A class of imidazoline corrosion inhibitors with adjustable numbers of imidazoline rings and hydrophobic long carbon chains and their preparation method

Abstract

This invention belongs to the field of chemical applications, specifically relating to a class of imidazoline corrosion inhibitors with adjustable numbers of imidazoline rings and hydrophobic long carbon chains, and their preparation method. The preparation method involves synthesizing acrylic acid imidazoline from acrylic acid and diethylenetriamine. After the acrylic acid imidazoline undergoes self-polymerization, it is then amidated with a long-chain organic acid to obtain a long-chain amide polymerized imidazoline corrosion inhibitor. The inhibitor is characterized by having multiple imidazoline rings in its structure, enabling more stable adsorption at multiple active sites on metal surfaces. The multiple carbon chains in the molecule also provide more effective barrier against corrosive media, and the number of imidazoline rings and hydrophobic long chains can be adjusted as needed.

Description

Technical Field

[0001] This invention belongs to the field of chemical applications, specifically relating to a class of imidazoline corrosion inhibitors with adjustable numbers of imidazoline rings and hydrophobic long chains, and their preparation methods. Background Technology

[0002] Corrosion of metallic materials exists in almost all areas of industrial production and living facilities, causing enormous losses and harm to society, and may even lead to serious safety accidents. Adding corrosion inhibitors for corrosion prevention has advantages such as high operability, high economic efficiency, rapid effect, and overall protection, and has become one of the effective means to prevent corrosion of metal equipment.

[0003] Imidazolines and their derivatives have advantages such as being green, non-toxic, and having good corrosion inhibition effects, and are widely used. Long-chain fatty acid imidazolines have poor water solubility, making them difficult to disperse in aqueous systems, resulting in poor corrosion inhibition. Therefore, long-chain fatty acid imidazolines generally need to be quaternized with benzyl chloride to prepare quaternized imidazolines. For example, patent CN105085402A synthesizes imidazoline quaternary ammonium salt corrosion inhibitors using rosin acid, diethylenetriamine, and benzyl chloride as raw materials; patent CN104829539A synthesizes bis-imidazoline quaternary ammonium salts using adipic acid, polyamines, thiourea, and benzyl chloride as raw materials. Quaternized imidazolines have surface activity, improving dispersion, but because quaternized imidazolines contain Cl... - Furthermore, quaternizing agents can cause metal corrosion, and most of them are carcinogenic. Therefore, industry professionals have been dedicated to developing environmentally friendly, aqueous, halogen-free imidazoline corrosion inhibitors that can replace imidazoline quaternary ammonium salts.

[0004] Patent CN108164465A synthesizes a corrosion inhibitor containing a bicyclic imidazoline using monocyclic imidazoline of lauric acid and 1,3-dibromopropane; patent CN114685372A first synthesizes oleic acid imidazoline using diethylenetriamine and oleic acid, and then amidates it with the three carboxylic acids in the citric acid structure to generate a corrosion inhibitor containing a tricyclic imidazoline. However, these types of corrosion inhibitors are mostly oil-soluble, and when used in aqueous systems, they are poorly dispersed, resulting in poor corrosion inhibition.

[0005] Patent CN101705112A uses long-chain fatty acids, polyamines, and glacial acetic acid as raw materials, employing a one-pot method. First, the primary and secondary amines (excluding one secondary amine group) of the polyamine are acylated at their nitrogenous sites to generate a polyamide. Then, the long-chain fatty acid is dehydrated to form an imidazoline ring, resulting in an imidazoline corrosion inhibitor containing one or more acetyl groups. This method has several drawbacks. In the first step of synthesis, it is difficult to ensure that the long-chain fatty acid is precisely attached to one end of the polyamine. Furthermore, even when other amine groups are amidated, the amine group adjacent to that end remains unacylated. Due to the high reactivity of acetic acid, it reacts preferentially, resulting in a low probability of generating the target intermediate. Because of the large steric hindrance at the polyamine end, the cyclization reaction requires a high temperature of 240°C. Moreover, this corrosion inhibitor uses only the amide as a hydrophilic group, resulting in low hydrophilicity; therefore, a surfactant is still needed as an auxiliary agent in practical applications.

