Process for producing light aromatic hydrocarbon raw material through hydrogenation

Abstract

The invention provides a process for producing a light aromatic hydrocarbon raw material through hydrogenation. The process comprises the following steps: fractionating a first raw material to obtain a light raw material and a heavy raw material; the second raw material and the heavy raw material enter a hydrofining reaction zone, a hydrofining reaction generation material obtained after the reaction and the light raw material enter a hydrocracking reaction zone, a hydrocracking reaction generation material obtained after the reaction is separated, and gas, a light aromatic hydrocarbon raw material and tail oil are obtained. The process provided by the invention can realize high-added-value utilization of two difficult-to-process raw materials, improve the yield of the light aromatic hydrocarbon raw material, remarkably shorten the adjustment time at the initial stage of startup of a device, and obtain the qualified light aromatic hydrocarbon raw material under the condition of high yield at the initial stage of startup.

Description

Technical Field

[0001] This invention belongs to the field of petroleum refining technology and relates to a hydroconversion method, particularly a process for producing light aromatic hydrocarbon feedstocks by hydrogenation. Background Technology

[0002] With the adjustment of the global energy structure and the impact of new energy vehicles, the demand for fuel products has been greatly limited, making the transformation and upgrading of refining and chemical enterprises imperative. Among these, BTX (benzene, toluene, and xylene mixture), as an important chemical raw material, has become a target for the upgrading and transformation of major refining and chemical enterprises. Combining the concept of molecular refining, the targeted conversion of difficult-to-process fractions rich in aromatics in existing processing technologies into BTX will have extremely high economic value.

[0003] Catalytic cracking units account for a large proportion of China's oil refining structure. The large quantities of difficult-to-process catalytic diesel fuel have become crucial for the transformation and upgrading of refining enterprises. Converting catalytic diesel fuel into gasoline fractions via hydrocracking is currently the mainstream technology for major refineries. However, gasoline production is nearing saturation. Therefore, research began on producing BTX from catalytic diesel fuel to achieve high-value conversion. However, conventional hydrocracking processes involve aromatic saturation and ring-opening reactions, resulting in low BTX yields (~30%) in liquid products. Especially in the initial stages of unit operation, due to the high activity of the hydrorefining catalyst, the oversaturation of aromatics in the catalytic diesel fuel leads to BTX yields in liquid products that can only be maintained at 20%–25%, significantly impacting the economic efficiency of the unit.

[0004] Patent CN112295607A discloses a processing method for the lightening of heavy aromatics and a selective hydrogenation catalyst for heavy aromatics. The catalyst has the advantages of good activity and activity stability and high strength, thereby realizing the lightening and utilization of heavy aromatics. However, the catalyst cannot achieve precise catalysis during use, resulting in high hydrogen consumption and low BTX yield.

[0005] Patent CN104549456A discloses a catalyst for the lightening of heavy aromatics and its preparation method. The catalyst includes MCM-41 molecular sieve, alumina, and at least one metal selected from Pt, Pd, or Ir. It solves the problems of low selectivity and easy deactivation of monocyclic aromatics to a certain extent, but it cannot solve the problem of low BTX yield in the initial stage of the device.

[0006] Patent CN106675636A discloses a catalytic diesel hydroconversion process, in which the hydrocracking reactor is graded with hydrocracking catalysts of different reaction characteristics, thereby improving the conversion selectivity of catalytic diesel and increasing the yield of high-octane gasoline. Summary of the Invention

[0007] To address the bottlenecks in existing hydroconversion processes for BTX production, this invention provides a process for producing light aromatic feedstocks via hydroconversion. This process increases the yield of the target product, light aromatic feedstock, by controlling the feed distillation range. Simultaneously, it employs programmed control of the initial feed distillation range and reaction conditions to achieve high-value utilization of two difficult-to-process feedstocks, significantly improving the yield of light aromatic feedstocks. Furthermore, it significantly shortens the initial setup time, enabling the acquisition of qualified light aromatic feedstocks under high-yield conditions from the outset.

[0008] The first aspect of this invention provides a process for producing light aromatic hydrocarbon feedstock through hydrogenation, comprising the following steps:

[0009] (1) The first raw material is fractionated to obtain light raw material and heavy raw material;

[0010] (2) In the presence of hydrogen, the second raw material and the heavy raw material obtained in step (1) enter the hydrogenation refining reaction zone and the hydrogenation refining reaction product is obtained after the reaction.

[0011] (3) In the presence of hydrogen, the hydrorefining reaction product obtained in step (2) and the light raw material obtained in step (1) enter the hydrocracking reaction zone and react to obtain the hydrocracking reaction product.

[0012] (4) The hydrocracking reaction product obtained in step (3) is separated to obtain gas, light aromatics feedstock and tail oil; wherein, the tail oil is divided into two streams, the first stream of tail oil is recycled back to the hydrorefining reaction zone for processing, and the second stream of tail oil is recycled together with the first feedstock for fractionation processing.

[0013] In the above-mentioned hydrogenation process for producing light aromatics, as a preferred embodiment, the first feedstock in step (1) is a hydrocarbon compound rich in monocyclic aromatics, wherein the monocyclic aromatic content is 40wt% to 75wt%, preferably 50wt% to 65wt%. Furthermore, the initial boiling point of the first feedstock is generally 50 to 200°C, preferably 65 to 165°C, and the final boiling point is generally 200 to 370°C, preferably 220 to 325°C. In a further preferred embodiment, the first feedstock can be at least one of reformed heavy aromatics, cracked gasoline heavy aromatics, C9 heavy aromatics, or aromatic components rich in the adsorption unit, preferably reformed heavy aromatics.

[0014] In the above-mentioned hydrogenation process for producing light aromatics feedstock, as a preferred embodiment, the cutting temperature of the light and heavy feedstocks in step (1) is 162-200°C, preferably 165-199°C.

