light oil composition comprising blending such that a value increment (ΔTAN) is 0.12 mgKOH / g or less.

  The antioxidant is preferably at least one compound selected from the group consisting of phenolic antioxidants and amine antioxidants.

  According to the present invention, by using the light oil oxidation parameter X represented by the formula (1), oxidation stability can be evaluated by a relatively simple method, and a light oil product having high oxidation stability is supplied. Can do.

  Further, according to the present invention, as a result of quality evaluation, when the value of the light oil oxidation parameter X exceeds the reference value of −1.17, an optimal effective amount without excess or deficiency of the antioxidant can be blended, The action of the antioxidant can be maximized. Further, by using the light oil oxidation parameter X, it is possible to quickly determine the oxidation stability, and it is possible to contribute to the production management of the light oil composition excellent in oxidation stability.

  Hereinafter, preferred embodiments of the present invention will be described in detail.

  The light oil composition (hereinafter referred to as “light oil composition”) targeted in the method for determining the oxidation stability of the light oil composition according to the present invention passes the standard of JIS K 2204 and has particular characteristics. The points will be described below.

The light oil composition according to the present invention has a sulfur content reduced to 10 ppm by mass or less. Preferably it is 7 mass ppm or less, More preferably, it is 3 mass ppm or less.
As described above, when the sulfur content exceeds 10 ppm by mass, the amount of particulate matter (PM) increases, which may lead to discharge of environmental pollutants.

According to JIS K 2204, the standard value of sulfur content was “50 mass pp in 2007”.
It was revised from "m or less" to "10 mass ppm or less".

The light oil composition according to the present invention has a flash point of 60 ° C. or higher, preferably 65 ° C. or higher, more preferably 70 ° C. or higher. When the flash point is less than 60 ° C., the lightness is increased, and there is a risk of ignition due to ignition.

According to the light oil composition of the present invention, the residual carbon content of 10% residual oil is 0.03% by mass.
Or less, preferably 0.02% by mass or less, more preferably 0.01% by mass or less. Such residual carbon content is generated when polycyclic aromatics having a large number of rings are excessively present, and if the content exceeds 0.03% by mass, PM may increase or combustion may be deteriorated.

The total aromatic content in the light oil composition according to the present invention is 1 from the viewpoint of ensuring oxidation stability.
It is 0 volume% or more, preferably 15 volume% or more, and more preferably 18 volume% or more.

On the other hand, if the total aromatic content is too large, the total aromatic content is 30% by volume or less, preferably 25% by volume or less, more preferably 22% by volume, from the viewpoint of deterioration in combustibility and increase in PM.
It is as follows.

In addition, the measuring method of total aromatic content is based on Petroleum Institute method JPI-5S-49.
Although it does not specifically limit about the cetane number of the light oil composition which concerns on this invention, Preferably it is 50 or more, More preferably, it is 53 or more, and can fully satisfy the specification of JISK2204.

Further, the density is 0.8400 or less at 15 ° C. and JIS of 0.86 or less.
K 2204 standard is fully satisfied.

About the light oil composition which concerns on this invention, in distillation property, the temperature difference of 95% distillation temperature and initial boiling point is at least 120 degreeC, Especially 140 degreeC or more, More preferably, it is 150 degreeC or more. Specifically, when the temperature difference is 140 ° C. or higher, the 95% distillation temperature is 330 ° C.
As described above, the initial boiling point is preferably adjusted to 190 ° C. or lower, and more preferably, the 95% distillation temperature is adjusted to 340 ° C. or higher and the initial boiling point is adjusted to 180 ° C. or lower when the temperature difference is 160 ° C. or higher.

If the temperature difference is large, it is presumed that the amount of components contributing to oxidation stability is ensured. On the other hand, if the temperature difference does not reach 145 ° C., even if the light oil oxidation parameter X is 0 or less, as shown in the examples described later, the increase in the total acid number due to accelerated oxidation increases, and the oxidation stability may decrease. Will occur.

