Multi-cation center Gemini ionic liquid demulsifier as well as preparation method and application thereof

Abstract

The invention discloses a polycation center Gemini ionic liquid demulsifier, which has the following molecular structural formula: wherein R1 is selected from C8-C18 alkyl groups; r2 is selected from halogen; r3 and R4 are respectively and independently selected from CH3 (CH2) mO-or (CH3) 3N + (CH2) n-, m is an integer from 7 to 15, and n is 0 or 1; r5 is selected from-CH2CH2-. The polycation center Gemini ionic liquid demulsifier has excellent interfacial activity, can replace a natural surfactant on an interfacial film, remarkably reduces interfacial tension at an oil-water interface, and realizes oil-water separation; meanwhile, the demulsifying agent has the advantages of wide pH value application range, strong salinity adaptability, low demulsifying temperature, small dosage, high demulsifying efficiency and the like; and the related synthesis process is controllable, efficient demulsification for emulsions with different water contents can be realized, and the method is suitable for popularization and application.

Description

Technical Field

[0001] This invention belongs to the field of oilfield chemical technology, specifically relating to a multi-cationic-center Gemini ionic liquid demulsifier, its preparation method, and its application. Background Technology

[0002] Water-in-oil emulsions are inevitably generated during oil extraction, and these emulsions can pose a series of hazards during oil extraction, transportation, and storage. First, because water-in-oil emulsions contain impurities such as water, gas, and solid particles, they increase the difficulty and cost of extraction operations and reduce extraction efficiency. Second, the high viscosity of water-in-oil emulsions easily clogs pipes and valves, leading to reduced flow rates in transportation pipelines and increased energy consumption. Furthermore, they can cause corrosion problems, damaging transportation facilities.

[0003] In oil extraction and processing, demulsification of water-in-oil emulsions is a crucial process. Among common demulsification methods, chemical demulsification is widely used due to its advantages such as high efficiency, environmental friendliness, and cost-effectiveness. Chemical demulsifiers typically have an amphiphilic molecular structure, allowing them to rapidly migrate to the oil-water interface and achieve oil-water separation by reducing interfacial tension and breaking down the existing interfacial film. However, traditional demulsifiers using ethylene oxide and propylene oxide as raw materials suffer from problems such as complex preparation processes, potential environmental pollution, and toxicity. Furthermore, they also exhibit poor pH / salinity adaptability, require high demulsification temperatures, and their demulsification capacity cannot meet current industrial needs during oil-water separation. Summary of the Invention

[0004] The main objective of this invention is to provide a multi-cation-center Gemini ionic liquid demulsifier to solve the problems of poor pH / salinity adaptability and high demulsifier temperature in the prior art.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A multi-cationic-center Gemini ionic liquid demulsifier, the molecular structure of which is shown in formula (I):

[0007]

[0008] Among them, R1 is selected from C8 to C9. 18 The alkyl group; R2 is selected from halogens; R3 and R4 are each independently selected from CH3(CH2)mO - Or (CH3)3N + (CH2) n - Where m is an integer from 7 to 15, and n is 0 or 1; R5 is selected from -CH2CH2-.

[0009] Further, the halogen is selected from chlorine, bromine or iodine.

[0010] The preparation method of the above-mentioned multi-cationic center Gemini ionic liquid demulsifier comprises the following steps:

[0011] 1) Under an inert atmosphere, a ring-opening reaction is carried out by taking a fatty primary amine and an epoxy monomer as main raw materials to obtain a tertiary amine ring-opening product; wherein the epoxy monomer is one or more of an epoxy group trimethyl quaternary ammonium salt and an alkyl glycidyl ether;

[0012] 2) An ionization reaction is carried out by taking the obtained tertiary amine ring-opening product and a dihalide to obtain the multi-cationic center Gemini ionic liquid demulsifier.

[0013] In the above scheme, the inert gas atmosphere includes but is not limited to nitrogen, which mainly plays the role of isolating oxygen; the epoxy group trimethyl quaternary ammonium salt and / or the alkyl glycidyl ether undergoes a ring-opening reaction with the fatty primary amine to generate a tertiary amine ring-opening product, and finally the dihalide reagent links the above-mentioned tertiary amine ring-opening product together, that is, the multi-cationic center Gemini ionic liquid demulsifier. The dihalide plays a bridging role in the technical scheme, connecting two tertiary amine ring-opening products.

