CN116536070A - Method for preparing mesophase pitch by hydrogenating coal tar pitch components - Google Patents

Abstract

The invention discloses a method for preparing mesophase pitch by hydrogenating coal tar pitch components, which comprises the steps of sequentially obtaining A, B and C components or A, B, C and D components or A, B, C, D and E components from coal tar pitch by adopting a progressive extraction method; adding a hydrogen-supplying solvent and a catalyst into the heavy components separated from the coal tar pitch, and carrying out hydrotreatment to obtain hydrogenated heavy components; mixing the hydrogenated heavy component and the unhydrogenated component according to a certain proportion to obtain modified asphalt; and performing thermal condensation polymerization on the modified asphalt to obtain mesophase asphalt. The modified asphalt provided by the invention has a molecular composition suitable for preparing mesophase asphalt, the molecular weight range is reasonable, the distribution is concentrated, the anisotropic content in the prepared mesophase asphalt is high, the optical structure is good, the modified asphalt is rich in a wide-area streamline structure, and the modified asphalt is a high-quality precursor for preparing carbon materials such as carbon fibers, needle coke and the like.

Description

A method for preparing mesophase pitch by hydrogenation of coal tar pitch components

technical field

The invention belongs to the field of deep processing of coal tar pitch, and in particular relates to a method for preparing mesophase pitch through hydrogenation of coal tar pitch components.

Background technique

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 stack and arrange according to the structure of graphite under high-temperature heat treatment conditions, which makes mesophase pitch-based carbon materials have many excellent properties. Therefore, mesophase pitch is an excellent precursor for the preparation of highly elastic carbon fibers, high specific surface area activated carbons, ultrahigh power graphite electrodes, and other advanced functional materials.

Coal tar pitch is widely used in the preparation of mesophase pitch because of its large output, low price and high aromatic content. However, coal tar pitch has a complex composition, high impurity content, and contains quinoline insolubles or highly reactive components, which are prone to excessive polycondensation during the carbonization process, which is not conducive to the formation of mesophase pitch molecules.

At present, in order to improve the hydrogen-to-carbon ratio, remove quinoline insolubles (QI) and adjust the molecular composition, the method of preparing mesophase for the modification of coal tar pitch raw materials is mainly hydrogenation modification. For example, the patent CN110699107A discloses a method of using coal tar pitch as a raw material to prepare mesophase pitch through hydrogen catalysis-hydrogen supply treatment. The method prepares mesophase pitch with moderate softening point and high content of mesophase, but the preparation method requires the raw material Secondary hydrogenation, the process is complicated and a large amount of hydrogen-donating solvent is used, it is difficult to control the depth of hydrogenation, and the preparation cost is high.

During the hydrogenation reaction, due to the wide molecular composition distribution of coal tar pitch, the light components are easily over-hydrogenated, while the heavy components are not hydrogenated deeply enough, resulting in low yield of mesophase and unsatisfactory optical structure. question. There are few patents on the precise adjustment of raw material composition and the prevention of excessive hydrogenation in the hydrogenation of coal tar pitch.

Contents of the invention

The purpose of this section is to outline some aspects of embodiments of the invention and briefly describe some preferred embodiments. Some simplifications or omissions may be made in this section, as well as in the abstract and titles of this application, to avoid obscuring the purpose of this section, abstract and titles, and such simplifications or omissions should not be used to limit the scope of the invention.

In view of the problems mentioned above and/or in the prior art, the present invention is proposed.

Therefore, the object of the present invention is to overcome the deficiencies in the prior art and provide a method for preparing mesophase pitch by hydrogenation of coal tar pitch components, by extracting coal tar pitch step by step to obtain components of different properties, wherein The heavy component is mixed with the non-hydrogenated component according to a certain ratio after hydrogenation, thereby changing the molecular composition of the asphalt, making the molecular weight distribution suitable, increasing the naphthenic structure and aliphatic side chain, and promoting the stable growth and fusion of mesophase globules. , the prepared mesophase pitch has a high content of anisotropic phase and mainly has a wide-area streamlined structure.

In order to solve the above technical problems, the present invention provides the following technical scheme: a method for preparing mesophase pitch by hydrogenating coal tar pitch components, comprising:

The coal tar pitch is extracted step by step 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;

Adding a hydrogen-donating solvent to one or more of the B, C, D or E components, mixing with the catalyst, and hydrotreating to obtain hydrogenated heavy components;

Mix hydrogenated heavy components and unhydrogenated components to obtain modified bitumen;

After the modified asphalt is thermally condensed, the mesophase asphalt is obtained.

