Method for preparing needle coke
By using a desulfurization adsorbent to contact heavy hydrocarbon oil for desulfurization treatment, combined with fractionation and coking processes, the problem of producing high-quality needle coke from petroleum feedstock has been solved, achieving the production of low-sulfur, high-density needle coke while maintaining the integrity of the aromatic structure.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-21
- Publication Date
- 2026-04-21
AI Technical Summary
Existing technologies struggle to effectively utilize petroleum feedstocks to produce high-quality needle coke, particularly due to issues such as gas expansion and insufficient true density during graphitization caused by high sulfur content.
Desulfurization is carried out by contacting heavy hydrocarbon oil with a desulfurization adsorbent in the presence of hydrogen to obtain desulfurized heavy hydrocarbon oil with a sulfur content of less than 0.5 wt%. Needle coke is then prepared by fractionation and coking. The desulfurization adsorbent is composed of a carrier and an active metal promoter. The carrier includes alumina, silicon oxide and zinc oxide, and the active metal is selected from cobalt, nickel and other materials.
It has achieved the production of high-quality needle coke with a sulfur content of less than 0.5% and a true density of more than 2.13 g/cm3, which maintains the aromatic structure in heavy hydrocarbon oil and avoids the loss of aromatic saturation.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of petrochemicals. Specifically, it is a method for removing sulfides from sulfur-containing heavy hydrocarbon oils using adsorption desulfurization and producing high-quality needle coke from the desulfurized heavy hydrocarbon oils. Background Technology
[0002] With the rapid development of electric vehicles, the demand for anode materials is increasing, as is the demand for needle coke used in their production. Needle coke exhibits a distinct layered structure and streamlined texture, with slender needle-like particles exhibiting significant anisotropy. Its molecular structure displays a considerable degree of ordered arrangement and possesses good graphitization properties. The quality of needle coke, such as its sulfur content and true density, significantly impacts the performance of the resulting electrode materials. For example, a high content of heteroatoms, such as sulfur, in needle coke can cause gas expansion during the graphitization process, leading to electrode cracks and reduced product quality. Therefore, a sulfur content of <0.5% is required for needle coke. Higher true density indicates a denser material structure, more orderly microcrystal arrangement, and a higher degree of graphitization. Therefore, high-quality needle coke requires a high true density. For instance, GB / T 37308-2019 and YB / T4910-2021 both require a true density greater than 2.13 g / cm³ for high-quality oil-based needle coke. 3 .
[0003] Currently, needle coke includes coal-based needle coke and petroleum-based needle coke. However, most of the needle coke that meets the requirements is currently coal-based. There is a need in the field for further methods to produce high-quality needle coke using petroleum feedstocks. Summary of the Invention
[0004] This application provides a method for preparing needle coke, comprising:
[0005] S1 desulfurizes heavy hydrocarbon oil feedstock by contacting it with a desulfurization adsorbent in the presence of hydrogen, resulting in desulfurized heavy hydrocarbon oil with a sulfur content of less than 0.5 wt%.
[0006] S2 fractionates the desulfurized heavy hydrocarbon oil to obtain an intermediate fraction with a distillation range of 310–550°C.
[0007] S3 processes the middle distillate in a coking unit to obtain needle coke.
[0008] The desulfurization adsorbent comprises a carrier and an active metal promoter loaded on the carrier. The carrier comprises 10-50 wt% alumina, 0-20 wt% silica, and 10-90 wt% zinc oxide, based on the total weight of the carrier. The active metal promoter is a reduced metal selected from one or more of cobalt, nickel, copper, iron, manganese, molybdenum, tungsten, silver, tin, vanadium, platinum, and palladium. The active metal promoter accounts for 2-35 wt% of the desulfurization adsorbent, based on the total weight of the desulfurization adsorbent.
