A method for preparing a scale inhibitor

Abstract

The present invention belongs to the technical field of scale inhibition, and specifically relates to a method for preparing a scale inhibitor. The present invention compounds a modified hyperbranched polymer with an AA-CA-LCA copolymer, and introduces components such as a corrosion inhibitor and a surfactant, so that the prepared scale inhibitor has good scale inhibition and corrosion inhibition effects on calcium carbonate, calcium sulfate, and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of scale inhibition, and in particular relates to a method for preparing a scale inhibitor. Background Art

[0002] In recent years, as the quality of crude oil has become heavier and worse, the scaling problem of oil processing equipment and pipelines has become increasingly prominent. Around the scaling problem of oil processing equipment and pipelines, researchers have proposed a series of measures such as coating the surface of equipment and pipelines with a layer of chemicals to passivate the metal surface to reduce scaling and optimize operating conditions; however, these methods have certain limitations and have failed to fundamentally inhibit the generation of scaling.

[0003] Scale inhibitor is an auxiliary agent used in the oil extraction, processing and pipeline transportation industries. It is mainly divided into natural scale inhibitors, copolymer scale inhibitors, phosphorus-based scale inhibitors, green scale inhibitors, nano-scale inhibitors, etc., which effectively solve the problem of scaling of oil processing equipment and pipelines.

[0004] Zhang Erchi et al. (Zhang Erchi, Synthesis and antiscaling performance of green and environmentally friendly polyaspartic acid scale inhibitor, Industrial Water Treatment, 2012) synthesized polyaspartic acid using maleic anhydride and ammonia water by thermal polycondensation, and further used L-aspartic acid to ring-open the polymer to prepare a polyaspartic acid scale inhibitor. 2+ When the mass concentration is 240 mg / L and the scale inhibitor dosage is 5 mg / L, the scale inhibition rate of polyaspartic acid reaches 72%; this type of scale inhibitor has good biodegradability and is suitable for industrial circulating cooling water and oilfield reinjection water with low mineralization, but the scale inhibition rate of this type of scale inhibitor is low, and the scale inhibition rate after modification is only 87%, and its scale inhibition effect is not ideal. Summary of the invention

[0005] The existing scale inhibitors have low scale inhibition efficiency. In order to solve this problem, the present invention provides a method for preparing a scale inhibitor.

[0006] In order to achieve the purpose of the present invention, the present invention adopts the following technical solutions:

[0007] The present invention provides a method for preparing a scale inhibitor, comprising the following steps:

[0008] S1: Under nitrogen protection, acrylic acid, citric acid, sulfoalanine and water are mixed evenly, and an aqueous solution of ammonium persulfate is added dropwise, and the temperature is raised for reaction; the mixture is cooled to room temperature, the pH is adjusted to 6.5-7, acetone is added and mixed evenly, and the mixture is filtered and dried to obtain an AA-CA-LCA copolymer;

[0009] S2.1: Under nitrogen protection, sorbitol, 2-aminoadipic acid and p-toluenesulfonic acid are mixed evenly, heated to react, and then acetone is added to mix evenly, filtered, and dried to obtain a hyperbranched polymer;

[0010] S2.2: Mix hydroxyethylidene diphosphonic acid, catalyst and N,N-dimethylformamide evenly, add the hyperbranched polymer solution dropwise, heat to react, add acetone and mix evenly, filter and dry to obtain a modified hyperbranched polymer;

[0011] S3: Evenly mix the AA-CA-LCA copolymer, the modified hyperbranched polymer, the corrosion inhibitor, the surfactant and water to obtain a high-efficiency scale inhibitor.

[0012] Preferably, in step S1, the molar ratio of acrylic acid, citric acid and cysteic acid is (1-2):(2-3):1.

[0013] By adopting the above technical solution, the ratio of three monomers, acrylic acid, citric acid and sulfoalanine, is optimized and adjusted to achieve the best scale inhibition efficiency.

[0014] Preferably, in step S1, the amount of ammonium persulfate used is 3%-5% of the total mass of the acrylic acid, citric acid and cysteic acid.

[0015] Preferably, in step S1, the reaction temperature is 75-85° C., and the reaction time is 3-6 h.

