Catalyst for synthesizing lubricant base oil, preparation method and application

Abstract

The invention relates to the technical field of lubricating oil base oil synthesis, in particular to a catalyst for lubricating oil base oil synthesis and a preparation method and application thereof.The method comprises the steps that firstly, a guiding agent assisted dynamic hydrothermal synthesis method is adopted for preparing an FAU type zeolite precursor with the high silica-alumina ratio and the high crystallinity; regulating and controlling surface charges and acidic sites through ammonium exchange, performing liquid-phase dealumination and silicon supplementation to improve the silicon-aluminum ratio of a framework, and constructing rich through type mesopores in a microporous system; finally, weak base treatment and secondary deep ammonium exchange are combined to further optimize pore connectivity, acidity distribution and structural stability, and the catalyst is obtained through high-temperature roasting activation. The catalyst has the advantages of high silica-alumina ratio, high crystallinity, through multistage pore channels and accurately modulated acidity distribution, and solves the problems of low activity, easy carbon deposition and limited mass transfer of the traditional FAU zeolite in alkylation reaction. The alkyl naphthalene base oil synthesized by using the catalyst has the advantages of high viscosity index, low pour point, high flash point and outstanding thermal oxidation stability.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of synthetic lubricating oil base oil, in particular to a catalyst for synthesizing lubricating oil base oil, a preparation method and application. BACKGROUND

[0002] As an indispensable key material in industrial production and mechanical operation, the performance of lubricating oil is directly related to the operation efficiency, service life and maintenance cost of equipment and many other aspects. In the field of lubricating oil, the selection of base oil is one of the core factors determining the performance of lubricating oil. For a long time, mineral base oil has occupied a dominant position in the lubricating oil market due to its abundant resource reserves and relatively low production cost, and is widely used in various ordinary mechanical equipment and industrial scenes. Mineral base oil is mainly extracted from the petroleum refining process, and its composition is complex, containing various hydrocarbon compounds, which can meet general lubrication requirements. However, due to its poor thermal stability and oxidation stability, it cannot meet the requirements of the high-end lubricating oil market.

[0003] Synthetic base oil is a good supplement to the lubricating oil market. Common synthetic base oils include polyalphaolefin (PAO) of the fourth type of lubricating oil and alkyl naphthalene of the fifth type of lubricating oil. Compared with mineral base oil, synthetic base oil has better low-temperature fluidity, higher oxidation stability, thermal stability, lower evaporation loss rate and good additive solubility. As the fifth type of lubricating oil, alkyl naphthalene base oil has more outstanding oxidation stability and additive solubility advantages compared with other synthetic base oils. Alkyl naphthalene has broad application prospects and can be used as a base oil alone or as an additive for mineral oil base oil and other synthetic base oils, mainly for high-end lubricating oil and lubricating grease.

[0004] At present, long-chain alkyl naphthalene is mainly prepared by alkylation of naphthalene, and common alkylating agents include long-chain alpha-olefins, halogenated alkanes and alcohols. Using long-chain alpha-olefins as the alkylating agent, the properties of the obtained base oil product are more excellent, and common alkylation catalysts include inorganic acids (concentrated sulfuric acid, HF, etc.), Lewis acids (AlCl3, ZnCl2, FeCl3, etc.). However, these catalysts have strong corrosiveness, which can cause serious corrosion to the reaction equipment during the reaction, not only shortening the service life of the equipment and increasing the maintenance cost of the equipment, but also having certain safety hazards. At the same time, these catalysts also have the problems of serious environmental pollution, difficulty in separating the product raw materials and poor selectivity, which not only causes serious pollution to the environment and increases the difficulty and cost of subsequent treatment, but also cannot synthesize the target product alkyl naphthalene with high selectivity, so that there are many by-products in the product, affecting the quality and performance of the product.

[0005] FAU type zeolite is a cubic system zeolite molecular sieve with unique three-dimensional twelve-membered ring pore system (pore size about 0.74 nm), which occupies a core position in the industrial fields of petroleum refining, gas separation, catalytic cracking and the like due to its high specific surface area, adjustable silicon aluminum ratio and excellent thermal / chemical stability. The framework silicon aluminum ratio of the FAU type zeolite is one of the key factors determining its catalytic performance. The silicon aluminum ratio (SiO2 / Al2O3) of the FAU type zeolite synthesized by the conventional method is usually between 4.8-5.0, and the corresponding unit cell constant is about 2.4654 nm. The synthesis of high-silicon FAU type zeolite (SiO2 / Al2O3>5.0) is more difficult, especially when the silicon aluminum ratio is more than 6.0, which is mainly due to the fact that the crystallization process is controlled by reaction kinetics. In the synthesis of high-silicon FAU zeolite, the activation energy of the polycondensation reaction between polysilicate and aluminate is high, and the reaction rate constant is low, which leads to the difficulty in effective polymerization and crystallization. Although the silicon aluminum ratio can be further increased by acid treatment, the process is easy to cause the damage of the framework structure, resulting in the significant decrease of the relative crystallinity, and the adverse effects on the stability and acidity of the zeolite. It can be seen that the existing synthesis and modification methods not only have complicated steps and low yield, but also damage the crystal integrity of the zeolite, weaken the structural stability, and further affect the catalytic performance and service life. Especially, it is worth noting that the secondary channels generated by the damage of the framework are mainly in the structure of “ink bottle”, and the connectivity between the channels is poor, so the diffusion of macromolecules is still limited by the narrow pore size, and therefore the effect of the method on the improvement of the catalyst performance is limited. SUMMARY

[0006] In view of the problem in the prior art that the FAU type zeolite has poor catalytic performance due to the difficulty in forming a stable framework with high silicon aluminum ratio caused by the reaction kinetics control in the preparation process of the FAU type zeolite, the application provides a catalyst for the synthesis of lubricating oil base oil, a preparation method and application.

[0007] In order to achieve the above-mentioned purpose, the following technical solutions are adopted in the application: The application provides a preparation method of a catalyst for the synthesis of lubricating oil base oil, which comprises the following steps: ammonium exchange of FAU zeolite to obtain NH4Y zeolite; de-alumination and silicon supplementation treatment of the NH4Y zeolite, followed by weak alkali treatment and secondary ammonium exchange to obtain modified zeolite; calcination and activation treatment of the modified zeolite to obtain the catalyst for the synthesis of lubricating oil base oil.

[0008] Optionally, the preparation method of the FAU zeolite comprises the following steps: preparation of a directing agent solution by using an alkali source, an aluminum source, a silicon source and water; preparation of a first composition by using a silicon source, an alkali source, an organic structure template agent and water; a second composition is prepared by using an aluminum source and water; the first composition is added to the directing agent solution and mixed uniformly to obtain a third composition; the second composition is added dropwise to the third composition and mixed uniformly and aged to obtain a gel mixture; after the gel mixture is dynamically aged, it is first dynamically crystallized and then statically crystallized to separate the solid and liquid phases, the separated solid phase is sequentially dried and calcined to obtain the FAU zeolite.

