CN110697676A - A kind of hollow carbon microsphere and preparation method thereof - Google Patents

Abstract

The invention provides a hollow carbon microsphere and a preparation method thereof. The preparation method comprises the following steps: after extracting heavy oil with a supercritical or near-critical extraction solvent, an extracted oil phase is obtained; After the supercritical desolvation treatment, an extraction component is obtained; wherein, the extraction solvent is selected from light hydrocarbons or light hydrocarbon fractions of C3-C5; the reaction system comprising the extraction component and the organic solvent is The thermal polycondensation reaction is carried out in a supercritical state or a near-critical state; after the thermal polycondensation reaction is completed, the organic solvent is separated, a crude product is collected, and a separation solvent is added for purification to obtain a purified crude product; the purified crude product is dried treatment to obtain the hollow carbon microspheres. The preparation method uses heavy oil as a raw material, does not need to add any template or catalyst, and can prepare high-quality hollow carbon microspheres with smooth surfaces in one step.

Description

A kind of hollow carbon microsphere and preparation method thereof

technical field

The invention relates to a hollow carbon microsphere and a preparation method thereof, belonging to the fields of heavy oil high value-added processing and carbon materials.

Background technique

Hollow carbon microspheres are a promising spherical carbon material with low toxicity, large specific surface area, low density, thermodynamic and chemical stability, etc. It has good application prospects in the fields of optoelectronics, heat insulation, sound insulation and electrode materials.

As a carbonization product, although it can be used for the preparation of hollow carbon microspheres from a wide range of raw materials, most of them are pure substances, such as glucose, phenol, benzene, ethylene, formaldehyde or polymers as carbon sources. The preparation method is mainly based on the template method, that is, the carbon source is uniformly distributed on the surface of the template in a certain way, and then the template is removed by acid etching or calcination to obtain hollow carbon microspheres. The preparation of hollow carbon microspheres not only requires complicated operations, but the quality and specifications of the products are also limited by process control and template use. Even without considering the complexity of the preparation process, templates of different specifications need to be equipped and used according to product specifications and properties. It also leads to the complexity of production operations. Whether from the perspective of raw material cost or the complexity of preparation methods, the current research on hollow carbon microspheres is still at the laboratory level, with high cost, complicated steps, and accompanied by environmental pollution. , high risk and other issues, it is difficult to apply on a large scale.

The output of heavy oil in my country is huge, and the coal chemical industry produces a large amount of coal tar every year. The refinery produces a large amount of ethylene coal tar in the process of cracking hydrocarbon raw materials to produce ethylene. In the petrochemical field, in addition to atmospheric and vacuum residual oil, The annual output of catalytic cracking oil slurry (FCC oil slurry) can reach 7.5 million tons. How to realize the rational utilization of these heavy oils and explore ways to broaden the added value of heavy oil has always been a difficult problem in the industry.

The composition of heavy oil is complex, but it also has obvious application advantages. Ideal carbon source for high value-added carbon materials. However, limited by the reaction method, the application of heavy oil in the field of high value-added carbon materials is rarely reported. The main reason is that the reaction of heavy oil is complex and difficult to control. Although there are many related deep processing application reports, there are generally the defects of unstable downstream product standard or poor quality and low yield. Although a small number of manufacturers have realized the preparation of needle coke and mesophase products (pitch or carbon microspheres) using heavy oil as raw material, this should be the main way to use heavy oil to prepare carbonized products through thermal polycondensation and coking reactions. , but the characteristics of heavy oil and the results of previous separation treatment have a great impact on the quality of carbonized products such as needle coke. With the current industrial production process, each batch of needle coke products will have 30% or more substandard low-quality coke. , To produce high-quality carbonized products with high output, the control of production process and equipment investment are high. On the other hand, even if the production of high-quality carbonized products can be realized, its downstream application route and scope are still narrow compared to the heavy oil feedstock with huge output.

SUMMARY OF THE INVENTION

In view of the above defects, the present invention provides a hollow carbon microsphere and a preparation method thereof. The preparation method uses heavy oil as a raw material, without adding any template or catalyst, and can prepare the hollow carbon microsphere in one step, which is easy to realize large-scale application.

The invention also provides a hollow carbon microsphere, which is obtained from a carbonized product of heavy oil as a raw material, has rich raw material sources, simple preparation process, is beneficial to industrialization, and provides a high value-added application approach for heavy oil.

The invention provides a preparation method of hollow carbon microspheres, comprising the following steps;

After the heavy oil is extracted with a supercritical or near-critical extraction solvent, an extracted oil phase is obtained; the extracted oil phase is subjected to supercritical desolvation treatment to obtain an extraction component; wherein, the extraction solvent is selected from Light hydrocarbons or fractions of C3-C5;

subjecting the reaction system comprising the extraction component and the organic solvent to a thermal polycondensation reaction in the supercritical state or near-critical state of the organic solvent;

After the thermal polycondensation reaction is completed, the organic solvent is separated, the crude product is collected, and the separation solvent is added for purification to obtain a purified crude product;

The purified crude product is subjected to drying treatment to obtain the hollow carbon microspheres.

The applicant's research found that, in the process of thermal polycondensation of heavy oil, the introduction of an organic solvent in a supercritical or near-critical state will change the shape and structure of the polycondensation product obtained, and become hollow microspheres. Compared with the phase product, it forms a layered structure with substantially concentric circles in cross section, so it can be said to be a mesophase microsphere with a hollow structure. In the invention, heavy oil is used as the raw material of hollow carbon microspheres, and the heavy oil is subjected to thermal polycondensation reaction in the supercritical state or near-critical state of an organic solvent to finally generate hollow carbon microspheres.

