System and method for increasing yield of benzene and p-xylene

Abstract

The invention belongs to the technical field of coal chemical industry and petrochemical industry, and discloses a system and a method for increasing the yield of benzene and xylene. The system comprises a first reaction unit, a first pre-fractionation unit, a light hydrocarbon separation unit, a second pre-fractionation unit, a family composition separation unit, an aromatic hydrocarbon separation unit, a second reaction unit and a crystal separation unit. According to the method, the oxygen-containing compound is coupled with light hydrocarbon raw materials such as naphtha, so that the yield of benzene and p-xylene is increased, and the target product yield and the energy efficiency can be greatly improved.

Description

Technical Field

[0001] This invention belongs to the field of coal chemical and petrochemical technology, and more specifically, relates to a system and method for producing benzene and para-xylene. Background Technology

[0002] Aromatics and low-carbon olefins are important basic organic raw materials. Currently, the industrial production of aromatics mainly uses naphtha as raw material and is produced through technologies such as catalytic reforming and light hydrocarbon aromatization; low-carbon olefins are mainly produced through processes such as steam cracking, catalytic cracking, and methanol-to-olefins.

[0003] In recent years, methods for producing aromatics and low-carbon olefins from oxygen-containing compounds and / or naphtha have become a hot topic and focus of research in the industry. Extensive research and exploration have been conducted on aspects such as process flow and equipment structure.

[0004] CN104892346A discloses a method and apparatus for producing para-xylene from methanol. The method involves subjecting methanol to a methanol aromatization reaction. A liquefied petroleum gas feedstock, the methanol aromatization gaseous product, and the non-aromatic raffinate separated from an aromatics extraction unit are then subjected to a low-carbon light aromatization reaction in a low-carbon light aromatization reactor to maximize the production of para-xylene.

[0005] CN105693458B discloses a method and apparatus for producing o-xylene and p-xylene from coal-based mixed aromatics and direct coal liquefaction naphtha, respectively. The method involves fractionating a coal-based mixed aromatics-containing material to obtain o-xylene; subjecting the obtained benzene to alkylation; and disproportionating and transferring the obtained toluene and C9-C12 aromatics to disproportionation and alkyl transfer reactions. The products are then sent to the fractionation section; p-xylene is obtained through adsorption separation. This method utilizes coal-based mixed aromatics resources and converts benzene, with the target products being o-xylene and p-xylene.

[0006] CN107963954A, CN115869863A, and CN104557417A disclose methods for producing aromatics by coupling methanol and naphtha (or liquefied petroleum gas). The main target products of the coupled reaction of methanol and naphtha (or liquefied petroleum gas) are mixed aromatics or paraxylene. The reaction process can be controlled through catalyst development and reaction system optimization, thereby improving product selectivity; or energy utilization efficiency can be improved through process flow optimization.

[0007] Currently, the downstream processing chains for benzene and paraxylene are more diversified, and market demand has been strong in recent years. Therefore, further research is needed to improve the yield of benzene and paraxylene and expand the range of feedstocks for olefin and aromatic hydrocarbon production. Summary of the Invention

[0008] The purpose of this invention is to address the shortcomings of existing technologies by providing a system and method for producing higher yields of benzene and para-xylene. This invention utilizes the coupling of oxygen-containing compounds with light hydrocarbon feedstocks such as naphtha to produce higher yields of benzene and para-xylene, which can significantly improve the target product yield and energy efficiency.

[0009] To achieve the above objectives, the present invention provides a system for producing benzene and p-xylene, the system comprising a first reaction unit, a first pre-fractionation unit, a light hydrocarbon separation unit, a second pre-fractionation unit, a group composition separation unit, an aromatic hydrocarbon separation unit, a second reaction unit, and a crystallization separation unit;

[0010] The pyrolysis feedstock pipeline is sequentially connected to the first reaction unit and the first pre-fractionation unit; the pyrolysis feedstock pipeline is an oxygen-containing compound feedstock pipeline and / or a naphtha feedstock pipeline; the first pre-fractionation unit is equipped with a light component discharge pipeline and a heavy component discharge pipeline.

