Method for refining coal-tar pitch raw material and application thereof

Abstract

The present application relates to the technical field of material, and especially relates to a coal pitch raw material refining method and application thereof, and the coal pitch raw material refining method comprises the following steps: mixing the coal pitch raw material with compound solvent oil to obtain a mixed liquid; introducing a carrier gas into the mixed liquid to perform pressurized hot filtration to obtain a filtrate; and performing vacuum distillation on the filtrate to obtain refined pitch. The coal pitch raw material refining method of the present application can obtain refined pitch with high purity, and the refined pitch can be applied in the preparation of carbon materials.

Description

Technical Field

[0001] This invention relates to the field of materials technology, and in particular to a method for refining coal tar pitch raw materials and its application. Background Technology

[0002] In the field of mesophase pitch preparation, the purification of raw materials is a crucial step affecting the performance of the final product. The core of this process lies in effectively removing harmful components such as native quinoline insolubles, ash, and mechanical impurities from the raw materials. Solvent filtration, as an important physical purification method, has become one of the continuously optimized process directions in this field due to its relatively mild operation and ability to balance purification effect and cost.

[0003] Mesophase pitch is a liquid crystal substance composed of flattened disc-shaped polycyclic aromatic hydrocarbon molecules, produced by the thermal condensation reaction of raw materials such as petroleum pitch, coal pitch, or pure aromatic hydrocarbons. It is a core precursor for the preparation of high-performance carbon fibers, needle coke, and other high-end carbon materials. The quality of the raw oil directly determines the molecular structure uniformity, spinnability, and mechanical properties of the final carbon fibers. If the raw material contains excessive amounts of native quinoline insolubles, it will severely hinder the fusion and development of mesophase microspheres, easily forming an unfavorable mosaic structure; while ash and mechanical impurities will significantly affect the pitch's viscosity, softening point, and other rheological properties, and may become defect sources in subsequent spinning or graphitization processes, reducing material performance.

[0004] Currently, industrial methods for purifying and refining asphalt feedstocks mainly include hydrochemical modification, solvent extraction sedimentation, and centrifugation. While hydrochemical modification can improve feedstock composition, it typically involves high-pressure reaction conditions and expensive catalysts, resulting in complex processes and high equipment investment. Solvent extraction sedimentation (which can be considered a preliminary process for solvent filtration) and centrifugation are widely used, but in practice, they often face problems such as high energy consumption, large organic solvent consumption, limited removal efficiency for micron- or submicron-sized impurities, and issues related to solvent recovery and potential environmental pollution. This is especially true for coal tar pitch feedstocks, which often contain residual fine impurities such as coal powder and coke particles, which are difficult to remove effectively using conventional hot-melt filtration or centrifugation methods, and may even lead to secondary polymerization of feedstock components due to high-temperature treatment. Although some studies have used advanced technologies such as supercritical fluid extraction for feedstock refining, these methods often have stringent process control requirements and high equipment costs, making it difficult to meet the economic and stability requirements of large-scale industrial production.

[0005] Therefore, it is of great significance to seek a refining method for coal tar pitch that is efficient, low-consumption, and can significantly reduce the impurity content in the raw materials. Summary of the Invention

[0006] To solve at least one of the above-mentioned technical problems, the present invention provides a method for refining coal tar pitch raw materials and its application.

[0007] In one aspect, the present invention provides a method for refining coal tar pitch raw material, comprising: mixing coal tar pitch raw material with composite solvent oil to obtain a mixed liquid; passing carrier gas into the mixed liquid and performing pressurized hot filtration to obtain a filtrate; and performing vacuum distillation on the filtrate to obtain refined pitch; wherein the pressurized hot filtration employs a single-layer filtration system.

[0008] In some embodiments, the mass ratio of coal tar pitch raw material to composite solvent oil in the mixed liquid is 1:(1~5), for example, it can be 1:1.5, 1:2.4, 1:3.2, 1:3.9, 1:4.2, 1:4.8, etc.

[0009] In some embodiments, the coal tar pitch raw material includes at least one of low-temperature coal tar pitch and medium-temperature coal tar pitch.

