Graphene structured carbon material and methods and systems for making the same

Abstract

The present disclosure relates to a graphene structure carbon material and a preparation method and system thereof, the method comprising: performing aromatic hydrocarbon separation on a diesel fraction to obtain an aromatic hydrocarbon product; performing gas phase deposition on the aromatic hydrocarbon product on a carrier to obtain a graphene structure carbon material. The present disclosure uses a low-value diesel fraction as a raw material to prepare a high-value carbon material with a graphene structure, has high utilization rate of aromatic hydrocarbons, good performance of the carbon material, and realizes comprehensive utilization of the poor diesel fraction.

Description

Technical Field

[0001] This disclosure relates to the fields of carbon material preparation and comprehensive utilization of diesel fuel, specifically to a graphene-structured carbon material and its preparation method and system. Background Technology

[0002] Diesel fuel is the primary product of petroleum refining, widely used as fuel for diesel locomotives, railway diesel locomotives, ships, and large engines, providing indispensable power for industrial production and economic growth. In recent years, with the development of the global economic situation and increasing environmental protection requirements, higher demands have been placed on both the quantity and quality of diesel fuel products. Currently, diesel fuel quality standards are constantly being upgraded, especially regarding the content of polycyclic aromatic hydrocarbons (PAHs) in diesel fractions. In my country, the upper limit for PAH content has decreased from 11% to 7% in the transition from National V to National VI diesel standards, and will gradually approach zero in the future. How to utilize the aromatics in diesel fractions is a common problem faced by both the petrochemical and environmental protection industries.

[0003] The aromatic hydrocarbons in diesel fractions have a complex composition and can be roughly classified into the following categories. Among them, R1 to R6 are substituents on the benzene ring or naphthalene ring, which can be hydrogen atoms, alkyl groups, benzyl groups, etc.

[0004]

[0005] The traditional processing route for these aromatic hydrocarbons in the petrochemical industry involves hydrogenation to saturate and open the aromatic rings, converting them into alkanes which are then used as blending components in diesel fuel. This process is not only costly but also consumes large amounts of hydrogen, which is detrimental to the environment. Exploring new processing and utilization routes for diesel aromatic hydrocarbons has significant economic and social value, and finding a solution for the disposal of bicyclic aromatic hydrocarbons in diesel fractions is one of the important issues facing petrochemical enterprises. Summary of the Invention

[0006] The purpose of this disclosure is to provide a method, system, and graphene-structured carbon material for preparing graphene-structured carbon material from diesel fraction.

[0007] To achieve the above objectives, this disclosure provides a method for preparing graphene-structured carbon materials, the method comprising:

[0008] The diesel fraction was subjected to aromatic separation to obtain aromatic products;

[0009] The aromatic products were vapor-deposited on a support to obtain graphene-structured carbon materials.

[0010] Optionally, the diesel fraction includes at least one of catalytic diesel, coking diesel, and coal tar.

[0011] Optionally, the aromatic separation includes: extracting the diesel fraction with an extraction solvent to obtain an extract oil containing the aromatic product; subjecting the extract oil to vacuum distillation to obtain the aromatic product from the distillate; and using the residue as a recycled extraction solvent.

[0012] The aromatic products include bicyclic aromatics and / or tricyclic aromatics, and the total aromatic content in the aromatic products is more than 90% by weight, and the content of bicyclic or higher aromatics is 70-90% by weight.

[0013] Optionally, the extraction solvent is an ionic liquid, which includes cations and anions, wherein the cation is an alkyl-substituted imidazole or pyridine cation, and the anion is hexafluorophosphate, tetrafluoroborate, or bis(trifluoromethanesulfonyl)imide.

[0014] Optionally, the weight ratio of the ionic liquid to the diesel fraction is (1-8):1; the extraction temperature is 40℃-200℃, and the pressure is 0.1MPa-0.3MPa.

[0015] Optionally, the carrier is a metal foil, which includes copper foil and / or nickel foil.

[0016] Optionally, the conditions for vapor deposition include: a temperature of 700℃ to 1500℃, a carrier gas flow rate of 60 mL / min to 200 mL / min, and a volume ratio of the aromatic product to the carrier gas of (0.001 to 0.05):1.

