AU2007231959B2

AU2007231959B2 - Method of hydrocracking wax

Info

Publication number: AU2007231959B2
Application number: AU2007231959A
Authority: AU
Inventors: Masahiro Higashi; Hiroyuki Seki
Original assignee: Nippon Oil Corp
Current assignee: Eneos Corp
Priority date: 2006-03-30
Filing date: 2007-03-13
Publication date: 2011-10-13
Anticipated expiration: 2027-03-13
Also published as: JP2007269902A; MY146666A; RU2428458C2; CN101410489A; AU2007231959A1; CN101410489B; JP4769110B2; WO2007114000A1; RU2008142949A

Abstract

A method of hydrocracking a wax, characterized in that in a fixed bed reactor provided with a catalytic reaction section having, disposed in sequence, a first catalyst layer containing a first amorphous solid acid, a second catalyst layer containing zeolite and a third catalyst layer containing a second amorphous solid acid, in the presence of hydrogen, a wax is caused to flow from the first catalyst layer toward the third catalyst layer of the catalytic reaction section.

Description

FP07-0099-00 DESCRIPTION METHOD OF HYDROCRACKING WAX Technical Field [0001] The present invention relates to a method for hydrocracking wax. 5 Background Art [0002] There has been demand in recent years for environmentally friendly clean liquid fuels, that is, low-aromatic hydrocarbon, low-sulfur fuels. As a result, methods for producing clean fuels have been the subject of a broad array of research, and the Fischer-Tropsch (FT) 10 synthesis has received attention as one such method. There are also expectations for the FT synthesis going forward because it uses carbon monoxide and hydrogen as its starting materials and can produce a paraffin-rich, sulfur-free liquid fuel base stock. [0003] While the FT synthesis can produce wax, this wax can be 15 hydrocracked and the resulting cracking product can also be used as a clean fuel base stock. In this case, middle distillate usable as a liquid fuel base stock for gasoline and is generally the target product. This has resulted in research into liquid fuel base stock production methods that emphasize middle distillate selectivity. For example, a method is 20 described in Patent Document 1 that produces middle distillate from wax using a catalyst in which platinum is supported on amorphous silica-alumina. [0004] In addition, research has been carried out into the conversion by hydroisomerization of the normal-paraffin present in wax into 25 isoparaffin and the use of the isoparaffin-rich product as a lubricating oil base stock. As methods for producing a lubricating oil base stock from FP07-0099-00 wax, Patent Document 2 describes a method that uses a catalyst in which, for example, cobalt, molybdenum, or nickel is supported on amorphous silica-alumina and Patent Document 3 describes a method that uses a zeolite-type catalyst. 5 Patent Document 1: Japanese Patent Application Laid-open No. Hei 6 41549 Patent Document 2: WO 00/14183 Patent Document 3: WO 04/081157 Disclosure of the Invention 10 Problem to be Solved by the Invention [0005] As a general matter, cracking denotes chemical reactions that are accompanied by a reduction in molecular weight, while isomerization denotes conversion into another compound while maintaining the molecular weight intact. Hydrocracking produces hydrocarbon with a 15 boiling point lower than that of the hydrocarbon subjected to the hydrocracking treatment. In hydroisomerization, on the other hand, the degree of branching in the incoming hydrocarbon is raised while the number of carbons therein is maintained unchanged. When wax is employed as the incoming hydrocarbon and this wax is subjected to 20 hydrocracking in the presence of a catalyst, both hydrocracking reactions and hydroisomerization reactions proceed with complex interactions therebetween. [0006] The catalyst is a key technology for the production of liquid fuel base stock and lubricating oil base stock from wax, and as a result the 25 technical development of the catalyst used for this purpose has heretofore been vigorously pursued. However, hydrocracking has a

