FP07-0097-00 DESCRIPTION PROCESS FOR PRODUCING LIQUID FUEL BASE Technical Field [0001] The present invention relates to a method for producing a liquid 5 fuel basestock. Background Art [0002] Recently, environmental control against liquid fuels such as gasoline and diesel 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. The field of fuel oil production also has studied various methods for producing a clean fuel which has a sulfur content reduced to 10 ppm or less. [0003] One of such preparation methods of clean fuels is Fisher Tropsch (FT) synthesis wherein hydrogen and carbon mono-oxide 15 obtained by gasifying asphalt or coal or by reforming natural gas are used as starting materials. The FT synthesis can give a liquid fuel basestock which is rich in paraffin and contains no sulfur [0004] The FT synthesis can produce a wax. A hydro-cracking of this wax gives a decomposition product which can be used as a clean fuel 20 basestock. It is important of the synthesis that the wax can be hydro cracked to allow high selection of a gasoline fraction, a kerosene fraction and a diesel oil fraction which are useful as a fuel basestock, that is, to inhibit the production of gases which are lighter than the gasoline fraction. This inhibition of the production of the light gases 25 contributes largely improvement of economical efficiency in the whole processes. Therefore, there has been studied a production method of 1 C:WRonb\DCWAM 799547.1.DOC-/0/011 -2 liquid fuel basestocks which attaches importance to the selectivity of those fractions. For instance, in Patent Document 1, there is described a method to produce a medium fractions from a wax by using a catalyst with platinum supported on an amorphous silica-alumina. 5 Patent Document 1: JP-Al-H06-41549 Disclosure of the Invention [0005] As in Patent Document 1, as an elemental technique for producing a liquid fuel basestock from a wax, a catalyst to use in the method has been intensively developed. In reality, however, there has not yet been 10 developed a process for sufficiently inhibiting the production of light gases. [0006] One or more embodiments of the present invention may provide a method for producing a liquid fuel basestock wherein a starting material containing a normal paraffin is hydro-cracked to sufficiently inhibit 15 production of the light gases. Means for Solving the Problem [0007] The present inventors have found that a catalyst containing a USY zeolite having an average particle size of 0.8 pm or less can be used to hydro-crack a paraffin hydrocarbon to get a given range of decomposition 20 rate which may solve the aforementioned problem. [0008] The method for producing a liquid fuel basestock according to the present invention comprises hydro-cracking a paraffin hydrocarbon in the presence of a hydro-cracking catalyst which contains a USY zeolite having C:\NRPonbrDCCWAM799547_.DOC-88OI/0 -3 a molar ratio of silica/alumina of from 25 to 50 and having an average particle size of 0.8 pm or less to get a decomposition rate of 75 to 90% by mass as defined by the following equation (1): Mass of fraction having b.p. 360 0 C or below contained in decomposition product Decomposition rate (mass %) = x 100 (1). Total mass of decomposition product 5 [0009] According to certain embodiments of the present invention, a paraffin hydrocarbon is hydro-cracked to allow the sufficiently inhibited production of the light gases. Concretely, the production of light gases having a carbon number of 1 to 3 may be inhibited to get 1.8% by mass or 10 less on the basis of the total mass of the obtained decomposition product. Therefore the method for producing a liquid fuel basestock according to embodiments of the present invention may be very useful because of its improvement in economical efficiency of processes for producing a liquid fuel. 15 [0010] According to some embodiments of the present invention, in order to inhibit sufficiently the light gases from producing, the hydro-cracking catalyst preferably contains USY zeolite having an average particle size of 0.5 pm or less. Further, similarly, the hydro-cracking catalyst contains preferably an alumina-boria. 