A process for the production of mesophase pitch by the hydrogenation of a component of coal tar pitch

Abstract

The application discloses a method for preparing mesophase pitch by hydrogenating coal tar pitch components, which comprises the following steps: obtaining three components A, B and C or four components A, B, C and D or five components A, B, C, D and E from coal tar pitch by using a step-by-step extraction method; adding a hydrogen-donating solvent and a catalyst into heavy components separated from the coal tar pitch, and performing hydrogenation treatment to obtain hydrogenated heavy components; mixing the hydrogenated heavy components and unhydrogenated components according to a certain proportion to obtain modified pitch; and performing thermal polycondensation reaction on the modified pitch to obtain mesophase pitch. The modified pitch has a suitable molecular composition for preparing mesophase pitch, the molecular weight range is reasonable and the distribution is concentrated, the prepared mesophase pitch has high anisotropy content and good optical structure, and is rich in wide-range flow line structure, so that the mesophase pitch is a high-quality precursor for preparing carbon fiber and needle coke and other carbon materials.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of deep processing of coal tar pitch, and particularly relates to a method for preparing mesophase pitch by hydrogenation of coal tar pitch components. BACKGROUND

[0002] Heavy aromatic compounds can form mesophase pitch through liquid-phase carbonization, which not only has anisotropic optical properties, but also has certain rheological properties. The regularly arranged planar aromatic macromolecules in mesophase pitch are easy to be stacked and arranged according to the structure of graphite under high-temperature heat treatment conditions, so that the mesophase pitch-based carbon material has many excellent properties. Therefore, mesophase pitch is an excellent precursor for preparing high-elasticity carbon fibers, high-specific-surface-area activated carbon, ultra-high-power graphite electrodes and other advanced functional materials.

[0003] Coal tar pitch has a large output, low price and high aromatic content, and is widely used for preparing mesophase pitch. However, coal tar pitch has a complex composition, high impurity content and contains quinoline insoluble or high-reactivity components, which are easy to be excessively condensed in the carbonization process, and are not conducive to the formation of mesophase pitch molecules.

[0004] At present, in order to improve the hydrogen-carbon ratio, remove quinoline insoluble (QI) and adjust the molecular composition, the method for preparing mesophase pitch mainly uses hydrogenation modification for coal tar pitch raw materials. For example, patent CN110699107A discloses a method for preparing mesophase pitch by hydrogenation catalysis-hydrogen supply treatment using coal tar pitch as raw material. The method has a moderate softening point of mesophase pitch and high mesophase content, but the preparation method needs secondary hydrogenation of the raw material, the process is complex, a large amount of hydrogen supply solvent is used, the hydrogenation depth is not easy to control, and the preparation cost is high.

[0005] In the hydrogenation reaction process, because the molecular composition of coal tar pitch is widely distributed, the light components are easy to be excessively hydrogenated, and the heavy components are insufficiently hydrogenated, which leads to problems such as low yield of mesophase and non-ideal optical structure. There are few patents related to accurate adjustment of the composition of coal tar pitch hydrogenation raw materials and prevention of excessive hydrogenation. SUMMARY

[0006] This section is intended to summarize some aspects of the embodiments of the present application and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract and title of the specification of the present application in order to avoid obscuring the purpose of this section, the abstract and the title, and such simplifications or omissions cannot be used to limit the scope of the present application.

[0007] In view of the above and / or problems existing in the prior art, the present application is proposed.

[0008] Therefore, the present application aims at overcoming the deficiencies in the prior art, and provides a method for preparing mesophase pitch by hydrogenation of coal tar pitch components, wherein different components with different properties are obtained by step-by-step extraction of the coal tar pitch, the heavy components are mixed with the non-hydrogenated components in a certain proportion after hydrogenation, the molecular composition of the pitch is changed, the molecular weight distribution is appropriate, the naphthenic structure and aliphatic side chains are increased, the stable growth and fusion of mesophase small balls are promoted, the mesophase pitch prepared has a high anisotropic phase content, and mainly has a wide-area streamline structure.

[0009] To solve the above technical problems, the present application provides the following technical scheme: a method for preparing mesophase pitch by hydrogenation of coal tar pitch components, comprising,

[0010] Step 1: Step 2: Step 3: Step 4: Step 5:

[0011] Step 6: Step 7: Step 8: Step 9: Step 10:

[0012] Step 11: Step 12: Step 13: Step 14: Step 15:

[0013] Step 16: Step 17: Step 18: Step 19: Step 20:

[0014] As a preferred scheme of the method, in the step of step-by-step extraction of the coal tar pitch with different extractants, the step-by-step extraction process comprises the following steps:

[0015] Step 1: Step 2: Step 3: Step 4: Step 5:

[0016] Step 6: Step 7: Step 8: Step 9: Step 10:

[0017] Step 11: Step 12: Step 13: Step 14: Step 15:

[0018] In the above steps, the step-by-step extraction process adopts four extractants to obtain four components A, B, C and D in turn; or five extractants to obtain five components A, B, C, D and E in turn.