[0010] In some embodiments, the composite solvent oil includes at least one of phenolic oil, naphthalene oil, kerosene, wash oil, and anthracene oil; and / or, the carrier gas is an inert gas.

[0011] In some embodiments, the mass ratio of kerosene to wash oil in the composite solvent oil is 1:(3~6), for example, it can be 1:3.5, 1:4.2, 1:4.9, 1:5.4, 1:5.8, etc.; and / or, the inert gas includes at least one of nitrogen and helium.

[0012] In some embodiments, pressurized heat filtration is performed under pressure of 0.1 to 1 MPa (e.g., 0.3 MPa, 0.6 MPa, 0.7 MPa, 0.8 MPa, 0.9 MPa, etc.) and temperature of 40 to 160°C (e.g., 43°C, 79°C, 93°C, 128°C, 148°C, etc.).

[0013] In some embodiments, in the single-layer filtration system, the filter layer is prepared by at least one of the following materials: sintered ceramic with a pore size of 1-10 μm (e.g., 2 μm, 4 μm, 6 μm, 7 μm, 8 μm, 9 μm, etc.), sintered stainless steel filter screen with a mesh size of 500-5000 (e.g., 600 mesh, 1600 mesh, 2800 mesh, 3700 mesh, 4600 mesh, etc.), and filter cloth with a mesh size of 500-2000 (e.g., 600 mesh, 800 mesh, 1300 mesh, 1600 mesh, 1900 mesh, etc.).

[0014] In some embodiments, the vacuum degree of the vacuum distillation is 0.05~0.1MPa (e.g., it can be 0.06MPa, 0.07MPa, 0.08MPa, 0.09MPa, 0.096MPa, etc.), and the temperature is 80~180℃ (e.g., it can be 90℃, 120℃, 130℃, 160℃, 170℃, etc.).

[0015] In some embodiments, the refined bitumen contains less than 0.02% virgin quinoline insolubles and less than 100 ppm ash.

[0016] In another aspect, the present invention provides an application of refined pitch obtained by the above-mentioned coal tar pitch raw material refining method in the preparation of carbon materials.

[0017] The technical solution provided by this invention has the following advantages: The refining method for coal tar pitch of the present invention, through the synergistic effect of composite solvent oil and pressurized hot filtration, prepares high-purity refined pitch. Specifically, the combination of "composite solvent oil" and "carrier gas introduced during filtration while maintaining pressurized heating" significantly improves the dissolution and separation efficiency of coal tar pitch, effectively preventing filter clogging, and thus significantly improving the purity of the refined pitch. The refined pitch obtained by the refining method of the present invention has a primary quinoline insoluble content of less than 0.02% and an ash content of less than 100 ppm, indicating high purity.

[0018] The coal tar pitch refining method of the present invention ensures that the refined pitch obtained has ultra-high purity while also taking into account the process efficiency and ease of operation (for example, the use of a high-efficiency single-layer filtration system in pressurized hot filtration has the characteristics of high filtration efficiency and easy operation), so that the coal tar pitch refining method of the present invention has the dual advantages of process controllability and low cost. Detailed Implementation

[0019] To better understand the above-mentioned objectives, features, and advantages of the present invention, the solutions of the present invention will be further described below. It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other.

[0020] Many specific details are set forth in the following description in order to provide a full understanding of the invention, but the invention may also be practiced in other ways different from those described herein; obviously, the embodiments in the specification are only some embodiments of the invention, and not all embodiments.

[0021] According to an embodiment of the present invention, a method for refining coal tar pitch raw material is provided, comprising: mixing coal tar pitch raw material with composite solvent oil to obtain a mixed liquid; passing carrier gas into the mixed liquid and performing pressurized hot filtration to obtain a filtrate; and performing vacuum distillation on the filtrate to obtain refined pitch; wherein the pressurized hot filtration adopts a single-layer filtration system.

