FP06-0521-00 DESCRIPTION PROCESS FOR PRODUCTION OF HYDROCARBON OIL AND HYDROCARBON OIL TECHNICAL FIELD 5 [0001] The present invention relates to a hydrocarbon oil and a method of manufacturing the same, and more specifically to a hydrocarbon oil useful as a diesel fuel base stock and a method of manufacturing the same. BACKGROUND ART 10 [0002] In recent years, from the viewpoint of reducing the burden on the environment, there have been calls for environmentally-friendly clean liquid fuels having low sulfur and aromatic hydrocarbon contents. In the petroleum industry, studies have thus been carried out into Fischer-Tropsch synthesis (hereinafter abbreviated to "FT synthesis") 15 using carbon monoxide and hydrogen as starting materials as a method of manufacturing a clean fuel. According to FT synthesis, a liquid fuel base having a high paraffin content and not containing sulfur can be manufactured, and hence there are great expectations. [0003] However, a synthetic oil obtained through FT synthesis 20 (hereinafter sometimes referred to as an "FT synthetic oil") has a high normal paraffin content, and contains oxygen-containing compounds such as alcohols, and hence it is difficult to use the synthetic oil as a fuel as is. More specifically, such a synthetic oil has an insufficient octane rating for use as automobile gasoline, and moreover has an insufficient 25 low-temperature fluidity for use as diesel fuel. Moreover, oxygen containing compounds such as alcohols have an adverse effect on the 1 FP06-052 1-00 oxidation stability of a fuel. In general, an FT synthetic oil is thus used as a fuel base after having been hydrotreated so as to convert normal paraffin in the synthetic oil into isoparaffin and convert oxygen containing compounds into other substances. 5 [0004] For example, in the case of manufacturing a diesel fuel base stock, a kerosene base stock, an aviation fuel base or the like, the low temperature fluidity of the fuel base is improved by mixing together as appropriate a middle fraction having a high isoparaffm content obtained by hydrocracking a heavy wax component of the FT synthetic oil, and a 10 middle fraction having an increased paraffin isomerization degree obtained by hydroisomerizing a middle fraction of the FT synthetic oil, or the like (for example, see Patent document 1 and 2.). [0005] Patent document 1: International Patent Application Laid-open No. 00/020535. 15 Patent document 2: French Patent Application Laid-open No. 2826971. DISCLOSURE OF THE INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION [0006] From the viewpoint of preventing fuel pump problems or heat chamber seizure due to oil film disruption, fuel used in diesel 20 automobiles preferably exhibits a certain kinematic viscosity at normal temperature and high temperature. For example, in the no. 2 light oil kinematic viscosity standard of JIS (Japanese Industrial Standards) K2283, the kinematic viscosity at 30 'C is stipulated as being not less than 2.5 mm 2 /s. A hydrocarbon oil to be used as a diesel fuel base 25 stock from out of a middle fraction obtained from an FT synthetic oil must thus have both the low-temperature fluidity and the kinematic 2 FP06-0521-00 viscosity thereof sufficiently improved. [0007] Meanwhile, from hitherto there have been increasingly strong demands to reduce the cost of diesel fuel manufacture, and there is no exception to this for fuel manufacture using FT synthesis; it has thus 5 also become necessary to manufacture a hydrocarbon oil suitable as a diesel fuel base stock from an FT synthetic oil efficiently. [0008] However, the prior art such as above-mentioned Patent document 1 and Patent document 2 is mainly concerned with improving the low-temperature fluidity of a fuel base as described above; no art 10 has as yet been provided that is effective for obtaining a high yield of a hydrocarbon oil that has both good low-temperature fluidity and good kinematic viscosity at 30 *C. [0009] When obtaining a hydrocarbon oil, one could envisage, for example, a method of improving both the low-temperature fluidity and 15 the kinematic viscosity at 30 'C by narrowing the boiling point range for the fractionation; however, with this method, the amount of a diesel fuel base stock that can be manufactured from an FT synthetic oil is reduced, and hence the fuel manufacturing process becomes uneconomical. Moreover, if only a middle fraction obtained by 20 hydrocracking a heavy wax component of an FT synthetic oil is used as a diesel fuel base stock, then it may be possible to obtain both good low-temperature fluidity and good kinematic viscosity at 30 *C; however, the amount of the diesel fuel base stock that can be manufactured from the FT synthetic oil is limited, and hence it is 25 difficult to manufacture a sufficient amount of the fuel base. [0010] The present invention has been devised in view of the above 3 C;\NRonb\DC\WAM3946031_1DOC-21/10/2011 -4 state of affairs; the present invention seeks to provide a hydrocarbon oil manufacturing method that enable a hydrocarbon oil having sufficiently good low temperature fluidity and a kinematic viscosity at 30 *C of not less than 2.5 mm 2 /s to be obtained with high yield from an FT synthetic oil, and a hydrocarbon oil 5 obtained using the method. MEANS FOR SOLVING THE PROBLEMS [001 OA] In a first aspect there is provided a hydrocarbon oil manufacturing method, comprising the steps of: fractionating a synthetic oil obtained through Fischer-Tropsch synthesis, so as to 10 obtain a middle fraction having a content of a fraction of boiling point 150 to 360 'C of not less than 90 mass% and a content of a fraction of boiling point not less than 350 *C of not more than 5 mass%, and a wax component that is heavier than said middle fraction; and bringing each of said middle fraction and said