Method for preparing alkylated naphthalene by using metal organic framework as catalyst and use thereof

Abstract

The present invention provides a method for preparing an alkylated naphthalene by using a metal organic framework as a catalyst and the use thereof. The method comprises the following steps: subjecting an α-olefin and naphthalene and / or methylnaphthalene to an alkylation reaction in the presence of a metal organic framework catalyst, so as to obtain an alkylated naphthalene. The present invention further provides an alkylated naphthalene obtained by means of the method for preparing an alkylated naphthalene by using a metal organic framework as a catalyst, and the use of the alkylated naphthalene as a group-V lubricant base oil. In the present invention, the MOF catalyst is used to prepare an alkylated naphthalene; and the catalyst has a large pore channel, and during the preparation process of an alkylated naphthalene, the catalyst has a high catalytic activity, long service life and no pollution, and is not prone to corroding equipment.

Description

A method for preparing alkylnaphthalene using metal organic framework as catalyst and its application Technical Field

[0001] The invention relates to a method for preparing alkyl naphthalene by using a metal organic framework as a catalyst and application thereof, belonging to the technical field of alkyl naphthalene base oil. Background Art

[0002] Alkylated naphthalene base oils (ANs) are alkylated aromatic hydrocarbons produced by introducing alkyl groups onto the naphthalene ring through an alkylation process using long-chain alpha olefins (C8-C20) and naphthalene as raw materials. They are a type of Group V lubricant base oil. Currently, ANs are used as base oils in hydraulic fluids, gear oils, heat transfer oils, compressor oils, and other applications. They are primarily used as high-efficiency blending components in high-end Group II, III, and IV base oils. They can significantly improve the oil's heat resistance, thermal and oxidative stability, solubility, dispersibility, additive sensitivity, rubber compatibility, volatility, and hydrolytic stability, thereby extending the service life of these high-end lubricants. As machinery and equipment evolve towards heavier loads and higher speeds, demand for ANs with excellent thermal and oxidative stability is increasing, and global supply is exceeding demand. Therefore, the production of ANs is crucial to the development of the lubricant industry.

[0003] Currently, the industry primarily uses liquid acids (concentrated sulfuric acid, hydrofluoric acid, trifluoromethanesulfonic acid, etc.) and solid acids (AlCl3, molecular sieves, etc.) as catalysts for the production of alkyl naphthalenes. Concentrated sulfuric acid and hydrofluoric acid are already well-established in industrial applications. However, these technologies present challenges such as equipment corrosion, environmental pollution, and catalyst deactivation. Therefore, developing a catalyst that is resistant to equipment corrosion, environmentally friendly, and has a long lifespan is crucial to this technology.

[0004] CN113388430A discloses a method for preparing alkylnaphthalene from mixed olefins. The method comprises the following steps: mixing a mixed α-olefin and naphthalene, adding a solid acid catalyst and a solvent, and subjecting the mixture to a high-temperature reaction to obtain the product. This method, using a solid acid catalyst, addresses the problem in the prior art where alkylnaphthalene produced from mixed olefins struggles to match the performance of alkylnaphthalene produced from single-carbon olefins. It also addresses the prior art issues of liquid catalysts corroding equipment, being environmentally unfriendly, and the high cost of the raw olefins. However, over extended use of the solid acid catalyst, polymers can clog the catalyst pores, leading to catalyst deactivation.

[0005] CN109824467A discloses a method for preparing polyalkylnaphthalene using ionic liquid catalysis. The method comprises the following steps: (1) preparing an ionic liquid catalyst having a calculated acidity of X; (2) adding naphthalene to the ionic liquid catalyst prepared in step (1) at a molar ratio of naphthalene to olefin of 1:1-1:10, and then slowly adding the olefin to the mixture dropwise; (3) after the reaction, cooling the mixture to room temperature and separating the layers. The upper liquid product is washed with water to remove a small amount of ionic liquid, and then the inert organic solvent and residual naphthalene are removed by vacuum distillation. The liquid in the flask is then extracted multiple times to obtain the polyalkylnaphthalene product. The reaction system in this method is a mixture of naphthalene, medium- and long-chain α-olefins, and the ionic liquid catalyst. This method overcomes the shortcomings of conventional alkylation catalysts, such as environmental pollution, high toxicity, and high corrosiveness. However, due to the complex preparation process and high cost of the ionic liquid catalyst, it is not suitable for industrial production.

[0006] CN114507110A discloses a method for producing alkylnaphthalenes. This method uses trifluoromethanesulfonic acid and / or methanesulfonic acid as catalysts, naphthalene and olefins as raw materials, and the naphthalene, olefins, and catalysts are mixed and reacted to produce alkylnaphthalenes. This method addresses issues such as a short catalyst life and difficult post-processing. However, the use of trifluoromethanesulfonic acid and / or methanesulfonic acid as catalysts can corrode equipment, which is not environmentally friendly.

[0007] CN104817419A discloses a method for preparing alkylnaphthalene and its application. The method comprises the following steps: alkylating naphthalene, α-methylnaphthalene, or a mixture of naphthalene and α-methylnaphthalene with a C4-C22 α-olefin in the presence of a gallium trifluoromethanesulfonate catalyst to produce an alkylnaphthalene product. The product alkylnaphthalene contains one or more identical or different C4-C22 alkyl substituents. The catalyst used in this method is susceptible to equipment corrosion, resulting in significant environmental pollution.

