Method for preparing high-grade oil products by hydrogenation of coal tar

Abstract

The present application provides a method for preparing high-grade oil products by hydrogenating coal tar, which relates to the petrochemical field. The method includes: subjecting a mixed material to a hydrofining reaction to obtain a refined product; subjecting the refined product to a hydrodearomatization reaction to obtain a dearomatized product; the naphtha and dry gas obtained by atmospheric fractionation of the dearomatized product are discharged from the top of the tower, and the dry gas is purified and used as fuel for the heating furnace and incorporated into the gas pipeline network; the liquid phase obtained by atmospheric fractionation is used as ethylene cracking stock or naphtha; the bottom material obtained by atmospheric fractionation is used as the feedstock for the second-stage hydrogenation; the feedstock for the second-stage hydrogenation is subjected to a hydroisomerization reaction to obtain an isomerized product; the isomerized product is subjected to a deep dearomatization reaction to obtain a deep dearomatized product; the deep dearomatized product is subjected to gas-liquid separation and pressure reduction and then enters the atmospheric and vacuum fractionation, and aviation kerosene, light white oil and lubricating oil base oil are separated according to the requirements of different products for the distillation range. The method provided by the present application not only solves the problem of difficult removal of sulfur, nitrogen and aromatics in coal tar, but also obtains high-grade oil products.

Description

Technical Field

[0001] The present application relates to the petrochemical field, and particularly to a method for preparing high-grade oil products by hydrogenating coal tar. Background Art

[0002] Coal tar is a black or dark brown viscous liquid product with a pungent odor generated after the dry distillation of coal. Compared with natural petroleum, coal tar has the characteristics of high contents of olefins, sulfur, nitrogen, oxygen, heavy metals, and heterocyclic aromatic hydrocarbons. These undesirable components in coal tar determine that it cannot be directly used as a product. Existing coal tar hydrogenation units can only remove some impurities in coal tar and put it on the market as fuel oil. However, with the promotion of the policy of "reducing oil and increasing chemicals", the market for ordinary fuel oil is gradually shrinking. Therefore, producing higher-end products from coal tar has become an effective way in the coal tar processing industry.

[0003] Hydrotreating is a general term for the catalytic upgrading of oil products under hydrogen pressure. It refers to the hydrocracking reactions in which sulfur, nitrogen, and oxygen in non-hydrocarbon components and organometallic compound molecules in oil product fractions are removed, and olefin and aromatic hydrocarbon molecules undergo hydrogenation reactions to become saturated in the presence of a catalyst and hydrogen. The reaction products are low-sulfur and low-nitrogen oil products and H 2 S, NH 3 3. All of the above reactions have chemical hydrogen consumption and are exothermic reactions. The main reactions in the hydrotreating process of oil product fractions include: hydrocracking reactions of non-hydrocarbons such as sulfur-containing, nitrogen-containing, and oxygen-containing compounds; hydrogenation saturation reactions of olefins and aromatic hydrocarbons (mainly polycyclic aromatic hydrocarbons); in addition, there are also a small number of ring-opening, chain-breaking, condensation, and isomerization reactions. These reactions generally include a series of parallel and sequential reactions, forming a complex reaction network, and the reaction depth and rate often depend on the chemical composition of the feedstock oil, the catalyst, and the process conditions. Generally speaking, the hydrogenation of nitrogen compounds is the most difficult and requires the most stringent conditions. Under the conditions that can meet denitrification, the requirements for desulfurization and deoxidation can also be met.

[0004] The existing hydrogenation process is that the feedstock oil undergoes a series of reactions such as passing through a hydrogenation protection catalyst, a hydrofining catalyst, a hydrocracking catalyst, and a supplementary refining catalyst to remove heavy metals, sulfides, nitrides, and oxides in coal tar under high temperature and high pressure conditions, simply cracking macromolecules into small molecules, and saturating the generated system, etc., and maximally producing low-end fuel oil, which cannot meet the current environmental protection requirements and market demands at all.

[0005] The existing coal tar hydrogenation process is as follows: First, the coal tar is subjected to atmospheric and vacuum distillation to remove the components with a boiling point of ≥520°C or lower that are difficult to hydrogenate. The fraction with a boiling point of ≤520°C is passed through two hydrogenation protection reactors used in parallel (the two protection reactors are in standby for each other). After removing part of the gum, asphaltene, heavy metals, etc. under the action of the protective agent, it enters two hydrofining reactors in sequence. After removing sulfides, nitrides, oxides, etc. in the feedstock under the action of the hydrofining catalyst, it enters a supplementary refining reactor. Under the action of the supplementary refining catalyst, some unsaturated hydrocarbons in the feedstock are saturated. The reaction product is subjected to atmospheric and vacuum distillation to separate the light fuel oil as a product. The heavy oil is lightened irregularly under high temperature and high pressure through a hydrocracking catalyst. The feedstock after hydrocracking is subjected to atmospheric distillation. The light oil is used as a product, and the heavy oil is recycled to the inlet of the hydrocracking reactor for recycling. After recycling to a certain extent, it is taken out of the device as wax oil and treated as a by-product of the device.

[0006] The catalysts used in the existing coal tar hydrogenation unit are all traditional hydrogenation catalysts in the refining industry. During use, it is necessary to ensure a certain amount of H 2 S in the system. Therefore, it is necessary to inject a certain amount of sulfur-containing substances into the feedstock irregularly to maintain the H 2 S concentration in the system.

