A modified hyperbranched demulsifier, its preparation process and application

Abstract

The invention provides a modified hyperbranched demulsifier and a preparation process and application thereof, belonging to the technical field of petrochemical industry, wherein the preparation process comprises the following steps: step 1: preparing a hyperbranched polymer; step 2: preparing an amphiphilic surfactant; step 3: preparing a modified hyperbranched demulsifier: (1) preparing a hyperbranched modified carbon nanotube; (2) preparing a surfactant-modified carbon nanotube; (3) mixing a hyperbranched modified carbon nanotube and a surfactant-modified carbon nanotube in a mass ratio of (1.4-1.7):1 to obtain a modified hyperbranched demulsifier. The modified hyperbranched demulsifier of the invention has high salt resistance and a small amount of use, and can achieve high-efficiency demulsification of an oil-in-water type crude oil emulsion at room temperature. It is also suitable for demulsifying an oil-in-water type crude oil emulsification system or purified oil with a high water content, has a wider range of adaptability, and has a high market value.

Description

Technical Field

[0001] The invention belongs to the technical field of petrochemical industry, and specifically relates to a modified hyperbranched demulsifier and a preparation process and application thereof. Background Art

[0002] The crude oil extracted from the oil well has surface activity due to certain chemical substances introduced naturally or by production-increasing measures. These substances are concentrated on the oil-water interface to form an interfacial film with a certain strength, so that the extracted crude oil forms a stable oil-water emulsion or multiple emulsions. The water content in the crude oil will increase the load on the pipeline and equipment, and will also cause corrosion and scaling to the pipeline and equipment, and more seriously, it will cause catalyst poisoning.

[0003] Crude oil demulsifier plays a vital role in the oil industry. It is mainly used to treat the emulsion contained in crude oil to achieve oil-water separation. During the extraction process, a large amount of water will be mixed into the crude oil to form a stable emulsion. Demulsifiers can destroy these emulsified structures and separate water and oil.

[0004] Emulsion is a very complex dispersion system, mainly water-in-oil (W / O) type. With the application of new oil recovery technologies, water-in-oil (O / W) emulsions have gradually appeared in the produced fluid. However, existing demulsifiers have problems such as small application range, large dosage, unsatisfactory demulsification effect at room temperature, poor salt resistance, etc., which leads to increased investment costs and still cannot achieve the ideal demulsification effect. Therefore, it is urgent to develop a new demulsifier with better effect and suitable for water-in-oil crude oil emulsion system or purified oil with high water content. Summary of the invention

[0005] The purpose of the present invention is to provide a preparation process and application of a modified hyperbranched demulsifier.

[0006] In order to achieve the above object, the present invention provides the following technical solution: a preparation process of a modified hyperbranched demulsifier, comprising the following steps:

[0007] Step 1: Prepare a hyperbranched polymer as follows:

[0008] (1) 1 mol of N,N'-di(3-aminopropyl)-1,3-propylenediamine, 3-5 mol of isobutyl methacrylate and methanol were mixed, and the mixture was stirred at 25-30°C for 23-27 hours to obtain mixture 1; 10-15 mol of N,N'-di(3-aminopropyl)-1,3-propylenediamine and 13-17 mol of isobutyl methacrylate were added to mixture 1 in sequence, and the mixture was stirred and reacted at 25-30°C for 28-32 hours to obtain mixture 2; 17-20 mol of N,N'-di(3-aminopropyl)-1,3-propylenediamine and 22-25 mol of isobutyl methacrylate were added to mixture 2 in sequence, and the mixture was stirred and reacted at 25-30°C for 35-40 hours to obtain mixture 3;

[0009] (2) After removing methanol from the mixture 3 under reduced pressure, the mixture was heated to 64-68°C for reaction for 60-80 min, then heated to 90-96°C for reaction for 100-120 min, then heated to 110-115°C for reaction for 130-150 min, then heated to 125-130°C for reaction for 140-160 min, and finally heated to 150-155°C for reaction for 180-200 min, cooled naturally to room temperature, precipitated with ether, and dried in vacuo to obtain a hyperbranched polymer;

[0010] Step 2: Prepare an amphiphilic surfactant as follows:

[0011] (1) Mix 1 mol 3,5-difluorobenzyl alcohol, 1.3-1.7 mol bromoform, 0.6-0.9 mol NaOH and 0.6-0.8 L dimethyl sulfoxide, stir evenly, heat to 125-130°C, react for 22-27 hours, cool to room temperature, add water to precipitate solid, and purify to obtain 3,5-difluorobenzyloxydibromomethane;

[0012] (2) Mix 1 mol 3,5-difluorobenzyloxydibromomethane, 2-2.3 mol sodium cyanide and 4-6 L ethanol, reflux at 74-77°C for 15-18 hours, then add NaOH aqueous solution, stir and react at 83-88°C for 4-6 hours, extract the organic phase, and then recrystallize to obtain an amphiphilic surfactant;

[0013] Step 3: Preparation of modified hyperbranched demulsifier:

[0014] (1) Add 1 g of mixed carbon nanotube A and 0.02-0.03 g of γ-aminopropyltriethoxysilane to 10-15 mL of acetone, react at 40-45° C. for 3-5 h, filter, wash, and dry to obtain silane-modified carbon nanotubes; mix 1 g of hyperbranched polymer, 0.1-0.3 g of silane-modified carbon nanotubes and 16-19 mL of methanol, disperse uniformly by ultrasonication, stir and react at 35-40° C. for 30-35 h, centrifuge, wash, and dry in sequence to obtain hyperbranched modified carbon nanotubes;

[0015] (2) Mix 1 g of mixed carbon nanotubes B, 0.04-0.06 g of amphiphilic surfactant and 5-8 g of water, stir evenly, react at 45-50° C. for 10-15 h, centrifuge, wash and dry in sequence to obtain surfactant-modified carbon nanotubes;

[0016] (3) The hyperbranched modified carbon nanotubes and the surfactant modified carbon nanotubes are mixed in a mass ratio of (1.4-1.7):1 to obtain a modified hyperbranched demulsifier.

[0017] The invention prepares a hyperbranched polymer through a multi-step synthesis process. Through nucleophilic substitution, the amine group acts as a nucleophilic reagent, and the carbonyl carbon in the ester group is an electrophilic center. Since N, N'-di(3-aminopropyl)-1, 3-propylenediamine has two amine groups and an excess of isobutyl methacrylate exists, the reaction can be further carried out to form a branch structure with multiple amide bonds; the amount of N, N'-di(3-aminopropyl)-1, 3-propylenediamine and isobutyl methacrylate is gradually increased to the mixture formed in the first stage to further deepen the polymerization reaction. As the concentration of the reactants increases, the extension of the reaction time helps to increase the depth of the reaction and the molecular weight of the product, thereby forming a more dense branch structure. Then, by combining the advantages of multiple components such as hyperbranched polymers, amphiphilic surfactants and modified carbon nanotubes, a multifunctional demulsifier system is formed to obtain a composite demulsifier, which can be effectively applied to the demulsification process of oil-in-water (O / W) and water-in-oil (W / O) emulsions at room temperature. The present invention is through the mode of step-by-step growth polymerization, first the formation of initial compound, then adding reactants to amplify the reaction in batches, and then heat treatment by heating, which helps to further promote the reaction, ensure that all reactive functional groups are utilized, make the hyperbranched polymer have a highly branched structure, can provide a large number of active sites, these sites can be adsorbed on the oil-water interface, destroy the stability of the emulsion layer. The amphiphilic surfactant has hydrophilic and hydrophobic ends, can be oriented on the oil-water interface, reduce interfacial tension, promote oil-water separation, and this property enables it to adapt to different types of emulsions. By mixing hyperbranched polymers, amphiphilic surfactants and modified carbon nanotubes in a specific ratio, the composite demulsifier formed can combine the advantages of each component, produce a synergistic effect, and improve demulsification efficiency. The interaction and complementarity between different components enable the composite demulsifier to adapt to complex and changeable emulsion conditions, whether it is oil-in-water or water-in-oil type emulsion, can show good demulsification performance.

[0018] Furthermore, the volume of the methanol is 7-10 times the total volume of the N,N'-di(3-aminopropyl)-1,3-propylenediamine and isobutyl methacrylate used in step (1).

[0019] Furthermore, the purification method is: filtering the solid, washing the filter cake with water for 2-3 times, drying at 104-107° C. for 3-5 hours, and then recrystallizing with ethanol.

[0020] Furthermore, ethyl acetate is used for recrystallization.

[0021] Furthermore, the mass percentage of the NaOH aqueous solution is 35-40%.

[0022] Furthermore, the amount of NaOH aqueous solution added is 0.3-0.5L.

[0023] Furthermore, the mixed carbon nanotubes A are double-walled carbon nanotubes, single-walled carbon nanotubes and multi-walled carbon nanotubes in a mass ratio of 1: (1.4-1.7): (0.2-0.6); the single-walled carbon nanotubes have a diameter of 10-30 nm and a length of 10-30 μm; the double-walled carbon nanotubes have a diameter of 5-15 nm and a length of 10-30 μm; the multi-walled carbon nanotubes have a diameter of 20-30 nm and a length of 10-30 μm.

[0024] Furthermore, the mixed carbon nanotubes B are double-walled carbon nanotubes, single-walled carbon nanotubes and multi-walled carbon nanotubes in a mass ratio of (0.5-0.8):1:(1.3-1.6); the single-walled carbon nanotubes have a diameter of 10-30 nm and a length of 10-30 μm; the double-walled carbon nanotubes have a diameter of 5-15 nm and a length of 10-30 μm; the multi-walled carbon nanotubes have a diameter of 20-30 nm and a length of 10-30 μm.

[0025] The present invention can improve the salt tolerance of demulsifier by using carbon nanotubes of different lengths and diameters. Analysis is that in the system of the present invention, when carbon nanotubes are used together with hyperbranched polymers and amphiphilic surfactants, carbon nanotubes of different sizes can serve as bridges to promote the synergy between hyperbranched polymers and amphiphilic surfactants, and enhance the salt tolerance of demulsifiers. Carbon nanotubes of different lengths and diameters provide different surface properties, which can provide more active sites, which help to adsorb and shield salt ions, reduce the negative impact of salt on demulsifier performance, and can form a more stable composite network with the interaction between hyperbranched polymers and surfactants to resist the interference of salt ions. By adjusting the size of carbon nanotubes, the synergy between them and hyperbranched polymers and amphiphilic surfactants can be optimized to form a more stable and effective composite system, thereby affecting the salt tolerance of demulsifiers.