Next, the light oil oxidation parameter represented by the formula (1) will be described.
In the method for determining the oxidation stability of the light oil composition according to the present invention, the following formula (1);
0.064 × IBP + 0.08 × T50−0.131 × T95−0.035 × PAH +
9.66 ≦ 0 (1)
It is necessary to satisfy the relationship.

Formula (1) shows that the initial boiling point, 50%, as a result of repeating a number of experiments in relation to the composition.
It is configured to have a specific relationship as seen in the above formula with the distillation property consisting of a distillation temperature and a 95% distillation temperature and the content of polycyclic aromatic compounds having two or more rings as elements.

The light oil composition according to the present invention is not particularly limited as long as it satisfies the relationship between the distillation property and the polycyclic aromatic content in the formula (1), and has the following distillation property. Those are preferred. In particular, those satisfying the relationship of 95% distillation temperature−initial boiling point> 120 ° C. are preferable as described above. In the present specification, the amount of distillation (%) in the distillation properties is volume%.

Initial boiling point; 170-190 ° C
10% distillation temperature; 205-225 ° C
50% distillation temperature; 270-290 ° C
90% distillation temperature; 310-330 ° C
95% distillation temperature; 320-350 ° C
End point; 325 to 360 ° C
In the light oil composition of the present invention, from the viewpoint of improving oxidation stability, the initial boiling point is preferably 190 ° C. or lower because the temperature difference between the 95% distillation temperature and the temperature is 120 ° C. or higher as described above.

However, if the initial boiling point is too low, some of the light fractions may be vaporized and unburned components may be mixed and discharged in the exhaust gas. 170 ° C
The above is preferable. If the initial boiling point is too high, a problem arises in low-temperature startability. However, in order to secure the oxidation stabilizing compound contained in the low-boiling fraction and maintain the temperature difference from the 95% distillation temperature as described above, 190 ° C. or lower. As a result, it is possible to ensure low temperature startability.

The 10% distillation temperature of the light oil composition according to the present invention is not particularly limited, but if it is too high, there is a possibility that a low temperature startability may be caused. Therefore, 240 ° C. or less, preferably 23
0 ° C. or lower, more preferably 225 ° C. or lower. On the other hand, when the temperature is too low, the vaporization problem may occur as in the case where the initial boiling point is too low. It is preferable that the temperature is higher than or equal to ° C, more preferably 205 ° C.

  In particular, it is preferable to set it as 205-225 degreeC from a viewpoint of ensuring oxidation stability.

The 50% distillation temperature of the light oil composition according to the present invention is preferably 250 ° C. or higher, more preferably 270 ° C. or higher, from the viewpoint of ensuring oxidation stability, and 310 from the viewpoint of fuel combustibility.
C. or lower, preferably 300.degree. C. or lower, more preferably 290.degree. C. or lower. The range of 270 to 290 ° C. is particularly preferable from the viewpoint of oxidation stability.

  The 90% distillation temperature of the light oil composition according to the present invention is not particularly limited, but is 360 ° C. or lower, preferably 340 ° C. or lower from the viewpoint of fuel combustibility, and 310 to 330 ° C. from the viewpoint of oxidation stability. The range of is preferable.

The 95% distillation temperature of the light oil composition according to the present invention is 310 ° C or higher, preferably 330 ° C or higher, in order to make the temperature difference from the initial boiling point 120 ° C or higher from the viewpoint of ensuring oxidation stability. More preferably, it is 340 ° C. or higher. On the other hand, when the 95% distillation temperature is too high, there is a concern of deterioration of combustibility and an increase in PM production, so that it is 380 ° C. or lower, preferably 360 ° C. or lower, more preferably 350 ° C. or lower.

The end point of the light oil composition according to the present invention is not particularly limited.
400 ° C. or less, preferably 380 ° C. or less, more preferably 360 ° C. or less from the viewpoint of an increase in M production, and a range of 325 to 360 ° C. is particularly preferable from the viewpoint of oxidation stability.

The measurement of the distillation properties is based on JIS K 2254 “Petroleum products—Distillation test method”.

