Method for separating C9+ heavy aromatics from heavy gasoline fraction and producing light aromatics

Abstract

The present invention relates to a method for separating C9+ heavy aromatics from a heavy gasoline fraction and producing light aromatics, the method comprising: (1) passing the heavy gasoline fraction into the middle of an extractive distillation tower, passing an extractive distillation solvent into the upper part of the extractive distillation tower, and after extractive distillation, discharging raffinate oil containing C9+ non-aromatics from the top of the tower, and discharging a rich solvent rich in C9+ aromatics from the bottom of the tower, wherein the extractive distillation solvent is a mixture of γ-butyrolactone and γ-valerolactone; (2) performing a first water wash on the raffinate oil in a first water washing tower to obtain C9+ non-aromatics and a first aqueous solvent; (3) performing a second water wash on the rich solvent in a second water washing tower to obtain C9+ heavy aromatics and a second aqueous solvent; (4) mixing the first aqueous solvent and the second aqueous solvent, contacting with an aromatization catalyst in the presence of hydrogen to perform an aromatization reaction, and obtaining light aromatics. The method of the present invention has a good separation effect on C9+ heavy aromatics, and can simultaneously produce light aromatics, thereby realizing the combination of separation and reaction.

Description

Technical Field

[0001] The present invention relates to a method for separating aromatic hydrocarbons from a hydrocarbon mixture by extractive distillation, and more particularly to a method for separating aromatic hydrocarbons and non-aromatic hydrocarbons from gasoline C9-C10 fractions by solvent extractive distillation and producing light aromatic hydrocarbons. Background Art

[0002] With the continuous increase in environmental protection efforts, on the one hand, the product standards for automotive gasoline continue to upgrade, the aromatic content and 50% evaporation temperature of gasoline continue to decrease, and the proportion of C9+ heavy aromatics that can be added to gasoline gradually decreases; on the other hand, in the chemical industry, aromatic products are important basic organic chemical raw materials for social development and are widely used in many fields such as polyester, chemical fiber, rubber, medicine and fine chemicals, with strong market demand. Therefore, it is of great significance to use appropriate separation methods to separate C9+ aromatics in gasoline fractions with low energy consumption and high yield, which can not only meet the requirements of the new gasoline standards, but also expand aromatic resources.

[0003] Sulfolane is the most commonly used solvent for the extraction and separation of C6-C8 aromatics. However, its solubility for C9+ aromatics is significantly reduced, making it unsuitable for the separation of heavy aromatics. Conventional aromatic extraction solvents such as tetraethylene glycol and N-methylpyrrolidone have strong solubility, but their selectivity for heavy aromatics is poor.

[0004] CN105503500B discloses a combined extractant and separation method for methyl ethyl benzene by extractive distillation of C9 aromatics, wherein palmitate and thiocyanate or / and acetate are used as combined extractants, a C9 aromatic mixture is subjected to extractive distillation, m- and p-methyl ethyl benzene are produced from the top of the tower, and the rich solvent in the bottom of the tower is recovered by solvent to obtain o-methyl ethyl benzene and mesitylene. The process does not involve the separation of C9 aromatics and non-aromatics.

[0005] CN101514136A discloses a method for extracting and rectifying coking crude benzene to produce high-purity toluene. The extractant used is at least one of cyclopentane, glycols, N-methylpyrrolidone, α-pyrrolidone, ethylene glycol, N,N-dimethylformamide, dimethyl sulfoxide, γ-butyrolactone and monoethanolamine. The method is to cut the coking crude benzene fraction to obtain a toluene fraction, and extract the toluene product after extracting and removing light and heavy hydrocarbons. The raw material fraction targeted by the separation method is relatively light and cannot be directly applied to the separation of heavy aromatics.

[0006] CN107586241A discloses a method for producing aromatic hydrocarbons from lactone compounds, comprising the steps of contacting the lactone compound with a composite metal oxide catalyst under aromatization conditions in the presence of water to produce aromatic hydrocarbons. The composite metal oxide catalyst used is selected from ZrO 2 and selected from MnO 2 、MoO 3, WO 3 ,La 2 O 3 and CeO 2 A composite oxide of one or more oxides. Summary of the invention

[0007] The purpose of the present invention is to provide a method for separating C9+ heavy aromatics from a heavy gasoline fraction and producing light aromatics. The method can simultaneously separate C9+ heavy aromatics and produce light aromatics, and is simple to operate and environmentally friendly.

