Preparation method of naphthalene oligomer

Abstract

According to the preparation method of the naphthalene oligomer provided by the invention, the C16H36CIP-xAlCl3 ionic liquid is adopted to catalyze the polymerization reaction of the naphthalene compound to obtain the naphthalene oligomer, the yield of the naphthalene oligomer can be effectively improved, and the prepared naphthalene oligomer has the advantages of narrow molecular weight distribution and low ash content, so that a high-quality precursor is provided for preparation of mesophase pitch.

Description

Technical Field

[0001] The invention relates to catalytic technology, and in particular to a method for preparing naphthalene oligomers. Background Art

[0002] Carbon fiber has a prominent position in various fields such as aerospace, national defense, sports equipment, etc. due to its advantages such as light weight and good mechanical properties. Among them, mesophase pitch-based carbon fiber has attracted extensive attention due to its excellent tensile modulus and heat transfer performance, but the preparation of high-quality spinnable mesophase pitch currently limits its industrial development and application. The key factors affecting the composition, structure and performance of mesophase pitch are the source of pitch and its preparation process.

[0003] The raw materials of mesophase pitch come from a wide range of sources, including coal tar pitch, petroleum pitch and pure aromatic compounds. Compared with coal tar pitch and petroleum pitch, pure aromatic substances are widely used as raw materials for synthesizing mesophase pitch due to their high purity, lack of ash and other impurities, and simple modulation process. Commonly used pure aromatics include naphthalene, acenaphthylene, tetrabenzophenazine and phenanthrene. For example, using naphthalene as raw material and AlCl 3 , HF / BF 3 、SO 4 2- / ZrO 2 Using solid superacid or ionic liquid as catalyst, naphthalene polymerization can obtain naphthalene polymers, which can be further polycondensed to obtain high-quality mesophase asphalt.

[0004] However, AlCl 3 When used as a catalyst, it exists in a molten form during the reaction and has a certain solubility in the generated product. Therefore, AlCl 3 The separation from naphthalene pitch is very difficult, resulting in the ash content of the obtained naphthalene pitch generally not less than 200μg / g, which will affect the performance of the final carbon product. 3 When used as a catalyst, it is highly toxic and corrosive, has strict requirements on the reactor, and the reaction process usually requires a pressure of more than 2 MPa to ensure the yield. 4 2- / ZrO 2 When used as catalyst, solid superacid has the problem that acid sites are unevenly distributed and active components are easily lost. Although ionic liquid catalysis solves the problems that the catalyst and product that the above-mentioned catalyst exists are difficult to separate, the catalytic active components are lost, the catalyst has high corrosiveness and high toxicity and the catalytic product ash content is high, the current ionic liquid catalysis naphthalene polymerization still has the problem that the yield of the obtained naphthalene oligomer is lower and the molecular weight distribution is dispersed. Therefore, how to obtain the naphthalene oligomer with high yield and concentrated molecular weight distribution is an important issue faced by those skilled in the art. Summary of the invention

[0005] The invention provides a method for preparing a naphthalene oligomer, which has the advantages of high yield and concentrated molecular weight distribution of the naphthalene oligomer, and can provide a high-quality precursor for the preparation of mesophase asphalt.

[0006] The present invention provides a method for preparing a naphthalene oligomer, comprising the following steps:

[0007] Using C 16 H 36 CIP-xAlCl 3 The ionic liquid catalyzes the polymerization reaction of the naphthalene series compound to obtain naphthalene oligomers;

[0008] C 16 H 36 CIP-xAlCl 3 The general structural formula of ionic liquids is shown in Formula 1:

[0009] Formula 1

[0010] In formula 1, 1<x≤2.

[0011] In the preparation method as described above, the naphthalene series compound comprises alkyl-substituted naphthalene and / or unsubstituted naphthalene.

[0012] The preparation method as described above, wherein C 16 H 36 CIP-xAlCl 3 The molar ratio of the ionic liquid to the naphthalene compound is (1-5):20.

[0013] In the preparation method as described above, the polymerization reaction temperature is 60-180°C.

[0014] In the preparation method as described above, the polymerization reaction time is 0.5-6.5 hours.

[0015] In the preparation method as described above, the stirring rate of the polymerization reaction is 150-250 r / min.

[0016] The preparation method as described above, wherein C 16 H 36 CIP-xAlCl 3 The preparation method of the ionic liquid comprises the following steps:

[0017] C 16 H 36 CIP and AlCl 3 mixing to obtain a mixture;

[0018] The mixture is reacted at 100-150°C for 1-10 hours to obtain C 16 H36 CIP-xAlCl 3 Ionic liquids.