[0009] Optionally, the molar ratio of the alkali source, the aluminum source, the silicon source and water in the directing agent solution is (5-30):1:(5-35):(250-450); the molar ratio of the silicon source, the alkali source, water and the organic structure template in the gel mixture is (10-20):1:(5-25):(300-450):(0.05-0.8); the mass of the directing agent solution accounts for 20%-30% of the total mass of the gel mixture.

[0010] Optionally, the aluminum source is selected from one or more of sodium metaaluminate, aluminum sulfate, aluminum isopropoxide, aluminum hydroxide, pseudo-boehmite, aluminum oxide and aluminum nitrate; the silicon source is selected from one or more of white carbon black, silica sol, solid silica gel, tetraethyl orthosilicate and water glass; the organic structure template is selected from one or more of tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, tetrapentylammonium hydroxide, tetrahexylammonium hydroxide, tetrapropylammonium bromide and tetrabutylammonium chloride; the alkali source is Na2O.

[0011] Optionally, the method for ammonium exchanging the FAU zeolite to obtain the NH4Y zeolite is: the FAU zeolite is repeatedly ammonium exchanged with an aqueous solution of ammonium chloride with a concentration of 0.5-1.5 mol / L until the mass fraction of sodium ions in the FAU zeolite is reduced to 0.05% or less to obtain the NH4Y zeolite.

[0012] Optionally, the method for obtaining the modified zeolite after the NH4Y zeolite is subjected to dealumination and silicon supplementation, then subjected to weak alkali treatment and secondary ammonium exchange is: The NH4Y zeolite is dispersed in a buffer solution, and ammonium fluosilicate solution with a concentration of 0.01-1.5 mol / L is added dropwise at a rate of 1-10 mL / min at 50-95 DEG C, with the mass ratio of ammonium fluosilicate to NH4Y zeolite being (0.05-0.5):1, and the reaction is carried out for 0.5-4 h, and then filtration, washing and drying are sequentially carried out to complete the dealumination and silicon supplementation treatment; wherein the buffer solution is one or a combination of more than one of the following: an aqueous solution of ammonium oxalate, ammonium citrate, ammonium acetate, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, ammonium carbonate and a buffer solution composed of ammonia and ammonium chloride, with the concentration being 0.05-1.0 mol / L. The NH4Y zeolite after the dealumination and silicon supplementation treatment is treated with weak alkali solution with a concentration of 0.01-3.0 mol / L, and then filtration, washing to neutral and drying are carried out to obtain a solid material; the weak alkali solution is ammonia, ammonium carbonate or ammonium bicarbonate solution. The solid material is again treated with 0.5-1.5 mol / L ammonium chloride aqueous solution at 95-110 DEG C, and then two ammonium exchanges are repeatedly carried out until the mass fraction of sodium ions is less than 0.05% to obtain the modified zeolite.

[0013] Optionally, the calcination activation treatment is carried out at a temperature of 350-900 DEG C for 2-6 h.

[0014] A catalyst for the synthesis of lubricating oil base oil is prepared by the above-mentioned method for preparing a catalyst for the synthesis of lubricating oil base oil.

[0015] The above-mentioned catalyst for the synthesis of lubricating oil base oil is applied to the preparation of alkyl naphthalene base oil, which comprises: Solid naphthalene is added into an organic solvent, and the solid naphthalene is melted and uniformly mixed with the organic solvent by heating to obtain a naphthalene-containing reaction system. The catalyst for the synthesis of lubricating oil base oil is added into the naphthalene-containing reaction system, and then alpha-olefin is added for alkylation reaction after the temperature is continuously increased to a target reaction temperature to obtain alkyl naphthalene base oil.

[0016] Optionally, the organic solvent is one or a mixture of C12-C14 normal alkanes; the alpha-olefin is one or a mixture of C6-C14 medium-long chain alpha-olefins; the molar ratio of solid naphthalene to alpha-olefin is 1:(0.5-2.5); the mass ratio of the sum of the mass of solid naphthalene and alpha-olefin to the mass of the organic solvent is (1-2):1; the mass ratio of naphthalene to the catalyst for the synthesis of lubricating oil base oil is 1:(0.05-0.15); and the target reaction temperature is 60-165 DEG C, and the alkylation reaction time is 0.5-1 h.

[0017] Compared with the prior art, the present application has the following beneficial effects: This invention provides a method for preparing a catalyst for the synthesis of lubricating oil base oils. The method first involves ammonium exchange of FAU zeolite, replacing most or all of the original cations in the FAU zeolite with ammonium ions to obtain NH4Y zeolite. This process effectively alters the surface charge distribution and acidic site properties of the FAU zeolite, creating a favorable foundation for subsequent modification. Then, the NH4Y zeolite undergoes dealumination and silica replenishment treatment, followed by weak alkali treatment and a second ammonium exchange to obtain the modified zeolite. The dealumination and silica replenishment treatment effectively increases the silica-alumina ratio of the framework, enhances the catalyst's thermal stability, optimizes acid properties, and introduces abundant mesopores into the microporous system, forming a continuous hierarchical pore structure and improving diffusion performance. Subsequently, the dealumination and silica replenished zeolite is treated with a weak alkali to remove amorphous fragments and clear mesoporous channels. A second deep ammonium exchange further reduces the sodium ion content and purifies the acidic sites, further improving the catalyst's stability and the accessibility of active sites. Finally, the modified zeolite is calcined and activated to obtain the catalyst for the synthesis of lubricating oil base oils. Calcination activation treatment can effectively remove residual template agents, complete the conversion from ammonium form to hydrogen form, and stabilize the crystal structure and pore system of the final catalyst, ensuring the structural stability and service life of the final product. This gives the prepared catalyst comprehensive characteristics such as high silicon-to-aluminum ratio, high crystallinity, interconnected multi-level pores, and optimized acidity distribution. As a result, in the catalytic reaction of naphthalene and α-olefin alkylation, the reaction time is shortened from 4-6 hours in the traditional process to 0.5-1 hour, while maintaining high conversion rate, high selectivity, and good stability, thus enhancing the market competitiveness of the product.

[0018] The method for preparing FAU zeolite involves first preparing a directing agent solution using an alkali source, an aluminum source, a silicon source, and water; then, preparing a first composition using a silicon source, an alkali source, an organic structural template agent, and water; preparing a second composition using an aluminum source and water; finally, adding the first composition to the directing agent solution and mixing thoroughly to obtain a third composition; then, adding the second composition dropwise to the third composition, mixing thoroughly, and aging to obtain a gel mixture; after dynamic aging of the gel mixture, dynamic crystallization followed by static crystallization until solid and liquid phases separate; the separated solid phase is then dried and calcined sequentially to obtain FAU zeolite. This method uses a specific composition of directing agent and optimized material ratios to prepare a FAU-type zeolite precursor with high crystallinity and an initial hierarchical porous structure through hydrothermal crystallization, thereby obtaining a matrix with a regular structure and good modifiability, providing a structural basis for subsequent modification.