[0008] In order to achieve the above object, the present invention provides a method for separating C9+ heavy aromatics from a heavy gasoline fraction and producing light aromatics, the method comprising:

[0009] (1) passing the heavy gasoline fraction into the middle part of an extractive distillation tower, passing an extractive distillation solvent into the upper part of the extractive distillation tower, and after extractive distillation, discharging the raffinate oil containing C9+ non-aromatic hydrocarbons from the top of the tower, and discharging the rich solvent rich in C9+ aromatic hydrocarbons from the bottom of the tower, wherein the extractive distillation solvent is a mixture of γ-butyrolactone and γ-valerolactone;

[0010] (2) washing the raffinate oil with water in a first water washing tower to obtain C9+ non-aromatic hydrocarbons and a first aqueous solvent;

[0011] (3) subjecting the rich solvent to a second water washing in a second water washing tower to obtain C9+ heavy aromatics and a second aqueous solvent;

[0012] (4) The first aqueous solvent and the second aqueous solvent are mixed and contacted with an aromatization catalyst in the presence of hydrogen to carry out an aromatization reaction to obtain light aromatics.

[0013] The method of the present invention uses a mixture of γ-butyrolactone and γ-valerolactone as an extractive distillation solvent to separate the heavy gasoline fraction by extractive distillation, which has the following advantages:

[0014] (1) The purity and yield of C9+ heavy aromatics and non-aromatics obtained by extractive distillation are high;

[0015] (2) The water washing method is used to separate the extractant from aromatic hydrocarbons and non-aromatic hydrocarbons, which has lower energy consumption than vacuum distillation;

[0016] (3) The extractive distillation solvent is not recycled, but is used as a raw material for producing light aromatics, thereby realizing the combination of extractive distillation separation of aromatics and solvent for aromatization reaction.

[0017] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present invention but do not constitute a limitation of the present invention. In the accompanying drawings:

[0019] Figure 1 It is a schematic diagram of the process flow for separating C9+ heavy aromatics and producing light aromatics provided by the present invention.

[0020] Description of Reference Numerals

[0021] 1-First pipeline 2-Second pipeline 3-Third pipeline

[0022] 4-Fourth pipeline 5-Fifth pipeline 6-Sixth pipeline

[0023] 7-the seventh pipeline 8-the eighth pipeline 9-the ninth pipeline

[0024] 10-10th pipeline 11-11th pipeline 12-12th pipeline

[0025] 101- Extraction distillation tower 102- First water washing tower 103- Second water washing tower

[0026] 104-Aromatization reactor 105-Storage tank DETAILED DESCRIPTION

[0027] The specific implementation of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the present invention, and is not used to limit the present invention.

[0028] The method of the present invention uses a mixture of γ-butyrolactone and γ-valerolactone as an extractive distillation solvent to separate C9+ heavy aromatics and non-aromatics from a heavy gasoline fraction. The extractive distillation solvent used has good solubility and selectivity for C9+ heavy aromatics, and does not contain heteroatoms such as S and N in its molecule, has low toxicity, high thermal stability, and is environmentally friendly. In view of its low boiling point, the present invention no longer recycles the solvent in the rich solvent, but washes the obtained raffinate oil and the rich solvent with water respectively to separate the C9+ non-aromatics and solvent in the raffinate oil, separate the C9+ heavy aromatics and solvent in the rich solvent, and use the water-containing solvent obtained by washing with water to prepare light aromatics (benzene, toluene and xylene), so that light aromatics can be produced from the used water-containing solvent while separating the C9+ heavy aromatics in the raw material, and the obtained C9+ heavy aromatics have high purity and yield and low energy consumption.

[0029] In a specific embodiment of the present invention, in step (1), the mass ratio of the content of γ-butyrolactone to the content of γ-valerolactone in the extractant can vary within a large range, for example, it can be 1-9:9-1, preferably 1-8:8-1.

