Petroleum-based hard carbon material and preparation method and system thereof

Abstract

The invention discloses a petroleum-based hard carbon material and a preparation method and system thereof. The preparation method comprises the following steps: carrying out solid removal and component adjustment on petroleum heavy oil to obtain pretreated petroleum heavy oil; selectively mixing more than two types of pretreated heavy petroleum oil to obtain mixed pyrolytic oil; carrying out microwave pyrolysis on the pretreated heavy petroleum oil or mixed pyrolytic oil to obtain pyrolytic carbon; modifying the pyrolytic carbon in the presence of a structure adjusting gas to obtain modified pyrolytic carbon; the modified pyrolytic carbon is crushed and coated with a modifier, and a hard carbon precursor is obtained; and carbonizing the hard carbon precursor to obtain the petroleum-based hard carbon material. The petroleum heavy oil is used as a carbon source, no additional chemical reagent is adopted, and the method has the advantages of being environmentally friendly and low in cost. The petroleum-based hard carbon material disclosed by the invention has relatively high electrochemical performance and can be used as a negative electrode material of a sodium-ion battery.

Description

A petroleum-based hard carbon material and its preparation method and system Technical Field

[0001] This invention relates to a petroleum-based hard carbon material and its preparation method and system, belonging to the field of anode material technology. Background Technology

[0002] With the rapid development of lithium-ion batteries and the scarcity of lithium resources, sodium-ion batteries, formed from sodium (an element in the same group as lithium), have abundant and inexpensive raw material resources. Furthermore, due to the properties of sodium, the manufacturing cost of sodium-ion batteries can be significantly reduced. Sodium-ion batteries have an ultra-wide operating temperature range of -40℃ to 80℃, and are less prone to thermal runaway even at high temperatures. Moreover, while lithium-ion batteries have higher internal resistance, sodium-ion batteries have lower short-circuit current and less instantaneous heat generation, making them less likely to cause fires or spontaneous combustion.

[0003] Graphite is widely used as an anode material in lithium-ion batteries due to its small interlayer spacing. Sodium ions, with their larger atomic mass and radius than lithium ions, are more difficult to insert into and detach from graphite during reactions. Therefore, sodium-ion batteries require the use of hard carbon materials with a different structure than graphite as the anode material.

[0004] Currently, the raw materials for preparing hard carbon materials mainly include aromatic resin polymers and biomass materials. Resin polymers are more expensive, while biomass materials are widely available in nature and have lower costs. However, biomass materials vary significantly by region and are difficult to collect; hard carbon materials made from the same type of biomass can have different properties depending on their origin. Furthermore, biomass materials have a high ash content, which usually requires acid washing to remove, but acid washing is environmentally unfriendly.

[0005] CN117945391A discloses a pitch-based carbon material, its preparation method, and its application. The method involves pulverizing, ball milling, and classifying pitch to obtain a powder; mixing the powder with an oxidant and then subjecting it to oxidation treatment to obtain an oxidized polymer; subjecting the oxidized polymer to a first carbonization treatment in an inert atmosphere to obtain a low-temperature carbonized polymer; and subjecting the low-temperature carbonized polymer to a second carbonization treatment in an inert atmosphere to obtain the pitch-based carbon material. The oxidant used in this method is an organic oxidant, which may explode when heated above 150°C, posing a fire and explosion hazard.

[0006] CN108963253A discloses a porous hard carbon anode material, its preparation method, and a lithium-ion battery. The method involves mixing nanomaterials, a solvent, and a carbonaceous precursor, then evaporating to remove the solvent, resulting in a mixture of nanomaterials and the carbonaceous precursor. This mixture is then sequentially cured, carbonized, crushed, graded, etched, and subjected to high-temperature tempering to obtain a high-temperature tempered powder. Finally, it is coated to obtain the porous hard carbon anode material. The etching agent used in this method includes one or more of HCl, H2SO4, HNO3, and HF, which removes the nanomaterials to form a porous structure. This process not only uses strong acids but also uses nanomaterials only as pore-forming agents, resulting in high costs and environmental unfriendliness.

[0007] CN114516627A discloses a method for preparing soft and hard carbon composite nanomaterials. This method involves placing asphalt, weathered coal humic acid, and a pore-forming agent into a ball mill jar, adding water and ethanol, and then ball milling. The milled slurry is dried and then placed in a reactor under a nitrogen atmosphere for high-temperature reaction. After washing with water and drying, it is calcined in a high-temperature tube furnace to obtain the soft and hard carbon composite nanomaterials. The pore-forming agent used in this method is one of lithium chloride, sodium chloride, and potassium chloride, thus requiring water washing. Furthermore, the use of the pore-forming agent increases the cost and complicates the process. Moreover, weathered coal humic acid contains high levels of impurities of varying types, which can easily lead to poor batch stability of the soft and hard carbon composite nanomaterials.

[0008] The existing technologies described above use oxidants, etchants, or pore-conditioning agents to form defects and pore structures in hard carbon materials. These methods either pose high safety risks or are cumbersome and polluting, thus losing the carbon reduction and environmental protection significance of new energy materials themselves.

[0009] In addition, existing technologies use biomass materials as raw materials for the preparation of hard carbon materials, which has the problem of large differences in properties due to different origins, resulting in poor performance stability of the hard carbon materials. Summary of the Invention

[0010] To address at least one of the aforementioned technical problems, the present invention aims to provide a petroleum-based hard carbon material and its preparation method and system. The present invention uses heavy petroleum oil as the carbon source and does not employ additional chemical reagents. Furthermore, the petroleum-based hard carbon material prepared by the present invention exhibits high electrochemical performance.

[0011] To achieve the above objectives, a first aspect of the present invention provides a method for preparing a petroleum-based hard carbon material, comprising the following steps:

[0012] (1) The heavy petroleum oil is desolidified and its composition is adjusted to obtain pretreated heavy petroleum oil; two or more of the pretreated heavy petroleum oils are selectively mixed to obtain mixed pyrolysis oil;

[0013] (2) Microwave pyrolysis is performed on the pretreated heavy petroleum oil or the mixed pyrolysis oil in a fluidized reactor to obtain pyrolysis char.

[0014] (3) The pyrolytic carbon is modified in the presence of a structure-adjusting gas to obtain modified pyrolytic carbon;

[0015] (4) The modified pyrolytic carbon is pulverized to obtain pulverized pyrolytic carbon; the pulverized pyrolytic carbon is coated with a modifier to obtain a hard carbon precursor.

[0016] (5) Carbonize the hard carbon precursor to obtain the petroleum-based hard carbon material.

[0017] According to a specific embodiment of the present invention, preferably, in step (1), based on the total mass of the heavy petroleum oil as 100%, the heavy petroleum oil has a saturated content of 5-30%, an aromatic content of 45-89%, a gum content of 5-25%, an asphaltenes content of 0-8%, a sulfur content of 0.1-3.2%, a nitrogen content of 0.05-0.85%, and a carbon residue content of 5-17%; and the heavy petroleum oil has an ash content of 300-5000 ppm. Specifically, the heavy petroleum oil includes, but is not limited to, one or more of the following: catalytic cracking slurry oil, coking wax oil, thermal cracking residue oil, hydrotreated tail oil, furfural extract oil, reformed heavy aromatic oil, vacuum distillate oil, ethylene tar, vacuum residue oil, thermal cracking residue oil, and ethylene tar hydrotreated wax oil fraction.

[0018] In this invention, ash refers to all metallic impurities, generally including one or more of Fe, Ni, V, Al, Cu, Na and Ca.