[0019] A catalyst for the synthesis of lubricating oil base oils is prepared using the aforementioned method. This catalyst exhibits a high silica-to-alumina ratio, resulting in better structural stability. Under high-temperature or hydrothermal environments, it is less prone to collapse and destruction. In the alkylation reaction of naphthalene and α-olefins, it effectively ensures the catalyst maintains a stable structure during prolonged reactions, thus sustaining its catalytic activity and extending its lifespan. Simultaneously, the high silica-to-alumina ratio reduces the aluminum content in the zeolite, thereby decreasing the number of strong acid sites and enhancing the catalyst's selectivity. It effectively catalyzes the alkylation reaction of naphthalene and α-olefins while minimizing side reactions. Furthermore, this catalyst possesses higher crystallinity and a interconnected hierarchical pore structure, further ensuring structural stability, catalytic efficiency, and lifespan during the catalytic reaction. This significantly reduces the alkylation reaction time of naphthalene and α-olefins, increases conversion rate, and enhances product competitiveness and economic value.

[0020] The application of the aforementioned catalyst for lubricating oil base oil synthesis in the preparation of alkylnaphthalene base oil involves adding solid naphthalene to an organic solvent, heating to melt the solid naphthalene and mix it uniformly with the organic solvent to obtain a naphthalene-containing reaction system. The catalyst for lubricating oil base oil synthesis is then added to this naphthalene-containing reaction system, and the temperature is further increased to the target reaction temperature. Subsequently, an α-olefin is added to carry out an alkylation reaction, yielding the alkylnaphthalene base oil. This catalysis can precisely control the progress of the lubricating oil base oil synthesis reaction, effectively improving the yield and selectivity of the target product, reducing the formation of by-products, and resulting in a synthesized lubricating oil base oil with superior physicochemical properties. This meets the stringent quality requirements of modern high-end lubricating oils, demonstrating good economic feasibility and market competitiveness, and is of great significance for promoting the sustainable development of the lubricating oil industry. Attached Figure Description

[0021] Figure 1 This is a schematic flowchart of a method for preparing a catalyst for the synthesis of lubricating oil base oil according to the present invention.

[0022] Figure 2 The XRD patterns are of the catalysts for the synthesis of lubricating oil base oils prepared in Examples 1-3 of the present invention.

[0023] Figure 3 The images shown are SEM images of the catalysts for the synthesis of lubricating oil base oil prepared in Examples 1-3 of the present invention, wherein a is an SEM image of catalyst C-1 for the synthesis of lubricating oil base oil prepared in Example 1, b is an SEM image of catalyst C-2 for the synthesis of lubricating oil base oil prepared in Example 2, and c is an SEM image of catalyst C-3 for the synthesis of lubricating oil base oil prepared in Example 3. Detailed Implementation

[0024] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0025] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.

[0026] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0027] In this article, unless otherwise specified, “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of,” for example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a.”

[0028] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0029] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0030] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications conventional in the art. In this specification and the following examples, unless otherwise specified, "%" refers to weight percentage, "parts" refers to parts by weight, and "ratio" refers to weight proportion.

[0031] The present invention will be further described in detail below with reference to specific embodiments. These descriptions are for explanation purposes only and are not intended to limit the scope of the invention.

[0032] See Figure 1 This invention provides a method for preparing a catalyst for the synthesis of lubricating oil base oils, characterized by comprising: S1: FAU zeolite is subjected to ammonium exchange to obtain NH4Y zeolite, specifically as follows: FAU zeolite is added to a 0.5-1.5 mol / L ammonium chloride aqueous solution and allowed to stand for 1-3 hours at 60-120°C to exchange the ammonium chloride, thereby obtaining NH4Y zeolite. Preferably, this process is repeated 2-3 times. More preferably, the ammonium exchange temperature is 90-120°C and the standing exchange time is 2.5-3 hours. Preferably, the preparation method of the FAU zeolite is as follows: The alkaline source, aluminum source, silicon source and water are mixed evenly in a molar ratio of (5-30):1:(5-35):(250-450) and aged at 15-60℃ for 7-72 ​​hours to obtain the directing agent solution. Preferably, the molar ratio of alkaline source, aluminum source, silicon source and water is (10-20):1:(5-25):(300-450), more preferably, it is (10-18):1:(10-25):(300-400). Preferably, the directing agent solution is aged dynamically for 2-6 hours at 15-60℃, and then aged statically in a sealed state for 10-72 hours. More preferably, it is aged dynamically for 2-4 hours at 25-40℃, and then aged statically in a sealed state for 10-24 hours.

[0033] The silicon source, alkali source, organic structural template agent and water are prepared into a first composition under conditions of 15-75℃. A second composition was prepared using an aluminum source and water; The first composition is added to the directing agent solution and mixed evenly to obtain the third composition; The second composition is slowly added dropwise to the third composition, mixed evenly, and aged to obtain a gel mixture; The gel mixture is subjected to dynamic aging at 15-90℃ for 2-8 hours, followed by dynamic crystallization at 70-180℃ for 2-6 hours, and then static crystallization for 8-14 hours until the solid and liquid phases separate. The separated solid phase is then subjected to drying at 100-150℃ for 12-18 hours and calcination at 550-650℃ for 4-8 hours to obtain FAU zeolite. Preferably, the mixture is first dynamically crystallized at 90-120℃ for 2-4 hours, followed by static crystallization for 8-10 hours.

[0034] In the gel mixture, the molar ratio of silicon source, alkali source, water, and organic structural template agent is (10-20):1:(5-25):(300-450):(0.05-0.8); the mass of the directing agent solution accounts for 20%-30% of the total mass of the gel mixture, preferably 20%-25%; the aluminum source is selected from one or more of sodium aluminate, aluminum sulfate, aluminum isopropoxide, aluminum hydroxide, boehmite, alumina, and aluminum nitrate; the silicon source is selected from one or more of silica, silica sol, solid silica gel, tetraethyl orthosilicate, and water glass; the organic structural template agent is selected from one or more of tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, tetrapentylammonium hydroxide, tetrahexylammonium hydroxide, tetrapropylammonium bromide, and tetrabutylammonium chloride; and the alkali source is Na2O.

[0035] The purpose of ammonium exchange in FAU zeolite is to completely remove sodium ions from the zeolite through multiple ammonium exchanges, converting it into catalytically active NH4-Y type zeolite, and providing a pure precursor for subsequent modification.