[0030] In a specific embodiment of the present invention, in step (1), the mass ratio of the extractive distillation solvent to the heavy gasoline fraction (solvent ratio) can vary within a large range, for example, it can be (5-15):1, preferably (5-10):1; the theoretical plate number of the extractive distillation tower is preferably 10-45, more preferably 20-40; the operating conditions of the solvent extraction tower may include: the bottom temperature is 200-240°C, and the top pressure is 80-150 kPa; preferably, the bottom temperature is 200-230°C, and the top pressure is 80-110 kPa.

[0031] In a specific embodiment of the present invention, in step (1), the reflux ratio of the upper part of the extractive distillation tower, that is, the mass ratio of the material refluxed into the tower from the upper part of the extractive distillation tower to the material discharged from the top of the tower is preferably 0.4-1.0, the inlet temperature of the heavy gasoline fraction is preferably 40-85°C, and the inlet temperature of the extractive distillation solvent is preferably 90-130°C; preferably, the reflux ratio is 0.4-0.8, the inlet temperature of the heavy gasoline fraction is 60-85°C, and the inlet temperature of the extractive distillation solvent is 90-120°C.

[0032] In a specific embodiment of the present invention, in step (2), the theoretical plate number of the first water washing tower is preferably 4 to 20, more preferably 8 to 15; the tower top pressure is preferably 80 to 500 kPa, more preferably 100 to 300 kPa; the mass ratio of water to the raffinate oil is preferably (0.1 to 0.5): 1; the temperature of the first water washing is preferably 30 to 60° C. The C9+ non-aromatic hydrocarbons obtained by the first water washing can be used to produce solvent oil or white oil.

[0033] In a specific embodiment of the present invention, in step (3), the theoretical plate number of the second water washing tower is preferably 4 to 25, more preferably 10 to 20; the tower top pressure is preferably 80 to 600 kPa, more preferably 100 to 300 kPa; the mass ratio of water to the rich solvent is preferably (0.2 to 1.0): 1; the temperature of the second water washing is preferably 30 to 60° C. The C9+ heavy aromatics obtained by the second water washing can be sent to the disproportionation unit of the aromatics complex to produce light aromatics.

[0034] In a specific embodiment of the present invention, in step (4), the aromatization catalyst is a solid acid catalyst; more preferably, the solid acid catalyst contains ZrO 2 and an active component selected from sulfuric acid, MnO 2 、MoO 3 and WO 3 One or more of the ZrO 2The mass ratio of the active component to the active component can vary within a wide range, preferably (0.2-2.0):1, more preferably (0.6-1.5):1.

[0035] In a specific embodiment of the present invention, in step (4), the conditions of the aromatization reaction include: a reaction temperature of 200 to 500°C, a hydrogen pressure of 0.1 to 3 MPa, a mass space velocity of the raw material of 0.3 to 5 hours -1 Preferably, the reaction temperature is 350-500°C, the hydrogen pressure is 0.3-2.0 MPa, and the mass space velocity of the raw material is 0.5-3 hours. -1 .

[0036] According to the present invention, the raw material containing C9+ heavy aromatics is a C9-C10 fraction of gasoline, and the gasoline may include but is not limited to one or more of catalytic cracking gasoline, LTA (catalytic cracking diesel hydrogenation-catalytic cracking combined high-yield aromatics technology) gasoline, DCC (deep catalytic cracking) gasoline, reformed gasoline and cracking hydrogenated gasoline. The content of C9+ heavy aromatics in the heavy gasoline fraction can vary within a large range, for example, 20 to 80% by mass.

[0037] In a specific embodiment of the present invention, in step (4): the content of the extractive distillation solvent in the aqueous solvent obtained by mixing the first aqueous solvent and the second aqueous solvent is preferably 45 to 85% by mass.

