A method for modifying petroleum coke

Abstract

The present application relates to a petroleum coke modification method, the method comprises the following steps: (1) in the presence of hydrogen-containing gas atmosphere, alkali metal is dissolved in organic stream, then is mixed with petroleum coke uniformly, and desulfurization reaction is carried out; (2) in the presence of inert gas atmosphere, the reaction stream obtained in step (1) is subjected to carbonization reaction; (3) the reaction stream obtained in step (2) is separated, washed and dried to obtain modified petroleum coke product. The method significantly reduces the sulfur content in petroleum coke, and in-situ repairs the sulfur defect sites generated after desulfurization of petroleum coke, which is more conducive to maintaining the bulk structure of petroleum coke in the subsequent graphitization process.

Description

TECHNICAL FIELD

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

[0002] With the increasing production of high-sulfur crude oil, the sulfur content of crude oil processed by a refinery also increases. Sulfides in the crude oil migrate during the oil refining process and are finally enriched in petroleum coke, resulting in the increasing production of high-sulfur petroleum coke. In addition, a coking device is a residue-consuming device of a refinery, and all heavy fluid materials that cannot be processed can be mixed into the coking device for processing, thereby causing the sulfur content in the petroleum coke to exceed the standard.

[0003] There is a new trend in the use of petroleum coke, which is converted from a traditional extensive fuel type to a fine chemical type. On this basis, the sulfur contained in the petroleum coke will adversely affect the subsequent high-value utilization of the petroleum coke. The removal of the excessively high sulfur content under high-temperature conditions will not only affect the environment, but also cause irreversible damage to the carbon structure of the petroleum coke, thereby affecting the electrochemical properties of the negative electrode material and the stability of the battery.

[0004] CN 108726502 A discloses a method for reducing the sulfur content of petroleum coke, a petroleum coke desulfurization device, and petroleum coke. Raw materials, oxidizing agents, and catalysts are mixed to obtain a mixture. Process intensification is performed during the desulfurization process. Cavitation equipment is used to generate cavitation effects to promote the oxidation reaction. The reaction is a liquid-liquid reaction, which converts thiophene sulfides in atmospheric residue, vacuum residue, catalytic slurry, asphaltene, and waste oil into sulfone sulfides. The sulfone sulfides are decomposed through the heat release of the coking thermal polycondensation reaction, thereby achieving the purpose of desulfurization of the coking product.

[0005] CN 101804977 A discloses a method for removing sulfur from petroleum coke and a desulfurizer therefor. Concentrated hydrochloric acid and concentrated nitric acid are mixed according to a certain molar ratio to form a desulfurizer. The desulfurizer is mixed with high-sulfur petroleum coke at a ratio of 10-40 mL / g. The desulfurization rate is 40-60%. The method belongs to post-desulfurization technology. CN 105000547 A, CN 105036113 A, and CN 104611087 A disclose a method for desulfurizing petroleum coke, which belongs to post-desulfurization technology. The method mixes petroleum coke with a trace amount of catalyst under an ammonia atmosphere, heats and keeps warm, thereby achieving the purpose of desulfurization. The catalyst uses NiO and MoO2 with a particle size of less than or equal to 0.1 mm, and the mass ratio of NiO to MoO2 is (4-2):1. The method can reduce the sulfur content from 6.5wt% to 3wt%, and the desulfurization rate is between 70-80%.

[0006] The existing petroleum coke desulfurization technology only simply focuses on petroleum coke desulfurization, and does not consider the bulk structure of the petroleum coke after desulfurization. The patent CN 101804977 A uses the oxidation of strong acid to perform petroleum coke desulfurization, although the petroleum coke can be desulfurized, but the graphite sheet structure of the petroleum coke after desulfurization is opened. A series of patents CN105000547A, CN 105036113 A and CN104611087A introduce a large amount of metal after desulfurization, and the excessive metal has a negative effect on the electrochemical application of the petroleum coke. SUMMARY

[0007] In view of the deficiencies in the prior art, the present application provides a petroleum coke modification method. The method can significantly reduce the sulfur content in the petroleum coke, and in-situ repair the sulfur defect sites generated after desulfurization of the petroleum coke, which is more conducive to maintaining the bulk structure of the petroleum coke in the subsequent graphitization process.

