A method for preparing coal-based isotropic carbon

Abstract

The application aims to provide a preparation method of coal-based isotropic carbon, and adjust the isotropic degree of the carbon material according to different application fields. The method is to prepare isotropic carbon by taking coal-based pitch as raw material, adding organic quinoline insoluble matter in a certain proportion, removing the fraction segment before anthracene oil through normal pressure or reduced pressure distillation, and heating again to 470-500 DEG C. The advantages of the application are as follows: the isotropic degree of the carbon material is improved by controlling the thermal reaction process through the addition of quinoline insoluble matter; the application range of the raw material is improved, the poor reactivity of the raw material is modified, and the reactivity is improved; according to different application fields, the performance indexes of the product can be adjusted. A simple, economical and efficient method for preparing isotropic carbon is provided.

Description

Technical Field

[0001] This invention relates to the field of novel processes for preparing isotropic carbon, and particularly to a method for preparing coal-based isotropic carbon. Background Technology

[0002] Isotropic carbon is a high-quality carbon material with characteristics such as high strength, high density, and high thermal conductivity. Its applications include nuclear graphite, semiconductor silicon and photovoltaic industries, mold graphite, and other emerging high-end materials. It is also a high-end carbon material in the fields of atomic energy and aerospace.

[0003] The purpose of this invention is to provide a new and practical method for producing coal-based isotropic carbon materials. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing coal-based isotropic carbon, and to adjust the degree of isotropy of the carbon material according to different application fields. The method involves using coal-based pitch as raw material, adding a proportion of quinoline-insoluble matter, removing the anthracene oil fraction by atmospheric or vacuum distillation, and then reheating to 470-500℃ to produce isotropic carbon.

[0005] A method for preparing coal-based isotropic carbon materials is characterized by: adding quinoline-insoluble substances to the formula, allowing coal-based pitch to rapidly absorb the mother liquor in the form of "crystal nuclei" during the cracking and condensation reaction; and under suitable reaction conditions, preventing the small spheres from growing too large, ultimately solidifying the desired microstructure, thus adjusting the isotropic degree of the carbon material for application in various fields. The preparation method is as follows:

[0006] 1. Raw material preparation

[0007] Straight-run asphalt, medium-temperature asphalt, or modified asphalt are mixed in a formula ratio of 1:3:1 to form raw material asphalt. Then, demorphized anthracene oil is added to adjust the softening point to 43-65℃. The mixing temperature is controlled at 125±5℃, and the pressure is atmospheric pressure. The mixture is circulated for 24 hours, with the raw material asphalt being circulated once. The asphalt properties after mixing are as follows:

[0008]

[0009] 2. Production Method

[0010] Under a pressure of 2 MPa, the raw material asphalt and quinoline insolubles are mixed at a ratio of 5-15%:85-95% (the temperature of the raw material asphalt is 120-150℃, and the temperature of the quinoline insolubles is 80-100℃).

[0011] Further, after mixing, the mixture is sent to a preheating furnace and heated to 280-350°C before entering an atmospheric distillation column. The light, phenol, naphthalene, and washing components before the anthracene oil fraction are separated out. The column top temperature is 200-270°C, and the mixture is cooled to 30-60°C by a water cooler before entering the atmospheric distillation column separator.

[0012] Furthermore, the mixture after the removal of light components enters a heating furnace (steam is injected into the pipeline to prevent the material from reacting and coking; the steam injection ratio is 2.5-3% of the material, the steam temperature is above 280℃, and the pressure is 4MPa) and is heated to 470-500℃. Then it enters a carbonization tower, where the reaction pressure is 0.25MPa and the carbonization time is 24±4hr.

[0013] The advantages of this invention are its simple process and the relatively adjustable degree of isotropy of the isotropic carbon material, allowing the product to be applied in multiple directions.

[0014] The advantages and positive effects of this invention are as follows:

[0015] 1. By adding quinoline insolubles, the thermal reaction process is controlled, thereby improving the isotropy of carbon materials;

[0016] 2. Improve the applicability of raw materials, modify raw materials with poor reactivity, and improve their reactivity;

[0017] 3. Depending on the application field, the performance indicators of the product can be adjusted. Attached Figure Description

[0018] Figure 1 Production flow chart of this invention;

[0019] Figure 2 Microstructure of the product after adding 5% quinoline insolubles;

[0020] Figure 3 Microstructure of the product after adding 10% quinoline insolubles;

[0021] Figure 4 Microstructure of the product after adding 15% quinoline insolubles;

[0022] In the diagram: D-1, Asphalt tank; D-2, Anthracene oil tank; D-3, Raw material tank; D-4, Quinoline tank; D-5, Homogenizing tank; D-6, Atmospheric pressure separation tank; D-7, Positive pressure separation tank; F-1, Preheating furnace; F-2, Heating furnace; T-1, Atmospheric pressure distillation column; T-2, Positive pressure distillation column; T-3, Carbonization column; P-1, Asphalt pump; P-2, Anthracene oil pump; P-3, Raw material pump; P-4, Preheating pump; P-5, Heating pump; P-6, Light oil pump; P-7, Heavy oil pump. Detailed Implementation

[0023] The specific embodiments of the present invention will now be further described with reference to the accompanying drawings.