[0015] In the above-mentioned hydrogenation process for producing light aromatics feedstock, as a preferred embodiment, the cutting temperatures of the light and heavy feedstocks in step (1) are dynamically adjusted during the initial operation of the unit. Starting from the moment the unit switches from operating oil to feedstock, the cutting temperatures T of the light and heavy feedstocks are continuously adjusted. h Real-time dynamic adjustments are made. Specifically, the corresponding cutting temperature (T) can be determined using a preset function based on the current time's distance from the raw material entry point (duration (h)). h );

[0016] The same represents the cutting temperature (T) of light and heavy raw materials. h The preset function relating the duration (h) to the time (h) is as follows:

[0017] T h =8.2*Ln(h+0.2)+175;

[0018] Wherein, the duration (h) is the time elapsed since the current moment when switching to the raw material, and the duration is an integer value in days; in this embodiment of the invention, the time point at which to stop adjusting the cutting temperature of light and heavy raw materials can be determined by setting the maximum value of the duration (h).

[0019] In practical applications, the maximum value of the duration (h) is no greater than 25;

[0020] Furthermore, the maximum value of the duration (h) is preferably 10 to 25, and more preferably 12 to 20 (e.g., 12, 13, 14, 15, 16, 17, 18, 19, 20); after h reaches the maximum value, the cutting temperature of the light and heavy raw materials is stopped and kept constant.

[0021] In the above-mentioned hydrogenation process for producing light aromatics feedstock, as a preferred embodiment, the hydrogen-to-oil volume ratio in the hydrorefining reaction zone is dynamically adjusted during the initial operation of the unit. Starting from the moment the unit switches from operating oil to feedstock, the hydrogen-to-oil volume ratio in the hydrorefining reaction zone is continuously and dynamically adjusted in real time. Specifically, the corresponding hydrogen-to-oil volume ratio (V0) can be determined using a preset function based on the time elapsed since the switch to feedstock (duration (h)). h );

[0022] Same as expressing the hydrogen-to-oil volume ratio (V h The preset function relating the duration (h) to the time (h) is as follows:

[0023] V h =-1.168h 2 +46.532h+760.86;

[0024] Wherein, the duration (h) is the time elapsed since the current moment when switching to the raw material, and the duration is measured in days; in this embodiment of the invention, the time point at which to stop adjusting the hydrogen-oil volume ratio can be determined by setting the maximum value of the duration (h).

[0025] In practical applications, the maximum value of the duration (h) is no greater than 32;

[0026] Furthermore, the preferred maximum value of the duration (h) is 20 to 32, and more preferably 25 to 30 (e.g., 25, 26, 27, 28, 29, 30); after h reaches the maximum value, the hydrogen-oil volume ratio is stopped and kept constant.

[0027] In the above-mentioned process for producing light aromatic feedstocks through hydrogenation, as a preferred embodiment, the hydrogen-to-oil volume ratio in the hydrocracking reaction zone changes with the hydrogen-to-oil volume ratio in the hydrorefining reaction zone, and does not require separate adjustment.

[0028] In the above-mentioned hydrogenation process for producing light aromatics, as a preferred embodiment, the second feedstock is a hydrocarbon compound rich in aromatics, wherein the total aromatic content is 60wt%–90wt%, preferably 70wt%–90wt%; the bicyclic aromatic content is 35wt%–55wt%, preferably 40wt%–50wt%; and the content of tricyclic or higher aromatics is 2wt%–12wt%, preferably 3wt%–8wt%. Furthermore, the initial boiling point of the second feedstock is generally 160–230℃, and the final boiling point is generally 300–360℃. In a further preferred embodiment, the second feedstock can be at least one of catalytic cracking diesel (FCC diesel), heavy oil high-efficiency catalytic cracking diesel (RTC), catalytic cracking process diesel that produces more isoalkane (MIP diesel), and catalytic cracking diesel (DCC diesel), preferably catalytic cracking diesel.

[0029] In the above-mentioned hydrogenation process for producing light aromatics feedstock, as a preferred embodiment, the second feedstock in step (2) and the heavy feedstock obtained in step (1) are respectively fed into the hydrogenation refining reaction zone through different inlets for processing. The first inlet is located at the top or bottom of the reactor (at the bottom of the reactor when feeding from below (using an upflow reactor), and at the top of the reactor when feeding from above). The second feedstock enters through the first inlet. The second inlet is located on the shell of the reactor. The heavy feedstock obtained in step (1) preferably enters through the second inlet. The catalyst loading volume between the first inlet and the second inlet is 10% to 60% of the total catalyst loading volume of the reactor, and more preferably 12% to 34%.

[0030] In the above-mentioned hydrogenation process for producing light aromatics feedstock, as a preferred embodiment, the mass ratio of the first feedstock to the second feedstock is 0.05 to 0.30, and more preferably 0.09 to 0.20.

[0031] In the above-mentioned hydrogenation process for producing light aromatics, as a preferred embodiment, the hydrogenation refining reaction zone in step (2) is filled with a hydrogenation refining catalyst. The hydrogenation refining catalyst includes a hydrogenation active metal component and a support. The hydrogenation active metal can be one or more metal elements from Group VIB, Group VIIB, and Group VIII, specifically selected from at least one of Co, Mo, Ni, and W as the hydrogenation active metal component. The support is generally an inorganic refractory oxide such as alumina or silicon dioxide. The hydrogenation refining catalyst can be a commercially available product or prepared according to common knowledge in the field. Specifically, commercial hydrogenation catalysts such as FHUDS-8, FF-66, FF-36, and FF-56 developed by Sinopec (Dalian) Petrochemical Research Institute Co., Ltd. (FRIPP) can be used.

[0032] In the above-mentioned hydrogenation process for producing light aromatics feedstock, as a preferred embodiment, the hydrogenation refining reaction zone in step (2) is provided with 1 to 5 catalyst beds, preferably 2 to 4 catalyst beds, and even more preferably 2 catalyst beds.

