Composition, deep eutectic solvent, preparation method and application of deep eutectic solvent, and method for extracting and separating aromatic hydrocarbon in petroleum fraction

Abstract

The invention relates to the field of petroleum component separation, and discloses a composition, a deep eutectic solvent, a preparation method and application of the deep eutectic solvent, and a method for extracting and separating aromatic hydrocarbons in petroleum fractions. The invention relates to a composition. The composition comprises 1-ethyl pyridine chlorine salt and levulinic acid, wherein the molar ratio of the 1-ethyl pyridine chlorine salt to the levulinic acid is (0.5-5): 1. The eutectic solvent prepared from the specific composition is used for extracting and separating aromatic hydrocarbons in petroleum fractions, the obtained raffinate oil basically has no solvent residue, the subsequent aromatic hydrocarbon separation method is simple, and the extraction effect is obviously improved; and compared with the existing common extraction solvent, the aromatic hydrocarbon selectivity is higher.

Description

Technical Field

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

[0002] At present, my country's petrochemical industry is in a period of transformation and development, and the demand for high-quality fuels and chemical raw materials has increased dramatically. In order to obtain better fuels and chemical raw materials, petroleum products need to be separated according to structure and properties and then used separately. Among them, the separation of aromatic-alkane mixed systems is of great significance to the full utilization of petroleum. However, since many aromatics and alkanes have similar physical and chemical properties, especially aromatics and alkanes with similar carbon numbers have very close boiling points and are prone to the production of azeotropes, conventional distillation is difficult to separate them economically and effectively. How to separate aromatics and alkanes in petroleum fractions in a green and efficient manner has become one of the most challenging problems in chemical separation. At present, the methods used by domestic and foreign researchers to separate aromatic-alkane systems mainly include solvent extraction, extractive distillation, adsorption separation, etc.

[0003] Solvent extraction is the most commonly used process in the separation of aromatic and alkane systems. It is a process that mainly uses the different solubility of each component in the aromatic extraction raw material in the organic solvent to achieve the separation of aromatics and alkanes. The solvent extraction method is very efficient in separating aromatics, and there are different process routes depending on the extraction solvent used. Among them, new solvents such as ionic liquids and deep eutectic solvents with structural design characteristics are considered to be one of the most promising directions in the field of extraction separation due to their excellent physical and chemical properties. Deep eutectic solvents (DESs) are usually low eutectic mixtures formed by hydrogen bonding of hydrogen bond donors (HBD) and hydrogen bond acceptors (HBA) in a certain stoichiometric ratio. They have the characteristics of simple preparation, low vapor pressure, good solubility, environmental friendliness, reusability, and strong designability. They are called new ionic liquids. Since it was first reported in 2003, it has been widely used in electrochemistry, energy, extraction solvents and other fields.

[0004] 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 aromatic hydrocarbons from aromatic-aliphatic mixtures. The results showed that DES can effectively separate benzene and hexane mixtures. It was also found that DES as an extractant plays a major role as a hydrogen bond donor (EG) in the extraction and separation process, while the hydrogen bond acceptor (TBPB) plays a secondary role. DES has achieved a separation effect similar to that of organic solvents, but it is difficult to achieve high extraction effect and high selectivity at the same time.

[0005] Inspired by Kareem's research, more and more researchers have begun to study the extraction and separation capabilities of different DESs for aromatics. Although reports on the separation of aromatic-alkane systems by DESs show that DESs have a high selectivity for aromatics, DESs also have the problem of weak solubility for aromatic compounds, resulting in a generally low distribution coefficient for aromatics, which also limits the application of DESs. The current focus of DESs research and development is to maximize its solubility for aromatics while maintaining its high selectivity.

[0006] The development of a low eutectic solvent system 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

[0007] The purpose of the present invention is to overcome the problem that it is difficult to achieve high extraction effect and high selectivity at the same time when DES is used to separate aromatic hydrocarbons in the prior art, and to provide a composition, a low eutectic solvent, a preparation method and application thereof, and a method for extracting and separating aromatic hydrocarbons from petroleum fractions. The low eutectic solvent prepared by the specific composition of the present invention is used to extract and separate aromatic hydrocarbons from petroleum fractions, and there is basically no solvent residue in the obtained raffinate oil, the subsequent aromatic hydrocarbon separation method is simple, and the extraction effect is significantly improved; and compared with the existing commonly used extraction solvents, it has higher aromatic hydrocarbon selectivity.

