CERTIFICATE OF VERIFICATION I, Shiro TERASAKI Japanese Patent Attorney Registered No. 9265 of SOEI PATENT & LAW FIRM Ginza First Bldg., 10-6, Ginza 1-chome, Chuo-ku, Tokyo 104-0061 Japan states that the attached document is a true and complete translation to the best of my knowledge of International Patent Application No. PCT/JP2007/054926 Dated this 26th day of August, 2008 Signature of translator: Shiro TERASAKI FPO7-0095-00 DESCRIPTION METHOD OF WAX HYDROCRACKING Technical Field [0001] The present invention relates to a method for hydrocracking 5 wax. Background Art [0002] Recently, environmental control against liquid fuels such as gasoline and gas oil has been tightened rapidly, and there has been grown expectation to an environment-friendly clean liquid fuel having a 10 low content of sulfur and aromatic hydrocarbons. One of such preparation methods of clean fuels is Fisher-Tropsch (FT) synthesis wherein hydrogen and carbon mono-oxide obtained by gasifying asphalt or coal or by reforming natural gas are used as starting materials. The FT synthesis can give not only a liquid fuel base which is rich in 15 paraffin and contains no sulfur, but also a wax (FT wax) at the same time. Then, the FT wax can be hydrocracked to convert to medium fractions (fuel bases such as kerosene and gas oil). [0003] Technique to produce fuel bases by hydrocracking wax has been studied. For example, in the following documents 1 to 3, there are 20 described hydrocracking methods where the FT wax is used as a starting material. Patent Document 1: WO2004/028688 Patent Document 2: JP-Al1-2004-255241 Patent Document 3: JP-Al-2004-255242 25 Disclosure of the Invention Problem to be Solved by the Invention
I
FPO7-0095-00 [0004] gas oils are required to have different properties depending on environments to use for, and are classified into Special No. 1 diesel fuel, No. 1 diesel fuel, No. 2 diesel fuel, No. 3 diesel fuel and Special No. 3 diesel fuel according to JIS K 2204 (2004). Among them, No. 3 diesel 5 fuel and Special No. 3 diesel fuel, which are formulated for a cold district, are required to have more stringent properties in items such as a pour point than the other gas oils. [0005] The conventional hydrocracking method, however, cannot give fuel bases having a sufficiently lowered pour point, and thus there is a 10 room to improve in a method for preparing gas oil for a cold district. [0006] The conventional oil refinery process gives only a usual gas oil fraction (for example, a fraction having b.p. 260-360*C), and is difficult to satisfy the requirements for No. 3 diesel fuel or Special No. 3 diesel fuel. The gas oil fraction, therefore, is supplied with a kerosene 15 fraction (for example, a fraction having b.p. 140-260°C) to prepare the gas oil for a cold district. The kerosene fraction, however, is highly demanded to use by itself in the cold district, and thus, from an economical point of view, desired to reduce in amount consumed for preparing the gas oil. 20 [0007] Considering this circumstances, an object of the present invention is to provide a hydrocracking method useful for preparation of a gas oil for a cold district, wherein a starting material containing a normal paraffin can be hydrocracked to give a decomposition product having a sufficiently lowered pour point. 25 Means for Solving the Problem [0008] The present inventors have made an intensive investigation to 2 FPO7-0095-00 accomplish the above object, and, as a result, found that a normal paraffin-rich wax can be used as a starting material and hydrocracked to get a given range of conversion rate as defined by the equation (1) to solve the aforementioned problem, and then completed the present 5 invention. [0009] Namely, the method for hydrocracking wax according to the present invention comprises hydrocracking a wax feed containing a normal paraffin having a carbon number of 20 or more at a content of 70% by mass or more in the presence of a hydrocracking catalyst to get 10 a conversion rate of 55 to 95% by mass as defined by the following equation (1): Conversion rate (ass%) Mass of fraction having b.p. below 360C