[0014] In the above scheme, the structure of the epoxy group trimethyl quaternary ammonium salt is shown in formula (II):

[0015] Wherein n is 0 or 1; the epoxy group trimethyl quaternary ammonium salt includes but is not limited to one or more of an epoxy propyl trimethyl quaternary ammonium salt and an epoxy butyl trimethyl quaternary ammonium salt.

[0016] In the above scheme, the structure of the alkyl glycidyl ether is shown in formula (III):

[0017] Wherein m is an integer of 7-15; the alkyl glycidyl ether includes but is not limited to one or more of C8-C 10 alkyl glycidyl ether, C 12 -C 14 alkyl glycidyl ether, glycidyl hexadecyl ether.

[0018] In the above scheme, the structure of the fatty primary amine is shown in formula (IV):

[0019] R1-NH2(IV), wherein R1 is selected from CH3(CH2) x -, and x is an integer of 7-17; the fatty primary amine includes but is not limited to one or more of 1-amino octane, dodecylamine and octadecylamine.

[0020] In the above scheme, the structure of the dihalide is shown as formula (V) :

[0021] wherein R2 is selected from halogen, and the halogen is selected from chlorine, bromine, iodine; the dihalide includes but is not limited to one or more of dichloride, dibromide and diiodide.

[0022] Specifically, the preparation method of the cationic center Gemini ionic liquid demulsifier includes the following steps: under an inert atmosphere (such as nitrogen), an epoxy monomer (epoxy trimethyl quaternary ammonium salt and / or alkyl glycidyl ether) is uniformly mixed with a fatty primary amine and an organic solvent, after a certain temperature and time of ring-opening reaction, a tertiary amine ring-opening product is obtained; a dihalide reagent is added to the ring-opening product, after a certain temperature and time of ionization reaction, the organic solvent is removed by reduced pressure distillation, and the multi-cationic center Gemini ionic liquid demulsifier is prepared.

[0023] In the above scheme, the organic solvent is one or more of toluene, xylene, N,N-dimethylformamide and dimethyl sulfoxide.

[0024] Preferably, the molar ratio of the epoxy trimethyl ammonium chloride, the alkyl glycidyl ether and the fatty primary amine is (0-2):(0-2):1; wherein the epoxy trimethyl ammonium chloride and the alkyl glycidyl ether cannot be 0 at the same time.

[0025] Preferably, the molar ratio of the tertiary amine ring-opening product and the dihalide is 2:1.

[0026] Preferably, the mixing reaction (ring-opening reaction) time of the epoxy trimethyl ammonium chloride and / or the alkyl glycidyl ether and the fatty primary amine is 4-12h, and the reaction temperature is 80-120℃.

[0027] In the above scheme, the ionization reaction uses a temperature of 80-120℃ and a time of 4-12h.

[0028] The application of the above multi-cationic center Gemini ionic liquid demulsifier in crude oil emulsion is preferably applied in a temperature range of 40-70℃ and a concentration range of 300-500mg / L.

[0029] The principle of the present application is:

[0030] The application can adjust the hydrophilic-lipophilic balance and interfacial activity of the whole molecule by adjusting the amount of quaternary ammonium salt, the length and number of hydrophobic chains, and the type of central bridging group, so that it can be adapted to different types of crude oil. Compared with traditional demulsifiers, the polycationic central ionic liquid of the application has a smaller molecular weight, and the multi-branched hydrophobic long chain makes it disperse quickly in the oil phase, can quickly migrate to the interfacial film and interact. In the special structure of the polycationic central ionic liquid, multiple cationic hydrophilic groups are tightly connected by chemical bonds through the bridging group to form a Gemini structure, greatly increasing the probability of water molecules attached to the hydrophilic group. In addition, the longer fatty carbon chain can increase the hydrophobicity of the demulsifier molecule and increase the tendency to separate from the aqueous solution. Changes in the number of polycationic centers, chemical structure, structure of dihalide, coupling position, rigidity, and chain length will make the structure of this demulsifier have diversified characteristics, thereby affecting the properties of its solution and aggregate behavior, and making it have more excellent physical and chemical properties, which can act on different types of crude oil emulsions. Compared with the tertiary amine structure, the quaternary ammonium salt structure of the application has more advantages. The reason is that the tertiary amine structure needs to gain and lose protons in the solution to be charged, while the quaternary ammonium salt structure itself is positively charged, has stronger hydrophilicity, and can promote the interaction between the polycationic central ionic liquid and the interfacial film, reduce the stability of the interfacial film, and thus facilitate oil-water separation. The Gemini demulsifier designed in the application has multiple quaternary ammonium salt structures, has stronger ability to reduce interfacial tension, lower Krafft point, and better wettability, so that the demulsifier molecule can be applied to lower temperatures and has stronger resistance to external environment.

