Compositions, deep eutectic solvents, methods of making and using the same, and methods of extracting aromatics from petroleum distillates

Abstract

The present application relates to the field of petroleum distillate separation, discloses a kind of composition, eutectic solvent and its preparation method and application, the method for extracting and separating aromatic hydrocarbon in petroleum distillate.A kind of composition, the composition includes 1-ethyl-3-methyl imidazole halogen salt and 1-vinylimidazole;Wherein, the molar ratio of 1-ethyl-3-methyl imidazole halogen salt and 1-vinylimidazole is 0.2-5:1.The eutectic solvent prepared by the composition disclosed in the present application is used for extracting and separating aromatic hydrocarbon in petroleum distillate, and there is basically no solvent residue in the raffinate obtained, the subsequent aromatic hydrocarbon separation method is simple, the extraction effect is obviously improved;And compared with the existing commonly used extraction solvent, it has higher aromatic hydrocarbon selectivity.

Description

Technical Field

[0001] The present invention relates to the field of petroleum fraction separation, and in particular to a composition, a deep eutectic solvent, a preparation method and application thereof, and a method for extracting and separating aromatic hydrocarbons in petroleum fractions. Background Art

[0002] my country's petrochemical industry is experiencing a dramatic increase in demand for high-quality fuels and chemical feedstocks. Separating aromatic / alkane mixtures is one of the most critical and challenging processes in the petrochemical industry. This is because many aromatics and alkanes have similar physical and chemical properties, especially when aromatics and alkanes with similar carbon numbers have very similar boiling points. Furthermore, mixtures of aromatics and alkanes tend to form azeotropes, making them ineffective for separation by conventional distillation.

[0003] Solvent extraction is currently the most commonly used process for separating aromatic and alkane systems. It primarily utilizes the different solubilities of various components in the aromatic extraction feedstock in organic solvents to separate aromatics from alkanes. Solvent extraction is highly efficient for separating aromatics, and different process routes are available depending on the extraction solvent used. Among these, novel solvents such as ionic liquids and deep eutectic solvents, which offer structurally designable properties, are considered one of the most promising areas for development in the field of extraction and separation due to their excellent physical and chemical properties. One of the earliest researchers to conduct research on ionic liquid extraction was Rogers (Rogers RD, Seddon KR. Ionic liquids—Solvents of the future? [J]. Science, 2003, 302(5646):792-793) at the University of Alabama in the United States. They used [BMIM]PF6 to extract aromatic compounds such as toluene, aniline, benzoic acid, and chlorobenzene from water and studied the partition coefficients of various extracts in ionic liquids. Subsequently, many universities and research institutions at home and abroad began to explore the effects of new solvents such as ionic liquids and low eutectic solvents in the separation of aromatics and alkanes.

[0004] Deep eutectic solvents (DESs) are typically eutectic mixtures formed by hydrogen bonding between hydrogen bond donors (HBDs) and hydrogen bond acceptors (HBAs) in a specific stoichiometric ratio. They are considered a new type of ionic liquid due to their simple preparation, low vapor pressure, good solubility, environmental friendliness, reusability, and designability. Since their initial description in 2003, they have been widely used in fields such as electrochemistry, energy, and extraction solvents.

[0005] In 2012, Kareem et al. (Kareem MA, Mjalli FS, Hashim MA, et al. Liquid-liquid equilibria for the ternary system (phosphonium-based deep eutectic solvent-benzene-hexane) at different temperatures: A new solvent introduced [J]. Fluid Phase Equilibria, 2012, 314(none):52-59.) first used DES (TBPB+EG) to extract and separate aromatics from an aromatic-aliphatic mixture. Their results showed that DES could effectively separate benzene and hexane mixtures. They also found that the hydrogen bond donor (EG) played a primary role in the extraction process, while the hydrogen bond acceptor (TBPB) played a secondary role. DES achieved similar separation results to organic solvents, but it was difficult to achieve both high extraction efficiency and high selectivity.

