Lanthanum gallium modified molecular sieve catalyst and preparation method and application thereof

Abstract

The invention relates to a lanthanum gallium modified molecular sieve catalyst and a preparation method and application thereof, and belongs to the technical field of lubricating oil. The preparation method of the lanthanum-gallium modified molecular sieve catalyst comprises the following steps: (1) carrying out ammonium exchange on a mordenite molecular sieve, drying and roasting to obtain a hydrogen-type mordenite molecular sieve; mixing with a lanthanum salt solution for ion exchange, drying and roasting to obtain a lanthanum modified molecular sieve; and finally, mixing with a gallium salt solution for ion exchange, drying and roasting to obtain the lanthanum gallium modified molecular sieve catalyst. The molecular sieve is jointly modified by adopting metal lanthanum and metal gallium, and the introduction of lanthanum and gallium can reduce the content of B acid in the molecular sieve and increase the content of L acid without damaging the skeleton structure of the molecular sieve, so that the carbon deposition inactivation of the reaction and the occurrence of isomerization reaction and olefin polymerization reaction can be effectively inhibited; the selectivity of a target product is improved; the service life of the catalyst is prolonged.

Description

Technical Field

[0001] The invention belongs to the technical field of lubricating oils, and in particular relates to a lanthanum-gallium modified molecular sieve catalyst and a preparation method and application thereof. Background Art

[0002] Alkyl naphthalene has the advantages of high oxidation stability, high flash point, good thermal stability and high safety. Among them, long-chain alkyl naphthalene has better additive solubility, good anti-emulsification performance and good compatibility. It occupies an important position in synthetic lubricants and is widely used in hydraulic oil, gear oil, heat transfer oil, transformer oil, refrigeration oil, compressor oil, liquid crystal and other fields.

[0003] The preparation of long-chain alkylnaphthalene usually adopts traditional liquid inorganic acids such as trifluoromethanesulfonic acid, concentrated sulfuric acid and hydrofluoric acid or Lewis acids such as aluminum chloride and ferric chloride as catalysts, which has serious corrosion problems on equipment, resulting in difficulty in separating the product from the catalyst or high separation cost, high environmental pressure, and does not meet the requirements of green chemistry. Patent CN101205161A provides a method for preparing long-chain alkylnaphthalene using ultrafine silica-supported heteropolyacid as catalyst under normal pressure. The product obtained by the method has low chromaticity and is easy to separate the catalyst, but the catalyst is prone to coking, the catalyst life is short, and multiple distillations are required to obtain high-viscosity components, which is cumbersome to operate. In addition, ultrafine solid catalysts are not conducive to fixed bed continuous reaction due to excessive bed pressure drop, which is not conducive to industrial production. Patent CN1029611C provides a method for preparing alkylnaphthalene using heteropolyacids or their salts as catalysts. The method is used for the alkylation reaction of C2-C20 olefins and aromatic hydrocarbons, and has a high product yield. However, the reaction requires cyclohexane pretreatment and needs to be carried out in a pressurized closed container. Large-scale industrialization has high costs and safety risks.

[0004] Therefore, the research and development of high-activity solid acid catalysts for the alkylation of long-chain olefins with naphthalene to prepare long-chain alkylnaphthalene is in line with the development concept of green environmental protection, and exploring new catalyst reaction technologies is the focus of current research. Summary of the invention

[0005] The purpose of the present invention is to overcome the problems existing in the above-mentioned prior art and to provide a lanthanum gallium modified molecular sieve catalyst and a preparation method and application thereof.

[0006] The present invention is achieved through the following technical solutions:

[0007] In a first aspect, the present invention provides a method for preparing a lanthanum gallium modified molecular sieve catalyst, comprising the following steps:

[0008] (1) exchanging the mordenite molecular sieve with ammonium, drying and calcining the mordenite molecular sieve to obtain a hydrogen-type mordenite molecular sieve;

[0009] (2) mixing the hydrogen-type mordenite molecular sieve obtained in step (1) with a lanthanum salt solution to perform ion exchange, drying, and calcining to obtain a lanthanum-modified molecular sieve;

[0010] (3) The lanthanum-modified molecular sieve obtained in step (2) is mixed with a gallium salt solution to perform ion exchange, and then dried and calcined to obtain the lanthanum-gallium-modified molecular sieve catalyst.

[0011] The present invention adopts metal lanthanum and metal gallium to jointly modify the molecular sieve. The introduction of lanthanum and gallium can reduce the B acid content in the molecular sieve and increase the L acid content without destroying the skeleton structure of the molecular sieve. It can effectively inhibit the carbon deposition deactivation and isomerization reaction of the reaction and the occurrence of olefin polymerization reaction, thereby improving the selectivity of the target product and the operating life of the catalyst.

[0012] As a preferred embodiment of the method for preparing the lanthanum gallium modified molecular sieve catalyst of the present invention, in the step (1), the silicon-aluminum ratio of the mordenite molecular sieve is 5-300.

[0013] Preferably, in step (1), the silicon-aluminum ratio of the mordenite molecular sieve is 10-200.

[0014] Preferably, the ammonium exchange is performed by mixing the mordenite molecular sieve with an ammonium salt solution to perform ammonium exchange; further, the ammonium salt is ammonium nitrate.

[0015] As a preferred embodiment of the preparation method of the lanthanum gallium modified molecular sieve catalyst of the present invention, in the lanthanum gallium modified molecular sieve catalyst, lanthanum accounts for 0.2% to 8% of the total mass of the catalyst, and gallium accounts for 0.2% to 8% of the total mass of the catalyst.

[0016] When the mass ratio of lanthanum and gallium in the catalyst is within the above range, the catalyst can have better catalytic performance, and the above mass ratio of lanthanum and gallium can be achieved by adjusting the number of ion exchanges and the concentration of the lanthanum salt solution or the gallium salt solution.

[0017] Preferably, in the lanthanum-gallium modified molecular sieve catalyst, lanthanum accounts for 0.5% to 5% of the total mass of the catalyst, and gallium accounts for 0.5% to 5% of the total mass of the catalyst.

[0018] As a preferred embodiment of the method for preparing the lanthanum-gallium modified molecular sieve catalyst of the present invention, in the lanthanum-gallium modified molecular sieve catalyst, the mass ratio of lanthanum to gallium is (0.5-4):1.