wax component into contact with a 15 hydrotreating catalyst comprising a carrier containing at least one solid acid selected from the group consisting of ultrastable Y (USY) zeolites, HY zeolites, mordenite and P zeolites, and heat-resistant amorphous metal oxides such as silica alumina, silica-zirconia and alumina-boria, and at least one metal selected from the group consisting of metals belonging to group VIII of the periodic table supported 20 on the carrier in the presence of hydrogen at a reaction temperature of 200 to 370 'C, a hydrogen partial pressure of 1.0 to 5.0 MPa, and a liquid hourly space velocity of 0.3 to 3.5 h-, and then mixing together in the same proportion as the C:NRPonblDCOWAM094(6U31 - DOC-21/10120l1 -4A yield of the middle fraction relative to the yield of the wax component from the synthetic oil, and fractionating, so as to obtain a hydrocarbon oil having a content of a fraction of boiling point 150 to 360 C of not less than 86 mass% and a content of a fraction of boiling point not less than 350 *C of not less than 5 mass%. 5 [0011] The present inventors carried out assiduous studies, and as a result accomplished the present invention upon discovering that a hydrocarbon oil obtained by obtaining from an FT synthetic oil a middle fraction containing a specified amount of a fraction having a specified boiling point range and a wax component that is heavier than the middle fraction, separately hydrotreating each of 10 the middle fraction and the wax component and then mixing the two together, and fractionating the mixture to obtain a hydrocarbon oil containing a specified amount of a fraction having a specified boiling point, which can exhibit a pour point of not more than -7.5 *C and a kinematic viscosity at 30 *C of not less than 2.5 mm 2 /s, and moreover exhibits a sufficient yield relative to the starting material FT synthetic oil. 15 [0012] That is, a hydrocarbon oil manufacturing method of the present invention comprises fractionating a synthetic oil obtained through Fischer-Tropsch synthesis, so as to obtain a middle fraction having a content of a fraction of boiling point 150 to 360 'C of not less than 90 mass% and a content of a fraction of boiling point not less than 350 'C of not more than 5 mass%, and a wax component that is heavier 20 than the middle fraction, and bringing each of the middle fraction and the wax FP06-052 1-00 component into contact with a hydrotreating catalyst in the presence of hydrogen, and then mixing together, and fractionating, so as to obtain a hydrocarbon oil having a content of a fraction of boiling point 150 to 360 *C of not less than 86 mass% and a content of a fraction of boiling 5 point not less than 350 *C of not less than 5 mass%. [0013] According to the hydrocarbon oil manufacturing method of the present invention, a hydrocarbon oil having sufficiently good low temperature fluidity and a kinematic viscosity at 30 'C of not less than 2.5 mm 2 /s can be obtained with high yield from an FT synthetic oil. 10 As a result, an environmentally-friendly diesel fuel can be manufactured economically. [0014] In the hydrocarbon oil manufacturing method of the present invention, preferably, the middle fraction is hydrotreated such that the content of hydrocarbons of boiling point not more than 150 'C in the 15 middle fraction is 3 to 9 mass% greater after the contact than before the contact with the hydrotreating catalyst. [0015] As a result, the pour point of the hydrocarbon oil can be further reduced while still securing a sufficient yield for the hydrocarbon oil. [0016] In the hydrocarbon oil manufacturing method of the present 20 invention, preferably, the wax component is hydrotreated such that the content of a fraction of boiling point not more than 360 *C in the wax component after the contact with the hydrotreating catalyst is 45 to 85 mass%. If this content is less than 45 mass%, then the yield for the hydrocarbon oil obtained will tend to decrease, and the low-temperature 25 fluidity of the hydrocarbon oil will tend to decrease. On the other hand, if this content is greater than 85 mass%, then the yield for the 5 C:\NRPonb\DCC\WAM\394(A'31.1 DOC-21/10/2011 -6 hydrocarbon oil obtained will tend to decrease. [0017] In the hydrocarbon oil manufacturing method of the present invention, preferably, each of the hydrotreating catalyst brought into contact with the middle fraction and the hydrotreating catalyst brought into contact with the wax component 5 comprises a carrier containing 0.1 to 80.0 mass% of a crystalline zeolite and 0.1 to 60.0 mass% of a heat-resistant amorphous metal oxide, and at least one metal selected from the group consisting of metals belonging to group VIII of the periodic table supported on the carrier. [0018] In the hydrocarbon oil manufacturing method of the present invention, the 10 middle fraction is brought into contact with the hydrotreating catalyst at a reaction temperature of 200 to 370 'C, a hydrogen partial pressure of 1.0 to 5.0 MPa, and a liquid hourly space velocity of 0.3 to 3.5 h-, and the wax component is brought into contact with the hydrotreating catalyst at a reaction temperature of 200 to 370 'C, a hydrogen partial pressure of 1.0 to 5.0 MPa, and a liquid hourly space velocity of 15 0.3 to 3.5 h1. [0019] Moreover, a hydrocarbon oil of the present invention is obtained through the hydrocarbon oil manufacturing method of the present invention as described above, which can have a pour point of not more than -7.5 'C, and a kinematic viscosity at 30 'C of not less than 2.5 mm 2 /s. Such a hydrocarbon oil has excellent 20 quality as a diesel fuel base stock, and moreover can be obtained with high yield from an FT synthetic oil. According to the hydrocarbon oil of the present invention, an environmentally-friendly diesel fuel can thus be realized at low cost.