[0008] The first aspect of the present application provides a petroleum coke modification method, which comprises the following steps:

[0009] (1) Dissolve an alkali metal in an organic stream in the presence of a hydrogen-containing atmosphere, and then uniformly mix the organic stream with petroleum coke to perform a desulfurization reaction;

[0010] (2) Perform a carbonization reaction on the reaction stream obtained in step (1) in the presence of an inert atmosphere;

[0011] (3) After separation, washing and drying of the reaction stream obtained in step (2), a modified petroleum coke product is obtained.

[0012] Further, in the above petroleum coke modification method, the particle size of the petroleum coke in step (1) is generally controlled to be 5-500 mesh, and preferably 80-200 mesh.

[0013] Further, in the above petroleum coke modification method, the hydrogen-containing atmosphere in step (1) is at least one of hydrogen, a mixture of hydrogen and an inert atmosphere, and the volume ratio of hydrogen to inert atmosphere in the mixture is 0.5-4:1, and preferably 1-2:1; the inert atmosphere is nitrogen and / or an inert gas, and preferably nitrogen, and the inert gas is at least one of helium, neon, argon, krypton and xenon.

[0014] Further, in the above petroleum coke modification method, the pressure of the hydrogen-containing atmosphere in step (1) is 0.5-6 MPa, and preferably 2-4 MPa.

[0015] Further, in the above petroleum coke modification method, the alkali metal in step (1) is one or more of lithium, sodium and potassium, and preferably sodium.

[0016] Further, in the above petroleum coke modification method, the organic stream in step (1) can be one or several of petroleum-based, coal-based, and biomass-based hydrocarbon-containing materials, preferably petroleum-based hydrocarbon-containing products, and further preferably kerosene or diesel oil fractions.

[0017] Further, in the above petroleum coke modification method, the ratio of petroleum coke to the organic stream in step (1) is 0.01-1:1, preferably 0.05-0.3:1, in terms of g / mL.

[0018] Further, in the above petroleum coke modification method, the mass ratio of alkali metal to petroleum coke in step (1) is 0.01-0.5:1, preferably 0.05-0.2:1.

[0019] Further, in the above petroleum coke modification method, the desulfurization reaction temperature in step (1) is 200-500°C, preferably 300-400°C, and the reaction time is 0.1-10 h, preferably 2-6 h.

[0020] Further, in the above petroleum coke modification method, the inert atmosphere in step (2) is nitrogen and / or an inert gas, preferably nitrogen, and the inert gas is at least one of helium, neon, argon, krypton, and xenon.

[0021] Further, in the above petroleum coke modification method, the gas partial pressure of the inert atmosphere in step (2) is 0.1-1 MPa, preferably 0.1-0.3 MPa.

[0022] Further, in the above petroleum coke modification method, the carbonization reaction temperature in step (2) is 500-900°C, preferably 600-700°C, and the reaction time is 1-10 h, preferably 4-6 h.

[0023] Further, in the above petroleum coke modification method, the separation in step (3) is solid-liquid separation, and the solid-liquid separation method is not particularly limited and can be any one of the existing solid-liquid separation methods in the art. In the present application, the solid-liquid separation method can be at least one of filtration, centrifugal separation, and sedimentation, and preferably filtration.

[0024] Further, in the above petroleum coke modification method, the drying conditions in step (3) are as follows: the drying temperature is 80-400°C, preferably 120-350°C, and the drying time is 2-8 h, preferably 4-6 h, and preferably the drying is performed under vacuum.

[0025] Further, in the above petroleum coke modification method, the washing in step (3) is washing with water for several times, preferably deionized water, and the washing is generally required to be neutral.