[0026] Furthermore, the step of extracting the organic phase is: adding the obtained reaction solution into 2-3L of water, extracting with ethyl acetate, and drying the extracted organic phase.

[0027] The invention provides a modified hyperbranched demulsifier prepared by the preparation process.

[0028] The invention also provides application of the modified hyperbranched demulsifier.

[0029] Furthermore, the modified hyperbranched demulsifier is used in the preparation of an oil-in-water emulsion, wherein the concentration of the demulsifier in the oil-in-water emulsion is 50-100 ppm, the demulsification temperature is 20-40° C., and the demulsification time is 30-60 min.

[0030] Furthermore, the salinity of the oil-in-water emulsion is 0.1-10000 ppm.

[0031] Furthermore, the modified hyperbranched demulsifier is used in the preparation of a water-in-oil emulsion, wherein the concentration of the demulsifier in the water-in-oil emulsion is 50-100 ppm, the demulsification temperature is 20-40° C., and the demulsification time is 30-60 min.

[0032] Compared with the prior art, the advantages and beneficial effects of the present invention are:

[0033] 1. The present invention provides a preparation process and application of a modified hyperbranched demulsifier. The present invention combines the advantages of multiple components such as hyperbranched polymers, amphiphilic surfactants and modified carbon nanotubes to form a multifunctional demulsification system, thereby obtaining a composite demulsifier that can be effectively applied to the demulsification process of oil-in-water (O / W) and water-in-oil (W / O) emulsions at room temperature. The demulsifier has high salt resistance and a small amount of use, and can achieve high-efficiency demulsification of oil-in-water crude oil emulsions at room temperature. The present invention has a wider range of application and a higher market value.

[0034] 2. The present invention can improve the salt tolerance of demulsifiers by using carbon nanotubes of different lengths and diameters. By adjusting the size of carbon nanotubes, the synergistic effect between carbon nanotubes, hyperbranched polymers and amphiphilic surfactants can be optimized to form a more stable and effective composite system, thereby affecting the salt tolerance of demulsifiers. DETAILED DESCRIPTION

[0035] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] The raw materials in the embodiment are:

[0037] N,N'-Bis(3-aminopropyl)-1,3-propanediamine, CAS: 4605-14-5.

[0038] Isobutyl methacrylate, CAS: 106-27-6.

[0039] 3,5-Difluorobenzyl alcohol, CAS: 423-80-4.

[0040] γ-Aminopropyltriethoxysilane, CAS: 3068-65-4.

[0041] The diameter of single-walled carbon nanotubes is 10-30nm and the length is 10-30μm; the diameter of double-walled carbon nanotubes is 5-15nm and the length is 10-30μm; the diameter of multi-walled carbon nanotubes is 20-30 nm and the length is 10-30μm. The diameter of single-walled carbon nanotubes is 1-2nm and the length is 1-3μm; the diameter of double-walled carbon nanotubes is 2-4nm and the length is 0.5-4μm; the diameter of multi-walled carbon nanotubes is 8-15nm and the length is 0.5-2μm. All of the above were purchased from Jiangsu Xianfeng Nanomaterial Technology Co., Ltd.

[0042] Example 1

[0043] This embodiment provides a preparation process of a modified hyperbranched demulsifier, comprising the following steps:

[0044] Step 1: Prepare a hyperbranched polymer as follows:

[0045] (1) 1 mol of N,N'-di(3-aminopropyl)-1,3-propylenediamine, 4 mol of isobutyl methacrylate and methanol were mixed, and the mixture was stirred at 27°C for 25 hours to obtain mixture 1; 13 mol of N,N'-di(3-aminopropyl)-1,3-propylenediamine and 15 mol of isobutyl methacrylate were added to mixture 1 in sequence, and the mixture was stirred and reacted at 27°C for 30 hours to obtain mixture 2; 18 mol of N,N'-di(3-aminopropyl)-1,3-propylenediamine and 24 mol of isobutyl methacrylate were added to mixture 2 in sequence, and the mixture was stirred and reacted at 27°C for 38 hours to obtain mixture 3; the volume of the methanol was 9 times the total volume of N,N'-di(3-aminopropyl)-1,3-propylenediamine and isobutyl methacrylate used in step (1).

