A method for producing chemical products from fuel oil

Abstract

The present disclosure relates to a method for producing chemical products from fuel oil, which comprises the following steps: feeding pretreated fuel oil and desorbent into a simulated moving bed adsorption device, and separating to obtain extract and raffinate; the desorbent comprises non-aromatic raffinate oil and low-carbon aromatic hydrocarbon, the non-aromatic raffinate oil and the low-carbon aromatic hydrocarbon are from an aromatic hydrocarbon combination device; the simulated moving bed adsorption device is provided with at least one flushing material, and the flushing material comprises the non-aromatic raffinate oil. The method of the present disclosure can avoid outsourcing desorbent materials, reduce costs; at the same time, the non-aromatic raffinate oil is used as the flushing material, and the selective pore volume of the adsorbent is not occupied, thereby reducing the use cost of the desorbent, improving the utilization efficiency of the adsorbent, and further improving the aromatic hydrocarbon yield.

Description

Technical Field

[0001] This disclosure relates to the field of aromatic hydrocarbon purification technology, and more specifically, to a method for producing chemical products from fuel oil. Background Technology

[0002] In recent years, with the rapid development of my country's new energy industry, the growth rate of refined oil consumption has gradually slowed down, especially diesel consumption, which has peaked. This has highlighted the overcapacity problem in the refining industry, making transformation an urgent necessity. For fuel oil, gasoline fractions can be reformed using chemical methods to produce more aromatics; kerosene fractions have significant future demand in the aviation fuel market, and if there is temporary overcapacity, they can be transferred to diesel fuel tanks or treated as diesel fuel; diesel fractions can be converted into gasoline fractions or BTX using diesel hydrotreating and hydrocracking technologies. However, these technologies all suffer from harsh reaction conditions and high energy and material consumption. Unlike traditional fraction refining processes, component refining is an important future development direction for the refining industry. Especially for diesel, if aromatic and alkane components can be separated, and the aromatic components can be used to produce BTX through hydrocracking or catalytic cracking, while the alkane components can be used to produce low-carbon olefins through thermal cracking, then the aromatic and alkane components in diesel fractions can be utilized for high-value chemical processing, thereby effectively promoting the transformation and development of the refining industry.

[0003] CN111996029A, CN105542835A, CN106187666A, CN105349175A, and CN109022020A disclose some methods for separating aromatics and alkanes using a simulated moving bed process. These methods employ a four-zone simulated moving bed process, with adsorbents often being molecular sieves, silica, or alumina, and desorbents such as cyclohexane, methylcyclohexane, xylene, and toluene, to achieve the separation of alkane and aromatic components in diesel fuel.

[0004] CN106244225A discloses a simulated moving bed adsorption separation method for achieving efficient separation of heavy aromatics. Using a simulated moving bed process, it achieves the separation of aromatics and non-aromatics in C9+ aromatic feedstock. Through efficient matching of the adsorption bed, it can also achieve the separation of monocyclic aromatics and polycyclic aromatics, as well as the separation of alkanes and cycloalkanes.

[0005] CN110938458A discloses a method for producing high-quality white oil. This method produces high-quality white oil through three process units: raw material pretreatment, simulated moving bed aromatic adsorption and separation, and desorbent distillation recovery. It uses surface-functionalized modified mesoporous silica adsorbent to produce high-quality white oil with an aromatic content of less than 5% by mass. This method not only broadens the range of raw material aromatic content but is also applicable to both low-aromatic-content and high-aromatic-content raw materials.

[0006] CN105368482A discloses a method for removing polycyclic aromatic hydrocarbons (PAHs) from diesel fuel using a multi-tower parallel adsorption system. The method uses activated carbon, oxides, or metal-modified materials as adsorbents, and passes the purified diesel fuel into a multi-tower parallel adsorption device to adsorb and separate PAHs from the diesel fuel. The removal rate of PAHs can reach 80%.

[0007] CN113372953A discloses a method for adsorbing and separating saturated and unsaturated hydrocarbons from FCC gasoline. This method uses a simulated moving bed process to separate FCC gasoline into alkane-rich and aromatic-rich components. The alkane component is a high-quality feedstock for ethylene cracking, while the aromatic component is returned to the catalytic cracking unit. It can be used to produce gasoline or hydrogenated and extracted to obtain BTX.

