CN113636538A - Mesocarbon microbeads and preparation method thereof - Google Patents

Mesocarbon microbeads and preparation method thereof Download PDF

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Publication number
CN113636538A
CN113636538A CN202111101465.2A CN202111101465A CN113636538A CN 113636538 A CN113636538 A CN 113636538A CN 202111101465 A CN202111101465 A CN 202111101465A CN 113636538 A CN113636538 A CN 113636538A
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heating
mesocarbon microbeads
pitch
stage
biomass
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CN202111101465.2A
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林雄超
王彩红
张玉坤
李磊
王永刚
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China University of Mining and Technology Beijing CUMTB
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China University of Mining and Technology Beijing CUMTB
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    • CCHEMISTRY; METALLURGY
    • C01INORGANIC CHEMISTRY
    • C01BNON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00Carbon; Compounds thereof
    • C01B32/05Preparation or purification of carbon not covered by groups C01B32/15, C01B32/20, C01B32/25, C01B32/30

Abstract

Provides a mesocarbon microbead and a preparation method thereof. The method comprises the following steps: putting coal tar pitch and biomass pitch into a reaction kettle, purging with inert gas, heating to 90-110 ℃, and uniformly stirring; then continuously heating to 400-420 ℃, preserving the heat, and then cooling to the room temperature in the inert gas atmosphere; extracting with quinoline, washing the residual solid with toluene after extraction until colorless, and drying; and putting the dried solid into a furnace, and heating for carbonization to obtain the mesocarbon microbeads. The process method is reasonable and environment-friendly, and the obtained mesocarbon microbeads have uniform spherical morphology and larger interlayer spacing and defect points.