[0006] Inspired by Kareem's work, a growing number of researchers have begun investigating the extraction and separation capabilities of various DESs for aromatic hydrocarbons. While reports on DESs for the separation of aromatic-alkane systems indicate high selectivity for aromatics, DESs also suffer from weak solubility for aromatic compounds, resulting in generally low distribution coefficients for aromatics. This also aligns with the principle that both selectivity and distribution coefficient cannot be increased simultaneously: when one is too high, the other is relatively low, thus limiting the application of DESs. Current research and development of DESs focuses on maintaining high selectivity while maximizing their solubility for aromatics.

[0007] The development of new solvent systems such as ionic liquids and low eutectic solvents suitable for the separation of aromatics in petroleum products of different fractions has certain economic value and social significance for improving the quality and efficiency of aromatics extraction technology and expanding the production of aromatics raw materials and products. Summary of the Invention

[0008] The present invention aims to overcome the difficulty of achieving both high extraction efficiency and high selectivity with deep eutectic solvents in the prior art. The present invention provides a composition, a deep eutectic solvent, a preparation method and application thereof, and a method for extracting and separating aromatic hydrocarbons from petroleum fractions. The deep eutectic solvent prepared from the composition of the present invention is used to extract and separate aromatic hydrocarbons from petroleum fractions. The resulting raffinate oil is essentially free of solvent residue, simplifying the subsequent aromatic hydrocarbon separation process and significantly improving the extraction efficiency. Furthermore, the composition exhibits higher aromatic hydrocarbon selectivity than conventional extraction solvents.

[0009] In order to achieve the above object, the present invention provides a composition in one aspect, which comprises 1-ethyl-3-methylimidazolium halide and 1-vinylimidazole; wherein the molar ratio of 1-ethyl-3-methylimidazolium halide to 1-vinylimidazole is 0.2-5:1.

[0010] The second aspect of the present invention provides a deep eutectic solvent, the solvent includes 1-ethyl-3-methylimidazole halide and 1-vinyl imidazole connected by hydrogen bonds. In the prior art, sulfolane is usually used as an extraction solvent, but because the boiling point of sulfolane is within the boiling range of kerosene and diesel fractions, it is difficult to recover the solvent by distillation, resulting in higher separation energy consumption; sulfolane will partially decompose at the same time, producing sulfur-containing corrosive substances, which has a certain impact on the long-term use of the device. The deep eutectic solvent of the structure of the present invention significantly overcomes the defects of sulfolane, has a wide liquid temperature range (-55 to 250 ° C), a large density difference with petroleum fractions, an extremely low saturated vapor pressure, and does not contain sulfur elements. It is applied to extract and separate aromatic hydrocarbons in petroleum fractions, can extract petroleum fractions within a wide temperature range, and is easy to separate phases with petroleum fractions, and there is substantially no solvent residue in the raffinate obtained, and the subsequent aromatic separation method is simple, significantly improves the extraction effect, and greatly saves processing costs.

[0011] A third aspect of the present invention provides a method for preparing a deep eutectic solvent, the method comprising: obtaining the deep eutectic solvent by subjecting the composition described in the first aspect to a melt reaction.

[0012] A fourth aspect of the present invention provides use of the deep eutectic solvent described in the second aspect or the deep eutectic solvent prepared by the method described in the third aspect in the extraction and separation of aromatic hydrocarbons.

[0013] A fifth aspect of the present invention provides a method for extracting and separating aromatic hydrocarbons from petroleum fractions, the method comprising:

[0014] (1) contacting the petroleum fraction with the deep eutectic solvent in reverse order to obtain a raffinate oil and an extracted oil containing the deep eutectic solvent and aromatic hydrocarbons;

[0015] (2) separating the extracted oil containing the deep eutectic solvent and aromatic hydrocarbons in step (1) to obtain aromatic hydrocarbons and the deep eutectic solvent;

[0016] Wherein, the low eutectic solvent in step (1) is the low eutectic solvent described in the second aspect or the low eutectic solvent prepared by the method described in the third aspect.

