Ternary block copolymerization low-temperature demulsifier, preparation method and application in oil-water separation

Abstract

The invention discloses a ternary block copolymerization low-temperature demulsifier, a preparation method and an application in oil-water separation, polyether and anhydride are dissolved in a solvent to obtain a mixed solution, and the mixed solution is subjected to a reaction at 70-90 DEG C for 1-3 h to obtain a polyether anhydride solution; the preparation method comprises the following steps: adding epoxy chloropropane, dimethylamine, polyethyleneimine and an end-capping reagent into a polyether anhydride solution, and reacting at 90-100 DEG C for 4-5 hours to obtain a binary block copolymerization demulsifier; and adding polysiloxane into the binary block copolymerization demulsifier, and reacting at 110-140 DEG C for 4-5 hours to obtain the ternary block copolymerization low-temperature demulsifier. When 50 ppm of the demulsifier is added at 40 DEG C, the demulsifier can quickly demulsify a high polymer heavy oil-water system and remove water. The demulsifier disclosed by the invention is simple in synthesis step and mild in condition, has a potential application prospect and is expected to be applied to large-scale production of oil fields.

Description

Technical Field

[0001] The invention belongs to the field of oilfield chemical synthetic materials, and in particular relates to a ternary block copolymer low-temperature demulsifier, a preparation method thereof and application thereof in oil-water separation. Background Art

[0002] In the process of crude oil drilling and production, a variety of surfactants are usually injected to improve the oil and gas recovery rate. A large amount of natural surfactants (asphaltenes, colloids) in heavy oil interact with water drive and polymer drive to produce ultra-stable W / O emulsions. Asphaltene and colloids make the structure of heavy oil more stable and the viscosity higher, which leads to serious pipeline corrosion and increases the cost of oil storage and transportation. Therefore, it is urgent to develop efficient heavy oil demulsifiers. At present, the demulsifiers suitable for heavy oil mainly include multifunctional polyether esters, biomass-based ionic liquids, acrylate copolymers, etc.

[0003] Atta et al. (Journal of Molecular Liquids, 2018, 252: 311-320) used natural cashew oil as raw material and prepared biomass-based ionic liquid DECA from cashew oil using polyamine and ethylene glycol. For high-polymer thick oil emulsion, the optimized demulsifier use conditions were 100 ppm DECA at 80 °C and 40 min for complete dehydration. However, the high temperature of demulsifier leads to increased energy consumption, which is not conducive to industrial production. Summary of the invention

[0004] In order to solve the problem of high demulsification temperature of demulsifiers in the prior art, the purpose of the present invention is to provide a ternary block copolymer low-temperature demulsifier and a preparation method and application in oil-water separation. The demulsifier prepared by the method can quickly demulsify at a low temperature of 40°C.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows: A method for preparing a ternary block copolymer low-temperature demulsifier comprises the following steps: Dissolving polyether and acid anhydride in a solvent to obtain a mixed solution, reacting the mixed solution at 70-90° C. for 1-3 hours to obtain a polyether acid anhydride solution; After adding epichlorohydrin, dimethylamine, polyethyleneimine and a capping agent to the polyether anhydride solution, reacting at 90-100° C. for 4-5 hours, a binary block copolymer demulsifier is obtained; Add polysiloxane to the binary block copolymer demulsifier and react at 110-140° C. for 4-5 hours to obtain a ternary block copolymer low-temperature demulsifier.

[0006] A further improvement of the present invention is that the polyether is PE-6800, PE-10500 or RPE174; the acid anhydride is maleic anhydride; and the solvent is anhydrous ethanol.

[0007] A further improvement of the present invention is that the molar ratio of polyether, acid anhydride and solvent is (62-63): (5000-6000): (2200-3000).

[0008] A further improvement of the present invention is that the polyethyleneimine is polyethylene polyamine with a molecular weight of 600-1800.

[0009] A further improvement of the present invention is that the amount of the end-capping agent is 4-5 times the amount of dimethylamine.

