A method for producing naphthenic rubber filler oil by hydrogenation

Abstract

The invention discloses a method for producing cycloalkyl rubber filler oil by hydrogenation. Cycloalkyl vacuum distillate oil is used as a raw material, and a hydrogenation treatment reaction is first performed; the effluent of the hydrogenation treatment reaction is subjected to high-pressure stripping to remove impurities such as H2S and NH3 that affect the precious metal catalyst, and then enters the isomerization decondensation-deep supplementary refining reaction zone to improve the low-temperature fluidity and stability of the oil product. The method of the invention can obtain high-quality cycloalkyl rubber filler oil products, and at the same time produce high-quality special oil products as by-products, and greatly reduces the energy consumption caused by the two-stage method of boosting-depressurization-boosting, heating-cooling-heating, and the process is simple and occupies less space.

Description

Technical Field

[0001] The present invention relates to a method for producing naphthenic rubber extension oil by hydrogenation, specifically a method for producing naphthenic special oil products by using naphthenic vacuum distillate oil as raw material through a two-stage process of hydrogenation treatment-high pressure hydrogen stripping / isomerization dewaxing-supplementary refining. Background Art

[0002] Cycloalkane crude oil has the characteristics of high density, high viscosity, low wax content, high aromatic and cycloalkane content, and low pour point. It is often used as a raw material to produce low-condensation lubricant base oil that does not require viscosity-temperature performance, such as transformer oil, refrigeration oil, rubber filler oil, etc. The traditional production of lubricant base oil adopts solvent technology. The two main steps are solvent refining to remove non-ideal components such as aromatics, and solvent dewaxing to ensure the low-temperature flow properties of the base oil. Nowadays, the technology of hydrogenation for producing lubricating oil is developing rapidly. The hydrogenation method refers to the process method of producing lubricating base oil by hydrogenation treatment or hydrocracking-hydrogenation decondensation or isodewaxing-hydrogenation refining combined process. The hydrogenation method has the advantages of high product quality, no environmental problems, and high base oil yield, and gradually replaces the traditional solvent process.

[0003] In the prior art, a variety of hydrogenation processes can be used to produce cycloalkyl lubricating base oils. CN1990833A discloses a method for producing transformer oil using cycloalkyl oil as raw material through a two-stage process of hydrogenation treatment-hydrogenation refining. This method does not improve the pour point and requires the selection of suitable raw materials to obtain the ideal product. CN1676585A reports a method for producing lubricating base oil by hydrogenation treatment-hydrogenation decondensation-supplementary refining. The hydrogenation product of this method must be subjected to gas-liquid separation before the liquid product can enter the hydrodecondensation process. CN161376838A introduces a method for producing lubricating base oil by a two-stage hydrogenation process of hydrogenation treatment-hydrogenation decondensation-supplementary refining. In this method, the hydrogenation product does not need to be separated and directly enters the hydrodecondensation and supplementary refining reaction zone.

[0004] Shell has announced a method of using high-pressure steam stripping to directly remove H2S and NH3 from hydrotreated products, which then enters precious metal hydrodewaxing and supplementary refining reactors to produce cyclopentane rubber filler oil. The method has three industrial applications in China, but since the cold high-fraction oil containing H2S and NH3 without deep dearomatization is directly incorporated into the distillation system, all products have poor color and stability. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present invention provides a method for producing naphthenic rubber filler oil by hydrogenation. Specifically, the method uses naphthenic vacuum distillate oil as raw material and produces naphthenic special oil products by a two-stage process of hydrogenation treatment-high-pressure hydrogen stripping / isomerization dewaxing-supplementary refining.

