Selective hydrotreating method for aromatic-rich raw material

Abstract

The invention discloses an aromatic-rich raw material selective hydrotreating method which comprises the following steps: S1, mixing an aromatic-rich raw material with hydrogen, crushing the hydrogen into microbubbles, and dispersing the microbubbles in the aromatic-rich raw material to form a gas-liquid emulsion material flow; s2, the gas-liquid emulsion flow sequentially passes through an up-flow fixed bed reactor and a trickle bed reactor which are connected in series for hydrogenation, and the reaction temperature of the up-flow fixed bed reactor is 5-20 DEG C lower than that of the trickle bed reactor; s3, a reactant flowing out of the trickle bed reactor is separated into a gas phase and a liquid phase, the gas phase is discharged, the liquid phase is divided into a light oil fraction and a heavy oil fraction after fractionation, part of the heavy oil fraction serves as circulating oil to be mixed with the aromatic-rich raw material, and the remaining heavy oil fraction and the light oil fraction serve as the needle coke raw material. According to the method, the over-saturation of aromatic hydrocarbon can be inhibited while the impurities are efficiently removed, the long-period stable operation of the device is realized, and the product meets the requirements of producing the needle coke.

Description

Technical Field

[0001] The present invention belongs to the technical field of petrochemical hydrogenation, and particularly relates to a method for selectively hydrogenating and treating aromatic-rich raw materials. Background Art

[0002] With the booming development of new energy technologies, the demand for carbon materials used in battery anodes is strong and the added value is relatively high. Heavy crude oils rich in aromatics, catalytic oil slurries and ethylene tar in secondary processed oils are all theoretically ideal raw materials for producing carbon materials. However, due to the high content of polycyclic aromatic hydrocarbons and high contents of impurities such as sulfur, nitrogen, metals and ash in these raw materials, there is currently no representative high-efficiency processing and utilization technology.

[0003] At present, the fixed-bed process in the hydrogenation and impurity removal technology for aromatic-rich heavy oil raw materials is mature, easy to operate, and has a relatively low device investment, and can be used as a pretreatment technology for petroleum-based carbon material raw materials. However, the traditional fixed-bed hydrogenation and impurity removal technology mainly uses trickle-bed reactors, which require maintaining a high hydrogen-oil volume ratio under a certain hydrogen partial pressure, making the continuous phase in the reactor gas and the dispersed phase liquid. Therefore, a large amount of recycle hydrogen is required for mass transfer and heat transfer between phases, and a recycle hydrogen system needs to be set up, resulting in high energy consumption and large investment. When processing raw materials with high polycyclic aromatic hydrocarbon content and high metal content, the catalyst is prone to coke formation and deactivation and caking, causing the pressure drop in the reactor to rise rapidly in a short period of time and leading to shutdown, affecting the long-term operation of the device. At the same time, the loss of aromatics is relatively large, which is not conducive to the further production of needle coke from the product.

[0004] Patent CN101250433B discloses a coal tar hydrogenation process. The coal tar is pretreated to obtain a coal tar hydrogenation feedstock, and then passes through a series of up-flow pre-hydrogenation fixed-bed reactors and down-flow main hydrogenation fixed-bed reactors, and gasoline fractions, diesel fractions and light fuel oil fractions are obtained through fractionation; the purpose of this process is to produce fuel oil, and the gas-liquid mass transfer in the reaction system is poor and the investment is high.

[0005] Patent CN103789028B discloses a pretreatment method for producing needle coke raw materials from catalytic oil slurry, including subjecting the catalytic oil slurry to mild hydrogenation treatment after filtration, and 20% - 50% (by weight) of the hydrogenated product oil is sent to a vacuum distillation unit, and the hydrogenated light distillate oil obtained is mixed with the remaining hydrogenated product oil as the raw material for producing needle coke; the defect of this method is poor raw material adaptability. Summary of the Invention

[0006] The purpose of the present invention is to provide a method for selectively hydrogenating and treating aromatic-rich raw materials, which can efficiently remove impurities while suppressing the excessive saturation of aromatics, realize the long-term stable operation of the device, and the product meets the requirements for producing needle coke.

[0007] To achieve the above purpose, the present invention provides a method for selectively hydrogenating and treating aromatic-rich raw materials, including:

[0008] S1. Mix the aromatic-rich raw material with hydrogen to break the hydrogen into microbubbles and disperse them in the aromatic-rich raw material to form a gas-liquid emulsion stream.

