Preparation method and application of imidazole-based ionic liquid corrosion inhibitor

Abstract

This invention relates to the field of chemical materials, particularly to metal protection in the metal pickling industry, specifically a method for preparing an imidazole-based ionic liquid corrosion inhibitor and its application. The chemical structural formula of the imidazole-based ionic liquid corrosion inhibitor, 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazolium-3-onium bromide, is as follows: The imidazole-based ionic liquid corrosion inhibitor of this invention can be used for the protection against acid pickling corrosion of metal materials, and can withstand various changes in cleaning conditions well. In particular, the pickling corrosion inhibitor of this invention has the technical characteristics of low preparation cost, good solubility, good environmental compatibility, low inhibitor dosage, high corrosion inhibition efficiency, stable performance of the corrosion inhibitor, and long continuous action time. Its application range is wide and it is worthy of large-scale promotion and application.

Description

Technical Field

[0001] This invention relates to the field of chemical materials, particularly to metal protection in the metal pickling industry, specifically to a method for preparing an imidazole-based ionic liquid corrosion inhibitor and its application. Background Technology

[0002] Metallic materials are widely used in building structures, chemical pipelines, water supply systems, and machinery due to their excellent machinability. These devices require degreasing and rust removal after a period of operation. Typically, inorganic acids such as hydrochloric acid and sulfuric acid are added during these processes. However, prolonged exposure to acidic environments can easily lead to corrosion of metallic materials, resulting in significant resource waste and economic losses.

[0003] Over the past few decades, various corrosion prevention methods have been applied to protect metallic materials, such as protective coatings, cathodic protection, anodic protection, and the addition of corrosion inhibitors. Among these, the addition of corrosion inhibitors is one of the most commonly used methods to prevent or reduce the corrosion of metallic materials in acidic media due to its ease of use and high efficiency.

[0004] Corrosion inhibitors are generally classified into inorganic and organic types. Inorganic corrosion inhibitors include cadmium salts, arsenic salts, nitrites, chromates, phosphates, dichromates, and alkali metal sulfides, which are added to corrosive solutions to protect various metallic materials and their alloys. However, these inorganic corrosion inhibitors suffer from drawbacks such as requiring large amounts and having poor environmental friendliness, thus limiting their application. Organic corrosion inhibitors, on the other hand, contain heteroatoms or unsaturated bonds such as N, O, and S, which can adsorb onto the metal surface, forming a protective film. While some organic corrosion inhibitors have gained widespread use due to their significant effectiveness, those with high toxicity are gradually being phased out because they do not meet environmental protection laws and regulations.

[0005] Currently developed organic corrosion inhibitors suffer from poor water solubility and unsatisfactory corrosion inhibition effects due to their aromatic ring structures. It is generally believed that the concentration of organic corrosion inhibitors to achieve the required corrosion inhibition in acidic corrosive media should be less than 500 ppm; however, the dosage of some organic corrosion inhibitors still far exceeds this requirement. Therefore, the design and synthesis of highly efficient, low-toxicity, and low-cost organic corrosion inhibitor molecular structures is a research hotspot and technical challenge in the field of metal pickling corrosion inhibitors.

[0006] Existing research has shown that ionic liquids have a series of advantages, such as low toxicity, wide liquid phase range, low volatility, high thermal stability, high water solubility and non-flammability. In the future, they will gradually become the main alternative to existing organic corrosion inhibitors for metal pickling. Summary of the Invention

[0007] To address the aforementioned problems, the present invention aims to provide an imidazole-based ionic liquid corrosion inhibitor and its preparation method. The imidazole-based ionic liquid corrosion inhibitor is 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-onium bromide, which is used as a metal pickling corrosion inhibitor. This imidazole-based ionic liquid exhibits good water solubility, acid solubility, and superior corrosion inhibition performance.

[0008] To achieve the above-mentioned objectives, the specific technical solution of this invention is as follows:

[0009] A corrosion inhibitor of imidazole-based ionic liquid, 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-onium bromide, has the following molecular structure:

[0010]

[0011] A corrosion inhibitor of imidazole-based ionic liquid, 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-onium bromide, is prepared by the following steps:

[0012]

[0013] The specific preparation method is as follows:

[0014] (1) Add 4-bromomethylbiphenyl, imidazole, potassium hydroxide and a certain amount of organic solvent to a round-bottom flask and stir under water bath heating conditions.