20 [0011] Further, according to some embodiments of the present invention, the paraffin hydrocarbon is preferably a wax (FT wax) prepared by Fisher Tropsch (FT) synthesis, because the FT wax has a high content of paraffin C:\NRortblCC\WAM\799547_l.DOC-&/0211 -4 and also contains substantially no sulfur. Effect of the Invention [0012] The present invention provides a method for producing a liquid fuel basestock wherein a starting material containing a normal paraffin can be 5 hydro-cracked to give a decomposition product with sufficiently inhibited production of the light gases. Brief Description of the Drawings [0012A] Various embodiments of the present invention will be described, by way of example only, with reference to the following drawing. 10 [0013] [Fig. 1] An explanation view of one embodiment of a fixed-bed reaction apparatus used in the present invention. Explanations of Numerals [0014] 1 ... Reaction tower, 2 ... Hydro-cracking catalyst bed, 3 ... Distillation apparatus, 15 L1, L2, L3, L4, L5, L6, L7, L8 ... Line. Best Modes for Carrying Out the Invention [0015] In the following description, suitable embodiments of the present invention will be explained in detail. [0016] Fig. 1 is an explanation view of one embodiment of a fixed-bed 20 reaction apparatus used preferably in the present invention. [00171 In the fixed-bed reaction apparatus shown in Fig. 1, a hydro cracking catalyst bed 2 is provided in a reaction tower 1. To the top of the reaction tower 1, a line Li to supply hydrogen into the reaction tower 1 is C:\NRtblDCCWAMU79547_I.DOC-L02OI I -5 connected, and a line L2 to supply a paraffin hydrocarbon is connected upstream of the connected position of the line Li and reaction tower 1. On the other hand, to the bottom of the reaction tower 1, a line L3 is connected to draw out a decomposition product after hydro-cracking from 5 the reaction tower 1, and the other end of the line L3 is connected to a distillation apparatus 3 used under atmospheric pressure. [0018] The distillation apparatus 3 can fractionally distil the decomposition product into fractions. The fractionally distilled fractions include a gas fraction having a boiling point (b.p.) of less than 30'C, 10 naphtha fraction having b.p. of 30-160*C, kerosene fraction having b.p. of 160-260*C, diesel oil fraction having b.p. of 260-360"C and wax fraction at b.p. of not less than 360*C. The fractions fractionally distilled at the distillation apparatus 3 are transported to their respective later processes through lines (L4 to L8) connected to the distillation apparatus 3. 15 [00191 The paraffin hydrocarbon used as the starting material is a composition of hydrocarbons which comprise mainly a normal paraffin and have a low degree of branching. The composition comprises preferably normal paraffins at a content of 80% by mass or more, more preferably 85% by mass or more on the basis of the total mass of the 20 paraffin hydrocarbon. [0020] The carbon number of a hydrocarbon contained in the paraffin hydrocarbon is not particularly limited, and is usually in the range of from 15 to 100. Such a wax includes a petroleum wax such as slack wax and C.WRPortbhDCC\WAMU799547_L.DO>C-808/211 -6 microcrystalline wax, and a synthetic wax such as the so-called FT wax prepared by the FT synthesis. The FT wax is particularly preferred as a wax because of its reduced load on environment. [0021] The hydro-cracking catalyst which composes the hydro-cracking 5 catalyst bed 2 contains a USY zeolite having an average particle size of 0.8 pm or less as a carrier. In order to inhibit sufficiently the production of the light gases, the USY zeolite has more preferably an average particle size of 0.5 pm or less. With a USY zeolite which has an average particle size of more than 0.8 pm it is difficult to inhibit sufficiently the production 10 of the light gases. [0022] Further, in order to inhibit sufficiently the production of the light gases, the hydro-cracking catalyst preferably comprises the USY zeolite and one or more of amorphous solid acids selected from silica-alumina, alumina-boria and silica-zirconia, and more preferably comprises the USY 15 zeolite and alumina-boria. [0023] In the present invention, the USY zeolite has a molar ratio of silica/alumina (silica/alumina ratio) of from 25 to 50. A USY zeolite which has a silica/alumina ratio of less than 25 is likely to increase the production of the light gases. On the other hand, a USY zeolite which has 20 a silica/alumina ratio of