A triblock copolymer ionic liquid demulsifier and its preparation method and application

Abstract

The present invention discloses a triblock copolymer ionic liquid demulsifier, a preparation method thereof, and applications thereof. The structure of the triblock copolymer ionic liquid demulsifier is as follows: #imgabs0# wherein l is an integer of 4-8, and m is an integer of 1-3. Compared to other existing demulsifiers, the triblock copolymer ionic liquid demulsifier of the present invention can efficiently drive the demulsification of low-water-content crude oil emulsions at lower concentrations and lower temperatures; the raw materials of the triblock copolymer ionic liquid demulsifier are readily available and low in cost; the triblock copolymer ionic liquid demulsifier has good adaptability, good demulsification performance, high demulsification efficiency, and fast demulsification speed, and has broad application prospects in the petroleum industry.

Description

Technical Field

[0001] The invention relates to the technical field of oil field demulsification, in particular to a triblock copolymer ionic liquid demulsifier and a preparation method and application thereof. Background Art

[0002] In oilfields, the presence of water-in-oil emulsions (W / O emulsions) poses a significant challenge to efficient oil production. These emulsions, composed of water droplets dispersed in oil, are typically formed due to the high turbulence and mixing that occurs during oil extraction operations. Furthermore, due to the presence of natural emulsifiers in crude oil, such as resins, asphaltenes, cyclohexane acids, and nanoparticles, approximately 80% of the world's crude oil is produced in the form of emulsions. These stable crude oil emulsions have extremely high viscosities, adversely affecting crude oil production rates, equipment efficiency, and overall oilfield performance. Therefore, it is necessary to separate water from crude oil emulsions prior to refining. Crude oil emulsions can be demulsified and dehydrated through mechanical, electrical, and chemical methods. However, in practice, chemical demulsifiers are considered the primary method for breaking crude oil emulsions in the oil industry due to their efficiency and cost-effectiveness.

[0003] Currently, chemical demulsifiers used for demulsifying oil-water emulsions are primarily polymeric surfactants based on ethylene oxide and propylene oxide block copolymers. However, these demulsifiers suffer from numerous drawbacks, including complex and hazardous preparation processes, difficult raw material transportation, and high production costs. In recent years, nanomaterials, surfactants, and ionic liquids (ILs) have emerged as advanced demulsifiers, driven by environmental considerations. The processing temperatures of nanoparticle demulsifiers are often too high, indirectly leading to very high demulsification costs. Currently, surfactant demulsifiers are primarily composed of polyethers and polyurethanes, most of which are modified from EO-PO. The synthesis of EO-PO block polyethers is complex and presents significant safety risks. Ionic liquid demulsifiers have attracted research attention due to their salt, acid, and alkali resistance. However, the several ionic liquid demulsifiers currently developed have low molecular weights and are generally only suitable for crude oil emulsions with high water content. They also require long demulsification times, typically above 70°C. In addition, compared with crude oil emulsions with high water content, crude oil emulsions with low water content have more natural surfactant, which makes demulsification more difficult and generally requires a larger dose of demulsifier and a higher temperature for demulsification. Summary of the Invention

[0004] The purpose of the present invention is to overcome the above technical deficiencies and propose a triblock copolymer ionic liquid demulsifier and its preparation method and application, so as to solve the technical problems in the prior art of high demulsification temperature and large amount of demulsifier required for low water content crude oil emulsion.

[0005] In a first aspect, the present invention provides a triblock copolymer ionic liquid demulsifier, the structure of which is shown below:

[0006]

[0007] In the formula, l is an integer of 4-8, and m is an integer of 1-3.

[0008] In a second aspect, the present invention provides a method for preparing a triblock copolymer ionic liquid demulsifier, comprising the following steps:

[0009] Using waste PET plastic as raw material, a depolymerization reaction is carried out in the presence of a first solvent and a catalyst, and after a first separation and purification, ethylene terecarboxylate is obtained. The ethylene terecarboxylate is then subjected to a first halogenation reaction with a first halogenating agent, and after a second separation and purification, dihalogenated ethylene terecarboxylate is obtained.

