Hydrofining composite catalyst for preparing aviation hydraulic oil base oil and application of hydrofining composite catalyst

Abstract

The invention discloses a composite catalyst for hydrofining, and the composite catalyst is prepared from the following components in parts by weight: a PHF-102 type catalyst, a KF757 type catalyst, KF767 and gamma-Fe2O3. The invention also discloses a hydrofining method for aviation hydraulic oil base oil by using the catalyst. According to the composite catalyst disclosed by the invention, by reasonably regulating and controlling the proportion of different types of catalysts and adding gamma-Fe2O3, hydrofining of the aviation hydraulic oil base oil is successfully realized, meanwhile, a prevulcanization process of the catalyst is omitted, the service life of the composite catalyst is prolonged, and the production efficiency is effectively improved.

Description

Technical Field

[0001] The invention belongs to the field of aviation hydraulic oil, and in particular relates to a hydrorefining composite catalyst for hydrorefining aviation hydraulic oil base oil, and a base oil hydrorefining method using the composite catalyst. Background Art

[0002] The hydraulic oil required by the US MIL-PRF-5606 specification has a base oil that is a refined light diesel fraction. The biggest feature of this hydraulic oil is its good low temperature performance, with a viscosity of no more than 2500mm at -54°C. 2 / s. Therefore, hydraulic oil of MIL-PRF-5606 specification is widely used in automatic control equipment, load gears, shock absorbers, brakes, flap control systems of aircraft hydraulic systems, hydraulic servo systems of missiles, and other hydraulic systems using synthetic sealing materials. However, MIL-PRF-5606 hydraulic oil has a fatal weakness: strong flammability. The flash point of this hydraulic oil is slightly higher than 92℃. It is not only easy to catch fire, but also has a high flame propagation speed. Once the hydraulic system catches fire, it will pose a great threat to the safety of the aircraft and its personnel, which brings serious safety problems to the aircraft. Later, the United States introduced a new MIL-PRF-83282 standard, which is a synthetic hydrocarbon fire-resistant hydraulic oil product. Its fire resistance is better than MIL-PRF-5606 hydraulic oil, but its disadvantage is that its low-temperature performance is relatively poor. Its low-temperature use range is -40℃, which is unacceptable for aviation equipment. Subsequently, the United States introduced a new MIL-PRF-87257 fire-resistant hydraulic oil standard, the full name of which is "Synthetic hydrocarbon-based fire-resistant and low-temperature hydraulic oil for aircraft and missiles." However, the preparation of this standard fire-resistant hydraulic oil remains confidential.

[0003] From the early 1960s to the 1970s, my country successfully developed No. 10 and No. 12 aviation hydraulic oils. No. 10 aviation hydraulic oil is usually made from the 230-305℃ fraction at normal pressure, which is dewaxed by molecular sieves, refined by acid and alkali, refined by white clay, and blended with thickeners, antioxidants and dyes. The flash point of No. 10 aviation hydraulic oil is also slightly higher than 92℃, and its viscosity-temperature performance is good. The operating temperature range is -55-100℃. In order to increase the upper limit of the working temperature, my country subsequently successfully developed No. 12 aviation hydraulic oil and increased the amount of antioxidant added, which improved the thermal stability of the hydraulic oil and the upper limit of the working temperature reached 125℃. In the late 1980s, in order to further increase the upper limit of the working temperature of hydraulic oil and also for the needs of international aviation, my country successfully developed No. 15 aviation hydraulic oil. After comprehensive laboratory evaluation, bench test and flight test, it was proved that No. 15 aviation hydraulic oil is superior to No. 10 and No. 12 aviation hydraulic oil in terms of thermal stability, low temperature performance and shear stability, which is equivalent to the US MIL-PRF-5606, but there is still a certain gap with the current US new MIL-PRF-87257 fire-resistant hydraulic oil standard, especially in terms of fire resistance. With the deterioration of the quality of raw oil products, the content of straight-chain alkanes is gradually increasing, and relatively speaking, the content of branched alkanes is gradually decreasing, which puts higher requirements on the dewaxing process. At the same time, the copper sheet corrosion performance and low temperature performance indicators of No. 15 hydraulic oil have a trend of further deterioration, so it needs to be improved.

