A method for pre-hydrogenation of a coal tar feedstock

Abstract

The present disclosure relates to a method for pre-hydrogenation of a coal tar raw material, which comprises: S1, mixing the coal tar raw material with a diluent and then performing solid-liquid separation to obtain a solid phase material and a liquid phase material; S2, under a hydrogenation condition, contacting the liquid phase material with a protective catalyst and an asphaltene hydroconversion catalyst to perform a hydrogenation reaction, and performing gas-liquid separation on the obtained hydrogenation reaction product. The method of the present disclosure can effectively remove impurities such as metals, ash and asphaltene in the coal tar raw material.

Description

Technical Field

[0001] This disclosure relates to the field of coal tar processing, and more specifically, to a method for pre-hydrogenating coal tar feedstock. Background Technology

[0002] my country is a country rich in coal, poor in oil, and scarce in natural gas. In 2020, its dependence on imported crude oil exceeded 72%, and this dependence has been increasing year by year. Therefore, producing alternative liquid fuels from coal has become a fundamental direction for coal processing and utilization, and it has significant strategic importance for energy security.

[0003] With the rapid development of China's coal chemical industry, coal tar production has increased year by year, and the clean and efficient utilization of coal tar has received increasing attention. Currently, the main utilization pathways of coal tar are deep processing to extract chemical products or hydrogenation to produce clean fuels. In recent years, the number of fixed-bed coal tar hydrogenation units in China has been increasing. Among them, fixed-bed hydrogenation units have the advantages of simple process, low investment, simple operation, and high technological maturity. However, when processing low-quality coal tar feedstock, they are prone to bed blockage, rapid pressure drop, heat exchanger coking and blockage, and asphalt deposits on the catalyst causing rapid catalyst deactivation. These problems force the unit to shut down, shorten the operating time, and seriously affect the economic benefits of enterprises.

[0004] Therefore, in order to extend the operating cycle of coal tar hydrogenation units, it is necessary to purify the coal tar feedstock to remove metals, ash, and convert asphaltene, and then hydrogenate it in a fixed bed to produce clean fuels, which can greatly extend the operating cycle of the unit.

[0005] Currently, the pretreatment of coal tar in China mainly adopts methods such as centrifugal separation, sedimentation separation, solvent extraction, electric field purification and filtration separation. These methods have disadvantages such as poor pretreatment effect, low efficiency and low utilization rate of coal tar resources.

[0006] CN106701157A discloses a method for demetallizing high-temperature coal tar. Although the method uses dilution oil, adds alcohols, and uses a demetallization reactor to pretreat the high-temperature coal tar to remove metals, water is introduced during the process. The treated water is phenolic water, which contains high levels of phenols, ammonia nitrogen, etc., making it difficult to treat and not meeting environmental protection requirements.

[0007] CN105713658B discloses a pretreatment process for low-temperature coal tar, in which the coal tar raw material is pretreated through steps such as sedimentation separation, primary electrostatic desalination, and secondary electrostatic desalination. However, the process is complex, the operating cost is high, and water is introduced during the implementation process, which also presents the problem of difficult treatment of phenolic water.

[0008] CN101012385A discloses a pretreatment method for coal tar, which uses distillate oil and aromatics to perform two-stage extraction on coal tar to remove ash and asphaltenes. Although solvent extraction separation method has a good purification effect, it requires a large amount of solvent, has a complex process, and has high operating costs. Summary of the Invention

[0009] The purpose of this disclosure is to provide a method for pre-hydrogenation of coal tar feedstock, which can effectively remove metals, ash and asphaltenes from the coal tar feedstock.

[0010] To achieve the above objectives, this disclosure provides a method for pre-hydrogenation of coal tar feedstock, the method comprising: S1, mixing coal tar feedstock with a diluent and then performing solid-liquid separation to obtain solid phase material and liquid phase material; S2, under hydrogen-containing conditions, contacting the liquid phase material with a protective catalyst and an asphaltene hydroconversion catalyst to perform a hydrogenation reaction, and performing gas-liquid separation on the obtained hydrogenation reaction product.

[0011] Optionally, in step S1, the volume ratio of the diluent to the coal tar raw material is (0.005-0.5):1, preferably (0.01-0.3):1.

[0012] Optionally, in step S1, the mixing conditions include: mixing temperature 50-200℃, mixing time 10-90min;

[0013] Preferably, the mixing temperature is 60-160℃ and the mixing time is 30-60min.

[0014] Optionally, in step S2, the conditions for the hydrogenation reaction include: a hydrogen partial pressure of 4-20 MPa, a reaction temperature of 300-390 °C, and a hydrogen-to-oil volume ratio of 400-1300 Nm. 3 / m 3 The volumetric hourly space velocity (HSV) of the feed liquid is 0.3-2.5 h⁻¹. -1 ;

[0015] Preferably, the hydrogen partial pressure is 6-10 MPa, the reaction temperature is 310-370°C, and the hydrogen-to-oil volume ratio is 500-1000 Nm. 3 / m 3 The volume hourly space velocity (HSV) of the feed liquid is 0.5-1.2 h⁻¹. -1 .