[0031] Compared with the prior art, the application has the following beneficial effects:

[0032] 1) The synthesis process of the polycationic central Gemini ionic liquid demulsifier has controllability, can adjust the raw material addition ratio to realize the regulation of the number, structure and amphiphilicity of the cationic center, and can realize high-efficiency demulsification for different water content emulsions by changing the structure of the bridging group.

[0033] 2) The demulsifier has excellent interfacial activity, can replace the natural surfactant on the interfacial film, significantly reduce the interfacial tension at the oil-water interface, realize oil-water separation, and has the advantages of wide pH value adaptation range, strong salinity adaptability, low demulsification temperature, small addition amount, high demulsification efficiency, and wide applicability. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 The synthesis route map of the polycationic central Gemini ionic liquid demulsifier prepared in Example 1;

[0035] Figure 2The infrared spectrum of the polycationic center Gemini ionic liquid demulsifier prepared in Example 1. DETAILED DESCRIPTION

[0036] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to examples. It should be understood that the specific examples described herein are only used to explain the present application and do not limit the present application.

[0037] In the following examples, the preparation method of the polycationic center Gemini ionic liquid demulsifier includes the following steps: under a nitrogen atmosphere, mixing and uniformly mixing the epoxy trimethyl quaternary ammonium salt and / or alkyl glycidyl ether and the fatty primary amine in a solvent, and then reacting for a period of time at a set temperature to obtain a ring-opening product of tertiary amine; adding a dihalide to the ring-opening product, and continuing to react for a period of time at a set temperature, and then removing the organic solvent by reduced pressure distillation to obtain the polycationic center Gemini ionic liquid demulsifier. The mixing reaction time of the epoxy trimethyl ammonium chloride and / or alkyl glycidyl ether and the fatty primary amine is 4-12 h, and the reaction temperature is 80-120℃; too much or too high reaction time and reaction temperature can accelerate the reaction speed and improve the reaction degree, and too short time or too low temperature can cause incomplete reaction or no reaction.

[0038] In the following examples, the application of the polycationic center ionic liquid demulsifier in crude oil emulsion demulsification (application temperature is 40-70℃) includes the following steps: dissolving the polycationic center ionic liquid in a solvent to obtain a demulsifier solution, and then mixing and standing the demulsifier solution and the crude oil emulsion at 40-70℃ for 0.5-3h; after demulsification, the oil-water interface is clear, and the water phase is clear. The solvent used is one or more of ethanol, toluene and xylene; the mass fraction of the demulsifier solution is 0.1-1wt%; and the volume ratio of the demulsifier solution to the crude oil emulsion is 1:10-20.

[0039] Example 1

[0040] The present example provides a polycationic center Gemini ionic liquid demulsifier, and the molecular structure thereof is shown in formula (VI):

[0041]

[0042] The synthesis route map thereof is shown in Figure 1 , and the specific preparation steps are as follows:

[0043] Under a nitrogen atmosphere, 1 mol of 2,3-epoxypropyltrimethylammonium chloride, 1 mol of dodecyl glycidyl ether, 1 mol of dodecylamine, and 100 ml of N,N-dimethylformamide were mixed evenly and reacted at 120 °C for 8 h to obtain a tertiary amine ring-opening product. Then, 0.5 mol of dichloroethyl ether reagent was added to 1 mol of the tertiary amine ring-opening product and reacted for 12 h. The N,N-dimethylformamide was removed by distillation under reduced pressure to obtain the above-mentioned multi-cationic-center Gemini ionic liquid demulsifier.

