Ionic liquid corrosion inhibitor and preparation method and application thereof

Abstract

The present application relates to a kind of ionic liquid corrosion inhibitor and preparation method and application, the ionic liquid corrosion inhibitor is composed of N, N-alkyl secondary ammonium cation and dodecyl benzene sulfonic acid anion, with the general structure shown in the following figure.The ionic liquid corrosion inhibitor is added to mineral oil as oil-soluble corrosion inhibitor, can prevent the corrosion of steel material in hot and humid atmosphere environment.The ionic liquid corrosion inhibitor has the characteristics of good oil solubility, stable micellar structure and high corrosion inhibition efficiency, and can be used as a key rust-preventing component in new anti-rust oil.The oil-soluble surface-active ionic liquid corrosion inhibitor based on N, N-alkyl-sec-ammonium ion and dodecyl benzene sulfonic acid ion proposed in the present application has the characteristics of green, non-toxic, good oil solubility and high corrosion inhibition efficiency.

Description

Technical Field

[0001] This invention belongs to the field of metal corrosion inhibition technology, specifically relating to an ionic liquid corrosion inhibitor, its preparation method, and its application. Background Technology

[0002] Under complex atmospheric conditions, storage and transportation equipment readily adsorbs hygroscopic salt particles (such as NaCl and MgCl2). Even under low humidity (<40%) conditions, micron-sized corrosive liquid films can still form through capillary adsorption and condensation. Furthermore, as instruments and equipment become increasingly integrated and miniaturized, even ng-level corrosion weight loss can lead to malfunctions such as instrument failure.

[0003] Traditional rust-preventive oil systems rely on physical barriers to block corrosive media. However, under the combined effects of multiple factors such as humidity, heat, salt deposition, and the intrusion of polluting gases, the protective efficacy of the oil film is prone to decline. Oil-soluble corrosion inhibitors, as a core component of rust-preventive oils, have a microscopic structure that is closely related to the macroscopic properties of the oil. Surface-active ionic liquids (SAILs), due to their tunable structure and high corrosion inhibition properties, have been widely used in the research of aqueous phase corrosion inhibitors in recent years. However, the amphiphilic nature of SAILs also provides potential for their application in the oil phase, which is of great significance for the development of high-performance rust-preventive oils. Summary of the Invention

[0004] In view of this, the present invention provides an ionic liquid corrosion inhibitor, its preparation method and application, which has the characteristics of being green and non-toxic, having good oil solubility and high corrosion inhibition efficiency.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] In a first aspect, the present invention provides an ionic liquid corrosion inhibitor comprising an N,N-dialkyl secondary ammonium dodecylbenzenesulfonic acid ionic liquid, the general structural formula of which is shown in I:

[0007]

[0008] I

[0009] In structural formula I, both m and n are 3-17.

[0010] Secondly, the present invention provides a method for preparing the aforementioned ionic liquid corrosion inhibitor, comprising the following steps:

[0011] S1. Mix long-chain alkyl primary amines and haloalkanes to obtain a solution of bi-long-chain secondary amine hydrohalides, wherein the long-chain alkyl primary amines contain 4-18 carbon atoms and the haloalkanes are n-bromobutane.

[0012] S2. The solution of the double long-chain secondary amine hydrohalate, sodium dodecylbenzenesulfonate, water and dichloromethane are mixed and purified to obtain an ionic liquid corrosion inhibitor.

[0013] Preferably, the molar ratio of long-chain alkyl primary amine, haloalkanes, and sodium dodecylbenzenesulfonate is 1:1:1.

[0014] Preferably, in step S1, a long-chain alkyl primary amine, a haloalkane, and a solvent are mixed to obtain a bis-long-chain secondary amine hydrohalide solution, wherein the solvent includes at least one of tetrahydrofuran, acetonitrile, and dimethylformamide.

[0015] Preferably, 4 mL of solvent is added for every 5 mmol of long-chain alkyl primary amine.

