Petroleum coke modification method

Abstract

The invention relates to a petroleum coke modification method, which comprises: (1) in the presence of a hydrogen-containing atmosphere, dissolving an alkali metal in an organic material flow, uniformly mixing with petroleum coke, and carrying out a desulfurization reaction, (2) in the presence of inert atmosphere, carrying out carbonization reaction on the reaction material flow obtained in the step (1); and (3) separating, washing and drying the reaction material flow obtained in the step (2) to obtain the modified petroleum coke product. According to the method, the sulfur content in the petroleum coke is obviously reduced, and sulfur defect sites generated by the desulfurized petroleum coke are repaired in situ, so that the body structure of the petroleum coke is more favorably kept in the subsequent graphitization process.

Description

Technical Field

[0001] The invention belongs to the technical field of carbon material preparation, and in particular relates to a petroleum coke modification method. Background Art

[0002] As the output of high-sulfur crude oil increases year by year, the sulfur content of crude oil processed by refineries also increases. The sulfides in crude oil will migrate during the refining process and eventually accumulate in petroleum coke, resulting in an increase in the output of high-sulfur petroleum coke year by year. In addition, the coking unit is a slag-eating unit in the refinery, and all heavy fluid materials that cannot be processed can be mixed into the coking unit for processing, which in turn causes the sulfur content in petroleum coke to exceed the standard.

[0003] There is a new trend in the use of petroleum coke, from the traditional extensive fuel type to the fine chemical type. On this basis, the sulfur contained in the petroleum coke itself will have an adverse effect on the subsequent high-value utilization of the petroleum coke. Excessive sulfur content during the thermal treatment of petroleum coke will not only affect the environment, but its removal under high temperature conditions will cause irreversible damage to the carbonaceous structure of the petroleum coke, affecting the carbonaceous structure of the petroleum coke, and further 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. A raw material, an oxidant and a catalyst are mixed to obtain a mixture, and the process is strengthened during the desulfurization process. A cavitation effect is produced by a cavitation device to promote the oxidation reaction. The reaction belongs to a liquid-liquid reaction, and thiophene sulfides in atmospheric residue oil, vacuum residue oil, catalytic slurry, asphaltene and waste oil are converted into sulfone sulfides, and the sulfone sulfides are decomposed by the heat release of the thermal polycondensation reaction of coking, thereby achieving the purpose of desulfurization of coking products.

[0005] CN 101804977 A discloses a method for removing sulfur from petroleum coke and a desulfurizer thereof. Concentrated hydrochloric acid and concentrated nitric acid are configured in a certain molar ratio to form a desulfurizer, and mixed with high-sulfur petroleum coke in a ratio of 10 to 40 mL / g. The desulfurization rate is 40 to 60%, and the method belongs to post-desulfurization technology. A series of patents including CN105000547A, CN105036113A and CN104611087A disclose a method for desulfurization of petroleum coke, which belongs to post-desulfurization technology. The method mixes petroleum coke with a trace catalyst under an ammonia atmosphere, heats and insulates the mixture, thereby achieving the purpose of desulfurization. The catalyst is NiO and MoO2 with a particle size 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% and 80%.

[0006] Existing petroleum coke desulfurization technology simply focuses on petroleum coke desulfurization, and does not consider the main structure of petroleum coke after desulfurization. Patent CN 101804977 A uses strong acid oxidation to desulfurize petroleum coke. Although desulfurization can be achieved, the graphite sheet structure of petroleum coke will be stretched after desulfurization. A series of patents such as CN105000547A, CN 105036113 A and CN104611087A introduce a large amount of metal after desulfurization, and excessive metal has a negative impact on the electrochemical application of petroleum coke. Summary of the invention

[0007] In view of the shortcomings of the prior art, the present invention provides a petroleum coke modification method, which can significantly reduce the sulfur content in the petroleum coke and perform in-situ repair of sulfur defects generated in the desulfurized petroleum coke, which is more conducive to maintaining the main structure of the petroleum coke in the subsequent graphitization process.

[0008] The first aspect of the present invention provides a petroleum coke modification method, the modification method comprising the following steps: (1) In the presence of a hydrogen-containing atmosphere, the alkali metal is dissolved in an organic stream and then mixed evenly with petroleum coke to carry out a desulfurization reaction; (2) subjecting the reaction stream obtained in step (1) to a carbonization reaction under an inert atmosphere; (3) The reaction stream obtained in step (2) is separated, washed and dried to obtain a modified petroleum coke product.