Conversion rate (mass %) = __ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ (1) Mass of wax fraction having b.p. 360'C or above where, in the equation (1), Mass of wax fraction having b.p. 360C or above represents a mass of wax fraction having b.p. 360C or above contained in the wax feed, and Mass of fraction having b.p. below 15 360*C represents a mass of fraction having b.p. below 360C contained in a decomposition product obtained by the hydrocracking, respectively. [0010] The present invention can hydrocrack a starting material containing a normal paraffin to lower sufficiently the pour point of the obtained decomposition product. Therefore the hydrocracking method 20 of the present invention is very useful because it can reduce kerosene in amount consumed for preparation of gas oil for a cold district. [0011] According to the present invention, in order to increase gas oil in yield, the hydrocracking catalyst contains preferably USY zeolite and one or more of solid acids selected from silica-alumina, alumina-boria 3 FPO7-0095-00 and silica-zirconia. [0012] Further, in order to hydrocrack to obtain a gas oil fraction having a sufficiently low pour point, the USY zeolite has preferably an average particle size of 1.0 ptn or less. 5 Effect of the Invention [0013] The present invention provides a hydrocracking method useful for preparation of a gas oil for a cold district, wherein a starting material containing a normal paraffin can be hydrocracked to give a decomposition product having a sufficiently lowered pour point. 10 Brief Description of the Drawings [0014] [Fig. 1] An explanation view of one embodiment of a fixed-bed reaction apparatus used in the present invention. Explanations of Numerals [0015] 1...Reaction tower, 2...hydrocracking catalyst bed, 15 3...Distillation apparatus Best Modes for Carrying Out the Invention [0016] In the followings, the suitable embodiments of the present invention will be explained in detail. [0017] Fig. 1 is an explanation view of one embodiment of a fixed-bed 20 reaction apparatus used preferably in the present invention. [0018] In the fixed-bed reaction apparatus shown in Fig. 1, a hydrocracking catalyst bed 2 is provided in a reaction tower 1. To the top of the reaction tower 1, a line L1 to supply hydrogen into the reaction tower 1 is connected, and a line L2 to supply a wax feed is 25 connected upstream of the connected position of the line L1 and reaction tower 1. On the other hand, to the bottom of the reaction 4 FPO7-0095-00 tower 1, a line L3 is connected to draw out a decomposition product after hydrocracking from the reaction tower 1, and the other end of the line L3 is connected to a distillation apparatus 3 used under atmospheric pressure. 5 [0019] The distillation apparatus 3 can fractionally distil a gas oil fraction having b.p. 260-360 0 C and the other fractions produced by the hydrocracking. The other fractions include a naphtha fraction having b.p. of below 160°C, a kerosene fraction having b.p. of 160-260 0 C and a wax fraction having b.p. of 360 0 C or above. The fractions fractionally 10 distilled at the distillation apparatus 3 are transported to their respective later processes through lines (L4 to L7) connected to the distillation apparatus 3. [0020] As the wax feed, there are preferably used petroleum or synthetic waxes containing a normal paraffin having a carbon number of 15 20 or more (preferably 20 to 100) at a content of 70% by mass or more, more preferably 80% by mass or more. Such a wax includes a petroleum wax such as slack wax and microcrystalline wax, and a synthetic wax such as the so-called FT wax prepared by the FT synthesis. The wax, which contains a normal paraffin having a carbon 20 number of 20 or more at a content of less than 70% by mass, is hydrocracked to give a gas oil fraction which has an elevated pour point and can not satisfy requirements for No. 3 diesel fuel. [0021] The hydrocracking catalyst which composes the hydrocracking catalyst bed 2 is not particularly limited. There may be used as the 25 hydrocracking catalyst for a carrier a solid acid such as 3 zeolite, mordenite, USY