[0009] In one embodiment, the conditions for desulfurization treatment include:
[0010] The temperature is 300–550℃, preferably 350–500℃;
[0011] The absolute pressure is 0.1–10 MPa, preferably 1.0–6 MPa;
[0012] The heavy hourly space velocity (WHSV) of hydrocarbon oil feedstock is 0.2–10 h⁻¹. -1 Optimal time: 0.5-5 hours -1 ;
[0013] The hydrogen-to-oil volume ratio is 50–5000, preferably 100–2500.
[0014] In one embodiment, the method of this application further includes stripping the desulfurization adsorbent to be produced, oxygen-containing regeneration treatment, and reduction treatment.
[0015] Among them, the stripping process includes stripping the nascent desulfurization adsorbent using light hydrocarbon oil and / or hydrogen as the stripping medium.
[0016] The oxygen-containing regeneration treatment involves contacting the stripped desulfurization adsorbent with oxygen-containing gas under regeneration conditions. The regeneration conditions include: a regeneration temperature of 350–800℃, preferably 450–600℃, and a regeneration pressure of 0.01–3.0 MPa, preferably 0.01–1.0 MPa.
[0017] The reduction treatment involves contacting the regenerated catalyst with hydrogen-containing gas under reduction conditions. The reduction conditions include: a reduction temperature of 300–550°C, preferably 350–500°C; an absolute pressure of 0.1–10 MPa, preferably 0.1–6 MPa; and a hydrogen gas fraction greater than or equal to 30% in the hydrogen-containing gas.
[0018] In one embodiment, the light hydrocarbon oil is one or a mixture of two or more of naphtha, gasoline or light diesel oil with a final boiling point not exceeding 280°C, preferably not exceeding 250°C.
[0019] In one embodiment, the desulfurization adsorbent is in the form of microspheres, small spheres, strips, Raschig rings, or clover.
[0020] In one embodiment, the sulfur mass fraction in the desulfurized heavy hydrocarbon oil is less than 0.4%; the distillation range of the middle fraction is 330–500°C.
[0021] In one embodiment, the coking conditions include: a reaction pressure of atmospheric pressure to 3.0 MPa, a temperature of 450–700 °C, and a coking time of 5 to 50 hours.
[0022] In one embodiment, the heavy hydrocarbon feedstock is a hydrocarbon oil fraction with an initial boiling point greater than 180°C, including one or a mixture of two or more of straight-run diesel, catalytic cracked diesel, atmospheric residue, vacuum residue, wax oil, and slurry oil.
[0023] Preferably, the density of the heavy hydrocarbon oil is 0.82 g / cm³. 3 The above-mentioned aromatic hydrocarbon mass fraction is greater than 40%, preferably greater than 50%.
[0024] In one embodiment, the desulfurization process is carried out in a fluidized bed, a moving bed, and a fixed bed.
[0025] The method of this invention couples the desulfurization of heavy hydrocarbon oil with the coking of the desulfurized product to prepare needle coke. The desulfurization method used has a high desulfurization rate without reducing the aromatic structure in the heavy hydrocarbon oil. The low-sulfur heavy hydrocarbon oil produced can be used to produce high-quality needle coke. Attached Figure Description
[0026] Figure 1 A schematic diagram of desulfurization using a fixed bed is shown;
[0027] Figure 2 A schematic diagram of desulfurization treatment using a moving bed is shown. Detailed Implementation
[0028] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. Through these descriptions, the features and advantages of the present application will become clearer and more apparent.
[0029] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments. Although various aspects of embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless specifically indicated otherwise.
[0030] Furthermore, the technical features involved in the different embodiments of this application described below can be combined with each other as long as they do not conflict with each other.
[0031] In petroleum processing, catalytic cracking slurry, a byproduct of catalytic cracking units, is difficult to further process and utilize due to its high density and high aromatic content. However, its high aromatic content, especially tricyclic and tetracyclic aromatics, makes it suitable as a feedstock for needle coke production, potentially serving as an effective pathway for refinery transformation and development.
