A catalytic diesel treatment process and treatment system

Abstract

The present invention discloses a catalytic diesel processing process and a processing system, wherein the processing process includes the following contents: (1) catalytic diesel is separated to obtain a first fraction, a second fraction and a third fraction; (2) the third fraction enters a first fixed bed hydrogenation reaction zone, and a first stream is obtained after reaction; (3) the second fraction and the first stream enter an ebullating bed hydrogenation reaction zone, and a second stream is obtained after reaction; (4) the first fraction and the second stream enter a second fixed bed hydrogenation reaction zone, and the reaction products are separated to obtain light naphtha, heavy naphtha and hydrogenated diesel. A processing system for realizing the above process is also provided. The process solves the problems of high hydrogen consumption, difficult control of the reaction process, low quality and yield of aromatic products in the processing of catalytic diesel, and realizes the maximum production of the target product naphtha.

Description

Technical Field

[0001] The invention belongs to the technical field of petrochemical industry, and in particular relates to a process and system for catalyzing efficient conversion of diesel. Background Art

[0002] At present, the total annual processing capacity of catalytic cracking units in my country has exceeded 170 million tons, and the annual output of catalytic diesel has reached 35 million tons. In recent years, on the one hand, as the quality of crude oil deteriorates, the raw materials processed by catalytic cracking have become increasingly heavy and inferior, resulting in increased operating severity of catalytic cracking units and reduced quality of catalytic diesel; on the other hand, in order to reduce the olefin content of gasoline and produce more propylene, many catalytic cracking units use MIP, MIP-CGP or FDFCC technology, but these technologies can produce more propylene and effectively reduce gasoline olefins, while further deteriorating the quality of catalytic diesel. Although the properties of catalytic diesel from different companies are different, they all have common characteristics, namely high density, low cetane number and high aromatic content. Catalytic diesel has become the main bottleneck restricting the current refining companies to achieve diesel quality upgrades with high efficiency and low consumption.

[0003] According to different production purposes, the catalytic diesel hydrogenation technology with low-quality high aromatics can be divided into hydrofining technology, hydromodification technology, hydrocracking technology and hydroconversion technology. For example, UOP's MQD (Maximum quality distillate) combined refining technology, MAK-LCO hydromodification process, HyCycle Unicracking process and Sinopec FRIPP's FD2G technology, different processing technologies are to convert low-quality diesel into clean diesel oil or gasoline, chemical products.

[0004] At present, the main problem of catalytic diesel conversion technology is that the cycloalkane content in the product is too high, resulting in product indicators that do not meet the requirements, high hydrogen consumption, and poor economy. Therefore, finding an efficient, low-consumption and economical processing route for catalytic diesel quality upgrade is a technical problem that needs to be solved urgently, which can greatly promote the efficiency of enterprises.

[0005] CN107286987A discloses a combined process for treating inferior diesel. The inferior diesel raw material is mixed with hydrogen and then enters a fixed bed hydrogenation reaction zone, where a hydrogenation reaction is carried out under the action of a hydrorefining catalyst; the resulting reaction oil is mixed with hydrogen and then enters an ebullated bed hydrocracking reaction zone, where a hydrocracking reaction is carried out in the presence of an ebullated bed hydroconversion catalyst, and the product is obtained after separation. In this combined process, the entire fraction of inferior diesel is directly processed in a fixed bed, which is prone to generate hot spots, the reaction process is difficult to control, the product quality is poor, the yield is low, and the device operation cycle is short, the hydrogen consumption is relatively large, and the economy is poor. Summary of the invention

[0006] In order to solve the problems existing in the prior art, the main purpose of the present invention is to provide a catalytic diesel processing process and a processing system. The processing process is based on the conversion law of aromatics with different structures in catalytic diesel, and utilizes a combined process of distillation units, fixed bed hydrogenation and boiling bed hydrogenation to match appropriate reactor types, catalyst types and process conditions for suitable reaction paths of aromatics with different structures, so as to solve the problems of high hydrogen consumption, difficult control of the reaction process, low quality and yield of aromatic products in the processing of catalytic diesel, and achieve maximum production of the target product naphtha.