[0019] The preparation method as described above, wherein C 16 H 36 CIP-xAlCl 3 The preparation of the ionic liquid is carried out under the protection of an inert gas, wherein the inert gas includes at least one of nitrogen, argon and neon;

[0020] And / or, the polymerization reaction is carried out under the protection of an inert gas, wherein the inert gas comprises at least one of nitrogen, argon and neon.

[0021] The preparation method as described above, wherein the polymerization reaction further includes a purification process, and the purification process includes:

[0022] The polymerization product obtained after the polymerization reaction contains a polymerization product and C 16 H 36 CIP-xAlCl 3 adding an organic solvent to the mixed product of the ionic liquid to obtain a mixed solution;

[0023] adding an alkali solution to the mixed solution, washing and separating to obtain a polymerization product containing naphthalene oligomers;

[0024] The polymerization product is subjected to reduced pressure distillation to obtain naphthalene oligomers.

[0025] The preparation method as described above, wherein the organic solvent comprises at least one of dichloromethane, chloroform, carbon tetrachloride, trichloroethane, chlorobenzene, benzene, toluene and xylene; and / or,

[0026] The alkaline solution includes at least one of sodium hydroxide and potassium hydroxide; the concentration of the alkaline solution is 0.1-2 mol / L.

[0027] The present invention provides a method for preparing a naphthalene oligomer, using C 16 H 36 CIP-xAlCl 3 Ionic liquids are used to catalyze the polymerization of naphthalene compounds to obtain naphthalene polymers. The preparation method has a high yield, and the prepared naphthalene polymers have a narrow molecular weight distribution and low ash content, and can provide high-quality precursors for the preparation of mesophase asphalt. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is the mass spectrum of the naphthalene polymer in Example 1 and Comparative Examples 1-4. DETAILED DESCRIPTION

[0029] In order to enable those skilled in the art to better understand the scheme of the present invention, the present invention is further described in detail below. The specific implementation methods listed below are only for describing the principles and features of the present invention. The examples are only used to explain the present invention and are not intended to limit the scope of the present invention. Based on the embodiments of the present invention, all other implementation methods obtained by ordinary technicians in the field without creative work are within the scope of protection of the present invention.

[0030] The first aspect of the present invention provides a method for preparing a naphthalene oligomer, comprising the following steps:

[0031] Using C 16 H 36 CIP-xAlCl 3 The ionic liquid catalyzes the polymerization reaction of the naphthalene series compound to obtain naphthalene oligomers;

[0032] C 16 H 36 CIP-xAlCl 3 The general structural formula of ionic liquids is shown in Formula 1:

[0033] Formula 1

[0034] In formula 1, 1<x≤2.

[0035] Among them, C 16 H 36 CIP-xAlCl 3 Ionic liquids are halogenated metal salt ionic liquids composed of ions. They provide high Lewis acidity comparable to traditional homogeneous catalysts in liquid form and can serve as an industrial-scale alternative to toxic and corrosive inorganic acids.

[0036] It is understandable that x represents C 16 H 36 CIP and AlCl 3 For example, when x is 2.0, that is, C 16 H 36 CIP-xAlCl 3 The ionic liquid is C 16 H 36 CIP-2.0AlCl 3 When ionic liquid is used, it means preparing C 16 H 36 CIP-xAlCl 3 C used in ionic liquids 16 H 36 CIP and AlCl 3 The molar ratio is 1:2.0.

[0037] In the present invention, C is defined as16 H 36 CIP-xAlCl 3 The general structural formula of ionic liquids and the range of x in the general structural formula can ensure that C 16 H 36 CIP-xAlCl 3 Ionic liquids are non-volatile, easy to separate from products, have high catalytic activity, adjustable acidity, are environmentally friendly, and have low corrosiveness. On the other hand, the value of x can be adjusted to promote C 16 H 36 CIP-xAlCl 3 When the ionic liquid is used as a catalyst to catalyze the polymerization reaction of naphthalene compounds, the yield of naphthalene polymers is effectively improved, and the prepared naphthalene polymers have the advantage of a narrow molecular weight distribution.

[0038] In one embodiment of the present invention, the naphthalene oligomer prepared by the preparation method of the present invention has a yield of up to 89.0%, a molecular weight distribution of 192-576 Da, and mainly includes dimers to tetramers of naphthalene, among which naphthalene dimers are the main ones, and also includes trace amounts of other polymers.

