Method for reforming carbonaceous structure of low-quality petroleum coke

Abstract

The application discloses a method for reforming carbonaceous structure of inferior petroleum coke. The method comprises the following steps: (1) mixing and reacting inferior petroleum coke raw materials with a gaseous oxidant, and washing and drying the reaction product to obtain a dry product; (2) contacting the dry product obtained in the step (1) with a compound modifier, and reacting under an inert atmosphere, and washing and drying to obtain modified petroleum coke. The method can adjust the carbonaceous structure of the petroleum coke to a greater extent under the premise of mild desulfurization, so that the lithium battery negative electrode performance of the petroleum coke is greatly improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of carbon material preparation, and particularly relates to a modification method of inferior petroleum coke. BACKGROUND

[0002] Petroleum coke is obtained by cracking and carbonization of petroleum-based raw materials such as catalytic cracking slurry oil, ethylene tar, refinery slop oil and dregs, etc. in the process of delayed coking or fluidized coking, with vacuum residue as the main raw material. The intrinsic structure of petroleum coke is dense, and the main element is carbon, accounting for ≥85%, and the hydrogen element accounts for about 10%, and also contains other heteroatoms such as nitrogen, sulfur, iron, zinc, cadmium, etc. Petroleum coke can be divided into three types according to its appearance and properties: sponge coke commonly used as fuel, reducing agent, negative electrode material and prebaked anode; pellet coke used for fuel; needle coke used for producing graphite electrodes and lithium battery negative electrode materials. Among them, the lithium ion negative electrode material is a new way of high value-added utilization of petroleum coke in recent years. The amount of lithium ion negative electrode material in 2022 is about 1 million tons. Due to the influence of graphitization process and carbonaceous structure of petroleum coke, the sulfur content in petroleum coke is required to be less than 1.5%.

[0003] Petroleum coke, especially ordinary petroleum coke, as a lithium battery negative electrode material, is the focus of attention of refineries, major negative electrode and battery enterprises. Ordinary petroleum coke is mainly in the form of mosaic structure, and has a lower graphitization tendency than needle coke. Therefore, the specific capacity, first coulombic efficiency and tap density of ordinary petroleum coke as a lithium battery negative electrode material are lower than those of needle coke, and it is more suitable for energy storage and markets with demand for charge and discharge rate. However, as a lithium battery negative electrode material, ordinary petroleum coke has relatively strict requirements for its sulfur content, which is generally required to be less than 1.5%, and it also requires ordinary petroleum coke to have a better carbonaceous structure to make it more suitable for lithium battery negative electrode applications.

[0004] The existing petroleum coke carbonaceous structure reform work is mainly focused on petroleum coke desulfurization, because some types of sulfides can hinder the rearrangement of the carbonaceous structure of petroleum coke. However, in addition to sulfides, some non-ideal carbonaceous structures inside petroleum coke also have a great influence on the subsequent high value-added application of petroleum coke. Therefore, in addition to desulfurization, the carbonaceous structure of petroleum coke should also be effectively controlled.

[0005] CN115490227A discloses a desulfurization and modification method of medium-high sulfur petroleum coke. The method mixes medium-high sulfur petroleum coke and a composite treatment agent, and calcines in the presence of ammonia and / or water vapor to perform desulfurization and modification, and obtains a treated material. The method improves the control of harmful sulfur in medium-high sulfur petroleum coke under the joint control of the composite treatment agent and the calcination atmosphere and temperature, so as to improve the electrochemical performance of the subsequently prepared graphite negative electrode. SUMMARY

[0006] In view of the deficiencies in the prior art, the present application provides a method for reforming carbon structure of inferior petroleum coke. The method can adjust the carbon structure of petroleum coke to a greater extent under the premise of mild desulfurization, so that the lithium battery negative electrode performance of the petroleum coke is greatly improved.

[0007] The present application provides a method for reforming carbon structure of inferior petroleum coke, comprising:

[0008] (1) mixing and reacting inferior petroleum coke raw material with gaseous oxidizing agent, washing and drying the reaction product to obtain dry product;

[0009] (2) contacting the dry product obtained in step (1) with a compounded modifier and reacting under inert atmosphere, washing and drying to obtain modified petroleum coke.

[0010] Further, in step (1), the particle size of the petroleum coke is 1-200 mesh, preferably 5-20 mesh. The inferior petroleum coke is high-sulfur petroleum coke, and further, the sulfur content in the petroleum coke is 0.3%-15%. The Sd1 / Sg in the inferior petroleum coke is 2.0 or less, preferably 1.8 or less, and the Sd3 / Sg is 1.0 or more.

