Fuel composition for spark ignition engines and method for blending fuel oil base stock

Abstract

To provide a fuel composition for a spark ignition engine that is rich in volatility of mixed water and has excellent ability to reduce the volatility.SOLUTION: A fuel composition for a spark ignition engine has (1) an aromatics total content ratio of 30.0 vol.% or less, (2) an oxygen-containing compound content ratio of 0.10 vol.% or less, (3) a moisture volatilization coefficient V of 33.0 or more (V is calculated by V=0.82(P4+0.70*O4)+0.70(P5+0.70*O5)+0.56(P6+0.70*O6)+0.48(P7+0.70*O7)+0.48(P8+0.70*O8) (Formulation I), where P4 to P8 each indicate a content ratio (vol.%) of liner saturated hydrocarbon having 4 to 8 carbon atoms, and O4 to O8 each indicate a content ratio (capacity%) of unsaturated hydrocarbon having 4 to 8 carbon atoms), and (4) a research octane number of 96 or more.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a fuel composition for spark ignition engines and a method for formulating a fuel oil basestock. [Background technology]

[0002] Hydrocarbon components such as fuel compositions for spark ignition engines have a low water solubility of several tens to several hundreds of ppm, and the saturated solubility varies with temperature. Fuel compositions for spark ignition engines may come into contact with moisture during transportation, storage, etc., and may contain dissolved moisture close to the saturation solubility. When a spark ignition engine fuel composition containing moisture close to its saturated solubility is cooled in accordance with a change in the environmental temperature, the moisture in the composition may begin to separate, resulting in the spark ignition engine fuel composition becoming cloudy or producing free water.

[0003] As a fuel composition for spark ignition engines having excellent water turbidity prevention performance, for example, a gasoline fuel composition in which the ethanol content and the olefin content are specified (see Patent Document 1) has been proposed. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2007-91922 A DISCLOSURE OF THEINVENTION [Problem to be solved by the invention]

[0005] The gasoline fuel composition described in Patent Document 1 is intended to suppress turbidity due to water by blending ethanol therein to increase the amount of water that can be dissolved in the gasoline fuel composition.

[0006] On the other hand, since fuel compositions for spark ignition engines consist of a mixture of hydrocarbons, it is generally difficult to obtain water solubility without using a hydrophilic compound such as an oxygen-containing compound such as ethanol.

[0007] Under these circumstances, the present inventors came up with the idea of ​​a fuel composition for spark ignition engines that is excellent in the ability to reduce mixed-in water by improving the volatility of water, instead of a fuel composition for spark ignition engines in which the solubility of water is improved.

[0008] An object of the present invention is to provide a fuel composition for spark ignition engines which is highly volatile and has excellent water reduction capabilities when mixed with it, and a method for blending fuel oil base materials for preparing such a fuel composition for spark ignition engines. [Means for solving the problem]

