An efficient compound quaternary ammonium salt reverse demulsifier and its preparation method

Abstract

The present invention relates to an efficient compounded quaternary ammonium salt reverse demulsifier and a preparation method thereof, belonging to the technical field of oilfield chemicals. The efficient compounded quaternary ammonium salt reverse demulsifier of the present invention is compounded by nano-scale quaternary ammonium salt modified titanium dioxide and reticular polymer quaternary ammonium salt. The nano-scale quaternary ammonium salt modified titanium dioxide has a high specific surface area and can form an integral body with the reticular polymer quaternary ammonium salt through intermolecular forces and hydrogen bonds, playing a nodal role and improving the spreading degree of the reticular polymer quaternary ammonium salt, so that the flexible reticular polymer quaternary ammonium salt with a longitudinal polyepichlorohydrin quaternary ammonium salt main chain and a transverse four-segment polyepichlorohydrin quaternary ammonium salt chain segment structure has a high distribution density and uniformity of quaternary ammonium salt at a lower dosage and a lower temperature. The transverse and longitudinal polyepichlorohydrin quaternary ammonium salt chain segments cooperate with each other to jointly play a demulsifying role, improve the demulsification effect, and effectively remove oil products and suspended solids.

Description

Technical Field

[0001] The present invention relates to a high - efficiency compounded quaternary ammonium salt reverse demulsifier and a preparation method thereof, belonging to the technical field of oilfield chemicals. Background Art

[0002] With the exploitation of oilfield resources, most oilfields have entered the middle and late high - water - cut exploitation stages. The output of water - in - oil emulsion produced water increases, the water quality changes, and the treatment difficulty increases. The water quality is becoming increasingly complex, showing problems such as high salinity, high oil - in - water emulsification degree, high small - particle - size suspended solids, high bacterial content, high corrosion rate, as well as characteristics such as low pH and low oil - water density difference. The phase state is stable, and the oil - water separation is difficult, which restricts the development of oil production technology. Therefore, the requirements for demulsifying water - in - oil emulsion produced water are gradually increasing.

[0003] At present, the reverse demulsifiers used for demulsifying water - in - oil emulsions mainly include low - molecular - weight electrolytes, alcohols, surfactants, and high - molecular polymers. Among them, polyquaternary ammonium salt demulsifiers have the advantages of good water solubility and fast diffusion speed, and have been widely studied. Chinese patent document CN112584910B discloses a hyperbranched quaternary ammonium salt reverse demulsifier prepared by the azo - Michael addition reaction of polyamine (Michael donor) and activated olefin (Michael acceptor). However, the distribution of quaternary ammonium salt segments in its structure is disorderly, resulting in general demulsification effect, and it needs to be carried out at a higher temperature to obtain a better demulsification effect, wasting energy and having a relatively high treatment cost. Summary of the Invention

[0004] The purpose of the present invention is to provide a high - efficiency compounded quaternary ammonium salt reverse demulsifier and a preparation method thereof, so as to solve the problems of large dosage and high demulsification temperature when the current quaternary ammonium salt reverse demulsifier is used for demulsifying oilfield produced water.

[0005] The present invention provides a high - efficiency compounded quaternary ammonium salt reverse demulsifier, which is composed of a polymer quaternary ammonium salt and quaternary ammonium salt - modified nano - titanium dioxide, and the mass ratio of the polymer quaternary ammonium salt to the quaternary ammonium salt - modified nano - titanium dioxide is 18 - 20:1; the quaternary ammonium salt - modified nano - titanium dioxide is prepared by reacting nano - titanium dioxide with dimethyloctadecyl [3 - (trimethoxysilyl) propyl] ammonium chloride;

[0006] The preparation method of the polymer quaternary ammonium salt is as follows:

[0007] (1) React 2 - hydroxy - 1,3 - propanediamine and bromopropane with a molar ratio of 1:2 to obtain a secondary amine compound;

[0008] (2) React the secondary amino group in the secondary amine compound with di - tert - butyl dicarbonate to obtain an amine - ester compound;

[0009] (3) React the hydroxyl group and terminal acyl chloride group in the amine ester compound with polyepichlorohydrin to obtain a polyepichlorohydrin-bridged amine ester compound; the molar ratio of the amine ester compound to the terminal acyl chloride group polyepichlorohydrin is 2:1, and the terminal acyl chloride group polyepichlorohydrin is prepared by subjecting the product obtained from the reaction of polyepichlorohydrin diol and succinic anhydride to an acyl chlorination reaction; the polyepichlorohydrin diol is prepared by subjecting ethylene glycol and epichlorohydrin with a molar ratio of 0.2 - 0.3:1 to a cationic ring-opening polymerization reaction;

[0010] (4) Deprotect the tert-butoxycarbonyl group in the polyepichlorohydrin-bridged amine ester compound to obtain a polyepichlorohydrin-bridged secondary amine compound;

[0011] (5) React the secondary amino group in the polyepichlorohydrin-bridged secondary amine compound with epichlorohydrin to obtain a polyepichlorohydrin-bridged four-arm chlorohydrin compound; then subject the polyepichlorohydrin-bridged four-arm chlorohydrin compound and epichlorohydrin to a cationic ring-opening polymerization reaction to obtain a polyepichlorohydrin-bridged four-arm polyepichlorohydrin; in the cationic ring-opening polymerization reaction, the molar ratio of epichlorohydrin to the polyepichlorohydrin-bridged secondary amine compound used for preparing the polyepichlorohydrin-bridged four-arm chlorohydrin compound is 0.1 - 0.2:1;

[0012] (6) Subject the tertiary amino group in the polyepichlorohydrin-bridged four-arm polyepichlorohydrin to a quaternization reaction with an alkyl bromide to obtain an ammonium bromide-bridged product; then subject the chlorine atom in the ammonium bromide-bridged product to a quaternization reaction with triethylamine to obtain a polymeric quaternary ammonium salt; the alkyl bromide is one of dodecyl bromide, undecyl bromide, n-decyl bromide, n-butyl bromide, n-pentyl bromide, n-hexyl bromide, n-heptyl bromide, n-octyl bromide, and n-nonyl bromide.

[0013] Preferably, in step (1) of the preparation method of the polymeric quaternary ammonium salt, when 2-hydroxy-1,3-propanediamine reacts with bromopropane, sodium hydroxide is used as a catalyst, and the molar ratio of 2-hydroxy-1,3-propanediamine, bromopropane, and sodium hydroxide is 1:2:2.3 - 2.5; the reaction temperature of 2-hydroxy-1,3-propanediamine and bromopropane is 60 - 70 °C, and the reaction time is 2 - 3 h.

[0014] Preferably, in step (2) of the preparation method of the polymeric quaternary ammonium salt, the molar ratio of di-tert-butyl dicarbonate to the secondary amine compound is 2:1.

[0015] Preferably, in step (3) of the preparation method of the polymeric quaternary ammonium salt, boron trifluoride diethyl ether complex is used as the catalyst in the cationic ring-opening polymerization reaction, and the mass of the boron trifluoride diethyl ether complex is 0.15-0.2% of the sum of the masses of ethylene glycol and epichlorohydrin; the temperature of the cationic ring-opening polymerization reaction is 0-5 °C, and the time is 3-4 h; the temperature of the reaction between polyepichlorohydrin diol and succinic anhydride is 50-60 °C, and the time is 5-8 h, and the molar ratio of polyepichlorohydrin diol to succinic anhydride is 1:2; in step (3), the acyl chlorination reaction is to mix the product obtained by the reaction of polyepichlorohydrin diol and succinic anhydride with thionyl chloride at a mass ratio of 10:50-60 and then reflux and react for 24-30 h.

[0016] Preferably, the method for deprotecting the tert-butoxycarbonyl group in the polyepichlorohydrin-bridged amine ester compound in step (4) of the preparation method of the polymeric quaternary ammonium salt is as follows: adding the dioxane solution of the polyepichlorohydrin-bridged amine ester compound into the dioxane solution of hydrogen chloride, mixing and reacting for 4-5 h, and then adding sodium hydroxide to adjust the pH of the reaction solution to 7.5-8; the concentration of the dioxane solution of hydrogen chloride is 2 mol / L, and the mass ratio of the dioxane solution of the polyepichlorohydrin-bridged amine ester compound to the dioxane solution of hydrogen chloride is 1:2-2.5.