[0019] Preferably, in the lanthanum-gallium modified molecular sieve catalyst, the mass ratio of lanthanum to gallium is (1-3):1.

[0020] In the present invention, the content of the lanthanum or gallium in the catalyst is calculated based on the mass of the metal element lanthanum or gallium.

[0021] As a preferred embodiment of the method for preparing the lanthanum-gallium modified molecular sieve catalyst of the present invention, the lanthanum salt is lanthanum nitrate, and the gallium salt is gallium nitrate.

[0022] As a preferred embodiment of the method for preparing the lanthanum gallium modified molecular sieve catalyst of the present invention, in the steps (1) to (3), the drying temperature is 60° C. to 140° C., and the drying time is 8 h to 24 h.

[0023] Preferably, in the steps (1) to (3), the drying temperature is 80° C. to 120° C., and the drying time is 12 h to 18 h.

[0024] As a preferred embodiment of the method for preparing the lanthanum gallium modified molecular sieve catalyst of the present invention, in the steps (1) to (3), the calcination temperature is 400° C. to 700° C., and the calcination time is 3 h to 10 h.

[0025] Preferably, in the steps (1) to (3), the calcination temperature is 500° C. to 650° C., and the calcination time is 4 h to 8 h.

[0026] In a second aspect, the present invention provides a lanthanum gallium modified molecular sieve catalyst prepared by the preparation method of the lanthanum gallium modified molecular sieve catalyst.

[0027] In a third aspect, the present invention provides the use of the lanthanum gallium modified molecular sieve catalyst in the preparation of long-chain alkyl naphthalene.

[0028] When the lanthanum gallium modified molecular sieve catalyst of the present invention is used for the preparation of long-chain alkylnaphthalene, it has higher catalytic activity than unmodified mordenite and single metal modified mordenite molecular sieves, and the reaction conversion rate and selectivity can be higher than 95%. In addition, the catalyst of the present invention is pollution-free, easy to separate, and reusable. The reaction conditions are mild, no pressurization is required, and it has high safety.

[0029] In a fourth aspect, the present invention provides a method for preparing long-chain alkyl naphthalene, comprising the following steps:

[0030] S1. In the presence of the lanthanum gallium modified molecular sieve catalyst, naphthalene is alkylated with a long-chain olefin to obtain a crude product of alkylnaphthalene;

[0031] S2. The crude alkylnaphthalene obtained in step S1 is filtered to remove the catalyst, the incompletely reacted long-chain olefins and naphthalene, and the obtained solution is heated and decolorized using activated clay, and the clay is removed after decolorization to obtain the first alkylnaphthalene;

[0032] S3. distill the first alkylnaphthalene under reduced pressure to obtain the second alkylnaphthalene.

[0033] The preparation method of the long-chain alkyl naphthalene provided by the present invention does not require the use of organic solvents such as cyclohexane and n-heptane, and can directly obtain an alkyl naphthalene type lubricating oil base oil of a high-viscosity component by removing the raw materials that have not been completely reacted after the reaction, and the separation process is simple and efficient; and the first high-viscosity alkyl naphthalene obtained after removing the white clay in the present invention can be further distilled to obtain a second low-viscosity alkyl naphthalene type lubricating oil base oil, and the preparation method of the present invention can obtain alkyl naphthalene products of different viscosity components, and has broad application prospects.

[0034] As a preferred embodiment of the method for preparing long-chain alkylnaphthalene of the present invention, in step S1, the long-chain olefin is a C8-C18 straight-chain α-olefin.

[0035] As a preferred embodiment of the method for preparing long-chain alkylnaphthalene of the present invention, in the step S1, the molar ratio of the naphthalene to the long-chain olefin is (1-3):1.

[0036] As a preferred embodiment of the method for preparing long-chain alkyl naphthalene of the present invention, in the step S1, the amount of the lanthanum gallium modified molecular sieve catalyst added is 0.2% to 20% of the mass of the naphthalene.

[0037] Preferably, in step S1, the amount of the lanthanum gallium modified molecular sieve catalyst added is 1% to 15% of the mass of the naphthalene.

[0038] As a preferred embodiment of the method for preparing long-chain alkylnaphthalene of the present invention, in the step S1, the temperature of the alkylation reaction is 90° C. to 210° C., and the time is 0.5 h to 7 h.

[0039] Preferably, in step S1, the temperature of the alkylation reaction is 100° C. to 190° C., and the time is 1 h to 5 h.

[0040] As a preferred embodiment of the method for preparing long-chain alkyl naphthalene of the present invention, in the step S2, the amount of activated clay added is 1% to 20% of the mass of the solution.

[0041] Preferably, in step S2, the amount of activated clay added is 3% to 15% of the mass of the solution.

[0042] As a preferred embodiment of the method for preparing long-chain alkyl naphthalene of the present invention, in the step S2, the heating decolorization temperature is 70°C to 150°C, and the time is 30min to 300min.

[0043] Preferably, in step S2, the temperature of the heating decolorization is 80°C to 130°C, and the time is 60min to 240min.

[0044] As a preferred embodiment of the method for preparing long-chain alkylnaphthalene of the present invention, in the step S3, the temperature of the reduced pressure distillation is 180°C to 230°C.

[0045] The present invention has the following beneficial effects: the present invention discloses a lanthanum gallium modified molecular sieve catalyst and a method for catalytically preparing long-chain alkyl naphthalene, and by improving the process conditions, a high-viscosity long-chain alkyl naphthalene lubricating oil base oil can be quickly separated, and alkyl naphthalene components with different viscosities can be obtained by further distillation. The present invention overcomes the problems in the prior art that a solvent needs to be added to the reaction, the product separation operation is cumbersome, the liquid acid catalyst is prone to corrosion of the equipment, and the reaction needs to be pressurized. The lanthanum gallium modified molecular sieve catalyst of the present invention is used as an alkylation reaction catalyst, has excellent stability and catalytic performance, high alkylation reaction conversion rate and selectivity, good reproducibility, can be reused, and has industrial application value. DETAILED DESCRIPTION

[0046] To better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments. It should be understood by those skilled in the art that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0047] Unless otherwise specified, the experimental methods used in the examples are all conventional methods; the materials, reagents, etc. used, unless otherwise specified, can be obtained from commercial channels.

