Four-branch four-center ionic liquid demulsifier, preparation method and application thereof

Abstract

The application discloses a four-branch four-center ionic liquid demulsifier and a preparation method and application thereof. The preparation method is as follows: taking an amino pyridine and a first halogenated hydrocarbon as raw materials, ionization reaction is carried out under the condition of a solvent to obtain a first reactant; the first reactant and polyethylene glycol diglycidyl ether are subjected to ring-opening reaction in a solvent B to obtain a second reactant; and the second reactant is subjected to ionization reaction with a second halogenated hydrocarbon to obtain the four-branch four-center ionic liquid demulsifier. The preparation method has a simple preparation process and is easy to implement. The demulsifier can demulsify stable oil-water emulsions under low-temperature conditions and has good demulsification effect. The structural formula of the demulsifier is as follows.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oil-water emulsion treatment, and particularly relates to a four-branched four-center ionic liquid demulsifier, a preparation method and application thereof. BACKGROUND

[0002] In the oil industry, oil-water emulsions are very common, and the properties of such emulsions are very stable due to the presence of natural surfactants. The natural active substances in crude oil mainly include asphaltene, resin, naphthenic acid and solid particles (clay or wax), and these natural surfactants can prevent water droplets from breaking, thereby stabilizing the emulsion by preventing the coalescence of water droplets in crude oil. Generally, emulsions are harmful, direct discharge will cause environmental pollution, destroy the ecology, also affect the subsequent oil production, serious corrosion of equipment, reduction of pipeline availability and increase of energy consumption, cause the reduction of recovery rate, make the production, processing and transportation of crude oil more difficult, so it is important and critical to separate the water phase from the crude oil emulsion before transportation and refining. Chemical demulsification is widely used because of its fast demulsification rate and high demulsification efficiency.

[0003] Chemical demulsification is a process of adding various chemical agents to break the emulsion by chemical reaction, so as to realize oil-water separation. The chemical demulsifier can replace the natural emulsifier adsorbed on the oil-water interface, reduce the viscoelasticity of the interface film, thereby reducing its strength, accelerating the coalescence of droplets, and finally realizing oil-water separation. Chemical demulsifiers mainly include polymer surfactants, nanoparticles and ionic liquids, for example, ethylene oxide-propylene oxide (EO-PO) block copolymer, silicon polyether, dendritic polymer, biodegradable polymer surfactant and nanoparticle-based demulsifier.

[0004] However, these demulsifiers have problems such as complex preparation process, high raw material cost, poor demulsification performance, and potential pollution risk to the environment. SUMMARY

[0005] Therefore, the present application provides a four-branched four-center ionic liquid demulsifier, a preparation method and application thereof, which solves the problems of poor demulsification performance of the demulsifier, high raw material cost of the demulsifier and poor adaptability in the prior art. The present application adopts the following technical scheme:

[0006] In a first aspect, the present application provides a four-branched four-center ionic liquid demulsifier, which has the following structure:

[0007]

[0008] wherein R1 and R2 are selected from any one of C10-C20 alkyl; X1 and X2 are selected from any one of halogen; and the amino group is located at the ortho, meta or para position of the N atom in the pyridine ring.

[0009] Preferably, R1 and R2 are the same and selected from one of C12-C18 linear alkyl; X1 and X2 are the same and selected from one of Cl ﹣ and Br ﹣ .

[0010] In a second aspect, the present application provides a method for preparing a four-branched four-center ionic liquid demulsifier, comprising the following steps:

[0011] ionic reaction in solvent A using amino pyridine and a first halogenated hydrocarbon as raw materials to obtain a first reactant;

[0012] ring-opening reaction of the first reactant and polyethylene glycol diglycidyl ether in solvent B to obtain a second reactant;

[0013] ionic reaction of the second reactant and a second halogenated hydrocarbon in solvent A to obtain the four-branched four-center ionic liquid demulsifier.

