Silver-based eutectic solvent and application thereof

Abstract

The invention belongs to the technical field of extraction separation, and relates to a silver-based eutectic solvent which is composed of silver salt serving as a hydrogen bond acceptor and an organic compound serving as a hydrogen bond donor. Wherein the organic compound serving as the hydrogen bond donor is a carbonyl organic compound or an alcohol organic compound. The silver-based deep-eutectic solvent provided by the invention is easy to prepare, the structure is easy to regulate and control, and the silver-based deep-eutectic solvent has the advantages of good thermal stability, reproducibility and the like, and has high unsaturated hydrocarbon absorption capacity and excellent separation performance for unsaturated hydrocarbon mixtures.

Description

Technical Field

[0001] The invention belongs to the technical field of extraction and separation, and relates to a silver-based low eutectic solvent and application thereof in extraction and separation of unsaturated hydrocarbon mixtures. Background Art

[0002] Unsaturated hydrocarbons (olefins and aromatics) are important products in petrochemical and coal chemical industries, and are also important basic raw materials closely related to industrial production and people's lives. Olefins and aromatics are used as starting materials to synthesize many valuable compounds and are widely used in the fields of industry, medicine, energy, etc. At present, olefins are mainly obtained through three process routes: naphtha-to-olefins, coal-to-olefins, and gas-to-olefins, among which oil-to-olefins dominate. However, in the process of producing olefins and aromatics, a mixture of them and alkanes is often obtained. Due to their similar structures and small boiling point differences, separation is extremely difficult.

[0003] At present, mature separation processes include extractive distillation, membrane separation, adsorption separation and liquid-liquid extraction. Traditional separation processes such as extractive distillation have the problems of high energy consumption and high cost for near-boiling or azeotropic systems. The membrane separation method forms a certain partial pressure difference on both sides of the membrane for separation based on the different permeation rates of each component in the membrane, but its high cost, complex production process and small processing volume have rarely been used in industry. The separation of gaseous mixed hydrocarbons by adsorption has been widely studied, but there are problems such as difficulty in determining the adsorption capacity in liquid mixed hydrocarbons, and the large-scale production and desorption recovery of adsorbents are also facing challenges. Liquid-liquid extraction has the advantages of simple operation, high separation selectivity and low energy consumption, and is widely used in the separation of hydrocarbon mixtures. Traditional liquid-liquid extraction processes often use organic solvents such as sulfolane (SUL), dimethyl sulfoxide (DMSO) and N-methylpyrrolidone (NMP) as extractants for separation. However, these organic solvents are toxic and volatile, and are easy to contaminate oil products during the separation process. At the same time, organic solvents have poor separation effects on olefin / alkane mixtures.

[0004] In order to improve the separation selectivity of unsaturated hydrocarbon mixtures, the separation efficiency of unsaturated hydrocarbons can be improved by introducing transition metal ions into the extractant. Transition metal ions can form π complexes with unsaturated hydrocarbons to obtain higher selectivity. Silver ions and cuprous ions are the most commonly used metal ions for the separation of unsaturated hydrocarbons, but the stability of cuprous ions limits their industrial application. Chinese patent CN117753171A provides a silver ion-containing liquid and its preparation method and application, which improves the absorption and selectivity of the absorbent for olefins. The preparation method has strict conditions and general selectivity for olefins. At present, there are relatively few studies on the separation of liquid unsaturated hydrocarbon mixtures using transition metals, and there have always been problems such as poor separation selectivity. Therefore, it is necessary to research and develop a new type of extractant with excellent separation performance of unsaturated hydrocarbon mixtures, easy preparation, and high stability. Summary of the invention

[0005] One of the purposes of the present invention is to provide a silver-based deep eutectic solvent in view of the problems existing in the prior art. The silver-based deep eutectic solvent introduces silver ions as structural units of the deep eutectic solvent, and the obtained silver-based deep eutectic solvent has the advantages of high absorption capacity, high selectivity, good thermal stability and regeneration.