[0048] The following analysis method of the present invention and conversion rate and selectivity are calculated as follows:

[0049] The conversion rate and selectivity of alkylnaphthalene were measured by gas chromatography. The instrument model was A90 from Zhejiang Fuli Co., Ltd., with FID detector, nitrogen carrier gas, injection volume of 2 μL, split ratio of 50:1, front inlet temperature of 280°C, and different heating programs were adopted according to different raw materials.

[0050] The kinematic viscosity of alkyl naphthalene lubricating oil is measured according to GB / T 265-1988 and GB / T 3535-2006 standards.

[0051] The ratios of ions in the examples are all molar ratios unless otherwise specified.

[0052] Example 1

[0053] The preparation method of the lanthanum gallium modified molecular sieve catalyst of this embodiment comprises the following steps:

[0054] (1) ammonium exchange is performed on a mordenite molecular sieve with a silicon-aluminum ratio of 10, and the mordenite molecular sieve is added to a 0.1M ammonium nitrate solution at a solid-liquid mass ratio of 1:10, and the ammonium exchange is performed at 80°C for 4 hours, washed, filtered, and dried at 100°C for 16 hours, and the above ammonium exchange operation is repeated twice; the dried molecular sieve is calcined at 500°C for 5 hours to obtain a hydrogen-type mordenite molecular sieve;

[0055] (2) ion-exchanging the hydrogen-type mordenite molecular sieve obtained in step (1) with a 0.5 M lanthanum nitrate solution at 80° C. for 8 h at a solid-liquid mass ratio of 1:10, repeating the exchange three times, then washing, filtering, drying at 100° C. for 16 h, and then calcining at 550° C. for 4 h to obtain a lanthanum-modified molecular sieve;

[0056] (3) The lanthanum-modified molecular sieve obtained in step (2) was ion exchanged with a 0.3 M gallium nitrate solution at 80° C. for 6 h at a solid-liquid mass ratio of 1:10, and then washed, filtered, dried at 100° C. for 16 h, and then calcined at 550° C. for 4 h to obtain the lanthanum-gallium-modified molecular sieve catalyst of this embodiment.

[0057] In the catalyst obtained in this example, the mass proportion of lanthanum is 3%, and the mass proportion of gallium is 1%.

[0058] The obtained catalyst is used to prepare long-chain alkyl naphthalene. The preparation method of the long-chain alkyl naphthalene comprises the following steps:

[0059] S1. Naphthalene and 1-octene are added into a three-necked flask at a molar ratio of 1.5:1, stirred and heated to 110°C, and the above-mentioned lanthanum gallium modified molecular sieve catalyst of 4% by mass of naphthalene is added, and the reaction is carried out for 2 hours to obtain a crude product of alkylnaphthalene; wherein the conversion rate of 1-octene is 99% and the selectivity is 99%.

[0060] S2. After cooling the crude alkyl naphthalene product obtained in step S1 to room temperature, filtering to remove the solid catalyst, removing the incompletely reacted long-chain olefins and naphthalene, adding 5% by weight of activated clay to the obtained solution, stirring at 100° C. for 60 min, and removing the clay to obtain a first alkyl naphthalene type lubricating oil base oil;

[0061] S3. The first alkyl naphthalene lubricating base oil is distilled under reduced pressure at 180°C to obtain a fraction of the second low-viscosity component of the alkyl naphthalene lubricating base oil; the kinematic viscosities of the two alkyl naphthalenes at 100°C are 2.63 mm 2 / s, 2.23mm 2 / s, and the pour points are -39℃ and -41℃ respectively.

[0062] Example 2

[0063] The preparation method of the lanthanum gallium modified molecular sieve catalyst of this embodiment comprises the following steps:

[0064] (1) ammonium exchange is performed on a mordenite molecular sieve having a silicon-aluminum ratio of 20, and the mordenite molecular sieve is added to a 0.1M ammonium nitrate solution at a solid-liquid mass ratio of 1:10, and the ammonium exchange is performed at 80°C for 4 hours, followed by washing, filtering, and drying at 120°C for 12 hours, and the above ammonium exchange operation is repeated twice; the dried molecular sieve is calcined at 500°C for 4 hours to obtain a hydrogen-type mordenite molecular sieve;

[0065] (2) exchanging the hydrogen-type mordenite molecular sieve obtained in step (1) with a 0.3 M lanthanum nitrate solution at 85° C. for 6 h at a solid-liquid mass ratio of 1:10, repeating the exchange three times, then washing, filtering, drying at 120° C. for 12 h, and then calcining at 550° C. for 5 h to obtain a lanthanum-modified molecular sieve;

[0066] (3) The lanthanum-modified molecular sieve obtained in step (2) was ion exchanged with a 0.15M gallium nitrate solution at 80°C for 4 hours at a solid-liquid mass ratio of 1:15, and then washed, filtered, dried at 120°C for 12 hours, and then calcined at 550°C for 4 hours to obtain the lanthanum-gallium-modified molecular sieve catalyst of this embodiment.

[0067] In the catalyst obtained in this example, the mass proportion of lanthanum is 1%, and the mass proportion of gallium is 0.5%.

[0068] The obtained catalyst is used to prepare long-chain alkyl naphthalene. The preparation method of the long-chain alkyl naphthalene comprises the following steps:

[0069] S1. Naphthalene and 1-decene are added into a three-necked flask in a molar ratio of 2:1, stirred and heated to 130°C, and the above-mentioned lanthanum gallium modified molecular sieve catalyst of 6% by mass of naphthalene is added, and the reaction is carried out for 2 hours to obtain a crude product of alkylnaphthalene; wherein the conversion rate of 1-decene is 99% and the selectivity is 99%.

[0070] S2. After cooling the crude alkyl naphthalene product obtained in step S1 to room temperature, filtering to remove the solid catalyst, removing the incompletely reacted long-chain olefins and naphthalene, adding 10% by weight of activated clay to the obtained solution, stirring at 95° C. for 120 min, and removing the clay to obtain a first alkyl naphthalene type lubricating oil base oil;

[0071] S3. The first alkyl naphthalene lubricating oil base oil is distilled under reduced pressure at 185°C to obtain a fraction of the second low-viscosity component alkyl naphthalene lubricating oil base oil; the kinematic viscosities of the two alkyl naphthalenes at 100°C are measured in accordance with the standards of GB / T 265-1988 and GB / T 3535-2006 to be 3.28 mm 2 / s, 2.59mm 2 / s, and the pour points are -39℃ and -42℃ respectively.