[0014] Preferably, the molar ratio of amino pyridine to the first halogenated hydrocarbon is 1:(1-2); the molar ratio of amino pyridine to polyethylene glycol diglycidyl ether is 2:1; and the molar ratio of amino pyridine to the second halogenated hydrocarbon is 1:(1-2).

[0015] Preferably, the temperature of the ionic reaction is 50-70℃, and the time is 12-14h.

[0016] Preferably, the temperature of the ring-opening reaction is 110-130℃, and the time is 8-10h.

[0017] Preferably, the amino pyridine includes one or more of 4-amino pyridine, 3-amino pyridine and 2-amino pyridine; and the halogenated hydrocarbon includes one or more of bromododecane, bromohexadecane and chloro-octadecane.

[0018] Preferably, the polyethylene glycol diglycidyl ether has an epoxy value of 0.70-0.80 mol / 100g and a viscosity of 5-25 mpa.s at 25℃.

[0019] Preferably, the solvent A and the solvent B are each independently selected from one or more of acetone, benzene and xylene.

[0020] In a third aspect, the present application provides an application of the four-branched four-center ionic liquid demulsifier in demulsification of crude oil emulsion.

[0021] Preferably, the application step comprises: dissolving the four-branched four-center ionic liquid demulsifier in solvent C to obtain a demulsifier solution, and then mixing the demulsifier solution with the crude oil emulsion for demulsification.

[0022] Preferably, the solvent C comprises one or more of water, ethanol, xylene.

[0023] Preferably, the mass fraction of the demulsifier in the demulsifier solution is 0.1wt%-0.5wt%.

[0024] The volume ratio of the demulsifier solution to the crude oil emulsion is 1:(10-20).

[0025] The demulsification temperature is 40-60℃, and the time is 60-180min.

[0026] The beneficial effects of the present application are as follows: the demulsifier of the present scheme has high surface activity, good thermal stability, good dispersibility in the oil phase, is suitable for petroleum crude oil emulsion, has high demulsification efficiency, small injection dose, low demulsification temperature, and fast demulsification rate; the method for preparing the demulsifier of the present scheme has simple steps and low raw material cost. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 The infrared spectrum of the demulsifier prepared in Example 1. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application is further described in detail below in combination with examples. It should be understood that the specific examples described herein are only used to explain the present application, and are not used to limit the present application.

[0029] The present application provides a four-branch four-center ionic liquid demulsifier, which has the following structural formula:

[0030]

[0031] wherein R1 and R2 are selected from any one of C10-C20 alkyl; X1 and X2 are selected from any one of halogen; the amino group is located at the ortho, meta or para position of the N atom in the pyridine ring.

[0032] Preferably, R1 and R2 are the same and selected from one of C12-C18 linear alkyl; further selected from C 12 H 25 , C 16 H 33 or C 18 H 37 .

[0033] Preferably, X1 and X2 are the same and selected from one of Cl ﹣ and Br ﹣ ; further preferably Br ﹣ .

[0034] Preferably, the grafted amino group is located at the para position of the N atom in the pyridine ring.

[0035] The demulsifier of the present invention is connected by polyethylene glycol diglycidyl ether to two [NH] + X ﹣ group, and then use two [NH] + X ﹣ The group and the two pyridine rings are each grafted with an R group to form a four-branched four-center structure. The demulsifier has a hydrophobic-hydrophilic-hydrophobic structure. The hydrophobic part is composed of an outer carbon chain, which makes it hydrophobic. At the same time, its four long carbon chains make it have better dispersibility and a stronger force with natural surfactants in the oil phase, which can significantly change the tension at the oil-water interface, promote water droplet coalescence, and achieve oil-water separation; the hydrophilic part in the middle has a hydroxyl group, a pyridine ring and its grafted amino group, etc., and the polyethylene glycol diglycidyl ether is also hydrophilic as a whole, so that it has hydrophilicity. In addition, the N atoms on the pyridine ring and the N atoms on the grafted amino group are ionized to obtain an ionic liquid with four centers, which further allows it to have a good demulsification effect at a lower temperature. The present invention provides a novel pollution-free four-branched four-center ionic liquid demulsifier, which can be stably present when the temperature is high and is not easily volatile, indicating that it has many advantages such as non-flammable, high thermal stability and low volatility, and can effectively reduce the tension at the oil-water interface.

