CN114957543A

CN114957543A - Reverse demulsifier and preparation method thereof

Info

Publication number: CN114957543A
Application number: CN202210386180.6A
Authority: CN
Inventors: 任小丽; 段明; 方申文; 张潇月; 王淇海
Original assignee: Southwest Petroleum University
Current assignee: Southwest Petroleum University
Priority date: 2022-07-01
Filing date: 2022-07-01
Publication date: 2022-08-30
Anticipated expiration: 2042-07-01
Also published as: CN114957543B

Abstract

The invention provides a reverse demulsifier and a preparation method thereof, and relates to the technical field of demulsifiers. The reverse demulsifier is prepared by the following steps: firstly, modifying purine by using 5-bromo-1-pentene, then carrying out emulsion polymerization on an unsaturated quaternary ammonium salt monomer and a modified purine monomer under the condition of adding an anionic emulsifier, and after the polymerization is finished, adding an acrylate monomer for further modification to finally obtain the reverse demulsifier. The reverse demulsifier prepared by the invention has the characteristics of high deoiling rate, small using amount and the like, and the application method is simple, does not need complex equipment and working procedures, and is suitable for industrial popularization.

Description

Reverse demulsifier and preparation method thereof

Technical Field

The invention belongs to the technical field of demulsifiers, and particularly relates to a reverse demulsifier and a preparation method thereof.

Background

At present, most oil fields in China enter the middle and later stages of water injection exploitation, the yield of produced liquid of the oil fields is increased, the water content of part of the produced liquid is as high as 80-90%, and the demulsification treatment of the produced liquid is also more and more difficult. The treatment of the oil field produced liquid is one of the important conditions for ensuring the normal exploitation of the oil field. Various reverse demulsifiers independently researched and developed in China are difficult to meet the treatment requirement of produced liquid, and the condition is that the oil content of lower-layer water after demulsification is high, and the cost and the difficulty of a sewage treatment system are increased.

Disclosure of Invention

In order to solve at least one problem, the invention provides a novel reverse demulsifier and a demulsifier prepared by the method, the method is simple, the raw materials are easy to obtain, and the reverse demulsifier has the characteristics of high deoiling rate, small using amount and the like.

The technical scheme of the invention is as follows: a method of preparing a reverse demulsifier comprising the steps of:

s1, purine modification: adding equimolar purine and potassium carbonate into a solvent, wherein 1-1.5 g of purine is added into every 10ml of solvent, reacting for 1h at 70-90 ℃, dropwise adding 5-bromo-1-pentene with equimolar amount with purine, reacting for 24h, cooling reaction liquid to room temperature, filtering and purifying to obtain modified purine, wherein the purine is one of guanine and adenine; the process mainly comprises the steps of reacting secondary amine in purine with alkyl halide, and grafting pentene capable of participating in subsequent reaction to a purine ring;

s2, synthesis of a reverse demulsifier: adding an unsaturated quaternary ammonium salt monomer and a modified purine monomer in a mass ratio of 4-8: 1 into water, deoxidizing, then adding an anionic emulsifier and hydrochloric acid, uniformly mixing, wherein the molar ratio of the hydrochloric acid to the modified purine monomer is 1:1, and then carrying out emulsion polymerization under the action of an initiator for 4-10 h, wherein the total mass concentration of the two monomers is not less than 45%; and after the polymerization is finished, cooling to 20-35 ℃, adding an acrylate monomer and alkali for neutralizing the hydrochloric acid, adding water to ensure that the total mass concentration of the reaction monomer is not less than 20%, and continuously reacting for 12-24 hours at 20-35 ℃ to obtain the purine derivative, wherein the molar ratio of the modified purine monomer to the acrylate monomer is 1: 0.3-1.2.

In S2, the phrase "base used for neutralizing the hydrochloric acid" means that the added base can completely neutralize the hydrochloric acid added in the previous step, and the base used in the process is usually an inorganic base such as sodium hydroxide, potassium hydroxide, sodium carbonate and the like.