[0019] According to a specific embodiment of the present invention, preferably, in step (1), the ash content of the deconsolidated heavy petroleum oil is 10-50 ppm. Specifically, the deconsolidation method includes, but is not limited to, one or more of sedimentation deconsolidation, centrifugal deconsolidation, and electric field deconsolidation. These deconsolidation methods can all be carried out according to existing technologies, and the present invention does not impose any special limitations on them.

[0020] According to a specific embodiment of the present invention, preferably, in step (1), the component adjustment includes one or more of distillation, solvent extraction, and solvent extraction. The present invention does not impose special restrictions on the conditions of these processes, which can be routinely adjusted by those skilled in the art, as long as the pretreated heavy petroleum oil that meets the requirements of the present invention can be obtained.

[0021] According to a specific embodiment of the present invention, preferably, in step (1), the pretreated heavy petroleum oil has a distillation range of 350–700°C and a density (20°C) of 0.95–1.15 g / cm³. 3 Based on the total mass of the pretreated heavy petroleum oil as 100%, the pretreated heavy petroleum oil has a saturated content of 10-25%, an aromatic content of 50-80%, a gum content of 1-20%, an asphaltenes content of 0-10%, a sulfur content of 0.5-2%, a nitrogen content of 0.05-0.7%, and a carbon residue content of 5-15%.

[0022] According to a specific embodiment of the present invention, preferably, in step (1), the mixing of two or more pretreated heavy petroleum oils is carried out by online mixing, wherein the online mixing temperature is 80-120°C and the linear velocity is 0.5-0.7 m / s.

[0023] According to a specific embodiment of the present invention, preferably, in step (1), the mixed pyrolysis oil has a distillation range of 350–700°C and a density (20°C) of 1.01–1.12 g / cm³. 3 Based on the total mass of the mixed pyrolysis oil as 100%, the mixed pyrolysis oil has a saturated content of 10-23%, an aromatic content of 55-80%, a gum content of 5-25%, an asphaltenes content of 1-6%, a sulfur content of 0.1-2%, a nitrogen content of 0.08-0.7%, and a residual carbon content of 8-15%. This invention does not impose special restrictions on the mixing ratio of two or more pretreated heavy petroleum oils, as long as a mixed pyrolysis oil meeting the above-mentioned indicators of this invention is obtained.

[0024] According to a specific embodiment of the present invention, preferably, in step (2), the mixed pyrolysis oil is subjected to microwave pyrolysis in a fluidized bed reactor to obtain pyrolysis char. In this case, step (1) includes: mixing two or more pretreated heavy petroleum oils to obtain mixed pyrolysis oil.

[0025] According to a specific embodiment of the present invention, preferably, step (2) includes: introducing the pretreated heavy petroleum oil or the mixed pyrolysis oil into a fluidized bed reactor, the fluidized bed reactor being connected to a microwave generator, and the pretreated heavy petroleum oil or the mixed pyrolysis oil being subjected to microwave pyrolysis by the microwave generator to obtain pyrolysis char and oil gas, the pyrolysis char being in a fluidized state; wherein, the flow rate of the pretreated heavy petroleum oil or the mixed pyrolysis oil entering the fluidized bed reactor is 1-2 kg / h, the frequency of the microwave generator is controlled at 2350-2550 MHz and the power at 2-5 kW, the residence time of the pretreated heavy petroleum oil or the mixed pyrolysis oil in the fluidized bed reactor is 2-4 seconds, and the temperature in the fluidized bed reactor is controlled at 530-580°C. The fluidized bed reactor connected to the microwave generator can be any existing device, and the present invention does not impose any special limitations on it. Those skilled in the art will understand that the microwave generator includes a control unit and a modulation unit, etc., to regulate the frequency and power of the microwave within the above-mentioned range. Those skilled in the art will understand that the fluidized reactor may also be referred to as a fluidized bed reactor.

[0026] In this invention, it should be noted that the pretreated heavy petroleum oil or mixed pyrolysis oil that first enters the fluidized reactor generates pyrolysis carbon and oil gas under the action of microwaves and heat. The pretreated heavy petroleum oil or mixed pyrolysis oil that enters the fluidized reactor later is in a gaseous state before being pyrolyzed into pyrolysis carbon. Therefore, the fluidized reactor contains the solid pyrolysis carbon and gaseous oil generated by the reaction first, and the pyrolysis carbon particles are suspended in the gaseous oil in a fluidized state.

[0027] This invention uses heavy petroleum oil as a carbon source, which contains a large amount of polycyclic aromatic hydrocarbons (PAHs). Since different components in heavy petroleum oil have different pyrolysis rates, this invention adjusts the composition of the heavy petroleum oil after desolidification to remove metallic impurities. By controlling the component content of the pretreated heavy petroleum oil and the mixed pyrolysis oil within the range specified in this invention, the pretreated heavy petroleum oil or the mixed pyrolysis oil can form different reaction networks during pyrolysis, thereby forming the structure of the petroleum-based hard carbon material of this invention. Specifically, by controlling the component content of the pretreated heavy petroleum oil and the mixed pyrolysis oil, and by using a fluidized bed reactor for microwave pyrolysis and controlling the pyrolysis conditions within the aforementioned range, this invention enables the aggregates of macromolecular aromatic rings to have high pyrolysis reactivity, allowing for relatively rapid pyrolysis. This results in short-range carbon microcrystals with small crystal size, short-range order and long-range disorder, interlaced carbon layers, and low directionality. Furthermore, it causes the polycyclic aromatic hydrocarbons to undergo pyrolysis, forming long-range carbon microcrystals with larger crystal size, long-range order, relatively regular carbon layer arrangement, and high directionality. During pyrolysis, the short-range carbon microcrystals form the core, while the long-range carbon microcrystals, as a regular carbon framework, form the extension of the core. Simultaneously, the saturated fractions in the pretreated heavy petroleum oil or mixed pyrolysis oil undergo pyrolysis to generate small-molecule hydrocarbons. Furthermore, the side chains of aromatic hydrocarbons may break during pyrolysis, also generating small-molecule hydrocarbons. Since these small-molecule hydrocarbons escape as oil and gas, the short-range and long-range carbon microcrystals simultaneously construct a three-dimensional porous structure. Moreover, this three-dimensional porous structure primarily consists of internally closed pores, which are channels larger than the interlamellar spacing, providing ion transport pathways. Therefore, the inventors hypothesize that the pyrolytic carbon of this invention has a structure with short-range carbon microcrystals as the core and long-range carbon microcrystals as the extension, containing internal pores. This allows the petroleum-based hard carbon material of this invention to also possess this core-extension structure containing internal pores. Due to the above structure, sodium ions can be embedded or adsorbed at multiple locations, including between layers, within pores, at pore edges, and on the outer surface, contributing space for storing sodium ions. Most existing hard carbon materials are based on short-range carbon microcrystals, which offer good fast-charging performance but have unsatisfactory capacity. The short-range carbon microcrystals of this invention provide storage space; the long-range carbon microcrystals increase the number of storage sites between layers, thus increasing capacity; simultaneously, the presence of internal pores not only provides storage space but also enables faster ion output, thereby improving power.

[0028] According to a specific embodiment of the present invention, preferably, step (2) further includes: distilling the oil and gas at least to obtain gasoline, diesel, and wax oil, etc. Specifically, after the oil and gas flows out from the top of the fluidized reactor, it can be cooled first to collect non-condensable gases; then the remaining part is distilled. The distillation can be carried out using a distillation column. The present invention does not impose special restrictions on the specific operating conditions of the distillation column, and conventional conditions in the art can be used. The gasoline, diesel, and wax oil obtained after distillation can be used as fuel oil.