[0036] The present invention provides a method for preparing a four-branch four-center ionic liquid demulsifier, comprising the following steps:

[0037] S1. Aminopyridine and a first halogenated hydrocarbon (R1X1) are used as raw materials, and an ionization reaction occurs in the presence of solvent A to obtain a first reactant (referred to as reactant 1 in the following examples); the reaction formula is as follows:

[0038]

[0039] S2. The first reactant and polyethylene glycol diglycidyl ether are mixed in solvent B and subjected to a ring-opening reaction to obtain a second reactant (referred to as reactant 2 in the following examples); the reaction formula is as follows:

[0040]

[0041] S3. The second reactant and the second halogenated hydrocarbon (R2X2) are ionized again in solvent A to obtain a four-branched four-center ionic liquid demulsifier; the reaction formula is as follows:

[0042]

[0043] The demulsifier prepared by the above method solves the problems in the prior art of poor demulsification performance for crude oil, high cost of demulsifier raw materials, and poor adaptability.

[0044] The demulsifier has the advantages of simple synthesis steps, low demulsification temperature, fast demulsification rate, and high demulsification efficiency. It has great significance for solving the problems of long demulsification time, large injection dose of chemical demulsifier, and high demulsification temperature in the chemical demulsification of crude oil emulsion in the petroleum industry. The four long carbon chains make it have better dispersibility in the oil phase and stronger force with natural interface active substances, which can significantly change the tension at the oil-water interface, promote water droplet coalescence, and realize oil-water separation.

[0045] In some embodiments, the molar ratio of the amino pyridine to the first halogenated hydrocarbon in step S1 is 1:(1-2), specifically, the molar ratio of the amino pyridine to the first halogenated hydrocarbon is 1:1.2, wherein the first halogenated hydrocarbon is appropriately excessive to ensure that the reaction proceeds sufficiently.

[0046] Preferably, in the present application, the polyethylene glycol diglycidyl ether is purchased from Macklin, CAS No. 39443-66-8, with an epoxy value of 0.70-0.80 mol / 100g and a viscosity (25°C) of 5-25 mpa.s.

[0047] In some embodiments, the molar ratio of the amino pyridine to the polyethylene glycol diglycidyl ether in step S2 is 2:1.

[0048] In some embodiments, the molar ratio of the amino pyridine to the second halogenated hydrocarbon in step S3 is 1:(1-2), specifically, the molar ratio of the amino pyridine to the second halogenated hydrocarbon is 1:1.2.

[0049] In some embodiments, the amino pyridine includes one or more of 4-amino pyridine, 3-amino pyridine, and 2-amino pyridine.

[0050] In some embodiments, the halogenated hydrocarbon includes one or more of bromododecane, bromohexadecane, and chloro-octadecane.

[0051] In some embodiments, in step S1, the temperature of the ionization reaction is 50-70°C, and suitably but not limitingly, the reaction temperature is 50°C, 52°C, 54°C, 56°C, 58°C, 60°C, 62°C, 64°C, or 66°C, and the reaction time is 12-14h, and suitably but not limitingly, the reaction time is 12h, 13h, or 14h.

[0052] In some embodiments, in step S2, the temperature of the ring-opening reaction is 110-130°C, and suitably but not limitingly, the reaction temperature is 110°C, 115°C, 120°C, 125°C, or 130°C, and the reaction time is 8-10h, and suitably but not limitingly, the reaction time is 8h, 9h, or 10h.

[0053] The reaction temperature needs to consider the solvent reflux temperature and ensure the smooth progress of the reaction, and the reaction temperature is too low, which will lead to incomplete reaction, and the reaction temperature is too high, which will evaporate the solvent, and the reaction time can be appropriately prolonged within a suitable range, which has little effect on the reaction within the above range.