[0006] Therefore, overcoming the shortcomings of existing imidazoline corrosion inhibitors, such as poor adsorption, poor water solubility, the presence of halide ions, or high viscosity, which make them difficult to use, and developing non-quaternary ammonium salt imidazoline corrosion inhibitors with excellent corrosion inhibition performance and good dispersibility in aqueous environments, is a problem that the industry needs to solve. Summary of the Invention

[0007] The purpose of this invention is to provide a class of imidazoline corrosion inhibitors with adjustable numbers of imidazoline rings and hydrophobic long carbon chains, as well as their preparation methods and applications. This class of imidazoline corrosion inhibitors has the following structure:

[0008]

[0009] Wherein, R is a straight-chain or branched hydrocarbon group with 10 to 20 C atoms; x is the degree of polymerization of imidazoline acrylate, x is 3 to 7; y is the degree of substitution of the amino group on the side chain of the imidazoline acrylate ring, y is 1 to 4.

[0010] The imidazoline corrosion inhibitor of the present invention, which has an adjustable number of imidazoline rings and hydrophobic carbon chains, is characterized by having multiple imidazoline rings in its structure, which can form more stable multi-active site adsorption on the metal surface, while the multiple carbon chains in the molecule can more effectively block the corrosive medium, and the number of imidazoline rings and hydrophobic long chains can be adjusted as needed.

[0011] This invention also provides a method for preparing an imidazoline corrosion inhibitor with an adjustable number of imidazoline rings and hydrophobic long carbon chains, specifically including the following steps:

[0012] (1) Acrylic acid reacts with diethylenetriamine via amidation and cyclization to generate imidazoline acrylate;

[0013] (2) Under the action of an initiator, imidazoline acrylic acid self-polymerizes to form polymerized imidazoline acrylic acid;

[0014] (3) Polymerized imidazoline acrylic acid and organic acid are amidated to obtain long-chain amide polymerized imidazoline.

[0015] In step (1), the molar ratio of diethylenetriamine to acrylic acid is 1.5 to 1; a water-carrying agent can also be added to promote the reaction. The water-carrying agent can be one or a mixture of several of benzene, toluene, and xylene.

[0016] The reaction temperature is 120–230℃, and the reaction time is 6–12 h.

[0017] In step (2), the amount of initiator used is 0.6 to 0.9% of the mass of imidazoline acrylate. The initiators include potassium persulfate, ammonium persulfate, and sodium persulfate. The self-polymerization temperature is 60 to 100°C, and the reaction time is 1 to 3 hours.

[0018] The organic acids in step (3) include: lauric acid, myristic acid, oleic acid, linoleic acid, and stearic acid; the molar ratio of the imidazoline ring of the polymerized acrylic acid to the organic acid is 3 to 1; the solvent can be one or a mixture of several of benzene, toluene, and xylene; the reaction temperature is 120 to 160°C, and the reaction time is 4 to 8 hours.

[0019] In the above preparation steps, the preferred molar ratio of diethylenetriamine to acrylic acid in step (1) is 1.3:1, and the preferred water-carrying agent is xylene.

[0020] In the above preparation steps, ammonium persulfate is preferred as the initiator in step (2).

[0021] In the above preparation steps, the preferred reaction temperature in step (3) is 140-160℃ and the reaction time is 3-5h.

[0022] Beneficial Effects: This invention provides a class of long-chain amide polymerized imidazoline corrosion inhibitors, their preparation methods, and applications. The inhibitor is characterized by multiple imidazoline rings in its structure, which can form more stable multi-active adsorption sites on the metal surface, while the multiple carbon chains in the molecule can more effectively block corrosive media. It exhibits good corrosion inhibition and can be applied to high-velocity oil and gas gathering and transportation pipelines containing CO2 / H2S, as well as in the treatment of high-velocity acidic produced water. Attached Figure Description

[0023] Figure 1 The infrared spectrum of imidazoline acrylate;

[0024] Figure 2 The mass spectrum of the polymeric imidazoline acrylate ① obtained in Example 1 is shown below.