[0029] According to a specific embodiment of the present invention, preferably, in step (3), the structure-adjusting gas includes one or two of water vapor and carbon dioxide, the modification temperature is 800-1000°C, the time is 1-4 hours, and the flow rate of the structure-adjusting gas is 0.5-1 L / h per 1 kg of pyrolytic carbon. Specifically, the modification can be carried out in a modifier, which can be a conventional reactor with heating function, such as a reactor with an electromagnetic heating unit. The pyrolytic carbon is added to the modifier, and the structure-adjusting gas is introduced while heating for modification. In the present invention, because the pyrolysis time is relatively short, the resulting pyrolytic carbon may adsorb some oil and gas, and at the same time, the pyrolytic carbon may carry some unreacted components (especially aromatics). The present invention allows the pyrolytic carbon discharged from the fluidized reactor to enter the modifier for modification. During this process, the structure-adjusting gas separates the adsorbed and carried oil and gas and unreacted components from the pyrolytic carbon on the one hand, and on the other hand, it constructs deep pores in the microcrystalline carbon skeleton of the pyrolytic carbon, forming more nanopores. The oil and gas separated from the pyrolysis char and the unreacted components can be returned to the fluidized reactor for further pyrolysis and / or oil and gas recovery.

[0030] According to a specific embodiment of the present invention, preferably, in step (4), the D10 particle size of the pulverized pyrolytic carbon is 2-3 μm, the D50 particle size is 7-10 μm, and the D90 particle size is 14-16 μm. Specifically, the pulverization can be carried out using an air jet mill and / or a mechanical grinder, etc., which should have pulverization and classification functions to obtain the pyrolytic carbon with the above-mentioned particle size range of the present invention. After pulverization, the present invention obtains pyrolytic carbon with suitable particle morphology and particle size distribution.

[0031] According to a specific embodiment of the present invention, preferably, in step (4), the modifier comprises wax oil; the wax oil has a distillation range of 360–550°C and a density (20°C) of 1.10–1.15 g / cm³. 3 Based on the total mass of the wax oil as 100%, the wax oil has a saturated content of 5-12%, an aromatic content of 68-90%, and a gum content of 5-20%. More preferably, the wax oil is the wax oil obtained by distillation of the oil and gas in step (2).

[0032] According to a specific embodiment of the present invention, preferably, in step (4), the coating includes: heating the modifier to 50-100°C, then pressurizing it to 2-3 MPa, and then spraying the modifier onto the pulverized pyrolytic carbon being stirred through a spray head. The diameter of the spray head is 0.5-1 mm, the stirring speed is 500-1000 r / min, and the amount of modifier is 1-10% of the mass of the pulverized pyrolytic carbon. Specifically, the coating can be carried out using a liquid-phase coating machine, and the residence time of the pulverized pyrolytic carbon in the liquid-phase coating machine can be 20-40 min. By using the coating method of the present invention, the modifier is sprayed out at high speed and contacts the pyrolytic carbon being stirred, thereby making the formed modifier coating layer more uniform. After the coating is completed, nitrogen gas can be introduced into the liquid-phase coating machine for cooling. After cooling to room temperature, pyrolytic carbon with a modifier coating layer is obtained, which is the hard carbon precursor. This invention coats modified pyrolytic carbon with a modifier. During the subsequent carbonization process, the modifier can form an amorphous carbon layer on the surface of the hard carbon material, thereby providing more reversible sodium storage sites. At the same time, during application, the coating layer of this invention can reduce the direct contact between the hard carbon material and the electrolyte, suppressing the occurrence of side reactions. Furthermore, the coating layer of this invention also increases the conductivity of the hard carbon material, improves the surface chemical properties of the material, and can also provide a fast ion diffusion pathway.

[0033] According to a specific embodiment of the present invention, preferably, in step (5), the carbonization temperature is 1200–1600°C, the heating rate is 1–10°C / min, and the carbonization time is 1–5 hours. Furthermore, the carbonization is carried out in a protective atmosphere, such as, but not limited to, nitrogen. By controlling the carbonization conditions within the above range, the present invention achieves a shorter carbonization reaction time, resulting in a lower degree of carbonization, and consequently, a larger interlayer spacing in the petroleum-based hard carbon material of the present invention.

[0034] A second aspect of the present invention provides a petroleum-based hard carbon material, which is prepared by the above-described method for preparing petroleum-based hard carbon materials.

[0035] According to a specific embodiment of the present invention, preferably, the specific surface area of ​​the petroleum-based hard carbon material is 4-7 m². 2 / g, interlayer spacing of crystals is 0.378–0.385 nm, and tap density is 0.7–0.8 g / cm³. 3 The petroleum-based hard carbon material of the present invention possesses various types of reversible sodium storage sites due to its large interlayer spacing, numerous defects, and abundant porosity.

[0036] A third aspect of the present invention provides a preparation system for petroleum-based hard carbon materials, which is used to realize the above-mentioned preparation method of petroleum-based hard carbon materials. The preparation system includes: a desolidification device, a component adjustment device, a fluidized reactor, a microwave generator, a modifier, a pulverizing device, a liquid phase coating machine, and a carbonization furnace, and optionally includes an online mixer.

[0037] The number of the solidification device and the component adjustment device is one or more; the outlet of one solidification device is connected to the inlet of one component adjustment device, and the outlet of one component adjustment device is connected to the inlet of the fluidized reactor; or, the outlets of two or more solidification devices are respectively connected to the inlets of two or more component adjustment devices, the outlets of two or more component adjustment devices are connected to the inlet of the online mixer, and the outlet of the online mixer is connected to the inlet of the fluidized reactor;

[0038] The fluidized reactor is connected to the microwave generator for providing microwave heating to the fluidized reactor;

[0039] The pyrolysis carbon outlet of the fluidized reactor is connected to the pyrolysis carbon inlet of the modifier. The modifier is also provided with a structure adjustment gas inlet. The modified pyrolysis carbon outlet of the modifier is sequentially connected to the pulverizing device, the liquid phase coating machine and the carbonization furnace.

[0040] According to a specific embodiment of the present invention, preferably, the deconsolidation device includes one or more of the following: a sedimentation deconsolidation device, a centrifugal deconsolidation device, and an electric field deconsolidation device. These devices can all be existing technologies, and the present invention does not impose any special limitations on them.

[0041] According to a specific embodiment of the present invention, preferably, the component adjustment device includes one or more of the following: a distillation column, an extraction column, and an extraction column.

[0042] According to a specific embodiment of the present invention, preferably, the microwave generator includes at least a control unit and a modulation unit for regulating the frequency and power of the microwaves.

[0043] According to a specific embodiment of the present invention, preferably, the preparation system further includes a distillation column, the fluidized reactor is also provided with an oil and gas outlet, the oil and gas outlet is connected to the inlet of the distillation column, and the distillation column is provided with at least a gasoline outlet, a diesel outlet and a wax oil outlet.

[0044] According to a specific embodiment of the present invention, preferably, the modifier includes a reactor having an electromagnetic heating unit.

[0045] According to a specific embodiment of the present invention, preferably, the reformer is further provided with an outlet for oil and gas and unreacted components, the outlet for oil and gas and unreacted components being connected to the fluidized reactor, for returning the oil and gas and unreacted components separated from the pyrolytic carbon to the fluidized reactor for further pyrolysis and / or recovery of oil and gas.

[0046] According to a specific embodiment of the present invention, preferably, the pulverizing device includes one or two of an air jet mill and a mechanical grinder.

[0047] According to a specific embodiment of the present invention, preferably, the preparation system further includes a heating device and a pressurizing device, the wax oil outlet of the distillation column is connected to the inlet of the heating device, the outlet of the heating device is connected to the inlet of the pressurizing device, and the outlet of the pressurizing device is connected to the liquid phase coating machine for providing the heated and pressurized modifier to the liquid phase coating machine.

