Dual-functional quaternary ammonium salt ion corrosion inhibitor as well as preparation method and application thereof

Abstract

The invention relates to the technical field of corrosion inhibitors, in particular to a bifunctional quaternary ammonium salt ion corrosion inhibitor and a preparation method and application thereof. The preparation method comprises the following steps: S1, synthesizing a thioether intermediate; s2, synthesizing a dication precursor; and S3, anion exchange and pH response modification. Through three innovations of double-coordination synergy, a gemini structure and pH response, the bottlenecks of a traditional corrosion inhibitor in temperature resistance, sulfur resistance, environmental adaptability and environmental friendliness are broken through, a low-cost, efficient and green solution is provided for long-acting corrosion prevention of a petroleum pipeline in a high-temperature, high-pressure and high-sulfuric-acid-content environment, and remarkable industrial application value and environmental protection benefits are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of corrosion inhibitors, in particular to a dual-functionalized quaternary ammonium salt ion corrosion inhibitor and a preparation method and application thereof. Background Art

[0002] Oil pipeline transportation is a core component of global energy supply, and pipeline corrosion caused by acidic oil and gas media has become a key challenge constraining the industry's safety and economic viability. According to statistics, the oil industry accounts for a significant portion of the global economic losses caused by corrosion each year. In my country, in the development of extremely high-sulfur gas fields, such as those in the Southwest Oil and Gas Field, H2S partial pressures can reach over 5 MPa. Carbon steel pipelines, exposed to temperatures exceeding 120°C, experience corrosion rates exceeding 10 mm / year, making traditional anti-corrosion technologies inadequate.

[0003] Currently, oil pipeline corrosion protection primarily relies on corrosion inhibitors. However, the synthesis cost of some inhibitors is prohibitive, and some, such as halogenated inhibitors, perform well at high temperatures but are highly toxic, making them incompatible with environmental protection. Epoxy coatings, which physically isolate corrosive media, are susceptible to high-pressure erosion and easy detachment. Nickel-based composite pipe coatings offer excellent corrosion resistance but are expensive. Cathodic protection technologies using impressed current or sacrificial anodes can inhibit corrosion but are less adaptable to complex structures.

[0004] There are many problems with traditional quaternary ammonium salt corrosion inhibitors: (1) The release of halogen ions above 120°C increases toxicity, and the thermal stability of quaternary ammonium cations decreases, causing the adsorption film to fall off. (2) The single functional group is unable to cope with the wide range of acidic environments of pH 2-6 and has poor environmental adaptability. (3) When the H2S partial pressure is >3MPa, the N coordination bond is easily replaced by S. - Replacement leads to a sharp drop in corrosion inhibition efficiency, resulting in weak anti-sulfur performance; (4) In coating technology, epoxy coatings are prone to pinhole defects in high-pressure H2S environments, causing Cl - Penetration local corrosion, nickel-based composite pipes are expensive; (5) cathodic protection has a blind area of ​​uneven current distribution in high resistivity media; in addition, Br - / Cl - Quaternary ammonium salts are difficult to degrade and can easily cause soil salinization. Their cationic structure may also destroy microbial cell membranes and cause biological toxicity.

[0005] Therefore, providing a new type of corrosion inhibitor has great market application prospects. Summary of the Invention

[0006] The first aspect of the present invention provides a method for preparing a bifunctional quaternary ammonium salt ion corrosion inhibitor, comprising the following steps:

[0007] S1. Synthesis of thioether intermediates;

[0008] ;

[0009] S2. Synthesis of dicationic precursors;

[0010] ;

[0011] S3. Anion exchange and pH-responsive modification;

[0012] .

[0013] In some preferred embodiments, the general structural formula of the bifunctionalized quaternary ammonium salt ion corrosion inhibitor is [(BTA-SRN + (CH3)2)2-L] 2+ 2BTA - .