[0011] The light component discharge pipeline is connected to the light hydrocarbon separation unit;

[0012] The heavy component discharge pipeline is sequentially connected to the second pre-fractionation unit, the group composition separation unit, and the aromatic hydrocarbon separation unit; the aromatic hydrocarbon separation unit is equipped with a benzene discharge pipeline, a toluene discharge pipeline, a C8 aromatic hydrocarbon discharge pipeline, and a C9+ component discharge pipeline.

[0013] The toluene discharge pipeline is connected to the second reaction unit; the second reaction unit is provided with a second reaction product discharge pipeline, which is connected to the aromatic hydrocarbon separation unit;

[0014] The C8 aromatic hydrocarbon discharge pipeline is connected to the crystallization separation unit; the crystallization separation unit is equipped with a p-xylene collection pipeline and a mixed C8 aromatic hydrocarbon collection pipeline.

[0015] According to the present invention, preferably, the light hydrocarbon separation unit comprises a compression boosting subunit, a purification subunit, a demethanizing subunit, and an olefin separation subunit connected in sequence;

[0016] The olefin separation subunit is equipped with ethylene production pipeline, ethane production pipeline, propylene production pipeline, propane production pipeline and C4+ component discharge pipeline.

[0017] According to the present invention, preferably, the pyrolysis feedstock pipeline and the C4+ component discharge pipeline are sequentially connected to the first reaction unit and the first pre-fractionation unit.

[0018] According to the present invention, preferably, the second pre-fractionation unit is provided with a C6-C7 component discharge pipeline and a C8+ component discharge pipeline; the second pre-fractionation unit is connected to the group composition separation unit through the C6-C7 component discharge pipeline;

[0019] The group composition separation unit is equipped with a non-aromatic hydrocarbon discharge pipeline and a C6-C7 aromatic hydrocarbon discharge pipeline.

[0020] The C6-C7 aromatic hydrocarbon discharge pipeline and the C8+ component discharge pipeline are connected together to the aromatic hydrocarbon separation unit;

[0021] The pyrolysis feedstock pipeline and the non-aromatic hydrocarbon discharge pipeline are sequentially connected to the first reaction unit and the first pre-fractionation unit.

[0022] According to the present invention, preferably, the aromatic hydrocarbon separation unit is provided with a benzene tower, a toluene tower and a xylene tower.

[0023] According to the present invention, preferably, the first pre-fractionation unit is provided with a C5 component discharge pipeline, and the pyrolysis feed pipeline and the C5 component discharge pipeline are sequentially connected to the first reaction unit and the first pre-fractionation unit.

[0024] Another aspect of the present invention provides a method for producing benzene and p-xylene, the method employing the above-described system and comprising the following steps:

[0025] S1: The pyrolysis feedstock is sequentially sent to the first reaction unit and the first pre-fractionation unit for pyrolysis reaction and pre-fractionation treatment to obtain light components and heavy components;

[0026] S2: The light components are sent to the light hydrocarbon separation unit for light hydrocarbon separation;

[0027] S3: The heavy components are sequentially sent to the second pre-fractionation unit, the group composition separation unit and the aromatic hydrocarbon separation unit to obtain benzene, toluene-rich material, C8 aromatic hydrocarbons and C9+ components;

[0028] S4: The toluene-rich material is sent to the second reaction unit for disproportionation reaction to obtain the second reaction product; the second reaction product is refluxed to the aromatics separation unit for separation treatment;

[0029] S5: The C8 aromatic hydrocarbons are sent to a crystallization separation unit for crystallization separation to obtain p-xylene and mixed C8 aromatic hydrocarbons.

[0030] According to the present invention, preferably, in step S1:

[0031] The pyrolysis feedstock is an oxygen-containing compound and / or naphtha; the oxygen-containing compound is methanol and / or dimethyl ether;

[0032] The first reaction products obtained by the first reaction unit include hydrogen, C1-C4 components, C5+ saturated hydrocarbons, C6-C8 aromatics and C9+ aromatics;

[0033] The light component includes hydrogen and C1 to C5 components;

[0034] The heavy components include C6+ saturated hydrocarbons and aromatics;

[0035] Preferably, the C5 component is separated from the first pre-fractionation unit and recycled to the first reaction unit as at least a portion of the first recycled material.

[0036] According to the present invention, preferably, in step S2, in the light hydrocarbon separation unit, the light component is sequentially compressed and purified to obtain purified light component; the purified light component is sent to the demethanizing subunit for demethanizing treatment to obtain methane hydrogen and C2+ light component, the methane hydrogen is discharged externally, and the C2+ light component is subjected to olefin separation to obtain ethylene, ethane, propylene, propane and C4+ component. The demethanizing treatment adopts an oil absorption method.