C:\RPo1bl\DCC\WAM3946031_ DOC-21/10/2011 -7 EFFECT OF THE INVENTION [0020] According to the present invention, there can be provided a hydrocarbon oil manufacturing method that enables a hydrocarbon oil having sufficiently good low-temperature fluidity and a kinematic viscosity at 30 *C of not less than 5 2.5 mm 2 /s to be obtained with high yield from an FT synthetic oil, and a hydrocarbon oil obtained using the method. BRIEF DESCRIPTION OF THE DRAWINGS [0021] FIG. 1 is a flow diagram showing an example of a hydrocarbon oil manufacturing apparatus for implementing a hydrocarbon oil manufacturing method 10 of an embodiment of the present invention. Explanation of Reference Numerals [0022] 1: FT synthetic oil introduction flow path; 2, 4, 6: flow path; 3: middle fraction flow path; 5: wax component flow path; 7, 8: recovery flow path; 9: circulating flow path; 10: first distillation column; 20, 30: hydrotreating apparatus; 15 22, 32: gas-liquid separation tank; 40: second distillation column; 100: hydrocarbon oil manufacturing apparatus. BEST MODE FOR CARRYING OUT THE INVENTION [0023] Following is a detailed description of a preferred embodiment of the present invention with reference to the attached non-limiting drawings. Note that in 20 the description of the drawings, same or equivalent elements are designated by the same reference numeral, and repeated description is omitted.
C: onbl\CC\WAM394031_1 0OC-2110/2011 -7A [0024] FIG. I is a flow diagram showing an example of a hydrocarbon oil manufacturing apparatus for implementing a hydrocarbon oil manufacturing method of an embodiment of the present invention. The hydrocarbon oil manufacturing apparatus 100 shown in FIG. 1 comprises an FT FP06-0521-00 synthetic oil introduction flow path 1 through which a starting material FT synthetic oil is introduced, a first distillation column 10 that fractionates the synthetic oil introduced in from the FT synthetic oil introduction flow path 1 into a light fraction, a middle fraction, and a 5 heavy wax component, a hydrotreating apparatus 20 that hydrogenates the middle fraction which is supplied in from the distillation column 10 via a middle fraction flow path 3, a hydrotreating apparatus 30 that hydrogenates the heavy wax component which is supplied in from the distillation column 10 via a wax component flow path 5, a gas-liquid 10 separation tank 22 for removing a gaseous component from the middle fraction that has passed through the hydrotreating apparatus 20, a gas liquid separation tank 32 for removing a gaseous component from the heavy wax component that has passed through the hydrotreating apparatus 30, and a second distillation column 40 that fractionates a 15 liquid component from the gas-liquid separation tank 22 and a liquid component from the gas-liquid separation tank 32. The gas-liquid separation tank 22 and the second distillation column 40, and the gas liquid separation tank 32 and the second distillation column 40 are connected together by a flow path 4 and a flow path 6 respectively. 20 [0025] Moreover, the first distillation column 10 has connected thereto a flow path 2 through which light wax is discharged out of the system. Furthermore, the second distillation column 40 has connected thereto a recovery flow path 8 for discharging the hydrocarbon oil of the present invention obtained through the fractionation, a recovery flow path 7 for 25 discharging a fraction lighter than the hydrocarbon oil, and a circulating flow path 9 for supplying a wax component heavier than the 8 FP06-052 1-00 hydrocarbon oil into the hydrotreating apparatus 30 for hydrotreating as required. [0026] Following is a detailed description of the hydrocarbon oil manufacturing method of the present invention with reference to the 5 hydrocarbon oil manufacturing apparatus 100 shown in FIG 1. [0027] (Fractionation of FT synthetic oil) First, there are no particular limitations on the FT synthetic oil used in the hydrocarbon oil manufacturing method of the present invention so long as the FT synthetic oil is produced through FT synthesis, although 10 the FT synthetic oil preferably contains not less than 80 mass% of hydrocarbons having a boiling point of not less than 150 'C based on the total amount of the FT synthetic oil, and not less than 35 mass% of hydrocarbons having a boiling point of not less than 360 'C based on the total amount of the FT synthetic oil. Here, the total amount of the 15 FT synthetic oil means the total amount of hydrocarbons having not less than 5 carbon atoms produced through the FT synthesis. [0028] For the first distillation column 10, two cut points are set when fractionating the FT synthetic oil, whereby a fraction having a boiling point of not more than the first cut point can be obtained as a light 20 fraction, a fraction having a boiling point between the first cut point and the second cut point as a middle fraction, and a fraction having a boiling point of not less than the second cut point as a bottom oil (heavy wax component). In the present embodiment, by setting the first cut point and the second cut point as appropriate, a middle fraction having a 25 content of a fraction of boiling point 150 to 360 *C of not less than 90 mass% and a content of a fraction of boiling point not less than 350 'C 9 FP06-0521-00 of not more than 5 mass%, and a wax component that is heavier than the middle fraction are obtained. [0029] The content of the fraction of boiling point 150 to 360 *C and the content of the fraction of boiling point not less than 350 *C (mass%) 5 in the middle fraction can be determined through analysis using a publicly known method, for example gas chromatography on a sample from the middle fraction flow path 3. [0030] Furthermore, in the present embodiment, in the first distillation column 10, the fractionation