A processing method for catalytic diesel

Abstract

The present invention discloses a method for processing catalytic diesel, comprising the following steps: (1) mixing catalytic diesel with hydrogen and entering a hydrorefining reaction zone, contacting with a hydrorefining catalyst for reaction, and obtaining a hydrorefining reaction effluent; (2) in the presence of hydrogen, mixing the hydrorefining reaction effluent in step (1) with an alkali metal and entering an alkali metal treatment reaction zone for reaction; (3) subjecting the alkali metal treatment effluent obtained in step (2) to separation treatment to obtain an alkali metal treatment liquid phase product; (4) subjecting the alkali metal treatment liquid phase product in step (3) to entering a hydrocracking reaction zone, and subjecting the reaction effluent to gas-liquid separation and fractionation in sequence to obtain gas and light naphtha, heavy naphtha, and tail oil, wherein the heavy naphtha enters an aromatics extraction unit to obtain BTX. The method combines hydrorefining, alkali metal treatment, and hydrocracking processes to process catalytic diesel, and can effectively avoid oversaturation of aromatics and improve the BTX yield.

Description

Technical Field

[0001] The present invention relates to a method for processing catalytic diesel, in particular to a method for processing catalytic diesel to produce more BTX. Background Art

[0002] Catalytically cracked diesel, a product of the catalytic cracking unit, has a high sulfur content and is rich in aromatics. The aromatic content in catalytic diesel can reach as high as 70-90%, primarily consisting of single-, double-, and triple-ring aromatics. Single-ring aromatics are primarily indanes and tetralins, while polycyclic aromatics are primarily naphthalenes and acenaphthenes. For example, in a refinery's catalytic diesel, single-ring aromatics are primarily concentrated in the lighter fraction below 260°C, while double- and higher-ring aromatics are primarily concentrated in the heavier fraction (>260°C). Hydrogenation is currently the primary method for processing catalytic diesel. While traditional hydrorefining techniques can remove sulfur and nitrogen impurities from catalytic diesel, the hydrogenation process consumes a lot of hydrogen, and deep desulfurization can lead to oversaturation of aromatics, reducing fuel quality.

[0003] CN106047404A discloses a combined process for increasing the production of high-octane gasoline from low-quality catalytic cracking diesel. This process involves first passing low-quality catalytic cracking diesel through a hydrofining reactor under a hydrogen atmosphere and relatively mild refining conditions to selectively hydrogenate condensed aromatic hydrocarbons and remove sulfur and nitrogen. The refined liquid product then enters a lightweighting reactor equipped with a precious metal catalyst for hydrogenation and lightweighting, ultimately achieving the goal of increasing the production of high-octane gasoline. This method uses conventional hydrofining agents, which require stringent reaction conditions to achieve deep impurity removal and present the problem of oversaturation of aromatic hydrocarbons.

[0004] CN103897731A discloses a catalytic cracking diesel and C 10 + The method for producing light aromatics by mixing distillate oil comprises the following steps: firstly, catalytic cracking diesel, C 10 + The distillate oil is mixed with hydrogen and then subjected to a hydrorefining reaction to remove sulfur and nitrogen, saturate olefins, and appropriately saturate aromatics. The hydrorefined product is then extracted with an extraction solvent to obtain an aromatics-rich extracted oil and an alkane-rich raffinate oil. The raffinate oil serves as a clean diesel blending component, and the extracted oil is separated by distillation to obtain an aromatics extracted oil. The aromatics extracted oil is then subjected to a hydrocracking reaction, and the hydrocracking products are further cut and separated. The distillate oil product with a temperature greater than 195°C is used as a clean diesel blending component, and the distillate oil with a temperature less than 195°C is used as an aromatic feedstock and enters an aromatics processing unit to obtain light aromatics products and a clean gasoline blending component. The above method suffers from high extraction solvent loss and poor extraction efficiency. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the present invention provides a method for processing catalytic diesel, which combines hydrorefining, alkali metal treatment and hydrocracking processes to process catalytic diesel, can effectively avoid oversaturation of aromatics and improve BTX yield.