[0054] The solvents A and B of the ionization reaction and the ring-opening reaction are each independently selected from one or more of acetone, benzene, xylene and the like, and the specific amount is not limited as long as the raw materials are fully dissolved.

[0055] The application of the demulsifier in the demulsification of crude oil emulsion includes the following steps: dissolving the demulsifier in solvent C to obtain a demulsifier solution, mixing the demulsifier solution with the crude oil emulsion to obtain a mixed solution, and then mixing and standing the mixed solution at a set temperature for 0.5-2h.

[0056] Preferably, the solvent C includes one or more of water, ethanol and xylene, and the mass fraction of the demulsifier in the demulsifier solution is 0.1wt%-0.5wt%.

[0057] Preferably, the volume ratio of the demulsifier solution to the crude oil emulsion is 1:10-20.

[0058] Preferably, the set temperature is 40-60℃, and the time is 60-180min.

[0059] After the demulsification, the oil-water interface is clear, the water content in the oil phase is small, the demulsification temperature is low, and the demulsifier dosage is small.

[0060] The present scheme is described below through specific examples.

[0061] Example 1

[0062] A four-branched four-center ionic liquid demulsifier is obtained by the following steps:

[0063] 4-Aminopyridine (1.88g, 0.02mol) is completely dissolved in acetone solvent (20mL), and bromohexadecane (0.024mol) is added, and the mixture is refluxed at 56℃ for 12h. Next, the mixture is naturally cooled and the solvent acetone is distilled off under reduced pressure to obtain a reactant 1, and the structural formula of the reactant 1 is as shown in formula I:

[0064]

[0065] Then, polyethylene glycol diglycidyl ether (0.01mol) is dissolved in solvent xylene (30mL), and then added to the above reactant 1, and the ring-opening reaction occurs between the reactant 1 and the polyethylene glycol diglycidyl ether under a nitrogen atmosphere at 120℃ for 8h, and then the solvent xylene is distilled off to obtain a reactant 2 as a precursor, and the reactant 2 is as shown in formula II:

[0066]

[0067] Finally, the bromo-hexadecane (0.024 mol), the reactant 2 and the acetone solvent (20 mL) were mixed again for the ionization reaction (reflux at 56 °C for 12 h) to obtain the target ionic liquid demulsifier as shown in formula III,

[0068]

[0069] Figure 1 The infrared spectrum of the demulsifier prepared in Example 1 is shown in Figure 1, in which the peaks at 2921 cm -1 and 2852 cm -1 confirm the presence of -CH3 and -CH2, the peak at 1652 cm -1 confirms the presence of C=C, the peaks at 1540 cm -1 , 1556 cm -1 and 1465 cm -1 confirm the presence of N-H and -OH. The peak at 1187 cm -1 confirms the presence of C-O-C.

[0070] Example 2

[0071] The main difference between Example 2 and Example 1 is that bromo-dodecane is used instead of bromo-hexadecane, and the other steps and conditions are the same as in Example 1.

[0072] A four-branched four-center ionic liquid demulsifier is obtained by the following steps:

[0073] The 4-aminopyridine (1.88 g, 0.02 mol) was completely dissolved in acetone (20 mL), and the bromo-dodecane (0.024 mol) was added, and the mixture was refluxed at 56 °C for 12 h. Next, the mixture was naturally cooled and the acetone was distilled off under reduced pressure to obtain the reactant 1. Then, the polyethylene glycol diglycidyl ether (0.01 mol) was dissolved in xylene (30 mL) and reacted with the reactant 1 under a nitrogen atmosphere at 120 °C for 8 h of stirring, and then the xylene was distilled off to obtain the reactant 2 as a precursor. Finally, the bromo-dodecane (0.024 mol), the reactant 2 and the acetone solvent (20 mL) were mixed again for the ionization reaction (reflux at 56 °C for 12 h) to obtain the target ionic liquid demulsifier.