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C:\NR~onbr\DCC\WAM\388000_. DOC-16A)9 2011 -3 complex reaction mechanism because, in addition to hydroisomerization, it is also accompanied by reactions such as hydrogen migration and carbon deposition. As a consequence, notwithstanding many years of research and development focusing on the catalyst, it has not been 5 entirely possible to obtain a cracking product that has the desired properties. [0007] In specific terms, it has not been possible to bring the yield of the middle distillate target product in wax hydrocracking to an acceptably high level. There have also been other problems originating in the fact 10 that the isomerisation rate has been inadequate, such as an inadequate low-temperature fluidity for the middle distillate and particularly for the gas oil fraction and a lubricating oil base stock yield that has remained low. (0008] The present invention was pursued considering the 15 circumstances described above and the present invention seeks to provide a method for hydrocracking wax that can achieve both a high middle distillate yield and a high lubricating oil base stock yield and at the same time that can produce a gas oil fraction that exhibits an excellent low temperature fluidity. 20 Means for Solving the Problem [0009] The wax hydrocracking method according to the present invention is characterized in that, in a fixed bed reactor that is provided with a catalytic reaction region in which a first catalyst layer containing a first amorphous solid acid, a second catalyst layer containing a zeolite, 25 and a third catalyst layer containing a second amorphous solid acid are disposed in this order, the wax is caused to flow from the first catalyst C:\NRPorb\DCCW AMusAN_1.DOC-I6APJ120j I -4 layer toward the third catalyst layer in the catalytic reaction region in the presence of hydrogen. [0010] By bringing about the hydrocracking reactions and hydroisomerization reactions in a catalytic reaction region provided with 5 a trilayer catalyst layer, the present invention can bring both the middle distillate yield and the normal-paraffin-to-isoparaffin isomerisation rate to high levels. A liquid fuel base stock can be efficiently produced from the wax due to the satisfactorily high middle distillate yield. Moreover, a satisfactorily improved low-temperature fluidity is obtained for the 10 resulting gas oil fraction and lubricating oil fraction since the isomerisation rate can be brought to a satisfactorily high level. [0011] The middle distillate referenced by the present invention denotes a fraction that contains at least 90 mass% hydrocarbon with a boiling point of at least 150"C but not higher than 360 0 C, while the 15 lubricating oil fraction referenced by the present invention denotes a fraction that contains at least 90 mass% hydrocarbon with a boiling point above 360*C. The gas oil fraction denotes a fraction that is a part of the middle distillate and that contains at least 90 mass% hydrocarbon with a boiling point of at least 260 0 C but not higher than 360'C. 20 [0012] In advantageous embodiments, the present invention enables the production of lubricating oil base stocks at satisfactorily high yields. A lubricating oil base stock is generally produced by carrying out a dewaxing treatment to reduce the content of the wax fraction whose main component is normal-paraffin that is present in 25 the lubricating oil fraction of the cracking product. Since the lubricating oil fraction present in the cracking product that can be yielded C:WRPorb\DCC\WAM 38500X0_I DOC-16tt9/20II -5 by the method of the present invention has a rich isoparaffin content due to the hydroisomerization, there is little normal-paraffin removal in the dewaxing treatment and a high lubricating oil base stock yield can thereby be achieved. 5 [0013] The second catalyst layer of the present invention preferably contains ultrastable Y-type zeolite (USY zeolite) as the zeolite. The presence of USY zeolite in the second catalyst layer can enable hydrocracking to be carried out more efficiently than the presence of other types of zeolite. 10 [0014] The first catalyst layer and the third catalyst layer preferably contain, as the first amorphous solid acid and the second amorphous solid acid, respectively, at least one type selected from silica-alumina, silica zirconia, and silicoaluminophosphate. The use of a first or second amorphous solid acid containing such an amorphous solid acid can 15 enable an additional increase in the isomerisation rate to be achieved in comparison to the use of amorphous solid acid other than the aforementioned. [0015] The first catalyst layer preferably contains at least one metal selected from platinum and palladium supported on the first amorphous 20 solid acid; the third catalyst layer preferably contains at least one metal selected from platinum and palladium supported on the second amorphous solid acid; and the second catalyst layer preferably contains at least one metal selected from platinum and palladium supported on the zeolite. It is because hydrocracking can be carried out more 25 efficiently, as