[0006] A method for processing catalytic diesel, comprising the following steps:

[0007] (1) Catalytic diesel and hydrogen are mixed and enter the hydrotreating reaction zone, where they are contacted with the hydrotreating catalyst to react and obtain a hydrotreating reaction effluent;

[0008] (2) In the presence of hydrogen, the effluent from the hydrotreating reaction in step (1) is mixed with an alkali metal and enters an alkali metal treatment reaction zone for reaction;

[0009] (3) separating and treating the alkali metal treatment effluent obtained in step (2) to obtain an alkali metal treatment liquid phase product;

[0010] (4) The alkali metal treated liquid product in step (3) enters the hydrocracking reaction zone, and the reaction effluent is sequentially subjected to gas-liquid separation and fractionation to obtain gas and light naphtha, heavy naphtha and tail oil. The heavy naphtha enters the aromatics extraction unit to obtain BTX.

[0011] In the method of the present invention, the catalytic diesel in step (1) is one of the main products of the catalytic cracking unit; the catalytic diesel is the 160°C-370°C fraction in the catalytic cracking full fraction product, preferably the 220°C-340°C fraction; the density of the catalytic diesel is generally 0.90 g / cm -3 -0.99 g / cm -3 The sulfur content is generally 200 μg / g-8000 μg / g, the nitrogen content is generally 100 μg / g-2000 μg / g, and the aromatic hydrocarbon content is generally 50 wt%-90 wt%, preferably 60 wt%-85 wt%.

[0012] In the method of the present invention, the catalytic diesel in step (1) is cut to obtain light distillate oil and heavy distillate oil, and the heavy distillate oil is mixed with hydrogen and enters the hydrotreating reaction zone; the cutting point is 250°C-300°C, preferably 260°C-275°C; the content of monocyclic aromatic hydrocarbons in the heavy distillate oil is 0.1 wt.%-10wt.%, preferably 0.2 wt.%-5wt.%, and more preferably 0.5 wt.%-2wt.%.

[0013] In the method of the present invention, the hydrorefining catalyst in step (1) includes a carrier and an active metal, wherein the carrier may be alumina and / or amorphous silica-alumina, and the content thereof is 45-90 wt% by mass; the active metal includes a main active metal and an auxiliary metal; the main active metal is a Group VIB metal component, such as tungsten and / or molybdenum, and the content thereof is 5-50 wt% by mass of the metal oxide; the auxiliary metal is a Group VIB metal component, such as cobalt and / or nickel, and the content thereof is 2-30 wt% by mass of the metal oxide.

[0014] In the method of the present invention, in step (1), the sulfur content of the hydrorefining effluent is controlled to be 50 μg / g-1000 μg / g, preferably 150 μg / g-850 μg / g, and more preferably 200 μg / g-500 μg / g; the nitrogen content is controlled to be 50 μg / g-800 μg / g, preferably 100 μg / g-500 μg / g, and more preferably 120 μg / g-200 μg / g. Specifically, in the present invention, the sulfur content of the hydrotreating effluent is controlled to be 50 μg / g-1000 μg / g, preferably 150 μg / g-850 μg / g, and more preferably 200 μg / g-500 μg / g; and the nitrogen content is controlled to be 50 μg / g-800 μg / g, preferably 100 μg / g-500 μg / g, and more preferably 120 μg / g-200 μg / g by controlling the operating conditions of the hydrotreating reactor.

[0015] In the method of the present invention, the process conditions of the hydrofining reaction zone in step (1) are compared with those of the conventional hydrofining reaction zone, in that the reaction pressure is 0.5 MPa-5.0 MPa lower, the average reaction temperature is 10°C-40°C lower, and the volume space velocity is 0.5-3.0 h higher. -1 Preferably, the reaction pressure is 1.0MPa-2.5MPa lower, the average reaction temperature is 15℃-25℃ lower, and the volume space velocity is 0.8-2.0 h higher. -1 The process conditions of the conventional hydrofining reaction zone are generally as follows: reaction pressure of 3.0 MPa-15.0 MPa, average reaction temperature of 300℃-450℃, volume space velocity of 0.5-10.0h -1 The preferred reaction pressure is 5.0 MPa-12.0 MPa, the average reaction temperature is 350 ℃-400 ℃, and the volume space velocity is 1.0-5.0h -1 .

[0016] In the method of the present invention, the hydrogen-to-oil volume ratio in the hydrorefining reaction zone in step (1) is 300 Nm 3 / m 3 -1500Nm 3 / m 3 , preferably 400Nm3 / m 3 -1200Nm 3 / m 3 .