[0004] At present, domestic raw oil products need acid-base refining process to produce aviation hydraulic oil base oil that meets the requirements, and other additives are added on this basis to form the final product. Therefore, the quality of the base oil has a decisive influence on the quality of the final aviation hydraulic oil. At present, the hydrorefining process has been widely used in the petroleum industry. For example, gasoline and diesel or some lubricating oil base oils are obtained from atmospheric and vacuum distillates through the hydrorefining process. Commonly used catalysts include PHF-102 catalyst, KF757 catalyst, KF767 catalyst, etc., but the problem with these catalysts is that they are used in large quantities and have a short lifespan. They also require pre-sulfurization and other processes before use, which greatly limits the use of such catalysts. When using such catalysts to produce aviation hydraulic oil base oil, the target product has poor performance and too low a yield, which cannot meet the requirements of industrial production. Summary of the invention

[0005] In view of the problems existing in the prior art, the present invention provides a composite catalyst for the hydrorefining of aviation hydraulic oil base oil. The catalyst is used in combination of multiple types of catalysts. γ-Fe2O3 with a specific crystal structure is added to the catalyst. No pre-sulfurization process is required, and the hydrorefining process for efficiently producing aviation hydraulic oil base oil can be achieved. At the same time, the selectivity of branched alkanes in the base oil can be effectively improved, creating good conditions for subsequent dewaxing.

[0006] According to a first aspect of the present invention, a first object of the present invention is to provide a composite catalyst for hydrofining, wherein the composite catalyst comprises, by weight:

[0007] 50-1000 parts by weight of PHF-102 catalyst, 50-600 parts by weight of KF757 catalyst, 50-600 parts by weight of KF767 and 50-300 parts by weight of γ-Fe2O3.

[0008] Preferably, in parts by weight, the catalyst comprises: 100-1000 parts by weight of PHF-102 catalyst, 100-500 parts by weight of KF757 catalyst, 100-500 parts by weight of KF767 catalyst and 100-300 parts by weight of γ-Fe2O3.

[0009] Preferably, in parts by weight, the catalyst comprises: 100-1000 parts by weight of PHF-102 catalyst, 100-500 parts by weight of KF757 catalyst, 100-500 parts by weight of KF767 catalyst and 100-300 parts by weight of γ-Fe2O3.

[0010] Preferably, in parts by weight, the catalyst comprises: 100 parts by weight of a PHF-102 catalyst, 45 parts by weight of a KF757 catalyst, 45 parts by weight of a KF767 catalyst and 25 parts by weight of γ-Fe2O3.

[0011] Preferably, in terms of weight ratio, the ratio of various components in the catalyst is: PHF-102 catalyst: KF757 catalyst: KF767 catalyst: γ-Fe2O3 is 100:30-50:30-50:20-50.

[0012] Preferably, in terms of weight ratio, the ratio of various components in the catalyst is: PHF-102 catalyst: KF757 catalyst: KF767 catalyst: γ-Fe2O3 is 100:40-50:40-50:20-40.

[0013] Preferably, in terms of weight ratio, the ratio of various components in the catalyst is: PHF-102 catalyst: KF757 catalyst: KF767 catalyst: γ-Fe2O3 is 100:45:45:25.

[0014] According to the second aspect of the present invention, the second object of the present invention is to provide a method for preparing the catalyst for hydrofining, the preparation method comprising:

[0015] The various components of the composite catalyst after grinding are mixed according to proportion, and a binder is added and mixed evenly to form a slurry, which is then formed by a forming device such as a screw extruder, and then dried at 120-200° C. for 2-4 hours in an inert atmosphere to obtain the composite catalyst.

[0016] Preferably, the binder is a binder commonly used in the field of hydrogenation catalysts, for example, a 4% by weight polyvinyl alcohol aqueous solution as the binder.

[0017] According to the third aspect of the present invention, the third object of the present invention is to provide a method for hydrofining of aviation hydraulic oil base oil, the method comprising:

[0018] 1) Desalting and dehydrating the base crude oil by ultrasonic desalting.