[0016] By adopting the above technical solution, within the temperature and time range, the molecular weight of the AA-CA-LCA copolymer is moderate, and the occurrence of side reactions such as branched chain cross-linking is avoided.

[0017] Preferably, in step S2.1, the molar ratio of sorbitol to 2-aminoadipic acid is 1:(2.5-5).

[0018] By adopting the above technical scheme, within the molar ratio range, there are more active sites and the formation of hyperbranched polymers is more complete; if the amount of 2-aminoadipic acid is too small, it may cause the reaction to form a linear polymer, making it difficult to form a rich branched structure; if the amount of 2-aminoadipic acid is too large, it may cause some groups to over-react with the branched structure that has been formed, affecting the structure of the hyperbranched polymer.

[0019] Preferably, in step S2.1, the amount of p-toluenesulfonic acid used is 0.8%-2.2% of the total mass of sorbitol and 2-aminoadipic acid.

[0020] By adopting the above technical solution, p-toluenesulfonic acid at this dosage can make the hydroxyl group of sorbitol more easily protonated, thereby enhancing its electrophilicity and making the reaction easier to proceed.

[0021] Preferably, in step S2.1, the temperature-raising reaction is specifically: heating to 115-130° C. for reaction for 1-2 hours, and then continuing to heat to 140-150° C. for reaction for 4-6 hours.

[0022] By adopting the above technical solution, the two-stage temperature-raising reaction makes the reaction more complete and reduces the generation of side reactions.

[0023] Preferably, in step S2.2, the mass ratio of hydroxyethylidene diphosphonic acid to the hyperbranched polymer is (1-3):1.

[0024] By adopting the above technical solution, an appropriate amount of phosphonic acid groups can be introduced into the hyperbranched polymer within the ratio range to enhance its adsorption capacity for metal ions.

[0025] Preferably, in step S2.2, the catalyst is 4-dimethylaminopyridine and 1-ethyl-(3-dimethylaminopropyl)carbodiimide in a molar ratio of (1-2):1; the amount of the catalyst is 5%-10% of the total mass of the hyperbranched polymer and hydroxyethylidene diphosphonic acid.

[0026] Preferably, in step S2.2, the hyperbranched polymer solution is composed of the hyperbranched polymer and N,N-dimethylformamide in a ratio of 1 g: 30-50 mL.

[0027] Preferably, in step S2.2, the reaction temperature is 60-70° C., and the reaction time is 8-10 h.

[0028] Preferably, in step S3, the amounts of AA-CA-LCA copolymer, modified hyperbranched polymer, corrosion inhibitor, surfactant and water are calculated by weight and are composed of:

[0029] 35-40 parts of AA-CA-LCA copolymer, 15-25 parts of modified hyperbranched polymer, 0.5-3 parts of corrosion inhibitor, 7-10 parts of surfactant and 20-30 parts of water.

[0030] Preferably, in step S3, the mixing temperature is 30-50° C., and the mixing time is 0.5-2 h.

[0031] In summary, the beneficial effects of the present invention are:

[0032] (1) The modified hyperbranched polymer prepared by the present invention has a three-dimensional structure, contains ester bonds, hydroxyl groups, carboxyl groups, phosphonic acid groups and other groups, and can chelate with metal ions in water to stabilize the metal ions inside the molecules, making it difficult for them to form scale crystals; at the same time, the branched structure has a large specific surface area and can be adsorbed on the crystal surface, which is conducive to dispersion;

[0033] (2) The AA-CA-LCA copolymer prepared by the present invention contains amide groups, carboxyl groups and the like, which can cause the lattice of scale crystals to be distorted and deformed through lattice distortion, thereby destroying the normal growth of scale and preventing the formation and deposition of scale; the introduced sulfonic acid groups have good water solubility and can prevent the formation of gelation between hydroxyl groups and metal ions; the chelation between sulfonic acid groups and metal ions is relatively stable and is suitable for different environments;

[0034] (3) The present invention compounds the modified hyperbranched polymer with the AA-CA-LCA copolymer, and introduces components such as corrosion inhibitors and surfactants. The obtained scale inhibitor has good scale and corrosion inhibition effects on calcium carbonate, calcium sulfate, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is the infrared spectrum of the modified hyperbranched polymer prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0036] The technical solution of the present invention is explained in detail below with reference to several representative embodiments of the present invention.