[0009] In order to achieve the above object, the present inventors have evaluated the volatilization characteristics of dissolved water for each of the hydrocarbons constituting a fuel composition for a spark ignition engine. That is, for each hydrocarbon, water was dissolved up to the saturation amount and then the mixture was allowed to stand for 15 minutes at room temperature (20°C). From the change in the amount of dissolved water before and after standing, the volatilization rate of the dissolved water {(amount of dissolved water reduced by standing for 15 minutes / amount of dissolved water before standing)×100} (%) was measured, which led to the following findings (a) to (d). (a) Of the linear saturated hydrocarbons constituting the fuel composition for spark ignition engines, the proportions of volatilization of dissolved water in the linear saturated hydrocarbons having 4 to 8 carbon atoms, which are the main components, are as follows on a mass basis: Chain saturated hydrocarbons with 4 carbon atoms (n-butane): 82% Chain saturated hydrocarbons with 5 carbon atoms (n-pentane): 70% Chain saturated hydrocarbons with 6 carbon atoms (n-hexane): 56% Chain saturated hydrocarbons with 6 carbon atoms (2-methylpentane): 56% Chain saturated hydrocarbons with 7 carbon atoms (n-heptane): 48% Chain saturated hydrocarbons with 8 carbon atoms (n-octane): 48% Therefore, the ratio of the volatilization rates of dissolved water in chain saturated hydrocarbons with 4 to 8 carbon atoms can be considered to be chain saturated hydrocarbons with 4 carbon atoms: chain saturated hydrocarbons with 5 carbon atoms: chain saturated hydrocarbons with 6 carbon atoms: chain saturated hydrocarbons with 7 carbon atoms: chain saturated hydrocarbons with 8 carbon atoms = 0.82:0.70:0.56:0.48:0.48. (b) When the number of carbon atoms is the same, the amount of dissolved water that evaporates is lower in unsaturated hydrocarbons (olefins) than in linear saturated hydrocarbons (paraffins). Compared to the amount of dissolved water that evaporates in linear saturated hydrocarbons with the same number of carbon atoms, the amount of dissolved water that evaporates in unsaturated hydrocarbons is about 0.70 times that of unsaturated hydrocarbons on a mass basis. (c) The amount of dissolved water that evaporates from aromatic compounds is negligibly small compared to that of linear saturated and unsaturated hydrocarbons. (d) The content of cyclic saturated hydrocarbons (naphthenes) in a fuel composition for spark ignition engines is usually very low, so that the amount of dissolved water that evaporates can be ignored.

[0010] Based on the findings of (a) to (d) above, the present inventors derived a moisture volatility coefficient V represented by a specific formula, and found that when the moisture volatility coefficient V is equal to or greater than a predetermined value, the mixed moisture can be effectively volatilized and the moisture content can be suitably reduced, thereby completing the present invention.

[0011] That is, the present invention provides (I) (1) The total aromatic content is 30.0% by volume or less; (2) The content of oxygen-containing compounds is 0.10% by volume or less; (3) The following formula (I) V=0.82(P4+0.70×O4)+0.70(P5+0.70×O5)+0.56(P6+0.70×O6)+0.48(P7+0.70×O7)+0.48(P8+0.70×O8) (I) (wherein P4 to P8 respectively indicate the content ratio (volume %) of chain saturated hydrocarbons having 4 to 8 carbon atoms, and O4 to O8 respectively indicate the content ratio (volume %) of unsaturated hydrocarbons having 4 to 8 carbon atoms), and the moisture volatility coefficient V calculated by the above is 33.0 or more, (4) Research octane number is 96 or higher A fuel composition for spark ignition engines, (II) A method for blending fuel oil base stocks to prepare a fuel composition for a spark ignition engine, comprising: (1) The total aromatic content is 30.0% by volume or less; (2) The content of oxygen-containing compounds is 0.10% by volume or less; (3) The following formula (I) V=0.82(P4+0.70×O4)+0.70(P5+0.70×O5)+0.56(P6+0.70×O6)+0.48(P7+0.70×O7)+0.48(P8+0.70×O8) (I) (wherein P4 to P8 respectively indicate the content ratio (volume %) of chain saturated hydrocarbons having 4 to 8 carbon atoms, and O4 to O8 respectively indicate the content ratio (volume %) of unsaturated hydrocarbons having 4 to 8 carbon atoms), and the moisture volatility coefficient V calculated by the above is 33.0 or more, (4) Research method octane number of 96 or more A method for blending a fuel oil base stock, comprising the steps of: obtaining a fuel composition for spark ignition engines, the fuel composition comprising: This provides: Effect of the Invention

[0012] Effects of the Invention The present invention can provide a fuel composition for spark ignition engines which is highly volatile and has excellent water reduction capabilities when mixed with water, and a method for blending fuel oil base materials for preparing such a fuel composition for spark ignition engines. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, an embodiment of the present invention will be described in detail. In this specification, the term "to" used to indicate a range of values ​​indicates a range that includes the values ​​set forth as the upper and lower limits. When a unit is set forth only for the upper limit of a range of values ​​set forth as "to", this also means that the lower limit is set in the same unit. In the present specification, any upper or lower limit value described in a numerical range may be replaced with the upper or lower limit value of another numerical range described in a numerical range. In this specification, the content or amount of each component in a composition means, when multiple substances corresponding to each component are present in the composition, the total content or amount of those multiple substances present in the composition, unless otherwise specified. As used herein, combinations of preferred aspects are more preferred aspects.