[0033] In the above-mentioned hydrogenation process for producing light aromatics feedstock, as a preferred embodiment, the hydrogenation refining catalyst between the first feed inlet and the second feed inlet in step (2) is named hydrogenation refining catalyst A, and the hydrogenation refining catalyst between the second feed inlet and the reactor outlet is named hydrogenation refining catalyst B. The weight ratio of the hydrogenation active metal components of hydrogenation refining catalyst A to hydrogenation refining catalyst B is 0.75 to 1.0, preferably 0.88 to 0.98.

[0034] In the above-mentioned process for producing light aromatics feedstock through hydrogenation, as a preferred embodiment, the hydrocracking reaction zone in step (3) is filled with a hydrocracking catalyst. The hydrocracking catalyst includes a hydrocracking active metal component and a support. The hydrocracking active metal can be one or more metal elements from Group VIB, Group VIIB, and Group VIII, specifically selected from at least one of Co, Mo, Ni, and W as the hydrocracking active metal component. The support typically includes amorphous silica-alumina and molecular sieves. The hydrocracking catalyst can be a commercially available product or prepared according to common knowledge in the field. Specifically, commercially available hydrocracking catalysts such as FC-70A, FC-70B, FC-90, and FC-52 developed by Sinopec (Dalian) Petrochemical Research Institute Co., Ltd. (FRIPP) can be used.

[0035] In the above-mentioned hydrogenation process for producing light aromatic feedstock, as a preferred embodiment, the hydrocracking reaction zone in step (3) is provided with 1 to 5 catalyst beds, preferably 2 to 3 catalyst beds.

[0036] In the above-mentioned hydrogenation process for producing light aromatics feedstock, as a preferred embodiment, the separation in step (4) generally includes gas-liquid separation and fractionation. The gas-liquid separation generally uses a gas-liquid separator to separate the hydrocracking reaction product obtained in step (3) into gaseous and liquid phases. The gaseous phase, after optional purification treatment (generally desulfurization treatment), is processed by a circulating hydrogen compressor and can be used as circulating hydrogen. The separated liquid phase is further separated in a fractionation tower to obtain gas, light aromatics feedstock, and tail oil.

[0037] In the above-mentioned hydrogenation process for producing light aromatics feedstock, the cutting point between the light aromatics feedstock and the tail oil is 170–220°C, preferably 180–195°C.

[0038] In the above-mentioned hydrogenation process for producing light aromatics feedstock, as a preferred embodiment, the operating conditions of the hydrogenation refining reaction zone are as follows: reaction temperature is 320–420℃, preferably 360–390℃; reaction pressure is 5.0–16.0 MPa, preferably 6.0–12.0 MPa; volume hourly space velocity (calculated based on the second feedstock) is 0.1–5.0 h⁻¹. -1 Preferably, it is 1.0 to 2.0 hours. -1 The hydrogen-to-oil volume ratio is calculated using the formula given above.

[0039] In the above-mentioned hydrogenation process for producing light aromatics feedstock, as a preferred embodiment, the operating conditions of the hydrocracking reaction zone are as follows: reaction temperature is 340–420℃, preferably 350–405℃; reaction pressure is 5.0–16.0 MPa, preferably 6.0–12.0 MPa; volume hourly space velocity (calculated based on the second feedstock) is 0.5–5.0 h⁻¹. -1 Preferably, it is 0.8 to 2.5 hours. -1 ;

[0040] In the above-mentioned hydrogenation process for producing light aromatics feedstock, as a preferred embodiment, the distribution ratio of the first and second tail oil streams in step (4) is dynamically adjusted during the initial operation of the unit. Starting from the moment the unit switches from operating oil to feedstock, the ratio Y of the first tail oil stream circulating back to the hydrogenation refining reaction zone to the total tail oil is adjusted. h Continuous adjustments are made. Specifically, based on the current time elapsed since the start of the feedstock cycle (duration (h)), a preset function is used to determine the proportion (Y) of the first tail oil stream circulating back to the hydrorefining reaction zone relative to the total tail oil. hThe remainder is the second tail oil, which is fractionated together with the first feedstock.

[0041] The proportion of the first tail oil stream in the hydrorefining reaction zone to the total tail oil (Y) h The preset function relating the duration (h) to the time (h) is as follows:

[0042] Y h =(0.0601h) 2 -4.3955h+88.148) / 100;

[0043] Wherein, the duration (h) is the time elapsed since the current moment when switching to the raw material, and the duration is an integer value in days; in this embodiment of the invention, the proportion of the first tail oil in the total tail oil to stop adjusting the circulation back to the hydrorefining reaction zone can be determined by setting the maximum value of the duration (h).

[0044] In practical applications, the maximum value of the duration (h) is no greater than 32;

[0045] Furthermore, the preferred maximum value of the duration (h) is 20 to 32, and more preferably 25 to 30; after h reaches the maximum value, the adjustment of the proportion of the first tail oil in the hydrorefining reaction zone to the total tail oil is stopped and maintained at a constant value.

[0046] A second aspect of the present invention provides a process for producing BTX by hydrogenation, wherein the process steps are as follows:

[0047] S1: Raw material for producing light aromatics;

[0048] S2: Use the light aromatics raw material obtained in step S1 as raw material to produce BTX.

[0049] In the above-mentioned hydrogenation process for producing BTX, as a preferred embodiment, the process for producing light aromatic feedstock in step S1 can be adopted as described above.

[0050] In the above-mentioned hydrogenation process for producing BTX, as a preferred embodiment, the production of BTX in step S2 can specifically adopt an aromatic extraction process, in which aromatics are separated from the light aromatic feedstock produced in S1 using an extractant. The solvent is sulfolane, the solvent-to-oil ratio is 0.1-20, and the operating temperature is 80-150°C.