[0015] (2) Cool and filter, remove organic solvent by rotary evaporation, dissolve the obtained solid in organic solvent, and repeatedly extract with water until the aqueous phase is neutral. Then dry the organic phase with anhydrous magnesium sulfate, filter, and evaporate the solvent to obtain pale yellow 1-(4'-biphenylmethyl)-1H-imidazole.

[0016] (3) Carefully add the 1-(4'-biphenylmethyl)-1H-imidazolium and ethyl bromoacetate obtained in step (2) into a round-bottom flask, then add an organic solvent, and react for 4-8 hours under stirring and heating.

[0017] (4) Evaporate the organic solvent to obtain a pale yellow oily substance. Wash the oily substance with n-hexane, petroleum ether or ethyl acetate, filter, and vacuum dry the oily substance to obtain 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-onium bromide.

[0018] As a preferred embodiment of this application, the molar ratio of 4-bromomethylbiphenyl, imidazole and potassium hydroxide in step (1) is 1:1-3:1-3; the stirring reaction time is 4-8h.

[0019] As a preferred embodiment of this application, the solvent in step (1) is any one of methanol, ethanol, isopropanol, and acetonitrile.

[0020] As a preferred embodiment of this application, the water bath temperature in step (1) is 40-80℃.

[0021] As a preferred embodiment of this application, the organic solvent used to dissolve the solid in step (2) is either dichloromethane or trichloromethane.

[0022] As a preferred embodiment of this application, the organic solvent in step (3) is any one of methanol, ethanol, isopropanol, and acetonitrile.

[0023] As a preferred embodiment of this application, the molar ratio of 1-(4'-biphenylmethyl)-1H-imidazole and ethyl bromoacetate in step (3) is 1:1-1.3.

[0024] As a preferred embodiment of this application, the heating conditions in step (3) are 30-60°C.

[0025] Another objective of this application is the application of the imidazole-based ionic liquid corrosion inhibitor, 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-onium bromide, described above, in the field of metal pickling.

[0026] As a preferred embodiment of this application, the specific application steps of 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-onium bromide as a corrosion inhibitor for metal corrosion are as follows:

[0027] A certain amount of 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-onium bromide was added to an inorganic acid to obtain an acid pickling corrosion inhibitor, which was then used for pickling various metallic materials.

[0028] In a preferred embodiment of this application, the inorganic acid is any one of hydrochloric acid, sulfuric acid, phosphoric acid, hydrofluoric acid, nitric acid, and carbonic acid.

[0029] In a preferred embodiment of this application, the concentration of inorganic acid in the pickling corrosion inhibitor is 1-4 mol / L.

[0030] In a preferred embodiment of this application, the metal material is any one of low-carbon steel, magnesium alloy, copper, or aluminum alloy.

[0031] In a preferred embodiment of this application, the concentration of 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-onium bromide in the pickling corrosion inhibitor is 0.02-0.2 mmol / L in the inorganic acid.

[0032] In a preferred embodiment of this application, the pickling temperature is 30-60°C and the pickling soaking time is 4-48 hours.

[0033] The 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-onium bromide of the present invention exhibits good corrosion inhibition effect in inorganic acids of 1-4 mol / L. Simultaneously, the concentration of 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-onium bromide in inorganic acids is 0.02-0.2 mmol / L, which is characterized by low dosage and high corrosion inhibition efficiency. Furthermore, the 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-onium bromide of the present invention can withstand various changes in cleaning conditions (such as temperature, acid concentration, immersion time, etc.), and can meet the requirements of most acid pickling industries.

[0034] The 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-onium bromide of the present invention can inhibit the corrosion of various metals (such as low-carbon steel, magnesium alloys, copper, aluminum alloys, etc.) in acidic media. In particular, it exhibits excellent corrosion inhibition properties for low-carbon steels, such as Q195, Q215, Q235, Q255, and Q275.

[0035] Test results show that the bromide 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-onium of the present invention has the advantages of low preparation cost, good water solubility, and good acid solubility. The metal pickling corrosion inhibitor prepared has the advantages of low corrosion inhibitor dosage, high corrosion inhibition efficiency, stable corrosion inhibitor performance, and long duration of corrosion inhibition effect. It has a wide range of applications and high application value.

