CN117143629A

CN117143629A - Aromatic oil for mesophase pitch and preparation method and application thereof

Info

Publication number: CN117143629A
Application number: CN202310597323.2A
Authority: CN
Inventors: 王象东; 刘辉; 王硕; 高昂; 王腾; 刘建国
Original assignee: Shandong Ruicheng Yuhang Carbon Material Co ltd
Current assignee: Shandong Ruicheng Yuhang Carbon Material Co ltd
Priority date: 2023-05-23
Filing date: 2023-05-23
Publication date: 2023-12-01

Abstract

The invention provides aromatic oil for mesophase pitch and a preparation method and application thereof. The preparation method comprises the steps of purification, refining, reforming, conversion and purification. The method can be used for converting and purifying heavy residual oil into aromatic hydrocarbon oil with higher aromatic hydrocarbon content, and the obtained aromatic hydrocarbon oil has narrow molecular weight distribution interval and low ash content and sulfur content. The mesophase pitch prepared by the aromatic oil through different processes has the advantages of high mesophase content, uniform molecular weight distribution, good mesophase morphology, low ash and sulfur content, proper softening point and good spinnability, and is applied to preparing carbon materials such as carbon fibers or graphite carbon foam and the like, and has excellent performance. In addition, the equipment used in the method is conventional industrial production equipment, so that the equipment investment and the production difficulty of converting the aromatic hydrocarbon oil by related enterprises can be greatly reduced.

Description

Aromatic oil for mesophase pitch and preparation method and application thereof

Technical Field

The invention relates to aromatic oil for mesophase pitch and a preparation method and application thereof, and belongs to the technical field of petroleum deep processing.

Background

The mesophase pitch is a pitch substance mainly comprising aromatic compounds, is a mixture of flat disc-shaped polycyclic aromatic hydrocarbon with the relative molecular mass of 370-2000, has a large C/H ratio (such as 1.72), and has a softening point of 205-285 ℃ mostly and sometimes higher than 300 ℃. Generally has lower melt viscosity above softening point temperature and can be kept stable and not decomposed for a long time so as to facilitate the subsequent processing operation of the liquid crystal melt. In addition, the density, heat capacity, and in particular viscosity of mesophase pitch also have a significant temperature dependence. Mesophase pitch has a distinct lamellar structure after melting and is readily graphitizable by high temperature treatment, so that it is typically an easily graphitizable carbon. The high-performance pitch-based carbon fiber can be obtained by controlling the synthesis process to orient the plane of the carbon net along the fiber axis direction. In addition, carbon materials such as foam carbon materials, porous carbon materials, refractory materials, ultra-high power electrode materials, mesophase carbon microspheres, fluorinated asphalt and the like prepared by using mesophase asphalt have higher performance than common asphalt products, and have immeasurable application prospects.

Mesophase pitch is prepared from high aromatic content oils (i.e., aromatic oils); the preparation of the mesophase pitch is usually started after the heavy residual oil is simply treated by adopting a method of filtering or distilling or the combination of the heavy residual oil and the heavy residual oil, which is limited by raw materials and process technology; the prepared mesophase pitch has the defects of insufficient mesophase content, large molecular weight distribution range, non-ideal mesophase morphology (small ratio of large streamline configuration), high ash content and sulfur content and the like, so that the performance improvement effect of the subsequently prepared carbon material is limited.