[0017] In the method of the present invention, step (2) also introduces light distillate oil obtained by cutting catalytic diesel, and the light distillate oil is mixed with the hydrotreating reaction effluent in step (1) and alkali metal and enters the alkali metal treatment reaction zone for reaction. During the research process, it was found that when the catalytic diesel is cut at a cutting point of 260-275°C, the monocyclic aromatic hydrocarbons are mainly concentrated in the lighter fraction segment, while the dicyclic and higher aromatic hydrocarbons are mainly concentrated in the heavier fraction segment. The present invention cuts the catalytic diesel according to the distribution pattern of monocyclic aromatic hydrocarbons and dicyclic and higher aromatic hydrocarbons in the catalytic diesel, and the light distillate rich in monocyclic aromatic hydrocarbons directly enters the alkali metal treatment device for desulfurization and denitrogenation reactions, thereby avoiding the hydrogenation saturation reaction of monocyclic aromatic hydrocarbons in the hydrotreating device.

[0018] In the method of the present invention, the alkali metal in step (2) is at least one of lithium, sodium, potassium, rubidium, cesium and francium, preferably lithium, sodium or potassium, and more preferably sodium; the mass ratio of the alkali metal to the hydrorefining reaction effluent is (0.1-5.0):100, preferably (0.5-2.5):100.

[0019] In the method of the present invention, the reactor used in the alkali metal treatment reaction zone in step (2) is one or more of a tank reactor, a pipeline reactor and a tower reactor, preferably a tank reactor.

[0020] In the method of the present invention, the process conditions of the alkali metal treatment reaction zone in step (2) are generally as follows: reaction temperature 200°C-380°C, hydrogen partial pressure 0.5MPa-15.0MPa, reaction time or residence time 0.1h-2.0h, hydrogen to oil volume ratio 100Nm 3 / m 3 -1000Nm 3 / m 3 Preferably, the reaction temperature is 280-340°C, the hydrogen partial pressure is 2.0 MPa-8.0 MPa, the reaction time or residence time is 0.5 h-1.0 h, and the hydrogen-to-oil volume ratio is 350 Nm 3 / m 3 -750Nm 3 / m 3 .

[0021] In the method of the present invention, the separation treatment in step (3) is a solid-liquid separation treatment. There is no particular requirement for the method of solid-liquid separation, and any of the existing solid-liquid separation methods in the art can be used. Specifically, in the present invention, the solid-liquid separation method can be at least one of vacuum filtration, pressure filtration, filtration centrifugation, sedimentation centrifugation, or membrane filtration.

[0022] In the method of the present invention, the acid value of the liquid phase stream obtained by the separation treatment in step (3) is less than 0.85 mgKOH / g, preferably less than 0.35 mgKOH / g; the solid content is 15-500 ppm, preferably 25-150 ppm.

[0023] In the method of the present invention, the separation treatment process in step (3) is as follows: the alkali metal treatment effluent obtained in step (2) is subjected to a solid-liquid separation to obtain a first liquid phase stream; the first liquid phase stream is mixed with an auxiliary agent, and the mixture is subjected to a second solid-liquid separation to obtain a second liquid phase stream, wherein the auxiliary agent is at least one of formic acid, acetic acid, phosphoric acid, hydrochloric acid, and sulfuric acid; the mass ratio of the auxiliary agent to the first liquid phase stream is (1-10):100, preferably (3-7):100. The alkalinity value of the first liquid phase stream is controlled to be 15-30 mgKOH / g, preferably 11-20 mgKOH / g; the solid content is controlled to be 500-2000 ppm, preferably 500-1000 ppm. The acid value of the second liquid phase stream is controlled to be less than 0.85 mgKOH / g, preferably less than 0.35 mgKOH / g, and the solid content is controlled to be 15-500 ppm, preferably 25-150 ppm.

[0024] In the method of the present invention, in step (3), an acidic additive is optionally added under stirring at a suitable temperature of 100-300° C., preferably 150-250° C. The stirring rate is 100-1500 r / min, preferably 500-1000 r / min.