[0010] performing a second halogenation reaction on the low molecular weight polyethylene glycol and a second halogenating agent, and obtaining a dihalogenated low molecular weight polyethylene glycol after a third separation and purification;

[0011] Polymerizing dihalogenated terephthalic acid glycol ester, dihalogenated low molecular weight polyethylene glycol and low carbon chain diterminal amine in the presence of a strong alkaline substance and a second solvent, and obtaining a triblock copolymer after a fourth separation and purification;

[0012] The triblock copolymer is subjected to ionization reaction with acetic acid to obtain a triblock copolymer ionic liquid demulsifier.

[0013] In a third aspect, the present invention provides use of the above triblock copolymer ionic liquid demulsifier in crude oil demulsification.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] Compared with other existing demulsifiers, the triblock copolymer ionic liquid demulsifier of the present invention can efficiently drive the demulsification of crude oil emulsions with low water content at lower concentrations and lower temperatures; the raw materials of the triblock copolymer ionic liquid demulsifier are easily available and the cost is low; the triblock copolymer ionic liquid demulsifier has good adaptability, good demulsification performance, high demulsification efficiency, and fast demulsification speed, and has broad application prospects in the petroleum industry. DETAILED DESCRIPTION

[0016] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0017] In a first aspect, the present invention provides a triblock copolymer ionic liquid demulsifier, the structure of which is shown below:

[0018]

[0019] In the formula, l is an integer of 4-8, and m is an integer of 1-3.

[0020] The triblock copolymer ionic liquid demulsifier provided by the present invention has the following advantages compared to traditional polymer demulsifiers: on the one hand, the large π bond structure of a benzene ring is introduced into its molecule, it can be better with the natural surface active effects such as asphaltene, resin, so as to destroy the interfacial film;On the other hand, the property of its ionic liquid can make it better dispersed at the interface, so as to destroy the interfacial film, promote film drainage and demulsification process. Meanwhile, the copolymer ionic liquid demulsifier provided by the present invention, compared to current ionic liquid demulsifier, greatly improves its molecular weight, so as to promote the coalescence and flocculation of emulsified droplets between emulsion droplets, improve demulsification efficiency. In addition, the triblock copolymer ionic liquid demulsifier provided by the present invention, its hydrophilic-lipophilic balance value can be controlled by changing the molecular weight of low molecular weight polyethylene glycol and the carbon chain length of low carbon chain di-terminal amine, so as to achieve the demulsification of crude oil emulsions of different water contents.

[0021] In a second aspect, the present invention provides a method for preparing a triblock copolymer ionic liquid demulsifier, comprising the following steps:

[0022] S1, using waste PET plastic as raw material, performing a depolymerization reaction in the presence of a first solvent and a catalyst, obtaining ethylene terecarboxylate after a first separation and purification, then subjecting the ethylene terecarboxylate to a first halogenation reaction with a first halogenating agent, and obtaining dihalogenated ethylene terecarboxylate after a second separation and purification;

[0023] S2, performing a second halogenation reaction on the low molecular weight polyethylene glycol and a second halogenating agent, and obtaining a dihalogenated low molecular weight polyethylene glycol after a third separation and purification;

[0024] S3, polymerizing dihalogenated terephthalic acid ethylene glycol ester, dihalogenated low molecular weight polyethylene glycol and a low carbon chain diterminal amine in the presence of a strong alkaline substance and a second solvent, and obtaining a triblock copolymer after a fourth separation and purification;

[0025] S4. Conducting an ionization reaction between the triblock copolymer and acetic acid to obtain a triblock copolymer ionic liquid demulsifier.

[0026] The specific reaction formula is as follows:

[0027]

[0028] The copolymer ionic liquid demulsifier prepared by the invention adopts waste PET plastic as raw material, the raw material is easily available and the economic cost is low.

[0029] In this embodiment, the first solvent described in step S1 includes but is not limited to ethylene glycol, propylene glycol, bisphenol A, etc.; the catalyst includes but is not limited to acetates such as potassium acetate, ammonium acetate, lead acetate, and zinc acetate; the mass ratio of the first solvent to the waste PET plastic is (2-4):1, and the mass ratio of the catalyst to the waste PET plastic is (0.1-0.2):100; the depolymerization reaction is carried out by reflux stirring reaction at a temperature of 180-190°C and a time of 6-10h; the first separation and purification step includes: filtering after the depolymerization reaction is completed, and then crystallizing and purifying the product.