[0038] In a specific embodiment of the present invention, step (4) further comprises: subjecting the reaction product of the aromatization reaction to distillation treatment, obtaining a light aromatics-rich liquid at the top of the tower, and obtaining a bottom liquid containing C9+ heavy aromatics and an extractive distillation solvent at the bottom of the tower. Preferably, the bottom liquid is subjected to a third water wash to obtain C9+ heavy aromatics and a third aqueous solvent, the C9+ heavy aromatics can be fractionated and returned to the C9-C10 feed tank, and the third aqueous solvent is returned to the aromatization reactor to continue the reaction.

[0039] like Figure 1 As shown, in a preferred embodiment of the present invention, a method comprising the following steps is used to separate C9+ heavy aromatics from a heavy gasoline fraction and produce light aromatics:

[0040] A mixture of γ-butyrolactone and γ-valerolactone is used as an extractive distillation solvent and is introduced into the upper part of an extractive distillation tower 101 through a first pipeline 1. A heavy gasoline fraction (i.e., a C9-C10 fraction) is introduced into the middle part of the extractive distillation tower 101 through a second pipeline 2. After extractive distillation, a mixture of C9-C10 non-aromatic hydrocarbons and solvent obtained at the top of the tower enters a storage tank 105. After condensation, water is separated, a part of which is returned to the upper part of the extractive distillation tower 101 through a third pipeline 3 as reflux, and the rest enters the lower part of a first water washing tower 102 through a fourth pipeline 4. Fresh water enters the upper part of the first water washing tower 102 through a fifth pipeline 5. The C9-C10 non-aromatic hydrocarbons obtained after the first water washing are discharged through a sixth pipeline 6. The first aqueous solvent obtained at the bottom of the first water washing tower 102 enters a seventh pipeline 7. The rich solvent containing C9-C10 aromatics obtained at the bottom of the extractive distillation tower 101 is sent to the lower part of the second water washing tower 103 through the eighth pipeline 8 after heat exchange, and fresh water enters the upper part of the second water washing tower 103 through the ninth pipeline 9. The C9-C10 aromatics obtained after water washing are discharged from the device through the tenth pipeline 10. The second aqueous solvent obtained at the bottom of the tower enters the seventh pipeline 7 through the eleventh pipeline 11, mixes with the first aqueous solvent, and then enters the aromatization reactor 104, contacts with the aromatization catalyst for aromatization reaction, and the product rich in light aromatics obtained by the aromatization reaction is discharged through the twelfth pipeline 12.

[0041] The present invention is further illustrated by the following examples, but the present invention is not limited thereto.

[0042] In the present invention, the selectivity of the extractive distillation solvent for the separated aromatics and non-aromatics is characterized by relative volatility (α), which is defined as:

[0043] α=(Y 2 / X 2 ) / (Y 1 / X 1 ) (1)

[0044] In formula (1), X 1 and X 2 Respectively represent the mass fraction of component 1 and component 2 in the liquid phase, Y 1 and Y 2 Respectively represent the mass fractions of component 1 and component 2 in the gas phase, where component 1 is aromatic hydrocarbons and component 2 is non-aromatic hydrocarbons. The larger the α value, the easier the extractive distillation process is, and a higher purity product can be obtained with fewer distillation plates, less reflux, and less solvent ratio.

[0045] Example 1

[0046] This example investigates the separation performance of C9-C10 aromatics / non-aromatics using a mixture of γ-butyrolactone / γ-valerolactone as an extractive distillation solvent.

[0047] Isopropylbenzene was selected as a model compound of aromatic hydrocarbons, and n-decane was selected as a model compound of non-aromatic hydrocarbons. A mixture of γ-butyrolactone / γ-valerolactone with a mass ratio of 1:1 was prepared as an extractive distillation solvent, and a mixture of isopropylbenzene and n-decane of a certain composition was used as a raw material. The raw material was added to the above-mentioned extractive distillation solvent, and a certain mass ratio of the extractive distillation solvent to the raw material (solvent ratio) was controlled. The mixture was shaken and evenly mixed, heated to 100°C, and allowed to stand for 30 minutes. The gas phase composition was analyzed by gas chromatography, and the relative volatility α of n-decane to isopropylbenzene was calculated by formula (1), wherein n-decane was component 2 and isopropylbenzene was component 1. The results measured with different raw materials and solvent ratios are shown in Table 1.