zeolite, SSZ-22, SAPO-11, silica-alumina, alumina 5 FPO7-0095-00 boria and silica-zirconia. Particularly, the bed contains more preferably USY zeolite and one or more of amorphous solid acids selected from silica-alumina, alumina-boria and silica-zirconia. [0022] Further, the hydrocracking catalyst preferably contains USY 5 zeolite which has an average particle size of 1.0 pm or less, more preferably 0.5 pm or less. The USY zeolite having an average particle size of more than 1.0 pm is likely to give a gas oil fraction having an elevated pour point. [0023] Further, the USY zeolite has preferably a silica/alumina molar 10 ratio of 25 to 80, more preferably 28 to 50. The USY zeolite having a silica/alumina molar ratio of less than 25 is likely to give a lowered yield of a gas oil fraction. On the other hand, the USY zeolite having a silica/alumina molar ratio of more than 80 causes no problem in yield of a gas oil fraction, but is likely to give a gas oil fraction which has a 15 lowered catalytic activity to need a raised reaction temperature, and thus has a shortened catalyst life. [0024] Further, the hydrocracking catalyst has preferably a USY zeolite content of 6% by mass or less, more preferably 4% by mass or less, and further preferably 3% by mass or less on the basis of the total amount of 20 the hydrocracking catalyst. The hydrocracking catalyst having a USY zeolite content of more than 6% by mass is likely to give a lowered yield of the gas oil fraction. [0025] In addition, the hydrocracking catalyst may further contain a binder for molding a carrier. The binder is not particularly limited, and 25 a preferable carrier is alumina or silica, and among them alumina is more preferable. The carrier is not formed to have a particularly 6 FPO7-0095-00 limited shape, and may be formed into any shape such as particle or column (pellet). [0026] Further, the hydrocracking catalyst preferably holds a metal of the periodic table VIII on the above carrier. The metal to carry is 5 preferably nickel, rhodium, palladium, iridium and platinum, and more preferably palladium and platinum. These metals to carry may be used alone or in a combination of two or more kinds. [0027] The hydrocracking catalyst composing the hydrocracking catalyst bed 2, which contains the aforementioned metal, is preferably 10 pretreated under a reducing atmosphere such as hydrogen gas to reduce the metal before hydrocracking. The reduction condition is not particularly limited. The reduction temperature is preferably 300 360'C, and the reduction time is preferably 1-6 hours, respectively. [0028] The fixed-bed reaction apparatus shown in Fug. 1 is used to 15 hydrocrack the wax feed. In order to satisfy the requirements of No. 3 diesel fuel defined in JIS (Japanese Industrial Standards), it is necessary to carry out the hydrocracking to get a conversion rate of 55 to 95% by mass (preferably 55 to 80% by mass) defined by the aforementioned equation (1). The hydrocracking, which is carried out to get a 20 conversion rate of less than 55% by mass, gives a gas oil fraction having a pour point which does not satisfy the requirement for No. 3 diesel fuel. On the other hand, the hydrocracking, which is carried out to get a conversion rate of more than 95% by mass, gives a lowered yield of a gas oil fraction which can satisfy the requirements for No. 3 diesel fuel, 25 but worsens in economical efficiency of the process. [0029] Further, the reaction conditions for hydrocracking the wax feed 7 FPO7-0095-00 are not particularly limited as far as they allow a conversion rate of 55 to 95% by mass defined by the aforementioned equation (1). The reaction temperature is preferably 370'C or bellow. The reaction temperature of above 370 0 C may easily produce aromatic compounds 5 which are not suitable to give a clean fuel base. Further the reaction pressure is not particularly limited, and the hydrogen fractional pressure is preferably 1-12 MPa, more preferably 2-6 MPa. Further the wax feed has a liquid space velocity which is not particularly limited and is preferably 0.2-5.0 h', more preferably 0.5-3.0 h- 1 . The liquid