[0072] Example 3

[0073] The preparation method of the lanthanum gallium modified molecular sieve catalyst of this embodiment comprises the following steps:

[0074] (1) ammonium exchange is performed on a mordenite molecular sieve having a silicon-aluminum ratio of 80, and the mordenite molecular sieve is added to a 0.1M ammonium nitrate solution at a solid-liquid mass ratio of 1:10, and the ammonium exchange is performed at 80°C for 4 hours, followed by washing, filtering, and drying at 100°C for 16 hours, and the above ammonium exchange operation is repeated twice; the dried molecular sieve is calcined at 500°C for 5 hours to obtain a hydrogen-type mordenite molecular sieve;

[0075] (2) exchanging the hydrogen-type mordenite molecular sieve obtained in step (1) with a 0.5 M lanthanum nitrate solution at 90° C. for 12 h at a solid-liquid mass ratio of 1:10, repeating the exchange 4 times, then washing, filtering, drying at 100° C. for 16 h, and then calcining at 600° C. for 4 h to obtain a lanthanum-modified molecular sieve;

[0076] (3) The lanthanum-modified molecular sieve obtained in step (2) was ion exchanged with a 0.5 M gallium nitrate solution at 80° C. for 8 h at a solid-liquid mass ratio of 1:10, and the exchange was repeated twice, followed by washing, filtering, and drying at 100° C. for 16 h, and then calcining at 600° C. for 4 h to obtain the lanthanum-gallium-modified molecular sieve catalyst of this embodiment.

[0077] In the catalyst obtained in this example, the mass proportion of lanthanum is 4%, and the mass proportion of gallium is 2%.

[0078] The obtained catalyst is used to prepare long-chain alkyl naphthalene. The preparation method of the long-chain alkyl naphthalene comprises the following steps:

[0079] S1. Naphthalene and 1-dodecene are added into a three-necked flask at a molar ratio of 2.5:1, stirred and heated to 140°C, and the above-mentioned lanthanum gallium modified molecular sieve catalyst of 5% by mass of naphthalene is added, and the reaction is carried out for 3 hours to obtain a crude product of alkylnaphthalene; wherein the conversion rate of 1-dodecene is 99% and the selectivity is 99%.

[0080] S2. After cooling the crude alkyl naphthalene product obtained in step S1 to room temperature, filtering to remove the solid catalyst, removing the incompletely reacted long-chain olefins and naphthalene, adding 8% by weight of activated clay to the obtained solution, stirring at 120° C. for 60 min, and removing the clay to obtain a first alkyl naphthalene type lubricating oil base oil;

[0081] S3. The first alkyl naphthalene lubricating base oil is distilled under reduced pressure at 190°C to obtain a fraction of the second low-viscosity component alkyl naphthalene lubricating base oil; the kinematic viscosities of the two alkyl naphthalenes at 100°C are measured according to the standards of GB / T 265-1988 and GB / T 3535-2006, and are 4.31 mm 2 / s, 3.69mm 2 / s, and the pour points are -38℃ and -41℃ respectively.

[0082] Example 4

[0083] The preparation method of the lanthanum gallium modified molecular sieve catalyst of this embodiment comprises the following steps:

[0084] (1) ammonium exchange is performed on a mordenite molecular sieve with a silicon-aluminum ratio of 50, and the mordenite molecular sieve is added to a 0.1M ammonium nitrate solution at a solid-liquid mass ratio of 1:15, and the ammonium exchange is performed at 90°C for 4 hours, washed, filtered, and dried at 110°C for 14 hours, and the above ammonium exchange operation is repeated twice; the dried molecular sieve is calcined at 500°C for 4 hours to obtain a hydrogen-type mordenite molecular sieve;

[0085] (2) the hydrogen-type mordenite molecular sieve obtained in step (1) was ion exchanged with a 0.5 M lanthanum nitrate solution at 80° C. for 6 h at a solid-liquid mass ratio of 1:15, and the exchange was repeated twice, followed by washing, filtering, and drying at 110° C. for 14 h, and then calcining at 500° C. for 4 h to obtain a lanthanum-modified molecular sieve;

[0086] (3) The lanthanum-modified molecular sieve obtained in step (2) was ion exchanged with a 0.3 M gallium nitrate solution at 80° C. for 4 h at a solid-liquid mass ratio of 1:15, and then washed, filtered, dried at 110° C. for 14 h, and then calcined at 550° C. for 4 h to obtain the lanthanum-gallium-modified molecular sieve catalyst of this embodiment.

[0087] In the catalyst obtained in this example, the mass proportion of lanthanum is 2%, and the mass proportion of gallium is 1%.

[0088] The obtained catalyst is used to prepare long-chain alkyl naphthalene. The preparation method of the long-chain alkyl naphthalene comprises the following steps:

[0089] S1. Naphthalene and 1-tetradecene are added into a three-necked flask at a molar ratio of 2.5:1, stirred and heated to 150°C, and the above-mentioned lanthanum gallium modified molecular sieve catalyst of 6% by mass of naphthalene is added, and the reaction is carried out for 3 hours to obtain a crude product of alkylnaphthalene; wherein the conversion rate of 1-tetradecene is 99% and the selectivity is 99%.

[0090] S2. After cooling the crude alkyl naphthalene product obtained in step S1 to room temperature, filtering to remove the solid catalyst, removing the incompletely reacted long-chain olefins and naphthalene, adding 5% by weight of activated clay to the obtained solution, stirring at 110° C. for 120 min, and removing the clay to obtain a first alkyl naphthalene type lubricating oil base oil;

[0091] S3. The first alkyl naphthalene lubricating base oil is subjected to vacuum distillation at 200°C to obtain a fraction of the second low-viscosity component alkyl naphthalene lubricating base oil; the kinematic viscosities of the two alkyl naphthalenes at 100°C are 4.51 mm and 4.51 mm, respectively, according to the standards of GB / T 265-1988 and GB / T 3535-2006. 2 / s, 3.83mm 2 / s, and the pour points are -40℃ and -43℃ respectively.