[0017] Optionally, the method further includes stripping carbon material after the vapor deposition.

[0018] Optionally, the carbon material stripping includes:

[0019] The product obtained by the vapor deposition is brought into contact with a transfer medium to obtain a material coated with the transfer medium.

[0020] The material coated with the transfer medium is brought into contact with an etching solution to obtain an etching product;

[0021] The transfer medium on the etched product is removed using a cleaning agent;

[0022] The transfer medium comprises a polymer, preferably at least one of polymethyl methacrylate, polydimethylsiloxane, and acrylate; the etching solution contains at least one of ferric ions and ammonium persulfate; and the cleaning agent comprises at least one of acetone, deionized water, ethanol, and N-methylpyrrolidone.

[0023] The product obtained by the vapor deposition includes a carrier and a carbon material film deposited on the surface of the carrier; the method further includes: spin-coating the transfer medium onto the carbon material film, and drying it to obtain the material coated with the transfer medium.

[0024] This disclosure also provides a system for preparing graphene-structured carbon materials, the system comprising:

[0025] The aromatics separation unit is used to separate aromatics from diesel fractions to obtain aromatic products.

[0026] A vapor phase deposition unit is used to contact the aromatic hydrocarbon product with a support for vapor phase deposition to obtain graphene-structured carbon materials.

[0027] This disclosure further provides graphene-structured carbon materials prepared by the above-described methods or systems.

[0028] Optionally, the graphene-structured carbon material has a thickness of 0.335 nm to 1.5 μm and a specific surface area of ​​200 m². 2 / g~2500m 2 / g.

[0029] Through the above technical solution, this disclosure utilizes low-value-added diesel fraction as raw material to effectively separate aromatic components from the diesel fraction. These aromatic components are then subjected to vapor-phase deposition to prepare high-value-added carbon materials with a graphene structure. The aromatic utilization rate is high, and the carbon materials exhibit excellent performance. The remaining diesel fraction after aromatic separation is mainly composed of saturated hydrocarbons and monocyclic aromatics, with a significantly increased cetane number, making it suitable for use as a blending component in clean diesel. This disclosure achieves comprehensive utilization of low-quality diesel fractions. Applying this solution to the petrochemical industry can not only add value to some diesel products but also reduce carbon emissions for enterprises. The application of this solution is highly feasible, yielding significant economic and social benefits.

[0030] Other features and advantages of this disclosure will be described in detail in the following detailed description section. Attached Figure Description

[0031] The accompanying drawings are provided to further illustrate the present disclosure and form part of the specification. They are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation thereof. In the drawings:

[0032] Figure 1 This is a schematic diagram of the system and process for preparing graphene-structured carbon materials in Example 1.

[0033] Figure 2 yes Figure 1 A schematic diagram of the structure and process flow of the aromatic hydrocarbon separation unit.

[0034] Figure 3 yes Figure 1A schematic diagram of the structure and process flow of a mid-phase vapor deposition unit.

[0035] Figure 4a This is a photograph of the nickel foil before vapor deposition in Example 1.

[0036] Figure 4b This is a photograph of the nickel foil after vapor deposition in Example 1.

[0037] Figure 4c This is a microscopic photograph of the nickel foil after vapor deposition in Example 1.

[0038] Figure 4d The image shows the Raman spectrum of the carbon material obtained after vapor deposition in Example 1.

[0039] Figure 5 This is a photograph of the graphene-structured carbon material after carbon material was exfoliated in Example 1.

[0040] Figure 6a This is a photograph of the copper foil before vapor deposition in Example 2.

[0041] Figure 6b This is a photograph of the copper foil after vapor deposition in Example 2.

[0042] Figure 6c The image shows the Raman spectrum of the carbon material obtained after vapor deposition in Example 2.

[0043] Explanation of reference numerals in the attached figures

[0044] 1. Aromatic hydrocarbon separation unit; 2. Vapor phase deposition unit

[0045] 3 Carbon material stripping unit; 4 Diesel fraction input pipeline

[0046] 5. Extraction solvent inlet line 6. Extraction solvent circulation line

[0047] 7. Clean diesel blending component output pipeline; 8. Aromatics product input pipeline.

