JPH0931477A - Unleaded gasoline - Google Patents

Abstract

(57) [Abstract] (Correction) [PROBLEMS] To provide unleaded gasoline that reduces the ozone production ability of evaporative emissions from automobiles, reduces the amount of benzene, and reduces photochemical reactivity and harmfulness. SOLUTION: Formula 1 X = Σ (C _i × MIR _i ) + 1.6 × RVP (1) [C _i is a C2-6 olefinic hydrocarbon or diolefinic compound contained in unleaded gasoline. Concentration (% by weight) of hydrocarbon component i, MIR _i is the MIR value of component i (gO
₃ / gNMOG) and RVP represents the vapor pressure (kPa) of unleaded gasoline, and 40 ≦ RVP ≦ 100. ] Evaporative gas ozone production index X of 64 to 130, and the formula 2 Y = BZ × (0.0715 × RVP-1.045) (2) [BZ is benzene contained in unleaded gasoline The RVP is the same as above. ] The unleaded gasoline whose evaporative emission index Y is less than or equal to 2.5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel unleaded gasoline, and more particularly to an unleaded gasoline capable of reducing the ozone producing ability of evaporative gas discharged from an automobile or the like and reducing the amount of benzene in the evaporative gas. It is a thing.

[0002]

When ultraviolet rays from the sun act on nitrogen oxides and hydrocarbons emitted from automobiles and other sources, photochemical oxidants mainly composed of ozone are produced. This product is a so-called photochemical smog, which is an environmental pollutant that causes acute damage such as irritating the eyes and throat of human beings, especially in areas where the air is likely to stay on a windy day. . In particular, hydrocarbon emissions from automobiles should be divided into exhaust gas exhausted from the exhaust pipe after combustion of fuel gasoline in the engine and fuel gasoline evaporative gas exhausted from the carburetor, fuel tank, fuel system, etc. You can In order to reduce the amount of hydrocarbon emission as described above, regarding the exhaust gas, a detergent was added for the purpose of maintaining its detergency from the viewpoint that dirt in the intake system increases the amount of hydrocarbon emission. Gasoline has been proposed from the viewpoint that deviation from the appropriate range of the air-fuel ratio during engine transient operation increases hydrocarbon emission, and gasoline having improved air-fuel ratio responsiveness. However, with respect to the above-mentioned evaporative gas, the fact is that few methods have been proposed for reducing the emission amount of hydrocarbons.

Under these circumstances, the present inventors have examined exhaust gas from automobiles, particularly evaporative gas during hot soak. That is, in general, there is a charcoal canister as a measure on the automobile side for preventing evaporative hydrocarbons from being released into the atmosphere while the engine is stopped. This is because evaporative hydrocarbons generated in a gasoline fuel tank are temporarily stored in activated carbon in a canister, and while the engine is operating, purge air is drawn in from the bottom of the canister body, and the evaporative hydrocarbons are introduced into the combustion chamber along with the air. It is a device that guides and burns. Usually, most of the evaporative gas hydrocarbons are captured by the canister, but in the hot soak, a slight amount of the evaporative gas hydrocarbons is actually released from the atmospheric opening at the bottom of the canister body. The inventors of the present invention have conducted studies to reduce the amount of hydrocarbons in the evaporative gas in order to improve the ozone producing property and the harmfulness of the evaporative gas. It has been found that the toxicity has a clear correlation with the composition and properties of fuel gasoline. The present invention has been accomplished based on the above findings. That is, the present invention provides a lead-free gasoline that reduces the ozone producing ability of evaporative gas discharged from an automobile and reduces the photochemical reactivity and harmfulness of the evaporative gas by reducing the amount of benzene in the evaporative gas. It was made for the purpose.

