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(11) | EP 1 619 232 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
| published in accordance with Art. 158(3) EPC |
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| (54) | GAS OIL COMPOSITION AND PROCESS FOR PRODUCING THE SAME |
| (57) A gas oil composition comprising 20 % by volume or greater of a deep hydrotreated
gas oil having a 90% distillation temperature of 200-380°C, a density of 780-870 kg/m3 at 15°C, a sulfur content of 5 ppm by mass or less, an aromatic content of 10 % by
volume or less and a naphthene content of 30 % by volume or greater, the hydrotreated
gas oil being obtained by subjecting a hydrotreated oil having a sulfur content of
5-10 ppm by mass and a boiling point range of 150-380°C to further hydrogenation in
the presence of a hydrogenation catalyst, the gas oil composition having a sulfur
content of 5 ppm by mass or less, an aromatic content of 10 % by volume or less, a
bicyclic or greater aromatic content of I % by volume or less, a naphthene content
of 30 % by volume or greater, a density of 820-840 kg/m3 at 15°C, a 10% distillation temperature of 250°C or lower and a 90% distillation
temperature of 320°C or lower. |
Technical Field
[0001] The present invention relates to a gas oil composition and to a method for production thereof.
Background Art
[0002] Straight-run gas oil or straight-run kerosene which is obtained by low-pressure distillation of crude oil and subjected to hydrotreating and hydrodesulfurization is conventionally known as a base stock for gas oil. For conventional gas oil, one or more such base stocks are used, in combination with a cetane number improver or a detergent as necessary (see, for example, "Nenryo Kogaku Gairon" [Introduction to Fuel Engineering], Onishi, S., Shokabo, March 1991, pp. 136-144).
Disclosure of the Invention
[0003] Improvement in the properties of gas oil, a type of fuel for internal combustion engines, has been desirable in recent years in consideration of reducing environmental problems. More specifically, from the standpoint of alleviating the environmental load, a demand has emerged for reduced sulfur contents and aromatic component contents of gas oil used as a fuel for internal combustion engines, and against the background of the problem of global house effect there is an increasing demand for fuel properties which can contribute to further improvement of fuel efficiency.
[0004] For alleviation of the environmental load, it is preferred to introduce dearomatizing treatment in the gas oil base production process in order to reduce the aromatic components (at most about 40 % by volume, with an average of about 20 % by volume) in gas oil bases. However, it is not always easy to adequately reduce the aromatic components with existing equipment such as hydrotreatment apparatuses or hydrodesulfurization treatment apparatuses, and efforts to obtain desired gas oil bases lead to notable increase in refining costs.
[0005] Because of the low aromatic content of kerosene bases in comparison to gas oil bases (at most about 30 % by volume, with an average of about 15 % by volume), it is possible in most cases to reduce the aromatic content to some degree by combining a kerosene base with a gas oil base. However, gas oil compositions obtained in such a way have low density and are extremely light, and these properties can lead to decreased fuel efficiency and power. In addition, such gas oil compositions also have low viscosity and therefore cannot be considered suitable in terms of lubricity for fuel injection pumps and the like.
[0006] On the other hand, some base oil stocks contain virtually no aromatic components, such as certain synthetic gas oils and synthetic kerosenes used as raw stocks for natural gas, asphalt, coal and the like. Nevertheless, because such base oil stocks are composed mainly of paraffins, there are concerns regarding waxy precipitation during low temperature start-up when they are used. Also, from the viewpoint of effects on parts used in fuel injection systems, it is considered preferable for gas oil to contain some level of aromatic components. Consequently, restrictions are sometimes placed on the mixing proportions for combining synthetic gas oils and/or synthetic kerosenes with other base oil stocks.
[0007] Base oil stocks composed of compounds with oxygen atoms in the molecule (oxygenated base oils) are also associated with problems similar to those of synthetic gas oils. In addition, oxygen-containing base oils have been implicated in problems relating to emission of aldehydes as combustion by-products and produce effects on the material parts of engines.
[0008] In light of the advantages and disadvantages of conventional gas oil bases, it has been extremely difficult to use such bases to design gas oils capable of both reducing environmental load and improving fuel efficiency. Thus, no commercially available diesel fuel has yet been obtained which satisfactorily exhibits the required performance described above, nor has adequate research been conducted on methods for its production.
[0009] The present invention has been accomplished in light of these circumstances, and its object is to provide a gas oil composition which is able to achieve a high level of and satisfactory balance between environmental load reduction and fuel efficiency improvement when used as a diesel fuel, as well as a method for production thereof.
[0010] In order to overcome the problems described above, the gas oil composition of the invention is characterized by comprising 20 % by volume or greater of a deep hydrotreated gas oil having a 90% distillation temperature of 200-380°C, a density of 780-870 kg/m3 at 15°C, a sulfur content of 5 ppm by mass or less, an aromatic content of 10 % by volume or less and a naphthene content of 30 % by volume or greater, the deep hydrotreated gas oil being obtained by subjecting a hydrotreated oil having a sulfur content of 5-10 ppm by mass and a boiling point range of 150-380°C to further hydrogenation in the presence of a hydrogenation catalyst; and the gas oil composition being further characterized by having a sulfur content of 5 ppm by mass or less, an aromatic content of 10 % by volume or less, a bicyclic or greater aromatic content of 1 % by volume or less, a naphthene content of 30 % by volume or greater, a density of 820-840 kg/m3 at 15°C, a 10% distillation temperature of 250°C or lower, and a 90% distillation temperature of 320°C or lower.
[0011] Using the aforementioned specific deep hydrotreated gas oil (hereinafter referred to simply as "deep hydrotreated gas oil") according to the invention, it is possible to easily and reliably control the sulfur content, aromatic content, naphthene content, density and distillation properties of the gas oil composition as a whole. Furthermore, by adding the deep hydrotreated gas oil to a gas oil composition at 20 % by volume or greater, and limiting the sulfur content, aromatic content, bicyclic or greater aromatic content, naphthene content, density at 15° C , 10% distillation temperature and 90% distillation temperature of the gas oil composition to the ranges specified above, a gas oil composition is realized which satisfies the required properties as a future-type diesel fuel and achieves a high level of and satisfactory balance between environmental load reduction and fuel efficiency improvement.
[0012] Preferably, the gas oil composition of the invention further comprises at least one selected from a hydrocracked gas oil, a hydrocracked kerosene, a hydrotreated kerosene, a synthetic gas oil and a synthetic kerosene.
[0013] The gas oil composition of the invention also preferably has an end point of 350°C or lower, a cetane number of 55 or greater, a cetane index of 52 or greater, a kinematic viscosity of 2-4 mm2/s at 40°C, an HFRR wear scar diameter of 400 µm or less and a flow point of -7.5°C or lower.
[0014] The method for production of the gas oil composition of the invention is characterized by comprising a first step of subjecting a hydrotreated oil having a sulfur content of 5-10 ppm by mass and a boiling point range of 150-380°C to further hydrogenation in the presence of a hydrogenation catalyst, to obtain a deep hydrotreated gas oil having a 90% distillation temperature of 200-380°C, a density of 780-870 kg/m3 at 15°C, a sulfur content of 5 ppm by mass or less, an aromatic content of 10 % by volume or less and a naphthene content of 30 % by volume or greater, and
a second step of mixing the deep hydrotreated gas oil with at least one selected from a hydrocracked gas oil, a hydrocracked kerosene, a hydrotreated kerosene, a synthetic gas oil and a synthetic kerosene, to obtain a gas oil composition comprising 20 % by volume or greater of the deep hydrotreated gas oil and having a sulfur content of 5 ppm by mass or less, an aromatic content of 10 % by volume or less, a bicyclic or greater aromatic content of 1 % by volume or less, a naphthene content of 30 % by volume or greater, a density of 820-840 kg/m3 at 15°C, a 10% distillation temperature of 250°C or lower, and a 90% distillation temperature of 320°C or lower.
