A high-efficiency fatty acid amide corrosion inhibitor, its preparation method and application

Abstract

This invention provides a high-efficiency fatty acid amide corrosion inhibitor, its preparation method, and its application. The high-efficiency fatty acid amide corrosion inhibitor includes a polymeric corrosion inhibitor, which is obtained by reacting polyethyleneimine and fatty acids. The preparation method of the high-efficiency fatty acid amide corrosion inhibitor includes the following steps: mixing polyethyleneimine, fatty acids, and a catalyst, and then heating and reacting to obtain the polymeric corrosion inhibitor. This invention uses the reaction of polyethyleneimine and fatty acids to obtain a polymeric corrosion inhibitor, which has the characteristics of multiple adsorption sites, high adsorption strength, and strong film stability. It solves the technical defects of existing small molecule corrosion inhibitors, such as poor temperature and media resistance and insufficient film stability. It can effectively improve the metal corrosion protection level under harsh working conditions, and the synthesis process is simple and low in cost, which has important practical significance for the development and application of corrosion inhibitor products.

Description

Technical Field

[0001] This invention relates to the field of corrosion inhibitor technology, and in particular to a high-efficiency fatty acid amide corrosion inhibitor, its preparation method, and its application. Background Technology

[0002] Metal corrosion is widespread in industrial fields such as oil and gas extraction, petroleum refining, industrial pickling, and circulating water treatment. It not only causes huge economic losses but can also lead to serious problems such as equipment failure, safety accidents, and environmental pollution. Among various anti-corrosion measures, corrosion inhibitors have become one of the most widely used protective methods due to their convenient application, low cost, and wide applicability. Organic adsorption corrosion inhibitors, in particular, have consistently been the mainstream research and application in this field due to their highly designable molecular structure and high corrosion inhibition efficiency.

[0003] Currently, commonly used organic corrosion inhibitors in industry mainly include imidazoline, quaternary ammonium salts, fatty amines, and amides. Among them, fatty acid-based corrosion inhibitors play an important role in acidic media corrosion protection due to their wide availability of raw materials, low cost, and certain biodegradability. In existing technologies, fatty acids are usually amidated and cyclized with small-molecule polyethylenepolyamines such as diethylenetriamine and triethylenetetramine to form imidazoline corrosion inhibitors, or reacted with low-carbon fatty amines to form small-molecule amide corrosion inhibitors. These products achieve corrosion inhibition by providing lone pair electrons from nitrogen atoms in the molecule to form coordination bonds with iron atoms on the metal surface, while the long alkyl chains construct a hydrophobic barrier.

[0004] However, existing fatty acid-based corrosion inhibitors still face numerous technical bottlenecks: their small molecular structure contains only 1-3 nitrogen adsorption sites, resulting in limited binding force with metals and insufficient adsorption strength. This leads to easy damage and desorption of the adsorption film, and a significant decrease in corrosion inhibition efficiency at high temperatures, necessitating increased dosage and thus higher operating costs. Furthermore, small-molecule corrosion inhibitors often form a single-layer adsorption film on metal surfaces, exhibiting microscopic defects that allow for easy penetration by corrosive media. If combined with synergists, compatibility fluctuations can occur, failing to address the fundamental issue of insufficient adsorption strength. To overcome the shortcomings of small-molecule corrosion inhibitors, research has also been conducted on polymeric corrosion inhibitors, such as those prepared through polymerization reactions to produce polyacrylamide and polyaniline-based inhibitors. However, these products generally suffer from numerous synthesis steps, stringent reaction conditions, and high raw material costs, hindering their industrial application. Therefore, current corrosion inhibitor products are insufficient to meet the protection requirements of harsh operating conditions such as high temperature, high acidity, high mineralization, and high flow rates.