[0019] As a preferred scheme of the method, the extractants are selected from n-hexane, n-heptane, toluene, pyridine, chloroform, acetone, tetrahydrofuran, quinoline, anthracene oil, wash oil and naphthalene oil.

[0020] As a preferred solution of the method, the stepwise extraction is carried out under the conditions of a mass ratio of the extractant to the pitch of 5:1-20:1 and stirring for 50-90 min at a temperature of 50-120°C.

[0021] As a preferred solution of the method, the hydrogen-donating solvent is one or a mixture of two or more of dihydropyrene, dihydroanthracene, tetrahydroanthracene, dihydronaphthalene, tetrahydronaphthalene, dihydrophenanthrene, octahydrophenanthrene, tetrahydroquinoline, a coal direct liquefaction hydrogen-donating solvent, and a coal tar fraction hydrogenation product.

[0022] The catalyst is one or a mixture of two or more of Fe2O3, FeS2, ZnO, ZnCl2, SnO2, Co, Mo and Ni catalysts.

[0023] As a preferred solution of the method, the hydrogen-donating solvent is 5wt%-60wt% of the mass of the heavy component.

[0024] The hydrotreatment is carried out under the conditions of 2-8 MPa of hydrogen or nitrogen and a temperature of 340-440°C.

[0025] As a preferred solution of the method, the hydrogenated heavy component and the unhydrogenated component are mixed under the conditions of a mass ratio of the hydrogenated heavy component to the unhydrogenated component of 20%-60%:20%-60%:10%-30%.

[0026] When the coal tar pitch is extracted into three components, the mass ratio of the unhydrogenated component and the hydrogenated heavy component is 10%-20%:20-50%:10%-40%.

[0027] When the coal tar pitch is extracted into four components, the mass ratio of the unhydrogenated component and the hydrogenated heavy component is 10%-20%:20-50%:10%-30%:10%-20%.

[0028] When the coal tar pitch is extracted into five components, the mass ratio of the unhydrogenated component and the hydrogenated heavy component is 10%-20%:20-50%:10%-30%:10%-20%:10%-20%.

[0029] As a preferred solution of the method, the thermal polycondensation is carried out at a temperature increasing rate of 0.5°C / min-5°C / min to a temperature of 320-480°C and a holding time of 3-15 h.

[0030] As a preferred solution of the method, the modified pitch is subjected to the thermal polycondensation under the conditions of a stirring rate of 50-500 r / min and an initial nitrogen pressure of 0.1-5 MPa.

[0031] As a preferred solution of the method, the mesophase pitch product has an anisotropic phase content of ≥80%, a wide-range flow line optical texture content of ≥60%, and a softening point of 120-380℃.

[0032] The present application has the following advantages:

[0033] (1) The present application provides a method for preparing high-quality mesophase pitch by using coal tar pitch as raw material, separating components by solvent extraction, hydrogenating heavy components, and adjusting the composition of the raw material by blending and modification. The prepared mesophase pitch has a suitable softening point, high anisotropic phase content, and rich ideal optical structure, and the method is simple and feasible.

[0034] (2) The present application separates components with different properties by organic solvent extraction of coal tar pitch, which can reduce impurities and high-reactivity substances in the raw material, facilitate smooth heat polycondensation reaction, inhibit coking, and improve the thermal stability of the system.

[0035] (3) The present application hydrogenates the heavy components of coal tar pitch to obtain hydrogenated heavy components, introduces naphthenic structure and alkyl side chains, releases active hydrogen in the heat polycondensation reaction, effectively inhibits excessive polycondensation of aromatic molecules, and facilitates the stable growth of mesophase small balls, which is conducive to the formation of wide-range mesophase.

[0036] (4) The present application obtains modified pitch by blending the unhydrogenated components and hydrogenated heavy components, adjusts the molecular weight distribution, introduces naphthenic structure and alkyl side chains, adjusts the heat polycondensation reaction rate, promotes the generation and development of mesophase, and realizes the improvement of mesophase content and the improvement of optical texture. BRIEF DESCRIPTION OF DRAWINGS

[0037] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor. Among them:

[0038] Figure 1 The polarized light microscopic morphology of the mesophase pitch prepared in Example 1 of the present application.