more than 50 is likely to need a raised reaction temperature because of its lowered catalytic activity, thereby shortening the life of the catalyst. [0024] Further, the hydro-cracking catalyst has preferably a USY zeolite C:\NR rbl\CC\WAMG79547_l.DOC-V0812011 -7 content of 1-30% by mass on the basis of the total amount of the hydro cracking catalyst. A hydro-cracking catalyst which has a USY zeolite content of less than 1% by mass is likely to need a raised reaction temperature because of its lowered catalytic activity, thereby shortening 5 the life of the catalyst. On the other hand, a hydro-cracking catalyst which has a USY zeolite content of more than 30% by mass is likely to increase the production of the light gases. [00251 Further, in some embodiments, a hydro-cracking catalyst which contains the USY zeolite and alumina-boria has preferably an alumina 10 boria content of 5-70% by mass on the basis of the total amount of the hydro-cracking catalyst. A hydro-cracking catalyst which has an alumina-boria content of less than 5% by mass is likely to exhibit an insufficient effect in spite of the added alumina-boria, and on the other hand, a hydro-cracking catalyst which has an alumina-boria content of 15 more than 70% by mass is likely to increase the production of the light gases. [0026] The alumina-boria has preferably an alumina/boria mass ratio of 1.2-7.8. Alumina-boria which has an alumina/boria mass ratio of outside the aforementioned range is likely to increase the production of the light 20 gases. [0027] In addition, the hydro-cracking catalyst may further contain a binder for molding a carrier. The binder is not particularly limited, and a preferable carrier is boehmite or silica, and among them boehmite is C:\NRtrtbDCCWAM\1399547_1 DOC-//2OI I -8 preferable. The carrier is not formed to have a particularly limited shape, and may be formed into any shape such as particle or column (pellet). [0028] Further, the hydro-cracking catalyst preferably holds a metal selected from the periodic table VIa and VIII on the above carrier. 5 Examples of the VIa metals are chromium, molybdenum, tungsten, and examples of VIII metals are cobalt, nickel, rhodium, palladium, iridium and platinum. Among them, more preferable are palladium and platinum, and further preferable is platinum. These metals to hold may be used alone or in a combination of two or more kinds. The amount of the metal 10 to hold is not particularly limited. Palladium and platinum are generally held to have a range of 0.05 to 2.0% by mass on the basis of the mass of the carrier. [0029] A hydro-cracking catalyst composing the hydro-cracking catalyst bed 2, which contains the aforementioned metal, is preferably pretreated 15 under a reducing atmosphere such as hydrogen gas to reduce the metal before hydro-cracking. 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. [0030] The fixed-bed reaction apparatus shown in Fig. 1 is used to hydro 20 crack the paraffin hydrocarbon. In order to inhibit sufficiently the production of light gases (carbon number 1-3), it is necessary to carry out the hydro-cracking in such a manner as to get a decomposition rate of from 75 to 90% by mass (preferably from 77 to 88% by mass) as defined C:\4RPonbl\DCC\WAMU799547_1.DOC42lOI I -9 by the aforementioned equation (1). Hydro-cracking which is carried out so as to get a decomposition rate of less than 75% by mass increases the production of a wax fraction, resulting in difficulty in producing the liquid fuel basestock with high selectivity. On the other hand, hydro-cracking 5 which is carried out so as to get a decomposition rate of more than 90% by mass increases the production of the light gases. [0031] Further, the reaction conditions for hydro-cracking a paraffin hydrocarbon are not particularly limited as far as they allow a decomposition rate of from 75 to 90% by mass as defined by the 10 aforementioned equation (1). Typical reaction conditions are: reaction temperature 250-370*C, hydrogen fractional pressure 0.5-10.0 MPa, liquid space velocity of the paraffin hydrocarbon 0.1-5.0 h-1, and hydrogen/oil ratio 150-2000 NL/L. Hydro-cracking which is carried out under reaction conditions out of these ranges is likely to increase the 15 production of the light gases. [00321 Further, in order to adjust the decomposition rate to a desired value as defined by the equation (1), for example, the reaction temperature may be controlled after the reaction conditions for hydro-cracking are set within the aforementioned ranges. 