[0017] Preferably, in step (5) of the preparation method of the polymeric quaternary ammonium salt, the molar ratio of the polyepichlorohydrin-bridged secondary amine compound to epichlorohydrin is 1:4-4.1 when preparing the polyepichlorohydrin-bridged four-arm chlorohydrin compound, the reaction temperature is 58-65 °C, and the time is 5-7 h; in step (5), boron trifluoride diethyl ether complex is used as the catalyst in the cationic ring-opening polymerization reaction, and the mass of the boron trifluoride diethyl ether complex is 0.15-0.2% of the sum of the masses of the polyepichlorohydrin-bridged secondary amine compound and epichlorohydrin.

[0018] Preferably, when quaternizing the tertiary amino group in the polyepichlorohydrin-bridged four-arm polyepichlorohydrin with bromoalkane in step (6) of the preparation method of the polymeric quaternary ammonium salt, the molar ratio of the polyepichlorohydrin-bridged four-arm polyepichlorohydrin to bromoalkane is 1:4.5-5, the reaction temperature is 85-90 °C, and the time is 6-8 h; the molar ratio of the chlorine atom to triethylamine in the ammonium bromide-bridged product is 1:1.1-1.3, and the temperature of the quaternization reaction between the chlorine atom and triethylamine in the ammonium bromide-bridged product is 85-90 °C, and the time is 6-8 h.

[0019] Preferably, the mass ratio of the nano-titanium dioxide to dimethyloctadecyl [3-(trimethoxysilyl)propyl] ammonium chloride is 1:4-5, and the reaction temperature of the nano-titanium dioxide and dimethyloctadecyl [3-(trimethoxysilyl)propyl] ammonium chloride is 70-80 °C, and the time is 28-30 h.

[0020] Preferably, the average particle size of the nano-titanium dioxide is 25-40 nm.

[0021] The present invention also provides a preparation method of the high-efficiency compound quaternary ammonium salt reverse demulsifier as described above, comprising the following steps: mixing the polymeric quaternary ammonium salt and the quaternary ammonium salt modified nano-titanium dioxide evenly.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] (1) For the high-efficiency compound quaternary ammonium salt reverse demulsifier of the present invention, firstly, the longitudinal polyepichlorohydrin quaternary ammonium salt main chain is connected to the transverse four-segment polyepichlorohydrin quaternary ammonium salt chain segments to form a dense polymeric quaternary ammonium salt molecule with dense quaternary ammonium salt long chain segments both longitudinally and transversely. Through the fixing and tension constraint effects of chemical bonds, the dense quaternary ammonium salt long chain segments longitudinally and transversely can form a regular flexible network structure, avoiding the entanglement of the quaternary ammonium salt long chain segments, ensuring that the demulsifier can effectively improve the distribution density and uniformity of the quaternary ammonium salt at a lower dosage and lower temperature. Then, the polymeric quaternary ammonium salt and the quaternary ammonium salt modified nano-titanium dioxide with long fatty chains are compounded. The nano-scale quaternary ammonium salt modified titanium dioxide has a high specific surface area and can form an integral body with the network polymeric quaternary ammonium salt through intermolecular forces and hydrogen bonds, etc., playing a nodal role, further improving the spreading degree of the network polymeric quaternary ammonium salt, enabling the longitudinal and transverse polyepichlorohydrin quaternary ammonium salt chain segments of the polymeric quaternary ammonium salt to cooperate with each other, jointly exerting the demulsification effect, and effectively removing oil products and suspended substances.

[0024] (2) The present invention adjusts the molar ratio of ethylene glycol and epichlorohydrin to ensure that the molecular weight of the longitudinal main chain polyepichlorohydrin quaternary ammonium salt chain segments of the polymeric quaternary ammonium salt is within a suitable range, and at the same time adjusts the molar ratio of epichlorohydrin and the polyepichlorohydrin-bridged secondary amine compound to ensure that the molecular weight of the polyepichlorohydrin quaternary ammonium salt chain segments grafted on the transverse four arms is within a suitable range, which can avoid the entanglement and kinking of the longitudinal main chain polyepichlorohydrin quaternary ammonium salt chain segments in the wastewater or the overlapping entanglement and kinking of the transverse four-arm polyepichlorohydrin quaternary ammonium salt chain segments, and at the same time ensure the stretching and opening of the longitudinal main chain quaternary ammonium salt chain segments and the transverse four-arm polyepichlorohydrin quaternary ammonium salt chain segments, enabling the longitudinal main chain quaternary ammonium salt chain segments and the transverse four-arm polyepichlorohydrin quaternary ammonium salt chain segments to cooperate with each other, thereby improving the demulsification effect. Description of the Drawings

[0025] Figure 1 It is the nuclear magnetic hydrogen spectrum diagram of the polyepichlorohydrin-bridged secondary amine compound prepared in the preparation method of the polymeric quaternary ammonium salt in Example 1 of the present invention. Detailed Embodiments

[0026] The following examples are intended to further illustrate the content of the present invention rather than limit the protection scope of the present invention.

[0027] Specific embodiments of the high-efficiency compound quaternary ammonium salt reverse demulsifier of the present invention and its preparation method are as follows:

[0028] Example 1

[0029] The high-efficiency compound quaternary ammonium salt reverse demulsifier of this example is composed of a polymer quaternary ammonium salt and quaternary ammonium salt-modified nano-titanium dioxide, and the mass ratio of the polymer quaternary ammonium salt to the quaternary ammonium salt-modified nano-titanium dioxide is 18:1.

[0030] Among them, the preparation method of the polymer quaternary ammonium salt includes the following steps:

[0031] (1) Add 2-hydroxy-1,3-propanediamine to the reaction kettle, and then drop bromopropane into the reaction kettle at 30°C. After the dropping is completed, drop a sodium hydroxide solution with a mass fraction of 35% into the reaction kettle. After the dropping is completed, heat the materials in the reaction kettle to 60°C, stir and react for 2 h, cool to room temperature, extract the reaction product with dichloromethane, then rotary evaporate the extracted organic phase to obtain a concentrate, and then purify the concentrate by column chromatography (the eluent is composed of methanol and dichloromethane with a volume ratio of 1:20) to obtain a secondary amine compound. Among them, the molar ratio of 2-hydroxy-1,3-propanediamine, bromopropane and sodium hydroxide is 1:2:2.3. The structural formula of the secondary amine compound is as follows: .

[0032] (2) Add di-tert-butyl dicarbonate and ethyl acetate to the reaction kettle, stir evenly to obtain a di-tert-butyl dicarbonate solution with a mass fraction of 45%; then cool the di-tert-butyl dicarbonate solution to -5°C, and drop a 40% ethyl acetate solution of the secondary amine compound into the reaction kettle under stirring conditions. After the dropping is completed, stir and react the materials in the reaction kettle at room temperature for 18 h, then quench the reaction with water, extract the reaction product with ethyl acetate, rotary evaporate the extracted organic phase to obtain a concentrate, and then purify the concentrate by column chromatography (the eluent is composed of petroleum ether and ethyl acetate with a volume ratio of 3:1) to obtain an amine ester compound. Among them, the molar ratio of di-tert-butyl dicarbonate to the secondary amine compound is 2:1. The structural formula of the amine ester compound is as follows: .

[0033] (3) Add 40 parts by mass of 1,2-dichloroethane to the reaction kettle, introduce nitrogen into the reaction kettle. After the air in the reaction kettle is completely replaced, add ethylene glycol and boron trifluoride diethyl ether complex catalyst to the reaction kettle. After stirring evenly, cool the materials in the reaction kettle to 0 °C. Then, under stirring conditions, dropwise add a 1,2-dichloroethane solution (mass fraction 60%) containing 50 parts by mass of epichlorohydrin to the reaction kettle. After the dropping is completed, continue to stir and react at 0 °C for 3 h. After the reaction is completed, add water to the reaction kettle for extraction, and subject the extracted organic phase to vacuum distillation to obtain polyepichlorohydrin diol. Among them, the molar ratio of ethylene glycol to epichlorohydrin is 0.2:1, and the mass of the boron trifluoride diethyl ether complex catalyst is 0.15% of the sum of the masses of ethylene glycol and epichlorohydrin. The structural formula of polyepichlorohydrin diol is as follows: 。

[0034] (4) Add polyepichlorohydrin diol and succinic anhydride to the reaction kettle, then add chloroform, heat to 50 °C, and stir and react for 5 h. Remove the chloroform in the reaction kettle by vacuum distillation to obtain carboxyl-terminated polyepichlorohydrin; the molar ratio of polyepichlorohydrin diol to succinic anhydride is 1:2, and the mass of chloroform is 40% of the sum of the masses of polyepichlorohydrin diol and succinic anhydride.