[0007] The first aspect of the present invention provides a catalytic diesel treatment process, the treatment process comprising the following contents:

[0008] (1) After catalytic diesel separation, a first fraction, a second fraction and a third fraction are obtained respectively;

[0009] (2) The third fraction obtained in step (1) enters the first fixed bed hydrogenation reaction zone and undergoes a hydrogenation reaction in the presence of hydrogen to obtain a first feed stream;

[0010] (3) the second fraction obtained in step (1) and the first stream obtained in step (2) enter into an ebullated bed hydrogenation reaction zone for reaction to obtain a second stream;

[0011] (4) The first fraction obtained in step (1) and the second stream obtained in step (3) enter a second fixed bed hydrogenation reaction zone, and the reaction products are separated to obtain a gas phase third stream and a liquid phase fourth stream;

[0012] (5) The fourth liquid stream obtained in step (4) is split to obtain light naphtha, heavy naphtha and hydrogenated diesel.

[0013] Furthermore, in the above-mentioned catalytic diesel treatment process, the hydrogenated diesel obtained in step (5) can be partially or completely recycled back to the ebullated bed hydrogenation reaction zone for treatment.

[0014] Furthermore, in the above-mentioned catalytic diesel treatment process, the gas phase third stream obtained in step (4) is introduced into a hydrogen recovery unit, and after light hydrocarbon recovery, hydrogen sulfide removal and membrane separation, purified and concentrated circulating hydrogen is obtained. The circulating hydrogen can be introduced into the ebullating bed hydrogenation reaction zone for use.

[0015] Furthermore, in the above catalytic diesel treatment process, the aromatic content in the catalytic diesel in step (1) is higher than 50wt%, preferably 55wt% to 90wt%. The catalytic diesel generally refers to the diesel fraction produced from a catalytic cracking unit.

[0016] Furthermore, in the above catalytic diesel treatment process, the cutting temperature of the first fraction and the second fraction in step (1) is 170-240°C, preferably 200-230°C; the cutting temperature of the second fraction and the third fraction is 280-340°C, preferably 290-330°C. The first fraction is rich in monocyclic aromatic hydrocarbons, wherein the content of monocyclic aromatic hydrocarbons is 35wt%-60wt%; the second fraction is rich in dicyclic aromatic hydrocarbons, wherein the content of dicyclic aromatic hydrocarbons is 50wt%-80wt%; the third fraction is rich in tricyclic aromatic hydrocarbons, wherein the content of tricyclic aromatic hydrocarbons is 45wt%-70wt%.

[0017] Furthermore, in the above-mentioned catalytic diesel treatment process, the reaction conditions of the first fixed bed hydrogenation reaction zone are as follows: reaction pressure is 5.0-20.0 MPa, preferably 6.0-10.0 MPa; reaction temperature is 300-420°C, preferably 320-390°C, hydrogen-to-oil volume ratio is 500-2000, preferably 600-1500, liquid hourly volume space velocity is 0.1-5.0 h -1 , preferably 0.5~2.0h -1 .

[0018] Further, in the above-mentioned catalytic diesel treatment process, the first fixed bed hydrogenation reaction zone can be provided with more than one hydrogenation reactor, preferably 1 or 2 hydrogenation reactors; multiple catalyst beds are provided in the hydrogenation reactor, preferably two catalyst beds are provided, and specifically, according to the flow direction of the liquid phase material, the two catalyst beds are respectively filled with a hydrorefining catalyst and a hydrocracking catalyst. Further, the hydrorefining catalyst can use a commercial product, or it can be prepared according to conventional knowledge in the field. The hydrorefining catalyst uses alumina or silicon-containing alumina as a carrier, and the active components are selected from the VIB group of Mo and / or W and / or the VIII group metal of Co and / or Ni. Based on the weight of the catalyst, the content of the VIB group metal and the content of the VIII group metal are 7wt% to 30wt% and 3wt% to 18wt% respectively in terms of oxide. Specifically, the FHUSD series catalysts and FF series wax oil hydrogenation catalysts (such as FF-24, FF-33, FF-34, FF-36, FFT-1B, etc.) developed by Sinopec Dalian Petrochemical Research Institute can be selected.