[0092] Example 5

[0093] The preparation method of the lanthanum gallium modified molecular sieve catalyst of this embodiment comprises the following steps:

[0094] (1) ammonium exchange is performed on a mordenite molecular sieve having a silicon-aluminum ratio of 30, and the mordenite molecular sieve is added to a 0.1M ammonium nitrate solution at a solid-liquid mass ratio of 1:10, and the ammonium exchange is performed at 80°C for 4 hours, followed by washing, filtering, and drying at 105°C for 16 hours, and the above ammonium exchange operation is repeated twice; the dried molecular sieve is calcined at 550°C for 4 hours to obtain a hydrogen-type mordenite molecular sieve;

[0095] (2) exchanging the hydrogen-type mordenite molecular sieve obtained in step (1) with a 0.3 M lanthanum nitrate solution at 80° C. for 4 h at a solid-liquid mass ratio of 1:15, repeating the exchange three times, then washing, filtering, drying at 105° C. for 16 h, and then calcining at 550° C. for 4 h to obtain a lanthanum-modified molecular sieve;

[0096] (3) The lanthanum-modified molecular sieve obtained in step (2) was ion exchanged with 0.3 M gallium nitrate solution at 80° C. for 4 h at a solid-liquid mass ratio of 1:15, and the exchange was repeated twice, followed by washing, filtering, and drying at 105° C. for 16 h, and then calcining at 550° C. for 4 h to obtain the lanthanum-gallium-modified molecular sieve catalyst of this embodiment.

[0097] In the catalyst obtained in this example, the mass proportion of lanthanum is 3%, and the mass proportion of gallium is 1.5%.

[0098] The obtained catalyst is used to prepare long-chain alkyl naphthalene. The preparation method of the long-chain alkyl naphthalene comprises the following steps:

[0099] S1. Naphthalene and 1-hexadecene are added into a three-necked flask in a molar ratio of 2:1, stirred and heated to 170°C, and the above-mentioned lanthanum gallium modified molecular sieve catalyst of 5% by mass of naphthalene is added, and the reaction is carried out for 3 hours to obtain a crude product of alkylnaphthalene; wherein the conversion rate of 1-hexadecene is 99% and the selectivity is 99%.

[0100] S2. After cooling the crude alkyl naphthalene product obtained in step S1 to room temperature, filtering to remove the solid catalyst, removing the incompletely reacted long-chain olefins and naphthalene, adding 8% by weight of activated clay to the obtained solution, stirring at 100° C. for 90 min, and removing the clay to obtain a first alkyl naphthalene type lubricating oil base oil;

[0101] S3. The first alkyl naphthalene lubricating oil base oil is distilled under reduced pressure at 220°C to obtain a fraction of the second low-viscosity component alkyl naphthalene lubricating oil base oil; the kinematic viscosities of the two alkyl naphthalenes at 100°C are measured according to the standards of GB / T 265-1988 and GB / T 3535-2006, and are 5.01 mm 2 / s, 4.29mm 2 / s, and the pour points are -39℃ and -41℃ respectively.

[0102] The lanthanum gallium modified molecular sieve catalyst obtained in this embodiment was filtered and recovered after one alkyl naphthalene preparation reaction, and the alkyl naphthalene preparation reaction was repeated 5 times. The conversion rate and selectivity of each time were statistically analyzed. The conversion rates of the five times were 99%, 98%, 97%, 97%, and 96%, respectively, and the selectivities were 99%, 98%, 97%, 96%, and 96%, respectively, indicating that the lanthanum gallium modified molecular sieve catalyst of the present invention can be recycled for multiple times and the catalytic activity will not be significantly reduced.

[0103] Example 6

[0104] The preparation method of the lanthanum gallium modified molecular sieve catalyst of this embodiment comprises the following steps:

[0105] (1) ammonium exchange is performed on a mordenite molecular sieve having a silicon-aluminum ratio of 80, and the mordenite molecular sieve is added to a 0.1M ammonium nitrate solution at a solid-liquid mass ratio of 1:10, and the ammonium exchange is performed at 80°C for 4 hours, followed by washing, filtering, and drying at 90°C for 16 hours, and the above ammonium exchange operation is repeated twice; the dried molecular sieve is calcined at 550°C for 4 hours to obtain a hydrogen-type mordenite molecular sieve;

[0106] (2) ion-exchanging the hydrogen-type mordenite molecular sieve obtained in step (1) with a 0.3 M lanthanum nitrate solution at 80° C. for 4 h at a solid-liquid mass ratio of 1:15, then washing, filtering, drying at 90° C. for 16 h, and then calcining at 550° C. for 4 h to obtain a lanthanum-modified molecular sieve;

[0107] (3) The lanthanum-modified molecular sieve obtained in step (2) was ion exchanged with a 0.3 M gallium nitrate solution at 80° C. for 4 h at a solid-liquid mass ratio of 1:15, and then washed, filtered, dried at 90° C. for 16 h, and then calcined at 550° C. for 4 h to obtain the lanthanum-gallium-modified molecular sieve catalyst of this embodiment.

[0108] In the catalyst obtained in this example, the mass proportion of lanthanum is 1%, and the mass proportion of gallium is 0.5%.

[0109] The obtained catalyst is used to prepare long-chain alkyl naphthalene. The preparation method of the long-chain alkyl naphthalene comprises the following steps:

[0110] S1. Naphthalene and 1-octadecene are added into a three-necked flask at a molar ratio of 1.5:1, stirred and heated to 180°C, and the above-mentioned lanthanum gallium modified molecular sieve catalyst with a mass% of naphthalene is added, and the reaction is carried out for 4 hours to obtain a crude product of alkylnaphthalene; wherein the conversion rate of 1-octadecene is 95% and the selectivity is 96%.

[0111] S2. After cooling the crude alkyl naphthalene product obtained in step S1 to room temperature, filtering to remove the solid catalyst, removing the incompletely reacted long-chain olefins and naphthalene, adding 10% by weight of activated clay to the obtained solution, stirring at 120° C. for 120 min, and removing the clay to obtain a first alkyl naphthalene type lubricating oil base oil;

[0112] S3. The first alkyl naphthalene lubricating base oil is distilled under reduced pressure at 225°C to obtain a fraction of the second low-viscosity component alkyl naphthalene lubricating base oil; the kinematic viscosities of the two alkyl naphthalenes at 100°C are measured in accordance with the standards of GB / T 265-1988 and GB / T 3535-2006 to be 5.44 mm 2 / s, 4.71mm 2 / s, and the pour points are -40℃ and -42℃ respectively.