The raw material heavy oil used in the present invention can also be called heavy oil, and is understood as partial "heavy" residual oil or tar residual oil, including heavy fuel oil, ethylene tar or coal tar produced by the petroleum processing chain, and is characterized by High molecular weight and high viscosity. According to the industry consensus, heavy petroleum oil refers to residual oil or oil slurry with a density higher than 0.934g/ ^cm3 . Generally speaking, residual oil, catalytic cracking oil slurry, thermally processed distillate oil, deasphalted oil, ethylene tar, etc. come from oil products. The residual oil of the processing chain can be called heavy oil. Coal tar residue is the heavier part of coal tar, such as the residue after distillation and extraction of coal tar. In a specific embodiment of the present invention, the heavy oil feedstock used includes petroleum residue oil (eg, catalytic cracking process tail oil, also known as FCC slurry, tar produced in ethylene processing), coal tar or coal tar residue oil.

Before the thermal polycondensation reaction, the heavy oil needs to be separated. First, the heavy oil is extracted with an extraction solvent in a near-critical or supercritical state to remove impurities in the heavy oil and also remove asphaltenes and some colloids that are harmful to the formation of hollow carbon microspheres. The extraction treatment not only realizes the purification of heavy oil, but also realizes the concentration of aromatic components in the extracted oil phase obtained. In addition, the supercritical solvent removal process for the extracted oil phase is combined, so as to obtain the raw material with improved quality and prepare high-quality hollow carbon microspheres by heat-supply polycondensation.

In the specific operation, the heavy oil is used as the raw material to make it contact with the extraction solvent in countercurrent in the extraction tower, and the temperature and pressure of the extraction tower are controlled to make the extraction solvent reach the supercritical state or near-critical state, thereby triggering the supercritical state of the heavy oil. Critical or near-critical extraction yields a raffinate phase and an extracted oil phase. Among them, the raffinate phase can recover the extraction solvent through separation operation, so as to realize the recycling use of the extraction solvent.

The extraction solvent of the present invention is a C3-C5 light hydrocarbon or a light hydrocarbon fraction, and the C3-C5 light hydrocarbon can be a C3-C5 hydrocarbon solvent, or a mixed solvent, or a C3-C5 light hydrocarbon fraction can be selected as the extraction solvent.

得到，式中x_i是轻烃或馏分中的组分 i的摩尔分数，Tc_i是该组分i的临界温度，n是该萃取溶剂所含的组分数。萃取溶剂在本发明中作为分离介质，选择合适的溶剂可以分离体系的温度、压力等参数，可得到相应的分离产物。If the extraction solvent is a mixed solvent or a fraction, the critical temperature Tc of the extraction solvent is between 90°C and 196°C, and the critical temperature Tc is based on the formula

Obtained, where x _i is the mole fraction of component i in the light hydrocarbon or fraction, Tci is the critical temperature of this component _i , and n is the number of components contained in the extraction solvent. The extraction solvent is used as a separation medium in the present invention, and a suitable solvent can be selected to separate parameters such as temperature and pressure of the system, and a corresponding separation product can be obtained.

According to the solution of the present invention, the heavy oil is extracted under the near-critical or supercritical conditions of the extraction solvent, and the extraction components are obtained by separating or recovering the extraction solvent, and the main impurity ash and catalyst particles in the heavy oil are removed. In addition to the raffinate phase, almost all of the C7 asphaltenes (n-heptane insolubles) and part of the heavy gums are also separated into the raffinate phase, and the aromatic components in the heavy oil are concentrated by removing the bad components. Using the extraction component as a preparation raw material is beneficial to obtain hollow carbon microspheres with more excellent shape and properties, and the surface of the obtained hollow carbon microspheres is also more smooth and uniform.

The extraction and separation of heavy oil can be completed by selecting a conventional extraction column, such as a sieve tray column or a packed column. The operation process can be, after mixing the heavy oil with the extraction solvent, feed from the middle of the extraction column and keep the inlet temperature at 50 °C. -280°C, the pressure of the extraction column is 3.0-10.0MPa, the extraction oil phase is separated from the top of the column, and the raffinate phase is separated from the bottom of the column. As the separation medium, the extraction solvent is recommended to be mixed with the heavy oil raw material at a high ratio, preferably 1.5:1 or higher. The existing quality of the extraction solvent and the heavy oil raw material can be controlled in practice. The ratio is (1.5-6):1.

After collecting the extracted oil phase, supercritical solvent removal (extraction solvent) treatment is also required. The corresponding supercritical conditions are controlled according to the properties of the extraction solvent used, and the extraction solvent can be recovered in a single fluid phase by determining an appropriate separation pressure to achieve separation from the extraction components. Under the supercritical state and the set separation pressure, theoretically, the higher the separation temperature, the lower the density of the solvent and the faster the fluid velocity. In order to reduce the carryover of the solvent to the light oil phase, the operating cost and control requirements are also corresponding. higher. In a specific embodiment of the present invention, when the solvent is extracted by supercritical separation, the density of the solvent is lower than 0.20g/cm ³ , the separation pressure is 3.0-10.0MPa, and the separation temperature is controlled not to be higher than 280°C.

After the extraction components are collected, the extraction components are mixed with the organic solvent to form a polycondensation reaction system. The present invention does not limit the order of addition of the extraction components and the organic solvent. The extraction components can be added to the reactor first, and then the organic solvent is added to the reactor; the organic solvent can also be added to the reactor first, and then the extraction components are added to the reactor; the organic solvent can also be added to the reactor at the same time. Solvents and Extractive Components.