[0008] In summary, existing alkylnaphthalene synthesis methods have disadvantages such as catalyst corrosion, environmental pollution, complex catalyst preparation process, and short catalyst life. Therefore, developing a new method for preparing alkylnaphthalene remains one of the urgent problems to be solved in the field.

[0009] Summary of the Invention

[0010] To address the above technical problems, the present invention provides a method for preparing alkylnaphthalene using a metal-organic framework (MOF) catalyst and its application. The present invention utilizes a MOF catalyst with large pores to prepare alkylnaphthalene. During the alkylnaphthalene production process, the catalyst exhibits high catalytic activity, a long lifespan, is pollution-free, and is less prone to corrosion.

[0011] In order to achieve the above object, the first aspect of the present invention provides a method for preparing alkylnaphthalene using a metal organic framework as a catalyst, which comprises the following steps:

[0012] In the presence of a metal organic framework (MOFs) catalyst, α-olefin and naphthalene and / or methylnaphthalene are subjected to an alkylation reaction to obtain the alkylnaphthalene;

[0013] The metal-organic framework catalyst is prepared by at least the following steps: mixing an inorganic metal salt and an organic ligand in a first solvent to obtain a mixed liquid, wherein the inorganic metal salt includes one or a combination of chromium salts, zirconium salts and aluminum salts; reacting the mixed liquid for a first time under a first temperature condition to obtain a reaction product; and subjecting the reaction product to solid-liquid separation, washing and drying to obtain the metal-organic framework catalyst.

[0014] According to some embodiments of the present invention, the alkylation reaction is carried out in the presence of a solvent. Preferably, the solvent comprises one or a combination of C6-C14 normal alkanes. The amount of the solvent used can be adjusted by a person skilled in the art.

[0015] According to some specific embodiments of the present invention, preferably, the α-olefin includes one or a combination of C8-C20 long-chain α-olefins.

[0016] According to some specific embodiments of the present invention, the methylnaphthalene may include α-methylnaphthalene and / or β-methylnaphthalene.

[0017] According to some specific embodiments of the present invention, preferably, the molar ratio of naphthalene and / or methylnaphthalene:α-olefin is (0.5-5):1.

[0018] According to some specific embodiments of the present invention, preferably, the mass ratio of the metal organic framework catalyst: α-olefin and naphthalene and / or methylnaphthalene is (0.01-0.1):1.

[0019] According to some specific embodiments of the present invention, preferably, the alkylation reaction temperature is 80-150° C., the pressure is normal pressure, and the time is 0.5-24 h.

[0020] According to some specific embodiments of the present invention, preferably, the above method further comprises the following steps: after the alkylation reaction is completed, washing the reaction mixture to remove the catalyst, then decolorizing it, and then distilling it under reduced pressure to obtain the alkyl naphthalene.

[0021] In some specific embodiments of the present invention, the decolorization treatment may include: mixing a decolorizing agent with the washed product, decolorizing the product, and obtaining a decolorized product after filtration or suction filtration. Preferably, the decolorizing agent includes activated carbon and / or activated clay. The mixing ratio of the decolorizing agent to the washed product can be conventionally adjusted by those skilled in the art. For example, the amount of the decolorizing agent can be 0.1%-0.5% of the mass of the washed product. The decolorization process can be carried out under stirring conditions, the temperature can be 60-100°C, and the stirring time can be 0.5-2 hours.

[0022] In some specific embodiments of the present invention, the temperature of the reduced pressure distillation is 70° C.-200° C., and the pressure is -99 kPa to 0 kPa.

[0023] According to some specific embodiments of the present invention, preferably, in the step of preparing the metal organic framework catalyst, the chromium salt includes one or a combination of chromium nitrate, chromium sulfate and chromium chloride.

[0024] According to some specific embodiments of the present invention, preferably, in the step of preparing the metal organic framework catalyst, the zirconium salt includes one or a combination of zirconium nitrate, zirconium sulfate and zirconium chloride.

[0025] According to some specific embodiments of the present invention, preferably, in the step of preparing the metal organic framework catalyst, the aluminum salt includes one or a combination of aluminum nitrate, aluminum sulfate and aluminum chloride.

[0026] According to some specific embodiments of the present invention, preferably, the inorganic metal salt includes a chromium salt and a zirconium salt, or a zirconium salt and an aluminum salt, or a chromium salt and an aluminum salt, or a chromium salt, a zirconium salt and an aluminum salt. When a combination of a chromium salt and a zirconium salt is used, the molar ratio of the chromium salt to the zirconium salt may be 1:(0.5-2), preferably 1:1. When a combination of a zirconium salt and an aluminum salt is used, the molar ratio of the zirconium salt to the aluminum salt may be 1:(0.5-2), preferably 1:1. When a combination of a chromium salt and an aluminum salt is used, the molar ratio of the chromium salt to the aluminum salt may be 1:(0.5-2), preferably 1:1. When a combination of a chromium salt, a zirconium salt and an aluminum salt is used, the molar ratio of the chromium salt, the zirconium salt and the aluminum salt may be 1:(0.5-2):(0.5-2), preferably 1:1:1.

[0027] According to some specific embodiments of the present invention, preferably, in the step of preparing the metal organic framework catalyst, the organic ligand includes terephthalic acid.

[0028] According to some specific embodiments of the present invention, preferably, in the step of preparing the metal organic framework catalyst, the molar ratio of the organic ligand to the metal in the inorganic metal salt is 1:(0.5-4).