[0032] This application provides a method for preparing needle coke using heavy hydrocarbon oil feedstock, comprising:
[0033] S1 desulfurizes heavy hydrocarbon oil feedstock by contacting it with a desulfurization adsorbent in the presence of hydrogen, resulting in desulfurized heavy hydrocarbon oil with a sulfur content of less than 0.5 wt%.
[0034] S2 fractionates the desulfurized heavy hydrocarbon oil to obtain an intermediate fraction with a distillation range of 310–550°C.
[0035] S3 processes the middle distillate in a coking unit to obtain needle coke.
[0036] The desulfurization adsorbent comprises a carrier and an active metal promoter loaded on the carrier. The carrier comprises 10-50 wt% alumina, 0-20 wt% silica, and 10-90 wt% zinc oxide, based on the total weight of the carrier. The active metal promoter is a reduced metal selected from one or more of cobalt, nickel, copper, iron, manganese, molybdenum, tungsten, silver, tin, vanadium, platinum, and palladium. The active metal promoter accounts for 2-35 wt% of the desulfurization adsorbent, based on the total weight of the desulfurization adsorbent.
[0037] The following sections describe each step of the method described in this application.
[0038] The method described in this application involves contacting a heavy hydrocarbon oil feedstock with a desulfurization adsorbent in the presence of hydrogen to perform desulfurization treatment, thereby obtaining a desulfurized heavy hydrocarbon oil with a sulfur content of less than 0.5 wt%.
[0039] In one embodiment, the conditions for desulfurization treatment include:
[0040] The temperature is 300–550℃, preferably 350–500℃;
[0041] The absolute pressure is 0.1–10 MPa, preferably 1.0–6 MPa;
[0042] The heavy hourly space velocity (WHSV) of hydrocarbon oil feedstock is 0.2–10 h⁻¹. -1 Optimal time: 0.5-5 hours -1 ;
[0043] The hydrogen-to-oil volume ratio is 50–5000, preferably 100–2500.
[0044] The desulfurization adsorbent used in the method of this application includes a support and an active metal promoter loaded on the support. The support comprises 10-50 wt% alumina, 0-20 wt% silica, and 10-90 wt% zinc oxide, based on the total weight of the support. The active metal promoter is a reduced metal selected from one or more of cobalt, nickel, copper, iron, manganese, molybdenum, tungsten, silver, tin, vanadium, platinum, and palladium. The active metal promoter accounts for 2-35 wt% of the desulfurization adsorbent, based on the total weight of the desulfurization adsorbent.
[0045] A carrier is obtained by mixing, shaping, drying, and calcining alumina, silica, and zinc oxide components. This carrier is then mixed with a precursor solution containing salts or other precursors of the active metal promoter components, and subjected to impregnation, drying, and calcination to obtain an adsorbent loaded with promoter metal oxides. The reduced promoter components can be obtained by reduction, such as reduction with hydrogen, before use. The desulfurization adsorbent can be in the form of microspheres, small spheres, strips, Raschig rings, or cloverleaf shapes, or other shapes that meet the requirements of the corresponding reactor for effective reaction.
[0046] The heavy hydrocarbon feedstock used in this application is a hydrocarbon oil fraction with an initial boiling point greater than 180°C, including one or a mixture of two or more of straight-run diesel, catalytic cracked diesel, kerosene, atmospheric residue, vacuum residue, wax oil, and slurry oil; preferably, the density of the heavy hydrocarbon oil is 0.82 g / cm³. 3 The aromatic hydrocarbon mass fraction is greater than 40%, preferably greater than 50%. The sulfur mass fraction is between 0.1% and 5.0%, preferably between 0.5% and 3.5%.
[0047] After the adsorbent is loaded with sulfur and carbon, its desulfurization activity decreases. In order to achieve good separation between the adsorbent and hydrocarbon oil, the method of this application also includes stripping, oxygen regeneration and reduction treatment of the adsorbent.