Description

Mesocarbon microbeads and preparation method thereof
Technical Field
The invention belongs to the field of processing of new coal-based materials, and particularly relates to a method for preparing mesocarbon microbeads by doping biomass pitch in coal tar pitch and the mesocarbon microbeads prepared by the method.
Background
Mesophase Carbon Microbeads (MCMB) are the intermediate temperature liquid phase pyrolysis products of polycyclic aromatic hydrocarbons. It can be prepared from coal or petroleum derived pitches, naphthalene isotropic pitches, heavy oils, and coal tar. MCMB has been extensively studied as a precursor for the preparation of carbon fibers, foams and other advanced functional materials. Recently, more research has been focused on the use of MCMBs as electrode materials, such as lithium ion secondary batteries and sodium ion batteries.
Because the coal tar pitch contains a large amount of polycyclic aromatic hydrocarbons, the coal tar pitch can be used as a precursor for preparing MCMB, and the intermediate phase carbon microspheres can be prepared by heating at 410-430 ℃ for 4-10 h for pyrolysis. In order to prevent the mesophase carbon microspheres from melting in the pyrolysis process, the carbonization time needs to be strictly controlled or shortened. Therefore, the yield of the carbon microspheres is generally low in the conventional MCMB preparation process, and the carbon microspheres only account for 5-20 wt% of the raw materials.
In view of the problem of low yield, it was found that the addition of some additives, such as carbon black, rosin and ferrocene, is beneficial to increase the yield of MCMB, and can prevent the rapid fusion of mesophase carbon microspheres. However, these additives have certain limitations due to cost or chemical properties, and biomass pitch is rich in alkyl and cycloalkyl functional groups. The large number of smaller molecular species generated during pyrolysis helps to reduce the softening point and viscosity of the mesophase pitch. The biomass asphalt provides an additional nucleation domain for forming the carbon microspheres, the biomass asphalt is taken as an additive, the yield of the carbon microspheres can be obviously improved, and the biomass asphalt has great advantages in the aspects of cost and environmental protection.
Thus, there is a need for a novel mesocarbon microbead and a method for preparing the same.
Disclosure of Invention
Therefore, the invention aims to provide a method for preparing mesocarbon microbeads by doping biomass pitch in coal tar pitch. The method is characterized in that biomass pitch is added as a nucleating agent of the mesocarbon microbeads, and the yield of the mesocarbon microbeads is improved through polycondensation reaction at a certain temperature. The method is simple to operate, environment-friendly and efficient; can effectively treat biomass asphalt as waste and produce high-valued mesocarbon microbeads by utilizing the characteristics of high activity, low price and the like of the biomass asphalt.
In order to achieve the above object, the present invention provides a method for preparing mesocarbon microbeads, which comprises:
(1) putting coal tar pitch and biomass pitch into a reaction kettle, purging with inert gas, heating to 90-110 ℃ (preferably 100 ℃), and uniformly stirring;
(2) then, the temperature is continuously increased to 400-420 ℃ (preferably 410 ℃), the temperature is kept for 6-9h (preferably 7h) for reaction, and then the reaction product is cooled to room temperature under the inert gas atmosphere;
(3) extracting the product obtained in the step (2) by using quinoline as a solvent, washing the residual solid by using toluene after extracting to be colorless, and then drying the washed solid in an oven;
(4) and (4) putting the solid obtained in the step (3) into a furnace, heating to 900-1100 ℃ in an inert gas atmosphere (preferably 1000 ℃), and keeping the temperature for 0.5-1.5h (preferably 1h) to carry out carbonization, thereby obtaining the mesocarbon microbeads.
Wherein in the step (1), the mass ratio of the biomass pitch to the total mass of the coal tar pitch and the biomass pitch is 10-20%.
Wherein, at normal temperature, the coal tar pitch is solid, and the biomass pitch is fluid.
Wherein, in the step (1), the reaction kettle is a stainless steel high-pressure reaction kettle.
Wherein, in the step (1), the stirring speed is 90-110r/min (preferably 100 r/min).
Wherein, in the step (1) or (2), the inert gas is one or more of nitrogen, argon and helium.
Wherein, in the step (2), a longer heat preservation reaction time is adopted to improve the yield of the mesocarbon microbeads.
Wherein, in the step (2), the temperature is raised at a temperature raising rate of 3-7 ℃/min (preferably 5 ℃/min).
In the step (3), the extracted solid is eluted by using a toluene solution, wherein the toluene solution can effectively reduce the drying temperature and shorten the drying time.
Wherein, in the step (3), extraction is performed by using a Soxhlet device.
Wherein, in the step (3), the drying temperature is 110-.
Wherein, in the step (4), the furnace is a tube furnace.
Wherein, in the step (4), the temperature rise is carried out in three stages: the first stage is as follows: heating from room temperature to 400 deg.C (preferably 350 deg.C) at a heating rate of 3-7 deg.C/min (preferably 5 deg.C/min); and a second stage: heating to 680-720 deg.C (preferably 700 deg.C) at a heating rate of 0.5-1.5 deg.C/min (preferably 1 deg.C/min); and a third stage: heating to 900-1100 deg.C (preferably 1000 deg.C) at a heating rate of 3-7 deg.C/min (preferably 5 deg.C/min).
In the step (4), the second-stage temperature rise is carried out at a slower temperature rise rate, so that the structure of the mesocarbon microbeads is further stabilized.
Wherein, in the step (4), the whole carbonization process is carried out under normal pressure.
The invention also provides the mesocarbon microbeads prepared by the preparation method.
Wherein the morphology of the mesocarbon microbeads is uniform and spherical, and the mesocarbon microbeads have larger interlayer spacing, particularly 0.3458nm-0.3516nm, and the average particle size of 10-19 μm (preferably 12 μm).
The invention has the following beneficial technical effects:
the biomass asphalt adopted by the invention is a renewable carbon product extracted from biomass tar by reduced pressure distillation. It has the characteristics of low cost, high hydrogen content, low ash content, low QI content and relatively high light component content. In addition, the abundance of oxygen-containing functional groups present in biomass pitch can increase its reactivity, resulting in pyrolysis, polymerization, and crosslinking reactions of the biomass pitch at lower reaction temperatures. During these reactions, the large planar aromatic molecules formed can act as nucleating agents for mesophase spheres. The addition of biomass pitch as a nucleating agent may provide more nucleation sites at lower temperatures than coal tar pitch. Since the addition of nucleating agents to semi-crystalline polymers can provide a surface for crystal growth, rapid crystal formation will result in many small crystal domains. This all contributes to an increase in the yield of carbon microspheres.