[0051] Compared with existing technologies, the hydrogenation process for producing light aromatics provided by this invention has one or more of the following effects:

[0052] (1) The raw materials rich in aromatics are components that are difficult to utilize in refineries with high added value. If the two raw materials in this invention are mixed and directly processed by conventional hydrocracking full-cycle process, the processing difficulty of the refining section will be significantly increased. Not only is it necessary to configure a catalyst with high hydrogenation activity, but there are also problems such as low yield of the target product BTX and short operation cycle of the unit.

[0053] (2) Existing processes for producing BTX via hydroconversion of catalytic diesel are limited by the reaction pathway and the aromatic content in the feedstock, resulting in a maximum BTX content of only 30%–35% in the product, severely restricting the economic efficiency of the plant. The processing technology provided by this invention achieves precise catalysis by introducing a first feedstock and optimizing the reaction pathway. Using the concept of molecular refining, based on the characteristics of the first feedstock's molecular structure, the portion rich in monocyclic aromatics enters the hydrocracking reactor directly without hydrosaturation, while the portion requiring saturation enters the reactor in the middle section of the hydrorefining reactor, reducing the risk of oversaturation of the ideal components. Simultaneously, a reaction zone with increased bicyclic aromatic concentration is established in the lower part of the hydrorefining reactor, significantly increasing the retention rate of monocyclic aromatics in the second feedstock. This results in a 5–15 percentage point increase in BTX content in the product compared to conventional technologies, leading to significant economic benefits.

[0054] (3) In the initial stage of traditional catalytic diesel hydroconversion to BTX production, the high activity of the hydrorefining catalyst leads to a higher-than-expected saturation depth, resulting in a low BTX content (20%–25%) in the initial product. As the activity of the hydrorefining catalyst stabilizes, the gasoline octane number rises to over 30%, typically requiring an adjustment period of nearly 30 days. Actively reducing the activity of the loaded hydrorefining catalyst would shorten the unit's operating cycle. In this invention, the molecular characteristics of heavy aromatics and circulating tail oil are utilized to allow them to enter the hydrorefining reactor through different inlets, increasing the volume hourly space velocity (VHSV) in the refining section. Simultaneously, considering the characteristic that the hydrorefining catalyst's activity is high initially and gradually decreases to a stable level over time, a program adjustment design is implemented, coupled with the stable activity stage of the hydrorefining catalyst. Specifically, during the initial stage of high catalyst activity, a large amount of circulating oil enters through the refining reactor inlet to increase the VHSV in the refining section, matching the change in hydrorefining catalyst activity and ensuring a high BTX content in the initial stage of unit startup.

[0055] (4) In the production process of this invention, the first raw material is difficult to process. Conventional hydrocracking processes will saturate the monocyclic aromatic hydrocarbons into cycloalkanes, which will lead to a decrease in the yield of the target product and a significant increase in hydrogen consumption, thus greatly increasing the production cost of the equipment. The production process provided by this invention utilizes the high aromatic hydrocarbon content of the first raw material to produce BTX, thereby improving its economic value. After the first raw material is cut, only the heavy raw material rich in polycyclic aromatic hydrocarbons is fed into the hydrorefining reactor for aromatic saturation, while the component rich in monocyclic aromatic hydrocarbons is directly fed into the hydrocracking reactor. Attached Figure Description

[0056] Figure 1 This is a schematic diagram of the hydrogenation process for producing light aromatic hydrocarbon feedstock according to the present invention.

[0057] Wherein, 1-Second feedstock; 2-Hydrorefining reaction zone; 3-First feedstock; 4-Light feedstock; 5-Preliminary fractionation tower; 6-Heavy feedstock; 7-Hydrorefining reaction product; 8-Mixture of light feedstock and hydrorefining reaction product; 9-Hydrocracking reaction zone; 10-Hydrocracking reaction product; 11-Gas-liquid separator; 12-Liquid phase material; 13-Fracturing tower; 14-Gas product; 15-Light aromatics feedstock; 16-Tail oil; 17-Gas phase material; 18-Recycled hydrogen compressor; 19-Recycled hydrogen; 20-New hydrogen; 21-First tail oil; 22-Second tail oil; 23-Aromatics extraction unit; 24-Rapid oil; 25-BTX. Detailed Implementation

[0058] The technical solution and technical effects of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0059] Unless otherwise expressly stated, throughout the specification and claims, the term "comprising" or its variations such as "including" or "comprises" shall be understood to include the stated elements or components without excluding other elements or other components.

[0060] In this document, the terms "first," "second," etc., are used to distinguish two different elements or parts, and are not used to define specific positions or relative relationships. In other words, in some embodiments, the terms "first," "second," etc., can also be used interchangeably.

[0061] All publications, patent applications, patents, and other references mentioned in this specification are incorporated herein by reference. Unless otherwise defined, all technical and scientific terms used in this specification have the meanings commonly understood by those skilled in the art. In case of conflict, the definitions in this specification shall prevail.

[0062] When this specification uses the prefixes “known to those skilled in the art,” “prior art,” or similar terms to derive materials, substances, methods, steps, apparatus, or components, the objects derived from such prefixes cover those commonly used in the art at the time of this application, but also include those that are not currently commonly used but will become generally recognized in the art as suitable for similar purposes.

[0063] In the context of this invention, all numerical values ​​of parameters (e.g., quantity or condition) should be understood to be modified by the term “about” in all cases, regardless of whether “about” actually appears before the numerical value.

[0064] In the context of this invention, "substantially" means that deviations that are acceptable or considered reasonable to those skilled in the art are permitted, such as deviations within ±5%, ±2%, ±1%, ±0.5%, or ±0.1%.

[0065] Unless otherwise specified, all percentages, parts, ratios, etc. mentioned in this instruction manual are based on weight, and the pressure is gauge pressure.

[0066] In the context of this invention, any two or more embodiments or aspects of this invention can be arbitrarily combined, and the resulting technical solutions are part of the original disclosure of this specification and also fall within the protection scope of this invention.