[0009] Furthermore, 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, preferably 80-200 mesh.

[0010] Furthermore, in the above petroleum coke modification method, the hydrogen-containing atmosphere in step (1) is at least one of hydrogen and a mixed gas of hydrogen and an inert atmosphere, and the volume ratio of hydrogen to the inert atmosphere in the mixed gas is 0.5-4:1, preferably 1-2:1; the inert atmosphere is nitrogen and / or an inert gas, preferably nitrogen, and the inert gas is at least one of helium, neon, argon, krypton, and xenon.

[0011] Furthermore, in the above petroleum coke modification method, the pressure of the hydrogen-containing atmosphere in step (1) is 0.5-6 MPa, preferably 2-4 MPa.

[0012] Furthermore, in the above petroleum coke modification method, the alkali metal in step (1) is one or more of lithium, sodium and potassium, preferably sodium.

[0013] Furthermore, in the above petroleum coke modification method, the organic stream in step (1) can be one or more of petroleum-based, coal-based, and biomass-based hydrocarbon-containing materials, preferably a petroleum-based hydrocarbon-containing product, and more preferably kerosene or diesel fractions.

[0014] Furthermore, in the above petroleum coke modification method, the ratio of petroleum coke to organic stream in step (1) is 0.01-1:1, preferably 0.05-0.3:1, in terms of g / mL.

[0015] Furthermore, 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.

[0016] Furthermore, 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.

[0017] Furthermore, 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.

[0018] Furthermore, 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.

[0019] Furthermore, 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.

[0020] Furthermore, in the petroleum coke modification method, the separation in step (3) is solid-liquid separation, and the method of solid-liquid separation is not particularly limited, and any of the existing solid-liquid two-phase separation methods in the art can be used. Specifically in the present invention, the solid-liquid separation method can be at least one of filtration, centrifugal separation, sedimentation, etc., preferably filtration.

[0021] Furthermore, in the above petroleum coke modification method, the drying conditions in step (3) are as follows: the drying temperature is 80 to 400° C., preferably 120 to 350° C., the drying time is 2 to 8 hours, preferably 4 to 6 hours, and the drying is preferably carried out under vacuum conditions.

[0022] Furthermore, in the above petroleum coke modification method, the washing in step (3) is performed by washing with water for several times, preferably with deionized water, and it is generally best to wash until the filtrate is neutral.

[0023] The second aspect of the present invention provides a modified petroleum coke obtained by the above method. The modified petroleum coke has a sulfur content of 0.5-10.0wt.%, a specific surface area of ​​1-15m 2 / g, true density 1.8~2.5 g / cm 3 , volatile matter is less than 9%.

[0024] Compared with the prior art, the petroleum coke modification method provided by the present invention has the following advantages: In the petroleum coke modification method of the present invention, the organic flow is used as a dispersant for the alkali metal to fully react with the sulfide in the petroleum coke; by optimizing the reaction atmosphere, the carbon-rich resources of the petroleum system and the coal system are further fully utilized to continuously modify the defective sites of the desulfurized petroleum coke during the two-step reaction process of step (1) and step (2), especially in the carbonization reaction of step (2), the reaction stream obtained in step (1) is subjected to an in-situ carbonization reaction to achieve non-destructive desulfurization of the main structure of the petroleum coke, that is, carbonization modification of the defective sites is performed while desulfurization is performed. The present invention can use diesel as a carbon source precursor, which is not only abundant in source but also simple and easy to operate. In addition, the present invention transforms the petroleum coke modification reaction from a solid-solid phase reaction to a liquid-solid phase reaction, greatly improving mass transfer. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The Raman spectra of petroleum coke before and after modification in Example 1 are shown. Wherein, P is the initial petroleum coke, and P-1 is the modified petroleum coke. Implementation

[0026] The technical content and effects of the present invention are further illustrated below in conjunction with embodiments, but the present invention is not limited thereby.

