Method for producing chemical from fuel oil

Abstract

A method for separating aromatic hydrocarbon components and non-aromatic hydrocarbon components in fuel oil by using a simulated moving bed. The method comprises the following steps: introducing fuel oil into a simulated moving bed so that the fuel oil is in contact with an adsorbent in the simulated moving bed and aromatic hydrocarbon components in the fuel oil are selectively adsorbed by the adsorbent, thereby obtaining a raffinate rich in non-aromatic hydrocarbon components; and introducing a desorbent into the simulated moving bed to desorb the adsorbed aromatic hydrocarbon components from the adsorbent, thereby obtaining an extract rich in aromatic components, wherein the desorbent comprises an alkane mixture and aromatic hydrocarbons, and the alkane mixture comprises cycloalkanes and linear alkanes. The method can significantly reduce the concentration of the aromatic hydrocarbon desorbent left in an adsorption area, improve the utilization efficiency of the adsorbent, and thus improve the aromatic hydrocarbon content in the extract, reduce the aromatic hydrocarbon content in the raffinate and further improve the aromatic hydrocarbon yield.

Description

A method for producing chemicals from fuel oil Technical Field

[0001] The present disclosure relates to the technical field of simulated moving bed separation, and in particular, to a method for producing aromatic components and non-aromatic components from fuel oil through simulated moving bed separation. Background Art

[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, with diesel consumption in particular reaching its peak. This has highlighted overcapacity in the refining industry, necessitating an urgent need for transformation. For fuel oil, gasoline fractions can be reformed chemically to produce more aromatics. Kerosene fractions, facing significant future demand in the aviation fuel market, can also be transferred to diesel pools or treated as diesel in the event of temporary overcapacity. Diesel fractions can be converted into gasoline fractions or BTX using technologies such as diesel hydroreforming and hydrocracking. However, these technologies suffer from harsh reaction conditions and high energy and material consumption. Unlike traditional distillate refining processes, fractional refining is a key development direction for the refining industry. For diesel in particular, if the aromatic and non-aromatic components in diesel can be separated, the aromatic components can be used to produce BTX through hydrocracking or catalytic cracking, while the non-aromatic components can be used to produce light olefins through thermal cracking. This would enable the high-value chemical utilization of the aromatic and non-aromatic components in the diesel fraction, thereby effectively promoting the transformation and development of the refining industry.

[0003] CN111996029A, CN105542835A, CN106187666A, CN105349175A, and CN109022020A disclose methods for separating aromatics and alkanes using a simulated moving bed process. A four-zone simulated moving bed process is used, and the adsorbents are mostly molecular sieves, silica, or alumina, and the desorbents are cyclohexane, methylcyclohexane, xylene, toluene, etc., to achieve the separation of alkane and aromatic components in diesel.

[0004] CN106244225A discloses a simulated moving bed adsorption separation method for achieving efficient separation of heavy aromatics. Using a simulated moving bed process, the separation of aromatics and non-aromatics in C9+ aromatic feedstock is achieved. Through efficient matching of the adsorption bed layer, the separation of monocyclic aromatics and polycyclic aromatics, and the separation of paraffins and cycloparaffins can also be achieved.

[0005] CN110938458A discloses a method for producing high-quality white oil. The method produces high-quality white oil through three process units: raw material pretreatment, simulated moving bed aromatic adsorption separation, and desorbent distillation recovery. The method uses a 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 aromatic content of the raw materials, but is also applicable to raw materials with both low and high aromatic content.

[0006] CN105368482A discloses a method for removing polycyclic aromatic hydrocarbons from diesel by multi-tower parallel adsorption. Activated carbon, oxides or metal-modified materials are used as adsorbents. The diesel after impurities removal is passed into a multi-tower parallel adsorption device to adsorb and separate the polycyclic aromatic hydrocarbons in the diesel. The removal rate of polycyclic aromatic hydrocarbons can reach 80%.