[0016] Optionally, in step S2, after the liquid phase material is contacted with three or four kinds of protective catalysts to carry out a first reaction, the first reaction product is contacted with three or four kinds of asphaltene hydroconversion catalysts to carry out a second reaction, thereby obtaining the hydrogenation reaction product.

[0017] Preferably, the protective catalyst comprises a first protective catalyst, a second protective catalyst, and a third protective catalyst arranged sequentially from upstream to downstream; the active components in the first protective catalyst, the second protective catalyst, and the third protective catalyst are each independently selected from one or more of Ni, Mo, Ti, and Co;

[0018] Preferably, the asphaltene hydroconversion catalyst comprises a first asphaltene hydroconversion catalyst, a second asphaltene hydroconversion catalyst, and a third asphaltene hydroconversion catalyst arranged sequentially from upstream to downstream; the active components in the first asphaltene hydroconversion catalyst, the second asphaltene hydroconversion catalyst, and the third asphaltene hydroconversion catalyst are each independently selected from one or more of Ni, Mo, W, Ti, and Co;

[0019] Preferably, the most probable pore sizes of the first asphaltene hydroconversion catalyst, the second asphaltene hydroconversion catalyst, and the third asphaltene hydroconversion catalyst decrease sequentially.

[0020] More preferably, the most probable pore size of the first asphaltene hydroconversion catalyst is 13-15 nm, the most probable pore size of the second asphaltene hydroconversion catalyst is 10-12 nm, and the most probable pore size of the third asphaltene hydroconversion catalyst is 7-9 nm.

[0021] Optionally, the first protective catalyst has an average diameter of 15-17 mm, a most probable pore size of 20-22 nm, and is supported on silica or alumina.

[0022] The second protective catalyst has an average diameter of 9-11 mm and a most probable pore size of 18-20 nm. Based on the total weight of the second protective catalyst, it contains 0.05-0.2% by weight of nickel oxide, 0.5-1.0% by weight of molybdenum oxide, and the balance of silicon oxide or aluminum oxide.

[0023] The third protective catalyst has an average diameter of 5.6-6.5 mm and a most probable pore size of 16-18 nm. Based on the total weight of the third protective catalyst, it contains 0.1-0.5% by weight of nickel oxide, 0.5-2.5% by weight of molybdenum oxide, and the balance of silicon oxide or aluminum oxide.

[0024] The first asphaltene hydroconversion catalyst has an average diameter of 2.5-3.5 mm and a most probable pore size of 13-15 nm. Based on the total weight of the first asphaltene hydroconversion catalyst, it contains 0.1-1% by weight of nickel oxide, 1-5.5% by weight of molybdenum oxide, and the balance of silicon oxide or aluminum oxide.

[0025] The second asphaltene hydroconversion catalyst has an average diameter of 1-1.2 mm and a most probable pore size of 10-12 nm. Based on the total weight of the second asphaltene hydroconversion catalyst, it contains 1-3% by weight of nickel oxide, 5-8% by weight of molybdenum oxide, and the balance of silicon oxide or aluminum oxide.

[0026] The third asphaltene hydroconversion catalyst has an average diameter of 1-1.2 mm and a most probable pore size of 7-9 nm. Based on the total weight of the third asphaltene hydroconversion catalyst, it contains 2-8% by weight of nickel oxide, 8-20% by weight of molybdenum oxide, and the balance of silicon oxide or aluminum oxide.

[0027] Optionally, relative to the total volume of 100 volumes of the third asphaltene hydroconversion catalyst, the amount of the first protective catalyst is 20-40 volumes, the amount of the second protective catalyst is 20-50 volumes, the amount of the third protective catalyst is 20-50 volumes, the amount of the first asphaltene hydroconversion catalyst is 30-60 volumes, and the amount of the second asphaltene hydroconversion catalyst is 40-80 volumes.

[0028] Optionally, in step S1, a centrifugal separation device is used to perform the solid-liquid separation, and the centrifugal separation device is selected from a horizontal screw centrifuge and / or a disc centrifuge.

[0029] The conditions for solid-liquid separation include: an operating temperature of 60-100℃ and a rotation speed of 3000-8000 rpm.

[0030] Optionally, the diluent is one or more of the following: hydrogenated product oil, cut distillate oil from coal tar feedstock, inorganic acid, C5-C9 hydrocarbons, C1-C4 alcohols, C1-C4 carboxylic acids, and pyruvic acid.

[0031] The hydrogenated product oil includes one or more of naphtha, kerosene, diesel oil, and tail oil;

[0032] The cut distillate oils of the coal tar feedstock include one or more of light oil, phenolic oil, wash oil, naphthalene oil, and anthracene oil.

