AU2007232015B2 - Method for treatment of synthetic oil, process for production of hydrocarbon oil, hydrocarbon oil for hydrogen production, hydrocarbon oil for the smoke point improver for kerosene, and hydrocarbon oil for diesel fuel base - Google Patents

Method for treatment of synthetic oil, process for production of hydrocarbon oil, hydrocarbon oil for hydrogen production, hydrocarbon oil for the smoke point improver for kerosene, and hydrocarbon oil for diesel fuel base Download PDF

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AU2007232015B2
AU2007232015B2 AU2007232015A AU2007232015A AU2007232015B2 AU 2007232015 B2 AU2007232015 B2 AU 2007232015B2 AU 2007232015 A AU2007232015 A AU 2007232015A AU 2007232015 A AU2007232015 A AU 2007232015A AU 2007232015 B2 AU2007232015 B2 AU 2007232015B2
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distillate
mass
fraction
hydrocracking
middle distillate
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AU2007232015A1 (en
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Yoshifumi Chiba
Osamu Sadakane
Shinya Takahashi
Yuichi Tanaka
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Eneos Corp
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Nippon Oil Corp
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Priority claimed from JP2006095201A external-priority patent/JP4908037B2/en
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    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G65/00—Treatment of hydrocarbon oils by two or more hydrotreatment processes only
    • C10G65/14—Treatment of hydrocarbon oils by two or more hydrotreatment processes only plural parallel stages only

Abstract

A process characterized by comprising the step of subjecting synthetic oil obtained by the Fischer-Tropsch process to fractional distillation to obtain a middle distillate comprising at least 90% by mass of components having boiling points of 150 to 360°C and a heavy wax component, the step of hydrorefining the middle distillate in such a way that the increase after hydrorefining in the content (% by mass) of components having boiling points of 150°C or below is 9% by mass or below, the step of subjecting the hydrorefined middle distillate to fractional distillation to obtain the first cut comprising at least 90% by mass of components having boiling points of 150 to 250°C and the second heavy cut, the step of hydrocracking the heavy wax component, the step of subjecting the hydrocracked wax component to fractional distillation to obtain the third cut comprising at least 90% by mass of components having boiling points of 150 to 360°C, and the step of mixing the second heavy cut with the third cut.

Description

FP06-0522-00 DESCRIPTION METHOD FOR TREATMENT OF SYNTHETIC OIL, PROCESS FOR PRODUCTION OF HYDROCARBON OIL, HYDROCARBON OIL FOR HYDROGEN PRODUCTION, HYDROCARBON OIL FOR THE SMOKE POINT IMPROVER FOR KEROSENE, AND HYDROCARBON OIL FOR DIESEL FUEL BASE TECHNICAL FIELD [0001] The present invention relates to a method for processing synthetic oil, a method for producing hydrocarbon oils, and hydrocarbon oils for use in hydrogen production, in kerosene smoke point improver and in a diesel fuel base stock each of which is obtained by the above processing method or hydrocarbon oil producing method. BACKGROUND ART [0002] Recently, from the viewpoint of mitigating the environmental impact, there have been demands for a clean liquid fuel that has low sulfur and low* aromatic hydrocarbon contents and is friendly to the environment. And in the oil industry, as a process for producing a clean fuel, Fischer Tropsch synthesis (hereinafter abbreviated as "FT synthesis"), which uses carbon monoxide and hydrogen as raw materials, has been examined. FT synthesis permits the production of a paraffin rich and sulfur-free liquid fuel base stock; therefore, very much hope is placed on it. [0003] The synthetic oil obtained by FT synthesis (hereinafter referred to as "FT synthetic oil") has a wide carbon number distribution, thereby providing FT naphtha distillate, which contains a large amount of hydrocarbons having a boiling point of 150*C or lower, FT middle FP06-0522-00 distillates, which contain a large amount of distillates having a boiling point in the range of 150*C to 360*C, and FT wax distillate, which is heavier than the middle distillates. Of these distillates, FT naphtha distillate has a high content of straight-chain hydrocarbons (which mean normal paraffin, straight-chain alcohols, a-olefins, and the like) and an extremely low octane number; therefore, it is of low value-added as a fuel base stock. In contrast, FT middle distillates and FT wax distillate can be converted, by hydrogenation, into high value-added components suitable for fuel base stocks, such as diesel fuel, kerosene and hydrocarbon oil for hydrogen production. Thus, from the viewpoint of improving the economy in fuel production process, there have been demands for a technique that enables the efficient conversion of FT synthetic oil, particularly its distillates having a boiling point of 150'C or higher, into high value-added components suitable for fuel base stocks. [0004] Methods for producing a diesel fuel base stock from FT synthetic oil have been examined up until now. For example, there are known techniques for hydrocracking heavy wax distillates (for example, see Patent document 1) or techniques for hydrotreating FT middle distillates (for example, see Patent document 2). [0005] Further, techniques have also been examined for utilizing the middle distillates in FT synthetic oil as a fuel for producing hydrogen to be fed for fuel cells. For example, there have been proposed techniques for increasing, using a hydrocarbon oil derived from FT synthetic oil and having a specific composition, the efficiency of hydrogen production unit which generates hydrogen by steam reforming 2 C\:NRFIrioULWAMUV1 IIjv-.UUL-i/ lIIWU i -3 (for example, see Patent document 3). [0006] Furthermore, as a method for producing kerosene or jet fuels from FT synthetic oil, there have been proposed techniques for fractionating oils produced by hydrocracking and isomerising FT 5 synthetic oil (for example, see Patent document 4). [0007] Patent document 1: International Publication Number WO 00/020535. Patent document 2: French Patent Laid-Open No. 2826971. Patent document 3: International Publication No. WO 00/061707. 10 Patent document 4: Japanese Patent Laid-Open No. 2004-323626. DISCLOSURE OF THE INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION [0008] However, in recent conditions where severer requirements are placed on fuel production costs than before, even in the conventional 15 techniques as described above, the economy in fuel production process is not necessarily satisfactory for the reason described below. [0009] Specifically, the techniques described in Patent document 1-4 are all for obtaining components useful for specific fuel base stocks, and when using such techniques in processing of FT synthetic oil on a 20 commercial scale, a large amount of low value-added or excess components are produced at the same time. Thus, further improvement is needed to increase the economy in fuel production process. [0010] The present invention has been made in the light of the above problem. The present invention seeks to provide: a method for 25 processing synthetic oil that makes it possible to convert FT synthetic oil into high value-added components at a high conversion and achieve the economy in fuel production process at high levels; and hydrocarbon oils, of high value-added and good in economy, for use in hydrogen production, in kerosene smoke point improver and in a diesel fuel base -4 stock, each of which is obtained by the above processing method. The present invention seeks to provide a method for producing hydrocarbon oils that permits the efficient production of such high value-added hydrocarbon oils. 5 MEANS FOR SOLVING THE PROBLEMS [0011] In a first aspect there is provided a method for processing synthetic oil, comprising: a first fractional-distillation step of subjecting a material to be processed, which comprises synthetic oil obtained by Fischer Tropsch 10 synthesis, to fractional distillation to obtain a middle distillate, which contains a fraction having a boiling point of 150 to 360*C at 90% by mass or more, and a wax distillate, which is heavier than the middle distillate; a hydrotreating step of subjecting the middle distillate obtained 15 in the first fractional-distillation step to a hydrotreating process that includes both hydrocracking and hydroisomerization by bringing said middle distillate into contact with a hydrotreating catalyst comprising a support containing one or more kinds of solid acids which are selected from the group consisting of crystalline zeolites and amorphous metal 20 oxides having heat resistance, and a group VIII metal supported on said support in the presence of hydrogen so that a fraction having a boiling point of 150*C or lower of the middle distillate has a content (% by mass) with an increase rate of 9% by mass or less after the contact with the catalyst; 25 a second fractional-distillation step of subjecting the middle distillate having passed through the hydrotreating step to fractional distillation to obtain a first fraction, which contains a fraction having a boiling point of 150 to 250*C at 90% by mass or more, and a second fraction, which is heavier than the first fraction; C:WNRborJU \LWAMU9713U-I.UU-IIlIUl -5 a hydrocracking step of subjecting the wax distillate obtained in the first fractional-distillation step to a hydrocracking process that includes hydroisomerization by bringing said wax distillate into contact with a hydrocracking catalyst comprising a support containing one or 5 more kinds of solid acids which are selected from the group consisting of crystalline zeolites and amorphous metal oxides having heat resistance, and a group VIII metal supported on said support in the presence of hydrogen; a third fractional-distillation step of subjecting the wax 10 distillate having passed through the hydrocracking step to fractional distillation to obtain a third fraction, which contains a fraction having a boiling point of 150 to 360"C at 90% by mass or more; and a mixing step of mixing the second fraction and the third fraction. 15 [0011 A] In a second aspect a hydrocarbon oil for hydrogen production, comprising the first fraction obtained by the method for producing hydrocarbon oils of the present invention, wherein the hydrocarbon oil has a smoke point of 44 mm or more. [0012] The term "increase level" above used means the value obtained 20 by subtracting the content (% by mass) of distillates having a boiling point of 150 0 C or lower in the middle distillate before the contact with hydrotreating catalyst from the content (% by mass) of distillates having a boiling point of 150*C or lower in the middle distillate after the contact with the same. 25 [0013] According to the method for processing synthetic oil of the -6 present invention, FT synthetic oil can be efficiently converted into high value-added hydrocarbon oils. This means that the method for processing synthetic oil of the present invention can make it possible to obtain high value-added hydrocarbon oils from FT synthetic oil in a high 5 yield, thereby achieving the economy in fuel production process at high levels. [0014] In the method for processing synthetic oil of the present invention, the first fraction can be obtained as a hydrocarbon oil for hydrogen production while the mixture of the second and third fractions 10 can be obtained as a hydrocarbon oil for use in a diesel fuel base stock. [0015] According to the method for processing synthetic oil, both hydrocarbon oil useful as a raw material for hydrogen production and hydrocarbon oil useful as a diesel fuel base stock can be obtained from FT synthetic oil in a high yield. 15 [0016] From the viewpoint of preventing the seizing in the combustion cylinder, which is caused by the fuel pump failure or oil film disruption, desirably diesel fuel used for diesel vehicles has a certain degree of kinematic viscosity at ordinary temperature and high temperatures. For example, it is stipulated in Japanese Industrial 20 Standards that the kinematic viscosity of gas oil at 30 0 C measured in accordance with JIS K2283-2 is to be 2.5 mm 2/s or higher. Thus, a hydrocarbon oil used as a diesel fuel base stock is required to have both fully improved low temperature fluidity and fully improved kinematic viscosity. 