[0025] In the method of the present invention, the catalyst used in the hydrocracking reaction zone in step (4) includes a support and a metal active component; the support includes at least one of alumina, amorphous silica-alumina, and a molecular sieve, and the molecular sieve is typically a Y-type and / or β-type molecular sieve; the metal active component is a Group VI, Group VII, or Group VIII metal, metal oxide, or metal sulfide, preferably one or more of iron, chromium, molybdenum, tungsten, cobalt, or nickel. Based on the weight of the catalyst, the content of the metal active component as oxide is generally 10 to 35 wt%, and the content of the support by mass is generally 60 to 85 wt%.

[0026] In the method of the present invention, the process conditions of the hydrocracking reaction zone in step (4) are generally as follows: reaction pressure of 3.0MPa-18.0MPa, average reaction temperature of 320℃-450℃, volume space velocity of 1.0-8.0h -1 , hydrogen to oil volume ratio is 300Nm 3 / m 3 -1500Nm 3 / m 3The preferred reaction pressure is 5.0 MPa-15.0 MPa, the average reaction temperature is 350 ℃-420 ℃, and the volume space velocity is 1.0-3.0h -1 , hydrogen to oil volume ratio is 400Nm 3 / m 3 -1200Nm 3 / m 3 .

[0027] In the method of the present invention, the aromatics extraction in step (4) can adopt existing technologies, such as solvent liquid-liquid extraction method and extractive distillation method. Specifically in the present invention, the aromatics extraction adopts solvent liquid-liquid extraction method, and the solvent liquid-liquid extraction method includes Udex method (glycol solvent), Sulfolane method (cyclopentane solvent), Arosolvan method (N-methylpyrrolidone solvent), DMSO method (dimethyl sulfoxide solvent), Formex method (N-formylmorpholine solvent); the operating conditions of the aromatics extraction device are: the mass ratio of solvent to heavy naphtha is 1-10:1, the extraction temperature is 20-250℃, and the extraction pressure is 0.1-3MPa. Preferably, the mass ratio of solvent to heavy naphtha is 3-6:1, the extraction temperature is 80-150℃, and the extraction pressure is 0.5-1.0MPa.

[0028] In the method of the present invention, the tail oil in step (4) can be discharged from the device as a product, or can be recycled to the hydrofining reaction zone.

[0029] Compared with the prior art, the advantages of the present invention are:

[0030] (1) The method of the present invention organically combines hydrofining with an alkali metal treatment unit, controls the depth of desulfurization and denitrification reactions during the hydrofining process, and transfers difficult-to-remove sulfur- and nitrogen-containing compounds to the alkali metal treatment unit. On the one hand, it can fully utilize the advantages of the high selectivity of the desulfurization and denitrification reactions of the alkali metal treatment technology. On the other hand, it can reduce the operating conditions of the hydrofining unit, especially the reaction pressure, to avoid oversaturation of aromatics, thereby further improving the yield of light aromatics.

[0031] (2) After being treated in the hydrotreating unit, the viscosity of the catalytic diesel is reduced, which is beneficial to the contact and reaction between the alkali metal and the catalytic diesel in the alkali metal treatment unit, thereby improving the reaction effect.

[0032] (3) The catalytic diesel is cut according to the distribution pattern of monocyclic aromatic hydrocarbons and dicyclic or higher aromatic hydrocarbons in the catalytic diesel. The light fraction rich in monocyclic aromatic hydrocarbons directly enters the alkali metal treatment unit for desulfurization and denitrogenation reactions, avoiding the hydrogenation saturation reaction of monocyclic aromatic hydrocarbons in the hydrotreating unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1This is a schematic diagram of a catalytic diesel hydrogenation method used in an embodiment of the present invention.

[0034] Among them, 1 is catalytic diesel, 2 is hydrogen, 3 is hydrorefining reaction zone, 4 is hydrorefining reaction effluent, 5 is alkali metal, 6 is alkali metal treatment reaction zone, 7 is alkali metal treatment reaction effluent, 8 is a primary solid-liquid separation device, 9 is a solid-phase product obtained by primary solid-liquid separation treatment, 10 is a first liquid phase feed stream, 11 is a purification treatment device, 12 is gas, 13 is a solid-liquid two-phase mixture obtained by purification treatment, 14 is an acidic additive, 15 is a secondary solid-liquid separation device, 16 is a second liquid phase feed stream, 17 is a solid-phase product obtained by secondary solid-liquid separation treatment, 18 is a hydrocracking reaction zone, 19 is gas, 20 is light naphtha, 21 is heavy naphtha, and 22 is tail oil.