[0015] According to the method for production described above, the aforementioned specific deep hydrotreated gas oil is used, and the aforementioned specific base oil is mixed with the deep hydrotreated gas oil, in order to easily and reliably obtain a gas oil composition according to the invention wherein the deep hydrotreated gas oil content, as well as the sulfur content, aromatic content, bicyclic or greater aromatic content, naphthene content, density at 15° C , 10% distillation temperature and 90% distillation temperature of the gas oil composition, are in the ranges specified above.
[0016] In the method for production of a gas oil composition according to the invention, the gas oil composition obtained in the second step preferably has an end point of 350°C or lower, a cetane number of 55 or greater, a cetane index of 52 or greater, a kinematic viscosity of 2-4 mm2/s at 40°C, an HFRR wear scar diameter of 400 µm or less and a flow point of -7.5°C or lower.
Brief Description of the Drawings
[0017] Fig. 1 is a schematic diagram showing a scanning mobility particle size analyzer used for the examples. Best Mode for Carrying Out the Invention
[0019] As mentioned above, the gas oil composition of the invention is characterized by comprising 20 % by volume or greater of a deep hydrotreated gas oil having a 90% distillation temperature of 200-380°C, a density of 780-870 kg/m3 at 15°C, a sulfur content of 5 ppm by mass or less, an aromatic content of 10 % by volume or less and a naphthene content of 30 % by volume or greater, and the gas oil composition being further characterized by having a sulfur content of 5 ppm by mass or less, an aromatic content of 10 % by volume or less, a bicyclic or greater aromatic content of 1 % by volume or less, a naphthene content of 30 % by volume or greater, a density of 820-840 kg/m3 at 15°C, a 10% distillation temperature of 250°C or lower, and a 90% distillation temperature of 320°C or lower. The deep hydrotreated gas oil is obtained by subjecting a hydrotreated oil having a sulfur content of 5-10 ppm by mass and a boiling point range of 150-380°C to further hydrogenation in the presence of a hydrogenation catalyst.
[0020] The hydrotreated oil used for production of the deep hydrotreated gas oil is not particularly restricted so long as it is a hydrotreated oil consisting of petroleum-based hydrocarbons with the sulfur content and boiling point in the ranges specified above, and a prescribed crude oil treated by hydrotreatment and/or hydrodesulfurization may be used. Examples of the crude oil for the hydrotreated oil include a straight-run gas oil obtained from an atmospheric pressure distillation apparatus, a straight-run heavy oil obtained from an atmospheric pressure distillation apparatus or a vacuum pressure gas oil obtained by treatment of a residual oil with a vacuum pressure distillation apparatus, a catalytic cracked gas oil and a hydrotreated gas oil obtained by catalytic cracking or hydrotreatment of vacuum pressure heavy gas oil or desulfurized heavy oil, or a hydrotreated gas oil or a hydrodesulfurized gas oil obtained by hydrotreatment of petroleum-based hydrocarbons.
[0021] The hydrotreatment conditions for the crude oil are not particularly restricted so long as the resulting hydrotreated oil has a 90% distillation temperature, density at 15° C , and sulfur, aromatic and naphthene contents in the respective ranges specified above, but preferably the hydrotreatment is carried out with a treatment temperature of 300-380°C, a hydrogen pressure of 3-8 MPa, an LHSV of 0.3-2 h-1 and a hydrogen/oil ratio of 100-500 NL/L. The catalyst used for the hydrotreatment may be an ordinary hydrodesulfurization catalyst. As active metal species for hydrodesulfurization catalysts there are commonly used sulfides of Group 6A and Group 8 metals (Co-Mo, Ni-Mo, Co-W, Ni-W), and porous inorganic oxides composed mainly of alumina are used as supports.
[0022] A deep hydrotreated gas oil according to the invention can be obtained by further hydrogenation of the aforementioned hydrotreated oil in the presence of a hydrogenation catalyst.
[0023] There are no particular restrictions on the construction of the apparatus used for the hydrogenation, and it may consist of a single reactor or a combination of different reactors. In the case of an apparatus comprising a plurality of reactors, additional hydrogen may be injected between adjacent reactors. The hydrogenation apparatus may also be provided with devices for a gas-liquid separation procedure and hydrogen sulfide removal procedure.
[0024] The reaction system of the hydrogenation apparatus is preferably a fixed-bed system. The hydrogen flow system may be in cocurrent or countercurrent with the hydrotreated oil. In the case of an apparatus provided with a plurality of reactors, a combination of cocurrent and countercurrent may be employed. An ordinary flow system is a gas-liquid tricle flow system. Hydrogen gas may also be injected at an intermediate level of the reactor as quench gas, for the purpose of reaction heat removal or hydrogen partial pressure increase.
[0025] The hydrogenation conditions are not particularly restricted so long as the resulting deep hydrotreated gas oil has a density at 15° C , and sulfur, aromatic and naphthene contents in the respective ranges specified above, but the reaction temperature is preferably 170-320°C, more preferably 175-300°C and even more preferably 180-280°C. The hydrogen pressure is preferably 2-10 MPa, more preferably 2.5-8 MPa and even more preferably 3-7 MPa. The LHSV is preferably 0.1-2 h-1, more preferably 0.2-1.5 h-1 and even more preferably 0.3-1.2 h-1. The hydrogen/oil ratio is preferably 100-800 NL/L, more preferably 150-600 NL/L and even more preferably 150-500 NL/L. Although a lower reaction temperature is advantageous for the hydrogenation reaction, it is not desirable for the desulfurization reaction. Also, while a higher hydrogen pressure and hydrogen/oil ratio will promote both the hydrogenation reaction and desulfurization reaction, an unfavorable situation in terms of economy will result if they are excessively high. A lower LHSV is advantageous for the reaction but an excessively low LHSV will require a very large reactor volume and is not preferred from the standpoint of equipment cost.
[0026] As examples of hydrogenation catalysts to be used for the hydrogenation there may be mentioned hydrogenation active metals supported in porous supports. Porous inorganic oxides may be used as porous supports for the hydrogenation catalyst, and specifically there may be mentioned alumina, titania, zirconia, boria, silica, zeolite and the like. These porous supports may be used alone or in combinations of two or more, but are preferably constructed from alumina and at least one from titania, zirconia, boria, silica and zeolite. The method for production of the porous support is not particularly restricted, and for example, it may be prepared by any preparation method using a raw material in the state of a sol or salt compound corresponding to the constituent element of the porous support. Alternatively, a complex hydroxide or complex oxide such as silica-alumina, silica-zirconia, alumina-titania, silica-titania or alumina-boria may be prepared first, and then alumina gel or another hydroxide added thereto either directly or in the form of an appropriate solution, to prepare a porous support. The alumina or other oxide may be present in any desired proportion in the porous support, but the alumina proportion is preferably 90% or less, more preferably 60% or less and even more preferably 40% or less.
[0027] Zeolite is a crystalline aluminosilicate. As more specific zeolites there may be mentioned faujasite, pentasil and mordenite, among which faujasite and mordenite are preferred, and Y-types and beta-types are especially preferred. These zeolites may be used after ultrastabilization by a prescribed hydrothermal treatment and/or acid treatment, or after adjustment of the alumina content of the zeolite. Ultrastabilization is particularly preferred when using Y-zeolite. Zeolite which has been ultrastabilized by hydrothermal treatment has newly formed fine pores in the range of 20-100 A in addition to its inherent fine porous structure (micropores) of 20 A or smaller. The hydrothermal treatment conditions applied may be conditions which are publicly known.