[0025] Figure 3 The infrared spectrum of the long-chain amide polymerized imidazoline ① obtained in Example 1;

[0026] Figure 4 The mass spectrum of the polymeric imidazoline acrylate ② obtained in Example 2 is shown below.

[0027] Figure 5 This is a schematic diagram showing the water contact angle of the polymerized imidazoline acrylic acid and the polymerized imidazoline acrylic acid obtained in various examples. Detailed Implementation

[0028] The following specific implementation examples illustrate and further explain this application. However, these examples are merely illustrative and are not intended to represent all technical solutions of the present invention, nor are they intended to limit the overall technical solution of the present invention. Any modifications or substitutions to the same or similar technical features are within the scope of protection of this invention.

[0029] Example 1

[0030] In a 250 mL four-necked flask equipped with a mechanical stirrer, acrylic acid (0.20 mol, 14.41 g), diethylenetriamine (0.20 mol, 20.63 g), and 50.0 mL of xylene were added. A thermometer and a reflux condenser were installed, and nitrogen gas was introduced for protection. The stirring was started, and the mixture was heated to 140 °C and reacted for 2 h. Then, a water separator was added, and the reaction was allowed to proceed for 1 h to remove water, leaving a small amount of xylene. The temperature was then raised to 200 °C, and the cyclization reaction was allowed to proceed for 6 h. After solvent removal, imidazoline acrylic acid was obtained (IR spectrum attached). Figure 1 (As shown).

[0031] Appendix Figure 1 Middle, 3416cm -1 The peak value is the absorption vibration peak of the amino group at 2924 cm⁻¹. -1 and 2854cm -1 The absorption peaks for the hydrocarbons of methyl and methylene groups are at 1603 cm⁻¹. -1 The peak at position C=N of the imidazoline ring indicates the synthesis of the imidazoline acrylic acid product.

[0032] Take 0.15 mol (27.80 g) of imidazoline acrylic acid and 0.22 g of ammonium persulfate (0.8% by mass of imidazoline acrylic acid, dissolved in 20.0 mL of distilled water); add them together to a 250 mL dry four-necked flask equipped with a reflux condenser, mechanical stirrer, and nitrogen inlet tube; purge with nitrogen for 20 min to remove air from the flask. Turn on the heater and stir, raise the temperature to 80 °C, and control the reaction time to 1 h; distill under reduced pressure to obtain a yellow transparent polymerized imidazoline acrylic acid ①. Seal and store for later use, and measure the molecular weight (ESI). + The mass spectrum is shown in the attached figure. Figure 2 (As shown).

[0033] Appendix Figure 2 Four main peaks can be observed, located at m / z: 140.3, 293.2, 413.3, and 551.4, corresponding to the addition peaks of polymers with polymerization degrees x = 1 to 4 and protons (Mn+1), respectively. Therefore, the polymerized imidazoline acrylate ① is a polymer with a polymerization degree of 3 as the main component.

[0034] Take the prepared polymerized imidazoline acrylate ①, oleic acid (0.05 mol, 14.12 g), and 50.0 mL of xylene, and add them to a dry 250 mL three-necked flask equipped with a thermometer, reflux condenser, and mechanical stirrer. Turn on the stirring and heating device, slowly raise the temperature to 150 °C and reflux for azeotropic dehydration, reacting for 5 h. When the xylene layer in the water separator is transparent and no small water droplets settle downwards, the reaction is considered to be basically complete. Remove the solvent to obtain oleamide polymerized imidazoline (OPI3-1, where 3 represents the degree of polymerization and 1 represents the degree of substitution; the infrared spectrum is attached). Figure 3 (As shown).

[0035] Appendix Figure 3 3433cm -1 The peak at 2935 cm⁻¹ represents the absorption vibration of the NH bond. -1 and 2821cm -1 The absorption peaks for the hydrocarbons of methyl and methylene groups are at 1648 cm⁻¹. -1 The absorption peak at 1625 cm⁻¹ is due to the stretching vibration of the carbonyl group of the amide. -1 The peak at 721 cm⁻¹ is a characteristic peak of the imidazoline ring -C=N⁻. -1 The presence of four consecutive hydrocarbon vibration absorption peaks at the position confirms the synthesis of the long-chain amide polymerized imidazoline product.