[0035] Figure 2 This is a schematic diagram of another catalytic diesel hydrogenation method used in an embodiment of the present invention.

[0036] Among them, 1 is catalytic diesel, 2 is a fractionating tower, 3 is catalytic cracking diesel light distillate oil, 4 is catalytic cracking diesel heavy distillate oil, 5 is hydrogen, 6 is a hydrotreating reaction zone, 7 is a hydrotreating reaction effluent, 8 is an alkali metal, 9 is an alkali metal treatment reaction zone, 10 is an alkali metal treatment reaction effluent, 11 is a primary solid-liquid separation device, 12 is a solid-phase product obtained by the primary solid-liquid separation treatment, 13 is a first liquid phase feed stream, 14 is a purification treatment device, 15 is a gas, 16 is a solid-liquid two-phase mixture obtained by the purification treatment, 17 is an acidic additive, 18 is a secondary solid-liquid separation device, 19 is a second liquid phase feed stream, 20 is a solid-phase product obtained by the secondary solid-liquid separation treatment, 21 is a hydrocracking reaction zone, 22 is a gas, 23 is light naphtha, 24 is heavy naphtha, and 25 is tail oil. Implementation Method

[0037] The method provided by the present invention is described below with reference to the accompanying drawings.

[0038] like Figure 1As shown, catalytic diesel 1 is mixed with hydrogen 2 and enters hydrofining reaction zone 3 for reaction to obtain hydrofining effluent 4; hydrofining effluent 4 is mixed with alkali metal 5 and enters alkali metal treatment reaction zone 6 for reaction to obtain alkali metal treatment reaction effluent 7; alkali metal treatment reaction effluent 7 enters primary solid-liquid separation device 8 for primary separation to obtain solid phase product 9 and first liquid phase stream 10, the first liquid phase stream 10 enters purification treatment device 11, and is mixed with acidic additive 14 for reaction to obtain gas phase products 12 such as hydrogen and hydrogen sulfide and solid-liquid two-phase mixture 13; the solid-liquid two-phase mixture 13 enters secondary solid-liquid separation device 15 for separation to obtain second liquid phase stream 16 and solid phase products 17 such as alkali metal salts, the second liquid phase stream 16 enters hydrocracking reaction zone 18 for cracking reaction, and obtains gas 19 and light naphtha 20, heavy naphtha 21 and tail oil 22 through gas-liquid separation and fractionation, wherein the heavy naphtha 21 is removed from the aromatics extraction device.

[0039] like Figure 2 As shown, catalytic diesel 1 enters a fractionating tower 2 for separation to obtain light distillate 3 and heavy distillate 4; the heavy distillate 4 is mixed with hydrogen 5 and enters a hydrotreating reaction zone 6 for reaction to obtain a hydrotreating effluent 7; the hydrotreating effluent 7 and the light distillate 3 are mixed with an alkali metal 8 and enter an alkali metal treatment reaction zone 9 for reaction to obtain an alkali metal treatment reaction effluent 10; the alkali metal treatment reaction effluent 10 enters a primary solid-liquid separation device 11 for primary separation to obtain a solid phase product 12 and a first liquid phase feed stream 13. The first liquid phase feed stream 13 is a liquid phase product. Stream 13 enters the purification treatment device 14, where it is mixed with the acidic additive 17 to react to obtain gaseous products 15 such as hydrogen and hydrogen sulfide and a solid-liquid two-phase mixture 16; the solid-liquid two-phase mixture 16 enters the secondary solid-liquid separation device 18 for separation to obtain a second liquid phase stream 19 and solid phase products 20 such as alkali metal salts. The second liquid phase stream 19 enters the hydrocracking reaction zone 21 for cracking reaction, and after gas-liquid separation and fractionation, a gas 22 and light naphtha 23, heavy naphtha 24 and tail oil 25 are obtained, wherein the heavy naphtha 24 is removed from the aromatics extraction device.

[0040] The following examples will further illustrate the method provided by the present invention, but are not intended to limit the present invention.

[0041] In the examples of the present invention and the comparative examples, the catalyst used in the hydrorefining reaction zone is FF-66 hydrorefining catalyst produced by Sinopec Catalyst Co., Ltd.; the catalyst used in the hydrocracking reaction zone is FC-70A hydrocracking catalyst produced by Sinopec Catalyst Co., Ltd.; the extraction solvent used in the aromatics extraction unit is N-methylpyrrolidone, the mass ratio of N-methylpyrrolidone to heavy naphtha is 5:1, the extraction temperature is 100° C., and the extraction pressure is 0.5 MPa.