[0019] 2) The base crude oil treated in step 1) is distilled through a normal vacuum distillation unit to obtain a normal second-line distillate oil with a distillation range of 200-260° C.,

[0020] 3) The fraction obtained in step 2) is subjected to at least two hydrogenation treatments to obtain a hydrorefined base oil, wherein the first hydrogenation reaction temperature is 340°C, the pressure is 7.0 MPa, and the space velocity is 1.5 h -1 , the hydrogen-to-oil volume ratio is 400:1, the reaction temperature of the second hydrogenation is 370°C, the pressure is 5.8MPa, and the space velocity is 2.3h -1 The volume ratio of hydrogen to oil is 580:1, and the two hydrogenation reactions are carried out using the above-mentioned composite catalyst.

[0021] Preferably, the base crude oil in step 1) is selected from one or more of Yumen crude oil, Tarim crude oil, and Tuha heavy oil.

[0022] Preferably, the base oil hydrofining treatment step 3) can further be subjected to a third hydrogenation, wherein the reaction temperature of the third hydrogenation is 380°C, the pressure is 7.0 MPa, and the space velocity is 0.6 h -1 , the volume ratio of hydrogen to oil is 580:1.

[0023] Preferably, the third hydrogenation may or may not use the composite catalyst.

[0024] Preferably, after the first hydrofining in step 3), the total aromatic content in the conventional second-line distillate oil is reduced from 12.5-18.4% of the raw material to 5.7-8.5%, the content of polycyclic aromatic hydrocarbons (naphthalenes, acenaphthenes, tricyclic aromatic hydrocarbons) is reduced from 4.8-6.2% of the raw material to 0.2-0.4%, the sulfur content is less than 1.0 μg / g, and the mass ratio of branched alkanes to straight-chain alkanes in chain alkanes is increased from 1:1-0.8:1.2 to 1.2:0.8-1.3:0.7.

[0025] Preferably, after the second hydrogenation refining in step 3), the total aromatic content is further reduced from 5.7-8.5% in the first hydrogenation to 3.0-3.4%, polycyclic aromatic hydrocarbons are substantially completely removed (undetectable amount), and the mass ratio of branched alkanes to straight-chain alkanes in the paraffins is further increased from 1.2:0.8-1.3:0.7 to 1.6:0.4-1.7:0.3.

[0026] Preferably, after the third hydrogenation in step 3), the total aromatics are reduced from 3.0-3.4% in the second hydrogenation to 2.4-2.5%.

[0027] Beneficial Effects

[0028] The composite catalyst according to the present invention successfully realizes the hydrorefining of aviation hydraulic oil base oil by reasonably regulating the ratio of different types of catalysts and adding γ-Fe2O3, while eliminating the catalyst presulfurization process, extending the life of the composite catalyst, and effectively improving production efficiency. DETAILED DESCRIPTION

[0029] Hereinafter, the present invention will be described in detail. Before describing, it should be understood that the terms used in this specification and the appended claims should not be interpreted as being limited to the general meaning and dictionary meaning, but should be interpreted according to the meaning and concept corresponding to the technical aspects of the present invention on the basis of the principle that the inventor is allowed to appropriately define the terms for the best interpretation. Therefore, the descriptions presented here are only preferred examples for illustrative purposes and are not intended to limit the scope of the present invention, so that it should be understood that other equivalents or improvements can be obtained therefrom without departing from the spirit and scope of the present invention.

[0030] In this document, the terms "include", "including", "have", "contain" or any other similar terms are open conjunctions, which are intended to cover non-exclusive inclusions. For example, a composition or product containing multiple elements is not limited to the elements listed herein, but may also include other elements that are not explicitly listed but are generally inherent to the composition or product. In addition, unless otherwise explicitly stated, the term "or" refers to an inclusive "or" rather than an exclusive "or". For example, any of the following situations satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist), A is false (or does not exist) and B is true (or exists), and A and B are both true (or exist). In addition, in this document, the interpretation of the terms "include", "including", "have", and "contain" should be considered to have been specifically disclosed and simultaneously cover closed or semi-closed conjunctions such as "consisting of" and "consisting essentially of".