As a preferred version of the method of the present invention, wherein: the coal tar pitch is extracted step by step with different extractants, including,

Adding extractant a to the coal tar pitch, standing still after extraction and separating the raffinate 1 and the supernatant, obtaining the extract and recovering the extractant a by vacuum distillation to obtain component A;

The raffinate 1 is vacuum-dried to a constant weight and then mixed with the extractant b. After extraction, the raffinate 2 and the supernatant are separated to obtain the extract and the extractant b is recovered by vacuum distillation to obtain component B;

The raffinate 2 was vacuum-dried to a constant weight, mixed with the extractant c, left standing after extraction, and the raffinate and supernatant were separated to obtain the extract, and the extractant c was recovered by vacuum distillation to obtain component C.

In the above steps, four kinds of extractants are used to sequentially obtain four components A, B, C and D in the step-by-step extraction process; five kinds of extractants are used to sequentially obtain five components A, B, C, D and E.

As a preferred version of the method of the present invention, wherein: the extractant is selected from n-hexane, n-heptane, toluene, pyridine, chloroform, acetone, tetrahydrofuran, quinoline, anthracene oil, washing oil and naphthalene oil.

As a preferred version of the method of the present invention, wherein: the step-by-step extraction, wherein the mass ratio of extractant to asphalt is 5:1 to 20:1, the extraction conditions are: at a temperature of 50°C to 120°C Stir for 50min to 90min under the same conditions.

As a preferred version of the method of the present invention, wherein: the hydrogen-donating solvent is dihydropyrene, dihydroanthracene, tetrahydroanthracene, dihydronaphthalene, tetrahydronaphthalene, dihydrophenanthrene, octahydrophenanthrene, tetrahydro One or more mixtures of quinoline, coal direct liquefaction hydrogen-donating solvent, and coal tar fraction hydrogenation products;

The catalyst is one or a mixture of two or more of Fe ₂ O ₃ , FeS ₂ , ZnO, ZnCl ₂ , SnO ₂ , Co, Mo and Ni catalysts.

As a preferred solution of the method of the present invention, wherein: the hydrogen-donating solvent is 5wt% to 60wt% of the weight of the heavy component;

The hydrogenation treatment is carried out under the condition of 2MPa～8MPa hydrogen or nitrogen, and the temperature is 340℃～440℃.

As a preferred version of the method of the present invention, wherein: the hydrogenated heavy components and unhydrogenated components are mixed, wherein,

When the coal tar pitch is extracted into three components, the mass ratio of the unhydrogenated component and the hydrogenated heavy component is 10% to 20%: 20 to 50%: 10% to 40%;

When the coal tar pitch is extracted into four components, the mass ratio of the unhydrogenated component and the hydrogenated heavy component is 10% to 20%: 20 to 50%: 10% to 30%: 10% to 20%;

When coal tar pitch is extracted into 5 components, the mass ratio of unhydrogenated component and hydrogenated heavy component is 10%～20%:20～50%:10%～30%:10%～20%: 10% to 20%.

As a preferred solution of the method of the present invention, wherein: the thermal polycondensation process is to raise the temperature to 320°C-480°C at a heating rate of 0.5°C/min-5°C/min, and the holding time is 3h-15h.

As a preferred version of the method of the present invention, wherein: the modified asphalt is thermally polycondensed, wherein the stirring rate is 50-500 r/min, and the initial nitrogen pressure is 0.1 MPa-5 MPa.

As a preferred solution of the method of the present invention, wherein: the mesophase pitch product is an intermediate phase with an anisotropic phase content ≥ 80%, a wide-area streamlined optical texture content ≥ 60%, and a softening point of 120-380°C. phase asphalt.

Beneficial effects of the present invention:

(1) The present invention proposes a method for preparing high-quality mesophase pitch by using coal tar pitch as a raw material, separating components through solvent extraction, hydrogenating heavy components, and adjusting the composition of raw materials by mixing and modifying; The mesophase pitch has a suitable softening point, high content of anisotropic phase, rich in ideal optical structure, and the method is simple and feasible.

(2) The present invention separates and obtains components with different properties by extracting coal tar pitch with an organic solvent, which can reduce impurities and highly reactive substances in raw materials, facilitate the smooth progress of thermal condensation polymerization, suppress coking and improve the thermal stability of the system sex.

(3) The present invention hydrogenates the heavy components of coal tar pitch to obtain hydrogenated heavy components, introduces naphthene structures and alkyl side chains, releases active hydrogen in the thermal polycondensation reaction, and effectively inhibits the excessive polycondensation of aromatic molecules, The smooth growth of mesophase globules is conducive to the formation of wide-area mesophase.