[0017] Through the above technical solution, the beneficial effects of the present invention include:

[0018] The deep eutectic solvent prepared from the specific composition of the present invention is used for extracting and separating aromatic hydrocarbons from petroleum fractions. The obtained raffinate oil has substantially no solvent residue, the subsequent aromatic hydrocarbon separation method is simple, the extraction effect is significantly improved, and the processing cost is greatly saved. Compared with existing commonly used extraction solvents, the low eutectic solvent has higher aromatic hydrocarbon selectivity and has good application prospects in the field of aromatic hydrocarbon separation from petroleum fractions.

[0019] The deep eutectic solvent of the present invention has the characteristics of simple preparation process, low corrosion to equipment, easy recovery, and environmental protection, and can provide a separation solution for the separation and utilization of petroleum distillate components. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is the nuclear magnetic resonance image of the deep eutectic solvent described in Example 1;

[0021] Figure 2 is a DSC graph of the deep eutectic solvent described in Example 1;

[0022] Figure 3 The present invention is a process flow chart for extracting and separating aromatic hydrocarbons from petroleum fractions.

[0023] Description of Reference Numerals

[0024] exist Figure 3 middle,

[0025] 1. Extraction tower; 2. Solvent recovery tower; 3. Deep eutectic solvent;

[0026] 4. Petroleum fractions; 5. Raffinate oil; 6. Extracted oil containing deep eutectic solvents and aromatics;

[0027] 7. Heat exchanger; 8. Aromatic components; 9. Reboiler. DETAILED DESCRIPTION

[0028] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0029] In the description of the present invention, it should be understood that the terms "top", "bottom", etc. indicating orientation or positional relationships are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they should not be understood as limitations on the present invention.

[0030] In the present invention, unless otherwise specified, the "tower top pressure" refers to absolute pressure.

[0031] One aspect of the present invention provides a composition, comprising 1-ethyl-3-methylimidazolium halide and 1-vinylimidazole; wherein the molar ratio of the 1-ethyl-3-methylimidazolium halide to the 1-vinylimidazole is 0.2-5:1.

[0032] During the research process, the inventors found that the composition uses 1-ethyl-3-methylimidazolium halide and 1-vinylimidazole, and controls the molar ratio of 1-ethyl-3-methylimidazolium halide to 1-vinylimidazole to be within the range of 0.2-5:1, which is conducive to preparing the deep eutectic solvent described in the second aspect of the present invention. When the molar ratio of 1-ethyl-3-methylimidazolium halide to 1-vinylimidazole is lower or higher than the range described in the present invention, since a stable and uniform hydrogen bond network cannot be formed between the molecules, it does not reach the deep eutectic solvent described in the present invention, and is only equivalent to a mixture of two solid salts.

[0033] In the present invention, the molar ratio of 1-ethyl-3-methylimidazolium halide to 1-vinylimidazole is 0.2-5:1, for example, 0.2:1, 0.5:1, 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1, 5:1, and any value in the range formed by any two of these values, preferably 1-3:1. This preferred embodiment is more conducive to obtaining the deep eutectic solvent described in the second aspect of the present invention.

[0034] According to the present invention, preferably, the 1-ethyl-3-methylimidazolium halide salt is 1-ethyl-3-methylimidazolium chloride or 1-ethyl-3-methylimidazolium bromide.

[0035] A second aspect of the present invention provides a deep eutectic solvent comprising a hydrogen-bonded 1-ethyl-3-methylimidazole halide and 1-vinylimidazole.