is preferably carried out such that the 10 fraction of boiling point not less than 350 *C is substantially not contained in the middle fraction. Moreover, the fractionation is preferably carried out such that not less than 15 mass% of a fraction of boiling point 300 to 350 *C is contained in the middle fraction. [0031] The first cut point and the second cut point are preferably set in 15 a range of 135 to 170 'C and in a range of 330 to 355 'C respectively, more preferably in a range of 145 to 155 *C and in a range of 345 to 355 'C respectively. [0032] Note that the number of cut points for the first distillation column 10 is not limited to being two, but rather three or more may be 20 set so long as the middle fraction and the wax component can be obtained as described above. [0033] (Hydrotreating of middle fraction) In the hydrotreating apparatus 20, the middle fraction obtained from the first distillation column 10 is hydrotreated. As the hydrotreating 25 apparatus 20, a publicly known fixed bed reaction column can be used. In the present embodiment, in the reaction column, a predetermined 10 C:NRPonbrDCC\WAM\394603 I .DOC-21110/2011 hydrorefining catalyst is preferably packed into the fixed bed flow reactor, so that the middle fraction obtained from the first distillation column 10 is hydrorefined. Here, "hydrorefining" includes both hydrocracking and hydroisomerization. Furthermore, "cracking" 5 means chemical reaction accompanied by a reduction in molecular weight, and "isomerization" means conversion into a compound having a different carbon backbone while maintaining the molecular weight and the number of carbons in the molecule as is. [0034] The hydrorefining catalyst is one in which a metal 10 belonging to group VIII of the periodic table is supported as an active metal on a carrier containing a solid acid. [0035] A suitable carrier is one containing at least one solid acid selected from crystalline zeolites such as ultrastable Y (USY) zeolites, HY zeolites, mordenite and P zeolites, and heat-resistant amorphous 15 metal oxides such as silica-alumina, silica-zirconia and alumina-boria. Furthermore, the carrier is more preferably one containing a USY zeolite, and at least one solid acid selected from silica-alumina, alumina-boria and silica-zirconia, yet more preferably one containing a USY zeolite and silica-alumina. 20 [0036] Such a USY zeolite is a Y zeolite that has been ultrastabilized through hydrothermal treatment and/or acid treatment, whereby in addition to a microporous structure of micropores of size not more than 20 A originally possessed by the Y zeolite, new pores of size in a range of 20 to 100 A are also formed. In the case of using a USY zeolite in 25 the carrier of the hydrorefining catalyst, there are no particular limitations on the mean particle diameter thereof, but this mean particle 11 FP06-052 1-00 diameter is preferably not more than 1.0 pm, more preferably not more than 0.5 pm. Moreover, for the USY zeolite, the silica/alumina molar ratio (the molar ratio of silica to alumina, hereinafter referred to as the "silica/alumina ratio") is preferably in a range of 10 to 200, more 5 preferably 15 to 100, yet more preferably 20 to 60. [0037] Moreover, the carrier preferably contains 0.1 to 80 mass% of the crystalline zeolite, and 0.1 to 60 mass% of the heat-resistant amorphous metal oxide. [0038] The catalyst carrier can be manufactured by molding a mixture 10 comprising the above solid acid and a binder, and then firing. The proportion of the solid acid is preferably in a range of 1 to 70 mass%, more preferably 2 to 60 mass%, based on the whole amount of the carrier. Moreover, in the case that the carrier contains a USY zeolite, the content of the USY zeolite is preferably in a range of 0.1 to 10 15 mass%, more preferably 0.5 to 5 mass%, based on the whole amount of the carrier. Furthermore, in the case that the carrier contains a USY zeolite and alumina-boria, the mass ratio between the USY zeolite and the alumina-boria (USY zeolite/alumina-boria) is preferably in a range of 0.03 to 1. Moreover, in the case that the carrier contains a USY 20 zeolite and silica-alumina, the mass ratio between the USY zeolite and the silica-alumina (USY zeolite/silica-alumina) is preferably in a range of 0.03 to 1. [0039] There are no particular limitations on the binder, but alumina, silica, silica-alumina, titania, or magnesia is preferable, alumina being 25 particularly preferable. The content of the binder is preferably in a range of 20 to 98 mass%, more preferably 30 to 96 mass%, based on the 12 C:\URPortbl\DCC\WAM\3946031_1 DOC-21/10201 I - 13 whole amount of the carrier. [0040] The firing temperature of the mixture is preferably in a range of 400 to 550 0 C, more preferably 470 to 530 'C, yet more preferably 490 to 530 0 C. [0041] Specific examples of the group VIII metal include cobalt, nickel, rhodium, 5 palladium, iridium, and platinum. Of these, it is preferable to use one metal selected from nickel, palladium and platinum alone, or a plurality thereof in combination. [0042] Such metal can be supported on the carrier through an ordinary method such as impregnation or ion exchange. There are no particular limitations on the 10 amount of the metal supported, but the total amount of the metal is preferably in a range of 0.1 to 3.0 mass% relative to the carrier. [0043] The hydrorefining of the middle fraction is carried out under the following reaction conditions. The hydrogen partial pressure is, in a range of 1.0 to 5.0 MPa. The liquid hourly space velocity (LHSV) of the middle fraction is in a range of 0.3 15 to 3.5 h. There are no particular limitations on the hydrogen/oil ratio, but this ratio is, for example, in a range of 50 to 1000 NL/L, preferably 70 to 800 NL/L. [0044] Note that, in the present specification, the "LHSV (liquid hourly space velocity)" means the volumetric flow rate of the starting material oil in a standard state (25 *C, 101325 Pa) per unit volume of the catalyst layer in which the catalyst 20 is packed, the unit "h"" thereof indicating the reciprocal of time (hours). Moreover, the unit "NL" of the hydrogen volume in the hydrogen/oil ratio indicates the hydrogen volume (L) in a normal state (0 'C, 101325 Pa).
