Corrosion-inhibiting composition and use thereof

Abstract

The application provides an anti-corrosion composition and application thereof. The anti-corrosion composition mainly comprises imidazoline derivatives, acetylenic alcohol derivatives, deoxidizing agents and metal salts, and secondly comprises surfactants and solvents. The anti-corrosion composition has good film forming performance, high anti-corrosion efficiency, can effectively prevent corrosion of carbon dioxide, hydrogen sulfide, oxygen and chloride ions, can be used as an anti-corrosion agent to effectively protect natural gas pipelines, and has the advantages of easy availability of raw materials, low cost, simple preparation method and application in the field of natural gas pipeline corrosion prevention.

Description

Technical Field

[0001] This invention belongs to the field of natural gas pipeline corrosion protection technology, and particularly relates to a corrosion-inhibiting composition and its application. Background Technology

[0002] In natural gas pipeline gathering and transportation, the presence of acidic and corrosive gases such as hydrogen sulfide and carbon dioxide, coupled with the fact that natural gas is not in a dry state and even trace amounts of moisture can cause these acidic gases to produce strong corrosive media such as sulfuric acid and hydrochloric acid, resulting in severe corrosion inside the pipeline.

[0003] Carbon dioxide corrosion is typically characterized by localized pitting, ring-like corrosion, and mesa-like pitting. Mesa-like pitting is the most severe, with a high perforation rate and a corrosion rate of 3 to 7 mm / year, reaching as high as 20 mm / year under anaerobic conditions. The most economical and effective method for combating carbon dioxide corrosion is to add corrosion inhibitors. While some inhibitors offer some protection against carbon dioxide corrosion, others are prone to desorption, significantly reducing their inhibitory efficiency or even rendering them ineffective. Hydrogen sulfide reacts with water to form sulfuric acid, further accelerating pipeline corrosion. The amount of steel consumed annually due to corrosion is enormous, causing substantial economic losses for companies. Although many corrosion inhibitors are available for oil pipelines, a highly effective solution remains for natural gas pipeline corrosion. Summary of the Invention

[0004] To address the aforementioned problems, the present invention aims to provide a corrosion-inhibiting composition and its application. The corrosion-inhibiting composition possesses the functions of preventing carbon dioxide corrosion, hydrogen sulfide corrosion, oxygen corrosion, and chloride ion corrosion, and can effectively protect natural gas pipelines under conditions of high oxygen and hydrogen sulfide content.

[0005] To achieve the above objectives, the present invention provides a corrosion inhibitory composition comprising an imidazoline derivative, an alkynol derivative, a deoxidizer, and a metal salt.

[0006] According to a preferred embodiment of the present invention, the corrosion inhibitor composition further includes a surfactant and a solvent.

[0007] According to a specific embodiment of the present invention, based on a mass meter of the corrosion inhibitor composition, the corrosion inhibitor composition comprises:

[0008]

[0009]

[0010] According to a specific embodiment of the present invention, the mass ratio of the imidazoline derivative to the alkynol derivative is (1 to 5):1;

[0011] Preferably, the mass ratio of the imidazoline derivative to the alkynol derivative is (1.6 to 4):1;

[0012] More preferably, the mass ratio of the imidazoline derivative to the alkynol derivative is 4:1.

[0013] According to a preferred embodiment of the present invention, based on the mass of the corrosion inhibitory composition, the corrosion inhibitory composition comprises 40 parts by mass of an imidazoline derivative, 10 parts by mass of an alkynol derivative, 20 parts by mass of a deoxidizer, 10 parts by mass of a metal salt, 5 parts by mass of a surfactant, and 20 parts by mass of a solvent.