[0019] Further, in the above-mentioned catalytic diesel treatment process, more than one ebullated bed reactor can be set in the ebullated bed hydrogenation reaction zone, and the ebullated bed reactor preferably adopts an ebullated bed reactor with a three-phase separator arranged inside the reactor, and specifically, an ebullated bed reactor with a three-phase separator developed by Fushun Petrochemical Research Institute of Sinopec Corporation can be used. The reactor is filled with an ebullated bed hydrogenation catalyst, and the ebullated bed hydrogenation catalyst can be selected from the existing diesel hydrogenation catalyst in the field, or prepared by itself according to the method disclosed in the prior art. Specifically in the present invention, the preferred ebullated bed hydrogenation catalyst uses high silicon alumina and molecular sieve as carriers, and uses Group VIII metal and Group VIB metal as active metal components. Based on the weight of the catalyst, the content of high silicon alumina is 30% to 70%, the content of molecular sieve is 10% to 50%, the content of Group VIII metal in terms of oxide is 1% to 9%, and the content of Group VIB metal in terms of oxide is 10% to 30%. The Group VIII metal is preferably Ni and / or Co; the Group VIB metal is preferably W and / or Mo; the molecular sieve is one or more selected from Y-type molecular sieve, β molecular sieve, ZSM-5 molecular sieve, SAPO molecular sieve, and MCM-41 mesoporous molecular sieve.

[0020] Furthermore, in the above-mentioned catalytic diesel combined treatment process, the process conditions of the ebullated bed hydrogenation reaction zone are: reaction temperature is 350-450°C, preferably 380-440°C, reaction pressure is 5.0-15.0MPa, preferably 6.0-10.0MPa, hydrogen-to-oil volume ratio is 500-2000, preferably 600-1500, liquid hourly volume space velocity is 0.1-5.0h -1 , preferably 0.2~2.0h -1 .

[0021] Furthermore, in the above-mentioned catalytic diesel combined treatment process, the second fixed-bed hydrogenation reaction zone can be provided with more than one fixed-bed hydrogenation reactor, preferably 1 or 2 fixed-bed hydrogenation reactors; one or more catalyst beds can be provided in the fixed-bed hydrogenation reactor. Further, in the above-mentioned technical scheme, the hydrorefining catalyst can use commercially available products, or it can be prepared according to conventional knowledge in the field. The hydrorefining catalyst uses alumina or silicon-containing alumina as a carrier, and the active components are selected from the VIB group metals of Mo and / or W and / or the VIII group metals of Co and / or Ni. The catalyst can use existing commercially available gasoline or naphtha hydrorefining technology catalysts, such as DCC cracking gasoline hydrorefining catalysts, ethylene cracking C9+ fraction hydrorefining catalysts or reforming pre-hydrogenation catalysts, such as the FH-40 series catalysts developed by Sinopec Dalian Petrochemical Research Institute.

[0022] Furthermore, in the above catalytic diesel combined treatment process, the process conditions of the second fixed bed hydrogenation reaction zone are: reaction temperature of 280-400°C, preferably 300-350°C, reaction pressure of 3.0-10.0MPa, preferably 4.0-6.0MPa, hydrogen-to-oil volume ratio of 500-2000, preferably 600-1500, liquid hourly volume space velocity of 0.1-5.0h -1 , preferably 0.2~2.0h -1 .

[0023] Furthermore, in the above-mentioned catalytic diesel combined treatment process, light naphtha and heavy naphtha can be directly discharged from the device as products, and their main components include monocyclic aromatic hydrocarbon components with carbon numbers of C5 to C9, specifically including light aromatic hydrocarbons such as benzene, toluene, xylene, methyl ethylbenzene, and mesitylene.

[0024] Furthermore, in the above-mentioned catalytic diesel combined treatment process, the separation unit includes a gas-liquid separator and an optional distillation tower; the gas-liquid separator may include a high-pressure separator and a low-pressure separator, and the distillation tower may adopt an existing distillation tower in the art, specifically a plate tower or a packed tower.