[0006] The second object of the present invention is to provide an application of a silver-based deep eutectic solvent in the extraction and separation of unsaturated hydrocarbon mixtures. The present invention utilizes the reversible complexation between silver ions and unsaturated hydrocarbons to greatly improve the separation selectivity and achieve efficient separation of unsaturated hydrocarbons.

[0007] To this end, the first aspect of the present invention provides a silver-based low eutectic solvent, which is composed of a silver salt as a hydrogen bond acceptor and an organic compound as a hydrogen bond donor; wherein the organic compound as a hydrogen bond donor is a carbonyl organic compound or an alcohol organic compound.

[0008] In some embodiments of the present invention, the silver salt serving as a hydrogen bond acceptor is any one of silver bis(trifluoromethanesulfonyl)imide, silver trifluoromethanesulfonate, silver trifluoroacetate, silver tetrafluoroborate, silver hexafluorophosphate, and silver nitrate.

[0009] In some embodiments of the present invention, the alcohol organic compound is any one of ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, glycerol, triethylene glycol, and tetraethylene glycol.

[0010] In the present invention, the carbonyl organic compound is an amide organic compound or a ketone organic compound.

[0011] In some embodiments of the present invention, the amide organic compound is selected from acetamide, propionamide, N,N-dimethylformamide, N,N-dimethylacetamide, acrylamide, N-ethylacetamide, isobutyramide, N,N-dimethylacrylamide, N-methylformanilide, cyclopropanamide, N-phenylformamide, N-(hydroxymethyl)acrylamide, p-aminobenzamide, caprolactam and N-vinylcaprolactam.

[0012] In some embodiments of the present invention, the ketone organic compound is selected from 2-pyrrolidone, N-methylpyrrolidone and 1,3-dimethyl-2-imidazolidinone.

[0013] Preferably, the molar ratio of the silver salt to the organic compound in the silver-based deep eutectic solvent is 1:(1-8).

[0014] In some embodiments of the present invention, the eutectic point of the silver-based deep eutectic solvent is less than 30°C.

[0015] The second aspect of the present invention provides use of the silver-based deep eutectic solvent as described in the first aspect of the present invention in extracting and separating unsaturated hydrocarbon mixtures.

[0016] According to the present invention, the application comprises:

[0017] Step A, using an unsaturated hydrocarbon mixture as a raw liquid and a silver-based low eutectic solvent as an extractant, performing liquid-liquid extraction, standing and separating, the upper layer is a raffinate phase containing unextracted unsaturated hydrocarbon mixture, and the lower layer is an extraction phase rich in unsaturated hydrocarbons;

[0018] Step B, performing vacuum rotary evaporation on the extract phase, collecting the condensate to obtain unsaturated hydrocarbons, and the remaining liquid is a silver-based low eutectic solvent;

[0019] Wherein, the unsaturated hydrocarbon mixture is a mixture of liquid unsaturated hydrocarbons and alkanes; the unsaturated hydrocarbons are olefins and / or aromatic hydrocarbons.

[0020] In some embodiments of the present invention, the extraction process conditions are: extraction temperature of 1 to 80°C, extraction time of 10s to 180min, extractant / raw liquid volume ratio of 1:10 to 10:1, and the molar content of unsaturated hydrocarbons in the mixture of liquid unsaturated hydrocarbons and alkanes is 0.1% to 99.9%.

[0021] In some specific embodiments of the present invention, the unsaturated hydrocarbon mixture is a mixture of olefins and alkanes, wherein the olefins are liquid chain olefins and / or cyclic olefins, and the alkanes are liquid alkanes.

[0022] In some other specific embodiments of the present invention, the unsaturated hydrocarbon mixture is a mixture of aromatic hydrocarbons and alkanes, wherein the aromatic hydrocarbons are single-ring and / or condensed-ring, and the alkanes are liquid alkanes.