In an embodiment of the present invention, in S1, the specific operations of filtering and purifying are as follows: and filtering the reacted product, collecting filtrate, adjusting the pH of the filtrate to 1-2, freezing for 12h at-4-0 ℃, filtering, putting the filtered solid phase into petroleum ether, adjusting the pH of the petroleum ether solution to be neutral, filtering again, drying the solid phase obtained after filtering again to obtain the target product, and purifying the modified purine through the process.

In one embodiment of the present invention, the unsaturated quaternary ammonium salt monomer is one of methacryloyloxyethyl trimethyl ammonium chloride and diallyl dimethyl ammonium chloride.

Preferably, the unsaturated quaternary ammonium salt monomer is methacryloyloxyethyl trimethyl ammonium chloride.

One embodiment of the present invention is that the structural formula of the acrylate monomer is: CH2 ═ CH-CO-O-R, where R is one of an alkyl group having a carbon chain length of not more than 4 or a hydroxyl group-containing alkyl group, such as methyl acrylate, ethyl acrylate, butyl acrylate, 2-hydroxyethyl acrylate, 4-hydroxybutyl acrylate, etc., but is not limited to these examples. Meanwhile, the reason that the length of the carbon chain of R is not more than 4 is limited because when the length of the carbon chain of R is more than 4, the finally prepared emulsion is unstable, and the emulsion breaking effect is poor due to the layering phenomenon.

Preferably, the acrylate monomer is 4-hydroxybutyl acrylate, and when the monomer is used, the effect is relatively better, because when the carbon chain length of R is not greater than 4, the longer the carbon chain length is, the better the final effect is, and meanwhile, after hydroxyl is introduced into acrylate, the viscosity of the whole system is increased, and the molecular weight is relatively increased.

One embodiment of the invention is that the anionic emulsifier is one of sodium dodecyl sulfate and sodium dodecyl benzene sulfonate, and the concentration of the anionic emulsifier is 1.5-2 g/L. As the anionic emulsifier, more anionic emulsifiers can be used in the present invention, but sodium lauryl sulfate and sodium dodecylbenzenesulfonate are preferred in view of cost and availability.

One embodiment of the invention is that the initiator is persulfate, and the addition amount of the initiator is 0.4-1.2% of the total mass of the two monomers; for the initiator, it is not limited to persulfate, but it is found through a large number of experiments by the inventors that the following advantages are obtained when persulfate is used as the initiator: the initiation rate is moderate while the temperature required for its initiation is relatively low. Therefore, in the present invention, persulfate is preferable as the initiator.

One embodiment of the present invention is that after the acrylate monomer is added in S2, the mixture is reacted at 25 ℃ for 12-24h, and the inventor tests that the product is obtained with the best effect when the temperature is 25 ℃.

The invention also aims to provide a reverse demulsifier, which is prepared by adopting any one of the methods. The reverse demulsifier has the characteristics of high deoiling rate, small using amount and the like, and the application method is simple without complex equipment and working procedures.

The invention has the beneficial effects that:

1. the reverse demulsifier has the advantages of high deoiling rate, small using amount, high oil-water separation speed and easy separation, ensures that produced water is demulsified and destabilized, accelerates the oil-water separation speed, and is applied to the field of treatment of oil-containing sewage in oil exploitation.

2. The produced water treatment process is simple, only a certain amount of the product of the invention needs to be added into the produced water, the product is fully stirred to quickly generate insoluble flocs, and the insoluble flocs are settled, separated and filtered without complex equipment and procedures.

3. The raw materials used in the invention are easy to obtain, and the synthesis process is simple.

Drawings

FIG. 1 is an infrared spectrum of modified adenine in example 1;

FIG. 2 is a nuclear magnetic hydrogen spectrum of modified adenine in example 1;

FIG. 3 is an infrared spectrum of the reverse demulsifier 1 from example 1.

Detailed Description

In order to make the technical solutions and technical advantages of the present invention clearer, the following will clearly and completely describe the technical solutions in the implementation process of the present invention with reference to the embodiments and the accompanying drawings.