[0046] (2) After removing methanol from the mixture 3 under reduced pressure, the mixture was heated to 66°C for 70 min, then heated to 93°C for 110 min, then heated to 112°C for 140 min, then heated to 127°C for 150 min, and finally heated to 152°C for 190 min, cooled naturally to room temperature, precipitated with ether, and dried in vacuo to obtain a hyperbranched polymer;

[0047] Step 2: Prepare an amphiphilic surfactant as follows:

[0048] (1) 1 mol 3,5-difluorobenzyl alcohol, 1.5 mol bromoform, 0.7 mol NaOH and 0.7 L dimethyl sulfoxide were mixed and stirred evenly, heated to 128°C, reacted for 25 h, cooled to room temperature, and solids were precipitated after adding water. After purification, 3,5-difluorobenzyloxydibromomethane was obtained. The purification method was as follows: the solids were filtered, the filter cake was washed with water 3 times, dried at 105°C for 4 h, and then recrystallized from ethanol;

[0049] (2) 1 mol of 3,5-difluorobenzyloxydibromomethane, 2.2 mol of sodium cyanide and 5 L of ethanol were mixed, and the mixture was refluxed at 76° C. for 17 h. Then, an aqueous NaOH solution was added, and the mixture was stirred at 85° C. for 5 h, and an organic phase was extracted. The steps of extracting the organic phase were as follows: adding the obtained reaction solution to 2.6 L of water, extracting with ethyl acetate, and drying the extracted organic phase; then, recrystallizing with ethyl acetate to obtain an amphiphilic surfactant; the mass percentage of the aqueous NaOH solution was 37%; and the amount of the aqueous NaOH solution added was 0.4 L.

[0050] Step 3: Preparation of modified hyperbranched demulsifier:

[0051] (1) 1 g of mixed carbon nanotubes A and 0.03 g of γ-aminopropyltriethoxysilane were added to 13 mL of acetone, reacted at 42° C. for 4 h, filtered, washed, and dried to obtain silane-modified carbon nanotubes; 1 g of hyperbranched polymer, 0.2 g of silane-modified carbon nanotubes and 17 mL of methanol were mixed, ultrasonically dispersed uniformly, stirred and reacted at 38° C. for 32 h, centrifuged, washed, and dried in sequence to obtain hyperbranched modified carbon nanotubes; the mixed carbon nanotubes A were double-walled carbon nanotubes, single-walled carbon nanotubes, and multi-walled carbon nanotubes in a mass ratio of 1:1.5:0.4; the single-walled carbon nanotubes had a diameter of 10-30 nm and a length of 10-30 μm; the double-walled carbon nanotubes had a diameter of 5-15 nm and a length of 10-30 μm; the multi-walled carbon nanotubes had a diameter of 20-30 nm and a length of 10-30 μm.

[0052] (2) 1 g of mixed carbon nanotubes B, 0.05 g of an amphiphilic surfactant and 7 g of water were mixed, stirred evenly, reacted at 47° C. for 12 h, and centrifuged, washed and dried in sequence to obtain surfactant-modified carbon nanotubes; the mixed carbon nanotubes B were double-walled carbon nanotubes, single-walled carbon nanotubes and multi-walled carbon nanotubes in a mass ratio of 0.6:1:1.5; the single-walled carbon nanotubes had a diameter of 10-30 nm and a length of 10-30 μm; the double-walled carbon nanotubes had a diameter of 5-15 nm and a length of 10-30 μm; and the multi-walled carbon nanotubes had a diameter of 20-30 nm and a length of 10-30 μm.

[0053] (3) The hyperbranched modified carbon nanotubes and the surfactant modified carbon nanotubes were mixed in a mass ratio of 1.6:1 to obtain a modified hyperbranched demulsifier.

[0054] Example 2

[0055] This embodiment provides a preparation process of a modified hyperbranched demulsifier, comprising the following steps:

[0056] Step 1: Prepare a hyperbranched polymer as follows:

[0057] (1) 1 mol of N,N'-di(3-aminopropyl)-1,3-propylenediamine, 3 mol of isobutyl methacrylate and methanol were mixed, and the mixture was stirred at 25°C for 23 hours to obtain mixture 1; 10 mol of N,N'-di(3-aminopropyl)-1,3-propylenediamine and 13 mol of isobutyl methacrylate were added to mixture 1 in sequence, and the mixture was stirred and reacted at 25°C for 28 hours to obtain mixture 2; 17 mol of N,N'-di(3-aminopropyl)-1,3-propylenediamine and 22 mol of isobutyl methacrylate were added to mixture 2 in sequence, and the mixture was stirred and reacted at 25°C for 35 hours to obtain mixture 3; the volume of the methanol was 7 times the total volume of N,N'-di(3-aminopropyl)-1,3-propylenediamine and isobutyl methacrylate used in step (1).

[0058] (2) After removing methanol from the mixture 3 under reduced pressure, the mixture was heated to 64°C for reaction for 60 min, then heated to 90°C for reaction for 100 min, then heated to 110°C for reaction for 130 min, then heated to 125°C for reaction for 140 min, and finally heated to 150°C for reaction for 180 min, cooled naturally to room temperature, precipitated with ether, and dried in vacuo to obtain a hyperbranched polymer;

[0059] Step 2: Prepare an amphiphilic surfactant as follows:

[0060] (1) 1 mol 3,5-difluorobenzyl alcohol, 1.3 mol bromoform, 0.6 mol NaOH and 0.6 L dimethyl sulfoxide were mixed and stirred evenly, heated to 125°C, reacted for 22 h, cooled to room temperature, and solids were precipitated after adding water. After purification, 3,5-difluorobenzyloxydibromomethane was obtained. The purification method was as follows: the solids were filtered, the filter cake was washed with water twice, dried at 104°C for 3 h, and then recrystallized from ethanol;

[0061] (2) 1 mol of 3,5-difluorobenzyloxydibromomethane, 2 mol of sodium cyanide and 4 L of ethanol were mixed, and the mixture was refluxed at 74° C. for 15 h. Then, an aqueous NaOH solution was added, and the mixture was stirred at 83° C. for 4 h, and an organic phase was extracted. The steps of extracting the organic phase were as follows: adding the obtained reaction solution to 2 L of water, extracting with ethyl acetate, and drying the extracted organic phase; then, recrystallizing with ethyl acetate to obtain an amphiphilic surfactant; the mass percentage of the aqueous NaOH solution was 35%; and the amount of the aqueous NaOH solution added was 0.3 L.