[0033] The inorganic acid is selected from one or more of phosphoric acid, hydrochloric acid, nitric acid, and sulfuric acid;

[0034] The C5-C9 hydrocarbons include one or more of n-pentane, n-hexane, n-heptane, benzene, toluene, and xylene;

[0035] The C1-C4 alcohols include one or more of methanol, ethanol, propanol, butanol, and isobutanol;

[0036] The C1-C4 carboxylic acids include one or more of formic acid, acetic acid, oxalic acid, and pyruvic acid.

[0037] Optionally, the coal tar raw material includes one or more of low-temperature coal tar, medium-low-temperature coal tar, medium-temperature coal tar, and high-temperature coal tar, or is a mixture of one or more of low-temperature coal tar, medium-low-temperature coal tar, medium-temperature coal tar, and high-temperature coal tar with anthracene oil and / or wash oil.

[0038] The method disclosed herein has the following advantages:

[0039] (1) It can effectively remove metals from coal tar raw materials and realize the conversion of asphaltene, while reducing the ash content. The pretreatment effect is good and can meet the feeding requirements of the subsequent hydrogenation reaction unit.

[0040] (2) It has the advantages of low energy consumption, low investment, simple process, simple operation and low operating cost;

[0041] (3) No water is introduced, thus avoiding environmental pollution problems caused by the difficulty in treating phenolic water and meeting environmental protection requirements.

[0042] Other features and advantages of this disclosure will be described in detail in the following detailed description section. Attached Figure Description

[0043] The accompanying drawings are provided to further illustrate the present disclosure and form part of the specification. They are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation thereof. In the drawings:

[0044] Figure 1 This is a schematic flowchart of the method for pre-hydrogenation treatment of coal tar feedstock provided in this disclosure.

[0045] Explanation of reference numerals in the attached figures

[0046] 1. Coal tar raw material; 2. Mixing tank; 3. Diluent

[0047] 4. Solid-liquid separator; 5. Solid material; 6. Pre-hydrogenation reactor

[0048] 7. Gas-liquid separator 8. Circulating hydrogen compressor 9. Hydrogen

[0049] 10. Pre-treatment product tank Detailed Implementation

[0050] The specific embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit this disclosure.

[0051] This disclosure provides a method for pre-hydrogenation of coal tar feedstock, the method comprising: S1, mixing the coal tar feedstock with a diluent and then performing solid-liquid separation to obtain a solid phase material and a liquid phase material; S2, under hydrogen-containing conditions, contacting the liquid phase material with a protective catalyst and an asphaltene hydroconversion catalyst to perform a hydrogenation reaction, and performing gas-liquid separation on the obtained hydrogenation reaction product.

[0052] The method disclosed herein can effectively remove impurities such as metals, ash, and bituminous substances from coal tar feedstock, thereby extending the stable operation cycle of the equipment.

[0053] In one specific embodiment of this disclosure, in step S1, the volume ratio of the diluent to the coal tar raw material can vary within a wide range, for example, it can be (0.005-0.5):1, preferably (0.01-0.3):1.

[0054] In one specific embodiment of this disclosure, in step S1, the coal tar raw material and the diluent can be mixed in any device, such as a mixing tank. The mixing conditions may include: mixing temperature of 50-200°C and mixing time of 10-90 min; preferably, the mixing temperature is 60-160°C and the mixing time is 30-60 min.

[0055] In one specific embodiment of this disclosure, the conditions for the hydrogenation reaction in step S2 may include: a hydrogen partial pressure of 4-20 MPa, a reaction temperature of 300-390°C, and a hydrogen-to-oil volume ratio of 400-1300 Nm. 3 / m 3 The volumetric hourly space velocity (HSV) of the feed liquid is 0.3-2.5 h⁻¹. -1 Preferably, the hydrogen partial pressure is 6-10 MPa, the reaction temperature is 310-370℃, and the hydrogen-to-oil volume ratio is 500-1000 Nm. 3 / m 3 The volume hourly space velocity (HSV) of the feed liquid is 0.5-1.2 h⁻¹. -1 .

[0056] In one specific embodiment of this disclosure, the gaseous material obtained by gas-liquid separation is returned to step S2 to participate in the hydrogenation reaction.

[0057] According to this disclosure, in step S2, the liquid phase material is contacted with at least two protective catalysts and at least two asphaltene hydroconversion catalysts to carry out a hydrogenation reaction. In one embodiment, after the liquid phase material is contacted with three or four of the protective catalysts to carry out a first reaction, the resulting first reaction product is contacted with three or four asphaltene hydroconversion catalysts to carry out a second reaction, thereby obtaining the hydrogenation reaction product. In a preferred embodiment, the protective catalyst includes a first protective catalyst, a second protective catalyst, and a third protective catalyst arranged sequentially from upstream to downstream; the active components in the first, second, and third protective catalysts are each independently selected from one or more of Ni, Mo, Ti, and Co; more preferably, the asphaltene hydroconversion catalyst includes a first asphaltene hydroconversion catalyst, a second asphaltene hydroconversion catalyst, and a third asphaltene hydroconversion catalyst arranged sequentially from upstream to downstream; the active components in the first, second, and third asphaltene hydroconversion catalysts are each independently selected from one or more of Ni, Mo, W, Ti, and Co. More preferably, the most probable pore sizes of the first asphaltene hydroconversion catalyst, the second asphaltene hydroconversion catalyst, and the third asphaltene hydroconversion catalyst decrease sequentially. For example, the most probable pore size of the first asphaltene hydroconversion catalyst is 13-15 nm, the most probable pore size of the second asphaltene hydroconversion catalyst is 10-12 nm, and the most probable pore size of the third asphaltene hydroconversion catalyst is 7-9 nm.