[0048] Stripping involves stripping the nascent desulfurization adsorbent using light hydrocarbon oil and / or hydrogen as the stripping medium. In one embodiment, the desulfurization adsorbent with reduced activity is stripped by contacting it with light hydrocarbon oil. The light hydrocarbon oil can be one or a mixture of two or more of naphtha, gasoline, or light diesel oil with a final boiling point not exceeding 280°C, preferably not exceeding 250°C, or it can be a C3-C12 single hydrocarbon or a mixture of two or more single hydrocarbons.
[0049] The desulfurization adsorbent stripped with light hydrocarbon oil and / or hydrogen is purged using inert stripping until the volume content of hydrogen and hydrocarbons in the purge gas is less than 0.5%, preferably less than 0.1%. Afterwards, an oxygen-containing regeneration treatment is performed. This treatment involves contacting the stripped desulfurization adsorbent with an oxygen-containing gas under regeneration conditions. These conditions include a regeneration temperature of 350–800°C, preferably 450–600°C, and a regeneration pressure of 0.01–3.0 MPa, preferably 0.01–1.0 MPa. The oxygen-containing gas can be air or a mixture of air or oxygen with inert gases such as nitrogen or CO2. The regenerated desulfurization adsorbent (hereinafter referred to as the regenerated adsorbent) is stripped using an inert gas to remove oxygen. This inert gas can be nitrogen, CO2, or other inert gases or mixtures thereof to reduce the oxygen carried by the regenerated adsorbent. The oxygen volume content in the purge tail gas is less than 0.5%, preferably less than 0.1%.
[0050] The regenerated adsorbent, after passing the purging process, is further reduced. The reduction treatment involves contacting the regenerated catalyst with hydrogen-containing gas under reduction conditions. These conditions include: a reduction temperature of 300–550°C, preferably 350–500°C; an absolute pressure of 0.1–10 MPa, preferably 0.1–6 MPa; and a hydrogen fraction greater than or equal to 30% in the hydrogen-containing gas. The reduced regenerated adsorbent can then be contacted again with a mixture of sulfur-containing heavy hydrocarbon oil and hydrogen for further desulfurization treatment.
[0051] The desulfurization treatment described in this application can be carried out in fluidized bed, moving bed, and fixed bed.
[0052] Figure 1This diagram illustrates a fixed-bed desulfurization process. Sulfur-containing heavy hydrocarbon feedstock from pipeline 1 is mixed with circulating hydrogen from pipeline 11, preheated to the required temperature, and then enters the desulfurization reactor R1 via pipeline 3. There, it contacts the desulfurization adsorbent and undergoes a desulfurization reaction. The resulting oil and gas are separated from the desulfurization adsorbent and sent to the gas-liquid separator V1 via pipelines 5 and 7. The separated liquid desulfurization product is discharged from the system via pipeline 8, while the separated gas is mixed with fresh hydrogen from pipeline 10 via pipeline 9 and used as circulating hydrogen. After the desulfurization adsorbent in reactor R1 is deactivated, the heavy hydrocarbon feedstock enters reactor R2 via pipelines 2 and 4 to continue the desulfurization reaction. After the heavy oil and hydrogen feeds to reactor R1 are cut off, inert nitrogen gas enters R1 via pipelines 21 and 23 to purge the reactor. The purging gas then enters the oil collection tank V2 via pipelines 24 and 26 to separate the purging hydrocarbon oil from the purging gas. After passing inert gas purging, the R1 desulfurization reactor undergoes a regeneration reaction by contacting oxygen-containing gas from pipelines 31 and 23. The regenerated tail gas is then sent to the tail gas treatment system V2 via pipelines 24 / 29 and 30. After regeneration, the R1 desulfurization adsorbent is again purged with inert gas from pipelines 21 and 23 to remove oxygen. The desulfurization adsorbent in the R1 reactor, after passing oxygen purging, undergoes a reduction reaction with hydrogen. The reduced desulfurization adsorbent can then be contacted again with sulfur-containing heavy hydrocarbon oil and hydrogen for another desulfurization reaction.