[0023] In some embodiments of the present invention, in step B, the process conditions of the reduced pressure rotary evaporation are: the vacuum degree is 0.01 MPa to 0.1 MPa, and the rotary evaporation temperature is 20 to 100°C.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) The present invention provides a silver-based low eutectic solvent, in which silver ions are introduced as structural units of the low eutectic solvent, and silver salts and organic compounds are used as hydrogen bond acceptors and hydrogen bond donors, respectively, to synthesize the silver-based low eutectic solvent under certain conditions.

[0026] (2) The silver-based low eutectic solvent provided by the present invention has a simple preparation method, an easily controllable structure, and has the advantages of high unsaturated hydrocarbon absorption, high separation selectivity, good thermal stability and renewability.

[0027] (3) The silver-based low eutectic solvent provided by the present invention has excellent separation performance for unsaturated hydrocarbon mixtures, the unsaturated hydrocarbon / alkane selectivity can reach up to 1167.32, and the single-stage extraction removal rate (i.e., extraction rate) can reach up to 97.23%. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The present invention will be described below with reference to the accompanying drawings.

[0029] Figure 1 The silver-based deep eutectic solvents composed of silver salts and carbonyl organic compounds in different molar ratios in the present invention are shown.

[0030] Figure 2 This is the thermogravimetric curve of the silver-based deep eutectic solvent prepared in Example 3 of the present invention. DETAILED DESCRIPTION

[0031] To make the present invention easy to understand, the present invention will be described in detail below in conjunction with the accompanying drawings and examples. However, before describing the present invention in detail, it should be understood that the present invention is not limited to the specific embodiments described. It should also be understood that the terms used herein are only for describing specific embodiments and are not intended to be limiting.

[0032] Unless otherwise defined, all terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the invention belongs. Although any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the present invention, preferred methods and materials are now described.

[0033] As mentioned above, the mixture of unsaturated hydrocarbons (olefins and aromatics) and alkanes is extremely difficult to separate due to their similar structures and small boiling point differences. Currently, mature separation processes include extractive distillation, membrane separation, adsorption separation and liquid-liquid extraction. Traditional separation processes such as extractive distillation have the problems of high energy consumption and high cost for near-boiling or azeotropic systems. Membrane separation is rarely used in industry due to its high cost, complex production process and small processing volume. The adsorption method has problems such as difficulty in determining the adsorption capacity in liquid mixed hydrocarbons, and the large-scale production and desorption recovery of adsorbents are also challenging. The organic solvents of the traditional liquid-liquid extraction process are toxic and volatile, which can easily contaminate the oil products during the separation process; at the same time, the organic solvent has a poor separation effect on olefin / alkane mixtures.

[0034] In order to improve the separation selectivity of unsaturated hydrocarbon mixtures, the separation efficiency of unsaturated hydrocarbons can be improved by introducing transition metal ions into the extractant. Silver ions and cuprous ions are the metal ions most commonly used for the separation of unsaturated hydrocarbons, but the stability of cuprous ions limits their industrial application. Chinese patent CN117753171A provides a silver ion-containing liquid and its preparation method and application, which improves the absorption and selectivity of the absorbent to olefins. The preparation method has strict conditions and general selectivity to olefins. At present, there are relatively few studies on the separation of liquid unsaturated hydrocarbon mixtures using transition metals, and there have always been problems such as poor separation selectivity. In view of this, the inventors have conducted a large amount of research on new extractants for the separation of unsaturated hydrocarbon mixtures.

[0035] The inventors have noticed that low eutectic solvents have been widely used due to their advantages such as low volatility and controllable structure. The inventors have found that mixing silver salts with carbonyl organic compounds or alcohol organic compounds can produce a silver-based low eutectic solvent with the advantages of high unsaturated hydrocarbon absorption, high selectivity, good thermal stability and renewability. The silver-based low eutectic solvent introduces silver ions as structural units of the low eutectic solvent, and utilizes the reversible complexation between silver ions and unsaturated hydrocarbons to greatly improve the separation selectivity and achieve efficient separation of unsaturated hydrocarbons. The present invention is thus obtained.