[0037] According to the present invention, preferably, the C4+ component is recycled to the first reaction unit as at least a portion of the first recycled material.

[0038] According to the present invention, preferably, in step S3:

[0039] The recombinant fraction is sent to the second pre-fractionation unit to obtain C6-C7 components and C8+ components;

[0040] The C6-C7 components are sent to the group composition separation unit to obtain C6-C7 aromatics and non-aromatics;

[0041] The C6-C7 aromatics and the C8+ component are sent to the aromatics separation unit to obtain benzene, toluene-rich material, C8 aromatics and C9+ component; the non-aromatics are recycled to the first reaction unit as at least part of the first recycled material.

[0042] The group composition separation unit employs at least one of the following methods: liquid-liquid extraction, extractive distillation, and adsorption separation.

[0043] According to the present invention, preferably, in step S4, the disproportionation reaction employs at least one of alkyl transfer, toluene shape-selective disproportionation, methanol toluene disproportionation, and heavy aromatic hydrocarbon lightening methods;

[0044] The feedstock participating in the disproportionation reaction also includes at least one of hydrogen, C9 aromatics, and methanol;

[0045] The second reaction products include benzene, C8 aromatics, and C9+ aromatics.

[0046] According to the present invention, preferably, in step S5, the mass fraction of p-xylene in the C8 aromatic hydrocarbons sent to the crystallization separation unit is 40-95%.

[0047] The beneficial effects of the technical solution of the present invention are as follows:

[0048] This invention utilizes the coupling of oxygen-containing compounds with light hydrocarbon feedstocks such as naphtha to produce more benzene and paraxylene, which can significantly improve the yield of the target products and energy efficiency.

[0049] Oxygen-containing compounds and light hydrocarbon feedstocks such as naphtha can be derived from petroleum, coal, and natural gas, resulting in a wide range of feedstocks. By integrating the first and second reaction units, the yields of benzene and p-xylene, as well as energy efficiency, can be significantly improved.

[0050] This invention can simultaneously produce benzene and xylene while also producing low-carbon olefins, further improving the overall economic efficiency of the process. At the same time, it optimizes the separation process of olefins and aromatics, shortening the processing flow and improving energy utilization efficiency. It has broad application prospects in the industrial production of benzene, para-xylene, and low-carbon olefins.

[0051] This invention can significantly reduce investment and energy consumption in the production process.

[0052] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0053] The above and other objects, features and advantages of the present invention will become more apparent from the more detailed description of exemplary embodiments of the invention in conjunction with the accompanying drawings, wherein the same reference numerals generally represent the same components in the exemplary embodiments of the invention.

[0054] Figure 1 A schematic diagram of a system that produces benzene and p-xylene according to Embodiment 1 of the present invention is shown.

[0055] The annotations in the attached figures are explained as follows:

[0056] 1-First reaction unit; 2-First pre-fractionation unit; 3-Second reaction unit; 4-Second pre-fractionation unit; 5-Purification sub-unit; 6-Demethanization sub-unit; 7-Olefin separation sub-unit; 8-Light hydrocarbon separation unit; 10-Group composition separation unit; 11-Aromatic hydrocarbon separation unit; 12-Crystallization separation unit;

[0057] 101-Naphtha; 102-Oxygenated compounds; 103-First reaction product; 104-Light components; 105-Heavy components; 201-Purified light components; 202-Ethylene; 203-Propylene; 210-C4+ components; 211-Non-aromatic hydrocarbons; 212-C6-C7 components; 213-C8+ components; 214-Benzene; 215-Toluene-rich materials; 216-C8 aromatic hydrocarbons; 217-C9+ components; 218-p-xylene; 219-Mixed C8 aromatic hydrocarbons; 220-Second reaction product; 221-C6-C7 aromatic hydrocarbons; 223-C5 components. Detailed Implementation

[0058] Preferred embodiments of the invention will now be described in more detail. While preferred embodiments of the invention are described below, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0059] Example 1

[0060] This embodiment provides a system that produces benzene and p-xylene, such as Figure 1 As shown, the system includes a first reaction unit 1, a first pre-fractionation unit 2, a light hydrocarbon separation unit, a second pre-fractionation unit 4, a group composition separation unit 10, an aromatic hydrocarbon separation unit 11, a second reaction unit 3, and a crystallization separation unit 12;

[0061] The pyrolysis feedstock pipeline is sequentially connected to the first reaction unit 1 and the first pre-fractionation unit 2; the pyrolysis feedstock pipeline is an oxygen-containing compound 102 feedstock pipeline and a naphtha 101 feedstock pipeline; the first pre-fractionation unit 2 is provided with a light component 104 discharge pipeline and a heavy component 105 discharge pipeline.