[0036] S2: After dealuminizing and siliconizing the NH4Y zeolite, it is subjected to weak alkali treatment and secondary ammonium exchange to obtain the modified zeolite, specifically: NH4Y zeolite is dispersed in a buffer solution. At 50-95℃, an ammonium fluorosilicate solution with a concentration of 0.01-1.5 mol / L is added dropwise at a rate of 1-10 mL / min, with a mass ratio of ammonium fluorosilicate to NH4Y zeolite of (0.05-0.5):1. The reaction is allowed to proceed for 0.5-4 h. The mixture is then sequentially filtered, washed, and dried to complete the dealuminization and silicon replenishment treatment. The buffer solution is an aqueous solution of one or more combinations of ammonium oxalate, ammonium citrate, ammonium acetate, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, ammonium carbonate, and a buffer solution composed of ammonia and ammonium chloride, with a concentration of 0.05-1.0 mol / L. After the NH4Y zeolite underwent dealuminization and silicon replenishment treatment, it was treated with a weak alkaline solution with a concentration of 0.01-3.0 mol / L, filtered, washed until neutral, and dried to obtain a solid material; the weak alkaline solution was ammonia water, ammonium carbonate, or ammonium bicarbonate solution. The solid material is subjected to a second ammonium exchange process again with a 0.5-1.5 mol / L ammonium chloride aqueous solution at 95-110°C until the sodium ion mass fraction is below 0.05%, thus obtaining the modified zeolite. Preferably, the exchange time for each second ammonium exchange is 2.5-3 hours, and this process is repeated 2-3 times to ensure that the final sodium ion mass fraction is below 0.05%.

[0037] In this step, the purpose of liquid-phase dealuminization and silicon addition in the ammonium fluorosilicate solution controlled by the buffer system is to achieve selective removal of aluminum from the zeolite framework and simultaneous insertion of silicon, thereby synergistically regulating the physicochemical properties of the zeolite, specifically manifested as follows: (i) Significantly improves the silica-alumina ratio of the zeolite framework, thereby enhancing its hydrothermal stability and structural stability, and optimizing its acid properties to form an acidic distribution dominated by strong acid sites and with a suitable total acid density, thereby effectively suppressing side reactions and improving its resistance to carbon deposition. (ii) Creating abundant mesoporous structures within the microporous framework and constructing a multi-level pore system greatly improves the diffusion and mass transfer efficiency of macromolecular reactants and products, and exposes more accessible active sites.

[0038] The synergistic optimization of the above structures is key to endowing the catalyst with excellent reactivity, selectivity and stability, ultimately achieving process intensification of the alkylation reaction.

[0039] By utilizing the selective dissolution effect of a weak alkaline solution, amorphous silicon-aluminum fragments generated during the dealumination and silicon replenishment process are removed, thereby clearing newly generated mesoporous channels and preventing active sites from being covered. At the same time, the slight etching of the zeolite framework by the weak alkaline solution can further optimize the size and connectivity of the mesoporous structure, forming an open channel system with higher mass transfer efficiency.

[0040] Secondary ammonium exchange is a deep and repeated process of ammonium exchange following weak alkali treatment. Its purpose is threefold: First, to ensure the complete removal of residual and stray cations that may have been introduced during the weak alkali treatment from the zeolite; second, to achieve pure and uniform activation of all acidic sites on the finally determined high silica-alumina ratio framework, ensuring that the catalyst has uniform and stable Brønsted acidity; and third, to ultimately stabilize the sodium ion content at an extremely low level (<0.05%), thereby maximizing the catalyst's thermal stability, acid strength, and resistance to deactivation.

[0041] These refinement steps work together to consolidate and enhance the results of previous modifications, and are key to obtaining process-enhancing catalysts with high stability, long lifespan, and excellent reusability.

[0042] S3: The modified zeolite is calcined and activated to obtain a catalyst for the synthesis of lubricating oil base oils, specifically: The modified zeolite was calcined and activated at 350-900℃ for 2-6 hours to obtain a catalyst for the synthesis of lubricating oil base oil.

[0043] The purpose of the calcination activation treatment is to transform the catalyst from a precursor to its final active form. Its effects are multifaceted: it thoroughly removes residual organic structural templates and any organic species from the zeolite channels, completely opening and unblocking all channels to ensure the accessibility of active sites. It converts ammonium-type (NH4Y) zeolite into hydrogen-type (HY) zeolite, activating Brønsted acid centers through thermal decomposition, thus endowing it with intrinsic activity for catalytic alkylation reactions. It stabilizes the zeolite's crystal framework and hierarchical pore structure, healing some defects and reinforcing mesoporous pore walls through high-temperature structural rearrangement and condensation of surface silanol groups, thereby significantly improving the catalyst's final structural stability, hydrothermal stability, and lifespan. This step is a crucial final step in ensuring the catalyst possesses high initial activity, excellent selectivity, and long-term stability.

[0044] The present invention also provides a catalyst for the synthesis of lubricating oil base oil, which is prepared using the above-described method for preparing the catalyst for the synthesis of lubricating oil base oil.

[0045] The FAU zeolite-based process enhancement catalyst prepared by the above method has the following optimized physicochemical properties: Crystal structure and composition: The relative crystallinity of the FAU zeolite-based process enhancement catalyst obtained by the above preparation method is not less than 87%, and the skeletal silicon-aluminum molar ratio is not less than 16.

[0046] Texture properties: Specific surface area not less than 650 m² / g, total pore volume not less than 0.55 cm³ / g, of which mesoporous pore volume accounts for not less than 45% of the total pore volume.

[0047] Acidity characteristics: Total acid density not higher than 0.20 mmol / g, and strong Brønsted acid center density not lower than 0.080 mmol / g.

[0048] This invention provides the application of the above-mentioned catalyst for the synthesis of lubricating oil base oil in the preparation of alkylnaphthalene base oil, comprising: Under an inert atmosphere (preferably nitrogen), solid naphthalene is added to an organic solvent and heated to 60-90°C to melt the solid naphthalene and mix it evenly with the organic solvent to obtain a naphthalene-containing reaction system. A catalyst used for the synthesis of lubricating oil base oils was added to a naphthalene-containing reaction system. The temperature was then raised to 60-165℃, followed by the addition of α-olefins to induce alkylation, yielding alkylnaphthalene base oils. During the reaction, the system pressure was maintained within the range of 1.0-3.5 atm. After the addition was complete, the reaction continued under these conditions for 0.5-1 hour to complete the alkylation reaction.