When the extraction components and the organic solvent are added to the reactor, the two are mixed evenly by stirring, and the reaction environment of the reaction system, such as pressure, temperature, etc., is adjusted, and the thermal polycondensation reaction is completed in the supercritical state or near-critical state of the organic solvent.

When the thermal polycondensation reaction is over, the reaction system is filtered at normal temperature and pressure to separate the organic solvent, and the crude reaction product is collected. The structure and morphology can be detected as hollow microsphere particles.

In order to improve the purity of the hollow carbon microspheres, it is also necessary to use a separation solvent to purify the crude reaction product, so that the impurities in the crude reaction product can be dissolved in the separation solvent, thereby helping to improve the purity of the hollow carbon microspheres.

Finally, the purified crude product is dried to remove the remaining solvent and possible moisture to obtain the hollow carbon microspheres of the present invention.

Specifically, in the operation, the separation solvent can be removed by filtration, the purified crude product can be collected, and then the purified crude product can be dried to obtain hollow carbon microspheres.

For the drying treatment of the purified crude product, atmospheric pressure drying or reduced pressure drying can be adopted. Considering the maintenance of the hollow carbon microsphere structure, it is advantageous to choose atmospheric pressure drying, or appropriate pressure reduction can be used to reduce the drying temperature and improve the drying efficiency.

Compared with the prior art for preparing hollow carbon microspheres, the present invention selects the processed heavy oil component as the raw material, and introduces supercritical or near-critical organic solvent in the thermal polycondensation reaction, which not only does not require any template in the entire preparation process. In addition, the preparation method is simple and the preparation cost is low, so it is easy to realize large-scale application. In addition, the preparation method of the present invention also opens up a new field for the application of the heavy oil raw material, and further realizes the efficient utilization of the heavy oil raw material.

According to the method of the present invention, the heavy oil is subjected to supercritical extraction or near-critical extraction to obtain an extracted oil phase, and then the extracted oil phase is subjected to supercritical separation to extract the solvent to obtain an extraction component, and the extraction component is selected as a raw material, and the supercritical The hollow carbon microspheres are obtained by thermal polycondensation process in the presence of organic solvent in the state or near critical state. Since the heavy oil used as the raw material for polycondensation is purified by extraction and separation, the prepared hollow carbon microspheres show high-quality characteristics such as smooth surface, uniform particle size distribution, and uniform wall thickness. Meanwhile, compared with the prior art for preparing hollow carbon microspheres, the present invention not only does not need any template agent and additives in the whole preparation process, but also has a simple preparation method and low preparation cost, so it is easy to realize large-scale application. In addition, the preparation method of the present invention also opens up a new field for the application of the heavy oil raw material, and further realizes the efficient utilization of the heavy oil raw material.

The terms "supercritical state" or "near critical state" used in the present invention belong to the common knowledge, that is, the state that reaches or exceeds the critical point of the organic solvent, or is close to the critical point of the organic solvent. In a specific embodiment, when the organic solvent is in a supercritical state, it means that the real-time temperature of the reaction system is controlled at 1.0-1.2 times the critical temperature of the organic solvent and the real-time pressure is 1-5 times its critical pressure; when the organic solvent is in a supercritical state The near-critical state means that the real-time temperature of the reaction system is controlled at 0.95-1.0 times the critical temperature of the organic solvent (absolute temperature K, the same below) and the real-time pressure is 1-5 times its critical pressure. According to the critical point (critical temperature and critical pressure) of the selected organic solvent, the temperature and pressure of the system can be adjusted according to known technical means, so that the organic solvent is in a supercritical or near-critical state.

In a further scheme, the extracted oil phase obtained by the heavy oil pretreatment can also be separated to prepare the raw material for the preparation of intermediate carbon microspheres, which will have wider adaptability.

Specifically, the present invention also includes further processing of the extracted oil phase, comprising the steps of:

The extraction oil phase is heated and separated to obtain the extracted light oil phase and the extracted heavy oil phase respectively;

After carrying out supercritical desolvation treatment on the extracted light oil phase and the extracted heavy oil phase, respectively, the extracted light components and the extracted heavy components are obtained;

During the thermal polycondensation reaction, the extraction component is selected from the extracted light component, the extracted heavy component or the mixture of the extracted light component and the extracted heavy component.

Through the heating treatment, the composition of various aromatic hydrocarbon contents in the extracted oil phase is further separated, and the composition of the thermal polycondensation raw material can be controlled to meet the preparation requirements of mesophase microspheres of different specifications. In the specific operation, the extraction oil phase is heated to a temperature of 5-90°C higher than the top temperature of the extraction column and enters the separation column, and the separation pressure is controlled to be 3.0-10.0MPa. The separation column can be selected from an empty column, a sieve tray column or a packed column, etc., The extracted heavy oil phase is discharged from the bottom of the tower, and the extracted heavy components are obtained after supercritical desolvation treatment; the extracted light oil phase is separated from the top of the tower, and the extracted light components are obtained after supercritical desolvation treatment. It can be understood that the mass ratio of the extracted light oil phase and the extracted heavy oil phase collected at different temperatures will be different. In addition, the same effect can be obtained by changing the pressure except that the extracted oil phase is divided into the extracted light oil phase and the extracted heavy oil phase by heating.

