Application of carbon steel corrosion inhibitor based on combination of physical adsorption, chemical adsorption and hydrophobic barrier

Abstract

The invention discloses application of a carbon steel corrosion inhibitor based on combination of physical adsorption, chemical adsorption and hydrophobic barrier, and relates to the technical field of metal corrosion inhibition. The technical problem that a corrosion inhibitor in the prior art is low in corrosion inhibition efficiency in a high-temperature strong-acid environment is solved. The preparation method of the carbon steel corrosion inhibitor comprises the following steps: firstly, ultrasonically dissolving 4-aminopyridine to obtain a solution I; then, dropwise adding an isopropanol solution of 2, 3-epoxypropyltrimethylammonium chloride into the solution I according to a molar ratio of 1: 1, removing a solvent through a rotary evaporation method, washing with ethanol, centrifuging to obtain quaternized 4-aminopyridine, and drying the quaternized 4-aminopyridine; and finally, the dried quaternized 4-aminopyridine and bromododecane are added into acetonitrile for a reaction, diethyl ether is dropwise added into obtained reaction liquid for precipitation, and the quaternized 4-aminopyridine-bromododecane carbon steel corrosion inhibitor is obtained after drying. The prepared carbon steel corrosion inhibitor is high in corrosion inhibition efficiency in a high-temperature and strong-acid environment.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metal corrosion inhibition, and particularly relates to application of a carbon steel corrosion inhibitor based on physical adsorption, chemical adsorption and hydrophobic barrier combination. BACKGROUND

[0002] Carbon steel is prone to uniform corrosion and localized corrosion in the acidic environment (especially hydrochloric acid system) in the petroleum and chemical fields, resulting in shortened equipment life and interrupted production, and thus high-efficiency corrosion inhibitors are in urgent need.

[0003] The existing corrosion inhibitors include organic complex corrosion inhibitors, nano material-based corrosion inhibitors and polysaccharide corrosion inhibitors, and the organic complex corrosion inhibitors are more commonly used in high-temperature and strong-acid environments in oil exploitation.

[0004] Application No. 202010275310.X discloses a multi-component complex corrosion inhibitor for magnesium and its alloys and application thereof, and each component is included in a weight percentage of 5% to 40% organic phosphonic acid corrosion inhibitor and 20% to 70% interpenetrating green corrosion inhibitor; the interpenetrating green corrosion inhibitor is a composition combined by at least two green corrosion inhibitors; the amount of the multi-component complex corrosion inhibitor is 0.01 g / L to 0.20 g / L; and the application method is to first add the interpenetrating green corrosion inhibitor according to the components into a solvent and uniformly mix, then add the organic phosphonic acid corrosion inhibitor for further mixing to obtain a corrosion inhibitor solution. Application No. 201410061809.5 discloses a complex carbon dioxide corrosion inhibitor, in which an organic compound is compounded with one or two of thiocyanate and sodium dodecyl sulfonate, and the mass ratio of each substance is 20% to 30% of the organic compound, 3% to 7% of thiocyanate and 5% to 10% of sodium dodecyl sulfonate; the rest is water; and the organic compound is an imidazoline corrosion inhibitor or derivative thereof, a fatty amine or derivative thereof, or a rosin amine. Application No. 201711170389.4 discloses a preparation method of a quaternary ammonium salt corrosion inhibitor, which is obtained by combining 1 to 1.2 molar amount of bromohexanoic acid compound with 1 to 1.2 molar amount of triethylamine after the bromohexanoic acid compound is reacted in an organic solution under the action of a condensation activator, and the bromohexanoic acid compound is synthesized by an amination reaction.

[0005] The existing corrosion inhibitors have the technical problem of low corrosion inhibition efficiency in a high-temperature 303K to 363K and strong-acid 1M to 15% HCl environment, and low applicability.

[0006] Therefore, the existing technology needs to be further improved. SUMMARY

[0007] The purpose of this invention is to provide an application of a carbon steel corrosion inhibitor based on a combination of physical adsorption, chemical adsorption, and hydrophobic barrier. It uses 4-aminopyridine as the parent material and obtains quaternized 4-aminopyridine-bromododecane through a two-step functionalization modification. The quaternary ammonium cation, pyridine ring, and dodecyl long-chain structure contained in this product serve as the physical adsorption center, chemical adsorption center, and hydrophobic barrier, respectively. The combination of these three can be used as a carbon steel corrosion inhibitor in high-temperature and strong acid environments.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: an application of a carbon steel corrosion inhibitor based on a combination of physical adsorption, chemical adsorption, and hydrophobic barrier, wherein the preparation method of the carbon steel corrosion inhibitor includes the following steps in sequence: a. dissolving 4-aminopyridine by ultrasonication to obtain solution one.