[0026] The second aspect of the present application provides a modified petroleum coke obtained by the above method. The modified petroleum coke has a sulfur content of 0.5-10.0 wt.%, a specific surface area of 1-15 m 2 / g, a true density of 1.8-2.5 g / cm 3 , and a volatile matter content of less than 9%.

[0027] Compared with the prior art, the petroleum coke modification method provided by the present application has the following advantages:

[0028] In the petroleum coke modification method, the organic stream acts as a dispersant for alkali metals, so that the alkali metals can fully react with sulfides in the petroleum coke. Through optimization of the reaction atmosphere, the petroleum system and the coal system rich in carbon resources are further utilized, so that the defect sites of the desulfurized petroleum coke are continuously modified in the two-step reaction process of step (1) and step (2), and in particular, in the carbonization reaction of step (2), the reaction stream obtained in step (1) is subjected to in-situ carbonization reaction, so as to realize lossless desulfurization of the petroleum coke body structure, i.e., desulfurization and carbonization modification of the defect sites are simultaneously performed. In the present application, diesel oil can be used as a carbon source precursor, which is not only abundant in source but also simple and easy to implement. In addition, the petroleum coke modification reaction is changed from a solid-solid phase reaction to a liquid-solid phase reaction, which greatly improves the mass transfer. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 The figure shows the Raman spectra of the petroleum coke before and after modification in Example 1. P represents the initial petroleum coke, and P-1 represents the modified petroleum coke. DETAILED DESCRIPTION

[0030] The technical content and effects of the present application are further illustrated below in combination with examples, but the present application is not limited thereto.

[0031] The petroleum coke raw material used in the examples and comparative examples of the present application has a sulfur content of 8.75 wt%, and the purity of the gas used in the present application is more than 99.9%. The initial petroleum coke is denoted as P, and the physical properties and performance of the petroleum coke are mainly evaluated by Raman spectrum analysis, specific surface area and pore size distribution (BET) testing, and lithium battery property testing. The Raman (Raman) spectrum analysis is performed on a HR800 confocal micro-laser Raman spectrometer of HORIBA Jobin Yvon Company in France, the emission laser wavelength is 532 nm, the power is 10 mW, the spectral resolution is 0.65 cm -1 , the grating is 1800 g·mm -1 , and the Raman shift range is 0-2000 cm -1 . I D / I G The D peak and the G peak of the Raman spectrum are calculated after peak fitting by the data processing software.

[0032] The specific surface area and pore size distribution (BET) test uses the ASAP-2460 full-automatic specific surface area and pore analyzer of the American Micromeritics company to characterize the specific surface area and pore size distribution of the petroleum coke. The sample is pretreated at 150 ℃ for 12 h, and then the adsorption and desorption isotherms are determined at a high-purity liquid nitrogen temperature (-196 ℃), and the specific surface area is calculated by the Brunauer-Emmett-Teller (BET) equation.

[0033] The sulfur content is analyzed using the Kaiyuan 5E-AS3200B automatic coulomb sulfur tester. First, the tube furnace is heated to 1150 ℃; the gas supply pump and the air pump are opened and the air flow is adjusted to 1000 ml / min, the electrolyte is added to the electrolytic cell, and the magnetic stirrer is turned on; about 0.05 g of sample is weighed into a porcelain boat, and a thin layer of tungsten trioxide is covered on the sample, the porcelain boat is placed in the sample quartz tray, the sample is automatically sent into the furnace, and the coulometric titration is started at the same time. After the test is completed, the coulometric integrator will give the sulfur content of the sample. Among them, the preparation method of potassium iodide electrolyte is: respectively weigh 5 g of potassium iodide and potassium bromide, dissolve in 300 ml of water, add 10 ml of glacial acetic acid to the solution, and mix well for standby.