[0029] According to some specific embodiments of the present invention, preferably, in the step of preparing the metal organic framework catalyst, the first solvent comprises N,N-dimethylformamide. The amount of the first solvent can be conventionally adjusted by those skilled in the art.

[0030] According to some specific embodiments of the present invention, preferably, in the step of preparing the metal-organic framework catalyst, the mixed solution is obtained by mixing an inorganic metal salt and an organic ligand in a first solvent and dissolving them by ultrasonication. The power, frequency, and duration of the ultrasonic wave can be conventionally adjusted by a person skilled in the art.

[0031] According to some specific embodiments of the present invention, preferably, in the step of preparing the metal organic framework catalyst, the first temperature is 80-150° C., and the first time is 12-72 hours.

[0032] In some specific embodiments of the present invention, in the preparation step of the metal organic framework catalyst, the solid-liquid separation, washing and drying of the reaction product can be carried out according to conventional methods in the art, and the present invention does not specifically limit them.

[0033] According to some specific embodiments of the present invention, preferably, the specific surface area of ​​the metal organic framework catalyst is 1000-2000m 2 / gThe average pore size is 0.5-1.5nm.

[0034] According to some specific embodiments of the present invention, preferably, the pore volume of the metal organic framework catalyst is 0.5-2 cm 2 / g. The second aspect of the present invention provides alkyl naphthalene prepared by the above-mentioned method for preparing alkyl naphthalene using a metal organic framework as a catalyst.

[0035] The third aspect of the present invention provides the use of the above-mentioned alkyl naphthalene as a Group V lubricant base oil.

[0036] According to some specific embodiments of the present invention, the 100°C kinematic viscosity of the alkyl naphthalene prepared by the method of the present invention is 4-41 mm 2 / s, kinematic viscosity at 40℃ is 10-500mm 2 / s, a viscosity index of 70-130, a pour point of -20°C to -60°C, and a flash point of 180°C-250°C, all of which meet the requirements for lubricant base oils in this field and can be directly used as Class V lubricant base oils.

[0037] Currently, the catalysts used in the industrial synthesis of alkyl naphthalenes typically use liquid acid catalysts (concentrated sulfuric acid, hydrofluoric acid, trifluoromethanesulfonic acid, etc.) and traditional solid acid catalysts (AlCl3, molecular sieves, etc.). However, traditional liquid acid catalysts have problems such as corrosion of equipment and environmental pollution. Acidic ionic liquid catalysts are a new type of liquid acid catalyst for the synthesis of alkyl naphthalene, but they still have disadvantages such as complex production processes, corrosion of equipment, and environmental pollution. Although solid acid catalysts can overcome these problems, due to the small pores of solid acids, the catalyst pores are easily clogged during long-term operation, leading to catalyst deactivation.

[0038] The technical solution of the present invention has at least the following beneficial effects:

[0039] (1) The metal organic framework (MOFs) catalyst synthesized in the present invention has large pores and is not easily deactivated due to pore blockage during long-term operation. Therefore, the catalyst of the present invention has a long lifespan, which can reach more than 100 hours.

[0040] (2) The present invention uses a metal organic framework catalyst to catalyze the alkylation reaction of long-chain α-olefins with naphthalene and / or methylnaphthalene, and has high catalytic activity. Under mild reaction conditions, the conversion rate of naphthalene and / or methylnaphthalene is higher than 98%.

[0041] (3) The metal organic framework catalyst of the present invention is not easy to corrode equipment and will not pollute the environment.

[0042] In summary, the present invention provides a method for preparing alkylnaphthalene using a metal-organic framework as a catalyst, alkylnaphthalene, and its applications. The present invention synthesizes MOFs materials via a hydrothermal method, which is simple to synthesize. The resulting acidic MOFs material has a high specific surface area and a large pore size. This invention is the first to use MOFs as catalysts for the preparation of alkylnaphthalene. The MOFs catalyst of the present invention exhibits advantages such as high catalytic activity, long lifespan, pollution-free operation, and resistance to equipment corrosion during the preparation of alkylnaphthalene. This breaks the constraints of existing liquid acid catalysts and solid acid catalysts, addressing the problems of equipment corrosion, environmental pollution, and catalyst deactivation associated with these catalysts. The method provided by the present invention can efficiently catalyze the synthesis of alkylnaphthalene from long-chain α-olefins, with a catalyst lifespan exceeding 100 hours and a naphthalene and / or methylnaphthalene conversion rate exceeding 98%. The present invention broadens the range of catalysts for synthesizing alkylnaphthalene. The catalyst can be widely applied to reactions involving various olefins and naphthalene, exhibiting broad applicability and high industrial application value. The alkyl naphthalene product prepared by the present invention has excellent physical and chemical properties, such as viscosity, flash point, pour point, etc., meets the requirements of the lubricating oil base oil in this field, and can be directly used as Class V lubricating oil base oil. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] FIG1 is an XRD pattern of MOFs catalyst A in Example 1. DETAILED DESCRIPTION

[0044] In order to have a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the technical solution of the present invention is now described in detail below, but it should not be understood as limiting the scope of implementation of the present invention.