(4) The present invention obtains modified asphalt by mixing unhydrogenated components and hydrogenated heavy components, and adjusts its molecular weight distribution while introducing naphthene structures and alkyl side chains, thereby adjusting the thermal polycondensation reaction rate and promoting intermediate Phase formation and development, to achieve an increase in mesophase content and an improvement in optical texture.

Description of drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the accompanying drawings that need to be used in the description of the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For Those of ordinary skill in the art can also obtain other drawings based on these drawings without any creative effort. in:

Fig. 1 is a polarized micrograph of the mesophase pitch prepared in Example 1 of the present invention.

Fig. 2 is a polarized micrograph of the mesophase pitch prepared in Example 2 of the present invention.

Fig. 3 is a polarized micrograph of the mesophase pitch prepared in Example 3 of the present invention.

Fig. 4 is a flow chart of a method for preparing mesophase pitch by hydrogenating coal tar pitch components in an embodiment of the present invention.

Detailed ways

In order to make the above objects, features and advantages of the present invention more obvious and comprehensible, the specific implementation manners of the present invention will be described in detail below in conjunction with the embodiments of the specification.

In the following description, a lot of specific details are set forth in order to fully understand the present invention, but the present invention can also be implemented in other ways different from those described here, and those skilled in the art can do it without departing from the meaning of the present invention. By analogy, the present invention is therefore not limited to the specific examples disclosed below.

Second, "one embodiment" or "an embodiment" referred to herein refers to a specific feature, structure or characteristic that may be included in at least one implementation of the present invention. "In one embodiment" appearing in different places in this specification does not all refer to the same embodiment, nor is it a separate or selective embodiment that is mutually exclusive with other embodiments.

Example 1

This embodiment provides a method for preparing mesophase pitch by hydrogenating coal tar pitch components. The process flow chart is shown in FIG. 4, which includes the following steps:

(1) Put 100g of coal tar pitch and 500g of n-heptane in a beaker, set aside after stirring for 50min in a water bath at 40°C, separate the raffinate 1 and the supernatant, and distill the resulting extract to remove the organic solvent , to obtain component A;

Take the raffinate 1 after vacuum drying for 24 hours and put 400 g of toluene in a beaker, put it in a water bath at 60°C, stir it for 60 minutes and then let it stand, separate the raffinate 2 and the upper layer, and distill the obtained extract to remove organic matter. Solvent, obtain component B;

Take the extract 2 after vacuum drying for 24 hours and put 200g of tetrahydrofuran in a beaker, put it in a water bath at 70°C, stir for 60 minutes and then let it stand, separate the raffinate 3 and the upper layer, and distill the obtained extract under reduced pressure to remove the organic solvent , to obtain component C;

Take the extract 3 and 200 g of quinoline after vacuum drying for 24 hours, put them in a beaker, put them in a water bath at 70°C, stir for 60 minutes, and then let them stand, separate the raffinate 4 and the upper layer, and distill the obtained extract to remove organic compounds. The solvent was used to obtain component D, and the raffinate 4 was vacuum-dried for 24 hours to obtain component E;

(2) Get 40g of component D, 6g of tetralin and 0.04g of cobalt-molybdenum catalyst in the reactor, the initial pressure of hydrogen is 4MPa, the stirring speed is 100 rpm, and the temperature is raised to 390 at a heating rate of 1.5°C/min. ℃, keep the temperature for 1h and then cool to room temperature to obtain the hydrogenated component D1;

Take 40g of component E, 4g of tetrahydronaphthalene and 0.03g of cobalt-molybdenum catalyst and put them in the reaction kettle. Cool to room temperature after 1h to obtain hydrogenated component E1;

(3) Take 5g of component A, 12.5g of component B, 15g of component C, 10g of hydrogenated component D1 and 7.5g of hydrogenated component E1 in a beaker, stir it with strong magnetic force for 30min in a water bath at 90°C, and cool to At room temperature, modified asphalt is obtained;

(4) Put the modified asphalt in the reaction kettle, the initial pressure of nitrogen is 0.5MPa, the temperature is raised to 375°C at a heating rate of 1.5°C/min, and the temperature is kept constant for 8h to obtain the mesophase pitch.

The polarized light microscopic morphology of the prepared mesophase pitch is shown in Figure 1, and the results of the anisotropic phase content and optical structure composition are shown in Table 1.