compared to the use of catalyst that does not carry these metals, when a catalyst comprising platinum and/or palladium C:WRonbl\DCC\WAM\3U8X8201_.DOC.16A1912011 -6 supported on the amorphous solid acid is used for the first and third catalyst layers and a catalyst comprising platinum and/or palladium supported on the zeolite is used for the second catalyst layer. [0016] The wax used by the present invention is preferably a wax 5 obtained by the Fischer-Tropsch synthesis. Waxes obtained by the FT synthesis substantially do not contain environmentally burdensome substances such as sulphur and aromatic hydrocarbon. As a consequence, the use of wax obtained by the FT synthesis as the wax feedstock enables the production of middle distillate and lubricating oil 10 base stock with a well reduced content of environmentally burdensome substances. Effect of the Invention [0017] The present invention provides a wax hydrocracking method that can achieve both a high middle distillate yield and a high lubricating 15 oil base stock yield and at the same time that can produce a gas oil fraction that has an excellent low-temperature fluidity. Brief Description of the Drawings [0018] An embodiment of the invention will be described with reference to the following non-limiting drawing in which: 20 Figure 1 is an explanatory drawing that shows an example of a fixed bed reactor used by the present invention. Examples of Numerals [0019] 1: catalytic reaction region, 1 a: catalyst layer (first catalyst layer), lb: catalyst layer (second catalyst layer), 1c: catalyst layer (third 25 catalyst layer), 10: reaction column (fixed bed reactor). Best Modes for Carrying Out the Invention [0020] Suitable embodiments of the present invention are described in detail in the following with reference to the drawing. Figure 1 is an explanatory drawing that shows a preferred example of a fixed bed 30 FP07-0099-00 reactor according to an embodiment of the present invention. The fixed bed reactor shown in Figure 1 carries out hydrocracking and hydroisomerization in a reaction column 10 and has a catalytic reaction region 1 disposed within the reaction column 10. 5 [0021] A line LI is connected to the top of the reaction column 10 in order to feed hydrogen into the reaction column 10, while a wax feed line L2 is connected to the line LI upstream from the connection of the line LI to the reaction column 10. This enables wax hydrocracking and hydroisomerization to be carried out by introducing wax and hydrogen 10 into the reaction column 10 and causing the same to flow through the catalytic reaction region 1. A line L3 is connected to the bottom of the reaction column 10 for recovery of the cracking product. [0022] While Figure 1 shows an example of a reactor in which the wax feed line L2 and the hydrogen feed line LI are combined, the hydrogen 15 feed line LI and the wax feed line L2 may be separately connected to the reaction column 10. The flow direction of the wax is preferably from the top side of the reaction column 10 toward the bottom side thereof, as shown in Figure 1. [0023] The catalytic reaction region 1 is provided with a catalyst layer 20 la containing the first amorphous solid acid (first catalyst layer), a catalyst layer lb containing zeolite (second catalyst layer), and a catalyst layer Ic containing the second amorphous solid acid (third catalyst layer). These catalyst layers are disposed in the catalytic reaction region 1 in the sequence of catalyst layer la, catalyst layer lb, 25 and catalyst layer 1 c moving from the upstream side to the downstream side. The first amorphous solid acid may be the same as or may differ 7 FP07-0099-00 from the second amorphous solid acid. [0024] The amorphous solid acid-containing catalyst (referred to below as the amorphous solid acid catalyst) comprising the catalyst layer la and the catalyst layer 1c exhibits a hydrocracking activity and a 5 hydroisomerization activity, but is not otherwise particularly limited. The use is preferred of catalyst containing at least one amorphous solid acid selected from silica-alumina, silica-zirconia, alumina-boria, silica titania, silica-magnesia, kaolinite, aluminophosphate, and silicoaluminophosphate as the carrier therein, while the use of catalyst 10 containing at least one amorphous solid acid selected from silica alumina, silica-zirconia, and silicoaluminophosphate is particularly preferred. [0025] The amorphous solid acid catalyst is preferably a catalyst comprising a metal from group VIA of the Periodic Table and/or a metal 15 from group VIII of the Periodic Table supported on the aforementioned carrier. The group VIA metal can be specifically exemplified by chromium, molybdenum, and tungsten. The group VIII metal can be specifically exemplified by cobalt, nickel, rhodium, palladium, iridium, and platinum. Palladium and/or platinum are preferred thereamong, 20 while platinum is more preferred. The amount of metal supported on the carrier is not particularly limited, but is preferably 0.01 to 2 mass% with respect to the carrier; when the metal supported on the carrier is palladium and/or platinum, this value