[0007] CN113372953A discloses a method for separating saturated hydrocarbons and unsaturated hydrocarbons from FCC gasoline by adsorption. This method uses a simulated moving bed process to separate FCC gasoline into an alkane-rich component and an aromatics-rich component. The alkane component is a high-quality raw material for ethylene cracking, and the aromatic component is returned to the catalytic cracking unit to produce gasoline or to obtain BTX after hydrogenation and extraction.

[0008] The desorbent used in the above-mentioned adsorption separation process is primarily a mixture of aromatic hydrocarbons and cycloalkanes. While the separation efficiency of this mixed desorbent is improved compared to that of a single aromatic desorbent, the field is still searching for desorbents with even better separation performance. Furthermore, existing processes typically use the desorbent or the extract as a flushing material. These components occupy the selective pore volume of the adsorbent, reducing adsorbent utilization and resulting in a decrease in adsorbent separation performance.

[0009] Summary of the Invention

[0010] The present invention provides a method for separating aromatic and non-aromatic components in fuel oil using a simulated moving bed. This method significantly reduces the residual concentration of aromatic desorbent in the adsorption zone, improving adsorbent utilization efficiency, thereby increasing the aromatic content in the extract and reducing the aromatic content in the raffinate, further improving the aromatic yield.

[0011] The inventors discovered that when aromatic hydrocarbons are used as desorbents, the residual concentration of the aromatic desorbent in the adsorption zone is high, occupying the adsorbent pores. This reduces the adsorption efficiency of aromatic hydrocarbons in the feedstock oil on the adsorbent, resulting in low adsorbent utilization and low aromatic hydrocarbon yield. However, when a combination of aromatic hydrocarbons and cycloalkanes is used as the desorbent, the residual concentration of the aromatic desorbent in the adsorption zone is reduced, and the aromatic hydrocarbon yield is improved.

[0012] The present inventors further discovered that by replacing part of the cycloalkanes in the mixed desorbent of aromatics and cycloalkanes with paraffins, the residual concentration of the aromatic desorbent in the adsorption zone was significantly reduced and the aromatic yield was significantly improved.

[0013] In a first aspect, the present disclosure provides a method for separating aromatic components and non-aromatic components in fuel oil using a simulated moving bed, wherein the simulated moving bed comprises one or more adsorption towers, each of which is filled with an adsorbent, and the fuel oil comprises aromatic components and non-aromatic components, wherein the method comprises the following steps:

[0014] The fuel is introduced into the simulated moving bed and contacts with the adsorbent in the simulated moving bed. The aromatic components in the fuel are selectively adsorbed by the adsorbent to obtain a raffinate rich in non-aromatic components.

[0015] The desorbent is introduced into the simulated moving bed to desorb the adsorbed aromatic components from the adsorbent to obtain an extract rich in aromatic components.

[0016] The desorbent comprises an alkane mixture and aromatic hydrocarbons, and the alkane mixture comprises cycloalkanes and chain alkanes.

[0017] In one embodiment of the present disclosure, the paraffins include normal paraffins and isoparaffins.

[0018] In a second aspect, the present disclosure provides a system for separating aromatic components and non-aromatic components in fuel oil using a simulated moving bed, comprising a simulated moving bed, an adsorbent and a desorbent, wherein the simulated moving bed comprises one or more adsorption towers, each of which is filled with the adsorbent, the fuel oil comprises aromatic components and non-aromatic components, and the desorbent comprises an alkane mixture and aromatic hydrocarbons, wherein the alkane mixture comprises cycloalkanes and chain alkanes.

[0019] The method disclosed herein replaces part of the cycloalkanes in the mixed desorbent of aromatics and cycloalkanes in the prior art with chain alkanes, thereby significantly reducing the residual concentration of the aromatic desorbent in the adsorption zone and significantly improving the aromatic yield. Simultaneously, the alkane mixture is used as a flushing material, which does not occupy the selective pore volume of the adsorbent, thereby improving the utilization efficiency of the adsorbent, increasing the aromatic content in the extracted liquid, reducing the aromatic content in the raffinate, and further improving the aromatic yield.