[0036] The nuclear magnetic resonance spectrum shows that the chemical shifts of H on the hydrogen bond donor and the hydrogen bond acceptor are shifted, indicating that a hydrogen bond interaction occurs between the hydrogen bond acceptor 1-ethyl-3-methylimidazolium halide and the hydrogen bond donor 1-vinylimidazole (abbreviated as 1-Vim). The solvent of the structure described in the present invention has been obtained, which can be referred to Figure 1 .

[0037] The schematic structural diagram of the solvent of the present invention can be referred to formula (1). Formula (1) is a schematic structural diagram of Example 1 of the present invention (in this case, the molar ratio of 1-ethyl-3-methylimidazole halide to 1-vinylimidazole is 2:1).

[0038]

[0039] Preferably, the 1-ethyl-3-methylimidazolium halide salt is 1-ethyl-3-methylimidazolium chloride or 1-ethyl-3-methylimidazolium bromide.

[0040] In order to further improve the extraction and separation effect, more preferably, the 1-ethyl-3-methylimidazolium halide is 1-ethyl-3-methylimidazolium chloride.

[0041] The deep eutectic solvent provided by the present invention has the characteristic of a wide liquid temperature range, which is beneficial to improving the extraction effect. Preferably, the solvent is liquid in the range of -55 to 250°C.

[0042] The liquidus temperature range of the solvent of the present invention is measured by DSC method. Figure 2 It can be seen that the freezing point of the DES is lower than -55°C.

[0043] The present invention does not particularly limit the preparation method of the above-mentioned deep eutectic solvent, as long as a deep eutectic solvent with the above-mentioned structure can be prepared. In order to further improve the extraction performance of the deep eutectic solvent, the present invention also provides a preparation method of the above-mentioned deep eutectic solvent. The preparation method provided by the present invention has a simple process and is widely applicable.

[0044] A third aspect of the present invention provides a method for preparing a deep eutectic solvent, the method comprising: obtaining the deep eutectic solvent by subjecting the composition described in the first aspect to a melt reaction.

[0045] According to the present invention, preferably, the temperature of the melt reaction is 80-150°C, preferably 100-150°C, for example 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, 130°C, 135°C, 140°C, 145°C, 150°C and any value in the range formed by any two of these values. Adopting this preferred embodiment is further conducive to obtaining the deep eutectic solvent having the structure of the present invention. When the temperature of the melt reaction is higher than the range of the present invention, many side reactions are generated and impurities increase.

[0046] The present invention has a wide range of time for selecting the melting reaction, which is based on obtaining the deep eutectic solvent having the structure of the present invention. Preferably, the melting reaction time is 1-10 hours, preferably 3-5 hours.

[0047] According to the present invention, preferably, the melt reaction is carried out under stirring conditions.

[0048] The present invention has no particular limitation on the stirring time and rate, which can be appropriately selected according to specific circumstances.

[0049] According to a specific embodiment of the present invention, the composition of the first aspect is placed in an oil bath, condensed, refluxed and stirred to obtain a deep eutectic solvent.

[0050] A fourth aspect of the present invention provides use of the deep eutectic solvent described in the second aspect or the deep eutectic solvent prepared by the method described in the third aspect in extracting and separating aromatic hydrocarbons, preferably in extracting and separating aromatic hydrocarbons in petroleum fractions.

[0051] The deep eutectic solvent provided by the present invention can be used to process different raw materials or products in petroleum fractions. Preferably, the petroleum fraction is selected from at least one of gasoline, diesel and kerosene.

[0052] The gasoline, kerosene and diesel provided in the present invention have conventional definitions in the art and are not particularly limited in the present invention.

[0053] Preferably, the diesel is light diesel.

[0054] The light diesel oil mentioned in the present invention refers to diesel oil with a distillation range of 180-380°C.