[0014] In the cationic part of the diquaternary ammonium structure, two BTA-SRN + The (CH3)2 units are connected by a linker L (methylene / ether bond) to form a gemini quaternary ammonium salt; R is a C12-C18 alkyl chain, and a sulfide bond (-S-) is introduced to connect BTA and the alkyl chain; BTA is a benzotriazole group, providing an N coordination center; in the anion part, the di-BTA⁻ can form a 1:1 ion pair with the cation.

[0015] Key functional groups: thioether bond (-S-), dicationic structure, and introduction of ethyl carboxylate group (-COOCH3) at the end of the alkyl chain.

[0016] In some preferred embodiments, the synthesis of the thioether intermediate specifically includes:

[0017] S11. Add 4-chloromethylbenzotriazole, dodecanethiol, and anhydrous ethanol to a container and stir until completely dissolved;

[0018] S12. Potassium carbonate was added in batches and the reaction was kept warm;

[0019] S13. After the reaction is completed, cool to room temperature and filter to remove the generated potassium chloride precipitate;

[0020] S14. The filtrate was distilled under reduced pressure to remove ethanol and obtain a light yellow oily intermediate BTA-SC. 12 H 25 .

[0021] In some preferred embodiments, the reaction equation for the synthesis of the thioether intermediate is as follows:

[0022]

[0023] In some preferred embodiments, the molar ratio of 4-chloromethylbenzotriazole to dodecanethiol is (1-3): (1-3).

[0024] In some preferred embodiments, the synthesis of the dicationic precursor specifically includes:

[0025] S21. BTA-SC 12 H 25 and acetonitrile were added into the reaction vessel and stirred to dissolve;

[0026] S22. Add 1,4-dibromobutane and heat the reaction;

[0027] S23. After the reaction is completed, cool to room temperature and remove acetonitrile by distillation under reduced pressure to obtain a white solid intermediate .

[0028] In some preferred embodiments, the reaction equation for the synthesis of the dicationic precursor is as follows:

[0029]

[0030] In some preferred embodiments, the specific conditions for the insulation reaction in S12 are: maintaining the reaction temperature at 55-65°C and reflux stirring for 5-10 hours; the specific conditions for the heating reaction in S22 are: heating to 75-85°C and reflux stirring for 20-30 hours.

[0031] In some preferred embodiments, the BTA-SC 12 H 25 The molar ratio of 1,4-dibromobutane to 1,4-dibromobutane is (1-3):1.

[0032] In some preferred embodiments, the anion exchange and pH response modification specifically include:

[0033] S31. [(BTA-SC 12 H 25 -N + (CH3)2)2-(CH2)4] 2+ Br2 - Dissolve in deionized water, add NaBTA aqueous solution, stir at room temperature to generate white precipitate, filter and wash to obtain [(BTA-SC 12 H 25 -N + (CH3)2)2-(CH2)4] 2+ (BTA - )2;

[0034] S32. The product of S31 was dissolved in acetonitrile, ethyl acrylate and concentrated sulfuric acid were added for catalytic esterification, and the mixture was stirred under reflux;

[0035] S33. After the reaction is completed, acetonitrile is removed by distillation under reduced pressure, and the residue is washed with anhydrous ether and dried in vacuum to obtain the target product.

[0036] The purpose of vacuum drying in S33 of the present invention is to remove residual solvents (such as acetonitrile and diethyl ether) and volatile impurities to obtain a pure product, which is a solid corrosion inhibitor. In actual use, the solid corrosion inhibitor can be applied in the following ways:

[0037] (1) Solid corrosion inhibitor is dissolved in crude oil, water or organic solvent to form an ionic liquid solution, which is then sprayed on the pipeline surface;

[0038] (2) Solid corrosion inhibitors utilize their melting point characteristics (melting at high temperatures) to spontaneously form a liquid adsorption film at the pipeline operating temperature.

[0039] In some preferred embodiments, the reaction equation of the anion exchange and pH response modification is as follows:

[0040]

[0041]

[0042] In some preferred embodiments, [(BTA-SC 12 H 25 -N + (CH3)2)2-(CH2)4] 2+ Br2 - The molar ratio of HCl and NaBTA is 1:(1-3).