The process method provided by the invention is reasonable, the environment-friendly, low-cost, environment-friendly and pollution-free reactants are fully utilized, a certain amount of biomass pitch is added under appropriate reaction conditions, the yield of the mesophase carbon microspheres prepared from coal tar pitch is improved, the mechanical strength of the carbon microspheres is effectively improved by roasting the carbon microspheres at high temperature under relatively closed conditions, the mesophase carbon microspheres with uniform appearance and large interlayer spacing can be obtained, and the yield of the carbon microspheres is high, particularly 33-43%.
Brief description of the drawings
FIG. 1 is a Scanning Electron Microscope (SEM) photograph of mesophase carbon microspheres of example 2 prepared according to the present invention.
FIG. 2 is a polarization microscope photograph of mesophase carbon microspheres of example 2 prepared according to the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Example 1
a) Putting 45g of coal tar pitch and 5g of biomass pitch into a stainless steel high-pressure reaction kettle, heating to 100 ℃ after nitrogen purging, and uniformly stirring at a stirring speed of 100R/min; (ii) a
b) Heating the reactor from the ambient temperature to 410 ℃, keeping the heating rate at 5 ℃/min for 7h, and cooling to room temperature in the nitrogen atmosphere;
c) extracting the product by using quinoline as a solvent by using a Soxhlet device, washing the residual solid by using toluene after extracting until the product is colorless, and drying the washed solid in an oven at 120 ℃ for 2 hours;
d) carbonizing the extracted solid in a tubular furnace in nitrogen atmosphere, firstly heating the sample from room temperature to 350 ℃, and the heating speed is 5 ℃/min. Then heating from 350 ℃ to 700 ℃, reducing the temperature rise speed to 1 ℃/min, then raising the temperature from 700 ℃ to 1000 ℃ at the temperature rise speed of 5 ℃/min, maintaining for 1h after raising the temperature to 1000 ℃, and carrying out the whole carbonization process under normal pressure.
The obtained product is a black powdery solid, and is observed to be spheres with similar size and particle size distribution of about 18.24 mu m under a scanning electron microscope. The yield is 35.2 wt%, the added biomass asphalt has a positive effect on the nucleation of the mesocarbon microbeads, the naphthenic structure and the fatty side chain generated by the biomass asphalt in the pyrolysis process effectively reduce the viscosity of the reaction system, and the yield of the mesocarbon microbeads can be obviously improved.
Example 2
a) Putting 42.5g of coal tar pitch and 7.5g of biomass pitch into a stainless steel high-pressure reaction kettle, heating to 100 ℃ after nitrogen purging, and uniformly stirring at a stirring speed of 100R/min; (ii) a
b) Heating the reactor from the ambient temperature to 410 ℃, keeping the heating rate at 5 ℃/min for 7h, and cooling to room temperature in the nitrogen atmosphere;
c) extracting the product by using quinoline as a solvent by using a Soxhlet device, washing the residual solid by using toluene after extracting until the product is colorless, and drying the washed solid in an oven at 120 ℃ for 2 hours;
d) carbonizing the extracted solid in a tubular furnace in nitrogen atmosphere, firstly heating the sample from room temperature to 350 ℃, and the heating speed is 5 ℃/min. Then heating from 350 ℃ to 700 ℃, reducing the temperature rise speed to 1 ℃/min, then raising the temperature from 700 ℃ to 1000 ℃ at the temperature rise speed of 5 ℃/min, maintaining for 1h after raising the temperature to 1000 ℃, and carrying out the whole carbonization process under normal pressure.
The obtained product is a black powdery solid, and is observed to be spheres with similar size and particle size distribution of about 12.31 mu m under a scanning electron microscope. The yield is 42.8 wt%, the added biomass asphalt has a positive effect on the nucleation of the mesocarbon microbeads, the naphthenic structure and the fatty side chain generated by the biomass asphalt in the pyrolysis process effectively reduce the viscosity of the reaction system, and the yield of the mesocarbon microbeads can be obviously improved. The biomass pitch can provide nucleation domains for the formation of carbon microspheres, thereby hindering small sphere fusion and bulk mesophase formation, thereby producing more mesophase carbon microspheres during pyrolysis.
Example 3
a) Putting 40g of coal tar pitch and 10g of biomass pitch into a stainless steel high-pressure reaction kettle, heating to 100 ℃ after nitrogen purging, and uniformly stirring at a stirring speed of 100R/min; (ii) a
b) Heating the reactor from the ambient temperature to 410 ℃, keeping the heating rate at 5 ℃/min for 7h, and cooling to room temperature in the nitrogen atmosphere;
c) extracting the product by using quinoline as a solvent by using a Soxhlet device, washing the residual solid by using toluene after extracting until the product is colorless, and drying the washed solid in an oven at 120 ℃ for 2 hours;
d) carbonizing the extracted solid in a tubular furnace in nitrogen atmosphere, firstly heating the sample from room temperature to 350 ℃, and the heating speed is 5 ℃/min. Then heating from 350 ℃ to 700 ℃, reducing the temperature rise speed to 1 ℃/min, then raising the temperature from 700 ℃ to 1000 ℃ at the temperature rise speed of 5 ℃/min, maintaining for 1h after raising the temperature to 1000 ℃, and carrying out the whole carbonization process under normal pressure.
The obtained product is a black powdery solid, and is observed to be spheres with similar size and particle size distribution of about 10.14 mu m under a scanning electron microscope. The yield is 33.8 wt%, the added biomass asphalt has a positive effect on the nucleation of the mesocarbon microbeads, the naphthenic structure and the fatty side chain generated by the biomass asphalt in the pyrolysis process effectively reduce the viscosity of the reaction system, and the yield of the mesocarbon microbeads can be obviously improved. However, excessive amounts of biomass pitch may negatively impact the formation of mesophase carbon microbeads, such as by reducing the yield of mesophase carbon microbeads.
Comparative example 1
Same as example 1, except that no biomass pitch was added in step a), i.e. 50g of coal tar pitch was taken.
The obtained product is a black powdery solid, and is observed to be spheres with similar size and the particle size distribution of about 22.18 mu m under a scanning electron microscope. The yield was 28.4 wt%, the viscosity of the system was high in the initial stage of the polycondensation reaction, a large number of small particles were formed as a nucleating material for mesophase formation, and other small particles were also attached to the surface of the mesophase carbon microspheres. In the intermediate stage of the reaction, the viscosity of the system is further reduced, but as the amount of the macromolecular component increases, the growth of the mesophase carbon microspheres dominates in the system. Meanwhile, small particles are continuously generated in the system, so that the particle size of the mesocarbon microbeads is slightly larger than that of the mesocarbon microbeads generated by adding the biomass asphalt, and thus, the added biomass asphalt can effectively provide a nucleation domain for the mesocarbon microbeads, and further the yield of the mesocarbon microbeads is increased.
It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications therefrom are within the scope of the invention.