[0055] A fifth aspect of the present invention provides a method for extracting and separating aromatic hydrocarbons from petroleum fractions, the method comprising:

[0056] (1) contacting the petroleum fraction with the deep eutectic solvent in reverse order to obtain a raffinate oil and an extracted oil containing the deep eutectic solvent and aromatic hydrocarbons;

[0057] (2) separating the extracted oil containing the deep eutectic solvent and aromatic hydrocarbons in step (1) to obtain aromatic hydrocarbons and the deep eutectic solvent;

[0058] Wherein, the low eutectic solvent in step (1) is the low eutectic solvent described in the second aspect or the low eutectic solvent prepared by the method described in the third aspect.

[0059] In the method provided by the present invention, the reverse contact means that the deep eutectic solvent contacts from top to bottom under the influence of gravity, and the petroleum fraction contacts from bottom to top.

[0060] Preferably, the reverse contact in step (1) is carried out in an extraction tower, and raffinate oil is obtained at the top of the tower, and extracted oil containing a low eutectic solvent and aromatic hydrocarbons is obtained at the bottom of the tower.

[0061] The low eutectic solvent provided by the present invention can extract petroleum fractions in a wide temperature range. Preferably, the reverse contact conditions in step (1) include: a temperature of 30-100°C.

[0062] According to the present invention, preferably, the mass ratio of the deep eutectic solvent to the petroleum fraction is 1-10:1.

[0063] According to the present application, preferably, the separation in step (2) is carried out in a solvent recovery column, and the aromatics are obtained at the top of the column, and the eutectic solvent is obtained at the bottom of the column.

[0064] According to the present application, preferably, the separation in step (2) is carried out under conditions including that the temperature at the bottom of the column is 80-200°C, and the pressure at the top of the column is 1-10 kPa.

[0065] In the present application, the extraction column and the solvent recovery column are devices for realizing the purpose of extracting and separating the aromatics in the petroleum distillate, and are not particularly limited, and can be conventional choices in the art.

[0066] The present application does not have a particular limitation on the separation, and the separation can be carried out by conventional technical means in the art. Preferably, the separation is vacuum distillation. By using this preferred embodiment, the aromatics can be separated from the eutectic solvent in a simple manner.

[0067] The eutectic solvent of the present application can be recycled and reused. According to the present application, preferably, the eutectic solvent obtained at the bottom of the solvent recovery column is returned to step (1) for recycling.

[0068] According to a preferred embodiment of the present application, the eutectic solvent 3 enters the extraction column 1 from the middle upper part, the petroleum distillate 4 enters the extraction column 1 from the middle lower part, the raffinate oil 5 (the raffinate oil rich in saturated hydrocarbons) flows out from the top of the extraction column after countercurrent extraction, the extract oil 6 containing the eutectic solvent and the aromatics is sent into the solvent recovery column 2 from the bottom of the extraction column through the heat exchanger 7, the aromatic component 8 is obtained at the top of the solvent recovery column 2, and the eutectic solvent 3 is partly returned to the extraction column 1 for recycling through the heat exchanger 7, and partly is returned to the solvent recovery column 2 after being reboiled by the reboiler 9 to provide heat for the solvent recovery column 2.

[0069] The present application will be described in detail by way of examples below.

[0070] In the following examples, the distribution coefficient (D) and the selectivity (S) are used to represent the extraction effect of the solvent.

[0071] The distribution coefficient (D) is the ratio of the actual mole fraction of the extract in the two phases (the extract phase and the raffinate phase) after the extraction system reaches equilibrium.

[0072] The selectivity (S) is the ratio of the distribution coefficients of the components to be separated, and quantitatively represents the degree of difficulty of the extractant in separating the system to be separated. The larger the S value, the better the separation effect.

[0073] The calculation formulae of the distribution coefficient (D) and the selectivity (S) are as follows:

[0074]

[0075]

[0076]

[0077] where x i is the mole fraction of aromatics, x j is the mole fraction of alkane, and D arom is the partition coefficient of aromatic hydrocarbons, D alkane is the distribution coefficient of alkanes, I and II are the raffinate phase and the extracted phase respectively, and S represents the selectivity of the extractant for aromatics.