[0014] The fuel composition for a spark ignition engine according to the present invention comprises: (1) The total aromatic content is 30.0% by volume or less; (2) The content of oxygen-containing compounds is 0.10% by volume or less; (3) The following formula (I) V=0.82(P4+0.70×O4)+0.70(P5+0.70×O5)+0.56(P6+0.70×O6)+0.48(P7+0.70×O7)+0.48(P8+0.70×O8) (I) (wherein P4 to P8 respectively indicate the content ratio (volume %) of linear saturated hydrocarbons having 4 to 8 carbon atoms, and O4 to O8 respectively indicate the content ratio (volume %) of unsaturated hydrocarbons having 4 to 8 carbon atoms.) The moisture volatility coefficient V calculated by is 33.0 or more, (4) Research method octane number of 96 or more It is characterized in that:

[0015] The fuel composition for spark ignition engines according to the present invention has a total content of (a) aromatic components (aromatic hydrocarbons) of 30.0 vol. % or less (0.0 to 30.0 vol. %), preferably 0.0 to 29.0 vol. %, and more preferably 0.0 to 28.0 vol. %.

[0016] By having the total aromatic content in the spark ignition engine fuel composition be 30 volume % or less, the contents of other components can be easily controlled within the desired range, making it possible to easily exert the volatility of water.

[0017] In the present application, the total aromatic content refers to a value measured according to JIS K 2536-2 "Petroleum products - Testing methods for components, Part 2: Determination of total components by gas chromatography".

[0018] The fuel composition for spark ignition engines according to the present invention has a content of the oxygen-containing compound (b) of 0.10% by volume or less (0 to 0.10% by volume), preferably 0 to 0.09% by volume, and more preferably 0 to 0.08% by volume.

[0019] Oxygen-containing compounds generally have high hydrophilicity and low water volatility, so by having the total content in the fuel composition for spark ignition engines be 0.10 volume % or less, the content ratios of other components can be easily controlled within the desired range, making it easy to exert water volatility.

[0020] In the spark ignition engine fuel composition according to the present invention, the oxygen-containing compound means an oxygen atom-containing compound which is blended as a constituent base material of the spark ignition engine fuel composition, and specific examples thereof include one or more compounds selected from ethyl tertiary butyl ether (ETBE), tertiary amyl methyl ether (TAME), tertiary amyl ethyl ether (TAEE), ethanol, butanol, etc.

[0021] In the present application, the content of oxygen-containing compounds means a value measured according to JIS K 2536-2 "Petroleum products - Testing methods for components, Part 2: Determination of total components by gas chromatography".

[0022] The fuel composition for spark ignition engines according to the present invention comprises: V=0.82(P4+0.70×O4)+0.70(P5+0.70×O5)+0.56(P6+0.70×O6)+0.48(P7+0.70×O7)+0.48(P8+0.70×O8) (I) (wherein P4 to P8 respectively indicate the content ratio (volume %) of linear saturated hydrocarbons having 4 to 8 carbon atoms, and O4 to O8 respectively indicate the content ratio (volume %) of unsaturated hydrocarbons having 4 to 8 carbon atoms.) The moisture volatility coefficient V calculated by the above formula is 33.0 or more.