[0028] The active metal of the hydrogenation catalyst is preferably at least one metal selected from Group 8 metals, more preferably at least one selected from Ru, Rd, Ir, Pd and Pt, and even more preferably Pd and/or Pt. The active metal used may be of a single species, or a combination of two or more species. As combinations of active metals there may be mentioned Pt-Pd, Pt-Rh, Pt-Ru, Ir-Pd, Ir-Rh, Ir-Ru, Pt-Pd-Rh, Pt-Rh-Ru, Ir-Pd-Rh and Ir-Rh-Ru. As metal sources there may be used ordinary inorganic salts and chelated salt compounds. There are no particular restrictions on the loading amount of the active metal, but the total amount of metals with respect to the total hydrogenation catalyst is preferably 0.1-10 % by mass, more preferably 0.15-5 % by mass and even more preferably 0.2-3 % by mass.
[0029] The method of loading the active metal into the porous support may be any loading method ordinarily used with hydrogenation catalysts, such as impregnation or ion-exchange methods. For loading of different metals, a mixed solution may be used for simultaneous loading, or simple solutions may be used for successive loading. The metal solution may be in the form of an aqueous solution or an organic solvent solution. The loading of the active metal onto the porous support may be carried out after completion of the entire preparation step for the porous support, or alternatively the active metal may be loaded onto an appropriate oxide, compound oxide or zeolite in an intermediate step of the porous support preparation, and this loading followed by steps such as gel preparation, thermocompression, kneading and the like.
[0030] The hydrogenation catalyst is preferably supplied for hydrogenation after pre-reduction under hydrogen stream. For example, by heating at 200°C or above according to a prescribed procedure while circulating a hydrogen-containing gas, it is possible to adequately reduce the active metal on the catalyst and achieve a high level of hydrogenation activity.
[0031] The 90% distillation temperature (hereinafter also referred to as "T90") of the deep hydrotreated gas oil of the invention obtained by the hydrogenation described above must be 200°C or higher, as mentioned above, in order to prevent an adverse effect on the driveability by excessive lightness of the distillation property, and this temperature is preferably 210°C or higher, more preferably 220°C or higher, even more preferably 230°C or higher and most preferably 240°C or higher. As also mentioned above, T90 must be 380°C or lower in order to prevent increase in particulate matter (PM) emitted from the engine, and it is preferably 370°C or lower, more preferably 360°C or lower, even more preferably 350°C or lower and most preferably 340°C or lower. The 90% distillation temperature (T90) referred to here is the value measured according to JIS K 2254, "Petroleum Product-Distillation Test Method".
[0032] The density at 15°C of the deep hydrotreated gas oil of the invention must be, as mentioned above, 780 kg/m3 or greater from the standpoint of guaranteeing the heat value, and it is preferably 790 kg/m3 or greater and more preferably 800 kg/m3 or greater. As also mentioned above, this density must be 870 kg/m3 or less from the standpoint of reducing NOx and PM emissions, and it is preferably 860 kg/m3 or less, more preferably 850 kg/m3 or less and even more preferably 840 kg/m3 or less. The density referred to here is the density measured according to JIS K 2249, "Crude Oil and Petroleum Product Density Test Method and Density/Mass/Volume Conversion Table".
[0033] The sulfur content of the deep hydrotreated gas oil of the invention must be, as mentioned above, 5 ppm by mass or less from the standpoint of reducing noxious exhaust components emitted from engines and improving performance of exhaust gas after treatment system, and it is preferably 3 ppm by mass or less, more preferably 2 ppm by mass or less and even more preferably 1 ppm by mass or less. The sulfur content referred to here is the sulfur content by mass based on the total amount of the gas oil composition, as measured according to JIS K 2541, "Sulfur Content Test Method".
[0034] The naphthene content of the deep hydrotreated gas oil of the invention must be, as mentioned above, 30 % by volume or greater, and it is preferably 32 % by volume or greater and more preferably 35 % by volume or greater. By limiting the naphthene content of the deep hydrotreated gas oil in this manner it is possible to easily and reliably achieve the properties specified for the gas oil composition of the invention. The naphthene content referred to here is the volume percentage (% by volume) of naphthene as measured according to ASTM D2786, "Standard Test Method for Hydrocarbon Types - Analysis of Gas-Oil Saturates Fractions by High Ionizing Mass Spectrometry".
[0035] The aromatic content of the deep hydrotreated gas oil of the invention must be, as mentioned above, 10 % by volume or less, and it is preferably 8 % by volume or less and more preferably 5 % by volume or less. By limiting the aromatic content of the deep hydrotreated gas oil in this manner it is possible to easily and reliably achieve the properties specified for the gas oil composition of the invention. The aromatic content referred to here is the volume percentage (% by volume) of aromatic components as measured according to JPI-5S-49-97, "Test Method for Hydrogen Types - High-Performance Liquid Chromatography", in Index on Testing Method for Petroleum Products published by The Japan Petroleum Institute.
[0036] By using a deep hydrotreated gas oil having the construction described above, it is possible to easily and reliably control the sulfur content, aromatic content and density of the gas oil composition as a whole, and to efficiently and reliably obtain a gas oil composition according to the invention.
[0037] The gas oil composition of the invention may consist of only a deep hydrotreated gas oil according to the invention so long as the sulfur content, aromatic content, bicyclic or greater aromatic content, naphthene content, density at 15 ° C, 10% distillation temperature and 90% distillation temperature of the composition are in the ranges specified above, or it may further contain components other than the deep hydrotreated gas oil; however, the content of the deep hydrotreated gas oil must be 20 % by volume or greater. If the composition does not contain a deep hydrotreated gas oil or the deep hydrotreated gas oil content is less than 20 % by volume, it will not be possible to simultaneously achieve environmental load reduction and fuel efficiency improvement. For the same reason, the content of the deep hydrotreated gas oil according to the invention is preferably 30 % by volume or greater, more preferably 40 % by volume or greater and even more preferably 50 % by volume or greater.
[0038] The sulfur content of the gas oil composition of the invention must be, as mentioned above, 5 ppm by mass or less, and it is preferably 3 ppm by mass or less, more preferably 2 ppm by mass or less and even more preferably 1 ppm by mass or less. If the sulfur content exceeds 5 ppm by mass, the effect of environmental load reduction is inadequate. The sulfur content referred to here is the sulfur content by mass based on the total amount of the gas oil composition, as measured according to JIS K 2541, "Sulfur Content Test Method".
[0039] The aromatic content of the gas oil composition of the invention must be, as mentioned above, 10 % by volume or less from the standpoint of environmental load reduction, and it is preferably 8 % by volume or less and even more preferably 5 % by volume or less.
[0040] The bicyclic or greater aromatic content among the aromatic components must be 1 % by volume or less, and it is preferably 0.8 % by volume or less and more preferably 0.5 % by volume or less. If the aromatic content or the bicyclic or greater aromatic content exceeds these respective upper limits, the NOx and PM emissions in exhaust gas will increase, and the effect of environmental load reduction will be inadequate. The aromatic content and bicyclic or greater aromatic content referred to here are the volume percentages (% by volume) of the aromatic content and bicyclic or greater aromatic content as measured according to JPI-5S-49-97, "Test Method for Hydrogen Types - High-Performance Liquid Chromatography", in Index on Testing Method for Petroleum Products published by The Japan Petroleum Institute.
[0041] The naphthene content of the gas oil composition of the invention must be, as mentioned above, 30 % by volume or greater from the standpoint of improving fuel efficiency and power, and it is preferably 32 % by volume or greater and more preferably 35 % by volume or greater. The naphthene content referred to here is the volume percentage (% by volume) of naphthene as measured according to ASTM D2786, "Standard Test Method for Hydrocarbon Types - Analysis of Gas-Oil Saturates Fractions by High Ionizing Mass Spectrometry".
[0042] The density at 15° C of the gas oil composition of the invention must be, as mentioned above, 820 kg/m3 or higher from the standpoint of fuel efficiency and accelerating property, and it is preferably 822 kg/m3 or higher and more preferably 825 kg/m3 or higher. Also, this density must be 840 kg/m3 or lower from the standpoint of lowering the PM concentration in exhaust gas, while it is preferably 837 kg/m3 or lower and more preferably 835 kg/m3 or lower. The density referred to here is the density measured according to JIS K 2249, "Crude Oil and Petroleum Product Density Test Method and Density/Mass/Volume Conversion Table".