[0014] According to a specific embodiment of the present invention, the imidazoline derivative is selected from at least one of 1-hydroxyethyl-2-undecyl-1-carboxymethyl imidazoline, heptadecanylaminoethyl imidazoline quaternary ammonium salt, hydroxyethyl amphoteric imidazoline, heptadecanylaminoethyl imidazoline, undecyl imidazoline, dodecyl hydroxyethyl imidazoline, hydroxyethyl oleic acid imidazoline, and heptadecanyl imidazoline; and / or

[0015] The alkynyl alcohol derivative is selected from at least one of alkynyl glycol polyoxyethylene ether, propoxylated alkynyl alcohol, ethoxylated alkynyl alcohol, 6-heptenyl alcohol, and 7-octynyl alcohol; and / or

[0016] The deoxygenating agent is selected from isoascorbic acid and / or sodium isoascorbate; and / or

[0017] The metal salt is selected from at least one of sodium salt, zinc salt, and nickel salt.

[0018] According to one specific embodiment of the present invention, the imidazoline derivative is a mixture of 1-hydroxyethyl-2-undecyl-1-carboxymethylimidazoline and heptadecenylaminoethylimidazoline; and / or

[0019] The alkynyl alcohol derivative is an alkynyl diol polyoxyethylene ether; and / or

[0020] The deoxidizer is a mixture of isoascorbic acid and sodium isoascorbate; and / or

[0021] The metal salt is a mixture of sodium and zinc salts.

[0022] According to one specific embodiment of the present invention, the mass ratio of 1-hydroxyethyl-2-undecyl-1-carboxymethylimidazoline to heptadecenylaminoethylimidazoline is 1:(0.3 to 1.2); and / or

[0023] The mass ratio of isoascorbic acid to sodium isoascorbate is 1:(0.5 to 1.5); and / or

[0024] The mass ratio of the sodium salt to the zinc salt is 1:(0.8 to 1.2);

[0025] Preferably, the mass ratio of 1-hydroxyethyl-2-undecyl-1-carboxymethylimidazoline to heptadecenylaminoethylimidazoline is 1:0.8; and / or

[0026] The mass ratio of isoascorbic acid to sodium isoascorbate and the mass ratio of sodium salt to zinc salt are independently 1:1.

[0027] According to one specific embodiment of the present invention, the deoxidizer is a mixture of D-isoascorbic acid and sodium D-isoascorbate; and / or

[0028] The sodium salt is sodium tungstate and / or sodium benzoate; and / or the zinc salt is zinc sulfate;

[0029] Preferably, the sodium tungstate is sodium tungstate dihydrate; and / or the zinc sulfate is zinc sulfate heptahydrate.

[0030] According to a specific embodiment of the present invention, the surfactant is selected from at least one of the following: amine salt cationic surfactants, quaternary ammonium salt cationic surfactants, heterocyclic cationic surfactants, cyclohexane salt cationic surfactants, anionic polyacrylamide anionic surfactants, fatty acid salt anionic surfactants, sulfonate anionic surfactants, sulfate salt anionic surfactants, phosphate salt anionic surfactants, fatty alcohol polyoxyethylene ether nonionic surfactants, alkylphenol polyoxyethylene ether nonionic surfactants, polyoxyethylene alkylamine nonionic surfactants, polyoxyethylene alkylolamine nonionic surfactants, and polyether nonionic surfactants; and / or

[0031] The solvent is selected from at least one of water, alcohol solvents, ether solvents, ester solvents, aliphatic hydrocarbon solvents, aromatic hydrocarbon solvents, ketone solvents, and phenol solvents.

[0032] In one specific embodiment of the present invention, the surfactant is selected from at least one of fatty alcohol polyoxyethylene ether type nonionic surfactants, alkylphenol polyoxyethylene ether type nonionic surfactants, polyoxyethylene alkylamine type nonionic surfactants, polyoxyethylene alkylolamine type nonionic surfactants, and polyether type nonionic surfactants; and / or

[0033] The solvent is a mixture of water and alcohol solvents;

[0034] Preferably, the mass ratio of water to alcohol solvent in the solvent is 1:(0.5 to 3);

[0035] Preferably, the mass ratio of water to alcohol solvent in the solvent is 1:2; and / or

[0036] The surfactant is a fatty alcohol polyoxyethylene ether type nonionic surfactant; and / or

[0037] The alcohol solvent is ethylene glycol.