[0048] According to a specific embodiment of the present invention, preferably, the liquid phase coating machine includes at least a spray head and a stirring unit; the diameter of the spray head is 0.5-1 mm, and it is used to spray a modifier; the stirring unit is used to stir the pulverized pyrolytic carbon in the liquid phase coating machine.

[0049] The present invention has at least the following beneficial effects:

[0050] This invention uses heavy petroleum oil as a carbon source, which has the advantages of wide availability and stable physical properties. It simultaneously prepares hard carbon materials, processes heavy petroleum oil, and produces fuel oil as a byproduct, making it environmentally friendly and cost-effective. Furthermore, this invention does not use additional chemical reagents such as oxidants, etchants, or pore-conditioning agents, reducing safety and environmental risks while also lowering costs. Therefore, this invention is suitable for large-scale industrial applications. The petroleum-based hard carbon material of this invention provides ample pathways for sodium ion insertion and deintercalation, exhibiting high electrochemical performance. Therefore, the petroleum-based hard carbon material of this invention can be used as a negative electrode material in sodium-ion batteries, exhibiting high initial sodium deintercalation capacity and initial coulombic efficiency. Attached Figure Description

[0051] Figure 1 is a schematic diagram of the preparation system of petroleum-based hard carbon material in an embodiment of the present invention.

[0052] Explanation of icon numbers:

[0053] 1-Deconsolidation device; 2-Component adjustment device; 3-Online mixer; 4-Fluidized reactor; 5-Microwave generator; 501-Control unit; 502-Modulation unit; 6-Distillation column; 7-Modifier; 8-Pulverizing device; 9-Liquid phase coating machine; 10-Heating device; 11-Pressure boosting device; 12-Carbonization furnace. Detailed Implementation

[0054] To provide a clearer understanding of the technical features, objectives, and beneficial effects of the present invention, the present invention will now be described in detail below, but this should not be construed as limiting the scope of the invention.

[0055] Test method:

[0056] Saturated content, aromatic content, resin content and asphaltene content: were obtained according to the records in SH / T 0509-2010 "Determination of Four Components of Petroleum Asphalt".

[0057] Sulfur content: The sulfur content was determined according to the specifications in GB / T 17040-2019 "Determination of sulfur content in petroleum and petroleum products by energy dispersive X-ray fluorescence spectrometry".

[0058] Nitrogen content: The nitrogen content was determined according to the specifications in SH / T 0657-2007 "Determination of trace nitrogen in liquid petroleum hydrocarbons by oxidative combustion and chemiluminescence method".

[0059] Carbon residue content: Tested according to the description in GB / T 17144-2021 "Determination of Carbon Residue in Petroleum Products (Trace Method)".

[0060] Ash content by mass: Tested according to the method for determination of ash content in petroleum products in GB / T 508-1985.

[0061] The specific surface area of ​​hard carbon materials was obtained according to the specifications in GB / T 19587-2017 "Determination of specific surface area of ​​solid materials by gas adsorption BET method".

[0062] Interlayer spacing of hard carbon materials: measured according to Appendix E of GB / T 24533-2019 "Graphite Anode Materials for Lithium-ion Batteries".

[0063] Tap density of hard carbon materials: Tested according to the description in GB / T 21354-2008 "General Method for Determination of Tap Density of Powder Products".

[0064] Electrochemical performance of hard carbon materials: Assembling hard carbon materials into sodium-ion button half-cells includes the following steps: Hard carbon materials, conductive agent Super-p, binder CMC, and binder SBR in a mass ratio of 93.26:1.74:1.5:3.5 are added to an appropriate amount of deionized water and thoroughly mixed to obtain a negative electrode slurry. This negative electrode slurry is coated onto copper foil and then dried in a vacuum drying oven for 12 hours to obtain a negative electrode sheet. The electrolyte is a 1 mol / L NaPF6 electrolyte, in which the solvent is a mixed solvent of ethylene carbonate (EC), diethyl carbonate (DEC), and dimethyl carbonate (DMC) in a volume ratio of 1:1:1. The separator is a PP-PE-PP composite membrane. The counter electrode is a sodium sheet. Using the above-mentioned negative electrode sheet, electrolyte, separator, and counter electrode, a sodium-ion button half-cell is assembled in a glove box. The cell size is Φ20.0×1.6mm. A constant current charge-discharge experiment was conducted in the Xinwei battery testing system. The charge-discharge voltage was 0.005-2V, and the charge-discharge current was 0.05C.

[0065] It should be noted that in the following examples and comparative examples, if the sum of the contents of the four components is not equal to 100%, it is due to testing errors, which is a common occurrence in the art.

[0066] Example 1

[0067] This embodiment provides a petroleum-based hard carbon material, the preparation method of which includes the following steps:

[0068] The catalytic cracking slurry (based on the total mass of the catalytic cracking slurry, containing 17% saturated fraction, 64% aromatic fraction, 16% gum content, 3% asphaltenes content, 0.53% sulfur content, 0.2% nitrogen content, and 9.5% residual carbon content; and with an ash content of 2000 ppm) was desolidified by an electric field to reduce the ash content to 20 ppm, yielding the desolidified catalytic cracking slurry. The ethylene tar hydrogenated wax oil fraction (based on the total mass of the ethylene tar hydrogenated wax oil fraction, containing 17% saturated fraction, 64% aromatic fraction, 16% gum content, 3% asphaltenes content, 0.53% sulfur content, 0.2% nitrogen content, and 9.5% residual carbon content; and with an ash content of 2000 ppm) was then subjected to electric field desolidification to reduce the ash content to 20 ppm, resulting in the desolidified catalytic cracking slurry. The ethylene tar hydrogenated wax oil fraction (containing 8% arsenic, 67% aromatics, 17% gum, 8% asphaltenes, 0.1% sulfur, 0.06% nitrogen, and 16% residual carbon, with an ash content of 600 ppm) was centrifuged to reduce the ash content to 10 ppm, yielding a deconsolidated ethylene tar hydrogenated wax oil fraction. The deconsolidated catalytic cracking slurry and the deconsolidated ethylene tar hydrogenated wax oil fraction were then distilled separately to obtain pretreated catalytic cracking slurry and pretreated ethylene tar hydrogenated wax oil fraction.

[0069] The pretreated catalytic cracking slurry has a boiling range of 350–610℃ and a density (20℃) of 1.06 g / cm³. 3 Based on the total mass of the pretreated catalytic cracking slurry as 100%, the saturated content is 18%, the aromatic content is 66%, the gum content is 15%, the asphaltene content is 1%, the sulfur content is 0.5%, the nitrogen content is 0.2%, the residual carbon content is 8%, and the ash content is 50 ppm.

[0070] The pretreated ethylene tar hydrogenated wax oil fraction has a boiling range of 370–560℃ and a density (20℃) of 1.12 g / cm³. 3 Based on the total mass of the pretreated ethylene tar hydrogenated wax oil fraction as 100%, the saturated content is 10%, the aromatic content is 70%, the gum content is 15%, the asphaltenes content is 5%, the sulfur content is 0.1%, the nitrogen content is 0.06%, the carbon residue content is 15%, and the ash content is 30 ppm.

[0071] Subsequently, the pretreated catalytic cracking slurry and the pretreated ethylene tar hydrogenated wax oil fraction were mixed online at a mass ratio of 1:3. The online mixing temperature was 80℃ and the linear velocity was 0.7 m / s, yielding a mixed pyrolysis oil. This mixed pyrolysis oil had a boiling range of 350–610℃ and a density (20℃) of 1.105 g / cm³. 3 Based on the total mass of the mixed pyrolysis oil as 100%, the saturated content is 12%, the aromatic content is 69%, the gum content is 15%, the asphaltenes content is 4%, the sulfur content is 0.2%, the nitrogen content is 0.1%, the residual carbon content is 13%, and the ash content is 35 ppm.