[0006] A method for producing cycloalkyl rubber filler oil by hydrogenation of the present invention comprises the following contents:

[0007] (1) The cycloalkyl vacuum distillate oil is mixed with hydrogen and then enters a hydroprocessing reactor, and sequentially contacts with a hydrorefining catalyst and a hydro-modifying catalyst to perform a hydro-modifying reaction; the hydro-modifying catalyst contains amorphous silica-alumina and a modified Y molecular sieve;

[0008] (2) The hydrotreatment effluent obtained in step (1) enters a high-pressure stripping tower from the top, and hydrogen is injected into the bottom of the tower as a stripping medium; after stripping, a tower bottom oil from which H2S and NH3 are removed and a tower top effluent containing H2S, NH3, hydrogen and part of light oil are obtained;

[0009] (3) The top effluent obtained in step (2) containing H2S, NH3, hydrogen and part of the light oil enters a cold high-pressure separator after heat exchange, and the cold high-fraction oil enters a cold low-fraction oil, and the cold low-fraction oil enters a H2S removal stripping tower to remove H2S and NH3, and is divided into two streams after pressure increase and heat exchange: one enters an isomerization dewaxing reactor, and the other enters a supplementary refining reactor;

[0010] (4) The high-pressure stripping tower bottom oil obtained in step (2) is mixed with hydrogen and then passed through an isomerization dewaxing reactor and a supplementary refining reactor in sequence together with the cold low-fraction oil from which H2S and NH3 have been removed, to perform isomerization dewaxing reaction and deep dearomatization reaction, thereby reducing the product freezing point and improving stability;

[0011] (5) The reaction effluent of step (4) enters the separation system to obtain cycloalkane specialty oil products with good stability and a series of light white oils that meet the technical index requirements of light white oil (II) in NB / SH / T 0913-2015.

[0012] Furthermore, the high-pressure stripping tower of step (2) includes a filler, and the selection of the filler is common knowledge of those skilled in the art. For example, the filler can be a rolled hole θ ring filler. Preferably, a ZnO bed is also provided at the lower part of the filler zone, and the ZnO bed can be used to remove a small amount of H2S that is not stripped cleanly due to operation fluctuations. The operating conditions of the high-pressure stripping tower are well known to those skilled in the art. For example, the stripping conditions include: a stripping temperature of 150 to 400°C, preferably the outlet temperature of the hydrotreating reaction zone, a stripping pressure that is the same as the pressure of the hydrotreating reaction zone, and a hydrogen consumption that is higher than the chemical hydrogen consumption of the hydrotreating reaction (hydrotreating and upgrading), preferably equivalent to the sum of the chemical hydrogen consumption of the hydrotreating reaction and the dissolved hydrogen of the hydrotreating system.

[0013] Furthermore, the cold high-fraction gas phase obtained in step (3) can be re-entered into the hydroprocessing reactor as circulating hydrogen after selective H2S removal.

[0014] Furthermore, the naphthenic distillate oil can be at least one of naphthenic distillate oil, coal tar hydrocracking tail oil or catalytic cracking diesel fraction. The aromatic content of the naphthenic distillate is generally 30 to 99 wt%, and the density at 20°C is generally 0.923 to 0.955 g / cm 3 The distillation range of the cycloalkane distillate oil raw material is any range formed by any two values ​​within the range of 140 to 600°C; preferably, the initial distillation point of the cycloalkane distillate oil is 140 to 350°C, and the final distillation point is 400 to 600°C.

[0015] Furthermore, the hydrorefining catalyst described in step (1) is a conventional hydrorefining catalyst in the art, such as a diesel hydrorefining catalyst or a hydrocracking pretreatment catalyst. The hydrorefining catalyst generally has Group VIB and / or Group VIII metals as active components and alumina or silicon-containing alumina as a carrier. The Group VIB metal is generally Mo and / or W, and the Group VIII metal is generally Co and / or Ni. Based on the weight of the catalyst, the Group VIB metal content is 10wt% to 50wt% in terms of oxide, and the Group VIII metal content is 3 to 15wt% in terms of oxide. The physical properties of the catalyst are as follows: the specific surface area is 100 to 350m 2 / g, pore volume is 0.15~0.6mL / g. Commercial catalysts that can be selected include 3936, 3996, FF-16, FF-26, FF-36, FF-46, FF-56, FF-66 and other hydrofining catalysts developed by Fushun Petrochemical Research Institute of Sinopec. It can also be a catalyst with similar functions developed by foreign catalyst companies, such as UOP's HC-K, HC-P catalysts, Topsoe's TK-555, TK-565 catalysts, and AKZO's KF-847, KF-848, etc.

