JP2007084724A - Gasoline composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gasoline composition which reduces particulate matter (total PM) in an exhaust gas and also can reduce microparticles (nano PM). <P>SOLUTION: The gasoline composition contains 1-20 vol.% ethyl t-butyl ether, has a ≥10C aromatic content of ≤5 vol.%, has a density of 0.71-0.76 g/cm<SP>3</SP>at 15°C, and has a sulfur content of ≤3 mass ppm. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a gasoline composition, and more particularly to a novel gasoline composition that can reduce the emission of particulate matter together with particulate matter.

A conventional gasoline engine is a so-called MPI system that premixes fuel and air and introduces the premixed gas into a combustion chamber. In recent years, however, direct injection engines that inject fuel directly into the combustion chamber have emerged. As this type of engine, a lean burn combustion type and a stoichiometric combustion type are known, but it is said that both types can increase the compression ratio and improve fuel efficiency and reduce CO ₂ emissions. .
However, it is known that when normal gasoline is used in a direct injection engine, the amount of particulate matter (PM) in the exhaust gas increases due to insufficient mixing of gasoline and air. is required.

By the way, the particulate matter (PM) includes those having various particle sizes. In addition to particles having a particle size of about 50 to 1000 nm and particles having a particle size larger than that, the particle size is about There are also fine particles of 50 nm or less (hereinafter sometimes referred to as “nano PM”). Particles having a particle size of about 50 to 1000 nm are called accumulation mode particles, and are usually particles composed of carbonaceous aggregates having organic or inorganic substances adsorbed on the surface, whereas the particle size is 50 nm or less. The fine particles are called Nuclei mode particles or nanoparticles, and are formed by agglomeration in the process of diluting and cooling the volatile precursor in the exhaust gas. In any case, these are mixed and contained in the PM contained in the exhaust gas, that is, all PMs.
Further, in the direct injection type engine, the emission amount of nano-PM tends to increase among PM (total PM) particularly at high speed and high load operation. Therefore, even if the discharge amount of all PMs is suppressed, the discharge amount of nano PM may increase. Moreover, it is said that this nano PM may have various effects on not only the respiratory system but also the human body as compared to the accumulation mode particles.

On the other hand, in order to reduce CO in exhaust gas, it has been widely studied to add an oxygen-containing compound to gasoline, and in particular, ethyl tertiary butyl ether (ETBE) has attracted attention. It is known that a fuel oil containing an oxygen-containing compound containing ETBE can reduce the total PM (see, for example, Patent Document 1).
However, the known techniques including Patent Document 1 do not disclose anything about the technology for reducing the problematic nano PM.
Therefore, it is desired to develop a fuel oil that reduces the total PM and at the same time reduces the nano PM.

JP 2005-54103 A

  The present invention has been made under such circumstances, and provides a gasoline composition capable of reducing particulate matter (total PM) in exhaust gas and at the same time reducing fine particles (nano PM) in total PM. It is intended to do.

  The present inventors have found that the object can be achieved by blending ethyl tertiary butyl ether with gasoline having a specific composition. The present invention has been completed based on such findings.

That is, the present invention
1. 1 to 20% by volume of ethyl tertiary butyl ether, an aromatic content of 10 or more carbon atoms is 5% by volume or less, and a density at 15 ° C. is 0.71 to 0.76 g / cm ³ .
And the gasoline composition characterized by sulfur content being 3 mass ppm or less,
2. The gasoline composition according to 1 above, wherein the research octane number is 89 or more, the aromatic content is 45% by volume or less, the benzene content is 1% by volume or less, and the olefin content is 25% by volume or less.
3. The gasoline composition according to claim 1 or 2, wherein the 50% distillation temperature is 75 to 105 ° C, the 70% distillation temperature is 100 to 135 ° C, and the 90% distillation temperature is 110 to 175 ° C.
4). The gasoline composition according to any one of 1 to 3, which is for a direct injection gasoline engine,
Is to provide.

  The gasoline composition of the present invention is a gasoline composition capable of reducing particulate matter (total PM) in exhaust gas and at the same time reducing fine particles (nano PM).

The gasoline composition of the present invention contains 1 to 20% by volume of ethyl tertiary butyl ether (hereinafter sometimes referred to as “ETBE”). When the content of ETBE is less than 1% by volume, the effect of reducing total PM or nano PM may not be sufficiently obtained. The content of ETBE is preferably 5% by volume or more, more preferably 7% by volume or more. On the other hand, if the ETBE content exceeds 20% by volume, it is difficult to control the air / fuel ratio of the engine, which may affect engine control during excessive response. Therefore, the preferable ETBE content is 15% by volume or less. The content of ETBE is a value measured by an all-component test method using a gas chromatograph in JIS K 2536-2 “Petroleum product-component test method”.
There is no restriction | limiting in particular about the manufacturing method of ETBE, Even if it is ETBE obtained by what manufacturing method, it can be used. For example, a method of reacting isobutylene and ethanol can be mentioned. In this case, ethanol as a raw material may be obtained from a known production method, but may be so-called bioethanol (ethanol produced from biomass such as sugarcane or corn fermentation). Use of bioethanol as the raw material ethanol is preferable for CO ₂ countermeasures.