[0049] Wherein, the organic solvent is one or a mixture of C12-C14 n-alkanes; the α-olefin is one or a mixture of C6-C14 medium-long chain α-olefins; the molar ratio of solid naphthalene to α-olefin is 1:(0.5-2.5); the mass ratio of the sum of the masses of solid naphthalene and α-olefin to the mass of the organic solvent is (1-2):1; the mass ratio of naphthalene to the catalyst used for the synthesis of lubricating oil base oil is 1:(0.05-0.15).

[0050] After the reaction, the crude product was subjected to vacuum distillation to remove unreacted raw materials and solvents. The residue was then thoroughly centrifuged to separate and collect the catalyst used for the synthesis of lubricating oil base oils, yielding the reaction product alkylnaphthalene. The catalyst collected for lubricating oil base oil synthesis can be regenerated through hydrothermal calcination at 600°C with 100% steam. The regenerated catalyst can be reused in the synthesis of alkylnaphthalenes while maintaining high catalytic activity.

[0051] Example 1 In this embodiment, the molar ratio of the directing agent components is Na2O:Al2O3:SiO2:H2O = 17.4:1:24.5:388.7. At a water bath temperature of 40℃, 7.82g of sodium hydroxide was slowly added, and stirring continued until the sodium hydroxide was completely dissolved. Then, 1.81g of sodium aluminate was slowly added, maintaining the original stirring rate to ensure that the sodium aluminate was fully dissolved and mixed evenly with the system. Finally, 45.37g of deionized water was added to the beaker, and dynamic stirring was maintained for 120min. The mixture was then allowed to stand for 24h to obtain the directing agent solution.

[0052] At a water bath temperature of 60℃, 165g of water glass solution (Na2O 9.96wt%, SiO2 31.5wt%) was added to another beaker, and the mixture was stirred dynamically. 9.39g of sodium hydroxide was slowly added, and stirring continued until the sodium hydroxide was completely dissolved. Then, 2.17g of sodium aluminate and 100g of directing agent solution were slowly added, and the mixture was stirred dynamically for 200min to ensure that the components were fully mixed. 80g of aluminum sulfate solution (Al2O3 7.8wt%) was slowly added to the above beaker, and the mixture was dynamically aged for 6h to obtain a gel mixture. The molar ratio of the components in the gel mixture was Na2O:Al2O3:SiO2:H2O:R = 4.6:1:13.2:205.1:0.42.

[0053] The gel mixture was added to a polytetrafluoroethylene-lined crystallization vessel and dynamically crystallized at 120°C for 4 hours, followed by static crystallization for 8 hours. The crystallized product was thoroughly filtered with deionized water, washed, and dried in an oven at 120°C for 18 hours. Then it was calcined at 550°C for 4 hours to obtain the FAU zeolite sample.

[0054] Testing revealed that the FAU zeolite synthesized in Example 1 had a crystallinity of 88% and a BET specific surface area of ​​855 m². 2 / g, with an external specific surface area of ​​77m² 2 / g, total pore volume is 0.55cm³ 3 / g, mesopore volume is 0.28cm³ 3 / g, with a framework silicon-to-aluminum ratio of 16.3 and a grain size of approximately 350nm.

[0055] Take 50g of the above-mentioned FAU zeolite and mix it with a solution prepared from 50g of ammonium chloride and 500g of deionized water. Stir and exchange the solution at 95℃ for 3 hours. Repeat this process three times. The sodium ion mass fraction in the resulting NH4Y zeolite was found to be reduced to 0.03%.

[0056] The obtained NH4Y zeolite was dispersed in a 0.2 mol / L ammonium citrate buffer solution. Approximately 1.06 L of a 0.05 mol / L ammonium fluorosilicate solution was slowly added dropwise at a rate of 3 mL / min under stirring conditions at 95 °C. After reacting for 90 min, the mixture was filtered, washed with deionized water until neutral, and dried at 110 °C. Subsequently, this dealumination and silicon replenishment process was repeated once under the same conditions, with the reaction time adjusted to 1.5 h.

[0057] The dealuminated and silica-added NH4Y zeolite was mixed in a 0.5 mol / L ammonia solution and treated at 90°C for 1.5 h. The mixture was then filtered, washed until neutral, and dried. The resulting solid was then mixed with 10 times its mass of a 1 mol / L ammonium chloride solution and subjected to a second ammonium exchange at 95°C for 3 h per exchange. This process was repeated three times to obtain the modified zeolite, with a final product containing 0.02% sodium ions by mass.

[0058] The modified zeolite was calcined at 600℃ for 4 hours to obtain a catalyst, denoted as C-1, for the synthesis of lubricating oil base oils. The physicochemical properties of catalyst C-1 prepared in Example 1 were characterized, and the results are as follows: The catalyst has a framework silicon-to-aluminum ratio of 18.6, a cell parameter of 2.435 nm, and a relative crystallinity of 89%.

[0059] Its specific surface area and pore structure parameters are as follows: total specific surface area 750 m² / g, total pore volume 0.565 cm³ / g; of which: mesoporous specific surface area 130 m² / g, mesoporous pore volume 0.290 cm³ / g.

[0060] The acidity characteristics are as follows: total acid density is 0.185 mmol / g; total Lewis acid density is 0.088 mmol / g, of which the density of strong Brønsted acid centers is 0.085 mmol / g and the density of strong Lewis acid centers is 0.065 mmol / g; acid center strength is 0.37.

[0061] Example 2 In this embodiment, except that the ammonium fluorosilicate solution is changed to 0.1 mol / L, the rest is the same as in Example 1, and the catalyst prepared for the synthesis of lubricating oil base oil is denoted as C-2.

[0062] The catalyst C-2 prepared in Example 2 was structurally characterized, and its physicochemical properties are as follows: The catalyst has a framework silicon-to-aluminum ratio of 22.4, a cell parameter of 2.433 nm, and a relative crystallinity of 87%.

[0063] Its texture properties are as follows: total specific surface area is 700 m² / g, mesoporous specific surface area is 180 m² / g; total pore volume is 0.638 cm³ / g, of which micropore volume is 0.283 cm³ / g and mesopore volume is 0.355 cm³ / g.

[0064] Characterization of acid properties showed that the total acid density was 0.185 mmol / g; among which, the density of strong Brønsted acid was 0.092 mmol / g, the total Lewis acid density was 0.073 mmol / g (the density of strong Lewis acid was 0.043 mmol / g); and the acid center strength was 0.51.

[0065] Example 3 In this embodiment, the buffer solution is changed to 0.25 mol / L ammonium oxalate, and the rest is the same as in Example 1. The catalyst prepared for the synthesis of lubricating oil base oil is denoted as C-3.

[0066] The physicochemical properties of catalyst C-3 prepared in Example 3 were characterized, and the results are as follows: The catalyst has a framework silicon-to-aluminum ratio of 19.4, a cell parameter of 2.435 nm, and a relative crystallinity of 87%.