[0045] In the following examples and comparative examples, the conversion of naphthalene and / or methylnaphthalene was determined using gas chromatography-mass spectrometry (GC-MS). The kinematic viscosity of the alkylnaphthalene product at 40°C and 100°C was measured according to GB / T 265, the viscosity index was measured according to GB / T 1995, the pour point was measured according to GB / T 3535, and the flash point was measured according to GB / T 3536. The average pore size and specific surface area of ​​the MOF catalyst were measured using a physical adsorption analyzer.

[0046] Example 1

[0047] This embodiment provides a method for preparing alkylnaphthalene using a metal organic framework as a catalyst, which comprises the following steps:

[0048] (1) Preparation of MOFs catalyst A

[0049] 1.60 g Cr(NO3)3·9H2O (0.004 mol) and 0.33 g terephthalic acid (0.002 mol) were dissolved in 40 mL N,N-dimethylformamide, placed in a sealed flask, and completely dissolved by ultrasound to obtain a mixed solution; the mixed solution was transferred to a 50 mL reactor, and the reactor was placed in an electric heated blast drying oven. After reacting at 120°C for 24 hours, a reaction product was obtained; the reaction product was allowed to cool naturally at room temperature, and after solid-liquid separation, the product was repeatedly washed with N,N-dimethylformamide for 3-4 times, and then placed in a drying oven at 80°C for 12 hours to obtain a white solid powder, namely MOFs catalyst A;

[0050] (2) Alkylation of naphthalene using MOFs catalyst A

[0051] 25.63 g of naphthalene and 0.59 g of MOFs catalyst A were added to a three-necked flask equipped with a stirrer and a reflux condenser, and 60 mL of n-decane was added. The three-necked flask was placed in an oil bath for heating with the stirrer turned on. Then, a total of 33.66 g of dodecene was added in small amounts and in multiple times. After the temperature of the reaction system reached 80°C, the reaction was kept at this temperature and stirred for 2 h. After the reaction was completed, heating was stopped.

[0052] The reaction mixture is washed with water to remove the catalyst; then, 0.1% by weight of activated clay is added to the washed product, stirred at 80° C. for 1 hour, and filtered to obtain a decolorized product; the decolorized product is subjected to reduced pressure distillation at 160° C. and -99 kPa to remove the solvent and unreacted raw materials to obtain a long-chain alkyl naphthalene product.

[0053] The average pore size of MOFs catalyst A in this example is 1 nm, and the specific surface area is 1486 m 2 The XRD pattern of the MOFs catalyst A is shown in FIG1 . As can be seen from FIG1 , the target catalyst was prepared in this embodiment.

[0054] The long-chain alkyl naphthalene product of this example was analyzed by GC-MS, and the conversion rate of naphthalene was shown in Table 1. The kinematic viscosity at 100°C, kinematic viscosity at 40°C, viscosity index, pour point, and flash point of the long-chain alkyl naphthalene product of this example are shown in Table 1.

[0055] Example 2

[0056] This embodiment provides a method for preparing alkylnaphthalene using a metal organic framework as a catalyst, which comprises the following steps:

[0057] (1) Preparation of MOFs catalyst B

[0058] 0.43 g Zr(NO3)4·5H2O (0.001 mol) and 0.33 g terephthalic acid (0.002 mol) were dissolved in 40 mL N,N-dimethylformamide, placed in a sealed flask, and the raw materials were completely dissolved by ultrasound to obtain a mixed solution; the mixed solution was transferred to a 50 mL reactor, and the reactor was placed in an electric heated blast drying oven. After reacting at 80°C for 12 hours, a reaction product was obtained; the reaction product was allowed to cool naturally at room temperature, and after solid-liquid separation, the product was repeatedly washed with N,N-dimethylformamide for 3-4 times, and then placed in a drying oven at 80°C for 12 hours to obtain a white solid powder, which is MOFs catalyst B;

[0059] (2) Alkylation of naphthalene using MOFs catalyst B

[0060] 12.81 g of naphthalene and 0.93 g of MOFs catalyst B were added to a three-necked flask equipped with a stirrer and a reflux condenser, and 46 mL of n-decane was added. The three-necked flask was placed in an oil bath for heating with the stirrer turned on. Then, a total of 33.66 g of dodecene was added in small amounts and in multiple times. After the temperature of the reaction system reached 90°C, the reaction was kept at this temperature and stirred for 12 hours. After the reaction was completed, heating was stopped.

[0061] The reaction mixture is washed with water to remove the catalyst; then, 0.1% by weight of activated clay is added to the washed product, stirred at 80° C. for 1 hour, and filtered to obtain a decolorized product; the decolorized product is subjected to reduced pressure distillation at 70° C. and 0 kPa to remove the solvent and unreacted raw materials to obtain a long-chain alkyl naphthalene product.

[0062] The average pore size of MOFs catalyst B in this example is 1.1 nm, and the specific surface area is 1543 m 2 / g.

[0063] The long-chain alkyl naphthalene product of this example was analyzed by GC-MS, and the conversion rate of naphthalene was shown in Table 1. The kinematic viscosity at 100°C, kinematic viscosity at 40°C, viscosity index, pour point, and flash point of the long-chain alkyl naphthalene product of this example are shown in Table 1.