[0043] In the gas oil composition of the invention, the 10% distillation temperature, as a distillation property, must be 250°C or lower, and it is preferably 240°C or lower, more preferably 230°C or lower, even more preferably 225°C or lower and most preferably 220°C or lower. If the 10% distillation temperature exceeds the upper limits, the exhaust gas performance will be impaired. The 10% distillation temperature is also preferably 160°C or higher, more preferably 170°C or higher and even more preferably 180°C or higher. If the 10% distillation temperature is lower than the lower limits, the engine power and high-temperature startability will be inferior.
[0044] The 90% distillation temperature of the gas oil composition of the invention must be 320°C or lower, and it is preferably 317°C or lower, more preferably 315°C or lower, even more preferably 312°C or lower and most preferably 310°C or lower. If the 90% distillation temperature exceeds the upper limits, PM and fine particle emissions will tend to increase. The 90% distillation temperature is also preferably 270°C or higher, more preferably 275°C or higher and even more preferably 280°C or higher.
[0045] The other distillation properties of the gas oil composition of the invention are not particularly restricted so long as the 10% distillation temperature and 90% distillation temperature are within the ranges specified above, but the 50% distillation temperature is preferably 310°C or lower, more preferably 300°C or lower, even more preferably 295°C or lower and most preferably 290°C or lower. If the 50% distillation temperature exceeds the upper limits, the exhaust gas performance will tend to be inferior. The 50% distillation temperature is also preferably 240°C or higher, more preferably 245°C or higher, even more preferably 250°C or higher, particularly preferably 255°C or higher and most preferably 260°C or higher. If the 50% distillation temperature is lower than the lower limits, the engine power and high-temperature startability will tend to be inferior.
[0046] The 95% distillation temperature of the gas oil composition of the invention is preferably 290°C or higher and more preferably 295°C or higher. The end point of the gas oil composition of the invention is preferably 300°C or higher and more preferably 305°C or higher. If the 95% distillation temperature and end point are lower than their respective lower limits, the effect of improved fuel efficiency will be inadequate and the engine power will tend to be lower. Also, the 95% distillation temperature is preferably 340°C or lower, more preferably 335°C or lower and even more preferably 330°C or lower. The end point is preferably 350°C or lower, more preferably 345°C or lower and even more preferably 340°C or lower. If the 95% distillation temperature and end point exceed their respective upper limits, the PM and fine particle emissions will tend to increase.
[0047] The 10% distillation temperature, 50% distillation temperature, 90% distillation temperature, 95% distillation temperature and end point referred to here are all values measured according to JIS K 2254, "Petroleum Product - Distillation Test Method".
[0048] The cetane number of the gas oil composition of the invention is preferably 55 or greater and more preferably 57 or greater from the viewpoint of lowering the concentrations of NOx, PM and aldehydes in the exhaust gas. The cetane number referred to here is the cetane number measured according to "7. Cetane Number Test Method" of JIS K 2280, "Petroleum Product-Fuel Oil-Octane Number and Cetane Number Test Methods and Cetane Index Calculation Method".
[0049] The cetane index of the gas oil composition of the invention is preferably 52 or greater, more preferably 53 or greater and even more preferably 55 or greater from the viewpoint of minimizing the concentrations of NOx, PM and aldehydes in the exhaust gas. The cetane index referred to here is the value calculated according to "8.4 Cetane Index Calculation Method By Variable Equation" of JIS K 2280, "Petroleum Product-Fuel Oil - Octane Number and Cetane Number Test Methods and Cetane Index Calculation Method". The cetane index according to this JIS standard is usually not applied for compositions containing added cetane number improvers, but the gas oil composition of the invention may include a cetane number improver as explained hereunder, and the "8.4 Cetane Index Calculation Method By Variable Equation" is applied even for such cases where the gas oil composition includes an added cetane number improver, with the value calculated by this calculation method being expressed as the cetane index.
[0050] The kinematic viscosity at 40°C of the gas oil composition of the invention is preferably 2 mm2/s or greater, more preferably 2.2 mm2/s or greater and even more preferably 2.4 mm2/s or greater. If the kinematic viscosity is less than 2 mm2/s, it will tend to be difficult to achieve control of the fuel injection timing, and the lubricity of the fuel injection pump parts may be impaired. The kinematic viscosity at 40°C is also preferably 4 mm2/s or less, more preferably 3.8 mm2/s or less and even more preferably 3.6 mm2/s or less. If the kinematic viscosity exceeds 4 mm2/s, increased friction in the injection system inside will tend to destabilize the injection characteristics and result in increased concentrations of NOx and PM in the exhaust gas. The kinematic viscosity referred to here is the kinematic viscosity measured according to JIS K 2283, "Crude Oil and Petroleum Product - Kinematic Viscosity Test Method and Viscosity Index Calculation Method".
[0051] The lubricity of the gas oil composition of the invention may be expressed based on the index of HFRR wear scar diameter (WS1.4). The HFRR wear scar diameter of the gas oil composition of the invention is preferably 400 µm or less, more preferably 390 µm or less and even more preferably 380 µm or less. An HFRR wear scar diameter of greater than 400 µm may produce increased driving torque of the pump during operation and increased wear of pump parts, particularly in diesel engines with equipped distributor-type injection pumps, thus potentially leading not only to poor exhaust gas performance and fine particle performance, but even breakdown of the engine itself. Friction with sliding surfaces and the like is still a concern even with electronically-controlled fuel injection pumps capable of high-pressure injection. The HFRR wear scar diameter referred to here is the value measured according to JPI-5S-50-98, "Gas oil - Lubricity Test Method" of the Japan Petroleum Institute Standards published by The Japan Petroleum Institute.
[0052] From the viewpoint of low-temperature startability and low-temperature driveability, as well as keeping condition of injection performance for electronically-controlled fuel injection pumps, the flow point of the gas oil composition of the invention is preferably - 7.5°C or lower, more preferably -15°C or lower and even more preferably -20°C or lower. The flow point referred to here is the flow point as measured according to JIS K 2269, "Crude Oil and Petroleum Product Flow Point and Petroleum Product Clouding Point Test Methods".
[0053] The ash content of the gas oil composition of the invention is preferably less than 0.01 % by mass. If the ash content is 0.01 % by mass or greater, the ash will become a sludge in fuel injection systems, thus potentially hampering performance. The ash content referred to here is the content of ash by mass based on the total amount of the gas oil composition, as measured according to JIS K 2272, "Crude Oil and Petroleum Product Ash and Sulfated Ash Content Test Method".
[0054] The cold filter plugging point of the gas oil composition of the invention is not particularly restricted, but it is preferably -5°C or lower, more preferably -8°C or lower, even more preferably -12°C or lower and still more preferably -19°C or lower. The cold filter plugging point referred to here is the cold filter plugging point measured according to JIS K 2288, "Gas oil - Cold Filter Plugging Point Test Method".
[0055] From the standpoint of storage stability, the gas oil composition of the invention has, after oxidation stability testing, a total insoluble portion of preferably 2.0 mg/100 mL or less, more preferably 1.0 mg/100 mL or less, even more preferably 0.5 mg/100 mL or less, still more preferably 0.3 mg/100 mL or less and most preferably 0.1 mg/100 mL or less. The oxidation stability testing referred to here is carried out according to ASTM D2274-94, at 95°C for 16 hours with oxygen bubbling. The total insoluble portion after oxidation stability testing is the value measured according to the aforementioned oxidation stability testing.
[0056] From the standpoint of storage stability and compatibility with engine materials, the gas oil composition of the invention has, after the aforementioned oxidation stability testing, a peroxide number of preferably 10 ppm by mass or less, more preferably 5 ppm by mass or less, even more preferably 2 ppm by mass or less and most preferably 1 ppm by mass or less. The peroxide number referred to here is the value measured according to Japan Petroleum Institute Standard JPI-5S-46-96.