Claims (9)

1. A method of mesocarbon microbeads comprising:
(1) putting coal tar pitch and biomass pitch into a reaction kettle, purging with inert gas, heating to 90-110 ℃, and uniformly stirring;
(2) then, continuously heating to 400-420 ℃, preserving the heat for 6-9h to carry out reaction, and then cooling to room temperature under the inert gas atmosphere;
(3) extracting the product obtained in the step (2) by using quinoline as a solvent, washing the residual solid by using toluene after extracting to be colorless, and then drying the washed solid in an oven;
(4) putting the solid obtained in the step (3) into a furnace, heating to 900-1100 ℃ in an inert gas atmosphere, and preserving heat for 0.5-1.5h to carry out carbonization to obtain the mesocarbon microbeads;
wherein, in the step (4), the temperature rise is carried out in three stages: the first stage is as follows: heating the mixture to 400 ℃ from room temperature; and a second stage: heating to 680-720 ℃ at a heating rate of 0.5-1.5 ℃/min; and a third stage: heating to 900-1100 ℃.
2. The method for preparing mesocarbon microbeads according to claim 1, wherein in said step (1), the mass ratio of biomass pitch is 10-20% relative to the total mass of coal tar pitch and biomass pitch.
3. The method for preparing mesocarbon microbeads of claim 1, wherein the stirring speed in step (1) is 90-110 r/min.
4. The method for preparing mesocarbon microbeads according to claim 1, wherein said step (2) is carried out at a temperature increase rate of 3-7 ℃/min.
5. The method for preparing mesocarbon microbeads as set forth in claim 1, wherein in said step (3), the drying temperature is 110-130 ℃ and the drying time is 2.5-3.5 h.
6. The method for preparing mesocarbon microbeads according to claim 1, wherein said temperature increase in step (4) is carried out in three stages: the first stage is as follows: heating from room temperature to 300-400 ℃ at the heating rate of 3-7 ℃/min; and a second stage: heating to 680-720 ℃ at a heating rate of 0.5-1.5 ℃/min; and a third stage: heating to 900-1100 ℃ at a heating rate of 3-7 ℃/min.
7. The method for preparing mesocarbon microbeads of claim 1, wherein said step (4) is performed under normal pressure for the whole carbonization process.
8. Mesocarbon microbeads produced by the method for producing mesocarbon microbeads as claimed in claims 1 to 7.
9. The mesocarbon microbeads of claim 8, wherein said mesocarbon microbeads are spherical in shape and have an average size of 10-19 microns.
CN202111101465.2A 2021-09-18 2021-09-18 Mesocarbon microbeads and preparation method thereof Pending CN113636538A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114477132A (en) * 2022-01-25 2022-05-13 四川轻化工大学 Mesocarbon microbeads and preparation method thereof

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
LEI LI等: "Preparation of mesocarbon microbeads from coal tar pitch with blending of biomass tar pitch", 《JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS》 *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114477132A (en) * 2022-01-25 2022-05-13 四川轻化工大学 Mesocarbon microbeads and preparation method thereof

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