[0048] Table 1

[0049]

[0050] As can be seen from Table 1, the mixture of γ-butyrolactone / γ-valerolactone as an extractive distillation solvent has high selectivity for C9-C10 aromatic hydrocarbons. When the solvent ratio is between 5 and 10, the selectivity is significantly improved by increasing the solvent ratio. When the solvent ratio is greater than 10, the selectivity tends to be flat with the change of the solvent ratio.

[0051] Example 2

[0052] This example investigates the separation performance of C9-C10 aromatics / non-aromatics using a mixture of γ-butyrolactone / γ-valerolactone as an extractive distillation solvent.

[0053] A mixture of γ-butyrolactone / γ-valerolactone in a mass ratio of 3:7 was prepared as an extractive distillation solvent, and a mixture of cumene and n-decane of a certain composition was used as a raw material. The raw material was added to the above-mentioned extractive distillation solvent, and a certain solvent ratio was controlled. The mixture was shaken and evenly mixed, and the temperature was raised to 100°C. The mixture was allowed to stand for 30 minutes. The gas phase composition was analyzed by gas chromatography, and the relative volatility α of n-decane to cumene was calculated by formula (1). The results measured with different raw material compositions and solvent ratios are shown in Table 2.

[0054] Table 2

[0055]

[0056] Example 3

[0057] This example investigates the separation performance of C9-C10 aromatics / non-aromatics using a mixture of γ-butyrolactone / γ-valerolactone as an extractive distillation solvent.

[0058] A mixture of γ-butyrolactone / γ-valerolactone in a mass ratio of 7:3 was prepared as an extractive distillation solvent, and a mixture of cumene and n-decane of a certain composition was used as a raw material. The raw material was added to the above-mentioned extractive distillation solvent, and a certain solvent ratio was controlled. The mixture was shaken and evenly mixed, and the temperature was raised to 100°C. The mixture was allowed to stand for 30 minutes. The gas phase composition was analyzed by gas chromatography, and the relative volatility α of n-decane to cumene was calculated by formula (1). The results measured with different raw material compositions and solvent ratios are shown in Table 3.

[0059] Table 3

[0060]

[0061] Example 4

[0062] This example follows Figure 1 The process flow shown separates aromatics and non-aromatics in the C9-C10 fraction of catalytic cracking gasoline and produces light aromatics.

[0063] A mixture of γ-butyrolactone / γ-valerolactone with a mass ratio of 1:1 was used as the extraction distillation solvent, and the raw material composition is shown in Table 4. The aromatization catalyst is ZrO 2 with WO 3 The solid acid catalyst is composed of ZrO 2 with WO 3 The mass ratio is 1.4:1. The preparation method of the solid acid catalyst is as follows: weigh a certain amount of zirconium oxychloride, prepare it into an aqueous solution with a concentration of 20% by mass, then add ammonia water to make the solution alkaline, and the zirconium oxychloride is decomposed into a hydrated zirconium oxide precipitate, filtered, and the obtained filter cake is dried at 120°C for 4 hours, and calcined at 450°C for 4 hours to obtain zirconium oxide. Take 26.2 grams of zirconium oxide, immerse it in 100 grams of 20% by mass ammonium metatungstate solution for 24 hours, then dry it at 120°C for 6 hours and calcine it at 500°C for 4 hours. The operating conditions of each tower and aromatization reactor are shown in Table 5, the separation and reaction results are shown in Table 6, and the conversion rate of the lactone in the aromatization reaction is 99% by mass.

[0064] Table 4

[0065]

[0066] Table 5

[0067]

[0068]

[0069] Table 6

[0070] project Example 4 Comparative Example 4 C9~C10 aromatics Purity, mass% 99.5 91.5 Yield, mass % 98.6 92.1 C9~C10 non-aromatic hydrocarbons Aromatic content, mass % 0.9 5.3 Yield, mass % 99.7 94.3 Light aromatics composition Benzene, mass% 6 -- Toluene, mass% 32 -- Xylene, mass% 28 -- C9+ aromatics, mass% 4 -- Non-aromatic hydrocarbons, mass % 30 --

[0071] As can be seen from the above, the method of the present invention can not only separate C9-C10 aromatics from the C9-C10 fraction of gasoline, but also prepare light aromatics from the used water-containing extraction distillation solvent, and the obtained C9-C10 aromatics and C9-C10 non-aromatics have high purity and yield and low energy consumption.