[0067] Combination Figure 1 This invention provides a process for producing light aromatics feedstock via hydrogenation. First feedstock 3 enters a primary fractionation tower 5 and is split into two streams: light feedstock 4 and heavy feedstock 6. In the presence of hydrogen (including fresh hydrogen 20 and recycled hydrogen 19), the second feedstock 1 enters a hydrorefining reactor 2 through a first inlet at the top of the hydrorefining reactor. The heavy feedstock 6 preferably enters the hydrorefining reactor 2 through a second inlet in the middle of the reactor for reaction. The resulting hydrorefined product 7 is mixed with the light feedstock 4 and then enters a hydrocracking reactor 9. In the presence of hydrogen (including fresh hydrogen 20... The hydrogen (19) undergoes a hydrocracking reaction with recycled hydrogen. The resulting hydrocracking product (10) enters a gas-liquid separator (11) for gas-liquid separation, yielding a gaseous product (17) and a liquid product (12). The gaseous product (17) is compressed by a recycled hydrogen compressor (18) and used as recycled hydrogen (19). The liquid product (12) enters a fractionation tower (13) for separation, yielding a gaseous product (14), a light aromatic feedstock (15), and tail oil (16). The tail oil is divided into two streams: the first stream (tail oil 21) is recycled to the primary fractionation tower for processing with the first feedstock, and the second stream (tail oil 22) is recycled to the hydrorefining reactor for processing with the second feedstock (1). The separated light aromatic feedstock (15) is processed in an aromatics extraction unit to obtain raffinate oil (24) and BTX (25).

[0068] In the context of this invention, the first feedstock used is reformed heavy aromatics, and the second feedstock is catalytic cracked diesel oil, the specific properties of which are shown in Table 1.

[0069] Table 1 Properties of Raw Materials

[0070]

[0071]

[0072] Example 1

[0073] use Figure 1 The process flow shown is illustrated in Table 1, and the properties of the first and second raw materials are listed below. The distribution ratio of the two tail oil streams is dynamically adjusted during the initial operation of the unit. The proportion of the first tail oil stream circulating to the hydrorefining reactor relative to the total tail oil is determined according to Y... h =(0.0601h) 2 The temperature is adjusted using (-4.3955h+88.148) / 100, with a control cycle of 30 days. The cutting temperature of the primary fractionation tower is dynamically adjusted during the initial startup phase, according to T... h =8.2*Ln(h+0.2)+175, with a control cycle of 18 days. The hydrogen-to-oil volume ratio in the hydrorefining reactor is dynamically adjusted during the initial startup phase, according to V h =-1.168h 2 The control period is +46.532h +760.86, with a control cycle of 25 days. The volume of catalyst that can be loaded at the top of the second feed inlet of the hydrorefining reactor accounts for 34% of the total catalyst loading volume of the hydrorefining reactor, and the feed mass ratio of the first feedstock to the second feedstock is 0.20. The weight ratio of the hydrorefining active metal component of the FF-66 catalyst loaded at the top of the second feed inlet to that loaded at the bottom of the second feed inlet of the hydrorefining reactor is 0.88. The hydrocracking catalyst used is FC-70A, the cut-off temperature of the light aromatics feedstock and tail oil is 190℃, and the reaction pressure is 7.0MPa. The volumetric space velocity (VHSV) of the hydrorefining reactor (calculated based on the second feedstock) is 2.0h. -1 The volumetric space velocity (using the second feedstock) of the hydrocracking reactor is 1.5 h⁻¹. -1 The operating temperature of the hydrorefining reactor was adjusted to control the nitrogen content of the refined oil to 10 ppm. The temperature of the hydrocracking reactor was adjusted based on a single-pass conversion rate of 50%. The solvent used in the aromatics extraction unit was sulfolane, with a solvent-to-oil ratio of 15 and a processing temperature of 90℃. The reaction results are shown in Table 2.

[0074] Example 2

[0075] use Figure 1The process flow shown is illustrated in Table 1, and the properties of the first and second raw materials are listed below. The distribution ratio of the two tail oil streams is dynamically adjusted during the initial operation of the unit. The proportion of the first tail oil stream circulating to the hydrorefining reactor relative to the total tail oil is determined according to Y... h =(0.0601h) 2 The temperature is controlled by adjusting the value of (-4.3955h+88.148) / 100, with a control cycle of 25 days. The cutting temperature of the primary fractionation tower is dynamically adjusted during the initial startup phase, according to T... h =8.2*Ln(h+0.2)+175, with a control cycle of 16 days. The hydrogen-to-oil volume ratio in the hydrorefining reactor is dynamically adjusted during the initial startup phase, according to V h =-1.168h 2 The control period is +46.532h +760.86, with a control cycle of 28 days. The volume of catalyst that can be loaded at the top of the second feed inlet of the hydrorefining reactor accounts for 20% of the total catalyst loading volume of the hydrorefining reactor, and the feed mass ratio of the first feedstock to the second feedstock is 0.10. The weight ratio of the hydrorefining active metal component of the FF-76 catalyst loaded at the top of the second feed inlet to that loaded at the bottom of the second feed inlet of the hydrorefining reactor is 0.90. The hydrocracking catalyst is FC-70B, the cut-off temperature of the light aromatics feedstock and tail oil is 185℃, and the reaction pressure is 10.0MPa. The volumetric space velocity (VHSV) of the hydrorefining reactor (calculated based on the second feedstock) is 1.0h. -1 The volumetric space velocity (using the second feedstock) of the hydrocracking reactor is 1.0 h⁻¹. -1 The principle for adjusting the temperature of the hydrorefining reactor is that the nitrogen content of the refined oil is 6 ppm. The principle for adjusting the temperature of the hydrocracking reactor is that the single-pass conversion rate is 55%. The solvent used in the aromatics extraction unit is sulfolane, the solvent-to-oil ratio is 20, and the processing temperature is 100℃. The reaction results are shown in Table 2.