[0027] The sulfur content of the petroleum coke raw material used in the embodiments and comparative examples of the present invention is 8.75wt%, the purity of the gas used in the present invention is above 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 spectroscopy, specific surface area and pore size distribution (BET) test and lithium battery property test. Raman spectroscopy analysis is performed on a HR800 confocal microscopic laser Raman spectrometer of HORIBA JobinYvon, France, with an emission laser wavelength of 532 nm, a power of 10 mW, and a spectral resolution of 0.65 cm -1 , grating is 1800 g·mm -1 , Raman shift range 0~2000 cm -1 I D / I G The result is calculated by data processing software after peak fitting of the D peak and G peak of the Raman spectrum.

[0028] The specific surface area and pore size distribution (BET) test was performed using the ASAP-2460 fully automatic specific surface area and pore size analyzer from Micromeritics, USA, to characterize the specific surface area and pore size distribution of petroleum coke. The sample was pretreated at 150 °C for 12 h, and then its adsorption-desorption isotherm was measured at high-purity liquid nitrogen temperature (-196 °C), and its specific surface area was calculated by the Brunauer-Emmett-Teller (BET) equation.

[0029] The sulfur content was analyzed using Kaiyuan 5E-AS3200B automatic coulometric sulfur analyzer. First, the tubular high-temperature furnace was heated to 1150 °C; the gas supply pump and the vacuum pump were turned on and the vacuum flow rate was adjusted to 1000 ml / min, the electrolyte was added to the electrolytic cell, and the magnetic stirrer was turned on; about 0.05 g of the sample was weighed and placed in a porcelain boat, and a thin layer of tungsten trioxide was covered on the sample, the porcelain boat was placed in the sample delivery quartz tray, and the sample delivery program controller was turned on. The sample automatically entered the furnace and coulometric titration was started at the same time. After the test, the coulometric integrator would give the sulfur content of the sample. Among them, the potassium iodide electrolyte was prepared as follows: 5 g of potassium iodide and potassium bromide were weighed respectively, dissolved in 300 ml of water, 10 ml of glacial acetic acid was added to the solution, and mixed well for later use.

[0030] The modified petroleum coke was graphitized in a graphitization furnace at a temperature of 2800℃. The modified petroleum coke after graphitization was used as the negative electrode to make a button-type lithium-ion battery. The assembly of the button-type lithium-ion battery was carried out in a glove box with an argon atmosphere. In the assembled lithium-ion battery, the counter electrode was a lithium sheet with a diameter of 19 mm, a polypropylene diaphragm was used, and the electrolyte was 1M lithium hexafluorophosphate / ethylene carbonate / dimethyl carbonate / ethyl methyl carbonate, with a volume ratio of 1:1:1. The assembly order was negative electrode shell, shrapnel, gasket, lithium sheet, diaphragm, pole piece, and positive electrode shell. The assembled battery was placed in a sealing machine for sealing, taken out of the glove box, and electrochemical tests were performed after standing for 24 hours. The button-type lithium-ion battery was charged and discharged and tested for rate performance using a Swiss Metrohm electrochemical workstation, with the discharge cut-off voltage set to 0.005 V and the charge cut-off voltage set to 2 V.

[0031] Example 1 Take 100 mesh petroleum coke 10g, 100 ml diesel and 1g sodium metal, mix them evenly, place them in a reactor with a hydrogen atmosphere and a hydrogen atmosphere pressure of 3.5 MPa, first heat it to 360℃ and react for 4h. After the reaction, switch to a nitrogen atmosphere for carbonization reaction, the nitrogen partial pressure is 0.1 MPa, heat it to 700℃ and react for 4h. After the reaction, separate the petroleum coke from the diesel, dry it under vacuum conditions, the drying temperature is 350°C, wash the dried petroleum coke with water until the pH value of the filtrate is neutral, and obtain the modified petroleum coke, which is recorded as P-1.

[0032] Example 2 Take 10g of 200-mesh petroleum coke, 100 ml of diesel and 1g of metallic sodium, mix them evenly, and place them in a reactor with a hydrogen atmosphere and a hydrogen atmosphere pressure of 3.5 MPa. First, heat it to 400°C and react for 4 hours. After the reaction, switch to a nitrogen atmosphere for carbonization reaction with a nitrogen partial pressure of 0.1 MPa, heat it to 700°C and react for 4 hours. After the reaction, separate the petroleum coke from the diesel, dry it under vacuum conditions at a drying temperature of 350°C, and wash the dried petroleum coke with water until the pH value of the filtrate is neutral to obtain modified petroleum coke, which is recorded as P-2.