[0007] Developing a technology that can solve the problems of difficult removal of sulfur, nitrogen, and aromatics in coal tar and can break the situation that traditional coal tar can only be used as low-end fuel oils such as gasoline and diesel has become the focus of research. Summary of the Invention

[0008] The purpose of this application is to provide a method for preparing high-grade oil products by hydrogenating coal tar to solve the above problems.

[0009] To achieve the above purpose, the following technical solutions are adopted in this application:

[0010] A method for preparing high-grade oil products by hydrogenating coal tar includes:

[0011] S1. The coal tar is filtered to remove impurities with a particle size of ≥15μm, pressurized and mixed with hydrogen to obtain a mixed material, and then subjected to the first heat exchange to 200-300°C (preferably 260°C-300°C). Then, the mixed material is heated to 320-380°C (preferably 320°C-340°C) and enters a hydrofining reactor to carry out a hydrofining reaction to obtain a refined product;

[0012] Optionally, the endpoint temperature of the first heat exchange may be 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, 260°C, 270°C, 280°C, 290°C, 300°C or any value between 200-300°C; the endpoint temperature of the mixed material heating may be 320°C, 330°C, 340°C, 350°C, 360°C, 370°C, 380°C or any value between 320-380°C;

[0013] The hydrotreating reactor is filled with a hydrotreating catalyst, wherein the hydrotreating catalyst uses macroporous alumina as a carrier, is calcined at 600-1200° C. (preferably 900-1100° C.), and then loaded with a first active metal at 80-120° C. (preferably 105-115° C.), wherein the first active metal includes one or more of W, Mo, Ni, and Co;

[0014] Optionally, the calcination temperature may be 600°C, 700°C, 800°C, 900°C, 1000°C, 1100°C, 1200°C or any value between 600-1200°C; the load temperature may be 80°C, 90°C, 100°C, 110°C, 120°C or any value between 80-120°C;

[0015] The reaction materials are deeply removed from the impurities such as sulfur, oxygen, nitrogen, and heavy metals in the raw materials under the action of the hydrorefining catalyst. Since the sulfur content in coal tar is 5000μg / g~8000μg / g, and the nitrogen content is 8000μg / g~10000μg / g, the traditional hydrorefining catalyst has a sulfur and nitrogen removal rate of about 98% for the raw materials. However, for coal tar, the sulfur and nitrogen content of the hydrogenated product is about 150μg / g, which does not meet the feed requirements of the second-stage catalyst (S≤10μg / g, N 2 ≤2μg / g), therefore, in the present invention, a super-large-pore alumina carrier is used for the hydrorefining catalyst in the hydrorefining reactor, and the catalyst is calcined at 600-1200°C. After the calcination, the catalyst carrier is loaded with active metals by a vacuum method at 80-120°C. The active metals are conventionally one or more of W, MO, Ni, and Co as active components, and their contents are also different. The contents are calculated in oxidation state and account for 3% to 50% of the catalyst weight. The catalyst produced by this method can make the product S≤2μg / g, N≤2μg / g under process conditions. 2 ≤2μg / g;

[0016] S2. The refined product is subjected to a second heat exchange to 180-260°C, and then enters a hydrodearomatization reactor to undergo a hydrodearomatization reaction to obtain a dearomatization product;

[0017] Optionally, the end temperature of the second heat exchange can be 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, 260°C, or any value between 180 - 260°C;

[0018] The hydrodearomatization reactor is filled with a hydrodearomatization catalyst. The hydrodearomatization catalyst uses macroporous alumina as a carrier, is calcined at 400 - 600°C (preferably 450 - 550°C), impregnated with a second active metal, dried, calcined at 300°C - 350°C, impregnated with Ni, then dried and calcined at 450 - 550°C; The second active metal includes one or more of vanadium, zirconium, and lanthanide metals;

[0019] Optionally, the temperature of the first calcination can be 400°C, 410°C, 420°C, 430°C, 440°C, 450°C, 460°C, 470°C, 480°C, 490°C, 500°C, 510°C, 520°C, 530°C, 540°C, 550°C, 560°C, 570°C, 580°C, 590°C, 600°C, or any value between 400 - 600°C, the temperature of the second calcination can be 300°C, 310°C, 320°C, 330°C, 340°C, 350°C, or any value between 300°C - 350°C, and the temperature of the third calcination can be 450°C, 460°C, 470°C, 480°C, 490°C, 500°C, 510°C, 520°C, 530°C, 540°C, 550°C, or any value between 450 - 550°C;

[0020] Under the action of the de-aromatization catalyst, various aromatics in the coal tar are removed to meet the requirements of the second-stage hydrogenation feed; Since the aromatic content in the coal tar is as high as over 85%, with monocyclic and bicyclic each accounting for about 20%, tricyclic accounting for about 10%, and tricyclic and above accounting for about 35%, the total aromatic content can be reduced to below 30% under the action of the de-aromatization catalyst. The catalyst produced by the above method has good sulfur tolerance activity and stable aromatic saturation activity;

[0021] S3. The de-aromatization product undergoes a third heat exchange, cooling, pressure reduction, gas-liquid separation. The gas phase is recycled, and the liquid phase is fractionated at atmospheric pressure. The naphtha and dry gas obtained from the atmospheric distillation are discharged from the top of the column. The dry gas is purified and used as fuel for the heating furnace and incorporated into the gas pipeline network; The liquid phase obtained from the atmospheric distillation is used as ethylene cracking feedstock or naphtha (light components); The bottom material (heavy components) obtained from the atmospheric distillation is used as the second-stage hydrogenation raw material;