The experimental procedures used in the following examples are all conventional procedures unless otherwise specified.

Materials, reagents and the like used in the following examples are commercially available unless otherwise specified.

In the following examples, the oil field produced water is from Bohai sea oil field, the initial turbidity value is 475NTU, and the oil content is 1560 mg/L.

In the following examples, the hydrochloric acid used was 37% strength hydrochloric acid.

In the following examples, methacryloyloxyethyl trimethylammonium chloride was used as an aqueous solution thereof, and the effective content was 80%.

In the following examples, acryloyloxyethyltrimethyl ammonium chloride was used as an aqueous solution thereof, and the content of the active ingredient was 80%.

In the following examples, diallyldimethylammonium chloride was used as an aqueous solution thereof, and the effective content was 65%.

The formula 1 shows an acrylate monomer, wherein an R group is one of linear alkyl and linear alkyl containing hydroxyl, and the number of carbon chains of the linear alkyl is less than or equal to 4;

CH ₂ is CH-CO-O-R formula 1

Example 1

And (3) modified synthesis of adenine: weighing 10g adenine and 10.23g K ₂ CO ₃ Adding into a three-neck flask, adding 100ml N-N dimethylformamide, reacting in 80 deg.C constant temperature water bath for 1 hr, and dropping under constant pressure11.03g of 5-bromo-1-pentene is slowly dropped into the liquid funnel, and the reaction is carried out for 28 hours to obtain a light yellow liquid. Cooling the reaction liquid to room temperature, carrying out suction filtration, collecting filtrate, dropwise adding HCl to adjust the pH value to 1-2, and gradually separating out white solid. Freezing at 0 ℃ for 12h, performing suction filtration again, collecting the solid in a beaker filled with 50ml of petroleum ether, dropwise adding ammonia water to adjust the pH of the solution to 7, filtering again to obtain a solid, and performing vacuum drying at 60 ℃ for 12h to obtain the modified adenine. The specific reaction process of the process is as follows:

and (3) synthesizing a reverse demulsifier: taking 26g of methacryloyloxyethyl trimethyl ammonium chloride aqueous solution, adding 4.16g of modified adenine, 17.75g of deionized water, 0.05g of sodium dodecyl sulfate and 2.01g of hydrochloric acid, after the hydrochloric acid is completely dissolved in the system, opening a heating switch, keeping the temperature at 60 ℃, introducing nitrogen to remove oxygen for 20min, adding 0.01g of ammonium persulfate, initiating polymerization for 8h, cooling to 25 ℃, adding 1.75g of methyl acrylate, 0.816g of sodium hydroxide and 84.88g of deionized water, and continuously stirring and reacting for 12h to obtain F-1. The reaction of this procedure is specifically shown below:

example 2

The present embodiment is different from embodiment 1 in that: in the synthesis process of the reverse demulsifier, 26g of methacryloyloxyethyl trimethyl ammonium chloride aqueous solution is replaced by 32g of diallyl dimethyl ammonium chloride aqueous solution, 17.75g of deionized water is replaced by 11.75g of deionized water, and the rest steps are the same, so that F-2 is finally prepared.

Example 3

The present embodiment is different from embodiment 1 in that: in the synthesis process of the reverse-phase demulsifier, 1.75g of methyl acrylate is replaced by 2.04g of ethyl acrylate, 84.88g of deionized water is replaced by 84.31g of deionized water, and the rest steps are the same, so that F-3 is finally prepared.

Example 4

The present embodiment is different from embodiment 1 in that: in the synthesis process of the reverse demulsifier, 1.75g of methyl acrylate is replaced by 2.61g of butyl acrylate, 84.88g of deionized water is replaced by 87.16g of deionized water, and the rest steps are the same, so that F-4 is finally prepared.