[0072] Comparative Example 1

[0073] This example investigates the separation performance of C9-C10 aromatics / non-aromatics using γ-butyrolactone as the extractive distillation solvent.

[0074] A mixture of isopropylbenzene and n-decane of a certain composition is used as a raw material. The raw material is added into γ-butyrolactone, a certain solvent ratio is controlled, the mixture is shaken and evenly mixed, the temperature is raised to 100°C, and the mixture is allowed to stand for 30 minutes. The gas phase composition is analyzed by gas chromatography, and the relative volatility α of n-decane to isopropylbenzene is calculated by formula (1). The results obtained by using different raw material compositions and solvent ratios are shown in Table 7.

[0075] Table 7

[0076]

[0077] Comparative Example 2

[0078] This example investigates the separation performance of C9-C10 aromatics / non-aromatics using γ-valerolactone as the extractive distillation solvent.

[0079] A mixture of isopropylbenzene and n-decane solution of a certain composition is used as a raw material, and the raw material is added into γ-valerolactone, and a certain solvent ratio is controlled. The mixture is shaken and evenly mixed, and the temperature is raised to 100°C, and the mixture is allowed to stand for 30 minutes. The gas phase composition is analyzed by gas chromatography, and the relative volatility α of n-decane to isopropylbenzene is calculated by formula (1). The results obtained by using different raw material compositions and solvent ratios are shown in Table 8.

[0080] Table 8

[0081]

[0082]

[0083] It can be seen from Tables 7 and 8 that the selectivity of γ-butyrolactone and γ-valerolactone alone as extractive distillation solvents for C9-C10 aromatic hydrocarbons is lower than the selectivity of the mixture of γ-butyrolactone / γ-valerolactone as an extractive distillation solvent for C9-C10 aromatic hydrocarbons.

[0084] Comparative Example 3

[0085] The separation performance of other commonly used organic solvents as shown in Table 9 for C9-C10 aromatic / non-aromatic hydrocarbons as extractive distillation solvents was investigated.

[0086] A mixture of n-decane and isopropylbenzene with a n-decane content of 47.84 mass % was used as a raw material, and the raw material was added to different distillation solvents with a solvent ratio of 15, and the mixture was shaken and evenly mixed, heated to 100° C., and allowed to stand for 30 min. The gas phase composition was analyzed by gas chromatography, and the relative volatility α of n-decane to isopropylbenzene was calculated by formula (1). The results are shown in Table 9. As can be seen from Table 9, the relative volatility of other commonly used organic solvents is relatively low, indicating that their selectivity for C9-C10 aromatics is low.

[0087] Table 9

[0088] Solvents Relative volatility α Ethylene carbonate 0.99 Diethyl Sebacate 1.01 Dimethyl phthalate 2.47 Dibutyl phthalate 1.16 Sulfolane 1.96 dimethylformamide 1.50

[0089] Comparative Example 4

[0090] Using sulfolane as solvent, the raw material described in Example 4 is separated by a conventional extractive distillation-solvent recovery process. The operation method is as follows: the extractive distillation solvent is passed into the upper part of the extractive distillation tower, and the extractive distillation raw material is passed into the middle part of the extractive distillation tower. After extractive distillation, C9-C10 non-aromatic hydrocarbons are discharged from the top of the tower, and the rich solvent containing C9-C10 aromatic hydrocarbons is discharged from the bottom of the tower and enters the middle part of the solvent recovery tower. After vacuum distillation, C9-C10 aromatic hydrocarbons are discharged from the top of the tower, and the lean solvent is discharged from the bottom of the tower and returned to the extractive distillation tower for reuse. The operating conditions of each tower are shown in Table 10, and the separation results are shown in Table 6.

[0091] As can be seen from Table 6, using sulfolane as the solvent, the purity and yield of C9-C10 aromatics obtained are both low, the energy consumption of vacuum distillation is high in the solvent recovery process, and sulfolane cannot be converted into light aromatics.