C WRPorb\DCCWAMU94603 U DOC-21/1012011 - 14 [0045] Moreover, the reaction temperature in the hydrorefining is, in a range 200 to 370 *C, more preferably 250 to 350 'C, yet more preferably 280 to 350 *C. It is undesirable for the reaction temperature in the hydrorefining to exceed 370 C, since then a side reaction of cracking into a naphtha fraction will increase, and 5 hence the yield of the middle fraction will decrease excessively, and moreover the product will become colored, and thus there will be limitations on use as a fuel base. Furthermore, it is undesirable for the reaction temperature to be less than 200 *C, since then alcohols will not be completely removed but rather will remain. [0046] Moreover, in the present embodiment, the middle fraction is preferably 10 hydrorefined such that the content (mass%) of hydrocarbons of boiling point not more than 150 'C in the middle fraction after the contact with the catalyst is 3 to 9 mass% greater than before the contact with the catalyst. [0047] The content (mass%) of hydrocarbons of boiling point not more than 150 C in the middle fraction before and after the contact with the catalyst can be 15 determined, for example, through analysis using a publicly known method such as gas chromatography on samples taken from the inlet and the outlet of the reaction column. [0048] In the hydrocarbon oil manufacturing method of the present embodiment, reaction conditions at which the content (mass%) of hydrocarbons of boiling point 20 not more than 150 *C in the middle fraction is 3 to 9 mass% greater after the contact than before the contact with the catalyst may be determined in advance while checking the FP06-0521-00 content of hydrocarbons having each number of carbon atoms in the middle fraction before and after the contact with the catalyst using a method as above, the hydrorefining then being carried out under these conditions. 5 [0049] (Hydrotreating of heavy wax component) In the hydrotreating apparatus 30, the heavy wax component obtained from the first distillation column 10 is hydrotreated. As the hydrotreating apparatus 30, a publicly known fixed bed reaction column can be used. In the present embodiment, in the reaction column, a 10 predetermined hydrocracking catalyst is packed into the fixed bed flow reactor, so that the wax component obtained from the first distillation column 10 is hydrocracked. Here, in the hydrotreating of the wax component, chemical reaction accompanied by a reduction in molecular weight mainly proceeds, but hydroisomerization is also included under 15 the hydrotreating. [0050] An example of the hydrocracking catalyst is one in which a metal belonging to group VIII of the periodic table is supported as an active metal on a carrier containing a solid acid. [0051] A suitable carrier is one containing at least one solid acid 20 selected from crystalline zeolites such as ultrastable Y (USY) zeolites, HY zeolites, mordenite and P zeolites, and heat-resistant amorphous metal oxides such as silica-alumina, silica-zirconia, and alumina-boria. Furthermore, the carrier is more preferably one containing a USY zeolite, and at least one solid acid selected from silica-alumina, 25 alumina-boria and silica-zirconia, yet more preferably one containing a USY zeolite and silica-alumina. 15 FP06-0521-00 [0052] Such a USY zeolite is a Y zeolite that has been ultrastabilized through hydrothermal treatment and/or acid treatment, whereby in addition to a microporous structure of micropores of size not more than 20 A originally possessed by the Y zeolite, new pores of size in a range 5 of 20 to 100 A are also formed. In the case of using a USY zeolite in the carrier of the hydrocracking catalyst, there are no particular limitations on the mean particle diameter thereof, but this mean particle diameter is preferably not more than 1.0 ptm, more preferably not more than 0.5 pLm. Moreover, for the USY zeolite, the silica/alumina molar 10 ratio (the molar ratio of silica to alumina, hereinafter referred to as the "silica/alumina ratio") is preferably in a range of 10 to 200, more preferably 15 to 100, yet more preferably 20 to 60. [0053] Moreover, the carrier preferably contains 0.1 to 80 mass% of the crystalline zeolite, and 0.1 to 60 mass% of the heat-resistant amorphous 15 metal oxide. [0054] The catalyst carrier can be manufactured by molding a mixture comprising the above solid acid and a binder, and then firing. The proportion of the solid acid is preferably in a range of 1 to 70 mass%, more preferably 2 to 60 mass%, based on the whole amount of the 20 carrier. Moreover, in the case that the carrier contains a USY zeolite, the content of the USY zeolite is preferably in a range of 0.1 to 10 mass%, more preferably 0.5 to 5 mass%, based on the whole amount of the carrier. Furthermore, in the case that the carrier contains a USY zeolite and alumina-boria, the mass ratio between the USY zeolite and 25 the alumina-boria (USY zeolite/alumina-boria) is preferably in a range of 0.03 to 1. Moreover, in the case that the carrier contains a USY 16 C :NRPortbIDCC\WAM\3946031_1 DOC-21/10/2011 zeolite and silica-alumina, the mass ratio between the USY zeolite and the silica-alumina (USY zeolite/silica-alumina) is preferably in a range of 0.03 to 1. [0055] There are no particular limitations on the binder, but alumina, 5 silica, silica-alumina, titania, or magnesia is preferable, alumina being