[0037] The experimental methods used in the following examples are conventional methods unless otherwise specified. The materials, reagents, etc. used in the following examples are all commercially available unless otherwise specified.

[0038] The corrosion inhibitors used in the following examples and comparative examples are all benzoic acid thiourea imidazoline, and the surfactants used are all nonylphenol polyoxyethylene ether.

[0039] Example 1

[0040] The preparation method of a scale inhibitor in this embodiment comprises the following specific steps:

[0041] S1.1: Add 3.17 g of ammonium persulfate to 15 mL of water and stir for 15 min to obtain an ammonium persulfate aqueous solution;

[0042] S1.2: Under nitrogen protection, 14.41 g acrylic acid, 48.03 g citric acid, 16.92 g cysteic acid and 100 mL water were added to a four-necked flask, heated to 60 °C and stirred for 1 h, and then slowly added with aqueous ammonium persulfate solution, and the temperature was continued to rise to 80 °C for reaction for 5 h; cooled to room temperature, the pH was adjusted to 7 with 35% aqueous sodium hydroxide solution, and then acetone was added and stirred for 15 min, filtered, and vacuum dried at 50 °C for 24 h to obtain AA-CA-LCA copolymer;

[0043] S2.1: Under nitrogen protection, 3.64 g sorbitol, 12.9 g 2-aminoadipic acid and 0.13 g p-toluenesulfonic acid were added to a four-necked flask, heated to 80°C and stirred for 1 h, then heated to 120°C for reaction for 2 h, then heated to 140°C for reaction for 6 h, then acetone was added and stirred for 0.5 h, filtered, and vacuum dried at 60°C for 24 h to obtain a hyperbranched polymer;

[0044] S2.2: 9 g of hydroxyethylidene diphosphonic acid, 0.45 g of 4-dimethylaminopyridine, 0.9 g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide and 50 mL of N,N-dimethylformamide were mixed evenly, and the hyperbranched polymer solution was added dropwise. The temperature was raised to 70°C for reaction for 10 h, and acetone was added and stirred for 0.5 h. The mixture was transferred to ether and stirred, precipitated, filtered, and vacuum dried at 60°C for 36 h to obtain a modified hyperbranched polymer. The hyperbranched polymer solution was prepared by stirring 4.5 g of the hyperbranched polymer with 180 mL of N,N-dimethylformamide for 20 min. The infrared spectrum of the modified hyperbranched polymer is shown in Figure 1 ;

[0045] S3: 37 g of AA-CA-LCA copolymer, 20 g of modified hyperbranched polymer, 2 g of corrosion inhibitor, 7 g of surfactant and 20 g of water were stirred at 40° C. for 1 h to obtain a high-efficiency scale inhibitor.

[0046] Example 2

[0047] The preparation method of a scale inhibitor in this embodiment comprises the following specific steps:

[0048] S1.1: Add 3.12 g of ammonium persulfate to 15 mL of water and stir for 15 min to obtain an ammonium persulfate aqueous solution;

[0049] S1.2: Under nitrogen protection, add 7.21g acrylic acid, 38.43g citric acid, 16.92g sulfoalanine and 100mL water into a four-necked flask, heat to 60℃ and stir for 1h, slowly add ammonium persulfate aqueous solution, continue to heat to 80℃ and react for 5h; cool to room temperature, adjust pH to 7 with 35% sodium hydroxide aqueous solution, add acetone and stir for 15min, filter, and vacuum dry at 50℃ for 24h to obtain AA-CA-LCA copolymer;

[0050] S2.1: Under nitrogen protection, 3.64 g sorbitol, 12.9 g 2-aminoadipic acid and 0.13 g p-toluenesulfonic acid were added to a four-necked flask, heated to 80°C and stirred for 1 h, then heated to 120°C for reaction for 2 h, then heated to 140°C for reaction for 6 h, then acetone was added and stirred for 0.5 h, filtered, and vacuum dried at 60°C for 24 h to obtain a hyperbranched polymer;