[0031] In this article, all features or conditions defined in the form of numerical ranges or percentage ranges are only for brevity and convenience. Accordingly, the description of numerical ranges or percentage ranges should be deemed to have covered and specifically disclosed all possible secondary ranges and individual values ​​within the range, especially integer values. For example, the range description of "1 to 8" should be deemed to have specifically disclosed all secondary ranges such as 1 to 7, 2 to 8, 2 to 6, 3 to 6, 4 to 8, 3 to 8, etc., especially secondary ranges defined by all integer values, and should be deemed to have specifically disclosed individual values ​​such as 1, 2, 3, 4, 5, 6, 7, 8, etc. within the range. Unless otherwise specified, the above interpretation method applies to all contents of the entire present invention, regardless of whether the range is broad or not.

[0032] If the quantity or other numerical value or parameter is expressed as a range, a preferred range or a series of upper and lower limits, it should be understood that all ranges consisting of any upper limit or preferred value of the range and the lower limit or preferred value of the range have been specifically disclosed herein, regardless of whether these ranges are disclosed separately. In addition, if a numerical range is mentioned herein, unless otherwise specified, the range should include its endpoints and all integers and fractions within the range.

[0033] In this document, under the premise of achieving the purpose of the invention, numerical values ​​should be understood to have the accuracy of the number of significant digits of the numerical value. For example, the number 40.0 should be understood to cover the range from 39.50 to 40.49.

[0034] Since 2014, the quality of No. 15 aviation hydraulic oil products has gradually become unstable, manifested in the deterioration of copper sheet corrosion performance. This is mainly due to the fact that with the deepening of domestic crude oil mining, the nature of crude oil has become heavier and inferior. The crude oil density has increased from an average of 852.6kg / m 3 Increased to an average of 868.5 kg / m in 2016 3 , the sulfur content increased from 0.18% in 2010 to 0.58% in 2016.

[0035] The components of the current catalysts PHF-102, KF757 and KF767 generally contain a variety of metals and oxides, among which the main active ingredients are nickel (Ni), cobalt (Co), molybdenum (Mo), tungsten (W), etc., and aluminum oxide (Al2O3) or silicon dioxide (SiO2) as carriers. However, these catalysts are expensive because they use the above-mentioned active ingredients. For example, KF757 and KF767 catalysts are both supported catalysts, whose main active ingredients are Ni and Mo, and the carrier is generally aluminum oxide. They also need pre-sulfurization and other processes before use, which greatly limits the use of such catalysts. When using such catalysts to produce aviation hydraulic oil base oil, the target product has poor performance and too low a yield, which cannot meet the requirements of industrial production.

[0036] Fe2O3 (ferric oxide) is a polycrystalline compound and a common catalyst. There are many different crystal types, mainly including the following:

[0037] α-Fe2O3: also known as hematite, is the most stable crystal form, with a hexagonal closest packing structure, and the crystals are red or brownish red; β-Fe2O3: also known as magnetic hematite, is a magnetic hematite crystal form. Its crystal structure is similar to that of α-Fe2O3, but has different magnetic properties; γ-Fe2O3: also known as magnetic iron oxide, is a magnetic iron oxide crystal form. Its crystal structure is different from that of α-Fe2O3, showing a cubic closest packing structure. γ-Fe2O3 has high magnetism and is often used to prepare magnetic materials. In addition, there are uncommon ε-Fe2O3, ζ-Fe2O3 and δ-Fe2O3 crystal forms.

[0038] The inventors have found that adding γ-Fe2O3 with a cubic closest packing structure to the composite catalyst can not only reduce the amount of expensive catalyst used, but also ensure a good hydrorefining effect, and eliminate the need for presulfurization and other processes. This may be because the iron ions in the crystal structure of γ-Fe2O3 exist in the form of hexacoordinated octahedrons, resulting in Fe 3+ The spin state of the ion changes from high spin (HS) to low spin (LS), which allows it to bind more tightly to the sulfur atoms in the sulfur-containing components of the oil. The effects of Fe2O3 with other crystal structures, such as α-Fe2O3 and β-Fe2O3, are quite different.