[0011] Further, in step (1), the gaseous oxidizing agent is nitrogen oxide, selected from one or more of NO, NO2, N2O3 and N2O4, preferably N2O4. The gaseous oxidizing agent can contain a carrier gas, which can be one or more of nitrogen and inert gas, preferably nitrogen. The volume content of nitrogen oxide in the gaseous oxidizing agent is 50%-100%.

[0012] Further, in step (1), the mixing and reacting of the inferior petroleum coke raw material with the gaseous oxidizing agent is carried out in a fixed bed reactor.

[0013] Further, in step (1), the mixing and reacting of the inferior petroleum coke with the gaseous oxidizing agent is carried out under the following conditions: temperature 20-120℃, preferably 30-70℃; pressure 1-5atm, preferably 1-2atm; volume space velocity of gaseous oxidizing agent 50-2000h -1 , preferably 150-1000h -1 , reaction time 0.5-12h, preferably 6-10h.

[0014] Further, in step (1), the washing can be water washing until neutral. The drying temperature is 60-150℃, preferably 80-120℃, and the drying time is 2-8h, preferably 4-6h.

[0015] Further, in step (2), the complex modifier comprises alkali, sodium salt and transition metal salt, wherein the mass ratio of alkali:sodium salt:transition metal salt is (0.1-0.5):(8-9):(0.5-1.9), preferably (0.3-0.5):9:(0.5-0.7).

[0016] Further, in step (2), the alkali in the complex modifier is one or both of potassium hydroxide and sodium hydroxide. The sodium salt is one or both of sodium carbonate and sodium acetate. The transition metal in the transition metal salt is one or more of iron, cobalt, nickel and manganese, and the salt can be at least one of nitrate, carbonate and chloride.

[0017] Further, in step (2), the mass ratio of the complex modifier to the dry material obtained in step (1) is 0.1-1:1, preferably 0.3-0.6:1.

[0018] Further, in step (2), the inert atmosphere can be one or more of nitrogen and inert gas, preferably nitrogen.

[0019] Further, in step (2), the reaction temperature of the complex modifier and the petroleum coke is 500-1200℃, preferably 700-900℃.

[0020] Further, in step (2), the reaction time of the complex modifier and the petroleum coke is 0.1-6.0h, preferably 0.3-2.0h.

[0021] Further, in step (2), the washing can be water washing until neutral. The drying temperature is 60-150℃, preferably 80-120℃, and the drying time is 2-8h, preferably 4-6h.

[0022] Further, compared with the petroleum coke raw material, the specific capacity of the modified petroleum coke is increased by 25%-70%, preferably 45%-70%, such as but not limited to 45%, 55%, 60%, 65%, 70% and the like. The specific capacity of the low-quality petroleum coke raw material is 290mAh / g or less, generally 200-240mAh / g.

[0023] Further, compared with the petroleum coke raw material, the Sd1 / Sg of the modified petroleum coke is increased by 10%-60%, preferably 25%-40%.

[0024] The application also provides a modified petroleum coke prepared by the above method.

[0025] Further, the Sd1 / Sg of the modified petroleum coke is greater than 2.0, and the Sd3 / Sg is 0.8 or less.

[0026] Compared with the prior art, the method has the following advantages:

[0027] 1、 the method of the application uses inferior petroleum coke as raw material, and uses oxidizing gas, especially nitrogen oxide to treat the petroleum coke, so that the interlayer spacing of the petroleum coke graphite sheet is obviously increased, and then the petroleum coke is treated with a specific compound modifier, so that mass transfer and diffusion can be carried out between the petroleum coke graphite sheet layers, the carbon structure of the large particle size petroleum coke is reformed, and the performance of the petroleum coke lithium negative electrode can be obviously improved under relatively moderate conditions.