The prior art also reports on pretreatment methods of raw oil. For example, chinese patent document CN112852464a discloses a pretreatment method of raw oil for preparing spinnable mesophase pitch and high-performance pitch-based carbon fiber. The method takes one or more heavy fraction sections of heavy oil rich in aromatic hydrocarbon, catalytic cracking slurry oil, coal tar or ethylene tar with the temperature of more than 300 ℃ as a raw material, carries out filtration and deashing coupling enhanced extraction process under the assistance of ultrasound, and further realizes flexible adjustment of the structural composition of the refined raw material by gel permeation chromatography technology to obtain high-quality aromatic-rich raw material oil. However, the invention has the defects of complex equipment and process and low production efficiency, such as stirring and ultrasonic treatment of the used ultrasonic thermal filtration coupling extraction system, and the limitation of ultrasonic equipment is well known to prevent the process from large-scale production, and the factory such as transferring the refined aromatic-rich raw oil needs to carry out large-scale modification on the existing equipment of the factory. In addition, the invention only carries out physical treatment on the raw oil to obtain refined raw oil, but does not carry out effective treatment on hetero atoms in the raw oil refining process, such as hetero atom carbon compounds such as nitrogen, sulfur and the like which are common in petroleum are not removed effectively; when the refined raw oil prepared by the method is used for preparing the mesophase pitch, the content of hetero atoms in the produced mesophase pitch is also more because more hetero atoms exist in the refined raw oil, and the mechanical properties of the final carbon fiber are still at a lower level.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides aromatic oil for mesophase pitch, and a preparation method and application thereof. The method can be used for converting and purifying heavy residual oil into aromatic hydrocarbon oil with higher aromatic hydrocarbon content, and the obtained aromatic hydrocarbon oil has narrow molecular weight distribution interval and low ash content and sulfur content. The mesophase pitch prepared by the aromatic oil through different processes has the advantages of high mesophase content, uniform molecular weight distribution, good mesophase morphology, low ash and sulfur content, proper softening point and good spinnability, and is applied to preparing carbon materials such as carbon fibers or graphite carbon foam and the like, and has excellent performance. In addition, the equipment used in the method is conventional industrial production equipment, so that the equipment investment and the production difficulty of converting the aromatic hydrocarbon oil by related enterprises can be greatly reduced.

The technical scheme of the invention is as follows:

aromatic oil for mesophase pitch, wherein the weight average molecular weight of the aromatic oil ranges from 800 to 1600,3 to 5, the content of cycloaromatics is more than or equal to 84wt%, the mass content of ash is less than or equal to 25ppm, and the content of sulfur is less than or equal to 0.01wt%.

According to the invention, the aromatic hydrocarbon oil has a weight average molecular weight ranging from 840 to 1510,3 to 5, a cycloarene content ranging from 84 to 92wt%, an ash content ranging from 20 to 25ppm, and a sulfur content less than or equal to 0.01wt%.

The preparation method of the aromatic oil for mesophase pitch comprises the following steps:

(1) Purifying: washing heavy residual oil sequentially by using a detergent sulfuric acid-phosphoric acid aqueous solution, a hydrochloric acid aqueous solution, a nitric acid aqueous solution and a sodium hydroxide aqueous solution, and then drying the water to obtain purified residual oil;

(2) Refining: distilling the purified residual oil, and taking a fraction at 200-400 ℃ to obtain refined residual oil;

(3) Reforming: fully mixing refined residual oil and decalin, reacting, distilling at 200 ℃, and taking the distillate to obtain reformed residual oil;

(4) Conversion: fully mixing the reformed residual oil with n-hexadecene, and reacting to obtain converted residual oil;

(5) Purifying: and (3) carrying out vacuum heating distillation on the converted residual oil, wherein the obtained distillate is aromatic hydrocarbon oil.

According to the present invention, in the sulfuric acid-phosphoric acid aqueous solution of step (1), sulfuric acid: the mass ratio of the water is (1-5): (1-5): (5-50).

According to the present invention, in the step (1), the mass concentration of the aqueous hydrochloric acid solution is preferably 5 to 30%.

According to the present invention, in the step (1), the mass concentration of the aqueous nitric acid solution is preferably 5 to 50%.

According to the present invention, in the step (1), the mass concentration of the aqueous sodium hydroxide solution is preferably 5 to 40%.

According to the present invention, preferably, in the step (1), the washing step of each detergent is as follows: mixing heavy residual oil and detergent, stirring at 40-60deg.C, standing at room temperature for layering, and collecting oil phase; the oil phase is centrifuged to remove solids, and then washed with water for 2-4 times, thus completing the washing step.