[0016] Furthermore, the hydro-modification catalyst contains amorphous silica-alumina and modified Y molecular sieve. Based on the weight of the catalyst, the hydro-modification catalyst contains 20wt% to 60wt% amorphous silica-alumina, 5wt% to 25wt% modified Y zeolite, 10wt% to 30wt% of Group VIB metals in terms of oxides, and 4wt% to 15wt% of Group VIII metals in terms of oxides. The specific surface area of ​​the hydro-modification catalyst is generally 220 to 300m 2 / g, pore volume is 0.3-0.6mL / g, pore volume with pore diameter of 3-10nm accounts for 75%-95% of the total pore volume, preferably 85%-95%, infrared acidity is 0.30-0.5mmol / g. The properties of the amorphous silica-alumina used are as follows: containing 10wt%-60wt% of silicon oxide, specific surface area of ​​400-650m 2 / g, pore volume of 1.0-1.8mL / g, infrared acidity of 0.34-0.50mmol / g, pore volume of pores with a pore diameter of 4-10nm accounts for 85%-95% of the total pore volume, and pore volume of >15nm accounts for less than 5% of the total pore volume; the preferred properties are as follows: containing 10wt%-35wt% of silicon oxide, specific surface area of ​​530-650m 2 / g, pore volume is 1.2-1.5mL / g. The modified Y zeolite has the following properties: SiO2 / Al2O3 molar ratio is 40-60, unit cell constant is 2.425-2.440nm, relative crystallinity is 80-100%, infrared acidity is 0.1-0.5mmol / g, among which medium-strong acid at 250-550℃ is concentrated, accounting for 60-70% of the total acid, and specific surface area is 600-900m 2 / g, pore volume 0.3~0.6mL / g, of which the pore volume of secondary mesopores of 4~15nm accounts for 40%~50% of the total pore volume. The hydrogenation reforming catalyst may also contain one or more of the components such as alumina, zirconium oxide, titanium oxide, etc.

[0017] Furthermore, the isomerization dewaxing catalyst used in the isomerization dewaxing reactor can select the lubricating oil hydroisomerization catalyst commonly used in the art. Commercial hydroisomerization catalysts can be used, or they can be prepared according to general knowledge in the art. The hydroisomerization catalyst carrier is generally alumina and TON structure molecular sieve. The TON structure molecular sieve is selected from at least one of NU-10 molecular sieve, ZSM-22 molecular sieve, ZSM-23 molecular sieve, ZSM-48 molecular sieve, etc., preferably ZSM-22 molecular sieve. The content of TON structure molecular sieve in the catalyst is 30wt%~80wt%, preferably 40wt%~70wt%, and part of silicon oxide can also be added to the carrier; the active metal component is one or more of Pt, Pd, Ru and Rh, and the content in the catalyst is 0.1wt%~5.0wt%; the optional auxiliary component is one or more of boron, fluorine, chlorine and phosphorus, and the content in the catalyst is 0.1wt%~5.0wt%. The specific surface area of ​​the hydroisomerization catalyst is 150~500m 2 / g, and the pore volume is 0.15~0.60ml / g.

[0018] Furthermore, the supplementary refining catalyst used in the supplementary refining reactor is a conventional reduced hydrorefining catalyst. Its active metal is one or two of Pt and Pd, or metallic nickel. The weight content of active metal in the precious metal catalyst is generally 0.05% to 1%; the weight content of nickel in terms of oxide is 30% to 80%; the catalyst carrier is generally Al2O3 or Al2O3-SiO2, and may also contain one or more of P, Ti, B, Zr, etc. as an auxiliary agent. The catalyst needs to be conventionally reduced before use to ensure that the hydrogenation active metal is in a reduced state during the reaction. Ordinary commercial catalysts in this field can be selected, or prepared according to ordinary methods in this field.