[0064] Example 3

[0065] This embodiment provides a method for preparing alkylnaphthalene using a metal organic framework as a catalyst, which comprises the following steps:

[0066] (1) Preparation of MOFs catalyst C

[0067] 2.99 g Al(NO3)3·9H2O (0.008 mol) and 0.33 g terephthalic acid (0.002 mol) were dissolved in 40 mL N,N-dimethylformamide, placed in a sealed flask, and the raw materials were completely dissolved by ultrasound to obtain a mixed solution; the mixed solution was transferred to a 50 mL reactor, and the reactor was placed in an electric heated blast drying oven. After reacting at 150°C for 72 hours, a reaction product was obtained; the reaction product was allowed to cool naturally at room temperature, and after solid-liquid separation, the product was repeatedly washed with N,N-dimethylformamide for 3-4 times, and then placed in a drying oven at 80°C for 12 hours to obtain a white solid powder, which is MOFs catalyst C;

[0068] (2) Alkylation of naphthalene using MOFs catalyst C

[0069] 51.27 g of naphthalene and 8.49 g of MOFs catalyst C were added to a three-necked flask equipped with a stirrer and a reflux condenser, and 85 mL of n-hexane was added. The three-necked flask was placed in an oil bath for heating with the stirrer turned on. Then, a total of 33.66 g of dodecene was added in small amounts and in multiple times. After the temperature of the reaction system reached 100°C, the reaction was kept at this temperature and stirred for 24 hours. When the reaction was completed, heating was stopped.

[0070] The reaction mixture is washed with water to remove the catalyst; then, 0.1% by weight of activated clay is added to the washed product, stirred at 80° C. for 1 hour, and filtered to obtain a decolorized product; the decolorized product is subjected to reduced pressure distillation at 200° C. and −10 kPa to remove the solvent and unreacted raw materials to obtain a long-chain alkyl naphthalene product.

[0071] The average pore size of MOFs catalyst C in this example is 0.5 nm, and the specific surface area is 1005 m 2 / g.

[0072] The long-chain alkyl naphthalene product of this example was analyzed by GC-MS, and the conversion rate of naphthalene was shown in Table 1. The kinematic viscosity at 100°C, kinematic viscosity at 40°C, viscosity index, pour point, and flash point of the long-chain alkyl naphthalene product of this example are shown in Table 1.

[0073] Example 4

[0074] This embodiment provides a method for preparing alkylnaphthalene using a metal organic framework as a catalyst, which comprises the following steps:

[0075] (1) Preparation of MOFs catalyst D

[0076] 4.29 g Zr(NO3)4·5H2O (0.01 mol) and 0.66 g terephthalic acid (0.004 mol) were dissolved in 40 mL N,N-dimethylformamide, placed in a sealed flask, and completely dissolved by ultrasound to obtain a mixed solution; the mixed solution was transferred to a 50 mL reactor, and the reactor was placed in an electric blast drying oven. After reacting at 135°C for 30 h, a reaction product was obtained; the reaction product was allowed to cool naturally at room temperature, and after solid-liquid separation, the product was repeatedly washed with N,N-dimethylformamide for 3-4 times, and then placed in a drying oven at 80°C for 12 h to obtain a white solid powder, which is MOFs catalyst D;

[0077] (2) Alkylation of methylnaphthalene using MOFs catalyst D

[0078] 51.27 g of α-methylnaphthalene and 4.24 g of MOFs catalyst D were added to a three-necked flask equipped with a stirrer and a reflux condenser, and 84 mL of tetradecane was added. The three-necked flask was placed in an oil bath for heating with the stirrer turned on. Then, a total of 33.66 g of dodecene was added in small amounts and in multiple times. After the temperature of the reaction system reached 120°C, the reaction was stirred at this temperature for 0.5 h. After the reaction was completed, heating was stopped.

[0079] The reaction mixture is washed with water to remove the catalyst; then, 0.1% by weight of activated clay is added to the washed product, stirred at 80° C. for 1 hour, and filtered to obtain a decolorized product; the decolorized product is subjected to reduced pressure distillation at 120° C. and -50 kPa to remove the solvent and unreacted raw materials to obtain a long-chain alkyl naphthalene product.

[0080] The average pore size of MOFs catalyst D in this example is 0.8 nm, and the specific surface area is 1254 m 2 / g.

[0081] The long-chain alkyl naphthalene product of this example was analyzed by GC-MS, and the conversion rate of α-methylnaphthalene was shown in Table 1 below. The kinematic viscosity at 100°C, kinematic viscosity at 40°C, viscosity index, pour point, and flash point of the long-chain alkyl naphthalene product of this example are shown in Table 1 below.

[0082] Example 5

[0083] This embodiment provides a method for preparing alkylnaphthalene using a metal organic framework as a catalyst, which comprises the following steps:

[0084] (1) Preparation of MOFs catalyst E

[0085] 5.15 g Zr(NO3)4·5H2O (0.012 mol) and 0.66 g terephthalic acid (0.004 mol) were dissolved in 40 mL N,N-dimethylformamide, placed in a sealed flask, and the raw materials were completely dissolved by ultrasound to obtain a mixed solution; the mixed solution was transferred to a 50 mL reactor, and the reactor was placed in an electric heated blast drying oven. After reacting at 100°C for 48 hours, a reaction product was obtained; the reaction product was allowed to cool naturally at room temperature, and after solid-liquid separation, the product was repeatedly washed with N,N-dimethylformamide for 3-4 times, and then placed in a drying oven at 80°C for 12 hours to obtain a white solid powder, which is MOFs catalyst E;

[0086] (2) Alkylation of naphthalene using MOFs catalyst E

[0087] 76.90 g of naphthalene and 6.63 g of MOFs catalyst E were added to a three-necked flask equipped with a stirrer and a reflux condenser, and 110 mL of n-decane was added. The three-necked flask was placed in an oil bath for heating with the stirrer turned on. Then, a total of 33.66 g of dodecene was added in small amounts and in multiple times. After the temperature of the reaction system reached 130°C, the reaction was stirred at constant temperature for 1 hour. After the reaction was completed, heating was stopped;

[0088] The reaction mixture is washed with water to remove the catalyst; then, 0.1% by weight of activated clay is added to the washed product, stirred at 80° C. for 1 hour, and filtered to obtain a decolorized product; the decolorized product is subjected to reduced pressure distillation at 200° C. and 0 kPa to remove the solvent and unreacted raw materials to obtain a long-chain alkyl naphthalene product.