[0067] Its specific surface area and pore structure parameters are as follows: total specific surface area 660 m² / g; of which, micropore specific surface area 476 m² / g, mesopore specific surface area 184 m² / g; total pore volume 0.638 cm³ / g, of which micropore pore volume 0.243 cm³ / g, mesopore pore volume 0.395 cm³ / g.

[0068] The acid properties are as follows: the total acid density is 0.151 mmol / g; among which, the density of strong Brønsted acid centers is 0.064 mmol / g, and the density of Lewis acid centers is 0.060 mmol / g (the density of strong Lewis acid centers is 0.030 mmol / g); the acid center strength is 0.42.

[0069] See Figure 2 XRD tests were performed on catalysts C-1 to C-3 prepared in Examples 1-3 for the synthesis of lubricating oil base oils. Comparative results showed that all three catalysts exhibited sharp and strong diffraction peaks at approximately 15.6°, 18.6°, 20.3°, 23.6°, 27.0°, 30.6°, 31.3°, and 34.0°, characteristic diffraction peaks of FAU-type zeolites. This confirms that the obtained catalysts are all FAU-type zeolites with high crystallinity and pure crystal phase. Furthermore, compared with conventional FAU zeolites, the characteristic peaks of all three catalysts showed a systematic shift towards higher angles (peak position shifted to the right). This directly confirms the shrinkage of the zeolite framework unit cell, which is key structural evidence of successful dealumination and silicon supplementation modification and a significant increase in the framework silicon-aluminum ratio.

[0070] See Figure 3 SEM images of catalysts C-1 to C-3 prepared for the synthesis of lubricating oil base oils in the above embodiments show that the catalysts of the present invention have regular FAU crystal morphology. Furthermore, through a unique modification process, abundant mesoscopic structures (rough surfaces, secondary pores) were successfully introduced into the crystals, thus achieving the construction of a multi-level "micropore-mesopore" pore structure. This provides channels for the rapid diffusion of reactant and product molecules and is one of the key structural factors for achieving "process enhancement" (significantly shortening reaction time) in the catalyst. The morphological differences under different conditions also demonstrate the controllability of process parameters on the final catalyst structure.

[0071] Example 4 Under a nitrogen inert atmosphere, 77.59 g of n-dodecane and 25.00 g of naphthalene were added sequentially to a 500 mL high-pressure reactor. After sealing the reactor, stirring was started and the temperature was raised to 115 °C to completely melt the naphthalene and mix it uniformly with the solvent. Then, 3.55 g of catalyst C-1 prepared in Example 1 was added to the system. The temperature was continued to rise and the system pressure was adjusted to 2.0 atm. Then, 87.55 g of 1-octene was slowly pumped into the reaction system at a controlled rate using a metering pump. After the addition was complete, the reaction was continued at 115 °C and 2.0 atm for 0.8 h. After the reaction was completed, the material was subjected to vacuum distillation to remove unreacted olefins, naphthalene, and n-dodecane solvent. The crude product was centrifuged to recover the solid catalyst, yielding a transparent golden-yellow alkylnaphthalene product. Analysis showed that the naphthalene conversion rate was 95.5%, the alkylnaphthalene selectivity was 99.9%, and the yield was 95.4%. GC-MS and ¹H NMR characterization results showed that the product was a polyoctyl-substituted naphthalene, in which the ratio of dialkylnaphthalene, trialkylnaphthalene and tetraalkylnaphthalene was 1.4:29.5:69.1.

[0072] Example 5 Under nitrogen protection, 66.77 g of n-dodecane and 25.00 g of naphthalene were added to a 500 mL high-pressure reactor. After sealing, the mixture was stirred and heated to 120 °C to melt the naphthalene. 5.60 g of catalyst C-1 was added, and the system pressure was adjusted to 2.3 atm. Subsequently, 85.92 g of 1-decene was slowly pumped in using a metering pump, controlling the dropping rate to maintain stable temperature and pressure. After the addition was complete, the reaction was carried out at 120 °C and 2.3 atm for 0.5 h. The reactants were subjected to vacuum distillation to remove volatiles, and the catalyst was separated by centrifugation to obtain a transparent golden-yellow product. The naphthalene conversion was 97.5%, the alkylnaphthalene selectivity was 99.9%, and the yield was 97.3%. The product composition was identified as polydecyl-substituted naphthalene, with a dialkylnaphthalene, trialkylnaphthalene, and tetraalkylnaphthalene ratio of 33.5:44.9:21.6.

[0073] Example 6 Under a nitrogen atmosphere, 76.94 g of n-dodecane and 25.00 g of naphthalene were added to a 500 mL high-pressure reactor. The reactor was sealed and heated to 110 °C to dissolve the naphthalene. 5.50 g of catalyst C-1 was added, and the system pressure was adjusted to 2.3 atm. Then, 95.31 g of 1-dodecene was slowly pumped into the reaction system using a metering pump. After the addition was complete, the reaction was carried out at 110 °C and 2.3 atm for 1.0 h. After the reaction was complete, the product was separated by vacuum distillation and centrifugation to obtain a transparent golden-yellow final product. The naphthalene conversion rate was 96.5%, the alkylnaphthalene selectivity was 99.9%, and the yield was 96.4%. GC-MS and ¹H NMR analysis showed that the product was polydodecyl-substituted naphthalene, with a dialkylnaphthalene, trialkylnaphthalene, and tetraalkylnaphthalene ratio of 28.9:54.2:16.9.

[0074] Example 7 Unlike Example 1, the aluminum source was a mixture of sodium aluminate and aluminum sulfate, the silicon source was silica, the organic structural template agent was tetraethylammonium hydroxide, the buffer solution was diammonium hydrogen phosphate with a concentration of 0.05 mol / L, and the concentration of ammonium chloride aqueous solution used for ammonium exchange and secondary ammonium exchange was 0.5 mol / L.

[0075] Example 8 Unlike Example 1, the aluminum source is a mixture of boehmite, alumina, and aluminum nitrate; the silicon source is tetraethyl orthosilicate; the organic structural template agent is tetrabutylammonium hydroxide; the molar ratio of silicon source, alkali source, water, and organic structural template agent in the gel mixture is 10:1:5:300:0.05; the mass of the directing agent solution accounts for 20% of the total mass of the gel mixture; the buffer solution is ammonium oxalate with a concentration of 0.5 mol / L; and the concentration of ammonium chloride aqueous solution used for ammonium exchange and secondary ammonium exchange is 1 mol / L.

[0076] Example 9 Unlike Example 1, the aluminum source is aluminum isopropoxide, the silicon source is tetraethyl orthosilicate, the organic structural template agent is tetraethylammonium hydroxide, and the molar ratio of silicon source, alkali source, water and organic structural template agent in the gel mixture is 20:1:25:450:0.8. The mass of the directing agent solution accounts for 25% of the total mass of the gel mixture. The buffer solution is ammonium oxalate with a concentration of 1 mol / L, and the concentration of ammonium chloride aqueous solution used for ammonium exchange and secondary ammonium exchange is 0.3 mol / L.