[0025] A second aspect of the present invention provides a catalytic diesel processing system, the processing system comprising

[0026] A first fractionation zone, which is used to receive and separate the catalytic diesel to obtain a first fraction, a second fraction and a third fraction after separation;

[0027] A first fixed bed hydrogenation reaction zone, which is used to receive hydrogen and the third fraction from the first fractionation zone, and obtain a first stream after reaction;

[0028] an ebullated bed hydrogenation reaction zone, which is used to receive hydrogen, the second fraction from the first fractionation zone, and the first stream from the first fixed bed hydrogenation reaction zone, and obtain a second stream after reaction;

[0029] A second fixed bed hydrogenation reaction zone is used to receive hydrogen, the first fraction from the first fractionation zone, and the second stream from the ebullated bed hydrogenation reaction zone, and obtain a reaction product after reaction;

[0030] A gas-liquid separation zone, which is used to receive the reaction product from the second fixed bed hydrogenation reaction zone, and obtain a gas phase third material flow and a liquid phase fourth material flow after separation;

[0031] The second fractionation zone is used to receive the fourth liquid stream from the gas-liquid separation zone, and obtain light naphtha, heavy naphtha and hydrogenated diesel after fractionation.

[0032] Furthermore, in the above catalytic diesel processing system, the first fractionation zone is provided with one or more devices with fractionation function, specifically a fractionation tower can be used, and the fractionation tower can be any one of the existing fractionation towers in the art, specifically a plate tower or a packed tower.

[0033] Furthermore, in the above catalytic diesel processing system, the first fixed bed hydrogenation reaction zone is provided with more than one fixed bed hydrogenation reactor, preferably 1 or 2 reactors.

[0034] Furthermore, in the above-mentioned catalytic diesel processing system, more than one fluidized bed reactor can be set in the fluidized bed hydrogenation reaction zone. The fluidized bed reactor preferably adopts a fluidized bed reactor with a three-phase separator arranged inside the reactor. Specifically, the fluidized bed reactor with a three-phase separator developed by Fushun Petrochemical Research Institute of China Petroleum and Chemical Corporation can be adopted.

[0035] Furthermore, in the above catalytic diesel processing system, the second fixed bed hydrogenation reaction zone may be provided with more than one fixed bed hydrogenation reactor, preferably 1 or 2 fixed bed hydrogenation reactors; and at least one catalyst bed may be provided in the fixed bed hydrogenation reactor.

[0036] Furthermore, in the above-mentioned catalytic diesel processing system, the system also includes a hydrogen recovery unit, including light hydrocarbon recovery equipment, a hydrogen sulfide removal tower and a membrane separation equipment, which is used to receive the gas phase third material flow from the gas-liquid separation zone, and obtain light hydrocarbons and circulating hydrogen after treatment. Furthermore, the circulating hydrogen can be introduced into the boiling bed hydrogenation reaction zone through a pipeline for use.

[0037] Furthermore, in the above catalytic diesel processing system, the hydrogenated diesel is introduced into the ebullating bed hydrogenation reaction zone for processing through a pipeline.

[0038] Compared with the prior art, the catalytic diesel treatment process and treatment system of the present invention have the following advantages:

[0039] (1) Compared with the existing direct processing technology of catalytic diesel, the present invention is based on the different processing technologies and specific reaction conditions suitable for different hydrocarbon molecules. According to the impurity content and aromatic distribution of catalytic diesel, it is divided into components to obtain fractions with different aromatic structures and impurity contents. The first fraction is rich in monocyclic aromatics, the second fraction is rich in dicyclic aromatics, and the third fraction is rich in polycyclic aromatics. In addition, the enrichment degree of impurities is also distinguished during the hydrocarbon separation process, achieving multiple separation effects of aromatics and impurities. The third fraction is a high nitrogen fraction, while the impurity content of the first and second fractions is relatively low. The multiple separation of aromatics and impurities is achieved through fractionation.

[0040] (2) In the catalytic diesel treatment process of the present invention, the separated heavy catalytic diesel fraction (i.e., the third fraction) is subjected to fixed-bed hydrogenation treatment. This is mainly because the heavy catalytic diesel is rich in polycyclic aromatic hydrocarbons and nitrogen impurities. If it is mixed with light catalytic diesel (i.e., the first fraction or the second fraction) and directly hydrogenated and refined, due to the difference in the reaction paths of polycyclic aromatic hydrocarbons and dicyclic aromatic hydrocarbons, dicyclic aromatic hydrocarbons will be more easily hydrogenated and saturated to become cycloalkanes during the hydrogenation of polycyclic aromatic hydrocarbons, thereby resulting in the loss of aromatic hydrocarbon content in the ebullating bed cracking unit. Therefore, a fixed-bed unit is used to treat the heavy catalytic diesel alone.