[0039] The high yield and narrow molecular weight distribution of naphthalene oligomers have important practical value for the subsequent acquisition of high-quality mesophase asphalt. In the thermal polycondensation process of preparing mesophase asphalt from naphthalene oligomers, the autocatalytic effect and the automatic acceleration of free radical reactions will make the preparation of mesophase asphalt difficult to control. However, since naphthalene oligomers with narrow molecular weight distribution have a relatively clear molecular structure and composition, their influence on the subsequent thermal polycondensation reaction can be known, which is helpful to regulate the preparation process of mesophase asphalt and easily obtain mesophase asphalt with excellent rheology and mesophase content close to 100%. At the same time, the high yield of naphthalene oligomers will also increase the yield of mesophase asphalt, which has an important impact on improving the overall reaction efficiency, reducing production costs and reducing environmental pollution.

[0040] In the present invention, the naphthalene polymers prepared by the above preparation method can be used as a precursor for preparing mesophase asphalt. The present invention does not limit the method for preparing mesophase asphalt from naphthalene polymers, and those skilled in the art can prepare it using conventional methods in the art.

[0041] In a specific embodiment, the naphthalene-based compound includes alkyl-substituted naphthalene and / or unsubstituted naphthalene.

[0042] In the present invention, the naphthalene series compound can be unsubstituted naphthalene, or alkyl-substituted naphthalene, or a mixture of unsubstituted naphthalene and alkyl-substituted naphthalene. When unsubstituted naphthalene is used as a raw material to prepare naphthalene polymers, its cost is relatively low, and its structure is simple, compared with coal tar and petroleum as raw materials, the side reactions that may occur during the polymerization process are reduced, so that the reaction path is more direct, and the purity of the reaction product is higher. When alkyl-substituted naphthalene is used as a raw material to prepare naphthalene polymers, the processing performance and handling convenience of naphthalene polymers can usually be improved, and then the prepared mesophase pitch has a lower softening point; however, the overlong alkyl side chain can cause a large amount of small molecule hydrocarbons to be cracked in the process of preparing mesophase pitch and subsequent fiber preparation by naphthalene polymers, affecting the yield of mesophase pitch and the quality of subsequent fiber, therefore, controlling the length of the alkyl chain also helps to prepare mesophase pitch of excellent quality, preferably, the alkyl chain length can be 1-5. In addition, since the preparation method of the present invention does not require high purity of raw materials, a mixture of unsubstituted naphthalene and alkyl-substituted naphthalene can also be used as the raw material, which makes the selection of raw materials more flexible, further reduces production costs and improves the utilization efficiency of raw materials.

[0043] In the scheme of the present invention, C 16 H 36 CIP-xAlCl 3 The molar ratio of the ionic liquid to the naphthalene compound is (1-5):20.

[0044] After experimental verification, it was found that the control C 16 H 36 CIP-xAlCl 3 When the molar ratio of the ionic liquid to the naphthalene compound satisfies the above range, it is helpful to further improve the yield of the prepared naphthalene oligomer. At the same time, within the above range, when other conditions remain unchanged, as C 16 H 36 CIP-2.0AlCl 3 The amount of ionic liquid increased, i.e. C 16 H 36 CIP-xAlCl 3 As the molar ratio of ionic liquid to naphthalene compound increases, C 16 H 36 CIP-2.0AlCl 3 The yield of naphthalene oligomers obtained by catalyzing naphthalene polymerization with ionic liquid as catalyst also gradually increases.

[0045] In the scheme of the present invention, the temperature of the polymerization reaction is 60-180°C.

[0046] Currently, AlCl 3 , HF / BF 3When a naphthalene compound is polymerized by a solid superacid, the polymerization temperature generally needs to be ≥100°C. 16 H 36 CIP-xAlCl 3 The polymerization reaction of naphthalene compounds catalyzed by ionic liquids can still obtain naphthalene polymers with a yield of ≥43.7% under mild conditions of 60°C-100°C, so the preparation method provided by the present invention provides an application approach of mild operating conditions for the synthesis of naphthalene polymers, and has application value in actual industrial production to a certain extent. In addition, when the temperature of the polymerization reaction is 100-180°C, the yield of naphthalene polymers is further increased. The inventors also found that, under other conditions unchanged, with the increase of the polymerization temperature, the yield of the naphthalene polymers obtained gradually increases. By controlling the temperature of the polymerization reaction to meet the above range, it is helpful to further improve the yield of the prepared naphthalene polymers.

[0047] In the scheme of the present invention, the polymerization reaction time is 0.5-6.5 hours.