[0058] In a preferred embodiment of this disclosure, the first protective catalyst has an average diameter of 15-17 mm and a most probable pore size of 20-22 nm, and the support is silicon oxide or alumina; the second protective catalyst has an average diameter of 9-11 mm and a most probable pore size of 18-20 nm, and based on the total weight of the second protective catalyst, it contains 0.05-0.2 wt% nickel oxide, 0.5-1.0 wt% molybdenum oxide, and the balance being silicon oxide or alumina; the third protective catalyst has an average diameter of 5.6-6.5 mm and a most probable pore size of 16-18 nm, and based on the total weight of the third protective catalyst, it contains 0.1-0.5 wt% nickel oxide, 0.5-2.5 wt% molybdenum oxide, and the balance being silicon oxide or alumina. This disclosure does not specifically limit the shape of the protective catalyst; it can be any catalyst shape known to those skilled in the art, such as a porous cylindrical shape, a honeycomb cylindrical shape, or a Raschig ring shape. In one embodiment, the present disclosure specifies that the first protective catalyst is a porous cylindrical shape, the second protective catalyst is a honeycomb cylindrical shape, and the third protective catalyst is a Raschig ring shape.

[0059] In a preferred embodiment of this disclosure, the first asphaltene hydroconversion catalyst has an average diameter of 2.5-3.5 mm and a most probable pore size of 13-15 nm. Based on the total weight of the first asphaltene hydroconversion catalyst, it contains 0.1-1 wt% nickel oxide, 1-5.5 wt% molybdenum oxide, and the balance being silicon oxide or aluminum oxide. The second asphaltene hydroconversion catalyst has an average diameter of 1-1.2 mm and a most probable pore size of 10-12 nm. Based on the total weight of the second asphaltene hydroconversion catalyst, it contains 1-3 wt% nickel oxide, 5-8 wt% molybdenum oxide, and the balance being silicon oxide or aluminum oxide. The third asphaltene hydroconversion catalyst has an average diameter of 1-1.2 mm and a most probable pore size of 7-9 nm. Based on the total weight of the third asphaltene hydroconversion catalyst, it contains 2-8 wt% nickel oxide, 8-20 wt% molybdenum oxide, and the balance being silicon oxide or aluminum oxide. This disclosure does not impose specific limitations on the shape of the asphaltene hydroconversion catalyst, and it can be any catalyst shape known to those skilled in the art, such as honeycomb, Raschig ring, and butterfly shapes. In one embodiment, the first asphaltene hydroconversion catalyst is Raschig ring shaped, the second asphaltene hydroconversion catalyst is butterfly shaped, and the third asphaltene hydroconversion catalyst is butterfly shaped.

[0060] In one specific embodiment of this disclosure, relative to the total volume of 100 volumes of the third asphaltene hydroconversion catalyst, the amount of the first protective catalyst is 20-40 volumes, the amount of the second protective catalyst is 20-50 volumes, the amount of the third protective catalyst is 20-50 volumes, the amount of the first asphaltene hydroconversion catalyst is 30-60 volumes, and the amount of the second asphaltene hydroconversion catalyst is 40-80 volumes.

[0061] According to this disclosure, any device capable of solid-liquid separation can be used for solid-liquid separation. In a preferred embodiment of this disclosure, in step S1, a centrifugal separation device is used for the solid-liquid separation. The centrifugal separation device can be selected from a horizontal screw centrifuge and / or a disc centrifuge. The conditions for solid-liquid separation may include: an operating temperature of 60-100℃ and a rotation speed of 3000-8000 rpm.

[0062] According to this disclosure, the diluent can be a diluent oil and / or an organic solvent. In one specific embodiment of this disclosure, the diluent is one or more of the following: hydrogenated product oil, cut distillate oil from coal tar feedstock, inorganic acid, C5-C9 hydrocarbons, C1-C4 alcohols, C1-C4 carboxylic acids, and pyruvic acid. The hydrogenated product oil can be obtained by hydrogenation of one or more of petroleum-based feedstocks, coal tar feedstocks, and Fischer-Tropsch synthetic oils, for example, it can include one or more of naphtha, kerosene, diesel, and tail oil; the cut fraction oil of the coal tar feedstock can include one or more of light oil, phenolic oil, wash oil, naphthalene oil, and anthracene oil; the inorganic acid can be selected from one or more of phosphoric acid, hydrochloric acid, nitric acid, and sulfuric acid; the C5-C9 hydrocarbons can include one or more of n-pentane, n-hexane, n-heptane, benzene, toluene, and xylene; the C1-C4 alcohols can include one or more of methanol, ethanol, propanol, butanol, and isobutanol; the C1-C4 carboxylic acids can include one or more of formic acid, acetic acid, oxalic acid, and pyruvic acid; preferably, the diluent is selected from one or more of tail oil, light oil, wash oil, n-heptane, xylene, methanol, and acetic acid.