[0022] S4. The second-stage hydrogenation raw material is pressurized (2.0 - 5.0 MPa), mixed with hydrogen, and heated to 290 - 360°C (preferably 300°C - 340°C) after the fourth heat exchange, and then enters the hydroisomerization reactor to carry out hydroisomerization reaction to obtain an isomerization product;

[0023] Optionally, the end pressure of the pressurization can be 2.0 MPa, 2.5 MPa, 3.0 MPa, 3.5 MPa, 4.0 MPa, 4.5 MPa, 5.0 MPa or any value between 2.0 - 5.0 MPa; the end temperature of the fourth heat exchange can be 290 °C, 300 °C, 310 °C, 320 °C, 330 °C, 340 °C, 350 °C, 360 °C or any value between 290 - 360 °C;

[0024] The hydroisomerization reactor is filled with a hydroisomerization catalyst. The hydroisomerization catalyst uses one or more of macroporous silicoaluminophosphates SAPO - 11, SM - 3, SSZ - 32, ZSM - 23, ZSM - 35, ZSM - 48 as the carrier (preferably mainly SAPO - 11, ZSM - 23, ZSM - 48, and the rest of the molecular sieves as the auxiliary). The carrier of the hydroisomerization catalyst is mixed with a binder and formed (kneaded, rolled, extruded), then dried at 60 - 80 °C (strictly controlling the heating rate during the drying process, and the heating rate is controlled at 5 - 10 °C / h), calcined at a temperature not higher than 300 °C, and then impregnated with a first promoter metal. The first promoter metal includes multiple of Mo, Ni, V, Co, Zn; after the impregnation is completed, it is dried and calcined at 290 - 330 °C, and then impregnated with a first active noble metal. The first active noble metal includes one or more of Pt, Re, and Pd;

[0025] Optionally, after the impregnation is completed, it is dried and calcined. The calcination temperature can be 290 °C, 300 °C, 310 °C, 320 °C, 330 °C or any value between 290 - 330 °C;

[0026] Before use, the hydroisomerization catalyst is passivated with tri - n - propylamine to reduce the cracking reaction caused by too high initial activity of the catalyst, and reduce the yield of the target product and the probability of catalyst coking. In traditional industry, sulfur - containing substances are selected to passivate the catalyst, and the passivation effect is significant. The principle of passivating the catalyst with sulfide is to completely kill the initial activity of the catalyst. Once the injection amount of sulfide is not well controlled during the implementation process, it will seriously affect the service life of the catalyst, and in severe cases, the catalyst can be permanently deactivated. Therefore, in the present invention, tri - n - propylamine is used to passivate the catalyst. Tri - n - propylamine plays an inhibitory role on the initial activity of the catalyst. As the catalyst is used, the inhibited activity can be slowly released, ensuring the long - term use of the catalyst.

[0027] Under the action of a heterogeneous catalyst, the structure with a high freezing point in the material is converted into a structure with a low freezing point; the general principle is (1) to break the long-chain molecules, and the broken molecular chains are used as branches and linked into the molecular chain to ensure that the molecular chain becomes shorter but the molecular weight remains unchanged; (2) to open the ring of naphthenes to make them into paraffins without reducing the molecular weight.

[0028] S5. The isomerization product is subjected to a fifth heat exchange to 160 - 280 °C and then enters a deep dearomatization reactor for deep dearomatization reaction to obtain a deep dearomatization product.

[0029] Optionally, the end temperature of the fifth heat exchange can be 160 °C, 170 °C, 180 °C, 190 °C, 200 °C, 210 °C, 220 °C, 230 °C, 240 °C, 250 °C, 260 °C, 270 °C, 280 °C or any value between 160 - 280 °C.

[0030] The deep dearomatization reactor is filled with a deep dearomatization catalyst. The deep dearomatization catalyst uses alumina as a carrier, one or more of Mg, Zn, and As as the second promoter metal, and Pt and / or Pd as the second active noble metal.

[0031] S6. The deep dearomatization product undergoes gas-liquid separation and pressure reduction and then enters atmospheric and vacuum distillation to separate aviation kerosene, light white oil, and lubricating oil base oil according to the distillation range requirements of different products.

[0032] During the reaction process, an alkaline solution is used intermittently or continuously for on-line treatment of all catalysts.

[0033] During the hydrorefining process, in order to ensure the long-term stable operation of the catalyst, a certain amount of hydrogen sulfide needs to be maintained in the system. However, the sulfur content in coal tar is 5000 μg / g - 8000 μg / g, and the nitrogen content is 8000 μg / g - 10000 μg / g. According to the reaction between the hydrogen sulfide and ammonia generated during the hydrogenation process, there is still a certain amount of ammonia in the system, which is very likely to damage the acidic center of the hydrotreating catalyst and cause the hydrotreating catalyst to deactivate quickly. Therefore, in the existing coal tar hydrogenation plants, each enterprise injects a sulfiding agent into the system irregularly during the production process to maintain the hydrogen sulfide content in the system. In the present invention, the catalyst is treated with ammonia water during the production process, which weakens the influence of ammonia on the catalyst activity. Therefore, it is not necessary to supplement the sulfiding agent during the production process, indirectly reducing the emission of sulfides.

[0034] Preferably, hydrogenation protection catalysts are filled in the upper parts of the hydrofining reactor, the hydrodearomatization reactor, the hydroisomerization reactor and the deep de-aromatization reactor. The hydrogenation protection catalyst uses macroporous alumina as the carrier and uses molybdenum and / or nickel as the protective agent metal, with a content of 3%-11% of the total mass of the hydrogenation protection catalyst, and is in the shape of hexagonal honeycomb, Raschig ring, Pall ring or polyhedral hollow sphere, and the porosity is 0.5-0.8.