[0042] In the embodiment of the present invention, the alkali metal used in the alkali metal treatment reaction zone is sodium; the auxiliary agent used in the separation treatment process is a mixture of acetic acid and phosphoric acid, and the mass ratio of acetic acid to phosphoric acid is 2:1.

[0043] Example 1

[0044] This embodiment adopts Figure 1 The process flow is shown.

[0045] (1) Catalytic diesel and hydrogen are mixed and enter the hydrotreating reaction zone, where they are contacted with the hydrotreating catalyst to react and obtain a hydrotreating reaction effluent;

[0046] (2) In the presence of hydrogen, the effluent from the hydrotreating reaction in step (1) is mixed with an alkali metal and enters an alkali metal treatment reaction zone for reaction;

[0047] (3) The alkali metal treatment effluent obtained in step (2) is subjected to separation treatment to obtain an alkali metal treatment liquid phase product; the separation treatment process is as follows: the alkali metal treatment effluent is subjected to a solid-liquid separation to obtain a first liquid phase stream; the first liquid phase stream is mixed with an auxiliary agent, and the mixed material is subjected to a second solid-liquid separation to obtain a second liquid phase stream;

[0048] (4) The alkali metal treated liquid product in step (3) enters the hydrocracking reaction zone, and the reaction effluent is sequentially subjected to gas-liquid separation and fractionation to obtain gas and light naphtha, heavy naphtha, and tail oil. The heavy naphtha enters the aromatics extraction unit for treatment to obtain BTX.

[0049] Example 2

[0050] The process flow of this embodiment is the same as that of embodiment 1.

[0051] Example 3

[0052] The process flow of this embodiment is the same as that of embodiment 1.

[0053] Example 4

[0054] This embodiment adopts Figure 2 The process flow is shown.

[0055] (1) Light distillate oil and heavy distillate oil are obtained by cutting catalytic diesel, and the heavy distillate oil is mixed with hydrogen and enters the hydrorefining reaction zone, contacts with the hydrorefining catalyst for reaction, and obtains the hydrorefining reaction effluent;

[0056] (2) In the presence of hydrogen, the hydrotreating reaction effluent in step (2) and the light distillate oil in step (1) are mixed with an alkali metal and enter an alkali metal treatment reaction zone for reaction;

[0057] (3) The alkali metal treatment effluent obtained in step (3) is subjected to separation treatment to obtain an alkali metal treatment liquid phase product; the separation treatment process is as follows: the alkali metal treatment effluent is subjected to a solid-liquid separation to obtain a first liquid phase stream; the first liquid phase stream is mixed with an auxiliary agent, and the mixed material is subjected to a second solid-liquid separation to obtain a second liquid phase stream;

[0058] (4) The alkali metal treated liquid product in step (4) enters the hydrocracking reaction zone, and the reaction effluent is sequentially subjected to gas-liquid separation and fractionation to obtain gas and light naphtha, heavy naphtha, and tail oil. The heavy naphtha enters the aromatics extraction unit for treatment to obtain BTX.

[0059] Example 5

[0060] The process flow of this embodiment is the same as that of Example 4.

[0061] The properties of the catalytic diesel feedstock are shown in Table 1; the operating conditions of the hydrotreating, alkali metal treatment and hydrocracking reaction zones are shown in Table 2; the operating conditions of the separation treatment are shown in Table 3; and the product properties are shown in Table 4.

[0062] Table 1 Catalytic diesel feedstock properties

[0063]

[0064] Table 2 Operating conditions of hydrotreating, alkali metal treatment and hydrocracking reaction zones

[0065]

[0066] Table 3 Separation treatment operating conditions

[0067]

[0068] Table 4 Product properties

[0069]

[0070] Comparative Example 1

[0071] The catalytic diesel first enters the hydrotreating reaction zone for a hydrogenation saturation reaction. The effluent from the hydrotreating reaction zone enters the hydrocracking reaction zone for a hydrocracking reaction. The reaction effluent undergoes gas-liquid separation and fractionation to produce gas, light naphtha, heavy naphtha, and tail oil. The heavy naphtha enters the aromatics extraction unit for processing to produce BTX. The operating conditions and reaction results are shown in Table 5.