Example 5

The present embodiment is different from embodiment 1 in that: in the synthesis process of the reverse-phase demulsifier, 1.75g of methyl acrylate is replaced by 2.37g of acrylic acid-2-hydroxyethyl ester, 84.88g of deionized water is replaced by 85.96g of deionized water, and the rest steps are the same, so that F-5 is finally prepared.

Example 6

The present embodiment is different from embodiment 1 in that: in the synthesis process of the reverse-phase demulsifier, 1.75g of methyl acrylate is replaced by 2.92g of 4-hydroxybutyl acrylate, 84.88g of deionized water is replaced by 88.72g of deionized water, and the rest steps are the same, so that F-6 is finally prepared.

Example 7

The present embodiment is different from embodiment 1 in that: f-7 was finally prepared by replacing 17.7g of deionized water with 23.30g and the remaining steps were the same.

Example 8

Synthesis of modified guanine 10g of guanine and 9.14g K g of guanine were weighed ₂ CO ₃ Adding the mixture into a three-neck flask, adding 100ml of N-N dimethylformamide, placing the mixture in a constant-temperature water bath at 80 ℃ for reaction for 1h, slowly dropwise adding 9.88g of 5-bromo-1-pentene by using a constant-pressure dropping funnel, and reacting for 48h to obtain a light yellow liquid. And cooling the reaction solution to room temperature, carrying out suction filtration, collecting filtrate, dropwise adding HCl to adjust the pH value to 1-2, and gradually separating out white solid. Freezing at 0 ℃ for 12h, performing suction filtration again, collecting the solid in a beaker filled with 50ml of petroleum ether, dropwise adding ammonia water to adjust the pH of the solution to 7, performing filtration again to obtain a solid, and performing vacuum drying at 60 ℃ for 12h to obtain the modified guanine.

And (2) synthesizing a reverse demulsifier, namely taking 26g of methacryloyloxyethyl trimethyl ammonium chloride aqueous solution, adding 4.16g of modified guanine, 17.84g of deionized water, 0.05g of sodium dodecyl sulfate and 1.87g of hydrochloric acid, after the hydrochloric acid is completely dissolved in the system, opening a heating switch, keeping the temperature at 60 ℃, introducing nitrogen to remove oxygen for 20min, adding 0.01g of ammonium persulfate, initiating polymerization for 8h, cooling to 25 ℃, adding 2.72g of 4-hydroxybutyl acrylate, 0.76g of sodium hydroxide and 87.91g of deionized water, and continuously stirring and reacting for 12h to obtain F-8.

Example 9

This embodiment is different from embodiment 6 in that: the same procedure was followed except that 2.92g of 4-hydroxybutyl acrylate was replaced with 1.75g of 4-hydroxybutyl acrylate, 88.72g of deionized water was replaced with 82.36g of deionized water, and F-9 was finally obtained.

Example 10

This embodiment is different from embodiment 6 in that: the same procedure was followed except that 2.92g of 4-hydroxybutyl acrylate was replaced with 3.50g of 4-hydroxybutyl acrylate, and 88.72g of deionized water was replaced with 91.61g of deionized water, to give F-10.

Example 11

This embodiment is different from embodiment 6 in that: the same procedure was followed except that 0.05g of sodium dodecylsulfate was replaced with 0.05g of sodium dodecylbenzenesulfonate, to finally obtain F-11.

Comparative example 1

This embodiment is different from embodiment 6 in that: and replacing 0.05g of sodium dodecyl sulfate with 0.05g of Tween 80, and carrying out the same steps to finally obtain D-1.

Comparative example 2

This embodiment is different from embodiment 6 in that: and replacing 0.05g of sodium dodecyl sulfate with 0.05g of dodecyl trimethyl ammonium bromide, and carrying out the same steps to finally obtain D-2.

Comparative example 3

This comparative example differs from example 1 in that: in the synthesis process of the reverse demulsifier, 1.75g of methyl acrylate is replaced by 2.89g of amyl acrylate, 84.88g of deionized water is replaced by 88.56g of deionized water, and the rest steps are the same, so that D-3 is finally prepared.