[0051] S2.2: 4.5 g of hydroxyethylidene diphosphonic acid, 0.45 g of 4-dimethylaminopyridine, 0.45 g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide and 50 mL of N,N-dimethylformamide were mixed evenly, and the hyperbranched polymer solution was added dropwise, and the temperature was raised to 70°C for reaction for 10 h, and then acetone was added and stirred for 0.5 h, and the mixture was transferred to ether and stirred, precipitated, filtered, and vacuum dried at 60°C for 36 h to obtain a modified hyperbranched polymer; the hyperbranched polymer solution was prepared by stirring 4.5 g of the hyperbranched polymer with 180 mL of N,N-dimethylformamide for 20 min;

[0052] S3: 35 g of AA-CA-LCA copolymer, 25 g of modified hyperbranched polymer, 1.5 g of corrosion inhibitor, 10 g of surfactant and 30 g of water were stirred at 30° C. for 2 h to obtain a high-efficiency scale inhibitor.

[0053] Example 3

[0054] The preparation method of a scale inhibitor in this embodiment comprises the following specific steps:

[0055] S1.1: Add 2.56 g of ammonium persulfate to 15 mL of water and stir for 15 min to obtain an ammonium persulfate aqueous solution;

[0056] S1.2: Under nitrogen protection, 10.81 g acrylic acid, 57.63 g citric acid, 16.92 g cysteic acid and 100 mL water were added to a four-necked flask, heated to 60 °C and stirred for 1 h, and then slowly added with aqueous ammonium persulfate solution, and the temperature was continued to rise to 85 °C for reaction for 3 h; cooled to room temperature, the pH was adjusted to 6.5 with 35% aqueous sodium hydroxide solution, and then acetone was added and stirred for 15 min, filtered, and vacuum dried at 50 °C for 24 h to obtain AA-CA-LCA copolymer;

[0057] S2.1: Under nitrogen protection, 3.64 g sorbitol, 16.1 g 2-aminoadipic acid and 0.2 g p-toluenesulfonic acid were added to a four-necked flask, heated to 80 °C and stirred for 1 h, then heated to 115 °C for reaction for 1 h, then heated to 150 °C for reaction for 4 h, then acetone was added and stirred for 0.5 h, filtered, and vacuum dried at 60 °C for 24 h to obtain a hyperbranched polymer;

[0058] S2.2: 13.5 g of hydroxyethylidene diphosphonic acid, 0.3 g of 4-dimethylaminopyridine, 0.6 g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide and 50 mL of N,N-dimethylformamide were mixed evenly, and the hyperbranched polymer solution was added dropwise, and the temperature was raised to 65°C for reaction for 8 h, and then acetone was added and stirred for 0.5 h, and the mixture was transferred to ether and stirred, precipitated, filtered, and vacuum dried at 60°C for 36 h to obtain a modified hyperbranched polymer; the hyperbranched polymer solution was prepared by stirring 4.5 g of the hyperbranched polymer with 225 mL of N,N-dimethylformamide for 20 min;

[0059] S3: 40 g of AA-CA-LCA copolymer, 15 g of modified hyperbranched polymer, 3 g of corrosion inhibitor, 8 g of surfactant and 25 g of water were stirred at 35° C. for 0.5 h to obtain a high-efficiency scale inhibitor.

[0060] Example 4

[0061] The preparation method of a scale inhibitor in this embodiment comprises the following specific steps:

[0062] S1.1: Add 2.79 g of ammonium persulfate to 15 mL of water and stir for 15 min to obtain an ammonium persulfate aqueous solution;

[0063] S1.2: Under nitrogen protection, 14.41 g acrylic acid, 38.43 g citric acid, 16.92 g sulfoalanine and 100 mL water were added to a four-necked flask, heated to 60 ° C and stirred for 1 h, and then slowly added with ammonium persulfate aqueous solution, and the temperature was continued to rise to 80 ° C for 5 h; cooled to room temperature, the pH was adjusted to 6.5 with 35% sodium hydroxide aqueous solution, and then acetone was added and stirred for 15 min, filtered, and vacuum dried at 50 ° C for 24 h to obtain AA-CA-LCA copolymer;