[0044] The infrared spectrum of the demulsifier prepared in this embodiment is as follows: Figure 2 As shown. By Figure 2 It can be known that at 2923cm -1 With 2854cm -1 The peak at 1654 cm⁻¹ is due to the asymmetric and symmetric stretching vibrations of -CH₂- in alkyl primary amines. -1 The peak is generated by the -CN stretching vibration; 1463 cm⁻¹ -1 The peak at 1112 cm⁻¹ is attributed to the plane bending vibration of -OH; the peak of CO appears at 1112 cm⁻¹. -1 These results indicate that the target product was successfully synthesized.

[0045] Example 2

[0046] A multi-cation-center Gemini ionic liquid demulsifier, the preparation steps of which are as follows:

[0047] Under a nitrogen atmosphere, 1 mol of 2,3-epoxypropyltrimethylammonium chloride, 1 mol of octyl glycidyl ether, 1 mol of octadecylamine, and 100 ml of N,N-dimethylformamide were mixed thoroughly and reacted at 80°C for 12 h to obtain a tertiary amine ring-opening product. Then, 0.5 mol of dichloroethyl ether reagent was added to 1 mol of the tertiary amine ring-opening product and reacted for another 12 h. The N,N-dimethylformamide was removed by distillation under reduced pressure to obtain the aforementioned multi-cationic-center Gemini ionic liquid demulsifier.

[0048] Example 3

[0049] A multi-cation-center Gemini ionic liquid demulsifier, the preparation steps of which are as follows:

[0050] Under a nitrogen atmosphere, 2 mol of glycidyl hexadecyl ether, 1 mol of n-octylamine and 100 ml of N,N-dimethylformamide were mixed evenly and reacted at 100 °C for 10 h to obtain a tertiary amine ring-opening product. 0.5 mol of dichloroethyl ether reagent was added to 1 mol of the tertiary amine ring-opening product and reacted for 12 h. The N,N-dimethylformamide was removed by distillation under reduced pressure to obtain the above-mentioned multi-cationic-center Gemini ionic liquid demulsifier.

[0051] Example 4

[0052] A multi-cationic center Gemini ionic liquid demulsifier, the preparation steps are as follows:

[0053] Under the atmosphere of nitrogen, 2 mol of 2,3-epoxypropyl trimethyl ammonium chloride, 1 mol of dodecylamine and 100 ml of N,N-dimethylformamide are mixed uniformly, and are placed under the reaction of 100℃ for 10h to obtain the tertiary amine ring-opening product; 0.5 mol of dichloroethyl ether reagent is continuously added to 1 mol of the tertiary amine ring-opening product to react for 12h, and N,N-dimethylformamide is removed by warming and reduced pressure distillation, thereby obtaining the above multi-cationic center Gemini ionic liquid demulsifier.

[0054] Example 5

[0055] A multi-cationic center Gemini ionic liquid demulsifier, the preparation steps are as follows:

[0056] Under the atmosphere of nitrogen, 2 mol of 2,3-epoxypropyl trimethyl ammonium chloride, 1 mol of dodecylamine and 100 ml of N,N-dimethylformamide are mixed uniformly, and are placed under the reaction of 100℃ for 10h to obtain the tertiary amine ring-opening product; 0.5 mol of dichloroethyl ether reagent is continuously added to 1 mol of the tertiary amine ring-opening product to react for 12h, and N,N-dimethylformamide is removed by warming and reduced pressure distillation, thereby obtaining the above multi-cationic center Gemini ionic liquid demulsifier.

[0057] Comparative Example 1

[0058] An ionic liquid demulsifier, the preparation method is substantially the same as that of Example 1, except that the tertiary amine ring-opening product and dichloroethyl ether are reacted according to a molar ratio of 0.5:1.

[0059] Comparative Example 2

[0060] An ionic liquid demulsifier, the preparation method is substantially the same as that of Example 1, except that the second step of bridging reaction is not performed.