[0039] As aviation base oil, it contains a variety of components, and aromatic hydrocarbons containing benzene rings, straight-chain alkanes, and sulfur content are all important indicators. Reducing the content of aromatic hydrocarbons can improve the oxidation stability of the base oil and help improve the performance of the oil.

[0040] In addition, the working environment of aviation base oil is often between -40 and -50℃, which requires good low-temperature fluidity, and the low-temperature fluidity properties (such as cloud point, pour point and cold filter point) are almost entirely dependent on the presence of straight-chain alkanes (normal alkanes). Because high-condensation point straight-chain alkanes will precipitate at low temperatures to form a wax crystal network structure, which will hinder the flow of oil products at low temperatures, causing equipment blockage and increased wear. Isomerization can reduce the pour point while keeping the molecular weight and distillation range unchanged, which allows the base oil to flow at low temperatures without solidifying. In the current aviation base oil processing technology, dewaxing is almost the only effective way to reduce all low-temperature fluidity properties and produce high-quality base oil. If the isomerization of straight-chain alkanes can be achieved as much as possible during the hydrogenation process, the pressure of the dewaxing process can be greatly reduced.

[0041] The following examples are only listed as examples of embodiments of the present invention and do not constitute any limitation to the present invention. It can be understood by those skilled in the art that modifications within the scope of the essence and concept of the present invention fall within the scope of protection of the present invention. Unless otherwise specified, the reagents and instruments used in the following examples are all commercially available products.

[0042] Catalyst Preparation Example

[0043] Example 1

[0044] Various catalyst components were prepared according to the weight ratio of PHF-102 catalyst: KF757 catalyst: KF767 catalyst: γ-Fe2O3 of 100:45:45:25, and a 4% by weight polyvinyl alcohol aqueous solution was added as a binder and fully mixed and stirred, and formed by a twin-screw screw extruder, cut into strip catalysts with a diameter of about 1.5 mm and a length of about 5 mm, and then dried at 160° C. for 4 hours under a nitrogen atmosphere to obtain a catalyst. Among them, γ-Fe2O3 was purchased from Beijing Zhongke Yannuo New Material Technology Co., Ltd., with a purity of 99.9% and a particle size of 20-50 nm in spherical particles.

[0045] Example 2

[0046] The catalyst was prepared in the same manner as in Example 1 except that the weight ratio of PHF-102 catalyst: KF757 catalyst: KF767 catalyst: γ-Fe2O3 was adjusted to 100:30:30:50.

[0047] Example 3

[0048] The catalyst was prepared in the same manner as in Example 1, except that the weight ratio of PHF-102 catalyst: KF757 catalyst: KF767 catalyst: γ-Fe2O3 was adjusted to 100:40:40:40.

[0049] Comparative Example 1

[0050] A catalyst was prepared in the same manner as in Example 1 except that γ-Fe2O3 was not added.

[0051] Comparative Example 2

[0052] A catalyst was prepared in the same manner as in Example 1 except that α-Fe2O3 was used instead of γ-Fe2O3.

[0053] Comparative Example 3

[0054] A catalyst was prepared in the same manner as in Example 1 except that β-Fe2O3 was used instead of γ-Fe2O3.

[0055] Comparative Example 4

[0056] The catalyst was prepared in the same manner as in Example 1, except that the weight ratio of PHF-102 catalyst: KF757 catalyst: KF767 catalyst: γ-Fe2O3 was adjusted to 100:30:30:100.

[0057] Test Example

[0058] Step 1) 100 kg of Yumen crude oil was subjected to ultrasonic desalting and dehydration for 3 hours;

[0059] Step 2) distilling the base crude oil treated in step 1) through a normal vacuum distillation unit to obtain a normal second-line distillate oil with a distillation range of 200-260° C., a sulfur content of 868.4 μg / g, a freezing point of -23.7° C., and a mass ratio of branched alkanes to straight-chain alkanes in the chain alkanes of about 1:1;

[0060] Step 3) The fraction obtained in step 2) is subjected to two hydrogenation treatments in a fixed bed reactor to obtain a hydrorefined base oil, wherein the first hydrogenation reaction temperature is 340°C, the pressure is 7.0 MPa, and the space velocity is 1.5 h -1 , the hydrogen-to-oil volume ratio is 400:1, the reaction temperature of the second hydrogenation is 370°C, the pressure is 5.8MPa, and the space velocity is 2.3h -1 , the volume ratio of hydrogen to oil is 580: 1. The two hydrogenation treatments are carried out using the catalysts prepared in Examples 1 to 3 and Comparative Examples 1 to 4, respectively.