[0016] Preferably, in step S1, the temperature for the mixed reaction of long-chain alkyl primary amines and haloalkanes is 60-80°C, and the reaction time is 4-5 hours.

[0017] Preferably, in step S2, the amount of water used is one-quarter of the solvent volume.

[0018] Preferably, in step S2, the amount of dichloromethane added is: 10 mL of dichloromethane for every 5 mmol of sodium dodecylbenzenesulfonate.

[0019] Thirdly, the present invention provides a rust-preventive oil, comprising the aforementioned ionic liquid corrosion inhibitor, or the ionic liquid corrosion inhibitor prepared by the aforementioned preparation method.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] (1) The oil-soluble surface-active ionic liquid corrosion inhibitor proposed in this invention based on N,N-dialkyl-secondary ammonium ions and dodecylbenzenesulfonate ions has the characteristics of being green and non-toxic, having good oil solubility and high corrosion inhibition efficiency.

[0022] (2) The synthesis method proposed in this invention has simple steps, mild reaction conditions, convenient operation, simple equipment, readily available raw materials, and no environmental pollutants generated. Attached Figure Description

[0023] Figure 1 The infrared spectra of the ionic liquid corrosion inhibitors provided in Examples 1-5 of this invention are shown below.

[0024] Figure 2 The contact angle diagram of the anti-rust oil film prepared with the ionic liquid corrosion inhibitor provided in Examples 1-5 of the present invention with water droplets on the surface of a carbon steel disc;

[0025] Figure 3Electrochemical impedance spectroscopy results of applying an anti-rust oil film prepared with the ionic liquid corrosion inhibitor provided in Examples 1-5 of this invention to a stacked electrode sensor;

[0026] Figure 4 The microscopic SEM images show the rust-preventive oil film prepared with the ionic liquid corrosion inhibitor provided in Examples 1-5 of this invention after being applied to carbon steel discs and subjected to a 24-hour wet hot salt water corrosion test. Detailed Implementation

[0027] The present invention will now be described in further detail with reference to specific embodiments, so that those skilled in the art can more clearly understand the present invention.

[0028] Traditional rust-preventive oil systems rely on physical barriers to block corrosive media. However, under the combined effects of multiple factors such as humidity, heat, salt deposition, and the intrusion of polluting gases, the protective efficacy of the oil film is prone to decline. Oil-soluble corrosion inhibitors, as a core component of rust-preventive oils, have a microscopic structure that is closely related to the macroscopic properties of the oil. Surface-active ionic liquids (SAILs), due to their tunable structure and high corrosion inhibition properties, have been widely used in the research of aqueous phase corrosion inhibitors in recent years. However, the amphiphilic nature of SAILs also provides potential for their application in the oil phase, which is of great significance for the development of high-performance rust-preventive oils.

[0029] To address the aforementioned technical problems, this invention provides an ionic liquid corrosion inhibitor comprising an N,N-dialkyl secondary ammonium dodecylbenzenesulfonic acid ionic liquid, the general structural formula of which is shown in Figure I:

[0030]

[0031] I

[0032] In structural formula I, both m and n are 3-17.

[0033] Secondly, the present invention provides a method for preparing the aforementioned ionic liquid corrosion inhibitor, comprising the following steps:

[0034] S1. Mix long-chain alkyl primary amines and haloalkanes to obtain a solution of di-long-chain secondary amine hydrohalide, wherein the long-chain alkyl primary amines contain 4-18 carbon atoms and the haloalkanes are n-bromobutane.

[0035] S2. The solution of the double long-chain secondary amine hydrohalate, sodium dodecylbenzenesulfonate, water and dichloromethane are mixed and purified to obtain an ionic liquid corrosion inhibitor.

[0036] It should be noted that the process formula in step S1 is as follows:

[0037]

[0038] It should be noted that the present invention mainly uses C8~C18 bromoalkane, C8~C18 primary amine and sodium dodecylbenzenesulfonate as raw materials.