[0048] When other catalysts are used to catalyze the polymerization of naphthalene compounds, the polymerization reaction time generally requires ≥ 2 hours. 16 H 36 CIP-xAlCl 3 Ionic liquid catalyzes naphthalene compounds, and naphthalene polymers with a yield of ≥66.5% can still be obtained within a reaction time of 0.5-2.0 h. Therefore, the preparation method provided by the present invention provides a new idea for continuous production and large-scale preparation of naphthalene polymers that can be prepared by a continuous reactor (such as a plug flow reactor). In addition, when the polymerization reaction time is 2.0-6.5 h, the yield of naphthalene polymers is further increased. The inventors also found that, under other conditions unchanged, as the polymerization reaction time increases, the yield of the obtained naphthalene polymers gradually increases. By controlling the polymerization reaction time to meet the above range, the yield of the prepared naphthalene polymers can be improved.

[0049] In the solution of the present invention, the stirring rate of the polymerization reaction is 150-250 r / min.

[0050] At the above stirring rate, C 16 H 36 CIP-xAlCl 3 The ionic liquid and the naphthalene compound are in full contact to ensure that C 16 H 36 CIP-xAlCl 3 A good uniform phase is formed between the ionic liquid and the naphthalene series compound, thereby increasing the yield of naphthalene oligomers and concentrating the molecular weight distribution.

[0051] In a specific embodiment, C 16 H 36 CIP-xAlCl 3 The preparation method of the ionic liquid comprises the following steps:

[0052] C 16 H 36 CIP and AlCl 3 mixing to obtain a mixture;

[0053] The mixture is reacted at 100-150°C for 1-10 hours to obtain C 16 H 36 CIP-xAlCl 3 Ionic liquids.

[0054] First, C 16 H 36 CIP and AlCl 3 Mixing to obtain a mixture, specifically, at room temperature (e.g., 0-35°C), C 16 H 36 CIP and AlCl 3 For one-time mixing, AlCl 3 Add C in batches 16 H 36 Then, the mixture is placed at 100-150°C for 1-10 hours to obtain C 16 H 36 CIP-xAlCl 3 Ionic liquids.

[0055] In one embodiment of the present invention, C 16 H 36 CIP-xAlCl 3 The ionic liquid can be prepared by accurately weighing 147.45 g (0.50 mol) of C 16 H 36 CIP and 133.34 g (1.00 mol) anhydrous AlCl 3 , that is, C 16 H 36 CIP and Anhydrous AlCl 3 The molar ratio is 1:2.0. First, C 16 H 36 CIP was placed in a 500 mL three-necked flask, and anhydrous AlCl was added in batches. 3 , each time anhydrous AlCl is added 3 Before you need to make C 16 H 36 CIP and previously added anhydrous AlCl3 A uniform phase is formed. 3 After the addition, the three-necked flask was placed in an oil bath and stabilized at 120 °C for 4 h to obtain C 16 H 36 CIP-2.0AlCl 3 Ionic liquids.

[0056] Furthermore, in order to promote the smooth progress of the reaction and prevent the water vapor in the air from affecting the anhydrous AlCl 3 and C 16 H 36 CIP-xAlCl 3 The influence of ionic liquids can make C 16 H 36 CIP-xAlCl 3 The preparation of the ionic liquid is carried out under the protection of an inert gas, and the inert gas includes at least one of nitrogen, argon and neon.

[0057] Similarly, in order to promote the smooth progress of the reaction and prevent the water vapor in the air from 16 H 36 CIP-xAlCl 3 Due to the influence of ionic liquids, the polymerization reaction can also be carried out under the protection of an inert gas, and the inert gas includes at least one of nitrogen, argon and neon.

[0058] In a specific embodiment, the polymerization reaction further includes a purification process, and the purification process includes:

[0059] The polymerization product obtained after the polymerization reaction contains a polymerization product and C 16 H 36 CIP-xAlCl 3 adding an organic solvent to the mixed product of the ionic liquid to obtain a mixed solution;

[0060] adding an alkali solution to the mixed solution, washing and separating to obtain a polymerization product containing naphthalene oligomers;

[0061] The polymerization product is subjected to reduced pressure distillation to obtain naphthalene oligomers.

[0062] In the present invention, first, a catalyst containing a polymer product and C 16 H 36 CIP-xAlCl 3 An organic solvent is added to the mixed product of the ionic liquid to completely dissolve the mixed product to obtain a mixed solution; an alkali solution is then added to the mixed solution to destroy the C 16 H 36 CIP-xAlCl 3The ionic liquid is then washed and separated to obtain a polymerization product rich in naphthalene oligomers, and the naphthalene oligomers are obtained by vacuum distillation. In specific implementation, deionized water can be used to wash until the mixed solution is neutral, and then the polymerization product containing naphthalene oligomers can be separated by a standing liquid separation method.