[0041] (3) In the catalytic diesel treatment process of the present invention, the reaction heat generated in the reaction process is fully utilized. The third fraction will generate a large amount of reaction heat in the fixed bed hydrogenation process. After being mixed with the second fraction with a relatively low temperature, it can reach the feed temperature of the ebullating bed hydrogenation reaction, thereby reducing the load of the heating furnace and having the advantages of energy saving and consumption reduction.

[0042] (4) In the treatment process of the present invention, the ebullated bed hydrogenation can directly process the light catalytic diesel (second fraction) after pre-fractionation. This is mainly because the desorption performance of nitrogen on the catalyst is enhanced at a higher reaction temperature under the ebullated bed system, and the nitrogen content index of the raw material can be relaxed. At the same time, the content of polycyclic aromatic hydrocarbons that are easy to coke in the pre-treated catalytic diesel is very low, which can greatly alleviate the problem of catalyst coking. At the same time, the ebullated bed hydrogenation adopts online catalyst replacement, which can achieve long-term operation.

[0043] (5) Low-pressure operation mode of the fixed-bed supplementary refining unit for the ebullated-bed hydrogenation product oil. Compared with the high-pressure mode of the pre-hydrogenation refining unit in the fixed-bed process, in this project, since the sulfur and nitrogen content in the light aromatics after the ebullated-bed hydrogenation conversion is low, a relatively mild operating condition can be used to achieve a good impurity removal effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 The figure is a schematic diagram of the catalytic diesel treatment process of the present invention.

[0045] Among them, 1-catalytic diesel, 2-first fractionation zone, 3-first fraction, 4-second fraction, 5-third fraction, 6-first fixed bed hydrogenation reaction zone, 7-first stream, 8-ebullated bed hydrogenation reaction zone, 9-second stream, 10-second fixed bed hydrogenation reaction zone, 11-gas-liquid separation zone, 12-gas phase third stream, 13-hydrogen recovery unit, 14-circulating hydrogen, 15-light hydrocarbons, 16-liquid phase fourth stream, 17-second fractionation zone, 18-light naphtha, 19-heavy naphtha, 20-hydrogenated diesel.

[0046] Figure 2 This is a schematic diagram of the process flow adopted in Comparative Example 1 of the present invention.

[0047] Figure 3This is a schematic diagram of the process flow adopted in Comparative Example 2 of the present invention. DETAILED DESCRIPTION

[0048] The technical scheme and technical effects of the present invention are further described below in conjunction with the accompanying drawings and specific implementation methods.

[0049] Unless explicitly stated otherwise, throughout the specification and claims, the term “comprise” or variations such as “include” or “comprising”, etc., will be understood to include the stated elements or components but not to exclude other elements or components.

[0050] In this document, for the convenience of description, spatial relative terms such as "below", "below", "down", "above", "above", "upper", etc. may be used to describe the relationship between one element or feature and another element or feature in the accompanying drawings. It should be understood that the spatial relative terms are intended to include different directions of objects in use or operation in addition to the directions drawn in the drawings. For example, if the object in the figure is turned over, the elements described as being "below" or "below" other elements or features will be oriented "above" the elements or features. Therefore, the exemplary term "below" can include both below and above directions. Objects may also have other orientations (rotated 90 degrees or other orientations) and the spatial relative terms used in this document should be interpreted accordingly.

[0051] In this document, the terms "first", "second", etc. are used to distinguish two different elements or parts, and are not used to limit a specific position or relative relationship. In other words, in some embodiments, the terms "first", "second", etc. can also be interchangeable.

[0052]

[0043] All numerical values ​​for parameters (eg, amounts or conditions) herein are to be understood as being modified in all instances by the term "about", whether or not "about" actually appears before the numerical value.