[0020] Other features and advantages of the present disclosure will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings are used to provide a further understanding of the present disclosure and constitute a part of the specification. Together with the following detailed description, they are used to explain the present disclosure but do not constitute a limitation of the present disclosure. In the accompanying drawings:

[0022] FIG1 is a simplified process diagram of the method for separating aromatic components and non-aromatic components in fuel oil according to the present disclosure.

[0023] FIG2 is a simplified diagram of the positions of the material inlet and outlet of the simulated moving bed of the present disclosure. DETAILED DESCRIPTION

[0024] The following describes the specific embodiments of the present disclosure in detail. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present disclosure, and are not intended to limit the present disclosure.

[0025] Unless otherwise specified, the terms used herein have the same meaning as commonly understood by those skilled in the art. If a term is defined herein and its definition is different from the commonly understood meaning in the art, the definition herein shall prevail.

[0026] The expressions "comprising" or "including" herein should be interpreted as including all the specifically mentioned features as well as optional, additional, unspecified features. As used herein, the use of the term "comprising" also discloses solutions in which no further features than the specifically mentioned features are present, for example, the expressions "consisting essentially of" and "consisting of.

[0027] The term "fuel oil" used herein refers to fuel oils such as light naphtha, heavy naphtha, gasoline, kerosene, and diesel.

[0028] In a first aspect, the present disclosure provides a method for separating aromatic components and non-aromatic components in fuel oil using a simulated moving bed, wherein the simulated moving bed comprises one or more adsorption towers, each of which is filled with an adsorbent, and the fuel oil comprises aromatic components and non-aromatic components, wherein the method comprises the following steps:

[0029] The fuel is introduced into the simulated moving bed and contacts with the adsorbent in the simulated moving bed. The aromatic components in the fuel are selectively adsorbed by the adsorbent to obtain a raffinate rich in non-aromatic components.

[0030] The desorbent is introduced into the simulated moving bed to desorb the adsorbed aromatic components from the adsorbent to obtain an extract rich in aromatic components.

[0031] The desorbent comprises an alkane mixture and aromatic hydrocarbons, and the alkane mixture comprises cycloalkanes and chain alkanes.

[0032] In one embodiment of the present disclosure, the paraffins include normal paraffins and isoparaffins.

[0033] In one embodiment of the present disclosure, the alkane mixture comprises 30%-70% of cycloalkanes and 30%-70% of paraffins, based on the weight of the alkane mixture. Preferably, the alkane mixture comprises 30%-70% of cycloalkanes, 5%-50% of isoalkanes and 20-60% of normal alkanes. More preferably, the alkane mixture comprises 40%-65% of cycloalkanes, 10%-35% of isoalkanes and 25%-50% of normal alkanes.

[0034] In one embodiment of the present disclosure, the aromatic hydrocarbon is a C6-C8 aromatic hydrocarbon, preferably one or more selected from benzene, toluene and xylene.

[0035] In one embodiment of the present disclosure, the cycloalkane is selected from one or more of methylcyclopentane, cyclopentane, cyclohexane, methylcyclohexane, 1,2-dimethylcyclohexane and 1,3-dimethylcyclohexane.

[0036] In one embodiment of the present disclosure, the normal alkane is selected from one or more of normal hexane, normal heptane and normal octane.

[0037] In one embodiment of the present disclosure, the isoalkane is selected from one or more of isooctane, 2-methylpentane and 2,2-dimethylbutane.

[0038] In one embodiment of the present disclosure, in the desorbent, the mass ratio of the aromatic hydrocarbon to the alkane mixture is 0.3-3, preferably 0.5-1.5, and more preferably 1-1.5.