[0063] In addition, the mixed product obtained after the polymerization reaction is cooled to below 40°C before adding the organic solvent, which helps prevent the organic solvent from volatilizing in large quantities or even boiling violently. When using the alkali destruction method, the mixed solution can be placed in an ice bath to prevent the reaction heat from causing the organic solvent to boil violently.

[0064] In a specific embodiment of the present invention, the purification treatment can be cooling the reaction to below 40°C after completion, adding 127.40 g (1.50 mol) of dichloromethane to completely dissolve the mixed product; placing the three-necked flask in an ice water bath, slowly dropping a 2 mol / L sodium hydroxide aqueous solution therein, stirring continuously until the white precipitate disappears, washing with deionized water until the solution is neutral, and then allowing the solution to stand for separation to obtain a mixture containing naphthalene oligomers and CH 2 Cl 2 The solution containing naphthalene polymer and CH 2 Cl 2 The solution was rotary evaporated and vacuum dried to remove unreacted naphthalene and CH 2 Cl 2 , and finally naphthalene polymers are obtained.

[0065] Specifically, the organic solvent includes at least one of dichloromethane, chloroform, carbon tetrachloride, trichloroethane, chlorobenzene, benzene, toluene and xylene. The use of the above organic solvent can more fully dissolve the mixed product, help to purify and separate more thoroughly, and further improve the yield of the obtained naphthalene oligomer.

[0066] In the present invention, the alkaline solution includes at least one of sodium hydroxide and potassium hydroxide, and the concentration of the alkaline solution is 0.1-2 mol / L. The use of the alkaline solution can effectively destroy C 16 H 36 CIP-xAlCl 3 The ionic liquid can remove the ions more cleanly, which is beneficial to obtain naphthalene oligomers with higher quality. At the same time, the concentration of the alkaline solution is limited in the present invention, which can further promote the 16 H 36 CIP-xAlCl 3 The ionic liquid is removed cleanly, thereby improving the quality of naphthalene oligomers.

[0067] The technical solution of the present application will be further explained below in conjunction with specific embodiments. The experimental methods in the following embodiments that do not specify specific conditions are usually carried out under conventional conditions or under conditions recommended by the manufacturer. The reagents used are commercially available or available from public channels unless otherwise specified.

[0068] Embodiment 1:

[0069] This embodiment provides a method for preparing a naphthalene oligomer, comprising the following steps:

[0070] (1) Under nitrogen atmosphere, accurately weigh 147.45 g (0.50 mol) C 16 H 36 CIP and 133.34 g (1.00 mol) anhydrous AlCl 3 , that is, C 16 H 36 CIP and Anhydrous AlCl 3 The molar ratio is 1:2.0. First, C 16 H 36 CIP was placed in a 500 mL three-necked flask, and anhydrous AlCl was added in batches. 3 , each time anhydrous AlCl is added 3 Before you need to make C 16 H 36 CIP and previously added anhydrous AlCl 3 A uniform phase is formed. 3 After the addition, the three-necked flask was placed in an oil bath and stabilized at 120 °C under a nitrogen atmosphere for 4 h to obtain C 16 H 36 CIP-2.0AlCl 3 After the ionic liquid has cooled, pour it into a reagent bottle and store it in a 40°C oven for later use.

[0071] (2) Add 70.20 g (0.125 mol) of C into a three-necked flask maintained in a nitrogen atmosphere. 16 H 36 CIP-2.0AlCl 3 and 64.08 g (0.5 mol) of naphthalene, catalyze the polymerization of naphthalene for 5 h under the polymerization conditions of temperature of 150 ° C, pressure of 1 atm, and stirring rate of 200 r / min to obtain a mixed product. After the reaction is completed, cool to below 40 ° C, add 127.40 g (1.50 mol) of dichloromethane to completely dissolve the mixed product. Place the three-necked flask in an ice water bath, slowly add 2 mol / L sodium hydroxide aqueous solution to it, stir continuously until the white precipitate disappears, wash with deionized water until the solution is neutral, and then let the solution stand to separate to obtain a mixture containing naphthalene oligomers and CH2 Cl 2 The solution containing naphthalene polymer and CH 2 Cl 2 The solution was rotary evaporated and vacuum dried to remove unreacted naphthalene and CH 2 Cl 2 , and finally the naphthalene polymer was obtained, named (1).