[0008] The desorbents used in the aforementioned adsorption separation processes are mainly mixtures of aromatics and single or multiple alkanes. It is well known that a very small amount of desorbent component is lost during the separation process in the evaporator and raffinate towers. To adjust the desorbent ratio, targeted replenishment of single components is necessary, increasing separation costs. Furthermore, existing processes typically use the desorbent or evaporator as a flushing stream, and these components occupy the selective pore volume of the adsorbent, reducing its utilization rate and consequently decreasing its separation performance. Summary of the Invention

[0009] The purpose of this disclosure is to provide a method for producing chemical products from fuel oil. This method can avoid purchasing desorbent materials externally, thereby reducing costs; at the same time, it can improve the utilization efficiency of the adsorbent, increase the aromatic content in the extract, reduce the aromatic content in the raffinate, and further improve the aromatic yield.

[0010] To achieve the above objectives, this disclosure provides a method for producing chemical products from fuel oil, the method comprising the following steps:

[0011] The pretreated fuel oil and desorbent are introduced into a simulated moving bed adsorption device, where they are separated by contact with the adsorbent to obtain extract and raffinate.

[0012] The desorbent comprises non-aromatic raffinate and low-carbon aromatics, wherein the non-aromatic raffinate and the low-carbon aromatics are derived from an aromatics complex.

[0013] The simulated moving bed adsorption device is provided with at least one flushing material, which includes the non-aromatic raffinate oil.

[0014] Optionally, based on the weight of the non-aromatic raffinate, the non-aromatic raffinate comprises 15-30% n-alkanes, 50-80% cycloalkanes, and 5-15% isoalkanes.

[0015] The low-carbon aromatic hydrocarbon is a C6-C8 aromatic hydrocarbon, selected from one or more of benzene, toluene, and xylene.

[0016] Optionally, in the desorbent, the mass ratio of the low-carbon aromatic hydrocarbon to the non-aromatic raffinate is 0.3 to 3:1, preferably 0.5 to 1.5:1.

[0017] Optionally, the initial boiling point of the fuel oil is 90–110°C, and the final boiling point is 390–410°C;

[0018] The non-aromatic raffinate oil has an initial boiling point of 40–70°C, preferably 55–70°C, and a final boiling point of 110–160°C, preferably 110–130°C.

[0019] Optionally, the simulated moving bed adsorption device is a single adsorption tower, which has 10 to 16 adsorption beds. The inlet for the flushing material is located 1 to 2 adsorption beds downstream of the extract. The adsorption tower is filled with an adsorbent, which is silica.

[0020] The BET specific surface area of ​​the silica is 500–800 m². 2 / g, with a pore size of 1-10nm, the silicon dioxide decreases in mass by less than 5% when calcined at 600°C.

[0021] Optionally, the method further includes: pretreating the fuel oil to obtain pretreated fuel oil;

[0022] The pretreatment is carried out in a fixed bed; the fixed bed is filled with a protective agent, which is selected from one or more of silica, metal oxides, molecular sieves, highly activated clay and activated carbon.

[0023] Optionally, the pretreatment conditions include: operating pressure of 0.1–1 MPa, adsorption temperature of 50–150 °C, and space velocity of 0.1–40 h⁻¹. -1 .

[0024] Optionally, the method further includes: sending the extractant into an extractant tower for separation to obtain an aromatic hydrocarbon-rich component and a first regenerated desorbent; subjecting the aromatic hydrocarbon-rich component to cracking treatment to obtain low-carbon aromatics; the cracking treatment including one or more of catalytic cracking and hydrocracking processes; and returning the first regenerated desorbent to the simulated moving bed adsorption unit for recycling as a desorbent.

[0025] Optionally, the method further includes: sending the raffinate into a raffinate tower for separation to obtain an alkane-rich component and a second regenerated desorbent; subjecting the alkane-rich component to thermal cracking to obtain low-carbon olefins; and returning the second regenerated desorbent to the simulated moving bed adsorption device for recycling as a desorbent.

[0026] Optionally, the operating conditions of the simulated moving bed include: adsorption and desorption temperatures of 70–120°C, feed injection temperatures of 70–120°C, desorbent injection temperatures of 100–130°C, and step switching times of 240–480 s.