[0076] Example 3

[0077] use Figure 1 The process flow shown is illustrated in Table 1, and the properties of the first and second raw materials are listed below. The distribution ratio of the two tail oil streams is dynamically adjusted during the initial operation of the unit. The proportion of the first tail oil stream circulating to the hydrorefining reactor relative to the total tail oil is determined according to Y... h =(0.0601h) 2 The temperature is controlled by adjusting the value of (-4.3955h+88.148) / 100, with a control cycle of 28 days. The cutting temperature of the primary fractionation tower is dynamically adjusted during the initial startup phase, according to T... h =8.2*Ln(h+0.2)+175, with a control cycle of 20 days. The hydrogen-to-oil volume ratio of the unit is dynamically adjusted during the initial startup phase, V h =-1.168h 2+46.532h +760.86, control cycle is 30 days. The catalyst loading volume at the top of the second feed inlet of the hydrorefining reactor accounts for 25% of the total catalyst loading volume of the hydrorefining reactor, and the feed mass ratio of the first feedstock and the second feedstock is 0.15. FF-34 catalyst is loaded at the top of the second feed inlet of the hydrorefining reactor, and FF-66 catalyst is loaded at the bottom of the second feed inlet. The hydrocracking catalyst is FC-90, the cut-off temperature of the light aromatics feedstock and tail oil is 180℃, and the reaction pressure is 12.0MPa. The volumetric space velocity (VHSV) of the hydrorefining reactor (calculated with the second feedstock) is 1.5h. -1 The volumetric space velocity (using the second feedstock) of the hydrocracking reactor is 1.8 h⁻¹. -1 The principle for adjusting the temperature of the hydrorefining reactor is that the nitrogen content of the refined oil is 9 ppm. The principle for adjusting the temperature of the hydrocracking reactor is that the single-pass conversion rate is 55%. The solvent used in the aromatics extraction unit is sulfolane, the solvent-to-oil ratio is 12, and the processing temperature is 95℃. The reaction results are shown in Table 2.

[0078] Example 4

[0079] use Figure 1 The process flow shown is illustrated in Table 1, and the properties of the first and second feedstocks are listed below. The proportion of the first tail oil recycled to the hydrorefining reactor to the total tail oil is Y. h =0.12. The cutting temperature of the primary fractionation tower is dynamically adjusted during the initial startup phase, according to T. h =8.2*Ln(h+0.2)+175, with a control cycle of 20 days. The hydrogen-to-oil volume ratio of the unit is 1150:1. The volume of catalyst that can be packed in the upper part of the second feed inlet of the hydrorefining reactor accounts for 34% of the total catalyst packing volume of the hydrorefining reactor, and the feed mass ratio of the first feedstock and the second feedstock is 0.20. The weight ratio of the active metal component of the FF-66 catalyst packed in the upper part of the second feed inlet of the hydrorefining reactor to that packed in the lower part of the second feed inlet of the hydrorefining reactor is 0.88. The hydrocracking catalyst is FC-70A, the cut-off temperature of the light aromatic feedstock and tail oil is 199℃, and the reaction pressure is 7.0MPa. The volume hourly space velocity (calculated with the second feedstock) of the hydrorefining reactor is 2.0h. -1 The volumetric space velocity (using the second feedstock) of the hydrocracking reactor is 1.5 h⁻¹. -1 The principle for adjusting the temperature of the hydrorefining reactor is that the nitrogen content of the refined oil is 10 ppm. The principle for adjusting the temperature of the hydrocracking reactor is that the single-pass conversion rate is 50%. The solvent used in the aromatics extraction unit is sulfolane, the solvent-to-oil ratio is 15, and the processing temperature is 90℃. The reaction results are shown in Table 2.

[0080] Comparative Example 1

[0081] Compare the process flow in Example 1 with Figure 1 The process is basically the same as the previous one, except that the first feedstock does not enter the primary fractionation tower for separation, but instead enters the hydrorefining reactor directly through the second feed inlet. All tail oil is recycled back to the hydrorefining reactor. The properties of the first and second feedstocks are shown in Table 1. The volume of catalyst that can be loaded at the top of the second feed inlet of the hydrorefining reactor accounts for 34% of the total catalyst loading volume of the hydrorefining reactor, and the feed mass ratio of the first and second feedstocks is 0.1. The weight ratio of the active metal components of the FF-66 catalyst loaded at the top of the second feed inlet to that loaded at the bottom of the second feed inlet of the hydrorefining reactor is 0.88. The hydrocracking catalyst is FC-70. The hydrogen-to-oil volume ratio is 1190:1, and the reaction pressure is 7.0 MPa. The volume hourly space velocity (VHSV) of the hydrorefining reactor (calculated based on the second feedstock) is 2.0 h⁻¹. -1 The volumetric space velocity (using the second feedstock) of the hydrocracking reactor is 1.5 h⁻¹. -1 The principle for adjusting the temperature of the hydrorefining reactor is that the nitrogen content of the refined oil is 10 ppm. The principle for adjusting the temperature of the hydrocracking reactor is that the single-pass conversion rate is 50%. The solvent used in the aromatics extraction unit is sulfolane, the solvent-to-oil ratio is 15, and the processing temperature is 90℃. The reaction results are shown in Table 3.