20 [0033] The present invention is not limited to the aforementioned embodiments. For instance, the hydro-cracking catalyst bed 2, which has a mono-layered construction in the aforementioned embodiment, may have a multi-layered construction wherein different kinds of hydro- C:\NRPonblOCCWAM3799547_I.DOC-WfZ/201 I - 9A cracking catalyst beds are stacked. Further, as the apparatus for hydro cracking the paraffin hydrocarbon, a fixed-bed reaction apparatus is exemplified. The apparatus is not particularly limited as far as it allows paraffin hydrocarbon and the hydro-cracking catalyst to contact with each 5 other. For instance, a fluidized-bed reaction apparatus may be employed. Examples [0034] In the following, some embodiments of the present invention are explained in more detail by referring to Examples and Comparative Examples, but the present invention is not limited to the following 10 Examples mentioned below. [0035] <Preparation of hydro-cracking catalyst> (Catalyst 1) 5 parts by mass of USY zeolite having an average particle size of 0.7 pm (silica/alumina ratio: 30) and 95 parts by mass of boehmite 15 (binder) were mixed and kneaded sufficiently to form a columnar carrier having 01.6 mm (1/16 inch) and length about 3 mm, which was then dried at 120"C for 3 hours and sintered at 500*C for 1 hour to obtain a carrier. The carrier was impregnated with an aqueous solution of dichlorotetraamine platinum (II) and made to support 0.5% by mass of 20 platinum relative to the carrier. This was dried at 120*C for 3 hours and sintered at 500*C for 1 hour to obtain a hydro-cracking catalyst (Catalyst 1).
C:\N lbI\DCOWAM3799471.DOC-8/3/20I I - 9B [0036] (Catalyst 2) A hydro-cracking catalyst (Catalyst 2) was obtained in the same FP07-0097-00 manner as in Catalyst 1 except that 5 parts by mass of USY zeolite having an average particle size of 0.4 pm (silica/alumina ratio: 32) and 95 parts by mass of boehmite (binder) were mixed and kneaded sufficiently to form a molded article. 5 [0037] (Catalyst 3) A hydro-cracking catalyst (Catalyst 3) was obtained in the same manner as in Catalyst 1 except that 5 parts by mass of USY zeolite having an average particle size of 0.4 pm (silica/alumina ratio: 32), 55 parts by mass of alumina-boria (mass ratio of alumina/boria: 5.5) and 40 10 parts by mass of boehmite (binder) were mixed and kneaded sufficiently to form a molded article, and further the carrier was made to support 0.4% by mass of platinum relative to the carrier. [0038] (Catalyst 4) A hydro-cracking catalyst (Catalyst 4) was obtained in the same 15 manner as in Catalyst 1 except that 5 parts by mass of USY zeolite having an average particle size of 1.2 pm (silica/alumina ratio: 30) and 95 parts by mass of boehmite (binder) were mixed and kneaded sufficiently to form a molded article. [0039] (Catalyst 5) 20 A hydro-cracking catalyst (Catalyst 5) was obtained in the same manner as in Catalyst 1 except that 70 parts by mass of silica-alumina (molar ratio of silica/alumina: 2.3) and 30 parts by mass of boehmite (binder) were mixed and kneaded sufficiently to form a molded article. [0040] The compositions of the carriers of Catalysts 1 to 5, the 25 properties of the USY zeolite and the amount of supported platinum are shown in Table 1. 10 FP07-0097-00 Table 1 Catalyst Catalyst Catalyst Catalyst Catalyst 1 2 3 4 5 USY zeolite 5 5 5 5 Composition of Alumina-boria - - 55 - Carrier (% by mass) Silica-alumina - - - - 70 Boehmite 95 95 40 95 30 Average Properties of particle size 0.7 0.4 0.4 1.2 USY zeolite Silica/alumina 30 32 32 30 ratio Amount of supported platinum 0.5 0.5 0.4 0.5 0.5 (% by mass) 0. 0 0 0 0.5 [0041] <Hydro-cracking of paraffin hydrocarbon> (Example 1) 5 The reaction tower 1 of the fixed-bed reaction apparatus shown in Fig. 1 was filled with Catalyst 1 (100 ml) to form the hydro-cracking catalyst bed, which was then used to hydro-crack a paraffin hydrocarbon. [0042] Firstly, the hydro-cracking catalyst was reduced under a 10 hydrogen stream at 345*C for 4 hours. Then, a paraffin hydrocarbon was hydro-cracked. As the paraffin hydrocarbon, FT wax (carbon number 28-80 (boiling temperature of 361 C or above), normal paraffin content: 88% by mass) was used. As the reaction conditions of the hydro-cracking, the liquid space velocity of the FT wax was 2.0 h 15 (flow rate of FT wax: 200 ml/h), the fractional pressure of hydrogen was 5 MPa, the ratio of hydrogen/oil was 700 NL/L, and the temperature was 320*C. Distillation test of the decomposition product showed that these reaction conditions gave a decomposition rate of 79% by mass as defined by the aforementioned equation (1). 