[0028] 2、 the method of the application can maximize the maintenance of the petroleum coke body structure without damage, and can target regulate the carbon structure in the petroleum coke, so as to improve the performance of the petroleum coke lithium negative electrode. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 Raman spectrum of petroleum coke A used in example 1;

[0030] Figure 2 Raman spectrum of modified petroleum coke in example 1;

[0031] Figure 3 Raman spectrum of modified petroleum coke in comparative example 1. DETAILED DESCRIPTION

[0032] The application will be described in detail below in combination with specific examples, and it is necessary to point out here that the following examples are only used to further illustrate the application, and cannot be understood as limiting the protection scope of the application,

[0033] In the application, the carbon structure of the petroleum coke is characterized by Raman spectrum. The Raman spectrum is performed on a HR800 type confocal microscopic laser Raman spectrometer of HORIBA Jobin Yvon Company in France, the emission laser wavelength is 532nm, the power is 10mW, the spectral resolution is 0.65cm -1 , the grating is 1 800g / mm, and the Raman shift range is 0-2 000cm -1 . Among them, the peak position of d1 is near 1350cm -1 , the peak position of d2 is near 1620cm -1 , the peak position of d3 is near 1500cm -1 , the peak position of d4 is near 1200cm -1 , and the peak position of g is near 1580cm -1Nearby, Sd1 / Sg, Sd2 / Sg, Sd3 / Sg, Sd4 / Sg respectively represent the peak area ratio of two peaks. Among them, the g peak represents the ordered graphite structure in the petroleum coke, the d1 peak represents the disordered graphite structure in the petroleum coke; the d2 peak is the graphite structure mixed with ordered and disordered structures in the petroleum coke, the d3 peak represents the amorphous carbon structure in the petroleum coke; and the d4 peak represents the carbon structure in the petroleum coke which tends to be polyene.

[0034] In the present application, the petroleum coke before and after modification is pulverized by gas flow to D 50 10-20 microns, and after graphitization, the lithium battery negative electrode performance test is carried out according to the standard of GB / T24533-2019 lithium ion battery graphite negative electrode material, that is, the specific capacity.

[0035] The properties of the inferior petroleum coke used in the examples and comparative examples of the present application are shown in Table 1.

[0036] Table 1 Properties of different petroleum coke raw materials

[0037]

[0038] Example 1

[0039] 50g of inferior petroleum coke A with a particle size of 5 mesh is loaded into a fixed bed reactor, the reaction temperature is 70℃, the reactor pressure is 2atm, 99.99vol.%concentration of N2O4 is used, the volume space velocity is 1000h -1 -1, and the oxidation treatment time is 8h. Then the oxidized product is washed with water until it is neutral, and then dried at 120℃ for 6h.

[0040] The composition of the compounded modifier is sodium hydroxide: sodium carbonate: nickel carbonate, wherein the mass ratio of sodium hydroxide: sodium carbonate: nickel carbonate is 0.5:9:0.5, the mass ratio of compounded modifier to petroleum coke is 0.5:1, the reaction temperature is 900℃ under nitrogen atmosphere, and the reaction time is 0.3h. The reaction product is washed with distilled water until it is neutral, dried at 120℃ for 6h, and the product is labeled as P-1.

[0041] Example 2

[0042] 50g of inferior petroleum coke A with a particle size of 20 mesh is loaded into a fixed bed reactor, the reaction temperature is 70℃, the reactor pressure is 1atm, 99.99vol.%concentration of N2O4 is used, the volume space velocity is 500h -1 -1, and the oxidation treatment time is 10h. Then the oxidized product is washed with water until it is neutral, and then dried at 120℃ for 6h.

[0043] The composition of the complex modifier used is potassium hydroxide: sodium acetate: iron nitrate, wherein the mass ratio of potassium hydroxide: sodium acetate: iron nitrate is 0.3:9:0.7, the mass ratio of complex modifier to petroleum coke is 0.3:1, the reaction temperature is 700°C under nitrogen atmosphere, and the reaction time is 1 h. The reaction product is washed with distilled water until it is neutral, and then dried at 120°C for 6 h to obtain the product marked as P-2.

[0044] Example 3

[0045] 50 g of low-quality petroleum coke A with a particle size of 5 mesh is loaded into a fixed bed reactor, the reaction temperature is 70°C, the reactor pressure is 2 atm, N2O4 with a concentration of 99.99 vol.% is used, the volume space velocity is 1000 h-1, and the oxidation treatment time is 8 h. Then, the oxidized product is washed with water until it is neutral, and then dried at 120°C for 6 h. -1

[0046] The composition of the complex modifier used is sodium hydroxide: sodium carbonate: cobalt nitrate, wherein the mass ratio of sodium hydroxide: sodium carbonate: cobalt nitrate is 0.4:9:0.6, the mass ratio of complex modifier to petroleum coke is 0.6:1, the reaction temperature is 800°C under nitrogen atmosphere, and the reaction time is 2 h. The reaction product is washed with distilled water until it is neutral, and then dried at 120°C for 6 h to obtain the product marked as P-3.