[0004]

The inventors of the present invention have identified specific parameters such as the concentration of each hydrocarbon in fuel gasoline, the MIR value, the benzene concentration, and the index as to the photochemical reactivity and harmfulness of the vaporized gas. The present invention found that the evaporative gas ozone productivity index X and the evaporative gas harmful index Y calculated from the vapor pressure of gasoline were found, and that gasoline in which these indexes are adjusted to a specific range can effectively achieve the above object of the present invention. Is completed. That is, the present invention provides the formula (1) X = Σ (C _i × MIR _i ) + 1.6 × RVP (1) [wherein C _i is 2 to 2 carbon atoms contained in unleaded gasoline]
6 represents the weight concentration (wt%) of the component i of the olefinic hydrocarbon or diolefinic hydrocarbon of 6 and MIR _i is the MIR value of the component i of the olefinic hydrocarbon or diolefinic hydrocarbon having 2 to 6 carbon atoms. (GO ₃ / gNMOG), and RVP represents the vapor pressure (kPa) of unleaded gasoline.
However, 40 ≦ RVP ≦ 100. ] The evaporative gas ozone productivity index X represented by is a value within the range of 64 to 130, and Y = BZ x (0.0715 x RVP-1.045) ... (2) [In the formula, BZ represents the weight concentration (% by weight) of benzene contained in unleaded gasoline, and RVP represents the vapor pressure (kPa) of unleaded gasoline. However, 40 ≦ RVP ≦ 100. ] An unleaded gasoline having an evaporative emission gas harmful index Y of 2.5 or less is provided.

The present invention will be described in more detail below. Book
The unleaded gasoline of the invention is an evaporation gas represented by the above formula (1).
The ozone production index X is a value within the range of 64-130.
It is necessary to From the canister during hot soak
Fuel gas scorpion which gives to ozone generating ability of evaporative gas discharged
As a result of examining the influence of the composition and properties of the ozone
Is an olefin having 2 to 6 carbon atoms contained in gasoline
Concentration of each component of hydrocarbon series or diolefin series
(Wt%) and the sum of MIR values of the components, that is,
Σ (C_i× MIR_i) Value and the vapor pressure of gasoline
I found out that That is, when the vapor pressure is constant
In this case, the ozone generation ability of the evaporative gas is Σ (C_i× MI
R _i) Linearly increases as the value of) increases, and Σ (C
_i× MIR_iWhen the value of) is constant, the ozone generation capacity is
A linearly increasing relationship was observed with increasing vapor pressure.
You.

Furthermore, by multiple regression analysis, Σ (C_i× MI
R_i) Value and vapor pressure value are ozone generation of evaporative gas
When the degree of influence on the performance is investigated, the vapor pressure is 1 kPa and Σ
(C _i× MIR_i) 1.6 (wt% · gO_Three/ GNMO
It was confirmed that G) had the same degree of influence. From the above, the book
In the present invention, the evaporative gas ozone production of fuel gasoline
Let the index X be Σ (C_i× MIR_i) + 1.6 × RVP and regulation
Conventional gasoline by reducing this value
Emitted from the canister during hot soak compared to
As a result, the ozone generation ability of the evaporative gas can be reduced.
As photochemical reactivity, that is, suppresses the generation of photochemical smog
Finds that it can offer a viable unleaded gasoline
did. In the present invention, the above equation (1) is expressed by RVP
Is applicable in the range of 40 to 100. This range
The box is in JIS K 2202 "Automobile gasoline"
It includes the range of RVP.

In the present invention, the evaporative gas ozone productivity index X is a value within the range of 64-130. When the value of X exceeds 130, the ozone generation ability of the vaporized gas becomes high as described above. Further, the smaller the value of Σ (C _i × MIR _i ) in the above formula (1) is, the better the environment is, but the vapor pressure RVP is not preferable from the viewpoint of engine startability. That is, considering the temperature in Japan, if the vapor pressure is less than 40 kPa, it may be difficult to start the engine depending on the vehicle type. Therefore, the lower limit of the vapor pressure is set to 40 kPa, and the lower limit of the evaporative gas ozone productivity index X corresponding to this is set. The value was defined as 64. Considering the above points, the evaporative gas ozone productivity index X is 64 to 100.
It is more preferable that the value is within the range.