[0072] Embodiment 2:

[0073] This embodiment provides a method for preparing a naphthalene oligomer. The specific steps can be referred to in Example 1, except that C is changed in step (1). 16 H 36 CIP and Anhydrous AlCl 3 The molar ratio of C 16 H 36 CIP-1.8AlCl 3 Ionic liquids, C 16 H 36 CIP-1.6AlCl 3 Ionic liquids, C 16 H 36 CIP-1.4AlCl 3 Ionic liquids and C 16 H 36 CIP-1.2AlCl 3 Ionic liquid. The above C 16 H 36 CIP-1.8AlCl 3 Ionic liquids, C 16 H 36 CIP-1.6AlCl 3 Ionic liquids, C 16 H 36 CIP-1.4AlCl 3 Ionic liquids and C 16 H 36 CIP-1.2AlCl 3 The naphthalene oligomers prepared by ionic liquids were named (2), (3), (4) and (5).

[0074] Embodiment 3:

[0075] This embodiment provides a method for preparing a naphthalene oligomer. The specific steps can be referred to in Example 1, except that C is changed in step (2). 16 H 36 CIP-2.0AlCl 3 The amount of ionic liquid used, i.e., changing C 16 H 36 CIP-2.0AlCl 3The molar ratio of ionic liquid to naphthalene was 0.100 mol, 0.075 mol, 0.050 mol, and 0.025 mol of C 16 H 36 CIP-2.0AlCl 3 Ionic liquid catalyzed naphthalene polymerization of 0.5 mol of naphthalene, and the prepared naphthalene polymers were named (6), (7), (8), and (9).

[0076] Embodiment 4:

[0077] This embodiment provides a method for preparing naphthalene polymers. The specific steps can be referred to in Example 1, except that the polymerization temperature in step (2) is changed to 180°C, 120°C, 90°C, and 60°C, respectively. The prepared naphthalene polymers are named (10), (11), (12), and (13).

[0078] Embodiment 5:

[0079] This embodiment provides a method for preparing naphthalene polymers. The specific steps can be referred to in Example 1, except that the naphthalene polymerization reaction time in step (2) is changed to 6.5 h, 3.5 h, 2 h, and 0.5 h, respectively. The prepared naphthalene polymers are named (14), (15), (16), and (17).

[0080] Comparative Example 1:

[0081] This comparative example provides a method for preparing a naphthalene oligomer. The specific steps can be referred to Example 1, except that 70.20 g (0.125 mol) of C 16 H 36 CIP-2.0AlCl 3 Replaced with 16.66 g (0.125 mol) anhydrous AlCl 3 The prepared naphthalene oligomer was named (18).

[0082] Comparative Example 2:

[0083] This comparative example provides a method for preparing a naphthalene oligomer. The specific steps can be referred to Example 1, except that 70.20 g (0.125 mol) of C 16 H 36 CIP-2.0AlCl 3 Replaced with 50.54 g (0.125 mol) Et 3 NHCl-2.0AlCl 3 The prepared naphthalene oligomer was named (19).

[0084] Comparative Example 3:

[0085] This comparative example provides a method for preparing a naphthalene oligomer. The specific steps can be referred to Example 1, except that 70.20 g (0.125 mol) of C 16 H 36 CIP-2.0AlCl 3 Replaced with 54.80 g (0.125 mol) C 9 H 14 ClN-2.0AlCl 3 The prepared naphthalene oligomer was named (20).

[0086] Comparative Example 4:

[0087] This comparative example provides a method for preparing a naphthalene oligomer. The specific steps can be referred to Example 1, except that 70.20 g (0.125 mol) of C 16 H 36 CIP-2.0AlCl 3 Replaced with 55.16 g (0.125 mol) BMIMCl-2.0AlCl 3 The prepared naphthalene oligomer was named (21).

[0088] Test example:

[0089] (1) The yields of the naphthalene oligomers (1) to (21) prepared in Examples 1 to 5 and Comparative Examples 1 to 4 were calculated, as shown in Table 1 and Table 2. The yield of the naphthalene oligomers was calculated by the following formula: (m2 / m1) × 100%; m1 refers to the mass of the naphthalene compound added to the polymerization reaction, and m2 refers to the mass of the naphthalene oligomers obtained.

[0090] (2) The ash contents of the naphthalene oligomers (1), (18) and (19) prepared in Example 1 and Comparative Examples 1-2 were measured in accordance with the method specified in the Petrochemical Industry Standard SHT 0422-2000 of the People's Republic of China for the determination of asphalt ash content. For details, see Table 2.