[0022] The coal tar pitch refining method of this invention employs an "optimized composite solvent oil system" combined with "pressurized hot filtration," which significantly improves the dissolution and separation efficiency of coal tar pitch, resulting in high-purity refined pitch. Specifically, the coal tar pitch raw material is fully dissolved using a composite solvent oil. The wash oil in the composite solvent oil opens micelles and dissolves convertible components, while the kerosene in the composite solvent oil reduces viscosity and promotes penetration. Together, they uniformly disperse impurities and inhibit agglomeration. Pressurized hot filtration, driven by carrier gas disturbance and pressure, achieves rapid separation of the solid and liquid phases at high temperatures, avoiding membrane clogging and efficiently removing quinoline insolubles to obtain high-purity refined pitch.

[0023] In some embodiments of the present invention, a method for refining coal tar pitch raw materials includes the following steps: (1) Coal tar pitch raw material and composite solvent oil are mixed at a mass ratio of 1:(1~5) (for example, it can be 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5, etc.), and heated and stirred at a temperature of 40~160℃ (for example, it can be 48℃, 78℃, 96℃, 108℃, 129℃, 156℃, etc.) to obtain a mixed liquid; (2) The carrier gas is introduced into the mixed liquid obtained in step (1), and pressure heat filtration is carried out under the conditions of pressure of 0.1~1MPa (for example, it can be 0.3MPa, 0.4MPa, 0.6MPa, 0.8MPa, 0.9MPa, etc.) and temperature of 40~160℃ (for example, it can be 48℃, 78℃, 96℃, 108℃, 129℃, 156℃, etc.) to obtain filtrate; (3) The filtrate obtained in step (2) is subjected to vacuum distillation under the conditions of vacuum degree of 0.05~0.1MPa (for example, 0.06MPa, 0.07MPa, 0.08MPa, 0.09MPa, 0.095MPa, etc.) and temperature of 80~180℃ (for example, 86℃, 93℃, 128℃, 158℃, 176℃, etc.) to obtain refined asphalt.

[0024] In some embodiments of the present invention, in step (1), the composite solvent oil includes at least one of phenolic oil, naphthalene oil, kerosene, wash oil, and anthracene oil.

[0025] In some embodiments of the present invention, in step (1), when the composition of the composite solvent oil is kerosene and wash oil, the mass ratio of kerosene and wash oil is in the range of 1:(3~6), for example, it can be 1:3.1, 1:3.6, 1:4.3, 1:5.1, 1:5.9, etc.

[0026] In some embodiments of the present invention, in step (2), the pressurized hot filtration adopts a single-layer filtration system; wherein, the filter layer is prepared by at least one of sintered ceramic with a pore size of 1~10μm, sintered stainless steel filter screen with a mesh size of 500~5000, and filter cloth with a mesh size of 500~2000.

[0027] In some embodiments of the present invention, in step (2), preferably, the filter layer is composed of one or two types of sintered stainless steel filter screen of 500-5000 mesh and filter cloth of 500-2000 mesh.

[0028] In some embodiments of the present invention, in step (3), the refined asphalt obtained contains less than 0.02% virgin quinoline insolubles and less than 100 ppm ash.

[0029] The technical solution of the present invention will be further explained and illustrated below through specific embodiments.

[0030] All reagents used in the following examples are commercially available.

[0031] Example 1 (1) Mix low-temperature coal tar pitch raw material and composite solvent oil in a mass ratio of 1:2, heat and stir at 60°C to obtain a mixed liquid; wherein, the composite solvent oil is composed of kerosene and wash oil in a mass ratio of 1:3. (2) Nitrogen gas is introduced into the mixed liquid obtained in step (1), and pressure heat filtration is performed under the conditions of 0.5 MPa and 80°C to obtain filtrate; wherein, the filter layer is a 2000-mesh stainless steel sintered filter screen. (3) The filtrate obtained in step (2) is subjected to vacuum distillation at a vacuum degree of 0.05 MPa and a temperature of 90°C to obtain refined asphalt.

[0032] The refined bitumen obtained contained 0.015% virgin quinoline insolubles according to GB / T 2293-2019 and 80 ppm ash according to GB / T 2295-2008.