[0043] The second aspect of the present invention provides a dual-functionalized quaternary ammonium salt ion corrosion inhibitor obtained by the above-mentioned preparation method.

[0044] The third aspect of the present invention provides an application of a dual-functionalized quaternary ammonium salt ion corrosion inhibitor in the anti-corrosion of petroleum pipelines.

[0045] Compared with the prior art, the present invention has the following beneficial effects:

[0046] 1. The present invention enhances adsorption stability at high temperatures through sulfide bonds and BTA double coordination centers, avoids thermal decomposition of quaternary ammonium cations to improve temperature resistance and corrosion resistance, and avoids decomposition of halogen ions and degradable carboxylate groups to reduce toxicity and environmental hazards.

[0047] 2. The present invention introduces a pH-responsive carboxylate group to achieve adaptive film formation under acidic conditions and improve the adsorption stability with a wide range of acidic adaptability.

[0048] 3. The dual cationic structure of the present invention improves surface coverage and film density, replacing the limitations of traditional coatings and cathodic protection, and achieving long-term corrosion protection under high pressure, high temperature and complex structures.

[0049] 4. The present invention breaks through the bottlenecks of traditional corrosion inhibitors in temperature resistance, sulfur resistance, environmental adaptability and environmental protection through three major innovations: dual coordination synergy, gemini structure and pH response. It provides a low-cost, high-efficiency and green solution for long-term corrosion protection of oil pipelines in high temperature, high pressure and high sulfuric acid environment, and has significant industrial application value and environmental benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 BTA-SC 12 H 25 Physical picture;

[0051] Figure 2 [(BTA-SC 12 H 25 -N + (CH3)2)2-(CH2)4] 2+ Br2 - Physical picture;

[0052] Figure 3 [(BTA-SC 12 H 25 -N + (CH3)2)2-(CH2)4] 2+ (BTA - 2. Physical picture;

[0053] Figure 4 It is a line chart of corrosion inhibition efficiency data. DETAILED DESCRIPTION

[0054] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0055] Example 1

[0056] This embodiment provides a dual-functionalized quaternary ammonium salt ion corrosion inhibitor, and the preparation method includes the following steps:

[0057] S1. Thioether intermediate synthesis;

[0058] S11. Add 0.1 mol 4-chloromethylbenzotriazole, 0.1 mol dodecanethiol and 50 ml of anhydrous ethanol to a container and stir until completely dissolved;

[0059] S12 was added in two batches of 0.15 mol potassium carbonate, the reaction temperature was maintained at 60 ° C, and refluxed with stirring for 8 hours;

[0060] S13. After the reaction is completed, cool to room temperature and filter to remove the generated potassium chloride precipitate;

[0061] S14. The filtrate was distilled under reduced pressure to remove ethanol and obtain a light yellow oily intermediate BTA-SC. 12 H 25 ,See Figure 1 .

[0062] S2. Dicationic precursor synthesis;

[0063] S21. 0.05 mol BTA-SC 12 H 25 Add 80 ml of acetonitrile to the reaction vessel and stir to dissolve;

[0064] S22. Add 0.025 mol of 1,4-dibromobutane, raise the temperature to 80°C, and reflux with stirring for 24 hours;

[0065] S23. After the reaction was completed, the mixture was cooled to room temperature and acetonitrile was removed by distillation under reduced pressure to obtain a white solid intermediate [(BTA-SC 12 H 25 -N + (CH3)2)2-(CH2)4] 2+ Br2 - ,See Figure 2 .