[0047] Example 4

[0048] 50 g of low-quality petroleum coke B with a particle size of 5 mesh is loaded into a fixed bed reactor, the reaction temperature is 70°C, the reactor pressure is 2 atm, N2O4 with a concentration of 99.99 vol.% is used, the volume space velocity is 800 h-1, and the oxidation treatment time is 8 h. Then, the oxidized product is washed with water until it is neutral, and then dried at 120°C for 6 h. -1

[0049] The composition of the complex modifier used is sodium hydroxide: sodium carbonate: cobalt nitrate, wherein the mass ratio of sodium hydroxide: sodium carbonate: cobalt nitrate is 0.4:9:0.6, the mass ratio of complex modifier to petroleum coke is 0.6:1, the reaction temperature is 800°C under nitrogen atmosphere, and the reaction time is 2 h. The reaction product is washed with distilled water until it is neutral, and then dried at 120°C for 6 h to obtain the product marked as P-3.

[0050] Example 5

[0051] 50 g of low-quality petroleum coke B with a particle size of 5 mesh is loaded into a fixed bed reactor, the reaction temperature is 70°C, the reactor pressure is 2 atm, N2O4 with a concentration of 99.99 vol.% is used, the volume space velocity is 1000 h-1, and the oxidation treatment time is 8 h. Then, the oxidized product is washed with water until it is neutral, and then dried at 120°C for 6 h. -1 ​​, oxidation treatment time is 10h. Then, the oxidized product is washed with water until neutral, and dried at 120°C for 6h.

[0052] The composition of the complex modifier is magnesium hydroxide: sodium carbonate: calcium carbonate, wherein the mass ratio of magnesium hydroxide: sodium carbonate: calcium carbonate is 0.5:9:0.5, and the mass ratio of the complex modifier to petroleum coke is 0.5:1. The reaction temperature is 900°C under nitrogen atmosphere, and the reaction time is 0.3h. The reaction product is washed with distilled water until neutral, and dried at 120°C for 6h to obtain a product marked as D-1.

[0053] Comparative Example 1

[0054] 50g of low-quality petroleum coke A with a particle size of 5 mesh is charged into a fixed bed reactor, the reaction temperature is 70°C, the reactor pressure is 2atm, and N2O4 with a concentration of 99.99vol.% is used, the volume space velocity is 1000h -1 , and the oxidation treatment time is 8h. Then, the oxidized product is washed with water until neutral, and dried at 120°C for 6h.

[0055] The composition of the complex modifier is magnesium hydroxide: sodium carbonate: calcium carbonate, wherein the mass ratio of magnesium hydroxide: sodium carbonate: calcium carbonate is 0.5:9:0.5, and the mass ratio of the complex modifier to petroleum coke is 0.5:1. The reaction temperature is 900°C under nitrogen atmosphere, and the reaction time is 0.3h. The reaction product is washed with distilled water until neutral, and dried at 120°C for 6h to obtain a product marked as D-1.

[0056] Comparative Example 2

[0057] 50g of low-quality petroleum coke A with a particle size of 20 mesh is used, and the composition of the complex modifier is potassium hydroxide: sodium acetate: ferric nitrate, wherein the mass ratio of potassium hydroxide: sodium acetate: ferric nitrate is 0.3:9:0.7, and the mass ratio of the complex modifier to petroleum coke is 0.3:1. The reaction temperature is 700°C under nitrogen atmosphere, and the reaction time is 1h. The reaction product is washed with distilled water until neutral, and dried at 120°C for 6h to obtain a product marked as D-2.

[0058] Properties of the modified petroleum coke in each example in Table 2

[0059]

[0060] The embodiments of the present application are only detailed descriptions of the technical solutions of the present application, but the present application is not limited to the above-mentioned embodiments, that is, the present application can be implemented regardless of the steps described in the above-mentioned embodiments. In summary, any improvement on the present application made by a person skilled in the art, as long as it does not deviate from the content of the technical solutions of the present application, any simple modification, equivalent change and modification made on the above-mentioned embodiments according to the technical essence of the present application, all belong to the protection scope and disclosure scope of the present application.