[0036] To realize the present invention, the inventors first mixed a silver salt as a hydrogen bond acceptor with an organic compound as a hydrogen bond donor under vacuum conditions of 0.04 to 0.1 MPa and light-proof conditions at 30 to 90° C. for 2 to 12 hours to obtain a silver-based low eutectic solvent, which is recorded as silver salt-organic compound.

[0037] In some embodiments of the present invention, the silver salt serving as a hydrogen bond acceptor is any one of silver bis(trifluoromethanesulfonyl)imide, silver trifluoromethanesulfonate, silver trifluoroacetate, silver tetrafluoroborate, silver hexafluorophosphate, and silver nitrate.

[0038] In the present invention, the organic compound serving as a hydrogen bond donor is a carbonyl organic compound or an alcohol organic compound.

[0039] In some embodiments of the present invention, the alcohol organic compound is any one of ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, glycerol, triethylene glycol, and tetraethylene glycol.

[0040] In the present invention, the carbonyl organic compound is an amide organic compound or a ketone organic compound.

[0041] In some embodiments of the present invention, the amide organic compound is selected from acetamide, propionamide, N,N-dimethylformamide, N,N-dimethylacetamide, acrylamide, N-ethylacetamide, isobutyramide, N,N-dimethylacrylamide, N-methylformanilide, cyclopropanamide, N-phenylformamide, N-(hydroxymethyl)acrylamide, p-aminobenzamide, caprolactam and N-vinylcaprolactam.

[0042] In some embodiments of the present invention, the ketone organic compound is selected from 2-pyrrolidone, N-methylpyrrolidone and 1,3-dimethyl-2-imidazolidinone.

[0043] The inventors have found that when the molar ratio of the silver salt to the organic compound in the silver-based deep eutectic solvent is 1:(1-8), preferably 1:(2-6), the separation efficiency of the obtained silver-based deep eutectic solvent for separating unsaturated hydrocarbon mixtures is relatively high.

[0044] In some embodiments of the present invention, the eutectic point of the silver-based deep eutectic solvent is less than 30°C.

[0045] The research results show that the silver-based low eutectic solvent provided by the present invention is easy to prepare, has an easy-to-control structure, has the advantages of good thermal stability and renewability, and has a high unsaturated hydrocarbon absorption capacity and excellent separation performance for unsaturated hydrocarbon mixtures.

[0046] The use of the above-mentioned silver-based deep eutectic solvent in the extraction and separation of unsaturated hydrocarbon mixtures involved in the present invention can be understood as a method for extracting and separating unsaturated hydrocarbon mixtures using the above-mentioned silver-based deep eutectic solvent, which comprises the following steps:

[0047] (1) using an unsaturated hydrocarbon mixture (liquid unsaturated hydrocarbon and alkane mixture) as a raw liquid, adding a silver-based deep eutectic solvent as an extractant, performing liquid-liquid extraction, and then standing to separate, the upper layer is a raffinate phase containing unextracted unsaturated hydrocarbon mixture, and the lower layer is an extraction phase rich in unsaturated hydrocarbons;

[0048] The process conditions of liquid-liquid extraction are: extraction temperature of 1 to 80° C., extraction time of 10 s to 180 min, preferably 1 to 90 min, volume ratio of extractant to raw liquid of 1:10 to 10:1, preferably 1:5 to 5:1, and molar content of unsaturated hydrocarbons in the mixture of liquid unsaturated hydrocarbons and alkanes of 0.1% to 99.9%, preferably 5% to 95%;

[0049] (2) performing vacuum rotary evaporation on the extract phase, collecting the condensate to obtain unsaturated hydrocarbons, and the remaining liquid is a silver-based deep eutectic solvent, which can be recycled;

[0050] Wherein, the unsaturated hydrocarbon mixture is a mixture of liquid unsaturated hydrocarbons and alkanes; the unsaturated hydrocarbons are olefins and / or aromatic hydrocarbons.