[0061] Step 4) The hydrorefined base oil obtained in step 3) is subjected to a dewaxing process to remove normal alkanes in the base oil.

[0062] Step 5) Based on 100 parts by weight of base oil, 18 parts by weight of tackifier T602 (Mudanjiang Gaoxin Company), 1.1 parts by weight of antioxidant, 0.5 parts by weight of anti-wear agent tricresyl phosphate, 10 ppm of anti-foaming agent methyl silicone oil, 0.05 parts by weight of rust inhibitor Siben 80 and 0.01 parts by weight of Sudan red were weighed.

[0063] The antioxidant is a compound of two antioxidants, T501 and T531, wherein the T501 antioxidant accounts for 0.7 parts by weight and the T531 antioxidant accounts for 0.4 parts by weight.

[0064] Step 6) Heat the hydrorefined base oil obtained in step 4) to 65°C, then add the tackifier T602, antioxidant, anti-wear agent tricresyl phosphate, anti-foaming agent methyl silicone oil and Sudan red in step 5) in sequence, stir for 1-2 hours, and filter.

[0065] Step 7) The hydrorefined aviation hydraulic oil mixed in step 6) is bottled to obtain a final product.

[0066] The test data of the base oil after the hydrofining treatment in step 3) is shown in Table 1 below.

[0067] Table 1:

[0068]

[0069]

[0070] It can be seen that when using a catalyst containing a specific proportion of γ-Fe2O3 (Examples 1 to 3), the sulfur content of the hydrorefined base oil is significantly reduced, and the mass ratio of branched alkanes to straight-chain alkanes in the paraffin is significantly improved. However, when the catalyst without γ-Fe2O3 (Comparative Example 1) or the catalyst with other crystal forms of Fe2O3 (Comparative Examples 2 and 3) is used, the reduction in sulfur content is not ideal. In Comparative Example 4, although the content of γ-Fe2O3 is greatly increased, after the secondary hydrogenation, the ratio of branched alkanes to straight-chain alkanes does not change as much as expected, so the higher the content of γ-Fe2O3, the better.

[0071] The hydrorefined aviation hydraulic oils of Examples 1 to 3 and Comparative Examples 1 and 4 were tested for kinematic viscosity at different temperatures according to GB / T 265, for flash point according to GB / T 3536, for pour point according to GB / T 3535, and for copper sheet corrosion according to GB / T 5096. The results are listed in Table 2 below.

[0072] Table 2

[0073]

[0074]

[0075] It can be seen from the data in Table 2 that, compared with the case of a catalyst without γ-Fe2O3 or a catalyst containing excessive γ-Fe2O3, the aviation hydraulic oil prepared using the base oil prepared using the catalyst prepared according to the present invention has improved corrosion resistance and low temperature performance (kinematic viscosity (-54°C)).

[0076] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A composite catalyst for hydrofining, comprising, by weight: 50-1000 parts by weight of PHF-102 catalyst, 50-600 parts by weight of KF757 catalyst, 50-600 parts by weight of KF767 and 50-300 parts by weight of γ-Fe2O3.