[0023] In the fuel composition for spark ignition engines according to the present invention, the water volatility coefficient V is 33.0 or more, preferably 34.0 or more, and more preferably 35.0 or more. In order to fully utilize the usefulness of the water volatilization in a fuel composition for spark ignition engines, it is necessary to volatilize about 40% of the water, and at this time the water volatilization coefficient V is 33.0. There is no particular upper limit to the water volatilization coefficient V, but taking into account production costs and practicality, the water volatilization coefficient is usually preferably 45.0 or less. In the fuel composition for spark ignition engines according to the present invention, since the water volatility coefficient V is 33.0 or more, it is possible to easily provide a fuel composition for spark ignition engines which has high volatility of mixed-in water and excellent water reduction capacity.

[0024] In the spark ignition engine fuel composition according to the present invention, P4 (the content (volume %) of linear saturated hydrocarbons having 4 carbon atoms), P5 (the content (volume %) of linear saturated hydrocarbons having 5 carbon atoms), P6 (the content (volume %) of linear saturated hydrocarbons having 6 carbon atoms), P7 (the content (volume %) of linear saturated hydrocarbons having 7 carbon atoms) and P8 (the content (volume %) of linear saturated hydrocarbons having 8 carbon atoms) mean values ​​measured in accordance with JIS K 2536-2 "Petroleum products -- Testing methods for components, Part 2: Determination of total components by gas chromatography". In addition, the fuel composition for spark ignition engines may contain saturated hydrocarbons with a carbon number of more than 8. However, since the content ratio of such saturated hydrocarbons and the amount of volatilization of dissolved water are relatively low, they can be ignored when calculating the water volatilization coefficient V.

[0025] In the fuel composition for spark ignition engines according to the present invention, O4 (the content (volume %) of unsaturated hydrocarbons having 4 carbon atoms), O5 (the content (volume %) of unsaturated hydrocarbons having 5 carbon atoms), O6 (the content (volume %) of unsaturated hydrocarbons having 6 carbon atoms), O7 (the content (volume %) of unsaturated hydrocarbons having 7 carbon atoms) and O8 (the content (volume %) of unsaturated hydrocarbons having 8 carbon atoms) mean values ​​measured in accordance with JIS K 2536-2 "Petroleum products -- Testing methods for components, Part 2: Determination of total components by gas chromatography". In addition, in a fuel composition for a spark ignition engine, unsaturated hydrocarbons having a carbon number of more than 8 may be contained. However, since the content ratio of such unsaturated hydrocarbons and the amount of volatilization of dissolved water are relatively low, they can be ignored when calculating the water volatilization coefficient V.

[0026] As described above, formula (I), which is a formula for calculating the water volatility coefficient V, was derived by dissolving water in each of the hydrocarbons constituting the fuel composition for a spark ignition engine until the saturation amount, and then allowing the composition to stand for 15 minutes at room temperature (20°C), and measuring the dissolved water volatility ratio {(amount of dissolved water reduced by allowing the composition to stand for 15 minutes / amount of dissolved water before allowing the composition to stand)×100} (%) from the change in the amount of dissolved water before and after allowing the composition to stand. More specifically, the dissolved water volatility ratio was determined by the following method.

[0027] <Method for evaluating the volatility of dissolved water> (1) Preparation of measurement samples Water (distilled water), the hydrocarbons to be measured (reagent), and a 100 ml glass container with a lid are left to stand at room temperature, and then 20 ml of water and 80 ml of the hydrocarbons (reagent) are added to the glass container, which is then vigorously shaken by hand for 1 minute to thoroughly dissolve the water. Thereafter, the glass container is placed in a thermostatic chamber set at 20° C. and left to stand for one day. After standing, the glass container is separated into two layers, a water layer and a hydrocarbon layer. The hydrocarbon layer is used as a measurement sample in which water has been dissolved until it reaches saturation. (2) Measurement of the amount of dissolved water evaporated 30 ml of the measurement sample (hydrocarbon layer) prepared in (1) above at 20°C is dispensed into a 60 ml syringe vial, and the dissolved water content (saturated water content) is measured by Karl Fischer coulometric titration (JIS K 2275-3). Thereafter, the gas phase in the syringe vial is replaced with nitrogen gas at a temperature of 28° C. and a humidity of 4%, and after the vial is capped, it is left to stand in a thermostatic bath at 20° C. for 15 minutes. Next, a measurement sample is taken from the syringe vial using a syringe, and its moisture content is measured by Karl Fischer coulometric titration (JIS K 2275-3). The volatilization rate is calculated as the mass-based change in dissolved moisture content {(amount of dissolved moisture reduction after standing for 15 minutes / amount of dissolved moisture before standing)×100} (%), and the volatilization characteristics are evaluated.