[0053] like Figure 1As shown, the catalytic diesel hydroprocessing process of the present invention is as follows: the catalytic diesel 1 enters the first fractionation zone 2, and is separated to obtain a first fraction 3 enriched in monocyclic aromatic hydrocarbons, a second fraction 4 enriched in bicyclic aromatic hydrocarbons, and a third fraction 5 enriched in polycyclic aromatic hydrocarbons; the third fraction 5 enters the first fixed bed hydrogenation reaction zone 6, and is subjected to impurity removal and aromatic hydrocarbon saturation reaction in the presence of hydrogen, and a first stream 7 is obtained after the reaction; the first stream 7 and the second fraction 4 enriched in bicyclic aromatic hydrocarbons are mixed and enter the ebullating bed hydrogenation reaction zone 8 for reaction, and a second stream 9 is obtained after the reaction, and the second stream 9 is obtained after the reaction. The stream 9 and the first fraction 3 enriched in monocyclic aromatic hydrocarbons are mixed and enter the second fixed bed hydrogenation reaction zone 10 for reaction. The obtained reaction product enters the gas-liquid separation zone 11. After separation, a gaseous third stream 12 and a liquid fourth stream 16 are obtained. The gaseous third stream 12 is treated by the dehydrogenation gas recovery unit 13 to obtain circulating hydrogen 14 and light hydrocarbons 15. The liquid fourth stream 16 enters the second fractionation zone for separation to obtain light naphtha 18, heavy naphtha 19 and hydrogenated diesel 20. The hydrogenated diesel 20 is returned to the boiling bed hydrogenation reaction zone 8 for further processing.

[0054] The basic properties of the catalytic diesel used in the examples and comparative examples of the present invention are shown in Table 1.

[0055] Table 1 Basic properties of catalytic diesel

[0056]

[0057] Example 1

[0058] use Figure 1 In the process flow shown in the figure, the cutting point temperature of the first fraction and the second fraction is 205°C, and the cutting point temperature of the second fraction and the third fraction is 315°C; the conditions of the first fixed bed hydrogenation reaction zone are reaction temperature 370°C, reaction pressure 8.0MPa, hydrogen-oil volume ratio 800, liquid hourly volume space velocity 1.2h -1 The hydrofining catalyst is FFT-1B, and the hydrocracking catalyst is FC-24B. The reaction conditions of the ebullient bed hydrogenation reaction zone are reaction temperature 420℃, reaction pressure 8.0MPa, hydrogen-oil volume ratio 800, liquid hourly volume space velocity 1.2h -1 The catalyst used is the spherical FC-70 hydrocracking catalyst developed by Sinopec Dalian Petrochemical Research Institute. The conditions of the second fixed bed hydrogenation reaction zone are reaction temperature 280°C, reaction pressure 4.0MPa, volume space velocity 1.5h -1 , hydrogen to oil volume ratio is 800, and the catalyst is FGH20 catalyst. The specific test results are shown in Table 2.

[0059] Example 2

[0060] use Figure 1In the process flow shown in the figure, the cutting point temperature of the first fraction and the second fraction is 210°C, and the cutting point temperature of the second fraction and the third fraction is 315°C; the conditions of the first fixed bed hydrogenation reaction zone are reaction temperature 380°C, reaction pressure 10MPa, hydrogen-oil volume ratio 800, liquid hourly volume space velocity 1.2h -1 The hydrofining catalyst is FFT-1B, and the hydrocracking catalyst is FC-24B. The reaction conditions of the ebullient bed hydrogenation reaction zone are reaction temperature 425℃, reaction pressure 10.0MPa, hydrogen-oil volume ratio 800, liquid hourly volume space velocity 0.6h -1 The catalyst used was the spherical FC-70 hydrocracking catalyst developed by Sinopec Dalian Petrochemical Research Institute. The conditions of the second fixed bed hydrogenation reaction zone were reaction temperature 300°C, reaction pressure 5.0 MPa, volume space velocity 1.8 h -1 , hydrogen to oil volume ratio is 800, and the catalyst is FGH20 catalyst. The specific test results are shown in Table 2.