[0062] Step 3: Preparation of modified hyperbranched demulsifier:

[0063] (1) Add 1 g of mixed carbon nanotubes A and 0.03 g of γ-aminopropyltriethoxysilane to 15 mL of acetone, react at 45° C. for 5 h, filter, wash, and dry to obtain silane-modified carbon nanotubes; mix 1 g of hyperbranched polymer, 0.3 g of silane-modified carbon nanotubes and 19 mL of methanol, disperse them uniformly by ultrasonication, stir and react at 40° C. for 35 h, centrifuge, wash, and dry in sequence to obtain hyperbranched modified carbon nanotubes; the mixed carbon nanotubes A are double-walled carbon nanotubes, single-walled carbon nanotubes, and multi-walled carbon nanotubes in a mass ratio of 1:1.4:0.2; the single-walled carbon nanotubes have a diameter of 10-30 nm and a length of 10-30 μm; the double-walled carbon nanotubes have a diameter of 5-15 nm and a length of 10-30 μm; the multi-walled carbon nanotubes have a diameter of 20-30 nm and a length of 10-30 μm.

[0064] (2) 1 g of mixed carbon nanotubes B, 0.06 g of an amphiphilic surfactant and 8 g of water were mixed, stirred evenly, reacted at 50° C. for 15 h, and centrifuged, washed and dried in sequence to obtain surfactant-modified carbon nanotubes; the mixed carbon nanotubes B were double-walled carbon nanotubes, single-walled carbon nanotubes and multi-walled carbon nanotubes in a mass ratio of 0.5:1:1.3; the single-walled carbon nanotubes had a diameter of 10-30 nm and a length of 10-30 μm; the double-walled carbon nanotubes had a diameter of 5-15 nm and a length of 10-30 μm; and the multi-walled carbon nanotubes had a diameter of 20-30 nm and a length of 10-30 μm.

[0065] (3) The hyperbranched modified carbon nanotubes and the surfactant modified carbon nanotubes were mixed in a mass ratio of 1.4:1 to obtain a modified hyperbranched demulsifier.

[0066] Example 3

[0067] This embodiment provides a preparation process of a modified hyperbranched demulsifier, comprising the following steps:

[0068] Step 1: Prepare a hyperbranched polymer as follows:

[0069] (1) 1 mol of N,N'-di(3-aminopropyl)-1,3-propylenediamine, 5 mol of isobutyl methacrylate and methanol were mixed, and the mixture was stirred at 30°C for 27 hours to obtain mixture 1; 15 mol of N,N'-di(3-aminopropyl)-1,3-propylenediamine and 17 mol of isobutyl methacrylate were added to mixture 1 in sequence, and the mixture was stirred and reacted at 30°C for 32 hours to obtain mixture 2; 20 mol of N,N'-di(3-aminopropyl)-1,3-propylenediamine and 25 mol of isobutyl methacrylate were added to mixture 2 in sequence, and the mixture was stirred and reacted at 30°C for 40 hours to obtain mixture 3; the volume of the methanol was 10 times the total volume of the N,N'-di(3-aminopropyl)-1,3-propylenediamine and isobutyl methacrylate used in step (1).

[0070] (2) After removing methanol from the mixture 3 under reduced pressure, the mixture was heated to 68°C for reaction for 80 min, then heated to 96°C for reaction for 120 min, then heated to 115°C for reaction for 150 min, then heated to 130°C for reaction for 160 min, and finally heated to 155°C for reaction for 200 min, cooled naturally to room temperature, precipitated with ether, and dried in vacuo to obtain a hyperbranched polymer;

[0071] Step 2: Prepare an amphiphilic surfactant as follows:

[0072] (1) 1 mol 3,5-difluorobenzyl alcohol, 1.7 mol bromoform, 0.9 mol NaOH and 0.8 L dimethyl sulfoxide were mixed and stirred evenly, heated to 130°C, reacted for 27 hours, cooled to room temperature, and solids were precipitated after adding water. After purification, 3,5-difluorobenzyloxydibromomethane was obtained. The purification method was as follows: the solids were filtered, the filter cake was washed with water three times, dried at 107°C for 5 hours, and then recrystallized from ethanol;

[0073] (2) 1 mol of 3,5-difluorobenzyloxydibromomethane, 2.3 mol of sodium cyanide and 6 L of ethanol were mixed, and the mixture was refluxed at 77° C. for 18 h. Then, an aqueous NaOH solution was added, and the mixture was stirred at 88° C. for 6 h, and an organic phase was extracted. The steps of extracting the organic phase were as follows: adding the obtained reaction solution to 3 L of water, extracting with ethyl acetate, and drying the extracted organic phase; then, recrystallizing with ethyl acetate to obtain an amphiphilic surfactant; the mass percentage of the aqueous NaOH solution was 40%; and the amount of the aqueous NaOH solution added was 0.5 L.