[0048] 9. Light hydrocarbon component output pipeline; 10. Carbon material input pipeline

[0049] 11 Extraction column 12 Vacuum distillation column

[0050] 13 Inert carrier gas inlet line 14 Heating furnace tube

[0051] 15 Heating furnace 16 Carrier

[0052] 17 Primary cooling equipment 18 Cooling oil return pipeline

[0053] 19 Secondary cooling equipment 20 Carrier gas circulation pipeline Detailed Implementation

[0054] The specific embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit this disclosure.

[0055] In a first aspect, this disclosure provides a method for preparing graphene-structured carbon materials, the method comprising:

[0056] The diesel fraction was subjected to aromatic separation to obtain aromatic products;

[0057] The aromatic product is contacted with a support and vapor-phase deposited to obtain a graphene-structured carbon material.

[0058] The diesel fraction can be of petroleum origin or of coal chemical origin. Preferably, the diesel fraction includes at least one of secondary processed diesel fuels such as catalytic diesel, coking diesel, and coal tar. The aromatics in these inferior diesel fractions are mainly naphthalene-based bicyclic aromatics, with all carbon atoms in the naphthalene ring structure having an sp... 2 Hybrid orbitals form σ bonds, identical to the basic structural unit of graphene, making it easy to prepare graphene-structured carbon materials. This disclosure converts inferior aromatic hydrocarbons in diesel fuel into graphene-structured carbon materials, significantly increasing the added value of diesel products, and the preparation process is atom-economical.

[0059] Furthermore, a liquid-liquid extraction method can be used to separate aromatics from the diesel fraction. Specifically, the aromatic separation may include: extracting the diesel fraction with an extraction solvent to obtain an extract oil containing the aromatic products; subjecting the extract oil to vacuum distillation to obtain the aforementioned aromatic products from the distillate; and using the residue as a recycled extraction solvent. Further, the extraction solvent is an ionic liquid. Using an ionic liquid as the extraction solvent can further improve the aromatic selectivity, resulting in a higher content of aromatic components, especially bicyclic aromatics. The ionic liquid is a highly aromatic-selective ionic liquid, comprising cations and anions. Preferably, the cation can be an alkyl-substituted imidazole or pyridine cation, and the anion can be hexafluorophosphate (PF6). - ), tetrafluoroborate (BF4) - ) or bis(trifluoromethanesulfonyl)imide (NTF2) -The weight ratio of the ionic liquid to the diesel fraction can be (1-8):1, preferably (2-5):1. The extraction temperature can be 40℃-200℃, preferably 80℃-150℃; the pressure can be 0.1MPa-0.3MPa, preferably 0.1MPa-0.2MPa. The aromatic products obtained after aromatic separation include bicyclic aromatics and / or tricyclic aromatics. The extraction solvent (i.e., ionic liquid) used in aromatic separation can be recycled back into this method. The recycling process can refer to existing methods (such as vacuum distillation), which will not be elaborated in this disclosure.

[0060] The vapor deposition can be thermochemical vapor deposition, and the carrier can be a metal foil. In this process, the aromatic products separated from the above steps undergo high-temperature catalytic thermal decomposition to generate carbon atom building blocks. These carbon units are absorbed by the metal foil, forming a graphene-structured carbon material film on the surface. Further, the metal foil can be made of a metal with high carbon solubility; for example, it can include at least one of copper foil and nickel foil. The vapor deposition is performed under an inert gas atmosphere (such as nitrogen or argon) as a carrier gas. The vapor deposition conditions can include: a temperature of 700℃~1500℃, preferably 800℃~1200℃; a carrier gas flow rate of 60mL / min~200mL / min; and a volume ratio of the aromatic product to the carrier gas of (0.001~0.05):1, preferably (0.002~0.02):1.

[0061] The graphene-structured carbon material grown on the carrier surface can be obtained through the above steps. Further, to peel the carbon material off the carrier, the method may also include carbon material peeling after the vapor deposition. The carbon material peeling may include:

[0062] The product obtained by the vapor deposition is brought into contact with a transfer medium to obtain a material coated with the transfer medium.