[0005] Polyethyleneimine (PEI), a water-soluble polymer rich in primary, secondary, and tertiary amine groups, possesses numerous nitrogen adsorption sites and strong molecular chain flexibility, theoretically exhibiting excellent interfacial adsorption potential. Technical solutions using PEI as a corrosion inhibitor have been reported. However, pure polyethyleneimine is excessively hydrophilic and lacks hydrophobic alkyl segments, making it difficult to form an effective hydrophobic barrier layer on metal surfaces. When used alone as a corrosion inhibitor, its shielding effect is weak, and it is easily affected by salting-out effects in high-mineralization systems. Therefore, the corrosion inhibition performance of this type of material is difficult to meet industrial requirements.

[0006] Therefore, it is necessary to provide a new technical solution to overcome the shortcomings of the existing technology. Summary of the Invention

[0007] To address the problems existing in the prior art, this invention provides a highly efficient fatty acid amide corrosion inhibitor, its preparation method, and its application. This invention uses the reaction of polyethyleneimine and fatty acids to obtain a polymer-type corrosion inhibitor, which possesses multiple adsorption sites, high adsorption strength, and strong film stability. It overcomes the technical shortcomings of existing small-molecule corrosion inhibitors, such as poor temperature and media resistance and insufficient film stability. This effectively improves the level of metal corrosion protection under harsh working conditions, and the synthesis process is simple and low-cost, making it of significant practical importance for the development and application of corrosion inhibitor products.

[0008] One object of the present invention is to provide a high-efficiency fatty acid amide corrosion inhibitor, wherein the high-efficiency fatty acid amide corrosion inhibitor includes a polymeric corrosion inhibitor;

[0009] The polymeric corrosion inhibitor is obtained by reacting polyethyleneimine and fatty acids.

[0010] Furthermore, the polyethyleneimine is selected from one or more of branched polyethyleneimine or hyperbranched polyethyleneimine.

[0011] Furthermore, the fatty acid has ≥8 carbon atoms.

[0012] Furthermore, the high-efficiency fatty acid amide corrosion inhibitor also includes a small molecule corrosion inhibitor, which is obtained by reacting a small molecule amine with a fatty acid.

[0013] Furthermore, the small molecule amine is selected from one or more of ethylene amine and alcohol amine.

[0014] Another object of the present invention is to provide a method for preparing the above-mentioned high-efficiency fatty acid amide corrosion inhibitor, the method comprising the following steps:

[0015] Polyethyleneimine, fatty acids, and a catalyst are mixed and heated to react, yielding a polymer-type corrosion inhibitor.

[0016] Furthermore, the temperature of the heating reaction is 50-100℃.

[0017] Furthermore, the mass ratio of polyethyleneimine to fatty acid is (0.1-0.5):1.

[0018] Furthermore, it also includes:

[0019] Small molecule amines and fatty acids are mixed and heated to react, yielding a small molecule corrosion inhibitor.

[0020] Furthermore, the molar ratio of the small molecule amine to the fatty acid is 1:(1-3).

[0021] The present invention has the following beneficial effects:

[0022] This invention discloses a highly efficient fatty acid amide corrosion inhibitor. The polymer-type corrosion inhibitor is obtained through an amidation reaction between polyethyleneimine and fatty acids. The preparation process of this polymer-type corrosion inhibitor is simple, with low energy consumption, achieving a lower overall cost and making it suitable for industrial production. Furthermore, the polymer-type corrosion inhibitor prepared by this invention, with its higher density of amino active sites and polymeric network framework structure, can form a more robust and dense adsorption protective film on the metal surface, exhibiting a stronger shielding effect against media such as water and corrosive molecules. It achieves higher corrosion inhibition efficiency even at lower addition concentrations. Simultaneously, the multi-point adsorption and molecular chain entanglement characteristics of this polymeric corrosion inhibitor significantly improve its stability, maintaining a stable and long-lasting corrosion inhibition effect in different environments, demonstrating excellent long-term corrosion inhibition reliability.