2. The composite catalyst for hydrotreating according to claim 1, characterized in that: In parts by weight, the catalyst comprises: 100-1000 parts by weight of a PHF-102 catalyst, 100-500 parts by weight of a KF757 catalyst, 100-500 parts by weight of a KF767 catalyst and 100-300 parts by weight of γ-Fe2O3; Preferably, the catalyst comprises, by weight: 100-1000 parts by weight of PHF-102 catalyst, 100-500 parts by weight of KF757 catalyst, 100-500 parts by weight of KF767 catalyst and 100-300 parts by weight of γ-Fe2O3; Preferably, the catalyst comprises, by weight: 100 parts by weight of a PHF-102 catalyst, 45 parts by weight of a KF757 catalyst, 45 parts by weight of a KF767 catalyst and 25 parts by weight of γ-Fe2O3; Preferably, the ratio of various components in the catalyst is 100:30-50:30-50:20-50 by weight: PHF-102 catalyst: KF757 catalyst: KF767 catalyst: γ-Fe2O3; Preferably, the ratio of various components in the catalyst is 100:40-50:40-50:20-40 by weight: PHF-102 catalyst: KF757 catalyst: KF767 catalyst: γ-Fe2O3; Preferably, in terms of weight ratio, the ratio of various components in the catalyst is: PHF-102 catalyst: KF757 catalyst: KF767 catalyst: γ-Fe2O3 is 100:45:45:

25.

3. The method for preparing a catalyst for hydrofining according to claim 1 or 2, the method comprising: The various components of the composite catalyst after grinding are mixed according to proportion, and a binder is added and mixed evenly to form a slurry, which is then formed by a forming device such as a screw extruder, and then dried at 120-200° C. for 2-4 hours in an inert atmosphere to obtain the composite catalyst.

4. A method for hydrofining an aviation hydraulic oil base oil, the method comprising: 1) Desalting and dehydrating the base crude oil by ultrasonic desalting. 2) The base crude oil treated in step 1) is distilled through a normal vacuum distillation unit to obtain a normal second-line distillate oil with a distillation range of 200-260° C., 3) The fraction obtained in step 2) is subjected to at least two hydrogenation treatments to obtain a hydrorefined base oil, wherein the first hydrogenation reaction temperature is 340°C, the pressure is 7.0 MPa, and the space velocity is 1.5 h -1 , the hydrogen-to-oil volume ratio is 400:1, the reaction temperature of the second hydrogenation is 370°C, the pressure is 5.8MPa, and the space velocity is 2.3h -1 , the hydrogen-to-oil volume ratio is 580:1, and the two hydrogenation reactions are carried out using the catalyst for hydrorefining according to claim 1 or 2.

5. The hydrotreating method according to claim 4, characterized in that: The base crude oil in step 1) is selected from one or more of Yumen crude oil, Tarim crude oil, and Tuha heavy oil.

6. The hydrotreating method according to claim 4, characterized in that: The base oil hydrofining treatment step 3) further performs a third hydrogenation, wherein the reaction temperature of the third hydrogenation is 380° C., the pressure is 7.0 MPa, and the space velocity is 0.6 h -1 , hydrogen-to-oil volume ratio is 580:1; Preferably, the third hydrogenation may or may not use the catalyst for hydrotreating according to claim 1 or 2.

7. The hydrotreating method according to claim 4, characterized in that: After the first hydrorefining in step 3), the total aromatic content in the conventional second-line distillate oil is reduced from 12.5-18.4% of the raw material to 5.7-8.5%, the content of polycyclic aromatic hydrocarbons (naphthalene, acenaphthene, tricyclic aromatic hydrocarbons) is reduced from 4.8-6.2% of the raw material to 0.2-0.4%, the sulfur content is less than 1.0 μg / g, and the mass ratio of branched alkanes to straight-chain alkanes in chain alkanes is increased from 1:1-0.8:1.2 to 1.2:0.8-1.3:0.

7.

8. The hydrotreating method according to claim 4, characterized in that: Preferably, after the second hydrogenation refining in step 3), the total aromatic content is further reduced from 5.7-8.5% in the first hydrogenation to 3.0-3.4%, polycyclic aromatic hydrocarbons are substantially completely removed (undetectable amount), and the mass ratio of branched alkanes to straight-chain alkanes in the paraffins is further increased from 1.2:0.8-1.3:0.7 to 1.6:0.4-1.7:0.

3.

9. The hydrotreating method according to claim 6, characterized in that: Preferably, after the third hydrogenation in step 3), the total aromatics are reduced from 3.0-3.4% in the second hydrogenation to 2.4-2.5%.

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