[0063] The material coated with the transfer medium is brought into contact with an etching solution to obtain an etching product;

[0064] The transfer medium on the etched product is removed using a cleaning agent.

[0065] Specifically, the transfer medium may include at least one of polymethyl methacrylate (PMMA), polydimethylsiloxane, and acrylate. The transfer medium is brought into contact with the vapor deposition product and cured (i.e., the solution is dried) for 8–20 hours to obtain a material coated with the transfer medium. Then, the material coated with the transfer medium is placed in an etching solution of a certain concentration to etch the metal foil. The etching solution may be a salt solution, which may include at least one of a solution containing ferric ions or an ammonium persulfate solution. The etching solution may be, for example, a FeCl3 solution or an ammonium persulfate solution, with a concentration of 0.1–1.5 M. The resulting etched product is a graphene-structured thin film containing the transfer medium. The transfer medium is then removed using a cleaning agent to obtain the graphene-structured carbon material. The cleaning agent is a solvent capable of removing the transfer medium by dissolution or reaction, and may include at least one of acetone, deionized water, ethanol, and N-methylpyrrolidone.

[0066] A second aspect of this disclosure provides a system for preparing graphene-structured carbon materials, with reference to... Figure 1 The system includes:

[0067] Aromatics separation unit 1 is used to separate aromatics from diesel fractions to obtain aromatic products;

[0068] The vapor deposition unit 2 is used to contact the aromatic product with the support for vapor deposition to obtain graphene-structured carbon materials.

[0069] Among them, reference Figure 2 When using liquid-liquid extraction to separate aromatics from diesel fractions, the aromatics separation unit 1 may include an extraction tower 11 and a vacuum distillation tower 12. In the extraction tower 11, an ionic liquid is used to extract the diesel fraction. In the vacuum distillation tower 12, the extraction solvent (i.e., the ionic liquid) used in the aromatics separation is recovered.

[0070] Among them, reference Figure 3 When the vapor deposition is thermochemical vapor deposition, the vapor deposition unit 2 may include a heating furnace 15, a primary cooling device 17, and a secondary cooling device 19. The heating furnace 15 is equipped with heating furnace tubes 14 for accommodating the carrier. The primary cooling device 17 is used to cool unreacted aromatic components, light hydrocarbons, carrier gas, etc. The secondary cooling device 19 is used to cool non-condensable gases.

[0071] Furthermore, the system may also include a carbon material stripping unit 3 for stripping carbon material from the product obtained after the vapor deposition unit 2 to obtain graphene-structured carbon material.

[0072] In a third aspect, this disclosure provides a graphene-structured carbon material prepared by the above-described method or system. Further, the thickness of the graphene-structured carbon material can be 0.335 nm to 1.5 μm, and the specific surface area is 200 m². 2 / g~2500m 2 / g, the shape can be similar to the shape of the carrier.

[0073] This disclosed method can effectively separate aromatic components from diesel fractions, and after vapor phase deposition and further exfoliation, carbon materials with graphene structures can be prepared. These carbon materials have wide applications, such as being used as electrodes for sensors or batteries, or as carbon molecular sieve membranes for separation and lubrication, etc.

[0074] The above method and system are explained below using a flowchart.

[0075] like Figure 1 As shown, diesel fraction enters aromatics separation unit 1 through diesel fraction input line 4, and extraction solvent enters aromatics separation unit 1 through extraction solvent input line 5. After liquid-liquid extraction separation, aromatic products are obtained, and clean diesel blending components are obtained through clean diesel blending component output line 7. The extraction solvent is recovered and recycled through extraction solvent return line 6. Aromatic products enter vapor deposition unit 2 through aromatic products input line 8. After high-temperature vapor deposition, graphene-structured carbon material products are obtained. At the same time, a certain amount of light hydrocarbon components are produced as by-products and output through light hydrocarbon component output line 9. The product obtained from vapor deposition is sent to carbon material stripping unit 3 through carbon material input line 10. After carbon material stripping, graphene-structured carbon materials are obtained, which can then be prepared into electrode materials or carbon molecular sieve membranes as needed.