Comparative example 4

This comparative example differs from example 1 in that: in the process of synthesizing the reverse demulsifier, the same steps are carried out by replacing 26g of the aqueous solution of methacryloyloxyethyl trimethyl ammonium chloride with 26g of the aqueous solution of acryloyloxyethyl trimethyl ammonium chloride, and D-4 is finally prepared.

Comparative example 5

This comparative example differs from example 1 in that: in the synthesis process of the reverse demulsifier, the steps of replacing 17.70g of deionized water with 39.14g of deionized water are the same, and D-5 is finally prepared.

Comparative example 6

This comparative example differs from example 1 in that: in the synthesis process of the reverse-phase demulsifier, the steps are the same except that 88.34g of deionized water is replaced by 127.38g of deionized water, and D-6 is finally prepared.

In particular, with respect to the reverse demulsifiers prepared in the above examples and comparative examples, the inventors found that, when the emulsifier types were changed, as in example 6, example 10, comparative example 1, and comparative example 2, it was found that each of the reverse demulsifiers had different results, and the stability and the residue condition of the emulsion synthesized with three different emulsifiers were observed when it was left to stand at 48, as shown in the following table.

	Kind of emulsifier	Evaluation of stability and residue
			S-6	Anion(s)	The emulsion has no residue and good stability
S-10	Anion(s)	The emulsion has small amount of polymer residue and good stability
			D-1	Non-ionic	Emulsion residue is much, stability is poor, and precipitation is generated after 48 hours
D-2	Cation(s)	Lumpy and fail to form emulsion

To further illustrate the effect of the reverse demulsifiers prepared in the above examples, the reverse demulsifiers prepared in examples 1-11 and comparative examples 1-5 above were tested as follows.

1. Spectrum measurement

The modified purine of example 1 was taken and tested as follows:

infrared analysis: 3228cm, as shown in FIG. 1 ^-1 And 3113cm ^-1 The strong peak of (A) belongs to N-H stretching vibration of primary amine; 2931cm ^-1 The strong peak is the stretching vibration peak of last methyl C-H bond of purine ring; 1677cm ^-1 The peak belongs to the stretching vibration of C ═ N double bond on purine ring; 1602cm ^-1 Out-of-plane bending vibration of primary amine N-H on purine ring; 660cm ^-1 Belonging to the out-of-plane bending vibration of N-H on the pyrimidine ring. 1477cm ^-1 An out-of-plane bending vibration peak of C-H of methylene appears; 999cm ^-1 、910cm ^-1 Out-of-plane bending vibrations of olefinic hydrogens occur, which belong to the characteristic absorption peaks of terminal olefins. In conclusion, it was demonstrated that adenine successfully reacts with 5-bromo-1-pentene and the desired product is obtained.

Nuclear magnetic analysis: as shown in fig. 2, the peak at δ ═ 8.30ppm was assigned to adenine six-membered ring-N ═ CH-N-, and the peak at δ ═ 8.23ppm was assigned to-N ═ CH-N on adenine five-membered ring, and the peak at δ ═ 5.68ppm was assigned to-CH ═ CH on carbon atom having side-chain pentenyl group bonded to double bond ₂ The peak at δ 4.87ppm is assigned to pentenyl-CH ═ CH ₂ Peak assignment at δ of 4.21ppm-N-CH at a carbon atom linked to an N atom of a purine Ring ₂ -CH ₂ The peak at 1.96ppm is assigned to-CH on the side-chain pentenyl group ₂ -CH ₂ The peak at-CH-, δ -1.89 ppm is assigned to-CH on pentenyl ₂ -CH ₂ -CH ₂ -. By combining the above, adenine successfully reacts with 5-bromo-1-pentene to obtain the target product.