According to a preferred embodiment of the present invention, in step (1), the drying temperature is 105 ℃. The drying temperature can not only effectively remove water, but also ensure that the dried product is not deteriorated.

According to a preferred embodiment of the invention, in step (2), the pressure of the distillation is 1000Pa; taking the fraction at 250-400 ℃.

According to the invention, in the step (3), the mass of decalin is 5-35% of the mass of the refined residue.

Preferably, according to the present invention, in step (3), the reaction is carried out under the protection of inert gas; the reaction temperature is 300-400 ℃, the reaction time is 0.5-5 hours, and the reaction pressure is 1.0-3.0 MPa. Preferably, the inert gas is nitrogen or argon.

According to a preferred embodiment of the present invention, in step (3), the distillation pressure is 1000Pa and the distillation time is 60 minutes.

According to the invention, in the step (4), the mass ratio of the reformed residuum to the n-hexadecene is 1: (1-10).

Preferably, according to the present invention, in step (4), the reaction is carried out under the protection of inert gas; the reaction temperature is 300-350 ℃, the reaction time is 2-5 hours, and the reaction pressure is 1.0-3.0 MPa. Preferably, the inert gas is nitrogen or argon.

According to a preferred embodiment of the present invention, in the step (5), the distillation temperature is 200℃and the pressure is 1000Pa.

The application of the aromatic oil for the mesophase pitch is applied to the preparation of mesophase pitch or carbon materials.

The process principle of the invention:

the invention mainly comprises a purifying part 5, a refining part 5, a reforming part 5, a conversion part 5 and a purifying part 5. The ash and catalyst particles in the heavy residue are first washed with an acid (sulfuric acid-phosphoric acid aqueous solution, hydrochloric acid aqueous solution, nitric acid aqueous solution), and the inorganic salt dissolved in water is removed, and the water-insoluble salt is removed by filtration. Then the organic acid contained in the residual oil is converted into organic acid sodium by using sodium hydroxide, and the organic acid sodium is dissolved in water to remove, and then the residual oil is cleaned and dried by using purified water so as to obtain the purified residual oil consisting of pure hydrocarbon. And separating useful components from the purified residual oil by distillation to obtain refined residual oil. The sulfur-containing organic molecules in the refined residual oil are destroyed by decalin to separate sulfur, and part of the molecules are hydrogenated to obtain reformed residual oil. And then polymerizing the reformed residual oil in the n-hexadecene to average the molecular weight of the residual oil molecules, and evaporating out small molecules and redundant n-hexadecene generated by the reaction to obtain the aromatic oil capable of preparing high-quality mesophase pitch.

The invention has the technical characteristics and beneficial effects that:

1. the process of the present invention uses various acid solutions to wash the heavy residuum to dissolve the ash metal oxides sufficiently in water for removal. In the reforming step, decalin reacts with residual oil, on the one hand, hydrogen is added to residual oil molecules, and the softening point of the residual oil is reduced; on the one hand, the molecules of the sulfur-containing compound can be destroyed to be broken into elemental sulfur or hydrogen sulfide to escape; the reforming step avoids the use of a catalyst, so that the ash content of residual oil can be ensured to be low, and the safety of equipment is improved without using hydrogen. In the conversion step of the invention, on the one hand, the function of the n-hexadecene is to average the molecular weight of the residuum molecules; on the other hand, the alkane is added to the residual oil molecules, so that the residual oil molecules have more side chains, form a form similar to multi-hand guanyin, and the mechanical property of the product can be enhanced by the multi-hand mutual pulling form. The transformation step and the condition of the invention are taken as a whole, and the effect can be achieved under the combined action.