In a specific embodiment, the preparation method of the hollow carbon microspheres of the present invention comprises:

The reaction system comprising the extracted light components and the organic solvent is subjected to a thermal polycondensation reaction in a supercritical state or a near-critical state of the organic solvent;

After the thermal polycondensation reaction is completed, the organic solvent is separated, the crude product is collected, and the separation solvent is added for purification to obtain a purified crude product;

The purified crude product is subjected to drying treatment to obtain the hollow carbon microspheres.

In another specific embodiment, the preparation method of the hollow carbon microspheres of the present invention comprises:

making the reaction system comprising the extracted heavy component and the organic solvent carry out a thermal polycondensation reaction in a supercritical state or a near-critical state of the organic solvent;

After the thermal polycondensation reaction is completed, the organic solvent is separated, the crude product is collected, and the separation solvent is added for purification to obtain a purified crude product;

The purified crude product is subjected to drying treatment to obtain the hollow carbon microspheres.

In another specific embodiment, the preparation method of the hollow carbon microspheres of the present invention comprises:

performing the thermal polycondensation reaction in a reaction system comprising the extracted heavy components, the extracted light components and the organic solvent in a supercritical state or a near-critical state of the organic solvent;

After the thermal polycondensation reaction is completed, the organic solvent is separated, the crude product is collected, and the separation solvent is added for purification to obtain a purified crude product;

The purified crude product is subjected to drying treatment to obtain the hollow carbon microspheres.

In the above three specific embodiments, except when the raw materials are extracted light components, extracted heavy components, and a mixture of the two, the remaining processes can be the same. It can be understood that the quality of the extracted light components and the extracted heavy components obtained as raw materials for the thermal polycondensation reaction is further optimized after the heating and separation treatment, and when the reaction raw materials are the mixture of the extracted light components and the extracted heavy components, the It is also beneficial to make the quality of the prepared hollow carbon microspheres better than that of the hollow carbon microspheres prepared by extracting the oil phase as the raw material. Therefore, before the thermal polycondensation reaction, the extracted oil phase from the heavy oil separation is further separated into light/heavy components, which can be selectively used as the raw material for the thermal polycondensation reaction, which not only improves the quality of the raw materials, but also adjusts and optimizes the composition of the raw materials for the reaction. , to obtain the desired microsphere product (eg regulation of particle size or properties).

In an embodiment of the thermal polycondensation reaction, the temperature of the reaction system is controlled at a rate of 0.5-10° C./min until the organic solvent reaches a supercritical state or a near-critical state.

Specifically, the reaction system is directly heated and the heating rate is controlled to be 0.5-10°C/min, so that the temperature of the reaction system is gradually raised to the supercritical temperature or near-critical temperature of the organic solvent, so that the organic solvent reaches the supercritical state or near-critical temperature. state.

In another specific embodiment of thermal polycondensation, after adjusting the pressure of the reaction system to increase to the supercritical pressure of the organic solvent, the reaction system is controlled to increase in temperature at a rate of 0.5-10°C/min until The organic solvent reaches a supercritical or near-critical state.

Specifically, firstly adjust the pressure of the reaction system to the critical pressure of the organic solvent, and then heat the reaction system to increase the temperature at a rate of 0.5-10°C/min until the temperature of the reaction system reaches the supercritical temperature or near-critical temperature, so that the organic solvent reach a supercritical or near-critical state.

According to the solution of the present invention, the thermal polycondensation process of the heavy oil extraction product (extracted component, extracted light component, extracted heavy component and one of the mixture of extracted light component and extracted heavy component) is carried out in a supercritical or near-critical solvent It is the key to ensure that the microspheres have a hollow structure. Adjusting and controlling the reaction On this basis, changing the process conditions, for example, the hollow carbon microsphere products with relative changes in wall thickness and particle size can be obtained. The applicant's research has found that when the reaction temperature and reaction pressure of the reaction system are adjusted, the particle size and wall thickness of the hollow carbon microspheres will change. In addition, in the process of adjusting the reaction system to the supercritical state or near-critical state of the organic solvent, by controlling the heating rate of the reaction system, the generated hollow carbon microspheres can also be controlled. For example, when the heating rate is low, hollow carbon microspheres with larger particle size and wall thickness can be obtained. On the contrary, when the heating rate is increased, hollow carbon microspheres with smaller particle size and Hollow carbon microspheres. Of course, the thermal polycondensation process will be different depending on the heavy oil feedstock, which may also affect the structure and size of the hollow carbon microspheres.

Further, in the present invention, in order to facilitate the thermal polycondensation reaction and the formation of hollow carbon microspheres, in the thermal polycondensation reaction, the mass ratio of the agent to oil is not less than 0.5:1. That is, the mass ratio of organic solvent to heavy oil extraction product (extraction component, extracted light component, extracted heavy component and one of the mixture of extracted light component and extracted heavy component) is not less than 0.5:1.

When the agent-oil mass ratio was further adjusted, the inventor found that with the increase of organic solvent, the particle size and wall thickness of the generated hollow carbon microspheres gradually increased. Considering comprehensively, the agent-oil mass ratio can be controlled to be 0.5-10 :1.

According to an embodiment of the present invention, in order to obtain hollow carbon microspheres that meet the requirements, the reaction time of the thermal polycondensation reaction is generally controlled to be 0.5-10 hours. That is to say, the reaction system comprising the heavy oil extraction product (extraction component, extracted light component, extracted heavy component, and one of the mixture of extracted light component and extracted heavy component) and the organic solvent reaches the supercritical state in the organic solvent. Or near critical state, continue to maintain this state for 0.5-10 hours. The wall thickness of hollow carbon microspheres increases with the prolongation of reaction time.