[0038] The application of the corrosion inhibitor composition according to the present invention in the field of natural gas pipeline corrosion protection technology, particularly as a corrosion inhibitor for continuous injection of natural gas pipelines under oxygen-containing and hydrogen sulfide-containing conditions.

[0039] The beneficial effects of this invention are:

[0040] To address the problem that existing corrosion inhibitors cannot effectively protect natural gas pipelines, this invention provides a corrosion-inhibiting composition and its application. The corrosion-inhibiting composition mainly comprises imidazoline derivatives, alkynyl alcohol derivatives, deoxidizers, and metal salts, and secondarily includes surfactants and solvents. The imidazoline derivatives, alkynyl alcohol derivatives, deoxidizers, and metal salts exhibit a synergistic effect in enhancing corrosion inhibition, showing good corrosion inhibition effects against carbon dioxide, hydrogen sulfide, oxygen, and chloride ion corrosion. At an experimental temperature of 50°C, using oilfield produced water containing carbon dioxide, hydrogen sulfide, oxygen, and chloride ions as the corrosive medium, the 0.05 mg / mL corrosion-inhibiting composition resulted in a uniform corrosion rate and pitting corrosion rate of only 0.0427 to 0.0521 mm / year and 0.0512 to 0.0634 mm / year for A3 steel sheets, respectively, corresponding to corrosion inhibition rates above 90%, specifically 92% to 96%. The corrosion inhibitor composition exhibits good film-forming properties: under constant temperature conditions of 50°C, A3 steel sheets were pre-coated with the corrosion inhibitor composition at a concentration of 0.05 mg / mL for 1 hour, then immersed in a saturated copper sulfate solution for 10 seconds. Finally, no copper plating was observed on the surface of the A3 steel sheets in a hydrochloric acid solution with a pH of 2.5. The corrosion inhibitor composition provided by this invention can be used as a corrosion inhibitor to effectively protect natural gas pipelines. Furthermore, the raw materials are readily available, the cost is low, and the preparation method is simple, making it applicable in the field of natural gas pipeline corrosion protection. Detailed Implementation

[0041] The present invention will be further described below with reference to the embodiments. However, the embodiments of the present invention are merely illustrative examples and should not be construed as limiting the present invention under any circumstances.

[0042] Formulation of corrosion inhibitor composition

[0043] 1-Hydroxyethyl-2-undecyl-1-carboxymethylimidazoline: purchased from Shanghai Xuejie Chemical Co., Ltd., product name is amphoteric imidazoline;

[0044] Heptadecanylaminoethylimidazoline: Purchased from Qinhuangdao Yuexiang Technology Co., Ltd., model number ODM;

[0045] Acetylene glycol polyoxyethylene ether: purchased from Taizhou Dongyao Chemical Co., Ltd., model number DY-456;

[0046] Fatty alcohol polyoxyethylene ether: purchased from Tianjin Hongtai Chemical Co., Ltd., model OS-15;

[0047] Sodium tungstate dihydrate: purchased from Wujiang Nanfeng Fine Chemical Co., Ltd.;

[0048] Zinc sulfate heptahydrate: purchased from Jinan Baiqin Chemical Co., Ltd.

[0049] Example 1

[0050] A corrosion inhibitor composition was obtained by mixing 40g of an imidazoline derivative (in which the mass ratio of 1-hydroxyethyl-2-undecyl-1-carboxymethylimidazoline to heptadecenylaminoethylimidazoline was 1:0.8), 10g of acetylacetonate diol polyoxyethylene ether, 20g of a deoxidizer (in which the mass ratio of D-isoascorbic acid to sodium D-isoascorbate was 1:1), 5g of fatty alcohol polyoxyethylene ether, 10g of a metal salt (in which the mass ratio of sodium tungstate dihydrate to zinc sulfate heptahydrate was 1:1) and 20g of a solvent (in which the mass ratio of water to ethylene glycol was 1:2).