[0039] In one embodiment of the present disclosure, the simulated moving bed is further provided with a flushing material, which is the alkane mixture.

[0040] In one embodiment of the present disclosure, the adsorbent is selected from one or more of silica, X molecular sieve, Y molecular sieve, and alumina.

[0041] In one embodiment of the present disclosure, the BET specific surface area of ​​the silicon dioxide is 500-800 m 2 / g, preferably 600-700m 2 / g; the pore diameter is 1-10nm, preferably 1.5-6.5nm, and the mass of the silicon dioxide is reduced by less than 5% by weight when calcined at 600°C.

[0042] In one embodiment of the present disclosure, the initial boiling point of the fuel is 90-110° C., and the final boiling point is 390-410° C.; preferably, the fuel is diesel.

[0043] In one embodiment of the present disclosure, the simulated moving bed is a single adsorption tower, 10-16 adsorption beds are provided in the adsorption tower, and the inlet for the flushing material is arranged 1-2 adsorption beds downstream of the extract.

[0044] In one embodiment of the present disclosure, the method further comprises: pre-treating the fuel oil to obtain pre-treated fuel oil. The pre-treatment is carried out in a fixed bed, wherein a protective agent is loaded in the fixed bed, and the protective agent is selected from one or more of silica, alumina, molecular sieve, highly activated clay, and activated carbon. The pre-treatment conditions include: an operating pressure of 0.1-1 MPa, an adsorption temperature of 50-150°C, and an air velocity of 0.1-40 h / min. -1The pretreatment includes removing highly polar components in the fuel, such as one or more of water, colloids, condensed ring sulfur and condensed ring nitrogen impurities.

[0045] In one embodiment of the present disclosure, the fuel oil may be from an atmospheric distillation tower or a vacuum distillation tower, or from a catalytic cracking unit, a reforming unit, a hydrocracking unit, or a coking unit. The fuel oil is preferably diesel from the above units.

[0046] In one embodiment of the present disclosure, the method further includes sending the extract into an extract tower for separation to obtain aromatic components and a first regenerated desorbent; cracking the aromatic components 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 for recycling as a desorbent.

[0047] In one embodiment of the present disclosure, the method further includes sending the raffinate into a raffinate tower for separation to obtain non-aromatic components and a second regenerated desorbent; performing thermal cracking on the non-aromatic components to obtain light olefins; and returning the second regenerated desorbent to the simulated moving bed for recycling as a desorbent.

[0048] In a second aspect, the present disclosure provides a system for separating aromatic components and non-aromatic components in fuel oil using a simulated moving bed, comprising a simulated moving bed, an adsorbent and a desorbent, wherein the simulated moving bed comprises one or more adsorption towers, each of which is filled with the adsorbent, the fuel oil contains aromatic components and non-aromatic components, and the desorbent contains an alkane mixture and aromatics, wherein the alkane mixture contains cycloalkanes and chain alkanes, and the chain alkanes preferably contain normal alkanes and isoalkanes.

[0049] In one embodiment of the present disclosure, the simulated moving bed includes a desorption zone, a purification zone, an adsorption zone and a buffer zone. Fuel, desorbent, extract, and residual liquid 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 fuel inlet is the purification zone, the area between the fuel inlet and the residual liquid outlet is the adsorption zone, and the area between the residual liquid outlet and the desorbent inlet is the buffer zone. In one embodiment of the present disclosure, 10-16 adsorption beds are provided in the adsorption tower, and the adsorption bed partitions can be set to 2-5 beds in the adsorption zone, 3-5 beds in the purification zone, 2-5 beds in the desorption zone, and 1-3 beds in the buffer zone.