[0089] The average pore size of MOFs catalyst E in this example is 1.5 nm, and the specific surface area is 1958 m 2 / g.

[0090] The long-chain alkyl naphthalene product of this example was analyzed by GC-MS, and the conversion rate of naphthalene was shown in Table 1. The kinematic viscosity at 100°C, kinematic viscosity at 40°C, viscosity index, pour point, and flash point of the long-chain alkyl naphthalene product of this example are shown in Table 1.

[0091] Example 6

[0092] This embodiment provides a method for preparing alkylnaphthalene using a metal organic framework as a catalyst, which comprises the following steps:

[0093] (1) Preparation of MOFs catalyst F

[0094] 0.80 g Cr(NO3)3·9H2O (0.002 mol), 0.86 g Zr(NO3)4·5H2O (0.002 mol) and 0.66 g terephthalic acid (0.004 mol) were dissolved in 40 mL N,N-dimethylformamide, placed in a sealed flask, and the raw materials were completely dissolved by ultrasound to obtain a mixed solution; the mixed solution was transferred to a 50 mL reactor, and the reactor was placed in an electric heated blast drying oven. After reacting at 110°C for 60 h, a reaction product was obtained; the reaction product was allowed to cool naturally at room temperature, and after solid-liquid separation, the product was repeatedly washed with N,N-dimethylformamide for 3-4 times, and then placed in a drying oven at 80°C for 12 h to obtain a white solid powder, namely MOFs catalyst F;

[0095] (2) Alkylation of naphthalene and methylnaphthalene using MOFs catalyst F

[0096] 102.54 g of a mixture of naphthalene and α-methylnaphthalene (the mass ratio of naphthalene to α-methylnaphthalene is 1:1) and 1.36 g of MOFs catalyst F were added to a three-necked flask equipped with a stirrer and a reflux condenser, and 136 mL of n-decane was added. The three-necked flask was placed in an oil bath for heating with the stirrer turned on. Then, 33.66 g of dodecene was added in small amounts and multiple times. After the temperature of the reaction system reached 90° C., the reaction was stirred at constant temperature for 10 h. The reaction was completed and heating was stopped.

[0097] The reaction mixture is washed with water to remove the catalyst; then, 0.1% by weight of activated clay is added to the washed product, stirred at 80° C. for 1 hour, and filtered to obtain a decolorized product; the decolorized product is subjected to reduced pressure distillation at 70° C. and -99 kPa to remove the solvent and unreacted raw materials to obtain a long-chain alkyl naphthalene product.

[0098] The average pore size of the MOFs catalyst F in this example is 1.4 nm, and the specific surface area is 1867 m 2 / g.

[0099] The long-chain alkylnaphthalene product of this example was analyzed by GC-MS, and the conversion rates of naphthalene and α-methylnaphthalene were shown in Table 1 below. The kinematic viscosity at 100°C, kinematic viscosity at 40°C, viscosity index, pour point, and flash point of the long-chain alkylnaphthalene product of this example are shown in Table 1 below.

[0100] Example 7

[0101] This embodiment provides a method for preparing alkylnaphthalene using a metal organic framework as a catalyst, which comprises the following steps:

[0102] (1) Preparation of MOFs catalyst G

[0103] 2.40 g Cr(NO3)3·9H2O (0.006 mol), 2.25 g Al(NO3)3·9H2O (0.006 mol) and 0.66 g terephthalic acid (0.004 mol) were dissolved in 40 mL N,N-dimethylformamide, placed in a sealed flask, and the raw materials were completely dissolved by ultrasound to obtain a mixed solution; the mixed solution was transferred to a 50 mL reactor, and the reactor was placed in an electric blast drying oven. After reacting at 140°C for 40 h, a reaction product was obtained; the reaction product was allowed to cool naturally at room temperature, and after solid-liquid separation, the product was repeatedly washed with N,N-dimethylformamide for 3-4 times, and then placed in a drying oven at 80°C for 12 h to obtain a white solid powder, which is MOFs catalyst G;

[0104] (2) Alkylation of naphthalene using MOFs catalyst G

[0105] 128.17 g of naphthalene and 3.24 g of MOFs catalyst G were added to a three-necked flask equipped with a stirrer and a reflux condenser, and 161 mL of n-decane was added. The three-necked flask was placed in an oil bath for heating with the stirrer turned on. Then, a total of 33.66 g of dodecene was added in small amounts and in multiple times. After the temperature of the reaction system reached 140°C, the reaction was stirred at constant temperature for 0.5 h. After the reaction was completed, heating was stopped.