[0035] Then add thionyl chloride to the reaction kettle, heat to reflux, stir and reflux for 24 h, and remove the excess thionyl chloride in the reaction kettle by vacuum distillation to obtain acyl chloride-terminated polyepichlorohydrin; the mass ratio of carboxyl-terminated polyepichlorohydrin to thionyl chloride is 10:50. The structural formula of acyl chloride-terminated polyepichlorohydrin is as follows: 。

[0036] (5) Add the amine ester compound and dichloromethane to the reaction kettle, stir evenly to obtain a 30% mass fraction solution of the amine ester compound; add acyl chloride-terminated polyepichlorohydrin and dichloromethane to the reaction kettle, stir evenly to obtain a 20% mass fraction solution of acyl chloride-terminated polyepichlorohydrin; then, under stirring and at 0 °C, dropwise add the acyl chloride-terminated polyepichlorohydrin solution to the amine ester compound solution. After the dropping is completed, add triethylamine, continue to stir and react at room temperature for 12 h, filter, and rotary evaporate the filtrate to obtain polyepichlorohydrin-bridged amine ester compound. Among them, the molar ratio of the amine ester compound, acyl chloride-terminated polyepichlorohydrin, and triethylamine is 2:1:1.2. The structural formula of polyepichlorohydrin-bridged amine ester compound is as follows: 。

[0037] (6) Under stirring and at 0 °C, a dioxane solution of a polyepichlorohydrin-bridged amine ester compound with a mass fraction of 45% was added dropwise to a dioxane solution of hydrogen chloride (concentration: 2 mol / L). After the addition was completed, the reaction was continued by stirring at room temperature for 4 h. Then, sodium hydroxide was added to adjust the pH of the reaction solution to 7.5. Subsequently, water and ethyl acetate were added to the reaction solution for extraction. The obtained organic phase was distilled under reduced pressure and dried to obtain a polyepichlorohydrin-bridged secondary amine compound (the proton nuclear magnetic resonance spectrum is as shown in Figure 1 ). Among them, the mass ratio of the dioxane solution of the polyepichlorohydrin-bridged amine ester compound to the dioxane solution of hydrogen chloride is 1:2. The structural formula of the polyepichlorohydrin-bridged secondary amine compound is as follows: .

[0038] (7) The polyepichlorohydrin-bridged secondary amine compound and 1,2-dichloroethane were added to a reaction kettle and stirred evenly. Then, the mixture was heated to 58 °C. Subsequently, epichlorohydrin was added dropwise to the reaction kettle under stirring. After the addition was completed, the reaction was continued by stirring for 5 h, and a polyepichlorohydrin-bridged tetra-armed chlorohydrin compound was formed in the reaction kettle. Among them, the molar ratio of the polyepichlorohydrin-bridged secondary amine compound to epichlorohydrin is 1:4, and the mass of 1,2-dichloroethane is 50% of the sum of the masses of the polyepichlorohydrin-bridged secondary amine compound and epichlorohydrin.

[0039] Then, nitrogen was introduced into the reaction kettle. After the air in the reaction kettle was completely replaced, boron trifluoride ether complex catalyst was added to the reaction kettle. After stirring evenly, the materials in the reaction kettle were cooled to 0 °C. Then, under stirring, a 1,2-dichloroethane solution of epichlorohydrin (mass fraction: 60%) was added dropwise to the reaction kettle. After the addition was completed, the reaction was continued by stirring at 0 °C for 3 h. After the reaction was completed, water was added to the reaction kettle for extraction. The obtained organic phase was distilled under reduced pressure to obtain polyepichlorohydrin-bridged tetra-armed polyepichlorohydrin. Among them, the molar ratio of epichlorohydrin to the polyepichlorohydrin-bridged secondary amine compound is 0.1:1, and the mass of the boron trifluoride ether complex catalyst is 0.15% of the sum of the masses of the polyepichlorohydrin-bridged secondary amine compound and epichlorohydrin. The structural formula of the polyepichlorohydrin-bridged tetra-armed polyepichlorohydrin is as follows: .

[0040] (8) Add polyepichlorohydrin-bridged tetra-arm polyepichlorohydrin and butanol into a reaction kettle, stir evenly, then dropwise add alkyl bromide into the reaction kettle at 85 °C under stirring conditions. After the dropping is completed, continue to stir and reflux at 85 °C for 6 h, and then perform vacuum distillation to remove the solvent butanol and unreacted alkyl bromide to obtain an ammonium bromide-bridged product. Among them, the molar ratio of polyepichlorohydrin-bridged tetra-arm polyepichlorohydrin to alkyl bromide is 1:4.5, the alkyl bromide is n-decyl bromide, and the mass of butanol is 60% of the sum of the masses of polyepichlorohydrin-bridged tetra-arm polyepichlorohydrin and alkyl bromide.

[0041] (9) Add the ammonium bromide-bridged product and butanol into a reaction kettle, stir evenly, then dropwise add triethylamine into the reaction kettle at 85 °C under stirring conditions. After the dropping is completed, continue to stir and reflux at 85 °C for 6 h, and then perform vacuum distillation to remove the solvent butanol and unreacted triethylamine to obtain a polymeric quaternary ammonium salt. Among them, the molar ratio of chlorine element in the ammonium bromide-bridged product to triethylamine is 1:1.1, and the mass of butanol is 60% of the sum of the masses of the ammonium bromide-bridged product and triethylamine.

[0042] A preparation method of quaternary ammonium salt-modified nano-titanium dioxide includes the following steps:

[0043] Disperse nano-titanium dioxide (average particle size is 25 nm) in water to obtain a dispersion with a mass fraction of 0.7%, then add dimethyloctadecyl [3-(trimethoxysilyl)propyl] ammonium chloride to the dispersion, heat to 70 °C, stir and react for 30 h, filter, wash the filter cake with water and ethanol respectively, and dry to obtain quaternary ammonium salt-modified nano-titanium dioxide; the mass ratio of nano-titanium dioxide to dimethyloctadecyl [3-(trimethoxysilyl)propyl] ammonium chloride is 1:5.

[0044] Example 2

[0045] The high-efficiency compound quaternary ammonium salt demulsifier in this example is composed of a polymeric quaternary ammonium salt and quaternary ammonium salt-modified nano-titanium dioxide, and the mass ratio of the polymeric quaternary ammonium salt to the quaternary ammonium salt-modified nano-titanium dioxide is 19:1.

[0046] Among them, the preparation method of the polymeric quaternary ammonium salt includes the following steps:

[0047] (1) Add 2-hydroxy-1,3-propanediamine to the reaction kettle, and then drop bromopropane into the reaction kettle at 32 °C. After the dropping is completed, drop a sodium hydroxide solution with a mass fraction of 38% into the reaction kettle. After the dropping is completed, heat the materials in the reaction kettle to 65 °C, stir and react for 2.5 h, cool to room temperature, extract the reaction product with dichloromethane, then rotary evaporate the obtained organic phase to obtain a concentrate, and then purify the concentrate by column chromatography (the eluent is composed of methanol and dichloromethane with a volume ratio of 1:20) to obtain a secondary amine compound. Among them, the molar ratio of 2-hydroxy-1,3-propanediamine, bromopropane and sodium hydroxide is 1:2:2.4. The structural formula of the secondary amine compound is as follows: 。

[0048] (2) Add di-tert-butyl dicarbonate and ethyl acetate to the reaction kettle, stir evenly to obtain a di-tert-butyl dicarbonate solution with a mass fraction of 47%; then cool the di-tert-butyl dicarbonate solution to -3 °C, and under stirring conditions, drop a 45% ethyl acetate solution of the secondary amine compound into the reaction kettle. After the dropping is completed, stir the materials in the reaction kettle at room temperature for 20 h, then add water to quench the reaction, and then extract the reaction product with ethyl acetate. Rotary evaporate the obtained organic phase to obtain a concentrate, and then purify the concentrate by column chromatography (the eluent is composed of petroleum ether and ethyl acetate with a volume ratio of 3:1) to obtain an amine ester compound. Among them, the molar ratio of di-tert-butyl dicarbonate and the secondary amine compound is 2:1. The structural formula of the amine ester compound is as follows: 。

[0049] (3) Add 40 parts by mass of 1,2-dichloroethane to the reaction kettle, introduce nitrogen into the reaction kettle, and after the air in the reaction kettle is completely replaced, add ethylene glycol and boron trifluoride diethyl ether complex catalyst to the reaction kettle. After stirring evenly, cool the materials in the reaction kettle to 2 °C, and then under stirring conditions, drop a 1,2-dichloroethane solution (mass fraction of 65%) containing 50 parts by mass of epichlorohydrin into the reaction kettle. After the dropping is completed, continue to stir and react at 2 °C for 3.5 h. After the reaction is completed, add water to the reaction kettle for extraction, and distill the obtained organic phase under reduced pressure to obtain polyepichlorohydrin diol. Among them, the molar ratio of ethylene glycol and epichlorohydrin is 0.25:1, and the mass of the boron trifluoride diethyl ether complex catalyst is 0.18% of the sum of the masses of ethylene glycol and epichlorohydrin. The structural formula of polyepichlorohydrin diol is as follows: 。

[0050] (4) Add polyepichlorohydrin diol and succinic anhydride into a reaction kettle, then add chloroform, heat to 55 °C, stir and react for 7 h, and remove chloroform in the reaction kettle by vacuum distillation to obtain carboxyl-terminated polyepichlorohydrin; the molar ratio of polyepichlorohydrin diol to succinic anhydride is 1:2, and the mass of chloroform is 45% of the sum of the masses of polyepichlorohydrin diol and succinic anhydride.