Next, PAH, which is an element of the formula (1), indicates the content of polycyclic aromatics having two or more rings. According to the present invention, including the distillation properties, the light oil parameter X = 0. 064 x IBP
+ 0.08 × T50−0.131 × T95−0.035 × PAH + 9.66 = −1.17 to −4.08 (1)
It is necessary to satisfy this relationship.

When the PAH content in the light oil composition is too low, the distillation properties (IBP, TSO
, T95, E.M. When P) does not change significantly, the value of diesel oil oxidation parameter X increases,
On the other hand, when the oxidation stability is lowered and PAH is too high, the distillation properties are affected, the relationship of the above formula (1) cannot be satisfied, and excellent oxidation stability cannot be ensured.

Therefore, the PAH content of the light oil composition according to the present invention is preferably 6% by volume or less, 1% by volume or more, preferably 2% by volume or more, and more preferably 3% by volume or more. Here, the content of PAH was measured using JPI-5S-49, a method of the Petroleum Society of Japan.

Specific examples of the polycyclic aromatic having two or more rings in the PAH include naphthalene and naphthalene such as naphthalene having an alkyl substituent in the side chain, for example, 1-methylnaphthalene, 2- (1-methylethyl) naphthalene, 2,6-dimethylnaphthalene, 2,3,5-trimethylnaphthalene, 2,3,6-trimethylnaphthalene and the like, as well as anthracene, acenaphthylene, phenanthrene, and polycyclic aromatics thereof having an alkyl substituent Etc. are included.

  Moreover, according to this invention, as shown in Claim 1, the determination method of the oxidation stability of a light oil composition can be provided. On the assumption that all the elements (a) to (e) are satisfied, the oxidation stability is determined by comparing the value of the light oil oxidation parameter X in (f) with a reference value. The reference value is set to -1.17 based on Table 2 and Example 4.

  Therefore, when the light oil oxidation parameter X is ≦ −1.17, the oxidation stability is good, whereas when X is> −1.17, it is indicated that the addition of an antioxidant is necessary. As described above, the amount of the antioxidant added is such that the total acid value increase (ΔTAN) is 0.12 mgKOH / g or less.

By using the light oil oxidation parameter X, it is possible to provide a light oil composition having excellent oxidation stability by blending an appropriate effective amount of an antioxidant without excess or deficiency.

The light oil composition according to the present invention has undergone a deep hydrodesulfurization step, and most of the aliphatic unsaturation is removed, and the composition other than the aromatic is almost saturated.
In the light oil composition according to the present invention, an additive can be blended with the base oil as long as the effect of the present invention is not hindered.

As the base oil, those prepared by appropriately mixing base materials such as a straight-run gas oil fraction, a straight-run kerosene fraction, a catalytic cracking light oil fraction, and a hydrocracked light oil fraction can be used. The straight-run gas oil fraction is
It is a light oil fraction obtained by distilling crude oil with an atmospheric distillation apparatus, and a straight-run kerosene fraction is also a base material collected from an atmospheric distillation apparatus using crude oil as a raw material.

The cracking gas oil fraction is a cracked gas oil fraction obtained by a catalytic cracking apparatus using a vacuum gas oil or a vacuum residue oil as a raw material. The hydrocracked light oil fraction is a light oil fraction collected from cracked product oil obtained by hydrocracking using heavy oil as a raw material.

As the light oil base oil according to the present invention, a mixture obtained by mixing the base material so as to satisfy the above-mentioned distillation properties and other properties is used.
Additives to be blended in the light oil composition according to the present invention may include antioxidants, detergents, lubricity improvers, fluidity improvers, cetane number improvers, antistatic agents and the like as necessary. , One or a mixture of two or more can be used.