[0019] Furthermore, the operating conditions of the hydroprocessing reactor are: hydrogen partial pressure 5.0-18.0 MPa, preferably 10.0-16.0 MPa; reaction temperature 230-430°C, preferably 350-410°C; hydrogen-to-oil volume ratio 200-1500, preferably 600:1-1000:1; volume space velocity 0.1-10.0 h -1 , preferably 0.3 h -1 ~0.5h -1 The loading ratio of the hydrotreating catalyst to the hydrorefining catalyst in the hydrotreating reaction zone is generally 1:9~9:1, preferably 4:6~6:4.

[0020] Further, the reaction conditions of the isomerization dewaxing reactor are: reaction temperature is 300°C to 380°C, preferably 310°C to 340°C, hydrogen partial pressure is 2.0MPa to 18.0MPa, preferably 10.0 to 15.0MPa, and the raw oil liquid volume space velocity is 0.2h -1 ~6.0h -1 , preferably 0.4 h -1 ~1.0h -1 , the volume ratio of hydrogen to oil is 400:1 to 1500:1, preferably 600:1 to 800:1.

[0021] Furthermore, the reaction conditions of the supplementary refining reactor are: reaction temperature is 200°C to 300°C, preferably 210°C to 280°C, hydrogen partial pressure is 6.0MPa to 18.0MPa, preferably 10.0 to 15.0MPa, volume space velocity is 0.2h -1 ~3.0h -1 , preferably 0.3h -1 ~0.6h -1 , the volume ratio of hydrogen to oil is 400:1 to 1500:1, preferably 600:1 to 800:1.

[0022] Furthermore, the cycloalkyl special oil product obtained in step (5) includes one or more of transformer oil, refrigeration oil and a series of rubber filler oils.

[0023] Compared with the prior art, the method of the present invention has the following beneficial effects:

[0024] 1. The two-stage hydrogenation process of high-pressure hydrogen stripping, hydrogenation treatment - isomerization decondensation - deep supplementary refining, avoids the design of two sets of fractionation systems required to avoid the influence of H2S and NH3 on precious metal catalysts in the traditional two-stage hydrogenation process; at the same time, most of the reaction feed (>85w%) in the hydrogenation process of the present invention is a one-time pressure-raising process, which avoids the process of pressure-raising-pressure-reducing-re-pressurizing of all raw oil between the two reaction zones of the traditional two-stage process device, saving electricity consumption; the stripping hydrogen injected at the bottom of the high-pressure stripping tower enters the circulating hydrogen system of the hydroprocessing device as part of the supplementary hydrogen. By adjusting the operating temperature of the high-pressure stripping tower, the bottom effluent of the stripping tower can directly enter the isomerization dewaxing reactor without the need to set up an isomerization dewaxing feed heating furnace, and also avoids the energy loss in the process of heating, cooling and reheating of all reaction products in the traditional two-stage process, saving electricity consumption and fuel gas consumption, while saving land.

[0025] 2. The effluent from the top of the high-pressure stripping tower enters the cold high-pressure separator after heat exchange. After separating the gas phase circulating hydrogen, the cold high-fraction oil containing H2S and NH3 is depressurized and enters the cold low-pressure separator to obtain the cold low-fraction oil, which enters the conventional H2S removal stripping tower to remove H2S and NH3. The liquid is divided into two streams after heat exchange, one enters the isomerization dewaxing reactor, and the other enters the supplementary refining reactor. This not only solves the problem of Shell process cold high-fraction oil directly entering the fractionation system to affect the product color and stability, but also solves the problem of the by-product light white oil pour point being greatly excessive when the heavy rubber filler oil pour point is qualified by flexibly adjusting the ratio of the two streams, thereby improving the total liquid yield and the target product yield. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a process flow diagram of the method of the present invention. DETAILED DESCRIPTION

[0027] The method of the present invention is described in more detail below with reference to the accompanying drawings and specific embodiments.