[0051] It should be understood by those skilled in the art that in the liquid-liquid extraction process in the above step (1), the upper phase after standing is the raffinate phase and the lower phase is the extraction phase. The raffinate phase contains the unextracted unsaturated hydrocarbon mixture, and the extraction phase is rich in unsaturated hydrocarbons and silver-based deep eutectic solvent extractant.

[0052] For example, in some specific embodiments, the unsaturated hydrocarbon mixture is a mixture of olefins and alkanes, wherein the olefins are liquid chain olefins and / or cyclic olefins; the alkanes are liquid alkanes, including but not limited to 1-hexene / n-hexane, cyclohexene / cyclohexane, and 1-octene / n-octane.

[0053] For another example, in some other specific embodiments, the unsaturated hydrocarbon mixture is a mixture of aromatic hydrocarbons and alkanes, wherein the aromatic hydrocarbons are monocyclic and / or condensed-ring aromatic hydrocarbons, and the alkanes are liquid alkanes, including but not limited to benzene / cyclohexane, toluene / n-heptane, tetralin / dodecane, and 1-methylnaphthalene / dodecane.

[0054] In some embodiments of the present invention, in the above step (2), the process conditions of the reduced pressure rotary evaporation are: the vacuum degree is 0.01MPa to 0.1MPa, and the rotary evaporation temperature is 20 to 100°C.

[0055] In the present invention, the content of each component in the extract phase and the raffinate phase obtained by liquid-liquid extraction is calculated using the following formula to calculate the distribution coefficient D, selectivity S, and extraction rate E of the component:

[0056]

[0057] In formulas (1) to (4), i is an olefin or aromatic hydrocarbon, j is an alkane; xi Ex is the mass fraction of olefins or aromatics in the extract phase (detected by gas chromatography), xi raf is the mass fraction of olefins or aromatics in the raffinate phase (detected by gas chromatography); D i is the distribution coefficient of olefins or aromatics, Dj is the distribution coefficient of alkanes; w i0 is the initial concentration of olefins or aromatics in the feed solution, w it is the final concentration of olefins in the raffinate phase.

[0058] Example

[0059] The present invention is further described in detail below through specific examples. The experimental methods described below, unless otherwise specified, are all routine laboratory methods. The experimental materials described below, unless otherwise specified, can all be obtained from commercial channels.

[0060] Embodiment 1:

[0061] (1) Accurately weigh a certain amount of silver trifluoromethanesulfonate and add it to a brown round-bottom flask. Add 1,3-dimethyl-2-imidazolidinone in a molar ratio of 1:2. Connect a tetrafluoro piston exhaust joint and evacuate the flask to maintain a vacuum environment (0.04-0.1 MPa). Then, place the mixture in an 80°C constant temperature oil bath in the dark and stir for 6 h to obtain a uniform and clear solution.

[0062] (2) A mixture of 1-hexene and n-hexane was used as the raw material liquid, and the molar ratio of 1-hexene to n-hexane in the raw material liquid was 2:8. A certain volume of silver-based low eutectic solvent was transferred into a 50 mL conical flask with a lid, and then the same volume of raw material liquid (the volume ratio of extractant / raw material liquid was 1:1) was transferred into the conical flask. The conical flask was then placed in a water bath constant temperature oscillator set at 30°C, oscillated at 200 rpm for 50 min, and then allowed to stand at the same temperature for 2 h until the upper and lower phases were completely separated. Finally, an appropriate amount of the extract phase and the raffinate phase were taken for GC analysis (Agilent 8890A, USA).

[0063] According to GC analysis, the distribution coefficient of 1-hexene is 0.7115, the distribution coefficient of n-hexane is 0.0164, the separation selectivity is 43.25, and the extraction rate of 1-hexene is 60.95%.

[0064] Embodiment 2:

[0065] (1) Accurately weigh a certain amount of silver trifluoroacetate and add it into a brown round-bottom flask, add propionamide in a molar ratio of 1:2, connect a tetrafluoro piston exhaust joint and evacuate the flask to maintain a vacuum environment (0.04-0.1 MPa), then place the mixture in an 80°C constant temperature oil bath in the dark and stir for 6 h to obtain a uniform and clear solution.