[0035] Optionally, the content of the protective agent metal can be 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11% of the total mass of the hydrogenation protection catalyst or any value between 3%-11%;

[0036] Since the content of various heavy metals (Cu, Ca, Mg, V, Fe, Na, Ni, etc.) in coal tar is as high as about 100 μg / g, especially the Fe content can account for about 50% of the total metal content, far exceeding the requirements of traditional hydrogenation for metal content (Fe≤2 μg / g), hydrogenation protection catalysts are filled in each reactor.

[0037] Preferably, the first active metal accounts for 3%-50% (preferably 35%-45%) of the total mass of the hydrofining catalyst.

[0038] Optionally, the proportion of the first active metal in the total mass of the hydrofining catalyst can be 3%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50% or any value between 3%-50%.

[0039] Preferably, the second active metal accounts for 0.05%-0.2% of the total mass of the hydrodearomatization catalyst, and the content of Ni accounts for 11%-15% of the total mass of the hydrodearomatization catalyst.

[0040] Optionally, the proportion of the second active metal in the total mass of the hydrodearomatization catalyst can be 0.05%, 0.1%, 0.15%, 0.2% or any value between 0.05%-0.2%, and the proportion of the content of Ni in the total mass of the hydrodearomatization catalyst can be 11%, 12%, 13%, 14%, 15% or any value between 11%-15%.

[0041] Preferably, the content of the first promoter metal is less than or equal to 0.01% of the total mass of the hydroisomerization catalyst.

[0042] Optionally, the content of the first promoter metal can be 0.001%, 0.005%, 0.01% of the total mass of the hydroisomerization catalyst or any value less than or equal to 0.01%.

[0043] Preferably, the content of the first active noble metal is 0.25% - 0.45% of the total mass of the hydroisomerization catalyst.

[0044] Optionally, the proportion of the content of the first active noble metal in the total mass of the hydroisomerization catalyst can be 0.25%, 0.30%, 0.35%, 0.40%, 0.45% or any value between 0.25% - 0.45%.

[0045] Preferably, the second promoter metal accounts for 0.01% - 0.03% of the total mass of the deep de-aromatization catalyst.

[0046] Optionally, the proportion of the second promoter metal in the total mass of the deep de-aromatization catalyst can be 0.01%, 0.02%, 0.03% or any value between 0.01% - 0.03%.

[0047] Preferably, the content of the second active noble metal is 0.15% - 0.45% of the total mass of the deep de-aromatization catalyst.

[0048] Optionally, the content of the second active noble metal can be 0.15%, 0.20%, 0.25%, 0.30%, 0.35%, 0.40%, 0.45% of the total mass of the deep de-aromatization catalyst or any value between 0.15% - 0.45%.

[0049] Preferably, the deep de-aromatization catalyst uses a mixture of macroporous alumina and mesoporous alumina with a mass ratio of 1:(1 - 3) as the carrier; the pore diameter of the macroporous alumina is 10nm - 20nm, and the pore diameter of the mesoporous alumina is 6nm - 10nm;

[0050] The alkaline solution is an ammonia aqueous solution.

[0051] Optionally, the mass ratio of macroporous alumina and mesoporous alumina can be 1:1, 1:2, 1:3 or any value between 1:(1 - 3); the pore diameter of the macroporous alumina can be 10nm, 15nm, 20nm or any value between 10nm - 20nm, and the pore diameter of the mesoporous alumina can be 6nm, 7nm, 8nm, 9nm, 10nm or any value between 6nm - 10nm;

[0052] Preferably, the reaction pressure of the hydrorefining reaction is 14.5 - 18.0 MPa, the reaction temperature is 325 - 365 °C, the volume space velocity is 0.5 - 1.1 h -1 , and the hydrogen-oil ratio is 1200 - 1800;

[0053] The reaction pressure of the hydrodearomatization reaction is 14.5 - 18.0 MPa, the reaction temperature is 190 - 240 °C, and the volume space velocity is 0.8 - 1.2 h -1 , and the hydrogen-oil ratio is 1200 - 1800;

[0054] The reaction pressure of the hydroisomerization reaction is 3.0 - 6.0 MPa, the reaction temperature is 310 - 360 °C, and the volume space velocity is 0.8 - 1.2 h -1 , and the hydrogen-oil ratio is 600 - 800;

[0055] The reaction pressure of the deep dearomatization reaction is 3.0 - 6.0 MPa, the reaction temperature is 140 - 190 °C, and the volume space velocity is 0.8 - 1.0 h -1 , and the hydrogen-oil ratio is 600 - 800.