[0039] Figure 2 The polarized light microscopic morphology of the mesophase pitch prepared in Example 2 of the present application.

[0040] Figure 3 The polarized light microscopic morphology of the mesophase pitch prepared in Example 3 of the present application.

[0041] Figure 4The process flow chart of the method for preparing mesophase pitch by hydrogenation of the coal tar pitch component in the embodiment of the present application is shown in the following. DETAILED DESCRIPTION

[0042] In order to make the above objectives, characteristics and advantages of the present application more apparent, the specific embodiments of the present application will be described in detail below with reference to the embodiments of the present application.

[0043] In the following description, a large number of specific details are set forth in order to provide a thorough understanding of the present application, but the present application can also be implemented in other manners different from those described herein, and those skilled in the art can make similar generalizations without departing from the concept of the present application, so the present application is not limited to the specific embodiments disclosed below.

[0044] Secondly, the "one embodiment" or "embodiment" referred to herein means that the specific features, structures or characteristics can be included in at least one implementation of the present application. The "in one embodiment" appearing in different places in the present specification does not mean the same embodiment, nor is it an embodiment that is independent or alternative to other embodiments.

[0045] Embodiment 1

[0046] The present embodiment provides a method for preparing mesophase pitch by hydrogenation of a coal tar pitch component, and the process flow chart is shown in the following Figure 4 , which comprises the following steps:

[0047] (1) 100 g of coal tar pitch and 500 g of n-heptane are placed in a beaker, stirred for 50 min at 40℃ in a water bath, and then separated to obtain a residue 1 and an upper liquid. The obtained extraction liquid is subjected to reduced pressure distillation to remove the organic solvent, and component A is obtained;

[0048] The residue 1 after vacuum drying for 24 h is placed in a beaker with 400 g of toluene, stirred for 60 min at 60℃ in a water bath, and then separated to obtain a residue 2 and an upper liquid. The obtained extraction liquid is subjected to reduced pressure distillation to remove the organic solvent, and component B is obtained;

[0049] The residue 2 after vacuum drying for 24 h is placed in a beaker with 200 g of tetrahydrofuran, stirred for 60 min at 70℃ in a water bath, and then separated to obtain a residue 3 and an upper liquid. The obtained extraction liquid is subjected to reduced pressure distillation to remove the organic solvent, and component C is obtained;

[0050] The residue 3 after vacuum drying for 24 h is placed in a beaker with 200 g of quinoline, stirred for 60 min at 70℃ in a water bath, and then separated to obtain a residue 4 and an upper liquid. The obtained extraction liquid is subjected to reduced pressure distillation to remove the organic solvent, and component D is obtained. The residue 4 after vacuum drying for 24 h obtains component E;

[0051] (2) Take 40 g of component D, 6 g of tetrahydronaphthalene and 0.04 g of cobalt-molybdenum catalyst into a reaction kettle, the initial hydrogen pressure is 4 MPa, the stirring speed is 100 rpm, the temperature is raised to 390 ℃ at a rate of 1.5 ℃ / min, and after 1 h of constant temperature, it is cooled to room temperature to obtain hydrogenated component D1;

[0052] Take 40 g of component E, 4 g of tetrahydronaphthalene and 0.03 g of cobalt-molybdenum catalyst into a reaction kettle, the initial hydrogen pressure is 4 MPa, the stirring speed is 100 rpm, the temperature is raised to 410 ℃ at a rate of 1.5 ℃ / min, and after 1 h of constant temperature, it is cooled to room temperature to obtain hydrogenated component E1;

[0053] (3) Take 5 g of component A, 12.5 g of component B, 15 g of component C, 10 g of hydrogenated component D1 and 7.5 g of hydrogenated component E1 into a beaker, and stir at a strong magnetic force for 30 min in a water bath at 90 ℃, and then cool to room temperature to obtain modified asphalt;

[0054] (4) Put the modified asphalt into a reaction kettle, the initial nitrogen pressure is 0.5 MPa, the temperature is raised to 375 ℃ at a rate of 1.5 ℃ / min, and after 8 h of constant temperature, the mesophase pitch is obtained.

[0055] The polarized light microscopy morphology of the prepared mesophase pitch is shown in Figure 1 The anisotropic phase content and optical structure composition measurement results are shown in Table 1.