[0033] Example 2 (1) Mix low-temperature coal tar pitch raw material and composite solvent oil in a mass ratio of 1:2, heat and stir at 120°C to obtain a mixed liquid; wherein, the composite solvent oil is composed of kerosene and wash oil in a mass ratio of 1:6. (2) Nitrogen gas is introduced into the mixed liquid obtained in step (1), and pressure heat filtration is performed under the conditions of 0.8 MPa and 90°C to obtain filtrate; wherein, the filter layer is a 5000-mesh stainless steel sintered filter screen. (3) The filtrate obtained in step (2) is subjected to vacuum distillation at a vacuum degree of 0.06 MPa and a temperature of 130 °C to obtain refined asphalt.

[0034] The refined bitumen obtained contained 0.013% virgin quinoline insolubles according to GB / T 2293-2019 and 60 ppm ash according to GB / T 2295-2008.

[0035] Example 3 (1) Mix low-temperature coal tar pitch raw material and composite solvent oil in a mass ratio of 1:5, heat and stir at 120°C to obtain a mixed liquid; wherein, the composite solvent oil is composed of kerosene and wash oil in a mass ratio of 1:6. (2) Nitrogen gas is introduced into the mixed liquid obtained in step (1), and pressure heat filtration is performed under the conditions of 0.8 MPa and 90°C to obtain filtrate; wherein, the filter layer is a 5000-mesh stainless steel sintered filter screen. (3) The filtrate obtained in step (2) is subjected to vacuum distillation at a vacuum degree of 0.06 MPa and a temperature of 130 °C to obtain refined asphalt.

[0036] The refined bitumen obtained contained 0.011% virgin quinoline insolubles according to GB / T 2293-2019 and 45 ppm ash according to GB / T 2295-2008.

[0037] Example 4 (1) Mix low-temperature coal tar pitch raw material and composite solvent oil in a mass ratio of 1:3, heat and stir at 120°C to obtain a mixed liquid; wherein, the composite solvent oil is composed of kerosene and wash oil in a mass ratio of 1:6. (2) Nitrogen gas is introduced into the mixed liquid obtained in step (1), and pressure heat filtration is performed under the conditions of 0.8 MPa and 90°C to obtain filtrate; wherein, the filter layer is a 5000-mesh stainless steel sintered filter screen. (3) The filtrate obtained in step (2) is subjected to vacuum distillation at a vacuum degree of 0.06 MPa and a temperature of 130 °C to obtain refined asphalt.

[0038] The refined bitumen obtained contained 0.012% virgin quinoline insolubles according to GB / T 2293-2019 and 51 ppm ash according to GB / T 2295-2008.

[0039] Comparative Example 1 (1) Mix low-temperature coal tar pitch raw material and wash oil in a mass ratio of 1:2, heat and stir at 60°C to obtain a mixed liquid; (2) Nitrogen gas is introduced into the mixed liquid obtained in step (1), and pressure heat filtration is performed under the conditions of 0.5 MPa and 80°C to obtain filtrate; wherein, the filter layer is a 2000-mesh stainless steel sintered filter screen. (3) The filtrate obtained in step (2) is subjected to vacuum distillation at a vacuum degree of 0.05 MPa and a temperature of 90°C to obtain refined asphalt.

[0040] The refined bitumen obtained contained 0.25% virgin quinoline insolubles according to GB / T 2293-2019 and 500 ppm ash according to GB / T2295-2008.

[0041] Comparative Example 2 (1) Mix low-temperature coal tar pitch raw material and wash oil in a mass ratio of 1:2, heat and stir at 120°C to obtain a mixed liquid; (2) Nitrogen gas is introduced into the mixed liquid obtained in step (1), and pressure heat filtration is performed under the conditions of 0.8 MPa and 90°C to obtain filtrate; wherein, the filter layer is a 5000-mesh stainless steel sintered filter screen. (3) The filtrate obtained in step (2) is subjected to vacuum distillation at a vacuum degree of 0.06 MPa and a temperature of 130 °C to obtain refined asphalt.

[0042] The refined bitumen obtained had a virgin quinoline insoluble content of 0.08% as determined by GB / T 2293-2019 and an ash content of 650 ppm as determined by GB / T 2295-2008.