[0050] In one embodiment of the present disclosure, the simulated moving bed is further provided with a flushing material, and the inlet of the flushing material is arranged at 1-2 adsorption beds downstream of the extract. The flushing material is the alkane mixture. The present disclosure does not impose any special restrictions on the flushing ratio. For example, the flushing amount can be adjusted according to the purity requirements of the actual product. The use of the flushing material of the present disclosure is conducive to avoiding the influence of the residual material in the pipeline on the purity and yield of the aromatic hydrocarbon product. At the same time, it does not occupy the selective pore volume of the adsorbent, improves the utilization efficiency of the adsorbent, further increases the aromatic hydrocarbon content in the extract, and reduces the aromatic hydrocarbon content in the residual liquid.

[0051] In one embodiment of the present disclosure, the operating conditions of the simulated moving bed include: adsorption and desorption temperatures of 70-120°C, preferably 90-110°C; raw material injection temperature of 70-120°C, preferably 80-100°C; desorbent injection temperature of 100-130°C, preferably 100-120°C; step switching time of 240-480s, preferably 300-360s.

[0052] This disclosure involves the following technical solutions:

[0053] Solution 1: A method for producing chemicals from fuel oil, characterized in that the method comprises the following steps:

[0054] The pretreated fuel oil and desorbent enter the simulated moving bed adsorption device, contact with the adsorbent and separate to obtain an extract and a raffinate;

[0055] The desorbent includes non-aromatic raffinate oil and low-carbon aromatic hydrocarbons, and the non-aromatic raffinate oil and the low-carbon aromatic hydrocarbons come from an aromatics complex;

[0056] The simulated moving bed adsorption device is provided with at least one flushing material, and the flushing material includes the non-aromatic raffinate oil.

[0057] Option 2: The method according to Option 1, wherein the non-aromatic raffinate oil comprises 15-30% normal paraffins, 50-80% cycloparaffins, and 5-15% isoparaffins, based on the weight of the non-aromatic raffinate oil.

[0058] The low-carbon aromatic hydrocarbons are C6-C8 aromatic hydrocarbons, selected from one or more of benzene, toluene and xylene.

[0059] Option 3: The method according to Option 1, wherein, in the desorbent, the mass ratio of the low-carbon aromatic hydrocarbons to the non-aromatic raffinate oil is 0.3 to 3:1, preferably 0.5 to 1.5:1.

[0060] Option 4: The method according to Option 1, wherein the fuel oil has an initial boiling point of 90-110°C and a final boiling point of 390-410°C;

[0061] 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.

[0062] Option 5. The method according to Option 1, wherein the simulated moving bed adsorption device is a single adsorption tower, wherein the adsorption tower is provided with 10 to 16 adsorption beds, and the inlet for the flushing material is provided 1 to 2 adsorption beds downstream of the extract; and the adsorbent is filled in the adsorption tower, wherein the adsorbent is silica.

[0063] The BET specific surface area of ​​the silicon dioxide is 500 to 800 m2 / g, the pore diameter is 1 to 10 nm, and the mass reduction of the silicon dioxide is less than 5 mass% when calcined at 600°C.

[0064] Option 6: The method according to Option 1, wherein the method further comprises: pre-treating the fuel oil to obtain pre-treated fuel oil;

[0065] The pretreatment is carried out in a fixed bed; the fixed bed is filled with a protective agent, and the protective agent is selected from one or more of silicon dioxide, metal oxides, molecular sieves, highly active clay and activated carbon.

[0066] Option 7. The method according to Option 6, wherein the pretreatment conditions include: operating pressure of 0.1 to 1 MPa, adsorption temperature of 50 to 150°C, and space velocity of 0.1 to 40 h-1.

[0067] Option 8. The method according to Option 1, wherein the method further comprises: sending the extract into an extract tower for separation to obtain an aromatic-rich component and a first regenerated desorbent; subjecting the aromatic-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 device for recycling as a desorbent.

[0068] Option 9. The method according to Option 1, wherein the method further comprises: sending the raffinate into a raffinate tower for separation to obtain an alkane-rich component and a second regenerated desorbent; performing thermal cracking treatment on the alkane-rich component to obtain light olefins; and returning the second regenerated desorbent to the simulated moving bed adsorption device for recycling as a desorbent.