[0030] In this embodiment, the first halogenating reagent described in step S1 includes but is not limited to phosphorus pentachloride, thionyl chloride, carbon tetrabromide, phosphorus triiodide, etc.; the mass ratio of ethylene glycol terephthalate to the first halogenating reagent is 1:(1.5-2); the temperature of the first halogenating reaction is 50-70°C, and the time of the first halogenating reaction is 4-8 hours; the second separation and purification step includes: after the first halogenating reaction is completed, the excess first halogenating reagent is evaporated.

[0031] In this embodiment, the second halogenation reagent described in step S2 includes but is not limited to phosphorus pentachloride, thionyl chloride, carbon tetrabromide, phosphorus triiodide, etc.; low molecular weight polyethylene glycol includes but is not limited to diethylene glycol, triethylene glycol, tetraethylene glycol, etc.; the mass ratio of low molecular weight polyethylene glycol to the second halogenation reagent is 1:(1.5-2); the temperature of the second halogenation reaction is 50-70°C, and the time of the second halogenation reaction is 4-8h; the third separation and purification step includes: after the second halogenation reaction is completed, the excess second halogenation reagent is evaporated.

[0032] In this embodiment, the low-carbon chain di-terminal amine described in step S3 includes but is not limited to 1,4-butanediamine, 1,5-pentanediamine, 1,6-hexanediamine, 1,7-heptanediamine, 1,8-octanediamine, etc.; the molar ratio of dihalogenated terephthalic acid glycol ester, dihalogenated low molecular weight polyethylene glycol and low-carbon chain di-terminal amine is 1:(0.8-1.2):(1.8-2.2), further 1:1:2; the second solvent includes but is not limited to N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, xylene, etc.; the usage ratio of dihalogenated terephthalic acid glycol ester to the second solvent is 1 g:(1.5-3) mL. The strong alkaline substance includes but is not limited to sodium hydroxide, potassium hydroxide, etc.; the molar ratio of dihalogenated terephthalic acid glycol ester to the strong alkaline substance is 1:(3-6); the polymerization reaction temperature is 25-60°C, and the reaction time is 8-48 hours; the fourth separation and purification step includes: filtering to remove the precipitate after the reaction, removing the solvent from the filtrate under reduced pressure distillation, and drying to obtain the triblock copolymer.

[0033] In this embodiment, the molar ratio of the triblock copolymer to acetic acid in step S4 is 1:(3-6); the temperature of the ionization reaction is 25-120° C., and the time of the ionization reaction is 4-28 hours.

[0034] In a third aspect, the present invention provides the use of the triblock copolymer ionic liquid demulsifier in crude oil demulsification, which is particularly suitable for low-temperature demulsification of crude oil emulsions with low water content.

[0035] In this embodiment, the water content of the crude oil emulsion is 10%-70%, including but not limited to 10%, 20%, 30%, 40%, 50%, 60%, 70%, etc.

[0036] In this embodiment, the applicable concentration of the triblock copolymer ionic liquid demulsifier in the crude oil emulsion is 50-300 mg / L, including but not limited to 50 mg / L, 100 mg / L, 150 mg / L, 200 mg / L, 250 mg / L, 300 mg / L, etc.

[0037] In this embodiment, the applicable temperature of the triblock copolymer ionic liquid demulsifier is 40-70°C, including but not limited to 40°C, 50°C, 60°C, 70°C, etc.

[0038] In this embodiment, the applicable pH of the triblock copolymer ionic liquid demulsifier is 1-13, including but not limited to 1, 3, 5, 7, 9, 11, 13, etc.

[0039] In this embodiment, the applicable salinity of the triblock copolymer ionic liquid demulsifier is 0-50000 mg / L.

[0040] In some specific embodiments of the present invention, the use of the triblock copolymer ionic liquid demulsifier in crude oil demulsification comprises the following steps:

[0041] dissolving the triblock copolymer ionic liquid demulsifier in a third solvent to obtain a demulsifier solution;

[0042] The demulsifier solution is mixed with the crude oil emulsion and allowed to stand at 40-70°C to achieve demulsification. After demulsification, the oil-water interface is clear, the water phase is clear, and the water content in the oil phase is low. The demulsification efficiency is also measured by measuring the dehydration rate.