[0061] Comparative Example 3

[0062] A multi-cationic center Gemini ionic liquid demulsifier, the preparation steps are as follows:

[0063] Under nitrogen atmosphere, 1 mol of 2,3-epoxypropyl trimethyl ammonium chloride, 1 mol of butyl alkyl glycidyl ether, 1 mol of n-butylamine and 100 ml of N,N-dimethylformamide were mixed uniformly, and then were reacted at 120°C for 8 h to obtain a tertiary amine ring-opening product; 0.5 mol of dichloroethyl ether reagent was further added to 1 mol of the tertiary amine ring-opening product, and then was reacted for 12 h; N,N-dimethylformamide was removed by heating and reduced pressure distillation, thereby obtaining the above-mentioned polycationic Gemini ionic liquid demulsifier.

[0064] Comparative Example 4

[0065] A Gemini ionic liquid demulsifier was prepared by the following steps:

[0066] Under nitrogen atmosphere, 1 mol of epoxybutyl trimethyl ammonium chloride, 1 mol of dodecylamine and 100 ml of N,N-dimethylformamide were mixed uniformly, and then were reacted at 120°C for 8 h; 0.5 mol of dichloroethyl ether reagent and 0.6 mol of powdered sodium hydroxide were further added, and then were reacted for 12 h to obtain the Gemini ionic liquid demulsifier; the molecular structure of the Gemini ionic liquid demulsifier is shown in formula (VII):

[0067]

[0068] Test Example 1

[0069] Based on Examples 1-5 and Comparative Examples 1-4, the polycationic Gemini ionic liquid demulsifiers prepared were used to characterize the demulsification performance thereof in crude oil emulsion.

[0070] Test procedure: 150 parts by weight of crude oil (crude oil source: Changqing Oilfield, Xi'an, China, density at 25°C: 0.862 g / cm 3 , viscosity at 25°C: 7.6 mPa·s; among them, asphaltene 14 wt%, resin 6.03 wt%, wax 15.46%, water 1.6 wt%) was added to 350 parts by weight of deionized water and stirred and mixed, heated to 70°C, and then stirred at a speed of 11000 r / min for 20 min, and this process was repeated three times until a stable water-in-oil emulsion was obtained.

[0071] The polycationic ionic liquid prepared in Examples 1-5 and Comparative Examples 1-4 was added to ethanol / xylene to prepare a demulsifier solution with a mass fraction of 1%.

[0072] 1 part by volume of the above polycationic central ionic liquid solution was added to 20 parts by volume of the crude oil emulsion and mixed uniformly by shaking at 2500 rpm for 2 min, then transferred to a 40 °C water bath and allowed to stand for 12 h. The demulsification efficiency was characterized by measuring the dehydration rate (referring to the People's Republic of China Petroleum and Natural Gas Industry Standard SY / T 5281-2000), and the results are shown in Table 1.

[0073] Table 1 Demulsification results of different examples and comparative examples

[0074] Group Crude oil demulsifier (mg / L) Demulsification efficiency (%) Example 1 500 100 Example 2 500 98.0 Example 3 500 93.4 Example 4 500 89.2 Example 5 500 91.2 Comparative Example 1 500 15.2 Comparative Example 2 500 35.8 Comparative Example 3 500 11.4 Comparative Example 4 500 42.9

[0075] Note: "Crude oil demulsifier (mg / L)" in the table refers to the concentration of the polycationic central ionic liquid in the crude oil emulsion. In the evaluation experiment, the concentration of each demulsifier was 500 mg / L, the demulsification temperature was 40 °C, the demulsification pH was 7, the salinity was 0, and the demulsification time was 12 h.

[0076] As can be seen from Table 1, the crude oil demulsifiers prepared in Examples 1-5 all have very good demulsification performance. The demulsification efficiency of Example 1 is the highest.

[0077] Test Example 2

[0078] Based on the demulsifier prepared in Example 1, different concentrations of demulsifier solutions were prepared to characterize the demulsification performance of different concentrations of crude oil demulsifiers in the crude oil emulsion; the specific steps include:

[0079] 1) 150 parts by weight of crude oil was added to 350 parts by weight of deionized water and mixed by stirring, heated to 70 °C, then stirred at a speed of 11000 r / min for 20 min, and this process was repeated three times until a stable water-in-oil emulsion was obtained;

[0080] 2) Different weights of the crude oil demulsifier prepared in Example 1 were added to ethanol to prepare crude oil demulsifier solutions with mass fractions of 1.0%, 0.7%, 0.6%, 0.4%, and 0.2%, respectively, and the obtained samples were respectively marked as experimental groups 6-10; the blank group was 0%, and the sample was marked as experimental group 11;

[0081] 3) 1 part by volume of the above experimental groups 6-11 was added to 20 parts by volume of the crude oil emulsion and mixed uniformly by shaking at 2500 rpm for 2 min, then transferred to a 40 °C water bath and allowed to stand for 12 h, and the dehydration rate was measured, and the results are shown in Table 2.