Example 2

This embodiment provides a method for preparing mesophase pitch by hydrogenating coal tar pitch components, comprising the following steps:

(1) 100g of coal tar pitch and 500g of n-hexane are placed in a beaker, placed in a water bath at 40° C., stirred for 40 minutes, then left to stand, and the raffinate 1 and the supernatant are separated, and the obtained extract is distilled off under reduced pressure to remove the organic solvent. Obtain component A;

Extract the raffinate 1 and 400g of toluene and place them in a beaker, stir in a water bath at 60°C for 40 minutes and then let it stand, separate the raffinate 2 and the upper layer, and distill the obtained extract to remove the organic solvent to obtain the component B;

Extract the raffinate 2 and 300g of chloroform and put them in a beaker, stir in a water bath at 65°C for 40 minutes and then let it stand, separate the raffinate 3 and the upper layer, and distill the obtained extract to remove the organic solvent to obtain the component C;

Take the extract 3 and 200g of pyridine and place it in a beaker, and put it in a water bath at 70°C, stir it for 50 minutes and let it stand, separate the raffinate 4 and the upper layer, and distill the obtained extract under reduced pressure to remove the organic solvent to obtain component D. The raffinate 4 was vacuum-dried for 24 hours to obtain component E;

(2) Take 40g of component E, 2g of dihydroanthracene and 0.03g of Fe ₂ O ₃ Catalysts are placed in a reaction kettle, the initial hydrogen pressure is 3MPa, the stirring speed is 100 rpm, and the temperature is raised at a heating rate of 1.5°C/min to 400°C, hold the temperature for 1 hour and then cool to room temperature to obtain the hydrogenated component E1;

(3) Take 7.5g of component A, 10g of component B, 15g of component C, 10g of component D and 7.5g of hydrogenated component E1 in a beaker, stir with strong magnetic force for 30min in a water bath at 90°C, and cool to room temperature , to obtain modified asphalt;

(4) Put the modified asphalt in the reaction kettle, the initial pressure of nitrogen is 0.5MPa, the temperature is raised to 375°C at a heating rate of 1.5°C/min, and the temperature is kept constant for 8h to obtain the mesophase pitch.

The polarized light microscopic morphology of the prepared mesophase pitch is shown in Figure 2, and the results of the anisotropic phase content and optical structure composition are shown in Table 1.

Example 3

This embodiment provides a method for preparing mesophase pitch by hydrogenating coal tar pitch components, comprising the following steps:

(1) 100g of coal tar pitch and 500g of n-hexane are placed in a beaker, placed in a water bath at 40° C., stirred for 40 minutes, then left to stand, and the raffinate 1 and the supernatant are separated, and the obtained extract is distilled off under reduced pressure to remove the organic solvent. Obtain component A;

Extract the raffinate 1 and 400g of toluene and place them in a beaker, stir in a water bath at 60°C for 40 minutes and then let it stand, separate the raffinate 2 and the upper layer, and distill the obtained extract to remove the organic solvent to obtain the component B;

Extract the raffinate 2 and 300g of chloroform and put them in a beaker, stir in a water bath at 65°C for 40 minutes and then let it stand, separate the raffinate 3 and the upper layer, and distill the obtained extract to remove the organic solvent to obtain the component C;

Take the extract 3 and 200g of quinoline and put them in a beaker, put them in a water bath at 70°C, stir for 50 minutes, and then let them stand, separate the raffinate 4 and the upper layer, and distill the obtained extracts under reduced pressure to remove the organic solvent to obtain component D , the raffinate 4 was vacuum-dried for 24 hours to obtain component E;

(2) Get 40g of component D, 4g of tetralin and 0.02g of cobalt-molybdenum catalyst in the reactor, the initial pressure of hydrogen is 5MPa, the stirring speed is 100 rpm, and the temperature is raised to 400 at a heating rate of 1.5°C/min. ℃, keep the temperature for 1h and then cool to room temperature to obtain the hydrogenated component D1;

(3) Put 10g of component A, 17.5g of component B, 15g of component C and 11.5g of hydrogenated component D1 into a beaker, stir with strong magnetic force for 15min in a water bath at 90°C, and cool to room temperature to obtain modified asphalt ;

(4) Put the modified asphalt in the reactor, the initial nitrogen pressure is 0.5MPa, the temperature is raised to 375°C at a heating rate of 1.5°C/min, and the temperature is kept constant for 7h to obtain the mesophase pitch.

The polarized light microscopic morphology of the prepared mesophase pitch is shown in Figure 3, and the results of the anisotropic phase content and optical structure composition are shown in Table 1.