[0009] b. Add a solution of 2,3-epoxypropyltrimethylammonium chloride in isopropanol to solution one at a molar ratio of 1:1, react at 85-95℃ for 9-11 hours, remove the solvent by rotary evaporation, wash with ethanol, and centrifuge to obtain quaternized 4-aminopyridine, and then dry it.

[0010] c. Add the dried quaternized 4-aminopyridine and bromododecane to acetonitrile and react at 80-100℃ for 20-25 hours. Add diethyl ether dropwise to the resulting reaction solution to precipitate the precipitate and dry it to obtain the quaternized 4-aminopyridine-bromododecane carbon steel corrosion inhibitor.

[0011] The application includes: pretreating carbon steel and immersing the pretreated carbon steel in a carbon steel corrosion inhibitor at 15% HCl and 363K. The quaternary ammonium cation, pyridine ring, and dodecyl long-chain structure contained in the carbon steel corrosion inhibitor jointly construct a triple synergistic mechanism of "physical adsorption + chemical adsorption + hydrophobic barrier", and the corrosion inhibition efficiency is 99% within 4 hours.

[0012] The technical effects directly brought about by the above technical solution are as follows: The present invention uses 4-aminopyridine as the parent material and prepares quaternized 4-aminopyridine-bromododecane through a two-step reaction method of ring opening and substitution. Quaternized 4-aminopyridine-bromododecane contains a pyridine ring, a quaternary ammonium salt and a dodecyl long-chain structure. The combination of the three can solve the technical problem of low corrosion inhibition efficiency of corrosion inhibitors in the prior art under high temperature and strong acid environment.

[0013] In the above-mentioned application of a carbon steel corrosion inhibitor based on a combination of physical adsorption, chemical adsorption, and hydrophobic barrier, in step a, 4-aminopyridine is ultrasonically dissolved in isopropanol.

[0014] In the application of the above-mentioned carbon steel corrosion inhibitor based on a combination of physical adsorption, chemical adsorption, and hydrophobic barrier, in step a, the ultrasonic power is 700-800W and the ultrasonic time is 3-8min.

[0015] In the application of the above-mentioned carbon steel corrosion inhibitor based on a combination of physical adsorption, chemical adsorption, and hydrophobic barrier, in step b, the drying temperature is 55-65℃, the centrifugation speed is 8000 r / min, and the centrifugation time is 5min.

[0016] In the application of the above-mentioned carbon steel corrosion inhibitor based on a combination of physical adsorption, chemical adsorption, and hydrophobic barrier, in step b, the rotary evaporation time is 50-70 minutes and the rotation speed is 50 times / minute.

[0017] In the above-mentioned application of a carbon steel corrosion inhibitor based on a combination of physical adsorption, chemical adsorption, and hydrophobic barrier, in step c, the molar ratio of the dried quaternized 4-aminopyridine to bromododecane is 1:2.

[0018] The above-mentioned application of a carbon steel corrosion inhibitor based on a combination of physical adsorption, chemical adsorption, and hydrophobic barrier involves N80 steel sheets, which are cleaned by adding acetone and ethanol.

[0019] The reaction mechanism of this invention is as follows.

[0020] .

[0021] Compared with the prior art, the present invention brings the following beneficial technical effects: (1) The quaternized 4-aminopyridine-bromododecane prepared by the present invention contains "pyridine ring (chemical adsorption) + quaternary ammonium salt (physical adsorption) + dodecyl long chain structure (hydrophobic barrier)", which can improve its corrosion inhibition performance in high temperature and strong acid environment without the need to add other compounding agents.

[0022] (2) The quaternized 4-aminopyridine-bromododecane corrosion inhibitor prepared by the present invention is particularly suitable for conditions of 15% HCl and 363K. Under these extreme conditions, the corrosion inhibition efficiency reaches 99%, and the performance is stable within 4 hours, which can meet the long-cycle industrial requirements.

[0023] (3) The raw materials of this invention are easy to obtain, the method is simple to operate, the reaction conditions are mild, and quaternized 4-aminopyridine-bromododecane can be prepared without complicated equipment, which is conducive to industrial promotion.