The thermal polycondensation product of the heavy oil extraction product (extracted component, extracted light component, extracted heavy component and one of the mixture of extracted light component and extracted heavy component) is removed from the organic solvent to obtain a crude product (with a hollow structure). The mesophase microspheres), it is also necessary to add a separation solvent for purification to remove impurities, etc. In an embodiment of the present invention, the step of collecting the crude product and adding the separation solvent for purification includes using the separation solvent for reflux purification, the reflux time is 2-48 hours, and the reflux temperature is 50-280°C.

A specific solution is that after the separation solvent is mixed with the crude product, the whole system can be heated until the separation solvent is refluxed. In the process of heating and refluxing, the impurities in the crude product will be dissolved in the separation solvent, thereby improving the purity of the hollow carbon microspheres.

The selection of the separation solvent is based on the ability to remove impurities on the surface of the crude product and easy separation. Generally, it is a solvent with a small molecular weight, and an organic solvent with a boiling point of 50-280 °C can be selected, which will not cause the hollow mesophase microspheres to react again. Solvents with altered structure and properties, such as one selected from the group consisting of toluene, ortho-xylene, meta-xylene, para-xylene, mixed xylenes, quinoline, tetralin, pyridine, ethanol, aviation kerosene, tetrahydrofuran and diesel or more. When the separation solvent is a mixture of multiple solvents, the present invention does not limit the ratio between the individual solvents.

The heavy oil raw material used in the present invention includes heavy fuel oil and various tar products, such as catalytic cracking oil slurry, coal tar and the like.

According to the embodiments of the present invention, different types of heavy oil feedstocks and different selection of organic solvents may also cause differences in the wall thickness and particle size of the obtained hollow carbon microspheres. For example, in different embodiments, the preparation process and parameters are similar, the selected heavy oil is coal tar, and the particle size range of the prepared hollow carbon microspheres is about 6-11 μm; the selected heavy oil is catalytic cracking oil slurry, The prepared hollow carbon microspheres have a particle size range of about 5-9 μm. It can be understood that with the change of other reaction conditions, even if the heavy oil is coal tar or catalytic cracking oil slurry, the particle size range of the prepared hollow carbon microspheres will also change.

The introduction of supercritical or near-critical organic solvents is a key factor for obtaining hollow microspheres. It is required to select organic solvents that will not participate in the reaction, are easy to separate and remove, and are conducive to controlling their supercritical or near-critical states. Can be selected from n-heptane, n-hexane, cyclohexane, n-pentane, cyclopentane, benzene, toluene, o-xylene, m-xylene, p-xylene, tetrahydronaphthalene, anthracene, tetrahydrofuran, pyridine and quinoline One or more of the phenoline, no matter it is a single solvent or a mixed solvent, as long as it can be confirmed that the expected thermal polycondensation reaction can be completed in the provided supercritical or near-critical state.

得到，式中x_i是有机溶剂中的组分i的摩尔分数，Tc_i是该组分i的临界温度，n是该有机溶剂所含的组分数。 _n When the organic solvent in the present invention is a mixture of multiple solvents, the critical temperature can generally be calculated according to the formula

Obtained, where x _i is the mole fraction of component i in the organic solvent, Tci is the critical temperature of this component _i , and n is the number of components contained in the organic solvent.

In the embodiment of the present invention, the organic solvent used in the thermal polycondensation reaction and the separation solvent used in the purification of the crude product may be the same or different, and can be determined according to the conditions of the raw materials and the convenience of operation.

The method for preparing hollow carbon microspheres proposed by the present invention is not only simple, but also requires no template. As long as the reaction conditions are properly adjusted, the particle size and wall thickness of the hollow carbon microspheres can be controlled. At the same time, due to the supercritical extraction of the heavy oil before the thermal polycondensation reaction, the raw material of the hollow carbon microspheres has a more concentrated distribution of the number of aromatic hydrocarbons, so that a smooth surface, a higher spheroidization rate, and a particle size can be prepared. High-quality hollow carbon microspheres with uniform diameter distribution and wall thickness.

In addition, the preparation method of the present invention does not impose too many restrictions on the reaction vessel, as long as the pressure and temperature can be adjusted. Generally, a common autoclave reactor can be used.

The present invention also provides a hollow carbon microsphere obtained by any one of the above-mentioned preparation methods.

As mentioned above, different from the hollow microspheres in the prior art, the hollow carbon microspheres prepared by the present invention are carbonized products from the thermal polycondensation process of heavy oil raw materials, which are produced in a supercritical or near-critical solvent along with the thermal polycondensation reaction. As the process grows, it should be a hollow microsphere particle with a mesophase morphology. Observe the cross section of the particle and find that it also has a layered structure.

The hollow carbon microspheres of the present invention are obtained without template, and the particle size and wall thickness are both micron level, the size distribution of the product can be achieved, the particle size is 3-50 μm, and the wall thickness is 0.5-2.5 μm.

Like the hollow carbon microspheres prepared in the prior art, the hollow carbon microspheres obtained by the present invention can also be widely used in the fields of secondary batteries, energy storage, high-strength carbon materials, catalysts and high-efficiency chromatography.