[0051] Then add thionyl chloride into the reaction kettle, heat to reflux, stir and reflux for 26 h, and remove excess thionyl chloride in the reaction kettle by vacuum distillation to obtain acyl chloride-terminated polyepichlorohydrin; the mass ratio of carboxyl-terminated polyepichlorohydrin to thionyl chloride is 10:55. The structural formula of acyl chloride-terminated polyepichlorohydrin is as follows: .

[0052] (5) Add the amine ester compound and dichloromethane into a reaction kettle, stir evenly to obtain a 40% by mass amine ester compound solution; add acyl chloride-terminated polyepichlorohydrin and dichloromethane into the reaction kettle, stir evenly to obtain a 28% by mass acyl chloride-terminated polyepichlorohydrin solution; then, under stirring and at 3 °C, drop the acyl chloride-terminated polyepichlorohydrin solution into the amine ester compound solution. After the dropping is completed, add triethylamine, and continue to stir and react at room temperature for 14 h, filter, and rotary evaporate the filtrate to obtain polyepichlorohydrin-bridged amine ester compound. Among them, the molar ratio of the amine ester compound, acyl chloride-terminated polyepichlorohydrin and triethylamine is 2:1:1.3. The structural formula of polyepichlorohydrin-bridged amine ester compound is as follows: .

[0053] (6) Under stirring and at 2 °C, drop a 48% by mass dioxane solution of polyepichlorohydrin-bridged amine ester compound into a dioxane solution of hydrogen chloride (concentration: 2 mol / L). After the dropping is completed, continue to stir and react at room temperature for 4.5 h, then add sodium hydroxide to adjust the pH of the reaction solution to 7.5, then add water and ethyl acetate to the reaction solution for extraction, and distill the extracted organic phase under reduced pressure and dry it to obtain polyepichlorohydrin-bridged secondary amine compound. Among them, the mass ratio of the dioxane solution of polyepichlorohydrin-bridged amine ester compound to the dioxane solution of hydrogen chloride is 1:2.3. The structural formula of polyepichlorohydrin-bridged secondary amine compound is as follows: .

[0054] (7) Add the polyepichlorohydrin-bridged secondary amine compound and 1,2-dichloroethane into the reaction kettle, stir evenly and then heat to 60 °C. Then, under stirring conditions, dropwise add epichlorohydrin into the reaction kettle. After the dropping is completed, continue to stir and react for 6 h, and a polyepichlorohydrin-bridged tetra-armed chlorohydrin compound is formed in the reaction kettle. Among them, the molar ratio of the polyepichlorohydrin-bridged secondary amine compound to epichlorohydrin is 1:4.05, and the mass of 1,2-dichloroethane is 55% of the sum of the masses of the polyepichlorohydrin-bridged secondary amine compound and epichlorohydrin.

[0055] Then, introduce nitrogen into the reaction kettle. After the air in the reaction kettle is completely replaced, add boron trifluoride ether complex catalyst into the reaction kettle, stir evenly and then cool the materials in the reaction kettle to 3 °C. Then, under stirring conditions, dropwise add a 1,2-dichloroethane solution of epichlorohydrin (mass fraction of 65%) into the reaction kettle. After the dropping is completed, continue to stir and react at 2 °C for 3.5 h. After the reaction is completed, add water into the reaction kettle for extraction, and subject the obtained organic phase to vacuum distillation to obtain polyepichlorohydrin-bridged tetra-armed polyepichlorohydrin. Among them, the molar ratio of epichlorohydrin to the polyepichlorohydrin-bridged secondary amine compound is 0.15:1, and the mass of the boron trifluoride ether complex catalyst is 0.18% of the sum of the masses of the polyepichlorohydrin-bridged secondary amine compound and epichlorohydrin. The structural formula of the polyepichlorohydrin-bridged tetra-armed polyepichlorohydrin is as follows: 。

[0056] (8) Add the polyepichlorohydrin-bridged tetra-armed polyepichlorohydrin and butanol into the reaction kettle, stir evenly, and then under stirring conditions at 88 °C, dropwise add bromoalkane into the reaction kettle. After the dropping is completed, continue to stir and reflux at 87 °C for 7 h, and then carry out vacuum distillation to remove the solvent butanol and unreacted bromoalkane to obtain an ammonium bromide-bridged product. Among them, the molar ratio of the polyepichlorohydrin-bridged tetra-armed polyepichlorohydrin to bromoalkane is 1:4.7, the bromoalkane is n-decyl bromide, and the mass of butanol is 70% of the sum of the masses of the polyepichlorohydrin-bridged tetra-armed polyepichlorohydrin and bromoalkane.

[0057] (9) Add the ammonium bromide-bridged product and butanol into the reaction kettle, stir evenly, and then under stirring conditions at 88 °C, dropwise add triethylamine into the reaction kettle. After the dropping is completed, continue to stir and reflux at 88 °C for 7 h, and then carry out vacuum distillation to remove the solvent butanol and unreacted triethylamine to obtain a polymer quaternary ammonium salt. Among them, the molar ratio of chlorine element to triethylamine in the ammonium bromide-bridged product is 1:1.2, and the mass of butanol is 70% of the sum of the masses of the ammonium bromide-bridged product and triethylamine.

[0058] A preparation method of quaternary ammonium salt-modified nano-titanium dioxide includes the following steps:

[0059] Disperse nano-titanium dioxide (average particle size of 30 nm) in water to obtain a dispersion with a mass fraction of 0.8%. Then add dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride to the dispersion, heat to 75 °C, stir and react for 29 h, filter, wash the filter cake with water and ethanol respectively, and dry to obtain quaternary ammonium salt-modified nano-titanium dioxide; the mass ratio of nano-titanium dioxide to dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride is 1:4.5.

[0060] Example 3

[0061] The high-efficiency compound quaternary ammonium salt reverse demulsifier of this example is composed of a polymer quaternary ammonium salt and quaternary ammonium salt-modified nano-titanium dioxide, and the mass ratio of the polymer quaternary ammonium salt to the quaternary ammonium salt-modified nano-titanium dioxide is 20:1.

[0062] Among them, the preparation method of the polymer quaternary ammonium salt includes the following steps:

[0063] (1) Add 2-hydroxy-1,3-propanediamine to the reaction kettle, and then drop bromopropane into the reaction kettle at 35 °C. After the dropping is completed, drop a 40% sodium hydroxide solution by mass fraction into the reaction kettle. After the dropping is completed, heat the materials in the reaction kettle to 70 °C, stir and react for 3 h, cool to room temperature, extract the reaction product with dichloromethane, then rotary evaporate the extracted organic phase to obtain a concentrate, and then purify the concentrate by column chromatography (the eluent is composed of methanol and dichloromethane with a volume ratio of 1:20) to obtain a secondary amine compound. Among them, the molar ratio of 2-hydroxy-1,3-propanediamine, bromopropane and sodium hydroxide is 1:2:2.5. The structural formula of the secondary amine compound is as follows: .

[0064] (2) Add di-tert-butyl dicarbonate and ethyl acetate to the reaction kettle, stir evenly to obtain a 50% di-tert-butyl dicarbonate solution by mass fraction; then cool the di-tert-butyl dicarbonate solution to 0 °C, and drop a 50% ethyl acetate solution of the secondary amine compound into the reaction kettle under stirring conditions. After the dropping is completed, stir the materials in the reaction kettle at room temperature for 24 h, then add water to quench the reaction, and then extract the reaction product with ethyl acetate. Rotary evaporate the extracted organic phase to obtain a concentrate, and then purify the concentrate by column chromatography (the eluent is composed of petroleum ether and ethyl acetate with a volume ratio of 3:1) to obtain an amine ester compound. Among them, the molar ratio of di-tert-butyl dicarbonate to the secondary amine compound is 2:1. The structural formula of the amine ester compound is as follows: .