[0008] In order to achieve the above-mentioned object, the present invention provides a composition on one hand, comprising 1-ethylpyridinium chloride and levulinic acid; wherein the molar ratio of 1-ethylpyridinium chloride to levulinic acid is 0.5-5:1, preferably 1-3:1.

[0009] A second aspect of the present invention provides a low eutectic solvent, the solvent comprising 1-ethylpyridinium chloride and levulinic acid connected by hydrogen bonds.

[0010] In the prior art, sulfolane is usually used as an extraction solvent, but since the boiling point of sulfolane is within the boiling range of kerosene and diesel fractions, it is difficult to recover the solvent through the distillation process, resulting in high separation energy consumption; at the same time, sulfolane will partially decompose to produce corrosive substances containing sulfur, which has a great impact on the long-term use of the device. The low eutectic solvent of the structure described in the present invention obviously overcomes the defects of sulfolane, has a wide liquid temperature range (-30 to 200°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 from petroleum fractions, can extract petroleum fractions within a wide temperature range, and is easy to separate phases with petroleum fractions. There is basically no solvent residue in the raffinate oil obtained, and the subsequent aromatic separation method is simple, which significantly improves the extraction effect and saves separation costs.

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

[0012] A fourth aspect of the present invention provides a use of the low eutectic solvent described in the second aspect or the low 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 in 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 obtained 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 low eutectic solvent prepared from the specific composition of the present invention is used for extracting and separating aromatic hydrocarbons in petroleum fractions. There is basically no solvent residue in the obtained raffinate oil. The subsequent aromatic hydrocarbon separation method is simple and easy to operate, which significantly improves the extraction effect and greatly saves the processing cost. Compared with the existing commonly used extraction solvents, it has higher aromatic hydrocarbon selectivity and has good application prospects in the field of aromatic hydrocarbon separation in petroleum fractions.

[0019] The low eutectic solvent of the present invention has the characteristics of simple preparation process, low corrosion to equipment, easy recovery, green and environmental protection, etc., and can provide a separation solution for the separation and utilization of petroleum fraction 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 the 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. Low eutectic solvent;

[0026] 4. Petroleum fractions; 5. Raffinate oil; 6. Extracted oil containing low eutectic solvent and aromatics; 7. Heat exchanger; 8. Aromatic components; 9. Reboiler. DETAILED DESCRIPTION

[0027] The endpoints and any values ​​of the ranges disclosed in this article 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 endpoint values ​​of each range, the endpoint values ​​of each range and the 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 as specifically disclosed in this article.

[0028] In the description of the present invention, it is necessary to understand that the terms "top", "bottom" and the like indicate orientations or positional relationships 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, and therefore should not be understood as a limitation on the present invention.

[0029] In the present invention, unless otherwise specified, the "tower top pressure" refers to absolute pressure.

[0030] One aspect of the present invention provides a composition, comprising 1-ethylpyridinium chloride and levulinic acid; wherein the molar ratio of 1-ethylpyridinium chloride to levulinic acid is 0.5-5:1, preferably 1-3:1.

[0031] The inventors found in the research process that the composition uses 1-ethylpyridine chloride and levulinic acid and controls the molar ratio of 1-ethylpyridine chloride to levulinic acid to be within the range of 0.5-5:1, which is conducive to preparing the deep eutectic solvent described in the second aspect of the present invention. When the molar ratio of 1-ethylpyridine chloride to levulinic acid is lower or higher than the range described in the present invention, since a stable and uniform hydrogen bond network cannot be formed between molecules, the DES described in the present invention cannot be obtained, which is only equivalent to a mixture of two solid salts.