In the above equation (1), Σ (C _i
X MIR _i ) C _i and MIR _i are both 2 to 2 carbon atoms.
It is a value about the component i of the olefinic hydrocarbon and the diolefinic hydrocarbon of No. 6. That is, as a result of conducting a hot soak test described later, the hydrocarbon content discharged from the canister has 7 carbon atoms if the vapor pressure of gasoline is extremely high.
Alternatively, although the component of 8 also increases slightly, it may be considered that most of the components within the vapor pressure range of commercially available gasoline are components having 2 to 6 carbon atoms. In addition, as far as the hydrocarbon content within the range of 2 to 6 carbon atoms is concerned, the photochemical reactivity of olefin-based hydrocarbons and diolefin-based hydrocarbons is significantly higher than that of saturated hydrocarbon content and aromatic content. Therefore, in the present invention, both C _i and MIR _i are limited to those of the olefinic hydrocarbon and diolefinic hydrocarbon components having 2 to 6 carbon atoms.

[0009] Here, the MIR value is a value proposed for evaluating the photochemical reactivity of organic compounds in vehicle exhaust gas, and ozone increases when a certain organic compound is released into the atmosphere. The maximum value when the production amount is obtained under various conditions is shown. That is, the conventional exhaust gas regulation was based on the total concentration of nitrogen oxides and hydrocarbons, but in recent years, in the United States, in order to obtain a new index for more effectively preventing photochemical smog, The measurement of productivity using a photochemical reaction model has been studied, and in fact, several methods have been proposed. Since many of these methods depend on environmental conditions, measured values cannot be obtained unless environmental conditions are determined, whereas MIR (Maximum Incremental Reactivi)
ty) method is a method that reflects the maximum ozone production potential of hydrocarbons under certain environmental conditions. Given that the most effective measure for ozone reduction is to control the most reactive types of hydrocarbons, this method is well suited to provide indicators for use in regulatory measures. It can be said that there is. From this point, the California Air Resources Board (CARB) of the United States of America calculates the ozone production performance of the exhaust gas by the following equation (3) using the above MIR value and calculates the photochemical reactivity of the exhaust gas. It is used as an index. Ozone generation capacity (gO ₃ / gNMOG) = Σ [NMOG _i (g / mile) × MIR _i (gO ₃ / gNMOG)] / ΣNMOG _i (g / mile) (3) [wherein NMOG _i is , The amount of hydrocarbons other than methane and the component i of the oxygen-containing organic compound, and MIR _i is the MIR value of the component i. ]

The present invention has found the above-mentioned formula (1) using the above MIR value, and the unleaded gasoline whose evaporative gas ozone productivity index X represented by this formula is in the range of 64-130 is the above-mentioned ozone. Although it has been found that the unleaded gasoline of the present invention is particularly excellent from the viewpoint of production ability, in addition to this, the vaporized gas harmful index Y represented by the above formula (2) is 2.5. The following values are required. In general, when the benzene content in fuel gasoline is high, not only the gasoline itself has a bad influence on the human body, but also the benzene content in the exhaust gas is high. It has been known that this benzene content is harmful to the human body such as a suspected carcinogenic substance, and causes various problems such as environmental pollution. In particular, as a result of examining the influence of the composition and properties of gasoline on the benzene content in the evaporative gas discharged from the canister during hot soaking, the concentration (wt%) of benzene contained in the gasoline and the vapor pressure RVP of the gasoline Have been found to contribute significantly. That is, the benzene content in the evaporative gas (Evp.-B
Z) (mg / TEST) to the benzene content (Fuel.-BZ) (wt%) contained in gasoline and the vapor pressure (kPa) of gasoline, the vapor pressure is 40 to
There is a linear relationship in the range of 100 kPa, and this relationship can be expressed by the following equation. (Evp.-BZ) / (Fuel.-BZ) = 0.0715 × RVP-1.045 This equation can be modified as follows. Evp.-BZ = (Fuel.-BZ) × (0.0715 × RVP-1.045)

From the above, in the present invention, the calculated Evp.-BZ is defined as the evaporative emission harmful index Y to reduce the benzene content in gasoline or the vapor pressure of gasoline, that is, (Fuel. -BZ) x (0.071
5 × RVP-1.045)
Compared to conventional gasoline, the amount of benzene in the evaporative gas discharged from the canister during hot soaking can be reduced. As a result, it is possible to obtain unleaded gasoline with less harmful vaporized gas. In the present invention, the evaporative gas harmful index Y represented by the above formula (2) is 2.5 or less. If the above value exceeds 2.5, the benzene content in the evaporative gas increases, and the harmfulness of the evaporative gas increases. Therefore,
From such a point of view, it is more preferable that the evaporative emission index Y is 1.5 or less. Further, the unleaded gasoline of the present invention preferably has a benzene content of 1.0% by weight or less from the viewpoint of reducing the harmfulness thereof.