[0072] Then, the mixed pyrolysis oil is continuously fed into a fluidized bed reactor connected to a microwave generator. The microwave generator causes the mixed pyrolysis oil to undergo microwave pyrolysis, yielding pyrolysis char and oil gas. The pyrolysis char is in a fluidized state. The flow rate of the mixed pyrolysis oil into the fluidized bed reactor is 1 kg / h, the frequency of the microwave generator is controlled at 2450 MHz and the power at 2 kW, the residence time of the mixed pyrolysis oil in the fluidized bed reactor is 2 seconds, and the temperature in the fluidized bed reactor is controlled at 530°C.

[0073] After the oil and gas flow out from the top of the fluidized reactor, they are first cooled to collect the non-condensable gas; then the remaining part is distilled to obtain gasoline, diesel and wax oil.

[0074] Subsequently, the pyrolytic carbon is fed into a reformer for reforming. The temperature in the reformer is controlled at 1000℃ by electromagnetic heating, and steam is introduced at a flow rate of 0.5 L / h per 1 kg of pyrolytic carbon. The reforming time is 1 hour, resulting in reformed pyrolytic carbon. At the same time, the oil and gas separated from the pyrolytic carbon and the unreacted components can be returned to the fluidized reactor for further pyrolysis and / or oil and gas recovery.

[0075] The modified pyrolytic carbon was then pulverized using a mechanical grinder to obtain pulverized pyrolytic carbon with a D10 particle size of 2.3 μm, a D50 particle size of 8.1 μm, and a D90 particle size of 15.8 μm.

[0076] Then, the pulverized pyrolytic carbon is added to a liquid-phase coating machine. The wax oil obtained by distillation of the oil and gas produced by the pyrolysis is used as a modifier. This wax oil has a distillation range of 380–550℃ and a density (20℃) of 1.12 g / cm³. 3 The wax oil, with a total mass of 100%, contains 8% saturated fraction, 75% aromatic fraction, and 17% gum. The wax oil is heated to 60°C and then pressurized to 3MPa using a high-pressure pump. The wax oil is then sprayed onto the pulverized pyrolytic carbon being stirred using a 0.5mm diameter nozzle. The stirring speed of the liquid-phase coating machine is 800r / min, and the amount of wax oil used is 10% of the mass of the pulverized pyrolytic carbon. The residence time of the pulverized pyrolytic carbon in the liquid-phase coating machine is 20min. Afterward, nitrogen gas is introduced into the liquid-phase coating machine for cooling. Once cooled to room temperature, pyrolytic carbon with a modifier coating layer is obtained, which is the hard carbon precursor.

[0077] Subsequently, the hard carbon precursor was added to a carbonization furnace and heated to 1200°C in a nitrogen atmosphere at a heating rate of 10°C / min. The material was then carbonized at 1200°C for 2 hours to obtain petroleum-based hard carbon material.

[0078] Following the testing method described above, the specific surface area of ​​the petroleum-based hard carbon material in this embodiment was found to be 5 m². 2 / g, interlayer spacing of crystals is 0.382nm, and tap density is 0.76g / cm³. 3 .

[0079] After assembling the petroleum-based hard carbon material of this embodiment into a sodium-ion button half-cell according to the method described above, a constant current charge-discharge experiment was conducted, and the initial sodium removal capacity (also known as the initial reversible specific capacity) was found to be 340 mAh / g, and the initial coulombic efficiency was 90%.

[0080] Example 2

[0081] This embodiment provides a petroleum-based hard carbon material, the preparation method of which includes the following steps:

[0082] Furfural extract oil (based on the total mass of the furfural extract oil as 100%, containing 19% saturated fraction, 75% aromatic fraction, 6% gum content, 0% asphaltenes content, 0.2% sulfur content, 0.2% nitrogen content, and 13% residual carbon content; and with an ash content of 300 ppm) is desolidified by an electric field to reduce the ash content to 10 ppm, thus obtaining the desolidified furfural extract oil.

[0083] The vacuum residue (based on 100% of its total mass, containing 22% saturated matter, 58% aromatics, 16% gum, 4% asphaltenes, 3.2% sulfur, 0.85% nitrogen, and 11% residual carbon; and with an ash content of 1500 ppm) was centrifuged to remove excess ash, resulting in an ash content of 30 ppm, thus obtaining the removed vacuum residue.

[0084] Then, the deconsolidated furfural extract and the deconsolidated vacuum residue were distilled separately to obtain pretreated furfural extract and pretreated vacuum residue.

[0085] The pretreated furfural extract oil has a distillation range of 350–580℃ and a density (20℃) of 1.05 g / cm³. 3 Based on the total mass of the pretreated furfural extract oil as 100%, the saturated content is 21%, the aromatic content is 76%, the gum content is 3%, the asphaltenes content is 0%, the sulfur content is 0.2%, the nitrogen content is 0.2%, the residual carbon content is 12%, and the ash content is 20 ppm.

[0086] The pretreated vacuum residue has a distillation range of 370–630℃ and a density (20℃) of 1.02 g / cm³. 3 Based on the total mass of the pretreated vacuum residue as 100%, the content of saturated fraction is 23%, aromatic fraction is 60%, gum content is 14%, asphaltenes content is 3%, sulfur content is 0.8%, nitrogen content is 0.3%, carbon residue is 10%, and ash content is 50 ppm.

[0087] Subsequently, the pretreated furfural extract oil and pretreated vacuum residue oil were mixed online at a mass ratio of 3:2. The online mixing temperature was 90℃ and the linear velocity was 0.5m / s to obtain a mixed pyrolysis oil. The distillation range of this mixed pyrolysis oil was 350–630℃, and its density (20℃) was 1.04 g / cm³. 3Based on the total mass of the mixed pyrolysis oil as 100%, the saturated content is 22%, the aromatic content is 70%, the gum content is 7.4%, the asphaltenes content is 1.2%, the sulfur content is 0.44%, the nitrogen content is 0.24%, the residual carbon content is 11%, and the ash content is 33 ppm.

[0088] Then, the mixed pyrolysis oil is continuously fed into a fluidized bed reactor connected to a microwave generator. The microwave generator causes the mixed pyrolysis oil to undergo microwave pyrolysis, yielding pyrolysis char and oil gas. The pyrolysis char is in a fluidized state. The flow rate of the mixed pyrolysis oil into the fluidized bed reactor is 2 kg / h, the frequency of the microwave generator is controlled at 2350 MHz and the power at 3 kW, the residence time of the mixed pyrolysis oil in the fluidized bed reactor is 3 seconds, and the temperature in the fluidized bed reactor is controlled at 560°C.

[0089] After the oil and gas flow out from the top of the fluidized reactor, they are first cooled to collect the non-condensable gas; then the remaining part is distilled to obtain gasoline, diesel and wax oil.

[0090] Subsequently, the pyrolytic carbon is fed into a reformer for reforming. The temperature in the reformer is controlled at 900°C by electromagnetic heating, and carbon dioxide is introduced at a flow rate of 0.5 L / h per 1 kg of pyrolytic carbon. The reforming time is 2 hours, resulting in reformed pyrolytic carbon. At the same time, the oil and gas separated from the pyrolytic carbon and the unreacted components can be returned to the fluidized reactor for further pyrolysis and / or oil and gas recovery.