[0063] According to this disclosure, coal tar, as is well known to those skilled in the art, refers to coal tar produced by coal pyrolysis, coal gasification, or other processes. The coal tar raw materials may include low-temperature coal tar produced during coal gasification, or one or more of the following: low-temperature coal tar, medium-temperature coal tar, medium-temperature coal tar, and high-temperature coal tar produced during coal pyrolysis or coking processes (including low-temperature pyrolysis, medium-temperature pyrolysis, and high-temperature coking processes); or a mixture of one or more of the following: low-temperature coal tar, medium-temperature coal tar, medium-temperature coal tar, and high-temperature coal tar with anthracene oil and / or wash oil.

[0064] According to this disclosure, the distillation range of the low-temperature coal tar can be 50-450℃; the distillation range of the medium-low temperature coal tar can be 50-550℃; the distillation range of the medium-temperature coal tar can be 50-600℃; and the distillation range of the high-temperature coal tar can be 50-650℃.

[0065] like Figure 1 As shown, in one specific embodiment, a method for pre-hydrogenating coal tar feedstock is employed, including the following steps:

[0066] S1. The coal tar raw material 1 to be pretreated is mixed with diluent 3 in mixing tank 2. The mixed material is introduced into solid-liquid separator 4 for solid-liquid separation to obtain solid material 5 and liquid material.

[0067] S2. The liquid material is mixed with hydrogen and then introduced into the pre-hydrogenation reactor 6. It contacts the protective catalyst and the asphaltene hydroconversion catalyst to carry out a hydrogenation reaction. The hydrogenation reaction product flowing out of the pre-hydrogenation reactor is introduced into the gas-liquid separator 7 for gas-liquid separation. The separated hydrogen-containing gas is pressurized by the circulating hydrogen compressor 8 and mixed with hydrogen 9 before returning to the pre-hydrogenation reactor 6 to participate in the reaction further. The separated liquid stream enters the pretreatment product tank 10. The pretreatment product can be used as feedstock for further deep hydrogenation in the subsequent main hydrogenation unit.

[0068] The present disclosure will be further illustrated by the following examples, but the present disclosure is not limited thereto.

[0069] In the following examples, all raw materials used were commercially available unless otherwise specified. The properties of the coal tar raw materials to be pretreated are shown in Table 1.

[0070] In Examples 1-9, the catalysts in the pre-hydrogenation reactor along the direction of the reaction stream are respectively a first protective catalyst, a second protective catalyst, a third protective catalyst, a first asphaltene hydroconversion catalyst, a second asphaltene hydroconversion catalyst, and a third asphaltene hydroconversion catalyst.

[0071] The first protective catalyst is a porous cylindrical structure with silica as the support, a diameter of 15-17 mm, and a most probable pore size of 20-22 nm. The second protective catalyst is a honeycomb cylindrical structure with a diameter of 9-11 mm and a most probable pore size of 18-20 nm, composed of 0.17 wt% nickel oxide, 0.9 wt% molybdenum oxide, and the balance being silica or alumina. The third protective catalyst is a Raschig ring structure with a diameter of 5.6-6.5 mm and a most probable pore size of 16-18 nm, composed of 0.35 wt% nickel oxide, 2.0 wt% molybdenum oxide, and the balance being silica. The first asphaltene hydroconversion catalyst is a Raschig ring. The first catalyst is cyclic, with a diameter of 2.5-3.5 mm and a most probable pore size of 13-15 nm, and its composition is 0.8 wt% nickel oxide, 3.0 wt% molybdenum oxide, and the balance being aluminum oxide; the second asphaltene hydroconversion catalyst is butterfly-shaped, with a diameter of 1.0-1.2 mm and a most probable pore size of 10-12 nm, and its composition is 2.2 wt% nickel oxide, 6.5 wt% molybdenum oxide, and the balance being silicon oxide; the third asphaltene hydroconversion catalyst is butterfly-shaped, with a diameter of 1.0-1.2 mm and a most probable pore size of 7-9 nm, and its composition is 5.0 wt% nickel oxide, 17.0 wt% molybdenum oxide, and the balance being silicon oxide.

[0072] Based on the total volume of the third asphaltene hydroconversion catalyst in the pre-hydrogenation reactor, the loading amount of the first protective catalyst is 30% by volume, the loading amount of the second protective catalyst is 35% by volume, the loading amount of the third protective catalyst is 35% by volume, the loading amount of the first asphaltene hydroconversion catalyst is 45% by volume, and the loading amount of the second asphaltene hydroconversion catalyst is 65% by volume.