[0056] Example 2

[0057] The present embodiment provides a method for preparing mesophase pitch by hydrogenation of coal tar pitch components, comprising the following steps:

[0058] (1) Put 100 g of coal tar pitch and 500 g of n-hexane into a beaker, stir for 40 min in a water bath at 40 ℃, and then separate the residue 1 and the upper liquid, remove the organic solvent from the obtained extraction liquid by reduced pressure distillation to obtain component A;

[0059] Put the residue 1 and 400 g of toluene into a beaker, stir for 40 min in a water bath at 60 ℃, and then separate the residue 2 and the upper liquid, remove the organic solvent from the obtained extraction liquid by reduced pressure distillation to obtain component B;

[0060] Put the residue 2 and 300 g of chloroform into a beaker, stir for 40 min in a water bath at 65 ℃, and then separate the residue 3 and the upper liquid, remove the organic solvent from the obtained extraction liquid by reduced pressure distillation to obtain component C;

[0061] The extract 3 and 200 g of pyridine were placed in a beaker, stirred at 70°C in a water bath for 50 min, and then separated into the residue 4 and the upper liquid. The obtained extract liquid was distilled under reduced pressure to remove the organic solvent to obtain component D. The residue 4 was vacuum dried for 24 h to obtain component E.

[0062] (2) 40 g of component E, 2 g of dihydroanthracene and 0.03 g of Fe2O3 catalyst were placed in a reaction kettle, the initial hydrogen pressure was 3 MPa, the stirring speed was 100 r / min, the temperature was raised to 400°C at a rate of 1.5°C / min, and then cooled to room temperature after constant temperature for 1 h to obtain hydrogenated component E1.

[0063] (3) 7.5 g of component A, 10 g of component B, 15 g of component C, 10 g of component D and 7.5 g of hydrogenated component E1 were placed in a beaker, stirred at 90°C in a water bath for 30 min, and then cooled to room temperature to obtain a modified asphalt.

[0064] (4) The modified asphalt was placed in a reaction kettle, the initial nitrogen pressure was 0.5 MPa, the temperature was raised to 375°C at a rate of 1.5°C / min, and then constant temperature for 8 h to obtain a mesophase pitch.

[0065] The polarized light microscopy morphology of the prepared mesophase pitch is shown in Figure 2 The anisotropic phase content and optical structure composition determination results are shown in Table 1.

[0066] Example 3

[0067] The present embodiment provides a method for preparing mesophase pitch by hydrogenation of coal tar pitch components, comprising the following steps:

[0068] (1) 100 g of coal tar pitch and 500 g of n-hexane were placed in a beaker, stirred at 40°C in a water bath for 40 min, and then separated into the residue 1 and the upper liquid. The obtained extract liquid was distilled under reduced pressure to remove the organic solvent to obtain component A.

[0069] The residue 1 and 400 g of toluene were placed in a beaker, stirred at 60°C in a water bath for 40 min, and then separated into the residue 2 and the upper liquid. The obtained extract liquid was distilled under reduced pressure to remove the organic solvent to obtain component B.

[0070] The residue 2 and 300 g of chloroform were placed in a beaker, stirred at 65°C in a water bath for 40 min, and then separated into the residue 3 and the upper liquid. The obtained extract liquid was distilled under reduced pressure to remove the organic solvent to obtain component C.

[0071] The extract 3 and 200g quinoline are placed in a beaker, and after stirring at 70℃ in a water bath for 50min, the residue 4 and the upper liquid are separated, the obtained extract liquid is distilled under reduced pressure to remove the organic solvent to obtain component D, and the residue 4 is vacuum dried for 24h to obtain component E;

[0072] (2) 40g component D, 4g tetrahydronaphthalene and 0.02g cobalt-molybdenum catalyst are placed in a reaction kettle, the initial hydrogen pressure is 5MPa, the stirring speed is 100r / min, the temperature is raised to 400℃ at a rate of 1.5℃ / min, and after constant temperature for 1h, it is cooled to room temperature to obtain hydrogenated component D1;

[0073] (3) 10g component A, 17.5g component B, 15g component C and 11.5g hydrogenated component D1 are placed in a beaker, and after stirring at 90℃ in a water bath for 15min, it is cooled to room temperature to obtain modified asphalt;

[0074] (4) The modified asphalt is placed in a reaction kettle, the initial nitrogen pressure is 0.5MPa, the temperature is raised to 375℃ at a rate of 1.5℃ / min, and after constant temperature for 7h, it is cooled to room temperature to obtain mesophase pitch.

[0075] The polarized light microscopy morphology of the prepared mesophase pitch is shown in Figure 3 The anisotropic phase content and optical structure composition determination results are shown in Table 1.