[0036] Example 2

[0037] In a 250 mL four-necked flask equipped with a mechanical stirrer, acrylic acid (0.20 mol, 14.41 g), diethylenetriamine (0.24 mol, 24.76 g), and 50.0 mL of xylene were added; a thermometer and a reflux condenser were installed, and nitrogen gas was introduced for protection. Stirring was started, and the mixture was heated to 140 °C and reacted for 4 h. A water separator was then added, and the reaction was allowed to proceed for 1 h to remove water, leaving a small amount of xylene. The temperature was then raised to 210 °C, and the cyclization reaction was allowed to continue for 5 h. After solvent removal, imidazoline acrylic acid was obtained.

[0038] Dissolve 0.15 mol (27.80 g) of imidazoline acrylic acid and 0.22 g of ammonium persulfate (0.8% of the mass fraction of imidazoline acrylic acid) in 20.0 mL of distilled water. Add both solutions to a 250 mL dry four-necked flask equipped with a reflux condenser, mechanical stirrer, and nitrogen inlet. Purge with nitrogen for 20 min to remove air from the flask. Start heating and stirring, raise the temperature to 80 °C, and control the reaction time for 1.5 h. Distill under reduced pressure to obtain polymerized imidazoline acrylic acid ②. Store in a sealed container for later use. Measure the molecular weight (ESI). + The mass spectrum is shown in the attached figure. Figure 4 (As shown).

[0039] Appendix Figure 4 Seven main peaks were observed, located at m / z: 140.3, 292.3, 413.3, 551.4, 688.5, 825.6, and 962.7, corresponding to the addition peaks (Mn+1) of polymers with polymerization degrees x = 1 to 7. Polymeric imidazoline acrylate ② is a polymer with a polymerization degree predominantly of 5.

[0040] Take the prepared polymeric imidazoline acrylate ②, oleic acid (0.03 mol, 8.48 g), and 50.0 mL of xylene; add them to a dry 250 mL three-necked flask equipped with a thermometer, reflux condenser, and mechanical stirrer. Turn on the stirring and heating apparatus, slowly raise the temperature to 140 °C, and perform azeotropic dehydration for 6 h. When the xylene layer in the water separator is transparent and no small water droplets settle downwards, the reaction is considered to be basically complete. Remove the solvent to obtain oleic acid amide polymeric imidazoline OPI5-1 (where 5 is the degree of polymerization and 1 is the degree of substitution).

[0041] Example 3

[0042] In a 250 mL four-necked flask equipped with a mechanical stirrer, acrylic acid (0.20 mol, 14.41 g), diethylenetriamine (0.24 mol, 24.76 g), and 50.0 mL of xylene were added; a thermometer and a reflux condenser were installed, and nitrogen was introduced for protection. Stirring was started, and the mixture was heated to 140 °C and reacted for 3 h. A water separator was then added, and the reaction was allowed to proceed for 1 h to remove water, leaving a small amount of xylene. The temperature was then raised to 190 °C, and the cyclization reaction was allowed to continue for 6 h. After solvent removal, imidazoline acrylic acid was obtained.

[0043] Dissolve 0.15 mol (27.80 g) of imidazoline acrylic acid and 0.22 g of ammonium persulfate (0.8% of the mass fraction of imidazoline acrylic acid) in 20.0 mL of distilled water. Add both to a 250 mL dry four-necked flask equipped with a reflux condenser, a mechanical stirrer, and a nitrogen inlet. Purge with nitrogen for 20 min to remove air from the flask. Turn on the heater and stir, raise the temperature to 80 °C, control the reaction time to 1.5 h, and distill under reduced pressure to obtain polymerized imidazoline acrylic acid ②.

[0044] Take the prepared polymeric imidazoline acrylate ②, oleic acid (0.06 mol, 16.96), and 50.0 mL of xylene; add them to a dry 250 mL three-necked flask equipped with a thermometer, reflux condenser, and mechanical stirrer. Turn on the stirring and heating apparatus, and slowly raise the temperature to reflux for azeotropic dehydration. When the xylene layer in the water separator is transparent and no small water droplets settle downwards, the reaction is considered to be basically complete. Remove the solvent to obtain oleic acid amide polymeric imidazoline OPI5-2 (where 5 is the degree of polymerization and 2 is the degree of substitution).