[0056] Optionally, the reaction pressure of the hydrorefining reaction can be 14.5 MPa, 15.0 MPa, 15.5 MPa, 16.0 MPa, 16.5 MPa, 17.0 MPa, 17.5 MPa, 18.0 MPa or any value between 14.5 - 18.0 MPa; the reaction temperature can be 325 °C, 335 °C, 345 °C, 355 °C, 365 °C or any value between 325 - 365 °C; the volume space velocity can be 0.5 h -1 , 0.6 h -1 , 0.7 h -1 , 0.8 h -1 , 0.9 h -1 , 1.0 h -1 , 1.1 h -1 or any value between 0.5 - 1.1 h -1 ; the hydrogen-oil ratio can be 1200, 1300, 1400, 1500, 1600, 1700, 1800 or any value between 1200 - 1800; the reaction pressure of the hydrodearomatization reaction can be 14.5 MPa, 15.0 MPa, 15.5 MPa, 16.0 MPa, 16.5 MPa, 17.0 MPa, 17.5 MPa, 18.0 MPa or any value between 14.5 - 18.0 MPa; the reaction temperature can be 190 °C, 200 °C, 210 °C, 220 °C, 230 °C, 240 °C or any value between 190 - 240 °C; the volume space velocity can be 0.8 h -1 , 0.9 h -1 , 1.0 h -1 , 1.1 h -1 , 1.2 h -1 or 0.8 - 1.2 h -1Any value between; the hydrogen-oil ratio can be 1200, 1300, 1400, 1500, 1600, 1700, 1800 or any value between 1200 - 1800; the reaction pressure of the hydroisomerization reaction can be 3.0 MPa, 4.0 MPa, 5.0 MPa, 6.0 MPa or any value between 3.0 - 6.0 MPa; the reaction temperature can be 310 °C, 320 °C, 330 °C, 340 °C, 350 °C, 360 °C or any value between 310 - 360 °C; the volume hourly space velocity can be 0.8 h -1 , 0.9 h -1 , 1.0 h -1 , 1.1 h -1 , 1.2 h -1 or any value between 0.8 - 1.2 h -1 Any value between; the hydrogen-oil ratio can be 600, 700, 800 or any value between 600 - 800; the reaction pressure of the deep dearomatization reaction can be 3.0 MPa, 4.0 MPa, 5.0 MPa, 6.0 MPa or any value between 3.0 - 6.0 MPa; the reaction temperature can be 140 °C, 150 °C, 160 °C, 170 °C, 180 °C, 190 °C or any value between 140 - 190 °C; the volume hourly space velocity can be 0.8 h -1 , 0.9 h -1 , 1.0 h -1 or 0.8 - 1.0 h -1 Any value between; the hydrogen-oil ratio can be 600, 700, 800 or any value between 600 - 800.

[0057] Compared with the prior art, the beneficial effects of the present application include:

[0058] The method for preparing high-grade oil by hydrogenation of coal tar provided by the present application solves the problems that the sulfur, nitrogen, oxygen, heavy metals, and aromatic hydrocarbon contents in coal tar are high, cannot be completely removed, and a sulfurizing agent needs to be added during the production process to maintain the hydrogen sulfide concentration in the system to ensure the long-term operation of the catalyst in the first-stage hydrogenation; in the second-stage hydrogenation, a hydroisomerization catalyst is used to rearrange, ring-open, and saturate the molecular chains in coal tar, and the freezing point of the product is greatly reduced without random cracking to produce a product with higher added value.

[0059] It not only solves the problem of difficult removal of sulfur, nitrogen, and aromatic hydrocarbons in coal tar, but also changes the molecular structure of coal tar through the isomerization process, making it possible to be used as aviation kerosene, light white oil, and lubricating oil base oil with a high viscosity index, breaking the situation that traditional coal tar can only be used as low-end fuel oils such as gasoline and diesel. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] To more clearly illustrate the technical solutions of the embodiments of the present application, the accompanying drawings required for the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present application and should not be regarded as limiting the scope of the present application.

[0061] Figure 1 It is a schematic process flow diagram of the method for preparing high-grade oil products by hydrogenation of coal tar provided for the embodiment. Specific embodiments

[0062] The following will describe the implementation solutions of the present application in detail in conjunction with specific embodiments. However, those skilled in the art will understand that the following embodiments are only used to illustrate the present application and should not be regarded as limiting the scope of the present application. For those not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. For reagents or instruments not specified by the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0063] First, the composition of the coal tar raw materials used in the embodiments and comparative examples of the present application will be described, as shown in Table 1 for details:

[0064] Table 1 Coal tar composition

[0065]

[0066] Embodiment

[0067] As Figure 1 shown, this embodiment provides a method for preparing high-grade oil products by hydrogenation of coal tar, including:

[0068] S1. The coal tar is passed through a filter to remove impurities ≥ 15 μm, metered and pressurized by a hydrogenation feed pump 1, mixed with hydrogen, then enters a heat exchanger 1, is heated to 245 °C and then enters a heating furnace 1. The mixed material is heated to 335 °C and then enters a hydrofining reactor for hydrofining reaction to obtain a refined product;

[0069] The hydrofining reactor is filled with a hydrofining catalyst. The hydrofining catalyst uses macroporous alumina as a carrier, is calcined at 800 °C and then loaded with a first active metal under the condition of 95 °C. The first active metal includes Mo and Co; the first active metal accounts for 27% of the total mass of the hydrofining catalyst.

[0070] S2. The refined product is heat-exchanged to 215 °C through a heat exchanger 2 and then enters a hydrodearomatization reactor for hydrodearomatization reaction to obtain a dearomatized product;

[0071] The hydrodearomatization reactor is filled with a hydrodearomatization catalyst. The hydrodearomatization catalyst uses macroporous alumina as the carrier, is calcined at 450 °C and then impregnated with a second active metal, dried and calcined at 325 °C, then impregnated with Ni, and then dried and calcined at 480 °C; the second active metal is vanadium; the second active metal accounts for 0.1% of the total mass of the hydrodearomatization catalyst, and the content of Ni accounts for 12% of the total mass of the hydrodearomatization catalyst;

[0072] S3. The de-aromatization product is subjected to heat exchange, cooling, pressure reduction, gas-liquid separation, and the liquid phase is fractionated at atmospheric pressure. The naphtha and dry gas obtained from the atmospheric distillation are discharged from the top of the column. The dry gas is purified and used as fuel for the heating furnace and incorporated into the gas pipeline network; the liquid phase obtained from the atmospheric distillation is used as ethylene cracking feedstock or naphtha; the bottom material obtained from the atmospheric distillation is used as the feedstock for the second-stage hydrogenation;