[0106] The reaction mixture is washed with water to remove the catalyst; then, 0.1% by weight of activated clay is added to the washed product, stirred at 80° C. for 1 hour, and filtered to obtain a decolorized product; the decolorized product is subjected to reduced pressure distillation at 160° C. and -99 kPa to remove the solvent and unreacted raw materials to obtain a long-chain alkyl naphthalene product.

[0107] The average pore size of MOFs catalyst G in this example is 1.2 nm, and the specific surface area is 1652 m 2 / g.

[0108] The long-chain alkyl naphthalene product of this example was analyzed by GC-MS, and the conversion rate of naphthalene was shown in Table 1. The kinematic viscosity at 100°C, kinematic viscosity at 40°C, viscosity index, pour point, and flash point of the long-chain alkyl naphthalene product of this example are shown in Table 1.

[0109] Example 8

[0110] This embodiment provides a method for preparing alkylnaphthalene using a metal organic framework as a catalyst, which comprises the following steps:

[0111] (1) Preparation of MOFs catalyst H

[0112] 1.72 g Zr(NO3)4·5H2O (0.004 mol), 1.50 g Al(NO3)3·9H2O (0.004 mol) and 0.66 g terephthalic acid (0.004 mol) were dissolved in 40 mL N,N-dimethylformamide, placed in a sealed flask, and the raw materials were completely dissolved by ultrasound to obtain a mixed solution; the mixed solution was transferred to a 50 mL reactor, and the reactor was placed in an electric heated blast drying oven. After reacting at 90°C for 15 hours, a reaction product was obtained; the reaction product was naturally cooled at room temperature, and after solid-liquid separation, the product was repeatedly washed with N,N-dimethylformamide for 3-4 times, and then placed in a drying oven at 80°C for 12 hours to obtain a white solid powder, which is MOFs catalyst H;

[0113] (2) Alkylation of naphthalene using MOFs catalyst H

[0114] 25.63 g of naphthalene and 0.53 g of MOFs catalyst H were added to a three-necked flask equipped with a stirrer and a reflux condenser, followed by 53 mL of n-decane. The flask was placed in an oil bath for heating with the stirrer turned on. 28.05 g of 1-decene was then added in small amounts and in multiple doses. After the temperature of the reaction system reached 100°C, the reaction was stirred at this temperature for 2 h. The reaction was then terminated and heating was stopped.

[0115] The reaction mixture is washed with water to remove the catalyst; then, 0.1% by weight of activated clay is added to the washed product, stirred at 80° C. for 1 hour, and filtered to obtain a decolorized product; the decolorized product is subjected to reduced pressure distillation at 160° C. and -99 kPa to remove the solvent and unreacted raw materials to obtain a long-chain alkyl naphthalene product.

[0116] The average pore size of the MOFs catalyst H in this example is 0.7 nm, and the specific surface area is 1152 m 2 / g.

[0117] The long-chain alkyl naphthalene product of this example was analyzed by GC-MS, and the conversion rate of naphthalene was shown in Table 1. The kinematic viscosity at 100°C, kinematic viscosity at 40°C, viscosity index, pour point, and flash point of the long-chain alkyl naphthalene product of this example are shown in Table 1.

[0118] Example 9

[0119] This embodiment provides a method for preparing alkylnaphthalene using a metal organic framework as a catalyst, which comprises the following steps:

[0120] (1) Preparation of MOFs Catalyst I

[0121] 1.60 g Cr(NO3)3·9H2O (0.004 mol), 1.72 g Zr(NO3)4·5H2O (0.004 mol), 1.50 g Al(NO3)3·9H2O (0.004 mol) and 0.66 g terephthalic acid (0.004 mol) were dissolved in 40 mL N,N-dimethylformamide, placed in a sealed flask, and the raw materials were completely dissolved by ultrasound to obtain a mixed solution; the mixed solution was transferred to a 50 mL reactor, and the reactor was placed in an electric heated blast drying oven. After reacting at 140°C for 48 h, a reaction product was obtained; the reaction product was allowed to cool naturally at room temperature, and after solid-liquid separation, the product was repeatedly washed with N,N-dimethylformamide for 3-4 times, and then placed in a drying oven at 80°C for 12 h to obtain a white solid powder, namely MOFs catalyst I;

[0122] (2) Alkylation of naphthalene using MOFs catalyst I

[0123] 51.26 g of naphthalene and 3.97 g of MOFs catalyst I were added to a three-necked flask equipped with a stirrer and a reflux condenser, and 79 mL of n-decane was added. The three-necked flask was placed in an oil bath for heating with the stirrer turned on. Then, 28.05 g of 1-decene was added in small amounts and in multiple times. After the temperature of the reaction system reached 120° C., the reaction was stirred at this temperature for 1 h. After the reaction was completed, heating was stopped.

[0124] The reaction mixture is washed with water to remove the catalyst; then, 0.1% by weight of activated clay is added to the washed product, stirred at 80° C. for 1 hour, and filtered to obtain a decolorized product; the decolorized product is subjected to reduced pressure distillation at 160° C. and -99 kPa to remove the solvent and unreacted raw materials to obtain a long-chain alkyl naphthalene product.

[0125] The average pore size of the MOFs catalyst I in this embodiment is 1 nm, and the specific surface area is 1488 m 2 / g.