Although it does not specifically limit as antioxidant, Dibutylhydroxytoluene (
In addition to BHT), either phenolic antioxidants, amine antioxidants, or mixtures thereof can be used. Examples of phenolic antioxidants include 2,6-di-t-butylphenol, 2,6-di-t-butyl-4-methylphenol, 2,4-dimethyl-6-t-butylphenol, 2,4 , 6-tri-t-butylphenol, 2-t-butyl-4,6-dimethylphenol, 2-t-butylphenol and the like. As the amine-based antioxidant, N, N′-diisopropyl-p
-Diphenylenediamine, N, N'-di-sec-butyl-p-phenylenediamine and the like.

Furthermore, in particular, a hindered type phenolic antioxidant is preferable, specifically,
For example, 4,4′-thiobis (3-methyl-6-tert-butylphenol); 4,4′-thiobis (2-methyl-6-tert-butylphenol); 4,4′-methylenebis (2,6-diphenyl) -T-butylphenol); 4,4'-ethylenebis (2,6-di-t-butylphenol); 4,4'-propylidenebis (2-methyl-6-t-butylphenol); 2,2 '
-Methylenebis (4-ethyl-6-tert-butylphenol); 2,2'-methylenebis (
4-methyl-6-tert-butylphenol); 4,4′-butylidenebis (3-methyl-6)
-T-butylphenol); 4,4'-isopropylidenebis (2,6-di-t-butylphenol); 2,2'-methylenebis (4-methyl-6-nonylphenol); 2,2 '
-Isobutylidenebis (4,6-dimethylphenol), 2,2'-methylenebis (4-
Methyl-6-cyclohexylphenol), 1,6-hexanediol-bis [β- (3
, 5-di-tert-butyl-4-hydroxyphenyl) propionate], 1,4-bis (4
-Benzoyl-3-hydroxyphenoxy) -butane, 2,2-thio-diethylenebis [
β- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], tris (
3,5-di-tert-butyl-4-hydroxybenzyl) -isocyanurate, 1,1,3-
Tris (5-t-butyl-4-hydroxy-2-methylphenyl) butane, 1,3,5-
Trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl)
Benzene, tetrakis (methylene-3,5-di-tert-butyl-4-hydrohydrocinnamate, triethylene glycol-bis [β- (3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate] 3,9-bis [1,1-dimethyl-2- [β- (
3-t-butyl-4-hydroxy-5-methylphenyl) propionyloxyethyl] ethyl] -2,4,8,10-tetraoxospiro [5,5] undecane.

As shown in the test method described later, the amount of antioxidant added is the total acid value increase (Δ
TAN) may be adjusted so as to be 0.12 mgKOH / g or less.

  Therefore, specifically, for a light oil composition having a light oil oxidation parameter> -1.17, it is blended at a rate of 3 to 100 ppm by mass, preferably 5 to 50 ppm by mass, and more preferably 5 to 20 ppm by mass. do it.

Examples of the detergent include ashless detergents such as polyalkenyl succinimides, polyalkenyl succinic amides, succinic acid esters obtained by the reaction of polyalkenyl succinic anhydrides and polyhydric alcohols such as pentaerythritol, succinic acid. Acid ester-amide, benzamine amine and the like can be mentioned. These detergents can be used alone or in combination of two or more.

  As polyalkenyl succinimide, for example, formula (2)

The monopolyalkenyl succinimide represented by these can be used.
R1 in the above formula is an olefin oligomer residue having 30 or more carbon atoms, R2 is an alkylene group having 2 to 4 carbon atoms, and m is an integer of 1 to 10.
Moreover, Formula (3)

The bispolyalkenyl succinimide etc. which are represented by these can be mentioned.
R3 and R4 in the above formula are each an olefin oligomer residue having 30 or more carbon atoms, which may be the same or different from each other, and R5 and R6 are each an alkylene group having 2 to 4 carbon atoms. They may be the same or different from each other. n
Is an integer of 0 or 1-10.

These polyalkenyl succinimides can be usually produced by reacting a polyalkenyl succinic anhydride obtained by reaction of polyolefin and maleic anhydride with a polyalkylene polyamine. At this time, by changing the ratio of the polyalkenyl succinic anhydride and the polyalkylene polyamine, a monopolyalkenyl succinimide, a bispolyalkenyl succinimide, or a mixture thereof can be obtained.