Taking the reverse demulsifier 1, and carrying out infrared scanning test on the reverse demulsifier, wherein the scanning result is shown in figure 3: at 3411cm ^-1 The peak at (a) is due to the characteristic stretching vibration of-N-H. At 1726cm ^-1 The peak of (A) is caused by the absorption of C ═ O stretching vibration in methyl acrylate and methacryloyloxyethyltrimethylammonium chloride, 1635cm ^-1 The peak of (a) is due to stretching vibration of C ═ N on the adenine ring. -CH ₂ and-CH ₃ Respectively appear at 1470cm ^-1 And 1402cm ^-1 To (3). 1153cm ^-1 The peak at (a) corresponds to the stretching vibration peak of C-O in methyl acrylate. 950cm ^-1 Is the out-of-plane stretching vibration peak of ═ C — H on the purine ring. In combination with the above, the reverse demulsifier has been successfully prepared.

2. Turbidity removal and oil removal test

Placing 50mL of Bohai certain oil field produced liquid in a water removal bottle, and preheating in a 75 ℃ constant-temperature water bath for 10 min; and then taking out the preheated dewatering bottle filled with the produced liquid, adding 50mg/L synthetic reverse demulsifier emulsion into the bottle, manually and violently shaking up and down for 100 minutes, continuously placing the dewatering bottle added with the medicament into a 75 ℃ water bath kettle, heating for 10 minutes at constant temperature, taking out the dewatering bottle, and standing for 5 minutes. Transferring and taking a lower-layer water sample of the descaled bottle after standing, measuring the turbidity value of the lower-layer water sample by a turbidity meter, and then calculating the turbidity removal rate; the OIL content was measured and the OIL removal rate was calculated using a JC-OIL-6 type infrared spectrophotometric OIL meter. The results are shown in the following table.

The final measurement results are shown in table 1.

TABLE 1 measurement of turbidity removal Rate

1. Compared with the turbidity reduction results and the oil removal effect of F-1, F-2 and D-4 synthesized under different cationic monomers, the demulsification effect of the reverse demulsifier synthesized by using methacryloyloxyethyl trimethyl ammonium chloride as a cationic monomer is the best compared with diallyl dimethyl ammonium chloride; when the acryloyloxyethyl trimethyl ammonium chloride is used as a cationic monomer, the synthesized reverse demulsifier has poorer effect and is difficult to meet the actual use requirement.

2. Compared with F-1, the reverse demulsifier synthesized by changing the types of the acrylic ester to obtain F-3, F-4, F-5 and F-6 has the best demulsification effect when the acrylic ester is 2-hydroxybutyl acrylate, because the cationic groups in the demulsifier can absorb the bridging action and the ester groups can absorb the oil-water interface after the agent is added into sewage, so that the strength of the oil-water interface membrane is reduced, and the oil-water separation is realized. Along with the growth of the carbon chain of the acrylic ester, the hydrophobicity is increased, the hydrophobic substance is easier to interact with oil drops, the demulsification effect is enhanced, the oil drops are favorable to coalescence and floating, and therefore the demulsification effect of the butyl acrylate is better than that of the ethyl acrylate and the methyl acrylate. Meanwhile, after hydroxyl is introduced into the acrylate, the viscosity of the product is increased, the molecular weight is increased, and therefore the demulsification effect of the 4-hydroxybutyl acrylate is best.

However, the carbon chain of the acrylate cannot be too long, see D-3, when the number of carbon atoms in the main chain is greater than 4, a stable emulsion cannot be formed, a layering phenomenon occurs, and finally, the demulsification effect is poor, so that the actual requirements are difficult to meet.

3. The modified purine was changed in type from F-6 to obtain F-8, in which the modified purine was modified guanine. The effect of the reverse demulsifier synthesized when the modified guanine is used as a primary amine monomer is lower than that of adenine.

4. Compared with F-6, the demulsifying effect is poor because the molar ratio of the modified purine to the acrylic ester is changed to obtain F-9 and F-10, and when the molar ratio of the modified purine to the 2-hydroxybutyl acrylate is too high, the 2-hydroxybutyl acrylate cannot completely react. When the molar ratio is too low, the grafting ratio is low, resulting in a low demulsifier effect.