[0010] A further improvement of the present invention is that the end-capping agent is an alkyl bromide or benzyl bromide having 2 to 12 carbon atoms. A further improvement of the present invention is that the molar ratio of polyether, epichlorohydrin, dimethylamine and polyethyleneimine is (7-8): (50-60): (100-200): (70-80).

[0011] A further improvement of the present invention is that the molar ratio of the binary block copolymer demulsifier to the polysiloxane is (10-20): (6-7).

[0012] A ternary block copolymer low-temperature demulsifier.

[0013] Application of a ternary block copolymer low-temperature demulsifier in oil-water separation.

[0014] Compared with the prior art, the present invention has the following beneficial effects: The present invention constructs a demulsifier composed of silicon groups by adding an end-capping agent to a binary block copolymer demulsifier system. Since the demulsifier has a large number of hydroxyls due to quaternary ammonium salt and polyether, it has high reactivity, and the effect between a large number of hydroxyls and asphaltene promotes demulsification. In addition, the oligomeric quaternary ammonium salt has a positive charge, and the surface of the oil-water emulsion has a negative charge, which can neutralize the interfacial charge and reduce the repulsive force between the emulsions. The quaternary ammonium salt and the cationic salt modified by the polyether rely on the positive charge neutralization mechanism to realize the destabilization flocculation of the oil droplets in the demulsification and dehydration process, and the oil droplets coalesce to form large oil droplets, and the oil-water two phases are separated. At the same time, the coalescence demulsification between the oil droplets lags behind the flocculation of the oil droplets, and the hindering effect of the polymer in the sewage can be effectively overcome, so that the high-polymerization thick oil emulsion is quickly separated. The present invention has simple synthesis steps and mild conditions, and has potential application prospects in terms of practicality, greenness, high efficiency and difficulty of synthesizing demulsifiers, and is expected to be applied to large-scale production in oil fields. The synthesis route of the ternary block copolymer low-temperature demulsifier of the present invention is simple and the conditions are mild. Compared with the traditional polyether and polyamine demulsifiers that need to be synthesized under high temperature and high pressure conditions, the synthesis conditions in the present invention are simple, the polymerization reaction can be initiated under normal pressure, and the molecular weight is moderate, the stability is good, and high-temperature synthesis operation is avoided.

[0015] Furthermore, the present invention uses different end-capping agents such as bromoalkyl or benzyl bromide with 2 to 12 carbon atoms, because the oily chain makes the molecule more amphiphilic and wettable at the oil-water interface, and the alkyl chains of different lengths have different hydrophobic effects, which conforms to the size effect. In the demulsification process, the organosilicon group is used to break the π-π stacking of asphaltene at the oil-water interface. When the ammonium salt ions neutralize the negative charge in the crude oil, the bromide ions (Br ⁻ ) can form complexes with ions in asphaltene, and by adjusting the charge distribution in the emulsion, help destroy the adsorption of the emulsifier on the interface, thereby breaking the rigid membrane of asphaltene, softening the membrane, and better agglomerating water droplets, thereby achieving a better oil-water separation effect.

[0016] Furthermore, after adding epichlorohydrin, dimethylamine and polyethyleneimine in the present invention, the reaction temperature should not exceed 100°C. If the temperature is too high, the molecular viscosity will be affected. If the molecular viscosity is too large, the demulsification efficiency will be affected. If the temperature is lower than 90°C, the degree of polymerization will be too low and the shedding of the Cl atom of epichlorohydrin will be affected. Moreover, the reaction time should not exceed 5h. If the time is too long, the viscosity and the degree of crosslinking will be too high, which will affect the molecular weight and demulsification efficiency. If the time is too short, the reaction will be incomplete, which may lead to reaction failure.

[0017] The ternary block copolymer low-temperature demulsifier of the present invention is used for efficient demulsification of heavy oil. The prepared ternary block copolymer low-temperature demulsifier has the following characteristics: (1) The oxygen groups in the demulsifier, i.e., the ether groups, can break the hydrogen bonds and π-π stacking between asphaltene and combine with water molecules to form new and stronger hydrogen bonds. The reconstruction of this hydrogen bond promotes the rupture of the membrane at the oil-water interface, thereby causing the water droplets in the oil phase to coalesce and break the emulsion.