[0053] Figure 2 The diagram illustrates a moving bed desulfurization process. Heavy hydrocarbon feedstock is mixed with hydrogen, preheated to the required temperature, and then fed into the desulfurization reactor 102 via pipeline 101. There, it contacts the desulfurization adsorbent and undergoes a desulfurization reaction. The reacted oil and gas are separated from the adsorbent and sent to a subsequent separation unit via pipeline 103. The regenerated adsorbent is then transported to the reactor receiver 105 via pipeline 104. In the reactor receiver, it undergoes light hydrocarbon stripping and then enters the closed-loop feeder 107 via pipeline 106. After further hydrogen stripping, it enters the closed-loop hopper 109 via pipeline 108, converting the high-pressure hydrogen-contaminated environment of the regenerated adsorbent to a low-pressure non-hydrogen-contaminated environment. The regenerated flue gas is then transported to the regenerator feed tank 112 via pipeline 111, and subsequently to the regenerator 114 via pipeline 113, where it contacts oxygen-containing gas from pipeline 115 for regeneration. The regenerated flue gas is then transported to the subsequent treatment system via pipeline 116. The regenerated adsorbent is transported via pipeline 117 to the regenerator receiver 118, and then via pipeline 119 into the closed hopper 109. After being converted in the closed hopper, the low-pressure oxygen-containing environment is transformed into a high-pressure hydrogen-containing environment. The regenerated adsorbent is then transported via pipeline 120 to the reactor feeder 121. After being reduced by hydrogen, the regenerated adsorbent is finally returned to the reactor 102 via pipeline 122 for further reaction. During the atmosphere conversion process in the closed hopper, the hydrogen-containing gas is discharged via pipeline 110 to the fuel network or flare.
[0054] This application has demonstrated that while hydrotreating (HDS) can remove sulfur from catalytic slurry, it also results in the loss of aromatics due to saturation. High aromatic saturation reduces the quality of the produced needle coke. In this application, the desulfurized heavy hydrocarbon oil achieves a sulfur mass fraction of less than 0.5%, particularly less than 0.4%, and a low aromatic saturation, effectively maintaining the aromatic content in the heavy hydrocarbon oil. The inventors have discovered that using such desulfurized heavy hydrocarbon oil, after fractionation and coking as described later in this application, yields high-quality needle coke with a low sulfur content (below 0.5%) and a high true density (above 2.13 g / cm³). 3 Even higher than 2.14 g / cm³ 3 This application can control the sulfur content and aromatic saturation rate by controlling the conditions of the desulfurization process, such as reaction time and hydrogen-to-oil volume ratio.
[0055] The inventors of this application have discovered that the suitable fraction for producing high-quality needle coke is a middle fraction with a boiling range of 310–550°C, preferably 330–500°C. Therefore, according to the method of this application, it is also necessary to fractionate the desulfurized heavy hydrocarbon oil after desulfurization treatment to obtain a middle fraction with a boiling range of 310–550°C (330–500°C). The fractionation treatment can be carried out in a fractionation tower, which will not be described in detail here. Typically, the aromatic hydrocarbon mass fraction in the middle fraction is not less than 50%, preferably not less than 60%, based on the total mass of the middle fraction.
[0056] According to the method of this application, the middle distillate is fed to a coking unit for coking to produce needle coke. The coking conditions include: a furnace outlet temperature of 420–550°C, preferably 430–530°C; a reaction pressure of atmospheric pressure to 3.0 MPa, preferably 0.2–1.0 MPa; a reaction temperature of 450–700°C; and a coking time of 5 to 50 hours, preferably 10–50 hours.
[0057] This yields high-quality needle coke with a true density greater than 2.13 g / cm³. 3 Preferred concentration: 2.14 g / cm³ 3 The sulfur mass fraction is less than 0.5%.