[0076] like Figure 2 As shown, in the aromatic separation unit 1, the extraction solvent is fed into the extraction tower 11 from the upper extraction solvent input line 5, and the diesel fraction is fed into the extraction tower 11 from the lower diesel fraction input line 4 for countercurrent extraction. The raffinate of the diesel blending components is obtained at the top of the tower (line 7), and the extract oil rich in aromatic components is obtained at the bottom of the tower. The extract oil is fed into the vacuum distillation tower 12 from the middle. After vacuum distillation, the aromatic products are distilled off from the top of the tower (line 8), and the solvent at the bottom of the tower is returned to the extraction tower 1 for recycling via the extraction solvent circulation line 6.

[0077] like Figure 3As shown, in the vapor deposition unit 2, aromatic products enter the heating furnace tube 14 via the inert carrier gas input line 13. The heating furnace tube 14 is heated by the heating furnace 15 and vapor deposition is carried out on the carrier 16 to generate carbon materials. Unreacted aromatic components, light hydrocarbons, carrier gas, etc. are cooled by the primary cooling device 17. The resulting bottom cooling oil is recycled through the cooling oil return line 18. Non-condensable gas is cooled by the secondary cooling device 19 to obtain a small amount of light hydrocarbon components (line 9). The carrier gas is recycled through the carrier gas circulation line 20.

[0078] The present disclosure will be further described in detail below through examples.

[0079] Example 1

[0080] The composition of the raw diesel fuel is shown in Table 1, and the operating system and process are as follows: Figures 1 to 3 As shown in Table 1, 1-heptyl-3-methylimidazolium tetrafluoroborate ionic liquid was used as the extraction solvent in the aromatics separation unit, with a solvent-to-oil weight ratio of 3:1, an extraction temperature of 60℃, and a pressure of 0.1 MPa. Solvent recovery was performed using vacuum distillation, with a bottom temperature of 200℃ and a pressure of 1.3 kPa. The composition of the aromatics products and residues separated from the diesel fraction after extraction is shown in Table 1, and can be used as components for blending clean diesel.

[0081] Table 1

[0082] Alkanes 20.6 0.5 46.5 Cycloalkanes 7.7 0.7 18.1 Total aromatics 71.7 98.8 35.4 Monocyclic aromatic hydrocarbons 16.3 10.7 16.9 Bicyclic and higher aromatic hydrocarbons 55.4 88.1 18.5 cetane number 17.1 ＜10 49.1

[0083] The separated aromatic products were vapor-phase deposited onto the surface of nickel foil to obtain a carbon material with a graphene structure (nitrogen was used as the carrier gas, the flow rate was 80 mL / min, the temperature was increased to 1000℃ at 5℃ / min and held for 1 h, and the volume ratio of aromatic products to carrier gas was 0.0125:1). The morphology of the nickel foil before and after carbon deposition is shown in the figure. Figure 4a , Figure 4b The morphology under a microscope (1500x) is as follows Figure 4c Raman spectroscopy (operated by a Renishaw inVia Raman spectrometer, under conditions of 633nm laser irradiation) Figure 4d .

[0084] In the carbon material stripping unit, the side of the nickel foil with the grown carbon material was spin-coated with PMMA solution, dried for 12 hours, and then dissolved in 0.5M FeCl3 solution. The carbon material film was retrieved using a silicon wafer, and the PMMA was washed away sequentially with acetone and water, yielding a graphene-structured carbon material as shown below. Figure 5 This carbon material can be used to make electrodes.

[0085] from Figure 4d The results show that the obtained carbon material has very obvious sp 2 Hybridization peak (1580cm) -1This indicates that the material has a typical graphene structure, a thickness of 0.9 μm, and a specific surface area of ​​1100 m². 2 / g. Combination Figure 4c and Figure 4d It can be inferred that the carbon material obtained in this embodiment has a graphene structure and can be used as an electrode material or a carbon molecular sieve membrane material.

[0086] Example 2

[0087] Graphene-structured carbon materials were prepared according to the method in Example 1, the difference being that copper foil was used as the vapor deposition support, and the morphology of the copper foil before and after carbon deposition was as follows. Figure 6a , Figure 6b Raman spectra of carbon materials obtained by vapor deposition, such as Figure 6c .from Figure 6c The results show that carbon materials with graphene structures were also obtained on the surface of the copper foil. The copper foil with the carbon material deposited on its surface was directly used as the electrode material without being stripped.