The gasoline composition of the present invention has an aromatic content of 10 or more carbon atoms (hereinafter sometimes referred to as “C10 ⁺ A”) of 5% by volume or less. If C10 ⁺ A exceeds 5% by volume, the effect of reducing total PM and nano PM may not be sufficiently obtained. C10 ⁺ A is preferably 3% by volume or less, and more preferably 1.5% by volume or less.
In addition, this C10 ⁺ A is the value measured by the all-component test method by the gas chromatograph of JISK2536-2 "Petroleum product-component test method".

The gasoline composition of the present invention has a density at 15 ° C. of 0.71 to 0.76 g / cm ³ . If the density at 15 ° C. exceeds 0.76 g / cm ³ , the effect of reducing total PM or nano PM may not be sufficiently obtained. On the other hand, if the density at 15 ° C. is less than 0.71 g / cm ³ , the output of the engine is reduced and the fuel consumption is deteriorated.
The density at 15 ° C. here is a value measured according to JIS K 2249 “Crude oil and petroleum products—Density test method and density / mass / capacity conversion table”.

The gasoline composition of the present invention is further required to have a sulfur content of 3 ppm by mass or less. If the sulfur content exceeds 3 ppm by mass, it becomes difficult to suppress nano PM (Nuclei mode particles, nanoparticles). In other words, nano PM emissions can be reduced by satisfying the above requirements and setting the sulfur content to 3 mass ppm or less. Therefore, the sulfur content is more preferably 2 mass ppm or less, and further preferably 1 mass ppm or less.
The sulfur content is a value measured according to JIS K 2541-2 “Crude oil and petroleum products—sulfur content test method”.

  The gasoline composition of the present invention preferably has a research octane number (RON) of 89 or more, more preferably 90 or more. If the RON is 89 or more, there is no possibility that the driving performance is deteriorated such as knocking. However, the premium specification is preferably 96 or more. On the other hand, the upper limit of RON is not particularly limited, but is usually about 105. The octane number of the research method is a value measured by JIS K 2280 “Petroleum products—fuel oil—octane number and cetane number test method and cetane index calculation method”.

  The gasoline composition of the present invention preferably has an aromatic content of 45% by volume or less, more preferably 40% by volume or less, and still more preferably 35% by volume or less. When the aromatic content is 45% by volume or less, there is no fear that hydrocarbons (THC) and CO in the exhaust gas will increase, and there is no fear that the spark plug will smolder, and the operating performance can be kept good. On the other hand, the lower limit of the aromatic content is not particularly limited, but it is preferably 5% by volume or more from the viewpoint of deterioration of fuel consumption and prevention of reduction in driving performance. The aromatic content is a value measured by the fluorescent indicator adsorption method of JIS K 2536-1 “Petroleum product-component test method”.

In the gasoline composition of the present invention, the benzene content is preferably 1% by volume or less, and more preferably 0.5% by volume or less. If the benzene content is 1% by volume, the benzene content in the exhaust gas is reduced, and there is no risk of environmental pollution becoming a problem. In addition, there is no risk that gasoline itself will adversely affect the human body.
In addition, benzene content is the value measured by the all component test method by the gas chromatograph of JISK2536-2 "Petroleum product-component test method".

  In the gasoline composition of the present invention, the olefin content is preferably 30% by volume or less, and more preferably 25% by volume or less. If the olefin content is 30% by volume or less, nitrogen oxides in the exhaust gas will not increase, and gasoline evaporated in the atmosphere will not generate ozone. Furthermore, there is no possibility that the oxidation stability of gasoline itself will deteriorate. The lower limit of the olefin content is preferably 3% by volume. If the lower limit of the olefin content is 3% by volume or more, there is no risk of misfire in a lean combustion state, and the driving performance of the direct injection engine vehicle can be ensured. The olefin content is a value measured by JIS K 2536-2 “Petroleum product component-component test method”.

The gasoline composition of the present invention preferably has the following distillation properties. In addition, the inside of () shows a more preferable range.
50% distillation temperature (T50): 75 to 105 ° C (78 to 100 ° C)
70% distillation temperature (T70): 100 to 135 ° C (105 to 130 ° C)
90% distillation temperature (T90): 110-175 ° C (110-170 ° C)
Distillation end point (EP): 210 ° C. or lower (200 ° C. or lower)
If T50, T70, T90, and EP are within the above ranges, driving performance such as acceleration is kept good, and fuel consumption is not deteriorated.
The above T50, T70, T90 and EP are values obtained from the distillation properties measured based on JIS K 2254 “Petroleum products-distillation test method”.