[0039] Furthermore, the molar ratio of long-chain alkyl primary amine, haloalkanes, and sodium dodecylbenzenesulfonate is 1:1:1.

[0040] Further, in step S1, the long-chain alkyl primary amine, the haloalkane, and the solvent are mixed to obtain a bis-long-chain secondary amine hydrohalide solution, wherein the solvent includes at least one of tetrahydrofuran, acetonitrile, and dimethylformamide.

[0041] It should be noted that the first step of the synthesis method, alkylation, is an SN2 nucleophilic substitution reaction, so the solvent should be a strongly polar aprotic solvent.

[0042] Further, 4 mL of solvent was added for every 5 mmol of long-chain alkyl primary amine.

[0043] Furthermore, in step S1, the long-chain alkyl primary amine and the haloalkane are reacted at a temperature of 60-80°C for 4-5 hours. The haloalkane reactant should be slowly added dropwise to the long-chain alkyl primary amine through a constant-pressure dropping funnel.

[0044] Furthermore, in step S2, the amount of water used is one-quarter of the solvent volume.

[0045] Further, in step S2, the amount of dichloromethane added is: 10 mL of dichloromethane for every 5 mmol of sodium dodecylbenzenesulfonate.

[0046] In some embodiments, in step S2, the specific reaction steps are as follows: After the first alkylation reaction is completed, sodium dodecylbenzenesulfonate and water are added to the reaction system in equimolar amounts as in the first reaction, with the amount of water added being one-quarter of the solvent in the first reaction; then stirring and reflux are continued for a certain period of time until the solid is completely dissolved, and heating is stopped; after the system is cooled, dichloromethane is added, with the amount added being 10 mL of dichloromethane for every 5 mmol of reactant; then the system is washed three times with 10 mL of water, and the system is dried with anhydrous magnesium sulfate; the solid is removed by centrifugation at 8000~10000 rpm for 1~2 min, and the solvent in the clear liquid obtained is evaporated by rotary evaporator at 50°C in a water bath to obtain the crude product; the crude product is dissolved successively in n-pentane and ethanol (or methanol), refrigerated (at about 4°C) and allowed to stand, the solid is precipitated, and then the solid is removed by centrifugation at 8000~10000 rpm for 1~2 min, and the solvent in the clear liquid obtained is evaporated by rotary evaporator at 50°C in a water bath to finally obtain the product ionic liquid.

[0047] It should be noted that the process formula in step S2 is as follows:

[0048]

[0049] Example 1

[0050] This embodiment provides a preparation process for N-butyl-N-octadecylammonium·dodecylbenzenesulfonic acid ionic liquid:

[0051] Reagents: n-Butane bromide, octadecylamine, sodium dodecylbenzenesulfonate, tetrahydrofuran, dichloromethane, n-pentane, anhydrous methanol, and deionized water.

[0052] Preparation process: Butane bromide (5 mmol), octadecylamine (5 mmol), and THF (4 mL) were added to a 100 mL round-bottom flask and refluxed in an oil bath at 70 °C for 5 h. Then, SDBS (5 mmol) and H₂O (1 mL) were added, and refluxed for another 1 h. After cooling the reaction system to room temperature, CH₂Cl₂ (10 mL) was added and stirred until homogeneous. The organic phase was washed three times with deionized water and dried with anhydrous magnesium sulfate (2 g). The supernatant was collected by centrifugation (8000 rpm, 3 min), and the solvent was evaporated using a rotary evaporator to obtain the crude N-butyl-N-octadecylammonium·dodecylbenzenesulfonic acid ionic liquid. The crude product was thoroughly dispersed in n-pentane (10 mL), refrigerated at 4 °C for 30 min, and then centrifuged (8000 rpm, 1 min) to collect the supernatant. Evaporate n-pentane using a rotary evaporator, then add methanol (3 mL) and mix thoroughly. Refrigerate at 4°C for 30 min, then centrifuge (8000 rpm, 1 min) to collect the supernatant. Finally, evaporate methanol using a rotary evaporator to obtain N-butyl-N-octadecylammonium dodecylbenzenesulfonic acid ionic liquid.