Table 1 Content and optical structure composition of mesophase pitch prepared in Examples 1-3

The method for preparing mesophase pitch by hydrogenating coal tar pitch components of the present invention provides a method for preparing high value-added mesophase pitch from coal tar pitch by extracting coal tar pitch step by step and hydrogenating heavy components at a suitable depth. A new path to control.

It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention without limitation, although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be carried out Modifications or equivalent replacements without departing from the spirit and scope of the technical solution of the present invention shall fall within the scope of the present invention.

Claims (10)

1. A method for preparing mesophase pitch by hydrogenating a coal tar pitch component is characterized by comprising the following steps: comprising the steps of (a) a step of,

step-by-step extraction is carried out on the coal tar pitch by using different extractants to obtain A, B and C three components or A, B, C and D four components or A, B, C, D and E five components;

adding hydrogen-supplying solvent into one or more of B, C, D or E components, mixing with a catalyst, and obtaining hydrogenated heavy components after hydrogenation treatment;

mixing the hydrogenated heavy component and the unhydrogenated component to obtain a modified asphalt;

and performing thermal condensation polymerization on the modified asphalt to obtain the mesophase pitch.

2. The method of claim 1, wherein: the step-by-step extraction of the coal tar pitch with different extractant comprises,

adding an extractant a into the coal tar pitch, standing after extraction, and separating raffinate 1 and supernatant to obtain an extract, and recovering the extractant a through reduced pressure distillation to obtain a component A;

vacuum drying the raffinate 1 to constant weight, mixing with the extractant B, standing after extraction, separating the raffinate 2 and supernatant to obtain an extract, and recovering the extractant B through reduced pressure distillation to obtain a component B;

and (3) vacuum drying the raffinate 2 to constant weight, mixing with the extractant C, standing after extraction, separating the raffinate and the supernatant to obtain an extract, and recovering the extractant C through reduced pressure distillation to obtain the component C.

In the steps, A, B, C and D components are sequentially obtained when four extracting agents are adopted in the step-by-step extraction process; when five extractants are used, A, B, C, D and E five components are obtained in sequence.

3. The method of claim 2, wherein: the extractant is selected from n-hexane, n-heptane, toluene, pyridine, chloroform, acetone, tetrahydrofuran, quinoline, anthracene oil, wash oil, naphthalene oil, and the like.

4. A method according to claim 2 or 3, wherein: the step-by-step extraction is carried out, wherein the mass ratio of the extractant to the asphalt is 5:1-20:1, and the extraction conditions are as follows: stirring at 50-120 deg.c for 50-90 min.

5. The method of claim 1, wherein: the hydrogen-supplying solvent is one or a mixture of more than two of dihydropyrene, dihydroanthracene, tetrahydroanthracene, dihydronaphthalene, tetrahydronaphthalene, dihydrophenanthrene, octahydrophenanthrene, tetrahydroquinoline and coal direct liquefaction hydrogen-supplying solvent and coal tar distillate hydrogenation products;

the catalyst is Fe ₂ O ₃ 、FeS ₂ 、ZnO、ZnCl ₂ 、SnO ₂ One or a mixture of two or more of Co, mo, ni and other catalysts.

6. The method of claim 5, wherein: the hydrogen supply solvent accounts for 5-60 wt% of the mass of the heavy components;

the hydrotreating is carried out under the condition of hydrogen or nitrogen of 2 MPa-8 MPa, and the temperature is 340 ℃ to 440 ℃.

7. The method of claim 1, wherein: mixing the hydrogenated heavy component and the unhydrogenated component, wherein,

when the coal tar pitch is separated into 3 components, the mass ratio of the unhydrogenated component to the hydrogenated heavy component is 10-20 percent, 20-50 percent and 10-40 percent;

when the coal tar pitch is separated into 4 components, the mass ratio of the unhydrogenated component to the hydrogenated heavy component is 10% -20%, 20% -50%, 10% -30% and 10% -20%;

when the 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% and 10% -20%.

8. The method of claim 1, wherein: the thermal polycondensation process is to heat up to 320-480 ℃ at a heating rate of 0.5-5 ℃/min, and the heat preservation time is 3-15 h.

9. The method of claim 1, wherein: the modified asphalt is subjected to thermal polycondensation, wherein the stirring speed is 50-500 r/min, and the initial pressure of nitrogen is 0.1-5 MPa.

10. The method of claim 1, wherein: the intermediate phase asphalt product is intermediate phase asphalt with anisotropic phase content more than or equal to 80%, wide area streamline optical texture content more than or equal to 60% and softening point of 120-380 ℃.