  The gasoline composition of the present invention can be produced by any method. For example, it can prepare using the gasoline base material shown next with ETBE. Examples of gasoline base materials include light naphtha obtained by atmospheric distillation of crude oil, cracked gasoline obtained by catalytic cracking or hydrocracking, and benzene in reformed gasoline obtained by catalytic reforming. Obtained by isomerization of straight chain lower paraffinic hydrocarbons, alkylates obtained by adding lower olefins to hydrocarbons such as isobutane, polymerized gasoline obtained by olefin polymerization Isomerized gasoline (isomerate), de-n-paraffin oil, and a specific range of these fractions and aromatic hydrocarbons.

Preferred examples of the composition of the gasoline composition of the present invention include the following.
(1) Debenzene reformed gasoline 0-70% by volume
(2) Cracked gasoline 0-80% by volume
(Mixture of light cracked gasoline and desulfurized heavy cracked gasoline)
(3) Light cracked gasoline 0-55 volume (4) Alkylate 0-60 volume%
(5) Desulfurized light naphtha 0-30% by volume
(6) Butane, LPG 0-15% by volume
(7) ETBE 1-20% by volume

  Various additives can be appropriately blended in the gasoline composition of the present invention as necessary. Examples of such additives include phenolic and amine antioxidants, metal deactivators such as Schiff compounds and thioamide compounds, surface ignition inhibitors such as organophosphorus compounds, succinimides, and polyalkylamines. , Detergents such as polyetheramines, anti-icing agents such as polyhydric alcohols and ethers, organic acid alkali metals and alkaline earth metal salts, auxiliary alcohols such as higher alcohol sulfates, anionic surfactants, cationic surfactants Agents, antistatic agents such as double-sided surfactants, rust inhibitors such as esters of alkenyl succinic acid, identifiers such as kilyzanine and coumarin, odorants such as natural essential oils and synthetic fragrances, colorants such as azo dyes, etc. Known gasoline additives can be mentioned, and one or more of these additives can be added. Further, the additive amount of these additives may be appropriately selected depending on the situation, but it is usually preferable that the total amount of the additive is 0.1% by mass or less based on the gasoline composition.

EXAMPLES Next, although an Example demonstrates this invention in detail, this invention is not restrict | limited at all by these examples. The properties and performance of the gasoline composition were determined according to the following method.
[Properties of gasoline composition]
(1) Research octane number,
Measurement was performed according to JIS K 2280.
(2) Sulfur content Measured according to JIS K 2541-2.
(3) Aromatic content, olefin content, benzene, aromatic content having 10 or more carbon atoms. These were measured according to JIS K 2536-2.
(4) Distillation property Measured according to JIS K2541.
(5) Density The density was measured according to JIS K 2249.

[Total PM, Nano PM emissions]
(1) Engine used 4-cylinder direct-injection lean-burn gasoline engine with a displacement of 2.5L (2) Engine operation method After running for 15 minutes at 60km / h, run in 10.15 mode to perform warm-up operation. went. Thereafter, the speed was increased stepwise from 0 → 60 → 100 → 120 km / h. After reaching 120 km / h, particles discharged for 10 minutes were collected, and the concentrations of total PM and nanoPM were measured.
(3) Measurement conditions for all PMs and nano PMs Measuring device: SMPS (Scanning Mobility Particle Sizer)
Dilution device: Microtunnel Temperature: 25 ° C
Humidity: 50%
Dilution ratio: 25

Examples 1-5 and Comparative Examples 1-3
Using the gasoline base material shown in Table 1, a gasoline composition was prepared by mixing at the ratio shown in Table 2, and its properties, composition and performance are shown in Table 2.
In Tables 1 and 2, LFG is light cracked gasoline, PG is debenzene reformed gasoline, PG (C10 + A) is reformed gasoline excluding fractions with 9 or less carbon atoms, and ALK is alkylate gasoline. , FG is cracked gasoline, ETBE is ethyl tertiary butyl ether, DLN is desulfurized light naphtha, and LPG is liquefied petroleum gas.

  According to the gasoline composition of the present invention, particulate matter (total PM) in exhaust gas can be reduced, and at the same time, fine particles (nano PM) can be reduced. Therefore, it is useful as gasoline that can prevent environmental pollution.

Claims (4)

It contains 1 to 20% by volume of ethyl tertiary butyl ether, has an aromatic content of 10 or more carbon atoms of 5% by volume or less, a density at 15 ° C. of 0.71 to 0.76 g / cm ³ , and a sulfur content of 3 A gasoline composition having a mass ppm or less.   The gasoline composition according to claim 1, having a research octane number of 89 or more, an aromatic content of 45% by volume or less, a benzene content of 1% by volume or less, and an olefin content of 25% by volume or less.   The gasoline composition according to claim 1 or 2, wherein the 50% distillation temperature is 75 to 105 ° C, the 70% distillation temperature is 100 to 135 ° C, and the 90% distillation temperature is 110 to 175 ° C. The gasoline composition according to any one of claims 1 to 3, which is for a direct injection gasoline engine.