[0062] The light hydrocarbon separation unit includes a compression and boosting subunit (not shown), a purification subunit 5, a demethanizing subunit 6, and an olefin separation subunit 7 connected in sequence; the light component 104 discharge pipeline is connected to the compression and boosting subunit of the light hydrocarbon separation unit; the olefin separation subunit 7 is equipped with an ethylene 202 discharge pipeline, an ethane discharge pipeline, a propylene 203 discharge pipeline, a propane discharge pipeline, and a C4+ component 210 discharge pipeline;

[0063] The discharge pipeline of the heavy component 105 is connected to the second pre-fractionation unit 4; the second pre-fractionation unit 4 is provided with a discharge pipeline of C6-C7 component 212 and a discharge pipeline of C8+ component 213; the second pre-fractionation unit 4 is connected to the group composition separation unit 10 through the discharge pipeline of C6-C7 component 212.

[0064] The group composition separation unit 10 is provided with a non-aromatic hydrocarbon 211 discharge pipeline and a C6-C7 aromatic hydrocarbon 221 discharge pipeline;

[0065] The C6-C7 aromatic hydrocarbon 221 discharge pipeline and the C8+ component 213 discharge pipeline are connected together to the aromatic hydrocarbon separation unit 11;

[0066] The aromatic hydrocarbon separation unit 11 is equipped with a benzene tower, a toluene tower and a xylene tower, as well as benzene discharge pipeline, toluene discharge pipeline, C8 aromatic hydrocarbon discharge pipeline and C9+ component discharge pipeline;

[0067] The toluene discharge pipeline is connected to the second reaction unit 3; the second reaction unit 3 is provided with a second reaction product 220 discharge pipeline, which is connected to the aromatic hydrocarbon separation unit 11.

[0068] The C8 aromatic hydrocarbon discharge pipeline is connected to the crystallization separation unit 12; the crystallization separation unit 12 is equipped with a paraxylene 218 collection pipeline and a mixed C8 aromatic hydrocarbon 219 collection pipeline.

[0069] The first pre-fractionation unit is also provided with a C5 component 223 discharge pipeline, and the C5 component discharge pipeline, the non-aromatic hydrocarbon 211 discharge pipeline and the C4+ component 210 discharge pipeline are also connected to the inlet of the first reaction unit 1.

[0070] This embodiment also provides a method for producing benzene and p-xylene, which uses the above-described system and includes the following steps:

[0071] S1: The pyrolysis feedstock and the first recycled material are sequentially sent to the first reaction unit 1 and the first pre-fractionation unit 2 for pyrolysis reaction and pre-fractionation treatment to obtain light components and heavy components;

[0072] The pyrolysis feedstock is oxygen-containing compound 102 and naphtha 101; the oxygen-containing compound 102 is methanol;

[0073] The first reaction product 103 obtained from the first reaction unit 1 includes hydrogen, C1-C4 components, C5+ saturated hydrocarbons, C6-C8 aromatics and C9+ aromatics;

[0074] The light component 104 includes hydrogen and C1 to C5 components;

[0075] The recombinant component 105 includes C6+ saturated hydrocarbons and aromatics;

[0076] S2: C5 component 223 is separated from the first pre-fractionation unit 2, and C5 component 223 is recycled to the first reaction unit 1 as at least a portion of the first recycle material. Other light components are sent to the light hydrocarbon separation unit, where the light components are sequentially compressed and purified to obtain purified light component 201. The purified light component 201 is then sent to the demethanizing subunit 6 for oil absorption and demethanizing treatment to obtain methane hydrogen and C2+ light components. The methane hydrogen is discharged, and the C2+ light components undergo olefin separation to obtain ethylene 202, ethane (not shown), propylene 203, propane (not shown), and C4+ component 210. The C4+ component 210 is recycled to the first reaction unit 1 as at least a portion of the first recycle material.