2. The invention discloses a method for preparing aromatic hydrocarbon oil with high aromatic hydrocarbon content, narrow molecular weight distribution interval and low ash content and sulfur content by purifying, refining, reforming, converting, purifying and the like heavy residual oil with wide molecular weight distribution for the first time. The aromatic hydrocarbon oil prepared by the process can prepare mesophase pitch with the mesophase content of 98-100%, uniform molecular weight distribution, good mesophase morphology, low ash and sulfur content, proper softening point and good spinnability. The various carbon materials prepared by the obtained mesophase pitch have better performance. If the strength of the prepared mesophase pitch carbon fiber (without graphitization) can reach more than 2500 MPa; the prepared graphite carbon foam has uniform pores and low density (less than or equal to 0.5 g/cm) ³ ) High heat conducting performance (more than or equal to 80W/m.K), and the like. In addition, the equipment used in the method is conventional industrial production equipment, so that the equipment investment and the production difficulty of converting the aromatic hydrocarbon oil by related enterprises can be greatly reduced.

Drawings

FIG. 1 is a microscope image of a mesophase pitch prepared from aromatic oils obtained in example 5;

FIG. 2 is a microscope image of a mesophase pitch prepared from the aromatic hydrocarbon oil obtained in comparative example 6;

FIG. 3 is a Scanning Electron Microscope (SEM) image of carbon fibers prepared from the aromatic hydrocarbon oil obtained in comparative example 5;

FIG. 4 is a drawing of a graphite carbon foam Scanning Electron Microscope (SEM) prepared from the aromatic oil obtained in example 1;

FIG. 5 is a Scanning Electron Microscope (SEM) image of graphite foam carbon prepared from the aromatic hydrocarbon oil obtained in comparative example 2.

Detailed Description

The technical scheme of the present invention is further described below with reference to the examples and the accompanying drawings, but the scope of the present invention is not limited thereto.

In the examples, the raw materials and reagents used, unless otherwise indicated, are commercially available; the method is the prior method unless specified otherwise.

Raw material source

The heavy residual oil is purchased from a Yanshan petrochemical refinery, and the technical indexes are as follows: density: 1.08g/cm ³ Viscosity: 21 Pa.S, moisture: no congealing point: 22 ℃, flash point: 218 ℃.

Example 1

The preparation method of the aromatic hydrocarbon oil for the mesophase pitch comprises the following steps:

(1) Purifying: placing heavy residual oil in a stirring kettle, adding a detergent sulfuric acid-phosphoric acid aqueous solution, heating to 50 ℃ and fully stirring, standing at room temperature, taking oil phase after layering, placing the oil phase in a centrifuge for centrifugal separation, removing solids, returning supernatant residual oil to the stirring kettle, and washing the residual oil with purified water for 3 times.

The steps were repeated using aqueous hydrochloric acid (5% by mass), aqueous nitric acid (5% by mass) and aqueous sodium hydroxide (5% by mass) as detergents, respectively. And finally, heating the residual oil to 105 ℃ and drying the residual oil to obtain purified residual oil.

(2) Refining: placing the purified residual oil prepared in the step (1) into a distillation kettle, then starting a vacuum pump to regulate vacuum to 1000Pa, heating and taking a fraction at 250-400 ℃ to obtain refined residual oil.

(3) Reforming: fully mixing refined residual oil prepared in the step (2) with decalin (the mass of decalin is 5% of the mass of the refined residual oil), placing the mixture in a reaction kettle, pressurizing to 1.0MPa under the protection of nitrogen, heating to 300 ℃ and keeping the temperature for 5 hours, reducing the temperature to 200 ℃, then starting a vacuum pump to 1000Pa, keeping the state for 60 minutes, and taking the distillate to obtain the reformed residual oil.

(4) Conversion: mixing the reformed residual oil obtained in the step (3) with n-hexadecene according to a mass ratio of 1:1, pressurizing to 1.0MPa under the protection of nitrogen, heating to 300 ℃ and keeping the temperature for 5 hours to obtain converted residual oil.

(5) Purifying: distilling the converted residual oil obtained in the step (4) at the pressure of 1000Pa and the temperature of 200 ℃, and obtaining the distillate which is aromatic hydrocarbon oil.