[0078] In the following examples, the mass ratio of the deep eutectic solvent to the petroleum fraction is referred to as the solvent-to-oil ratio.

[0079] Example 1

[0080] Weigh the hydrogen bond acceptor 1-ethyl-3-methylimidazolium chloride (EmimCl) and the hydrogen bond donor 1-vinylimidazole (1-Vim) at a molar ratio of 2:1. Stir under reflux at 300 rpm in an oil bath at 100°C for 3 hours to obtain DES. Seal the resulting DES tightly and store in a desiccator for extraction experiments.

[0081] The nuclear magnetic resonance spectrum of DES prepared in Example 1 is given as an example. Figure 1 It can be seen that the chemical shifts of H on the hydrogen bond donor and the hydrogen bond acceptor shift, indicating that a hydrogen bond occurs between EmimCl and Vim, proving the formation of a low eutectic solvent with the structure described in this application.

[0082] The DSC diagram of the DES prepared in Example 1 is given as an example. Figure 2 It can be seen that the freezing point of the DES is lower than -55°C, and the solvent is liquid in the range of -55 to 250°C.

[0083] The synthesized DES was used to extract the 10 model oils in Table 1 at a reagent-oil ratio of 2:1 at 40°C for 30 min. The distribution coefficients and aromatic selectivities were calculated. The compositions of the 10 simulated oils are shown in Table 1, and the extraction results are shown in Table 2.

[0084] Table 1

[0085] Hydrocarbon mole fraction / % Model oil 1 Model oil 2 Model oil 3 Model oil 4 Model Oil 5 Dodecane 51 61 72 81 91 Tetralin 49 39 28 19 9 Hydrocarbon mole fraction / % Model Oil 6 Model Oil 7 Model Oil 8 Model Oil 9 Model oil 10 n-heptane 50 60 71 80 90 Toluene 50 40 29 20 10

[0086] Example 2

[0087] The DES synthesized in Example 1 was used as the extraction solvent, and the model oil 4 in Table 1 was extracted with the synthesized DES at a solvent-to-oil ratio of 4:1 at 60°C for 30 min. The distribution coefficient and aromatic selectivity were calculated. The results are shown in Table 2.

[0088] Example 3

[0089] The DES synthesized in Example 1 was used as the extraction solvent, and the model oil 4 in Table 1 was extracted with the synthesized DES at a solvent-to-oil ratio of 6:1 at 50°C for 30 min. The distribution coefficient and aromatic selectivity were calculated. The results are shown in Table 2.

[0090] Example 4

[0091] Weigh EmimCl and 1-Vim in a molar ratio of 1.5:1. Stir under reflux at 300 rpm in an oil bath at 120°C for 4 hours to obtain DES. Seal the resulting DES tightly and store in a desiccator for use in extraction experiments.

[0092] The model oil 4 in Table 1 was extracted with the synthesized DES at a ratio of 2:1 at 40°C for 30 min. The distribution coefficient and aromatic selectivity were calculated. The results are shown in Table 2.

[0093] Example 5

[0094] Weigh EmimCl and 1-Vim in a molar ratio of 2.5:1. Stir under reflux at 300 rpm in an oil bath at 130°C for 4 hours to obtain DES. Seal the resulting DES tightly and store in a desiccator for use in extraction experiments.

[0095] The model oil 4 in Table 1 was extracted with the synthesized DES at a reagent-oil ratio of 2:1 at 40°C for 30 min. The distribution coefficient and aromatic selectivity were calculated. The results are shown in Table 2.

[0096] Example 6

[0097] The method of Example 1 was followed, except that the molar ratio of 1-ethyl-3-methylimidazolium halide to 1-vinylimidazole was 4.5:1, to obtain DES. The synthesized DES was tightly sealed and stored in a desiccator for use in extraction experiments.