[0073] Example 1

[0074] S1. The coal tar to be pretreated is used as raw material, and hydrogenated tail oil is mixed with it in a mixing tank at a volume ratio of 0.1:1. The mixing temperature is 160℃ and the mixing time is 50 min. The mixed stream enters a solid-liquid separator to separate the solid residue and liquid, obtaining solid and liquid phase materials.

[0075] S2. The separated liquid material is mixed with hydrogen and then fed into the pre-hydrogenation reactor, where it comes into contact with the protective catalyst and the asphaltene hydroconversion catalyst to carry out the hydrogenation reaction. The effluent from the pre-hydrogenation reactor enters the gas-liquid separator for gas-liquid separation. The separated liquid stream enters the pre-treatment product tank. The pre-treatment product is suitable as a feedstock for the subsequent coal tar hydrogenation unit.

[0076] The specific conditions for the hydrogenation reaction are shown in Table 2, and the properties of the coal tar after hydrogenation pretreatment are shown in Table 3.

[0077] Example 2

[0078] S1. The coal tar to be pretreated is used as raw material 1. Xylene is mixed with it in a mixing tank at a volume ratio of 0.3:1. The mixing temperature is 120℃ and the mixing time is 60 min. The mixed stream enters a solid-liquid separator to separate the solid residue and liquid, obtaining solid and liquid phase materials.

[0079] S2. The separated liquid material is mixed with hydrogen and then fed into the pre-hydrogenation reactor, where it comes into contact with the protective catalyst and the asphaltene hydroconversion catalyst to carry out the hydrogenation reaction. The effluent from the pre-hydrogenation reactor enters the gas-liquid separator for gas-liquid separation. The separated liquid stream enters the pre-treatment product tank. The pre-treatment product is suitable as a feedstock for the subsequent coal tar hydrogenation unit.

[0080] The specific conditions for the hydrogenation reaction are shown in Table 2, and the properties of the coal tar after hydrogenation pretreatment are shown in Table 3.

[0081] Example 3

[0082] S1. The coal tar to be pretreated is used as raw material 1. Acetic acid is mixed with it in a mixing tank at a volume ratio of 0.015:1. The mixing temperature is 80℃ and the mixing time is 30min. The mixed material enters the solid-liquid separator to separate the solid residue and liquid to obtain solid material and liquid material.

[0083] S2. The separated liquid material is mixed with hydrogen and then fed into the pre-hydrogenation reactor, where it comes into contact with the protective catalyst and the asphaltene hydroconversion catalyst to carry out the hydrogenation reaction. The effluent from the pre-hydrogenation reactor enters the gas-liquid separator for gas-liquid separation. The separated liquid stream enters the pre-treatment product tank. The pre-treatment product is suitable as a feedstock for the subsequent coal tar hydrogenation unit.

[0084] The specific conditions for the hydrogenation reaction are shown in Table 2, and the properties of the coal tar after hydrogenation pretreatment are shown in Table 3.

[0085] Example 4

[0086] S1. The coal tar to be pretreated is used as raw material 1. It is thoroughly mixed with n-heptane in a mixing tank at a volume ratio of 0.08:1. The mixing temperature is 80℃, and the mixing time is 40 minutes. The mixed stream then enters a solid-liquid separator to separate the solid residue and liquid, obtaining solid and liquid phase materials.

[0087] S1. The separated liquid material is mixed with hydrogen and then enters the pre-hydrogenation reactor, where it comes into contact with the protective catalyst and the asphaltene hydroconversion catalyst to carry out the hydrogenation reaction. The effluent from the pre-hydrogenation reactor enters the gas-liquid separator for gas-liquid separation. The separated liquid stream enters the pre-treatment product tank. The pre-treatment product is suitable as a feedstock for the subsequent coal tar hydrogenation unit.

[0088] The specific operating conditions of the pre-hydrogenation reactor are shown in Table 2, and the properties of the pretreated coal tar are shown in Table 3.

[0089] Example 5

[0090] S1. The coal tar to be pretreated is used as raw material 1. Methanol is mixed with it in a mixing tank at a volume ratio of 0.25:1. The mixing temperature is 60℃ and the mixing time is 30 min. The mixed stream enters a solid-liquid separator to separate the solid residue and liquid, obtaining solid and liquid phase materials.

[0091] S2. The separated liquid material is mixed with hydrogen and then fed into the pre-hydrogenation reactor, where it reacts with the protective catalyst and the asphaltene hydroconversion catalyst. The effluent from the pre-hydrogenation reactor enters the gas-liquid separator for gas-liquid separation. The separated liquid stream enters the pre-treatment product tank, and the pre-treatment product is suitable as a feedstock for subsequent coal tar hydrogenation units.

[0092] The specific operating conditions of the pre-hydrogenation reactor are shown in Table 2, and the properties of the pretreated coal tar are shown in Table 3.