[0065] (3) Add 40 parts by mass of 1,2-dichloroethane into the reaction kettle, introduce nitrogen into the reaction kettle. After the air in the reaction kettle is completely replaced, add ethylene glycol and boron trifluoride diethyl ether complex catalyst into the reaction kettle. After stirring evenly, cool the materials in the reaction kettle to 5 °C. Then, under stirring conditions, dropwise add a 1,2-dichloroethane solution (mass fraction 70%) containing 50 parts by mass of epichlorohydrin into the reaction kettle. After the dropping is completed, continue to stir and react at 5 °C for 4 h. After the reaction is completed, add water into the reaction kettle for extraction, and subject the extracted organic phase to vacuum distillation to obtain polyepichlorohydrin diol. Among them, the molar ratio of ethylene glycol to epichlorohydrin is 0.3:1, and the mass of the boron trifluoride diethyl ether complex catalyst is 0.2% of the sum of the masses of ethylene glycol and epichlorohydrin. The structural formula of polyepichlorohydrin diol is as follows: 。

[0066] (4) Add polyepichlorohydrin diol and succinic anhydride into the reaction kettle, then add chloroform, heat to 60 °C, stir and react for 8 h, and remove chloroform in the reaction kettle by vacuum distillation to obtain terminal carboxyl polyepichlorohydrin; the molar ratio of polyepichlorohydrin diol to succinic anhydride is 1:2, and the mass of chloroform is 50% of the sum of the masses of polyepichlorohydrin diol and succinic anhydride.

[0067] Then add thionyl chloride into the reaction kettle, heat to reflux, stir and reflux for 30 h, and remove the excess thionyl chloride in the reaction kettle by vacuum distillation to obtain terminal acyl chloride polyepichlorohydrin; the mass ratio of terminal carboxyl polyepichlorohydrin to thionyl chloride is 10:60. The structural formula of terminal acyl chloride polyepichlorohydrin is as follows: 。

[0068] (5) Add the amine ester compound and dichloromethane into the reaction kettle, stir evenly to obtain an amine ester compound solution with a mass fraction of 45%; add terminal acyl chloride polyepichlorohydrin and dichloromethane into the reaction kettle, stir evenly to obtain a terminal acyl chloride polyepichlorohydrin solution with a mass fraction of 35%; then, under stirring and at 5 °C, dropwise add the terminal acyl chloride polyepichlorohydrin solution into the amine ester compound solution. After the dropping is completed, add triethylamine, continue to stir and react at room temperature for 15 h, filter, and rotary evaporate the filtrate to obtain polyepichlorohydrin bridged amine ester compound. Among them, the molar ratio of the amine ester compound, terminal acyl chloride polyepichlorohydrin and triethylamine is 2:1:1.4. The structural formula of polyepichlorohydrin bridged amine ester compound is as follows: 。

[0069] (6) Under stirring and at 5 °C, a dioxane solution of a polyepichlorohydrin-bridged amine ester compound with a mass fraction of 50% was added dropwise to a dioxane solution of hydrogen chloride (concentration: 2 mol / L). After the addition was completed, the reaction was continued under stirring at room temperature for 5 h. Then, sodium hydroxide was added to adjust the pH of the reaction solution to 8. Subsequently, water and ethyl acetate were added to the reaction solution for extraction. The organic phase obtained by extraction was distilled under reduced pressure and dried to obtain a polyepichlorohydrin-bridged secondary amine compound. Among them, the mass ratio of the dioxane solution of the polyepichlorohydrin-bridged amine ester compound to the dioxane solution of hydrogen chloride was 1:2.5. The structural formula of the polyepichlorohydrin-bridged secondary amine compound is as follows: 。

[0070] (7) The polyepichlorohydrin-bridged secondary amine compound and 1,2-dichloroethane were added to a reaction kettle and stirred evenly. Then, the mixture was heated to 65 °C. Subsequently, epichlorohydrin was added dropwise to the reaction kettle under stirring. After the addition was completed, the reaction was continued under stirring for 7 h, and a polyepichlorohydrin-bridged four-armed chlorohydrin compound was formed in the reaction kettle. Among them, the molar ratio of the polyepichlorohydrin-bridged secondary amine compound to epichlorohydrin was 1:4.1, and the mass of 1,2-dichloroethane was 60% of the sum of the masses of the polyepichlorohydrin-bridged secondary amine compound and epichlorohydrin.

[0071] Then, nitrogen was introduced into the reaction kettle. After the air in the reaction kettle was completely replaced, boron trifluoride ethyl ether complex catalyst was added to the reaction kettle and stirred evenly. Then, the materials in the reaction kettle were cooled to 5 °C. Subsequently, a 1,2-dichloroethane solution of epichlorohydrin (mass fraction: 70%) was added dropwise to the reaction kettle under stirring. After the addition was completed, the reaction was continued under stirring at 5 °C for 4 h. After the reaction was completed, water was added to the reaction kettle for extraction. The organic phase obtained by extraction was distilled under reduced pressure to obtain polyepichlorohydrin-bridged four-armed polyepichlorohydrin. Among them, the molar ratio of epichlorohydrin to the polyepichlorohydrin-bridged secondary amine compound was 0.2:1, and the mass of the boron trifluoride ethyl ether complex catalyst was 0.2% of the sum of the masses of the polyepichlorohydrin-bridged secondary amine compound and epichlorohydrin. The structural formula of the polyepichlorohydrin-bridged four-armed polyepichlorohydrin is as follows: 。

[0072] (8) Add polyepichlorohydrin-bridged tetra-arm polyepichlorohydrin and butanol into a reaction kettle, stir evenly, and then dropwise add alkyl bromide to the reaction kettle at 90 °C under stirring conditions. After the addition is completed, continue to stir and reflux at 90 °C for 8 h, and then perform vacuum distillation to remove the solvent butanol and unreacted alkyl bromide to obtain an ammonium bromide-bridged product. Among them, the molar ratio of polyepichlorohydrin-bridged tetra-arm polyepichlorohydrin to alkyl bromide is 1:5, the alkyl bromide is n-decyl bromide, and the mass of butanol is 80% of the sum of the masses of polyepichlorohydrin-bridged tetra-arm polyepichlorohydrin and alkyl bromide.

[0073] (9) Add the ammonium bromide-bridged product and butanol into a reaction kettle, stir evenly, and then dropwise add triethylamine to the reaction kettle at 90 °C under stirring conditions. After the addition is completed, continue to stir and reflux at 90 °C for 8 h, and then perform vacuum distillation to remove the solvent butanol and unreacted triethylamine to obtain a polymer quaternary ammonium salt. Among them, the molar ratio of chlorine element in the ammonium bromide-bridged product to triethylamine is 1:1.3, and the mass of butanol is 80% of the sum of the masses of the ammonium bromide-bridged product and triethylamine.

[0074] A preparation method of quaternary ammonium salt-modified nano-titanium dioxide includes the following steps:

[0075] Disperse nano-titanium dioxide (average particle size is 40 nm) in water to obtain a dispersion with a mass fraction of 1%, and then add dimethyloctadecyl [3-(trimethoxysilyl)propyl] ammonium chloride to the dispersion, heat to 80 °C, stir and react for 28 h, filter, wash the filter cake with water and ethanol respectively, and dry to obtain quaternary ammonium salt-modified nano-titanium dioxide; the mass ratio of nano-titanium dioxide to dimethyloctadecyl [3-(trimethoxysilyl)propyl] ammonium chloride is 1:4.

[0076] Example 4

[0077] The difference between the high-efficiency compound quaternary ammonium salt reverse demulsifier in this example and the high-efficiency compound quaternary ammonium salt reverse demulsifier in Example 1 is only that the alkyl bromide in step (8) of the preparation method of the polymer quaternary ammonium salt in the high-efficiency compound quaternary ammonium salt reverse demulsifier in this example is n-butyl bromide.

[0078] Example 5

[0079] The difference between the high-efficiency compound quaternary ammonium salt reverse demulsifier in this example and the high-efficiency compound quaternary ammonium salt reverse demulsifier in Example 1 is only that the alkyl bromide in step (8) of the preparation method of the polymer quaternary ammonium salt in the high-efficiency compound quaternary ammonium salt reverse demulsifier in this example is n-dodecyl bromide.

[0080] The preparation method of the high-efficiency compound quaternary ammonium salt reverse demulsifier in Examples 1-5 is as follows: Stir the polymer quaternary ammonium salt and quaternary ammonium salt-modified nano-titanium dioxide evenly to obtain it.