is preferably 0.05 to 2 mass%. The metal present in the amorphous solid acid catalyst comprising the 25 catalyst layer la may be the same as or may differ from the metal present in the amorphous solid acid catalyst comprising the catalyst 8 FP07-0099-00 layer Ic. [0026] The amorphous solid acid catalyst may additionally contain a binder for carrier molding. The binder is not particularly limited, but alumina and silica are preferred binders. The shape of the carrier is not 5 particularly limited, and, for example, a granular shape or cylindrical shape (pellet) can be used. The binder present in the amorphous solid acid catalyst comprising the catalyst layer la may be the same as or may differ from the binder present in the amorphous solid acid catalyst comprising the catalyst layer 1 c. 10 [0027] The zeolite-containing catalyst (referred to hereafter as the zeolite-type catalyst) comprising the catalyst layer lb has a hydrocracking activity and a hydroisomerization activity, but is not otherwise particularly limited. The use is preferred of a catalyst that contains as its carrier at least one zeolite selected from USY zeolite, HY 15 zeolite, mordenite, -zeolite, and Q-zeolite, while the use of USY zeolite-containing catalyst is particularly preferred thereamong. The proportion of the USY zeolite in the carrier is not particularly limited in those cases where the carrier of the zeolite-type catalyst comprises USY zeolite; however, viewed from the perspective of preventing a 20 lightening of the cracking product, the proportion of USY zeolite is preferably no more than 15 mass% and more preferably no more than 5 mass%, in each case with reference to the carrier as a whole. [0028] The silica/alumina molar ratio in the USY zeolite is not particularly limited, but is preferably 20 to 200, more preferably 25 to 25 100, and most preferably 30 to 60. The average particle size of the USY zeolite is preferably no larger than 1.0 jim and more preferably is no 9 FP07-0099-00 larger than 0.5 pm. The obtained cracking product tends to become lighter when the average particle size of the USY zeolite exceeds 1.0 Pm. [0029] The zeolite-type catalyst is preferably a catalyst in which a metal 5 from group VIA of the Periodic Table and/or a metal from group VIII is supported on the aforementioned carrier. The group VIA metal can be specifically exemplified by chromium, molybdenum, and tungsten. The group VIII metal can be specifically exemplified by cobalt, nickel, rhodium, palladium, iridium, and platinum. Palladium and/or platinum 10 are preferred thereamong, while platinum is more preferred. The amount of metal supported on the carrier is not particularly limited, but is preferably 0.01 to 2 mass% with respect to the carrier; when the metal supported on the carrier is palladium and/or platinum, this value is preferably 0.05 to 2 mass%. 15 [0030] The zeolite-type catalyst may additionally contain a binder for carrier molding. The binder is not particularly limited, but alumina and silica are preferred binders. The shape of the carrier is not particularly limited, and, for example, a granular shape or cylindrical shape (pellet) can be used. 20 [0031] There are no particular limitations on the ratio between the fill amounts (volume) of the first and second amorphous solid acid catalysts and the fill amount (volume) of the zeolite-type catalyst in the catalytic reaction region 1. However, letting the fill amount of the zeolite-type catalyst comprising the catalyst layer lb be 1 volume part, the fill 25 amount of the first amorphous solid acid catalyst comprising the catalyst layer la is preferably 0.5 to 3 volume parts. There is a tendency for the 10 FP07-0099-00 middle distillate yield to decline when the fill amount of the first amorphous solid acid catalyst is outside the range of 0.5 to 3 volume parts rather than within this range. [0032] Letting the fill amount of the zeolite-type catalyst comprising 5 the catalyst layer lb be 1 volume part, the fill amount of the third amorphous solid acid catalyst comprising the catalyst layer ic is preferably 0.5 to 2.0 volume parts. While the middle distillate yield increases when the fill amount of the third amorphous solid acid catalyst is less than 0.5, the low-temperature fluidity of the middle distillate also 10 tends to become unsatisfactory. On the other hand, while the low temperature fluidity of the middle distillate improves when the fill amount of the third amorphous solid acid catalyst is above 2 volume parts, the middle distillate yield tends to decline. [0033] The wax introduced into the reaction column 10 via the 15 hydrogen feed line Li can be exemplified by petroleum-based or synthetic wax that contains at least 30 mass% C 15 -oa and preferably C 2 0 . 