Example 2

(1) The purified residuum was prepared as in example 1;

(2) Refined residuum was prepared as in example 1;

(3) Reforming: fully mixing refined residual oil prepared in the step (2) with decalin (the mass of decalin is 15% of the mass of the refined residual oil), placing the mixture in a reaction kettle, pressurizing to 2.0MPa under the protection of nitrogen, heating to 400 ℃ and keeping the temperature for 2 hours, reducing the temperature to 200 ℃, then starting a vacuum pump to 1000Pa, keeping the state for 60 minutes, and taking the distillate to obtain the reformed residual oil.

(4) Conversion: mixing the reformed residual oil obtained in the step (3) with n-hexadecene according to a mass ratio of 1:10, pressurizing to 1.0MPa under the protection of nitrogen, heating to 350 ℃ and keeping the temperature for 3 hours to obtain converted residual oil.

Example 3

The above steps were repeated using aqueous hydrochloric acid (30% by mass), aqueous nitric acid (50% by mass) and aqueous sodium hydroxide (40% by mass) as detergents, respectively. And finally, heating the residual oil to 105 ℃ and drying the residual oil to obtain purified residual oil.

(3) Reformed residuum was produced in the same manner as in example 1.

(4) The conversion residuum was prepared as in example 1.

(5) The purification procedure was as in example 1 to give aromatic oil.

Example 4

(1) The purified residuum was prepared as in example 3.

(2) Refined residuum preparation was the same as in example 3.

Example 5

The above steps were repeated using aqueous hydrochloric acid (15% by mass), aqueous nitric acid (25% by mass) and aqueous sodium hydroxide (20% by mass) as detergents, respectively. And finally, heating the residual oil to 105 ℃ and drying the residual oil to obtain purified residual oil.

(2) Refining: placing the purified residual oil prepared in the step (1) into a distillation kettle, and then starting a vacuum pump to regulate vacuum

Heating to 250-400 deg.c to obtain refined residual oil at 1000Pa.

(3) Reforming: fully mixing refined residual oil prepared in the step (2) with decalin (the mass of decalin is 15% of the mass of the refined residual oil), placing the mixture in a reaction kettle, pressurizing to 3.0MPa under the protection of nitrogen, heating to 400 ℃ and keeping the temperature for 2 hours, reducing the temperature to 200 ℃, then starting a vacuum pump to 1000Pa, keeping the state for 60 minutes, and taking the distillate to obtain the reformed residual oil.

(4) Conversion: mixing the reformed residual oil obtained in the step (3) with n-hexadecene according to a mass ratio of 1:5, pressurizing to 3.0MPa under the protection of nitrogen, heating to 350 ℃ and keeping the temperature for 5 hours to obtain converted residual oil.

Comparative example 1

A process for the preparation of aromatic oils as described in example 1, with the difference that: in the step (3), the mass of decalin was 2% of the mass of the refined residue, and the other steps were the same as in example 1.

Comparative example 2

A process for the preparation of aromatic oils as described in example 1, with the difference that: in the step (3), the mass of decalin was 40% of the mass of the refined residue, and the other steps were the same as in example 1.

Comparative example 3

A process for the preparation of aromatic oils as described in example 5, with the difference that: the mass ratio of reformed residuum to n-hexadecene in step (4) was adjusted to 1:0.5, and the other steps were the same as in example 5.

Comparative example 4

A process for the preparation of aromatic oils as described in example 5, with the difference that: the mass ratio of reformed residuum to n-hexadecene in step (4) was adjusted to 1:11, and the other steps were the same as in example 5.

Comparative example 5

A preparation method of aromatic hydrocarbon oil comprises the following steps: distilling heavy residual oil under 1000Pa, taking 300-350 ℃ distillate, and filtering the distillate with a 0.5 mu m filter screen to obtain aromatic oil.

Comparative example 6

A preparation method of aromatic hydrocarbon oil comprises the following steps: distilling heavy residual oil under 1000Pa, taking fraction at 250-350 ℃, and filtering the distillate with a 0.5 μm filter screen to obtain aromatic oil.