The implementation of the present invention has at least the following advantages:

1. The preparation method of the hollow carbon microspheres of the present invention is simple and easy to operate, the preparation of the hollow carbon microspheres can be completed in one step, the process parameters are easy to control, the products can be quickly separated, and the assistance of large-scale equipment and instruments is not required;

2. The method for preparing the hollow carbon microspheres of the present invention carries out supercritical extraction and supercritical desolvation treatment on heavy oil, so the quality control of the hollow carbon microspheres can be realized, and high spheroidization rate, particle size and wall thickness can be obtained. High-quality hollow carbon microspheres with uniform distribution, regular microsphere shape and smooth surface;

3. The preparation method of the hollow carbon microspheres of the present invention uses heavy oil as the raw material, which not only improves the added value of the heavy oil raw material, but also does not require any templates and additives, effectively reduces the production cost of the hollow carbon microspheres, and simplifies the The production process of hollow carbon microspheres;

4. The preparation method of the hollow carbon microspheres of the present invention further broadens the application route of heavy oil including petroleum processing tail oil and coal tar tail oil, and opens up a new field for the application of a large number of heavy oil resources in the industry;

5. The preparation method of the hollow carbon microspheres of the present invention does not require a template agent, and the particle size and wall thickness of the hollow carbon microspheres can be controlled by adjusting the raw materials and preparation parameters, which reduces the difficulty of production and is beneficial to industrialization. It also provides a guarantee for the application of hollow carbon microsphere products in various fields.

Description of drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description These are some embodiments of the present invention, and for those of ordinary skill in the art, other drawings can also be obtained from these drawings without any creative effort.

Fig. 1 is a SEM image of obtaining hollow carbon microspheres in embodiment 1;

Fig. 2 is another SEM image of obtaining hollow carbon microspheres in embodiment 1;

Fig. 3 is a SEM image of obtaining hollow carbon microspheres in embodiment 2;

4 is another SEM image of obtaining hollow carbon microspheres in Example 2;

Fig. 5 is a SEM image of obtaining hollow carbon microspheres in embodiment 3;

Fig. 6 is another SEM image of obtaining hollow carbon microspheres in embodiment 3;

Fig. 7 is the SEM image of obtaining hollow carbon microspheres in embodiment 4;

FIG. 8 is a FIB-SEM image of the hollow carbon microspheres obtained in Example 4. FIG.

Detailed ways

In order to make the purposes, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments These are some embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

Example 1

The preparation method of the hollow carbon microspheres of the present embodiment is as follows:

1) Taking mixed light hydrocarbons as the extraction solvent, the composition is isobutane and n-butane, and the mass ratio is 1:1. According to the calculation, its critical temperature is 143.45°C. Feed and feed temperature is 90 ℃, the mass ratio of agent oil is 4:1, mixed solvent and catalytic cracking oil slurry are carried out supercritical extraction in the extraction tower, and the formed extraction oil phase is sent out from the top of the extraction tower and enters the separation tower, The raffinate phase is discharged from the bottom of the extraction column as recovery;

2) after the extraction oil phase is carried out supercritical desolvation treatment, the extraction component is obtained;

3) adding the extraction component into the kettle type reactor, then adding toluene to the kettle type reactor, and locking the kettle type reactor after stirring;

Use nitrogen to purge the kettle type reactor, then increase the pressure to 4.5MPa, and use a heating furnace for heating at a heating rate of about 1.5°C/min. After the temperature rises to 390°C, the temperature and pressure are maintained for about 3 hours;

Wherein, the mass ratio of the toluene and the extraction component to the agent oil is about 2:1;

4) after the temperature and pressure of the kettle reactor are reduced to room temperature and normal pressure, the mixed solution in the kettle reactor is taken out and filtered, and the filter cake is collected as the crude product;

5) put the crude product in step 4) into a flask equipped with a condenser tube and a stirrer, then add aviation kerosene to the flask, heat the flask until the solvent is refluxed, and stop heating after about 4h;

The mixed solution in the flask is filtered, and the filter cake is collected to obtain a purified crude product;

6) drying the purified crude product in step 5) at atmospheric pressure to obtain the hollow carbon microspheres of the present embodiment;

Among them, the drying temperature is 140 ℃, and the drying time is about 12h.

FIG. 1 is a SEM image of the hollow carbon microspheres obtained in Example 1, which are clearly shown as micron-sized spheres.

FIG. 2 is another SEM image of the hollow carbon microspheres obtained in Example 1, which clearly shows that the microsphere products are hollow microspheres with a certain wall thickness.

It can be determined from Figures 1 and 2 that the particle size of the hollow carbon microspheres prepared in this example is 5-13 μm, the wall thickness is 0.5-1 μm, the particle size distribution of the microspheres is also relatively uniform, and there are fewer irregular shaped products. , thanks to the optimization of raw material properties.

Example 2

The preparation method of the hollow carbon microspheres of the present embodiment is as follows:

1) Take n-pentane as extraction solvent, its critical temperature is 196.6 ℃, after coal tar and extraction solvent are mixed, feed from the middle part of extraction tower and feed temperature is 150 ℃, agent oil mass ratio is 3:1, n-pentane Carry out supercritical extraction and separation with coal tar in the extraction tower, the formed extraction oil phase is sent out from the extraction tower top and enters the separation tower, and the raffinate phase is discharged from the extraction tower bottom as recovery;

2) the one-stage separation temperature (the first separation column) of the separation tower is 150 ℃, and the second-stage separation (the second separation column) is 170 ℃ of temperature, and the separation pressure is 5MPa, respectively obtaining the extraction light oil phase and the extraction heavy oil phase;

The extracted light oil phase and the extracted heavy oil phase are respectively subjected to supercritical desolvation treatment to obtain the extracted light component and the extracted heavy component;

3) adding the extraction heavy component into the kettle type reactor, then adding toluene to the kettle type reactor, and locking the kettle type reactor after stirring;