[0036] Furthermore, the present invention provides an application of the corrosion-inhibiting effect of 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-onium bromide in metal pickling solutions. Specifically, 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-onium bromide is added to an inorganic acid (hydrochloric acid, sulfuric acid, etc.) with a concentration of 1-4 mol / L, making its concentration range 0.02-0.2 mmol / L. The pickling temperature is controlled at 30-60°C. Different metal materials are cleaned, and the immersion time is 4-48 hours to complete the pickling of metal materials and related metal equipment.

[0037] Compared with the prior art, the beneficial effects of the present invention are:

[0038] (1) Good environmental compatibility. The molecular structure of the imidazole-based ionic liquid corrosion inhibitor of the present invention does not contain elements such as P and S, and it has good environmental compatibility. The imidazole-based ionic liquid corrosion inhibitor of the present invention has high solubility in inorganic acids and can be dissolved in pickling solutions without the need for additional organic solvents. Therefore, it overcomes the environmental pollution and cost increase problems caused by the use of organic solvents in some existing organic corrosion inhibitors.

[0039] (2) The corrosion inhibitor requires a small amount of solution and has a high corrosion inhibition efficiency. The imidazole-based ionic liquid corrosion inhibitor of the present invention can achieve a corrosion inhibition efficiency of more than 95% at a concentration of 0.1 mmol / L (i.e., 40 mg / L) in inorganic acid.

[0040] (3) The corrosion inhibitor has a long duration of action and the corrosion inhibitor solution has stable performance. The imidazole-based ionic liquid corrosion inhibitor of the present invention can maintain a corrosion inhibition efficiency of over 90% at 30-60℃, and can also adapt to changes in inorganic acid concentration. In addition, the corrosion inhibition efficiency of the inhibitor hardly decreases after 48 hours of continuous action.

[0041] (4) The corrosion inhibitor has a wide range of applications for metallic materials. The imidazole-based ionic liquid corrosion inhibitor of the present invention not only exhibits excellent corrosion inhibition performance on low carbon steel (Q195, Q215, Q235, Q255 and Q275, etc.), but also exhibits good corrosion inhibition performance on other metals (such as copper, magnesium alloys, aluminum alloys, etc.), and has a wide range of applications. Attached Figure Description

[0042] Figure 1 The 1H NMR spectrum of 1-(4'-biphenylmethyl)-1H-imidazole prepared in Example 1.

[0043] Figure 2 The 1H NMR spectrum of 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-onium bromide prepared in Example 2.

[0044] Figure 3 The graph shows the relationship between the corrosion inhibition efficiency of Q235 steel after immersion in 1 mol / L hydrochloric acid containing 0.02-0.1 mmol / L of 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-onium bromide for 4 h at 30℃ and the concentration.

[0045] Figure 4The graph shows the relationship between the corrosion inhibition efficiency of Q235 steel and the concentration after immersion in 1 mol / L hydrochloric acid containing 0.02-0.1 mmol / L of 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-onium bromide for 4 h at 40℃.

[0046] Figure 5 The graph shows the relationship between the corrosion inhibition efficiency of Q235 steel after immersion in 1 mol / L hydrochloric acid containing 0.02-0.1 mmol / L of 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-onium bromide for 4 h at 50℃ and the concentration.

[0047] Figure 6 The graph shows the relationship between the corrosion inhibition efficiency of Q235 steel after immersion in 1 mol / L hydrochloric acid containing 0.02-0.1 mmol / L of 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-onium bromide for 4 h at 60℃ and the concentration.

[0048] Figure 7 The graph shows the relationship between the corrosion inhibition efficiency of Q235 steel and the concentration after immersion in 1 mol / L sulfuric acid containing 0.02-0.1 mmol / L of 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-onium bromide for 4 h at 30℃.

[0049] Figure 8 The graph shows the relationship between the corrosion inhibition efficiency of Q235 steel after immersion in 1 mol / L hydrochloric acid containing 0.02-1.0 mmol / L of 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-onium bromide for 4 h at 30℃ and the concentration. Detailed Implementation

[0050] This invention conducts a weight loss test on the coated material according to GB10124-88 (Metallic Materials Laboratory Uniform Corrosion Full Immersion Test Method).