Test examples

The aromatic hydrocarbon oils prepared in the above examples and comparative examples were prepared in a conventional manner to prepare mesophase pitches, and carbon fibers and graphite carbon foam were prepared using the mesophase pitches for performance comparison.

The conventional method for preparing the mesophase pitch is a two-stage method, and the technological process is as follows: the pressurizing section is kept at 420 ℃ and 2.0MPa for 5 hours, and the depressurizing section is kept at 400 ℃ and 5000Pa for 4 hours.

Spinnability test: and spinning the asphalt sample to be tested with the same quality at a drawing rate of 400m/min, and testing the longest continuous spinning time to obtain spinnability.

The preparation method of the carbon fiber comprises the following steps: spinning mesophase pitch into a precursor under the conditions of 0.05MPa of pressure and 400m/min of drafting rate, oxidizing the precursor at the constant temperature of 300 ℃ for 10min, and heating oxidized fibers to the constant temperature of 1000 ℃ for 10min under the protection of nitrogen.

The preparation method of the graphite carbon foam comprises the following steps: and (3) placing the mesophase pitch into a high-temperature high-pressure kettle, heating to 500 ℃ under 1000Pa, keeping the temperature for 10min, pressurizing to 20MPa, keeping the temperature for 5 h, cooling, taking out, and keeping the temperature at 2800 ℃ for 15min to obtain the graphite carbon foam.

The performance test data are shown in tables 1-2 below.

Table 1 comparison of parameters of aromatic oils and mesophase pitches prepared in examples and comparative examples

From Table 1, it can be seen that comparative example 4 differs from example 5 in that the mass ratio of reformed residuum to n-hexadecene in step (4) was adjusted to 1:11, so that its various data are similar to those of example 5, indicating that too high a ratio of n-hexadecene employed in the system would not affect the performance of aromatic hydrocarbon oil, but rather the economy would be affected by too much n-hexadecene addition (so comparative example 4 will not be discussed later).

The molecular weight distribution ranges of examples 1 to 5 are small and close, whereas the comparative example 1 has too low a proportion of decalin added, and the residual oil cannot obtain enough hydrogen atoms, so the molecular weight distribution range is wide. In comparative example 2, the ratio of decalin added is too high, and the hydrogen atoms obtained from the residual oil molecules are too high, so that the molecular weight distribution range is not high, but the softening point of the subsequently prepared mesophase pitch is too low. The comparative examples 5 to 6 used different distillation temperature ranges, the obtained product did not control the molecular weight distribution range well, and in addition, the softening point of the prepared mesophase pitch was also high, affecting the spinning performance.

The aromatic oil prepared in examples 1-5 has lower ash and sulfur content, while comparative examples 1-3 also have similar ash and sulfur content to the examples, demonstrating that treating residuum with acid and base can perform a good ash and sulfur content reduction. Comparative examples 5 to 6 employed a method of filtering and directly distilling to obtain refined residues, and ash and sulfur could not be effectively removed.

Table 2 comparison of properties of mesophase pitch articles prepared in examples and comparative examples

As can be seen from Table 2, the mesophase pitch carbon fibers prepared in examples all have higher tensile strength and modulus, and the data related to comparative examples 1 to 6 (except comparative example 4) are all lower, especially comparative examples 5 to 6 are at the lowest value.

In addition, the graphite carbon foams prepared in the examples also all have lower density, better thermal conductivity, good compressive strength and modulus, which are not achieved in the comparative examples (except comparative example 4).

Compared with the conventional method, the preparation method of the aromatic oil has better performance.

Figures 1-5 further illustrate that the aromatic oil preparation process of the present invention provides superior results compared to conventional processes.

Fig. 1 is a mesophase pitch having a large streamline form prepared from the aromatic oil obtained in example 5, and fig. 2 is a mesophase pitch having a finely divided mosaic structure prepared from the aromatic oil obtained in comparative example 6.