[0023] In addition, this invention also combines polymer-type corrosion inhibitors with small-molecule corrosion inhibitors, which work synergistically. By constructing a continuous adsorption framework with polymers and filling the gaps between the film layers and the high-energy active sites of the metal with small molecules, the comprehensive performance of the corrosion-inhibiting film, such as temperature resistance, strength, and corrosion resistance, is improved simultaneously. This not only achieves high corrosion inhibition efficiency but also helps to further reduce the cost of use. Detailed Implementation

[0024] To more clearly illustrate the technical solution of the present invention, the following embodiments are provided. Unless otherwise stated, the raw materials, reactions, and post-processing methods appearing in the embodiments are all commercially available raw materials and technical methods well known to those skilled in the art.

[0025] The terms "preferred," "more preferably," and "more suitable" used in this invention refer to embodiments of the invention that provide certain beneficial effects under certain circumstances. However, other embodiments may also be preferred under the same or other circumstances. Furthermore, the description of one or more preferred embodiments does not imply that other embodiments are unavailable, nor is it intended to exclude other embodiments from the scope of this invention.

[0026] It should be understood that, except in any operational instance or otherwise indicated, all figures representing the amounts of ingredients used, for example, in the specification and claims, should be understood to be modified in all cases by the term "about". Therefore, unless otherwise stated, the numerical parameters set forth in the following specification and appended claims are approximations varying with the desired performance to be obtained according to the invention.

[0027] The polyethyleneimine used in this embodiment of the invention was purchased from Aladdin, MW=1200.

[0028] Example 1

[0029] A high-efficiency fatty acid amide corrosion inhibitor, wherein the high-efficiency fatty acid amide corrosion inhibitor is a polymeric corrosion inhibitor;

[0030] The preparation method of the high-efficiency fatty acid amide corrosion inhibitor includes the following steps:

[0031] Using chloroform as a solvent, oleic acid and N,N'-carbonyldiimidazole were mixed and stirred for 30 min. Then, polyethyleneimine (the mass ratio of polyethyleneimine, oleic acid, and N,N'-carbonyldiimidazole was 0.5:1:0.57) was added, and the mixture was stirred and refluxed in an oil bath at 70 °C. After reacting for 10 h, the mixture was washed with saturated brine, dried with anhydrous magnesium sulfate, filtered, and then distilled under reduced pressure to obtain a polymer-type corrosion inhibitor.

[0032] Example 2

[0033] A high-efficiency fatty acid amide corrosion inhibitor, wherein the high-efficiency fatty acid amide corrosion inhibitor is a polymeric corrosion inhibitor and a small molecule corrosion inhibitor in a mass ratio of 4:1;

[0034] The preparation method of the high-efficiency fatty acid amide corrosion inhibitor includes the following steps:

[0035] Using chloroform as solvent, polyethyleneimine, oleic acid and N,N'-carbonyldiimidazole in a mass ratio of 0.5:1:0.57 were mixed and stirred under reflux in an oil bath at 70°C. After reacting for 10 h, the mixture was washed with saturated brine, dried with anhydrous magnesium sulfate, filtered, and then distilled under reduced pressure to obtain a polymer-type corrosion inhibitor.

[0036] Using xylene as a solvent, diethylenetriamine and oleic acid were mixed in a molar ratio of 1:1 and stirred and refluxed in an oil bath at 160°C. After the water level in the separator stopped increasing, vacuum distillation was carried out to obtain a small molecule corrosion inhibitor.

[0037] Example 3

[0038] A high-efficiency fatty acid amide corrosion inhibitor, wherein the high-efficiency fatty acid amide corrosion inhibitor is a polymeric corrosion inhibitor;

[0039] The preparation method of the high-efficiency fatty acid amide corrosion inhibitor includes the following steps:

[0040] Stearic acid and N,N'-carbonyldiimidazole were mixed and stirred for 30 min using chloroform as solvent. Then, polyethyleneimine (the mass ratio of polyethyleneimine, stearic acid and N,N'-carbonyldiimidazole was 0.5:1:0.57) was added, and the mixture was stirred and refluxed in an oil bath at 70 °C for 10 h. After the reaction, the mixture was washed with saturated brine, dried with anhydrous magnesium sulfate, filtered, and then distilled under reduced pressure to obtain a polymer-type corrosion inhibitor.