[0064] S2.1: Under nitrogen protection, 3.64 g sorbitol, 9.67 g 2-aminoadipic acid and 0.26 g p-toluenesulfonic acid were added to a four-necked flask, heated to 80 ° C and stirred for 1 h, then heated to 125 ° C for reaction for 1.5 h, then heated to 150 ° C for reaction for 5 h, then acetone was added and stirred for 0.5 h, filtered, and vacuum dried at 60 ° C for 24 h to obtain a hyperbranched polymer;

[0065] S2.2: 11.5 g of hydroxyethylidene diphosphonic acid, 0.4 g of 4-dimethylaminopyridine, 0.8 g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide and 50 mL of N,N-dimethylformamide were mixed evenly, and the hyperbranched polymer solution was added dropwise, and the temperature was raised to 70°C for reaction for 10 h, and then acetone was added and stirred for 0.5 h, and the mixture was transferred to ether and stirred, precipitated, filtered, and vacuum dried at 60°C for 36 h to obtain a modified hyperbranched polymer; the hyperbranched polymer solution was prepared by stirring 4.5 g of the hyperbranched polymer with 160 mL of N,N-dimethylformamide for 20 min;

[0066] S3: 35 g of AA-CA-LCA copolymer, 20 g of modified hyperbranched polymer, 3 g of corrosion inhibitor, 10 g of surfactant and 25 g of water were stirred at 50° C. for 1 h to obtain a high-efficiency scale inhibitor.

[0067] Comparative Example 1

[0068] The difference from Example 1 is that this comparative example uses an equal amount of hyperbranched polymer instead of the modified hyperbranched polymer, the preparation method of the hyperbranched polymer is the same as that of Example 1, and the rest is the same as that of Example 1.

[0069] Comparative Example 2

[0070] The difference from Example 1 is that the mass ratio of hydroxyethylidene diphosphonic acid to the hyperbranched polymer in the modified hyperbranched polymer of this comparative example is 7:1, and the rest is the same as Example 1.

[0071] Comparative Example 3

[0072] The difference from Example 1 is that the amounts of acrylic acid, citric acid and cysteic acid used in the AA-CA-LCA copolymer are adjusted in this comparative example, as shown in Table 1. The rest are the same as in Example 1.

[0073] Table 1 Amounts of acrylic acid, citric acid and cysteic acid

[0074]

[0075] Comparative Example 4

[0076] The difference from Example 1 is that no modified hyperbranched polymer is added to the high-efficiency scale inhibitor of this comparative example, and the rest is the same as Example 1.

[0077] Comparative Example 5

[0078] The difference from Example 1 is that no AA-CA-LCA copolymer is added to the high-efficiency scale inhibitor of this comparative example, and the rest is the same as Example 1.

[0079] Related tests

[0080] The high-efficiency scale inhibitors prepared in Examples 1 to 4 and Comparative Examples 1 to 5 of the present invention were performance tested in accordance with SY / T5673-2020 "General Technical Conditions for Scale Inhibitors for Oil Fields". The addition amount of the high-efficiency scale inhibitor was 20 mg / L, and the test results are shown in Table 2.

[0081] Table 2 Test results

[0082]

[0083] By comparing Comparative Example 1 and Comparative Example 2 with Example 1, it can be seen that the scale inhibition rate of the hyperbranched polymer that has not been modified with hydroxyethylidene diphosphonic acid is lower than that of the modified hyperbranched polymer; the introduction of hydroxyethylidene diphosphonic acid can increase the chelating effect on scale-forming metal ions and reduce the probability of scale formation; when the phosphate group combines with the metal ion, it will adsorb on the surface of the scale crystal, causing the growth and arrangement of the scale crystal to be distorted, which will destroy the normal growth process of the scale crystal, causing the scale to be dispersed in the water, thereby enhancing the scale inhibition effect; however, the excessive introduction of hydroxyethylidene diphosphonic acid can easily make the structure of the modified hyperbranched polymer too complicated, reduce the dispersion performance, and make the scale inhibition effect worse.

[0084] From the comparison between Comparative Example 3 and Example 1, it can be seen that when the ratio of the amounts of the three monomers acrylic acid, citric acid and sulfalanine is in the range of (1-2):(2-3):1, the scale inhibition performance of the scale inhibitor is optimal.