[0061] Example 3

[0062] use Figure 1 In the process flow shown in the figure, the cutting point temperature of the first fraction and the second fraction is 210°C, and the cutting point temperature of the second fraction and the third fraction is 325°C; the conditions of the first fixed bed hydrogenation reaction zone are reaction temperature 3650°C, reaction pressure 9.0 MPa, hydrogen-oil volume ratio 700, liquid hourly volume space velocity 0.8 h -1 The hydrofining catalyst is FFT-1B, and the hydrocracking catalyst is FC-24B. The reaction conditions of the ebullient bed hydrogenation reaction zone are reaction temperature 415°C, reaction pressure 9.0MPa, hydrogen-oil volume ratio 800, liquid hourly volume space velocity 0.8h -1 The catalyst used is the spherical FC-70 hydrocracking catalyst developed by Sinopec Dalian Petrochemical Research Institute. The conditions of the second fixed bed hydrogenation reaction zone are reaction temperature 3000℃, reaction pressure 6.0MPa, volume space velocity 1.2h -1 , hydrogen to oil volume ratio is 800, and the catalyst is FGH20 catalyst. The specific test results are shown in Table 2.

[0063] Comparative Example 1

[0064] use Figure 2In the process flow shown, the catalytic diesel 1 and hydrogen are mixed and enter the first fixed bed reactor 2 for hydrofining reaction to remove sulfur and nitrogen impurities and saturate aromatics. The hydrogenated oil obtained after the reaction then enters the second fixed bed reactor 3, in which a hydrocracking reaction is carried out. The hydrogenated oil obtained enters the gas-liquid separator 4. The gas phase stream obtained after separation enters the hydrogen recovery unit 5 for treatment to obtain circulating hydrogen 7 and light hydrocarbon components 6. The liquid phase stream enters the fractionation system 8 for separation to obtain light naphtha 9, heavy naphtha 10 and unconverted diesel 11, wherein the unconverted diesel 11 is returned to the second fixed bed reactor for further reaction. Among them, the catalysts loaded in the first fixed bed reactor and the second fixed bed reactor are FF-36 brand hydrofining catalyst and FC-24B hydrocracking catalyst developed by Sinopec Dalian Petrochemical Research Institute, respectively. The conditions of the first fixed bed reactor are: reaction temperature of 370°C, reaction pressure of 8.0MPa, hydrogen-oil volume ratio of 700, reaction space velocity of 0.8h -1 ; Second fixed bed reactor conditions: reaction temperature 415°C, reaction pressure 8.0MPa, hydrogen to oil volume ratio 1200, reaction space velocity 0.8h -1 The specific test results are shown in Table 2.

[0065] Comparative Example 2

[0066] use Figure 3 In the process flow chart shown, the catalytic diesel 1 and hydrogen are mixed and enter the fixed bed reactor 2 for hydrofining reaction, sulfur and nitrogen impurities are removed, and aromatics are saturated. The hydrogenated oil obtained after the reaction then enters the ebullated bed reactor 3, in which the hydrocracking reaction is carried out, and the hydrogenated oil obtained enters the gas-liquid separator 4. The gas phase stream obtained after separation enters the hydrogen recovery unit 5 for treatment to obtain circulating hydrogen 7 and light hydrocarbon components 6. The liquid phase stream enters the fractionation system 8 for separation to obtain light naphtha 9, heavy naphtha 10 and unconverted diesel 11, wherein the unconverted diesel 11 is returned to the ebullated bed reactor for further reaction. Among them, the catalysts loaded in the fixed bed reactor are the FF-36 brand hydrofining catalyst developed by Sinopec Dalian Petrochemical Research Institute, and the ebullated bed reactor is loaded with the spherical FC-24B hydrocracking catalyst developed by Sinopec Dalian Petrochemical Research Institute. The fixed bed reactor conditions are: reaction temperature of 370°C, reaction pressure of 8.0MPa, hydrogen-to-oil volume ratio of 700, reaction space velocity of 0.8h -1 ; Ebullating bed reactor conditions: reaction temperature 420°C, reaction pressure 8.0MPa, hydrogen-oil volume ratio 1200, reaction space velocity 0.8h -1 The specific test results are shown in Table 2.