[0043] The third solvent is at least one of water, alcohol and xylene; the mass fraction of the demulsifier solution is 0.1wt%-0.6wt%, the volume ratio of the demulsifier solution to the crude oil emulsion is 1:(10-20); and the standing time is 0.5-5h.

[0044] Example 1

[0045] A triblock copolymer ionic liquid demulsifier, the structure of which is shown below:

[0046]

[0047] The preparation method of the above-mentioned triblock copolymer ionic liquid demulsifier is as follows:

[0048] 50g of waste PET plastic and 150g of ethylene glycol were uniformly mixed at room temperature, followed by the addition of 0.1g of zinc acetate. After mixing, the mixture was heated to 186°C and refluxed for 8h. After the reaction, the mixture was filtered and the product was purified by crystallization to obtain ethylene terephthalate. The resulting ethylene terephthalate and 30g of tetraethylene glycol were each reacted with 45g of thionyl chloride at 65°C for 4h. After the reaction, the excess thionyl chloride was removed by rotary evaporation. Subsequently, 0.1mol of ethylene terephthalate dichloride, 0.1mol of tetraethylene glycol dichloride, and 0.2mol of 1,6-hexanediamine were dispersed in 50mL of DMF, and 0.4mol of sodium hydroxide was added. The mixture was reacted at room temperature for 24h. After the reaction, the mixture was filtered, and the filtrate was evaporated under reduced pressure to remove the solvent. The resulting triblock copolymer was then dried. The triblock copolymer was then mixed with 0.4mol of acetic acid and reacted at 100°C for 5h to obtain the desired triblock copolymer ionic liquid demulsifier.

[0049] Example 2

[0050] A triblock copolymer ionic liquid demulsifier, the structure of which is shown below:

[0051]

[0052] The preparation method of the above-mentioned triblock copolymer ionic liquid demulsifier is as follows:

[0053] 50g of waste PET plastic and 150g of ethylene glycol were uniformly mixed at room temperature, followed by the addition of 0.1g of zinc acetate. After mixing, the mixture was heated to 186°C and refluxed for 8 hours. After the reaction, the mixture was filtered and the product was purified by crystallization to obtain ethylene terephthalate. The resulting ethylene terephthalate and 30g of triethylene glycol were then reacted with 45g of thionyl chloride at 65°C for 4 hours. After the reaction, the excess thionyl chloride was removed by rotary evaporation. Subsequently, 0.1mol of ethylene terephthalate dichloride, 0.1mol of triethylene glycol dichloride, and 0.2mol of 1,6-hexanediamine were dispersed in 50mL of DMF, and 0.4mol of sodium hydroxide was added. The mixture was reacted at room temperature for 24 hours. After the reaction, the mixture was filtered, and the filtrate was evaporated under reduced pressure to remove the solvent. The resulting triblock copolymer was then dried. The triblock copolymer was then mixed with 0.4mol of acetic acid and reacted at 100°C for 5 hours to obtain the desired triblock copolymer ionic liquid demulsifier.

[0054] Comparative Example 1

[0055] A triblock copolymer demulsifier, the structure of which is shown below:

[0056]

[0057] The preparation method of the above-mentioned triblock copolymer demulsifier is as follows:

[0058] 50g of waste PET plastic and 150g of ethylene glycol were uniformly mixed at room temperature, followed by the addition of 0.1g of zinc acetate. After mixing, the temperature was raised to 186°C and refluxed for 8h. After the reaction was completed, the mixture was filtered and the product was crystallized and purified to obtain ethylene terephthalate. The obtained ethylene terephthalate and 30g of tetraethylene glycol were reacted with 45g of thionyl chloride at 65°C for 4h. After the reaction was completed, the excess thionyl chloride was evaporated. Subsequently, 0.1mol of ethylene terephthalate dichloride, 0.1mol of tetraethylene glycol dichloride, and 0.2mol of 1,6-hexanediamine were dispersed in 50mL of DMF, 0.4mol of sodium hydroxide was added, and the mixture was reacted at room temperature for 24h. After the reaction was completed, the mixture was filtered, and the filtrate was distilled under reduced pressure to remove the solvent. After drying, a triblock copolymer was obtained.