[0074] Step 3: Preparation of modified hyperbranched demulsifier:

[0075] (1) Add 1 g of mixed carbon nanotubes A and 0.03 g of γ-aminopropyltriethoxysilane to 15 mL of acetone, react at 45° C. for 5 h, filter, wash, and dry to obtain silane-modified carbon nanotubes; mix 1 g of hyperbranched polymer, 0.3 g of silane-modified carbon nanotubes and 19 mL of methanol, disperse them uniformly by ultrasonication, stir and react at 40° C. for 35 h, centrifuge, wash, and dry in sequence to obtain hyperbranched modified carbon nanotubes; the mixed carbon nanotubes A are double-walled carbon nanotubes, single-walled carbon nanotubes, and multi-walled carbon nanotubes in a mass ratio of 1:1.7:0.6; the single-walled carbon nanotubes have a diameter of 10-30 nm and a length of 10-30 μm; the double-walled carbon nanotubes have a diameter of 5-15 nm and a length of 10-30 μm; the multi-walled carbon nanotubes have a diameter of 20-30 nm and a length of 10-30 μm.

[0076] (2) 1 g of mixed carbon nanotubes B, 0.06 g of an amphiphilic surfactant and 8 g of water were mixed, stirred evenly, reacted at 50° C. for 15 h, and centrifuged, washed and dried in sequence to obtain surfactant-modified carbon nanotubes; the mixed carbon nanotubes B were double-walled carbon nanotubes, single-walled carbon nanotubes and multi-walled carbon nanotubes in a mass ratio of 0.8:1:1.6; the single-walled carbon nanotubes had a diameter of 10-30 nm and a length of 10-30 μm; the double-walled carbon nanotubes had a diameter of 5-15 nm and a length of 10-30 μm; and the multi-walled carbon nanotubes had a diameter of 20-30 nm and a length of 10-30 μm.

[0077] (3) The hyperbranched modified carbon nanotubes and the surfactant modified carbon nanotubes were mixed in a mass ratio of 1.7:1 to obtain a modified hyperbranched demulsifier.

[0078] Comparative Example 1

[0079] The difference between this comparative example and Example 1 is that the mixed carbon nanotubes A are double-walled carbon nanotubes, single-walled carbon nanotubes and multi-walled carbon nanotubes in a mass ratio of 1:1:1; the diameter of the single-walled carbon nanotubes is 10-30nm and the length is 10-30μm; the diameter of the double-walled carbon nanotubes is 5-15nm and the length is 10-30μm; the diameter of the multi-walled carbon nanotubes is 20-30 nm and the length is 10-30μm.

[0080] Comparative Example 2

[0081] The difference between this comparative example and Example 1 is that the mixed carbon nanotubes A are double-walled carbon nanotubes, single-walled carbon nanotubes and multi-walled carbon nanotubes in a mass ratio of 1:1.5:0.4; the diameter of the single-walled carbon nanotubes is 1-2nm and the length is 1-3μm; the diameter of the double-walled carbon nanotubes is 2-4nm and the length is 0.5-4μm; the diameter of the multi-walled carbon nanotubes is 8-15nm and the length is 0.5-2μm.

[0082] Comparative Example 3

[0083] The difference between this comparative example and Example 1 is that the mixed carbon nanotubes B are double-walled carbon nanotubes, single-walled carbon nanotubes and multi-walled carbon nanotubes in a mass ratio of 1:1:1; the diameter of the single-walled carbon nanotubes is 10-30nm and the length is 10-30μm; the diameter of the double-walled carbon nanotubes is 5-15nm and the length is 10-30μm; the diameter of the multi-walled carbon nanotubes is 20-30 nm and the length is 10-30μm.

[0084] Comparative Example 4

[0085] The difference between this comparative example and Example 1 is that the mixed carbon nanotubes B are double-walled carbon nanotubes, single-walled carbon nanotubes and multi-walled carbon nanotubes in a mass ratio of 0.6:1:1.5; the diameter of the single-walled carbon nanotubes is 1-2nm and the length is 1-3μm; the diameter of the double-walled carbon nanotubes is 2-4nm and the length is 0.5-4μm; the diameter of the multi-walled carbon nanotubes is 8-15nm and the length is 0.5-2μm.

[0086] Comparative Example 5

[0087] The difference between this comparative example and Example 1 is that the preparation method of the hyperbranched polymer is different.

[0088] The hyperbranched polymer was prepared as follows:

[0089] (1) 1 mol of N,N'-di(3-aminopropyl)-1,3-propylenediamine, 4 mol of isobutyl methacrylate and methanol were mixed, and the mixture was stirred and reacted at 27°C for 25 hours to obtain a mixture 1; 31 mol of N,N'-di(3-aminopropyl)-1,3-propylenediamine and 39 mol of isobutyl methacrylate were added to the mixture 1 in sequence, and the mixture was stirred and reacted at 27°C for 60 hours to obtain a mixture 2; the volume of the methanol was 9 times the total volume of the N,N'-di(3-aminopropyl)-1,3-propylenediamine and isobutyl methacrylate used in step (1).