[0045] Example 4

[0046] In a 250 mL four-necked flask equipped with a mechanical stirrer, acrylic acid (0.20 mol, 14.41 g), diethylenetriamine (0.24 mol, 24.76 g), and 50.0 mL of xylene were added; a thermometer and a reflux condenser were installed, and nitrogen gas was introduced for protection. Stirring was started, and the mixture was heated to 140 °C and reacted for 2 h; then a water separator was added, and the reaction was dehydrated for 1 h, leaving a small amount of xylene; the temperature was then raised to 190 °C, and the cyclization reaction was carried out for 6 h. After solvent removal, imidazoline acrylic acid was obtained.

[0047] Dissolve 0.15 mol (27.80 g) of imidazoline acrylic acid and 0.22 g of ammonium persulfate (0.8% of the mass fraction of imidazoline acrylic acid) in 20.0 mL of distilled water. Add both to a 250 mL dry four-necked flask equipped with a reflux condenser, a mechanical stirrer, and a nitrogen inlet. Purge with nitrogen for 20 min to remove air from the flask. Turn on the heater and stir, raise the temperature to 80 °C, control the reaction time to 1.5 h, and distill under reduced pressure to obtain polymerized imidazoline acrylic acid ②.

[0048] Take the prepared polymeric imidazoline acrylate ②, oleic acid (0.09 mol, 25.42 g), and 50.0 mL of xylene; add them to a dry 250 mL three-necked flask equipped with a thermometer, reflux condenser, and mechanical stirrer. Turn on the stirring and heating apparatus, and slowly raise the temperature to 150 °C for azeotropic dehydration. When the xylene layer in the water separator is transparent and no small water droplets settle downwards, the reaction is considered to be basically complete. Remove the solvent to obtain oleic acid amide polymeric imidazoline OPI5-3 (where 5 is the degree of polymerization and 3 is the degree of substitution).

[0049] Example 5

[0050] In a 250 mL four-necked flask equipped with a mechanical stirrer, acrylic acid (0.20 mol, 14.41 g), diethylenetriamine (0.24 mol, 24.76 g), and 50 mL of xylene were added; a thermometer and a reflux condenser were installed, and nitrogen gas was introduced for protection. Stirring was started, and the mixture was heated to 140 °C and reacted for 2 h. A water separator was then added, and the reaction was allowed to proceed for 1 h to remove water, leaving a small amount of xylene. The temperature was then raised to 190 °C, and the cyclization reaction was allowed to continue for 6 h. After solvent removal, imidazoline acrylic acid was obtained.

[0051] Dissolve 0.15 mol (27.80 g) of imidazoline acrylic acid and 0.22 g of ammonium persulfate (0.8% of the mass fraction of imidazoline acrylic acid) in 20.0 mL of distilled water. Add both to a 250 mL dry four-necked flask equipped with a reflux condenser, mechanical stirrer, and nitrogen inlet. Purge with nitrogen for 20 min to remove air from the flask. Turn on the heater and stir, raise the temperature to 80 °C, and control the reaction time for 1 h to obtain polymerized imidazoline acrylic acid ②. Distill under reduced pressure to obtain a yellow transparent polymer.

[0052] Take the prepared polymerized imidazoline acrylate ②, lauric acid (0.09 mol, 18.04 g), and 50.0 mL of xylene; add them to a dry 250 mL three-necked flask equipped with a thermometer, reflux condenser, and mechanical stirrer. Turn on the stirring and heating device, slowly raise the temperature to 160 °C, and perform azeotropic dehydration for 5 h. When the xylene layer in the water separator is transparent and no small water droplets settle downwards, the reaction is considered to be basically complete. Remove the solvent to obtain laurate amide polymerized imidazoline (LAPI5-3, where 5 is the degree of polymerization and 3 is the degree of substitution).