[0027] Through the above technical solution, the method disclosed herein uses non-aromatic raffinate oil produced as a byproduct of the aromatic hydrocarbon complex as a desorbent to compound alkanes, avoiding the purchase of desorbent materials and reducing costs; at the same time, using non-aromatic raffinate oil as a flushing material does not occupy the selective pore volume of the adsorbent, thereby reducing the cost of desorbent use, improving the utilization efficiency of the adsorbent, increasing the aromatic hydrocarbon content in the extract, reducing the aromatic hydrocarbon content in the raffinate, and further improving the aromatic hydrocarbon yield.

[0028] Other features and advantages of this disclosure will be described in detail in the following detailed description section. Attached Figure Description

[0029] The accompanying drawings are provided to further illustrate the present disclosure and form part of the specification. They are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation thereof. In the drawings:

[0030] Figure 1 This is a simplified process diagram of a method for producing chemical products from fuel oil.

[0031] Figure 2 This disclosure presents a simplified diagram of the position for simulating the feeding and discharging of a moving bed. Detailed Implementation

[0032] The specific embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit this disclosure.

[0033] This disclosure provides a method for producing chemical products from fuel oil, the method comprising the following steps:

[0034] The pretreated fuel oil and desorbent are introduced into a simulated moving bed adsorption device, where they are separated by contact with the adsorbent to obtain extract and raffinate.

[0035] The desorbent comprises non-aromatic raffinate and low-carbon aromatics, wherein the non-aromatic raffinate and the low-carbon aromatics are derived from an aromatics complex.

[0036] The simulated moving bed adsorption device is provided with at least one flushing material, which includes the non-aromatic raffinate oil.

[0037] This disclosed method uses non-aromatic raffinate, a byproduct of an aromatics complex, as a desorbent to compound alkanes, avoiding the need for externally purchased desorbent materials and reducing costs. Simultaneously, using non-aromatic raffinate as a flushing material does not occupy the selective pore volume of the adsorbent, thus reducing desorbent usage costs while improving adsorbent utilization efficiency, increasing the aromatic content in the effluent, decreasing the aromatic content in the raffinate, and further increasing aromatic yield. This disclosed method enables fuel oil production to separate alkane and aromatic components, which are then used to increase the production of low-carbon olefins and low-carbon aromatics, respectively, providing a viable technological path for the transformation from oil refining to chemical processing.

[0038] According to one embodiment of this disclosure, based on the weight of the non-aromatic raffinate oil, the non-aromatic raffinate oil comprises 15-30% n-alkanes, 50-80% cycloalkanes, and 5-15% isoalkanes. The n-alkanes may be one or more of n-hexane, n-heptane, and n-octane. The cycloalkanes may be one or more of methylcyclopentane, cyclopentane, cyclohexane, methylcyclohexane, 1,2-dimethylcyclohexane, and 1,3-dimethylcyclohexane. The isoalkanes may be one or more of isooctane, 2-methylpentane, and 2,2-dimethylbutane. The low-carbon aromatics are C6-C8 aromatics selected from one or more of benzene, toluene, and xylene.

[0039] According to one embodiment of this disclosure, in the desorbent, the mass ratio of the low-carbon aromatic hydrocarbon to the non-aromatic raffinate is 0.3 to 3:1, preferably 0.5 to 1.5:1.

[0040] According to one embodiment of this disclosure, the initial boiling point of the fuel oil is 90-110°C, and the final boiling point is 390-410°C.

[0041] The non-aromatic raffinate oil has an initial boiling point of 40–70°C, preferably 55–70°C, and a final boiling point of 110–160°C, preferably 110–130°C.

[0042] According to one embodiment of this disclosure, the method further includes: pretreating the fuel oil to obtain pretreated fuel oil; the pretreatment is carried out in a fixed bed; the fixed bed is filled with a protective agent selected from one or more of silica, metal oxides, molecular sieves, highly activated clay, and activated carbon. In one embodiment, the fuel oil can be fuel oil from an atmospheric distillation column, a vacuum distillation column, or fuel oil from a catalytic cracking unit, a reforming unit, a hydrocracking unit, and a coking unit. The pretreatment includes removing strongly polar components from the fuel oil, such as one or more of water, gum, polycyclic sulfur, and polycyclic nitrogen impurities.