[0018] (2) The amine skeleton is alternately inserted into the fragment containing the ether group. Its structure promotes the multi-point extension of the demulsifier molecule, which is beneficial for the demulsifier molecule to spread at the oil-water interface and enhances the ability of the demulsifier molecule to break the rigid film of the interface. (3) The organosilicon demulsifier can quickly polymerize the oil droplets, allowing these molecules to quickly form an adsorption layer on the surface of the oil droplets, weakening the electrostatic repulsion between the oil droplets and the stable interface film, allowing small oil droplets to polymerize into large oil droplets, accelerating separation. Therefore, the present invention combines the advantages of the three blocks to provide a low-temperature heavy oil demulsifier with good salt resistance, fast dehydration, and obvious demulsification effect at 40°C.

[0019] The ternary block copolymer low-temperature demulsifier prepared in the present invention can neutralize the particles in the sewage, greatly reducing the repulsive force between molecules, destabilizing and precipitating the sewage particles, and thus facilitating the treatment of oily sewage. Compared with other types of demulsifiers, the ternary block copolymer low-temperature demulsifier synthesized in the present invention can achieve sewage purification while ensuring efficient demulsification. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to make the synthesis mechanism, technical scheme and application effect of the present invention clearer, the present invention provides the following drawings: Figure 1 The infrared spectrum of the ternary block copolymer low-temperature demulsifier of the present invention; Figure 2 is the nuclear magnetic resonance hydrogen spectrum of the ternary block copolymer low-temperature demulsifier of the present invention; Figure 3 This is a diagram of the demulsification effect of different types of demulsifiers at 50ppm for 1h at 40℃ under produced oil from an oil production plant in a block in northern Shaanxi; Figure 4 This is a diagram showing the demulsification effect of different doses of JST2 at 40℃ for 1h under produced oil from an oil production plant in a block in northern Shaanxi. DETAILED DESCRIPTION

[0021] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thoroughly and comprehensively understood.

[0022] A method for preparing a ternary block copolymer low-temperature demulsifier of the present invention comprises the following steps: 1) Pour polyether (PE-6800, PE-10500 or RPE1740) and acid anhydride (maleic anhydride) into a 500 mL three-necked flask, dissolve the two in 150 mL anhydrous ethanol to obtain a mixed solution, and react the mixed solution at 70-90° C. with constant temperature stirring for 1-3 hours to form ether bonds to obtain a polyether anhydride solution; the molar ratio of polyether, acid anhydride and anhydrous ethanol is (62-63): (5000-6000): (2200-3000).

[0023] 2) Add epichlorohydrin, dimethylamine, polyethyleneimine and end-capping agent to the polyether anhydride solution, and react for 4-5 hours under the conditions of heating in an oil bath at 90-100°C and stirring, and then rotary evaporate at 0.09Mpa and 75°C to obtain a binary block copolymer demulsifier. The amount of the end-capping agent is 4-5 times the amount of dimethylamine. The end-capping agent is bromoalkane C n H 2n+1 (n=2~12) or benzyl bromide. The molar ratio of polyether, epichlorohydrin, dimethylamine and polyethyleneimine is (7-8): (50-60): (100-200): (70-80).

[0024] 3) Add polysiloxane (polysiloxane manufacturer: Shanghai MacLean Biochemical Technology Co., Ltd.) to the above binary block copolymer demulsifier, and heat to 110-140°C for 4-5 hours under constant temperature stirring to obtain a ternary block copolymer low-temperature demulsifier suitable for efficient demulsification of heavy oil.

[0025] The molar ratio of the binary block copolymer demulsifier to the polysiloxane is (10-20): (6-7).

[0026] The reaction mechanism of the present invention is: 1. The mechanism of preparing the binary block copolymer demulsifier in step 2) is as follows: the reaction is a nucleophilic addition reaction, the lone pair of electrons of the N atom of dimethylamine attacks the CO bond of epichlorohydrin, causing the CO ring to open, and the chlorine-containing end of the intermediate attacks the hydroxyl group of propylene oxide, and finally the bromine atom on the emulsion falls off, and the generated negative carbon ion attacks the active hydrogen connected to the N atom on the C of the intermediate, generating a polyquaternary ammonium salt-modified polyether, i.e., a binary block copolymer demulsifier.