25 [0017] On the other hand, from the viewpoint of producing hydrogen efficiently and for a long time, desirably a hydrocarbon oil for hydrogen production is such that it does not significantly lower the hydrogen production capacity of hydrogen production unit, such as steam reformer. [0018] In this respect, the above method for processing synthetic oil - 6A can make it possible to obtain, in a high yield, a hydrocarbon oil for use in a diesel fuel base stock that has a pour point of -7.5*C or lower and a kinematic viscosity of 2.55 mm 2/s or higher at 30'C, as the mixture of the second and third fractions, and a hydrocarbon oil for hydrogen 5 production that allows the decrease in hydrogen production capacity of hydrogen production unit to be very small, as the first fraction. According to the present invention, high value-added hydrocarbon oils FP06-0522-00 as described above can be obtained in a high yield, whereby the economy in fuel production process can be achieved at very high levels. [0019] In the method for processing synthetic oil of the present invention, the first fraction can be obtained as a hydrocarbon oil for use in kerosene smoke point improver and the mixture of the second and third fractions as a hydrocarbon oil for use in a diesel fuel base stock. [0020] According to the method for processing synthetic oil, both hydrocarbon oil having the excellent kerosene-smoke-point improving effect and hydrocarbon oil useful as a diesel fuel base stock can be obtained in a high yield. [0021] The hydrocarbon oil used as a diesel fuel base stock is required to have both fully improved low temperature fluidity and fully improved kinematic viscosity, as described above. On the other hand, in the straight-run kerosene distillate obtained from some crude oil (e.g. Dubai crude oil or Isthmus crude oil) or the cracked kerosene distillate produced when subjecting a heavy oil distillate having a boiling point higher than that of kerosene to hydrogenation or catalytic cracking, its smoke point is low even if it undergoes hydrogenation; thus, it cannot be used directly as kerosene. Under these circumstances, methods have been examined in which a kerosene base stock having a high smoke point is blended as kerosene smoke point improver in such kerosene distillate to increase the production of kerosene, like the method described in Japanese Patent Laid-Open No. 2000-256681. However, the kerosene base stock used in the above conventional methods is insufficient to improve kerosene smoke point; as a result, the material needs to be blended in a large amount. I7 FP06-0522-00 [0022] In contrast, according to the method for processing synthetic oil of the present invention, it is possible to obtain, in a high yield, a hydrocarbon oil showing a pour point of -7.5*C or lower and a kinematic viscosity of 2.5 mm2/s or higher at 30*C as the mixture of the second and third fractions and a hydrocarbon oil that produces, when blended with inferior quality kerosene having a smoke point of 22 mm or less, the effect of improving the smoke point to 2.3 mm or more, in terms of the value when the blend percentage is 10% by mass (based on the total amount of the kerosene after blended with the hydrocarbon), as the first fraction. Thus, according to the present invention, it is possible to achieve the economy in fuel base stock production process at very high levels. [0023] The term "smoke point of kerosene" herein used means a smoke point measured in accordance with the test method specified in JIS K2537. [0024] In the method for processing synthetic oil of the present invention, preferably part of or the whole of the wax distillate obtained in the third fractional-distillation step, which is heavier than the third fraction, is subjected to a hydrocracking step. Recycling and hydrocracking such a wax distillate makes it possible to increase the yield of the component useful as a diesel fuel base stock, that is, the mixture of the second and third fractions. [0025] In the method for processing synthetic oil of the present invention, preferably the hydrocracking of the wax distillate is carried out so that the wax distillate after the contact with hydrocracking catalyst contains a fraction having a boiling point of 360*C or lower at 0 FP06-0522-00 45 to 85% by mass. If the content is lower than 45% by mass, the yield of the component useful as a diesel fuel base stock, that is, the yield of the mixture of the second and third fractions tends to decrease, and besides, the low temperature fluidity of the mixture also tends to lower, whereas if the content is higher than 85% by mass, the yield of the component useful as a diesel fuel base stock, that is, the yield of the mixture of the second and third fractions tends to decrease. [0026] In the method for processing synthetic oil of the present invention, preferably the hydrotreating catalyst, which is brought into contact with the middle distillate, includes: a support containing 0.1% by mass to 80.0% by mass crystalline zeolite and heat resistant amorphous metal oxide; and one or more kinds of metals selected from the group consisting of the group VIII metals in the periodic table, which are supported on the support. [0027] In the method for processing synthetic oil of the present invention, preferably the hydrocracking catalyst, which is brought into contact with the wax distillate, includes: a support containing 0.1% by mass to 80.0% by mass crystalline zeolite and 0.1% by mass to 60.0% by mass heat resistant amorphous metal oxide; and one or more kinds of metals selected from the group consisting of the group VIII metals in the periodic table, which are supported on the support. [0028] In the method for processing synthetic oil of the present invention, when the middle distillate is brought into contact with the hydrotreating catalyst, preferably the reaction temperature is 200 to 370 0 C, the hydrogen partial pressure is 1.0 to 5.0 MPa and the liquid hourly space velocity is 0.3 to 3.5 h~', and when the wax distillate is nI FP06-0522-00 brought into contact with the hydrocracking catalyst, preferably the reaction temperature is 200 to 370*C, the hydrogen partial pressure is 1.0 to 5.0 MPa and the liquid hourly space velocity is 0.3 to 3.5 h-I. [0029] In the method for processing synthetic oil of the present invention, it is preferable from the viewpoint of fully ensuring the economy in process that the total mass of the first, second and third fractions is 66% by mass or more of the mass of the distillates in FT synthetic oil that substantially have a boiling point of 150*C or higher. [0030] In the method for processing synthetic oil of the present invention, when subjecting part of or the whole of the wax distillate obtained in the above described third fractional-distillation step, which is heavier than the third fraction, to hydrocracking step, it is preferable from the viewpoint of further improving the economy in process that the total mass of the first, second and third fractions is 77% by mass or more of the mass of the distillates in FT synthetic oil that substantially have a boiling point of 150*C or higher. [0031] The present invention also provides a hydrocarbon oil for use in a diesel fuel base stock, which includes the mixture of the second and third fractions obtained by the method for processing synthetic oil of the present invention and is characterized in that it has a pour point of 7.5*C or lower and a kinematic viscosity of 2.5 mm 2 /s or higher at 30*C. [0032] The present invention also provides a hydrocarbon oil for hydrogen production, which includes the first fraction obtained by the method for processing synthetic oil of the present invention and is characterized in that it has a smoke point of 44 mm or more. The term "smoke point of a hydrocarbon oil" herein used means a smoke point 1 / - 11 measured in accordance with the test method specified in JIS K2537. [0033] The present invention also provides a hydrocarbon oil for use in kerosene smoke point improver, which includes the first fraction obtained by the method for processing synthetic oil of the present 5 invention and is characterized in that it has a smoke point of 44 mm or more. [0034] The hydrocarbon oils, of the present invention, for use in a diesel fuel base stock, in hydrogen production and in kerosene smoke point improver each can have a good performance and can be obtained in 10 a high yield by the method for processing synthetic oil of the present invention, thereby advantageously having a very high cost-performance. Accordingly, the use of the hydrocarbon oil for a diesel fuel base stock of the present invention can make it possible to realize cost reduction for diesel fuel with low environmental impact. The use of the hydrocarbon 15 oil for hydrogen production of the present invention can make it possible to sufficiently retrain the decrease in hydrogen production capacity of hydrogen production unit, thereby achieving the production of hydrogen at lower costs. And the use of the hydrocarbon oil for use in kerosene smoke point improver of the present invention can make it possible to 20 increase kerosene production at lower costs. [0035] - 12 [0036] According to the method for producing hydrocarbon oils of the present invention, high value-added hydrocarbon oils as described above can be obtained in a high yield, because the method includes the above described steps. Specifically, according to the method for 5 producing hydrocarbon oils of the present invention, it is possible to obtain from FT synthetic oil, in a high yield, the first fraction as a -13 hydrocarbon oil suitable for use in hydrogen production or in kerosene smoke point improver and the mixture of the second and third fractions as a hydrocarbon oil suitable for use in a diesel fuel base stock. EFFECT OF THE INVENTION 5 [0037] According to the present invention, there can be provided a method for processing synthetic oil that makes it possible to convert FT synthetic oil into high value-added components at a high conversion and achieve the economy in fuel manufacturing process at high levels and also provided hydrocarbon oils for use in hydrogen production, in 10 kerosene smoke point improver and in a diesel fuel base stock all of which are obtained by the above processing method and are of high value-added and good in economy. According to the present invention, a method for producing hydrocarbon oils can also be provided which enables the efficient production of such high value-added hydrocarbon 15 oils. BRIEF DESCRIPTION OF THE DRAWINGS [0038] Embodiments of the invention will now be described with reference to the drawings which are non-limiting and in which: FIG. 1 is a flow diagram showing one example of hydrocarbon 20 oil production apparatus in which the method for processing synthetic oil of the present invention is carried out. FIG. 2 is a schematic block diagram of testing machine for hydrogen production capacity. Explanation of Reference Numerals 25 [0039] LI: FT-synthetic-oil introducing flow path; L2: middle distillate flow path; L3: wax-distillate flow path; L4 - L1O: flow path; Lil: circulation flow path; L12, L13: flow path; 10: first distillation column; 20: hydrotreating unit; 30: hydrocracking unit, 40: second distillation FP06-0522-00 column; 50: third distillation column; 100: Hydrocarbon oil production apparatus. BEST MODE FOR CARRYING OUT THE INVENTION [0040] In the following, the preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, identical or corresponding elements are denoted by like reference numerals so that the repetitive description will be omitted. [0041] FIG 1 is a flow diagram showing one example of hydrocarbon oil production apparatus in which the method for processing synthetic oil of the present invention is carried out. Hydrocarbon oil production apparatus 100 shown in FIG 1 includes: FT-synthetic-oil introducing flow path LI through which a raw material including FT synthetic oil is introduced; first distillation column 10 which fractionates the synthetic oil having been introduced through FT-synthetic-oil introducing flow path Ll into a light distillate, a middle distillate and a heavy wax distillate; hydrotreating unit 20 which hydrotreats the middle distillate fed from first distillation column 10 through middle-distillate flow path L2; hydrocracking unit 30 which hydrocracks the heavy wax distillate fed from first distillation column 10 through wax-distillate flow path L3; second distillation column 40 which fractionates the middle distillate having passed through hydrotreating unit 20 (hydrotreated distillate) into a light middle distillate (first fraction) and a heavy middle distillate (second fraction), which is heavier than the light middle distillate; third distillation column 50 which fractionates the heavy wax distillate having passed through hydrocracking unit 30 (hydrocracked 1A FP06-0522-00 distillate) into a middle distillate (third fraction) and a heavy wax distillate (un-hydrocracked wax distillate), which is heavier than the middle distillate; flow path L6 for taking the light middle distillate (first fraction) from second distillation column 40 to the outside of the system; and flow path L13 for mixing the heavy middle distillate (second fraction) fed from second distillation column 40 through flow path L7 and the middle distillate (third fraction) fed from third distillation column 50 through flow path L10 and taking the mixture to the outside the system. hydrotreating unit 20 and second distillation column 40 are connected to each other by flow path L5 and midway along the flow path is provided a gas-liquid separation tank (not shown in the