[0024] (4) The quaternized 4-aminopyridine-bromododecane prepared by the present invention can be adapted to the existing petroleum and chemical acid processes without the need for additional equipment modification, and has strong compatibility. Attached Figure Description

[0025] Figure 1 The infrared spectrum of quaternized 4-aminopyridine-bromododecane.

[0026] Figure 2The thermogravimetric curve of quaternized 4-aminopyridine-bromododecane.

[0027] Figure 3 The corrosion rate diagrams are for different concentrations of quaternized 4-aminopyridine-bromododecane under four corrosion conditions.

[0028] Figure 4 Electrochemical impedance values ​​of quaternized 4-aminopyridine-bromododecane at different concentrations under four corrosion conditions. Detailed Implementation

[0029] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings.

[0030] All the raw materials mentioned in this invention can be purchased through commercial channels.

[0031] The technical concept of this invention is as follows: taking the low corrosion inhibition efficiency of corrosion inhibitors under high temperature and strong acid environment as a starting point, a quaternized 4-aminopyridine-bromododecane with a triple mechanism of chemical adsorption, physical adsorption and hydrophobicity is prepared by a two-step reaction method of ring opening and substitution. After experimental testing, its corrosion inhibition efficiency still exceeds 99% under extreme conditions of 15% HCl and 363K.

[0032] Example 1: This invention discloses a method for preparing a carbon steel corrosion inhibitor based on a combination of physical adsorption, chemical adsorption, and hydrophobic barrier, specifically comprising the following steps: Step 1: Dissolving 4-aminopyridine by ultrasonication to obtain Solution 1. Specifically, 1 g of 4-aminopyridine (0.01 mol) is ultrasonically dissolved in 20 mL of isopropanol at a molar ratio of 1:1, with an ultrasonic power of 800 W and an ultrasonic time of 8 min.

[0033] Step 2: Add 10 mL of isopropanol solution containing 1.52 g of 2,3-epoxypropyltrimethylammonium chloride (0.01 mol) to Solution 1 according to a molar ratio of 1:1. React at 90℃ for 10 h. The solution changes from colorless and transparent to brown. Remove isopropanol by rotary evaporation, wash the crude product obtained by the reaction with ethanol, and centrifuge to obtain quaternized 4-aminopyridine. Dry it at 60 ℃ for 70 min by rotary evaporation at a rotation speed of 50 times / min.

[0034] Step 3: Add the dried quaternized 4-aminopyridine and bromododecane to acetonitrile at a molar ratio of 1:2, react at 90℃ for 24 hours, add diethyl ether dropwise to the resulting reaction solution to precipitate three times, and dry at 60℃ to obtain the quaternized 4-aminopyridine-bromododecane carbon steel corrosion inhibitor.

[0035] The quaternized 4-aminopyridine-bromododecane prepared in this example was structurally characterized, and the conclusions were as follows:Figure 1 As shown, infrared spectroscopy analysis confirmed the successful synthesis of the target product. Specifically, the absorption peaks at 2930 cm⁻¹ and 2850 cm⁻¹ are attributed to the stretching vibration of the methylene group, confirming the presence of the dodecyl long-chain structure; the absorption peak at 1478 cm⁻¹ is due to the stretching vibration of the methyl group, a typical indicator of a quaternary ammonium salt structure. Furthermore, except for the change in the characteristic peak of the amino group on 4-aminopyridine, all other characteristic absorption peaks of the pyridine ring were retained, indicating that the pyridine ring structure remained intact during the reaction.

[0036] The thermodynamic properties of the quaternized 4-aminopyridine-bromododecane prepared in this example were characterized, such as... Figure 2 As shown, the thermogravimetric analysis reveals that the product possesses good thermal stability. Its mass loss from room temperature to 100°C is mainly attributed to the evaporation of adsorbed moisture; the primary thermal decomposition process occurs at approximately 300°C. This characteristic indicates that the product can meet the thermal stability requirements of high-temperature applications and is suitable for corrosion protection under high-temperature conditions.

[0037] The relevant properties of the quaternized 4-aminopyridine-bromododecane prepared in this embodiment were tested. The specific method was as follows: To evaluate the corrosion inhibition performance of the quaternized 4-aminopyridine-bromododecane prepared in this embodiment, a combination of weight loss method and electrochemical testing was used for systematic characterization. The test steps were as follows: First, the N80 steel sample was ultrasonically cleaned sequentially with acetone and anhydrous ethanol, and its initial mass was accurately weighed after drying. Then, the treated sample was immersed in a corrosive medium containing different concentrations of the quaternary ammonium salt product. To comprehensively evaluate its applicability under harsh conditions such as high acidity and high temperature, four corrosion environments were specifically set up: 1 M HCl solution (303 K and 363 K) and 15% HCl solution (303 K and 363 K). The corrosion behavior of the sample under different conditions was analyzed to scientifically characterize the performance of the corrosion inhibitor. The corrosion rates of quaternized 4-aminopyridine-bromododecane under the four corrosion conditions are as follows: Figure 3 As shown, the electrochemical impedance values ​​of quaternized 4-aminopyridine-bromododecane under four corrosion conditions are as follows: Figure 4 As shown.

