CN115650203A

CN115650203A - Deep oxidation modification process of coal pitch

Info

Publication number: CN115650203A
Application number: CN202211280579.2A
Authority: CN
Inventors: 常辉; 张建; 高振年
Original assignee: Wuhai Baohua Wanchen Coal Chemical Co ltd
Current assignee: Wuhai Baohua Wanchen Coal Chemical Co ltd
Priority date: 2022-10-19
Filing date: 2022-10-19
Publication date: 2023-01-31

Abstract

The invention discloses a deep oxidation modification process of coal pitch. The deep oxidation modification process of the coal pitch comprises the following steps: s1: adding raw material asphalt with a softening point of 29.7 ℃ into a reaction kettle, and heating at 100-170 ℃; s2: gas-liquid oxidation: injecting air into the asphalt softened in the reaction kettle, and oxidizing the asphalt to improve the softening point of the asphalt; s3: gas-solid oxidation: cooling the oxidized asphalt obtained in the step S2 into a solid, adding the solid into a roller furnace, blowing air into the roller furnace, and further oxidizing the oxidized asphalt in the roller furnace to obtain a precursor; s4: crushing and shaping: crushing the precursor obtained in the step S3 by using a jet mill; s5: carbonizing: the precursor in the form of crushed particles obtained in S4 is carbonized in a high-temperature environment in a nitrogen atmosphere. The deep oxidation modification process for the coal pitch provided by the invention adopts gas-liquid oxidation and gas-solid oxidation to carry out high molecular weight on the raw material pitch, and has the advantages of simple process, easy industrialization, low energy consumption and low production cost.

Description

Deep oxidation modification process of coal pitch

Technical Field

The invention relates to the technical field of asphalt modification, in particular to a deep oxidation modification process of coal asphalt.

Background

The lithium ion battery has very obvious advantages as a typical representative of a novel energy source, not only has the characteristics of high energy density, no memory effect, long cycle life and the like, but also has little pollution and meets the requirement of environmental protection, thereby being widely applied to the daily life of people, such as the fields of portable electronic products, electric automobiles, aerospace, energy storage and the like, and becoming a new focus of global economic development.

The future development direction of the lithium ion battery is high specific capacity, high charge-discharge efficiency, high cycle performance, high multiplying power, high safety and low cost. The main approach to high capacity is to use higher gram capacity positive and negative electrode materials. At present, a graphite material is mainly used as a negative electrode material, a manufacturing process is relatively mature, but the negative electrode material is limited by structural characteristics, the gram capacity of the graphite negative electrode material gradually tends to a limit value, and the rate capability can not meet the increasing performance requirements of downstream products on a battery core; the problems of volume expansion and poor cycle stability of the emerging silicon cathode are not effectively solved, the practical application of the silicon cathode is severely restricted, and the silicon cathode is difficult to be qualitatively improved in a short period. The search for carbon negative electrode materials with better performance is still an important subject of lithium ion battery research. The novel cathode material with rich resources, low price and good compatibility with electrolyte solvent becomes the starting point of the future industry.

The hard carbon negative electrode material is paid much attention due to a special lithium storage mechanism, excellent safety, rate characteristics and low-temperature performance, and particularly has unique advantages in the field of automotive power lithium ion batteries. The microporous structure of the hard carbon is beneficial to the movement of lithium ions, can quickly discharge and charge and is very beneficial to power type application. The lithium ion battery cathode material determines the safety, cycle life and energy density of the battery to a great extent, so the development of the novel hard carbon cathode material provides more combinations for the selection of a lithium ion battery material system.

Hard carbon refers to non-graphitizable carbon, is a carbon material obtained by high-temperature pyrolysis with a high molecular polymer as a precursor, is generally prepared by pyrolyzing resin at about 1000 ℃, and is also difficult to graphitizate at a high temperature of more than 2500 ℃. The reversible specific capacity of the hard carbon is higher than that of graphite, and is generally 500-700mAh/g. Common hard carbons are resin carbons (e.g., phenolic resin, polyfurfuryl alcohol, etc.), organic polymer pyrolytic carbons (e.g., PFA, PVC, PVDF, PAN, etc.), carbon black, and the like. Compared with graphite, the hard carbon has larger interlayer spacing and richer pore structures, has excellent low-temperature rate performance and excellent electrolyte compatibility, and becomes the most potential cathode material of a power battery.