[0058] This invention utilizes a catalyst with high adsorption desulfurization activity for desulfurization, allowing the reaction to proceed at a relatively low hydrogen partial pressure. Furthermore, while achieving desulfurization of heavy hydrocarbon oils, the method minimizes aromatic saturation reactions and results in a low aromatic saturation rate. This desulfurized oil can then be used to produce high-quality needle coke with a true density greater than 2.13 g / cm³. 3 Preferred concentration: 2.14 g / cm³ 3 The sulfur mass fraction is less than 0.5%.
[0059] Example
[0060] The following examples will further illustrate the present invention, but are not intended to limit the invention. The basic properties of each feedstock oil are listed in Table 1.
[0061] Synthesis example 1
[0062] 30g of dispersed aluminum sol and 70g of zinc oxide powder were mixed evenly, and then 5% dilute nitric acid was added and extruded to obtain carrier A1. Carrier A1 was dried at 120℃ for 60 minutes and then calcined at 650℃ for 90 minutes. 98.94g of nickel nitrate hexahydrate and 24g of deionized water were mixed and then impregnated with 100g of the above carrier A1 to obtain the catalyst. After drying at 120℃ for 60 minutes, the catalyst was calcined at 650℃ for 90 minutes to obtain desulfurization adsorbent A.
[0063] Synthesis example 2
[0064] 60g of expanded perlite and 180g of zinc oxide were mixed and ground for 30 minutes to obtain mixture B1. Simultaneously, 50g of dispersed aluminum sol, 110g of deionized water, and 80g of 5% dilute nitric acid were mixed with mixture B1 to obtain mixture B2. After thorough stirring, the mixture was granulated to obtain microsphere carrier B3. Carrier B3 was dried at 120℃ for 60 minutes and calcined at 650℃ for 90 minutes. 98.94g of nickel nitrate hexahydrate was mixed with 24g of deionized water and then impregnated with 100g of the above carrier B3 for 8 hours. The resulting catalyst was dried at 120℃ for 60 minutes and calcined at 650℃ for 90 minutes to obtain desulfurization adsorbent B.
[0065] Comparative Synthesis Example 1
[0066] 18g of nickel nitrate hexahydrate was mixed with 72g of deionized water and then impregnated with 100g of γ-alumina microspheres obtained by extrusion for 4h. After drying at 120℃ for 60min and calcining at 650℃ for 90min, an intermediate was obtained. The intermediate was then mixed with a solution obtained by mixing 24g of ammonium molybdate and 72g of deionized water and impregnated for 4h. After drying at 120℃ for 60min and calcining at 650℃ for 90min, the catalyst NM / Al2O3 was obtained.
[0067] Example 1
[0068] 120 ml of adsorbent A was packed into a fixed-bed reactor. Wax oil A was used as a raw material, mixed with hydrogen gas, and then introduced into the reactor. The reaction was carried out at a pressure of 3 MPa, a hydrogen-to-oil volume ratio of 100, and a WHSV of 0.6 h⁻¹. -1 Desulfurization was carried out under reaction conditions at 430℃. The properties of the desulfurized oil are shown in Table 2.
[0069] The desulfurized oil was fractionated to obtain an intermediate fraction at 330–500°C, which was then sent to a coking unit. The reaction conditions were: furnace outlet temperature of 450–505°C, heating rate of 7°C / h, reaction pressure of 0.6 MPa, and reaction time of 43 h. The properties of the produced needle coke are listed in Table 3.
[0070] Example 2
[0071] 120 ml of adsorbent B was packed into a fixed-bed reactor. Oil slurry B was used as feedstock, mixed with hydrogen gas, and then introduced into the reactor. The reaction was carried out at a pressure of 3.0 MPa, a hydrogen-to-oil volume ratio of 100, and a WHSV of 0.6 h⁻¹. -1 Desulfurization was carried out under reaction conditions at 430℃. The results of the desulfurized oil slurry are listed in Table 2.