The kettle-type reactor was purged with nitrogen, and then the pressure was increased to 5MPa, and the heating furnace was used for heating at a heating rate of about 1.5°C/min. After the temperature rose to 390°C, the temperature and pressure were maintained for about 5 hours;

Wherein, the mass ratio of toluene and the extraction heavy component of the agent oil is about 3:1;

4) after the temperature and pressure of the kettle reactor are reduced to room temperature and normal pressure, the mixed solution in the kettle reactor is taken out and filtered, and the filter cake is collected as the crude product;

5) Put the crude product in step 4) into a flask equipped with a condenser tube and a stirrer, then add toluene to the flask, heat the flask until the solvent is refluxed, and stop heating after about 4h;

The mixed solution in the flask is filtered, and the filter cake is collected to obtain a purified crude product;

6) drying the purified crude product in step 5) at atmospheric pressure to obtain the hollow carbon microspheres of the present embodiment;

Among them, the drying temperature is 140 ℃, and the drying time is about 12h.

FIG. 3 is a SEM image of the hollow carbon microspheres obtained in Example 2, which are clearly shown as micron-sized spheres.

FIG. 4 is another SEM image of the hollow carbon microspheres obtained in Example 2, which clearly shows that the microsphere products are hollow microspheres with a certain wall thickness.

It can be determined from Fig. 3 and Fig. 4 that the particle size of the hollow carbon microspheres prepared in this example is 6-12 μm, the wall thickness is 0.5-1 μm, and the particle size distribution of the microspheres is more uniform than that of Example 1, and the shape is irregular There is very little product (high spheroidization rate), benefiting from further optimization of raw material properties.

Example 3

The preparation method of the hollow carbon microspheres of the present embodiment is as follows:

1) Take n-pentane as extraction solvent, its critical temperature is 196.6 ℃, after coal tar and extraction solvent are mixed, feed from the middle part of extraction tower and feed temperature is 150 ℃, agent oil mass ratio is 4:1, n-pentane Carry out supercritical extraction with coal tar in the extraction tower, the formed extraction oil phase is sent out from the top of the extraction tower and enters the separation tower, and the raffinate phase is discharged from the bottom of the extraction tower as recovery;

2) the one-stage separation temperature (the first separation column) of the separation tower is 150 ℃, and the second-stage separation (the second separation column) is 170 ℃ of temperature, and the separation pressure is 5MPa, respectively obtaining the extraction light oil phase and the extraction heavy oil phase;

The extracted light oil phase and the extracted heavy oil phase are respectively subjected to supercritical desolvation treatment to obtain the extracted light component and the extracted heavy component;

3) Add the extracted light components into the kettle type reactor, then add 5°C mixed xylene (petroleum mixed xylene (GB/T 3407-2010)) to the kettle type reactor, and lock the kettle type after stirring evenly. reactor;

The kettle-type reactor was purged with nitrogen, and then the pressure was increased to 4.5MPa, and heated in a heating furnace at a heating rate of about 1.5°C/min. After the temperature rose to 400°C, the temperature and pressure were maintained for about 7 hours;

Wherein, the mass ratio of mixed xylene to the agent oil for extracting light components is about 2:1;

4) after the temperature and pressure of the kettle reactor are reduced to room temperature and normal pressure, the mixed solution in the kettle reactor is taken out and filtered, and the filter cake is collected as the crude product;

5) Put the crude product in step 4) into a flask equipped with a condenser tube and a stirrer, then add toluene to the flask, heat the flask until the solvent refluxes, and stop heating after about 4h;

The mixed solution in the flask is filtered, and the filter cake is collected to obtain a purified crude product;

6) drying the purified crude product in step 5) at atmospheric pressure to obtain the hollow carbon microspheres of the present embodiment;

Among them, the drying temperature is 140 ℃, and the drying time is about 12h.

FIG. 5 is a SEM image of the hollow carbon microspheres obtained in Example 3, which are clearly shown as micron-sized spheres.

FIG. 6 is another SEM image of the hollow carbon microspheres obtained in Example 3, which clearly shows that the microsphere products are hollow microspheres with a certain wall thickness.

It can be determined from Fig. 5 and Fig. 6 that the particle size of the hollow carbon microspheres prepared in this example is 4-7 μm, the wall thickness is 0.5-1 μm, and the particle size distribution of the microspheres is more uniform than that of Example 1, and the shape is irregular Very little product was present, benefiting from further optimization of the raw material properties.

Example 4

The preparation method of the hollow carbon microspheres of the present embodiment is as follows:

1) Taking isobutane as the extraction solvent, its critical temperature is 135°C, after the catalytic cracking oil slurry is mixed with the extraction solvent, it is fed from the middle of the extraction tower and the feed temperature is 90°C, the mass ratio of the agent to oil is 3.5:1, and the isobutane is mixed with the extraction solvent. The butane and the catalytically cracked oil slurry are subjected to supercritical extraction in the extraction tower, the formed extracted oil phase is sent out from the top of the extraction tower and enters the separation tower, and the raffinate phase is discharged from the bottom of the extraction tower as recovery;

2) the one-stage separation temperature (the first separation column) of the separation tower is 90°C, and the second-stage separation (the second separation column) is 150°C of temperature, and the separation pressure is 5MPa, respectively obtaining the extraction light oil phase and the extraction heavy oil phase;

The extracted light oil phase and the extracted heavy oil phase are respectively subjected to supercritical desolvation treatment to obtain the extracted light component and the extracted heavy component;

3) adding the extraction heavy component to the tank reactor, then adding mixed xylene to the tank reactor, and locking the tank reactor after stirring;