[0033] Example 3 Take 10g of 100-mesh petroleum coke, 33 ml of diesel and 1g of sodium metal, mix them evenly, and place them in a reactor with a hydrogen atmosphere and a hydrogen atmosphere pressure of 3.5 MPa. First, heat it to 360°C and react for 4 hours. After the reaction, switch to a nitrogen atmosphere for carbonization reaction with a nitrogen partial pressure of 0.3 MPa, heat it to 600°C and react for 4 hours. After the reaction, separate the petroleum coke from the diesel, dry it under vacuum conditions at a drying temperature of 350°C, and wash the dried petroleum coke with water until the pH value of the filtrate is neutral to obtain modified petroleum coke, which is recorded as P-3.

[0034] Example 4 Take 100-mesh petroleum coke 10g, 100 ml diesel and 0.5g sodium metal, mix them evenly, and place them in a reactor. The atmosphere is hydrogen, and the pressure of the hydrogen atmosphere is 2 MPa. First, heat it to 360℃ and react for 6h. After the reaction, switch to nitrogen atmosphere for carbonization reaction. The nitrogen partial pressure is 0.1 MPa, heat it to 700℃ and react for 4h. After the reaction, separate the petroleum coke from the diesel, dry it under vacuum conditions, and the drying temperature is 350℃. Wash the dried petroleum coke with water until the pH value of the filtrate is neutral to obtain modified petroleum coke, which is recorded as P-4.

[0035] Example 5 Take 100-mesh petroleum coke 10g, 100 ml kerosene and 1g metallic sodium, mix them evenly, and place them in a reactor. The atmosphere is a mixture of hydrogen and nitrogen. The pressure of the mixture is 4 MPa, and the volume ratio of hydrogen to nitrogen is 1.5:1. First, heat it to 360℃ and react for 4h. After the reaction, switch to nitrogen atmosphere for carbonization reaction. The nitrogen partial pressure is 0.1 MPa, heat it to 700℃, and react for 4h. After the reaction, separate the petroleum coke from the kerosene, dry it under vacuum conditions, and the drying temperature is 350℃. Wash the dried petroleum coke with water until the pH value of the filtrate is neutral to obtain modified petroleum coke, which is recorded as P-5.

[0036] Example 6 Take 100-mesh petroleum coke 10g, 100 ml diesel and 1g potassium metal, mix them evenly, and place them in a reactor with a hydrogen atmosphere and a hydrogen atmosphere pressure of 3.5 MPa. First, heat it to 360°C and react for 4 hours. After the reaction, switch to a nitrogen atmosphere for carbonization reaction with a nitrogen partial pressure of 0.1 MPa, heat it to 700°C and react for 4 hours. After the reaction, separate the petroleum coke from the diesel, dry it under vacuum conditions at a drying temperature of 350°C, and wash the dried petroleum coke with water until the pH value of the filtrate is neutral to obtain modified petroleum coke, which is recorded as P-6.

[0037] Example 7 Take 100-mesh petroleum coke 10g, 100 ml diesel and 1g potassium metal, mix them evenly, and place them in a reactor. The atmosphere is a mixture of hydrogen and nitrogen. The pressure of the mixture is 4 MPa, and the volume ratio of hydrogen to nitrogen is 1:1. First, heat it to 300℃ and react for 6h. After the reaction, switch to helium atmosphere for carbonization reaction. The helium partial pressure is 0.1 MPa, heat it to 700℃, and react for 6h. After the reaction, separate the petroleum coke from the diesel, dry it under vacuum conditions, and the drying temperature is 350℃. Wash the dried petroleum coke with water until the pH value of the filtrate is neutral to obtain modified petroleum coke, which is recorded as P-7.

[0038] Example 8 Take 100-mesh petroleum coke 10g, 100 ml diesel and 1g potassium metal, mix them evenly, and place them in a reactor. The atmosphere is a mixture of hydrogen and nitrogen. The pressure of the mixture is 4 MPa, and the volume ratio of hydrogen to nitrogen is 1:1. First, heat it to 300℃ and react for 6h. After the reaction, switch to helium atmosphere for carbonization reaction. The helium partial pressure is 0.1 MPa, heat it to 650℃, and react for 6h. After the reaction, separate the petroleum coke from the diesel, dry it under vacuum conditions, and the drying temperature is 350℃. Wash the dried petroleum coke with water until the pH value of the filtrate is neutral to obtain modified petroleum coke, which is recorded as P-8.