[0081] Comparative Example 1

[0082] The difference between the high-efficiency compound quaternary ammonium salt reverse demulsifier of this comparative example and that of Example 1 lies only in that the preparation method of the polymer quaternary ammonium salt in the high-efficiency compound quaternary ammonium salt reverse demulsifier of this comparative example includes the following steps:

[0083] (1) Add 2-hydroxy-1,3-propanediamine to the reaction kettle, then drop bromopropane into the reaction kettle at 30°C. After the dropping is completed, drop a sodium hydroxide solution with a mass fraction of 35% into the reaction kettle. After the dropping is completed, heat the materials in the reaction kettle to 60°C, stir and react for 2 h, cool to room temperature, extract the reaction product with dichloromethane, then rotary evaporate the extracted organic phase to obtain a concentrate, and then purify the concentrate by column chromatography (the eluent consists of methanol and dichloromethane with a volume ratio of 1:20) to obtain a secondary amine compound. Among them, the molar ratio of 2-hydroxy-1,3-propanediamine, bromopropane and sodium hydroxide is 1:2:2.3.

[0084] (2) Add the secondary amine compound and 1,2-dichloroethane to the reaction kettle, stir evenly and heat to 58°C, then drop epichlorohydrin into the reaction kettle under stirring conditions. After the dropping is completed, continue to stir and react for 5 h to generate a chlorohydrin compound in the reaction kettle; among them, the molar ratio of the secondary amine compound and epichlorohydrin is 1:2, and the mass of 1,2-dichloroethane is 50% of the sum of the masses of the secondary amine compound and epichlorohydrin.

[0085] Then introduce nitrogen into the reaction kettle. After the air in the reaction kettle is completely replaced, add boron trifluoride ether complex catalyst to the reaction kettle, stir evenly and cool the materials in the reaction kettle to 0°C, and then, under stirring conditions, drop a 1,2-dichloroethane solution of epichlorohydrin (mass fraction of 60%) into the reaction kettle. After the dropping is completed, continue to stir and react at 0°C for 3 h. After the reaction is completed, add water to the reaction kettle for extraction, and distill the extracted organic phase under reduced pressure to obtain polyepichlorohydrin. Among them, the molar ratio of epichlorohydrin and the secondary amine compound is 0.1:1, and the mass of the boron trifluoride ether complex catalyst is 0.15% of the sum of the masses of the secondary amine compound and epichlorohydrin.

[0086] (3) Add polyepichlorohydrin and butanol to the reaction kettle, stir evenly, and then drop bromoalkane into the reaction kettle at 85°C under stirring conditions. After the dropping is completed, continue to stir and reflux at 85°C for 6 h, and then perform reduced pressure distillation to remove the solvent butanol and unreacted bromoalkane to obtain an ammonium bromide product. Among them, the molar ratio of polyepichlorohydrin and bromoalkane is 1:2.5, the bromoalkane is n-decyl bromide, and the mass of butanol is 60% of the sum of the masses of polyepichlorohydrin and bromoalkane.

[0087] (4) Add ammonium bromide product and butanol into the reaction kettle, stir evenly, and then add triethylamine dropwise to the reaction kettle at 85 °C under stirring conditions. After the addition is completed, continue to stir and reflux at 85 °C for 6 h, and then perform vacuum distillation to remove the solvent butanol and unreacted triethylamine to obtain the polymeric quaternary ammonium salt. Among them, the molar ratio of chlorine element to triethylamine in the ammonium bromide product is 1:1.1, and the mass of butanol is 60% of the sum of the masses of the ammonium bromide product and triethylamine.

[0088] Comparative Example 2

[0089] The difference between the high-efficiency compound quaternary ammonium salt reverse demulsifier of this comparative example and that of Example 1 lies only in that the preparation method of the polymeric quaternary ammonium salt in the high-efficiency compound quaternary ammonium salt reverse demulsifier of this comparative example includes the following steps:

[0090] (1) Add 40 parts by mass of 1,2-dichloroethane into the reaction kettle, introduce nitrogen into the reaction kettle. After the air in the reaction kettle is completely replaced, add ethylene glycol and boron trifluoride ether complex catalyst into the reaction kettle, stir evenly, and then cool the materials in the reaction kettle to 0 °C. Then, under stirring conditions, add a 1,2-dichloroethane solution (mass fraction of 60%) containing 50 parts by mass of epichlorohydrin dropwise to the reaction kettle. After the addition is completed, continue to stir and react at 0 °C for 3 h. After the reaction is completed, add water into the reaction kettle for extraction, and perform vacuum distillation on the obtained organic phase to obtain polyepichlorohydrin diol. Among them, the molar ratio of ethylene glycol to epichlorohydrin is 0.2:1, and the mass of the boron trifluoride ether complex catalyst is 0.15% of the sum of the masses of ethylene glycol and epichlorohydrin.

[0091] (2) Add polyepichlorohydrin diol and butanol into the reaction kettle, stir evenly, and then add triethylamine dropwise to the reaction kettle at 85 °C under stirring conditions. After the addition is completed, continue to stir and reflux at 85 °C for 6 h, and then perform vacuum distillation to remove the solvent butanol and unreacted triethylamine to obtain the polymeric quaternary ammonium salt. Among them, the molar ratio of chlorine element to triethylamine in the polyepichlorohydrin diol is 1:1.1, and the mass of butanol is 60% of the sum of the masses of the polyepichlorohydrin diol and triethylamine.

[0092] Comparative Example 3

[0093] The difference between the high-efficiency compound quaternary ammonium salt reverse demulsifier of this comparative example and that of Example 1 lies only in that the molar ratio of ethylene glycol to epichlorohydrin in step (3) of the preparation method of the polymeric quaternary ammonium salt in the high-efficiency compound quaternary ammonium salt reverse demulsifier of this comparative example is 0.1:1.

[0094] Comparative Example 4

[0095] The difference between the high-efficiency compound quaternary ammonium salt reverse demulsifier of this comparative example and that of Example 1 lies only in that in step (3) of the preparation method of the polymer quaternary ammonium salt in the high-efficiency compound quaternary ammonium salt reverse demulsifier of this comparative example, the molar ratio of ethylene glycol to epichlorohydrin is 0.4:1.

[0096] Comparative Example 5

[0097] The difference between the high-efficiency compound quaternary ammonium salt reverse demulsifier of this comparative example and that of Example 1 lies only in that in step (7) of the preparation method of the polymer quaternary ammonium salt in the high-efficiency compound quaternary ammonium salt reverse demulsifier of this comparative example, the molar ratio of epichlorohydrin to polyepichlorohydrin bridged secondary amine compound is adjusted from 0.1:1 to 0.05:1.

[0098] Comparative Example 6

[0099] The difference between the high-efficiency compound quaternary ammonium salt reverse demulsifier of this comparative example and that of Example 1 lies only in that in step (7) of the preparation method of the polymer quaternary ammonium salt in the high-efficiency compound quaternary ammonium salt reverse demulsifier of this comparative example, the molar ratio of epichlorohydrin to polyepichlorohydrin bridged secondary amine compound is adjusted from 0.1:1 to 0.3:1.

[0100] Comparative Example 7

[0101] The difference between the high-efficiency compound quaternary ammonium salt reverse demulsifier of this comparative example and that of Example 1 lies only in that the preparation method of the polymer quaternary ammonium salt in the high-efficiency compound quaternary ammonium salt reverse demulsifier of this comparative example includes the following steps: Stir the polymer quaternary ammonium salt prepared in Comparative Example 1 and the polymer quaternary ammonium salt prepared in Comparative Example 2 evenly according to the mass ratio of 4:1 to obtain the polymer quaternary ammonium salt.

[0102] Comparative Example 8

[0103] The difference between the high-efficiency compound quaternary ammonium salt reverse demulsifier of this comparative example and that of Example 1 lies only in that the preparation method of the polymer quaternary ammonium salt in the high-efficiency compound quaternary ammonium salt reverse demulsifier of this comparative example includes the following steps: Add 70 g of (3-acrylamidopropyl) trimethyl ammonium chloride and 20 g of water to the reaction kettle, then drop 10 g of pentaethylenehexamine into the reaction kettle at room temperature and under stirring conditions, then stir and react at 80 °C for 12 h, remove the moisture by reduced pressure distillation, and obtain the high-efficiency compound quaternary ammonium salt reverse demulsifier after drying.