[0093] Example 6

[0094] S1. The coal tar to be pretreated is used as raw material 1. Wash oil is mixed with it in a mixing tank at a volume ratio of 0.2:1. The mixing temperature is 90℃ and the mixing time is 50min. The mixed material enters the solid-liquid separator to separate the solid residue and liquid to obtain solid material and liquid material.

[0095] S2. The separated liquid material is mixed with hydrogen and then fed into the pre-hydrogenation reactor, where it reacts with the protective catalyst and the asphaltene hydroconversion catalyst. The effluent from the pre-hydrogenation reactor enters the gas-liquid separator for gas-liquid separation. The separated liquid stream enters the pre-treatment product tank, and the pre-treatment product is suitable as a feedstock for subsequent coal tar hydrogenation units.

[0096] The specific operating conditions of the pre-hydrogenation reactor are shown in Table 2, and the properties of the pretreated coal tar are shown in Table 3.

[0097] Example 7

[0098] The coal tar feedstock was pre-hydrogenated using the same method as in Example 1, except that in step S1, the volume ratio of the hydrogenated tail oil to the coal tar feedstock was 0.007:1.

[0099] Example 8

[0100] The coal tar feedstock was pre-hydrogenated using the same method as in Example 1, except that the mixing conditions were different in step S1: the mixing temperature was 50°C and the mixing time was 60 min.

[0101] Example 9

[0102] The coal tar feedstock was pre-hydrogenated using the same method as in Example 1, except that the hydrogenation reaction conditions in step S2 were different: the hydrogen partial pressure was 11 MPa, the reaction temperature was 300 °C, and the hydrogen-to-oil volume ratio was 400 Nm³. 3 / m 3 The volume hourly space velocity (VHSV) of the feed liquid is 0.8 h⁻¹. -1 .

[0103] Example 10

[0104] The coal tar feedstock was pre-hydrogenated using the same method as in Example 1, except that the catalysts used in step S2 were only the first protective catalyst and the first asphaltene hydroconversion catalyst.

[0105] Comparative Example 1

[0106] Coal tar feedstock and hydrotreated tail oil were mixed at a volume ratio of 10:1 at 160°C for 50 min. The resulting mixture was then fed into a demetallization reactor, where it was brought into full contact with the catalyst packed inside the reactor. The reaction was carried out at a hydrogen partial pressure of 8 MPa, a temperature of 320°C, and a liquid hourly space velocity of 0.8 h⁻¹.-1 The reaction was carried out under conditions where the hydrogen-to-oil volume ratio was 800. The catalyst packed in the demetallizer along the direction of the reaction stream was the same as the catalyst in the pre-hydrogenation reactor in Example 1.

[0107] Table 1

[0108]

[0109]

[0110] Table 2 Operating Conditions

[0111]

[0112] Pre-hydrogenation reactor operating conditions Example 7 Example 8 Example 9 Example 10 Hydrogen partial pressure / MPa 8.0 8.0 11.0 8.0 Reaction temperature / °C 320 320 300 320 <![CDATA[Volumetric space velocity of the feedstock solution / h -1 > 0.8 0.8 0.8 0.8 Hydrogen-to-oil volume ratio 800 800 400 800

[0113] Table 3

[0114] project Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 <![CDATA[Density (20 °C) / (g / cm 3 )]]> 1.0003 1.0054 1.0100 1.0004 1.0046 1.0046 Total metal content (μg / g) 2.1 8.4 14.7 4.0 7.9 5.7 Ash content / weight % 0.001 0.0015 0.002 0.0013 0.0015 0.0017 Asphalt content / % 0.18 0.70 0.94 0.27 0.68 1.02

[0115]

[0116]

[0117] As can be seen from the above, the method disclosed herein has good pretreatment effect, significantly reducing the content of metals, ash and asphaltene in coal tar raw materials. Moreover, this method has the advantages of low energy consumption, low investment, simple process, simple operation and low operating cost.

[0118] The preferred embodiments of this disclosure have been described in detail above with reference to the accompanying drawings. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.

[0119] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0120] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.