The kettle-type reactor was purged with nitrogen, and then the pressure was increased to 5MPa, and heated in a heating furnace at a heating rate of about 1.5°C/min. After the temperature rose to 410°C, the temperature and pressure were maintained for about 5 hours;

Wherein, the mass ratio of the mixed xylene and the extracted heavy component is about 3:1;

4) after the temperature and pressure of the kettle reactor are reduced to room temperature and normal pressure, the mixed solution in the kettle reactor is taken out and filtered, and the filter cake is collected as the crude product;

5) put the crude product in step 4) into a flask equipped with a condenser tube and a stirrer, then add aviation kerosene to the flask, heat the flask until the solvent is refluxed, and stop heating after about 4h;

The mixed solution in the flask is filtered, and the filter cake is collected to obtain a purified crude product;

6) drying the purified crude product in step 5) at atmospheric pressure to obtain the hollow carbon microspheres of the present embodiment;

Among them, the drying temperature is 140 ℃, and the drying time is about 12h.

FIG. 7 is an SEM image of the hollow carbon microspheres obtained in Example 4, which are clearly shown as micron-sized spheres.

8 is a FIB-SEM image of the hollow carbon microspheres obtained in Example 4, which clearly shows that the microsphere product is a hollow microsphere with a certain wall thickness.

It can be determined from FIG. 7 and FIG. 8 that the particle size of the hollow carbon microspheres prepared in this example is 3-9 μm, the wall thickness is 0.5-1.5 μm, and the particle size distribution of the microspheres is more uniform than that of Example 1, and does not There are very few regular-shaped products, which benefit from further optimization of the raw material properties.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, but not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: The technical solutions described in the foregoing embodiments can still be modified, or some or all of the technical features thereof can be equivalently replaced; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the technical solutions of the embodiments of the present invention. scope.

Claims (12)

1. The preparation method of the hollow carbon microsphere is characterized by comprising the following steps:

extracting the heavy oil by using an extraction solvent in a supercritical state or a near-critical state to obtain an extracted oil phase; performing supercritical desolventizing treatment on the extraction oil phase to obtain an extraction component; wherein the extraction solvent is selected from light hydrocarbon or light hydrocarbon fraction of C3-C5;

subjecting a reaction system comprising the extracted component and an organic solvent to a thermal polycondensation reaction in a supercritical state or a near-critical state of the organic solvent;

separating the organic solvent after the thermal polycondensation reaction is finished, collecting a crude product, and adding a separation solvent for purification treatment to obtain a purified crude product;

and drying the purified crude product to obtain the hollow carbon microspheres.

2. The method for preparing hollow carbon microspheres according to claim 1, wherein the extracted oil phase is subjected to temperature-raising separation treatment to obtain an extracted light oil phase and an extracted heavy oil phase; respectively carrying out supercritical solvent removal treatment on the extracted light oil phase and the extracted heavy oil phase to obtain an extracted light component and an extracted heavy component;

in the thermal polycondensation reaction, the extraction component is selected from the extraction light component, the extraction heavy component or a mixture of the extraction light component and the extraction heavy component.

3. The method for preparing hollow carbon microspheres according to claim 1, wherein the reaction time of the thermal polycondensation is 0.5 to 10 hours.

4. The method for preparing hollow carbon microspheres according to any one of claims 1 to 3, wherein the temperature of the reaction system is controlled to be increased at a rate of 0.5 to 10 ℃/min until the organic solvent reaches a supercritical state or a near-critical state; or after the pressure of the reaction system is regulated to be raised to the supercritical pressure of the organic solvent, controlling the reaction system to be raised at the speed of 0.5-10 ℃/min until the organic solvent reaches the supercritical state or the near-critical state.

5. The method for preparing hollow carbon microspheres according to any one of claims 1 to 3, wherein the near-critical state of the organic solvent means that the real-time temperature of the organic solvent is 0.95 to 1.2 times its critical temperature and the real-time pressure is 1 to 5 times its critical pressure.

6. The method for preparing hollow carbon microspheres according to any one of claims 1 to 3, wherein in the thermal polycondensation reaction, the mass ratio of solvent to oil is not less than 0.5: 1.

7. the method for preparing hollow carbon microspheres according to any one of claims 1 to 3, wherein the recovering of the crude product and the purification treatment by adding the separation solvent comprises reflux purification using the separation solvent at reflux temperature of 50 to 280 ℃ for 2 to 48 hours.

8. The method for preparing hollow carbon microspheres according to any one of claims 1 to 3, wherein the heavy oil is selected from coal tar and catalytic cracking slurry oil.

9. The method for preparing hollow carbon microspheres according to any one of claims 1 to 3, wherein the organic solvent is selected from one or more of n-heptane, n-hexane, cyclohexane, n-pentane, cyclopentane, benzene, toluene, o-xylene, m-xylene, p-xylene, tetrahydronaphthalene, anthracene, tetrahydrofuran, pyridine and quinoline.

10. The method for preparing hollow carbon microspheres according to any one of claims 1 to 3, wherein the separation solvent is one or more selected from the group consisting of toluene, o-xylene, m-xylene, p-xylene, mixed xylene, quinoline, tetrahydronaphthalene, pyridine, ethanol, jet fuel, tetrahydrofuran and diesel.

11. A hollow carbon microsphere prepared by the method of any one of claims 1 to 10.

12. The hollow carbon microsphere according to claim 11, wherein the particle size of the hollow carbon microsphere is 3 to 50 μm and the wall thickness of the hollow carbon microsphere is 0.5 to 2.5 μm.

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