[0077] S3: The heavy component 105 is sent to the second pre-fractionation unit 4 to obtain C6-C7 component 212 and C8+ component 213; the C6-C7 component 212 is sent to the group composition separation unit 10 to obtain C6-C7 aromatic hydrocarbons 221 and non-aromatic hydrocarbons 211; the C6-C7 aromatic hydrocarbons 221 and the C8+ component 213 are sent to the aromatic hydrocarbon separation unit 11 to obtain benzene 214, toluene-rich material 215, C8 aromatic hydrocarbons 216 and C9+ component 217; the non-aromatic hydrocarbons 211 are recycled to the first reaction unit 1 as at least a portion of the first recycled material.

[0078] The group composition separation unit 10 employs a liquid-liquid extraction separation method.

[0079] S4: The toluene-rich material 215, together with the feed (including hydrogen and C9 aromatics) participating in the disproportionation reaction, is sent to the second reaction unit 3 for toluene shape-selective disproportionation to obtain the second reaction product 220 (including benzene, C8 aromatics and C9+ aromatics); the second reaction product 220 is refluxed to the aromatics separation unit 11 for separation.

[0080] S5: The C8 aromatic hydrocarbon 216 (the mass fraction of p-xylene in C8 aromatic hydrocarbon 216 is 70-80%) is sent to the crystallization separation unit 12 for crystallization separation to obtain p-xylene 218 and mixed C8 aromatic hydrocarbon 219.

[0081] Compared with conventional catalytic reforming for aromatics production, this embodiment can use light hydrocarbons such as methanol and naphtha as raw materials, resulting in a shorter processing flow. According to techno-economic calculations, investment can be reduced by 10%. In this embodiment, the first reaction unit can couple reaction heat and integrate the separation of aromatics with the second reaction unit. According to process flow calculations, the energy consumption of the entire separation process can be reduced by 20%. In addition, this invention can also produce low-carbon olefins as a byproduct, further improving techno-economic efficiency.

[0082] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A system for producing benzene and p-xylene, characterized in that, The system includes a first reaction unit, a first pre-fractionation unit, a light hydrocarbon separation unit, a second pre-fractionation unit, a group composition separation unit, an aromatic hydrocarbon separation unit, a second reaction unit, and a crystallization separation unit; The pyrolysis feedstock pipeline is sequentially connected to the first reaction unit and the first pre-fractionation unit; the pyrolysis feedstock pipeline is an oxygen-containing compound feedstock pipeline and / or a naphtha feedstock pipeline; the first pre-fractionation unit is equipped with a light component discharge pipeline and a heavy component discharge pipeline. The light component discharge pipeline is connected to the light hydrocarbon separation unit; The heavy component discharge pipeline is sequentially connected to the second pre-fractionation unit, the group composition separation unit, and the aromatic hydrocarbon separation unit; the aromatic hydrocarbon separation unit is equipped with a benzene discharge pipeline, a toluene discharge pipeline, a C8 aromatic hydrocarbon discharge pipeline, and a C9+ component discharge pipeline. The toluene discharge pipeline is connected to the second reaction unit; the second reaction unit is provided with a second reaction product discharge pipeline, which is connected to the aromatic hydrocarbon separation unit; The C8 aromatic hydrocarbon discharge pipeline is connected to the crystallization separation unit; the crystallization separation unit is equipped with a p-xylene collection pipeline and a mixed C8 aromatic hydrocarbon collection pipeline.

2. The system for producing benzene and p-xylene according to claim 1, wherein, The light hydrocarbon separation unit includes a compression boosting subunit, a purification subunit, a demethanizing subunit, and an olefin separation subunit connected in sequence. The olefin separation subunit is equipped with ethylene production pipeline, ethane production pipeline, propylene production pipeline, propane production pipeline and C4+ component discharge pipeline. Preferably, the pyrolysis feedstock pipeline and the C4+ component discharge pipeline are sequentially connected to the first reaction unit and the first pre-fractionation unit.