figure) for removing gaseous components from the hydrotreated distillate. And hydrocracking unit 30 and third distillation column 50 are connected to each other by flow path L9 and midway along the flow path is provided a gas-liquid separation tank (not shown in the figure) for removing gaseous components from the hydrocracked distillate. Further, to third distillation column 50 are connected flow path L12 for taking the distillate lighter than the middle distillate (third fraction) out and circulation flow path L 11 for feeding, if necessary, the wax distillate heavier than the middle distillate (third fraction) to hydrocracking unit 30 to hydrocrack the same. [0042] In the following the method for processing synthetic oil of the present invention will be described in detail with reference to hydrocarbon oil production apparatus 100 of FIG 1. [0043](Fractional distillation of raw material including FT synthetic oil) As FT synthetic oil which is contained in a raw material subject 1s FP06-0522-00 to processing by the method for processing synthetic oil of the present invention (a material to be processed), is preferable FT synthetic oil that contains, on the basis of total amount of FT synthetic oil, 80% by mass or more hydrocarbon having a boiling point of 150*C and 35% by mass or more hydrocarbon having a boiling point of 360*C, though it is not limited to any specific FT synthetic oil as long as it is produced by FT synthesis. The term "total amount of FT synthetic oil" herein used means the total amount of hydrocarbons having 5 or more carbon atoms which are produced by FT synthesis. [0044] In first distillation column 10, two cut points are set to fractionate a raw material including FT synthetic oil, whereby the distillate lower than the first cut point can be obtained as a light distillate, the distillate between the first cut point and the second cut point as a middle distillate, and the distillate higher than the second cut point as bottom oil (heavy wax distillates). In this embodiment, a middle distillate, which contains 90% by mass or more distillates having a boiling point of 150 to 360*C, and a wax distillate, which is heavier than the middle distillate, are obtained by properly setting the first and second cut points. [0045] The content of the distillates having a boiling point of 150 to 360"C in the middle distillate can be obtained by, for example, analyzing the sample taken from the middle-distillate flow path L2 by a known method, such as gas chromatography. [0046] Preferably the above first and second cut points are set so that they fall in the range of 135 to 170*C and 330 to 370C, respectively, and more preferably in the range of 145 to 155*C and 355 to 365*C, 16 FP06-0522-00 respectively. [0047] The number of the cut points in the first distillation column is not limited to two, but three or more cut points can be set as long as the middle distillate and wax distillate as described above can be obtained. [0048](Hydrotreating of middle distillates) In hydrotreating unit 20, the middle distillate obtained in first distillation column 10 is hydrotreated. As hydrotreating unit 20, any known fixed bed reactor can be used. In this embodiment, preferably hydrotreating is carried out in a reaction column in such a manner as to pack specified hydrotreating catalyst into fixed bed flow reactor and then allow hydrogen and the middle distillate obtained in first distillation column 10 to flow through the reactor. The term hydrotreating " herein used includes both hydrocracking and hydroisomerization. The "cracking" means the chemical reaction involving the decrease in molecular weight of a molecule, while the "isomerization" means the transformation of a compound into a compound having the same molecular weight and carbon atom number, but a different carbon skeleton. [0049] Examples of hydrotreating catalysts include catalysts consisting of: a support that contains a solid acid; and metal, which is classified as the group VIII metal in the periodic table, supported on the support. [0050] Examples of suitable supports include: supports that contain one or more kinds of solid acids selected from the group consisting of crystalline zeolites, such as ultra-stable Y zeolite (USY), HY zeolite, mordenite and p zeolite, and amorphous metal oxides having heat resistance, such as silica-alumina, silica-zirconia and aluminaboria. 17 FP06-0522-00 Preferable are supports containing USY zeolite and one or more kinds of solid acids selected from the group consisting of silica-alumina, aluminaboria and silica-zirconia, and more preferable are supports containing USY zeolite and silica-alumina. [0051] USY zeolite is Y type zeolite having undergone hydrothermal treatment and/or acid treatment, thereby being made ultra stable. It has a micro porous structure with micropores of 20 A or smaller, which is intrinsic to Y type zeolite, and also has newly formed pores of 20 to 100 A. When using USY zeolite as a support for hydrotreating catalyst, preferably the average particle size of USY zeolite is, but not limited to, 1.0 pm or smaller and more preferably 0.5 gm or smaller. And in USY zeolite, the molar ratio of silica/alumina (the molar ratio of silica to alumina; hereinafter referred to as "silica/alumina ratio") is preferably 10 to 200, more preferably 15 to 100, and much more preferably 20 to 60. [0052] Preferably the support contains 0.1% by mass to 80% by mass crystalline zeolite and 0.1% by mass to 60% by mass amorphous metal oxide having heat resistance. [0053] The catalyst support can be prepared by shaping a mixture that contains the above solid acid(s) and binder and then firing the shaped mixture. The blend ratio of the solid acid(s) is, based on the entire amount of the support, preferably 1 to 70% by mass and more preferably 2 to 60% by mass. When the support contains USY zeolite, the amount of the USY zeolite blended is, based on the entire amount of the support, preferably 0.1 to 10% by mass and more preferably 0.5 to 5% by mass. When the support contains USY zeolite and 1Q FP06-0522-00 aluminaboria, the blend ration of USY zeolite to aluminaboria (USY zeolite/aluminaboria) is preferably 0.03 to I by mass. And when the support contains USY zeolite and silica-alumina, the blend ration of USY zeolite to silica-alumina (USY zeolite/silica-alumina) is preferably 0.03 to 1 by mass. [0054] As binder, preferable are, but not limited to, alumina, silica, silica-alumina, titania and magnesia, and more preferable is alumina. The blend ratio of the binder is, based on the entire amount of the support, preferably 20 to 98% by mass and more preferably 30 to 96% by mass. [0055] The firing temperature of the mixture is preferably within the range of 400 to 550*C, more preferably within the range of 470 to 530*C, and much more preferably within the range of 490 to 530'C. [0056] Concrete examples of the group VIII metals include: cobalt, nickel, rhodium, palladium, iridium and platinum. Of these metals, one of the metals selected from the group consisting of nickel, palladium, and platinum alone or the combination of two or more of the same is preferably used. [0057] These metals can be supported on the support described above by usual method such as impregnation or ion exchange. Preferably the amount of the metal(s) supported is, but not limited to, such that the total amount of the metal(s) is 0.1 to 3.0% by mass of the support. [0058] The hydrotreating of the middle distillate can be carried out under the following reaction conditions. Hydrogen partial pressure is in the range of 0.5 to 12 MPa and preferably in the range of 1.0 to 5.0 MPa. The liquid hourly space velocity (LHSV) is 0.1 to 10.0 h-1 and FP06-0522-00 preferably 0.3 to 3.5 h-'. The hydrogen/oil ratio is, but not limited to, 50 to 1000 NL/L and preferably 70 to 800 NL/L. [0059] The term "LHSV (liquid hourly space velocity)" herein used means the volumetric flow rate of crude oil per volume of a catalyst bed packed with the catalyst under standard conditions (25*C, 101325 Pa) and the unit 'W"' represents the reciprocal of the time (hour). The term "NL", which is the unit of hydrogen volume in the hydrogen/oil ratio, means the hydrogen volume (L) under normal conditions (0"C, 101325 Pa). [0060] The reaction temperature in the hydrotreating is 180 to 400*C, preferably 200 to 370*C, more preferably 250 to 350C, and much more preferably 280 to 350*C. If the reaction temperature is higher than 370C, unfavorably, a side reaction occurs more often which cracks the middle distillate into a naphtha distillate, resulting in an extreme decrease in the yield of the first and second fractions, and moreover, the product is colored, whereby the use of the distillate as a fuel base stock is limited. If the reaction temperature is lower than 200*C, unfavorably the alcohol content cannot be completely removed, thereby allowing some of the alcohol content to remain. [0061] In this embodiment, it is necessary to hydrotreat the middle distillate so that the increase in content (% by mass) of the hydrocarbons having a boiling point of 150*C or lower in the middle distillates after the contact with catalyst is 9% by mass or less. The "increase in content (% by mass) of the hydrocarbons having a boiling point of 150*C or lower" above used means the value obtained by subtracting the content (% by mass) of distillates having a boiling point of 150*C or FP06-0522-00 lower in the middle distillate before the contact with catalyst from the content (% by mass) of distillates having a boiling point of 150*C or lower in the middle distillate after the contact with catalyst. Preferably the middle distillate is hydrotreated so that the increase in content (% by mass) of isoparaffin in the middle distillate after the contact with catalyst is 30% by mass or more. The "increase in content (% by mass) of isoparaffin" above used means the value obtained by subtracting the content (% by mass) of isoparaffin in the middle distillate before the contact with catalyst from the content (% by mass) of isoparaffin in the middle distillate after the contact with catalyst. [0062] The contents (% by mass) of hydrocarbons having a boiling point of 150*C or lower in the middle distillates before and after the contact with catalyst can be obtained by, for example, analyzing the samples taken from the inlet and outlet of the reaction column by a known method, such as gas chromatography. And the contents (% by mass) of isoparaffin in the middle distillates before and after the contact with catalyst can be obtained by, for example, analyzing the samples taken from the inlet and outlet of the reaction column by a known method, such as gas chromatography. [0063] In the method for processing synthetic oil of the present invention, hydrotreating may be carried out under such reaction conditions that have been determined in advance, while checking the content of hydrocarbons having different numbers of carbon atoms in the middle distillates before and after the contact with catalyst by the above method, so that the increase in content (% by mass) of hydrocarbons having a boiling point of 150C or lower in the middle 21 FP06-0522-00 distillates before and after the contact with catalyst is 9% by mass or lower. Preferably, hydrotreating is carried out under such reaction conditions that have been determined in advance so that the increase in content (% by mass) of hydrocarbons having a boiling point of 150*C or lower in the middle distillate is 9% by mass or lower and the increase in content (% by mass) of isoparaflin in the middle distillate is 30% by mass or more. [0064](Hydrocracking of heavy wax distillates) In hydrocracking unit 30, the wax distillate obtained in first distillation column 10 are hydrocracked. As hydrocracking unit 30, any known fixed bed reaction column can be used. In this embodiment, preferably hydrocracking is carried out in a reaction column in such a manner as to pack specified hydrocracking catalyst into fixed bed flow reactor and then allow hydrogen and the wax distillate obtained in first distillation column 10 to flow through the reactor. In the hydrocracking of the wax distillate, mainly chemical reaction involving the decrease in molecular weight progresses; however, it also includes hydroisomerization. [0065] Examples of hydrocracking catalysts include catalysts consisting of: a support that contains a solid acid; and a metal species as active metal, which falls into the group VIII metal in the periodic table, supported on the support. [0066] Examples of suitable supports include: supports that contain one or more kinds of solid acids selected from the group consisting of crystalline zeolites, such as ultra-stable Y zeolite (USY), HY zeolite, mordenite and ( zeolite, and amorphous metal oxides having heat FP06-0522-00 resistance, such as silica-alumina, silica-zirconia and aluminaboria. Preferable are supports containing USY zeolite and one or more kinds of solid acids selected from the group consisting of silica-alumina, aluminaboria and silica-zirconia, and more preferable are supports containing USY zeolite and