[0076] Table 1: Content and optical structure composition of mesophase pitch prepared in Examples 1-3

[0077]

[0078] The method for preparing mesophase pitch by hydrogenation of coal tar pitch components provided by the application provides a controllable new path for preparing high-value-added mesophase pitch from coal tar pitch by step-by-step extraction of coal tar pitch and hydrogenation of heavy components to a suitable depth.

[0079] It should be noted that the above examples are only used to illustrate the technical solutions of the application and are not limiting, and although the application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the application can be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the application, and all should be included in the scope of the application.

Claims

1. A method for preparing mesophase pitch by hydrogenation of coal tar pitch components, characterized in that: include, Coal tar pitch was extracted stepwise with different extractants to obtain three components A, B, and C; or four components A, B, C, and D; or five components A, B, C, D, and E. Add one or more of components B, C, D or E to a hydrogen-donating solvent, mix with a catalyst, and then hydrogenate the heavy component to obtain the hydrogenated heavy component. Modified asphalt is obtained by mixing hydrogenated heavy components and non-hydrogenated components; Modified asphalt is thermally polycondensed to obtain mesophase asphalt.

2. The method as described in claim 1, characterized in that: The stepwise extraction of coal tar pitch using different extractants includes... Extractant a was added to coal tar pitch. After extraction, the mixture was allowed to stand and the extract residue 1 and the supernatant were separated. The extract was then subjected to vacuum distillation to recover extractant a and obtain component A. After vacuum drying of 1 to constant weight, it was mixed with extractant b. After extraction, the mixture was allowed to stand and 2 was separated from the supernatant. The extract was then subjected to vacuum distillation to recover extractant b and obtain component B. After vacuum drying of the residue 2 to constant weight, it was mixed with extractant c. After extraction, the residue and supernatant were separated and the extract was obtained. Extractant c was recovered by vacuum distillation to obtain component C. In the above steps, when four extractants are used in the stepwise extraction process, four components A, B, C and D are obtained in sequence; when five extractants are used, five components A, B, C, D and E are obtained in sequence.

3. The method as described in claim 2, characterized in that: The extractant is selected from hexane, heptane, toluene, pyridine, chloroform, acetone, tetrahydrofuran, quinoline, anthracene oil, wash oil, and naphthalene oil.

4. The method as described in claim 2 or 3, characterized in that: The stepwise extraction process involves an extractant to asphalt mass ratio of 5:1 to 20:1, and extraction conditions of stirring for 50 to 90 minutes at a temperature of 50°C to 120°C.

5. The method as described in claim 1, characterized in that: The hydrogen-donating solvent is one or a mixture of two or more of the following: dihydropyrene, dihydroanthracene, tetrahydroanthracene, dihydronaphthalene, tetrahydronaphthalene, dihydrophenanthrene, octahydrophenanthrene, and tetrahydroquinoline. The catalyst is one or a mixture of two or more of the following: Fe2O3, FeS2, ZnO, ZnCl2, SnO2, Co, Mo, and Ni catalysts.

6. The method as described in claim 5, characterized in that: The hydrogen-donating solvent is 5 wt% to 60 wt% of the heavy component. Hydrogenation is performed under hydrogen or nitrogen conditions at pressures of 2 MPa to 8 MPa, at temperatures of 340°C to 440°C.

7. The method as described in claim 1, characterized in that: The process involves mixing the hydrogenated heavy component and the unhydrogenated component, wherein... When coal tar pitch is separated into three components, the mass ratio of the unhydrogenated component to the hydrogenated heavy component is 10%–20%: 20–50%: 10%–40%. When coal tar pitch is separated into four components, the mass ratio of the unhydrogenated component to the hydrogenated heavy component is 10%–20%: 20–50%: 10%–30%: 10%–20%. When coal tar pitch is separated into 5 components, the mass ratio of the unhydrogenated component to the hydrogenated heavy component is 10%–20%: 20–50%: 10%–30%: 10%–20%: 10%–20%.

8. The method as described in claim 1, characterized in that: The thermal polycondensation process involves heating to 320℃ to 480℃ at a heating rate of 0.5℃ / min to 5℃ / min, and holding at that temperature for 3h to 15h.

9. The method as described in claim 1, characterized in that: The modified asphalt is subjected to thermal polycondensation, wherein the stirring rate is 50-500 r / min and the initial nitrogen pressure is 0.1 MPa-5 MPa.

10. The method as described in claim 1, characterized in that: The mesophase pitch product is an anisotropic phase content ≥80%, a wide-area streamline optical texture content ≥60%, and a softening point of 120~380℃.

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