[0051] Example 2

[0052] A corrosion inhibitor composition was obtained by mixing 10g of an imidazoline derivative (in which the mass ratio of 1-hydroxyethyl-2-undecyl-1-carboxymethylimidazoline to heptadecenylaminoethylimidazoline was 1:0.3), 5g of acetylacetonate diol polyoxyethylene ether, 10g of a deoxidizer (in which the mass ratio of D-isoascorbic acid to sodium D-isoascorbate was 1:0.5), 1g of fatty alcohol polyoxyethylene ether, 5g of a metal salt (in which the mass ratio of sodium tungstate dihydrate to zinc sulfate heptahydrate was 1:0.8), and 10g of a solvent (in which the mass ratio of water to ethylene glycol was 1:0.5).

[0053] Example 3

[0054] A corrosion inhibitor composition was obtained by mixing 50g of an imidazoline derivative (in which the mass ratio of 1-hydroxyethyl-2-undecyl-1-carboxymethylimidazoline to heptadecenylaminoethylimidazoline was 1:1.2), 30g of acetylacetonate diol polyoxyethylene ether, 30g of deoxidizer (in which the mass ratio of D-isoascorbic acid to sodium D-isoascorbate was 1:1.5), 10g of fatty alcohol polyoxyethylene ether, 20g of metal salt (in which the mass ratio of sodium tungstate dihydrate to zinc sulfate heptahydrate was 1:1.2), and 30g of solvent (in which the mass ratio of water to ethylene glycol was 1:3).

[0055] Comparative Example 1

[0056] A corrosion inhibitor composition was obtained by mixing 10g of acetylacetonate diol polyoxyethylene ether, 20g of deoxidizer (in which the mass ratio of D-isoascorbic acid and sodium D-isoascorbate was 1:1), 5g of fatty alcohol polyoxyethylene ether, 10g of metal salt (in which the mass ratio of sodium tungstate dihydrate and zinc sulfate heptahydrate was 1:1) and 20g of solvent (in which the mass ratio of water and ethylene glycol was 1:2).

[0057] Comparative Example 2

[0058] A corrosion inhibitor composition was obtained by mixing 40g of an imidazoline derivative (in which the mass ratio of 1-hydroxyethyl-2-undecyl-1-carboxymethylimidazoline to heptadecenylaminoethylimidazoline was 1:0.8), 20g of a deoxidizer (in which the mass ratio of D-isoascorbic acid to sodium D-isoascorbate was 1:1), 5g of fatty alcohol polyoxyethylene ether, 10g of a metal salt (in which the mass ratio of sodium tungstate dihydrate to zinc sulfate heptahydrate was 1:1) and 20g of a solvent (in which the mass ratio of water to ethylene glycol was 1:2).

[0059] Comparative Example 3

[0060] A corrosion-inhibiting composition was obtained by mixing 40g of an imidazoline derivative (in which the mass ratio of 1-hydroxyethyl-2-undecyl-1-carboxymethylimidazoline to heptadecenylaminoethylimidazoline was 1:0.8), 10g of acetylacetonate diol polyoxyethylene ether, 5g of fatty alcohol polyoxyethylene ether, 10g of a metal salt (in which the mass ratio of sodium tungstate dihydrate to zinc sulfate heptahydrate was 1:1) and 20g of a solvent (in which the mass ratio of water to ethylene glycol was 1:2).

[0061] Comparative Example 4

[0062] A corrosion inhibitor composition was obtained by mixing 40g of imidazoline derivative (in which the mass ratio of 1-hydroxyethyl-2-undecyl-1-carboxymethylimidazoline and heptadecenylaminoethylimidazoline was 1:0.8), 10g of acetylacetonate diol polyoxyethylene ether, 20g of deoxidizer (in which the mass ratio of D-isoascorbic acid and sodium D-isoascorbate was 1:1), 5g of fatty alcohol polyoxyethylene ether, and 20g of solvent (in which the mass ratio of water and ethylene glycol was 1:2).