[0077] Example 10 Take 5.00 g of catalyst C-1 prepared according to the method of Example 1, place it in a high-pressure reactor, and carry out the alkylation reaction of naphthalene and 1-octene under nitrogen atmosphere protection according to the reaction conditions described in Application Example 4 (i.e., 115°C, 2.0 atm pressure, n-dodecane as solvent, naphthalene and 1-octene as reactants, and the mass ratio of naphthalene to catalyst as in Example 4). The single reaction time is 1 h.

[0078] After the reaction was completed, the solid catalyst was recovered by centrifugation and washed three times with n-hexane solvent to completely remove the organic matter adsorbed on the surface. Then it was dried at 110°C for 2 hours to obtain the regenerated catalyst.

[0079] The dried catalyst was transferred to a muffle furnace and regenerated at 600°C for 2 hours under a 100% steam atmosphere. The regenerated catalyst was then directly used for the next alkylation reaction test. This cycle was repeated five times before the naphthalene conversion was tested. The results are shown in the table below.

[0080] As can be seen, the catalyst C-1 prepared in this invention for the synthesis of lubricating oil base oil, after undergoing five consecutive alkylation reactions and four harsh regenerations at 100% steam and 600°C, still maintains a naphthalene conversion rate of 90.7% in the fifth cycle, and the alkylnaphthalene selectivity remains above 99.6%. Experiments show that after five regenerations, the catalyst's catalytic activity and selectivity remain at a high level, and the key properties of the synthesized lubricating oil base oil show no significant degradation, greatly reducing catalyst consumption and operating costs in industrial applications. This result undeniably proves that the catalyst prepared in this invention has a much higher resistance to carbon buildup and deactivation and a longer overall service life than conventional catalysts, meeting the stringent durability requirements of industrial applications. The deactivated catalyst does not require complex treatment processes; efficient regeneration can be achieved simply through hydrothermal calcination.

[0081] Comparative Example 1 Under a nitrogen inert atmosphere, 77.59 g of n-dodecane and 25.00 g of naphthalene were added sequentially to a 500 mL high-pressure reactor. After sealing the reactor, stirring was started and the temperature was raised to 115 °C to completely melt the naphthalene and mix it evenly with the solvent. Then, 3.55 g of conventionally hydrothermally superheated USY zeolite was added to the system. The temperature was further increased and the system pressure was adjusted to 2.0 atm. Then, 87.55 g of 1-octene was slowly pumped into the reaction system at a controlled rate using a metering pump. After the addition was complete, the reaction was continued at 115 °C and 2.0 atm for 4 hours. After the reaction was completed, the material was subjected to vacuum distillation to remove unreacted olefins, naphthalene, and n-dodecane solvent. The crude product was centrifuged to recover the solid catalyst, yielding a transparent golden-yellow alkylnaphthalene product. Analysis showed that the naphthalene conversion was only 44.94%, the alkylnaphthalene selectivity was 91.18%, and the yield was 40.98%.

[0082] Under the same reaction conditions of 115℃ and 2.0 atm, the catalyst (C-1) prepared in this invention for the synthesis of lubricating oil base oils can achieve a naphthalene conversion rate of 95.5% within 0.8 h, while the conventional USY zeolite used in Comparative Example 1 only achieved a conversion rate of 22.5% in the same time, and even when the reaction time was extended to 4 h, its conversion rate was only 44.9%. This data fully demonstrates that the catalyst prepared in this invention for the synthesis of lubricating oil base oils can significantly shorten the reaction time of 4-6 h required by the traditional process to 0.5-1 h, achieving true process intensification. The structural basis for this ultra-high reaction efficiency lies in the fact that, as characterized in Examples 1-4, the catalyst possesses high crystallinity (≥87%), interconnected hierarchical channels (mesoporous pore volume ratio ≥45%), and an optimized acidity distribution dominated by strong Brønsted acids (density ≥0.085 mmol / g). The synergistic effect of these three factors ensures efficient mass transfer between reactants and products and high intrinsic catalytic activity.

[0083] Comparative Example 2 Comparative Example 2 is a commercially available alkylnaphthalene base oil with a kinematic viscosity of 141.1 cst at 40°C, a kinematic viscosity of 15.2 cst at 100°C, a viscosity index of 110, a pour point of -39°C, a flash point of 264°C, a water content of <50 ppm, and a total acid value of <50 ppm.

[0084] The properties of the lubricating oil base oils prepared in Examples 4-6 and Comparative Example 2 are shown in the table below:

[0085] As can be seen from the table above, the lubricating oil base oil prepared in the embodiments of the present invention has similar properties to the commercially available alkyl naphthalene base oil in Comparative Example 1. The alkyl naphthalene product of the present invention has properties such as high thermal and oxygen stability, high flash point, high viscosity, and low friction.

[0086] Therefore, the catalyst is environmentally friendly and the process is green: the FAU zeolite catalyst prepared by this invention is an all-solid-state acidic catalyst, which fundamentally avoids the use of traditional liquid acids (such as hydrofluoric acid, sulfuric acid, and aluminum trichloride), and completely solves the problems of equipment corrosion, waste acid treatment and environmental pollution. It is a clean alkylation technology that conforms to the development direction of green chemical industry.

[0087] This invention utilizes a modification process of "guided synthesis – deep dealumination and silicon replenishment – ​​weak alkali treatment" to form a cohesive and synergistic whole. The guided synthesis step, by controlling the initial crystallization, yields a small-grained FAU zeolite precursor rich in rudimentary hierarchical pores, providing an ideal structural foundation for subsequent modification. Building upon this foundation, the deep dealumination and silicon replenishment step, through atomic-level framework reconstruction, significantly improves the zeolite's framework silicon-to-aluminum ratio, thereby enhancing its hydrothermal stability and optimizing its acid properties to a "high-strength acid, low-total-acid" distribution, effectively suppressing carbon deposition. Furthermore, it creates abundant mesopores within the crystal, which, together with rudimentary pores, construct a continuous hierarchical pore system, greatly promoting the diffusion and mass transfer of reactants and products. The subsequent weak alkali treatment step serves to refine and optimize the process, removing amorphous fragments generated during dealumination and silicon replenishment, clearing and further optimizing the connectivity of the mesoporous structure, ensuring the high efficiency and stability of the hierarchical pores. This results in an excellent structure and performance of the final catalyst, which can shorten the traditional alkylation reaction, which takes several hours, to 0.5-1 hour when applied to the synthesis of lubricating oil base oils. It also has high catalytic activity, high selectivity, excellent hydrothermal stability and anti-carbon deposit ability.