particularly preferable. The content of the binder is preferably in a range of 20 to 98 mass%, more preferably 30 to 96 mass%, based on the whole amount of the carrier. [0056] The firing temperature of the mixture is preferably in a range of 10 400 to 550 *C, more preferably 470 to 530 *C, yet more preferably 490 to 530 OC. [0057] Specific examples of the group VIII metal include cobalt, nickel, rhodium, palladium, iridium, and. platinum. Of these, it is preferable to use one metal selected from nickel, palladium and platinum alone, or a 15 plurality thereof in combination. [0058] Such metal can be supported on the carrier through an ordinary method such as impregnation or ion exchange. There are no particular limitations on the amount of the metal supported, but the total amount of the metal is preferably in a range of 0.1 to 3.0 mass% relative to the 20 carrier. [0059] The hydrocracking of the heavy wax component can be carried out under the following reaction conditions. The hydrogen partial pressure is, in a range of 1.0 to 5.0 MPa. The liquid hourly space velocity (LHSV) of the middle fraction is, in a range of 0.3 to 3.5 h-1. There are 25 no particular limitations on the hydrogen/oil ratio, 17 FP06-052 1-00 but this ratio is, for example, in a range of 50 to 1000 NL/L, preferably 70 to 800 NL/L. [0060] Moreover, in the present embodiment, the wax component is preferably hydrocracked such that the content of a fraction of boiling 5 point not more than 360 *C in the wax component after the contact with the catalyst is in a range of 45 to 85 mass%. [0061] The content of the fraction of boiling point not more than 360 'C in the wax component after the contact with the catalyst can be determined, for example, through analysis using a publicly known 10 method such as gas chromatography on samples taken from the inlet and the outlet of the reaction column. [0062] In the hydrocarbon oil manufacturing method of the present embodiment, reaction conditions at which the content of the fraction of boiling point not more than 360 'C in the wax component after the 15 contact with the catalyst is 45 to 85 mass% may be determined in advance, the hydrocracking then being carried out under these conditions. [0063] (Fractionation of hydrocarbon oil) The hydrotreated middle fraction flowing out from the hydrotreating 20 apparatus 20 (hereinafter sometimes referred to as the "hydrorefming product", and the hydrotreated wax component flowing out from the hydrotreating apparatus 30 (hereinafter sometimes referred to as the "hydrocracking product") are transported into the second distillation column 40 via the gas-liquid separation tanks 22 and 32 respectively, 25 and distilled together in the second distillation column 40, so as to be fractionated into desired fractions. 18 FP06-0521-00 [0064] In the gas-liquid separation tanks 22 and 32, the hydrorefining product and the hydrocracking product are each separated into, for example, unreacted hydrogen gas and light hydrogen gas comprising hydrocarbons having not more than 4 carbon atoms, and a liquid 5 hydrocarbon oil comprising hydrocarbons having not less than 5 carbon atoms. Here, the liquid hydrocarbon oils are transferred into the distillation column 40 as the hydrorefming product and the hydrocracking product. As each of the gas-liquid separation tanks, a publicly known one can be used. 10 [0065] In the second distillation column 40, two cut points are set when fractionating the hydrorefining product and the hydrocracking product, whereby a fraction having a boiling point of not more than the first cut point can be obtained as a light fraction, a fraction having a boiling point between the first cut point and the second cut point as a middle 15 fraction, and a fraction having a boiling point of not less than the second cut point as a bottom oil (the heavy wax component). In the present embodiment, the middle fraction, which is fractionated such that the content of a fraction of boiling point 150 to 360 'C is not less than 90 mass% and the content of a fraction of boiling point not less than 20 350 'C is not less than 5 mass%, is obtained as the hydrocarbon oil according to the present invention. [0066] The first cut point and the second cut point are preferably set in a range of 135 to 170 *C and in a range of 345 to 375 'C respectively, more preferably in a range of 145 to 155 *C and in a range of 360 to 25 375 'C respectively. [0067] Note that the number of cut points for the second distillation 19 C:\NRonbl\DCCWAM\9460M3l DOC-21110/2011 column 40 is not limited to being two, but rather three or more may be set so long as the hydrocarbon oil according to the present invention can be obtained as described above. [0068] The middle fraction obtained as described above, i.e. the 5 hydrocarbon oil according to the present invention, is recovered via the recovery flow path 8, Moreover, a naphtha fraction lighter than the middle fraction is discharged out of the system via the flow path 7, while a wax component heavier than the middle fraction is supplied into the hydrotreating apparatus 30 via the circulating flow path 9, and 10 subjected to the hydrocracking as required. [0069] According to the hydrocarbon oil manufacturing method of the present invention described above, a hydrocarbon oil having a pour point of not more than -7.5 *C and a kinematic viscosity at 30 *C of not less than 2.5 mm 2 /s can be obtained with high yield. Such a 15 hydrocarbon oil can be suitably used as, for example, a base for an environmentally-friendly diesel fuel. EXAMPLES [0070] Following is a more detailed description of embodiments of the present invention through working examples. However, the present 20 invention is not limited to these working examples. [0071] <Preparation of catalyst> (Catalyst A) A USY zeolite (silica/alumina