[0057] In order to reduce the total insoluble portion and peroxide number of the gas oil composition of the invention, additives such as the antioxidants or metal deactivators described hereunder may be added in appropriate amounts.
[0058] The conductivity of the gas oil composition of the invention is not particularly restricted, but it is preferably 50 pS/m or greater from the standpoint of safety. The conductivity referred to here is the value measured according to JIS K 2276, "Petroleum Product - Aircraft Fuel Oil Test Method". An appropriate amount of an antistatic agent or the like, described hereunder, may also be added to the gas oil composition of the invention to improve the conductivity.
[0059] According to the invention, a gas oil base other than the aforementioned deep hydrotreated gas oil may be added so long as the sulfur content, aromatic content, bicyclic or greater aromatic content, naphthene content, density at 15° C , 10% distillation temperature and 90% distillation temperature of the obtained gas oil composition are within the respective ranges specified above. Specifically, there may be used: straight-run gas oil obtained from a crude oil atmospheric pressure distillation apparatus, straight-run heavy oil obtained from an atmospheric pressure distillation apparatus, or vacuum pressure gas oil obtained by treatment of residual oil with a reduced-pressure distillation apparatus; hydrotreated gas oil obtained by hydrotreatment of the aforementioned gas oils with a hydrotreatment apparatus depending on the sulfur content; hydrodesulfurized gas oil obtained by hydrodesulfurization in one or more stages under more stringent conditions than hydrotreatment; or hydrocracked gas oil obtained by hydrocracking of any of the aforementioned gas oil bases. Throughout the following explanation, these gas oil bases will be referred to as "additional gas oil bases".
[0060] Although there are no particular restrictions on the properties of the additional gas oil bases, they preferably have the following specific properties in order to easily and reliably achieve the properties which are intended for the gas oil composition of the invention.
[0061] Specifically, the T90 of the additional gas oil bases is preferably 200°C or higher, more preferably 210°C or higher, even more preferably 220°C or higher, still more preferably 230°C or higher and most preferably 240°C or higher. The T90 is also preferably 380°C or lower, more preferably 370°C or lower, even more preferably 360°C or lower, still more preferably 350°C or lower and most preferably 340°C or lower.
[0062] The density at 15° C of the additional gas oil bases is preferably 780 kg/m3 or greater, more preferably 790 kg/m3 or greater and even more preferably 800 kg/m3 or greater. The density is also preferably 870 kg/m3 or less, more preferably 860 kg/m3 or less, even more preferably 850 kg/m3 or less and still more preferably 840 kg/m3 or less.
[0063] The sulfur content of the additional gas oil bases is preferably 10 ppm by mass or less, more preferably 5 ppm by mass or less and more preferably 3 ppm by mass or less.
[0064] The aromatic content of the above gas oil bases is not particularly restricted but is preferably 20 % by volume or less, more preferably 15 % by volume or less and even more preferably 10 % by volume or less.
[0065] The amount of additional gas oil bases added to the gas oil composition of the invention may be appropriately set according to the actual desired performance as a commercially available fuel oil (for example, low temperature flow property or lubricity), as long as the content of the deep hydrotreated gas oil is 20 % by volume or greater and the gas oil composition has a sulfur content, aromatic content, bicyclic or greater aromatic content, naphthene content, density at 15° C, 10% distillation temperature and 90% distillation temperature in the respective ranges specified above. In order to further increase both the environment load-alleviating effect and fuel efficiency enhancing effect, the content of such gas oil bases is preferably 5 % by volume or greater, more preferably 10 % by volume or greater and even more preferably 15 % by volume or greater. Also, the content is preferably 80 % by volume or less, more preferably 70 % by volume or less and even more preferably 60 % by volume or less.
[0066] According to the invention, synthetic gas oils may also be combined with the gas oil composition, so long as the content of the deep hydrotreated gas oil, as well as the sulfur content, aromatic content, bicyclic or greater aromatic content, naphthene content, density at 15° C , 10% distillation temperature and 90% distillation temperature of the gas oil composition are in the respective ranges specified above.
[0067] A synthetic gas oil according to the invention is a synthetic gas oil obtained by chemical synthesis from a raw material such as natural gas, asphalt or coal. The chemical synthesis method may be indirect liquefaction or direct liquefaction, and the Fisher-Tropsch method may be mentioned as a typical method for synthesis; however, a synthetic gas oil used for the invention is not limited to one obtained by such production processes. Synthetic gas oils are generally composed mainly of saturated hydrocarbons, and specifically n-paraffins, iso-paraffins and naphthenes. In other words, synthetic gas oils typically contain virtually no aromatic components.
[0068] A synthetic gas oil used preferably has the following specific properties in order to easily and reliably achieve the properties which are intended for the gas oil composition of the invention.
[0069] Specifically, the density at 15° C of the synthetic gas oil is preferably 720 kg/m3 or greater, more preferably 730 kg/m3 or greater, even more preferably 740 kg/m3 or greater and still more preferably 750 kg/m3 or greater. The density is also preferably 840 kg/m3 or less, more preferably 830 kg/m3 or less, even more preferably 820 kg/m3 or less and still more preferably 810 kg/m3 or less.
[0070] The sulfur content of the synthetic gas oil is preferably 5 ppm by mass or less, more preferably 3 ppm by mass or less, even more preferably 2 ppm by mass or less and still more preferably 1 ppm by mass or less.
[0071] The amount of synthetic gas oil added according to the invention may be appropriately set according to the actual desired performance as a commercially available fuel oil (for example, low temperature flow property or lubricity), as long as the content of the deep hydrotreated gas oil, and the sulfur content, aromatic content, bicyclic or greater aromatic content, naphthene content, density at 15° C , 10% distillation temperature and 90% distillation temperature of the gas oil composition are in the respective ranges specified above. In order to further increase both the environment load-alleviating effect and fuel efficiency enhancing effect, the synthetic gas oil content is preferably 2 % by volume or greater and more preferably 5 % by volume or greater. Also, the content is preferably 30 % by volume or less, more preferably 20 % by volume or less and even more preferably 10 % by volume or less.
[0072] According to the invention, kerosene bases may also be added to the composition as long as the content of the deep hydrotreated gas oil, and the sulfur content, aromatic content, bicyclic or greater aromatic content, naphthene content, density at 15° C , 10% distillation temperature and 90% distillation temperature of the gas oil composition are in the respective ranges specified above.
[0073] As such kerosene bases there may be used straight-run kerosene obtained by atmospheric pressure distillation of crude oil; cracked kerosene obtained by cracking of diesel fractions obtained by atmospheric pressure distillation of straight-run crude oil; hydrocracked kerosene produced along with hydrocracked gas oil; hydrotreated kerosene obtained by hydrotreatment of the aforementioned kerosene fractions; as well as synthetic kerosenes obtained from natural gas, asphalt, coal or the like as raw materials.
[0074] As kerosene bases there also may be used deep hydrotreated kerosene subjected to high-level hydrotreatment in order to completely minimize the sulfur content or aromatic content.
[0075] There are no particular restrictions on the properties of these kerosene bases used, but they preferably have the following specific properties in order to easily and reliably achieve the properties which are intended for the gas oil composition of the invention.
[0076] Specifically, the T90 of a kerosene base used is preferably at least 140°C, more preferably 145°C or higher and even more preferably 150°C or higher. The T90 is also preferably 280°C or lower, more preferably 270°C or lower and even more preferably 260°C or lower.
[0077] The density at 15° C of a kerosene base used is preferably 750 kg/m3 or greater, more preferably 760 kg/m3 or greater and even more preferably 770 kg/m3 or greater. The density is also preferably 820 kg/m3 or less, more preferably 810 kg/m3 or less and even more preferably 800 kg/m3 or less.
[0078] The sulfur content of a kerosene base used is preferably 10 ppm by mass or less, more preferably 5 ppm by mass or less and even more preferably 3 ppm by mass or less.