[0032] In the art, bromide salts are usually used as hydrogen bond acceptors because of their advantages of being easily available and easy to form DES. However, the inventors found in the research process that when a low eutectic solvent prepared by using chloride salt (1-ethylpyridine chloride salt) as a hydrogen bond acceptor in combination with levulinic acid is used to extract and separate aromatic hydrocarbons from petroleum fractions, it has a higher selectivity for aromatic hydrocarbons, and the chloride salt (1-ethylpyridine chloride salt) has more stable performance and is not easy to decompose.

[0033] In the present invention, the molar ratio of 1-ethylpyridine chloride to levulinic acid is 0.5-5:1, such as 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] A second aspect of the present invention provides a low eutectic solvent, wherein the solvent comprises 1-ethylpyridinium chloride and levulinic acid connected by hydrogen bonds.

[0035] According to the characterization of the nuclear magnetic resonance spectrum, it can be seen that the H at 12.08ppm of pure levulinic acid (LA) shifted after forming DES, and the chemical shift shifted from 12.08ppm to 12.27ppm. In the process of DES formation, the hydroxyl hydrogen on LA reacts with the halogen anion Cl on 1-ethylpyridinium chloride (EpyCl) - Therefore, there is no shift in the hydrogen position in the spectrum of EpyCl. According to the above analysis, hydrogen bonding occurs between EpyCl and LA, indicating that a solvent with the structure described in the present invention has been obtained. Figure 1 .

[0036] The schematic structural diagram of the solvent of the present invention can refer 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-ethylpyridine chloride to levulinic acid is 2:1).

[0037]

[0038] The low 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 -30 to 200°C.

[0039] The liquid 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 this DES is lower than -60°C.

[0040] The present invention has no particular limitation on the preparation method of the above-mentioned low eutectic solvent, as long as the low eutectic solvent of the above-mentioned structure can be prepared. In order to further improve the extraction performance of the low eutectic solvent, the present invention also provides a preparation method of the above-mentioned low eutectic solvent. The preparation method provided by the present invention has a simple process and can be widely used.

[0041] Preferably, the third aspect of the present invention provides a method for preparing a low eutectic solvent, the method comprising: the low eutectic solvent is obtained by subjecting the composition described in the first aspect to a melt reaction.

[0042] According to the present invention, preferably, the temperature of the melt reaction is 80-150°C, preferably 100-120°C, such as 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. The use of this preferred embodiment is further conducive to obtaining the low eutectic solvent having the above structure of the present invention. When the temperature of the melt reaction is higher than the range described in the present invention, many side reactions occur and impurities increase.

[0043] The present invention has a wide range of time for the melting reaction, which is based on obtaining the low eutectic solvent having the above structure of the present invention. Preferably, the melting reaction time is 1-10 hours, preferably 3-5 hours.

[0044] According to the present invention, preferably, the melt reaction is carried out under stirring conditions.

[0045] The present invention has no particular limitation on the stirring time and speed, which can be appropriately selected according to specific circumstances.

[0046] 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 low eutectic solvent.

[0047] The fourth aspect of the present invention provides an application of the low eutectic solvent described in the second aspect or the low eutectic solvent obtained by the method described in the third aspect in extracting and separating aromatic hydrocarbons, preferably in extracting and separating aromatic hydrocarbons in petroleum fractions.

[0048] 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 fractions are selected from at least one of gasoline, diesel and kerosene.

[0049] The gasoline, kerosene and diesel provided by the present invention have the conventional definitions in the art and are not particularly limited in the present invention.

[0050] Preferably, the diesel is light diesel.

[0051] The light diesel oil of the present invention refers to diesel oil with a distillation range of 180-380°C.

[0052] A fifth aspect of the present invention provides a method for extracting and separating aromatic hydrocarbons in petroleum fractions, the method comprising:

[0053] (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;

[0054] (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;

[0055] 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.

[0056] In the method provided by the present invention, the reverse contact means that the low eutectic solvent contacts from top to bottom with gravity, and the petroleum fraction contacts from bottom to top.

[0057] 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 aromatics is obtained at the bottom of the tower.