[0009] S2. The gas-liquid emulsion stream is successively hydrogenated through an upflow fixed-bed reactor and a trickle-bed reactor connected in series. The reaction temperature of the upflow fixed-bed reactor is 5°C to 20°C lower than that of the trickle-bed reactor.

[0010] S3. Separate the reactants flowing out of the trickle-bed reactor into a gas phase and a liquid phase. The gas phase is discharged, and the liquid phase is fractionated into a light oil fraction and a heavy oil fraction after fractionation. Part of the heavy oil fraction is used as recycle oil and mixed with the aromatic-rich raw material, and the remaining heavy oil fraction and light oil fraction are raw materials for needle coke.

[0011] In the method for selective hydrotreating of aromatic-rich raw material of the present invention, in step S1, the diameter of the microbubbles is 10 to 1000 μm.

[0012] In the present invention, no specific limitations are imposed on the equipment for mixing the aromatic-rich raw material with hydrogen, the equipment for gas-liquid separation, and the equipment for fractionation. They are all commonly used equipment in the art, and those skilled in the art can select or adjust according to the actual situation. For example, the equipment for mixing the aromatic-rich raw material with hydrogen can be a combination of one or more of a metal tube bundle, a porous ceramic membrane, a Venturi tube, a shear pump, etc.; the equipment for gas-liquid separation can be a combination of conventional high-pressure / low-pressure gas-liquid separators; the equipment for fractionation can be a combination of a stripping column and a fractionating column.

[0013] In the method for selective hydrotreating of aromatic-rich raw material of the present invention, the aromatic-rich raw material is one or several of catalytic oil slurry, deasphalted oil, residue oil, furfural extract oil, and ethylene tar with an ash content not higher than 350 ppm.

[0014] In the method for selective hydrotreating of aromatic-rich raw material of the present invention, the upflow fixed-bed reactor is filled with a hydrogenation protective agent and a hydrotreating agent in sequence along the flow direction of the material. Based on the total catalyst volume in the upflow fixed-bed reactor, the filling volume percentages of the hydrogenation protective agent and the hydrotreating agent are 50 to 100% and 0 to 50% respectively. The feed inlet of the upflow reactor is arranged at the bottom of the reactor, and the material in the reactor flows through the catalyst bed layer from bottom to top in sequence.

[0015] The selective hydrotreating method for aromatic-rich raw materials according to the present invention, in the trickle-bed reactor, a hydrogenation protective agent, a hydrogenation pretreatment agent, and a hydrogenation refining agent are filled in sequence along the material flow direction. Based on the total catalyst volume in the trickle-bed reactor, the filling volume percentages of the hydrogenation protective agent, the hydrogenation pretreatment agent, and the hydrogenation refining agent are 5-35%, 10-50%, and 15-85% respectively. The feed inlet of the trickle-bed reactor is arranged at the top of the reactor, and the materials in the reactor flow through the catalyst bed layer from top to bottom in sequence.

[0016] The selective hydrotreating method for aromatic-rich raw materials according to the present invention, the hydrogenation protective agent is configured in a hierarchical pore size structure of millimeter-micron-nanometer in accordance with the material flow direction. The proportion of the hydrogenation protective agent with a pore size of 1-10 mm is 5-40%; the proportion of the hydrogenation protective agent with a pore size of 10-300 μm is 30-50%; the proportion of the hydrogenation protective agent with a pore size of 100-900 nm is 10-65%.

[0017] In the present invention, the hydrogenation protective agent, the hydrogenation pretreatment agent, and the hydrogenation refining agent are all commonly used catalysts in the art, and the specific types of the hydrogenation protective agent, the hydrogenation pretreatment agent, and the hydrogenation refining agent are not specifically limited in the present invention. The hydrogenation pretreatment agent and the hydrogenation refining agent respectively comprise a carrier and an active component supported on the carrier; the hydrogenation protective agent may or may not contain an active component; the carrier is an inorganic oxide, and the active components are independently selected from Group VIB metals and / or Group VIII metals; wherein the Group VIB metal is selected from W and / or Mo; the Group VIII metal is selected from Co and / or Ni.