molar ratio: 37) having a mean particle diameter of 1.1 pm, silica-alumina (silica/alumina molar ratio: 14), and 25 an alumina binder were mixed and kneaded together in a weight ratio of 3:57:40, and the mixture was molded into cylindrical shapes of diameter 20 FP06-052 1-00 approximately 1.6 mm and length approximately 4 mm, and then firing was carried out at 500 'C for 1 hour, whereby a carrier was obtained. A chloroplatinic acid aqueous solution was impregnated into the carrier, thus supporting platinum. The platinum-supporting carrier was dried 5 at 120 *C for 3 hours, and then fired at 500 'C for 1 hour, whereby catalyst A was obtained. The amount of platinum supported was 0.8 mass% relative to the carrier. [0072] <Manufacture of hydrocarbon oil for diesel fuel base stock > (Example 1) 10 (Fractionation of FT synthetic oil) A produced oil obtained through FT synthesis (an FT synthetic oil) (content of hydrocarbons of boiling point not less than 150 'C: 84 mass%, content of hydrocarbons of boiling point not less than 360 'C: 42 mass%, both contents based on total amount of FT synthetic oil (total 15 amount of hydrocarbons having not less than 5 carbon atoms)) was separated using a distillation column into a light fraction of boiling point not more than 150 C, a middle fraction of boiling point 150 to 350 C (content of hydrocarbons of boiling point 150 to 360 *C: 100 mass%, content of hydrocarbons of boiling point not less than 350 'C: 0 20 mass%, content of hydrocarbons of boiling point 300 to 350 *C: 19 mass%, content of hydrocarbons of boiling point not more than 150 *C: 0 mass%), and a column bottom residue heavy wax component (being a fraction of boiling point not less than 350 C). [0073] (Hydrotreating (hydrorefining) of middle fraction) 25 Catalyst A (150 ml) was packed into a fixed bed flow reactor, the middle fraction obtained as described above was supplied in at a rate of 21 FP06-052 1-00 300 ml/h from the top of the reaction column, and hydrotreating was carried out under a hydrogen gas stream under the following reaction conditions. [0074] That is, hydrogen was supplied in from the top of the column at 5 a hydrogen/oil ratio of 340 NL/L relative to the middle fraction, a back pressure valve was adjusted such that the reaction column pressure was fixed at an inlet pressure of 3.0 MPa, and under these conditions the reaction temperature (catalyst bed weight average temperature) was adjusted such that the content of hydrocarbons of boiling point not more 10 than 150 'C in the hydrotreated middle fraction (the reaction product) was 5 mass%. The reaction temperature for this was 308 'C. The above content was checked through gas chromatography measurement on the hydrotreated middle fraction (the reaction product). [0075] (Hydrotreating (hydrocracking) of heavy wax component) 15 On the other hand, using another reaction column, catalyst A (150 ml) was packed into a fixed bed flow reactor, the column bottom residue heavy wax component obtained as described above was supplied in at a rate of 300 mih from the top of the reaction column, and hydrotreating was carried out under a hydrogen gas stream under the following 20 reaction conditions. [0076] That is, hydrogen was supplied in from the top of the column at a hydrogen/oil ratio of 680 NL/L relative to the wax component, a back pressure valve was adjusted such that the reaction column pressure was fixed at an inlet pressure of 4.0 MPa, and under these conditions the 25 reaction temperature (catalyst bed weight average temperature) was adjusted such that the total content of cracking products of boiling point 22 FP06-0521-00 not more than 360 'C in the hydrotreated wax component (the hydrocracking product) was approximately 70 mass%. The reaction temperature for this was 320 'C. The above content was checked through gas chromatography measurement on the hydrotreated wax 5 component (the hydrocracking product) and analysis of the distillation characteristics. [0077] (Fractionation of hydrorefining product and hydrocracking product) The middle fraction hydrorefining product and the wax component 10 hydrocracking product obtained as described above were mixed together as is in the proportion of their respective yields, and the mixture was fractionated using a distillation column. A fraction of boiling point 150 to 360 'C was obtained as a hydrocarbon oil for a diesel fuel base stock of Working Example 1. For the hydrocarbon oil obtained, the 15 pour point (C) and the kinematic viscosity at 30 *C (mm 2 /s) were measured. The results are shown in Table 1. The pour point was measured in accordance with the test method of JIS K2269, and the kinematic viscosity at 30 'C was measured in accordance with the test method of JIS K2283. 23 FP06-0521-00 [0078] Table 1 Example Example Example Example Example Comparative Comparative 1 2 3 4 5 Example I Example 2 Content of fraction of boiling point not less than 350 *C in middle 0 0 0 0 4 10 20 fraction to be subjected to hydrotreating (mass%) Boiling point range of 150- 150- 145- 140- 150 hydrocarbon oil 360 380 380 385 360 150-360 150-360 for diesel fuel base stock (*C) Content of fraction of boiling point 150 to 360 *C in hydrocarbon oil for diesel fuel base stock (mass%) Content of fraction of boiling point not less than 350 *C 5 8 7.8 9 8 8 13 in hydrocarbon oil for diesel fuel base stock (mass%) Yield of hydrocarbon oil for diesel fuel base stock 64 68 70 72 65 63 65 relative to starting material FT synthetic oil (mass%) Kinematic viscosity of hydrocarbon oil 2.6 2.8 2.7 2.7 2.65 2.8 3.0 for diesel fuel base stock at 30 *C (mm 2 /s) Pour point of hydrocarbonoil -12.5 -7.5 -10.0 -7.5 -10.0 -5.0 -2.5 for diesel fuel base stock (*C) 24 FP06-052 1-00 [0079] (Example 2) A hydrocarbon oil for a diesel fuel base stock of Example 2 was obtained as in Example 1, except that instead of obtaining a fraction of boiling point 150 to 360 *C as the hydrocarbon oil for a diesel fuel base 5 stock through the fractionation of the hydrorefining product and the hydrocracking product as in Example 1, a fraction of boiling point 150 to 380 *C was obtained as the hydrocarbon oil for a diesel fuel base stock. For the hydrocarbon oil obtained, analysis was carried out as in Example 1. The results are shown in Table 1. 