[0090] (2) After removing methanol from the mixture 2 under reduced pressure, the mixture was heated to 66°C for reaction for 180 min, then heated to 120°C for reaction for 290 min, and finally heated to 152°C for reaction for 190 min. The mixture was naturally cooled to room temperature, precipitated with ether, and vacuum dried to obtain a hyperbranched polymer.

[0091] Comparative Example 6

[0092] The difference between this comparative example and Example 1 is that the amphiphilic surfactant is Span 20, which was purchased from Haian Petrochemical Plant in Jiangsu Province.

[0093] Performance Testing

[0094] (1) Water-in-oil crude oil emulsion

[0095] Take crude oil and heat it until it can flow, heat an equal volume of deionized water, keep warm and stir until it is uniform, then stir at high speed until the two phases are stable, and let it stand overnight to prepare an oil-in-water crude oil emulsion;

[0096] The crude oil has a viscosity of 200 mPa·s and contains, by mass fraction, 16.2% asphalt, 9.8% resin, 16.2% paraffin and 1.8% water.

[0097] (2) Oil-in-water crude oil emulsion

[0098] Crude oil (10 mL) and sodium chloride solution (490 mL) were mixed and heated to 60°C, stirred until uniform, and then stirred at high speed until the two phases were stable, and allowed to stand overnight to prepare an oil-in-water crude oil emulsion;

[0099] The crude oil has a viscosity of 200 mPa·s, contains 16.6% asphalt, 9.2% resin, 16.8% paraffin, 1.6% water, and 10,000 ppm sodium chloride.

[0100] (3) Evaluation method

[0101] The demulsification performance of the water-in-oil crude oil emulsion was evaluated with reference to SY / T5281-2000 "Test Method for Performance of Crude Oil Demulsifiers", specifically: the demulsifiers of Examples 1-3 and Comparative Examples 1-6 were respectively dispersed in deionized water to obtain dispersions, which were added to the water-in-oil crude oil emulsion, with the mass volume ratio of the demulsifier to the emulsification system being 80 mg / L, shaken 200 times, and allowed to stand at room temperature (25°C) for 60 minutes, and the demulsification efficiency was calculated based on the dehydration amount;

[0102] The demulsification performance of the water-in-oil crude oil emulsion was evaluated by the bottle method. The demulsifiers of Examples 1-3 and Comparative Examples 1-4 were dispersed in deionized water to obtain a dispersion, which was added to the water-in-oil crude oil emulsion. The mass volume ratio of the demulsifier to the emulsification system was 80 mg / L. The mixture was shaken 200 times and allowed to stand at room temperature (25°C) for 60 minutes. The oil yield was calculated according to SY / T0503-2011. The performance test results are shown in Table 1.

[0103] Table 1 Performance test results

[0104] Demulsification efficiency of water-in-oil crude oil emulsion % Oil yield of water-in-oil crude oil emulsion % Example 1 99.34 94.23 Example 2 97.29 93.12 Example 3 98.21 92.37 Comparative Example 1 95.32 88.43 Comparative Example 2 94.34 86.16 Comparative Example 3 92.01 87.54 Comparative Example 4 93.13 84.42 Comparative Example 5 94.78 87.12 Comparative Example 6 85.13 74.87

[0105] It can be seen from the above performance test results that Examples 1-3 can be effectively applied to the demulsification process of oil-in-water (O / W) and water-in-oil (W / O) emulsions at room temperature, have good demulsification effect, and have high salt resistance. In particular, the comprehensive performance of Example 1 is the most outstanding. This is mainly because the hyperbranched polymer, amphiphilic surfactant and modified carbon nanotubes are mixed in a specific proportion to form a composite demulsifier that can combine the advantages of each component to produce a synergistic effect and improve the demulsification efficiency.

[0106] The comparative examples are obviously inferior to the embodiments in the corresponding performance tests because they do not adopt the necessary technical solutions. In comparative examples 1-4, the types or proportions of carbon nanotubes are changed, and it can be seen that the demulsification effect on the oil-in-water crude oil emulsion is significantly reduced, proving that the types and proportions of carbon nanotubes have an important influence on the salt resistance effect of the demulsifier. The above experimental results further prove the importance of the technical solution defined in the present invention for its technical effect. It can be seen from comparative example 5 that changing the hyperbranched polymer preparation method leads to a change in the structure of the hyperbranched polymer and a decrease in demulsification performance. It can be seen from comparative example 6 that when the amphiphilic surfactant uses a commercial product, the demulsifier is significantly reduced in two types of crude oil emulsions, indicating that the amphiphilic surfactant prepared by the present invention can work synergistically with the other components to effectively reduce the surface tension of the crude oil emulsion.