11 FP07-0097-00 [0043] The amount of the light gases (carbon number 1-3) contained in the decomposition product was quantified by on-line gas chromatography. In Table 2, the production of the light gases is shown on the basis of the total mass of the decomposition product. In Table 5 2, the hydro-cracking catalyst used, the reaction temperature for hydro cracking and the decomposition rate are mentioned together. [0044] (Example 2) The hydro-cracking of a paraffin hydrocarbon was carried out and the production of the light gases was measured in the same manner 10 as in Example 1 except that the reaction tower 1 was filled with Catalyst 2 (100 ml) to form the hydro-cracking catalyst bed and the reaction temperature for hydro-cracking was 318'C. As the paraffin hydrocarbon, the same FT wax as in Example 1 was used. The reaction conditions of this Example gave a decomposition rate of 82% 15 by mass. The results are shown in Table 2. [0045] (Example 3) The hydro-cracking of a paraffin hydrocarbon was carried out and the production of the light gases was measured in the same manner as in Example 1 except that the reaction tower 1 was filled with Catalyst 20 3 (100 ml) to form the hydro-cracking catalyst bed and the reaction temperature for hydro-cracking was 304*C. As the paraffin hydrocarbon, the same FT wax as in Example 1 was used. The reaction conditions of this Example gave a decomposition rate of 87% by mass. The results are shown in Table 2. 25 [0046] (Comparative Example 1) The hydro-cracking of a paraffin hydrocarbon was carried out 12 FP07-0097-00 and the production of the light gases was measured in the same manner as in Example 1 except that the reaction tower 1 was filled with Catalyst 4 (100 ml) to form the hydro-cracking catalyst bed and the reaction temperature for hydro-cracking was 322*C. As the paraffin 5 hydrocarbon, the same FT wax as in Example 1 was used. The reaction conditions of this Example gave a decomposition rate of 80% by mass. The results are shown in Table 2. [0047] (Comparative Example 2) The hydro-cracking of a paraffin hydrocarbon was carried out 10 and the production of the light gases was measured in the same manner as in Example 1 except that the reaction tower 1 was filled with Catalyst 5 (100 ml) to form the hydro-cracking catalyst bed and the reaction temperature for hydro-cracking was 363'C. As the paraffin hydrocarbon, the same FT wax as in Example 1 was used. The 15 reaction conditions of this Example gave a decomposition rate of 81% by mass. The results are shown in Table 2. Table 2 Ex. 1 Ex. 2 Ex. 3 Comp. Comp. Ex.1 Ex.2 Catalyst used Catalyst Catalyst Catalyst Catalyst Catalyst 1 2 3 4 5 Reaction temperature 320 318 304 322 363 (C) Decomposition rate 79 82 87 80 81 (% by mass) Production of light gases 1.5 1.5 1.6 1.9 2.2 (% by mass) 1_1 [0048] As mentioned above, the hydro-cracking catalyst containing the 20 USY zeolite having an average particle size of 0.8 pm or less was used 13 C:\NRPonblDCC\WAM\3799547_LDOC-8V/201 I - 14 to hydro-crack a paraffin hydrocarbon, allowing sufficient inhibition of the production of the light gases. Industrial Applicability [0049] One or more embodiments of the present invention may provide a 5 method for producing a liquid fuel basestock wherein a starting material containing a normal paraffin can be hydro-cracked to give a decomposition product with sufficiently inhibited production of the light gases. [0050] Throughout this specification and the claims which follow, unless 10 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 step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps. [0051] The reference in this specification to any prior publication (or 15 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 common general knowledge in the field of endeavour to which this specification relates.