[0082] Comparative Example 2

[0083] use Figure 1 The process flow shown only processes the second raw material, the properties of which are shown in Table 1. The distribution ratio of the two tail oil streams is dynamically adjusted during the initial operation of the unit. The proportion of the first tail oil stream circulating to the hydrorefining reactor to the total tail oil is determined according to Y. h =(0.0601h) 2 The temperature is adjusted using (-4.3955h+88.148) / 100, with a control cycle of 30. The cutting temperature of the primary fractionation tower is dynamically adjusted during the initial startup phase, according to T... h =8.2*Ln(h+0.2)+175, with a control cycle of 18 days. The hydrogen-to-oil volume ratio of the unit is dynamically adjusted during the initial startup phase, V h =-1.168h 2+46.532h +760.86, control cycle is 25 days. The volume of catalyst that can be loaded at the top of the second feed inlet of the hydrorefining reactor accounts for 34% of the total catalyst loading volume of the hydrorefining reactor. The weight ratio of the hydrorefining active metal component of the FF-66 catalyst loaded at the top of the second feed inlet of the hydrorefining reactor to that loaded at the bottom of the second feed inlet of the hydrorefining reactor is 0.88. The hydrocracking catalyst is FC-70A, the cut-off temperature of the light aromatic feedstock and tail oil is 190℃, and the reaction pressure is 7.0MPa. The volumetric space velocity (calculated with the second feedstock) of the hydrorefining reactor is 2.0h. -1 The volumetric space velocity (using the second feedstock) of the hydrocracking reactor is 1.5 h⁻¹. -1 The principle for adjusting the temperature of the hydrorefining reactor is that the nitrogen content of the refined oil is 10 ppm. The principle for adjusting the temperature of the hydrocracking reactor is that the single-pass conversion rate is 50%. The solvent used in the aromatics extraction unit is sulfolane, the solvent-to-oil ratio is 15, and the processing temperature is 90℃. The reaction results are shown in Table 3.

[0084] Comparative Example 3

[0085] use Figure 1 The process flow shown is illustrated in Table 1, and the properties of the first and second feedstocks are listed below. The proportion of the first tail oil recycled to the hydrorefining reactor to the total tail oil is Y. h The cut-off temperature of the primary fractionation column is 199℃. The hydrogen-to-oil volume ratio of the unit is 1190:1. The volume of catalyst that can be packed in the upper part of the second feed inlet of the hydrorefining reactor accounts for 34% of the total catalyst packing volume of the hydrorefining reactor, and the feed mass ratio of the first feedstock to the second feedstock is 0.20. The mass ratio of the metal active component of the catalyst packed in the upper part of the second feed inlet of the hydrorefining reactor to that packed in the lower part of the second feed inlet of the hydrorefining reactor is 0.88. The hydrocracking catalyst is FC-70A, the cut-off point of the light aromatics feedstock and tail oil is 190℃, and the reaction pressure is 7.0 MPa. The volume hourly space velocity (VHSV) of the hydrorefining reactor (calculated with the second feedstock) is 2.0 h⁻¹. -1 The volumetric space velocity (using the second feedstock) of the hydrocracking reactor is 1.5 h⁻¹. -1 The principle for adjusting the temperature of the hydrorefining reactor is that the nitrogen content of the refined oil is 10 ppm. The principle for adjusting the temperature of the hydrocracking reactor is that the single-pass conversion rate is 50%. The solvent used in the aromatics extraction unit is sulfolane, the solvent-to-oil ratio is 15, and the processing temperature is 90℃. The reaction results are shown in Table 3.

[0086] Table 2 Reaction results of Examples 1-4

[0087]

[0088]

[0089] Table 3. Reaction results of Comparative Examples 1-3

[0090]

[0091]

[0092] Comparative results from the examples and comparative cases show that the production process provided by this invention achieves a high and stable BTX yield (minimum 41.5%) in the initial stage of production, while conventional processes require 3 to 6 times the time for adjustment before the liquid product BTX yield reaches a maximum of about 36.6%. Simultaneously, the yield of light aromatics is significantly higher than that of conventional processing methods, and the required temperature for the hydrorefining stage is greatly reduced. This provides enterprises with a safe, reliable, and economically efficient high-value-added technology solution for utilizing raw materials rich in bicyclic and monocyclic aromatics.

Claims

1. A process for producing light aromatic hydrocarbon feedstock by hydrogenation, comprising the following steps: (1) obtaining light feedstock and heavy feedstock by fractionating a first feedstock; the first feedstock is a hydrocarbon-containing compound rich in monocyclic aromatic hydrocarbons, wherein the content of monocyclic aromatic hydrocarbons is 40 wt%-75 wt%; (2) in the presence of hydrogen, feeding the second feedstock and the heavy feedstock obtained in step (1) into a hydrofining reaction zone to obtain a hydrofining reaction product; the second feedstock is a hydrocarbon-containing compound rich in aromatic hydrocarbons, wherein the total content of aromatic hydrocarbons is 60 wt%-90 wt%; (3) in the presence of hydrogen, feeding the hydrofining reaction product obtained in step (2) and the light feedstock obtained in step (1) into a hydrocracking reaction zone to obtain a hydrocracking reaction product; (4) separating the hydrocracking reaction product obtained in step (3) to obtain gas, light aromatic hydrocarbon feedstock and tail oil; wherein the tail oil is divided into two streams, the first stream of tail oil is recycled back to the hydrofining reaction zone for treatment, and the second stream of tail oil is recycled together with the first feedstock for fractionation treatment.

2. The hydrogendifferentiation process to light aromatic feedstock according to claim 1, wherein, The content of monocyclic aromatic hydrocarbons in the first feedstock in step (1) is 50 wt%-65 wt%, the initial boiling point of the first feedstock is 50-200℃, preferably 65-165℃, and the final boiling point is 200-370℃, preferably 220-325℃.

3. The hydrogendiffusing process to light aromatic feedstock according to claim 1 or 2, wherein, The first feedstock is at least one of reforming heavy aromatic hydrocarbons, pyrolysis gasoline heavy aromatic hydrocarbons, C9 heavy aromatic hydrocarbons and adsorption device aromatic hydrocarbon-rich components, preferably reforming heavy aromatic hydrocarbons.

4. The hydrogendifferentiation process to light aromatic feedstock according to claim 1, wherein, The cutting temperature of the light feedstock and the heavy feedstock in step (1) is 162-200℃, preferably 165-199℃.