[0053] Example 2

[0054] This embodiment provides a preparation process for N-butyl-N-hexadecylammonium·dodecylbenzenesulfonic acid ionic liquid:

[0055] Reagents: n-Butane bromide, hexadecylamine, sodium dodecylbenzenesulfonate, acetonitrile, dichloromethane, n-pentane, anhydrous ethanol, and deionized water.

[0056] Preparation process: Compared with Example 1, the first step of the alkylation reaction used acetonitrile as solvent, with a volume of 4 mL; the amount of hexadecylamine was 5 mmol; anhydrous ethanol was used instead of anhydrous methanol in the subsequent step; the amount of other reagents, reaction steps and reaction time were the same as in Example 1.

[0057] Example 3

[0058] This embodiment provides a preparation process for N-butyl-N-hexadecylammonium·dodecylbenzenesulfonic acid ionic liquid:

[0059] Reagents: n-Butane bromide, dodecylamine, sodium dodecylbenzenesulfonate, tetrahydrofuran, dichloromethane, n-pentane, anhydrous methanol, and deionized water.

[0060] Preparation process: The amount of dodecylamine used was 5 mmol, and the amounts of other reagents, reaction steps and reaction time were the same as in Example 1.

[0061] Example 4

[0062] This embodiment provides a preparation process for N-butyl-N-hexadecylammonium·dodecylbenzenesulfonic acid ionic liquid:

[0063] Reagents: n-Butane bromide, n-Octylamine, sodium dodecylbenzenesulfonate, tetrahydrofuran, dichloromethane, n-pentane, anhydrous methanol, and deionized water.

[0064] Preparation process: The amount of n-octylamine used was 5 mmol, and the amount of other reagents, reaction steps and reaction time were the same as in Example 1.

[0065] Example 5

[0066] This embodiment provides a preparation process for N-butyl-N-hexadecylammonium·dodecylbenzenesulfonic acid ionic liquid:

[0067] Reagents: n-Butane bromide, n-Butylamine, sodium dodecylbenzenesulfonate, tetrahydrofuran, dichloromethane, n-Pentane, anhydrous methanol, and deionized water.

[0068] Preparation process: The amount of n-butylamine used was 5 mmol, and the amount of other reagents, reaction steps and reaction time were the same as in Example 1.

[0069] The ionic liquid corrosion inhibitors obtained in Examples 1-5 were named C4C. n NSPD (n = 4, 8, 12, 16, 18).

[0070] Performance Tests and Results

[0071] (1) The infrared spectra of the ionic liquid corrosion inhibitors obtained in Examples 1-5 are as follows: Figure 1 As shown: 3200~2200cm 1 The broad band between 3000 and 2800 cm⁻¹ represents the stretching vibration peak of secondary ammonium ions. 1 The sharp peaks between these peaks represent the asymmetric and symmetric stretching vibrations of alkyl groups; 1600 cm⁻¹ 1 The nearby peak is the C=C stretching vibration peak of the benzene ring; 1465 cm⁻¹ 1 The left and right sides show the C–H shear vibration peaks; 1300~1000cm 1 These are the asymmetric and symmetric stretching vibration peaks of the sulfonate ion, and are characteristic peaks of the sulfonate ion; 830 cm⁻¹ 1 This is the out-of-plane bending vibration peak of the C–H group in the para-substituted benzene ring, a characteristic peak of para-substituted benzene rings; 600~650 cm⁻¹ 1 The peaks between these peaks are in-plane bending vibration peaks of the sulfonate ion.