In the production of polyalkenyl succinimide, the polyolefin used as a raw material has 30 or more, preferably 40 or more carbon atoms obtained by polymerizing olefins having 2 to 6 carbon atoms, and an average molecular weight of 500 to 20, 000, preferably 700 to 5,000. Examples of the olefin for producing the polyolefin include ethylene, propylene, 1-butene, isobutylene, 1-hexene, 2-methylpentene-
Preferable examples include α-olefins having 2 to 8 carbon atoms such as 1,1-octene. Particularly preferred polyolefins are polypropylene and polyisobutylene.

On the other hand, as the polyalkylene polyamine, a compound represented by the following formula (4) is used.

R2 and m in the general formula (4) have the same meaning as the compound of the general formula (2).
Moreover, as a polyalkylene polyamine, Formula (5)

The compound represented by these is used.
R5, R6 and n in the above general formula have the same meaning as in the above formula (3).

Examples of such polyalkylene polyamines include polyethylene polyamine, polypropylene polyamine, and polybutylene polyamine. Among these, polyethylene polyamine is preferred.

The amount of the detergent is usually 10 to 200 mass ppm, preferably 10 to 100 mass pp.
m. Examples of the lubricity improver include carboxylic acid-based, alcohol-based, and ester-based lubricity improvers, and ester-based is preferable.

Examples of the carboxylic acid-based lubricity improver include oleic acid, salicylic acid, palmitic acid, myristic acid, linoleic acid, and the like. These lubricating oil improvers can be used alone or in combination of two or more.

Examples of the ester-based lubricity improver include carboxylic acid esters of glycerin, and examples of the carboxylic acid include linoleic acid, oleic acid, salicylic acid, and palcytic acid.

The blending amount of the lubricity improver is 50 to 500 mg / L, preferably 100 to 300 mg / L.
It can be employed within the range. Examples of the fluidity improver include an ethylene-vinyl acetate copolymer, an ethylene-alkyl acrylate copolymer, and a polyalkyl methacrylate compound.
These fluidity improvers can be used alone or in combination of two or more.

The blending amount of the fluidity improver is usually 50 to 1000 ppm by mass, preferably 100 to 50 ppm.
Adopted in the range of 0 ppm by mass.

Examples of the cetane number improver include nitrate esters and organic peroxides, and one or a mixture of two or more can be used.

As the nitrate ester, 2-chloroethyl nitrate, 2-ethoxyethyl nitrate, 2-ethylhexyl nitrate, isopropyl nitrate, buker nitrate and the like can be used. The compounding amount of the cetane number improver is usually 100-1500 mg / L, preferably 200-10.
00 mg / L.

Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. However, the present invention is not limited to the examples.
In addition, about the oxidation stability of the light oil composition test oil used in the Example etc., it evaluated in accordance with the following accelerated oxidation test method.

Moreover, the property measuring method enumerated below was employ | adopted for the measurement of the property of test oil.
Further, the following materials were used as the substrate.

Oxidation stability evaluation Accelerated oxidation test method 350 ml of a sample is oxidatively deteriorated while blowing at 115 ° C. for 16 hours and oxygen at a rate of 3 liters per minute. Before and after this oxidation deterioration test, the total acid value was measured according to JIS K 2501, and the difference between the acid values before and after (ΔTAN) was determined.

Property Measurement Method (1) Density: JIS K2249 “Crude oil and petroleum products-Density / mass / capacity conversion table”
(2) Distillation properties: JIS K2254 "Petroleum products-Distillation test method"
(3) Flash point: JIS K2265 "Crude oil and petroleum products-Flash point test method"
(4) Residual carbon content: JIS K2270 “Crude oil and petroleum products-Residual carbon content test method”
(5) Cetane number: JIS K2280 "Petroleum products-fuel oil-octane number and cetane number test method and cetane index calculation method"
(6) Sulfur content: JIS K2541-6 "Crude oil and petroleum products-Sulfur content test method"
(7) Polycyclic aromatics: Petroleum Society method JPI-5S-49 "Petroleum products-Hydrocarbon type test method-High performance liquid chromatographic method"
<Base material>

Reference Examples 1-3, 10-11, Examples 4-9
Gas oil compositions G to I, P having mainly the straight-run gas oil among the above-mentioned base materials, mixing other base materials and having the properties shown in Table 1 and the characteristics defined in the standards of JIS K 2204 ~ N
Was prepared. Increase in total acid value by the oxidation degradation test method by accelerated oxidation of each gas oil composition (
ΔTAN) was measured, and the results are shown in the same table.