silica-alumina. [0067] USY zeolite is Y type zeolite having undergone hydrothermal treatment and/or acid treatment, thereby being made ultra stable. It has a micro porous structure with micropores of 20 A or smaller, which is intrinsic to Y type zeolite, and also has newly formed pores of 20 to 100 A. When using USY zeolite as a support for hydrocracking catalyst, preferably the average particle size of USY zeolite is, but not limited to, 1.0 pm or smaller and more preferably 0.5 pim or smaller. And in USY zeolite, the molar ratio of silica/alumina (the molar ratio of silica to alumina; hereinafter referred to as "silica/alumina ratio") is preferably 10 to 200, more preferably 15 to 100, and much more preferably 20 to 60. [0068] Preferably the support contains 0.1% by mass to 80% by mass crystalline zeolite and 0.1% by mass to 60% by mass amorphous metal oxide having heat resistance. [0069] The catalyst support can be prepared by shaping a mixture that contains the above solid acid(s) and binder and then firing the shaped mixture. The blend ratio of the solid acid(s) is, based on the entire amount of the support, preferably 1 to 70% by mass and more preferably 2 to 60% by mass. When the support contains USY zeolite, the amount of the USY zeolite blended is, based on the entire amount of the support, preferably 0.1 to 10% by mass and more preferably 0.5 to FP06-0522-00 5% by mass. When the support contains USY zeolite and aluminaboria, the blend ration of USY zeolite to aluminaboria (USY zeolite/aluminaboria) is preferably 0.03 to 1 by mass. And when the support contains USY zeolite and silica-alumina, the blend ration of USY zeolite to silica-alumina (USY zeolite/silica-alumina) is preferably 0.03 to 1 by mass. [0070] As binder, preferable are, but not limited to, alumina, silica, silica-alumina, titania and magnesia, and more preferable is alumina. The blend ratio of the binder is, based on the entire amount of the support, preferably 20 to 98% by mass and more preferably 30 to 96% by mass. [0071] The firing temperature of the mixture is preferably within the range of 400 to 550*C, more preferably within the range of 470 to 530*C, and much more preferably within the range of 490 to 530*C. [0072] Concrete examples of the group VIII metals include: cobalt, nickel, rhodium, palladium, iridium and platinum. Of these metals, one of the metals selected from the group consisting of nickel, palladium, and platinum alone or the combination of two or more of the same is preferably used. [0073] These metals can be supported on the support described above by usual method such as impregnation or ion exchange. Preferably the amount of the metal(s) supported is, but not limited to, such that the total amount of the metal(s) is 0.1 to 3.0% by mass of the support. [0074] The hydrocracking of the heavy wax distillate can be carried out under the following reaction conditions. Hydrogen partial pressure is in the range of 0.5 to 12 MPa and preferably in the range of 1.0 to 5.0 FP06-0522-00 MPa, The liquid hourly space velocity (LHSV) of the heavy wax distillate is 0.1 to 10.0 h~' and preferably 0.3 to 3.5 h~I. The hydrogen/oil ratio is, but not limited to, 50 to 1000 NL/L and preferably 70 to 800 NL/L. [0075] In this embodiment, preferably the wax distillate is hydrocracked so that the wax distillate after the contact with the hydrocracking catalyst contains a fraction having a boiling point of 360*C or lower at 45 to 85% by mass. In this case, the wax distillate can be hydrocracked so that the cracking ratio defined by the following equation (1) is 45 to 85% by mass. The cracking ratio expressed by equation (1) can be calculated using, for example, the measurements by gas chromatography of the hydrocracking products (oil and gas produced) of the wax distillate. [Equation 1] Cracking ratio (% by mass) = (Mass of distillates having a boiling point of 360*C or lower) / (Total mass of oil and gas produced) x 100 (1) [0076] The content of distillates having a boiling point of 360*C or lower in the wax distillates before and after the contact with catalyst can be obtained by, for example, analyzing the samples taken from the inlet and outlet of the reaction column by a known method, such as gas chromatography. [0077] In the method for processing synthetic oil of the present invention, hydrocracking may be carried out under the conditions which have been determined in advance, by the above method, so that the content of distillate having a boiling point of 360*C or lower in the wax FP06-0522-00 distillate after the contact with catalyst is 45 to 85% by mass. [0078](Fractional distillation of hydrotreating products) The middle distillate after hydrotreating (hereinafter sometimes referred to as "hydrotreating product") which flows out from hydrotreating unit 20 is passed through a gas-liquid separation tank and transferred to a second distillation column 40 where it is fractionated into specified distillates. [0079] In the gas-liquid separation tank, the above hydrotreating product is separated into: for example, light hydrocarbon gas consisting of unreacted hydrogen gas and hydrocarbons having 4 or less carbon atoms; and liquid hydrocarbon composition oil consisting of hydrocarbons having 5 or more carbon atoms. In this case, the liquid hydrocarbon composition oil is transferred, as a hydrotreating product, to second distillation column 40. As a gas-liquid separation tank, a known one can be used. [0080] In second distillation column 40, two cut points are set to fractionate the hydrotreating product, whereby the distillate lower than the first cut point can be obtained as a naphtha distillate, the distillate between the first cut point and the second cut point as light middle distillate (first fraction), and the distillate higher than the second cut point as heavy middle distillate (second fraction). In this embodiment, the light middle distillate (first fraction) is fractionated so that it contains 90% by mass or more distillate having a boiling point of 150 to 250'C, and such light middle distillate (first fraction) is taken out from flow path L6 as the hydrocarbon oil for hydrogen production or for use in kerosene smoke point improver of the present invention. The heavy FP06-0522-00 middle distillate (second fraction) taken out from flow path L7 is mixed with the third fraction described later. And the mixture is taken out from flow path L13 as the hydrocarbon oil for use in a diesel fuel base stock of the present invention. [0081] Preferably the above first and second cut points are set so that they fall within the range of 135 to 170*C and within the range of 210 to 265*C, respectively, and more preferably within the range of 145 to 155*C and within the range of 230 to 260*C, respectively. [0082] The number of the cut points in second distillation column 40 is not limited to two, but three or more cut points can be set as long as the distillates of the present invention can be obtained. [0083](Fractional distillation of hydrocracking product) The wax distillate after hydrocracking (hereinafter sometimes referred to as "hydrocracking product") which flows out from hydrocracking unit 30 is passed through a gas-liquid separation tank and transferred to third distillation column 50 where it is fractionated into specified distillates. [0084] In the gas-liquid separation tank, the above hydrocracking product is separated into: for example, light hydrocarbon gas consisting of unreacted hydrogen gas and hydrocarbons having 4 or less carbon atoms; and liquid hydrocarbon composition oil consisting of hydrocarbons having 5 or more carbon atoms. In this case, the liquid hydrocarbon composition oil is transferred, as a hydrocracking product, to third distillation column 50. As a gas-liquid separation tank, a known one can be used. [0085] In third distillation column 50, two cut points are set to T7 FP06-0522-00 fractionate the hydrocracking product, whereby the distillate lower than the first cut point can be obtained as cracked naphtha distillate, the distillate between the first cut point and the second cut point as cracked middle distillate (third fraction), and the distillate higher than the second cut point as a bottom distillate (uncracked distillate). In this embodiment, the cracked middle distillate (third fraction) is fractionated so that it contains 90% by mass or more distillate having a boiling point of 150 to 360*C, and the cracked middle distillate (third fraction) taken out from flow path L1O is mixed with the heavy middle distillate (second fraction) described above. This mixture is taken out from flow path L13 as the hydrocarbon oil for use in a diesel fuel base stock of the present invention. [0086] Preferably, the above first and second cut points are set so that they fall within the range of 135 to 170*C and within the range of 345 to 375*C, respectively, and more preferably within the range of 145 to 155*C and within the range of 355 to 365C, respectively. [0087] The number of the cut points in third distillation column 50 is not limited to two, but three or more cut points can be set as long as the above cracked middle distillate (third fraction) of the present invention can be obtained. [0088] Part of or the whole of the uncracked wax distillate, which is heavier than the cracked middle distillate (third fraction) obtained as above, is fed to hydrocracking unit 30 through circulation flow path L 1, depending on the situation, so that it undergoes hydrocracking. [0089](Supply as a product) The light middle distillate (first fraction) obtained in second FP06-0522-00 distillation column 40 is, for example, accumulated in the as fractionated state in a product tank and used as a hydrocarbon oil for hydrogen production or in kerosene smoke point improver. [0090] In hydrocarbon oil production apparatus 100 shown in FIG 1, the heavy middle distillate (second fraction) obtained in second distillation column 40 and the cracked middle distillate (third fraction) obtained in third distillation column 50 are mixed in flow path L13. However, they may be mixed suitably after being accumulated in different product tanks or they may be mixed in a single product tank, before used as hydrocarbon oil for use in a diesel fuel base stock. [0091] When producing a diesel fuel base stock by mixing the heavy middle distillate (second fraction) and the cracked middle distillate (third fraction), a suitable amount of light middle distillate (first fraction) can also be mixed, provided that the kinematic viscosity of the resultant mixture is kept 2.5 mm 2 /s or higher at 30*C, so as to lower the pour point of the fuel base stock depending on the situation. [0092] According to the above described method for processing synthetic oil of the present invention, both hydrocarbon oil for use in a diesel fuel base stock having a pour point of -7.5*C or lower and a kinematic viscosity of 2.5 mm 2 /s or higher at 30*C and hydrocarbon oil for hydrogen production or in kerosene smoke point improver having a smoke point of 44 mm or higher can be obtained in a high yield. The hydrocarbon oil for use in a diesel fuel base stock thus obtained is suitably used as, for example, a base stock for diesel fuel with low environmental impact. And the hydrocarbon oil for hydrogen production thus obtained allows the decrease in hydrogen production FP06-0522-00 capacity of hydrogen production unit to be kept sufficiently small; thus, use of such hydrocarbon oil as a raw material for hydrogen production enables the hydrogen production at lower costs. The hydrocarbon oil for use in kerosene smoke point improver thus obtained can produce, when blended with inferior quality kerosene having a smoke point of 22 mm or less, the effect of improving the smoke point to 2.3 mm or more, in terms of the value when the blend ratio is 10% by mass (based on the total amount of the kerosene after blended with the hydrocarbon oil), thereby enabling the increase in kerosene production at low costs. [0093] The method for producing hydrocarbon oils of the present invention is to obtain the first fraction and the mixture of the second and third fractions in the method for processing synthetic oil of the present invention as hydrocarbon oils. When the first fraction is obtained as hydrocarbon oil for hydrogen production and the mixture of the second and third fractions as hydrocarbon oil for use in a diesel fuel base stock, the method for producing hydrocarbon oils in accordance with the embodiment of the present invention can be used as a method that permits economical production of hydrocarbon oils for use in hydrogen production and in a diesel fuel base stock. Further, when the first fraction is obtained as hydrocarbon oil for use in kerosene smoke point improver and the mixture of the second and third fractions as hydrocarbon oil for use in a diesel fuel base stock, the method of producing hydrocarbon oils in accordance with the embodiment of the present invention can be used as a method that permits economical manufacturing of hydrocarbon oils for use in kerosene smoke point improver and in a diesel fuel base stock.