[0063] Experimental Evaluation

[0064] 1. Evaluation of the corrosion inhibition performance of the corrosion-inhibiting composition

[0065] According to the "Method for Determining Static Corrosion Rate and Corrosion Inhibition Rate under Normal Pressure" in the petroleum and natural gas industry standard SY / T 5273-2000 "Performance Evaluation Method for Corrosion Inhibitors for Oilfield Produced Water", the corrosion inhibition performance of the corrosion inhibitor compositions prepared in Examples 1 to 3 and Comparative Examples 1 to 4 was evaluated.

[0066] i. Corrosive medium: Oilfield produced water containing carbon dioxide, hydrogen sulfide, oxygen, and chloride ions, with a carbon dioxide content of 8 wt% and a hydrogen sulfide concentration of 18000 mg / m³. 3 The dissolved oxygen concentration was 0.3 mg / L, and the chloride ion concentration was 130,000 mg / L.

[0067] ii. Preparation of corrosion inhibitor solution: Mix the corrosion inhibitor composition with water at a mass ratio of 1:1 to obtain the corrosion inhibitor solution;

[0068] iii. Test piece: A rectangular A3 steel sheet with dimensions of 50mm × 13mm × 1.5mm was used. A small hole with a diameter of 4mm was drilled 10mm from the edge at one end, and the hole was marked. The test piece was then wiped clean with filter paper and placed in acetone with a boiling range of 60 to 90℃. The grease on the surface of the test piece was removed with degreasing cotton. The test piece was then soaked in anhydrous ethanol for 5 minutes for further degreasing and dehydration. The test piece was then removed, placed on filter paper, dried with cold air, wrapped in filter paper, and placed in a desiccator for 1 hour to obtain the treated test piece. The dimensions and weight were measured, with the weight accurate to 0.1mg.

[0069] iv. Use a pipette to transfer 50 mL (i.e. 25 mg) of corrosion inhibitor solution into a 250 mL wide-mouth glass bottle sealed with a rubber stopper. Add nitrogen gas to remove oxygen, then introduce the corrosive medium through a rubber tube until the bottle is full. As the liquid level rises, gradually raise the rubber tube. When the liquid level reaches the bottleneck, hang the prepared test piece from step iii, seal the bottle with a rubber stopper, and place it in a constant temperature oven at 50 °C for the experiment.

[0070] ⅵ After 7 days of experimentation, remove the corroded specimen, observe and record the corrosion state of the surface and the adhesion of corrosion products, immediately rinse off the test medium with clean water, and wipe dry with filter paper;

[0071] vii. Place the corroded specimen treated in step vi into acetone with a boiling range of 60 to 90°C. Remove surface oil with degreasing cotton, then soak in anhydrous ethanol for 5 minutes for further degreasing and dehydration. Next, soak in acid cleaning solution (obtained by mixing 100 mL of analytical grade hydrochloric acid and 10 g of analytical grade hexamethylenetetramine and diluting with water to 1000 mL) for 5 minutes, while gently wiping the corrosion products on the surface of the specimen with a small amount of degreasing cotton using tweezers. Remove the specimen from the acid cleaning solution, rinse off the residual acid with tap water, and immediately immerse the specimen in a sodium hydroxide aqueous solution (with a sodium hydroxide concentration of 60 g / L). After 30 seconds, rinse with tap water, then soak in anhydrous ethanol for 5 minutes, washing and dehydrating twice. Remove the specimen, place it on filter paper, dry it with cold air, wrap it with filter paper, place it in a desiccator for 1 hour, and weigh it to an accuracy of 0.1 mg.

[0072] ⅷ Observe and record the corrosion status of the test piece surface. If there is pitting, record the number of pits per unit area and measure the deepest pitting depth using a pitting depth sounder.