5. Compared with F-6, the anionic emulsifier used in the synthesis process is changed into the nonionic emulsifier and the cationic emulsifier to obtain D-1 and D-2, and the results of comparing the three emulsifiers of nonionic, anionic and cationic types show that the anionic emulsifier has less residue in the synthesis of the emulsion and good emulsion stability; the non-ionic emulsifier synthesized emulsion has the similar effect with the reverse demulsifier prepared by the anionic emulsifier under certain conditions, but has the defects of more residues, poor emulsion stability, difficult storage due to long-term deposit generation and unsuitability for industrial application; the cationic emulsifier is integrally agglomerated in the process of synthesizing the emulsion, so that the emulsion cannot be formed, and meanwhile, the emulsion breaking effect is not achieved; and when the emulsifier is replaced by sodium dodecyl benzene sulfonate by combining with F-11, only a small amount of polymer residues exist in the emulsion, and the demulsification effect is better. In summary, anionic emulsifiers should be selected for the polymerization system.

6. Compared with F-1, the concentration of the monomer polymerized by methacryloyloxyethyl trimethyl ammonium chloride and modified adenine is reduced from 50% to 45%, 40% of the monomer is respectively used for obtaining a reverse demulsifier F-7 and a reverse demulsifier D-5, and when the concentration of the monomer and the concentration of the demulsifier are lower than 45%, the turbidity reduction rate and the oil removal rate are greatly reduced, so that the concentration of the monomer and the concentration of the demulsifier are not lower than 45% during polymerization; after adding methyl acrylate, the system concentration is reduced from 20% to 15% to obtain the reverse demulsifier D-6, the demulsification performance of which is too low. In summary, the total mass concentration of the quaternary ammonium salt monomer and the modified purine monomer is not less than 45%, and after the polymerization is completed, the acrylate monomer is added and water is added to make the total mass concentration of the reaction monomer not less than 20%.

Although the present invention has been described with reference to the preferred embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the present invention.

Claims

1. A method of preparing a reverse demulsifier comprising the steps of:

s1, purine modification: adding equimolar purine and potassium carbonate into a solvent, wherein 1-1.5 g of purine is added into every 10ml of solvent, reacting for 1h at 70-90 ℃, dropwise adding 5-bromo-1-pentene with equimolar amount with purine, reacting for 24h, cooling reaction liquid to room temperature, filtering and purifying to obtain modified purine, wherein the purine is one of guanine and adenine;

2. The method of claim 1, wherein in S1, the specific operations of filtering and purifying are as follows: and filtering the product after reaction, collecting filtrate, adjusting the pH of the filtrate to 1-2, freezing for 12h at-4-0 ℃, filtering, putting the filtered solid phase into petroleum ether, adjusting the pH of the petroleum ether solution to be neutral, filtering again, and drying the solid phase obtained after filtering again to obtain the target product.

3. The method of claim 1, wherein the unsaturated quaternary ammonium salt monomer is one of methacryloyloxyethyl trimethyl ammonium chloride and diallyl dimethyl ammonium chloride.

4. The method of claim 3, wherein the unsaturated quaternary ammonium salt monomer is methacryloyloxyethyl trimethyl ammonium chloride.

5. The method of claim 1, wherein the acrylate monomer has the formula: CH (CH) ₂ The compound is CH-CO-O-R, wherein R is one of alkyl with a carbon chain length not more than 4 or hydroxyl-containing alkyl.

6. The method of claim 5, wherein the acrylate monomer is 4-hydroxybutyl acrylate.

7. The method according to claim 1, wherein the anionic emulsifier is one of sodium dodecyl sulfate and sodium dodecyl benzene sulfonate, and the concentration of the anionic emulsifier is 1.5-2 g/L.

8. The method according to claim 1, wherein the initiator is persulfate, and the amount of the initiator added is 0.4 to 1.2% of the total mass of the two monomers.

9. The method as claimed in claim 1, wherein the reaction is carried out at 25 ℃ for 12-24h after the acrylate monomer is added into S2.

10. A reverse demulsifier prepared by the method of any one of claims 1-9.