[0069] Option 10. A method according to Option 1, wherein the operating conditions of the simulated moving bed include: adsorption and desorption temperatures of 70 to 120°C, raw material injection temperature of 70 to 120°C, desorbent injection temperature of 100 to 130°C, and step switching time of 240 to 480s.

[0070] Example

[0071] The present invention is further illustrated by the following examples, but the present invention is not limited thereto.

[0072] The components of the diesel feedstock in the present disclosure are determined using the NB / SH / T0606 method.

[0073] Examples 1-3 and Comparative Examples 1-4

[0074] To investigate the effect of desorbent composition on aromatics separation, the following experiment was conducted. The fuel feedstock processed was a typical diesel fraction from a refinery, with a composition shown in Table 1, and an aromatics content of 20.6% by weight. The feedstock first entered a fixed-bed guard tower filled with molecular sieve adsorbent. The fixed-bed guard tower operated at a pressure of 0.8 MPa, a temperature of 60°C, and a space velocity of 1 h / min. -1 The molecular sieve adsorbent used in the protection tower is RAN-520 from Sinopec Catalyst Company.

[0075] As shown in Figure 1, the pretreated fuel oil enters a four-zone simulated moving bed, where a desorbent is introduced. The desorbents used are listed in Table 2. The flushing material used is a mixture of alkanes in the desorbent, and the adsorbent used is silica RAX-3000 from Sinopec Catalyst Company. The feedstock throughput is 438 g / h, the desorbent feed rate is 780 g / h, the flushing rate is 18 g / h, the draw rate is 334 g / h, and the raffinate rate, calculated using a material balance, is approximately 902 g / h.

[0076] After the diesel feed is separated by adsorption in a simulated moving bed, extract E, rich in aromatics, and raffinate R, rich in non-aromatics, are obtained. Extract E and raffinate R are separated in a distillation column, and the resulting desorbent is recycled. The four-zone simulated moving bed contains 12 beds, divided into desorption, purification, adsorption, and buffer zones. The beds in each zone are arranged in a 3-4-3-2 configuration, and each bed is evenly loaded with silica adsorbent. The adsorption and desorption temperature is 100°C, the feed injection temperature is 90°C, the desorbent injection temperature is 110°C, and the step-by-step switching time is 320 seconds. The aromatics yields are shown in Table 2.

[0077] Aromatic hydrocarbon yield = mass of aromatic hydrocarbons in the extract / mass of aromatic hydrocarbons in the feed × 100%.

[0078] Table 1: Composition of diesel feedstock in weight % based on total diesel weight

[0079] Table 2: Desorbents used and aromatic yields

[0080] According to the data in Table 2, when toluene was mixed with n-heptane and / or isooctane as a desorbent (Comparative Examples 1, 2, and 4), the aromatics yield was approximately 81%. When toluene was mixed with methylcyclohexane as a desorbent (Comparative Example 3), the aromatics yield was improved to approximately 83%. When n-heptane and / or isooctane were used to replace some of the methylcyclohexane in the desorbent mixed with toluene and methylcyclohexane (Examples 1-3), the aromatics yield was significantly increased to 86% or 87%. The combination of toluene + n-heptane + isooctane + methylcyclohexane had the highest separation efficiency, with an aromatics yield of 87.31%. This demonstrates the synergistic effect between the different components of the desorbent disclosed herein, resulting in a significant increase in aromatics yield.

[0081] In order to further explore the mechanism of the improvement in aromatics yield, the toluene content at the raw material inlet of the simulated moving bed adsorption zone in the above Examples 1-3 and Comparative Examples 1-4 was measured. The results are shown in Table 3.