10 [0080] (Example 3) A hydrocarbon oil for a diesel fuel base stock of Example 3 was obtained as in Example 1, except that instead of obtaining a fraction of boiling point 150 to 360 *C as the hydrocarbon oil for a diesel fuel base stock through the fractionation of the hydrorefming product and the 15 hydrocracking product as in Example 1, a fraction of boiling point 145 to 380 *C was obtained as the hydrocarbon oil for a diesel fuel base stock. For the hydrocarbon oil obtained, analysis was carried out as in Example 1. The results are shown in Table 1. [0081] (Example 4) 20 A hydrocarbon oil for a diesel fuel base stock of Example 4 was obtained as in Example 1, except that instead of obtaining a fraction of boiling point 150 to 360 'C as the hydrocarbon oil for a diesel fuel base stock through the fractionation of the hydrorefining product and the hydrocracking product as in Example 1, a fraction of boiling point 140 25 to 385 'C was obtained as the hydrocarbon oil for a diesel fuel base stock. For the hydrocarbon oil obtained, analysis was carried out as in 25 FP06-0521-00 Example 1. The results are shown in Table 1. [0082] (Example 5) A hydrocarbon oil for a diesel fuel base stock of Example 5 was obtained as in Example 1, except that instead of obtaining a fraction of 5 boiling point 150 to 350 'C as the middle fraction through the fractionation of the FT synthetic oil as in Example 1, a fraction of boiling point 150 to 356 *C (content of hydrocarbons of boiling point not less than 350 'C: 4 mass%) was obtained, and a wax component being a fraction of boiling point not less than 356 'C was obtained as 10 the column bottom residue wax component. For the hydrocarbon oil obtained, analysis was carried out as in Example 1. The results are shown in Table 1. [0083] (Comparative Example 1) A hydrocarbon oil for a diesel fuel base stock of Comparative Example 15 1 was obtained as in Example 1, except that instead of obtaining a fraction of boiling point 150 to 350 'C as the middle fraction through the fractionation of the FT synthetic oil as in Example 1, a fraction of boiling point 150 to 362 'C (content of hydrocarbons of boiling point not less than 350 'C: 10 mass%) was obtained, and a wax component 20 being a fraction of boiling point not less than 362 'C was obtained as the column bottom residue wax component. For the hydrocarbon oil obtained, analysis was carried out as in Example 1. The results are shown in Table 1. [0084] (Comparative Example 2) 25 A hydrocarbon oil for a diesel fuel base stock of Comparative Example 2 was obtained as in Example 1, except that instead of obtaining a 26 FP06-0521-00 fraction of boiling point 150 to 350 'C as the middle fraction through the fractionation of the FT synthetic oil as in Example 1, a fraction of boiling point 150 to 375 *C (content of hydrocarbons of boiling point not less than 350 *C: 20 mass%) was obtained, and a wax component 5 being a fraction of boiling point not less than 375 'C was obtained as the column bottom residue wax component. For the hydrocarbon oil obtained, analysis was carried out as in Example 1. The results are shown in Table 1. [0085] (Comparative Example 3) 10 A hydrocarbon oil for a diesel fuel base stock of Comparative Example 3 was obtained as in Example 1, except that instead of obtaining a fraction of boiling point 150 to 360 'C as the hydrocarbon oil for a diesel fuel base stock through the fractionation of the hydrorefming product and the hydrocracking product as in Example 1, a fraction of 15 boiling point 180 to 330 'C was obtained as the hydrocarbon oil for a diesel fuel base stock. For the hydrocarbon oil obtained, analysis was carried out as in Example 1. The results are shown in Table 2. 27 C:W4RPonb\DCC\WAM3946031_. DOC-21/10/201l - 27A [0085A] The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that that prior publication (or information derived from it) or known matter forms part of the 5 common general knowledge in the field of endeavour to which this specification relates. [0085B] Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or 10 step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.
FP06-052 1-00 [0086] Table 2 Comparative Comparative Example 3 Example 4 Boiling point range of hydrocarbon oil for diesel 180-330 150-370 fuel base stock (*C) Content of fraction of boiling point 150 to 100 96 360 *C in hydrocarbon oil for diesel fuel base stock (mass/o) Content of fraction of boiling point not less than 0 11 350 *C in hydrocarbon oil for diesel fuel base stock (mass%) Yield of hydrocarbon oil for diesel fuel base 46 24 stock relative to starting material FT synthetic oil (mass%) Kinematic viscosity of hydrocarbon oil for 2.6 2.6 diesel fuel base stock at 30 *C (mm2/s) Pour point of hydrocarbon oil for diesel fuel -7.5 -15 base stock (*C) II __j [0087] (Comparative Example 4) A hydrocarbon oil for a diesel fuel base stock of Comparative Example 4 was obtained as in Example 1, except that the middle fraction was not 5 used as in Example 1, but rather only the hydrocracking product from the column bottom residue wax component was fractionated using the distillation column, a fraction of boiling point 150 to 370 *C being obtained as the hydrocarbon oil for a diesel fuel base stock. For the hydrocarbon oil obtained, analysis was carried out as in Example 1. 10 The results are shown in Table 2. 28