The unleaded gasoline of the present invention may have any composition and properties as long as it satisfies the above-mentioned conditions, and the origin thereof is not particularly limited. For example, the following gasoline base material is used. Then, it can be prepared by appropriately mixing the above conditions and the required JIS standard. Examples of such a gasoline base material include light naphtha obtained by fractionating a naphtha fraction obtained by atmospheric distillation of crude oil, heavy naphtha, desulfurized light naphtha obtained by hydrorefining these, and desulfurized heavy naphtha. , Reformed gasoline obtained by catalytic reforming method, cracked gasoline obtained by catalytic cracking method, hydrocracking method, polymerized gasoline obtained by polymerization of olefin, addition of lower olefin to hydrocarbon such as isobutane (alkylation) Alkylate gasoline obtained by the above, isomerized gasoline obtained by isomerizing straight-chain lower paraffin hydrocarbons, or fractions or aromatic hydrocarbons having a specific boiling point range thereof,
Methyl tertiary butyl ether (MTBE) or the like can be used. Particularly, in the present invention, a light olefin fraction having a high photochemical reactivity, for example, a boiling point of 70 ° C.
The use of cracked gasoline from which the following fractions have been cut or fractions near the boiling point of benzene, for example reformed gasoline from which the boiling point in the range of 70 to 90 ° C. has been cut, is effective from the purpose.

In the present invention, the above-mentioned base materials are appropriately combined so as to satisfy the following properties required for unleaded gasoline, and both the evaporative gas ozone production index X and the evaporative gas harmful index Y satisfy the range of the present invention. Unleaded gasoline can be prepared as described above. Density (15 ° C.) 0.783 (g / cm ³ ) or less Research method octane number 89 or more 50% Distillation temperature 125 ° C. or less In addition, Σ of the formula (1) representing the evaporative gas ozone productivity index X
The (C _i × MIR _i ) term and the BZ term of the formula (2) representing the evaporative emission harmful index Y are quantified by separating and identifying each component of the gasoline base material by gas chromatography or the like, and previously obtained. It is desirable to keep.

The unleaded gasoline of the present invention may further contain various additives as required. Examples of such additives include oxygen-containing oxygen such as tertiary amyl methyl ether (TAME), ethyl tertiary butyl ether (ETBE), and tertiary amyl ethyl ether (TAEE) in addition to the above-mentioned methyl tertiary butyl ether (MTBE). Anti-knock agents such as compounds, phenolic and amine antioxidants, metal deactivators such as Schiff type compounds and thioamide type compounds, surface ignition inhibitors such as organophosphorus compounds, succinimide, polyalkyl Detergents and dispersants such as amines and polyether amines, anti-icing agents such as polyhydric alcohols and ethers, alkali metal and alkaline earth metal salts of organic acids, combustion improvers such as sulfuric acid esters of higher alcohols, anionic surfactants, Antistatic protection for cationic surfactants and amphoteric surfactants Agents, rust preventives such as alkenyl succinic acid esters, discriminating agents such as quilizanin and coumarin, odorants such as natural essential oils and synthetic fragrances, coloring agents such as azo dyes, corrosion inhibitors, bactericidal agents, lubricity imparting Known fuel oil additives such as agents are included, and one or more of these may be added. Further, the amounts of these additives can be appropriately selected according to the situation.

[0015]

(Properties)

(1) Density Determined according to JIS K-2249. (2) Research octane number (RON) Obtained in accordance with JIS K-2280. (3) Vapor pressure Determined according to JIS K-2258. (4) Distillation property Determined according to JIS K-2254. (5) Composition The content of each hydrocarbon in the fuel oil is determined according to the Japan Petroleum Institute method JPI-5S-33-90.