[0053] Example 6

[0054] In a 250 mL four-necked flask equipped with a mechanical stirrer, acrylic acid (0.20 mol, 14.41 g), diethylenetriamine (0.24 mol, 24.76 g), and 50 mL of xylene were added; a thermometer and a reflux condenser were installed, and nitrogen gas was introduced for protection. Stirring was started, and the mixture was heated to 140 °C and reacted for 2 h; then a water separator was added, and the reaction was dehydrated for 1 h, leaving a small amount of xylene; the temperature was then raised to 190 °C, and the cyclization reaction was carried out for 6 h. After solvent removal, imidazoline acrylic acid was obtained.

[0055] Dissolve 0.15 mol (27.80 g) of imidazoline acrylic acid and 0.22 g of ammonium persulfate (0.8% of the mass fraction of imidazoline acrylic acid) in 20.0 mL of distilled water. Add both to a 250 mL dry four-necked flask equipped with a reflux condenser, a mechanical stirrer, and a nitrogen inlet. Purge with nitrogen for 20 min to remove air from the flask. Turn on the heater and stir, raise the temperature to 80 °C, and control the reaction time for 1 h to obtain polymerized imidazoline acrylic acid ②. Distill under reduced pressure to obtain a yellow transparent polymer.

[0056] Take the prepared polymerized imidazoline acrylate ②, stearic acid (0.09 mol, 25.60 g), and 50.0 mL xylene; add them to a dry 250 mL three-necked flask equipped with a thermometer, reflux condenser, and mechanical stirrer. Turn on the stirring and heating device, slowly raise the temperature to 160 °C, and perform azeotropic dehydration for 6 h. When the xylene layer in the water separator is transparent and no small water droplets settle downwards, the reaction is considered to be basically complete. Remove the solvent to obtain stearateamide polymerized imidazoline SAPI5-3 (SAPI5-3, where 5 is the degree of polymerization and 3 is the degree of substitution).

[0057] Example 7 Effect Experiment

[0058] (1) Water solubility test

[0059] Equal masses of the synthesized products were weighed and compared with the long-chain amide polymeric imidazoline prepared in Examples 1-6 and the ungrafted polymeric acrylic imidazoline ① and ② to observe the solubility and dispersion of the corrosion inhibitors in water. The solubility properties and HLB values ​​of the corrosion inhibitors in water are shown in Table 1:

[0060] Table 1

[0061] product Phenomenon HLB value Polyacrylic acid imidazoline ① clear solution >13 Polyacrylic acid imidazoline ② clear solution >13 Example 1 Product Translucent to transparent dispersions 10～13 Example 2 Product clear solution >13 Example 3 Product Translucent to transparent dispersions 10～13 Example 4 Product Translucent to transparent dispersions 10～13 Example 5 Product Translucent to transparent dispersions 10～13 Example 6 Product Translucent to transparent dispersions 10～13

[0062] As can be seen from the test results in Table 1 above, this type of long-chain amide polymerized imidazoline has good water solubility and dispersibility.

[0063] (2) Contact angle test

[0064] At 30℃, 20 # Carbon steel was immersed in a 1M sulfuric acid solution containing 0.50 g / L of the long-chain amide polymerized imidazoline prepared in Examples 1-6 for 6 hours, and then the surface was dried with cold air. The contact angle of water droplets on the metal surface is shown in the diagram. Figure 5 As shown.

[0065] from Figure 5 The test results show that, compared with ungrafted polymeric acrylic imidazoline, this type of long-chain amide polymeric imidazoline has better hydrophobicity and can effectively block contact with corrosive media.

[0066] (3) Corrosion inhibition performance test

[0067] The experiment was conducted in accordance with the performance evaluation method of corrosion inhibitors for oilfield produced water (SY / T 5273-2000), and the corrosion inhibition rate was tested using the rotating plate weight loss method.