[0072] Table 5 Operating conditions and reaction results of Comparative Example 1

[0073]

[0074] It can be seen from the test results of the examples and comparative examples that the processing method of the catalytic diesel of the present invention can effectively increase the heavy naphtha yield and the light aromatics content, and improve the BTX yield.

Claims

1. A method for processing catalytic diesel, characterized by: The method comprises the following steps: (1) Catalytic diesel and hydrogen are mixed and enter the hydrotreating reaction zone, where they are contacted with the hydrotreating catalyst to react and obtain a hydrotreating reaction effluent; (2) In the presence of hydrogen, the effluent from the hydrotreating reaction in step (1) is mixed with an alkali metal and enters an alkali metal treatment reaction zone for reaction; (3) separating and treating the alkali metal treatment effluent obtained in step (2) to obtain an alkali metal treatment liquid phase product; (4) The alkali metal treated liquid product in step (3) enters the hydrocracking reaction zone, and the reaction effluent is sequentially subjected to gas-liquid separation and fractionation to obtain gas and light naphtha, heavy naphtha and tail oil. The heavy naphtha enters the aromatics extraction unit to obtain BTX; In step (1), the catalytic diesel is cut to obtain light distillate oil and heavy distillate oil, and the heavy distillate oil is mixed with hydrogen and enters the hydrorefining reaction zone; the cutting point is 250°C-300°C; In step (2), a light distillate oil obtained by cutting catalytic diesel is also introduced, and the light distillate oil and the hydrofining reaction effluent in step (1) are mixed with alkali metal and enter the alkali metal treatment reaction zone for reaction; The process conditions of the alkali metal treatment reaction zone in step (2) are: reaction temperature 200℃-380℃, hydrogen partial pressure 0.5MPa-15.0MPa, reaction time 0.1h-2.0h, hydrogen oil volume ratio 100Nm 3 / m 3 -1000Nm 3 / m 3 ; The alkali metal in step (2) is at least one of lithium, sodium, and potassium; the mass ratio of the alkali metal to the hydrorefining reaction effluent is (0.1-5.0):100; The separation treatment process in step (3) is as follows: the alkali metal treatment effluent obtained in step (2) is subjected to a solid-liquid separation to obtain a first liquid phase stream; the first liquid phase stream is mixed with an auxiliary agent to obtain a mixed material, and the mixed material is subjected to a second solid-liquid separation to obtain an alkali metal treatment liquid phase product, wherein the auxiliary agent is at least one of formic acid, acetic acid, phosphoric acid, hydrochloric acid and sulfuric acid.

2. The method according to claim 1, wherein: The alkali metal in step (2) is sodium.

3. The method according to claim 1, wherein: The catalytic diesel in step (1) is the 160°C-370°C fraction in the catalytic cracking full fraction product; the density of the catalytic diesel is 0.90 g / cm -3 -0.99 g / cm -3 , the sulfur content is 200μg / g-8000 μg / g, the nitrogen content is 100μg / g-2000 μg / g, and the aromatic hydrocarbon content is 50 wt%-90 wt%.

4. The method according to claim 3, wherein: The catalytic diesel in step (1) is the 220°C-340°C fraction in the catalytic cracking full fraction product; the aromatic content of the catalytic diesel is 60 wt%-85 wt%.

5. The method according to claim 1, wherein: The cutting point in step (1) is 260°C-275°C.

6. The method according to claim 1, wherein: The content of monocyclic aromatic hydrocarbons in the heavy distillate oil is 0.1 wt.%-10 wt.%.

7. The method according to claim 6, characterized in that: The content of monocyclic aromatic hydrocarbons in the heavy distillate oil is 0.2 wt.%-5 wt.%.

8. The method according to claim 6, wherein: The content of monocyclic aromatic hydrocarbons in the heavy distillate oil is 0.5 wt.%-2 wt.%.

9. The method according to claim 1, wherein: In step (1), the sulfur content of the hydrotreating reaction effluent is controlled to be 50 μg / g-1000 μg / g, and the nitrogen content is controlled to be 50 μg / g-800 μg / g.

10. The method according to claim 9, characterized in that: In step (1), the sulfur content of the hydrotreating reaction effluent is controlled to be 150 μg / g-850 μg / g, and the nitrogen content is controlled to be 100 μg / g-500 μg / g.

