Preparation method and application of spinnable mesophase pitch

Abstract

The invention belongs to the technical field of continuous processing of carbonaceous mesophase materials, and particularly relates to a preparation method of spinnable mesophase pitch. The preparation method comprises the following steps: in a nitrogen atmosphere, continuously injecting coal liquefied asphalt as a raw material into a tubular cavity of a dynamic tubular reactor through a pipeline; heating to raise the temperature, adjusting the reaction pressure, continuously stirring, and carrying out a thermal polycondensation reaction; conveying the material after the primary reaction to a molecular reduced pressure rectifying tower, raising the temperature and pressure, collecting the fraction as mesophase pitch, refluxing the residual fraction into the dynamic tubular reactor, and continuing to perform thermal polycondensation reaction; the obtained mesophase pitch is sequentially subjected to melt spinning, pre-oxidation, carbonization and / or graphitization, and the mesophase pitch-based carbon fiber is prepared. Continuous flow can be realized by using the dynamic tubular reactor, so that the utilization rate of reactants is increased, the reaction time is shortened, and the overall reaction efficiency is improved. The raw material utilization rate is improved, and the reaction cost is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of continuous processing of carbonaceous mesophase materials, and particularly relates to a preparation method and application of spinnable mesophase pitch. Background Art

[0002] Coal liquefaction pitch, as a by-product of coal liquefaction technology, is a liquid fuel formed by the chemical reaction of coal with specific solvents under high temperature and high pressure environments. This pitch has significant characteristics of high viscosity, high boiling point, and high carbon content, giving it wide application potential in multiple fields. It can not only be used as a key material in road construction to improve the durability and performance of roads, but also be used in the production of waterproof materials to enhance the waterproof performance of materials. In addition, coal liquefaction pitch also plays an important role in the production of carbon materials, providing raw materials for manufacturing high-quality carbon products.

[0003] Mesophase pitch-based carbon materials are prepared by regulating the pitch during heat treatment to cause phase separation. It transforms into a short-range ordered graphitized structure. In addition, this special crystal structure endows the carbon materials derived from mesophase pitch with advantages such as good stability, corrosion resistance, electrical conductivity, thermal conductivity, and high modulus, making them occupy an important position in many fields such as electrode materials, catalyst carriers, and high-performance composite materials. The development of this material is based on an in-depth understanding of the complex microstructure formed by pitch at high temperatures and the unremitting pursuit of the performance of carbon materials. Its highly graphitized structure endows the material with extraordinary electrical conductivity, enabling it to play a key role in energy storage and conversion devices. At the same time, the thermal stability of mesophase pitch-based carbon fibers enables them to withstand extreme temperature environments, making them an ideal choice for high-tech fields such as aerospace and nuclear industries. In addition, its chemical stability ensures that its performance remains unchanged in various chemical reactions, thus performing excellently in catalyst carrier applications. Through these excellent characteristics, mesophase pitch-based carbon fibers have promoted the development of related scientific and technological fields.

[0004] Flow chemistry technology, known as continuous flow chemistry, is an advanced process for carrying out chemical reactions in a closed pipeline system. Compared with traditional batch chemical reactions, this technology has significant advantages. The flow chemistry process can significantly improve production efficiency. By precisely controlling reaction conditions such as temperature, pressure, and reaction time, rapid and efficient chemical conversions can be achieved. This technology performs well in reducing energy consumption and costs. Due to the small reactor volume and high heating and cooling efficiency, the energy consumption is significantly reduced. In addition, the flow chemistry process has unique advantages in reducing waste generation. The precise control of reaction conditions greatly reduces the generation of by-products and waste, thus improving the utilization rate of raw materials. This technology is convenient for modular design and automated operation, making the chemical production process more flexible, easy to expand and adjust, and adaptable to production requirements of different scales. The dynamic tubular reactor, as a continuous flow chemical reaction device, effectively promotes the progress of chemical reactions by achieving dynamic mixing of fluids inside the tube. This reactor is known for its simple structure, convenient operation, and controllability of reaction conditions, and can achieve efficient and uniform reaction effects. It is widely used in many fields such as chemical industry, pharmaceuticals, and food processing, and is applicable to various chemical reaction types such as synthesis, decomposition, and polymerization. However, there are few reports on the method of preparing spinnable mesophase pitch-based carbon materials using a dynamic tubular reactor. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method for preparing spinnable mesophase pitch and its application. Using coal liquefaction pitch as the raw material and a dynamic tubular reactor for the reaction, the utilization rate of coal liquefaction pitch is improved, and the efficient preparation of spinnable mesophase pitch is realized. The technical solution adopted is as follows:

[0006] A method for preparing spinnable mesophase pitch uses a dynamic tubular reactor. One end of the dynamic tubular reactor is connected to a nitrogen gas cylinder through a pipeline, and the other end is connected to a molecular vacuum rectification tower through a pipeline. And there is also a pipeline for reflux connection between the molecular vacuum rectification tower and the dynamic tubular reactor. The steps included in the method are as follows:

[0007] (1) Open the nitrogen gas cylinder to displace the air in the tube cavity of the dynamic tubular reactor;

[0008] (2) Under a nitrogen atmosphere, continuously inject coal liquefaction pitch as the raw material into the tube cavity of the dynamic tubular reactor through the pipeline;

[0009] (3) Heat to raise the temperature, adjust the reaction pressure, and continuously stir to carry out thermal condensation polymerization reaction;

[0010] (4) Open the discharge port, transport the preliminarily reacted material to the molecular vacuum rectification tower through the pipeline, then raise the temperature and pressure, and collect the fraction as mesophase pitch;

[0011] The remaining fraction is refluxed through a pipeline into the dynamic tubular reactor to continue the thermal polycondensation reaction.

[0012] Preferably, in the step (1), the air in the lumen of the dynamic tubular reactor is displaced by nitrogen at least once.

[0013] Preferably, in the step (2), the coal liquefaction pitch is one or more of coal tar pitch, hydro-upgraded coal tar pitch, and hydro-upgraded coal liquefaction pitch, and the ash content is less than 500 ppm.

[0014] Preferably, in the step (3), the reaction temperature is 300-450 °C, the reaction pressure is 0.1-0.3 MPa, the stirring opening is 95%, and the reaction time is 2-4 h.

[0015] Preferably, the stirring opening is 95% during the reaction.

[0016] Preferably, in the step (4), the vacuum distillation temperature is 350-400 °C and the pressure is -100 to -200 KPa.

[0017] Preferably, the residual carbon value of the obtained mesophase pitch is 80-85%.

[0018] Application of the mesophase pitch prepared by the method for preparing a spinnable mesophase pitch of the present invention in carbon fibers. The obtained mesophase pitch is successively subjected to melt spinning, pre-oxidation, carbonization, and / or graphitization to obtain mesophase pitch-based carbon fibers; the density is 1.65-1.75 g / cm, the tensile strength reaches 2500 Mpa, and the modulus reaches 2000 Gpa.

[0019] The present invention uses coal liquefaction pitch as the main raw material and performs a thermal polycondensation reaction using a dynamic tubular reactor. During the reaction, a series of complex chemical changes occur to the coal liquefaction pitch under high temperature and high pressure conditions to generate mesophase pitch and incompletely converted coal pitch. To ensure product quality and production efficiency, this process uses a vacuum distillation fractionation technology to effectively separate the mesophase pitch from the incompletely converted coal pitch. The separated mesophase pitch can be used to prepare high-performance pitch-based carbon fibers, while the incompletely converted coal liquefaction pitch flows back into the dynamic tubular reactor through a pipeline to achieve continuous production.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] The present invention uses a dynamic tubular reactor to replace the batch kettle type. The dynamic tubular reactor can achieve continuous flow, thereby improving the utilization rate of reactants, reducing the reaction time, and enhancing the overall reaction efficiency. In addition, since the contact time between the reactants and the catalyst in the flow process is shortened, the reaction heat is more easily dissipated, thus reducing energy consumption. The dynamic tubular reactor can achieve precise control of parameters such as temperature, pressure, and flow rate, which is conducive to optimizing the reaction conditions and improving the product quality. Compared with the traditional process, the equipment structure of the dynamic tubular reactor is simple and the investment cost is relatively low.

[0022] After the coal tar pitch undergoes a thermal polycondensation reaction, part of it undergoes thermal conversion. The formed mixture is subjected to molecular vacuum rectification to separate the mesophase pitch fiberizable and the unconverted coal tar pitch in the mixture, and then the mesophase pitch fiberizable can be obtained. The unconverted coal liquefied pitch is further reacted through reflux in the dynamic tubular reactor to be further converted into mesophase pitch fiberizable, thereby improving the reaction efficiency and raw material utilization rate and reducing the reaction cost.