[0072] (2) The contact angle between the rust-preventive oil film prepared with the ionic liquid corrosion inhibitor obtained in Examples 1-5 and water droplets on the surface of the carbon steel disc is as follows: Figure 2 As shown, (a) represents C4C4NSPD, (b) represents C4C8NSPD, and (c) represents C4C... 12 NSPD, (d) represents C4C 16 NSPD and (e)C4C 18 NSPD. It can be seen that the critical micelle concentration (CMC) of C4C4 NSPD is 5 wt%, the CMC of C4C8 NSPD is 1 wt%, and C4C... 12 NSPD, C4C 16 NSPD and C4C 18 The CMC of NSPD is 0.5 wt%, and the CMC decreases with the length of the carbon chain.

[0073] (3) The electrochemical impedance spectroscopy results of the anti-rust oil film prepared with the ionic liquid corrosion inhibitors obtained in Examples 1-5 applied to the stacked electrode sensor are as follows: Figure 3 As shown, (a) is the Nyquist plot and (b) is the Bode plot. The results indicate that the corrosion inhibition performance gradually increases with the growth of the nonpolar terminal carbon chain of the cation.

[0074] (4) The microscopic SEM images of the rust-preventive oil film prepared with the ionic liquid corrosion inhibitors obtained in Examples 1-5 after being coated on carbon steel discs and subjected to a 24-hour wet hot salt water corrosion test are shown below. Figure 4 As shown in the figure. (a) represents the control group, (b) represents C4C4NSPD, (c) represents C4C8NSPD, and (d) represents C4C... 12 NSPD, (e) indicates C4C 16 NSPD, (f)C4C 18 NSPD. The results showed that the actual corrosion inhibition effect was consistent with the electrochemical impedance spectroscopy results, and C4C 18 NSPD has the best corrosion inhibition effect.

[0075] Unless otherwise specified, all raw materials used in this invention are existing substances that can be purchased directly from the market.

[0076] The above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An ionic liquid corrosion inhibitor, characterized in that, The ionic liquid corrosion inhibitor is an oil-soluble corrosion inhibitor, comprising an N,N-dialkyl secondary ammonium dodecylbenzene sulfonic acid ionic liquid, the general structural formula of which is shown in Figure I: I； In structural formula I, both m and n are 3-17.

2. The method for preparing the ionic liquid corrosion inhibitor according to claim 1, characterized in that, Includes the following steps: S1. Mix long-chain alkyl primary amines and haloalkanes to obtain a solution of di-long-chain secondary amine hydrohalide, wherein the long-chain alkyl primary amines contain 4-18 carbon atoms and the haloalkanes are n-bromobutane. S2. The solution of the double long-chain secondary amine hydrohalate, sodium dodecylbenzenesulfonate, water and dichloromethane are mixed and purified to obtain an ionic liquid corrosion inhibitor.

3. The preparation method according to claim 2, characterized in that, The molar ratio of long-chain alkyl primary amine, haloalkanes, and sodium dodecylbenzenesulfonate is 1:1:

1.

4. The preparation method according to claim 2, characterized in that, In step S1, a long-chain alkyl primary amine, a haloalkane, and a solvent are mixed to obtain a bis-long-chain secondary amine hydrohalide solution, wherein the solvent includes at least one of tetrahydrofuran, acetonitrile, and dimethylformamide.

5. The preparation method according to claim 4, characterized in that, Add 4 mL of solvent for every 5 mmol of long-chain alkyl primary amine.

6. The preparation method according to claim 2, characterized in that, In step S1, the long-chain alkyl primary amine and haloalkane are reacted at a temperature of 60-80°C for 4-5 hours.

7. The preparation method according to claim 4, characterized in that, In step S2, the amount of water used is one-quarter of the solvent volume.

8. The preparation method according to claim 4, characterized in that, In step S2, the amount of dichloromethane added is: 10 mL of dichloromethane for every 5 mmol of sodium dodecylbenzenesulfonate.

9. A rust-preventive oil, characterized in that, Includes the ionic liquid corrosion inhibitor according to claim 1, or the ionic liquid corrosion inhibitor prepared by the preparation method according to any one of claims 2-8.

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