60 normal-paraffin. The petroleum-based wax can be exemplified by slack wax and microwax, while the synthetic wax can be exemplified by so-called FT wax, i.e., wax produced by the FT synthesis. FT wax is 20 particularly well suited for use as the wax from the perspective of the ameliorated environmental burden. [0034] The hydrocracking process conditions in the reaction column 10 are not particularly limited; however, the reaction temperature is preferably 250 to 370'C and more preferably is 280 to 330'C. There is a 25 tendency for hydrocracking to fail to progress adequately when the reaction temperature is below 250'C. On the other hand, the middle 11 FP07-0099-00 distillate yield from hydrocracking declines and the cracking product tends to discolor when the reaction temperature exceeds 370'C. [0035] The liquid hourly space velocity in the reaction column 10 is preferably 0.1 to 10.0 h~' and more preferably is 0.2 to 3.0 h~1. The 5 middle distillate yield tends to decline when the liquid hourly space velocity is less than 0.1 h-'. There is a tendency for hydrocracking to fail to progress adequately when the liquid hourly space velocity exceeds 10.0 h-1. [0036] The reaction pressure in the reaction column 10 is not 10 particularly limited; however, the hydrogen partial pressure is preferably 0.5 to 10.0 MPa and more preferably is 2.0 to 7.0 MPa. The hydrogen/oil ratio in the reaction column 10 is preferably 150 to 1200 NL/L and more preferably is 200 to 700 NL/L. [0037] The cracking product transported by the line L3 contains 15 naphtha (fraction with a boiling point below 145'C), middle distillate (fraction with a boiling point from 145 to 360'C), and a lubricating oil fraction (fraction with a boiling point above 360'C). Base stocks for various applications can be obtained by fractional distillation of these fractions. 20 [0038] Based on a consideration of the low-temperature starting characteristics and low-temperature operating characteristics, the middle distillate used as a liquid fuel base stock preferably has a low pour point. As a particular matter, the pour point of the gas oil fraction (fraction with a boiling point from 260 to 360'C) is preferably equal to or below 25 -10 C, more preferably equal to or below -15'C, even more preferably equal to or below -20'C, and even more preferably equal to or below 12 FP07-0099-00 251C. Here, the pour point denotes the pour point measured in accordance with JIS K 2269-1987, "Test methods for the pour point of crude oil and petroleum products and the cloud point of petroleum products". 5 [0039] When the lubricating oil fraction obtained from the cracking product by fractional distillation does not have an adequately low pour point, dewaxing can be carried out in order to obtain a lubricating base oil having a desired pour point. This dewaxing can be carried out by the usual methods, e.g., solvent dewaxing and catalytic dewaxing. Solvent 10 dewaxing generally uses a mixed solvent of MIEK and toluene, but solvents such as benzene, acetone, and MIBK may also be used. Solvent dewaxing is preferably carried out under the following conditions: solvent/oil ratio = 1- to 6-fold, filtration temperature = -5 to -45'C and preferably -10 to -40'C. The wax fraction removed here can be 15 reintroduced into the reaction column 10 as slack wax. Examples [0040] The present invention is more specifically described hereinbelow based on examples and comparative examples; however, the present invention is in no way limited by the examples that follow. 20 [0041] < Preparation of amorphous solid acid catalysts > (Catalyst A- 1) 40 mass parts boehmite (alumina) was added as binder to 60 mass parts amorphous silica-alumina that had an alumina content of 14 mass%, a pore volume of 0.68 mL/g, and an average particle size of 5 25 pm. The amorphous silica-aluminalboehmite mixture was thoroughly mixed and kneaded and was then molded into a cylindrical carrier with 13 FP07-0099-00 a diameter of 1.6 mm and a length of approximately 2 mm. This was calcined (calcination temperature: 500'C, holding time: 3 hours) to obtain an amorphous solid acid. This amorphous solid acid was impregnated with an aqueous solution of dichlorotetraammine 5 platinum(II) so as to support 0.5 mass% platinum with respect to the amorphous solid acid. This was dried and calcined (calcination temperature: 500'C, holding time: 1 hour) to give catalyst A-1. [0042] (Catalyst A-2) 50 mass parts boehmite was added as binder to 50 mass parts 10 aluminophosphate (SAPO- 11) comprising a 41 mass% alumina content, 56 mass% phosphorus pentoxide, and 3 mass% silica. The aluminophosphate/boehmite mixture was thoroughly mixed and kneaded and was then molded into a cylindrical shape with a diameter of 1.6 mm and a length of approximately 2 mm. This was calcined 15 (calcination temperature: 500'C, holding time: 3 hours) to obtain an amorphous solid acid. This amorphous solid acid was impregnated with an aqueous solution of dichlorotetraammine platinum(II) so as to support 0.5 mass% platinum with respect to the amorphous solid acid. This was dried and calcined (calcination temperature: 500'C, holding 20 time: 1 hour) to give catalyst A-2. [0043] < Preparation of a zeolite-type catalyst > (Catalyst Z-1) 97 mass parts boehmite was added as binder to 3 mass parts USY zeolite that had a silica/alumina molar ratio of 38 and an average 25 particle size of 0.8 pm. The USY zeolite/boehmite mixture was thoroughly mixed and kneaded and was then molded into a cylindrical 14.