[0018] The hydrogenation pretreatment agent and the hydrogenation refining agent are in an ex-situ pre-sulfided state or an oxidized state. When the hydrogenation pretreatment agent and the hydrogenation refining agent are in an oxidized state, in-situ sulfidation is required. When in-situ sulfidation is carried out, the sulfidation method is selected from dry sulfidation or wet sulfidation. When in-situ sulfidation is carried out, the sulfiding agents are independently selected from one or more of H 2 S, mercaptan, dimethyl sulfide, polysulfide, and thiophenecarboxylic acid compounds. The polysulfide is selected from carbon disulfide and / or dimethyl disulfide.

[0019] The selective hydrotreating method for aromatic-rich raw materials according to the present invention, the pore volume of the hydrogenation pretreatment agent is not less than 0.60 mL / g, and the average pore diameter is 12-30 nm.

[0020] The selective hydrotreating method for aromatic-rich raw materials according to the present invention, the pore volume of the hydrogenation refining agent is not less than 0.50 mL / g, and the average pore diameter is 6-12 nm.

[0021] The selective hydrotreating method for the aromatic-rich raw material of the present invention, the process conditions of the upflow fixed-bed reactor and the trickle-bed reactor are as follows: hydrogen partial pressure is 2.0 MPa to 18.0 MPa, preferably 4.0 MPa to 10.0 MPa; temperature is 280 °C to 410 °C, preferably 300 °C to 395 °C; the volume hourly space velocity of the aromatic-rich raw material is 0.1 h -1 ~1.0 h -1 ,preferably 0.2 h -1 ~0.6 h -1 。

[0022] In the selective hydrotreating method for the aromatic-rich raw material of the present invention, the heavy oil fraction is a fraction of ≥ 350 °C.

[0023] In the selective hydrotreating method for the aromatic-rich raw material of the present invention, the recycle oil accounts for 20% to 80% of the mass of the heavy oil fraction.

[0024] Advantages of the present invention:

[0025] 1. The present invention eliminates the recycle hydrogen system, effectively reducing the investment cost;

[0026] 2. Adopting the liquid-phase hydrogenation mode, reducing the radial temperature difference in the reactor, which is beneficial to the long-term stable operation of the device;

[0027] 3. Adopting the upflow fixed-bed reactor, effectively suppressing the increase in pressure drop, improving the raw material adaptability, and ensuring the long-term stable operation of the device;

[0028] 4. Through the optimization of the catalyst loading and grading scheme, improving the selective hydrogenation performance of the catalyst, preventing the excessive hydrogenation saturation of three-ring and four-ring aromatic hydrocarbons, which is beneficial to the hydrogenated product as a raw material for preparing carbon materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic flow chart of the selective hydrotreating method for the aromatic-rich raw material of the present invention.

[0030] Among them, reference numerals:

[0031] 1: Aromatic-rich raw material;

[0032] 2: Hydrogen;

[0033] 3: Enhanced hydrogen mixing unit;

[0034] 4: Upflow fixed-bed reactor;

[0035] 5: Trickle-bed reactor;

[0036] 6: Gas-liquid separation unit;

[0037] 7: Fractionation unit;

[0038] 8: Recirculating oil. Detailed implementation mode

[0039] The present invention will be specifically described below through embodiments. It is necessary to point out here that the following embodiments are only used to further illustrate the present invention and cannot be construed as limiting the protection scope of the present invention. Those skilled in the art can make some non-essential improvements and adjustments to the present invention based on the above content of the present invention.

[0040] In the method for selective hydrotreating of aromatic-rich raw materials provided by the present invention, the aromatic-rich raw material 1 and the recirculating oil 8 are mixed and then together with hydrogen 2 pass through the enhanced hydrogen mixing unit 3 to form a gas-liquid emulsion stream. After flowing upward through the upflow fixed-bed reactor 4 and the catalyst bed layer therein, it then flows downward through the trickle-bed reactor 5 and the catalyst bed layer therein. The material after the hydrogenation reaction enters the gas-liquid separation unit 6, and the liquid-phase stream enters the fractionation unit 7. A part of the heavy oil fraction fractionated is used as the recirculating oil 8.

[0041] The sources of the main materials involved in the examples and comparative examples of the present invention are shown in Table 1 below. Other materials not specified are all commercially available products.