[0088] This disclosed solution can not only significantly reduce the content of bicyclic and higher aromatic hydrocarbons in diesel fractions, providing blending components for the production of China VI diesel, but also use low-value-added aromatic hydrocarbon components to produce high-end carbon materials, thereby increasing the value of aromatic hydrocarbon components in diesel fractions. This not only improves the economic efficiency of enterprises and reduces carbon emissions, but also provides new ideas for enterprises to achieve high-quality transformation and development.

[0089] The preferred embodiments of the present disclosure have been described in detail above with reference to the accompanying drawings. However, the present disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present disclosure, various simple modifications can be made to the technical solutions of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.

[0090] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0091] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.

Claims

1. A method for preparing graphene-structured carbon materials, characterized in that, The method includes: The diesel fraction was subjected to aromatic separation to obtain aromatic products; The aromatic products were vapor-deposited on a support to obtain graphene-structured carbon materials. The diesel fraction includes at least one of catalytic diesel, coking diesel, and coal tar; the aromatic products include bicyclic aromatics and / or tricyclic aromatics; the total aromatic content of the aromatic products is more than 90% by weight, and the content of bicyclic or higher aromatics is 70-90% by weight; the vapor deposition conditions include: a temperature of 700℃-1500℃, a carrier gas flow rate of 60mL / min-200mL / min, and a volume ratio of the aromatic products to the carrier gas of (0.001-0.05):

1. The graphene-structured carbon material has a thickness of 0.335 nm to 1.5 μm and a specific surface area of ​​200 m². 2 / g~2500m 2 / g.

2. The method according to claim 1, wherein, The aromatic separation includes: extracting the diesel fraction with an extraction solvent to obtain an extract oil containing the aromatic products; subjecting the extract oil to vacuum distillation to obtain the aromatic products from the distillate; and using the residue as a recycled extraction solvent.

3. The method according to claim 2, wherein, The extraction solvent is an ionic liquid, which includes cations and anions. The cations are alkyl-substituted imidazole or pyridine cations, and the anions are hexafluorophosphate, tetrafluoroborate, or bis(trifluoromethanesulfonyl)imide.

4. The method according to claim 2, wherein, The weight ratio of the extraction solvent to the diesel fraction is (1~8):1; the extraction temperature is 40℃~200℃, and the pressure is 0.1MPa~0.3MPa.

5. The method according to claim 1, wherein, The carrier is metal.

6. The method according to claim 5, wherein, The carrier is a metal foil, which includes copper foil and / or nickel foil.

7. The method according to claim 1, wherein, The method also includes stripping carbon material after the vapor deposition.

8. The method according to claim 7, wherein, The carbon material stripping includes: The product obtained by the vapor deposition is brought into contact with a transfer medium to obtain a material coated with the transfer medium. The material coated with the transfer medium is brought into contact with an etching solution to obtain an etching product; The transfer medium on the etched product is removed using a cleaning agent; The transfer medium comprises a polymer; the etching solution contains at least one of ferric ions and ammonium persulfate; and the cleaning agent comprises at least one of acetone, deionized water, ethanol, and N-methylpyrrolidone. The product obtained by the vapor deposition includes a carrier and a carbon material film deposited on the surface of the carrier; the method further includes: spin-coating the transfer medium onto the carbon material film, and drying it to obtain the material coated with the transfer medium.

9. The method according to claim 8, wherein, The transfer medium includes at least one of polymethyl methacrylate, polydimethylsiloxane, and acrylate.

10. A system for preparing graphene-structured carbon materials by implementing the method of any one of claims 1 to 9, characterized in that, The system includes: The aromatics separation unit is used to separate aromatics from diesel fractions to obtain aromatic products. A vapor deposition unit is used to perform vapor deposition of the aromatic products on a support to obtain graphene-structured carbon materials.

11. A graphene-structured carbon material, characterized in that, It is prepared by the method according to any one of claims 1-9 or by the system according to claim 10.

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