[0073] Following the steps described above, the corrosion inhibition performance of the corrosion inhibitor compositions prepared in Examples 1 to 3 and Comparative Examples 1 to 4 was determined. Corrosion media without the addition of corrosion inhibitor solution prepared from the corrosion inhibitor composition were used as blank controls. The above experiments were conducted together with each group of experiments, which consisted of three parallel experiments, and each parallel experiment contained three test pieces.

[0074] After the experiment, the uniform corrosion rate of the specimens in each group of experiments and the corresponding corrosion inhibition rate were calculated according to the following formulas:

[0075]

[0076] In the formula: r corr The corrosion rate is uniform, expressed in mm / year.

[0077] m is the mass of the test piece before the experiment, in grams;

[0078] m t The mass of the test piece after the experiment is expressed in grams.

[0079] S1 represents the total area of ​​the test piece, in cm². 2 ;

[0080] ρ is the density of the sample material, in g / cm³. 2 ;

[0081] t represents the experimental time, in hours (h).

[0082]

[0083] In the formula: η is the corrosion inhibition rate, in %;

[0084] Δm0 represents the mass loss of the specimen in the blank experiment (i.e., the corrosive medium without the addition of corrosion inhibitor solution), in grams.

[0085] Δm1 represents the mass loss of the test piece in the corrosive medium to which the corrosion inhibitor solution was added, in grams.

[0086]

[0087] In the formula, r t The value represents the pitting rate, expressed in mm / year.

[0088] h t The deepest pitting depth on the surface of the specimen after corrosion, in mm;

[0089] t represents the experimental time, in hours (h).

[0090] The arithmetic mean of the measurement results of 9 test pieces from 3 parallel experiments in each group was taken as the measurement result, as shown in Table 1.

[0091] Table 1. Evaluation of the sustained-release performance of corrosion-inhibiting compositions

[0092] Serial Number Uniform corrosion rate (mm / year) Pitting rate (mm / year) Corrosion inhibition rate (%) Blank control 0.4217 0.5621 / Example 1 0.0427 0.0512 96 Example 2 0.0521 0.0634 92 Example 3 0.0482 0.0553 95 Comparative Example 1 0.1279 0.1436 84 Comparative Example 2 0.2004 0.2347 62 Comparative Example 3 0.1675 0.1860 75 Comparative Example 4 0.1356 0.1524 80

[0093] As can be seen from the data in Table 1, the uniform corrosion rate and pitting rate of the test pieces in the blank control group were the highest. The uniform corrosion rate and pitting rate of the test pieces in the corrosive medium containing the corrosion inhibitor compositions prepared in Examples 1 to 3 were only 0.0427 to 0.0521 mm / year and 0.0512 to 0.0634 mm / year, respectively. Compared with the blank control group, the corrosion inhibition rate of the corrosion inhibitor compositions prepared in Examples 1 to 3 was all above 90%, specifically 92% to 96%, indicating a better corrosion inhibition effect. Compared with the examples, Comparative Examples 1 to 4 all showed a lack of raw materials in their formulations, and the uniform corrosion rate and pitting rate were respectively... The corrosion inhibition rates were 0.1279 to 0.2004 mm / year and 0.1436 to 0.2347 mm / year, both greater than those in Examples 1 to 3. Compared with the blank control group, the corrosion inhibition rate of the corrosion-inhibiting compositions prepared in Comparative Examples 1 to 4 was 62% to 84%, which did not reach 90%. The corrosion inhibition performance was worse than that of the corrosion-inhibiting compositions prepared in Examples 1 to 3. This also indicates that there is a synergistic effect between the imidazoline derivatives, alkynol derivatives, deoxidizers and metal salts in the corrosion-inhibiting compositions prepared in this invention in enhancing corrosion inhibition, so that the corrosion-inhibiting compositions have a good corrosion inhibition effect on oilfield produced water containing carbon dioxide, hydrogen sulfide, oxygen and chloride ions.