[0113] Comparative Example 1

[0114] The difference between the preparation method of the catalyst in this comparative example and the preparation method of the catalyst in Example 1 is that the step (3) is not included, that is, only lanthanum is used to modify the molecular sieve, and the remaining preparation method parameters are the same as those in Example 1 to obtain the lanthanum-modified molecular sieve catalyst in this comparative example.

[0115] The catalyst of this comparative example is used to catalytically prepare long-chain alkyl naphthalene. The preparation method of long-chain alkyl naphthalene is the same as that of Example 1. In this comparative example, the conversion rate of 1-octene is 90% and the selectivity is 95%.

[0116] Comparative Example 2

[0117] The difference between the preparation method of the catalyst in this comparative example and the preparation method of the catalyst in Example 1 is that the step (2) is not included, that is, only gallium is used to modify the molecular sieve, and the remaining preparation method parameters are the same as those in Example 1 to obtain the gallium-modified molecular sieve catalyst in this comparative example.

[0118] The catalyst of this comparative example is used to catalytically prepare long-chain alkyl naphthalene. The preparation method of long-chain alkyl naphthalene is the same as that of Example 1. In this comparative example, the conversion rate of 1-octene is 88% and the selectivity is 94%.

[0119] Comparative Example 3

[0120] In this comparative example, the mordenite molecular sieve raw material with a silicon-aluminum ratio of 10 used in Example 1 is used as a catalyst for catalytic preparation of long-chain alkyl naphthalene. The preparation method of long-chain alkyl naphthalene is the same as that of Example 1. In this comparative example, the conversion rate of 1-octene is 74% and the selectivity is 91%.

[0121] Comparative Example 4

[0122] In this comparative example, the catalyst in Example 1 is used to catalyze the preparation of long-chain alkyl naphthalene. The difference between the preparation method of long-chain alkyl naphthalene and that of Example 1 is that in step S1, the temperature of the alkylation reaction is 80° C., and the other preparation method parameters are the same as those of Example 1. In this comparative example, the conversion rate of 1-octene is 60% and the selectivity is 88%.

[0123] Comparative Example 5

[0124] In this comparative example, the catalyst in Example 1 is used to catalyze the preparation of long-chain alkyl naphthalene. The difference between the preparation method of long-chain alkyl naphthalene and that of Example 1 is that in step S1, the alkylation reaction time is 220 min, and the other preparation method parameters are the same as those of Example 1. In this comparative example, the conversion rate of 1-octene is 75%, and the selectivity is 85%.

[0125] Comparative Example 6

[0126] The difference between the preparation method of the comparative example catalyst and the preparation method of the catalyst in Example 3 is that the comparative example catalyst does not contain step (3), that is, only lanthanum is used to modify the molecular sieve, and the remaining preparation method parameters are the same as those in Example 3 to obtain the lanthanum-modified molecular sieve catalyst of the comparative example.

[0127] The catalyst of this comparative example is used to catalytically prepare long-chain alkyl naphthalene. The preparation method of long-chain alkyl naphthalene is the same as that of Example 3. In this comparative example, the conversion rate of 1-dodecene is 87% and the selectivity is 94%.

[0128] Comparative Example 7

[0129] The difference between the preparation method of the comparative example catalyst and the preparation method of the catalyst of Example 3 is that the comparative example catalyst does not contain step (2), that is, only gallium is used to modify the molecular sieve, and the remaining preparation method parameters are the same as those of Example 3 to obtain the gallium-modified molecular sieve catalyst of the comparative example.

[0130] The catalyst of this comparative example is used to catalytically prepare long-chain alkyl naphthalene. The preparation method of long-chain alkyl naphthalene is the same as that of Example 3. In this comparative example, the conversion rate of 1-dodecene is 88% and the selectivity is 95%.

[0131] Comparative Example 8

[0132] In this comparative example, the mordenite molecular sieve raw material with a silicon-aluminum ratio of 80 used in Example 3 is used as a catalyst for catalytic preparation of long-chain alkyl naphthalene. The preparation method of long-chain alkyl naphthalene is the same as that of Example 3. In this comparative example, the conversion rate of 1-dodecene is 71% and the selectivity is 92%.

[0133] Comparative Example 9

[0134] The difference between the preparation method of the catalyst of this comparative example and the preparation method of the catalyst of Example 3 is that the method does not contain step (2) and step (3), and the remaining preparation method parameters are the same as those of Example 3, that is, the hydrogen-type mordenite molecular sieve obtained in step (1) is the catalyst of this comparative example.

[0135] The catalyst of this comparative example is used to catalytically prepare long-chain alkyl naphthalene. The preparation method of long-chain alkyl naphthalene is the same as that of Example 3. In this comparative example, the conversion rate of 1-dodecene is 75% and the selectivity is 93%.

[0136] Comparative Example 10

[0137] The difference between the preparation method of the comparative example catalyst and the preparation method of the catalyst of Example 5 is that the comparative example catalyst does not contain step (3), that is, only lanthanum is used to modify the molecular sieve, and the remaining preparation method parameters are the same as those of Example 5 to obtain the lanthanum-modified molecular sieve catalyst of the comparative example.

[0138] The catalyst of this comparative example is used to catalytically prepare long-chain alkyl naphthalene. The preparation method of long-chain alkyl naphthalene is the same as that of Example 5. In this comparative example, the conversion rate of 1-hexadecene is 91% and the selectivity is 95%.

[0139] Comparative Example 11

[0140] The difference between the preparation method of the comparative example catalyst and the preparation method of the catalyst of Example 5 is that the comparative example catalyst does not contain step (2), that is, only gallium is used to modify the molecular sieve, and the remaining preparation method parameters are the same as those of Example 5 to obtain the gallium-modified molecular sieve catalyst of the comparative example.

[0141] The catalyst of this comparative example is used to catalytically prepare long-chain alkyl naphthalene. The preparation method of long-chain alkyl naphthalene is the same as that of Example 5. In this comparative example, the conversion rate of 1-hexadecene is 90% and the selectivity is 95%.

[0142] Comparative Example 12

[0143] In this comparative example, the mordenite molecular sieve raw material with a silicon-aluminum ratio of 30 used in Example 5 is used as a catalyst for catalytic preparation of long-chain alkyl naphthalene. The preparation method of long-chain alkyl naphthalene is the same as that of Example 5. In this comparative example, the conversion rate of 1-hexadecene is 80% and the selectivity is 93%.