[0027] 2. The reaction between polyether and polysiloxane in the binary block copolymer demulsifier is a nucleophilic addition reaction. The lone pair of electrons on the ether bond of the polyether attacks the Si-H bond to form a Si-O bond, generating a polysiloxane polyether quaternary ammonium salt, i.e., a ternary block copolymer low-temperature demulsifier.

[0028] Example 1 1) Pour polyether PE-6800 and acid anhydride (maleic anhydride) into a 500mL three-necked flask, then add 150mL of anhydrous ethanol to obtain a mixed solution of maleic anhydride and PE6800, and stir the mixed solution of maleic anhydride and PE6800 at 80°C for 2h to form an ether bond to obtain a mixture; PE6800, acid anhydride (maleic anhydride) and anhydrous ethanol are in a molar ratio of 62:5000:2300.

[0029] 2) Add the end-capping agent to the above mixture, continue to add epichlorohydrin, dimethylamine and polyethylene polyamine (molecular weight 600) to the system, and react for 4 hours under the conditions of heating and stirring in a 90°C oil bath, and then rotary evaporate at 0.09Mpa and 75°C to obtain a binary block copolymer demulsifier. Among them, the amount of the end-capping agent is 4 times the amount of dimethylamine substance. The end-capping agent is 0.2 mol of bromohexane. The molar ratio of polyether, epichlorohydrin, dimethylamine and polyethyleneimine (molecular weight 600) is 7:50:100:70.

[0030] 3) Add polysiloxane (polysiloxane manufacturer: Shanghai MacLean Biochemical Technology Co., Ltd.) to the above binary block copolymer demulsifier, and heat to 130°C for reaction for 5 hours under constant temperature stirring to obtain a ternary block copolymer low-temperature demulsifier, denoted as JST2 (yellow transparent viscous liquid), wherein the molar ratio of the binary block copolymer demulsifier to the polysiloxane is 10:6.

[0031] Example 2 The same as Example 1, except that in step 2), the end-capping agent is ethyl bromide, and a ternary block copolymer low-temperature demulsifier is obtained, which is recorded as JST-3 (brown-yellow transparent viscous liquid).

[0032] Example 3 The same as Example 1, except that in step 2), the end-capping agent is benzyl bromide, and a ternary block copolymer low-temperature demulsifier is obtained, which is recorded as JST-4 (red transparent viscous liquid).

[0033] Example 4 The same as Example 1, except that in step 2), the end-capping agent is octane bromide, and a ternary block copolymer low-temperature demulsifier is obtained, which is recorded as JST-5 (reddish brown viscous paste solid).

[0034] Example 5 The same as Example 1, except that in step 2), the end-capping agent is dodecane bromide, and a ternary block copolymer low-temperature demulsifier is obtained, which is recorded as JST-6 (yellow-brown viscous paste solid).

[0035] Example 6 1) Pour polyether PE-10500 and acid anhydride (maleic anhydride) into a 500mL three-necked flask, then add 150mL of anhydrous ethanol to obtain a mixed solution, and stir the mixed solution at 70°C for 3h to react to form an ether bond to obtain a mixture; the molar ratio of PE-10500, acid anhydride and anhydrous ethanol is 62:5000:3000.

[0036] 2) Add the end-capping agent to the above mixture, continue to add epichlorohydrin, dimethylamine and polyethylene polyamine (molecular weight 1800) to the system, and react for 4 hours under the conditions of heating and stirring in an oil bath at 100°C, and then rotary evaporate at 0.09Mpa and 75°C to obtain a binary block copolymer demulsifier. Among them, the amount of the end-capping agent is 4 times the amount of dimethylamine substance. The end-capping agent is ethyl bromide. The molar ratio of polyether, epichlorohydrin, dimethylamine and polyethyleneimine (molecular weight 600) is 8:60:100:70.