High temperature carbonization of organic materials or high molecular polymers with higher carbon content is a common method for preparing hard carbon materials. The process often involves many complex chemical reactions, and the structure and performance of the obtained material are closely related to the composition and structure of the precursor, so that the structure and property of the obtained carbon material can be regulated and controlled to some extent by controlling the composition and structure of the precursor. In order to obtain a higher performance hard carbon negative electrode material, researchers are continuously searching for a higher quality carbon source. Hard carbon can be classified into high molecular polymer carbon, biomass carbon, and the like according to the difference in carbon source. The pitch-based precursor can be used as a precursor for preparing hard carbon materials due to high carbon residue rate, wide and easily available raw material sources and low price. However, coal pitch, if not pretreated, tends to form mesophase structures during carbonization. Therefore, in order to prepare hard carbon, a precursor asphalt needs to be pretreated, and usually, the asphalt is subjected to crosslinking treatment by using a crosslinking agent to change the microstructure of the asphalt, so that the growth of graphite microcrystals is hindered in the pyrolysis carbonization process, and a solid-phase carbonization process is performed, so that the hard carbon material can be obtained. Another method for preparing asphalt is a pre-oxidation method, i.e. the asphalt is pre-oxidized by using an oxidant to obtain pre-oxidized asphalt with a certain oxygen content. Due to the existence of oxygen heteroatoms, the asphalt is not easy to form an ordered structure in the pyrolysis carbonization process, so that the hard carbon material with a relatively disordered microstructure is obtained. The pre-oxidized asphalt can directly carry out a solid-phase carbonization process without a melting and liquefying stage in the pyrolysis and carbonization process, and a disordered microstructure is reserved to obtain the hard carbon material.

Therefore, it is necessary to provide a deep oxidation modification process for coal tar pitch to solve the above technical problems.

Disclosure of Invention

Aiming at the situation, in order to overcome the defects of the prior art, the invention provides a deep oxidation modification process of coal pitch, which can carry out high molecular weight modification on the raw material pitch.

In order to realize the purpose, the technical scheme adopted by the invention is as follows:

the deep oxidation modification process of the coal pitch comprises the following steps:

s1: adding raw material asphalt with a softening point of 29.7 ℃ into a reaction kettle, and heating at 100-170 ℃;

s2: gas-liquid oxidation: injecting air into the asphalt softened in the reaction kettle, and oxidizing the asphalt to improve the softening point of the asphalt;

s3: gas-solid oxidation: cooling the oxidized asphalt obtained in the step S2 into a solid, adding the solid into a roller furnace, blowing air into the roller furnace, and further oxidizing the oxidized asphalt in the roller furnace to obtain a precursor;

s4: crushing and shaping: crushing the precursor obtained in the step S3 by using an air flow mill to obtain a crushed granular precursor;

s5: carbonizing: and carbonizing the precursor in the particle shape obtained in the step S4 in a nitrogen gas and high-temperature environment to obtain the hard carbon material.

Preferably, the coke value of the cleaned raw material in the S1 is more than or equal to 90 percent, the ash content is less than or equal to 0.05 percent, the QI is more than or equal to 90 percent, the TI is more than or equal to 90 percent, and the magnetic foreign matter is less than or equal to 30ppm.

Preferably, the time for oxidizing the asphalt in the S2 process is 6-10h, the volume of the introduced air is 3-5 times of the volume of the raw material asphalt, the pressure in the reaction kettle is 0.1-3MPa, and the softening point of the oxidized asphalt is 162 ℃.

Preferably, the temperature rise rate in the reaction kettle is 5-15 ℃/min.

Preferably, the reaction time of the oxidized asphalt in the S3 in the roller furnace is 1-2h, and the reaction temperature is 700-900 ℃.

Preferably, the precursor obtained in S4 is pulverized and then subjected to shaping, demagnetization and sieving to obtain a precursor having uniform particles.

Preferably, the carbonization temperature of the precursor is 1000 ℃, and the carbonization time is 2h.

Compared with the prior art, the invention has the following beneficial effects:

(1) The invention adopts cheap asphalt as raw material, thus reducing the production cost of the hard carbon cathode material;

(2) The invention adopts gas-liquid oxidation and gas-solid oxidation to carry out high molecular weight polymerization on the raw material asphalt, and has simple process, easy industrialization, low energy consumption and low production cost.

Drawings

FIG. 1 is a flow chart of a deep oxidation modification process of coal pitch provided by the invention.

Detailed Description

The present invention will be further described with reference to the following description and examples, which include but are not limited to the following examples.

Example 1

A deep oxidation modification process of coal pitch comprises the following steps: s1: adding raw material asphalt with the softening point of 29.7 ℃, the coking value of more than or equal to 90 percent, the ash content of less than or equal to 0.05 percent, the QI of more than or equal to 90 percent, the TI of more than or equal to 90 percent and the magnetic foreign matter of less than or equal to 30ppm into a reaction kettle, heating at 100 ℃, and raising the temperature rate in the reaction kettle at 5 ℃/min;

s2: gas-liquid oxidation: injecting air into the softened asphalt in the reaction kettle, wherein the volume of the introduced air is 5 times of that of the raw material asphalt, the pressure in the reaction kettle is 0.1MPa, the asphalt is oxidized for 10 hours, and the softening point of the oxidized asphalt is 162 ℃;

s3: gas-solid oxidation: cooling the oxidized asphalt obtained in the step S2 into a solid, adding the solid into a roller furnace, blowing air into the roller furnace, and further oxidizing the oxidized asphalt in the roller furnace for 1h at the reaction temperature of 900 ℃ to obtain a precursor;

s5: carbonizing: and carbonizing the precursor in the particle shape obtained in the step S4 in nitrogen at the carbonization temperature of 1000 ℃ for 2h to obtain the pitch-based hard carbon material.