[0098] The model oil 4 in Table 1 was extracted with the synthesized DES at a reagent-oil ratio of 2:1 at 40°C for 30 min. The distribution coefficient and aromatic selectivity were calculated. The results are shown in Table 2.

[0099] Comparative Example 1

[0100] Model oil 4 in Table 1 was extracted once with sulfolane as solvent at a solvent-to-oil ratio of 2:1 at 40°C for 30 min. The distribution coefficient and aromatic selectivity were calculated. The results are shown in Table 2.

[0101] Comparative Example 2

[0102] Model oil 4 in Table 1 was extracted once with dimethyl sulfoxide as solvent at a solvent-to-oil ratio of 2:1 at 40°C for 30 min. The distribution coefficient and aromatic selectivity were calculated. The results are shown in Table 2.

[0103] Comparative Example 3

[0104] Model oil 4 in Table 1 was extracted once with N,N-dimethylformamide (DMF) as solvent at a solvent-to-oil ratio of 2:1 at 40°C for 30 min. The distribution coefficient and aromatic selectivity were calculated. The results are shown in Table 2.

[0105] Comparative Example 4

[0106] Model oil 4 in Table 1 was extracted once for 30 min at 40°C using N-methylpyrrolidone (NMP) as solvent at a solvent-to-oil ratio of 2:1. The distribution coefficient and aromatic selectivity were calculated. The results are shown in Table 2.

[0107] Comparative Example 5

[0108] The method of Example 1 was followed, except that 1-methylimidazole (1-Mim) was used as a hydrogen bond donor to obtain DES. The synthesized DES was tightly sealed and stored in a desiccator for use in extraction experiments.

[0109] The model oil 4 in Table 1 was extracted with the synthesized DES at a reagent-oil ratio of 2:1 at 40°C for 30 min. The distribution coefficient and aromatic selectivity were calculated. The results are shown in Table 2.

[0110] Table 2

[0111]

[0112]

[0113] It can be seen from the results in Table 2 that, compared with conventional organic solvents, the extraction solvent provided by the present invention has better extraction selectivity and is suitable for use as an aromatic hydrocarbon extraction solvent.

[0114] Example 7

[0115] Process flow such as Figure 3 shown.

[0116] The gasoline fraction was subjected to countercurrent extraction using the DES synthesized in Example 1 as the extraction solvent at a solvent-to-oil ratio of 4:1. The extraction column temperature was 50°C, the solvent recovery column bottom temperature was 120°C, and the solvent recovery column top pressure was 3 kPa. The solvent was then recovered by vacuum distillation to obtain raffinate and extracted oil. The compositions of the gasoline feed, raffinate, and extracted oils are shown in Table 3.

[0117] As can be seen from Table 3, the N content in the raffinate oil did not increase relative to the gasoline feedstock, indicating that there was essentially no DES residue in the raffinate oil.

[0118] Table 3

[0119]

[0120]

[0121] Note: Yield = Raffinate oil mass (extracted oil mass) / Raw oil mass × 100%

[0122] Example 8

[0123] Process flow such as Figure 3 shown.

[0124] The light diesel oil fraction was subjected to countercurrent extraction using the DES synthesized in Example 1 as the extraction solvent at a solvent-to-oil ratio of 4:1. The extraction column temperature was 50°C, the solvent recovery column kettle temperature was 160°C, and the solvent recovery column top pressure was 1.5 kPa. The solvent was then recovered by vacuum distillation to produce raffinate oil and extracted oil. The compositions of the light diesel oil feedstock, raffinate oil, and extracted oil are shown in Table 4.

[0125] It can be seen from Table 4 that the N content in the raffinate oil does not increase compared with the light diesel feedstock, indicating that there is basically no DES residue in the raffinate oil.