[0028] The fuel composition for spark ignition engines according to the present invention may contain various fuel additives as required. Examples of fuel additives include phenolic, amine-based and other antioxidants, metal deactivators such as thioamide compounds, surface ignition inhibitors such as organic phosphorus compounds, detergent dispersants such as succinimide, polyalkylamines, polyetheramines and polyisobutyleneamines, friction modifiers such as polyhydric alcohol esters and amide compounds, anti-icing agents such as polyhydric alcohols and their ethers, combustion improvers such as alkali metal and alkaline earth metal salts of organic acids and sulfates of higher alcohols, antistatic agents such as anionic surfactants, cationic surfactants and amphoteric surfactants, rust inhibitors such as alkenyl succinate esters, and colorants such as azo dyes, as well as known fuel additives. The fuel composition for spark ignition engines according to the present invention may contain one or a combination of two or more of these fuel additives. The content of these fuel additives is not particularly limited, but it is usually preferable that the total amount added is 0.1 mass% or less.

[0029] The fuel composition for spark ignition engines according to the present invention preferably has a sulfur content of 10 ppm by mass or less. In the fuel composition for spark ignition engines according to the present invention, the sulfur content is 10 ppm by mass or less, so that deterioration of the performance of the exhaust gas purification catalyst can be suppressed, and emissions of nitrogen oxides (NOx), hydrocarbons (THC), carbon monoxide (CO), etc. can be reduced, and the amount of sulfur oxides (SOx) in the exhaust gas can be reduced. In the present application, the sulfur content refers to a value measured according to the provisions of JIS K 2541.

[0030] The fuel composition for spark ignition engines according to the present invention has a 10% distillation temperature T10 of 30 to 70°C or lower, preferably 35 to 65°C, and more preferably 40 to 60°C. The fuel composition for spark ignition engines according to the present invention preferably has a 50% distillation temperature T50 of 75 to 110°C, more preferably 75 to 108°C, and even more preferably 75 to 105°C. The fuel composition for spark ignition engines according to the present invention has a 90% distillation temperature T90 of 100 to 180°C or lower, preferably 100 to 160°C, and more preferably 100 to 140°C.

[0031] According to the investigations of the present inventors, for each of the hydrocarbons constituting a fuel composition for a spark ignition engine, the amount of dissolved water that evaporates at room temperature (20°C) is greater for those with a smaller carbon number (i.e., generally, those with a lower boiling point). Therefore, since the fuel composition for spark ignition engines according to the present invention is composed of hydrocarbons with a low boiling point, any moisture contained therein is easily volatilized, and the moisture content can be easily reduced.

[0032] In the present application, the distillation properties such as T10, T50 and T90 of the fuel composition for spark ignition engines refer to values ​​measured in accordance with JIS K 2254 "Petroleum products-Distillation test method".

[0033] In the fuel composition for spark ignition engines according to the present invention, the research octane number (RON) is preferably 96-111, more preferably 96-109, and even more preferably 96-107.

[0034] In the spark ignition engine fuel composition according to the present invention, the RON is within the above range, so that the fuel can be used in any spark ignition engine. In the present application, RON means a value measured in accordance with the provisions relating to the research octane number test method in JIS K 2280 "Petroleum products-Fuel oil-Octane number and cetane number test method and cetane index calculation method."