[0023] The present invention simplifies the continuous production method of mesophase pitch, enables the continuous production of mesophase pitch, and the obtained mesophase pitch fiberizable and its derivative carbon fiber have good uniformity, good spinning performance, high strength and modulus. The automation level is high. It is a brand-new production process for mesophase pitch with relatively low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a flow chart of the method of the present invention DETAILED DESCRIPTION OF THE INVENTION

[0025] The drawings are only for illustrative purposes; the following detailed description only represents some embodiments and aims to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0026] The model of the dynamic tubular reactor used in the present invention is horizontal VTRWSS0014 / VTRWHS0014, which can be purchased through commercial channels. Other methods and means not mentioned herein are all carried out in the usual manner in the prior art, and other instruments not clearly specified can be purchased through commercial channels or have the commonly used specifications.

[0027] Example 1

[0028] As Figure 1 shown, a method for preparing fiberizable mesophase pitch uses a dynamic tubular reactor. One end of the dynamic tubular reactor is connected to a nitrogen gas cylinder through a pipeline, and the other end is connected to a molecular vacuum rectification tower through a pipeline. Moreover, a reflux pipeline is also connected between the molecular vacuum rectification tower and the dynamic tubular reactor. The steps included in the method are as follows:

[0029] First, open the nitrogen gas cylinder and replace the air in the dynamic tube 3 times to fill the lumen of the dynamic tube reactor with high-purity nitrogen to 0.1 Mpa;

[0030] Under a nitrogen atmosphere, coal liquefied asphalt with an ash content of less than 500 ppm is added to the lumen of the dynamic tube reactor through a pipeline at a flow rate of 0.75 L / h;

[0031] Heat, and carry out thermal polycondensation reaction at 420 °C for 4 hours. The asphalt conversion rate is about 85%. Then, while it is hot, separate it with a molecular vacuum rectification device at -100 Kpa and 390 °C;

[0032] Separate the unreacted asphalt, and then reflux it through the pipeline back to the dynamic tube reactor to continue the thermal polycondensation reaction.

[0033] Finally, obtain mesophase pitch. After spinning, pre-oxidation, carbonization, and graphitization, obtain spinable mesophase pitch-based carbon fiber with a modulus of 1800 GPa.

[0034] Example 2

[0035] First, open the nitrogen gas cylinder and replace the air in the dynamic tube 3 times, and finally fill the lumen of the dynamic tube reactor with high-purity nitrogen to 0.1 Mpa;

[0036] Under a nitrogen atmosphere, coal liquefied asphalt with an ash content of less than 400 ppm is added to the lumen of the dynamic tube reactor through a pipeline at a flow rate of 0.75 L / h. Carry out thermal polycondensation reaction at 420 °C for 4 hours. The asphalt conversion rate is about 89%. Then, while it is hot, separate it with a molecular vacuum rectification device at -100 Kpa and 390 °C. Separate the unreacted asphalt, and then reflux it through the pipeline back to the dynamic tube reactor. Finally, obtain mesophase pitch. After spinning, pre-oxidation, carbonization, and graphitization, obtain carbon fiber with a modulus of 1800 GPa.

[0037] Other parts not mentioned are the same as in Example 1.

[0038] Example 3

[0039] The difference from Example 1 is that under a nitrogen atmosphere, coal liquefied asphalt with an ash content of less than 300 ppm is added to the lumen of the dynamic tube reactor through a pipeline at a flow rate of 0.75 L / h; carry out thermal polycondensation reaction for 3 hours, and the asphalt conversion rate is about 90%.

[0040] Finally, obtain mesophase pitch. After spinning, pre-oxidation, carbonization, and graphitization, obtain carbon fiber with a modulus of 2000 GPa.

[0041] Other parts not mentioned are the same as in Example 1.

[0042] Example 4

[0043] The difference from Example 1 is that the inner cavity of the dynamic tubular reactor is filled with high-purity nitrogen gas to 0.3 Mpa; the thermal polycondensation reaction is carried out at 450 °C for 4 hours, and the asphalt conversion rate is about 85%.

[0044] Finally, mesophase pitch is obtained. After spinning, pre-oxidation, carbonization, and graphitization, carbon fibers with a modulus of 1600 GPa are obtained.

[0045] Other parts not mentioned are the same as in Example 1.

[0046] Example 5

[0047] The difference from Example 1 is that the inner cavity of the dynamic tubular reactor is filled with high-purity nitrogen gas to 0.3 Mpa; under a nitrogen atmosphere, coal liquefied asphalt with an ash content of less than 400 ppm is added to the inner cavity of the dynamic tubular reactor through a pipeline at a flow rate of 0.75 L / h; the thermal polycondensation reaction is carried out at 450 °C for 4 hours, and the asphalt conversion rate is about 83%; separation is carried out using a molecular vacuum rectification device at -200 Kpa and 390 °C while it is still hot.