[0043] According to one embodiment of this disclosure, the pretreatment conditions include: an operating pressure of 0.1–1 MPa, an adsorption temperature of 50–150 °C, and a space velocity of 0.1–40 h⁻¹. -1 .

[0044] According to one embodiment of this disclosure, the simulated moving bed adsorption device is a single adsorption tower, which has 10 to 16 adsorption beds, preferably 11 to 14 adsorption beds, and each adsorption bed is filled with adsorbent; the adsorbent filled in the adsorption tower is silicon dioxide.

[0045] According to one embodiment of this disclosure, the BET specific surface area of ​​the silica is 500-800 m². 2 / g, preferably 600-700m 2 / g; pore size is 1-10nm, preferably 1.5-6.5nm, and the silicon dioxide decreases in mass by less than 5% when calcined at 600°C.

[0046] According to one embodiment of this disclosure, the simulated moving bed includes a desorption zone, a purification zone, an adsorption zone, and a buffer zone. Raw materials, desorbents, extracts, and raffinates enter and exit the adsorption tower at specific locations. The area between the desorbent inlet and the extract outlet is the desorption zone; the area between the extract outlet and the raw material inlet is the purification zone; the area between the raw material inlet and the raffinate outlet is the adsorption zone; and the area between the raffinate outlet and the desorbent inlet is the buffer zone. The inlet for the flushing material is located 1-2 adsorption bed layers downstream of the extract. The flushing stream includes non-aromatic raffinate oil. In one embodiment, the adsorption bed can be divided into 2-5 adsorption zones, 3-5 purification zones, 2-5 desorption zones, and 1-3 buffer zones. This disclosure does not impose special limitations on the flushing ratio; for example, the flushing volume can be adjusted according to the purity requirements of the actual product. The above-described implementation method helps to avoid the impact of residual materials in the pipeline on the purity and yield of aromatic products, while not occupying the selective pore volume of the adsorbent, reducing the cost of desorbent use, improving the utilization efficiency of the adsorbent, further increasing the aromatic content in the extract, and reducing the aromatic content in the raffinate.

[0047] According to one embodiment of this disclosure, the method further includes: sending the extractant into an extractant tower for separation to obtain an aromatic hydrocarbon-rich component and a first regenerated desorbent; subjecting the aromatic hydrocarbon-rich component to cracking treatment to obtain low-carbon aromatics; the cracking treatment including one or more of catalytic cracking and hydrocracking processes; and returning the first regenerated desorbent to the simulated moving bed adsorption unit for recycling as a desorbent.

[0048] According to one embodiment of this disclosure, the method further includes: sending the raffinate into a raffinate tower for separation to obtain an alkane-rich component and a second regenerated desorbent; subjecting the alkane-rich component to thermal cracking to obtain low-carbon olefins; and returning the second regenerated desorbent to the simulated moving bed adsorption device for recycling as a desorbent.

[0049] According to one embodiment of this disclosure, the first regenerated desorbent and the second regenerated desorbent are added to a desorbent buffer tank, and then low-carbon aromatics or non-aromatic raffinate are added for recycling.

[0050] According to one embodiment of this disclosure, the operating conditions of the simulated moving bed include: an adsorption and desorption temperature of 70–120°C, preferably 90–110°C; a feedstock injection temperature of 70–120°C, preferably 80–100°C; a desorbent injection temperature of 100–130°C, preferably 100–120°C; and a step-switching time of 240–480 s, preferably 300–360 s.

[0051] The method of the present invention is further illustrated by the following examples, but the present invention is not limited thereto.

[0052] In this disclosure, the components of the extract and raffinate are determined using method NB / SH / T 0606.

[0053] Comparative Example 1

[0054] The fuel oil feedstock processed was a typical diesel fraction from a refinery, with the composition shown in Table 1. The aromatic content was 20.6% by mass. This feedstock first entered a fixed-bed protection tower, which was filled with molecular sieve adsorbent. The operating pressure of the fixed-bed protection tower was 0.8 MPa, the operating temperature was 60℃, and the space velocity was 1 h⁻¹. -1 The pretreated fuel oil is obtained.

[0055] like Figure 1 As shown, fuel oil enters the simulated moving bed in zone four, and a desorbent is introduced. The desorbent used is a mixture of toluene and methylcyclohexane, with a toluene mass fraction of 50%. The flushing material used is also the desorbent. The feed rate is 438 g / h, the desorbent feed rate is 780 g / h, the effluent flow rate is 334 g / h, the flushing flow rate is 18 g / h, and the residual liquid is calculated using material balance, approximately 902 g / h.