[0038] Example 2: This invention discloses a method for preparing a carbon steel corrosion inhibitor based on a combination of physical adsorption, chemical adsorption, and hydrophobic barrier, specifically comprising the following steps: Step 1: Dissolving 4-aminopyridine by ultrasonication to obtain Solution 1. Specifically, 1 g of 4-aminopyridine (0.01 mol) is ultrasonically dissolved in 20 mL of isopropanol at a molar ratio of 1:1, with an ultrasonic power of 700 W and an ultrasonic time of 3 min.

[0039] Step 2: Add 10 mL of isopropanol solution containing 1.52 g of 2,3-epoxypropyltrimethylammonium chloride (0.01 mol) to Solution 1 according to a molar ratio of 1:1. React at 80℃ for 9 h. The solution changes from colorless and transparent to brown. Remove isopropanol by rotary evaporation, wash the crude product obtained by the reaction with ethanol, and centrifuge to obtain quaternized 4-aminopyridine. Dry it at 60 ℃ for 50 min by rotary evaporation at a rotation speed of 50 times / min.

[0040] Step 3: Add the dried quaternized 4-aminopyridine and bromododecane to acetonitrile at a molar ratio of 1:2, react at 90℃ for 24 hours, add diethyl ether dropwise to the resulting reaction solution to precipitate three times, and dry at 60℃ to obtain the quaternized 4-aminopyridine-bromododecane carbon steel corrosion inhibitor.

[0041] The relevant properties of the quaternized 4-aminopyridine-bromododecane prepared in this embodiment were tested, and the test method was the same as in Example 1.

[0042] Comparative Example 1: Medicinal plant extracts (such as marjoram) prepared by reflux extraction were used as corrosion inhibitors for low-carbon steel in 1 M HCl. Under optimal conditions, their maximum corrosion inhibition efficiency was approximately 92%. Although this type of corrosion inhibitor is environmentally friendly, its efficiency has reached a bottleneck, and its stability and efficiency typically decrease significantly in high-temperature, high-concentration acidic media.

[0043] Comparative Example 2: Imidazoline quaternary ammonium salts and their derivatives can be synthesized through the amidation reaction of oleic acid with diethylenetriamine, followed by quaternization with benzyl chloride. These corrosion inhibitors can achieve a maximum corrosion inhibition efficiency of 98.5% in a carbon dioxide-mineralized water system at room temperature. However, imidazoline substances may undergo molecular degradation in strong acid and high-temperature environments, resulting in poor long-term stability.

[0044] Comparative Example 3: Nitrogen-doped carbon dots (N-CDs) were prepared using a hydrothermal method with aminosalicylic acid as a precursor and applied to the protection of Q235 carbon steel in 1M HCl. The maximum corrosion inhibition efficiency of this carbon dot corrosion inhibitor was between 93% and 96%. Although carbon dots are environmentally friendly and novel, their preparation cost is relatively high, and their adsorption mode on metal surfaces is relatively simple, limiting the potential for performance improvement.

[0045] A comprehensive analysis of the embodiments and comparative examples of the present invention clearly highlights the innovation and technical advantages of the present invention: (1) Performance advantages: The corrosion inhibitor of the present invention achieves a corrosion inhibition efficiency of 99%, which exceeds that of the imidazoline quaternary ammonium salt (98.5%) corrosion inhibitor in comparative example 2, and significantly surpasses the plant extract (92%) in comparative example 1 and the carbon point (93-96%) in comparative example 3. More importantly, the corrosion inhibitor of the present invention can still maintain an efficiency of over 95% under extreme conditions of high temperature (363K) and high concentration of acid (15% HCl), which is difficult for most comparative corrosion inhibitors to achieve, demonstrating its unparalleled environmental adaptability.