[0068] Using a 1 mol / L H₂SO₄ solution as the acidic corrosion system, a container measuring 5.0 × 2.5 × 0.2 cm was used. 3 20 # Steel sheets were used as corrosion testing materials. The corrosion was tested at a temperature of 30℃, a rotation speed of 100 r / min, and a corrosion time of 6 h, with corrosion inhibitors added at concentrations of 0.05 g / L, 0.10 g / L, and 0.15 g / L on 20... # The corrosion inhibition rate of carbon steel; and the effects of corrosion inhibitors at 30℃, 150 r / min, and an addition amount of 0.15 g / L on corrosion times of 20 g / L at 12 h, 36 h, and 48 h. # Corrosion inhibition rate of carbon steel. Comparative analysis of the long-chain amide polymeric imidazoline prepared in Examples 1-6 with ungrafted polymeric acrylic acid imidazoline ① and ②.

[0069] According to the formula, The corrosion inhibition rate was calculated, where Δm0 is the mass loss of the blank test steel sheet; and Δm1 is the mass loss of the test steel sheet after adding the corrosion inhibitor.

[0070] Table 2 shows the corrosion inhibition rates of the long-chain amide polymeric imidazoline and the ungrafted polymeric acrylic acid imidazoline ① and ② prepared in Examples 1-6 as a function of addition, at a temperature of 30℃, a rotation speed of 100r / min, and a corrosion time of 6h.

[0071] Table 2

[0072]

[0073]

[0074] Experimental results show that, compared with ungrafted polymeric imidazoline acrylic acid, the long-chain amide polymeric imidazoline corrosion inhibitor prepared in this invention exhibits good corrosion inhibition performance even when added in small amounts.

[0075] Table 3 shows the corrosion inhibition rates of the long-chain amide polymeric imidazoline and the ungrafted polymeric acrylic acid imidazoline ① and ② prepared in Examples 1-6 as a function of corrosion time at a temperature of 30℃, a rotation speed of 150 r / min, and an addition amount of 0.20 g / L.

[0076] Table 3

[0077]

[0078] Experimental results show that, compared with ungrafted polymeric imidazoline acrylic acid, the long-chain amide polymeric imidazoline corrosion inhibitor prepared in this invention can maintain long-term corrosion inhibition and has broad application prospects in high-velocity oil and gas gathering and transportation pipelines containing CO2 / H2S and in the treatment of high-velocity acidic produced water.

Claims

1. A type of imidazoline corrosion inhibitor with an adjustable number of imidazoline rings and hydrophobic long carbon chains, characterized in that, The preparation method of the corrosion inhibitor is as follows: (1) Acrylic acid reacts with diethylenetriamine via amidation and cyclization to generate imidazoline acrylate; (2) Under the action of an initiator, imidazoline acrylic acid self-polymerizes to form polymeric imidazoline acrylic acid; The initiators are potassium persulfate, ammonium persulfate, and sodium persulfate, and their dosage is 0.6-0.9% of the mass of imidazoline acrylate, with a degree of polymerization of 3-7. (3) Polymerized imidazoline acrylic acid is amidated with organic acid to obtain long-chain amide polymerized imidazoline; The organic acids are lauric acid, myristic acid, oleic acid, linoleic acid, and stearic acid, with an acyl group substitution degree of 1-4. The corrosion inhibitor is applied to high-velocity oil and gas gathering and transportation pipelines containing CO2 / H2S, as well as to the treatment of high-velocity acidic produced water.

2. The imidazoline corrosion inhibitor with an adjustable number of imidazoline rings and hydrophobic long carbon chains according to claim 1, characterized in that, In step (1), the molar ratio of diethylenetriamine to acrylic acid is 1.5 to 1; the reaction temperature is 120 to 230 °C; and the reaction time is 6 to 12 h.

3. The imidazoline corrosion inhibitor with an adjustable number of imidazoline rings and hydrophobic long carbon chains according to claim 1, characterized in that, The self-polymerization temperature in step (2) is 60~100℃, and the reaction time is 1~3 h.

4. The imidazoline corrosion inhibitor with an adjustable number of imidazoline rings and hydrophobic long carbon chains according to claim 1, characterized in that, In step (3), the molar ratio of the imidazoline ring to the organic acid in the polymerized imidazoline acrylic acid is 3 to 1.

5. The imidazoline corrosion inhibitor with an adjustable number of imidazoline rings and hydrophobic long carbon chains according to claim 1, characterized in that, In step (3), the amidation reaction temperature is 120~160 ℃ and the reaction time is 4~8 h.

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