[0035] The fuel composition for spark ignition engines according to the present invention has a density at 15°C of 0.700 to 0.783 g / cm 3 Preferably, the viscosity is 0.710 to 0.783 g / cm 3 More preferably, it is 0.720 to 0.783 g / cm 3 It is even more preferable that: In the fuel composition for spark ignition engines according to the present invention, when the density at 15° C. is within the above range, a decrease in fuel economy can be easily suppressed. In the present application, the density at 15°C means a value measured in accordance with the provisions of JIS K 2249 "Crude petroleum and petroleum products -- Density test method and density, mass and volume conversion tables."

[0036] The fuel composition for spark ignition engines according to the present invention preferably has a Reid vapor pressure (RVP) of 44 to 93 kPa, more preferably 46 to 93 kPa, and even more preferably 48 to 93 kPa. In the present application, the Reid vapor pressure (RVP) was measured according to the provisions of JIS K 2258-1. In the fuel composition for spark ignition engines according to the present invention, the Reid vapor pressure (RVP) is within the above range, so that drivability can be maintained.

[0037] It is desirable that the properties of the spark ignition engine fuel composition according to the present invention other than those mentioned above satisfy the regulations of JIS K 2202 Type 1 for motor gasoline.

[0038] The spark ignition engine fuel composition according to the present invention can be used as a gasoline fuel composition or the like in general spark ignition engines such as automobile engines.

[0039] The fuel composition for spark ignition engines according to the present invention is not particularly limited, but can be prepared as necessary by appropriately blending any of the gasoline base stocks (i) to (vi) described below in a desired ratio as a fuel oil base stock. (i) Catalytic cracking gasoline obtained by cracking heavy diesel or vacuum diesel using a solid acid catalyst (e.g., silica-alumina mixed with zeolite) using a conventionally known catalytic cracking process, particularly a fluid catalytic cracking process (UOP process, Shell two-stage process, Flexicracking process, Ultra Orthoflow process, Texaco process, Gulf process, UltraCat cracking process, RCC process, HOC process, etc.) using heavy diesel or vacuum diesel as raw materials. (ii) Desulfurized light naphtha, which is the light fraction obtained by distilling desulfurized straight-run naphtha obtained by desulfurizing straight-run naphtha obtained by atmospheric distillation of crude oil and separating the desulfurized straight-run naphtha into light and heavy fractions. (iii) Alkylate obtained by reacting isobutane with lower olefins (butene, propylene, etc.) in the presence of an acid catalyst (sulfuric acid, hydrogen fluoride, aluminum chloride, etc.). (iv) C4 fractions mainly composed of butane and butenes obtained by distillation during atmospheric distillation of crude oil, raw oil, etc., during the production of reformed gasoline, or during the production of cracked gasoline, etc. (v) Isopentane obtained by isomerization of linear lower paraffinic hydrocarbons or by precision distillation of the isomerate. (vi) A light catalytic reformate fraction and a heavy catalytic reformate fraction obtained from a catalytic reformer.

[0040] In the spark ignition engine fuel composition according to the present invention, the fuel oil base materials are mixed in a desired ratio so that the resulting spark ignition engine fuel composition satisfies the above-mentioned respective requirements for (1) the total aromatic content, (2) the oxygen-containing compound content, (3) the water volatility coefficient V, and (4) the research octane number (RON).

[0041] According to the present invention, it is possible to provide a fuel composition for spark ignition engines which has high volatility of mixed water and has excellent water reduction ability.