[0079] There are no particular restrictions on the aromatic content of a kerosene base used, but it is preferably 30 % by volume or less, more preferably 25 % by volume or less, even more preferably 20 % by volume or less, still more preferably 15 % by volume or less and most preferably 10 % by volume or less.
[0080] The amount of a kerosene base added according to the invention may be appropriately set according to the actual desired performance as a commercially available fuel oil (for example, low temperature flow property or lubricity), as long as the content of the deep hydrotreated gas oil, as well as the sulfur content, aromatic content, bicyclic or greater aromatic content, naphthene content, density at 15° C , 10% distillation temperature and 90% distillation temperature of the gas oil composition are in the respective ranges specified above. In order to further increase both the environment load-alleviating effect and fuel efficiency enhancing effect, the content of such kerosene bases is preferably 5 % by volume or greater and more preferably 10 % by volume or greater. Also, the content is preferably 60 % by volume or less, more preferably 50 % by volume or less, even more preferably 40 % by volume or less and still more preferably 30 % by volume or less.
[0081] As explained above, the gas oil composition of the invention may contain other bases in addition to the deep hydrotreated gas oil, but gas oil compositions comprising mixtures of the deep hydrotreated gas oil with one or more selected from hydrocracked gas oil, hydrocracked kerosene, hydrotreated kerosene, synthetic gas oil and synthetic kerosene are preferred. Combination of such base oils allows more easy and reliable control of the content of the deep hydrotreated gas oil, as well as the sulfur content, aromatic content, bicyclic or greater aromatic content, naphthene content, density at 15° C , 10% distillation temperature and 90% distillation temperature of the gas oil composition.
[0082] According to the invention, a cetane number improver may also be added in an appropriate amount as necessary in order to obtain a gas oil composition with the desired cetane number.
[0083] As cetane number improvers there may be used any of various compounds known as gas oil cetane number improvers, and as examples there may be mentioned nitric acid esters and organic peroxides. These cetane number improvers may be used alone or in combinations of two or more.
[0084] According to the invention, a nitric acid ester is preferably used as the cetane number improver. Such nitric acid esters include various nitrates such as 2-chloroethyl nitrate, 2-ethoxyethyl nitrate, isopropyl nitrate, butyl nitrate, 1-amyl nitrate, 2-amyl nitrate, isoamyl nitrate, 1-hexyl nitrate, 2-hexyl nitrate, n-heptyl nitrate, n-octyl nitrate, 2-ethylhexyl nitrate, cyclohexyl nitrate, ethyleneglycol dinitrate and the like, among which C6-8 alkyl nitrates are particularly preferred.
[0085] The cetane number improver content is preferably 500 ppm by mass or greater, more preferably 600 ppm by mass or greater, even more preferably 700 ppm by mass or greater, still more preferably 800 ppm by mass or greater and most preferably 900 ppm by mass or greater, based on the total amount of the composition. If the cetane number improver content is less than 500 ppm by mass, an adequate cetane number improving effect will not be obtained, and it may not be possible to sufficiently reduce the PM, aldehydes and NOx in diesel engine exhaust gas. While there is no particular restriction on the upper limit for the cetane number improver content, it is preferably 1400 ppm by mass or less, more preferably 1250 ppm by mass or less, even more preferably 1100 ppm by mass or less and most preferably 1000 ppm by mass or less, based on the total amount of the gas oil composition.
[0086] The cetane number improver used may be one synthesized according to an ordinary method, or it may be a commercially available product. Commercially available cetane number improvers are typically purchased in a form having the active ingredient contributing to cetane number improvement (i.e., the cetane number improver itself) diluted with an appropriate solvent. When such a commercially available product is used to prepare the gas oil composition of the invention, the content of the active ingredient in the gas oil composition is preferably within the range specified above.
[0087] The gas oil composition of the invention may also contain other additives in addition to the aforementioned cetane number improver, as necessary, and it is particularly preferred to add a lubricity improver and/or a detergent.
[0088] As lubricity improvers there may be used, for example, one or more desired carboxylic acid-based, ester-based, alcohol-based and phenol-based lubricity improvers. Carboxylic acid-based and ester-based lubricity improvers are preferred among these.
[0089] As examples of carboxylic acid-based lubricity improvers there may be mentioned linoleic acid, oleic acid, salicylic acid, palmitic acid, myristic acid, hexadecenoic acid and mixtures of two or more of these carboxylic acids.
[0090] As ester-based lubricity improvers there may be mentioned carboxylic acid esters of glycerin. The carboxylic acids of carboxylic acid esters used may be of one or more types, and as specific examples there may be mentioned linoleic acid, oleic acid, salicylic acid, palmitic acid, myristic acid and hexadecenoic acid.
[0091] The amount of a lubricity improver which is added is preferably 35 ppm by mass or greater and more preferably 50 ppm by mass or greater, based on the total amount of the composition. It is possible to effectively bring out the performance of the added lubricity improver if the lubricity improver content is in this range, and for example, in diesel engines with equipped distributor-type injection pumps, it is possible to inhibit increase in the driving torque of the pump during operation, and reduce pump wear. The upper limit for the amount of addition is preferably 150 ppm by mass or less and more preferably 105 ppm by mass or less based on the total amount of the composition, since addition in greater amounts does not produce a commensurate effect.
[0092] As examples of detergents there may be mentioned ash-free detergents, including imide-based compounds; alkenylsuccinic acid imides such as polybutenylsuccinic acid imides synthesized from polybutenylsuccinic anhydride and ethylenepolyamines; succinic acid esters such as polybutenylsuccinic acid esters synthesized from polyhydric alcohols such as pentaerythritol and polybutenylsuccinic anhydride; copolymerizable polymers such as copolymers of dialkylaminoethyl methacrylate, polyethyleneglycol methacrylate or vinylpyrrolidone with alkyl methacrylates, and reaction products of carboxylic acids and amines. Preferred among these are alkenylsuccinic acid imides and reaction products of carboxylic acids and amines. Such detergents may be used alone or in combinations of two or more different types.
[0093] As examples of using alkenylsuccinic acid imides, there may be mentioned the use of a single alkenylsuccinic acid imide with an average molecular weight of about 1,000-3,000 and the use of mixtures of an alkenylsuccinic acid amide with an average molecular weight of about 700-2,000 and an alkenylsuccinic acid imide with an average molecular weight of about 10,000-20,000.
[0094] The carboxylic acid portion of the reaction product between the carboxylic acid and amine may be of a single type or two or more types, and as specific examples there may be mentioned C12-24 fatty acids and C7-24 aromatic carboxylic acids. C12-24 fatty acids include, but are not limited to, linoleic acid, oleic acid, palmitic acid and myristic acid. C7-24 aromatic carboxylic acids include, but are not limited to, benzoic acid and salicylic acid. Also, the amine portion of the reaction product between the carboxylic acid and amine may be of a single type or two or more types. Oleylamine is a typical amine which may be used in this case, but there is no limitation to this amine and various amines may be used. The amount of detergent used is not particularly restricted, but in order to bring out the effect of adding the detergent, and specifically the effect of preventing occlusion of the fuel injection nozzle, the detergent content is preferably 30 ppm by mass or greater, more preferably 60 ppm by mass or greater and even more preferably 80 ppm by mass or greater. No effect may be exhibited if the amount of addition is less than 30 ppm by mass. On the other hand, an excessively large amount will not produce a commensurate effect, and conversely it may increase the NOx, PM and aldehydes in diesel engine exhaust gas, for which reason the amount of detergent added is preferably 300 ppm by mass or less and more preferably 180 ppm by mass or less.
[0095] Similar to the cetane number improvers mentioned above, commercially available lubricity improvers and detergents are generally purchased in a form having the active ingredient contributing to lubricity improvement or detergency diluted with an appropriate solvent. When such a commercially available product is used to prepare the gas oil composition of the invention, the content of the active ingredient in the gas oil composition is preferably within the range specified above.