[0072] The desulfurized slurry obtained in Example 2 was fractionated to obtain an intermediate fraction at 330–500°C, which was then sent to a coking unit. The reaction conditions were: furnace outlet temperature of 450–505°C, heating rate of 7°C / h, reaction pressure of 0.6 MPa, and reaction time of 43 h. The properties of the produced needle coke are listed in Table 3.
[0073] Comparative Example 1
[0074] 120 ml of NM / Al2O3 adsorbent was packed into a fixed-bed reactor. Dimethyl disulfide (1.5% sulfur by mass) + cyclohexane was used as the pre-sulfurization feedstock. The reaction was carried out at a pressure of 6.0 MPa, a hydrogen-to-oil volume ratio of 1500, and a WHSV of 2.0 h⁻¹. -1 Under the following conditions, a programmed temperature-controlled pre-sulfurization process was performed: 150℃ was maintained for 2 hours, then the temperature was increased to 230℃ and maintained for 8 hours, then increased to 290℃ and maintained for 6 hours, and finally increased to 335℃ and maintained for 4 hours. Following this, a hydrodesulfurization reaction was carried out. Oil slurry B was used as feedstock, mixed with hydrogen, and then fed into the reactor. The reaction was carried out at a pressure of 6.0 MPa, a hydrogen-to-oil volume ratio of 700, and a WHSV of 0.6 h⁻¹. -1 Desulfurization was carried out under reaction conditions at a temperature of 365℃. The results of the desulfurized oil slurry are listed in Table 2.
[0075] The desulfurized oil slurry was fractionated to obtain an intermediate fraction at 330–500°C, which was then sent to the coking unit. The reaction conditions were: furnace outlet temperature of 450–505°C, heating rate of 7°C / h, reaction pressure of 0.6 MPa, and reaction time of 43 h. The properties of the produced needle coke are listed in Table 3.
[0076] Comparative Example 2
[0077] The oil slurry B was fractionated to obtain an intermediate fraction at 330–500°C, which was then sent to the coking unit. The reaction conditions were: furnace outlet temperature of 450–505°C, heating rate of 7°C / h, reaction pressure of 0.6 MPa, and reaction time of 43 h. The properties of the produced needle coke are listed in Table 3.
[0078] Table 1 Properties of Crude Oil
[0079] Wax Oil A Oil Slurry B Density, g / cm3 0.9651 1.088 Sulfur content, m% 1.57 0.757 Hydrogen content, m% 10.7 7.71 Aromatic content 62.77 87.2 Distillation range ASTM-D1160 - 0.5 296 110 10％ 418 376 50％ 441 438 90％ 471 629 99.5％ - -
[0080] Table 2 Properties of Desulfurized Oil Products
[0081] Example 1 Example 2 Comparative Example 1 Sulfur content, m% 0.36 0.33 0.35 Hydrogen content, m% 10.88 7.83 8.19 Aromatic hydrocarbon content, m% 62.32 87.6 83.4 Aromatic saturation, % 0.72 -0.45 4.36
[0082] Aromatic saturation rate refers to (aromatic content of feedstock oil - aromatic content of desulfurized oil) / aromatic content of feedstock oil * 100%
[0083] Table 3 Properties of needle char
[0084] Example 1 Example 2 Comparative Example 1 Comparative Example 2 Sulfur content, m% 0.38 0.31 0.33 0.73 Ash content, m% 0.10 0.12 0.13 0.14 Volatile matter, m% 4.59 4.93 5.47 6.17 <![CDATA[True density, g / cm 3 > 2.132 2.143 2.127 2.041 <![CDATA[Tap density, g / cm 3 > 0.90 0.93 0.87 0.82
[0085] The present application has been described above with reference to preferred embodiments; however, these embodiments are merely exemplary and illustrative. Various substitutions and modifications can be made to the present application based on these embodiments, all of which fall within the protection scope of the present application.