[0074] Example 3

[0075] The main difference between Example 3 and Example 1 is that chloro-octadecane is used instead of bromo-hexadecane, and the other steps and conditions are the same as in Example 1.

[0076] A four-branch four-center ionic liquid demulsifier is obtained by the following steps:

[0077] 4-Aminopyridine (1.88 g, 0.02 mol) was completely dissolved in acetone (20 mL), and octadecane chloride (0.024 mol) was added, and the mixture was refluxed at 56°C for 12 h. Next, the mixture was naturally cooled and the acetone was distilled off under reduced pressure to obtain reactant 1. Then, polyethylene glycol diglycidyl ether (0.01 mol) was dissolved in xylene (30 mL) and reacted with reactant 1 under a nitrogen atmosphere at 120°C for 8 h. The xylene was then distilled off to obtain reactant 2 as a precursor. Finally, octadecane chloride (0.024 mol), reactant 2, and acetone solvent (20 mL) were mixed and ionized (refluxed at 56°C for 12 h) to obtain the target ionic liquid demulsifier.

[0078] Example 4

[0079] A four-branch four-center ionic liquid demulsifier is obtained by the following steps:

[0080] 4-Aminopyridine (1.88 g, 0.02 mol) was completely dissolved in acetone (20 mL), and octadecane chloride (0.024 mol) was added, and the mixture was refluxed at 52 ° C for 12 h. Next, the mixture was cooled naturally and the acetone was distilled off under reduced pressure to obtain reactant 1. Then, polyethylene glycol diglycidyl ether (0.01 mol) was dissolved in xylene (30 mL) and reacted with reactant 1 under a nitrogen atmosphere at 120 ° C for 8 h, and then the xylene was distilled off to obtain reactant 2 as a precursor. Finally, octadecane chloride (0.024 mol), reactant 2 and acetone solvent (20 mL) were mixed and ionized (refluxed at 52 ° C for 12 h) to obtain the target ionic liquid demulsifier.

[0081] Example 5

[0082] A four-branch four-center ionic liquid demulsifier is obtained by the following steps:

[0083] Dissolve 4-aminopyridine (1.88 g, 0.02 mol) completely in xylene (20 mL) and add chlorooctadecane (0.024 mol), reflux the mixture at 120°C for 12 h. Next, cool the mixture naturally and distill off the xylene under reduced pressure to obtain the reactant 1. Then, dissolve polyethylene glycol diglycidyl ether (0.01 mol) in xylene (30 mL) and react with the reactant 1 under nitrogen atmosphere at 120°C for 8 h, and then distill off the xylene to obtain the reactant 2 as a precursor. Finally, mix chlorooctadecane (0.024 mol), the reactant 2 and an acetone solvent (20 mL) to perform ionization reaction (reflux at 56°C for 12 h) to obtain the target ionic liquid demulsifier.

[0084] Test Example

[0085] To avoid repetition, the crude oil emulsion used in the following tests is prepared according to the following steps:

[0086] Add 150 parts by weight of crude oil into 350 parts by weight of deionized water, mix and heat to 60°C, and then stir at a speed of 11000 r / min for 20 min, repeat the stirring process one to three times until a stable water-in-oil emulsion, i.e. a crude oil emulsion, is obtained. To ensure the accuracy of the test, the crude oil emulsion prepared by repeating the stirring process three times is used in the present application, and the mixture is more uniform.

[0087] 1. Commercial demulsifier K3800 is used as Comparative Example 1, PE10100 is used as Comparative Example 2, PDB9904 is used as Comparative Example 3, and PDB9360 is used as Comparative Example 4. The demulsification performance of the demulsifiers prepared in Examples 1-5 in the crude oil emulsion is tested and compared, and the specific steps are as follows:

[0088] The ionic liquids prepared in Examples 1-5 are respectively added into xylene / ethanol (75:25) to prepare a solution with a mass fraction of 0.5%, i.e. Experimental Groups 1-5. Commercial demulsifiers K3800, PE10100, PDB9904 and PDB9360 are respectively used as Comparative Groups 1-4 for comparison experiments. The commercial demulsifiers in the comparative examples are added into xylene / ethanol (75:25) to prepare a solution with a mass fraction of 0.5%, i.e. Comparative Groups 1-4.