FP07-0099-00 shape with a diameter of 1.6 mm and a length of approximately 2 mm. This was calcined (calcination temperature: 500'C, holding time: 3 hours) to obtain a zeolite-containing carrier. This carrier was impregnated with an aqueous solution of dichlorotetraammine 5 platinum(II) so as to support 0.6 mass% platinum with respect to the carrier. This was dried and calcined (calcination temperature: 500 0 C, holding time: 1 hour) to give catalyst Z-1. [0044] (Example 1) < Wax hydrocracking > 10 100 mL of catalyst A-I was then filled as catalyst layer la into the fixed bed reactor shown in Figure 1; 100 mL of catalyst Z-1 was filled as catalyst layer lb; 100 mL of catalyst A-1 was filled as catalyst layer 1c; and wax hydrocracking was carried out. Prior to the execution of wax hydrocracking, each of the catalysts was subjected to a reducing 15 treatment by holding the catalytic reaction region 1 at 340'C for 2 hours under hydrogen. [0045] The wax feedstock was FT wax with a boiling point above 360'C; this wax feedstock was fed at a rate of 200 mL/h from the top of the reaction column 10. Hydrogen was fed from the top of the column at 20 a hydrogen/oil ratio of 590 NL/L with respect to the wax feedstock. The pressure in the reaction column 10 was adjusted with a backpressure valve so as to provide a constant inlet pressure of 4 MPa. The hydrocracking temperature in the reaction column 10 was 312'C upon adjustment so as to provide a wax cracking rate of 80 mass%. Here, the 25 wax cracking rate refers to the cracking rate defined by formula (1) below. In formula (1) below, the "total mass of the cracking product" is 15 FP07-0099-00 the sum of the product oil and product gas yielded by the hydrocracking, while the "mass of the fraction with a boiling point less than 360'C" is the mass of the fraction with a boiling point less than 360*C present in the cracking product. mass of the fraction with a 5 cracking rate (mass%) boiling point below 360C total mass of the cracking product [0046] The resulting cracking product was subjected to atmospheric fractional distillation into a kerosene fraction (fraction with a boiling point of 145 to 260'C), a gas oil fraction (fraction with a boiling point of 260 to 360'C), and a lubricating oil fraction (fraction with a boiling 10 point above 360'C) and the yield of each fraction with reference to the mass of the wax feedstock was determined. The following are shown in Table 1: the yield of the middle distillate (fraction with a boiling point of 145 to 360 0 C), obtained by adding the kerosene fraction yield and the gas oil fraction yield, and the pour point of the gas oil fraction as 15 measured in accordance with JIS K 2269-1987. [0047] A lubricating oil base stock was produced by subjecting the lubricating oil fraction to solvent dewaxing. This was carried out using a mixed solvent of methyl ethyl ketone-toluene as the solvent, a solvent/oil ratio of 4-fold, and a filtration temperature of -20'C. The 20 lubricating oil base yield with reference to the mass of the wax feedstock is shown in Table 1. [0048] (Example 2) Wax hydrocracking, solvent dewaxing, and the various measurements were carried out as in Example 1, but in this example 16 FP07-0099-00 filling 100 mL of catalyst A-2 rather than catalyst A-I as the catalyst layer 1 c. The hydrocracking temperature in the reaction column 10 was 31 0 0 C upon adjustment so as to provide a wax cracking rate of 80 mass%. The measurement results are shown in Table 1. 