[0059] Comparative Example 2

[0060] A block copolymer ionic liquid demulsifier, the structure of which is shown below:

[0061]

[0062] The preparation method of the above-mentioned block copolymer ionic liquid demulsifier is as follows:

[0063] 30g of tetraethylene glycol and 45g of thionyl chloride were reacted at 65°C for 4 hours. After the reaction, the excess thionyl chloride was removed by rotary evaporation. Subsequently, 0.1mol of tetraethylene glycol dichloride and 0.1mol of 1,6-hexanediamine were dispersed in 50mL of DMF, and 0.2mol of sodium hydroxide was added. The mixture was allowed to react at room temperature for 24 hours. After the reaction, the mixture was filtered, and the solvent was removed by vacuum distillation of the filtrate. After drying, the block copolymer was obtained. The copolymer was then mixed with 0.2mol of acetic acid and reacted at 100°C for 5 hours to obtain the target block copolymer ionic liquid demulsifier.

[0064] Comparative Example 3

[0065] A block copolymer ionic liquid demulsifier, the structure of which is shown below:

[0066]

[0067] The preparation method of the above-mentioned block copolymer ionic liquid demulsifier is as follows:

[0068] 50g of waste PET plastic and 150g of ethylene glycol were uniformly mixed at room temperature, followed by the addition of 0.1g of zinc acetate. After mixing, the mixture was heated to 186°C and refluxed for 8 hours. After the reaction, the mixture was filtered and the product was purified by crystallization to obtain ethylene terephthalate. The resulting ethylene terephthalate was reacted with 45g of thionyl chloride at 65°C for 4 hours. After the reaction, the excess thionyl chloride was removed by rotary evaporation. Subsequently, 0.1mol of ethylene terephthalate dichloride and 0.1mol of 1,6-hexanediamine were dispersed in 50mL of DMF, and 0.2mol of sodium hydroxide was added. The mixture was allowed to react at room temperature for 24 hours. After the reaction, the mixture was filtered, and the filtrate was distilled under reduced pressure to remove the solvent. The block copolymer was then dried. The copolymer was then mixed with 0.2mol of acetic acid and reacted at 100°C for 5 hours to obtain the target block copolymer ionic liquid demulsifier.

[0069] Evaluation Test

[0070] The compounds and ionic liquids prepared in Examples 1-2 and Comparative Examples 1-3 were used as demulsifiers to demulsify crude oil emulsions, and the demulsification performance was evaluated.

[0071] 250 parts by weight of 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, asphaltenes: 14 wt %, resin: 6.03 wt %, wax: 15.46%, water: 1.6 wt %) were added to 250 parts by weight of deionized water, stirred and mixed, heated to 60°C, and then stirred at a speed of 11,000 r / min for 20 minutes, and this process was repeated three times until a stable water-in-oil emulsion was obtained.

[0072] The compounds prepared above were added into xylene as demulsifiers to prepare demulsifier solutions with a mass fraction of 0.5%.

[0073] 1 part by volume of the above demulsifier solution was added to 20 parts by volume of crude oil emulsion and mixed evenly. The mixture was then transferred to a 40°C water bath and allowed to stand for 4 hours. The demulsification efficiency was characterized by measuring its dehydration rate. The results are shown in Table 1.

[0074] Table 1 Demulsification effect of different compounds used as demulsifiers

[0075] Group Crude oil demulsifier (mg / L) Demulsification efficiency (%) Example 1 250 98.6 Example 2 250 82.1 Comparative Example 1 250 78.4 Comparative Example 2 250 53.8 Comparative Example 3 250 21.7

[0076] Note: "Crude oil demulsifier (mg / L)" in the table refers to the concentration of demulsifier in crude oil emulsion.