[0034] The modified petroleum coke is graphitized in a graphitization furnace at a temperature of 2800 ℃. The modified petroleum coke after graphitization treatment is used as the negative electrode to make a button lithium ion battery. The assembly of the button lithium ion battery is carried out in an argon atmosphere glove box. In the assembled lithium ion battery, the cathode is a lithium sheet with a diameter of 19 mm, a polypropylene separator is used, and the electrolyte is 1M lithium hexafluorophosphate / ethylene carbonate / dimethyl carbonate / methyl ethyl carbonate with a volume ratio of 1:1:1. The assembly sequence is negative shell, spring, gasket, lithium sheet, separator, electrode, and positive shell. The assembled battery is sealed in a sealing machine, taken out of the glove box, and placed for 24 h before electrochemical testing. The button lithium ion battery is tested for charge and discharge and rate performance using a Swiss Watan electrochemical workstation, with a discharge cutoff voltage of 0.005 V and a charge cutoff voltage of 2 V.

[0035] Example 1

[0036] Take 100 mesh petroleum coke 10 g, 100 ml diesel and 1 g of sodium metal, mix evenly, placed in the reaction kettle, the atmosphere is hydrogen, hydrogen containing atmosphere pressure is 3.5 MPa, first heated to 360 ℃ temperature, reaction 4 h. After the reaction switch to nitrogen atmosphere carbonization reaction, nitrogen partial pressure is 0.1 MPa, heated to 700 ℃, reaction 4 h. After the reaction, the petroleum coke and diesel are separated, dried under vacuum, the drying temperature is 350 °C, the dried petroleum coke is washed with water until the filtrate pH is neutral, the modified petroleum coke is obtained, the petroleum coke is recorded as P-1.

[0037] Example 2

[0038] Take 200 mesh petroleum coke 10 g, 100 ml diesel and 1 g of sodium metal, mix evenly, placed in the reaction kettle, the atmosphere is hydrogen, hydrogen containing atmosphere pressure is 3.5 MPa, first heated to 400 ℃ temperature, reaction 4 h, after the reaction switch to nitrogen atmosphere carbonization reaction, nitrogen partial pressure is 0.1 MPa, heated to 700 ℃, reaction 4 h. After the reaction, the petroleum coke and diesel are separated, dried under vacuum, the drying temperature is 350 °C, the dried petroleum coke is washed with water until the filtrate pH is neutral, the modified petroleum coke is obtained, the petroleum coke is recorded as P-2.

[0039] Example 3

[0040] Take 100 mesh petroleum coke 10 g, 33 ml diesel and 1 g of sodium metal, mix evenly, placed in the reaction kettle, the atmosphere is hydrogen, hydrogen containing atmosphere pressure is 3.5 MPa, first heated to 360 ℃ temperature, reaction 4 h, after the reaction switch to nitrogen atmosphere carbonization reaction, nitrogen partial pressure is 0.3 MPa, heated to 600 ℃, reaction 4 h. After the reaction, the petroleum coke and diesel are separated, dried under vacuum, the drying temperature is 350 °C, the dried petroleum coke is washed with water until the filtrate pH is neutral, the modified petroleum coke is obtained, the petroleum coke is recorded as P-3.

[0041] Example 4

[0042] Take 100 mesh petroleum coke 10 g, 100 ml diesel and 0.5 g of sodium metal, mix evenly, placed in the reaction kettle, the atmosphere is hydrogen, hydrogen containing atmosphere pressure is 2 MPa, first heated to 360 ℃ temperature, reaction 6 h, after the reaction switch to nitrogen atmosphere carbonization reaction, nitrogen partial pressure is 0.1 MPa, heated to 700 ℃, reaction 4 h. After the reaction, the petroleum coke and diesel are separated, dried under vacuum, the drying temperature is 350 °C, the dried petroleum coke is washed with water until the filtrate pH is neutral, the modified petroleum coke is obtained, the petroleum coke is recorded as P-4.

[0043] Example 5

[0044] Take 10g of 100 mesh petroleum coke, 100 ml of kerosene and 1 g of metallic sodium, mix uniformly, then place in the reaction kettle, the atmosphere is hydrogen and nitrogen mixed gas, the pressure of the mixed gas is 4 MPa, the volume ratio of hydrogen to nitrogen is 1.5:1, first heat to 360°C, react for 4 h, then switch to nitrogen atmosphere for carbonization reaction, the nitrogen partial pressure is 0.1 MPa, heat to 700°C, react for 4 h. Then separate the petroleum coke and kerosene after the reaction, dry them under vacuum conditions, the drying temperature is 350°C, wash the dried petroleum coke with water until the filtrate pH value is neutral, obtain the modified petroleum coke, the petroleum coke is recorded as P-5.