Fig. 3 is a SEM cross-sectional view of carbon fibers prepared from the aromatic oil obtained in comparative example 5. The section of the mesophase pitch carbon fiber prepared from aromatic oil obtained by acid and alkali treatment of residual oil basically has no hole defect, while the mesophase pitch carbon fiber prepared by the conventional method has more or less larger hole defect, and part of the carbon fiber has cracks.

Fig. 4 and 5 are cross-sectional views of graphite carbon foam prepared from aromatic hydrocarbon oils obtained in example 1 and comparative example 2, respectively. It can be seen that the graphite carbon foam prepared by the embodiment has a relatively uniform pore structure, and the size difference is in a relatively small range; and the graphite carbon foam prepared in the comparative example has uneven pore size.

Claims

1. The aromatic hydrocarbon oil for the mesophase pitch is characterized in that the weight average molecular weight range of the aromatic hydrocarbon oil is 800-1600,3-5, the content of cycloaromatics is more than or equal to 84wt%, the mass content of ash is less than or equal to 25ppm, and the content of sulfur is less than or equal to 0.01wt%.

2. The aromatic hydrocarbon oil for mesophase pitch according to claim 1, wherein the aromatic hydrocarbon oil has a weight average molecular weight ranging from 840 to 1510,3 to 5, a cyclic aromatic hydrocarbon content of 84 to 92wt%, an ash mass content of 20 to 25ppm, and a sulfur content of 0.01wt% or less.

3. The method for producing an aromatic oil for mesophase pitch according to any one of claims 1 or 2, comprising the steps of:

4. A process for the preparation of aromatic hydrocarbon oil for mesophase pitch as claimed in claim 3, wherein in step (1) one or more of the following conditions are included:

i. sulfuric acid-phosphoric acid aqueous solution, sulfuric acid: the mass ratio of the water is (1-5): (1-5): (5-50);

ii. The mass concentration of the aqueous solution of hydrochloric acid is 5-30%;

iii, the mass concentration of the nitric acid aqueous solution is 5-50%;

iv, the mass concentration of the sodium hydroxide aqueous solution is 5-40%;

v, the washing steps of each detergent are as follows: mixing heavy residual oil and detergent, stirring at 40-60deg.C, standing at room temperature for layering, and collecting oil phase; centrifuging the oil phase to remove solids, and washing the oil phase with water for 2-4 times to finish the washing step;

vi, the drying temperature is 105 ℃.

5. The process for producing aromatic hydrocarbon oil for mesophase pitch according to claim 3, wherein in the step (2), the distillation pressure is 1000Pa; taking the fraction at 250-400 ℃.

6. A process for the preparation of aromatic hydrocarbon oil for mesophase pitch as claimed in claim 3, wherein in step (3) one or more of the following conditions are included:

i. the mass of decalin is 5-35% of the mass of refined residual oil;

ii. The reaction is carried out under the protection of inert gas; the reaction temperature is 300-400 ℃, the reaction time is 0.5-5 hours, and the reaction pressure is 1.0-3.0 MPa; preferably, the inert gas is nitrogen or argon;

iii, the distillation pressure is 1000Pa, and the distillation time is 60min.

7. The process for producing aromatic hydrocarbon oil for mesophase pitch as set forth in claim 3, wherein in the step (4), the mass ratio of the reformed residuum to n-hexadecene is 1: (1-10).

8. The process for producing aromatic hydrocarbon oil for mesophase pitch according to claim 3, wherein in the step (4), the reaction is carried out under the protection of inert gas; the reaction temperature is 300-350 ℃, the reaction time is 2-5 hours, and the reaction pressure is 1.0-3.0 MPa; preferably, the inert gas is nitrogen or argon.

9. The process for producing aromatic hydrocarbon oil for mesophase pitch as claimed in claim 3, wherein in the step (5), the distillation temperature is 200℃and the pressure is 1000Pa.

10. Use of an aromatic oil for mesophase pitch according to any one of claims 1 or 2 for the preparation of mesophase pitch or carbon materials.