[0056] After adsorption separation, diesel feedstock yields extract E rich in aromatics and raffinate R rich in alkanes. Extract E and raffinate R are then recycled after desorption separation via a distillation column. The four-zone simulated moving bed contains 12 beds, divided into desorption, purification, adsorption, and buffer zones. Each zone has a 3-4-3-2 bed configuration. Each bed is uniformly packed with silica adsorbent. The adsorption / desorption temperature is 100℃, the feedstock injection temperature is 90℃, the desorbent injection temperature is 110℃, and the step-switching time is 320s. The hydrocarbon composition of the extract and raffinate is shown in Table 1.

[0057] Aromatic purity = Mass of aromatics in extract / Total mass of extract × 100%;

[0058] Aromatics yield = (Mass of aromatics in extract / Mass of aromatics in feed) × 100% = X E (X F -X R ) / (X F (X E -X R )).

[0059] Example 1

[0060] Alkanes and aromatics in diesel fuel were separated according to the method of Comparative Example 1, except that the desorbent used was a mixture of toluene and non-aromatic raffinate, and the flushing stream used was non-aromatic raffinate. The mass ratio of toluene to non-aromatic raffinate was 1:1. Toluene and non-aromatic raffinate came from the aromatics complex. The composition of non-aromatic raffinate is shown in Table 2, and the mass composition of hydrocarbons in the extract and raffinate is shown in Table 1.

[0061] Table 2

[0062] n-Hexane 27.89 Methylcyclopentane 32.32 Cyclopentane 11.38 Cyclohexane 8.15 Methylcyclohexane 9.37 Isooctane 10.88 total 100

[0063] Example 2

[0064] Alkanes and aromatics in diesel fuel were separated according to the method of Comparative Example 1, except that the desorbent used was a mixture of toluene and non-aromatic raffinate oil at a mass ratio of 3:7, and the flushing stream used was non-aromatic raffinate oil. The mass composition of hydrocarbons in the extract and raffinate is shown in Table 1.

[0065] Example 3

[0066] Alkanes and aromatics in diesel fuel were separated according to the method of Comparative Example 1, except that the desorbent used was a mixture of toluene and non-aromatic raffinate oil at a mass ratio of 2:1, and the flushing stream used was non-aromatic raffinate oil. The mass composition of hydrocarbons in the extract and raffinate is shown in Table 1.

[0067] Table 1

[0068]

[0069]

[0070] According to the data in Table 1, comparing Example 1 and Comparative Example 1, it can be seen that, compared to Comparative Example 1 which used toluene and methylcyclohexane as desorbents and used the desorbent as the rinsing material, Example 1 used a mixture of low-carbon aromatics and non-aromatic raffinate oil as desorbents and used non-aromatic raffinate oil as the rinsing material. Under similar operating conditions, the aromatic content in the extract slightly increased from 98.1% to 98.4%, while the aromatic content in the raffinate decreased significantly from 5.5% to 3.0%, and the aromatic yield increased from 77.65% to 88.12%. This indicates that using a mixture of non-aromatic raffinate oil and low-carbon aromatics as the desorbent improves the desorption capacity of the desorbent. Using non-aromatic raffinate oil for rinsing, compared to using the desorbent, reduces the total aromatic content in the adsorption tower, increases the utilization efficiency of the adsorbent, and further improves the aromatic yield. By comparing Examples 1 and 3, it can be seen that within the preferred mass ratio range of low-carbon aromatics to non-aromatic raffinate oil disclosed in this invention, the desorption capacity of the desorbent can be further improved, the utilization efficiency of the adsorbent can be increased, and the yield of aromatics can be improved.

[0071] Comparative Example 2

[0072] The diesel feedstock from Comparative Example 1 was directly fed into the thermal cracking unit. The cracking temperature was 750℃, the pressure at the feed port of the cracking furnace was 0.02MPa, the feed rate was 30g / h, the steam rate was 15g / h, and the single-pass operation time of the cracking furnace was 6h. The product distribution is shown in Table 3.

[0073] Example 4

[0074] The raffinate from Example 1 was fed into a thermal cracking unit under the same thermal cracking operating conditions as Comparative Example 2, and the product distribution is shown in Table 3.