[0066] S3. Anion exchange and pH-responsive modification;

[0067] S31. 0.025 mol [(BTA-SC 12 H 25 -N + (CH3)2)2-(CH2)4] 2+ Br2 - Dissolved in 50 ml of deionized water, added 0.05 mol of 2 mol / L NaBTA aqueous solution, stirred at room temperature for 2 hours to form a white precipitate, filtered and washed with deionized water three times to obtain [(BTA-SC 12 H 25 -N + (CH3)2)2-(CH2)4] 2+ (BTA - )2;

[0068] S32 0.025 mol of the product of S31 was dissolved in 80 ml of acetonitrile, 0.05 mol of ethyl acrylate and 0.1 ml of 98% concentrated sulfuric acid were added for catalytic esterification, and the mixture was stirred at reflux for 4 hours;

[0069] S33. After the reaction was completed, acetonitrile was removed by distillation under reduced pressure, and the residue was washed three times with anhydrous ether and dried in vacuo to obtain the desired product. Figure 3 .

[0070] Performance Testing

[0071] The following is a pipeline simulation anti-corrosion experiment of the corrosion inhibitor prepared in Example 1:

[0072] 1. Experimental Preparation

[0073] (1) Material preparation: Prepare multiple carbon steel specimens of the same material and size (simulating the material of oil pipelines). Polish the surface of the specimens with sandpaper to remove the oxide layer and impurities to make the surface smooth. Rinse with deionized water and then with anhydrous ethanol. After drying, accurately weigh them with an analytical balance and record the initial mass m0.

[0074] A solution simulating an acidic oil and gas medium was prepared, with concentrations of 0.1 mol / L H2S, 0.05 mol / L CO2, and 0.6 mol / L Cl- to simulate an extremely high sulfur gas field environment such as an oil and gas field. At the same time, different concentrations of Example 1 dissolved in 95% industrial ethanol were prepared as a corrosion inhibitor solution.

[0075] (2) Experimental equipment: prepare several glass containers with lids for immersing the test pieces, and ensure that the containers are clean and well sealed; prepare a constant temperature device to control the immersion temperature at 120°C; prepare appropriate reagents and tools for removing corrosion products from the surface of the test pieces, and select a rust remover based on the characteristics of the corrosion products.

[0076] 2. Experimental Procedure

[0077] (1) Group immersion: Carbon steel specimens were divided into multiple groups. One group, serving as a blank control group, was immersed in a simulated acidic oil and gas medium solution without the target corrosion inhibitor. The other groups were immersed in simulated acidic oil and gas medium solutions containing different concentrations of the target corrosion inhibitor. Multiple replicates were set up for each group to improve experimental accuracy. After sealing all containers, they were placed in a device with a constant temperature of 120°C and 5 MPa, maintained at a stable temperature, and immersed for 7 days.

[0078] (2) Removal and weighing: After the immersion time is over, remove the test pieces one by one. Remove the corrosion products on the surface of the test pieces, and ensure that the base metal is not damaged during the removal of the corrosion products.

[0079] 3. Data calculation

[0080] (1) Calculation of weight loss: Calculate the weight loss of each specimen Δm = m0 - m1.

[0081] (2) Calculation of corrosion rate: According to the surface area S of the test piece, the corrosion rate v is calculated using the formula v = S × tΔm, with the unit being g / (m 2 ·h).

[0082] (3) Calculation of corrosion inhibition efficiency: For the experimental group containing corrosion inhibitor, calculate the corrosion inhibition efficiency The experimental data are shown in Table 1 and Figure 4 .

[0083] Table 1 Weight loss test data

[0084]

[0085] From the above data, it can be seen that the corrosion inhibitor prepared by the present invention provides a long-term anti-corrosion effect for oil pipelines in a high-temperature, high-pressure, and high-sulfuric acid environment, and has good application prospects.