[0028] Combination Figure 1The method for producing cyclopentane rubber filling oil by hydrogenation of the present invention is as follows: the cyclopentane vacuum distillate oil passes through pipeline 1, is mixed with the circulating hydrogen of pipeline 2, and first enters the hydroprocessing reaction zone 3 to carry out desulfurization, denitrogenation, deoxygenation and aromatic saturation reaction; then the hydroprocessing product 4 enters the high-pressure hydrogen stripping tower 5, and the stripping hydrogen 6 is blown into the bottom of the tower to obtain the tower bottom oil 7 from which H2S and NH3 are removed, and the top of the high-pressure stripping tower enters the separation system 8 of the hydroprocessing section, and the separation system 8 generally includes a high-pressure separator and a low-pressure separator; the separated gas phase is returned to the hydroprocessing reaction system through pipeline 2 as the circulating hydrogen, and the liquid phase product enters the H2S removal stripping tower 10 through pipeline 9, and the tower bottom oil 11 from which H2S and NH3 are removed is pressurized and heat exchanged, and then separated according to a certain proportion. The two streams 13 and 14 are respectively fed into an isomerization dewaxing reactor 15 and a supplementary refining reactor 17; the high-pressure stripping tower bottom oil 7 is mixed with the stream 13 and the new hydrogen 12 and directly fed into the isomerization dewaxing reactor 15 for isomerization decondensation reaction; the isomerization dewaxing product 16 is mixed with the stream 14 and fed into the supplementary refining reactor 17 for deep dearomatization reaction to improve the light and heat stability of the product; the supplementary refining reaction product 18 enters a separation system 19, which generally includes a high-pressure separator and a low-pressure separator; the low-pressure oil enters a fractionation system 20, which includes a normal-pressure fractionation tower and a vacuum fractionation tower to obtain light naphtha 21, light white oil 22 and cycloalkyl products 23 (including transformer oil, refrigeration oil and a series of cycloalkyl rubber filler oils).

[0029] The specific contents and effects of the method of the present invention are described below by means of specific embodiments.

[0030] The following examples will further illustrate the method provided by the present invention, but the scope of the present invention is not limited thereby. The properties of the raw materials treated by the present invention are shown in Table 1, and the physical and chemical properties of the catalyst used are shown in Table 2.

[0031] Table 1 Raw material properties

[0032]

[0033] Table 2 Catalyst

[0034]

[0035] Example 1

[0036] Raw material 1 is the naphthenic base oil listed in Table 1, and the catalyst physicochemical properties are shown in Table 2. The hydroprocessing zone is filled with a series of hydroprotective agents, hydrofining catalysts and hydromodification catalysts, wherein the series of hydroprotective agents: hydrofining catalysts: hydromodification catalysts = 1:5.5:3.5 (volume). See the principle flow chart Figure 1 The results are shown in Tables 3 and 4.

[0037] Example 2

[0038] The raw materials are the cycloalkyl oil listed in Table 1, and the same catalyst as in Example 1 is used. Figure 1 The results are shown in Tables 3 and 4.

[0039] Comparative Example 1

[0040] Comparative Example 1 adopts the traditional two-stage hydrogenation process. The process flow is as follows: the hydroprocessed product first enters the hot high-pressure separator, and then enters the cold high-pressure separator after gas phase heat exchange. The cold high-fraction gas phase enters the circulating hydrogen system, and the cold high-fraction oil enters the cold low-fraction after decompression, and the top of the separator is the low-fraction gas; the hot high-fraction oil enters the hot low-fraction after decompression, and the top is the low-fraction gas; the hot low-fraction oil (most of the product) and the cold low-fraction oil are mixed and then all enter the dehydrogen sulfide stripping tower (pressure is about 1MPa), and a small amount of hydrogen sulfide gasoline is discharged from the top of the tower and all liquids (sulfur content <10µg.g -1 , nitrogen content <2µg.g -1 ) After heating and pressure increase, it enters the second stage isomerization dewaxing-supplementary refining stage; the supplementary refined product is subjected to gas-liquid separation and fractionation to obtain various products.