[0075] Table 3

[0076] hydrogen 0.69 0.81 methane 9.66 10.88 ethylene 24.52 31.55 propylene 14.12 15.55 Hybrid C4 11.12 11.1 other 39.89 30.11 sum 100 100

[0077] According to the data in Table 3, a comparison between Comparative Example 2 and Example 4 shows that after the diesel feedstock undergoes adsorption separation, the alkane components are fed into the thermal cracking unit. Compared with directly feeding the diesel feedstock into the thermal cracking unit, the proportion of ethylene in the cracking products increases by approximately 7%. This indicates that the method of this disclosure, which separates the alkane components from the diesel feedstock and feeds them into the ethylene thermal cracking unit, can further improve the ethylene yield.

[0078] The preferred embodiments of this disclosure have been described in detail above with reference to the accompanying drawings. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.

[0079] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0080] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.

Claims

1. A method for producing chemical products from fuel oil, characterized in that, The method includes the following steps: The pretreated fuel oil and desorbent are introduced into a simulated moving bed adsorption device, where they are separated by contact with the adsorbent to obtain extract and raffinate. The adsorbent is silica; the desorbent comprises non-aromatic raffinate and low-carbon aromatics, wherein the non-aromatic raffinate and the low-carbon aromatics are derived from an aromatics complex; based on the weight of the non-aromatic raffinate, the non-aromatic raffinate comprises 15-30% n-alkanes, 50-80% cycloalkanes, and 5-15% isoalkanes; in the desorbent, the mass ratio of the low-carbon aromatics to the non-aromatic raffinate is 0.5-1.5:1; The simulated moving bed adsorption device is provided with at least one flushing material, which includes the non-aromatic raffinate oil.

2. The method according to claim 1, wherein, The low-carbon aromatic hydrocarbon is a C6-C8 aromatic hydrocarbon, selected from one or more of benzene, toluene, and xylene.

3. The method according to claim 1, wherein, The initial boiling point of the fuel oil is 90~110℃, and the final boiling point is 390~410℃; The non-aromatic raffinate oil has an initial boiling point of 40-70℃ and a final boiling point of 110-160℃.

4. The method according to claim 1, wherein, The non-aromatic raffinate oil has an initial boiling point of 55-70℃ and a final boiling point of 110-130℃.

5. The method according to claim 1, wherein, The simulated moving bed adsorption device is a single adsorption tower, which contains 10 to 16 adsorption beds. The inlet for the flushing material is located 1 to 2 adsorption beds downstream of the extract. The BET specific surface area of ​​the silica is 500~800 m². 2 / g, with a pore size of 1~10nm, the silicon dioxide decreases in mass by less than 5% when calcined at 600℃.

6. The method according to claim 1, wherein, The method further includes: pretreating the fuel oil to obtain pretreated fuel oil; The pretreatment is carried out in a fixed bed; the fixed bed is filled with a protective agent, which is selected from one or more of silica, metal oxides, molecular sieves, highly activated clay and activated carbon.

7. The method according to claim 6, wherein, The pretreatment conditions include: operating pressure of 0.1~1 MPa, adsorption temperature of 50~150℃, and space velocity of 0.1~40 h⁻¹. -1 .

8. The method according to claim 1, wherein, The method further includes: sending the extractant into an extractant tower for separation to obtain an aromatic hydrocarbon-rich component and a first regenerated desorbent; subjecting the aromatic hydrocarbon-rich component to cracking treatment to obtain low-carbon aromatics; the cracking treatment includes one or more of catalytic cracking and hydrocracking processes; and returning the first regenerated desorbent to the simulated moving bed adsorption unit for recycling as a desorbent.

9. The method according to claim 1, wherein, The method further includes: sending the raffinate into a raffinate tower for separation to obtain an alkane-rich component and a second regenerated desorbent; subjecting the alkane-rich component to thermal cracking to obtain low-carbon olefins; and returning the second regenerated desorbent to the simulated moving bed adsorption device for recycling as a desorbent.

10. The method according to claim 1, wherein, The operating conditions of the simulated moving bed include: adsorption and desorption temperatures of 70~120℃, feed injection temperature of 70~120℃, desorbent injection temperature of 100~130℃, and step switching time of 240~480s.

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