[0046] (2) Mechanism advantages: Compared with the comparative examples with simple structures, the corrosion inhibitor of the present invention has a unique molecular design, integrating three functional groups: pyridine nitrogen atom (chemisorption), quaternary ammonium salt center (electrostatic physical adsorption), and long alkyl chain (hydrophobic barrier), realizing the synergistic effect of multiple protection mechanisms. In contrast, the composition of comparative example 1 (plant extract) is complex and the content of effective ingredients is low; comparative example 3 (carbon dots) mainly relies on physical adsorption; the present invention achieves precise design and performance optimization at the molecular level.

[0047] (3) Overall performance: While maintaining high-efficiency protection, this invention also has excellent thermal stability (decomposition temperature of about 300℃), which makes up for the instability of Comparative Example 2 (imidazoline) under high temperature and strong acid. This invention obtains a single compound with a well-defined structure and stable performance through a clear two-step synthetic route, overcoming the industry pain point of large batch-to-batch variation and difficulty in quality control of Comparative Example 1 (plant extract).

[0048] In summary, the quaternized 4-aminopyridine-bromododecane corrosion inhibitor provided by this invention exhibits significant comprehensive advantages in terms of efficiency, stability, breadth of applicable conditions, and synergistic mechanism of action. It is a novel high-efficiency corrosion inhibitor with excellent performance and suitable for harsh working conditions.

[0049] Any parts not mentioned in this invention can be achieved by referring to existing technologies.

[0050] Those skilled in the art should recognize that the above embodiments are only used to illustrate this application and are not intended to limit this application. Any appropriate changes and variations made to the above embodiments within the essential spirit and scope of this application fall within the scope of protection claimed in this application.

Claims

1. An application of a carbon steel corrosion inhibitor based on a combination of physical adsorption, chemical adsorption, and hydrophobic barrier, characterized in that, The preparation method of the carbon steel corrosion inhibitor includes the following steps in sequence: a. Dissolve 4-aminopyridine by sonication to obtain solution one; b. Add 2,3-epoxypropyltrimethylammonium chloride in isopropanol solution to solution one at a molar ratio of 1:1, react at 85-95℃ for 9-11 h, remove solvent by rotary evaporation, wash with ethanol, centrifuge to obtain quaternized 4-aminopyridine, and dry it. c. Add the dried quaternized 4-aminopyridine and bromododecane into acetonitrile and react at 80-100℃ for 20-25h. Add diethyl ether dropwise to the resulting reaction solution to precipitate and dry it to obtain the quaternized 4-aminopyridine-bromododecane carbon steel corrosion inhibitor. The applications include: Carbon steel was pretreated and then immersed in a carbon steel corrosion inhibitor at 15% HCl and 363K. The quaternary ammonium cation, pyridine ring, and dodecyl long-chain structure contained in the carbon steel corrosion inhibitor jointly constructed a triple synergistic mechanism of "physical adsorption + chemical adsorption + hydrophobic barrier", and the corrosion inhibition efficiency was 99% within 4 hours.

2. The application of the carbon steel corrosion inhibitor based on a combination of physical adsorption, chemical adsorption, and hydrophobic barrier as described in claim 1, characterized in that: In step a, 4-aminopyridine is ultrasonically dissolved in isopropanol, and the molar ratio of 4-aminopyridine to 2,3-epoxypropyltrimethylammonium chloride is 1:

1.

3. The application of the carbon steel corrosion inhibitor based on a combination of physical adsorption, chemical adsorption, and hydrophobic barrier as described in claim 1, characterized in that: In step a, the ultrasonic power is 700-800W and the ultrasonic time is 3-8min.

4. The application of a carbon steel corrosion inhibitor based on a combination of physical adsorption, chemical adsorption, and hydrophobic barrier as described in claim 1, characterized in that: In step b, the drying temperature is 55–65°C, the centrifugation speed is 8000 r / min, and the centrifugation time is 5 min.

5. The application of a carbon steel corrosion inhibitor based on a combination of physical adsorption, chemical adsorption, and hydrophobic barrier as described in claim 1, characterized in that: In step b, the rotary evaporation time is 50–70 minutes, and the rotation speed is 50 times / minute.

6. The application of the carbon steel corrosion inhibitor based on a combination of physical adsorption, chemical adsorption, and hydrophobic barrier as described in claim 1, characterized in that: In step c, the molar ratio of the dried quaternized 4-aminopyridine to bromododecane is 1:

2.

7. The application of a carbon steel corrosion inhibitor based on a combination of physical adsorption, chemical adsorption, and hydrophobic barrier as described in claim 1, characterized in that: The carbon steel is N80 steel sheet, which is cleaned by adding acetone and ethanol.

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