[0058] The low eutectic solvent provided by the present invention can extract petroleum fractions in a wide temperature range and is easy to phase separate from the petroleum fractions. In order to optimize the extraction effect, preferably, the reverse contact conditions in step (1) include: the extraction temperature is 20-150°C, preferably 40-100°C.

[0059] According to the present invention, preferably, the mass ratio of the deep eutectic solvent to the petroleum fraction is 0.5-15:1, preferably 1-10:1.

[0060] According to the present invention, preferably, the separation in step (2) is carried out in a solvent recovery tower, aromatics are obtained at the top of the tower, and a low eutectic solvent is obtained at the bottom of the tower.

[0061] According to the present invention, preferably, the separation conditions in step (2) include: the tower bottom temperature is 80-200° C.; and the tower top pressure is 1-10 kPa.

[0062] In the present invention, the extraction tower and solvent recovery tower are devices for extracting and separating aromatic hydrocarbons in petroleum fractions, and are not particularly limited and can be conventionally selected in the art.

[0063] The present invention has no particular limitation on the separation, and the separation can be performed by conventional technical means in the art. Preferably, the separation is vacuum distillation. With this preferred embodiment, the aromatic hydrocarbons and the deep eutectic solvent can be separated in a simple manner.

[0064] The low eutectic solvent of the present invention can be recycled and reused. Preferably, the low eutectic solvent obtained at the bottom of the solvent recovery tower is returned to the extraction tower for recycling.

[0065] According to a preferred embodiment of the present invention, the low eutectic solvent 3 enters the extraction tower 1 from the middle and upper part, the petroleum fraction 4 enters the extraction tower 1 from the middle and lower part, and the raffinate 5 (raffinate oil rich in saturated hydrocarbons) after countercurrent extraction flows out from the top of the extraction tower, and the extracted oil 6 containing the low eutectic solvent and aromatics is sent to the solvent recovery tower 2 from the bottom of the extraction tower through the heat exchanger 7, and the aromatic component 8 is obtained at the top of the solvent recovery tower 2, and the low eutectic solvent 3 is obtained at the bottom of the tower. Part of it returns to the extraction tower 1 for recycling through the heat exchanger 7, and part of it returns to the solvent recovery tower 2 after passing through the reboiler 9 to provide heat for the solvent recovery tower 2.

[0066] The present invention will be described in detail below through examples.

[0067] In the following examples, the extraction effect of the solvent is reflected by the distribution coefficient (D) and selectivity (S).

[0068] The distribution coefficient (D) is the ratio of the actual molar fractions of the extracted substance in the two phases (the extracted phase and the raffinate phase) after the extraction system reaches equilibrium.

[0069] Selectivity (S) is the ratio of the distribution coefficients of the components to be separated, which quantitatively indicates the difficulty of the extractant in separating the system to be separated. The larger the S value, the better the separation effect.

[0070] The distribution coefficient (D) and selectivity (S) are calculated as follows:

[0071]

[0072]

[0073]

[0074] Among them, x i is the mole fraction of aromatics, x j is the mole fraction of alkane, and D arom is the partition coefficient of aromatics, 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 extraction solvent for aromatics.

[0075] In the following examples, the mass ratio of the deep eutectic solvent to the petroleum fraction is referred to as the agent-oil ratio.

[0076] Example 1

[0077] Weigh hydrogen bond acceptor 1-ethylpyridinium chloride (EpyCl) and hydrogen bond donor levulinic acid (LA), the molar ratio of EpyCl to LA is 2:1, and condense and reflux in an oil bath at 100°C and a speed of 300 r / min for 3 h to obtain DES. The synthesized DES is well sealed and stored in a desiccator for use in extraction experiments.

[0078] The nuclear magnetic resonance spectrum of DES prepared in Example 1 is given as an example. Figure 1 As shown in the figure, it can be seen that the H of pure levulinic acid (LA) with a chemical shift of 12.08 ppm shifted to 12.27 ppm after forming DES, indicating that hydrogen bonding occurred between EpyCl and LA, proving the formation of a low eutectic solvent with the structure described in the present invention.