[0073] S4. The second-stage hydrogenation feedstock is metered and pressurized by the second-stage hydrogenation feed pump 2, mixed with hydrogen, and heat-exchanged and then enters the heating furnace 2. The material is heated to 320 °C and enters the hydroisomerization reactor to carry out hydroisomerization reaction to obtain an isomerization product;

[0074] The hydroisomerization reactor is filled with a hydroisomerization catalyst. The hydroisomerization catalyst uses macroporous silicoaluminophosphate molecular sieves SAPO-11, ZSM-23, and ZSM-48 as the carrier. The carrier of the hydroisomerization catalyst is mixed with a binder, formed, dried at 75 °C, and calcined at a temperature not higher than 300 °C, and then impregnated with a first promoter metal, and the first promoter metal includes Mo and Co; after the impregnation is completed, it is dried and calcined at 315 °C, and then impregnated with an active noble metal, and the first active noble metal includes Re and Pd; the content of the first promoter metal is 0.01% of the total mass of the hydroisomerization catalyst; the content of the first active noble metal is 0.35% of the total mass of the hydroisomerization catalyst;

[0075] The hydroisomerization catalyst is passivated with tri-n-propylamine before use;

[0076] S5. The isomerization product is subjected to a fifth heat exchange to 260 °C and enters the deep de-aromatization reactor to carry out a deep de-aromatization reaction to obtain a deep de-aromatization product;

[0077] The deep de-aromatization reactor is filled with a deep de-aromatization catalyst. The deep de-aromatization catalyst uses a mixture of macroporous alumina and mesoporous alumina with a mass ratio of 1:2 as the carrier, uses Mg as the second promoter metal, and uses Pd as the second active noble metal; the second promoter metal accounts for 0.02% of the total mass of the deep de-aromatization catalyst, and the content of the second active noble metal is 0.3% of the total mass of the deep de-aromatization catalyst.

[0078] S6. The deep de-aromatization product is subjected to gas-liquid separation and pressure reduction and then enters the atmospheric and vacuum distillation to separate out aviation kerosene, light white oil, and lubricating oil base oil according to the requirements of the distillation range of different products;

[0079] During the reaction process, ammonia water is used intermittently or continuously for on-line treatment of all catalysts.

[0080] Hydrotreating catalysts are loaded in the upper parts of the hydrofining reactor, hydrodearomatization reactor, hydroisomerization reactor and deep de-aromatization reactor. The hydrotreating catalyst uses macroporous alumina as the carrier, is in a hexagonal honeycomb shape, has a porosity of 0.5 - 0.8, and the protective agent metals are molybdenum and nickel, with the total content of molybdenum and nickel being 10%.

[0081] Control experiment

[0082] Hydrogenation experiments were carried out on the coal tar in Yulin area. Two catalysts currently used in industrial applications (the selected catalysts are the catalysts used in the coal tar hydrogenation device in Yulin area, and the manufacturer is a domestic catalyst company) and the catalyst prepared in the present invention (Example) were tested under exactly the same process conditions.

[0083] The hydrofining reaction parameters and results are shown in Table 2:

[0084] Table 2 Hydrofining reaction parameters and results

[0085]

[0086] Among them, the compositions and related performance parameters of the above-mentioned Catalyst 1 and Catalyst 2 are shown in Table 3 below:

[0087] Table 3 Compositions and related performance parameters of Catalyst 1 and Catalyst 2

[0088]

[0089] During the above tests, sulfurizing agents were regularly injected into the system for Catalyst 1 and Catalyst 2 to maintain the hydrogen sulfide content in the system ≥ 200 μg / g, and no sulfurizing agent was added to the catalyst of the present invention.

[0090] Since the existing coal tar hydrogenation technology does not consider the aromatic hydrocarbon content, two catalysts with relatively stable industrial applications in China were selected in the present invention for comparative tests. The raw materials used in the tests were the products obtained by the present invention in Example 1, and the comparative tests were carried out under the same process conditions.

[0091] The hydrodearomatization reaction parameters and results are shown in Table 4:

[0092] Table 4 Hydrodearomatization reaction parameters and results

[0093]

[0094] Among them, the compositions and related performance parameters of the above-mentioned Catalyst 1 and Catalyst 2 are shown in Table 5 below:

[0095] Table 5 Composition and Related Performance Parameters of Catalyst 3 and Catalyst 4

[0096]

[0097] From the product aromatic hydrocarbon distribution data, it can be seen that the catalysts of the present invention and the existing catalysts have the same saturation ability for monocyclic and bicyclic aromatic hydrocarbons and can completely remove them; however, there are certain differences in the effects on aromatic hydrocarbons with three or more rings.

[0098] Since the second stage of the existing coal tar technology uses hydrocracking catalysts, the purpose is to maximize the cracking of raw materials to produce gasoline and diesel. Therefore, catalysts used in the petroleum industry for hydroisomerization of wax oil to produce lubricating base oil were selected for testing. To ensure the reliability of the test, hydroisomerization catalysts produced by two domestic enterprises with different compositions were used. The raw material used in the test was the raw material after hydrofining of coal tar with S≤2 μg / g, N 2 ≤2 μg / g and an aromatic hydrocarbon content of about 16%. To verify the performance of the catalyst, the catalyst passivation was carried out using a sulfiding agent.