Claims

1. A method for pre-hydrogenating coal tar feedstock, wherein, The method includes: S1. After mixing the coal tar raw material with the diluent, solid-liquid separation is performed to obtain solid and liquid phase materials; wherein, the volume ratio of the diluent to the coal tar raw material is (0.01-0.3):1; the mixing conditions include: mixing temperature of 60-160℃ and mixing time of 30-60min; S2. Under hydrogen-containing conditions, the liquid material is brought into contact with the protective catalyst and the asphaltene hydroconversion catalyst to carry out a hydrogenation reaction, and the hydrogenation reaction product is subjected to gas-liquid separation. The protective catalyst includes a first protective catalyst, a second protective catalyst, and a third protective catalyst arranged sequentially from upstream to downstream; the active components in the first protective catalyst, the second protective catalyst, and the third protective catalyst are each independently selected from one or more of Ni, Mo, Ti, and Co; The asphaltene hydroconversion catalyst comprises a first asphaltene hydroconversion catalyst, a second asphaltene hydroconversion catalyst, and a third asphaltene hydroconversion catalyst arranged sequentially from upstream to downstream; the active components in the first, second, and third asphaltene hydroconversion catalysts are each independently selected from one or more of Ni, Mo, W, Ti, and Co; the most probable pore sizes of the first, second, and third asphaltene hydroconversion catalysts decrease sequentially. Relative to the total volume of 100 volumes of the third asphaltene hydroconversion catalyst, the amount of the first protective catalyst is 20-40 volumes, the amount of the second protective catalyst is 20-50 volumes, the amount of the third protective catalyst is 20-50 volumes, the amount of the first asphaltene hydroconversion catalyst is 30-60 volumes, and the amount of the second asphaltene hydroconversion catalyst is 40-80 volumes. The conditions for the hydrogenation reaction include: a hydrogen partial pressure of 6-10 MPa, a reaction temperature of 310-370℃, and a hydrogen-to-oil volume ratio of 500-1000 Nm. 3 / m 3 The volumetric hourly space velocity (HSV) of the feed liquid is 0.5-1.2 h⁻¹. -1 .

2. The method according to claim 1, wherein, In step S2, the most probable pore size of the first asphaltene hydroconversion catalyst is 13-15 nm, the most probable pore size of the second asphaltene hydroconversion catalyst is 10-12 nm, and the most probable pore size of the third asphaltene hydroconversion catalyst is 7-9 nm.

3. The method according to claim 2, wherein, The first protective catalyst has an average diameter of 15-17 mm, a most probable pore size of 20-22 nm, and is supported on silica or alumina. The second protective catalyst has an average diameter of 9-11 mm and a most probable pore size of 18-20 nm. Based on the total weight of the second protective catalyst, it contains 0.05-0.2% by weight of nickel oxide, 0.5-1.0% by weight of molybdenum oxide, and the balance of silicon oxide or aluminum oxide. The third protective catalyst has an average diameter of 5.6-6.5 mm and a most probable pore size of 16-18 nm. Based on the total weight of the third protective catalyst, it contains 0.1-0.5% by weight of nickel oxide, 0.5-2.5% by weight of molybdenum oxide, and the balance of silicon oxide or aluminum oxide. The first asphaltene hydroconversion catalyst has an average diameter of 2.5-3.5 mm and a most probable pore size of 13-15 nm. Based on the total weight of the first asphaltene hydroconversion catalyst, it contains 0.1-1% by weight of nickel oxide, 1-5.5% by weight of molybdenum oxide, and the balance of silicon oxide or aluminum oxide. The average diameter of the second asphaltene hydroconversion catalyst is 1-1.2 mm, the most probable pore size is 10-12 nm, and based on the total weight of the second asphaltene hydroconversion catalyst, it contains 1-3% by weight of nickel oxide, 5-8% by weight of molybdenum oxide, and the balance of silicon oxide or aluminum oxide. The third asphaltene hydroconversion catalyst has an average diameter of 1-1.2 mm and a most probable pore size of 7-9 nm. Based on the total weight of the third asphaltene hydroconversion catalyst, it contains 2-8% by weight of nickel oxide, 8-20% by weight of molybdenum oxide, and the balance of silicon oxide or aluminum oxide.

4. The method according to claim 1, wherein, In step S1, a centrifugal separation device is used to perform the solid-liquid separation. The centrifugal separation device is selected from a horizontal screw centrifuge and / or a disc centrifuge. The conditions for solid-liquid separation include: an operating temperature of 60-100℃ and a rotation speed of 3000-8000 rpm.

5. The method according to claim 1, wherein, The diluent is one or more of the following: hydrogenated product oil, cut distillate oil from coal tar feedstock, inorganic acid, C5-C9 hydrocarbons, C1-C4 alcohols, C1-C4 carboxylic acids, and pyruvic acid. The hydrogenated product oil includes one or more of naphtha, kerosene, diesel oil, and tail oil; The cut distillate oils of the coal tar feedstock include one or more of light oil, phenolic oil, wash oil, naphthalene oil, and anthracene oil. The inorganic acid is selected from one or more of phosphoric acid, hydrochloric acid, nitric acid, and sulfuric acid; The C5-C9 hydrocarbons include one or more of n-pentane, n-hexane, n-heptane, benzene, toluene, and xylene; The C1-C4 alcohols include one or more of methanol, ethanol, propanol, butanol, and isobutanol; The C1-C4 carboxylic acids include one or more of formic acid, acetic acid, and oxalic acid.

6. The method according to claim 1, wherein, The coal tar raw material includes one or more of low-temperature coal tar, medium-low-temperature coal tar, medium-temperature coal tar, and high-temperature coal tar, or a mixture of one or more of low-temperature coal tar, medium-low-temperature coal tar, medium-temperature coal tar, and high-temperature coal tar with anthracene oil and / or wash oil.

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