5 [0049] (Comparative Example 1) Wax hydrocracking, solvent dewaxing, and the various measurements were carried out as in Example 1, except that 100 mL of catalyst Z-1 was filled as catalyst layer lb and catalyst layer la and catalyst layer 1 c were not installed. The hydrocracking temperature in 10 the reaction column 10 was 317 0 C upon adjustment so as to provide a wax cracking rate of 80 mass%. The measurement results are shown in Table 1. [0050] (Comparative Example 2) Wax hydrocracking, solvent dewaxing, and the various 15 measurements were carried out as in Example 1, except that 100 mL of catalyst A-i was filled as catalyst layer la, 100 mL of catalyst Z-1 was filled as catalyst layer 1b, and catalyst layer Ic was not installed. The hydrocracking temperature in the reaction column 10 was 314'C upon adjustment so as to provide a wax cracking rate of 80 mass%. The 20 measurement results are shown in Table 1. [0051] (Comparative Example 3) Wax hydrocracking, solvent dewaxing, and the various measurements were carried out as in Example 1, except that 100 mL of catalyst Z- 1 was filled as catalyst layer I b, 100 mL of catalyst A-I was 25 filled as catalyst layer le, and catalyst layer la was not installed. The hydrocracking temperature in the reaction column 10 was 315'C upon 17 FP07-0099-00 adjustment so as to provide a wax cracking rate of 80 mass%. The measurement results are shown in Table 1. [Table 1] Comp. Comp. Comp. Ex.1 Ex.2 Ex.1 Ex.2 Ex.3 catalyst layer la A-1 A-1 - A-1 catalyst catalyst layer lb Z-1 Z-1 Z-1 Z-1 Z-1 catalyst layer 1c A-1 A-2 - - A-2 Yield of middle distillate 60.5 60.8 54.7 60.1 54.4 (mass%) Pour point of gas oil fraction -25.0 -27.5 -17.5 -17.5 -22.5 (OC) I___ I_ _I Yield of lubricating oil base 15.7 16.6 11.6 11.8 14.2 stock (mass%) [0052] The preceding results show that, by carrying out hydrocracking 5 in a catalytic reaction region having a trilayer structure in which an amorphous solid acid catalyst, zeolite-type catalyst, and amorphous solid acid catalyst are disposed in the sequence given, both a high middle distillate yield and a high lubricating oil base stock yield can be achieved and a gas oil fraction that exhibits an excellent low 10 temperature fluidity can be obtained at the same time. Industrial Applicability [0053] The present invention provides a method for wax hydrocracking that can achieve both a high middle distillate yield and a high lubricating oil base stock yield and at the same time that can produce a 15 gas oil fraction that exhibits an excellent low-temperature fluidity. i8 C:\NRPonbI\DCC\WA K(M\)3(_I DOC-16A9/2111 - 18A [0054] 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. [0055] Throughout this specification and the claims which follow, 5 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 step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

Claims

1. A method for hydrocracking a wax in a fixed bed reactor, the fixed bed reactor comprising a catalytic reaction region in which there is 5 disposed in this order a first catalyst layer containing a first amorphous solid acid, a second catalyst layer containing a zeolite, and a third catalyst layer containing a second amorphous solid acid wherein the wax is caused to flow from the first catalyst layer toward the third catalyst layer in the catalytic reaction region in the presence of hydrogen. 10

2. The wax hydrocracking method according to claim 1, characterized in that the second catalyst layer contains USY zeolite.

3. The wax hydrocracking method according to claim 1 or 2, 15 characterized in that the first catalyst layer and the third catalyst layer each contains at least one type selected from silica-alumina, silica zirconia, and silicoaluminophosphate.

4. The wax hydrocracking method according to any one of claims 20 1 to 3, characterized in that the first catalyst layer contains at least one metal selected from platinum and palladium supported on the first amorphous solid acid; the third catalyst layer contains at least one metal selected from platinum and palladium supported on the second amorphous solid acid; and the second catalyst layer contains at least one 25 metal selected from platinum and palladium supported on the zeolite.

5. The wax hydrocracking method according to any one of claims 1 to 4, characterized in that the wax is obtained by Fischer-Tropsch synthesis.