[0037] 3) Add polysiloxane (polysiloxane manufacturer: Shanghai MacLean Biochemical Technology Co., Ltd.) to the above binary block copolymer demulsifier, and heat to 120°C for reaction for 5 hours under constant temperature stirring to obtain a ternary block copolymer low-temperature demulsifier. The molar ratio of the binary block copolymer demulsifier to the polysiloxane is 10:7.

[0038] Example 7 1) Pour polyether RPE1740 and acid anhydride (maleic anhydride) into a 500 mL three-necked flask, then add 150 mL of anhydrous ethanol to obtain a mixed solution, and stir the mixed solution at 90°C for 1 hour to react to form an ether bond to obtain a mixture; the molar ratio of RPE1740, acid anhydride and anhydrous ethanol is 63:6000:2600.

[0039] 2) Add the end-capping agent to the above mixture, continue to add epichlorohydrin, dimethylamine and polyethylene polyamine (molecular weight 1000) to the system, and react for 5 hours under the conditions of heating and stirring in a 90°C oil bath, and then rotary evaporate at 0.09Mpa and 75°C to obtain a binary block copolymer demulsifier. Among them, the amount of the end-capping agent is 4.5 times the amount of dimethylamine substance. The end-capping agent is dodecane bromide. The molar ratio of polyether, epichlorohydrin, dimethylamine and polyethyleneimine (molecular weight 600) is 7:60:100:70.

[0040] 3) Add polysiloxane (polysiloxane manufacturer: Shanghai MacLean Biochemical Technology Co., Ltd.) to the above binary block copolymer demulsifier, and heat to 140°C for reaction for 4 hours under constant temperature stirring to obtain a ternary block copolymer low-temperature demulsifier. The molar ratio of the binary block copolymer demulsifier to the polysiloxane is 20:6.

[0041] Example 8 1) Pour polyether PE-10500 and acid anhydride (maleic anhydride) into a 500mL three-necked flask, then add 150mL of anhydrous ethanol to obtain a mixed solution, and stir the mixed solution at 75°C for 2h to react to form an ether bond to obtain a mixture; the molar ratio of PE-10500, acid anhydride and anhydrous ethanol is 62:6000:2200.

[0042] 2) Add the end-capping agent to the above mixture, continue to add epichlorohydrin, dimethylamine and polyethylene polyamine (molecular weight 1400) to the system, and react for 4.5 hours under the conditions of heating and stirring in a 95°C oil bath, and then rotary evaporate at 0.09Mpa and 75°C to obtain a binary block copolymer demulsifier. The amount of the end-capping agent is 5 times the amount of dimethylamine. The end-capping agent is benzyl bromide. The molar ratio of polyether, epichlorohydrin, dimethylamine and polyethylene polyamine is 8:50:200:80.

[0043] 3) Add polysiloxane (polysiloxane manufacturer: Shanghai MacLean Biochemical Technology Co., Ltd.) to the above binary block copolymer demulsifier, and heat to 110°C for reaction for 5 hours under constant temperature stirring to obtain a ternary block copolymer low-temperature demulsifier. The molar ratio of the binary block copolymer demulsifier to the polysiloxane is 10:6.

[0044] The structural characterization of the ternary block copolymer low-temperature demulsifier of Test Example 1 was carried out under the following test conditions: 1) Using a Nicolet infrared spectrometer and a thin film method, directly apply the ternary block copolymer low-temperature demulsifier on a salt sheet and measure using a total reflection system or a reflection system with an alkali halide lens.

[0045] 2) Dissolve the demulsifier in deuterated DMSO and place it in a Bruker 400M 1 H NMR ( 1 H NMR) detection.

[0046] from Figure 1 It can be seen that at 3440cm -1 The obvious NH stretching vibration peak is at 2360 cm -1 and 1640cm -1 Characteristic peaks of Si-H and CN, 1350cm -1 and 1100cm -1 , respectively CH and CO stretching vibration, at 773cm -1 It is an obvious NH out-of-plane vibration peak. It is preliminarily judged that the ternary block copolymer low-temperature demulsifier is successfully synthesized. The ternary block copolymer low-temperature demulsifier is recorded as JST2.