[0045] Example 6

[0046] Take 10g of 100 mesh petroleum coke, 100 ml of kerosene and 1 g of metallic sodium, mix uniformly, then place in the reaction kettle, the atmosphere is hydrogen and nitrogen mixed gas, the pressure of the mixed gas is 4 MPa, the volume ratio of hydrogen to nitrogen is 1.5:1, first heat to 360°C, react for 4 h, then switch to nitrogen atmosphere for carbonization reaction, the nitrogen partial pressure is 0.1 MPa, heat to 700°C, react for 4 h. Then separate the petroleum coke and kerosene after the reaction, dry them under vacuum conditions, the drying temperature is 350°C, wash the dried petroleum coke with water until the filtrate pH value is neutral, obtain the modified petroleum coke, the petroleum coke is recorded as P-5.

[0047] Example 7

[0048] Take 10g of 100 mesh petroleum coke, 100 ml of kerosene and 1 g of metallic sodium, mix uniformly, then place in the reaction kettle, the atmosphere is hydrogen and nitrogen mixed gas, the pressure of the mixed gas is 4 MPa, the volume ratio of hydrogen to nitrogen is 1.5:1, first heat to 360°C, react for 4 h, then switch to nitrogen atmosphere for carbonization reaction, the nitrogen partial pressure is 0.1 MPa, heat to 700°C, react for 4 h. Then separate the petroleum coke and kerosene after the reaction, dry them under vacuum conditions, the drying temperature is 350°C, wash the dried petroleum coke with water until the filtrate pH value is neutral, obtain the modified petroleum coke, the petroleum coke is recorded as P-5.

[0049] Example 8

[0050] Take 100 mesh petroleum coke 10 g, 100 ml diesel and 1 g of metal potassium, mix evenly, placed in the reaction kettle, the atmosphere is hydrogen and nitrogen mixed gas, the pressure of the mixed gas is 4 MPa, the volume ratio of hydrogen to nitrogen is 1:1, first heated to 300℃, reaction for 6h, after reaction switch to helium atmosphere for carbonization reaction, the partial pressure of helium is 0.1 MPa, heated to 650℃, reaction for 6h. Then the petroleum coke and diesel are separated after reaction, dried under vacuum, the drying temperature is 350℃, the dried petroleum coke is washed with water until the filtrate pH value is neutral, the modified petroleum coke is obtained, the petroleum coke is recorded as P-8.

[0051] Comparative example 1

[0052] Put 100 mesh petroleum coke into the reaction kettle, the hydrogen partial pressure is 3.5 MPa, first heated to 360℃, reaction for 4h, the nitrogen partial pressure is 0.1 MPa, heated to 700℃, reaction for 4h. Then the petroleum coke and diesel are separated after reaction, dried under vacuum, the drying temperature is 350℃, the dried petroleum coke is washed with water until the filtrate pH value is neutral, the modified petroleum coke is obtained, the petroleum coke is recorded as D-1.

[0053] Comparative example 2

[0054] Take 100 mesh petroleum coke 10 g, 100 ml diesel and 1 g of metal sodium, mix evenly, placed in the reaction kettle, the nitrogen partial pressure is 3.5 MPa, first heated to 360℃, reaction for 4h, the nitrogen partial pressure is 0.1 MPa, heated to 700℃, reaction for 4h. Then the petroleum coke and diesel are separated after reaction, dried under vacuum, the drying temperature is 350℃, the dried petroleum coke is washed with water until the filtrate pH value is neutral, the modified petroleum coke is obtained, the petroleum coke is recorded as D-2.