[Performance of Fuel Oil] (1) Hydrocarbon Content in Evaporative Gas Emitted to the Atmosphere during Hot Soak The vehicle used has an engine displacement of 2000 cc, in-line 4-cylinder, multi-point injection. Yes, it was a passenger car with an automatic transmission. Assuming an outside air temperature of 35 ° C in the summer, operating the engine under the conditions specified in the Federal Test Procedure under that temperature condition, stop the engine, and evaporate the gas discharged from the canister bottom opening within 1 hour. Concentration of individual hydrocarbons and gas weight (g /
TEST) was measured to calculate the weight of individual hydrocarbons (gNMOG _i / TEST) in the vaporized gas per test. (2) Ozone-producing ability Using the hydrocarbon weight and the MIR value shown in the following table, the ozone-producing ability was evaluated according to the equation (3). The MIR value used here is as described in J. P. "AUTO / OIL AIR QUAL reported by Cohen et al.
TY IMPROVEMENT RESEARCH
PROGRAM: DEVELOPMENT OF E
MISSIONS REACTIVITY VALUE
S FOR PHASE 1 RESULTS (199
January 29, 2nd, SYSAPP-92 / 012) ”of the Nomber 1991.

NMOG component MIR (gO ₃ / gNMOG) alkane Normal alkane methane 0.015 ethane 0.25 propane 0.48 n-butane 1.02 n-pentane 1.04 n-hexane 0.98 n-heptane 0.08 81 n-octane 0.61 n-nonane 0.54 n-decane 0.47 n-undecane 0.42 n-dodecane 0.38

Branched alkane 2-methylpropane 1.21 2,2-dimethylpropane 0.37 2-methylbutane 1.38 2,2-dimethylbutane 0.82 2,3-dimethylbutane 1.07 2-methylpentane 1 .53 3-methylpentane 1.52 2,2,3-trimethylbutane 1.32 2,2-dimethylpentane 1.40 2,3-dimethylpentane 1.51 2,4-dimethylpentane 1.78 3,3 -Dimethylpentane 0.71 2-Methylhexane 1.08 3-Methylhexane 1.40 2,2,4-Trimethylpentane 0.93 2,3,4-Trimethylpentane 1.60 2,2-Dimethylhexane 1. 20 2,3-Dimethylhexane 1.32 2,4-Dimethylhexane 1.50 2,5-Dimethylhexane 1.63 3,3-Dimethylhexane 1.20 2-Methylheptane 0.96 3-Methylheptane 0.99 4-Methylheptane 1.20 2,4-Dimethylheptane 1.34 2,2,5-Trimethylhexane 0.97 Other branched C ₉ H ₂₀ alkanes 1.14 Branched C ₁₀ H ₂₂ Alkane 1.01

Cycloalkane cyclopentane 2.38 Methylcyclopentane 2.82 Cyclohexane 1.28 c-1,3-Dimethylcyclopentane 2.55 t-1,2-Dimethylcyclopentane 1.85 Methylcyclohexane 1.85 Ethyl Cyclopentane 2.31 1c, 2t, 3-trimethylcyclopentane 1.94 Dimethylcyclohexane 1.94 Ethylcyclohexane 1.94

The alkenes ethene 7.29 propene 9.40 1-butene 8.91 1-butene 9.94 2-methylpropene 5.31 1-pentene 6.22 2-pentene 8.80 2-methyl-1-butene 4.90 3-Methyl-1-butene 6.22 2-Methyl-2-butene 6.41 1-Hexene 4.42 2-Hexene 6.69 3-Hexene 6.69 Methyl-1-pentene 4.42 Methyl 2-Pentene 6.69 3,3-Dimethyl-1-butene 4.42 1-Heptene 3.48 2-Heptene 5.53 3-Heptene 5.53 3-Ethyl-2-pentene 5.53 2,3 -Dimethyl-2-pentene 5.53 3-Methyl-1-hexene 3.48 2-Methyl-2-hexene 5.53 3-Methyl-3-hexene 5.53 1-octene 2.69 2-octene 5. 29 4-octene 5.29 2,4,4-trimethyl 1-pentene 2.69 2,4,4-trimethyl-2-pentene 5.29 1-nonene 2.23 propadiene 7.29 1,3-butadiene 10.89 2-methyl-1,3-butadiene 9.08 Cyclopentadiene 7.66 Cyclopentene 7.66 3-Methylcyclopentene 5.67 Cyclohexene 5.67