FP06-0522-00 EXAMPLES [0094] In the following the present invention will be described in more detail by purely illustrative and non-limiting examples. [0095] First, an example will be described in which hydrocarbon oils for use in hydrogen production and in a diesel fuel base stock are produced from FT synthetic oil. [0096]<Preparation of catalyst> (Catalyst A) USY zeolite (the silica/alumina molar ratio: 37) having an average particle size of 1.1 pm, silica-alumina (the silica/alumina molar ratio: 14), and alumina binder were mixed at a weight ratio of 3 : 57 : 40 and kneaded, shaped into cylinders 1.6 mm in diameter and about 4 mm in length, and fired at 500'C for one hour to produce supports. The supports were impregnated with an aqueous solution of chloroplatinic acid so that platinum was supported on and in each of the supports. The supports were then dried at 120'C for 3 hours and fired at 500*C for 1 hour to prepare catalyst A. The amount of platinum supported on a support was 0.8% by mass of the support. [0097]<Processing of FT synthetic oil> (Example 1) (Fractional distillation of FT synthetic oil) Oil produced by FT synthesis (FT synthetic oil) (the content of hydrocarbons having a boiling point of 150*C or higher: 82% by mass, the content of hydrocarbons having a boiling point of 360*C or higher: 41% by mass, both are based on the whole amount of FT synthetic oil (the total amount of hydrocarbons having 5 or more carbon atoms)) was FP06-0522-00 separated, in a distillation column, into: a light distillate having a boiling point of 150*C or lower; a FT middle distillate having a boiling point of 150 to 360*C (the content of hydrocarbons having a boiling point of 150 to 360*C is 100% by mass, the content of hydrocarbons having a boiling point of 300 to 360*C is 25% by mass, and the content of hydrocarbons having a boiling point of 150*C or lower is 0% by mass); and a bottom residue heavy FT wax distillate (corresponding to distillate having a boiling point of 360C or higher). [0098](Hydrotreating of FT middle distillate) Catalyst A (100 ml) was packed into fixed bed flow reactor, and the FT middle distillate obtained above was fed from the top of the reaction column at a feeding rate of 200 ml/h to hydrotreat the distillate in a stream of hydrogen under the following reaction conditions. [0099] Specifically, hydrogen was fed from the top of the column to the middle distillate at hydrogen/oil ratio of 340 NL/L, the back pressure regulating valve was adjusted so that the inlet pressure of the reaction column was kept constant, at 3.0 MPa, and under these conditions the reaction temperature (weight averaged catalyst bed temperature) was controlled so that the content of the hydrocarbons having a boiling point of 150*C or lower in the middle distillate after hydrotreating (in the hydrotreating product) was 7% by mass. The reaction temperature thus controlled was 311*C. The content of the hydrocarbons described above was confirmed by gas chromatography of the middle distillate after hydrotreating (hydrotreating products). [0100](Hydrocracking of FT wax distillate) In another reaction column, catalyst A (100 ml) was packed into FP06-0522-00 fixed bed flow reactor, and the bottom residue heavy FT wax distillate obtained above was fed from the top of the reaction column at a feeding rate of 200 ml/h to hydrocrack the distillate in a stream of hydrogen under the following reaction conditions. [0101] Specifically, hydrogen was fed from the top of the column to the wax distillate at hydrogen/oil ratio of 680 NL/L, the back pressure regulating valve was adjusted so that the inlet pressure of the reaction column was kept constant, at 4.0 MPa, and under these conditions the reaction temperature (weight averaged catalyst bed temperature) was controlled so that the content of the distillates having a boiling point of 360C or lower in the wax distillate after hydrocracking (in the hydrocracking product) was about 70% by mass (the cracking ratio defined by the above equation (1) is about 70% by mass). The reaction temperature thus controlled was 326*C. The. content of the distillate (cracking ratio) described above was confirmed by gas chromatography of the wax distillate after hydrocracking (hydrocracking products) and analysis of the distillation characteristics. [0102](Fractional distillation of hydrotreating product) The hydrotreating product of the FT middle distillate obtained above was fractionated in a distillation column to obtain distillate having a boiling point of 150 to 250*C as light middle distillate and distillate having a boiling point of 250*C or higher as heavy middle distillate. [0103](Fractional distillation of hydrocracking product) The hydrocracking product of the FT wax distillate obtained above was fractionated in a distillation column to obtain distillate FP06-0522-00 having a boiling point of 150 to 360*C as cracked middle distillate. [0104](Preparation of hydrocarbon oils for use in hydrogen production and in a diesel fuel base stock) The whole amount of the light middle distillate obtained above was used as a hydrocarbon oil for hydrogen production of Example 1. The heavy middle distillate and cracked middle distillate above were mixed at the ratio corresponding to that of their yields and the mixture was used as a hydrocarbon oil for use in a diesel fuel base stock of Example 1. [0105] The yields of the FT middle distillate and FT wax distillate obtained by the fractional distillation of FT synthetic oil, the yields of the light middle distillate and heavy middle distillate obtained by the hydrotreating of the FT middle distillate, the yield of the cracked middle distillate obtained by the hydrocracking of the FT wax distillate, and the yields of the hydrocarbon oils for use in hydrogen production and in a diesel fuel base stock are shown in Table 1. And the increase (% by mass) in the content (% by mass) of isoparaffin in the hydrotreating ([the content (% by mass) of isoparaffin in the FT middle distillate after hydrotreating] - [the content (% by mass) of isoparaffin in the FT middle distillate before hydrotreating]) is also shown in Table 1. [0106](Example 2) The hydrocarbon oils for use in hydrogen production and in a diesel fuel base stock of Example 2 were obtained in the same manner as those of Example 1, provided that in the hydrocracking of the FT wax distillate, the reaction temperature (weight averaged catalyst bed temperature) was controlled so that the content of the distillate having a 2I A FP06-0522-00 boiling point of 360*C or lower in the wax distillate after hydrocracking (hydrocracking product) was about 46% by mass (the cracking ratio defined by the above equation (1) was about 46% by mass). The reaction temperature thus controlled was 315*C. [0107] The yields of the FT middle distillate and FT wax distillate obtained by the fractional distillation of FT synthetic oil, the yields of the light middle distillate and heavy middle distillate obtained by the hydrotreating of the FT middle distillate, the yield of the cracked middle distillate obtained by the hydrocracking of the FT wax distillate, the yields of the hydrocarbon oils for use in hydrogen production and in a diesel fuel base stock, and the increase (% by mass) in the content (% by mass) of isoparaffin in the hydrotreating are shown in Table 1. [0108](Example 3) The hydrocarbon oils for use in hydrogen production and in a diesel fuel base stock of Example 3 were obtained in the same manner as those of Example 1, provided that in the hydrocracking of the FT wax distillate, the reaction temperature (weight averaged catalyst bed temperature) was controlled so that the content of the distillate having a boiling point of 360*C or lower in the wax distillate after hydrocracking (hydrocracking product) was about 84% by mass (the cracking ratio defined by the above equation (1) was about 84% by mass). The reaction temperature thus controlled was 33 1C. [0109] The yields of the FT middle distillate and FT wax distillate obtained by the fractional distillation of FT synthetic oil, the yields of the light middle distillate and heavy middle distillate obtained by the hydrotreating of the FT middle distillate, the yield of the cracked middle FP06-0522-00 distillate obtained by the hydrocracking of the FT wax distillate, the yields of the hydrocarbon oils for use in hydrogen production and in a diesel fuel base stock, and the increase (% by mass) in the content (% by mass) of isoparaffin in the hydrotreating are shown in Table 1. [011 0](Example 4) The hydrocarbon oils for use in hydrogen production and in a diesel fuel base stock of Example 4 were obtained in the same manner as those of Example 1, provided that the hydrocracking of the FT wax distillate was carried out under the conditions below, on the assumption that circulation of uncracked wax distillate would be carried out. [0111] Specifically, as a FT wax distillate subject to hydrocracking, was prepared one obtained by mixing the FT wax distillate and the wax distillate having a boiling point of 360'C or higher which was obtained by the hydrocracking of the FT wax distillate (uncracked wax distillate) at a mass ratio of 100 : (100 - 84). The mixture was fed from the top of the reaction column at a feeding rate of 116 ml/h, hydrogen was fed from the top of the column to the mixture at hydrogen/oil ratio of 680 NL/L, the back pressure regulating valve was adjusted so that the inlet pressure of the reaction column was kept constant, at 4.0 MPa, and under these conditions the reaction temperature (weight averaged catalyst bed temperature) was controlled so that the content of the distillates having a boiling point of 360*C or lower in the mixture after hydrocracking (hydrocracking product) was about 84% by mass (the cracking ratio defined by the above equation (1) was about 84% by mass). The reaction temperature thus controlled was 334 0 C. [0112] The yields of the FT middle distillate and FT wax distillate 36 FP06-0522-00 obtained by the fractional distillation of FT synthetic oil, the yields of the light middle distillate and heavy middle distillate obtained by the hydrotreating of the FT middle distillate, the yield of the cracked middle distillate obtained by the hydrocracking of the FT wax distillate, the yields of the hydrocarbon oils for use in hydrogen production and in a diesel fuel base stock, and the increase (% by mass) in the content (% by mass) of isoparaffin in the hydrotreating are shown in Table 1. [0113](Example 5) The hydrocarbon oils for use in hydrogen production and in a diesel fuel base stock of Example 5 were obtained in the same manner as those of Example 1, provided that the hydrocracking of the FT wax distillate was carried out under the conditions below, on the assumption that circulation of uncracked wax distillate would be carried out. [0114] Specifically, as a FT wax distillate subject to hydrocracking, was prepared one obtained by mixing the FT wax distillate and the wax distillate having a boiling point of 360'C or higher which was obtained by the hydrocracking of the FT wax distillate (uncracked wax distillate) at a mass ratio of 100 : (100 - 46). The mixture was fed from the top of the reaction column at a feeding rate of 154 ml/h, hydrogen was fed from the top of the column to the mixture at hydrogen/oil ratio of 680 NL/L, the back pressure regulating valve was adjusted so that the inlet pressure of the reaction column was kept constant, at 4.0 MPa, and under these conditions the reaction temperature (weight averaged catalyst bed temperature) was controlled so that the content of the distillates having a boiling point of 360*C or lower in the mixture after hydrocracking (hydrocracking product) was about 46% by mass (the FP06-0522-00 cracking ratio defined by the above equation (1) was about 46% by mass). The reaction temperature thus controlled was 319*C. [0115] The yields of the FT middle distillate and FT wax distillate obtained by the fractional distillation of FT synthetic oil, the yields of the light middle distillate and heavy middle distillate obtained by the hydrotreating of the FT middle distillate, the yield of the cracked middle distillate obtained by the hydrocracking of the FT wax distillate, the yields of the hydrocarbon oils for use in hydrogen production and in a diesel fuel base stock, and the increase (% by mass) in the content (% by mass) of isoparafFin in the hydrotreating are shown in Table 1. [011 6](Comparative Example 1) The hydrocarbon oils for use in hydrogen production and in a diesel fuel base stock of Comparative Example 1 were obtained in the same manner as those of Example 1, provided that in the hydrotreating of the FT middle distillate, the reaction temperature (weight averaged catalyst bed temperature) was controlled so that the content of the hydrocarbons having a boiling point of 150*C or lower in the middle distillate after hydrotreating (hydrotreating product) was 15% by mass. The reaction temperature thus controlled was 321*C. [0117] The yields of the FT middle distillate and FT wax distillate obtained by the fractional distillation of