[0048] Finally, mesophase pitch is obtained. After spinning, pre-oxidation, carbonization, and graphitization, carbon fibers with a modulus of 1750 GPa are obtained.

[0049] Other parts not mentioned are the same as in Example 1.

[0050] Example 6

[0051] The difference from Example 1 is that the inner cavity of the dynamic tubular reactor is filled with high-purity nitrogen gas to 0.5 Mpa; under a nitrogen atmosphere, coal liquefied asphalt with an ash content of less than 500 ppm is added to the inner cavity of the dynamic tubular reactor through a pipeline at a flow rate of 1.5 L / h; the thermal polycondensation reaction is carried out at 420 °C for 2 hours, and the asphalt conversion rate is about 55%.

[0052] Finally, mesophase pitch is obtained. After spinning, pre-oxidation, carbonization, and graphitization, carbon fibers with a modulus of 1200 GPa are obtained.

[0053] Other parts not mentioned are the same as in Example 1.

[0054] Compare the reaction conditions of Examples 1 - 6, and the results are shown in Table 1.

[0055]

[0056] As can be seen from the above embodiments, when the pressure of the thermal polycondensation reaction is 0.1 Mpa, the ash content of the raw material is less than 300 ppm, the temperature of the thermal polymerization reaction is 420 °C, and the time is 3 hours, the asphalt conversion rate is the highest, which is 90%. The molecular vacuum distillation equipment is separated at -100 Kpa and 390 °C. Finally, the mesophase pitch is obtained and after spinning, pre-oxidation, carbonization, and graphitization, the obtained carbon fiber has the highest modulus.

[0057] Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions, or substitutions made by those skilled in the art within the scope of the essence of the present invention should also fall within the protection scope of the present invention.

Claims

1. A preparation method of spinnable mesophase pitch, using a dynamic tubular reactor, characterized in that, One end of a dynamic tubular reactor is connected to a nitrogen gas cylinder through a pipeline, and the other end is connected to a molecular vacuum rectification column. A pipeline for reflux is also connected between the molecular vacuum rectification column and the dynamic tubular reactor. The steps of the method include: (1) Open the nitrogen gas cylinder to displace the air in the lumen of the dynamic tubular reactor; (2) Under a nitrogen atmosphere, continuously inject coal liquefied asphalt as a raw material into the lumen of the dynamic tubular reactor through a pipeline; (3) Heat to raise the temperature, adjust the reaction pressure, and continuously stir to carry out thermal polycondensation reaction; (4) Open the discharge port, transport the preliminarily reacted material to the molecular vacuum rectification column through a pipeline, then raise the temperature and pressure, collect the distillate as mesophase pitch, and return the remaining distillate to the dynamic tubular reactor through a pipeline to continue the thermal polycondensation reaction.

2. The preparation method of a spinnable mesophase pitch according to claim 1, characterized in that, In the step (1), displace the air in the lumen of the dynamic tubular reactor with nitrogen at least once.

3. The preparation method of a spinnable mesophase pitch according to claim 1, characterized in that In the step (2), the coal liquefied asphalt is one or more of coal tar pitch, hydro-upgraded coal tar pitch, and hydro-upgraded coal liquefied asphalt, and the ash content is less than 500 ppm.

4. The preparation method of a spinnable mesophase pitch according to claim 1, characterized in that, In the step (3), the reaction temperature is 300 - 450 °C, the reaction pressure is 0.1 - 0.3 MPa, the stirring opening is 95%, and the reaction time is 2 - 4 h.

5. The preparation method of a spinnable mesophase pitch according to claim 4, characterized in that, The stirring opening is 95% during the reaction.

6. The preparation method of a spinnable mesophase pitch according to claim 1, characterized in that, In the step (4), the vacuum rectification temperature is 350 - 400 °C, and the pressure is -100 - -200 KPa.

7. The preparation method of a spinnable mesophase pitch according to claim 1, characterized in that, The residual carbon value of the obtained mesophase pitch is 80 - 85%.

8. Use of the mesophase pitch prepared by the method for preparing a spinnable mesophase pitch according to any one of claims 1-7 in carbon fiber precursors, characterized in that, Carry out melt spinning, pre-oxidation, carbonization, and / or graphitization on the obtained mesophase pitch in sequence to obtain mesophase pitch-based carbon fiber; the density is 1.65 - 1.75 g / cm, the tensile strength reaches 2500 Mpa, and the modulus reaches 2000 Gpa.

Images