[0144] Comparative Example 13

[0145] The difference between the preparation method of the catalyst of this comparative example and the preparation method of the catalyst of Example 5 is that the method does not contain step (2) and step (3), and the remaining preparation method parameters are the same as those of Example 5, that is, the hydrogen-type mordenite molecular sieve obtained in step (1) is the catalyst of this comparative example.

[0146] The catalyst of this comparative example is used to catalytically prepare long-chain alkyl naphthalene. The preparation method of long-chain alkyl naphthalene is the same as that of Example 5. In this comparative example, the conversion rate of 1-hexadecene is 83% and the selectivity is 95%.

[0147] Comparative Example 14

[0148] In this comparative example, a mordenite molecular sieve raw material with a silicon-aluminum ratio of 200 is used as a catalyst for catalytic preparation of long-chain alkyl naphthalene. The preparation method of long-chain alkyl naphthalene is the same as that of Example 5. In this comparative example, the conversion rate of 1-hexadecene is 72% and the selectivity is 93%.

[0149] Comparative Example 15

[0150] In this comparative example, a mordenite molecular sieve raw material with a silicon-aluminum ratio of 100 is used as a catalyst for catalytic preparation of long-chain alkyl naphthalene. The preparation method of long-chain alkyl naphthalene is the same as that of Example 5. In this comparative example, the conversion rate of 1-hexadecene is 76% and the selectivity is 94%.

[0151] Comparative Example 16

[0152] In this comparative example, the catalyst in Example 5 is used to catalyze the preparation of long-chain alkyl naphthalene. The difference between the preparation method of long-chain alkyl naphthalene and that of Example 5 is that in step S1, the temperature of the alkylation reaction is 85° C., and the other preparation method parameters are the same as those of Example 5. In this comparative example, the conversion rate of 1-hexadecene is 68%, and the selectivity is 87%.

[0153] Comparative Example 17

[0154] In this comparative example, the catalyst in Example 5 is used to catalyze the preparation of long-chain alkyl naphthalene. The difference between the preparation method of long-chain alkyl naphthalene and that of Example 5 is that in step S1, the addition amount of the lanthanum gallium modified molecular sieve catalyst is 0.1% of the mass of naphthalene, and the other preparation method parameters are the same as those of Example 5. In this comparative example, the conversion rate of 1-hexadecene is 40% and the selectivity is 70%.

[0155] Comparative Example 18

[0156] In this comparative example, the catalyst in Example 5 is used to catalytically prepare long-chain alkyl naphthalene. The difference between the preparation method of long-chain alkyl naphthalene and Example 5 is that in step S1, naphthalene and 1-hexadecene are in a molar ratio of 0.8:1, and the remaining preparation method parameters are the same as those in Example 5. In this comparative example, the conversion rate of 1-hexadecene is 80% and the selectivity is 95%.

[0157] Comparative Example 19

[0158] In this comparative example, the catalyst in Example 5 is used to catalyze the preparation of long-chain alkyl naphthalene. The difference between the preparation method of long-chain alkyl naphthalene and that of Example 5 is that in step S1, the alkylation reaction time is 9 hours, and the other preparation method parameters are the same as those of Example 5. In this comparative example, the conversion rate of 1-hexadecene is 90%, and the selectivity is 95%.

[0159] Comparative Example 20

[0160] The preparation method of the catalyst of this comparative example comprises the following steps:

[0161] (1) ion exchange was performed on a mordenite molecular sieve having a silicon-aluminum ratio of 10 at a solid-liquid mass ratio of 1:10 with a 0.5 M lanthanum nitrate solution at 80° C. for 8 h, and the exchange was repeated 3 times, followed by washing, filtering and drying, and then calcining at 550° C. for 4 h to obtain a lanthanum-modified molecular sieve;

[0162] (2) ion-exchanging the lanthanum-modified molecular sieve obtained in step (1) with a 0.3 M gallium nitrate solution at 80° C. for 6 h at a solid-liquid mass ratio of 1:10, then washing, filtering and drying, and then calcining at 550° C. for 4 h to obtain a lanthanum-gallium modified molecular sieve;

[0163] (3) The lanthanum-gallium modified molecular sieve obtained in step (2) was added to a 0.1M ammonium nitrate solution at a solid-liquid mass ratio of 1:10, and ammonium exchange was performed at 80°C for 4 hours, followed by washing, filtering and drying, and the above ammonium exchange operation was repeated twice; the dried molecular sieve was calcined at 500°C for 5 hours to obtain the lanthanum-gallium modified molecular sieve catalyst of this comparative example.

[0164] That is, the difference between the preparation method of the catalyst of this comparative example and the preparation method of the catalyst of Example 1 is that ion exchange is first performed with lanthanum nitrate, then with gallium nitrate, and finally with ammonium exchange to obtain the catalyst of this comparative example.

[0165] The catalyst of this comparative example is used to catalytically prepare long-chain alkyl naphthalene. The preparation method of long-chain alkyl naphthalene is the same as that of Example 1. In this comparative example, the conversion rate of 1-octene is 93% and the selectivity is 94%.

[0166] Comparative Example 21

[0167] The preparation method of the catalyst of this comparative example comprises the following steps:

[0168] (1) ammonium exchange is performed on a mordenite molecular sieve having a silicon-aluminum ratio of 10, and the mordenite molecular sieve is added to a 0.1M ammonium nitrate solution at a solid-liquid mass ratio of 1:10, and the ammonium exchange is performed at 80°C for 4 hours, followed by washing, filtering and drying, and the above ammonium exchange operation is repeated twice; the dried molecular sieve is calcined at 500°C for 5 hours to obtain a hydrogen-type mordenite molecular sieve;

[0169] (2) exchanging the hydrogen-type mordenite molecular sieve obtained in step (1) with a 0.1 M lanthanum nitrate solution at 80° C. for 10 h at a solid-liquid mass ratio of 1:10, repeating the exchange three times, then washing, filtering and drying, and then calcining at 550° C. for 4 h to obtain a lanthanum-modified molecular sieve;

[0170] (3) The lanthanum-modified molecular sieve obtained in step (2) was ion exchanged with a 0.15M gallium nitrate solution at 80°C for 8 hours at a solid-liquid mass ratio of 1:10, and then washed, filtered and dried, and then calcined at 550°C for 4 hours to obtain the lanthanum-gallium-modified molecular sieve catalyst of this comparative example.