[0099] The hydroisomerization reaction parameters and results are shown in Table 6:

[0100] Table 6 Hydroisomerization Reaction Parameters and Results

[0101]

[0102] Note: The purpose of the above experiment was to verify the effect of the isomerizing agent, so the hydrotreated product was not fractionated.

[0103] Among them, the composition and related performance parameters of the above-mentioned Catalyst 5 and Catalyst 6 are shown in Table 7 below:

[0104] Table 7 Composition and Related Performance Parameters of Catalyst 5 and Catalyst 6

[0105]

[0106] To verify the difference between passivating the hydroisomerizing agent with sulfide and tri-n-propylamine, the selected hydroisomerization catalyst was the existing catalyst, i.e., the existing Catalyst 6 in Table 7. The inspection results were expressed by the isomerization rate of the product after the catalyst was used for a certain period of time, and the raw material was n-hexadecane. The results are shown in Table 8:

[0107] Table 8 Differences in Different Passivating Agents

[0108]

[0109] As can be seen from Table 8, when using a sulfurizing agent as a passivator, the isomerization rate of the hydroisomerization catalyst always remains at about 89%, which is relatively stable. When using tri-n-propylamine as a passivator, the initial isomerization rate is not much different from that passivated by the sulfurizing agent. However, as the catalyst is used, its isomerization activity gradually recovers and finally remains at about 95%. This indicates that passivating with a sulfurizing agent completely destroys the initial activity of the hydroisomerization catalyst, while passivating the hydroisomerization catalyst with the passivator used in the present invention only inhibits the initial activity of the catalyst, and the inhibited activity will slowly recover as the catalyst is used.

[0110] Examples 2 - 7

[0111] To verify the reliability of the technology provided by the present invention, an overall verification was carried out according to the process. The feedstock oil was the coal tar from Yulin area.

[0112] The results are shown in Table 9:

[0113] Table 9 Results of Examples 2 - 7

[0114]

[0115] Table 9 shows that for the method provided in this application, the quality of the obtained product meets the national or industrial required indicators. The 2000h life experiment shows that the activity of the catalyst described in the present invention is stable and fully meets the requirements of industrial application.

[0116] Control experiment

[0117] In the present invention, the catalyst is treated with ammonia water during the production process. In this control experiment, the catalyst of Example 1 was used. Catalyst 7 was not treated with ammonia water, and Catalyst 8 was treated with ammonia water. A comparative experiment was carried out under the same coal tar feedstock and the same process conditions. The specific results are shown in Table 10:

[0118] Table 10 Control results

[0119]

[0120] Before the 1000h of the test, the activities of the two catalysts were basically not different. When it reached 1000h, the sulfur and nitrogen contents of the products obtained by Catalyst 7 gradually increased. By 2400h, the sulfur content of the product of Catalyst 7 had exceeded 10μg / g.

[0121] The present invention provides a method for producing aviation kerosene, lubricating oil base oil and other high-grade chemical raw materials from coal tar through a hydrogenation process. It changes the state of the original coal tar after fractionation to remove heavy components and then hydrogenation to produce fuel oil blending components such as gasoline and diesel. In the method used in this application, improvements are made to the protective agent, refining catalyst, and de-aromatization catalyst used in the first-stage hydrogenation in terms of materials, production processes, additives, etc., so that the first-stage hydrogenation can meet the processing of the whole fraction of coal tar. During the production process, no sulfurizing agent needs to be added, and S≤2μg / g and N 2 ≤2μg / g in the product; the second-stage hydrogenation method used in this application changes the original hydrogenation cracking process method and adopts the process method of "hydroisomerization-supplementary refining" of precious metals. A catalyst suitable for coal tar hydroisomerization and hydrotreating is invented, which does not damage the size of the molecular chains in coal tar, but only reorganizes and saturates the molecular chains to reduce the freezing point of coal tar to meet the requirements of high-grade products such as aviation kerosene and lubricating oil base oil; in the second-stage hydrogenation process, the original use of sulfide to permanently damage the initial activity of the hydroisomerization catalyst is changed to passivation with tri-n-propylamine that temporarily inhibits the initial activity of the catalyst, reducing the initial use temperature of the hydroisomerization catalyst and extending the service life of the catalyst.

[0122] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, rather than to limit them; although this application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of this application.

[0123] In addition, those skilled in the art can understand that although some of the embodiments herein include certain features included in other embodiments rather than other features, the combination of the features of different embodiments means that it is within the scope of this application and forms different embodiments. For example, in the above claims, any one of the claimed embodiments can be used in any combination. The information disclosed in this background art section is only intended to deepen the understanding of the overall background art of this application, and should not be regarded as an admission or any form of suggestion that this information constitutes the prior art known to those skilled in the art.