[0024] 1. Raw material preparation

[0025] Straight-run asphalt, medium-temperature asphalt, or modified asphalt are mixed in a formula ratio of 1:3:1 to form raw material asphalt. Then, demorphized anthracene oil is added to adjust the softening point to 43-65℃. The mixing temperature is controlled at 125±5℃, and the pressure is atmospheric pressure. The mixture is circulated for 24 hours, with the raw material asphalt being circulated once. The asphalt properties after mixing are as follows:

[0026] Softening point: 43-65℃;

[0027] Density (100℃): 1.18-1.22 g / cm³;

[0028] Quinoline insoluble matter: 0-5%;

[0029] β-component: 8-12%;

[0030] Ash content: <0.2%;

[0031] Sulfur content: <0.5%;

[0032] Nitrogen content: <1.0%.

[0033] 2. Production Method

[0034] First, the raw asphalt in the qualified raw material tank D-3 and the quinoline insolubles in the quinoline tank D-4 (temperature 80-100℃) are homogenized and mixed in a pipeline through pump P-3 at a ratio of 5-15%:85-95%, and then stirred in the homogenization tank D-5. The raw asphalt temperature is 120-150℃ and the pressure is 2Mpa to form a mixture.

[0035] Furthermore, the mixture is pumped by P-4 to the preheating furnace F-1 and heated to 280-350°C before entering the atmospheric distillation tower T-1. The light, phenolic, naphthalene, and washing components before the anthracene oil fraction are separated out. The temperature at the top of the tower is 200-270°C. The mixture is then cooled to 30-60°C by the water cooler E-1 before entering the atmospheric distillation tower separator D-6. The light component oil is treated as a byproduct. The non-condensable gas and coal gas are collected together with the non-condensable gas from the positive pressure tower separator as coking coal gas.

[0036] Furthermore, the mixture after the removal of light components is pumped by pump P-6 into heating furnace F-2 (steam is injected into the pipeline to prevent the material from reacting and coking; the steam injection ratio is 2.5-3% of the material, the steam temperature is above 280℃, and the pressure is 4MPa) and heated to 470-500℃. It then enters carbonization tower T-2, with a reaction pressure of 0.25MPa. Depending on the amount of quinoline insolubles added, special carbon materials with different degrees of isotropy are formed.

[0037] Furthermore, the vapor-liquid phase medium at 440-470℃ at the top of the carbonization tower T-2 enters the secondary distillation tower T-3 to recover the oil products cracked from the carbonization reaction. The pressure of the positive pressure distillation tower is 0.2 MPa, and the temperature of each tray can be controlled by adjusting the reflux: 350-380℃ at the bottom, 320-340℃ in the middle, and 132-164℃ at the top. The vapor phase from the positive pressure distillation tower passes through the water cooler E-2, and the temperature drops to 30-60℃ before entering the positive pressure tower separator to recover oil from different fractions as byproducts. The non-condensable gas and coal gas are collected together with the non-condensable gas from the atmospheric pressure tower separator as coking coal gas.

[0038] 3. Implementation Results

[0039] The results of implementing three formulations with added quinoline insolubles are listed below:

[0040]

Claims

1. A method for preparing coal-based isotropic carbon, characterized in that, Under 2 MPa pressure, the raw material and quinoline insolubles are mixed at a ratio of 85-95%:5-15%; the raw material is a mixture of straight-run pitch, medium-temperature pitch, and modified pitch in a ratio of 1:3:1, and after being circulated for 24 hours with decrystalline anthracene oil at 125±5℃ and atmospheric pressure; the temperature of the raw material is 120-150℃, and the temperature of the quinoline insolubles is 80-100℃; after mixing, the mixture is sent to a preheating furnace and heated to 280-350℃ before entering an atmospheric distillation column, where the light and flammable components before the anthracene oil fraction are separated. Phenol, naphthalene, and washing components are separated. The top temperature of the tower is 200-270℃. After being cooled to 30-60℃ by a water cooler, the mixture enters the atmospheric pressure tower separator. The mixture after the light components are removed enters the heating furnace. Steam is injected into the pipeline of the heating furnace to prevent the material from reacting and coking. The steam injection ratio is 2.5-3% of the material, the steam temperature is above 280℃, the pressure is 4 MPa, and the material is heated to 470-500℃. Then it enters the carbonization tower. The reaction pressure is 0.25 MPa, and the carbonization time is 24±4 hours to obtain coal-based isotropic carbon.

2. The method for preparing coal-based isotropic carbon according to claim 1, characterized in that, The asphalt properties after formulation of the raw materials are as follows: softening point: 43-65℃; density (100℃): 1.18-1.22 g / cm³. 3 Quinoline insolubles: 0-5%; β-fraction: 8-12%; Ash content: <0.2%; Sulfur content: <0.5%; Nitrogen content: <1.0%.

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