[0091] (3) The naphthalene oligomers (1), (18), (19), (20), and (21) prepared in Example 1 and Comparative Examples 1-4 were detected using a matrix-assisted laser desorption time-of-flight mass spectrometer (MALDI-TOF / TOF, Bruker rapiflexMALDI Tissuetyper). The mass spectra obtained were: Figure 1 , wherein the solvent used is CDCl 3 , the matrix is ​​DCTB, and the measured molecular weight range is 128-2000.

[0092] Table 1

[0093]

[0094] Table 2

[0095]

[0096] As shown in Table 1, the yield of naphthalene oligomer (1) is 85.2%, the yield of naphthalene oligomer (2) is 74.2%, the yield of naphthalene oligomer (3) is 59.6%, the yield of naphthalene oligomer (4) is 40.7%, and the yield of naphthalene oligomer (5) is 21.4%. Under the condition that other conditions remain unchanged, with the increase of C 16 H 36 CIP-xAlCl 3 As the value of x increases in ionic liquids, C 16 H 36 CIP-xAlCl 3 The yield of naphthalene oligomers obtained by catalyzing naphthalene polymerization with ionic liquid as catalyst also gradually increased; when x = 2.0, even if C 16 H 36 CIP-2.0AlCl 3 When ionic liquid is used as catalyst, the yield of naphthalene oligomers is the highest.

[0097] The yield of naphthalene oligomer (1) was 85.2%, the yield of naphthalene oligomer (6) was 82.7%, the yield of naphthalene oligomer (7) was 78.4%, the yield of naphthalene oligomer (8) was 73.8%, and the yield of naphthalene oligomer (9) was 70.1%. Under other conditions unchanged, with the increase of C 16 H 36 CIP-2.0AlCl 3 The amount of ionic liquid increased, C 16 H 36 CIP-2.0AlCl 3 The yield of naphthalene oligomers obtained by catalyzing naphthalene polymerization with ionic liquid as catalyst also gradually increased; 16 H 36 CIP-2.0AlCl 3 When the dosage of ionic liquid is 0.125 mol, the yield of naphthalene oligomer is the highest.

[0098] The yield of naphthalene oligomer (10) was 89.0%, the yield of naphthalene oligomer (1) was 85.2%, the yield of naphthalene oligomer (11) was 77.6%, the yield of naphthalene oligomer (12) was 59.5%, and the yield of naphthalene oligomer (13) was 43.7%. When other conditions remained unchanged, the yield of the obtained naphthalene oligomers gradually increased with the increase of the polymerization temperature. When the polymerization temperature was 180°C, the yield of the obtained naphthalene oligomers was the highest.

[0099] The yields of naphthalene oligomer (14) were 87.9%, naphthalene oligomer (1) was 85.2%, naphthalene oligomer (15) was 80.3%, naphthalene oligomer (16) was 73.7%, and naphthalene oligomer (17) was 66.4%. When other conditions remained unchanged, the yield of the obtained naphthalene oligomers increased with the increase of the naphthalene polymerization reaction time. When the naphthalene polymerization reaction time was 6.5 h, the yield of the obtained naphthalene oligomers was the highest.

[0100] As shown in Table 2, the yield of naphthalene oligomer (1) was 85.2%, the yield of naphthalene oligomer (18) was 49.9%, the yield of naphthalene oligomer (19) was 70.8%, the yield of naphthalene oligomer (20) was 74.2%, and the yield of naphthalene oligomer (21) was 80.2%. This indicates that the C 16 H 36 CIP-2.0AlCl 3 Ionic liquids are more effective than anhydrous AlCl in catalyzing naphthalene polymerization. 3 , Et 3 NHCl-2.0AlCl 3 , C 9 H 14 ClN-2.0AlCl 3 or BMIMCl-2.0AlCl 3 As a catalyst, it has a significant yield improvement effect. In addition, the ash content of naphthalene polymer (1) is 50 μg / g, the ash content of naphthalene polymer (18) is 730 μg / g, and the ash content of naphthalene polymer (19) is 30 μg / g; the ash content of naphthalene polymer (1) is significantly lower than that of naphthalene polymer (18), which meets the requirements of being a high-quality spinnable mesophase pitch. This shows that C 16 H 36 CIP-2.0AlCl 3 Ionic liquids are more effective than anhydrous AlCl in catalyzing naphthalene polymerization. 3 As a catalyst, it can significantly reduce the ash content of the prepared naphthalene polymer, thereby improving the quality of the spinnable mesophase pitch.