[0021] Alkyne ethyne 0.50 propyne 4.10 1-butyne 9.24 2-butyne 9.24 aromatic hydrocarbons as benzene 0.42 toluene 2.73 Ethylbenzene 2.70 o-Xylene 6.46 m-Xylene 7 .38 p-xylene 7.38 n-propylbenzene 2.12 i-propylbenzene 2.24 methylethylbenzene 7.20 1,2,3-trimethylbenzene 8.85 1,2,4-trimethylbenzene 8.83 1 , 3,5-Trimethylbenzene 10.12 n-Butylbenzene 1.87 s-Butylbenzene 1.89 Diethylbenzene 6.45 C ₁₀ Trialkylbenzene 9.07 Tetramethylbenzene 9.07 1-Methyl-4-isobutylbenzene 5 .84 Indane (C ₉ H ₁₀ ) 1.06 Naphthalene 1.18 Styrene 2.22

Aromatic oxygenate benzaldehyde 0.55 p-tolualdehyde 3.32 oxygenate alcohol methanol 0.56 ethanol 1.34 aldehyde formaldehyde 7.15 acetaldehyde 5.52 propionaldehyde 6.53 acrolein 6.77 n- Butyraldehyde 5.26 Crotonaldehyde 5.42 Pentane aldehyde 4.41 Hexane aldehyde 3.79 Ether methyl t-butyl ether 0.62 Ethyl t-butyl ether 1.98 Ketone acetone 0.56 Butanone 1.18

Examples 1 to 4 and Comparative Examples 1 to 4 Gasoline base materials having the properties shown in Table 1 were mixed in the proportions shown in Table 2 to prepare fuel oil, and their properties, composition and performance were evaluated. evaluated. Further, the evaporative gas ozone productivity index X and the evaporative gas harmful index Y were calculated from these values. Table 2 shows the results. However, in the calculation of the evaporative emission ozone productivity index X, the MIR value used was the value used in the evaluation of ozone productivity.

[0024]

[Table 1]

[0025]

[Table 2]

[0026]

[Table 3]

[0027]

[Table 4]

[0028]

As described above in detail, in the unleaded gasoline of the present invention, when the evaporative gas ozone production index X and the evaporative gas harmful index Y are set to values within a specific range, the evaporative gas emitted from the automobile is It is possible to significantly reduce the ozone-forming ability of the, and to reduce the amount of benzene in the vaporized gas. As a result, it becomes possible to reduce the photochemical reactivity and the harmfulness of the vaporized gas.

Claims (4)

[Claims] 1. A formula (1) X = Σ (C _i × MIR _i ) + 1.6 × RVP (1) [wherein C _i is 2 to 2 carbon atoms contained in unleaded gasoline.
6 represents the concentration (% by weight) of the component i of the olefinic hydrocarbon or diolefinic hydrocarbon of 6 and MIR _i is 2 carbon atoms.
Represents the MIR value (gO ₃ / gNMOG) of the component i of the olefinic hydrocarbon or the diolefinic hydrocarbon of
RVP represents the vapor pressure (kPa) of unleaded gasoline. However, 40 ≦ RVP ≦ 100. ] The evaporative gas ozone productivity index X represented by is a value within the range of 64 to 130, and Y = BZ x (0.0715 x RVP-1.045) ... (2) [In the formula, BZ represents the concentration (% by weight) of benzene contained in unleaded gasoline, and RVP represents the vapor pressure (kPa) of unleaded gasoline. However, 40 ≦ RVP ≦ 100. ] The unleaded gasoline whose evaporative gas poisoning index Y represented by is a value of 2.5 or less. 2. The harmful index of evaporative emission Y represented by the formula (2)
The unleaded gasoline according to claim 1, wherein is a value of 1.5 or less. 3. The unleaded gasoline according to claim 1, comprising a base material containing cracked gasoline from which a light olefin fraction has been cut and / or reformed gasoline from which a fraction near the boiling point of benzene has been cut. 4. The unleaded gasoline according to claim 1, which has a research octane number of 89 or more.