[0041] Example 4

[0042] A high-efficiency fatty acid amide corrosion inhibitor, wherein the high-efficiency fatty acid amide corrosion inhibitor is a polymeric corrosion inhibitor;

[0043] The preparation method of the high-efficiency fatty acid amide corrosion inhibitor includes the following steps:

[0044] Lauric acid and N,N'-carbonyldiimidazole were mixed and stirred for 30 min using chloroform as solvent. Then, polyethyleneimine (the mass ratio of polyethyleneimine, lauric acid and N,N'-carbonyldiimidazole was 0.7:1:0.81) was added, and the mixture was stirred and refluxed in an oil bath at 70 °C for 10 h. After the reaction, the mixture was washed with saturated brine, dried with anhydrous magnesium sulfate, filtered, and then distilled under reduced pressure to obtain a polymer-type corrosion inhibitor.

[0045] Example 5

[0046] A high-efficiency fatty acid amide corrosion inhibitor, wherein the high-efficiency fatty acid amide corrosion inhibitor is a polymeric corrosion inhibitor;

[0047] The preparation method of the high-efficiency fatty acid amide corrosion inhibitor includes the following steps:

[0048] Using chloroform as a solvent, eicosapentaenoic acid and N,N'-carbonyldiimidazole were mixed and stirred for 30 min. Then, polyethyleneimine (the mass ratio of polyethyleneimine, eicosapentaenoic acid, and N,N'-carbonyldiimidazole was 0.47:1:0.54) was added, and the mixture was stirred and refluxed in an oil bath at 70 °C. After reacting for 10 h, the mixture was washed with saturated brine, dried with anhydrous magnesium sulfate, filtered, and then distilled under reduced pressure to obtain a polymer-type corrosion inhibitor.

[0049] Comparative Example 1

[0050] A small molecule corrosion inhibitor, the preparation method includes the following steps:

[0051] Using xylene as a solvent, diethylenetriamine and oleic acid were mixed in a molar ratio of 1:1 and stirred and refluxed in an oil bath at 160°C. After the water level in the separator stopped increasing, vacuum distillation was carried out to obtain a small molecule corrosion inhibitor.

[0052] Comparative Example 2

[0053] A polymeric corrosion inhibitor, wherein the polymeric corrosion inhibitor is polyethyleneimine.

[0054] Test case

[0055] The corrosion inhibition effect of the corrosion inhibitor was tested using the weight loss method:

[0056] The sample was made of Q235A low carbon steel, with dimensions of 50 mm × 10 mm × 3 mm. Before testing, it was cleaned with acetone, ethanol and deionized water in sequence and then dried.

[0057] The corrosive medium was a 1000 mg / L HCl + 200 mg / L H2S solution (when the corrosion inhibitor sample was added, the concentration of the corrosion inhibitor was 100 mg / L); the stirring speed was 100 r / min (corrosive medium flow rate), the temperature was 50℃, and the corrosion time was 12 h.

[0058] After corrosion was completed, the samples were treated in accordance with GB / T 16545-1996. The corrosion deposits were cleaned with a cleaning solution of 10% HCl + 0.5% hexamethylenetetramine for 5 minutes. After cleaning, the samples were immediately cleaned with deionized water and anhydrous ethanol, then dried and weighed.