[0042] Table 1 Description of material sources

[0043] Serial Number Product Specification / Model Manufacturer 1 Catalytic Oil Slurry Product of Fluid Catalytic Cracking Unit Urumqi Petrochemical Company 2 Deasphalted Oil Product of Deasphalting Unit Karamay Petrochemical Company 3 Vacuum Residue Atmospheric and Vacuum Distillation Unit Daqing Petrochemical Company 4 Furfural Extracted Oil Furfural Extraction Unit Daqing Petrochemical Company 5 Ethylene Tar Ethylene Cracking Unit Jilin Petrochemical Company 6 Hydrogenation Protective Agent PHR-401 / 402 / 403 / 404 Fushun Catalyst Factory 7 Hydrogenation Pretreatment Agent PHR-103 / PHR-201 Fushun Catalyst Factory 8 Hydrogenation Refining Agent PHR-301 Fushun Catalyst Factory

[0044] Table 2 Catalyst types and volume ratios of the dosages of various types of catalysts

[0045]

[0046] Example 1

[0047] Adopt as Figure 1 The process flow schematic diagram shown. The main properties and operating conditions of the raw materials used are shown in Table 3 and Table 4, and the evaluation results are shown in Table 5.

[0048] The upflow fixed-bed reactor is filled with 100% hydrogenation protective agent configured in a pore size structure gradient of millimeter-micron-nanometer in sequence along the material flow direction; the trickle-bed reactor is filled with 30% hydrogenation protective agent, 15% hydrogenation pretreatment agent, and 55% hydrogenation refining catalyst configured in a pore size structure gradient of millimeter-micron-nanometer in sequence along the material flow direction.

[0049] Wet sulfidation is adopted. The wet sulfidation refers to sulfiding the catalyst with an oil product carrying a sulfiding agent. The sulfidation process of the catalyst is specifically through the following steps:

[0050] The sulfiding agent uses hydrogen sulfide (H 2S), the addition amount is 2.0% of the feed amount of the sulfiding oil. The sulfiding oil uses the fourth side stream diesel of the atmospheric column. Hydrogen passes through once. The sulfiding conditions are to keep the temperature constant at 280 °C for 20 h, keep the temperature constant at 320 °C for 8 h, and the heating rate is 10 °C / h.

[0051] After the sulfiding is completed, switch to the evaluation feedstock for evaluation.

[0052] Example 2

[0053] Adopt the Figure 1 shown process flow schematic diagram. The main properties and operating conditions of the raw materials used are shown in Table 3 and Table 4, and the evaluation results are shown in Table 5.

[0054] In the up-flow fixed bed reactor, 80% of the hydrogenation protective agent and 20% of the hydrogenation pretreatment agent are loaded in sequence along the material flow direction in a pore size structure gradient configuration of millimeter-micron-nanometer; in the trickle bed reactor, 20% of the hydrogenation protective agent, 20% of the hydrogenation pretreatment agent, and 60% of the hydrogenation refining catalyst are loaded in sequence along the material flow direction in a pore size structure gradient configuration of millimeter-micron-nanometer.

[0055] Wet sulfiding is adopted. The wet sulfiding means using an oil product to carry a sulfiding agent to carry out sulfiding treatment on the catalyst. The sulfiding process of the catalyst is specifically carried out through the following steps:

[0056] The sulfiding agent uses carbon disulfide (CS 2 ), the addition amount is 2.0% of the feed amount of the sulfiding oil. The sulfiding oil uses the fourth side stream diesel of the atmospheric column. Hydrogen passes through once. The sulfiding conditions are to keep the temperature constant at 280 °C for 20 h, keep the temperature constant at 320 °C for 8 h, and the heating rate is 10 °C / h.

[0057] After the sulfiding is completed, switch to the evaluation feedstock for evaluation.

[0058] Example 3

[0059] Adopt the Figure 1 shown process flow schematic diagram. The main properties and operating conditions of the raw materials used are shown in Table 3 and Table 4, and the evaluation results are shown in Table 5.

[0060] In the up-flow fixed bed reactor, 60% of the hydrogenation protective agent and 40% of the hydrogenation pretreatment agent are loaded in sequence along the material flow direction in a pore size structure gradient configuration of millimeter-micron-nanometer; in the trickle bed reactor, 30% of the hydrogenation protective agent, 15% of the hydrogenation pretreatment agent, and 55% of the hydrogenation refining catalyst are loaded in sequence along the material flow direction in a pore size structure gradient configuration of millimeter-micron-nanometer.