[0041] Comparative Example 1 uses the same raw materials and the same catalyst as in Example 1. The process conditions and test results are shown in Table 3-4.

[0042] Comparative Example 2

[0043] Comparative Example 2 adopts the Shell process ("Research on the Application of High-Pressure Hydrogen Stripping in the Production Process of Fully Hydrogenated Lubricant Oil", Xue Nan, "Petroleum Refining and Chemical Industry", October 2019).

[0044] Comparative Example 2 uses the same raw materials and catalyst as in Example 1. The process is that the hydrotreated product directly enters the isomerization dewaxing-supplementary refining section after high-pressure stripping, the hot high-fraction gas phase enters the cold low-pressure separator, the cold low-fraction gas is returned to the reaction system as circulating hydrogen, and the cold low-fraction oil directly enters the subsequent fractionation system for fractionation to obtain various products. The results are shown in Tables 3-4.

[0045] Table 3 Process conditions

[0046]

[0047] *, for fresh ingredients.

[0048] Table 4 Test results

[0049]

[0050] **, for fresh feed.

[0051] From the data in Table 3-4, it can be seen that the use of cycloalkane vacuum distillate as raw material, the use of hydrotreatment - high-pressure hydrogen stripping / isomerization dewaxing - supplementary refining two-stage process can produce products of equivalent quality to the conventional hydrotreatment / isomerization dewaxing - supplementary refining two-stage process, while avoiding the energy consumption of all feed pressure boosting - pressure reduction - pressure boosting, temperature rise - temperature drop - temperature rise in the conventional two-stage process, reducing the footprint of the device, and reducing the energy consumption of the device by about 11%. In addition, since the cold high-fraction oil is subjected to conventional stripping and enters the isomerization dewaxing reactor and supplementary refining reactor respectively according to the optimized ratio, the light oil loss at the top of the conventional two-stage distillation process H2S stripping tower is greatly reduced, and the total liquid recovery and target product yield are improved. While the Shell process flow has lower energy consumption, the aromatics in the cold low-fraction oil are directly fed into the fractionation system without hydrogenation supplementary refining, resulting in the light and thermal stability of the entire line of products failing to meet the standards.

Claims

1. A method for producing cyclopentane rubber filler oil by hydrogenation, comprising the following contents: (1) The cycloalkyl vacuum distillate oil is mixed with hydrogen and enters the hydroprocessing reaction zone, and sequentially contacts with a hydrorefining catalyst and a hydro-modifying catalyst to perform a hydro-modifying reaction; the hydro-modifying catalyst contains amorphous silica-alumina and a modified Y molecular sieve; (2) The hydrotreatment effluent obtained in step (1) enters a high-pressure stripping tower from the top, and hydrogen is injected into the bottom of the tower as a stripping medium; after stripping, a tower bottom oil from which H2S and NH3 are removed and a tower top effluent containing H2S, NH3, hydrogen and part of light oil are obtained; (3) The top effluent obtained in step (2) containing H2S, NH3, hydrogen and part of the light oil enters a cold high-pressure separator after heat exchange, and the cold high-fraction oil enters a cold low-fraction oil, and the cold low-fraction oil enters a H2S removal stripping tower to remove H2S and NH3, and is divided into two streams after pressure increase and heat exchange: one enters an isomerization dewaxing reactor, and the other enters a supplementary refining reactor; (4) The high-pressure stripping tower bottom oil obtained in step (2) is mixed with hydrogen and then passed through an isomerization dewaxing reactor and a supplementary refining reactor in sequence together with the cold low-fraction oil from which H2S and NH3 have been removed, to perform an isomerization dewaxing reaction and a deep dearomatization reaction; (5) The reaction effluent of step (4) enters a separation system to obtain a cycloalkyl special oil product having a pour point that meets the requirements and good stability and a series of light white oils that meet the technical index requirements of light white oil (II) in NB / SH / T 0913-2015; the cycloalkyl special oil product includes one or more of the series of rubber filler oils; in, The stripping pressure of the high-pressure stripping tower in step (2) is the same as the pressure in the hydroprocessing reaction zone, and the pressure of the hydroprocessing reactor is 5.0 to 18.0 MPa in terms of hydrogen partial pressure.