Claims

1. A method for reforming the carbonaceous structure of inferior petroleum coke, comprising: (1) Mix inferior petroleum coke raw material with gaseous oxidant and react. The reaction product is washed and dried to obtain dried product. (2) The dried material obtained in step (1) is reacted with the compound modifier under an inert atmosphere, and after washing and drying, modified petroleum coke is obtained. In step (1), the gaseous oxidant is a nitrogen oxide, selected from one or more of NO, NO2, N2O3 and N2O4; In step (1), the conditions for the reaction of the inferior petroleum coke with the gaseous oxidant are: a temperature of 20-120℃; In step (2), the compound modifier includes an alkali, a sodium salt, and a transition metal salt, wherein the mass ratio of alkali:sodium salt:transition metal salt is (0.1-0.5):(8-9):(0.5-1.9); In step (2), the reaction temperature of the compound modifier and petroleum coke is 500-1200℃.

2. The method according to claim 1, characterized in that, In step (1), the particle size of the inferior petroleum coke raw material is 1-200 mesh.

3. The method according to claim 2, characterized in that, In step (1), the particle size of the inferior petroleum coke raw material is 5-20 mesh.

4. The method according to claim 1, characterized in that, The inferior petroleum coke raw material is high-sulfur petroleum coke.

5. The method according to claim 4, characterized in that, The petroleum coke contains 3% to 15% sulfur by mass.

6. The method according to claim 1, characterized in that, In step (1), the gaseous oxidant is N2O4.

7. The method according to claim 1 or 6, characterized in that, In step (1), the volume content of nitrogen oxides in the gaseous oxidant is 50%-100%.

8. The method according to claim 1, characterized in that, In step (1), the reaction of inferior petroleum coke feedstock with gaseous oxidant is carried out in a fixed-bed reactor.

9. The method according to claim 1 or 8, characterized in that, In step (1), the conditions for the reaction of the inferior petroleum coke with the gaseous oxidant are: pressure of 1-5 atm and volume hourly space velocity of the gaseous oxidant of 50-2000 h⁻¹. -1 The reaction time is 0.5-12 hours.

10. The method according to claim 1 or 8, characterized in that, In step (1), the conditions for the reaction of the inferior petroleum coke with the gaseous oxidant are: temperature of 30-70℃, pressure of 1-2 atm, and volume hourly space velocity of the gaseous oxidant of 150-1000 h⁻¹. -1 The reaction time is 6-10 hours.

11. The method according to claim 1, characterized in that, In step (1), the drying temperature is 60-150℃ and the drying time is 2-8h; and / or, in step (2), the drying temperature is 60-150℃ and the drying time is 2-8h.

12. The method according to claim 1, characterized in that, In step (1), the drying temperature is 80-120℃ and the drying time is 4-6h; and / or, in step (2), the drying temperature is 80-120℃ and the drying time is 4-6h.

13. The method according to claim 1, characterized in that, In the compound modifier described in step (2), the mass ratio of alkali:sodium salt:transition metal salt is (0.3-0.5):9:(0.5-0.7).

14. The method according to claim 1, characterized in that, In step (2), the base in the compound modifier is one or two of potassium hydroxide or sodium hydroxide; the sodium salt is one or two of sodium carbonate and sodium acetate; the transition metal salt is selected from one or more of iron, cobalt, nickel and manganese, and the transition metal salt is at least one of nitrate, carbonate and chloride.

15. The method according to claim 1, characterized in that, In step (2), the mass ratio of the compound modifier to the dried product obtained in step (1) is 0.1-1:

1.

16. The method according to claim 1, characterized in that, In step (2), the mass ratio of the compound modifier to the dried product obtained in step (1) is 0.3-0.6:

1.

17. The method according to claim 1, characterized in that, In step (2), the reaction time between the compound modifier and petroleum coke is 0.1-6.0 h.

18. The method according to claim 1 or 17, characterized in that, In step (2), the reaction temperature of the compound modifier with petroleum coke is 700-900℃; and / or, the reaction time of the compound modifier with petroleum coke is 0.3-2.0 h.

19. The method according to claim 1, characterized in that, Compared with petroleum coke feedstock, modified petroleum coke has a 25% to 70% increase in specific capacity; and / or, compared with petroleum coke feedstock, modified petroleum coke has a 10% to 60% increase in Sd1 / Sg ratio.

20. The method according to claim 19, characterized in that, Compared with petroleum coke feedstock, modified petroleum coke has a 45% to 70% increase in specific capacity; and / or, compared with petroleum coke feedstock, modified petroleum coke has a 25% to 40% increase in Sd1 / Sg ratio.

21. A modified petroleum coke, characterized in that, Prepared using the method described in any one of claims 1-20.

22. The petroleum coke according to claim 21, characterized in that, In the modified petroleum coke, Sd1 / Sg is greater than 2.0, and Sd3 / Sg is less than 0.8.

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