[0061] Wet sulfiding is adopted. The wet sulfiding means using an oil product to carry a sulfiding agent to carry out sulfiding treatment on the catalyst. The sulfiding process of the catalyst is specifically carried out through the following steps:

[0062] The vulcanizing agent used is dimethyl disulfide (DMDS), and the addition amount is 2.0% of the feed amount of the vulcanizing oil. The vulcanizing oil used is the fourth normal paraffin diesel. Hydrogen passes through once, and the vulcanizing conditions are to keep the temperature constant at 280 °C for 20 h and then keep the temperature constant at 320 °C for 8 h, with a heating rate of 10 °C / h.

[0063] After vulcanization is completed, switch to the evaluation raw material for evaluation.

[0064] Example 4

[0065] Adopt the Figure 1 process flow schematic diagram shown. The main properties and operating conditions of the raw materials used are shown in Table 3 and Table 4, and the evaluation results are shown in Table 5.

[0066] In the up-flow fixed-bed reactor, 85% of the hydrogenation protective agent and 15% of the hydrogenation pretreatment agent are loaded in sequence along the material flow direction in a pore size structure gradient configuration of millimeter-micron-nanometer; in the trickle-bed reactor, 30% of the hydrogenation protective agent, 15% of the hydrogenation pretreatment agent, and 55% of the hydrogenation refining catalyst are loaded in sequence along the material flow direction in a pore size structure gradient configuration of millimeter-micron-nanometer.

[0067] Wet vulcanization is adopted, and the wet vulcanization means that the vulcanizing agent is carried by the oil product to vulcanize the catalyst.

[0068] The vulcanizing agent used is dimethyl disulfide (DMDS), and the addition amount is 1.8% of the feed amount of the vulcanizing oil. The vulcanizing oil used is the fourth normal paraffin diesel. Hydrogen passes through once, and the vulcanizing conditions are to keep the temperature constant at 280 °C for 20 h and then keep the temperature constant at 320 °C for 8 h, with a heating rate of 10 °C / h.

[0069] After vulcanization is completed, switch to the evaluation raw material for evaluation.

[0070] Example 5

[0071] Adopt the Figure 1 process flow schematic diagram shown. The main properties and operating conditions of the raw materials used are shown in Table 3 and Table 4, and the evaluation results are shown in Table 5.

[0072] In the up-flow fixed-bed reactor, 100% of the hydrogenation protective agent is loaded in sequence along the material flow direction in a pore size structure gradient configuration of millimeter-micron-nanometer; in the trickle-bed reactor, 30% of the pre-vulcanized hydrogenation protective agent, 15% of the pre-vulcanized hydrogenation pretreatment agent, and 55% of the pre-vulcanized hydrogenation refining catalyst are loaded in sequence along the material flow direction in a pore size structure gradient configuration of millimeter-micron-nanometer.

[0073] Wet vulcanization is adopted, and the wet vulcanization means that the vulcanizing agent is carried by the oil product to vulcanize the catalyst.

[0074] The vulcanizing agent used is ethyl mercaptan, and the addition amount is 1.8% of the feed amount of the vulcanizing oil. The vulcanizing oil used is the fourth normal paraffin diesel. Hydrogen passes through once. The vulcanizing conditions are to keep the temperature constant at 280 °C for 20 h and then keep the temperature constant at 320 °C for 8 h, with a heating rate of 10 °C / h.

[0075] After the vulcanization is completed, switch to the evaluation feedstock for evaluation.

[0076] Comparative Example 1

[0077] Two conventional trickle bed reactors in series are used. The catalysts loaded in the first and second trickle bed reactors, the vulcanizing conditions, the reaction pressure, the reaction temperature, the volume space velocity of the aromatic-rich feedstock, and the proportion of the recycle oil in the heavy oil fraction are the same as those of the upflow fixed bed reactor and the trickle bed reactor in Example 1 respectively. The difference is that Comparative Example 1 has a recycle hydrogen system. In the two conventional trickle bed reactors in series, the continuous phase is gas and the dispersed phase is liquid, and the hydrogen-oil volume ratio is 1200 V / V. The evaluation results are shown in Table 5.