[0101] like Figure 1As shown, the molecular weight distribution of naphthalene polymer (1) is 192-576 Da, mainly including dimers to tetramers of naphthalene, among which dimers of naphthalene are the main ones, and also include trace amounts of other polymers; the molecular weight distribution of naphthalene polymer (18) is 192-1088 Da, mainly including dimers to octamers of naphthalene; the molecular weight distribution of naphthalene polymer (19) is 192-1088 Da, mainly including dimers to octamers of naphthalene; the molecular weight distribution of naphthalene polymer (20) is 192-960 Da, mainly including dimers to heptamers of naphthalene; the molecular weight distribution of naphthalene polymer (21) is 240-1088 Da, mainly including dimers to octamers of naphthalene. This shows that the C 16 H 36 CIP-2.0AlCl 3 Ionic liquids are more effective than anhydrous AlCl in catalyzing naphthalene polymerization. 3 , Et 3 NHCl-2.0AlCl 3 , C 9 H 14 ClN-2.0AlCl 3 or BMIMCl-2.0AlCl 3 As a catalyst, the obtained naphthalene oligomers have a significantly narrower molecular weight distribution.

[0102] In summary, the present invention provides a method for preparing naphthalene oligomers, using C 16 H 36 CIP-xAlCl 3 Ionic liquids catalyze the polymerization of naphthalene compounds to obtain naphthalene polymers, which can effectively improve the yield of naphthalene polymers, and the prepared naphthalene polymers have a narrower molecular weight distribution and lower ash content. On this basis, by controlling the value of x, C 16 H 36 CIP-xAlCl 3 The molar ratio of ionic liquid to naphthalene compounds, the temperature and time of the polymerization reaction can further improve the yield of naphthalene polymers and enable the prepared naphthalene polymers to have a narrower molecular weight distribution, thereby providing high-quality precursors for the preparation of mesophase asphalt.

[0103] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions described in the above embodiments can still be modified, or some or all of the technical features can be replaced by equivalents. However, these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a naphthalene oligomer, characterized in that: The steps include: Using C 16 H 36 CIP-xAlCl3 ionic liquid catalyzes the polymerization reaction of naphthalene compounds to obtain naphthalene oligomers; The C 16 H 36 The general structural formula of CIP-xAlCl3 ionic liquid is shown in Formula 1: Formula 1 In formula 1, 1<x≤2.

2. The preparation method according to claim 1, characterized in that: The naphthalene-based compounds include alkyl-substituted naphthalene and / or unsubstituted naphthalene.

3. The preparation method according to claim 1 or 2, characterized in that: The C 16 H 36 The molar ratio of the CIP-xAlCl3 ionic liquid to the naphthalene compound is (1-5):

20.

4. The preparation method according to any one of claims 1 to 3, characterized in that The polymerization temperature is 60-180°C.

5. The preparation method according to any one of claims 1 to 4, characterized in that: The polymerization reaction time is 0.5-6.5 hours.

6. The preparation method according to any one of claims 1 to 5, characterized in that: The stirring rate of the polymerization reaction is 150-250 r / min.

7. The preparation method according to any one of claims 1 to 6, characterized in that: The C 16 H 36 The preparation method of CIP-xAlCl3 ionic liquid comprises the following steps: C 16 H 36 CIP and AlCl3 are mixed to obtain a mixture; The mixture is reacted at 100-150° C. for 1-10 hours to obtain the C 16 H 36 CIP-xAlCl3 ionic liquid.

8. The preparation method according to claim 7, characterized in that: The C 16 H 36 The preparation of CIP-xAlCl3 ionic liquid is carried out under the protection of an inert gas, wherein the inert gas includes at least one of nitrogen, argon and neon; And / or, the polymerization reaction is carried out under the protection of an inert gas, wherein the inert gas comprises at least one of nitrogen, argon and neon.

9. The preparation method according to any one of claims 1 to 8, characterized in that: The polymerization reaction further includes a purification process, and the purification process includes: The polymerization product obtained after the polymerization reaction contains a polymerization product and C 16 H 36 An organic solvent is added to the mixed product of CIP-xAlCl3 ionic liquid to obtain a mixed solution; adding an alkali solution to the mixed solution, washing and separating to obtain a polymerization product containing naphthalene oligomers; The polymerization product is subjected to reduced pressure distillation to obtain the naphthalene oligomer.

10. The preparation method according to claim 9, characterized in that: The organic solvent comprises at least one of dichloromethane, chloroform, carbon tetrachloride, trichloroethane, chlorobenzene, benzene, toluene and xylene; and / or, The alkaline solution includes at least one of sodium hydroxide and potassium hydroxide; the concentration of the alkaline solution is 0.1-2 mol / L.

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