[0088] The alkylnaphthalene products synthesized based on this catalyst are mainly high-performance alkylnaphthalenes. As a Group V high-performance lubricating oil base oil, this product exhibits excellent thermal oxidation stability, high flash point, high viscosity index, excellent viscosity-temperature properties, and low friction characteristics, meeting the growing market demand for high-end lubricating oil base oils.

[0089] In summary, this invention has achieved breakthroughs in catalyst design, preparation process, reaction process, and final product performance, providing an efficient, green, and economical synthesis route for high-quality lubricating oil base oils, with significant industrial application value.

[0090] The above description is merely a preferred embodiment of the present invention and is not intended to limit the technical solution of the present invention in any way. Those skilled in the art should understand that, without departing from the spirit and principles of the present invention, the technical solution can be modified and replaced in several simple ways, and these modifications and replacements are all within the scope of protection covered by the claims.

Claims

1. A method for preparing a catalyst for the synthesis of lubricating oil base oil, characterized in that, include: FAU zeolite was subjected to ammonium exchange to obtain NH4Y zeolite; After the NH4Y zeolite was subjected to dealuminization and silicon replenishment treatment, it was subjected to weak alkali treatment and secondary ammonium exchange to obtain the modified zeolite. The modified zeolite was calcined and activated to obtain a catalyst for the synthesis of lubricating oil base oil.

2. The method for preparing the catalyst for the synthesis of lubricating oil base oil according to claim 1, characterized in that, The preparation method of the FAU zeolite is as follows: A directing agent solution was prepared using an alkali source, an aluminum source, a silicon source, and water. The first composition was prepared using a silicon source, an alkaline source, an organic structural template agent, and water. A second composition was prepared using an aluminum source and water; The first composition is added to the directing agent solution and mixed evenly to obtain the third composition; The second composition is added dropwise to the third composition, mixed thoroughly, and aged to obtain a gel mixture; After dynamic aging of the gel mixture, it is first dynamically crystallized and then statically crystallized until the solid and liquid phases are separated. The separated solid phase is then dried and calcined to obtain FAU zeolite.

3. The method for preparing the catalyst for the synthesis of lubricating oil base oil according to claim 2, characterized in that, The molar ratio of alkali source, aluminum source, silicon source and water in the directing agent solution is (5-30):1:(5-35):(250-450); the molar ratio of silicon source, aluminum source, alkali source, water and organic structural template agent in the gel mixture is (10-20):1:(5-25):(300-450):(0.05-0.8); the mass of the directing agent solution accounts for 20%-30% of the total mass of the gel mixture.

4. The method for preparing the catalyst for the synthesis of lubricating oil base oil according to claim 2, characterized in that, The aluminum source is selected from one or more of sodium aluminate, aluminum sulfate, aluminum isopropoxide, aluminum hydroxide, boehmite, aluminum oxide, and aluminum nitrate. The silicon source is selected from one or more of silica, silica sol, solid silica gel, tetraethyl orthosilicate, and water glass; The organic structural template agent is selected from one or more of tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, tetrapentylammonium hydroxide, tetrahexylammonium hydroxide, tetrapropylammonium bromide, and tetrabutylammonium chloride; The alkali source is Na2O.

5. The method for preparing the catalyst for the synthesis of lubricating oil base oil according to claim 1, characterized in that, The method for obtaining NH4Y zeolite by ammonium exchange of FAU zeolite is as follows: FAU zeolite was repeatedly subjected to ammonium exchange with an aqueous solution of 0.5-1.5 mol / L ammonium chloride until the mass fraction of sodium ions in FAU zeolite was reduced to below 0.05%, thus obtaining NH4Y zeolite.

6. The method for preparing the catalyst for the synthesis of lubricating oil base oil according to claim 1, characterized in that, The method for obtaining modified zeolite by subjecting NH4Y zeolite to dealuminization and silicon replenishment treatment, followed by weak alkali treatment and secondary ammonium exchange is as follows: NH4Y zeolite is dispersed in a buffer solution. At 50-95℃, an ammonium fluorosilicate solution with a concentration of 0.01-1.5 mol / L is added dropwise at a rate of 1-10 mL / min, with a mass ratio of ammonium fluorosilicate to NH4Y zeolite of (0.05-0.5):

1. The reaction is allowed to proceed for 0.5-4 h. The mixture is then sequentially filtered, washed, and dried to complete the dealuminization and silicon replenishment treatment. The buffer solution is an aqueous solution of one or more combinations of ammonium oxalate, ammonium citrate, ammonium acetate, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, ammonium carbonate, and a buffer solution composed of ammonia and ammonium chloride, with a concentration of 0.05-1.0 mol / L. After the NH4Y zeolite underwent dealuminization and silicon replenishment treatment, it was treated with a weak alkaline solution with a concentration of 0.01-3.0 mol / L, filtered, washed until neutral, and dried to obtain a solid material; the weak alkaline solution was ammonia water, ammonium carbonate, or ammonium bicarbonate solution. The solid material was subjected to a second ammonium exchange process with a 0.5-1.5 mol / L ammonium chloride aqueous solution at 95-110℃ until the sodium ion mass fraction was below 0.05%, thus obtaining the modified zeolite.

7. The method for preparing the catalyst for the synthesis of lubricating oil base oil according to claim 1, characterized in that, The calcination activation treatment is carried out at a temperature of 350-900℃ for 2-6 hours.

8. A catalyst for the synthesis of lubricating oil base oils, characterized in that, Prepared using the method for preparing the catalyst for the synthesis of lubricating oil base oil according to any one of claims 1-7.

9. The application of the catalyst for the synthesis of lubricating oil base oil according to claim 8 in the preparation of alkylnaphthalene base oil, characterized in that, include: Solid naphthalene is added to an organic solvent, and the temperature is raised to melt the solid naphthalene and mix it evenly with the organic solvent to obtain a naphthalene-containing reaction system. A catalyst used for the synthesis of lubricating oil base oil is added to a naphthalene-containing reaction system. After the temperature is raised to the target reaction temperature, α-olefins are added to carry out an alkylation reaction to obtain alkylnaphthalene base oil.

10. The application of the catalyst for the synthesis of lubricating oil base oil according to claim 9 in the preparation of alkylnaphthalene base oil, characterized in that, The organic solvent is one or a mixture of C12-C14 n-alkanes; the α-olefin is one or a mixture of C6-C14 medium-long chain α-olefins; the molar ratio of solid naphthalene to α-olefin is 1:(0.5-2.5); the mass ratio of the sum of the masses of solid naphthalene and α-olefin to the mass of the organic solvent is (1-2):1; the mass ratio of naphthalene to the catalyst used for the synthesis of lubricating oil base oil is 1:(0.05-0.15); the target reaction temperature is 60-165℃, and the alkylation reaction time is 0.5-1h.

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