[0082] Table 3: Toluene content at the raw material inlet of the adsorption zone

[0083] According to the data in Table 3, the aromatics yield is closely related to the toluene content at the raw material inlet of the simulated moving bed adsorption zone. When the toluene content at the raw material inlet of the adsorption zone is high, the aromatics yield is low; when the toluene content at the raw material inlet of the adsorption zone is low, the aromatics yield is high. By replacing part of the methylcyclohexane in the desorbent mixed with toluene and methylcyclohexane with n-heptane and / or isooctane, the residual toluene content at the raw material inlet of the adsorption zone is significantly reduced, and the aromatics yield is significantly improved. The inventor speculates that the difference in polarity between the desorbent and the aromatics in diesel is particularly important for the aromatics separation effect. The combined use of aromatics, cycloalkanes and paraffins as desorbents can more accurately control the polarity of the desorbent, so that the polarity of the desorbent is better matched with the polarity of the aromatics in diesel, so that the desorbent can both desorb the strongly polar aromatic components in the diesel in the adsorbent pores and be replaced by the weakly polar aromatic components in the diesel, realizing the process of adsorbent adsorption of aromatics, desorbent desorption of aromatics, and aromatic replacement of the desorbent in the adsorbent.

[0084] Examples 4-8 and Comparative Examples 5-6

[0085] To investigate the effect of the mass ratio of the aromatics to alkanes mixture in the desorbent on the aromatics separation efficiency, the following experiment was conducted. The experimental conditions were essentially the same as those in Example 1, except that the mass ratio of the aromatics to alkanes mixture was as shown in Table 4. Furthermore, the mass ratio of n-heptane, isooctane, and methylcyclohexane was 1:1:1.

[0086] Table 4: Mass ratio of aromatic hydrocarbons to alkane mixtures and aromatic hydrocarbon yields

[0087] The data in Table 4 show that when the mass ratio of the aromatics to alkanes mixture is between 0.3 and 3, the aromatics yield can reach over 81%, while outside this mass ratio range, the aromatics yield significantly decreases. Furthermore, when the mass ratio is between 0.5 and 1.5, the aromatics yield can be further increased to 83% or higher. Furthermore, the most preferred mass ratio is between 1 and 1.5, with aromatics yields as high as 86% to 87%.

[0088] The preferred embodiments of the present disclosure are described in detail above in conjunction with the accompanying drawings. However, the present disclosure is not limited to the specific details of the above embodiments. Within the technical concept of the present disclosure, various simple modifications can be made to the technical solutions of the present disclosure, and these simple modifications all fall within the scope of protection of the present disclosure.

[0089] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present disclosure will not further describe various possible combinations.

[0090] In addition, the various embodiments of the present disclosure may be arbitrarily combined, and as long as they do not violate the concept of the present disclosure, they should also be regarded as the contents disclosed by the present disclosure.

Claims

1. A method for separating aromatic components and non-aromatic components in fuel oil by using a simulated moving bed, wherein the simulated moving bed comprises one or more adsorption towers, each of which is filled with an adsorbent, and the fuel oil comprises aromatic components and non-aromatic components, wherein the method comprises the following steps: The fuel oil is introduced into the simulated moving bed and contacts with the adsorbent in the simulated moving bed. The aromatic components in the fuel oil are selectively adsorbed by the adsorbent to obtain a raffinate rich in non-aromatic components. The desorbent is introduced into the simulated moving bed to desorb the adsorbed aromatic components from the adsorbent to obtain an extract rich in aromatic components. The desorbent comprises an alkane mixture and aromatic hydrocarbons, and the alkane mixture comprises cycloalkanes and chain alkanes.

2. The method according to claim 1, wherein: The paraffins include normal paraffins and isoparaffins.

3. The method according to claim 2, wherein: Based on the weight of the alkane mixture, the alkane mixture contains 30%-70% of cycloalkanes and 30%-70% of chain alkanes. Preferably, the alkane mixture contains 30%-70% of cycloalkanes, 5%-50% of isoalkanes and 20-60% of normal alkanes. More preferably, the alkane mixture contains 40%-65% of cycloalkanes, 10%-35% of isoalkanes and 25-50% of normal alkanes.