[0059] The corrosion inhibition rate is calculated using the following formula:

[0060]

[0061] η: Corrosion inhibition rate, %

[0062] v1: Corrosion rate before adding corrosion inhibitor;

[0063] v2: Corrosion rate after adding corrosion inhibitor;

[0064] The corrosion rate v is calculated using the following formula:

[0065]

[0066] m1: Mass of the sample before corrosion, in g;

[0067] m2: Mass of the sample after corrosion, in grams;

[0068] S: Surface area of ​​the sample, m² 2 ;

[0069] T: Corrosion time, h.

[0070] The test results are shown in Table 1.

[0071] Table 1 Performance Test Results

[0072]

[0073] As can be seen from the test data in Table 1, the high-efficiency fatty acid amide corrosion inhibitor prepared in the examples has a high corrosion inhibition rate. The polymeric corrosion inhibitor can form an efficient protective barrier through multiple active sites and long alkyl chains. In particular, Example 2, which combines polymeric and small-molecule corrosion inhibitors, can produce a strong synergistic effect. The polymeric network structure effectively anchors and covers the substrate surface, while the small-molecule corrosion inhibitor fills the gaps between macromolecules with its high mobility, resulting in a dense protective structure. This makes the corrosion inhibition effect more comprehensive and sufficient, and the erosion resistance stronger, thus achieving the highest corrosion inhibition rate. Comparative Example 1 uses a single small-molecule corrosion inhibitor, which has fewer adsorption sites and insufficient porosity and structural strength of the intermolecular arrangement, resulting in a significantly lower effect compared to the polymeric corrosion inhibitor in the examples. Comparative Example 2 uses polyethyleneimine as a corrosion inhibitor. Although it can be adsorbed by a large number of amino groups, its structure does not contain long hydrophobic alkyl segments, so it cannot form a hydrophobic shielding effect. The medium can still easily penetrate and corrode, and its corrosion inhibition performance is significantly weaker than that of the amidation product.

[0074] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0075] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A highly efficient fatty acid amide corrosion inhibitor, characterized in that, The high-efficiency fatty acid amide corrosion inhibitor includes polymer-type corrosion inhibitors; The polymeric corrosion inhibitor is obtained by reacting polyethyleneimine and fatty acids.

2. The high-efficiency fatty acid amide corrosion inhibitor according to claim 1, characterized in that, The polyethyleneimine is selected from one or more of branched polyethyleneimine or hyperbranched polyethyleneimine.

3. The high-efficiency fatty acid amide corrosion inhibitor according to claim 1, characterized in that, The fatty acid has ≥8 carbon atoms.

4. The high-efficiency fatty acid amide corrosion inhibitor according to claim 1, characterized in that, The high-efficiency fatty acid amide corrosion inhibitor also includes a small molecule corrosion inhibitor, which is obtained by reacting a small molecule amine with a fatty acid.

5. The high-efficiency fatty acid amide corrosion inhibitor according to claim 4, characterized in that, The small molecule amine is selected from one or more of ethylene amine and alcohol amine.

6. A method for preparing the high-efficiency fatty acid amide corrosion inhibitor according to any one of claims 1-5, characterized in that, The preparation method of the high-efficiency fatty acid amide corrosion inhibitor includes the following steps: Polyethyleneimine, fatty acids, and a catalyst are mixed and heated to react, yielding a polymer-type corrosion inhibitor.

7. The preparation method of the high-efficiency fatty acid amide corrosion inhibitor according to claim 6, characterized in that, The temperature of the heating reaction is 50-100℃.

8. The method for preparing the high-efficiency fatty acid amide corrosion inhibitor according to claim 6, characterized in that, The mass ratio of polyethyleneimine to fatty acid is (0.1-0.5):

1.

9. The method for preparing the high-efficiency fatty acid amide corrosion inhibitor according to claim 6, characterized in that, Also includes: Small molecule amines and fatty acids are mixed and heated to react, yielding a small molecule corrosion inhibitor.

10. The method for preparing the high-efficiency fatty acid amide corrosion inhibitor according to claim 9, characterized in that, The molar ratio of the small molecule amine to the fatty acid is 1:(1-3).

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