Example 2

A deep oxidation modification process of coal pitch comprises the following steps: s1: adding raw material asphalt with the softening point of 29.7 ℃, the coking value of more than or equal to 90 percent, the ash content of less than or equal to 0.05 percent, the QI of more than or equal to 90 percent, the TI of more than or equal to 90 percent and the magnetic foreign matter of less than or equal to 30ppm into a reaction kettle, heating at the temperature of 170 ℃, and increasing the temperature rate in the reaction kettle at 15 ℃/min;

s2: gas-liquid oxidation: injecting air into the softened asphalt in the reaction kettle, wherein the volume of the introduced air is 3 times of that of the raw material asphalt, the pressure in the reaction kettle is 3MPa, the asphalt is oxidized for 6 hours, and the softening point of the oxidized asphalt is 162 ℃;

s3: gas-solid oxidation: cooling the oxidized asphalt obtained in the step S2 into a solid, adding the solid into a roller furnace, blowing air into the roller furnace, reacting the oxidized asphalt in the roller furnace for 2 hours at the reaction temperature of 700 ℃, and further oxidizing to obtain a precursor;

Example 3

A deep oxidation modification process of coal tar pitch comprises the following steps: s1: adding raw material asphalt with the softening point of 29.7 ℃, the coking value of more than or equal to 90 percent, the ash content of less than or equal to 0.05 percent, the QI of more than or equal to 90 percent, the TI of more than or equal to 90 percent and the magnetic foreign matter of less than or equal to 30ppm into a reaction kettle, heating at the temperature of 140 ℃, and raising the temperature of the interior of the reaction kettle at the speed of 10 ℃/min;

s2: gas-liquid oxidation: injecting air into the softened asphalt in the reaction kettle, wherein the volume of the introduced air is 3 times of that of the raw material asphalt, the pressure in the reaction kettle is 1.5MPa, the asphalt is oxidized for 8 hours, and the softening point of the oxidized asphalt is 162 ℃;

s3: gas-solid oxidation: cooling the oxidized asphalt obtained in the step S2 into a solid, adding the solid into a roller furnace, blowing air into the roller furnace, reacting the oxidized asphalt in the roller furnace for 1.5 hours at the reaction temperature of 800 ℃ and further oxidizing to obtain a precursor;

s4: crushing and shaping: crushing the precursor obtained in the step S3 by using an air flow mill to obtain a precursor in a particle shape;

s5: carbonizing: and carbonizing the crushed granular precursor obtained in the step S4 in nitrogen at the carbonization temperature of 1000 ℃ for 2 hours to obtain the pitch-based hard carbon material.

The performance parameters of the pitch-based hard carbon obtained in the above example are as follows:

the process adopts cheap asphalt as a raw material, so that the production cost of the hard carbon cathode material is reduced; the gas-liquid oxidation and gas-solid oxidation are adopted to carry out the high molecular reaction on the raw material asphalt, the process is simple and easy to industrialize, the energy consumption is low, and the production cost is low.

The above-mentioned embodiment is only one of the preferred embodiments of the present invention, and should not be used to limit the scope of the present invention, but all the insubstantial modifications or changes made within the spirit and scope of the main design of the present invention, which still solve the technical problems consistent with the present invention, should be included in the scope of the present invention.

Claims

1. The deep oxidation modification process of the coal pitch is characterized by comprising the following steps of:

s5: carbonizing: and carbonizing the precursor in the form of crushed particles obtained in the step S4 in a nitrogen gas and high-temperature environment to obtain the hard carbon material.

2. The process of claim 1, wherein the coking value of the raw material cleaning in the S1 is not less than 90%, the ash content is not more than 0.05%, the QI content is not less than 90%, the TI content is not less than 90%, and the magnetic foreign matter content is not more than 30ppm.

3. The process of claim 1, wherein the time for oxidizing the asphalt in the S2 process is 6-10 hours, the volume of the introduced air is 3-5 times of the volume of the raw asphalt, the pressure in the reaction kettle is 0.1-3MPa, and the softening point of the oxidized asphalt is 162 ℃.

4. The process of claim 1, wherein the temperature rise rate in the reaction kettle is 5-15 ℃/min.

5. The process of claim 1, wherein the reaction time of the oxidized asphalt in the S3 in the roller furnace is 1-2h, and the reaction temperature is 700-900 ℃.

6. The process of claim 1, wherein the precursor obtained in step S4 is pulverized, and then subjected to shaping, demagnetizing and screening to obtain a precursor with uniform particles.

7. The deep oxidation modification process of coal pitch as claimed in claim 1, wherein the carbonization temperature of the precursor is 1000 ℃ and the carbonization time is 2h.