[0126] The long-chain alkyl naphthalene product of this example was analyzed by GC-MS, and the conversion rate of naphthalene was shown in Table 1. The kinematic viscosity at 100°C, kinematic viscosity at 40°C, viscosity index, pour point, and flash point of the long-chain alkyl naphthalene product of this example are shown in Table 1.

[0127] Comparative Example 1

[0128] This comparative example provides a method for preparing alkylnaphthalene using an AlCl3 solid acid catalyst, which comprises the following steps:

[0129] 25.63g of naphthalene and 0.59g of AlCl3 were added to a three-necked flask equipped with a stirrer and a reflux condenser, followed by 60mL of n-decane. The flask was placed in an oil bath and heated with a stirrer. 33.66g of dodecene were then added in small amounts and multiple times. After the reaction system reached 80°C, the mixture was stirred at this temperature for 2h. The reaction was then terminated and heating was stopped.

[0130] The reaction mixture is washed with water to remove the catalyst; then, 0.1% by weight of activated clay is added to the washed product, stirred at 80° C. for 1 hour, and filtered to obtain a decolorized product; the decolorized product is subjected to reduced pressure distillation at 160° C. and -99 kPa to remove the solvent and unreacted raw materials to obtain a long-chain alkyl naphthalene product.

[0131] The long-chain alkyl naphthalene product of this comparative example was analyzed by GC-MS, and the conversion rate of naphthalene was shown in Table 1. The kinematic viscosity at 100°C, kinematic viscosity at 40°C, viscosity index, pour point and flash point of the long-chain alkyl naphthalene product of this comparative example are shown in Table 1.

[0132] Table 1

[0133] In summary, the present invention synthesizes MOFs materials by hydrothermal method, which have higher specific surface area and larger pore size. In the preparation process of alkylnaphthalene, the MOFs catalyst of the present invention has the advantages of high catalytic activity, long service life, pollution-free, and non-corrosive equipment. The catalyst life can reach more than 100 hours, and the conversion rate of naphthalene and / or methylnaphthalene is higher than 98%. Simultaneously, the alkylnaphthalene product prepared by the present invention has excellent physical and chemical properties, such as viscosity, flash point, pour point, etc., which meet the requirements of this area for lubricant base oil and can be directly used as Class V lubricant base oil.

Claims

1. A method for preparing alkylnaphthalene using a metal organic framework as a catalyst, comprising the following steps: In the presence of a metal organic framework catalyst, α-olefin and naphthalene and / or methylnaphthalene are subjected to an alkylation reaction to obtain the alkylnaphthalene; The metal organic framework catalyst is prepared by at least the following steps: mixing an inorganic metal salt and an organic ligand in a first solvent to obtain a mixed solution, wherein the inorganic metal salt includes one or a combination of chromium salts, zirconium salts and aluminum salts; reacting the mixed solution for a first time under a first temperature condition to obtain a reaction product; and subjecting the reaction product to solid-liquid separation, washing and drying to obtain the metal organic framework catalyst.

2. The method according to claim 1, wherein: The alkylation reaction is carried out in the presence of a solvent, and the solvent includes one or a combination of several C6-C14 normal alkanes.

3. The method according to claim 1, wherein: The α-olefin includes one or a combination of several C8-C20 long-chain α-olefins.

4. The method according to claim 1, wherein: The molar ratio of naphthalene and / or methylnaphthalene:α-olefin is (0.5-5):

1.

5. The method according to claim 1, wherein: The mass ratio of metal organic framework catalyst: alpha-olefin and naphthalene and / or methylnaphthalene is (0.01-0.1):

1.

6. The method according to claim 1, wherein: The alkylation reaction is carried out at a temperature of 80-150°C, a pressure of normal pressure and a time of 0.5-24h.

7. The method according to claim 1, wherein: The method further comprises the following steps: after the alkylation reaction is completed, washing the reaction mixture to remove the catalyst, then decolorizing it, and then distilling it under reduced pressure to obtain the alkyl naphthalene.

8. The method according to claim 1, wherein: In the step of preparing the metal organic framework catalyst, the chromium salt includes one or a combination of chromium nitrate, chromium sulfate and chromium chloride.

9. The method according to claim 1, wherein: In the step of preparing the metal organic framework catalyst, the zirconium salt includes one or a combination of zirconium nitrate, zirconium sulfate and zirconium chloride.

10. The method according to claim 1, wherein: In the step of preparing the metal organic framework catalyst, the aluminum salt includes one or a combination of aluminum nitrate, aluminum sulfate and aluminum chloride.

11. The method according to claim 1, wherein: In the step of preparing the metal organic framework catalyst, the organic ligand includes terephthalic acid.

12. The method according to claim 1, wherein: In the step of preparing the metal organic framework catalyst, the molar ratio of the organic ligand to the metal in the inorganic metal salt is 1:(0.5-4).

13. The method according to claim 1, wherein: In the step of preparing the metal organic framework catalyst, the first solvent includes N,N-dimethylformamide.

14. The method according to claim 1, wherein: In the step of preparing the metal organic framework catalyst, the first temperature is 80-150° C., and the first time is 12-72 hours.

15. The method according to claim 1, wherein: The specific surface area of ​​the metal organic framework catalyst is 1000-2000m 2 / gThe average pore size is 0.5-1.5nm.

16. The alkyl naphthalene prepared by the method for preparing alkyl naphthalene using a metal organic framework as a catalyst as claimed in claim 1.

17. Use of the alkylnaphthalene according to claim 16 as a Group V lubricant base oil.

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