3. The system for producing benzene and p-xylene according to claim 1, wherein, The second pre-fractionation unit is equipped with a C6-C7 component discharge pipeline and a C8+ component discharge pipeline; the second pre-fractionation unit is connected to the group composition separation unit through the C6-C7 component discharge pipeline; The group composition separation unit is equipped with a non-aromatic hydrocarbon discharge pipeline and a C6-C7 aromatic hydrocarbon discharge pipeline. The C6-C7 aromatic hydrocarbon discharge pipeline and the C8+ component discharge pipeline are connected together to the aromatic hydrocarbon separation unit; The cracking feedstock pipeline and the non-aromatic hydrocarbon discharge pipeline are sequentially connected to the first reaction unit and the first pre-fractionation unit. The aromatic hydrocarbon separation unit is equipped with a benzene tower, a toluene tower, and a xylene tower.

4. The system for producing benzene and p-xylene according to claim 1, wherein, The first pre-fractionation unit is equipped with a C5 component discharge pipeline, and the pyrolysis feed pipeline and the C5 component discharge pipeline are sequentially connected to the first reaction unit and the first pre-fractionation unit.

5. A method for producing benzene and p-xylene, characterized in that, This method employs the system described in any one of claims 1-4 and includes the following steps: S1: The pyrolysis feedstock is sequentially sent to the first reaction unit and the first pre-fractionation unit for pyrolysis reaction and pre-fractionation treatment to obtain light components and heavy components; S2: The light components are sent to the light hydrocarbon separation unit for light hydrocarbon separation; S3: The heavy components are sequentially sent to the second pre-fractionation unit, the group composition separation unit and the aromatic hydrocarbon separation unit to obtain benzene, toluene-rich material, C8 aromatic hydrocarbons and C9+ components; S4: The toluene-rich material is sent to the second reaction unit for disproportionation reaction to obtain the second reaction product; the second reaction product is refluxed to the aromatics separation unit for separation treatment; S5: The C8 aromatic hydrocarbons are sent to a crystallization separation unit for crystallization separation to obtain p-xylene and mixed C8 aromatic hydrocarbons.

6. The method for producing benzene and p-xylene according to claim 5, wherein, In step S1: The pyrolysis feedstock is an oxygen-containing compound and / or naphtha; the oxygen-containing compound is methanol and / or dimethyl ether; The first reaction products obtained by the first reaction unit include hydrogen, C1-C4 components, C5+ saturated hydrocarbons, C6-C8 aromatics and C9+ aromatics; The light component includes hydrogen and C1 to C5 components; The heavy components include C6+ saturated hydrocarbons and aromatics; Preferably, the C5 component is separated from the first pre-fractionation unit and recycled to the first reaction unit as at least a portion of the first recycled material.

7. The method for producing benzene and p-xylene according to claim 5, wherein, In step S2, in the light hydrocarbon separation unit, the light components are sequentially compressed and purified to obtain purified light components; the purified light components are sent to the demethanizing subunit for demethanizing to obtain methane hydrogen and C2+ light components; the methane hydrogen is discharged; and the C2+ light components are subjected to olefin separation to obtain ethylene, ethane, propylene, propane and C4+ components. Preferably, the C4+ component is recycled to the first reaction unit as at least a portion of the first recycled material.

8. The method for producing benzene and p-xylene according to claim 5, wherein, In step S3: The recombinant fraction is sent to the second pre-fractionation unit to obtain C6-C7 components and C8+ components; The C6-C7 components are sent to the group composition separation unit to obtain C6-C7 aromatics and non-aromatics; The C6-C7 aromatics and the C8+ component are sent to the aromatics separation unit to obtain benzene, toluene-rich material, C8 aromatics and C9+ component; the non-aromatics are recycled to the first reaction unit as at least part of the first recycled material. The group composition separation unit employs at least one of the following methods: liquid-liquid extraction, extractive distillation, and adsorption separation.

9. The method for producing benzene and p-xylene according to claim 5, wherein, In step S4, the disproportionation reaction employs at least one of the following methods: alkyl transfer, toluene shape-selective disproportionation, methanol-toluene disproportionation, and heavy aromatic hydrocarbon lightening. The feedstock participating in the disproportionation reaction also includes at least one of hydrogen, C9 aromatics, and methanol; The second reaction products include benzene, C8 aromatics, and C9+ aromatics.

10. The method for producing benzene and p-xylene according to claim 5, wherein, In step S5, the mass fraction of p-xylene in the C8 aromatics sent to the crystallization separation unit is 40-95%.

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