[0042] Next, a method for blending the fuel oil base material according to the present invention will be described. The method for blending a fuel oil basestock according to the present invention is a method for blending a fuel oil basestock for preparing a fuel composition for a spark ignition engine, comprising the steps of: (1) The total aromatic content is 30.0% by volume or less; (2) The content of oxygen-containing compounds is 0.10% by volume or less; (3) The following formula (I) V=0.82(P4+0.70×O4)+0.70(P5+0.70×O5)+0.56(P6+0.70×O6)+0.48(P7+0.70×O7)+0.48(P8+0.70×O8) (I) (wherein P4 to P8 respectively indicate the content ratio (volume %) of chain saturated hydrocarbons having 4 to 8 carbon atoms, and O4 to O8 respectively indicate the content ratio (volume %) of unsaturated hydrocarbons having 4 to 8 carbon atoms), and the moisture volatility coefficient V calculated by the above is 33.0 or more, (4) Research method octane number of 96 or more The present invention is characterized in that it provides a fuel composition for spark ignition engines,

[0043] In the method for blending a fuel oil base stock according to the present invention, specific examples of the fuel oil base stock can include those mentioned above. In the method of blending fuel oil base stocks according to the present invention, the blending ratios of the fuel oil base stocks to be blended are determined based on (i) the total aromatic content, (ii) the oxygen-containing compound content, (iii) P4 to P8 and O4 to O8, and (iv) the research octane number in each of the fuel oil base stocks to be blended, so that the resulting fuel composition for spark ignition engines will have predetermined values ​​for (1) the total aromatic content, (2) the oxygen-containing compound content, (3) the water volatility coefficient V, and (4) the research octane number, respectively. Then, by blending the various fuel oils, the desired fuel composition for spark ignition engines can be prepared.

[0044] Details of the fuel composition for spark ignition engines obtained by the method for blending a fuel oil base material according to the present invention are as described above in the explanation of the fuel composition for spark ignition engines according to the present invention.

[0045] According to the present invention, it is possible to provide a method for blending a fuel oil base material, which can easily produce a fuel composition for spark ignition engines which has high volatility of contaminated water and has excellent water reduction properties.

[0046] The present invention will be described in more detail below with reference to examples. However, these examples are merely examples of the case where the present invention is carried out, and the present invention is not limited to these examples in any way. The analytical values ​​in the table were measured according to the above-mentioned measuring methods.

[0047] In the following examples and comparative examples, light catalytic cracked gasoline (L-FCC, a light fraction obtained by fractionating catalytic cracked gasoline into light and heavy fractions by distillation), heavy catalytic reformate (H-RMT), alkylate (ALKY), C4 fraction (C4), and diisobutylene (DIB) were used as base materials.

[0048] (Example 1 to Example 2) A fuel composition for spark ignition engines was prepared by blending the above-mentioned light catalytic cracked gasoline (L-FCC), heavy catalytic reformed gasoline (H-RMT), alkylate (ALKY), C4 fraction (C4) and diisobutylene (DIB) as gasoline base stocks in the blending ratios shown in Table 1 so that the resulting gasoline composition would have the desired values ​​of (1) total aromatic content (volume %), (2) oxygen-containing compound content (volume %), (3) water volatility coefficient V, and (4) research octane number (RON). The properties of the spark ignition engine fuel compositions obtained in each example are shown in Table 2.

[0049] Comparative Example 1 A gasoline fuel composition was prepared as a fuel composition for spark ignition engines by blending the above-mentioned light catalytic cracked gasoline (L-FCC), heavy catalytic reformed gasoline (H-RMT) and C4 fraction (C4) as base materials in the blending ratios shown in Table 1. The properties of the spark ignition engine fuel composition obtained in Comparative Example 1 are shown in Table 2.

[0050] In Table 2, the volatilization rate (%) of dissolved water, which is an evaluation index of volatility characteristics, was determined by the method described below.