2. The method according to claim 1, characterized in that A ZnO bed is arranged at the lower part of the packing zone of the high-pressure stripping tower.

3. The method according to claim 1, characterized in that The stripping temperature of the high-pressure stripping tower is 150-400° C., and the amount of hydrogen used is higher than the chemical hydrogen consumption of the hydroprocessing reaction.

4. The method according to claim 3, characterized in that The stripping temperature of the high-pressure stripping tower is the outlet temperature of the hydroprocessing reaction zone, and the amount of hydrogen used is equivalent to the sum of the chemical hydrogen consumption of the hydroprocessing reaction and the dissolved hydrogen of the hydrofining system.

5. The method according to claim 1, characterized in that The cold high-fraction gas phase obtained in step (3) is selectively de-H2Sed and then re-enters the hydroprocessing reaction zone as circulating hydrogen.

6. The method according to claim 1, characterized in that The cycloalkane vacuum distillate oil has an aromatic content of 30 to 99 wt % and a density of 0.923 to 0.955 g / cm 3 .

7. The method according to claim 1, characterized in that The initial distillation point of the cycloalkyl vacuum distillate oil is 140-350°C, and the final distillation point is 400-600°C.

8. The method according to claim 1, characterized in that Based on the weight of the catalyst, the hydrogenation and reforming catalyst contains 20wt% to 60wt% amorphous silica-alumina, 5wt% to 25wt% modified Y molecular sieve, 10wt% to 30wt% of Group VIB metal calculated as oxide, and 4wt% to 15wt% of Group VIII metal calculated as oxide.

9. The method according to claim 8, characterized in that The specific surface area of ​​the hydrogenation catalyst is 220 to 300 m 2 / g, the pore volume is 0.3~0.6mL / g, the pore volume with pore diameter of 3-10nm accounts for 75%~95% of the total pore volume, and the infrared acidity is 0.30~0.5mmol / g.

10. The method according to claim 1, characterized in that An isodewaxing catalyst is used in the isodewaxing reactor. The isodewaxing catalyst carrier is alumina and TON structure molecular sieve, the active metal component is one or more of Pt, Pd, Ru and Rh, and the optional auxiliary component is one or more of boron, fluorine, chlorine and phosphorus.

11. The method according to claim 1, characterized in that The supplementary refining catalyst used in the supplementary refining reactor is a reduction type hydrogenation refining catalyst, the active metal is one or two of Pt and Pd, or metallic nickel, the catalyst carrier is Al2O3 or Al2O3-SiO2, and contains one or more of P, Ti, B, and Zr as an auxiliary agent.

12. The method according to claim 1, characterized in that The operating conditions of the hydroprocessing reaction zone are: reaction temperature 230-430°C, hydrogen-to-oil volume ratio 200-1500, volume space velocity 0.1-10.0h -1 .

13. The method according to claim 1, characterized in that The reaction conditions of the isomerization dewaxing reactor are: reaction temperature of 300°C to 380°C, hydrogen partial pressure of 2.0MPa to 18.0MPa, raw oil liquid volume space velocity of 0.2h -1 ~6.0h -1 , hydrogen-oil volume ratio 400:1~1500:

1.

14. The method according to claim 1, characterized in that The reaction conditions of the supplementary refining reactor are: reaction temperature of 200°C to 300°C, hydrogen partial pressure of 6.0MPa to 18.0MPa, volume space velocity of 0.2h -1 ~3.0h -1 , hydrogen-oil volume ratio 400:1~1500:

1.

15. The method according to claim 1, characterized in that The cycloalkyl specialty oil obtained in step (5) also includes transformer oil and / or refrigeration oil.

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