[0082] Table 2 Demulsification results of experimental groups 6-11

[0083] Group Crude oil demulsifier (mg / L) Demulsification efficiency (%) Experiment Group 6 500 100 Experiment Group 7 400 88.7 Experiment Group 8 300 75.0 Experiment Group 9 200 0 Experiment Group 10 100 0 Experiment Group 11 0 0

[0084] Note: "Crude oil demulsifier (mg / L)" in the table refers to the concentration of the demulsifier in the crude oil emulsion.

[0085] As shown in Table 2, the demulsifier provided by the application has good demulsification performance, and a demulsification efficiency of 75.0% can be achieved with 300 mg / L of the crude oil demulsifier; when the concentration is 400 mg / L, the demulsification efficiency reaches 88.7%; and when the concentration is 500 mg / L, the demulsification efficiency is 100%.

[0086] Test Example 3

[0087] Based on the demulsifier prepared in Example 1, experimental groups 12-15 are sequentially established for characterizing the demulsification performance of the demulsifier under different temperatures and times; the specific steps include:

[0088] 1) 150 parts by weight of crude oil is added to 350 parts by weight of deionized water and stirred and mixed, heated to 70℃, and then stirred at a speed of 11000 r / min for 20 minutes, and this process is repeated three times until a stable water-in-oil emulsion is obtained;

[0089] 2) The demulsifier prepared in Example 1 is added to ethanol to prepare a solution with a mass fraction of 1.0%;

[0090] 3) 1 part by volume of the above-mentioned crude oil demulsifier solution is added to 20 parts by volume of the crude oil emulsion, then mixed uniformly by using a shaker at 2500 rpm for 2 min, and then transferred to a water bath kettle set at different temperatures and left to stand for 1 h, and the dehydration rate is measured, and the results are shown in Table 3.

[0091] Table 3 Demulsification results of experimental groups 12-15

[0092]

[0093] As shown in Table 3, the crude oil demulsifier provided by the application can achieve a demulsification efficiency of 100% at 60℃ and 70℃ for 3 h, a demulsification efficiency of 100% at 50℃ for 9 h, and a demulsification efficiency of 100% at 40℃ for 12 h.

[0094] Test Example 4

[0095] Based on the demulsifier prepared in Example 1, experimental groups 16-21 are sequentially established for characterizing the demulsification performance of the demulsifier under different pH conditions; the specific steps include:

[0096] 1) 150 parts by weight of crude oil is added to 350 parts by weight of deionized water and stirred and mixed, the pH value is adjusted by adding hydrochloric acid or sodium hydroxide, heated to 70℃, and then stirred at a speed of 11000 r / min for 20 minutes, and this process is repeated three times until a stable water-in-oil emulsion is obtained;

[0097] 2) The crude oil demulsifier prepared in Example 1 was added to ethanol to prepare a solution with a mass fraction of 1.0%;

[0098] 3) 1 part by volume of the above crude oil demulsifier solution was added to 20 parts by volume of crude oil emulsion with different pH values, and then mixed uniformly by using a shaker at 2500 rpm for 2 min, and then transferred to a 40℃ water bath respectively and left to stand for 12 h, and the dehydration rate was measured, and the results are shown in Table 4.

[0099] Table 4 Demulsification results of experimental groups 16-21

[0100] Group pH Demulsification efficiency (%) Experiment Group 16 2 100 Experiment Group 17 4 100 Experiment Group 18 6 100 Experiment Group 19 7 100 Experiment Group 19 8 100 Experiment Group 20 10 100 Experiment Group 21 12 98.3

[0101] As can be seen from Table 4, the crude oil demulsifier provided by the application has a higher demulsification efficiency in strong acid and strong base.