Claims
1. A method for preparing needle coke, comprising: S1 desulfurizes heavy hydrocarbon oil feedstock by contacting it with a desulfurization adsorbent in the presence of hydrogen, resulting in desulfurized heavy hydrocarbon oil with a sulfur content of less than 0.5 wt%. S2 fractionates the desulfurized heavy hydrocarbon oil to obtain an intermediate fraction with a distillation range of 310–550°C. S3 processes the middle distillate in a coking unit to obtain needle coke; The desulfurization adsorbent comprises a carrier and an active metal promoter loaded on the carrier. The carrier comprises 10-50 wt% alumina, 0-20 wt% silica, and 10-90 wt% zinc oxide, based on the total weight of the carrier. The active metal promoter is a reduced metal selected from one or more of cobalt, nickel, copper, iron, manganese, molybdenum, tungsten, silver, tin, vanadium, platinum, and palladium. The active metal promoter accounts for 2-35 wt% of the desulfurization adsorbent, based on the total weight of the desulfurization adsorbent.
2. The method according to claim 1, wherein, The conditions for desulfurization treatment include: The temperature is 300–550℃, preferably 350–500℃; The absolute pressure is 0.1–10 MPa, preferably 1.0–6 MPa; The heavy hourly space velocity (WHSV) of hydrocarbon oil feedstock is 0.2–10 h⁻¹. -1 Optimal time: 0.5-5 hours -1 ; The hydrogen-to-oil volume ratio is 50–5000, preferably 100–2500.
3. The method according to claim 1, wherein, It also includes stripping treatment, oxygen-containing regeneration treatment, and reduction treatment of the desulfurization adsorbent to be produced; Among them, the stripping process includes stripping the nascent desulfurization adsorbent using light hydrocarbon oil and / or hydrogen as the stripping medium. The oxygen-containing regeneration treatment involves contacting the stripped desulfurization adsorbent with oxygen-containing gas under regeneration conditions. The regeneration conditions include: a regeneration temperature of 350–800℃, preferably 450–600℃, and a regeneration pressure of 0.01–3.0 MPa, preferably 0.01–1.0 MPa. The reduction treatment involves contacting the regenerated catalyst with hydrogen-containing gas under reduction conditions. The reduction conditions include: a reduction temperature of 300–550°C, preferably 350–500°C; an absolute pressure of 0.1–10 MPa, preferably 0.1–6 MPa; and a hydrogen gas fraction greater than or equal to 30% in the hydrogen-containing gas.
4. The method according to claim 3, wherein, Light hydrocarbon oil is one or a mixture of two or more of naphtha, gasoline or light diesel oil with a final boiling point not exceeding 280°C, preferably not exceeding 250°C.
5. The method according to claim 1, wherein, The desulfurization adsorbent is in the form of microspheres, small spheres, strips, Raschig rings, or clover.
6. The method according to claim 1, wherein, The sulfur mass fraction in the desulfurized heavy hydrocarbon oil is less than 0.4%; the distillation range of the middle fraction is 330–500℃.
7. The method according to claim 1, wherein, The coking conditions include: reaction pressure from atmospheric pressure to 3.0 MPa, temperature of 450 to 700°C, and coking time of 5 to 50 hours.
8. The method according to claim 1, wherein, Heavy hydrocarbon feedstocks are hydrocarbon oil fractions with an initial boiling point greater than 180°C, including straight-run diesel, catalytic cracked diesel, atmospheric residue, vacuum residue, wax oil, and oil slurry, or a mixture of two or more of these. Preferably, the density of the heavy hydrocarbon oil is 0.82 g / cm³. 3 The above-mentioned aromatic hydrocarbon mass fraction is greater than 40%, preferably greater than 50%.
9. The method according to claim 1, wherein, Desulfurization treatment is carried out in fluidized bed, moving bed and fixed bed.