[0067] Table 2 Test results

[0068]

Claims

1. A catalytic diesel treatment process, the treatment process comprising the following contents: (1) After catalytic diesel separation, a first fraction, a second fraction and a third fraction are obtained respectively; the first fraction is rich in monocyclic aromatic hydrocarbons, wherein the content of monocyclic aromatic hydrocarbons is 35wt% to 60wt%; the second fraction is rich in dicyclic aromatic hydrocarbons, wherein the content of dicyclic aromatic hydrocarbons is 50wt% to 80wt%; the third fraction is rich in tricyclic aromatic hydrocarbons, wherein the content of tricyclic aromatic hydrocarbons is 45wt% to 70wt%; (2) the third fraction obtained in step (1) enters the first fixed bed hydrogenation reaction zone, and undergoes a hydrogenation reaction in the presence of hydrogen to obtain a first stream; the first fixed bed hydrogenation reaction zone is provided with two catalyst beds, and the two catalyst beds are sequentially loaded with a hydrorefining catalyst and a hydrocracking catalyst, respectively, according to the flow direction of the liquid phase material; (3) the second fraction obtained in step (1) and the first stream obtained in step (2) enter into an ebullated bed hydrogenation reaction zone for reaction to obtain a second stream; (4) The first fraction obtained in step (1) and the second stream obtained in step (3) enter a second fixed bed hydrogenation reaction zone, and the reaction products are separated to obtain a gas phase third stream and a liquid phase fourth stream; (5) The fourth liquid stream obtained in step (4) is separated to obtain light naphtha, heavy naphtha and hydrogenated diesel, wherein: The main components of light naphtha and heavy naphtha include monocyclic aromatic components with carbon numbers of C6 to C9; part or all of the hydrogenated diesel is recycled back to the ebullating bed hydrogenation reaction zone for treatment.

2. The catalytic diesel treatment process according to claim 1, characterized in that: The aromatic content in the catalytic diesel in step (1) is higher than 50 wt%.

3. The catalytic diesel treatment process according to claim 1, characterized in that: The aromatic content in the catalytic diesel in step (1) is 55wt% to 90wt%.

4. The catalytic diesel treatment process according to claim 1, characterized in that: In step (1), the cutting temperature of the first fraction and the second fraction is 170-240°C; the cutting temperature of the second fraction and the third fraction is 280-340°C.

5. The catalytic diesel treatment process according to claim 1, characterized in that: In step (1), the cutting temperature of the first fraction and the second fraction is 200-230°C; the cutting temperature of the second fraction and the third fraction is 290-330°C.

6. The catalytic diesel treatment process according to claim 1, characterized in that: The reaction conditions of the first fixed bed hydrogenation reaction zone are as follows: reaction pressure of 5.0-20.0 MPa, reaction temperature of 300-420°C, hydrogen-to-oil volume ratio of 500-2000, liquid hourly volume space velocity of 0.1-5.0 h -1 .

7. The catalytic diesel treatment process according to claim 1, characterized in that: The reaction conditions of the first fixed bed hydrogenation reaction zone are as follows: reaction pressure of 6.0-10.0 MPa, reaction temperature of 320-390°C, hydrogen-to-oil volume ratio of 600-1500, liquid hourly volume space velocity of 0.5-2.0 h -1 .

8. The catalytic diesel treatment process according to claim 1, characterized in that: The process conditions of the ebullient bed hydrogenation reaction zone are: reaction temperature of 350-450°C, reaction pressure of 5.0-15.0 MPa, hydrogen-oil volume ratio of 500-2000, liquid hourly volume space velocity of 0.1-5.0 h -1 .

9. The catalytic diesel treatment process according to claim 1, characterized in that: The process conditions of the ebullient bed hydrogenation reaction zone are: reaction temperature of 380-440°C, reaction pressure of 6.0-10.0 MPa, hydrogen-oil volume ratio of 600-1500, liquid hourly volume space velocity of 0.2-2.0 h -1 .

10. The catalytic diesel treatment process according to claim 1, characterized in that: The process conditions of the second fixed bed hydrogenation reaction zone are: reaction temperature of 280-400°C, reaction pressure of 3.0-10.0 MPa, hydrogen-oil volume ratio of 500-2000, liquid hourly volume space velocity of 0.1-5.0 h -1 .

11. The catalytic diesel treatment process according to claim 1, characterized in that: The process conditions of the second fixed bed hydrogenation reaction zone are: reaction temperature of 300-350°C, reaction pressure of 4.0-6.0 MPa, hydrogen-oil volume ratio of 600-1500, liquid hourly volume space velocity of 0.2-2.0 h -1 .

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