[0107] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A process for preparing a modified hyperbranched demulsifier, characterized in that: The following steps are involved: Step 1: Prepare a hyperbranched polymer as follows: (1) 1 mol of N,N'-di(3-aminopropyl)-1,3-propylenediamine, 3-5 mol of isobutyl methacrylate and methanol were mixed, and the mixture was stirred at 25-30°C for 23-27 hours to obtain mixture 1; 10-15 mol of N,N'-di(3-aminopropyl)-1,3-propylenediamine and 13-17 mol of isobutyl methacrylate were added to mixture 1 in sequence, and the mixture was stirred and reacted at 25-30°C for 28-32 hours to obtain mixture 2; 17-20 mol of N,N'-di(3-aminopropyl)-1,3-propylenediamine and 22-25 mol of isobutyl methacrylate were added to mixture 2 in sequence, and the mixture was stirred and reacted at 25-30°C for 35-40 hours to obtain mixture 3; (2) After removing methanol from the mixture 3 under reduced pressure, the mixture was heated to 64-68°C for reaction for 60-80 min, then heated to 90-96°C for reaction for 100-120 min, then heated to 110-115°C for reaction for 130-150 min, then heated to 125-130°C for reaction for 140-160 min, and finally heated to 150-155°C for reaction for 180-200 min, cooled naturally to room temperature, precipitated with ether, and dried in vacuo to obtain a hyperbranched polymer; Step 2: preparing an amphiphilic surfactant; Step 3: Preparation of modified hyperbranched demulsifier: (1) Add 1 g of mixed carbon nanotube A and 0.02-0.03 g of γ-aminopropyltriethoxysilane to 10-15 mL of acetone, react at 40-45° C. for 3-5 h, filter, wash, and dry to obtain silane-modified carbon nanotubes; mix 1 g of hyperbranched polymer, 0.1-0.3 g of silane-modified carbon nanotubes and 16-19 mL of methanol, disperse uniformly by ultrasonication, stir and react at 35-40° C. for 30-35 h, centrifuge, wash, and dry in sequence to obtain hyperbranched modified carbon nanotubes; (2) Mix 1 g of mixed carbon nanotubes B, 0.04-0.06 g of amphiphilic surfactant and 5-8 g of water, stir evenly, react at 45-50° C. for 10-15 h, centrifuge, wash and dry in sequence to obtain surfactant-modified carbon nanotubes; (3) mixing the hyperbranched modified carbon nanotubes and the surfactant modified carbon nanotubes in a mass ratio of (1.4-1.7):1 to obtain a modified hyperbranched demulsifier; The preparation method of the amphiphilic surfactant is as follows: (1) Mix 1 mol 3,5-difluorobenzyl alcohol, 1.3-1.7 mol bromoform, 0.6-0.9 mol NaOH and 0.6-0.8 L dimethyl sulfoxide, stir evenly, heat to 125-130°C, react for 22-27 hours, cool to room temperature, add water to precipitate solid, and purify to obtain 3,5-difluorobenzyloxydibromomethane; (2) Mix 1 mol 3,5-difluorobenzyloxydibromomethane, 2-2.3 mol sodium cyanide and 4-6 L ethanol, reflux at 74-77°C for 15-18 hours, then add NaOH aqueous solution, stir and react at 83-88°C for 4-6 hours, extract the organic phase, and then recrystallize to obtain an amphiphilic surfactant; The mixed carbon nanotubes A are double-walled carbon nanotubes, single-walled carbon nanotubes and multi-walled carbon nanotubes in a mass ratio of 1: (1.4-1.7): (0.2-0.6); the single-walled carbon nanotubes have a diameter of 10-30 nm and a length of 10-30 μm; the double-walled carbon nanotubes have a diameter of 5-15 nm and a length of 10-30 μm; the multi-walled carbon nanotubes have a diameter of 20-30 nm and a length of 10-30 μm; The mixed carbon nanotubes B are double-walled carbon nanotubes, single-walled carbon nanotubes and multi-walled carbon nanotubes in a mass ratio of (0.5-0.8):1:(1.3-1.6); the diameter of the single-walled carbon nanotubes is 10-30nm and the length is 10-30μm; the diameter of the double-walled carbon nanotubes is 5-15nm and the length is 10-30μm; the diameter of the multi-walled carbon nanotubes is 20-30 nm and the length is 10-30μm.

2. The preparation process of the modified hyperbranched demulsifier according to claim 1, characterized in that: The volume of the methanol is 7-10 times the total volume of the N,N'-di(3-aminopropyl)-1,3-propylenediamine and isobutyl methacrylate used in step (1).

3. The preparation process of the modified hyperbranched demulsifier according to claim 2, characterized in that: The mass percentage of the NaOH aqueous solution is 35-40%; the amount of the NaOH aqueous solution added is 0.3-0.5L.

4. A modified hyperbranched demulsifier obtained by the preparation process according to any one of claims 1 to 3.

5. Use of the modified hyperbranched demulsifier according to claim 4 in the preparation of an oil-in-water emulsion, characterized in that: The concentration of the modified hyperbranched demulsifier in the oil-in-water emulsion is 50-100 ppm, the demulsification temperature is 20-40° C., and the demulsification time is 30-60 min.

6. Use of the modified hyperbranched demulsifier according to claim 5 in the preparation of an oil-in-water emulsion, characterized in that: The salinity of the oil-in-water emulsion is 0.1-10000 ppm.

7. Use of the modified hyperbranched demulsifier according to claim 4 in preparing a water-in-oil emulsion, characterized in that: The concentration of the modified hyperbranched demulsifier in the water-in-oil emulsion is 50-100 ppm, the demulsification temperature is 20-40° C., and the demulsification time is 30-60 min.