[0104] Comparative Example 9

[0105] The difference between the high-efficiency compounded quaternary ammonium salt reverse demulsifier of this comparative example and that of Example 1 lies only in that in the preparation method of the quaternary ammonium salt modified nano-titanium dioxide in the high-efficiency compounded quaternary ammonium salt reverse demulsifier of this comparative example, dimethyloctadecyl [3-(trimethoxysilyl)propyl] ammonium chloride is replaced by trimethyl [3-(trimethoxysilyl)propyl] ammonium chloride.

[0106] Comparative Example 10

[0107] The difference between the high-efficiency compounded quaternary ammonium salt reverse demulsifier of this comparative example and that of Example 1 lies only in that the dosage of the quaternary ammonium salt modified nano-titanium dioxide in the high-efficiency compounded quaternary ammonium salt reverse demulsifier of this comparative example is 0.

[0108] Comparative Example 11

[0109] The difference between the high-efficiency compounded quaternary ammonium salt reverse demulsifier of this comparative example and that of Example 1 lies only in that the dosage of the polymeric quaternary ammonium salt in the high-efficiency compounded quaternary ammonium salt reverse demulsifier of this comparative example is 0.

[0110] Effect Example

[0111] In order to investigate the comprehensive performance of the high-efficiency compounded quaternary ammonium salt reverse demulsifiers prepared in each example and comparative example, the simulated oily sewage was added into a conical flask, and after being kept standing at a constant temperature for 30 min at the experimental temperature (the experimental temperature is 30°C or 80°C), then the high-efficiency compounded quaternary ammonium salt reverse demulsifier (the dosage is 50 mg / L) was added into the conical flask, magnetically stirred for 3 min, and then kept standing for 45 min. The lower-layer clear liquid was taken, and according to the regulations in the standard SY / T 5329-1994 "Recommended Indexes and Analytical Methods for Injection Water Quality in Clastic Rock Reservoirs", the oil content concentration and suspended solid concentration of the clear liquid were tested. Then, according to the oil content concentration and suspended solid concentration of the simulated oily sewage, the oil removal rate and suspended solid removal rate during the demulsification process were calculated. The oil removal rate = (the oil content concentration of the simulated oily sewage - the oil content concentration of the clear liquid) / the oil content concentration of the simulated oily sewage, and the suspended solid removal rate = (the suspended solid concentration of the simulated oily sewage - the suspended solid concentration of the clear liquid) / the suspended solid concentration of the simulated oily sewage. Among them, the oil content concentration of the simulated oily sewage is 700 mg / L, and the suspended solid concentration is 175 mg / L.

[0112] The oil removal rate and suspended solid removal rate corresponding to the high-efficiency compounded quaternary ammonium salt reverse demulsifiers prepared in each example and comparative example are shown in Table 1.

[0113] Table 1 Oil removal rate and suspended solid removal rate corresponding to the high-efficiency compounded quaternary ammonium salt reverse demulsifiers prepared in each example and comparative example

[0114]

[0115] As can be seen from the test results in Table 1, when the addition amount of the high-efficiency compounded quaternary ammonium salt reverse demulsifier prepared by the present invention in the oily sewage is 50 mg / L, the oil removal rate and suspended solid removal rate in the sewage both exceed 89% at 80 °C, and both exceed 81% at 30 °C. Among them, the oil removal rate and suspended solid removal rate corresponding to the high-efficiency compounded quaternary ammonium salt reverse demulsifier prepared in Examples 1-3 both exceed 93% at 80 °C, and both exceed 90% at 30 °C, indicating that the high-efficiency compounded quaternary ammonium salt reverse demulsifier prepared by the present invention has good removal rates for both oil products and suspended solids in sewage at low and high temperatures. The above experimental results show that the high-efficiency compounded quaternary ammonium salt reverse demulsifier of the present invention is compounded by nano-level quaternary ammonium salt modified titanium dioxide and network polymer quaternary ammonium salt. The nano-level quaternary ammonium salt modified titanium dioxide has a high specific surface area and can form an integral body with the network polymer quaternary ammonium salt through intermolecular forces and hydrogen bonds, playing a nodal role and improving the spreading degree of the network polymer quaternary ammonium salt, so that the flexible network polymer quaternary ammonium salt with a longitudinal polyepichlorohydrin quaternary ammonium salt main chain and a transverse four-segment polyepichlorohydrin quaternary ammonium salt chain segment structure has a high distribution density and uniformity of quaternary ammonium salt at a lower dosage and a lower temperature. The transverse and longitudinal polyepichlorohydrin quaternary ammonium salt chain segments cooperate with each other to jointly play a demulsifying role, improve the demulsifying effect, and effectively remove oil products and suspended solids.

[0116] As can be seen from Example 1 and Examples 4-5, when the brominated hydrocarbon for the quaternization reaction of the tertiary amine in the preparation of the polymer quaternary ammonium salt is replaced with bromododecane with a longer carbon chain, the quaternary ammonium salt chain segment length of the transverse four arms of the prepared polymer quaternary ammonium salt will shield the lipophilic butyric acid esterified chain segment, affecting the lipophilicity of the longitudinal main chain polyepichlorohydrin quaternary ammonium salt chain segment of the demulsifier and resulting in a poor demulsifying effect. When the brominated hydrocarbon for the quaternization reaction of the tertiary amine is replaced with bromobutane with a shorter carbon chain, the hydrophobicity of the quaternary ammonium salt chain segment of the transverse four arms of the prepared polymer quaternary ammonium salt becomes poor, affecting the lipophilicity of the transverse four-arm polyepichlorohydrin quaternary ammonium salt chain segment of the demulsifier and resulting in a poor demulsifying effect. Therefore, in order to effectively improve the demulsifying effect at low and high temperatures, it is necessary to keep the fatty chain of the brominated hydrocarbon at an appropriate length.

[0117] As can be seen from Example 1, Comparative Example 1-2 and Comparative Example 7, when the longitudinal main chain polyepichlorohydrin quaternary ammonium salt demulsifier prepared in Comparative Example 1 and the polyepichlorohydrin quaternary ammonium salt chain segment prepared in Comparative Example 2 are simply compounded by physical mixing, due to the lack of chemical bond fixation and tension constraint, the two cannot form a regular network structure and will entangle and knot together in the wastewater, reducing the quaternary ammonium salt distribution uniformity and distribution range, resulting in a poor demulsifying effect, and the demulsifying effect after the two are mixed is worse than that of using either of them alone.

[0118] It can be seen from Example 1 and Comparative Examples 3-4 that when the molecular weight of the longitudinal main-chain polyepichlorohydrin quaternary ammonium salt segment is changed by adjusting the molar ratio of ethylene glycol and epichlorohydrin, when the molecular weight of the longitudinal main-chain polyepichlorohydrin quaternary ammonium salt segment is too large, it is easy to entangle and kink in wastewater, which is not conducive to the unfolding of the longitudinal main-chain quaternary ammonium salt segment, thereby affecting the demulsification effect; when the molecular weight of the longitudinal main-chain polyepichlorohydrin quaternary ammonium salt segment is too small, the transverse four-arm polyepichlorohydrin quaternary ammonium salt segment cannot be effectively unfolded, resulting in overlapping, entanglement and kinking, which is not conducive to the unfolding of the transverse four-arm polyepichlorohydrin quaternary ammonium salt segment, thereby affecting the demulsification effect. Therefore, in order to cooperate with the transverse four-arm polyepichlorohydrin quaternary ammonium salt segment, the molar ratio of ethylene glycol and epichlorohydrin when preparing the longitudinal main-chain polyepichlorohydrin quaternary ammonium salt segment needs to be controlled within a suitable range.

[0119] It can be seen from Example 1 and Comparative Examples 5-6 that when the molecular weight of the polyepichlorohydrin quaternary ammonium salt segment grafted on the transverse four arms is changed by adjusting the molar ratio of epichlorohydrin and polyepichlorohydrin bridged secondary amine compound, when the molecular weight of the polyepichlorohydrin quaternary ammonium salt segment grafted on the transverse four arms is too large, it will overlap, entangle and kink in wastewater, which is not conducive to the unfolding of the transverse four-arm polyepichlorohydrin quaternary ammonium salt segment, thereby affecting the demulsification effect; when the molecular weight of the polyepichlorohydrin quaternary ammonium salt segment grafted on the transverse four arms is too small, the overall quaternary ammonium salt density of the demulsifier decreases, resulting in a poor demulsification effect.

[0120] It can be seen from Example 1 and Comparative Example 8 that compared with the conventional hyperbranched polymer quaternary ammonium salt, the present invention has a better demulsification effect by preparing a polymer quaternary ammonium salt with a regular structure, especially the demulsification effect at low temperature.