[0066] (2) A mixture of 1-hexene and n-hexane was used as the raw material liquid, and the molar ratio of 1-hexene to n-hexane in the raw material liquid was 2:8. A certain volume of silver-based low eutectic solvent was transferred into a 50 mL conical flask with a lid, and then the same volume of raw material liquid (volume ratio of extractant / raw material liquid was 1:1) was transferred into the conical flask. The conical flask was then placed in a water bath constant temperature oscillator set at 30°C, oscillated at 200 rpm for 50 min, and then allowed to stand at the same temperature for 2 h until the upper and lower phases were completely separated. Finally, an appropriate amount of the extract phase and the raffinate phase were taken for GC analysis.

[0067] According to GC analysis, the distribution coefficient of 1-hexene is 0.3784, the distribution coefficient of n-hexane is 0.0185, the separation selectivity is 20.49, and the extraction rate of 1-hexene is 51.25%.

[0068] Embodiment 3:

[0069] (1) Accurately weigh a certain amount of silver bis(trifluoromethanesulfonyl)imide and add it into a brown round-bottom flask, add propionamide in a molar ratio of 1:2, connect a tetrafluoro piston exhaust joint and evacuate the air to maintain a vacuum environment (0.04-0.1 MPa) in the flask, then place the mixture in a constant temperature oil bath at 80°C in the dark and stir for 6 h to obtain a uniform and clear solution.

[0070] (2) A mixture of 1-hexene and n-hexane was used as the raw material liquid, and the molar ratio of 1-hexene to n-hexane in the raw material liquid was 2:8. A certain volume of silver-based low eutectic solvent was transferred into a 50 mL conical flask with a lid, and then the raw material liquid was transferred into the conical flask according to a volume ratio of 3:1 (the volume ratio of the extractant / raw material liquid was 3:1). The conical flask was then placed in a water bath constant temperature oscillator set at 30°C, and oscillated at 200 rpm for 50 min. After that, it was left to stand for 2 h at the same temperature until the upper and lower phases were completely separated. Finally, an appropriate amount of the extract phase and the raffinate phase were taken for GC analysis.

[0071] According to GC analysis, the distribution coefficient of 1-hexene is 4.3492, the distribution coefficient of n-hexane is 0.0156, the separation selectivity is 278.20, and the extraction rate of 1-hexene is 97.23%.

[0072] Silver-based deep eutectic solvents composed of different molar ratios of silver bis(trifluoromethanesulfonyl)imide and propionamide such as Figure 1 As shown, from Figure 1 It can be seen that the extractants synthesized in different molar ratios are all clear, transparent light yellow liquids; the experimental results show that the silver-based low eutectic solvent synthesized from silver bistrifluoromethanesulfonyl imide and propionamide in a molar ratio of 1:2 has the best separation performance, the distribution coefficient of 1-hexene is 4.3492, the distribution coefficient of n-hexane is 0.0156, the separation selectivity is 278.20, and the extraction rate of 1-hexene is 97.23%.

[0073] The thermogravimetric curve of the silver-based deep eutectic solvent synthesized from silver bis(trifluoromethanesulfonyl)imide and propionamide in a molar ratio of 1:2 is shown in Figure 2 As shown, from Figure 2 It can be seen that the solvent exhibits a two-stage mass loss, the thermal decomposition temperature is higher than 160 °C, and it has good thermal stability.

[0074] Example 4

[0075] (1) Accurately weigh a certain amount of silver tetrafluoroborate and add it to a brown round-bottom flask, add 1,2-propylene glycol in a molar ratio of 1:2, connect a tetrafluoro piston vacuum joint and evacuate the flask to maintain a vacuum environment (0.04-0.1 MPa), then place the mixture in a 60°C constant temperature oil bath in the dark and stir for 3 h to obtain a uniform and clear solution.