[0079] The DSC diagram of DES prepared in Example 1 is given as an example. Figure 2 It can be seen that the solvent is in liquid state within the range of -30 to 200°C.

[0080] At a ratio of 2:1, the synthesized DES was used to extract 10 model oils for 30 min at 40°C. The distribution coefficients and aromatic selectivity were calculated. The compositions of the 10 simulated oils are shown in Table 1, and the extraction results are shown in Table 2.

[0081] Table 1

[0082] Hydrocarbon mole fraction / % Model oil 1 Model oil 2 Model oil 3 Model oil 4 Model Oil 5 n-Heptane 52.6 62.6 72.8 82.1 91.2 Toluene 47.4 37.4 27.2 17.9 8.8 Hydrocarbon mole fraction / % Model oil 6 Model Oil 7 Model oil 8 Model oil 9 Model oil 10 Cyclohexane 47.7 57.6 68.2 79.0 90.1 benzene 52.3 42.4 31.8 21.0 9.9

[0083] Example 2

[0084] Using the DES synthesized in Example 1 as the extraction solvent, at a solvent-oil ratio of 4:1, at 60°C, a single extraction was performed on the model oil 4 in Table 1 for 30 minutes, and the distribution coefficient and aromatic selectivity were calculated. The results are shown in Table 2.

[0085] Example 3

[0086] Using the DES synthesized in Example 1 as the extraction solvent, at a solvent-oil ratio of 6:1, at 50°C, a single extraction was performed on the model oil 4 in Table 1 for 30 minutes, and the distribution coefficient and aromatic selectivity were calculated. The results are shown in Table 2.

[0087] Example 4

[0088] Weigh EpyCl and LA, the molar ratio of EpyCl to LA is 1.5:1, and react in an oil bath at 120°C, 300 rpm, condense, reflux, stir and react for 4 h to obtain DES. The synthesized DES is well sealed and stored in a desiccator for use in extraction experiments.

[0089] The model oil 4 in Table 1 was extracted once with the synthesized DES at a ratio of 2:1 at 40°C for 30 min, and the distribution coefficient and aromatic selectivity were calculated. The results are shown in Table 2.

[0090] Example 5

[0091] Weigh EpyCl and LA, the molar ratio of EpyCl to LA is 2.5:1, and react in an oil bath at 120°C, 300 rpm, condense, reflux, stir and react for 4 h to obtain DES. The synthesized DES is well sealed and stored in a desiccator for use in extraction experiments.

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

[0093] Example 6

[0094] The method of Example 1 was followed, except that the molar ratio of the hydrogen bond acceptor 1-ethylpyridinium chloride (EpyCl) to the hydrogen bond donor levulinic acid (LA) was 4:1 to obtain DES. The synthesized DES was well sealed and stored in a desiccator for use in extraction experiments.

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

[0096] Comparative Example 1

[0097] Using sulfolane as solvent, at a solvent-oil ratio of 2:1, at 40°C, the model oil 4 in Table 1 was extracted once for 30 min, and the distribution coefficient and aromatic selectivity were calculated. The results are shown in Table 2.

[0098] Comparative Example 2

[0099] Using dimethyl sulfoxide as solvent, at a solvent-oil ratio of 2:1, at 40°C, the model oil 4 in Table 1 was extracted once for 30 min, and the distribution coefficient and aromatic selectivity were calculated. The results are shown in Table 2.

[0100] Comparative Example 3

[0101] Using N,N-dimethylformamide (DMF) as solvent, at a solvent-oil ratio of 2:1, at 40°C, the model oil 4 in Table 1 was extracted once for 30 min, and the distribution coefficient and aromatic selectivity were calculated. The results are shown in Table 2.

[0102] Comparative Example 4

[0103] Using N-methylpyrrolidone (NMP) as solvent, at a solvent-oil ratio of 2:1, at 40°C, the model oil 4 in Table 1 was extracted once for 30 min, and the distribution coefficient and aromatic selectivity were calculated. The results are shown in Table 2.