[0092] Table 10

[0093] project Comparative Example 4 Extractive distillation tower Theoretical plates 30 Tower top pressure, kPa 14 Solvent ratio 8.0 Reflux ratio 0.7 Solvent inlet temperature, °C 88 Bottom temperature, ℃ 140 Solvent recovery tower Bottom temperature, ℃ 189 Reflux ratio 1.0 Tower top pressure, kPa 14

[0094] The preferred embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0095] 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. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0096] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A method for separating C9+ heavy aromatics from a heavy gasoline fraction and producing light aromatics, the method comprising: (1) A heavy gasoline fraction is introduced into the middle part of an extractive distillation tower, and an extractive distillation solvent is introduced into the upper part of the extractive distillation tower. After extractive distillation, a raffinate oil containing C9+ non-aromatic hydrocarbons is discharged from the top of the tower, and a rich solvent rich in C9+ aromatic hydrocarbons is discharged from the bottom of the tower. The extractive distillation solvent is a mixture of γ-butyrolactone and γ-valerolactone. The mass ratio of the extractive distillation solvent to the heavy gasoline fraction is (5-15):

1. The heavy gasoline fraction is a C9-C10 fraction of gasoline. (2) washing the raffinate oil in a first water washing tower to obtain C9+ non-aromatic hydrocarbons and a first aqueous solvent; (3) subjecting the rich solvent to a second water wash in a second water wash tower to obtain C9+ heavy aromatics and a second aqueous solvent; (4) The first aqueous solvent and the second aqueous solvent are mixed and contacted with an aromatization catalyst in the presence of hydrogen to carry out an aromatization reaction to obtain light aromatics.

2. The method according to claim 1, wherein: In step (1), the mass ratio of the γ-butyrolactone to the γ-valerolactone in the extractive distillation solvent is 1-9:9-1.

3. The method according to claim 1, wherein: In step (1), the number of theoretical plates of the extractive distillation tower is 10 to 45; The operating conditions of the extractive distillation tower include: the tower bottom temperature is 200-240° C., and the tower top pressure is 80-150 kPa.

4. The method according to claim 1 or 3, wherein: In step (1), the reflux ratio of the upper part of the extractive distillation tower is 0.4-1.0, the inlet temperature of the heavy gasoline fraction is 40-85°C, and the inlet temperature of the extractive distillation solvent is 90-130°C.

5. The method according to claim 1, wherein: In step (2), the theoretical plate number of the first water washing tower is 4-20; the tower top pressure is 80-500 kPa; the mass ratio of water to the raffinate oil is (0.1-0.5):1; and the temperature of the first water washing is 30-60°C.

6. The method according to claim 1, wherein: In step (3), the theoretical plate number of the second water washing tower is 4-25; the tower top pressure is 80-600 kPa; the mass ratio of water to the rich solvent is (0.2-1.0):1; and the temperature of the second water washing is 30-60°C.

7. The method according to claim 1, wherein: In step (4), the aromatization catalyst is a solid acid catalyst; The solid acid catalyst contains ZrO2 and an active component, wherein the active component is selected from one or more of sulfuric acid, MnO2, MoO3 and WO3, and the mass ratio of ZrO2 to the active component is (0.2~2.0):

1.

8. The method according to claim 1, wherein: In step (4), the conditions of the aromatization reaction include: reaction temperature of 200-500°C, hydrogen pressure of 0.1-3 MPa, mass space velocity of the raw material of 0.3-5 h -1 .

9. The method according to claim 1, wherein: The content of C9+ heavy aromatics in the heavy gasoline fraction is 20-80% by mass, and the gasoline is one or more of catalytic cracking gasoline, catalytic cracking diesel hydrogenation-catalytic cracking combined high-yield aromatics technology gasoline, DCC gasoline, reformed gasoline and cracking hydrogenated gasoline.

10. The method according to claim 1, wherein: In step (4), the content of the extractive distillation solvent in the aqueous solvent obtained by mixing the first aqueous solvent and the second aqueous solvent is 45-85% by mass.

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