[0055] Table 1 Physical properties and performance of petroleum coke

[0056]

Claims

1. A method for modifying petroleum coke, characterized by: The method comprises the following steps: (1) dissolving alkali metal in organic stream in the presence of hydrogen-containing atmosphere, then mixing with petroleum coke uniformly, and carrying out desulfurization reaction; (2) carrying out carbonization reaction on the reaction stream obtained in step (1) in the presence of inert atmosphere; (3) obtaining modified petroleum coke product after separation, washing and drying of the reaction stream obtained in step (2); The organic stream in step (1) is one or several of petroleum-based, coal-based and biomass-based hydrocarbon-containing materials; The ratio of petroleum coke to organic stream in step (1) is 0.01-1:1 in g / mL; The mass ratio of alkali metal to petroleum coke in step (1) is 0.01-0.5:1; The carbonization reaction temperature in step (2) is 500-900℃.

2. The method of claim 1, wherein: The particle size of petroleum coke in step (1) is controlled to be 5-500 mesh.

3. The method of claim 2, wherein: The particle size of petroleum coke in step (1) is controlled to be 80-200 mesh.

4. The method of claim 1, wherein: The hydrogen-containing atmosphere in step (1) is at least one of hydrogen, a mixture of hydrogen and inert atmosphere, and the volume ratio of hydrogen to inert atmosphere in the mixture is 0.5-4:

1.

5. The method of claim 4, wherein: The volume ratio of hydrogen to inert atmosphere in the mixture is 1-2:

1.

6. The method of claim 4, wherein: The inert atmosphere in step (1) is nitrogen and / or inert gas; the inert gas is at least one of helium, neon, argon, krypton and xenon.

7. The method of claim 6, wherein: The inert atmosphere in step (1) is nitrogen.

8. The method of claim 1, wherein: The pressure of hydrogen-containing atmosphere in step (1) is 0.5-6 MPa.

9. The method of claim 8, wherein: The pressure of hydrogen-containing atmosphere in step (1) is 2-4 MPa.

10. The method of claim 1, wherein: The alkali metal in step (1) is one or several of lithium, sodium and potassium.

11. The method of claim 10, wherein: The alkali metal in step (1) is sodium.

12. The method of claim 1, wherein: The organic stream in step (1) is petroleum-based hydrocarbon-containing product.

13. The method of claim 12, wherein: The organic stream in step (1) is kerosene or diesel fraction.

14. The method of claim 1, wherein: The ratio of petroleum coke to organic stream in step (1) is 0.05-0.3:1 in g / mL.

15. The method of claim 1, wherein: The mass ratio of alkali metal to petroleum coke in step (1) is 0.05-0.2:

1.

16. The method of claim 1, wherein: The desulfurization reaction temperature in step (1) is 200-500℃.

17. The method of claim 16, wherein: The desulfurization reaction temperature in step (1) is 300-400℃.

18. The method of claim 1, wherein: The inert atmosphere in step (2) is nitrogen and / or inert gas, and the inert gas is at least one of helium, neon, argon, krypton and xenon.

19. The method of claim 18, wherein: The inert atmosphere in step (2) is nitrogen.

20. The method of claim 1, wherein: The gas partial pressure of inert atmosphere in step (2) is 0.1-1 MPa.

21. The method of claim 20, wherein: The gas partial pressure of inert atmosphere in step (2) is 0.1-0.3 MPa.

22. The method of claim 1, wherein: The carbonization reaction temperature in step (2) is 600-700℃.

23. The method of claim 1, wherein: The drying conditions in step (3) are as follows: the drying temperature is 80-400℃, and the drying time is 2-8h.

24. The method of claim 23, wherein: The drying conditions in step (3) are as follows: the drying temperature is 120-350℃, and the drying time is 4-6h.

25. The method of claim 23, wherein: The drying in step (3) is carried out under vacuum condition.

26. The modified petroleum coke obtained by the process of any one of claims 1 to 25, characterized in that: The modified petroleum coke has a sulfur content of 0.5-10.0 wt.%, a specific surface area of 1-15 m 2 / g, a true density of 1.8-2.5 g / cm 3 , and a volatile matter content of less than 9%.

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