[0047] Table 1 FT-IR identification of JST2

[0048] Figure 2 is the NMR spectrum of DMD4, 1 H NMR (400 MHz, DMSO) δ 6.84, 3.23, 3.48 3.42, 3.41, 3.39, ,2.5, 2.2, 1.88, 1.26, 0.83.

[0049] Table 2 JST2 1HNMR assignment

[0050] from Figure 2 It can be seen that the uncapped intermediate is compared with JST2 capped with bromohexane, and the molecular formulas match, which further determines that the modification is successful.

[0051] Demulsification and dehydration rate effects of test examples 1 to 4: The present invention refers to China's petroleum and natural gas industry standard SY / T 5280-2018 "General Technical Conditions for Crude Oil Demulsifiers". A mud-containing O / W emulsion provided by an oilfield company (an oil production plant in a block in northern Shaanxi) is added with different doses of OP emulsifier in a mixed system with an oil-water volume ratio of 3:7, and stirred at a stirring speed of 5000 rpm for 40 min to obtain an O / W emulsion (E37). The mixture is allowed to stand for one week to observe its stability.

[0052] The present invention conducts a demulsifier performance evaluation experiment based on the petroleum and natural gas industry standard SY / T 5281-2000 "Crude oil demulsifier performance test method (bottle test method)" and SY / T 5280-2018 "Crude oil demulsifier general technical conditions". An appropriate amount of demulsifier is dissolved in distilled water, added to the emulsion, and the stoppered measuring cylinder (scintillation bottle) is manually shaken 200 times to explore the relationship between dosage, time, temperature, pH, salinity and demulsification efficiency using a single factor control variable method. The dehydration rate formula is as follows:

[0053] Where: V is the volume of the separated aqueous phase, V0 is the volume of the original water in the emulsion The present invention selects a commercially available demulsifier (ST600) with better demulsification effect and the crude oil low-temperature demulsifier (JST3) provided in Example 2 to conduct different crude oil dehydration experiments for comparison, and through dosage screening, it can be used for industrial large-scale demulsification.

[0054] The results are as follows: For an oil production plant in a certain area in northern Shaanxi, the demulsification and dehydration rate of JST2 can reach 100% under the conditions of 1h, 40℃ and 50ppm.

[0055] 1. Select agent: Table 3 Demulsification of high-polymer heavy oil emulsion in a block in northern Shaanxi at 50ppm, different types of demulsifiers, 1h, 40℃

[0056] As can be seen from Table 3, JST2 has a higher dehydration rate than the commercially available demulsifier ST600, has a good demulsification effect, and can be used to effectively handle the demulsification of an oil production plant in a certain area in northern Shaanxi.

[0057] from Figure 3 It can be seen that Figure 3 From left to right are the demulsification effects of the blank group, JST2, JST-3, and ST600. Figure 3 It can be seen that JST2 has a higher dehydration rate than the commercially available demulsifier ST600 and has a good demulsification effect. It can effectively handle the demulsification of high-polymer heavy oil emulsion in a block in northern Shaanxi.

[0058] 2. Select quantity (JST2): Table 4 Demulsification of JST2 at different dosages for high-polymer heavy oil emulsion in a block in northern Shaanxi

[0059] It can be seen from Table 4 that JST2 can achieve complete dehydration at 50 ppm.

[0060] For a high-polymer heavy oil emulsion in a certain area in northern Shaanxi, the demulsification and dehydration rate of JST2 can reach 100% under the conditions of 1h, 40℃ and 50ppm.

[0061] from Figure 4 It can be seen that Figure 4 From left to right, the demulsification of JST2 at 10, 20, 30, 50, and 100 ppm is shown. Figure 4 It can be seen that the demulsification and dehydration rate of JST2 can reach 100% under the conditions of 1h, 40℃ and 50ppm, which is suitable for demulsification of high-polymer heavy oil emulsion in a block in northern Shaanxi.