[0086] When the inhibitor concentration exceeds a critical value, the hydrophobic effect of the long-chain alkyl groups causes the molecules to self-aggregate into micelles, resulting in a decrease in the number of free, effectively adsorbed molecules in the solution and, in turn, weakening the ability to form a uniform film on the metal surface. The ethyl carboxylate groups at the end of the alkyl chains are pH-responsive and hydrolyze to carboxylate groups in acidic environments, enhancing adsorption. However, at high concentrations, the hydrolysis rate of the carboxylate groups may exceed the dynamic equilibrium required for adsorption on the metal surface. At inhibitor concentrations of 0.2 and 0.3 mol / L, the diquaternary ammonium salt structure of the inhibitor self-aggregates due to the hydrophobic effect of the long-chain alkyl groups, disrupting the dense adsorption film on the metal surface. Furthermore, high concentrations intensify coordination competition with corrosive ions, leading to film defects and reducing the inhibition efficiency below the optimal concentration of 0.1 mol / L.

[0087] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for preparing a dual-functionalized quaternary ammonium salt ion corrosion inhibitor, characterized in that: The steps include: S1. Synthesis of thioether intermediates; ； S2. Synthesis of dicationic precursors; ； S3. Anion exchange and pH-responsive modification; 。 2. The preparation method according to claim 1, characterized in that The synthesis of the thioether intermediate specifically includes: S11. Add 4-chloromethylbenzotriazole, dodecanethiol, and anhydrous ethanol to a container and stir until completely dissolved; S12. Potassium carbonate was added in batches and the reaction was kept warm; S13. After the reaction is completed, cool to room temperature and filter to remove the generated potassium chloride precipitate; S14. The filtrate was distilled under reduced pressure to remove ethanol and obtain a light yellow oily intermediate BTA-SC. 12 H 25 .

3. The preparation method according to claim 2, characterized in that The molar ratio of the 4-chloromethylbenzotriazole and dodecanethiol is (1-3): (1-3).

4. The preparation method according to claim 3, characterized in that The synthesis of the dicationic precursor specifically includes: S21. BTA-SC 12 H 25 and acetonitrile were added into the reaction vessel and stirred to dissolve; S22. Add 1,4-dibromobutane and heat the reaction; S23. After the reaction was completed, the mixture was cooled to room temperature and acetonitrile was removed by distillation under reduced pressure to obtain a white solid intermediate [(BTA-SC 12 H 25 -N + (CH3)2)2-(CH2)4] 2+ Br2 - .

5. The preparation method according to claim 4, characterized in that The specific conditions for the heat preservation reaction in S12 are: maintaining the reaction temperature at 55-65° C. and reflux stirring for 5-10 hours; the specific conditions for the temperature increase reaction in S22 are: increasing the temperature to 75-85° C. and reflux stirring for 20-30 hours.

6. The preparation method according to claim 5, characterized in that The BTA-SC 12 H 25 The molar ratio of 1,4-dibromobutane to 1,4-dibromobutane is (1-3):

1.

7. The preparation method according to claim 6, characterized in that The anion exchange and pH response modification specifically include: S31. [(BTA-SC 12 H 25 -N + (CH3)2)2-(CH2)4] 2+ Br2 - Dissolve in deionized water, add NaBTA aqueous solution, stir at room temperature to generate white precipitate, filter and wash to obtain [(BTA-SC 12 H 25 -N + (CH3)2)2-(CH2)4] 2+ (BTA - )2; S32. The product of S31 was dissolved in acetonitrile, ethyl acrylate and concentrated sulfuric acid were added for catalytic esterification, and the mixture was stirred under reflux; S33. After the reaction is completed, acetonitrile is removed by distillation under reduced pressure, and the residue is washed with anhydrous ether and dried in vacuum to obtain the target product.

8. The preparation method according to claim 7, characterized in that [(BTA-SC 12 H 25 -N + (CH3)2)2-(CH2)4] 2+ Br2 - The molar ratio of HCl and NaBTA is 1:(1-3).

9. A dual-functionalized quaternary ammonium salt ion corrosion inhibitor, characterized in that: The method is obtained by the preparation method according to any one of claims 1 to 8.

10. Use of the dual-functionalized quaternary ammonium salt ion corrosion inhibitor according to claim 9 in the anti-corrosion of petroleum pipelines.

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