[0051] <Method for measuring the amount of dissolved water evaporated> (1) Preparation of measurement samples Water (distilled water), the spark ignition engine fuel composition to be measured, and a 100 ml glass container with a lid are left to stand at room temperature, and then 20 ml of water and 80 ml of the spark ignition engine fuel composition are added to the glass container, and the glass container is shaken vigorously by hand for 1 minute to thoroughly dissolve the water. Thereafter, the glass container is placed in a thermostatic chamber set at 20° C. and left to stand for one day. After standing, the glass container is separated into two layers, a water layer and a hydrocarbon layer. The hydrocarbon layer is used as a measurement sample in which water has been dissolved until it reaches saturation. (2) Measurement of the amount of dissolved water evaporated 30 ml of the measurement sample (hydrocarbon layer) prepared in (1) above at 20°C is dispensed into a 60 ml syringe vial, and the dissolved water content (saturation water content (ppm by mass)) is measured by Karl Fischer coulometric titration (JIS K 2275-3). Thereafter, the gas phase in the syringe vial is replaced with nitrogen gas at a temperature of 28° C. and a humidity of 4%, and after the vial is capped, it is left to stand in a thermostatic bath at 20° C. for 15 minutes. Next, a measurement sample is taken from the syringe vial using a syringe, and its moisture content is measured by Karl Fischer coulometric titration (JIS K 2275-3). The percentage of volatilization of dissolved moisture is calculated as the percentage change in dissolved moisture content by mass {(amount of dissolved moisture reduced by leaving the sample undisturbed for 15 minutes / amount of dissolved moisture before leaving the sample undisturbed)×100} (%).

[0052] [Table 1]

[0053] [Table 2]

[0054] As can be seen from Table 2, the fuel compositions for spark ignition engines obtained in Examples 1 and 2 were prepared so that (1) the total aromatic content, (2) the oxygen-containing compound content, (3) the water volatility coefficient V, and (4) the research octane number were all desired values. Therefore, it can be seen that the dissolved water volatility rate was high at 41 to 48%, the mixed water was highly volatile, and the fuel compositions had excellent water reduction capabilities.

[0055] On the other hand, as can be seen from Table 2, the fuel composition for spark ignition engines obtained in Comparative Example 1 did not satisfy the specified regulations in terms of (1) the total aromatic content and (3) the water volatility coefficient V, and therefore the rate of change in the dissolved water content (the rate of volatilization of the dissolved water content) was low at 28%, indicating that the volatility of the mixed water was poor. [Industrial Applicability]

[0056] Effects of the Invention The present invention can provide a fuel composition for spark ignition engines which is highly volatile and has excellent water reduction capabilities when mixed with water, and a method for blending fuel oil base materials for preparing such a fuel composition for spark ignition engines.

Claims

1. (1) The total aromatic content is 30.0% by volume or less; (2) The content of oxygen-containing compounds is 0.10% by volume or less; (3) A compound represented by the following formula (I): V=0.82(P4+0.70×O4)+0.70(P5+0.70×O5)+0.56(P6+0.70×O6)+0.48(P7+0.70×O7)+0.48(P8+0.70×O8) (I) (wherein P4 to P8 each indicate the content ratio (volume %) of linear saturated hydrocarbons having 4 to 8 carbon atoms, and O4 to O8 each indicate the content ratio (volume %) of unsaturated hydrocarbons having 4 to 8 carbon atoms), is 33.0 or more and 45.0 or less, (4) Research octane number is 96 or more. A fuel composition for spark ignition engines comprising:

2. 1. A method for blending fuel oil base stocks to prepare a fuel composition for a spark ignition engine, comprising: (1) The total aromatic content is 30.0% by volume or less; (2) The content of oxygen-containing compounds is 0.10% by volume or less; (3) A compound represented by the following formula (I): V=0.82(P4+0.70×O4)+0.70(P5+0.70×O5)+0.56(P6+0.70×O6)+0.48(P7+0.70×O7)+0.48(P8+0.70×O8) (I) (wherein P4 to P8 each indicate the content ratio (volume %) of linear saturated hydrocarbons having 4 to 8 carbon atoms, and O4 to O8 each indicate the content ratio (volume %) of unsaturated hydrocarbons having 4 to 8 carbon atoms), is 33.0 or more and 45.0 or less, (4) Research method octane number of 96 or more 2. A method for blending a fuel oil base stock, comprising the steps of: obtaining a fuel composition for spark ignition engines comprising:

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