[0102] Test Example 5

[0103] Based on the demulsifier prepared in Example 1, experimental groups 22-27 were established in turn to characterize the demulsification performance of the demulsifier under salinity conditions, and the specific steps included:

[0104] 1) 150 parts by weight of crude oil was added to 350 parts by weight of deionized water and stirred to mix, the salinity was adjusted by adding sodium chloride, heated to 70℃, and then stirred at a speed of 11000 r / min for 20 min, and this process was repeated three times until a stable water-in-oil emulsion was obtained;

[0105] 2) The crude oil demulsifier prepared in Example 1 was added to ethanol to prepare a solution with a mass fraction of 1.0%;

[0106] 3) 1 part by volume of the above crude oil demulsifier solution was added to 20 parts by volume of crude oil emulsion with different pH values, and then mixed uniformly by using a shaker at 2500 rpm for 2 min, and then transferred to a 40℃ water bath respectively and left to stand for 12 h, and the dehydration rate was measured, and the results are shown in Table 5.

[0107] Table 5 Demulsification results of experimental groups 22-27

[0108] Group Salinity (mg / L) Demulsification efficiency (%) Experiment Group 22 0 100 Experiment Group 23 10000 100 Experiment Group 24 20000 100 Experiment Group 25 30000 100 Experiment Group 26 40000 100 Experiment Group 27 50000 100

[0109] As can be seen from Table 5, the demulsifier provided by the application has a higher demulsification efficiency under high salinity conditions, indicating that the demulsifier has high salt resistance.

[0110] The crude oil demulsifier provided by the application is suitable for demulsification of crude oil emulsion, and has the characteristics of simple preparation method, short demulsification time, low demulsification temperature, excellent demulsification performance, etc.

[0111] The above description of the specific embodiments of the present application is not intended to limit the scope of the present application. Any other corresponding changes and modifications made according to the technical concept of the present application should be included in the scope of protection of the claims of the present application.

Claims

1. A multi-cation-center Gemini ionic liquid demulsifier, characterized in that, Its molecular structure is shown in formula (I): Among them, R1 is selected from C8 to C9. 18 The alkyl group; R2 is selected from halogens; R3 and R4 are each independently selected from CH3(CH2). m O - Or (CH3)3N + (CH2) n - Where m is an integer from 7 to 15, and n is 0 or 1; R5 is selected from -CH2CH2-.

2. The multi-cation-center Gemini ionic liquid demulsifier according to claim 1, characterized in that, The halogen is selected from chlorine, bromine or iodine.

3. The method for preparing the multi-cation-center Gemini ionic liquid demulsifier according to claim 1 or 2, characterized in that, Includes the following steps: 1) Under an inert atmosphere, a ring-opening reaction is carried out using aliphatic primary amines and epoxy monomers as the main raw materials to obtain tertiary amine ring-opening products; wherein the epoxy monomer is one or more of epoxy trimethyl quaternary ammonium salt and alkyl glycidyl ether. 2) The obtained tertiary amine ring-opening product is subjected to an ionization reaction with the dihalogenated product to obtain the multi-cation-center Gemini ionic liquid demulsifier.

4. The preparation method according to claim 3, characterized in that, The structure of the epoxy-trimethyl quaternary ammonium salt is shown in formula (II): Where n is 0 or 1.

5. The preparation method according to claim 3, characterized in that, The structure of the alkyl glycidyl ether is shown in formula (III): Where m is an integer from 7 to 15.

6. The preparation method according to claim 3, characterized in that, The structure of the aliphatic primary amine is shown in Figure (IV): R1-NH2 (IV), where R1 is CH3(CH2). x -, where x is an integer from 7 to 17.

7. The preparation method according to claim 3, characterized in that, The structural formula of the dihalogenated product is shown in formula (V): R2 is selected from halogens.

8. The preparation method according to claim 3, characterized in that, The molar ratio of the epoxytrimethylammonium chloride, alkyl glycidyl ether, and fatty primary amine is (0-2):(0-2):1; wherein the epoxytrimethylammonium chloride and alkyl glycidyl ether cannot both be 0.

9. The preparation method according to claim 3, characterized in that, The ring-opening reaction was carried out at a temperature of 80–120°C for 4–12 hours; the ionization reaction was carried out at a temperature of 80–120°C for 4–12 hours.

10. Application of a multi-cation-center Gemini ionic liquid demulsifier in crude oil emulsions.

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