[0076] (2) A mixture of cyclohexene and cyclohexane was used as the raw material liquid, and the molar ratio of cyclohexene to cyclohexane in the raw material liquid was 2:8. A certain volume of silver-based low eutectic solvent was transferred into a 50 mL conical flask with a lid, and then the same volume of raw material liquid (the volume ratio of extractant / raw material liquid was 1:1) was transferred into the conical flask. The conical flask was then placed in a water bath constant temperature oscillator set at 30°C, oscillated at 200 rpm for 40 min, and then allowed to stand at the same temperature for 2 h until the upper and lower phases were completely separated. Finally, an appropriate amount of the extract phase and the raffinate phase were taken for GC analysis.

[0077] According to GC analysis, the distribution coefficient of cyclohexene is 4.0250, the distribution coefficient of cyclohexane is 0.0087, the separation selectivity is 461.94, and the extraction rate of cyclohexene is 81.38%.

[0078] Example 5

[0079] (1) Accurately weigh a certain amount of silver bis(trifluoromethanesulfonyl)imide and add it into a brown round-bottom flask, add propionamide in a molar ratio of 1:2, connect a tetrafluoro piston exhaust joint and evacuate the air to maintain a vacuum environment (0.04-0.1 MPa) in the flask, then place the mixture in a constant temperature oil bath at 80°C in the dark and stir for 6 h to obtain a uniform and clear solution.

[0080] (2) A mixture of toluene and n-heptane was used as the raw material liquid, and the molar ratio of toluene to n-heptane in the raw material liquid was 6:4. A certain volume of silver-based low eutectic solvent was transferred into a 50 mL conical flask with a lid, and then the same volume of raw material liquid (the volume ratio of extractant / raw material liquid was 1:1) was transferred into the conical flask. The conical flask was then placed in a water bath constant temperature oscillator set at 30°C, oscillated at 200 rpm for 50 min, and then allowed to stand at the same temperature for 2 h until the upper and lower phases were completely separated. Finally, an appropriate amount of the extract phase and the raffinate phase were taken for GC analysis.

[0081] According to GC analysis, the distribution coefficient of toluene is 0.4454, the distribution coefficient of n-heptane is 0.0269, the separation selectivity is 16.56, and the extraction rate of toluene is 42.72%.

[0082] Example 6

[0083] (1) Accurately weigh a certain amount of silver bis(trifluoromethanesulfonyl)imide and add it into a brown round-bottom flask, add propionamide in a molar ratio of 1:2, connect a tetrafluoro piston exhaust joint and evacuate the air to maintain a vacuum environment (0.04-0.1 MPa) in the flask, then place the mixture in a constant temperature oil bath at 80°C in the dark and stir for 6 h to obtain a uniform and clear solution.

[0084] (2) A mixture of 1-methylnaphthalene and dodecane was used as the raw material liquid, and the molar ratio of 1-methylnaphthalene to dodecane in the raw material liquid was 1:9. A certain volume of silver-based low eutectic solvent was transferred into a 50 mL conical flask with a lid, and then the same volume of raw material liquid (the volume ratio of extractant / raw material liquid was 1:1) was transferred into the conical flask. The conical flask was then placed in a water bath constant temperature oscillator set at 30°C, oscillated at 200 rpm for 50 min, and then allowed to stand at the same temperature for 2 h until the upper and lower phases were completely separated. Finally, an appropriate amount of the extract phase and the raffinate phase were taken for GC analysis.

[0085] According to GC analysis, the distribution coefficient of 1-methylnaphthalene is 1.5378, the distribution coefficient of dodecane is 0.0013, the separation selectivity is 1167.32, and the extraction rate of 1-methylnaphthalene is 77.80%.

[0086] It should be noted that the embodiments described above are only preferred embodiments of the present invention, which are used to explain the present invention and do not constitute any limitation to the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory words, rather than restrictive words. The present invention may be modified as specified within the scope of the claims of the present invention, and the present invention may be revised without departing from the scope and spirit of the present invention. Although the present invention described therein relates to specific methods, materials and embodiments, it does not mean that the present invention is limited to the specific examples disclosed therein. On the contrary, the present invention can be extended to all other methods and applications with the same functions.