4. The method according to claim 2, wherein: The aromatic hydrocarbon is a C6-C8 aromatic hydrocarbon, preferably one or more selected from benzene, toluene and xylene; and / or The cycloalkane is selected from one or more of methylcyclopentane, cyclopentane, cyclohexane, methylcyclohexane, 1,2-dimethylcyclohexane and 1,3-dimethylcyclohexane; and / or The normal alkane is selected from one or more of normal hexane, normal heptane and normal octane; and / or The isoalkane is selected from one or more of isooctane, 2-methylpentane and 2,2-dimethylbutane.

5. The method according to claim 1, wherein: In the desorbent, the mass ratio of the aromatic hydrocarbon to the alkane mixture is 0.3-3, preferably 0.5-1.5, and more preferably 1-1.

5.

6. The method according to claim 1, wherein: The simulated moving bed is also provided with a flushing material consisting of the alkane mixture.

7. The method according to claim 1, wherein: The adsorbent is selected from one or more of silicon dioxide, X molecular sieve, Y molecular sieve, and alumina.

8. The method according to claim 1, wherein: The initial distillation point of the fuel oil is 90-110° C., and the final distillation point is 390-410° C.; preferably, the fuel oil is diesel.

9. The method according to claim 6, wherein: The simulated moving bed is a single adsorption tower, and 10-16 adsorption beds are arranged in the adsorption tower. The inlet of the flushing material is arranged at 1-2 adsorption beds downstream of the extracted liquid.

10. The method according to claim 1, wherein: The method further comprises: pre-treating the fuel to obtain pre-treated fuel; The pretreatment is carried out in a fixed bed; a protective agent is filled in the fixed bed, and the protective agent is selected from one or more of silicon dioxide, aluminum oxide, molecular sieve, highly active clay and activated carbon; The pretreatment conditions include: operating pressure of 0.1-1 MPa, adsorption temperature of 50-150°C, space velocity of 0.1-40h -1 .

11. The method according to claim 1, wherein: The method further comprises: The extract is sent to an extract tower for separation to obtain aromatic components and a first regenerated desorbent; the aromatic components are cracked to obtain low-carbon aromatics; the cracking process includes one or more of catalytic cracking and hydrocracking processes; the first regenerated desorbent is returned to the simulated moving bed for recycling as a desorbent; and / or The raffinate is sent to a raffinate tower for separation to obtain non-aromatic components and a second regenerated desorbent; the non-aromatic components are subjected to thermal cracking to obtain light olefins; and the second regenerated desorbent is returned to the simulated moving bed for recycling as a desorbent.

12. The method according to claim 1, wherein: The operating conditions of the simulated moving bed include: adsorption and desorption temperatures of 70-120° C., fuel injection temperature of 70-120° C., desorbent injection temperature of 100-130° C., and step switching time of 240-480 s.

13. A system for separating aromatic components and non-aromatic components in fuel oil by using a simulated moving bed, comprising a simulated moving bed, an adsorbent and a desorbent, wherein the simulated moving bed comprises one or more adsorption towers, each of which is filled with the adsorbent, the fuel oil comprises aromatic components and non-aromatic components, and the desorbent comprises an alkane mixture and aromatics, wherein the alkane mixture comprises cycloalkanes and chain alkanes.

14. The system according to claim 13, wherein: The paraffins include normal paraffins and isoparaffins.

15. The system of claim 14, wherein: Based on the weight of the alkane mixture, the alkane mixture contains 30%-70% of cycloalkanes and 30%-70% of chain alkanes. Preferably, the alkane mixture contains 30%-70% of cycloalkanes, 5%-50% of isoalkanes and 20-60% of normal alkanes. More preferably, the alkane mixture contains 40%-65% of cycloalkanes, 10%-35% of isoalkanes and 25%-50% of normal alkanes.

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