Claims

1. A method for preparing high-grade oil products by hydrogenation of coal tar, characterized in that, it includes: S1. Removing impurities ≥15μm from the coal tar through a filter, mixing with hydrogen after pressurization to obtain a mixed material, then performing the first heat exchange to 200 - 300°C, and then heating the mixed material to 320 - 380°C and feeding it into a hydrofining reactor to carry out hydrofining reaction to obtain a refined product; A hydrofining catalyst is filled in the hydrofining reactor. The hydrofining catalyst uses macroporous alumina as a carrier, is calcined at 600 - 1200°C, and then loaded with a first active metal under the condition of 80 - 120°C. The first active metal includes one or more of W, Mo, Ni, and Co; S2. The refined product is subjected to the second heat exchange to 180 - 260°C, and then enters a hydrodearomatization reactor to carry out hydrodearomatization reaction to obtain a dearomatized product; A hydrodearomatization catalyst is filled in the hydrodearomatization reactor. The hydrodearomatization catalyst uses macroporous alumina as a carrier, is calcined at 400 - 600°C, impregnated with a second active metal, dried, calcined at 300°C - 350°C, then impregnated with Ni, and then dried and calcined at 450 - 550°C; The second active metal includes one or more of vanadium, zirconium, and lanthanide metals; S3. The dearomatized product undergoes the third heat exchange, cooling, pressure reduction, gas-liquid separation. The liquid phase is fractionated at atmospheric pressure. The naphtha and dry gas obtained from the atmospheric distillation are discharged from the top of the tower. The dry gas is purified and used as fuel for the heating furnace and incorporated into the gas pipeline network; The liquid phase obtained from the atmospheric distillation is used as ethylene cracking stock or naphtha; The bottom material obtained from the atmospheric distillation is used as the feedstock for the second-stage hydrogenation; S4. The second-stage hydrogenation feedstock is pressurized, mixed with hydrogen, and heated to 290 - 360°C after the fourth heat exchange and then enters a hydroisomerization reactor to carry out hydroisomerization reaction to obtain an isomerized product; A hydroisomerization catalyst is filled in the hydroisomerization reactor. The hydroisomerization catalyst uses one or more of macroporous silicoaluminophosphate molecular sieves SAPO-11, SM-3, SSZ-32, ZSM-23, ZSM-35, and ZSM-48 as carriers. The carrier of the hydroisomerization catalyst is mixed with a binder, formed, dried under the condition of 60 - 80°C, calcined under the condition not higher than 300°C, and then impregnated and loaded with a first promoter metal. The first promoter metal includes multiple of Mo, Ni, V, Co, and Zn; After the impregnation is completed, it is dried and calcined at 290 - 330°C, and then impregnated with a first active noble metal. The first active noble metal includes one or more of Pt, Re, and Pd; The hydroisomerization catalyst is passivated with tri-n-propylamine before use; S5. The isomerized product is subjected to the fifth heat exchange to 160 - 280°C and enters a deep dearomatization reactor to carry out deep dearomatization reaction to obtain a deep dearomatized product; A deep dearomatization catalyst is filled in the deep dearomatization reactor. The deep dearomatization catalyst uses alumina as a carrier, uses one or more of Mg, Zn, and As as a second promoter, and uses Pt and / or Pd as a second active noble metal; S6. The deep de-aromatization product enters the atmospheric and vacuum distillation after gas-liquid separation and pressure reduction, and aviation kerosene, light white oil and lubricating oil base oil are separated according to the distillation range requirements of different products; During the reaction process, an alkaline solution is used intermittently or continuously to perform on-line treatment on all catalysts.

2. The method according to claim 1, characterized in that, Hydrogenation protection catalysts are filled in the upper parts of the hydrofining reactor, the hydro-de-aromatization reactor, the hydro-isomerization reactor and the deep de-aromatization reactor. The hydrogenation protection catalyst uses macroporous alumina as the carrier, and molybdenum and / or nickel as the protective agent metal, with a content of 3%-11% of the total mass of the hydrogenation protection catalyst, and is in the shape of hexagonal honeycomb, Raschig ring, Pall ring or polyhedral hollow sphere, and the porosity is 0.5-0.

8.

3. The method according to claim 1, characterized in that, The first active metal accounts for 3%-50% of the total mass of the hydrofining catalyst.

4. The method according to claim 1, characterized in that, The second active metal accounts for 0.05%-0.2% of the total mass of the hydro-de-aromatization catalyst, and the content of Ni accounts for 11%-15% of the total mass of the hydro-de-aromatization catalyst.

5. The method according to claim 1, characterized in that, The content of the first promoter metal is less than or equal to 0.01% of the total mass of the hydro-isomerization catalyst.

6. The method according to claim 1, characterized in that, The content of the first active noble metal is 0.25%-0.45% of the total mass of the hydro-isomerization catalyst.

7. The method according to claim 1, characterized in that, The second promoter accounts for 0.01%-0.03% of the total mass of the deep de-aromatization catalyst.

8. The method according to claim 1, characterized in that, The content of the second active noble metal is 0.15%-0.45% of the total mass of the deep de-aromatization catalyst.

9. The method according to claim 1, characterized in that, The deep de-aromatization catalyst uses a mixture of macroporous alumina and mesoporous alumina with a mass ratio of 1:(1-3) as the carrier; the pore diameter of the macroporous alumina is 10nm-20nm, and the pore diameter of the mesoporous alumina is 6nm-10nm; The alkaline solution is an ammonia water solution.

10. The method according to any one of claims 1-9, characterized in that, The reaction pressure of the hydrofining reaction is 14.5 - 18.0 MPa, the reaction temperature is 325 - 365 °C, the volume space velocity is 0.5 - 1.1 h -1 , and the hydrogen-oil ratio is 1200 - 1800; The reaction pressure of the hydrodearomatization reaction is 14.5 - 18.0 MPa, the reaction temperature is 190 - 240 °C, the volume space velocity is 0.8 - 1.2 h -1 , and the hydrogen-oil ratio is 1200 - 1800; The reaction pressure of the hydroisomerization reaction is 3.0 - 6.0 MPa, the reaction temperature is 310 - 360 °C, the volume hourly space velocity is 0.8 - 1.2 h -1 , and the hydrogen-oil ratio is 600 - 800; The reaction pressure of the deep de-aromatization reaction is 3.0 - 6.0 MPa, the reaction temperature is 140 - 190 °C, the volume space velocity is 0.8 - 1.0 h -1 , and the hydrogen-oil ratio is 600 - 800.

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