[0089] The Experimental Groups 1-5 and Comparative Groups 1-4 are added into the above-mentioned crude oil emulsion in a volume ratio of 1:19, then fully shaken and mixed uniformly, and then transferred to a 40°C water bath for standing for 2 h. The dehydration rate is measured, and the results are shown in Table 1.

[0090] Table 1 Demulsification results of Experimental Groups 1-5 and Comparative Groups 1-4

[0091] Group Demulsifier (mg / L) Demulsification efficiency (%) Experiment group 1 250 98.34 Experiment group 2 250 97.0 Experiment group 3 250 95.84 Experiment group 4 250 94.27 Experiment group 5 250 95.25 Comparison group 1 250 71.43 Comparison group 2 250 88.43 Comparison group 3 250 90.83 Comparison group 4 250 81.16

[0092] Note: "Demulsifier (mg / L)" in the table refers to the concentration of the demulsifier in the crude oil emulsion.

[0093] From Table 1, it can be seen that the demulsifiers prepared in Examples 1-5 all have very good demulsification performance, but due to the differences in preparation conditions, such as the type of halogenated hydrocarbon, reaction temperature, and type of solvent, the demulsification efficiency will be different. For example, from Examples 1 and 2, it can be seen that appropriate enhancement of the length of the carbon chain is beneficial to the improvement of the demulsification performance, and from Example 3, it can be seen that if the carbon chain is too long, there will be stronger hydrophobicity, thereby reducing the demulsification efficiency. The reaction conditions of Examples 4 and 5 are changed, so the demulsification efficiency is different. Compared with the commercial demulsifiers in the comparative group, the demulsification ability of the demulsifiers provided by the present application also has more excellent effect.

[0094] 2. Solutions of different concentrations of the demulsifier prepared based on Example 1 are used to characterize the demulsification performance of the demulsifier in the crude oil emulsion at different concentrations.

[0095] Different weight parts of the demulsifier prepared in Example 1 are added to dimethylbenzene / ethanol (75:25) to prepare demulsifiers with mass fractions of 0.5%, 0.4%, 0.3%, 0.2%, and 0.1%, respectively, and the obtained samples are recorded as experimental groups 6-10; the blank group is 0%, and the sample is recorded as experimental group 11.

[0096] 1 volume part of the above experimental groups 6-11 is added to 19 volume parts of the crude oil emulsion, then mixed uniformly by oscillation, and then transferred to a 40℃ water bath for 2h, and the dehydration rate is measured, and the results are shown in Table 2.

[0097] Table 2 Demulsification results of experimental groups 6-11

[0098] Group Demulsifier (mg / L) Demulsification efficiency (%) Experiment group 6 250 98.34 Experiment group 7 200 96.85 Experiment group 8 150 93.45 Experiment group 9 100 90.84 Experiment group 10 50 0 Experiment group 11 0 0

[0099] Note: "Demulsifier (mg / L)" in the table refers to the concentration of the demulsifier in the crude oil emulsion.

[0100] From Table 2, it can be seen that the demulsifier provided by the present application has good demulsification performance, and a demulsification efficiency of 93.45% can be achieved with 150mg / L of the demulsifier, the demulsification efficiency reaches 96.85% when the concentration is 200mg / L, and the demulsification efficiency is 98.34% when the concentration is 250mg / L.

[0101] 3. Experimental groups 12-14 are established in turn based on the demulsifier prepared in Example 1, for characterizing the demulsification performance of the demulsifier at different temperatures and times.

[0102] The demulsifier prepared in Example 1 was added to xylene / ethanol (75:25) to prepare a solution with a mass fraction of 0.5%.