[0096] For the purpose of further improving the performance of the gas oil composition of the invention, other publicly known fuel oil additives (hereinafter referred to as "other additives" for convenience) described hereunder may be added either alone or in combinations of more than one type. As examples of other additives there may be mentioned cold flow improvers such as ethylene-vinyl acetate copolymer, and alkenylsuccinic acid imides; phenol-based and amine-based antioxidants; metal deactivators such as salicylidene derivatives; anti-icing agents such as polyglycol ethers; corrosion inhibitors such as aliphatic amines and alkenylsuccinic acid esters; antistatic agents such as anionic, cationic and amphoteric surfactants; coloring agents such as azo dyes; and anti-foaming agents such as silicones.
[0097] The other additives may be added in any desired amounts, but the amount for addition of each additive is preferably 0.5 % by mass or less and more preferably 0.2 % by mass or less.
[Examples]
[0098] The present invention will now be explained in greater detail through examples and comparative examples, with the understanding that these examples are in no way limitative on the invention.
(Examples 1-3)
[0099] First, a hydrotreated gas oil having the prescribed properties was subjected to further hydrogenation in the presence of a hydrogenation catalyst (Pt/Pd-silica/alumina), under the conditions shown in Table 1, to obtain deep hydrotreated gas oil-1 and deep hydrotreated gas oil-2. The properties (density at 15° C , kinematic viscosity at 40°C, sulfur content, distillation properties, aromatic content (total aromatic and bicyclic or group aromatic contents), naphthene content and cetane index) of the hydrotreated gas oil, deep hydrotreated gas oil-1 and deep hydrotreated gas oil-2 are shown in Table 2.
[0100] The deep hydrotreated gas oil-1 and/or deep hydrotreated gas oil-2 obtained in this manner was combined with one or more hydrocracked gas oils, synthetic gas oils, deep hydrotreated kerosenes and/or hydrotreated kerosenes, and the additives mentioned below were further added to obtain gas oil compositions for Examples 1-3 having the compositions shown in Table 3. The properties of the hydrocracked gas oils, synthetic gas oils, deep hydrotreated kerosenes and hydrotreated kerosenes are shown in Table 2. The properties (density at 15° C , kinematic viscosity at 40 °C, sulfur content, distillation properties, aromatic content (total aromatic and bicyclic or group aromatic contents), naphthene content, cetane index, cetane number, flow point, cold filter plugging point, HFRR wear scar diameter (WS1.4) representing the lubricity, ash content, oxidation stability (total insoluble fraction and peroxide number) and conductivity) of the gas oil compositions of Examples 1-3 are shown in Table 3.
(Additives)
[0101]
Lubricity improver: Carboxylic acid mixture composed mainly of linoleic acid
Detergent: Reaction product of alkylamine and carboxylic acid mixture composed mainly of oleic acid.
Cold flow improver: Ethylene-vinyl acetate copolymer
(Comparative Examples 1 and 2)
[0102] The hydrotreated gas oils, synthetic gas oils, deep hydrotreated kerosenes and aforementioned additives were used to prepare gas oil compositions for Comparative Examples 1 and 2, having the compositions shown in Table 3. The properties of the gas oil compositions of Comparative Examples 1 and 2 are also shown in Table 3.
Table 1
| Deep hydrotreated gas oil-1 | Deep hydrotreated gas oil-2 | |||
| Hydrogenation catalyst | Pt/Pd-silica/alumina | Pt/Pd-silica/alumina | ||
| Reaction temperature [°C] | 240 | 180 | ||
| Hydrogen partial pressure [MPa] | 5 | 5 | ||
| LHSV [h-1] | 1.0 | 1.0 | ||
| Hydrogen/oil ratio [NL/L] | 450 | 450 | ||
| Feed properties | Sulfur content [ppm by mass] | 9 | 9 | |
| Distillation properties (°C) | Initial boiling point | 197 | 197 | |
| 10% | 257 | 257 | ||
| 50% | 306 | 306 | ||
| 90% | 342 | 342 | ||
| End point | 356 | 356 | ||
Table 3
| Example 1 | Example 2 | Example 3 | Comparative Example 1 | Comparative Example 2 | |||
| Base oil composition [% by volume] | Deep hydrotreated diesel fuel-1 | 85 | - | 60 | - | - | |
| Deep hydrotreated diesel fuel-2 | - | 80 | 20 | - | - | ||
| Hydrotreated diesel fuel | - | - | - | 80 | - | ||
| Hydrocracked diesel fuel | - | - | 5 | - | - | ||
| Synthetic diesel fuel | - | - | 5 | - | 80 | ||
| Deep hydrotreated kerosene | 15 | - | 10 | 20 | 20 | ||
| Hydrotreated kerosene | - | 20 | - | - | - | ||
| Additives [ppm by mass] | Lubricity improver | 70 | 70 | 70 | 70 | 150 | |
| Cold flow improver | - | 200 | 200 | 200 | 400 | ||
| Detergent | - | - | 150 | 150 | - | ||
| Density (15°C) [kg/m3] | 822 | 826 | 824 | 831 | 790 | ||
| Dynamic viscosity (40°C) [mm2/s] | 3.8 | 3.8 | 3.9 | 4.2 | 3.3 | ||
| Sulfur content [ppm by mass] | 0.4 | 3.2 | 0.9 | 7.3 | 0.1 | ||
| Distillation properties [°C] | Initial boiling point | 165 | 169 | 166 | 166 | 162 | |
| 10% | 241 | 244 | 240 | 242 | 221 | ||
| 50% | 287 | 295 | 293 | 293 | 247 | ||
| 90% | 314 | 319 | 319 | 330 | 276 | ||
| End point | 339 | 348 | 346 | 345 | 317 | ||
| Aromatic content [% by volume] | Total aromatic components | 0.6 | 9.1 | 2.4 | 15.9 | 0.1 | |
| Bicyclic or greater | 0.1 | 0.4 | 0.2 | 2.1 | 0.0 | ||
| Naphthene content [% by volume] | 45.3 | 34.4 | 41.6 | 33.8 | 9.2 | ||
| Cetane index | 65.5 | 65.4 | 66.0 | 62.5 | 70.7 | ||
| Cetane number | 64.1 | 65.0 | 65.0 | 64.7 | 68.8 | ||
| Flow point [°C] | -12.5 | -12.5 | -12.5 | -12.5 | -15.0 | ||
| Wear scar diameter (WS1.4) [µm] | 390 | 380 | 380 | 380 | 380 | ||
[0103] As shown in Table 3, Examples 1-3 employed deep hydrotreated gas oil-1 and deep hydrotreated gas oil-2 which had 90% distillation temperatures, densities at 15°C, sulfur contents, naphthene contents and aromatic contents that were all within the ranges specified by the invention, and it was therefore possible to easily and reliably obtain gas oil compositions having sulfur contents of 5 ppm by volume or less, aromatic contents of 10 % by volume or less, bicyclic or greater aromatic contents of 1 % by volume or less, densities at 15°C of between 820 kg/m3 and 840 kg/m3, 10% distillation temperatures of 250°C or lower and 90% distillation temperatures of 320°C or lower. However, in Comparative Examples 1 and 2 in which gas oil compositions were prepared without using deep hydrotreated gas oil, all of the properties could not be simultaneously satisfied.
[0104] Next, the gas oil compositions of Examples 1-3 and Comparative Examples 1 and 2 were subjected to different tests using the diesel engine described below. The test method used for the engine exhaust gas measurement was according to "Technical Standards for Diesel Vehicle 13-Mode Exhaust Gas Measurement", enclosed with the Reference Handbook For New Vehicle Inspections, edited by the (former) Transport Ministry, under stationary conditions in the 10th of 13 modes (60% rpm, 80% load). The DPF used was a continuous regenerating DPF with an oxidizing catalyst function in the filter section. All of the results were evaluated as relative values with respect to 100 as the value for measurement when running without the DPF using the gas oil composition of Comparative Example 1 as the test fuel. That is, the fuel efficiency was considered to be improved if the results exceed 100, and the PM, aldehyde and fine particles were considered to be improved if the results were below 100.