[0094] 2. Evaluation of the film-forming properties of the corrosion-inhibiting composition

[0095] According to the "5. Film-forming performance test method" in the petroleum and natural gas industry standard SY / T 5273-2000 "Performance evaluation method for corrosion inhibitors used in oilfield produced water", the film-forming performance of the corrosion inhibitor compositions prepared in Examples 1 to 3 and Comparative Examples 1 to 4 was evaluated.

[0096] A. Corrosive Media: Oilfield produced water containing carbon dioxide, hydrogen sulfide, oxygen, and chloride ions, with a carbon dioxide content of 8 wt% and a hydrogen sulfide concentration of 18000 mg / m³. 3 The dissolved oxygen concentration was 0.3 mg / L, and the chloride ion concentration was 130,000 mg / L.

[0097] B. Preparation of corrosion inhibitor solution: Mix the corrosion inhibitor composition with water at a mass ratio of 1:1 to obtain the corrosion inhibitor solution;

[0098] C. Prepare 1000 mL of hydrochloric acid solution with a pH of 2.5 using water and concentrated hydrochloric acid (analytical grade);

[0099] D. Prepare a saturated copper sulfate solution using water and copper sulfate (analytical grade);

[0100] E. Test piece: A rectangular A3 steel sheet with dimensions of 50mm×13mm×1.5mm is used. A small hole with a diameter of 4mm is drilled 10mm from the edge at one end and marked. Then, the test piece is wiped clean with filter paper and placed in acetone with a boiling range of 60 to 90℃. The grease on the surface of the test piece is removed with degreasing cotton. The test piece is then soaked in anhydrous ethanol for 5 minutes for further degreasing and dehydration. The test piece is then removed, placed on filter paper, dried with cold air, wrapped with filter paper, and placed in a desiccator for 1 hour to obtain the treated test piece.

[0101] F. Use a pipette to transfer 50 mL (i.e. 25 mg) of corrosion inhibitor solution into a 250 mL wide-mouth bottle, then fill it with the corrosive medium, mix it evenly, and obtain the corrosive medium containing the corrosion inhibitor.

[0102] G. Suspend the test piece treated in step E in a corrosive medium containing corrosion inhibitor using steel nylon thread, seal it, and pre-film it at a constant temperature of 50°C for 1 hour;

[0103] H. Take out the pre-filmed sample, immerse it in the saturated copper sulfate solution prepared in step D for 10 seconds, and immediately place it in the hydrochloric acid solution with a pH of 2.5 prepared in step C. Observe the copper plating on the sample and evaluate the film-forming performance of the corrosion inhibitor composition according to the standards specified in Table 2.

[0104] Following the steps described above, the film-forming properties of the corrosion-inhibiting compositions prepared in Examples 1 to 3 and Comparative Examples 1 to 4 were evaluated, and the results are shown in Table 3.

[0105] Table 2. Evaluation of film-forming properties of corrosion-inhibiting compositions

[0106] Phenomenon Evaluation results rating level Full copper plating on the surface of the test piece The corrosion inhibitor composition exhibits poor film-forming properties at this mass concentration. D 1 / 2 copper plating on the surface of the test piece The corrosion inhibitory composition exhibits moderate film-forming properties at this mass concentration. C 1 / 3 of the sample surface is coated with copper The corrosion-inhibiting composition exhibits good film-forming properties at this mass concentration. B The test piece surface is bright and has no copper plating. The corrosion-inhibiting composition exhibits good film-forming properties at this mass concentration. A

[0107] Table 3. Evaluation results of corrosion inhibitor film-forming performance

[0108]

[0109]

[0110] As shown in Tables 2 and 3, after the experiment, the surface of the test piece was bright and without coating when the corrosion inhibitor compositions prepared in Examples 1 to 3 were added to the corrosive medium, proving that the corrosion inhibitor compositions prepared in Examples 1 to 3 had good film-forming performance as corrosion inhibitors on the test piece surface. After the experiment, the surface of the test piece had copper coating on 1 / 3 to 1 / 2 of the area when the corrosion inhibitor compositions prepared in Comparative Examples 1 to 4 were added to the corrosive medium, indicating that the film-forming performance of the corrosion inhibitor compositions prepared in Comparative Examples 1 to 4 as corrosion inhibitors on the test piece surface was worse than that of the corrosion inhibitor compositions prepared in Examples 1 to 3.