[0077] As shown in Table 1, the crude oil demulsifier prepared by Example 1 has the best demulsification performance;It can be found by comparing Example 1 with Example 2 that demulsification performance decreases with the reduction of polyethylene glycol molecular weight, and the reason may be to reduce the hydrophilicity of triblock copolymer ionic liquid demulsifier, causing its hydrophobicity to enhance, which is unfavorable for improving demulsification performance. Example 1 has better demulsification performance than Comparative Example 1, shows that the demulsification performance of copolymer can be significantly improved after ionization;Comparing Example 1 and Comparative Examples 2,3, it can be found that although Comparative Example 2 is hydrophilic and lipophilic, it is not containing the large π bond of benzene ring, causing its demulsification speed and poor performance;The demulsification efficiency of Comparative Example 3 is very low, because it is almost without hydrophilic part, although there are more large π bonds of benzene ring, but amphiphilicity is too poor, it is difficult to migrate to oil-water interface. It can be seen from this group of tests that the triblock copolymer ionic liquid demulsifier provided by the present invention has excellent demulsification efficiency.

[0078] The demulsification performance of the ionic liquid demulsifier in Example 1 at different concentrations, pH values, and salinities was tested using the aforementioned testing method. To avoid further elaboration, the testing method is similar to the aforementioned testing procedure, with all other conditions remaining unchanged. The difference lies in the corresponding adjustments to the concentration, pH value, and salinity during the testing process. The demulsification effects at different concentrations are shown in Table 2, those at different pH values in Table 3, and those at different salinities in Table 4. This was done to assess the suitability of each demulsifier.

[0079] Table 2 Demulsification effect of each demulsifier at different concentrations

[0080]

[0081] Among them, except that the amount of crude oil demulsifier was changed according to Table 2, other test conditions were the same as the test conditions in Table 1. As can be seen from Table 2, the demulsifier provided by the present invention has good demulsification performance. A demulsification efficiency of 99.4% can be achieved with 300 mg / L of crude oil demulsifier, which is almost 100%.

[0082] Table 3 Demulsification effect of each demulsifier at different pH values

[0083]

[0084] Except for the pH value of demulsification, which was changed according to Table 3, other test conditions were the same as those in Table 1. It can be seen that the crude oil demulsifier provided by the present invention has a high demulsification efficiency in a wide pH range.

[0085] Table 4 Demulsification effect of different demulsifiers at different salinities

[0086]

[0087] Among them, except that the salinity of demulsification was changed according to Table 4, the salinity was achieved by adding different concentrations of sodium chloride, and the other test conditions were the same as the test conditions in Table 1. It can be seen that the demulsifier provided by the present invention can have a higher demulsification efficiency under high salinity conditions, indicating that the demulsifier has high salt resistance.

[0088] Table 5 Demulsification performance of different demulsifiers at different temperatures and times

[0089]

[0090] Except for the demulsification temperature and time, which were changed according to Table 5, the other test conditions were the same as those in Table 1. It can be seen that the demulsifier provided by the present invention can achieve a demulsification efficiency of almost 100% under short-term and low-temperature conditions. In addition, this product is prepared from waste PET plastic, greatly reducing the cost of the demulsifier.

[0091] The specific embodiments of the present invention described above do not limit the scope of protection of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the scope of protection of the claims of the present invention.

Claims

1. A triblock copolymer ionic liquid demulsifier, characterized in that: Its structure is as follows: In the formula, l is an integer of 4-8, and m is an integer of 1-3.

2. A method for preparing the triblock copolymer ionic liquid demulsifier according to claim 1, characterized in that: The following steps are involved: Using waste PET plastic as raw material, performing a depolymerization reaction in the presence of a first solvent and a catalyst, obtaining ethylene terecarboxylate after a first separation and purification, then subjecting the ethylene terecarboxylate to a first halogenation reaction with a first halogenating agent, and obtaining dihalogenated ethylene terecarboxylate after a second separation and purification; performing a second halogenation reaction on the low molecular weight polyethylene glycol and a second halogenating agent, and obtaining a dihalogenated low molecular weight polyethylene glycol after a third separation and purification; The dihalogenated terephthalic acid ethylene glycol ester, the dihalogenated low molecular weight polyethylene glycol and the low carbon chain diterminal amine are polymerized in the presence of a strong alkaline substance and a second solvent, and a triblock copolymer is obtained after a fourth separation and purification; The triblock copolymer is subjected to an ionization reaction with acetic acid to obtain a triblock copolymer ionic liquid demulsifier.