[0091] The modified pyrolytic carbon was then pulverized using a mechanical grinder to obtain pulverized pyrolytic carbon with a D10 particle size of 2.1 μm, a D50 particle size of 9.5 μm, and a D90 particle size of 15.8 μm.

[0092] Then, the pulverized pyrolytic carbon is added to a liquid-phase coating machine. The wax oil obtained by distillation of the oil and gas produced by the pyrolysis is used as a modifier. This wax oil has a distillation range of 360–530℃ and a density (20℃) of 1.105 g / cm³. 3The wax oil, with a total mass of 100%, contains 7% saturated fraction, 78% aromatic fraction, and 15% gum. The wax oil is heated to 90°C and then pressurized to 2 MPa using a high-pressure pump. The wax oil is then sprayed onto the pulverized pyrolytic carbon being stirred using a 0.7 mm diameter nozzle. The stirring speed of the liquid-phase coating machine is 850 r / min, and the amount of wax oil used is 8% of the mass of the pulverized pyrolytic carbon. The residence time of the pulverized pyrolytic carbon in the liquid-phase coating machine is 30 min. Nitrogen gas is then introduced into the liquid-phase coating machine for cooling. After cooling to room temperature, pyrolytic carbon with a modifier coating layer is obtained, which is the hard carbon precursor. The hard carbon precursor is then added to a carbonization furnace and heated to 1300°C at a rate of 1°C / min in a nitrogen atmosphere. Carbonization is carried out at 1300°C for 1 hour to obtain petroleum-based hard carbon material.

[0093] Following the testing method described above, the specific surface area of ​​the petroleum-based hard carbon material in this embodiment was determined to be 7 m². 2 / g, interlayer spacing of crystals is 0.384nm, and tap density is 0.77g / cm³. 3 .

[0094] After assembling the petroleum-based hard carbon material of this embodiment into a sodium-ion button half-cell according to the method described above, a constant current charge-discharge experiment was conducted, and the initial sodium removal capacity was 345 mAh / g, and the initial coulombic efficiency was 89%.

[0095] Example 3

[0096] This embodiment provides a petroleum-based hard carbon material, the preparation method of which includes the following steps:

[0097] The pretreated catalytic cracking slurry from Example 1 and the pretreated vacuum residue from Example 2 were mixed online at a mass ratio of 1:3. The online mixing temperature was 90°C and the linear velocity was 0.6 m / s to obtain a mixed pyrolysis oil. The mixed pyrolysis oil had a distillation range of 350–630°C and a density (20°C) of 1.03 g / cm³. 3 Based on the total mass of the mixed pyrolysis oil as 100%, the saturated content is 22%, the aromatic content is 62%, the gum content is 14%, the asphaltenes content is 2.5%, the sulfur content is 0.73%, the nitrogen content is 0.28%, the residual carbon content is 9.5%, and the ash content is 50 ppm.

[0098] Then, the mixed pyrolysis oil is continuously fed into a fluidized bed reactor connected to a microwave generator. The microwave generator causes the mixed pyrolysis oil to undergo microwave pyrolysis, yielding pyrolysis char and oil gas. The pyrolysis char is in a fluidized state. The flow rate of the mixed pyrolysis oil into the fluidized bed reactor is 2 kg / h, the frequency of the microwave generator is controlled at 2550 MHz and the power at 5 kW, the residence time of the mixed pyrolysis oil in the fluidized bed reactor is 4 seconds, and the temperature in the fluidized bed reactor is controlled at 580°C.

[0099] After the oil and gas flow out from the top of the fluidized reactor, they are first cooled to collect the non-condensable gas; then the remaining part is distilled to obtain gasoline, diesel and wax oil.

[0100] Subsequently, the pyrolytic carbon is fed into a reformer for reforming. The temperature in the reformer is controlled at 800°C by electromagnetic heating, and carbon dioxide is introduced at a flow rate of 1 L / h per 1 kg of pyrolytic carbon. The reforming time is 4 hours, resulting in reformed pyrolytic carbon. At the same time, the oil and gas separated from the pyrolytic carbon and the unreacted components can be returned to the fluidized reactor for further pyrolysis and / or oil and gas recovery.

[0101] The modified pyrolytic carbon was then pulverized using a mechanical grinder to obtain pulverized pyrolytic carbon with a D10 particle size of 2.5 μm, a D50 particle size of 8.6 μm, and a D90 particle size of 15.1 μm.

[0102] Then, the pulverized pyrolytic carbon is added to a liquid-phase coating machine. The wax oil obtained by distillation of the oil and gas produced by the pyrolysis is used as a modifier. This wax oil has a distillation range of 400–500℃ and a density (20℃) of 1.105 g / cm³. 3 The wax oil, with a total mass of 100%, contains 5% saturated fraction, 88% aromatic fraction, and 7% gum content. The wax oil is heated to 100°C and then pressurized to 3 MPa using a high-pressure pump. The wax oil is then sprayed onto the pulverized pyrolytic carbon being stirred using a 0.9 mm diameter nozzle. The stirring speed of the liquid-phase coating machine is 980 r / min, and the amount of wax oil used is 3% of the mass of the pulverized pyrolytic carbon. The residence time of the pulverized pyrolytic carbon in the liquid-phase coating machine is 30 min. Nitrogen gas is then introduced into the liquid-phase coating machine for cooling. After cooling to room temperature, pyrolytic carbon with a modifier coating layer is obtained, which is the hard carbon precursor.

[0103] Subsequently, the hard carbon precursor was added to a carbonization furnace and heated to 1500°C in a nitrogen atmosphere at a heating rate of 5°C / min. The carbonization was then carried out at 1200°C for 2 hours to obtain petroleum-based hard carbon material.

[0104] Following the testing method described above, the specific surface area of ​​the petroleum-based hard carbon material in this embodiment was found to be 4 m². 2 / g, interlayer spacing of crystals is 0.382nm, and tap density is 0.73g / cm³. 3 .

[0105] After assembling the petroleum-based hard carbon material of this embodiment into a sodium-ion button half-cell according to the method described above, a constant current charge-discharge experiment was conducted, and the initial sodium removal capacity was 349 mAh / g, and the initial coulombic efficiency was 90%.

[0106] Example 4

[0107] This embodiment provides a preparation system for petroleum-based hard carbon materials, which is used to realize the preparation methods of petroleum-based hard carbon materials in Examples 1 to 3. As shown in Figure 1, the preparation system includes: a desolidification device 1, a component adjustment device 2, an online mixer 3, a fluidized reactor 4, a microwave generator 5, a distillation column 6, a modifier 7, a pulverizing device 8, a liquid phase coating machine 9, a heating device 10, a pressurizing device 11, and a carbonization furnace 12.

[0108] The number of solidification devices 1 and component adjustment devices 2 are two or more, the outlets of the two solidification devices 1 are respectively connected to the inlets of the two component adjustment devices 2, the outlets of the two component adjustment devices 2 are connected to the inlet of the online mixer 3, and the outlet of the online mixer 3 is connected to the inlet of the fluidized reactor 4.

[0109] The fluidized reactor 4 is connected to a microwave generator 5, which is used to provide microwave heating to the fluidized reactor 4;

[0110] The oil and gas outlet of the fluidized reactor 4 is connected to the inlet of the distillation column 6, which is equipped with at least a gasoline outlet, a diesel outlet, and a wax oil outlet.