[0104] Comparative Example 5

[0105] Using dimethyl sulfoxide as solvent, at a solvent-oil ratio of 2:1, at 40°C, the model oil 9 in Table 1 was extracted once for 30 min, and the distribution coefficient and aromatic selectivity were calculated. The results are shown in Table 2.

[0106] Comparative Example 6

[0107] Using DMF as solvent, at a solvent-oil ratio of 2:1, at 40°C, the model oil 9 in Table 1 was subjected to a single extraction for 30 min, and the distribution coefficient and aromatic selectivity were calculated. The results are shown in Table 2.

[0108] Comparative Example 7

[0109] The method of Example 1 was followed, except that 1-ethylpyridinium bromide was used as a hydrogen bond acceptor to obtain DES. The synthesized DES was well sealed and stored in a desiccator for use in extraction experiments.

[0110] The model oil 4 in Table 1 was extracted once with the synthesized DES at a ratio of 2:1 at 40°C for 30 min, and the distribution coefficient and aromatic selectivity were calculated. The results are shown in Table 2.

[0111] Table 2

[0112] Extraction agent Model oil <![CDATA[D 烷烃 ]]> <![CDATA[D 芳烃 ]]> <![CDATA[S 芳烃 ]]> Example 1 <![CDATA[n EpyCl :n LA =2]]> 1 0.0073 0.2718 37.41 Example 1 <![CDATA[n EpyCl :n LA =2]]> 2 0.0070 0.2711 38.52 Example 1 <![CDATA[n EpyCl :n LA =2]]> 3 0.0066 0.2736 41.36 Example 1 <![CDATA[n EpyCl :n LA =2]]> 4 0.0060 0.2755 45.60 Example 1 <![CDATA[n EpyCl :n LA =2]]> 5 0.0055 0.3092 56.17 Example 1 <![CDATA[n EpyCl :n LA =2]]> 6 0.0199 0.2351 11.79 Example 1 <![CDATA[n EpyCl :n LA =2]]> 7 0.0186 0.2368 12.75 Example 1 <![CDATA[n EpyCl :n LA =2]]> 8 0.0178 0.2377 13.32 Example 1 <![CDATA[n EpyCl :n LA =2]]> 9 0.0146 0.2444 16.77 Example 1 <![CDATA[n EpyCl :n LA =2]]> 10 0.0119 0.2513 21.09 Example 2 <![CDATA[n EpyCl :n LA =2]]> 4 0.0039 0.1653 42.38 Example 3 <![CDATA[n EpyCl :n LA =2]]> 4 0.0031 0.1194 38.52 Example 4 <![CDATA[n EpyCl :n LA =1.5]]> 4 0.0041 0.1856 45.27 Example 5 <![CDATA[n EpyCl :n LA =2.5]]> 4 0.0029 0.1371 47.28 Example 6 <![CDATA[n EpyCl :n LA =4]]> 4 0.0013 0.0587 45.15 Comparative Example 1 Sulfolane 4 0.0089 0.3988 44.82 Comparative Example 2 Dimethyl sulfoxide 4 0.0093 0.2926 31.58 Comparative Example 3 DMF 4 0.1029 0.702 6.82 Comparative Example 4 NMP 4 0.2352 0.59 2.51 Comparative Example 5 Sulfolane 9 0.2369 1.56 6.59 Comparative Example 6 Dimethyl sulfoxide 9 0.3531 1.8696 5.30 Comparative Example 7 <![CDATA[n C2py :n LA =2]]> 4 0.0106 0.2885 27.11

[0113] It can be seen from the results in Table 2 that, compared with conventional organic solvents, the low eutectic 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 DES synthesized in Example 1 was used as an extraction solvent, at a solvent-oil ratio of 4:1, under the conditions of an extraction tower temperature of 50°C, a solvent recovery tower kettle temperature of 120°C, and a solvent recovery tower top pressure of 3kPa, the gasoline fraction was subjected to countercurrent extraction with the synthesized DES, and the solvent was recovered by vacuum distillation to obtain raffinate oil and extracted oil. The composition results of the gasoline raw material, raffinate oil and extracted oil are shown in Table 3.