[0078] Comparative Example 2

[0079] The difference between this comparative example and Example 2 is only that:

[0080] The hydrogenation reaction temperature of the upflow fixed bed reactor is different from that of the trickle bed reactor, and the former temperature is higher.

[0081] Comparative Example 3

[0082] The difference between this comparative example and Example 5 is only that:

[0083] The upflow fixed bed reactor is replaced by a trickle bed reactor.

[0084] Comparative Example 4

[0085] The difference between this comparative example and Example 1 is only that:

[0086] Part of the heavy oil fraction is not returned as recycle oil to the upflow fixed bed reactor.

[0087] The following Tables 3 and 4 are the evaluation feedstocks and process operation conditions of the above examples and comparative examples respectively. The specific contents are shown in the following tables.

[0088] Table 3 Main properties of the feedstock

[0089]

[0090]

[0091] Table 4 Process operation conditions

[0092]

[0093] Table 5 below shows the evaluation results of the above examples and comparative examples. In terms of the average value, the specific data results are shown in the following table.

[0094] Table 5 Evaluation Results

[0095]

[0096]

[0097] By comparing Tables 1 to 5, we can find that:

[0098] Under the condition that the product properties are basically the same, the operation cycle of Example 1 using Figure 1 the process is more than twice that of Comparative Example 1 using the process of two conventional trickle bed reactors in series;

[0099] Within the same operation cycle, using the same raw materials and Figure 1 the process flow, when the process conditions are different, compared with Comparative Example 2, Example 2 has comparable impurity contents such as sulfur, nitrogen, and asphaltene in the product, but less loss of aromatics;

[0100] The only difference between Comparative Example 3 and Example 5 is that the upflow fixed bed reactor in Example 5 is replaced with a trickle bed reactor, that is, two series-connected trickle bed reactors are used in Comparative Example 3. Compared with Example 5, Comparative Example 3 has more loss of aromatics and a shorter operation cycle;

[0101] The only difference between Comparative Example 4 and Example 1 is that in Comparative Example 4, part of the heavy oil fraction is not returned as recycle oil to the upflow fixed bed reactor. Compared with Example 1, the impurity contents such as sulfur, nitrogen, and asphaltene in the product of Comparative Example 4 are greatly increased, and the operation cycle is significantly shortened. Using the method provided by the present invention is not only beneficial to the long-term operation of the device, but also can effectively remove the raw material impurities while suppressing the excessive saturation of aromatics.

[0102] Application Example 1

[0103] Using the hydrogenated raw materials of Examples 1, 3, and 5, a needle coke preparation test was carried out to investigate the properties of the calcined needle coke products. The raw materials were loaded into a pot-type coking reactor, the pressure was controlled at 0.8 MPa, the temperature was raised to 410 °C at a heating rate of 5 °C / h, and when the temperature was raised to 490 °C, it was heated to 520 °C at a heating rate of 10 °C / h and held at this temperature for 2 h until the coking test ended. The coke taken out was calcined at 1400 °C for 4 h to obtain the calcined needle coke, numbered S-1, S-2, and S-3 in sequence, and the property results are shown in Table 6.

[0104] Application Comparative Example 1

[0105] Using the raw material after solid removal but without hydrogenation in Example 1 (comparative raw material) for the preparation test of needle coke, the properties of the calcined needle coke products were investigated. The raw material was charged into a autoclave reactor, the pressure was controlled at 0.8 MPa, variable temperature control was adopted, the temperature range was 410 - 490 °C, the variable temperature rate was 5 °C / h. When the temperature rose to 490 °C, it was heated to 520 °C at a rate of 10 °C / h and kept at this temperature for 2 h until the coking test ended. The obtained coke was calcined at 1400 °C for 4 hours to obtain the calcined needle coke, numbered D-1. The property results are shown in Table 6.

[0106] Table 6 Analysis of the properties of needle coke products

[0107]

[0108] As can be seen from Table 6, compared with the calcined needle coke product D-1, the thermal expansion coefficients of the calcined needle cokes S-1, S-2 and S-3 prepared from the raw materials after hydrogenation treatment by the present invention are significantly reduced, the ash content is lower, and the true density and volatile matter are comparable. It can thus be shown that: the raw materials prepared by the method of the present invention can be used as high-quality raw materials for graphite electrodes and anode materials.