[0062] We et al. (ACS Omega, 2021, 6(39): 25518-25528) synthesized the FB series of fluorinated polyether demulsifiers by block copolymerization for demulsification of heavy oil in Liaohe Oilfield. The dehydration rate of FB4 can reach 90.3% under the conditions of 100 ppm, 120 min, and 60 °C. This synthesis method is simple and can demulsify at low temperatures, but the dehydration rate is somewhat inferior. The dehydration rate of the present invention can reach more than 98.6%.

[0063] Abdullah et al. (Arabian Journal of Chemistry, 2020, 13(1): 3403-3428) synthesized two new amphiphilic ionic liquids CRC-PS and CRC-BA by reacting curcumin with 1,3-propane sultone and bromoacetic acid to generate the corresponding sulfonic acid and carboxylic acid. The dehydration rate of CRC can reach 98.0% under the conditions of 250 min, 60 ℃, and 1000 ppm. The demulsifier synthesized by Abdullah et al. has a long demulsification time, while the demulsifier of the present invention can quickly demulsify in 40 minutes, with a short demulsification time.

[0064] Xu et al. (Physicochemical and Engineering Aspects, 2023, 669: 131498) used isobutyl acrylate (IBA) and N,N-Dimethylacrylamide (DMAA) free radical copolymerization reaction, synthesized a series of amphiphilic copolymers, at 80 ° C, 400 ppm, 210 min, the dehydration rate reached 92.7%. The synthesis method is through free radical polymerization, free radical copolymerization reaction, the reaction is violent, difficult to control. The reaction conditions of the present invention are mild, and it is easy to react and synthesize demulsifiers, and can be industrialized.

[0065] The above description is only for the best embodiment of the present invention, but it should not be understood as limiting the claims. The present invention is not limited to the above embodiments, and its specific structure is allowed to be changed. However, all changes made within the protection scope of the independent claims of the present invention are within the protection scope of the present invention.

[0066] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

Claims

1. A method for preparing a ternary block copolymer low-temperature demulsifier, characterized in that: The following steps are involved: Dissolving polyether and acid anhydride in a solvent to obtain a mixed solution, reacting the mixed solution at 70-90° C. for 1-3 hours to obtain a polyether acid anhydride solution; After adding epichlorohydrin, dimethylamine, polyethyleneimine and a capping agent to the polyether anhydride solution, reacting at 90-100° C. for 4-5 hours, a binary block copolymer demulsifier is obtained; Add polysiloxane to the binary block copolymer demulsifier and react at 110-140° C. for 4-5 hours to obtain a ternary block copolymer low-temperature demulsifier.

2. The method for preparing the ternary block copolymer low-temperature demulsifier according to claim 1, characterized in that: The polyether is PE-6800, PE-10500 or RPE174; the acid anhydride is maleic anhydride; and the solvent is anhydrous ethanol.

3. The method for preparing the ternary block copolymer low-temperature demulsifier according to claim 1, characterized in that: The molar ratio of polyether, acid anhydride and solvent is (62-63): (5000-6000): (2200-3000).

4. The method for preparing the ternary block copolymer low-temperature demulsifier according to claim 1, characterized in that: Polyethyleneimine is a polyethylene polyamine with a molecular weight of 600-1800.

5. The method for preparing the ternary block copolymer low-temperature demulsifier according to claim 1, characterized in that: The amount of the capping agent used is 4-5 times the amount of dimethylamine.

6. The method for preparing the ternary block copolymer low-temperature demulsifier according to claim 1, characterized in that: The end-capping agent is an alkyl bromide or benzyl bromide having 2 to 12 carbon atoms.

7. The method for preparing the ternary block copolymer low-temperature demulsifier according to claim 1, characterized in that: The molar ratio of polyether, epichlorohydrin, dimethylamine and polyethyleneimine is (7-8): (50-60): (100-200): (70-80).

8. The method for preparing the ternary block copolymer low-temperature demulsifier according to claim 1, characterized in that: The molar ratio of the binary block copolymer demulsifier to the polysiloxane is (10-20): (6-7).

9. A ternary block copolymer low-temperature demulsifier prepared according to the method according to any one of claims 1 to 8.

10. Use of a ternary block copolymer low-temperature demulsifier prepared according to the method of any one of claims 1 to 8 in oil-water separation.

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