[0117] It can be seen from Table 3 that 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] Gasoline raw materials Extraction of residual oil Extraction of oil Yield, wt% / 75.5 24.5 N content, μg / g 5 4 / Hydrocarbon composition, wt% Alkanes 32.93 43.81 1.12 Cycloalkanes 6.03 7.98 0.28 Olefins 35.71 45.84 2.16 Aromatics 25.33 2.37 96.44 total 100 100 100

[0120] Note: Yield = Raffinate oil mass (extracted oil mass) / raw oil mass × 100%

[0121] Example 8

[0122] Process flow such as Figure 3 shown.

[0123] The DES synthesized in Example 1 was used as the extraction solvent, and the solvent-oil ratio was 5:1. Under the conditions of an extraction tower temperature of 50°C, a solvent recovery tower kettle temperature of 160°C, and a solvent recovery tower top pressure of 1.5 kPa, the light diesel oil fraction was subjected to countercurrent extraction, and the solvent was recovered by vacuum distillation to obtain raffinate oil and extracted oil. The composition results of the light diesel oil raw material, raffinate oil and extracted oil are shown in Table 4.

[0124] As can be seen from Table 4, the N content in the raffinate oil did not increase relative to the diesel feedstock, indicating that there was essentially no DES residue in the raffinate oil.

[0125] Table 4

[0126] Diesel feedstock Extraction of residual oil Extraction of oil Yield, wt% 25.8 74.2 N content, μg / g 22 14 / Hydrocarbon composition, wt% Alkanes 13.4 42.6 2.0 Cycloalkanes 4.3 13.8 1.0 Monocyclic aromatic hydrocarbons 38.8 37.4 39.1 PAHs 43.5 6.2 57.9 Total aromatics 82.3 43.6 97.0 total 100 100 100

[0127] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A composition, characterized in that The composition comprises 1-ethylpyridinium chloride and levulinic acid; wherein the molar ratio of 1-ethylpyridinium chloride to levulinic acid is 0.5-5:1, preferably 1-3:

1.

2. A deep eutectic solvent comprising hydrogen-bonded 1-ethylpyridinium chloride and levulinic acid.

3. The solvent according to claim 2, wherein The solvent is liquid in the range of -30 to 200°C.

4. A method for preparing a deep eutectic solvent, the method comprising: The deep eutectic solvent is obtained by subjecting the composition according to claim 1 to a melt reaction.

5. The method according to claim 4, wherein: The temperature of the melt reaction is 80-150°C, preferably 100-120°C; Preferably, the melting reaction time is 1-10 h, preferably 3-5 h.

6. Use of the deep eutectic solvent according to claim 2 or 3 or the deep eutectic solvent obtained by the method according to claim 4 or 5 in extracting and separating aromatic hydrocarbons, preferably in extracting and separating aromatic hydrocarbons in petroleum fractions.

7. A method for extracting and separating aromatic hydrocarbons from petroleum fractions, the method comprising: (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; (2) separating the extracted oil containing the deep eutectic solvent and aromatic hydrocarbons obtained in step (1) to obtain aromatic hydrocarbons and the deep eutectic solvent; Wherein, the low eutectic solvent in step (1) is the low eutectic solvent according to claim 2 or 3 or the low eutectic solvent prepared by the method according to claim 4 or 5.

8. The method according to claim 7, wherein: The conditions for the reverse contact in step (1) include: a temperature of 20-150° C., preferably 40-100° C.; Preferably, the mass ratio of the deep eutectic solvent to the petroleum fraction is 0.5-15:1, preferably 1-10:

1.

9. The method according to claim 7, wherein: The separation in step (2) is carried out in a solvent recovery tower; Preferably, the separation conditions in step (2) include: the tower bottom temperature is 80-200° C.; the tower top pressure is 0.1-10 kPa; Preferably, the separation is vacuum distillation; Preferably, the low eutectic solvent obtained at the bottom of the solvent recovery tower is returned to step (1) for recycling.

10. The method according to claim 9, wherein: The petroleum fraction is selected from at least one of gasoline, diesel and kerosene.

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