[0126] Table 4

[0127] Light diesel raw materials Raffinate oil Extracted oil Yield, wt% / 16.6 83.4 N content, μg / g 22 17 / Hydrocarbon composition, wt% Alkanes 13.4 50.9 2.4 Cycloalkanes 4.3 15.5 1.2 Monocyclic aromatic hydrocarbons 38.8 27.4 36.8 polycyclic aromatic hydrocarbons 43.5 6.2 59.6 Total aromatics 82.3 33.6 96.4 total 100 100 100

[0128] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. Use of a deep eutectic solvent in the extraction and separation of aromatic hydrocarbons, wherein the deep eutectic solvent is obtained by melt reaction of 1-ethyl-3-methylimidazole halide and 1-vinylimidazole; in, The molar ratio of 1-ethyl-3-methylimidazole halide to 1-vinylimidazole is 0.2-5:

1.

2. The use according to claim 1, wherein The molar ratio of 1-ethyl-3-methylimidazole halide to 1-vinylimidazole is 1-3:

1.

3. The use according to claim 1, wherein: 1-ethyl-3-methylimidazolium halide is 1-ethyl-3-methylimidazolium chloride or 1-ethyl-3-methylimidazolium bromide.

4. The use according to claim 1, wherein The deep eutectic solvent is liquid in the range of -55 to 250°C.

5. The use according to claim 1, wherein The temperature of the melt reaction is 80-150°C; The melting reaction time is 1-5 hours.

6. The use according to claim 5, wherein: The temperature of the melting reaction is 100-150°C; The melting reaction time is 3-5h.

7. The use according to any one of claims 1 to 6, wherein: Application of the deep eutectic solvent in extracting and separating aromatic hydrocarbons in petroleum fractions.

8. A method for extracting and separating aromatic hydrocarbons from petroleum fractions, the method comprising: (1) The petroleum fraction is brought into countercurrent contact with the deep eutectic solvent to obtain a raffinate oil and an extracted oil containing the deep eutectic solvent and aromatic hydrocarbons; (2) separating the extracted oil containing the deep eutectic solvent and aromatic hydrocarbons in step (1) to obtain aromatic hydrocarbons and the deep eutectic solvent; Wherein, the deep eutectic solvent is obtained by melting reaction of 1-ethyl-3-methylimidazole halide and 1-vinylimidazole; Wherein, the molar ratio of 1-ethyl-3-methylimidazole halide to 1-vinylimidazole is 0.2-5:

1.

9. The method according to claim 8, wherein The reverse contact conditions in step (1) include: a temperature of 30-100°C.

10. The method according to claim 8, wherein The mass ratio of the deep eutectic solvent to the petroleum fraction is 1-10:

1.

11. The method according to claim 8, wherein The separation in step (2) is carried out in a solvent recovery tower.

12. The method according to claim 11, wherein The separation conditions in step (2) include: a bottom temperature of 80-200° C.; and a top pressure of 1-10 kPa.

13. The method according to claim 11, wherein The separation is performed by distillation under reduced pressure.

14. The method according to claim 11, wherein The low eutectic solvent obtained at the bottom of the solvent recovery tower is returned to step (1) for recycling.

15. The method according to claim 8, wherein The petroleum fraction is selected from at least one of gasoline, diesel and kerosene.

16. The method according to claim 8, wherein The molar ratio of 1-ethyl-3-methylimidazole halide to 1-vinylimidazole is 1-3:

1.

17. The method according to claim 8, wherein 1-ethyl-3-methylimidazolium halide is 1-ethyl-3-methylimidazolium chloride or 1-ethyl-3-methylimidazolium bromide.

18. The method according to claim 8, wherein The deep eutectic solvent is liquid in the range of -55 to 250°C.

19. The method according to claim 8, wherein The temperature of the melt reaction is 80-150°C; The melting reaction time is 1-5 hours.

20. The method according to claim 19, wherein The temperature of the melting reaction is 100-150°C; The melting reaction time is 3-5h.

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