FT synthetic oil, the yields of the light middle distillate and heavy middle distillate obtained by the hydrotreating of the FT middle distillate, the yield of the cracked middle distillate obtained by the hydrocracking of the FT wax distillate, the yields of the hydrocarbon oils for use in hydrogen production and in a diesel fuel base stock, and the increase (% by mass) in the content (% FP06-0522-00 by mass) of isoparaffin in the hydrotreating are shown in Table 1. [011 8](Comparative Example 2) The hydrocarbon oil for hydrogen production and for a diesel fuel base stock of Comparative Example 2 were obtained differently from those of Example 1, in such a way that the mixture of the light middle distillate and the heavy middle distillate obtained by mixing the same at the ratio corresponding to that of their yields was used, instead of the light middle distillate, as a hydrocarbon oil for hydrogen production and the cracked middle distillate was used, instead of the mixture of the heavy middle distillate and the cracked middle distillate, as a hydrocarbon oil for a diesel fuel base stock. [0119] The yields of the FT middle distillate and FT wax distillate obtained by the fractional distillation of FT synthetic oil, the yields of the light middle distillate and heavy middle distillate obtained by the hydrotreating of the FT middle distillate, the yield of the cracked middle distillate obtained by the hydrocracking of the FT wax distillate, the yields of the hydrocarbon oils for use in hydrogen production and in a diesel fuel base stock, and the increase (% by mass) in the content (% by mass) of isoparaffin in the hydrotreating are shown in Table 1. [0120](Comparative Example 3) The hydrocarbon oil for a diesel fuel base stock of Comparative Example 3 was obtained as the mixture of the light middle distillate, heavy middle distillate and cracked middle distillate, which was obtained by mixing the same at the ratio corresponding to that of their yields was used, though the light middle distillate obtained above was used as a hydrocarbon oil for hydrogen production, and the mixture of FP06-0522-00 the heavy middle distillate and the cracked middle distillate as a hydrocarbon oil for a diesel fuel base stock. [0121] The yields of the FT middle distillate and FT wax distillate obtained by the fractional distillation of FT synthetic oil, the yields of the light middle distillate and heavy middle distillate obtained by the hydrotreating of the FT middle distillate, the yield of the cracked middle distillate obtained by the hydrocracking of the FT wax distillate, the yields of the hydrocarbon oils for use in hydrogen production and in a diesel fuel base stock, and the increase (% by mass) in the content (% by mass) of isoparaffin in the hydrotreating are shown in Table 1. [0122] A A FP06-0522-00 [Table 1] Ex. I Ex. 2 Ex. 3 Ex. 4 Ex. 5 Com. Ex 1 Con. Ex. 2 Com. Ex 3 Yield (% by mass) of FT middle distillate (having a boiling point in the 50 50 50 50 50 50 50 50 range of 150 to 360*C) *1 Yield (% by mass) of Fr wax distillate 50 50 50 50 50 50 50 50 Yield (% by mass) of naphtha distillate (having a boiling point of 150*C or 7 7 7 7 7 15 7 7 lower) obtained by hydrotreating *2 Increase (% by mass) in content (% by 34 34 34 34 34 46 34 34 mass) of isoparaffin in hydrotreating Yield (% by mass) of light middle distillate (having a boiling point in the 42 42 42 42 42 40 42 42 range of 150 to 250"C) obtained by hydrotreating *2 Yield (% by mass) of heavy middle distillate (having a boiling point in the 50 50 50 50 50 43 50 50 range of 250 to 360"C) obtained by hydrotreating *2 Cracking ratio (% by mass) in 70 46 84 84 46 46 70 70 hydrocracking of FT wax distillate Presence or absence of circulation of uncracked wax distillate in absent absent absent present present absent absent absent hydrocracking of FT wax distillate Yield (%/ by mass) of cracked middle distillate (having a boiling point in the 52 42 57 68 91 42 52 52 range of 150 to 360"C) obtained by hydrocracking *3 Yield (/ by mass) of hydrocarbon oil 21 21 21 21 21 20 46 0 for hydrogen production *1 Yield (% by mass) of hydrocarbon oil 51 46 53.5 57 70.5 42.5 26 72 for use in a diesel fuel base stock *I Total yield (% by mass) of hydrocarbon oils for use in hydrogen production and 72 67 74.5 78 91.5 62.5 72 72 in a diesel fuel base stock *I *1: Yield to distillate having a boiling point of 150*C or higher in FT synthetic oil *2: Yield to FT middle distillate *3: Yield to FT wax distillate FP06-0522-00 [0123](Evaluation of hydrocarbon oils for use in hydrogen production and in a diesel fuel base stock) The hydrocarbon oils for use in hydrogen production and in a diesel fuel base stock of Examples 1 to 5 and Comparative Examples 1 to 3 were evaluated as follows. The results are shown in Table 2. [0124]<Evaluation of hydrocarbon oil for hydrogen production> Each of the obtained hydrocarbon oils for use in hydrogen production was evaluated for its ability to maintain the hydrogen production capacity of a hydrogen production unit, by determining the loss rate of hydrogen production capacity based on the method described below. [0125] A schematic block diagram of testing machine for hydrogen production capacity is shown in FIG 2 which was used to obtain the decrease in hydrogen production capacity of hydrogen production unit. The configuration of testing machine 200 for hydrogen production capacity is shown in FIG 2, where it includes: tank 51 which contains a hydrocarbon oil for hydrogen production; tank 52 which contains water; fuel preheater 53 which heats the hydrocarbon oil for hydrogen production fed from tank 51 through flow path L21 and converts the same into fuel vapor; steam generator 54 which heats the water fed from tank 52 through flow path L22 and converts the same into steam; reformer 55 which allows the fuel vapor fed from fuel preheater 53 through flow path L23 and the steam fed from steam generator 54 through flow path L24 to react with each other to cause steam reforming reaction; gas flow meter 56 which measures the amounts of the reformed gases (H 2 , CO, CO 2 , CI 4 ) and unreacted gases flowing out FP06-0522-00 from reformer 55 through flow path L25; and gas chromatograph 57 which analyzes the gas composition of the reformed gas (H2, CO, C0 2 ,
CH
4 ) and unreacted gas flowing out from reformer 55 through flow path L25. [0126] Tank 51 and tank 52 are placed on the respective balances 60, whereby the amounts of the hydrocarbon oil for hydrogen production and water fed to reformer 55, per hour, can be measured. [0127] Reformer 55 has a reforming tube reactor packed with reforming catalyst (ruthenium-based, 9: 2 mm, pack quantity: 5 mL). The tube reactor is kept at a specified temperature with electric heater (not shown in the figure) andconverts the fuel vapor feed and steam into hydrogen rich reformed gas. [0128](Calculation of decrease in hydrogen production capacity) The steam reforming reaction of each hydrocarbon oil for hydrogen production was performed under the following conditions using testing machine 200 for hydrogen production capacity described above, and the conversion defined by the following equation (A) was obtained. The conversion was represented by CVI(%). [Reaction conditions 1] LHSV: 0.5 h- 1 , S/C (the number of moles of water molecules/the number of moles of carbon atoms): 3 mol/mol, Outlet temperature of reforming catalyst bed: 650*C [0129] [Equation 2] Conversion (%) [Number of moles of C1 (the sum of C0 2 , CO and CH 4 ) in the reformed gas generated] x100 [Number of moles of carbon atoms in the hydrocarbon oil feed for hydrogen production]
.(A)
FP06-0522-00 [0130] Then, the steam reforming reaction of each hydrocarbon oil for hydrogen production was performed for 100 hours under the following conditions. [Reaction conditions 2] LHSV: 5 h-I, S/C (the number of moles of water molecules/the number of moles of carbon atoms): 3 mol/mol, Outlet temperature of reforming catalyst bed: 650*C [0131] Subsequently after that, the steam reforming reaction of each hydrocarbon oil for hydrogen production was performed again under the reaction conditions 1, and the conversion defined by the above equation (A) was obtained. The conversion was represented by CV 2 (%). [0132] Using CVI(%) and CV 2 (%), the decrease (%) in hydrogen generation performance defined by the following equation (B) was calculated. The results are shown in Table 2. [0133] [Equation 3] Decrease (%) in hydrogen generation performance= - CV 2 ) x 100 -..(B) CV, [0134]<Measurement of smoke point of hydrocarbon oil for hydrogen production> The smoke point (mm) of each of the obtained hydrocarbon oils for use in hydrogen production was measured in accordance with the test method specified in JIS K2537. [0135]<Kinematic viscosity and pour point of hydrocarbon oil for use in a diesel fuel base stock > The kinematic viscosity (mm 2 /s) at 30*C of each of the obtained hydrocarbon oils for use in a diesel fuel base stock was measured in FP06-0522-00 accordance with the test method specified in JIS K2283 and the pour point (*C) of the same in accordance with the test method specified in JIS K2269. [0136] [Table 2] Ex I Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. Ex. Ex.3 Decrease (%) in hydrogen production capacity 0.5 0.5 0.5 0.5 0.5 1.0 28.2 caused by hydrocarbon oil for hydrogen production Smoke point (mm) of hydrocarbon oil for 44 44 44 44 44 44 44 hydrogen production Kinematic viscosity (mm 2 /s) at 30 0 C of 2.7 2.9 2.6 2.5 2.7 2.7 2.4 2.4 hydrocarbon oil for use in a diesel fuel base stock Pour point ("C) of hydrocarbon oil for use in -10 -7.5 -12.5 -15 -10 -10 -17.5 -10 a diesel fuel base stock I I [0137] The results shown in Table 1 and Table 2 prove that, according to any one of the method for processing synthetic oil of Examples 1 to 5, it is possible to obtain from FT synthetic oil, in a high yield, both hydrocarbon oil for hydrogen production capable of restraining the decrease in hydrogen production capacity to 0.5% and sufficiently maintaining the hydrogen generating efficiency for a long time and hydrocarbon oil for use in a diesel fuel base stock having sufficiently improved pour point and kinematic viscosity at 30*C. [0138] In the following, examples will be described of producing hydrocarbon oils for use in kerosene smoke point improver and in a diesel fuel base stock from FT synthetic oil. [0139]<Preparation of catalyst> FP06-0522-00 Catalyst A described above was prepared. [0140]<Processing of FT synthetic oil> (Example 6) (Fractional distillation of FT synthetic oil) Oil produced by FT synthesis (FT synthetic oil) (the content of hydrocarbons having a boiling point of 150*C or higher: 82% by mass, the content of hydrocarbons having a boiling point of 360*C or higher: 41% by mass, both are based on the whole amount of FT synthetic oil (the total amount of hydrocarbons having 5 or more carbon atoms)) was separated, in a distillation column, into: light distillate having a boiling point of 150*C or lower, FT middle distillate having a boiling point of 150 to 360*C (the content of hydrocarbons having a boiling point of 150 to 360*C is 100% by mass, the content of hydrocarbons having a boiling point of 300 to 360"C is 25% by mass, and the content of hydrocarbons having a boiling point of 150*C or lower is 0% by mass); and bottom residue heavy FT wax distillate (corresponding to distillate having a boiling point of 360*C or higher). [0141](Hydrotreating of FT middle distillate) Catalyst A (100 ml) was packed into fixed bed flow reactor, and the FT middle distillate obtained above was fed from the top of the reaction column at a feeding rate of 200 ml/h to hydrotreat the distillate in a stream of hydrogen under the following reaction conditions. [0142] Specifically, hydrogen was fed from the top of the column to the middle distillate at hydrogen/oil ratio of 340 NL/L, the back pressure regulating valve was adjusted so that the inlet pressure of the reaction column was kept constant, at 3.0 MPa, and under these conditions the FP06-0522-00 reaction temperature (weight averaged catalyst bed temperature) was controlled so that the content of the hydrocarbons having a boiling point of 150 0 C or lower in the middle distillate after hydrotreating (in the hydrotreating product) was 7% by mass. The reaction temperature thus controlled was 311*C. The content of the hydrocarbons described above was confirmed by gas chromatography of the middle distillate after hydrotreating (hydrotreating products). [0143](Hydrocracking of FT wax distillate) In another reaction column, catalyst A (100 ml) was packed into fixed bed flow reactor, and the bottom residue heavy FT wax distillate obtained above was fed from the top of the reaction column at a feeding rate of 200 ml/h to hydrocrack the distillate in a stream of hydrogen under the following reaction conditions. [0144] Specifically, hydrogen was fed from the top of the column to the wax distillate at hydrogen/oil ratio of 680 NL/L, the back pressure regulating valve was adjusted so that the inlet pressure of the reaction column was kept constant, at 4.0 MPa, and