5. The hydrogendifferentiation process to a light aromatic feedstock according to claim 1 or 4 wherein, Taking the moment when the device is switched into the raw material from the start-up oil as the starting point, taking the time length (h) as the input parameter, and according to the preset function of the cutting temperature T h of the light raw material and the heavy raw material, the device is dynamically adjusted, and the preset function comprises: T h =8.2*Ln(h+0.2)+175; The length (h) is the length of time from the current time to the time when the feedstock is switched in, and the length is rounded to an integer value in days; the maximum value of the length (h) is not greater than 25, preferably 10-25, further preferably 12-20, and h reaches the maximum value to stop adjusting the cutting temperature of the light feedstock and the heavy feedstock.

6. The hydrogendifferentiation light aromatics feedstock process of claim 1 wherein, Taking the time when the device is switched from start-up oil to feedstock as the starting point and the length (h) as the input parameter, the hydrogen to oil volume ratio of the hydrofining reaction zone is dynamically adjusted according to a preset function, and the preset function comprises: V h = -1.168h 2 + 46.532h + 760.86; The length (h) is the length of time from the current time to the time when the feedstock is switched in, and the length is rounded to an integer value in days; the maximum value of the length (h) is not greater than 32, preferably 20-32, further preferably 25-30; h reaches the maximum value to stop adjusting the hydrogen to oil volume ratio.

7. The hydrogendifferentiation light aromatics feedstock process of claim 1 wherein, The total content of aromatic hydrocarbons in the second feedstock is 70 wt%-90 wt%; wherein the content of bicyclic aromatic hydrocarbons is 35 wt%-55 wt%, preferably 40 wt%-50 wt%; the content of aromatic hydrocarbons with three or more rings is 2 wt%-12 wt%, preferably 3 wt%-8 wt%; the initial boiling point of the second feedstock is 160-230℃, and the final boiling point is 300-360℃.

8. The hydrogendifferentiation process to a light aromatic feedstock of claim 1 or 7 wherein, The second feedstock is at least one of catalytically cracked diesel, heavy oil high-efficiency catalytic cracking diesel, isomerate-rich catalytic cracking diesel and catalytic cracking diesel, preferably catalytically cracked diesel.

9. The hydrogendifferentiation process to light aromatic feedstock according to claim 1, wherein, The second raw material in step (2) and the heavy raw material obtained in step (1) are introduced into the hydrofining reaction zone through different feed ports for treatment, wherein the first feed port is arranged at the top or bottom of the reactor, and the second raw material is introduced through the first feed port; the second feed port is arranged on the shell of the reactor, and the heavy raw material obtained in step (1) is introduced through the second feed port; wherein the catalyst loading volume between the first feed port and the second feed port is 10% to 60% of the total catalyst loading volume of the reactor, preferably 12% to 34%.

10. The hydrogendifferentiation process to light aromatic feedstock according to claim 1 wherein, The mass ratio of the first raw material to the second raw material is 0.05 to 0.30, and further preferably 0.09 to 0.

20.

11. The hydrogendifluoride production light aromatics feedstock process of claim 9 wherein, The hydrofining catalyst between the first feed port and the second feed port in step (2) is named hydrofining catalyst A, and the hydrofining catalyst between the second feed port and the reactor outlet is named hydrofining catalyst B, wherein the weight ratio of the hydrogenation active metal components of the hydrofining catalyst A to the hydrofining catalyst B is 0.75 to 1.0, and preferably 0.88 to 0.

98.

12. The hydrogendifferentiation process to light aromatic feedstock of claim 1 wherein, The cutting point of the light aromatic hydrocarbon raw material and the tail oil is 170 to 220°C, and preferably 180 to 195°C.

13. The hydrogendifferentiation process to light aromatic feedstock of claim 1 wherein, The operating conditions of the hydrofining reaction zone are as follows: the reaction temperature is 320-420°C, preferably 360-390°C; the reaction pressure is 5.0-16.0 MPa, preferably 6.0-12.0 MPa; the volume space velocity is 0.1-5.0 h -1 , preferably 1.0-2.0 h -1 .

14. The hydrogendifferentiation process to light aromatic feedstock of claim 1 wherein, The operating conditions of the hydrocracking reaction zone are as follows: the reaction temperature is 340-420°C, preferably 350-405°C; the reaction pressure is 5.0-16.0 MPa, preferably 6.0-12.0 MPa; the volume space velocity is 0.5-5.0 h -1 , preferably 0.8-2.5 h -1 .

15. The hydrogendifferentiation process to light aromatic feedstock of claim 1 wherein, The distribution ratio of the two tail oils in step (4) is dynamically adjusted at the initial stage of the operation of the device, and the time length (h) is taken as the input parameter. According to the preset function, the proportion Y of the first tail oil in the total tail oil circulating back to the hydrofining reaction zone is calculated from the moment when the device is switched from the start-up oil to the raw material as the starting point. h is dynamically adjusted, and the preset function includes: Y h = (0.0601 h 2 - 4.3955 h + 88.148) / 100; The length (h) is the length of time from the current time to the time when the raw material is switched in, and the length is rounded to an integer value in days; the maximum value of the length (h) is not greater than 32; preferably 20 to 32, and further preferably 25 to 30; the cutting temperature of the light raw material and the heavy raw material is stopped adjusting when h reaches the maximum value.

16. A BTX production process by hydrogenation, the process steps are as follows: S1: producing a light aromatic hydrocarbon raw material; the process for producing a light aromatic hydrocarbon raw material adopts the process for producing a light aromatic hydrocarbon raw material by hydrogenation according to any one of claims 1 to 16; S2: producing BTX using the light aromatic hydrocarbon raw material obtained in step S1 as raw material.

17. The hydroprocessing to BTX process of claim 16, wherein, The production of BTX in step S2 adopts an aromatic extraction process.

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