[0111] The pyrolysis carbon outlet of the fluidized reactor 4 is connected to the pyrolysis carbon inlet of the reformer 7; the reformer 7 is also provided with a structure adjustment gas inlet, which is used to provide one or two of water vapor and carbon dioxide to the reformer 7; the reformer 7 is also provided with an oil and gas and unreacted component outlet, which is connected to the fluidized reactor 4, so as to return the oil and gas and unreacted components separated from the pyrolysis carbon to the fluidized reactor 4 for further pyrolysis and / or recovery of oil and gas;

[0112] The outlet of the modified pyrolytic carbon of the modifier 7 is connected to the inlet of the pulverizing device 8, and the outlet of the pulverizing device 8 is connected to the inlet of the pulverized pyrolytic carbon of the liquid phase coating machine 9.

[0113] The wax oil outlet of the distillation column 6 is connected to the inlet of the heating device 10, the outlet of the heating device 10 is connected to the inlet of the pressurizing device 11, and the outlet of the pressurizing device 11 is connected to the modifier inlet of the liquid phase coating machine 9, for providing the heated and pressurized modifier to the liquid phase coating machine 9.

[0114] The hard carbon precursor outlet of the liquid phase coating machine 9 is connected to the inlet of the carbonization furnace 12, and the outlet of the carbonization furnace 12 produces petroleum-based hard carbon material.

[0115] In this embodiment, the deconsolidation device 1 includes one or more of the following: sedimentation deconsolidation device, centrifugal deconsolidation device, and electric field deconsolidation device. The component adjustment device 2 includes one or more of the following: distillation column, extraction column, and extraction column. The microwave generator 5 includes at least a control unit 501 and a modulation unit 502 for controlling the frequency and power of the microwave. The modifier 7 is a reactor with an electromagnetic heating unit. The pulverizing device 8 includes one or more of the following: an air jet mill and a mechanical grinder. The liquid phase coating machine 9 includes at least a spray head and a stirring unit; the diameter of the spray head is 0.5-1 mm, used for spraying the modifier; the stirring unit is used for stirring the pulverized pyrolytic carbon in the liquid phase coating machine 9. The heating device 10 can be a conventional tubular heater, etc., and the pressurization device 11 can be a conventional booster pump, etc.

[0116] Comparative Example 1

[0117] This comparative example provides a petroleum-based hard carbon material, the preparation method of which includes the following steps:

[0118] The mixed pyrolysis oil used in Example 1 has a distillation range of 350–610°C and a density (20°C) of 1.105 g / cm³. 3 Based on the total mass of the mixed pyrolysis oil as 100%, the saturated content is 12%, the aromatic content is 69%, the resin content is 15%, the asphaltene content is 4%, the sulfur content is 0.2%, the nitrogen content is 0.1%, the residual carbon content is 13%, and the ash content is 35 ppm. The mixed pyrolysis oil is added to a high-pressure reactor for intermittent pyrolysis reaction. The temperature in the high-pressure reactor is controlled at 520℃ and the pressure is 0.5MPa. Pyrolysis is carried out for 6 hours to obtain pyrolysis carbon.

[0119] Subsequently, the pyrolytic carbon is introduced into a reformer for reforming. The temperature in the reformer is controlled at 1000℃ by electromagnetic heating, and steam is introduced. The steam flow rate is 0.5L / h per 1kg of pyrolytic carbon, and the reforming time is 1 hour, to obtain the reformed pyrolytic carbon.

[0120] The modified pyrolytic carbon was then pulverized using a mechanical grinder to obtain pulverized pyrolytic carbon with a D10 particle size of 2.5 μm, a D50 particle size of 8.6 μm, and a D90 particle size of 15.1 μm.

[0121] Then, the pulverized pyrolytic carbon is added to a liquid phase coating machine for modification coating. The wax oil in Example 1 is used as the modifier, and the coating process is the same as in Example 1, to obtain pyrolytic carbon with a modifier coating layer. Due to the difference in the preparation process, a soft carbon precursor is obtained.

[0122] Subsequently, the soft carbon precursor was added to a carbonization furnace and heated to 1200°C in a nitrogen atmosphere at a heating rate of 10°C / min. The carbonization was carried out at 1200°C for 2 hours to obtain petroleum-based soft carbon material.

[0123] Following the methods described above, the specific surface area of ​​the petroleum-based hard carbon material in this comparative example was found to be 4 m². 2 / g, interlayer spacing of crystals is 0.3448nm, and tap density is 0.63g / cm³. 3 .

[0124] After assembling the petroleum-based hard carbon material of this comparative example into a sodium-ion button half-cell according to the method described above, a constant current charge-discharge experiment was conducted, and the initial sodium removal capacity was 156 mAh / g, and the initial coulombic efficiency was 65%.

[0125] Comparative Example 2

[0126] This comparative example provides a petroleum-based hard carbon material, the preparation method of which is basically the same as that of Example 1, except that: no desolidification and component adjustment are performed; instead, the catalytic cracking slurry oil and ethylene tar hydrogenated wax oil fraction from Example 1 are mixed online at a mass ratio of 1:3, the online mixing temperature is 80℃ and the linear velocity is 0.7m / s, resulting in a mixed pyrolysis oil; the boiling range of this mixed pyrolysis oil is 350-610℃, and the density (20℃) is 1.05g / cm³. 3 Based on the total mass of the mixed pyrolysis oil (100%), the saturated content was 11%, the aromatic content was 67%, the gum content was 17%, the asphaltenes content was 5%, the sulfur content was 0.26%, the nitrogen content was 0.15%, the residual carbon content was 16%, and the ash content was 950 ppm. The subsequent pyrolysis, modification, pulverization, coating, and carbonization conditions were the same as in Example 1, and the wax oil from Example 1 was used for coating to obtain petroleum-based hard carbon material. Tests conducted according to the methods described above showed that the specific surface area of ​​the petroleum-based hard carbon material in this comparative example was 8 m². 2 / g, interlayer spacing of crystals is 0.373nm, and tap density is 0.63g / cm³. 3 .

[0127] After assembling the petroleum-based hard carbon material of this comparative example into a sodium-ion button half-cell according to the method described above, a constant current charge-discharge experiment was conducted, and the initial sodium removal capacity was 254 mAh / g, and the initial coulombic efficiency was 68%.

[0128] Comparative Example 3

[0129] This comparative example provides a petroleum-based hard carbon material, the preparation method of which is basically the same as that of Example 1, except that: no modifier coating is performed, and the pulverized pyrolytic carbon in Example 1 is directly carbonized under the same carbonization conditions as in Example 1 to obtain the petroleum-based hard carbon material.

[0130] Following the methods described above, the specific surface area of ​​the petroleum-based hard carbon material in this comparative example was found to be 35 m². 2 / g, interlayer spacing of crystals is 0.376nm, and tap density is 0.69g / cm³. 3 .

[0131] After assembling the petroleum-based hard carbon material of this comparative example into a sodium-ion button half-cell according to the method described above, a constant current charge-discharge experiment was conducted, and the initial sodium removal capacity was 262 mAh / g, and the initial coulombic efficiency was 68%.

Claims

1. A method for preparing a petroleum-based hard carbon material, comprising the following steps: (1) Desolidify and adjust the composition of heavy petroleum oil to obtain pretreated heavy petroleum oil; selectively mix two or more of the pretreated heavy petroleum oils to obtain mixed pyrolysis oil; (2) microwave pyrolyze the pretreated heavy petroleum oil or the mixed pyrolysis oil in a fluidized bed reactor to obtain pyrolysis carbon; (3) modify the pyrolysis carbon in the presence of a structure-adjusting gas to obtain modified pyrolysis carbon; (4) pulverize the modified pyrolysis carbon to obtain pulverized pyrolysis carbon; coat the pulverized pyrolysis carbon with a modifier to obtain a hard carbon precursor; (5) carbonize the hard carbon precursor to obtain the petroleum-based hard carbon material.