[0103] 1 volume part of the above demulsifier was added to 19 volume parts of the crude oil emulsion and then mixed uniformly by oscillation, and then transferred to a water bath set at different temperatures and allowed to stand for 3 h, and the dehydration rate was measured, and the results are shown in Table 3.

[0104] Table 3 demulsification results of experimental groups 12-14

[0105]

[0106]

[0107] As can be seen from Table 3, the demulsifier provided by the present application can achieve a demulsification efficiency of 93.02% at 40℃ for 120 min, a demulsification efficiency of 94.24% at 50℃ for 120 min, a demulsification efficiency of 87.1% at 60℃ for 60 min, and a demulsification efficiency of 94.08% at 90 min.

[0108] In summary, the demulsifier of the present application has the advantages of simple synthesis steps, low demulsification temperature, fast demulsification rate, and high demulsification efficiency. It has great significance for solving the problems of long demulsification time, large injection dose of chemical demulsifiers, and high demulsification temperature in the petroleum industry. The four long carbon chains make it have better dispersibility in the oil phase and stronger force with natural interfacial active substances, which can significantly change the tension at the oil-water interface, promote water droplet coalescence, and achieve oil-water separation.

[0109] The above, only for the present application is the preferred specific implementation, but the scope of protection of the present application is not limited to this, any familiar with the technology in the art of skilled person in the technical range disclosed by the present application, can easily think of changes or replacement, should be covered in the scope of protection of the present application.

Claims

1. A four-branched four-center ionic liquid demulsifier, characterized in that: Its structural formula is shown below: wherein R1 and R2 are each selected from any one of C10-C20 alkyl groups; X1 and X2 are each selected from any one of halogen groups; and the amino group is located at the ortho, meta or para position relative to the nitrogen atom in the pyridine ring; The preparation method of the demulsifier comprises the following steps: Aminopyridine and a first halogenated hydrocarbon are used as raw materials, and an ionization reaction occurs in solvent A to obtain a first reactant; The first reactant and polyethylene glycol diglycidyl ether undergo a ring-opening reaction in solvent B to obtain a second reactant; The second reactant and the second halogenated hydrocarbon undergo ionization reaction in solvent A to obtain a four-branched four-center ionic liquid demulsifier; The polyethylene glycol diglycidyl ether has an epoxy value of 0.70 to 0.80 mol / 100 g and a viscosity of 5 to 25 mPa.s at 25° C.

2. The four-branched four-center ionic liquid demulsifier according to claim 1, characterized in that: R1 and R2 are the same and are selected from one of C12-C18 straight chain alkyl groups; X1 and X2 are the same and are selected from Cl ﹣ and Br ﹣ One of them.

3. The four-branched four-center ionic liquid demulsifier according to claim 1, characterized in that: The molar ratio of aminopyridine to the first halogenated hydrocarbon is 1:(1-2); the molar ratio of aminopyridine to polyethylene glycol diglycidyl ether is 2:1; and the molar ratio of aminopyridine to the second halogenated hydrocarbon is 1:(1-2).

4. The four-branched four-center ionic liquid demulsifier according to claim 1, characterized in that: The temperature of the ionization reaction is 50°C to 70°C, and the time is 12 to 14 hours.

5. The four-branched four-center ionic liquid demulsifier according to claim 1, characterized in that: The temperature of the ring-opening reaction is 110-130° C., and the time is 8-10 hours.

6. The four-branched four-center ionic liquid demulsifier according to claim 1, characterized in that: The aminopyridine is selected from one or more of 4-aminopyridine, 3-aminopyridine and 2-aminopyridine; the halogenated hydrocarbon is selected from one or more of brominated dodecane, brominated hexadecane and chlorooctadecane.

7. The four-branched four-center ionic liquid demulsifier according to claim 1, characterized in that: Solvent A and solvent B are independently selected from one or more of acetone, benzene and xylene.

8. Use of the demulsifier according to any one of claims 1 to 7 in demulsifying crude oil emulsion.

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