[0043] Comparative Example 3 (1) Mix low-temperature coal tar pitch raw material and kerosene at a mass ratio of 1:2, heat and stir at 120°C to obtain a mixed liquid; (2) Nitrogen gas is introduced into the mixed liquid obtained in step (1), and pressure heat filtration is performed under the conditions of 0.8 MPa and 90°C to obtain filtrate; wherein, the filter layer is a 5000-mesh stainless steel sintered filter screen. (3) The filtrate obtained in step (2) is subjected to vacuum distillation at a vacuum degree of 0.06 MPa and a temperature of 130 °C to obtain refined asphalt.

[0044] The refined bitumen obtained contained 0.15% virgin quinoline insolubles according to GB / T 2293-2019 and 580 ppm ash according to GB / T2295-2008.

[0045] in conclusion: Based on the data from Examples 1-4 and Comparative Examples 1-3, the following conclusions can be drawn: (1) In the mixed liquid, the mass ratio of coal tar pitch raw material to composite solvent oil is 1:(1~5), preferably 1:3. This is because when the mass ratio of coal tar pitch raw material to composite solvent oil changes from 1:3 to 1:5, the detection results of virgin quinoline insolubles and ash content hardly change; considering economic factors, the optimal mass ratio of coal tar pitch raw material to composite solvent oil is 1:3.

[0046] (2) When the components of the composite solvent oil contain only one of wash oil or kerosene, the detection of native quinoline insolubles and ash is much higher than that of the composite solvent oil containing both wash oil and kerosene.

[0047] In summary, the coal tar pitch refining method of this invention, through a physical purification technique combining optimized solvent and filtration, yields high-purity refined pitch. This is of great significance for improving the quality of mesophase pitch and promoting the development of the high-performance carbon materials industry. Furthermore, the refining method of this invention also improves the refining rate of coal tar pitch by optimizing pretreatment and reaction conditions, offering advantages such as process controllability and low cost.

[0048] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0049] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments described herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for refining coal tar pitch raw materials, characterized in that, include: Coal tar pitch raw material is mixed with composite solvent oil to obtain a mixed liquid; The carrier gas is introduced into the mixed liquid and subjected to pressurized thermal filtration to obtain the filtrate; The filtrate was subjected to vacuum distillation to obtain refined asphalt; Among them, the pressurized heat filtration uses a single-layer filtration system.

2. The method for refining coal tar pitch raw material according to claim 1, characterized in that, In the mixed liquid, the mass ratio of coal tar pitch raw material to composite solvent oil is 1:(1~5).

3. The method for refining coal tar pitch raw material according to claim 1 or 2, characterized in that, The coal tar pitch raw material includes at least one of low-temperature coal tar pitch and medium-temperature coal tar pitch.

4. The method for refining coal tar pitch raw material according to any one of claims 1 to 3, characterized in that, The composite solvent oil includes at least one of phenolic oil, naphthalene oil, kerosene, wash oil, and anthracene oil; And / or, the carrier gas is an inert gas.

5. The method for refining coal tar pitch raw material according to claim 4, characterized in that, In the composite solvent oil, the mass ratio of kerosene to wash oil is 1:(3~6); And / or, the inert gas includes at least one of nitrogen and helium.

6. The method for refining coal tar pitch raw material according to any one of claims 1 to 5, characterized in that, Pressurized heat filtration is performed under pressure conditions of 0.1~1MPa and temperature conditions of 40~160℃.

7. The method for refining coal tar pitch raw material according to any one of claims 1 to 6, characterized in that, In the single-layer filtration system, the filter layer is made of at least one of the following materials: sintered ceramic with a pore size of 1-10 μm, sintered stainless steel filter screen with a mesh size of 500-5000 mesh, and filter cloth with a mesh size of 500-2000 mesh.

8. The method for refining coal tar pitch raw material according to any one of claims 1 to 7, characterized in that, The vacuum degree of the vacuum distillation is 0.05~0.1MPa, and the temperature is 80~180℃.

9. The method for refining coal tar pitch raw material according to any one of claims 1 to 8, characterized in that, The refined asphalt contains less than 0.02% virgin quinoline insolubles and less than 100 ppm ash.

10. The application of refined pitch obtained by the refining method of coal tar pitch raw material according to any one of claims 1 to 9 in the preparation of carbon materials.