(Engine specifications)
[0105]
Engine type: Natural aspiration in-line 4-cylinder diesel
Displacement volume: 5 L
Compression ratio: 19
Maximum power: 110 kW/2900 rpm
Maximum torque: 360 Nm/1700 rpm
Conformity to standards: Conformed to 2004 Exhaust Gas Standards
(PM and aldehyde concentration measurement test)
[0106] The concentration measurement for a PM sample and aldehyde sample was conducted with the engine alone, or with the DPF equipped in the engine, by exhaust gas dilution using the partial tunnel dilution method conforming to the test method described above. Collection and analysis were accomplished using a fluorocarbon-coated glass fiber filter for the PM sampling and a DNPH cartridge for the aldehyde sampling. The results are shown in Table 4.
(Measurement of fine particles)
[0107] The total number of particles in the PM was also measured during the PM and aldehyde concentration measurement test.
[0108] For measurement of the number of particles, a scanning mobility particle size analyzer such as shown in Fig. 1 was used for separation of the different particle sizes and detection of the particle sizes. In the apparatus shown in Fig. 1, a charge distribution controller 12, a classifier 13 and a particle counter 14 are provided along the flow channel through which the diluted exhaust gas sample passes, in that order from the upstream end. The fine particles in the diluted exhaust gas are in a balanced charge distribution in the charge distribution controller 12, and the particles are classified (separated) in the classifier 13 according to their respective electrical mobilities. The particles separated according to size are then counted in the particle counter 14.
[0109] The results of measuring the total number of particles of the PM are shown in Table 4. The values in Table 4 are the total numbers of fine particles emitted in mode 13, evaluated as relative values with respect to 100 as the value for measurement when running without the DPF using the gas oil composition of Comparative Example 1 as the test fuel.
(Evaluation of fuel efficiency property)
[0110] The fuel efficiency property of each gas oil composition was evaluated during the PM and aldehyde concentration measurement test. For the fuel efficiency, the fuel volume flow consumed at the 10th mode was adjusted for fuel temperature and substituted for the weight value, and each was evaluated as a relative value with respect to 100 as the value for measurement when running without the DPF using the gas oil composition of Comparative Example 1 as the test fuel. The results are shown in Table 4.
Table 4
| Example 1 | Example 2 | Example 3 | Comp. Example 1 | Comp. Example 2 | ||
| Without DPF | PM | 65 | 85 | 85 | 100 | 80 |
| Aldehydes | 70 | 88 | 85 | 100 | 75 | |
| Fine particle count | 70 | 75 | 75 | 100 | 85 | |
| Fuel efficiency | 102 | 105 | 103 | 100 | 80 | |
| With DPF | PM | 18 | 23 | 23 | 25 | 21 |
| Aldehydes | 15 | 18 | 17 | 20 | 16 | |
| Fine particle count | 11 | 13 | 11 | 15 | 18 | |
| Fuel efficiency | 102 | 105 | 102 | 99 | 81 | |
[0111] As explained above, the present invention employs a deep hydrotreated gas oil having a 90% distillation temperature, density at 15° C , sulfur content, naphthene content and aromatic content that are all within the respective ranges specified above, which is obtained by hydrogenation of a hydrotreated fuel with prescribed properties in the presence of a hydrogenation catalyst, thereby allowing easy and reliable control of the sulfur content, aromatic content, naphthene content, density and distillation properties of the gas oil composition as a whole, which has been difficult to realize with conventional base oils. Furthermore, by adding the deep hydrotreated gas oil in a prescribed amount to a gas oil composition to obtain a gas oil composition having a sulfur content, aromatic content, bicyclic or greater aromatic content, naphthene content, density at 15° C , 10% distillation temperature and 90% distillation temperature which are in the respective ranges specified above, a gas oil composition is realized which satisfies the required properties as a future-type diesel fuel and can achieve a high level of and satisfactory balance between environmental load reduction and fuel efficiency improvement.
1. A gas oil composition characterized
by comprising 20 % by volume or greater of a deep hydrotreated gas oil having a 90% distillation temperature of 200-380°C, a density of 780-870 kg/m3 at 15°C, a sulfur content of 5 ppm by mass or less, an aromatic content of 10 % by volume or less and a naphthene content of 30 % by volume or greater, the deep hydrotreated gas oil obtained by subjecting a hydrotreated oil having a sulfur content of 5-10 ppm by mass and a boiling point range of 150-380°C to further hydrogenation in the presence of a hydrogenation catalyst; and
by having a sulfur content of 5 ppm by mass or less, an aromatic content of 10 % by volume or less, a bicyclic or greater aromatic content of 1 % by volume or less, a naphthene content of 30 % by volume or greater, a density of 820-840 kg/m3 at 15°C, a 10% distillation temperature of 250°C or lower, and a 90% distillation temperature of 320°C or lower.
by comprising 20 % by volume or greater of a deep hydrotreated gas oil having a 90% distillation temperature of 200-380°C, a density of 780-870 kg/m3 at 15°C, a sulfur content of 5 ppm by mass or less, an aromatic content of 10 % by volume or less and a naphthene content of 30 % by volume or greater, the deep hydrotreated gas oil obtained by subjecting a hydrotreated oil having a sulfur content of 5-10 ppm by mass and a boiling point range of 150-380°C to further hydrogenation in the presence of a hydrogenation catalyst; and
by having a sulfur content of 5 ppm by mass or less, an aromatic content of 10 % by volume or less, a bicyclic or greater aromatic content of 1 % by volume or less, a naphthene content of 30 % by volume or greater, a density of 820-840 kg/m3 at 15°C, a 10% distillation temperature of 250°C or lower, and a 90% distillation temperature of 320°C or lower.
2. A gas oil composition according to claim 1, characterized by further comprising at least one selected from a hydrocracked gas oil, a hydrocracked
kerosene, a hydrotreated kerosene, a synthetic gas oil and a synthetic kerosene.
3. A gas oil composition according to claim 1 or 2, characterized by having an end point of 350°C or lower, a cetane number of 55 or greater, a cetane
index of 52 or greater, a kinematic viscosity of 2-4 mm2/s at 40°C, an HFRR wear scar diameter of 400 µm or less and a flow point of -7.5°C
or lower.
4. A method for production of a gas oil composition characterized by comprising:
a first step of subjecting a hydrotreated oil having a sulfur content of 5-10 ppm by mass and a boiling point range of 150-380°C to further hydrogenation in the presence of a hydrogenation catalyst, to obtain a deep hydrotreated gas oil having a 90% distillation temperature of 200-380°C, a density of 780-870 kg/m3 at 15°C, a sulfur content of 5 ppm by mass or less, an aromatic content of 10 % by volume or less and a naphthene content of 30 % by volume or greater, and
a second step of mixing the deep hydrotreated gas oil with at least one selected from a hydrocracked gas oil, a hydrocracked kerosene, a hydrotreated kerosene, a synthetic gas oil and a synthetic kerosene, to obtain a gas oil composition comprising 20 % by volume or greater of the deep hydrotreated gas oil and having a sulfur content of 5 ppm by mass or less, an aromatic content of 10 % by volume or less, a bicyclic or greater aromatic content of 1 % by volume or less, a naphthene content of 30 % by volume or greater, a density of 820-840 kg/m3 at 15°C, a 10% distillation temperature of 250°C or lower, and a 90% distillation temperature of 320°C or lower.
5. A method for production of a gas oil composition according to claim 4, characterized in that the gas oil composition obtained in the second step has an end point of 350°C or
lower, a cetane number of 55 or greater, a cetane index of 52 or greater, a kinematic
viscosity of 2-4 mm2/s at 40°C, an HFRR wear scar diameter of 400 µm or less and a flow point of -7.5°C
or lower.