under these conditions the reaction temperature (weight averaged catalyst bed temperature) was controlled so that the content of the distillates having a boiling point of 360*C or lower in the wax distillate after hydrocracking (in the hydrocracking product) was about 70% by mass (the cracking ratio defined by the above equation (1) is about 70% by mass). The reaction temperature thus controlled was 326*C. The content of the distillate (cracking ratio) described above was confirmed by gas chromatography of the wax distillate after hydrocracking (hydrocracking products) and analysis of the distillation characteristics. A PT FP06-0522-00 [0145](Fractional distillation of hydrotreating product) The hydrotreating product of the FT middle distillate obtained above was fractionated in a distillation column to obtain distillate having a boiling point of 150 to 250'C as light middle distillate and distillate having a boiling point of 250*C or higher as heavy middle distillate. [01 46](Fractional distillation of hydrocracking product) The hydrocracking product of the FT wax distillate obtained above was fractionated in a distillation column to obtain distillate having a boiling point of 150 to 360'C as cracked middle distillate. [0147](Preparation of hydrocarbon oils for use in kerosene smoke point improver and in a diesel fuel base stock) The whole amount of the light middle distillate obtained above was used as a hydrocarbon oil for use in kerosene smoke point improver of Example 6. The heavy middle distillate and cracked middle distillate obtained above were mixed at the ratio corresponding to that of their yields and the mixture was used as a hydrocarbon oil for use in a diesel fuel base stock of Example 6. [0148] The yields of the FT middle distillate and FT wax distillate obtained by the fractional distillation of FT synthetic oil, the yields of the light middle distillate and heavy middle distillate obtained by the hydrotreating of the FT middle distillate, the yield of the cracked middle distillate obtained by the hydrocracking of the FT wax distillate, and the yields of the hydrocarbon oils for use in kerosene smoke point improver and in a diesel fuel base stock are shown in Table 3. And the increase (% by mass) in the content (% by mass) of isoparaffin in the FPO6-0522-00 hydrotreating ([the content (% by mass) of isoparaffin in the FT middle distillate after hydrotreating] - [the content (% by mass) of isoparaffin in the FT middle distillate before hydrotreating]) is also shown in Table 3. [0149](Example 7) The hydrocarbon oils for use in kerosene smoke point improver and in a diesel fuel base stock of Example 7 were obtained in the same manner as those of Example 6, provided that in the hydrocracking of the FT wax distillate, the reaction temperature (weight averaged catalyst bed temperature) was controlled so that the content of the distillate having a boiling point of 360*C or lower in the wax distillate after hydrocracking (hydrocracking product) was about 46% by mass (the cracking ratio defined by the above equation (1) was about 46% by mass). The reaction temperature thus controlled was 315*C. [0150] The yields of the FT middle distillate and FT wax distillate obtained by the fractional distillation of FT synthetic oil, the yields of the light middle distillate and heavy middle distillate obtained by the hydrotreating of the FT middle distillate, the yield of the cracked middle distillate obtained by the hydrocracking of the FT wax distillate, the yields of the hydrocarbon oils for use in kerosene smoke point improver and in a diesel fuel base stock, and the increase (% by mass) in the content (% by mass) of isoparaffin in the hydrotreating are shown in Table 3. [015 1](Example 8) The hydrocarbon oils for use in kerosene smoke point improver and in a diesel fuel base stock of Example 8 were obtained in the same manner as those of Example 6, provided that in the hydrocracking of the FP06-0522-00 FT wax distillate, the reaction temperature (weight averaged catalyst bed temperature) was controlled so that the content of the distillate having a boiling point of 360*C or lower in the wax distillate after hydrocracking (hydrocracking product) was about 84% by mass (the cracking ratio defined by the above equation (1) was about 84% by mass). The reaction temperature thus controlled was 33 1C. [0152] The yields of the FT middle distillate and FT wax distillate obtained by the fractional distillation of FT synthetic oil, the yields of the light middle distillate and heavy middle distillate obtained by the hydrotreating of the FT middle distillate, the yield of the cracked middle distillate obtained by the hydrocracking of the FT wax distillate, the yields of the hydrocarbon oils for use in kerosene smoke point improver and in a diesel fuel base stock, and the increase (% by mass) in the content (% by mass) of isoparaffin in the hydrotreating are shown in Table 3. [0153](Example 9) The hydrocarbon oils for use in kerosene smoke point improver and in a diesel fuel base stock of Example 9 were obtained in the same manner as those of Example 6, provided that the hydrocracking of the FT wax distillate was carried out under the conditions below, on the assumption that circulation of uncracked wax distillate would be carried out. [0154] Specifically, as a FT wax distillate subject to hydrocracking, was prepared one obtained by mixing the FT wax distillate and the wax distillate having a boiling point of 360*C or higher which was obtained by the hydrocracking of the FT wax distillate (uncracked wax distillate) FP06-0522-00 at a mass ratio of 100 : (100 - 84). The mixture was fed from the top of the reaction column at a feeding rate of 116 ml/h, hydrogen was fed from the top of the column to the mixture at hydrogen/oil ratio of 680 NL/L, the back pressure regulating valve was adjusted so that the inlet pressure of the reaction column was kept constant, at 4.0 MPa, and under these conditions the reaction temperature (weight averaged catalyst bed temperature) was controlled so that the content of the distillates having a boiling point of 360*C or lower in the mixture after hydrocracking (hydrocracking product) was about 84% by mass (the cracking ratio defined by the above equation (1) was about 84% by mass). The reaction temperature thus controlled was 334*C. [0155] The yields of the FT middle distillate and FT wax distillate obtained by the fractional distillation of FT synthetic oil, the yields of the light middle distillate and heavy middle distillate obtained by the hydrotreating of the FT middle distillate, the yield of the cracked middle distillate obtained by the hydrocracking of the FT wax distillate, the yields of the hydrocarbon oils for use in kerosene smoke point improver and in a diesel fuel base stock, and the increase (% by mass) in the content (% by mass) of isoparaffin in the hydrotreating are shown in Table 3. [0156](Example 10) The hydrocarbon oils for use in kerosene smoke point improver and in a diesel fuel base stock of Example 10 were obtained in the same manner as those of Example 6, provided that the hydrocracking of the FT wax distillate was carried out under the conditions below, on the assumption that circulation of uncracked wax distillate would be carried e I FP06-0522-00 out. [0157] Specifically, as a FT wax distillate subject to hydrocracking, was prepared one obtained by mixing the FT wax distillate and the wax distillate having a boiling point of 360*C or higher which was obtained by the hydrocracking of the FT wax distillate (uncracked wax distillate) at a mass ratio of 100 : (100 - 46). The mixture was fed from the top of the reaction column at a feeding rate of 154 m%/h, hydrogen was fed from the top of the column to the mixture at hydrogen/oil ratio of 680 NL/L, the back pressure regulating valve was adjusted so that the inlet pressure of the reaction column was kept constant, at 4.0 MPa, and under these conditions the reaction temperature (weight averaged catalyst bed temperature) was controlled so that the content of the distillates having a boiling point of 360*C or lower in the mixture after hydrocracking (hydrocracking product) was about 46% by mass (the cracking ratio defined by the above equation (1) was about 46% by mass). The reaction temperature thus controlled was 319*C. [0158] The yields of the FT middle distillate and FT wax distillate obtained by the fractional distillation of FT synthetic oil, the yields of the light middle distillate and heavy middle distillate obtained by the hydrotreating of the FT middle distillate, the yield of the cracked middle distillate obtained by the hydrocracking of the FT wax distillate, the yields of the hydrocarbon oils for use in kerosene smoke point improver and in a diesel fuel base stock, and the increase (% by mass) in the content (% by mass) of isoparaffin in the hydrotreating are shown in Table 3. [01 59](Comparative Example 4) FP06-0522-00 The hydrocarbon oils for use in kerosene smoke point improver and in a diesel fuel base stock of Comparative Example 4 were obtained in the same manner as those of Example 6, provided that in the hydrotreating of the FT middle distillate, the reaction temperature (weight averaged catalyst bed temperature) was controlled so that the content of the hydrocarbons having a boiling point of 150*C or lower in the middle distillate after hydrotreating (hydrotreating product) was 15% by mass. The reaction temperature thus controlled was 321*C. [0160] The yields of the FT middle distillate and FT wax distillate obtained by the fractional distillation of FT synthetic oil, the yields of the light middle distillate and heavy middle distillate obtained by the hydrotreating of the FT middle distillate, the yield of the cracked middle distillate obtained by the hydrocracking of the FT wax distillate, the yields of the hydrocarbon oils for use in kerosene smoke point improver and in a diesel fuel base stock, and the increase (% by mass) in the content (% by mass) of isoparaffin in the hydrotreating are shown in Table 3. [0161](Comparative Example 5) The fractional distillation of FT synthetic oil, hydrotreating of the FT middle distillate and hydrocracking of the FT wax distillate were carried out in the same manner as in Example 6. Then the hydrotreating product of the FT middle distillate and the hydrocracking product of the FT wax distillate were mixed, and the mixture was fractionated in a distillation column to obtain mixed light middle distillate having a boiling point of 150 to 250*C and mixed heavy middle distillate having a boiling point of 250 to 360'C. The yield of FP06-0522-00 the mixed light middle distillate to the distillate having a boiling point of 150'C or higher of FT synthetic oil was 35% by mass while the yield of the mixed heavy middle distillate to the distillate having a boiling point of 150*C or higher of FT synthetic oil was 37% by mass. [0162] The whole amount of the mixed light middle distillate obtained above was used as the hydrocarbon oil for use in kerosene smoke point improver of Comparative Example 5. And the whole amount of the mixed heavy middle distillate obtained above was used as the hydrocarbon oil for use in a diesel fuel base stock of Comparative Example 5. [0163] The yields of the FT middle distillate and FT wax distillate obtained by the fractional distillation of FT synthetic oil and the yields of the hydrocarbon oils for use in kerosene smoke point improver and in a diesel fuel base stock are shown in Table 3. [0164] [Table 3] FP06-0522-00 Ex.6 Ex.7 Ex.8 Ex.9 Ex.10 Com.Ex.4 Com.Ex.5 /d (0 by mass) of FT middle dilate (having a boiling point 50 50 50 50 50 50 50 he range of 150 to 360*C) *1 Id (% by mass) of FT wax 50 50 50 50 50 50 50 *late*I _ ld (% by mass) of naphtha latee (having a boiling point 7 7 7 7 7 15 7 150 0 C or lower) obtained by lrotreating *2 rease (% by mass) in content by mass) of isoparaffn in 34 34 34 34 34 46 34 __treatng Id (% by mass) of light ile distillate (having a ing point in the range of 150 42 42 42 42 42 40 250*C) obtained by rotating *2 Id (% by mass) of heavy Idle distillate (having a ing point in the range of250 50 50 50 50 50 43 360*C) obtained by rotating *2 king ratio (% by mass) in rocracking of FT wax 70 46 84 84 46 46 70 illate ;ence or absence of oatin ofdr cracking of absent absent absent present present absent absent distillate Id (% by mass) of cracked ddle distillate (having a ling point in the range of 150 52 42 57 68 91 42 360*C) obtained by drocracking *3 Dld (% by mass) of drocarbon oil for use in 21 21 21 21 21 20 35 rosene smoke point improver :ld (% by mass) of drocarbon oil for use in a 51 46 53.5 57 70.5 42.5 37 sel fuel base stock *I tal yield (% by mass) of drocarbon oils for use in rosene smoke point improver 72 67 74.5 78 91.5 62.5 72 I in a diesel fuel base stock Yield to distillate having a boiling point of 150*C or higher of FT synthetic oil Yield to FT middle distillate Yield to FT wax distillate FP06-0522-00 [01 65](Evaluation of hydrocarbon oils for use in kerosene smoke point improver and in a diesel fuel base stock) The hydrocarbon oils for