In Table 2, the light oil oxidation parameter X is displayed on the horizontal axis, and the measured value of the total acid value increase (ΔTAN) is displayed on the vertical axis, and the relationship between the light oil oxidation parameter X and the oxidation stability is shown.

In addition, an Example is related with the light oil composition which shows light oil oxidation parameter X <=-1.17, and is a case where all the other properties were also satisfied.
Reference Example 11
The results shown in Table 3 were obtained by blending 0-50 mass ppm of the antioxidant with the sample X shown in Table 1 having a light oil oxidation parameter X of -1.17 or more. In Table 3, the horizontal axis indicates the amount of antioxidant (Amount of anti-oxidant) (expressed in mass ppm), and the vertical axis indicates the total acid value increase (ΔTAN) (mgKOH / g), The relationship between the two is indicated by ◆.
Comparative Examples 1-11
The light oil compositions A to F and J to O having the distillation properties and various characteristics shown in Table 1 as in the examples.
The total acid value increase (ΔTAN) was measured for each prototype oil. The results are shown in the same table.

From the results of the above-mentioned Examples and Comparative Examples, the light oil composition satisfying the elements (a) to (e), particularly the distillation properties under specific conditions, and satisfying the light oil oxidation parameter X of (f) It was revealed that the increase (ΔTAN) was significantly reduced. In addition, when the light oil oxidation parameter X exceeds the reference value (−1.17), an appropriate amount of an antioxidant is blended to obtain a light oil composition with a drastic decrease in the total acid value increase as shown in Table 3. It has been shown that it can.

Table description
Table 1 shows properties of each gas oil composition test oil according to Reference Examples 1 to 3, 10, 11, Examples 4 to 9 and Comparative Examples 1 to 11, diesel oil oxidation parameter X, and total acid value increase (ΔTAN). This is a list.
Table 2 is a graph showing the relationship between the light oil oxidation parameter X and the total acid value increase (TAN Increase) (ΔTAN).
Table 3 shows the effect of anti-oxidant on the increase in total acid value (ΔTAN).
It is shown in relation to

Claims (2)

In quality evaluation of oxidation stability of light oil composition,
(A) The sulfur content is 10 mass ppm or less, (b) the flash point is 60 ° C or higher, (c) the residual carbon content of 10% residual oil is 0.03 mass% or less, ( d) Regarding a light oil composition having a distillation property in which a temperature difference between a 95% distillation temperature and an initial boiling point is 120 ° C. or more, and (e) a polycyclic aromatic concentration of two or more rings is 6% by volume or less.
The following formula (1);
X = 0.064 × IBP + 0.08 × T ₅₀ −0.131 × T ₉₅ −0.035 × PAH + 9.66 (1)
(Where IBP; initial boiling point in distillation properties (° C)
T ₅₀ ; 50% distillation temperature (° C) in distillation properties
EP: End point (° C) in distillation properties
PAH; polycyclic aromatic content of 2 or more rings (volume%))
A method for determining the oxidation stability of a gas oil composition, wherein the oxidation stability is determined by comparing a value calculated using a gas oil oxidation parameter X represented by the reference value (−1.17) . In the distillation property, the temperature difference between the 95% distillation temperature and the initial boiling point is 140 ° C. or more,
The initial boiling point is 190 ° C or lower,
95% distillation temperature is 330 ° C or higher,
The method for determining the oxidation stability of a light oil composition according to claim 1, wherein the end point is 360 ° C or lower.