[0111] While the present invention has been described with reference to specific embodiments, those skilled in the art will understand that various changes can be made without departing from the true spirit and scope of the invention. Furthermore, numerous modifications can be made to the subject, spirit, and scope of the invention to suit specific situations, materials, material compositions, and methods. All such modifications are included within the scope of the claims of the present invention.

Claims

1. An inhibitor composition comprising an imidazoline derivative, an acetylenic alcohol derivative, a deoxidizing agent, and a metal salt; a mass ratio of the imidazoline derivative and the acetylenic alcohol derivative is (1 to 5): 1; the imidazoline derivative is a mixture of 1-hydroxyethyl-2-undecyl-1-carboxymethyl imidazoline and heptadecenyl amine ethyl imidazoline, wherein a mass ratio of 1-hydroxyethyl-2-undecyl-1-carboxymethyl imidazoline and heptadecenyl amine ethyl imidazoline is 1:(0.3 to 1.2); the acetylenic alcohol derivative is an acetylenic diol polyoxyethylene ether; the deoxidizing agent is a mixture of erythorbic acid and sodium erythorbate, wherein a mass ratio of erythorbic acid and sodium erythorbate is 1:(0.5 to 1.5); the metal salt is a mixture of a sodium salt and a zinc salt, wherein a mass ratio of the sodium salt and the zinc salt is 1:(0.8 to 1.2), the sodium salt is sodium tungstate, and the zinc salt is zinc sulfate.

2. The corrosion inhibiting composition of claim 1, wherein, the inhibitor composition further comprises a surfactant and a solvent.

3. The corrosion inhibiting composition of claim 2, wherein, the inhibitor composition comprises, based on a mass of the inhibitor composition: the imidazoline derivative 10 to 50 parts by mass; the acetylenic alcohol derivative 5 to 30 parts by mass; the deoxidizing agent 10 to 30 parts by mass; the metal salt 5 to 20 parts by mass; the surfactant 1 to 10 parts by mass; the solvent 10 to 30 parts by mass.

4. The corrosion inhibiting composition according to any one of claims 1 to 3, characterized in that, a mass ratio of the imidazoline derivative and the acetylenic alcohol derivative is (1.6 to 4):

1.

5. The corrosion inhibiting composition of claim 2, wherein, the surfactant is at least one selected from the group consisting of an amine salt type cationic surfactant, a quaternary ammonium salt type cationic surfactant, a heterocyclic type cationic surfactant, a betaine type cationic surfactant, an anionic polyacrylamide type anionic surfactant, a fatty acid salt type anionic surfactant, a sulfonate type anionic surfactant, a sulfate ester salt type anionic surfactant, a phosphate ester salt type anionic surfactant, a fatty alcohol polyoxyethylene ether type nonionic surfactant, an alkyl phenol polyoxyethylene ether type nonionic surfactant, a polyoxyethylene alkyl amine type nonionic surfactant, a polyoxyethylene alkyl alcohol amine type nonionic surfactant, and a polyether type nonionic surfactant; and / or the solvent is at least one selected from the group consisting of water, an alcohol solvent, an ether solvent, an ester solvent, a fatty hydrocarbon solvent, an aromatic hydrocarbon solvent, a ketone solvent, and a phenol solvent.

6. Use of the inhibitor composition according to any one of claims 1 to 5 in the technical field of natural gas pipeline corrosion prevention.

7. Use according to claim 6, characterized in that, the use is use of the inhibitor composition as a continuous inhibitor for a natural gas pipeline under a working condition containing oxygen and hydrogen sulfide.

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