[0109] Of course, the present invention may have many other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and deformations according to the present invention, but these corresponding changes and deformations should all fall within the protection scope of the claims of the present invention.

Claims

1. A method for selective hydrotreating of aromatic-rich raw materials, characterized in that, it includes: S1, mixing the aromatic-rich raw material with hydrogen to break the hydrogen into microbubbles and disperse them in the aromatic-rich raw material to form a gas-liquid emulsion stream; S2, the gas-liquid emulsion stream is successively hydrogenated through an up-flow fixed-bed reactor and a trickle-bed reactor connected in series, and the reaction temperature of the up-flow fixed-bed reactor is 5°C to 20°C lower than that of the trickle-bed reactor; S3, the reactants flowing out of the trickle-bed reactor are separated into a gas phase and a liquid phase. The gas phase is discharged, and the liquid phase is fractionated into a light oil fraction and a heavy oil fraction after fractionation. Part of the heavy oil fraction is used as recycle oil and mixed with the aromatic-rich raw material, and the remaining heavy oil fraction and the light oil fraction are raw materials for needle coke.

2. The method for selective hydrotreating of aromatic-rich raw materials according to claim 1, characterized in that, in step S1, the diameter of the microbubbles is 10 to 1000 μm.

3. The method for selective hydrotreating of aromatic-rich raw materials according to claim 1, characterized in that, the aromatic-rich raw material is one or more of catalytic oil slurry, deasphalted oil, residue oil, furfural extract oil and ethylene tar with an ash content not higher than 350 ppm.

4. The method for selective hydrotreating of aromatic-rich raw materials according to claim 1, characterized in that, the up-flow fixed-bed reactor is filled with a hydrotreating protective agent and a hydrotreating pretreatment agent in sequence according to the material flow direction. Based on the total catalyst volume in the up-flow fixed-bed reactor, the filling volume percentages of the hydrotreating protective agent and the hydrotreating pretreatment agent are 50 to 100% and 0 to 50% respectively.

5. The method for selective hydrotreating of aromatic-rich raw materials according to claim 1, characterized in that, the trickle-bed reactor is filled with a hydrotreating protective agent, a hydrotreating pretreatment agent and a hydrotreating refining agent in sequence according to the material flow direction. Based on the total catalyst volume in the trickle-bed reactor, the filling volume percentages of the hydrotreating protective agent, the hydrotreating pretreatment agent and the hydrotreating refining agent are 5 to 35%, 10 to 50% and 15 to 85% respectively.

6. The method for selective hydrotreating of aromatic-rich raw materials according to claim 4 or 5, characterized in that, the hydrotreating protective agent is configured in a pore size structure gradient of millimeter-micron-nanometer according to the material flow direction. The proportion of the hydrotreating protective agent with a pore size of 1 to 10 mm is 5 to 40%; the proportion of the hydrotreating protective agent with a pore size of 10 to 300 μm is 30 to 50%; the proportion of the hydrotreating protective agent with a pore size of 100 to 900 nm is 10 to 65%.

7. The method for selective hydrotreating of aromatic-rich raw materials according to claim 4 or 5, characterized in that, the pore volume of the hydrotreating pretreatment agent is not less than 0.60 mL / g, and the average pore size is 12 to 30 nm.

8. The method for selective hydrotreating of aromatic-rich raw materials according to claim 5, characterized in that, the pore volume of the hydrotreating refining agent is not less than 0.50 mL / g, and the average pore size is 6 to 12 nm.

9. The method for selective hydrotreating of aromatic-rich raw materials according to claim 1, characterized in that, The process conditions of the above-mentioned up-flow fixed-bed reactor and trickle-bed reactor are as follows: hydrogen partial pressure is 2.0 MPa to 18.0 MPa, preferably 4.0 MPa to 10.0 MPa; temperature is 280 °C to 410 °C, preferably 300 °C to 395 °C; the volume hourly space velocity of the aromatic-rich feedstock is 0.1 h -1 ~1.0 h -1 , preferably 0.2 h -1 ~0.6 h -1 .

10. The method for selective hydrotreating of aromatic-rich raw materials according to claim 1, characterized in that, the heavy oil fraction is a fraction with a boiling point of ≥350°C.

11. The selective hydrotreating method for aromatic-rich raw materials according to claim 1, characterized in that, the recycled oil accounts for 20% to 80% of the mass of the heavy oil fraction.

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