[0121] It can be seen from Example 1 and Comparative Example 9 that when using nano-titanium dioxide modified with long fatty chains, its long fatty chains can better overlap on the network polymer quaternary ammonium salt matrix to form a stable complex structure and improve the synergistic effect of the two.

[0122] It can be seen from Example 1 and Comparative Examples 10-11 that when using quaternary ammonium salt modified nano-titanium dioxide or polymer quaternary ammonium salt alone, the demulsification effect of the reverse demulsifier becomes poor. This is because when using the network polymer quaternary ammonium salt and quaternary ammonium salt modified nano-titanium dioxide alone, a demulsifier with a regular network structure cannot be formed, resulting in a poor distribution density and uniformity of the quaternary ammonium salt groups and a poor demulsification effect.

Claims

1. A highly efficient composite quaternary ammonium salt reverse demulsifier, characterized in that: The invention is composed of a polymer quaternary ammonium salt and a quaternary ammonium salt-modified nano titanium dioxide, wherein the mass ratio of the polymer quaternary ammonium salt to the quaternary ammonium salt-modified nano titanium dioxide is 18-20:1; the quaternary ammonium salt-modified nano titanium dioxide is prepared by reacting nano titanium dioxide and dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride; The preparation method of the polymer quaternary ammonium salt is as follows: (1) reacting 2-hydroxy-1,3-propanediamine and bromopropane in a molar ratio of 1:2 to obtain a secondary amine compound; (2) reacting the secondary amino group in the secondary amine compound with di-tert-butyl dicarbonate to obtain an amine ester compound; (3) reacting the hydroxyl group in the amine ester compound with the terminal acyl chloride polyepichlorohydrin to obtain a polyepichlorohydrin bridged amine ester compound; the molar ratio of the amine ester compound to the terminal acyl chloride polyepichlorohydrin is 2:1, and the terminal acyl chloride polyepichlorohydrin is obtained by subjecting the product obtained by the reaction of polyepichlorohydrin diol and succinic anhydride to chlorination reaction; the polyepichlorohydrin diol is obtained by subjecting ethylene glycol and epichlorohydrin in a molar ratio of 0.2 to 0.3:1 to cationic ring-opening polymerization; (4) deprotecting the tert-butyloxycarbonyl group in the polyepichlorohydrin-bridged amine ester compound to obtain a polyepichlorohydrin-bridged secondary amine compound; (5) reacting the secondary amino group in the polyepichlorohydrin-bridged secondary amine compound with epichlorohydrin to obtain a polyepichlorohydrin-bridged four-arm chlorohydrin compound; then subjecting the polyepichlorohydrin-bridged four-arm chlorohydrin compound and epichlorohydrin to a cationic ring-opening polymerization to obtain a polyepichlorohydrin-bridged four-arm polyepichlorohydrin; in the cationic ring-opening polymerization, the molar ratio of epichlorohydrin to the polyepichlorohydrin-bridged secondary amine compound used to prepare the polyepichlorohydrin-bridged four-arm chlorohydrin compound is 0.1 to 0.2:1; (6) A tertiary amino group in the polyepichlorohydrin-bridged four-arm polyepichlorohydrin is subjected to a quaternization reaction with an alkyl bromide to obtain an ammonium bromide bridged product; and a chlorine atom in the ammonium bromide bridged product is subjected to a quaternization reaction with triethylamine to obtain a polymer quaternary ammonium salt; the alkyl bromide is one of dodecane bromide, undecane bromide, n-decane bromide, n-butane bromide, n-pentane bromide, n-hexane bromide, n-heptane bromide, n-octane bromide and n-nonane bromide.

2. The highly efficient composite quaternary ammonium salt reverse demulsifier according to claim 1, characterized in that: In step (1) of the method for preparing a polymer quaternary ammonium salt, sodium hydroxide is used as a catalyst when 2-hydroxy-1,3-propylenediamine and bromopropane react, and the molar ratio of 2-hydroxy-1,3-propylenediamine, bromopropane and sodium hydroxide is 1:2:2.3-2.5; the temperature of the reaction of 2-hydroxy-1,3-propylenediamine and bromopropane is 60-70°C, and the reaction time is 2-3 hours.

3. The highly efficient composite quaternary ammonium salt reverse demulsifier according to claim 1, characterized in that: In step (2) of the method for preparing the polymer quaternary ammonium salt, the molar ratio of di-tert-butyl dicarbonate to the secondary amine compound is 2:

1.

4. The highly efficient composite quaternary ammonium salt reverse demulsifier according to claim 1, characterized in that: In step (3) of the method for preparing a polymer quaternary ammonium salt, boron trifluoride etherate complex is used as a catalyst during the cationic ring-opening polymerization reaction, and the mass of the boron trifluoride etherate complex is 0.15-0.2% of the sum of the masses of ethylene glycol and epichlorohydrin; the temperature of the cationic ring-opening polymerization reaction is 0-5°C, and the time is 3-4 hours; the temperature of the reaction of polyepichlorohydrin diol and succinic anhydride is 50-60°C, and the time is 5-8 hours, and the molar ratio of polyepichlorohydrin diol to succinic anhydride is 1:2; and the acyl chloride reaction in step (3) is to mix the product obtained by the reaction of polyepichlorohydrin diol and succinic anhydride with dichlorothionyl in a mass ratio of 10:50-60, and then reflux for reaction for 24-30 hours.

5. The highly efficient composite quaternary ammonium salt reverse demulsifier according to claim 1, characterized in that: The method for deprotecting the tert-butyloxycarbonyl group in the polyepichlorohydrin bridged amine ester compound in step (4) of the method for preparing the polymer quaternary ammonium salt is as follows: adding a dioxane solution of the polyepichlorohydrin bridged amine ester compound to a dioxane solution of hydrogen chloride, mixing and reacting for 4 to 5 hours, then adding sodium hydroxide, and adjusting the pH of the reaction solution to 7.5 to 8; the concentration of the dioxane solution of hydrogen chloride is 2 mol / L, and the mass ratio of the dioxane solution of the polyepichlorohydrin bridged amine ester compound to the dioxane solution of hydrogen chloride is 1:2 to 2.

5.

6. The highly efficient composite quaternary ammonium salt reverse demulsifier according to claim 1, characterized in that: In the step (5) of the method for preparing a polymer quaternary ammonium salt, when preparing a polyepichlorohydrin-bridged four-arm chlorohydrin compound, the molar ratio of the polyepichlorohydrin-bridged secondary amine compound to epichlorohydrin is 1:4-4.1, the reaction temperature is 58-65° C., and the reaction time is 5-7 hours. In the cationic ring-opening polymerization reaction in step (5), boron trifluoride etherate complex is used as a catalyst, and the mass of the boron trifluoride etherate complex is 0.15-0.2% of the sum of the masses of the polyepichlorohydrin-bridged secondary amine compound and epichlorohydrin.

7. The high-efficiency composite quaternary ammonium salt reverse demulsifier according to claim 1, characterized in that: In step (6) of the method for preparing a polymer quaternary ammonium salt, when the tertiary amino group in the polyepichlorohydrin-bridged four-arm polyepichlorohydrin and the alkyl bromide are subjected to a quaternization reaction, the molar ratio of the polyepichlorohydrin-bridged four-arm polyepichlorohydrin and the alkyl bromide is 1:4.5-5, the reaction temperature is 85-90°C, and the reaction time is 6-8h; the molar ratio of the chlorine atom and triethylamine in the ammonium bromide bridging product is 1:1.1-1.3, and the temperature for the quaternization reaction of the chlorine atom in the ammonium bromide bridging product and the triethylamine is 85-90°C, and the reaction time is 6-8h.

8. The highly efficient composite quaternary ammonium salt reverse demulsifier according to any one of claims 1 to 7, characterized in that: The mass ratio of the nano titanium dioxide and dimethyl octadecyl [3- (trimethoxysilyl) propyl] ammonium chloride is 1:4-5, and the reaction temperature of the nano titanium dioxide and dimethyl octadecyl [3- (trimethoxysilyl) propyl] ammonium chloride is 70-80° C. and the reaction time is 28-30 hours.

9. The high-efficiency composite quaternary ammonium salt reverse demulsifier according to claim 8, characterized in that: The average particle size of the nano titanium dioxide is 25-40 nm.

10. A method for preparing a highly efficient composite quaternary ammonium salt reverse demulsifier as claimed in any one of claims 1 to 9, characterized in that: The following steps are involved: The polymer quaternary ammonium salt and the quaternary ammonium salt modified nano titanium dioxide are mixed evenly.

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