[0171] In the catalyst obtained in this comparative example, the mass proportion of lanthanum is 0.1%, and the mass proportion of gallium is 0.1%.

[0172] The catalyst of this comparative example is used to catalyze the preparation of long-chain alkyl naphthalene. The preparation method of long-chain alkyl naphthalene is the same as that of Example 1. In this comparative example, the conversion rate of 1-octene is 88% and the selectivity is 92%. The mass proportion of lanthanum is 3%, and the mass proportion of gallium is 1%.

[0173] Comparative Example 22

[0174] The preparation method of the catalyst of this comparative example comprises the following steps:

[0175] (1) ammonium exchange is performed on a mordenite molecular sieve having a silicon-aluminum ratio of 10, and the mordenite molecular sieve is added to a 0.1M ammonium nitrate solution at a solid-liquid mass ratio of 1:10, and the ammonium exchange is performed at 80°C for 4 hours, followed by washing, filtering and drying, and the above ammonium exchange operation is repeated twice; the dried molecular sieve is calcined at 500°C for 5 hours to obtain a hydrogen-type mordenite molecular sieve;

[0176] (2) exchanging the hydrogen-type mordenite molecular sieve obtained in step (1) with a 1.0 M lanthanum nitrate solution at 80° C. for 12 h at a solid-liquid mass ratio of 1:10, repeating the exchange three times, then washing, filtering and drying, and then calcining at 550° C. for 4 h to obtain a lanthanum-modified molecular sieve;

[0177] (3) The lanthanum-modified molecular sieve obtained in step (2) was ion exchanged with a 0.5M gallium nitrate solution at 80°C for 8h at a solid-liquid mass ratio of 1:10, and then washed, filtered and dried, and then calcined at 550°C for 4h to obtain the lanthanum-gallium-modified molecular sieve catalyst of this comparative example.

[0178] In the catalyst obtained in this comparative example, the mass proportion of lanthanum is 5%, and the mass proportion of gallium is 1%.

[0179] The catalyst of this comparative example is used to catalytically prepare long-chain alkyl naphthalene. The preparation method of long-chain alkyl naphthalene is the same as that of Example 1. In this comparative example, the conversion rate of 1-octene is 90% and the selectivity is 93%.

[0180] In summary, the lanthanum gallium modified molecular sieve catalyst provided by the present invention can be used to catalyze the alkylation reaction of long-chain olefins and naphthalene to prepare long-chain alkylnaphthalene, has high conversion rate and selectivity, can be recycled, can prepare two viscosities of alkylnaphthalene type lubricating oil base oils, and the separation process is simple to operate, and has industrial application value.

[0181] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A method for preparing a lanthanum-gallium modified molecular sieve catalyst, characterized in that: The following steps are involved: (1) exchanging the mordenite molecular sieve with ammonium, drying and calcining the mordenite molecular sieve to obtain a hydrogen-type mordenite molecular sieve; (2) mixing the hydrogen-type mordenite molecular sieve obtained in step (1) with a lanthanum salt solution to perform ion exchange, drying, and calcining to obtain a lanthanum-modified molecular sieve; (3) The lanthanum-modified molecular sieve obtained in step (2) is mixed with a gallium salt solution to perform ion exchange, and then dried and calcined to obtain the lanthanum-gallium-modified molecular sieve catalyst.

2. The method for preparing the lanthanum-gallium modified molecular sieve catalyst according to claim 1, characterized in that: In the lanthanum-gallium modified molecular sieve catalyst, lanthanum accounts for 0.2% to 8% of the total mass of the catalyst, and gallium accounts for 0.2% to 8% of the total mass of the catalyst.

3. The method for preparing the lanthanum-gallium modified molecular sieve catalyst according to claim 1, characterized in that: Satisfy at least one of the following: (1-1) In the lanthanum-gallium modified molecular sieve catalyst, the mass ratio of lanthanum to gallium is (0.5-4):1; (1-2) In step (1), the silicon-aluminum ratio of the mordenite molecular sieve is 5 to 300; (1-3) In the steps (1) to (3), the calcination temperature is 400° C. to 700° C. and the calcination time is 3 h to 10 h; (1-4) In the steps (1) to (3), the drying temperature is 60°C to 140°C and the drying time is 8h to 24h; (1-5) The lanthanum salt is lanthanum nitrate, and the gallium salt is gallium nitrate.

4. A lanthanum-gallium modified molecular sieve catalyst prepared by the preparation method of the lanthanum-gallium modified molecular sieve catalyst according to any one of claims 1 to 3.

5. Use of the lanthanum-gallium modified molecular sieve catalyst according to claim 4 in the preparation of long-chain alkylnaphthalene.

6. A method for preparing long-chain alkyl naphthalene, characterized in that: The following steps are involved: S1. In the presence of the lanthanum gallium modified molecular sieve catalyst according to claim 4, naphthalene is subjected to an alkylation reaction with a long-chain olefin to obtain a crude product of alkylnaphthalene; S2. The crude alkylnaphthalene obtained in step S1 is filtered to remove the catalyst, the incompletely reacted long-chain olefins and naphthalene, and the obtained solution is heated and decolorized using activated clay, and the clay is removed after decolorization to obtain the first alkylnaphthalene; S3. distill the first alkylnaphthalene under reduced pressure to obtain the second alkylnaphthalene.

7. The method for preparing long-chain alkylnaphthalene according to claim 6, characterized in that: In the step S1, the molar ratio of the naphthalene to the long-chain olefin is (1-3):

1.

8. The method for preparing long-chain alkyl naphthalene according to claim 6, characterized in that: In the step S1, the amount of the lanthanum gallium modified molecular sieve catalyst added is 0.2% to 20% of the mass of the naphthalene.

9. The method for preparing long-chain alkylnaphthalene according to claim 6, characterized in that: In the step S1, the temperature of the alkylation reaction is 90° C. to 210° C., and the time is 0.5 h to 7 h.

10. The method for preparing long-chain alkyl naphthalene according to claim 6, characterized in that: Satisfy at least one of the following: (2-1) In step S1, the long-chain olefin is a C8-C18 straight-chain α-olefin; (2-2) In step S2, the amount of activated clay added is 1% to 20% of the mass of the solution; (2-3) In step S2, the heating decolorization temperature is 70°C to 150°C, and the time is 30min to 300min; (2-4) In the step S3, the temperature of the reduced pressure distillation is 180°C to 230°C.