space 10 velocity of smaller than 0.2 h- 1 is likely to need an enlarged reaction tower which increases a construction cost to worse the economical efficiency of the process. On the other hand, the liquid space velocity of larger than 5.0 h' 1 , which drops the activity, needs a raised reaction temperature to shorten the life of the catalyst. In addition, the 15 hydrogen/oil ratio is not particularly limited, and is preferably 200-850 NL/L, more preferably 350-650 NL/L. [0030] According to the aforementioned embodiment, the wax feed which contains a normal paraffin having a carbon number of 20 or more at a content of 70% by mass or more is hydrocracked to get a 20 conversion rate of 55 to 95% by mass as defined by the aforementioned equation (1), allowing a high yield of the gas oil fraction having a sufficiently low pour point. This gas oil fraction, which can satisfy the requirements of No. 3 diesel fuel defined in JIS, can be used as a gas oil base. Accordingly, the gas oil base can reduce sufficiently kerosene in 25 amount consumed for preparing gas oil for a cold district. [0031] The present invention is not limited to the aforementioned 8 FPO7-0095-00 embodiments. For instance, the hydrocracking catalyst bed 2, which has a mono-layered construction in the aforementioned embodiment, may have a multi-layered construction wherein different kinds of hydrocracking catalyst beds are stacked. Further, as the apparatus for 5 hydrocracking the wax feed, a fixed-bed reaction apparatus is exemplified. The apparatus is not particularly limited as far as it allows the wax feed and the hydrocracking catalyst to contact with each other. For instance, a fluidized-bed reaction apparatus may be employed. 10 Examples [0032] In the following, the present invention is explained in more detail by referring Examples and Comparative Examples, but the present invention is not limited to the following Examples mentioned bellow. 15 [0033] (Example 1) A USY zeolite having an average particle size of 0.9 pm (molar ratio of silica/alumina: 37), a silica-alumina (alumina content 14% by mass) and an alumina binder are used to mold a columnar carrier (USY zeolite/silica-alumina/alumina binder = 4/56/40 (mass ratio)) of <p 1.5 20 mm and length about 3 mm. This carrier was impregnated with an aqueous solution of platinum chloride acid to hold 0.8% by mass of platinum relative to the carrier. This was dried at 120'C for 3 hours and then sintered at 500*C for 1 hour to obtain a hydrocracking catalyst. [0034] Next, the reaction tower 1 of the fixed-bed reaction apparatus 25 shown in Fig. 1 was filled with 100 ml of the obtained hydrocracking catalyst to form the hydrocracking catalyst bed 2, which was then used 9 FPO7-0095-00 to hydrocrack the wax feed. [0035] Firstly, the hydrocracking catalyst was reduced under a hydrogen stream at 345°C for 4 hours. Then, the wax feed was hydrocracked. As the wax feed, FT wax (carbon number 21-80, 5 normal paraffin content 95% by mass) was used. As the reaction conditions for hydrocracking, the liquid space velocity of the wax feed to the total amount of the hydrocracking catalyst was 2.0 h- (flow rate of the wax feed: 200 ml/h), the fractional pressure of hydrogen was 3 VMPa, the hydrogen/oil ratio was 570 NL/L, and a reaction temperature 10 was set to get a conversion rate of 60% by mass defined by the aforementioned equation (1). The reaction temperature at that time was 293"C. [0036] The obtained decomposition product was distilled to obtain a gas oil fraction having b.p. 260-360 0 C. The properties of the obtained 15 gas oil fraction and the yield of gas oil are shown in Table 1. The yield of gas oil is a value calculated from the following equation (2). Mass of gas oil fraction Yield of gas oil = Mass of wax feed x 100 (2) Mass of wax feed [0037] The properties of gas oil fraction shown in Table 1 are a flash point, a temperature for 90% distillation, a pour point, a cold filter 20 plugging point, a carbon residue of 10% distillation residue, a cetane number, a kinematic viscosity (30*C), a sulfur content, and a density (15'C). With respect to each of the