11. The method according to claim 9, wherein: In step (1), the sulfur content of the hydrotreating reaction effluent is controlled to be 200 μg / g-500 μg / g, and the nitrogen content is controlled to be 120 μg / g-200 μg / g.

12. The method according to claim 1, wherein: Compared with the conventional hydrofining reaction zone process conditions, the reaction pressure in step (1) is 0.5MPa-5.0MPa lower, the average reaction temperature is 10℃-40℃ lower, and the volume space velocity is 0.5-3.0h higher. -1 The conventional hydrorefining reaction zone process conditions are: reaction pressure of 3.0MPa-15.0MPa, average reaction temperature of 300℃-450℃, volume space velocity of 0.5-10.0h -1 .

13. The method according to claim 12, wherein: Compared with the conventional hydrofining reaction zone process conditions, the reaction pressure in step (1) is 1.0MPa-2.5MPa lower, the average reaction temperature is 15℃-25℃ lower, and the volume space velocity is 0.8-2.0h higher. -1 .

14. The method according to claim 12, wherein: The process conditions of the conventional hydrofining reaction zone are: reaction pressure of 5.0MPa-12.0MPa, average reaction temperature of 350℃-400℃, volume space velocity of 1.0-5.0h -1 .

15. The method according to claim 1, wherein: The mass ratio of the alkali metal to the hydrorefining reaction effluent in step (2) is (0.5-2.5):

100.

16. The method according to claim 1, wherein: The reactor used in the alkali metal treatment reaction zone in step (2) is one or more of a kettle reactor, a pipeline reactor and a tower reactor.

17. The method according to claim 16, wherein: The reactor used in the alkali metal treatment reaction zone in step (2) is a kettle reactor.

18. The method according to claim 1, wherein: The process conditions of the alkali metal treatment reaction zone in step (2) are: reaction temperature 280℃-340℃, hydrogen partial pressure 2.0MPa-8.0MPa, reaction time 0.5h-1.0h, hydrogen oil volume ratio 350Nm 3 / m 3 -750Nm 3 / m 3 .

19. The method according to claim 1, wherein: The catalyst used in the hydrocracking reaction zone in step (4) includes a carrier and a metal active component; the carrier includes at least one of alumina, amorphous silica-alumina, and a molecular sieve, and the molecular sieve is a Y-type and / or β-type molecular sieve; the metal active component is a metal, metal oxide, or metal sulfide of Group VIB or Group VIII; based on the weight of the catalyst, the content of the metal active component in terms of oxide is 10-35wt%, and the content of the carrier in terms of mass is 60-85wt%.

20. The method according to claim 19, wherein: The metal active component is one or more of iron, chromium, molybdenum, tungsten, cobalt and nickel.

21. The method according to claim 1, wherein: The process conditions of the hydrocracking reaction zone in step (4) are: reaction pressure of 3.0MPa-18.0MPa, average reaction temperature of 320℃-450℃, volume space velocity of 1.0-8.0h -1 , hydrogen to oil volume ratio is 300Nm 3 / m 3 -1500Nm 3 / m 3 .

22. The method according to claim 21, characterized in that: The process conditions of the hydrocracking reaction zone in step (4) are: reaction pressure of 5.0MPa-15.0MPa, average reaction temperature of 350℃-420℃, volume space velocity of 1.0-3.0h -1 , hydrogen to oil volume ratio is 400Nm 3 / m 3 -1200Nm 3 / m 3 .

23. The method according to claim 1, wherein: The aromatics extraction in step (4) is a solvent liquid-liquid extraction method and / or an extractive distillation method.

24. The method according to claim 23, wherein: The aromatics extraction adopts a solvent liquid-liquid extraction method; the operating conditions of the solvent liquid-liquid extraction method are: a mass ratio of solvent to heavy naphtha is 1-10:1, an extraction temperature is 20-250°C, and an extraction pressure is 0.1-3MPa.

25. The method according to claim 24, wherein: The operating conditions of the solvent liquid-liquid extraction method are: a mass ratio of solvent to heavy naphtha of 3-6:1, an extraction temperature of 80-150° C., and an extraction pressure of 0.5-1.0 MPa.

26. The method according to claim 1, wherein: The tail oil in step (4) is circulated to the hydrotreating reaction zone.

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