Claims

1. A silver-based deep eutectic solvent, which is composed of a silver salt as a hydrogen bond acceptor and an organic compound as a hydrogen bond donor; wherein: The organic compound serving as a hydrogen bond donor is a carbonyl organic compound or an alcohol organic compound.

2. The silver-based deep eutectic solvent according to claim 1, characterized in that The silver salt of the hydrogen bond acceptor is any one of silver bis(trifluoromethanesulfonyl)imide, silver trifluoromethanesulfonate, silver trifluoroacetate, silver tetrafluoroborate, silver hexafluorophosphate, and silver nitrate; And / or, the carbonyl organic compound is an amide organic compound or a ketone organic compound; Preferably, the amide organic compound is selected from acetamide, propionamide, N,N-dimethylformamide, N,N-dimethylacetamide, acrylamide, N-ethylacetamide, isobutyramide, N,N-dimethylacrylamide, N-methylformanilide, cyclopropanamide, N-phenylformamide, N-(hydroxymethyl)acrylamide, p-aminobenzamide, caprolactam and N-vinylcaprolactam; the ketone organic compound is selected from 2-pyrrolidone, N-methylpyrrolidone and 1,3-dimethyl-2-imidazolidinone; And / or, the alcohol organic compound is any one of ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, glycerol, triethylene glycol, and tetraethylene glycol.

3. The silver-based deep eutectic solvent according to claim 1 or 2, characterized in that The molar ratio of the silver salt to the organic compound in the silver-based deep eutectic solvent is 1:(1-8).

4. The silver-based deep eutectic solvent according to any one of claims 1 to 3, characterized in that The silver-based deep eutectic solvent has a eutectic point of less than 30°C.

5. Use of the silver-based deep eutectic solvent according to any one of claims 1 to 4 in extracting and separating unsaturated hydrocarbon mixtures.

6. The use according to claim 5, characterized in that: The applications include: Step A, using an unsaturated hydrocarbon mixture as a raw liquid and a silver-based low eutectic solvent as an extractant, performing liquid-liquid extraction, standing and separating, the upper layer is a raffinate phase containing unextracted unsaturated hydrocarbon mixture, and the lower layer is an extraction phase rich in unsaturated hydrocarbons; Step B, performing vacuum rotary evaporation on the extract phase, collecting the condensate to obtain unsaturated hydrocarbons, and the remaining liquid is a silver-based low eutectic solvent; Wherein, the unsaturated hydrocarbon mixture is a mixture of liquid unsaturated hydrocarbons and alkanes; the unsaturated hydrocarbons are olefins and / or aromatic hydrocarbons.

7. The use according to claim 6, characterized in that: The extraction process conditions are as follows: extraction temperature is 1-80°C, extraction time is 10s-180min, volume ratio of extractant to raw material liquid is 1:10-10:1, and molar content of unsaturated hydrocarbon in the mixture of liquid unsaturated hydrocarbon and alkane is 0.1%-99.9%.

8. The use according to claim 6 or 7, characterized in that: The unsaturated hydrocarbon mixture is a mixture of olefins and alkanes, wherein the olefins are liquid chain olefins and / or cyclic olefins, and the alkanes are liquid alkanes.

9. The use according to claim 6 or 7, characterized in that: The unsaturated hydrocarbon mixture is a mixture of aromatic hydrocarbons and alkanes, wherein the aromatic hydrocarbons are monocyclic and / or condensed-ring aromatic hydrocarbons, and the alkanes are liquid alkanes.

10. The use according to any one of claims 6 to 10, characterized in that: In step B, the process conditions of the reduced pressure rotary evaporation are: the vacuum degree is 0.01MPa to 0.1MPa, and the rotary evaporation temperature is 20 to 100°C.

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