[0039] Comparative Example 1 The 100-mesh petroleum coke was placed in a reactor with a hydrogen partial pressure of 3.5 MPa, first heated to 360°C and reacted for 4 hours, and then the nitrogen partial pressure was 0.1 MPa, heated to 700°C and reacted for 4 hours. After the reaction, the petroleum coke was separated from the diesel and dried under vacuum at a drying temperature of 350°C. The dried petroleum coke was washed with water until the pH value of the filtrate was neutral, and the modified petroleum coke was obtained, which was recorded as D-1.

[0040] Comparative Example 2 Take 100-mesh petroleum coke 10g, 100 ml diesel and 1g sodium metal, mix them evenly, put them in a reactor, and heat them to 360℃ for 4h with nitrogen partial pressure of 3.5 MPa, then heat them to 700℃ for 4h with nitrogen partial pressure of 0.1 MPa. After the reaction, separate the petroleum coke from diesel, dry them under vacuum at 350℃, wash the dried petroleum coke with water until the pH value of the filtrate is neutral, and obtain the modified petroleum coke, which is recorded as D-2.

[0041] Table 1 Physical properties and performance of petroleum coke

Claims

1. A petroleum coke modification method, characterized in that: The method comprises the following steps: (1) In the presence of a hydrogen-containing atmosphere, the alkali metal is dissolved in an organic stream and then mixed evenly with petroleum coke to carry out a desulfurization reaction; (2) subjecting the reaction stream obtained in step (1) to a carbonization reaction under an inert atmosphere; (3) The reaction stream obtained in step (2) is separated, washed and dried to obtain a modified petroleum coke product.

2. The method according to claim 1, characterized in that: The particle size of the petroleum coke in step (1) is controlled to be 5-500 mesh, preferably 80-200 mesh.

3. The method according to claim 1, characterized in that: The hydrogen-containing atmosphere in step (1) is at least one of hydrogen and a mixed gas of hydrogen and an inert atmosphere, and the volume ratio of hydrogen to the inert atmosphere in the mixed gas is 0.5-4:1, preferably 1-2:

1.

4. The method according to claim 3, characterized in that: The inert atmosphere is nitrogen and / or an inert gas, preferably nitrogen; the inert gas is at least one of helium, neon, argon, krypton and xenon.

5. The method according to claim 1, characterized in that: The pressure of the hydrogen-containing atmosphere in step (1) is 0.5-6 MPa, preferably 2-4 MPa.

6. The method according to claim 1, characterized in that: The alkali metal in step (1) is one or more of lithium, sodium and potassium, preferably sodium.

7. The method according to claim 1, characterized in that: The organic stream in step (1) is one or more of petroleum-based, coal-based, and biomass-based hydrocarbon-containing materials, preferably a petroleum-based hydrocarbon-containing product, and more preferably kerosene or diesel fractions.

8. The method according to claim 1, characterized in that: The ratio of petroleum coke to organic stream in step (1) is 0.01 to 1:1, preferably 0.05 to 0.3:1, in g / mL.

9. The method according to claim 1, characterized in that: The mass ratio of alkali metal to petroleum coke in step (1) is 0.01-0.5:1, preferably 0.05-0.2:

1.

10. The method according to claim 1, characterized in that: The desulfurization reaction temperature in step (1) is 200-500°C, preferably 300-400°C.

11. The method according to claim 1, characterized in that: The inert atmosphere in step (2) is nitrogen and / or an inert gas, preferably nitrogen. The inert gas is at least one of helium, neon, argon, krypton and xenon.

12. The method according to claim 1, characterized in that: The gas partial pressure of the inert atmosphere in step (2) is 0.1-1 MPa, preferably 0.1-0.3 MPa.

13. The method according to claim 1, characterized in that: The carbonization reaction temperature in step (2) is 500-900°C, preferably 600-700°C.

14. The method according to claim 1, characterized in that: The drying conditions in step (3) are as follows: the drying temperature is 80 to 400° C., preferably 120 to 350° C., the drying time is 2 to 8 hours, preferably 4 to 6 hours, and the drying is preferably carried out under vacuum conditions.

15. A modified petroleum coke obtained by the method of any one of claims 1 to 14.

16. The modified petroleum coke according to claim 15, 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, true density 1.8~2.5 g / cm 3 , volatile matter is less than 9%.

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