3. The method for preparing the triblock copolymer ionic liquid demulsifier according to claim 2, characterized in that: The first solvent is at least one of ethylene glycol, propylene glycol, and bisphenol A; the catalyst is acetate; the mass ratio of the first solvent to the waste PET plastic is (2-4):1, and the mass ratio of the catalyst to the waste PET plastic is (0.1-0.2):100; the depolymerization reaction is carried out by reflux stirring reaction at a temperature of 180-190°C and a time of 6-10 hours.

4. The method for preparing the triblock copolymer ionic liquid demulsifier according to claim 2, characterized in that: The first halogenation reagent is at least one of phosphorus pentachloride, thionyl chloride, carbon tetrabromide, and phosphorus triiodide; the mass ratio of the ethylene glycol terephthalate to the first halogenation reagent is 1:(1.5-2); the temperature of the first halogenation reaction is 50-70°C, and the time of the first halogenation reaction is 4-8 hours.

5. The method for preparing the triblock copolymer ionic liquid demulsifier according to claim 2, characterized in that: The second halogenation reagent is at least one of phosphorus pentachloride, thionyl chloride, carbon tetrabromide, and phosphorus triiodide; the low molecular weight polyethylene glycol is at least one of diethylene glycol, triethylene glycol, and tetraethylene glycol; the mass ratio of the low molecular weight polyethylene glycol to the second halogenation reagent is 1:(1.5-2); the temperature of the second halogenation reaction is 50-70°C, and the time of the second halogenation reaction is 4-8h.

6. The method for preparing the triblock copolymer ionic liquid demulsifier according to claim 2, characterized in that: The low-carbon chain di-terminal amine is at least one of 1,4-butanediamine, 1,5-pentanediamine, 1,6-hexanediamine, 1,7-heptanediamine, and 1,8-octanediamine; the molar ratio of the dihalogenated terephthalic acid glycol ester, the dihalogenated low-molecular-weight polyethylene glycol, and the low-carbon chain di-terminal amine is 1:(0.8-1.2):(1.8-2.2); the second solvent is at least one of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, and xylene; the amount ratio of the dihalogenated terephthalic acid glycol ester to the second solvent is 1 g:(1.5-3) mL; the strong alkaline substance is at least one of sodium hydroxide and potassium hydroxide; the molar ratio of the dihalogenated terephthalic acid glycol ester to the strong alkaline substance is 1:(3-6); the temperature of the polymerization reaction is 25-60° C., and the time of the polymerization reaction is 8-48 hours.

7. The method for preparing the triblock copolymer ionic liquid demulsifier according to claim 2, characterized in that: The molar ratio of the triblock copolymer to acetic acid is 1:(3-6); the temperature of the ionization reaction is 25-120° C., and the time of the ionization reaction is 4-28 hours.

8. Use of the triblock copolymer ionic liquid demulsifier according to claim 1 in crude oil demulsification.

9. Use of the triblock copolymer ionic liquid demulsifier in crude oil demulsification according to claim 8, characterized in that: The water content of the crude oil emulsion is 10%-70%, the applicable concentration of the triblock copolymer ionic liquid demulsifier in the crude oil emulsion is 50-300 mg / L, the applicable temperature of the triblock copolymer ionic liquid demulsifier is 40-70°C, the applicable pH of the triblock copolymer ionic liquid demulsifier is 1-13, and the applicable salinity of the triblock copolymer ionic liquid demulsifier is 0-50000 mg / L.

10. Use of the triblock copolymer ionic liquid demulsifier in crude oil demulsification according to claim 8, characterized in that: The following steps are involved: dissolving the triblock copolymer ionic liquid demulsifier in a third solvent to obtain a demulsifier solution; The demulsifier solution and crude oil emulsion are mixed and allowed to stand at 40-70°C to achieve demulsification; wherein, The third solvent is at least one of water, alcohol and xylene; the mass fraction of the demulsifier solution is 0.1wt%-0.6wt%, the volume ratio of the demulsifier solution to the crude oil emulsion is 1:(10-20); and the standing time is 0.5-5h.

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