properties, the flash point was measured according to the requirements of JIS K 2265, the temperature for 90% distillation was according to JIS K 2254, the pour point was 25 according to JIS K 2269, the cold filter plugging point was according to 10 FPO7-0095-00 JIS K 2288, the carbon residue of 10% distillation residue was according to JIS K 2270, the cetane number was according to JIS K 2280, the kinematic viscosity was according to JIS K 2283, the sulfur content was according to JIS K 2541, the density was according to JIS 5 K 2249. In Table 1, the requirements of No. 3 diesel fuel are mentioned together. [6038] (Example 2) The wax feed was hydrocracked to give a decomposition product, which was then distilled to give a gas oil fraction, in the same 10 manner as in Example 1 except that the reaction temperature was set to get a conversion rate of 82% by mass as defined by the aforementioned equation (1). The reaction temperature at that time was 301'C. The properties of the obtained gas oil fraction and the yield of gas oil are shown in Table 1. 15 [0039] (Example 3) The wax feed was hydrocracked to give a decomposition product, which was then distilled to give a gas oil fraction, in the same manner as in Example 1 except that a USY zeolite having an average particle size of 0.5 pm was used instead of the USY zeolite having an 20 average particle size of 0.9 jim. The reaction temperature to get a conversion rate of 60% by mass was 291*C. The properties of the obtained gas oil fraction and the yield of gas oil are shown in Table 1. [0040] (Example 4) The wax feed was hydrocracked to give a decomposition 25 product, which was then distilled to give a gas oil fraction, in the same manner as in Example 1 except that a mixture of 40 parts by mass of the 11 FPO7-0095-00 FT wax used in Example 1 and 60 parts by mass of a petroleum paraffin wax was used as the wax feed. The wax feed contained the normal paraffin having a carbon number of 20 or more at a content of 86% by mass. The reaction temperature to get a conversion rate of 60% by 5 mass was 292'C. The properties of the obtained gas oil fraction and the yield of gas oil are shown in Table 1. [0041] (Comparative Example 1) The wax feed was hydrocracked to give a decomposition product, which was then distilled to give a gas oil fraction, in the same 10 manner as in Example 1 except that a petroleum paraffin wax which contained the normal paraffin having a carbon number of 20 or more at a content of 67% by mass was uses as the wax feed. The reaction temperature to get a conversion rate of 60% by mass was 298°C. The properties of the obtained gas oil fraction and the yield of gas oil are 15 shown in Table 1. [0042] (Comparative Example 2) The wax feed was hydrocracked to give a decomposition product, which was then distilled to give a gas oil fraction, in the same manner as in Example 1 except that the reaction temperature was set to 20 get a conversion rate of 40% by mass as defined by the aforementioned equation (1). The reaction temperature at that time was 286°C. The properties of the obtained gas oil fraction and the yield of gas oil are shown in Table 1. 12 D L U COl 6C ''Y1-6o E cv A - 1 0 o 0 30 0 D ci C) 1N 0 f u LJ c- '-0 j C- co Lu - ' 0 N 60 U? co (D0 Y 0 coU c~i LO o. (J 0)0 ) U) C% 0 0 0
C,
5 0o Oc' 0 co q r-( T- 0 (n () U) (n E) 01 cl l c ~ '.. U0 U 0) U) a) a) 0 a a) a)~ Uf a ) o 0 ~ 0a a) a) 0 ~ 0 0 0 L- L .. 0 4 0 FPO7-0095-00 [0043] As shown in Table 1, the wax feed containing the normal paraffin having a carbon number of 20 or more at a content of 70% by mass or more is used and hydrocracked to get a conversion rate of 55 to 95% by mass as defined by the aforementioned equation (1), allowing a 5 high yield of the gas oil fraction (fraction having b.p. 260-360'C) which satisfies the requirements for No. 3 diesel fuel. Industrial Applicability [0044] The present invention provides a hydrocracking method useful for preparation of a gas oil for a cold district, wherein a starting material 10 containing a normal paraffin can be hydrocracked to give a decomposition product having a sufficiently lowered pour point. 14