[0085] By comparing Comparative Examples 4 and 5 with Example 1, it can be seen that the modified hyperbranched polymer provides a large number of chelating sites and has a strong chelating ability for metal ions; the AA-CA-LCA copolymer has good lattice distortion ability and dispersion performance. After the two are compounded, they can not only efficiently chelate metal ions, but also effectively destroy the growth and aggregation of scale crystals, and the synergistic effect enhances the scale inhibition effect.

[0086] The above is an exemplary description of the present invention. It should be noted that, without departing from the core of the present invention, any simple deformation, modification or equivalent replacement that can be done by other technicians in this field without expending creative labor falls within the protection scope of the present invention.

Claims

1. A method for preparing a scale inhibitor, characterized in that: The steps include: S1: Under nitrogen protection, acrylic acid, citric acid, sulfoalanine and water are mixed evenly, the molar ratio of acrylic acid, citric acid and sulfoalanine is (1-2): (2-3): 1, and an aqueous solution of ammonium persulfate is added dropwise, and the temperature is raised for reaction; cooled to room temperature, the pH is adjusted to 6.5-7, and acetone is added and mixed evenly, filtered, and dried to obtain AA-CA-LCA copolymer; S2.1: Under nitrogen protection, sorbitol, 2-aminoadipic acid and p-toluenesulfonic acid are mixed evenly, heated to react, and then acetone is added to mix evenly, filtered, and dried to obtain a hyperbranched polymer; S2.2: Mix hydroxyethylidene diphosphonic acid, a catalyst and N,N-dimethylformamide evenly, add the hyperbranched polymer solution dropwise, heat to react, add acetone and mix evenly, filter and dry to obtain a modified hyperbranched polymer, wherein the catalyst is 4-dimethylaminopyridine and 1-ethyl-(3-dimethylaminopropyl)carbodiimide in a molar ratio of (1-2):1; S3: Evenly mix the AA-CA-LCA copolymer, the modified hyperbranched polymer, the corrosion inhibitor, the surfactant and water to obtain a high-efficiency scale inhibitor.

2. The method for preparing a scale inhibitor according to claim 1, characterized in that: In the step S1, the amount of the ammonium persulfate used is 3%-5% of the total mass of the acrylic acid, citric acid and cysteic acid.

3. The method for preparing a scale inhibitor according to claim 1, characterized in that: In the step S1, the reaction temperature is 75-85°C, and the reaction time is 3-6h.

4. The method for preparing a scale inhibitor according to claim 1, characterized in that: In the step S2.1, the molar ratio of sorbitol to 2-aminoadipic acid is 1:(2.5-5); the amount of p-toluenesulfonic acid used is 0.8%-2.2% of the total mass of sorbitol and 2-aminoadipic acid.

5. The method for preparing a scale inhibitor according to claim 1, characterized in that: In the step S2.1, the temperature-raising reaction is specifically: the temperature is raised to 115-130° C. for reaction for 1-2 hours, and then the temperature is further raised to 140-150° C. for reaction for 4-6 hours.

6. The method for preparing a scale inhibitor according to claim 1, characterized in that: In the step S2.2, the mass ratio of hydroxyethylidene diphosphonic acid to the hyperbranched polymer is (1-3):

1.

7. The method for preparing a scale inhibitor according to claim 1, characterized in that: In the step S2.2, the amount of the catalyst used is 5%-10% of the total mass of the hyperbranched polymer and hydroxyethylidene diphosphonic acid.

8. The method for preparing a scale inhibitor according to claim 1, characterized in that: In the step S2.2, the hyperbranched polymer solution is composed of a hyperbranched polymer and N,N-dimethylformamide in a ratio of 1 g: 30-50 mL.

9. The method for preparing a scale inhibitor according to claim 1, characterized in that: In the step S2.2, the reaction temperature is 60-70° C. and the reaction time is 8-10 h.

10. The method for preparing a scale inhibitor according to claim 1, characterized in that: In step S3, the amounts of AA-CA-LCA copolymer, modified hyperbranched polymer, corrosion inhibitor, surfactant and water are calculated by weight and are composed of: 35-40 parts of AA-CA-LCA copolymer, 15-25 parts of modified hyperbranched polymer, 0.5-3 parts of corrosion inhibitor, 7-10 parts of surfactant and 20-30 parts of water.

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