2. The method for preparing petroleum-based hard carbon material according to claim 1, wherein, In step (1), the ash content of the deconsolidated heavy petroleum oil is 10 to 50 ppm.

3. The method for preparing petroleum-based hard carbon material according to claim 1, wherein, In step (1), the component adjustment includes one or more of distillation, solvent extraction and solvent extraction.

4. The method for preparing petroleum-based hard carbon material according to claim 1, wherein, In step (1), the pretreated heavy petroleum oil has a distillation range of 350–700°C and a density of 0.95–1.15 g / cm³. 3 Based on the total mass of the pretreated heavy petroleum oil as 100%, the pretreated heavy petroleum oil has a saturated content of 10-25%, an aromatic content of 50-80%, a gum content of 1-20%, an asphaltenes content of 0-10%, a sulfur content of 0.5-2%, a nitrogen content of 0.05-0.7%, and a carbon residue content of 5-15%.

5. The method for preparing petroleum-based hard carbon material according to claim 1, wherein, In step (1), the two or more pretreated heavy petroleum oils are mixed online, and the online mixing temperature is 80-120°C and the linear velocity is 0.5-0.7 m / s.

6. The method for preparing petroleum-based hard carbon material according to claim 1, wherein, In step (1), the mixed pyrolysis oil has a distillation range of 350–700°C and a density of 1.01–1.12 g / cm³. 3 Based on the total mass of the mixed pyrolysis oil as 100%, the mixed pyrolysis oil has a saturated content of 10-23%, an aromatic content of 55-80%, a resin content of 5-25%, an asphaltenes content of 1-6%, a sulfur content of 0.1-2%, a nitrogen content of 0.08-0.7%, and a residual carbon content of 8-15%.

7. The method for preparing petroleum-based hard carbon material according to claim 1, wherein, Step (2) includes: introducing the pretreated heavy petroleum oil or the mixed pyrolysis oil into a fluidized bed reactor, the fluidized bed reactor being connected to a microwave generator, and the pretreated heavy petroleum oil or the mixed pyrolysis oil being subjected to microwave pyrolysis by the microwave generator to obtain pyrolysis char and oil gas, the pyrolysis char being in a fluidized state; wherein, the flow rate of the pretreated heavy petroleum oil or the mixed pyrolysis oil entering the fluidized bed reactor is 1-2 kg / h, the frequency of the microwave generator is controlled at 2350-2550 MHz and the power at 2-5 KW, the residence time of the pretreated heavy petroleum oil or the mixed pyrolysis oil in the fluidized bed reactor is 2-4 seconds, and the temperature in the fluidized bed reactor is controlled at 530-580℃.

8. The method for preparing petroleum-based hard carbon material according to claim 7, wherein, Step (2) further includes: distilling the oil and gas at least to obtain gasoline, diesel and wax oil.

9. The method for preparing petroleum-based hard carbon material according to claim 1, wherein, In step (3), the structure adjustment gas includes one or both of water vapor and carbon dioxide, the temperature of the modification is 800-1000℃ and the time is 1-4 hours, and the flow rate of the structure adjustment gas is 0.5-1L / h per 1kg of the pyrolytic carbon.

10. The method for preparing petroleum-based hard carbon material according to claim 1, wherein, In step (4), the pulverized pyrolytic carbon has a D10 particle size of 2-3 μm, a D50 particle size of 7-10 μm, and a D90 particle size of 14-16 μm.

11. The method for preparing petroleum-based hard carbon material according to claim 1, wherein, In step (4), the modifier includes wax oil; the wax oil has a distillation range of 360–550°C and a density of 1.10–1.15 g / cm³. 3 Based on the total mass of the wax oil (100%), the wax oil has a saturated content of 5-12%, an aromatic content of 68-90%, and a gum content of 5-20%.

12. The method for preparing petroleum-based hard carbon material according to claim 8, wherein, In step (4), the modifier includes wax oil; the wax oil is the wax oil obtained by distillation of the oil and gas in step (2).

13. The method for preparing petroleum-based hard carbon material according to claim 1, wherein, In step (4), the coating includes: heating the modifier to 50-100°C, then pressurizing it to 2-3 MPa, and then spraying the modifier onto the pulverized pyrolytic carbon being stirred through a spray nozzle. The diameter of the spray nozzle is 0.5-1 mm, the stirring speed is 500-1000 r / min, and the amount of the modifier is 1-10% of the mass of the pulverized pyrolytic carbon.

14. The method for preparing petroleum-based hard carbon material according to claim 1, wherein, In step (5), the carbonization temperature is 1200-1600℃, the heating rate is 1-10℃ / min, and the carbonization time is 1-5 hours.

15. A petroleum-based hard carbon material, which is prepared by the method for preparing petroleum-based hard carbon material according to any one of claims 1-14.

16. The petroleum-based hard carbon material according to claim 15, wherein, The specific surface area of ​​the petroleum-based hard carbon material is 4-7 m². 2 / g, interlayer spacing of crystals is 0.378–0.385 nm, and tap density is 0.7–0.8 g / cm³. 3 .

17. A system for preparing a petroleum-based hard carbon material, used to implement the method for preparing the petroleum-based hard carbon material according to any one of claims 1-14, the system comprising: The system includes a desolidification device, a component adjustment device, a fluidized bed reactor, a microwave generator, a modifier, a pulverizing device, a liquid-phase coating machine, and a carbonization furnace, optionally including an online mixer; wherein the number of the desolidification device and the component adjustment device is one or more; the outlet of one desolidification device is connected to the inlet of one component adjustment device, and the outlet of one component adjustment device is connected to the inlet of the fluidized bed reactor; or, the outlets of two or more desolidification devices are respectively connected to the inlets of two or more component adjustment devices, the outlets of two or more component adjustment devices are connected to the inlet of the online mixer, and the outlet of the online mixer is connected to the inlet of the fluidized bed reactor; the fluidized bed reactor is connected to the microwave generator for providing microwave heating to the fluidized bed reactor; the pyrolytic carbon outlet of the fluidized bed reactor is connected to the pyrolytic carbon inlet of the modifier, the modifier is also provided with a structure adjustment gas inlet, and the modified pyrolytic carbon outlet of the modifier is sequentially connected to the pulverizing device, the liquid-phase coating machine, and the carbonization furnace.

18. The preparation system for petroleum-based hard carbon materials according to claim 17, wherein, The desolidification device includes one or more of the following: sedimentation desolidification device, centrifugal desolidification device, and electric field desolidification device.

19. The preparation system for petroleum-based hard carbon materials according to claim 17, wherein, The component adjustment device includes one or more of the following: distillation column, extraction column, and extraction column.

20. The preparation system for petroleum-based hard carbon materials according to claim 17, wherein, The preparation system further includes a distillation column, and the fluidized reactor is also provided with an oil and gas outlet, which is connected to the inlet of the distillation column. The distillation column is provided with at least a gasoline outlet, a diesel outlet, and a wax oil outlet.

21. The preparation system for petroleum-based hard carbon materials according to claim 17, wherein, The reformer is also provided with oil and gas outlets and unreacted component outlets, which are connected to the fluidized reactor to return the oil and gas and unreacted components separated from the pyrolytic carbon to the fluidized reactor for further pyrolysis and / or oil and gas recovery.

22. The preparation system for petroleum-based hard carbon materials according to claim 20, wherein, The preparation system further includes a heating device and a pressurizing device. The wax oil outlet of the distillation column is connected to the inlet of the heating device, the outlet of the heating device is connected to the inlet of the pressurizing device, and the outlet of the pressurizing device is connected to the liquid phase coating machine for providing the heated and pressurized modifier to the liquid phase coating machine.

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