use in kerosene smoke point improver and in a diesel fuel base stock obtained in Examples 6 to 10 and Comparative Examples 4 and 5 were evaluated as follows. The evaluations are shown in Table 4. [0166]<Measurement of smoke point of hydrocarbon oil for use in kerosene smoke point improver> The smoke point (mm) of each of the obtained hydrocarbon oil for use in kerosene smoke point improver was measured in accordance with the test method specified in JIS K2537. [0167]<Evaluation of smoke point improving effect of hydrocarbon oil for use in kerosene smoke point improver> A cracked kerosene distillate having a boiling point in the range of 150*C to 260*C and a smoke point of 20.5 mm, which was obtained from atmospheric residual oil using a direct desulfurization unit, was blended with 15% by mass and 30% by mass of each of the obtained hydrocarbon oils for use in kerosene smoke point improver, respectively. The percentage (% by mass) of the hydrocarbon oil for use in kerosene smoke point improver blended was on the basis of the total mass of the hydrocarbon oil for use in kerosene smoke point improver and the cracked kerosene distillate. Then the smoke point (mm) of each blend was measured in accordance with the test method specified in JIS K2537. The increase in smoke point (mm/10% by mass), in terms of addition of 10% by mass of hydrocarbon oil for use in kerosene smoke point improver, was calculated using the increase in smoke point (mm) FP06-0522-00 when the directly desulfurized cracked kerosene was blended with 15% by mass of hydrocarbon oil for use in kerosene smoke point improver and the increase in smoke point (mm) when the directly desulfurized cracked kerosene was blended with 30% by mass of hydrocarbon oil for use in kerosene smoke point improver. It was used as an indicator for smoke point improvement. [0168]<Kinematic viscosity and pour point of hydrocarbon oil for use in a diesel fuel base stock> The kinematic viscosity (mm 2 /s) at 30*C of each of the obtained hydrocarbon oils for use in a diesel fuel base stock was measured in accordance with the test method specified in JIS K2283 and the pour point (*C) of the same in accordance with the test method specified in JIS K2269. [0169] FP06-0522-00 [Table 4] Ex.6 Ex.7 Ex.8 Ex.9 Ex.10 Ex. Ex. Smoke point (mm) of hydrocarbon oil for use 44 44 44 44 44 44 45 in kerosene smoke point improver Increase (mm) in smoke point when the directly desulfurized cracked kerosene was blended with 15% by mass of hydrocarbon +3.5 +3.5 +3.5 +3.5 +3.5 +3.5 +3.6 oil for use in kerosene smoke point improver *1 Increase (mm) in smoke point when the directly desulfurized cracked kerosene was blended with 30% by mass of hydrocarbon +7.0 +7.0 +7.0 +7.0 +7.0 +7.0 +7.1 oil for use in kerosene smoke point improver *1 Smoke point improving effect per 10% by mass of hydrocarbon oil for use in kerosene +2.3 +2.3 +2.3 +2.3 +2.3 +2.3 +2.4 smoke point improver blended (mm/10% by mass) *1 Kinematic viscosity (mm 2 /s) at 30*C of hydrocarbon oil for use in a diesel fuel base 2.7 2.9 2.6 2.5 2.7 2.7 4.0 stock Pour point ("C) of hydrocarbon oil for use in -10 -7.5 -12.5 -15 -10 -10 -2.5 a diesel fuel base stock I I II__I _ * 1: The percentage (% by mass) of the hydrocarbon oil for use in kerosene smoke point improver blended was based on the total mass of the hydrocarbon oil for use in kerosene smoke point improver and the directly desulfurized cracked kerosene. [0170] The results shown in Table 3 and Table 4 prove that, according to any one of the methods for processing synthetic oil of Examples 6 to 10, it is possible to obtain from FT synthetic oil, in a high yield, both hydrocarbon oil for use in kerosene smoke point improver having an excellent smoke point improving effect and hydrocarbon oil for use in a diesel fuel base stock having sufficiently improved pour point and kinematic viscosity at 30*C. INDUSTRIAL APPLICABILITY [0171] According to the present invention, there can be provided a method for processing synthetic oil that makes it possible to convert FT synthetic oil into high value-added components at a high conversion and - 59 achieve the economy in fuel manufacturing process at high levels and also provided hydrocarbon oils for use in hydrogen production, in kerosene smoke point improver and in a diesel fuel base stock all of 5 which are obtained by the above processing method and are of high value-added and good in economy. According to the present invention, a method for producing hydrocarbon oils can also be provided which enables the efficient production of such high value-added hydrocarbon oils. 10 [0172] The reference to any prior art in this specification is not, and should not be taken as, an acknowledgment or any form of suggestion that that prior art forms part of the common general knowledge. [00173] Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and 15 variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

Claims (12)

1. A method for processing synthetic oil, comprising: a first fractional-distillation step of subjecting a material to be 5 processed, which comprises synthetic oil obtained by Fischer Tropsch synthesis, to fractional distillation to obtain a middle distillate, which contains a fraction having a boiling point of 150 to 360"C at 90% by mass or more, and a wax distillate, which is heavier than the middle distillate; 10 a hydrotreating step of subjecting the middle distillate obtained in the first fractional-distillation step to a hydrotreating process that includes both hydrocracking and hydroisomerization by bringing said middle distillate into contact with a hydrotreating catalyst comprising a support containing one or more kinds of solid acids which are selected 15 from the group consisting of crystalline zeolites and amorphous metal oxides having heat resistance, and a group VIII metal supported on said support in the presence of hydrogen so that a fraction having a boiling point of 150*C or lower of the middle distillate has a content (% by mass) with an increase rate of 9% by mass or less after the contact with the 20 catalyst; a second fractional-distillation step of subjecting the middle distillate having passed through the hydrotreating step to fractional distillation to obtain a first fraction, which contains a fraction having a boiling point of 150 to 250 0 C at 90% by mass or more, and a second 25 fraction, which is heavier than the first fraction; a hydrocracking step of subjecting the wax distillate obtained in the first fractional-distillation step to a hydrocracking process that includes hydroisomerization by bringing said wax distillate into contact with a hydrocracking catalyst comprising a support containing one or -61 more kinds of solid acids which are selected from the group consisting of crystalline zeolites and amorphous metal oxides having heat resistance, and a group VIII metal supported on said support in the presence of hydrogen; 5 a third fractional-distillation step of subjecting the wax distillate having passed through the hydrocracking step to fractional distillation to obtain a third fraction, which contains a fraction having a boiling point of 150 to 360 0 C at 90% by mass or more; and a mixing step of mixing the second fraction and the third 10 fraction.
2. The method for processing synthetic oil according to claim 1, wherein part of or all of a wax distillate obtained from the third fractional-distillation step, which is heavier than the third fraction, is 15 subjected to the hydrocracking step.
3. The method for processing synthetic oil according to claim 1 or claim 2, wherein the hydrocracking of the wax distillate in the hydrocracking step is carried out so that the wax distillate after the 20 contact with the hydrocracking catalyst contains a fraction having a boiling point of 360 0 C or lower at 45 to 85% by mass.
4. The method for processing synthetic oil according to claim 1, wherein the first fraction is obtained as a hydrocarbon oil for hydrogen 25 production while the mixture of the second and third fractions is obtained as a hydrocarbon oil for use in a diesel fuel base stock.
5. The method for processing synthetic oil according to claim 1, wherein the first fraction is obtained as a hydrocarbon oil for use in - 62 kerosene smoke point improver while the mixture of the second and third fractions is obtained as a hydrocarbon oil for use in a diesel fuel base stock. 5
6. A method for producing hydrocarbon oils, comprising: a first fractional-distillation step of subjecting a material to be processed, which comprises synthetic oil obtained by Fischer Tropsch synthesis, to fractional distillation to obtain a middle distillate, which contains a fraction having a boiling point of 150 to 360*C at 90% by 10 mass or more, and a wax distillate, which is heavier than the middle distillate; a hydrotreating step of subjecting the middle distillate obtained in the first fractional-distillation step to a hydrotreating process that includes both hydrocracking and hydroisomerization by bringing said 15 middle distillate into contact with a hydrotreating catalyst comprising a support containing one or more kinds of solid acids which are selected from the group consisting of crystalline zeolites and amorphous metal oxides having heat resistance, and a group VIII metal supported on said support in the present of hydrogen so that a fraction having a boiling 20 point of 150*C or lower of the middle distillate has a content (% by mass) with an increase rate of 9% by mass or less after the contact with the catalyst; a second fractional-distillation step of subjecting the middle distillate having passed through the hydrotreating step to fractional 25 distillation to obtain a first fraction, which contains a fraction having a boiling point of 150 to 250*C at 90% by mass or more, and a second fraction, which is heavier than the first fraction; a hydrocracking step of subjecting the wax distillate obtained in the first fractional-distillation step to a hydrocracking process that -63 includes hydroisomerization by bringing said wax distillate into contact with a hydrocracking catalyst comprising a support containing one or more kinds of solid acids which are selected from the group consisting of crystalline zeolites and amorphous metal oxides having heat resistance, 5 and a group VIII metal supported on said support in the presence of hydrogen; a third fractional-distillation step of subjecting the wax distillate having passed through the hydrocracking step to fractional distillation to obtain a third fraction, which contains a fraction having a 10 boiling point of 150 to 360 0 C at 90% by mass or more; and a mixing step of mixing the second fraction and the third fraction to obtain a mixture of the second fraction and third fraction as a hydrocarbon oil. 15
7. The method for producing hydrocarbon oils according to claim 6, wherein the hydrotreating of the middle distillate in the hydrotreating step is carried out so that the increase in content (% by mass) of isoparaffin in the middle distillate after the contact with catalyst is 30% by mass or more, and the hydrocracking of the wax distillate in the 20 hydrocracking step is carried out so that the wax distillate after the contact with the hydrocracking catalyst contains a fraction having a boiling point of 360*C or lower at 45 to 85% by mass.
8. A hydrocarbon oil for use in a diesel fuel base stock, 25 comprising the mixture of the second and third fractions obtained by the method for producing hydrocarbon oils according to claim 7, wherein the hydrocarbon oil has a pour point of -7.5*C or lower and a kinematic viscosity of 2.5 mm 2 /s or higher at 30 0 C. CWNRPrtl\LJC\WAMX39271J9I .II-I1/10/201 -64
9. A diesel fuel base stock comprising the hydrocarbon oil of claim 8.
10. A hydrocarbon oil for hydrogen production, comprising the 5 first fraction obtained by the method for producing hydrocarbon oils according to claim 7, wherein the hydrocarbon oil has a smoke point of 44 mm or more.
11. A kerosene smoke point improver comprising the hydrocarbon 10 oil of claim 10.
12. A hydrocarbon oil obtained by a method for producing hydrocarbon oils according to claim 7 when used for hydrogen production. 15
AU2007232015A 2006-03-30 2007-03-05 Method for treatment of synthetic oil, process for production of hydrocarbon oil, hydrocarbon oil for hydrogen production, hydrocarbon oil for the smoke point improver for kerosene, and hydrocarbon oil for diesel fuel base Ceased AU2007232015B2 (en)

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JP2006095228A JP4908038B2 (en) 2006-03-30 2006-03-30 Method for treating synthetic oil, hydrocarbon oil for hydrogen production and hydrocarbon oil for diesel fuel base material
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JP2006-095201 2006-03-30
PCT/JP2007/054185 WO2007113967A1 (en) 2006-03-30 2007-03-05 Method for treatment of synthetic oil, process for production of hydrocarbon oil, hydrocarbon oil for hydrogen production, hydrocarbon oil for the smoke point improver for kerosene, and hydrocarbon oil for diesel fuel base

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