[0051] All features disclosed in this specification, or all steps in all disclosed methods or processes, may be combined in any way, except for mutually exclusive features and / or steps.

[0052] Any feature disclosed in this specification, unless otherwise stated, may be replaced by other equivalent or similar features. That is, unless otherwise stated, each feature is merely one example of a series of equivalent or similar features.

[0053] Example 1

[0054] In a 250 mL round-bottom flask, 5 mmol of 4-bromomethylbiphenyl, 10 mmol of imidazole, and 10 mmol of potassium hydroxide were added and dissolved in 50 mL of isopropanol. The mixture was stirred and reacted in a water bath at 60 °C for 6 h. After cooling and filtration, the organic solvent was removed by rotary evaporation. The resulting solid was dissolved in 30 mL of dichloromethane and repeatedly extracted with water until the aqueous phase was neutral. The dichloromethane phase was then dried with anhydrous magnesium sulfate, filtered, and the solvent was evaporated to obtain a pale yellow solid, namely 1-(4'-biphenylmethyl)-1H-imidazole. The NMR spectrum is shown below. Figure 1 . 1 H NMR (600MHz, DMSO-d6, δ / ppm): 7.79 (s, 1H), 7.66-7.64 (m, 2H), 7.64 (d, J=2.0Hz, 2H), 7.45 (t, J= 7.7Hz,2H),7.36(d,J=7.4Hz,1H),7.34(d,J=8.2Hz,2H),7.22(s,1H),6.93(s,1H),5.24(s,2H).

[0055] Example 2

[0056] 5 mmol of 1-(4'-biphenylmethyl)-1H-imidazolium prepared in Example 1 and 5 mmol of ethyl bromoacetate were added to a 100 mL round-bottom flask, dissolved in 30 mL of chloroform, and reacted with stirring at 50 °C for 6 h. The solvent was evaporated, the mixture was washed three times with n-hexane, filtered, and dried under vacuum to obtain 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazolium-3-onium bromide. The NMR spectrum is shown below. Figure 2 . 1 H NMR (600MHz, DMSO-d6, δ / ppm): 9.45 (s, 1H), 7.97 (s, 1H), 7.85 (s, 1H), 7.72 (d, J = 8.3Hz, 2H), 7.67 (d, J = 7.2Hz, 2H), 7.56 (d, J = 8 .2Hz,2H),7.46(t,J=7.7Hz,2H),7.37(t,J=7.4Hz,1H),5.62(s,2H),5.33(s,2H),4.20(q,J=7.1Hz,2H),1.23(t,J=7.1Hz,3H).

[0057] Example 3

[0058] In this embodiment, hydrochloric acid was used as the inorganic acid, with a concentration of 1 mol / L and a volume of 200 mL. Different concentration gradients of 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-onium bromide (0.02-0.1 mmol / L) prepared in Example 2 were added to this inorganic acid solution to obtain a pickling solution. The Q235 steel to be cleaned was immersed in this pickling solution for 4 hours at 30°C. Experimental results are shown below. Figure 3 The highest corrosion inhibition efficiency obtained in the test was 96.32%.

[0059] Example 4

[0060] In this embodiment, hydrochloric acid was used as the inorganic acid, with a concentration of 1 mol / L and a volume of 200 mL. Different concentration gradients of 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-onium bromide (0.02-0.1 mmol / L) prepared in Example 2 were added to this inorganic acid solution to obtain a pickling solution. The Q235 steel to be cleaned was immersed in this pickling solution for 4 hours at 40°C. Experimental results are shown below. Figure 4 The highest corrosion inhibition efficiency obtained in the test was 95.59%.

[0061] Example 5

[0062] In this embodiment, hydrochloric acid was used as the inorganic acid, with a concentration of 1 mol / L and a volume of 200 mL. Different concentration gradients of 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-onium bromide (0.02-0.1 mmol / L) prepared in Example 2 were added to this inorganic acid solution to obtain a pickling solution. The Q235 steel to be cleaned was immersed in this pickling solution for 4 hours at 50°C. Experimental results are shown below. Figure 5 The highest corrosion inhibition efficiency obtained in the test was 93.91%.

[0063] Example 6

[0064] In this embodiment, hydrochloric acid was used as the inorganic acid, with a concentration of 1 mol / L and a volume of 200 mL. Different concentration gradients of 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-onium bromide (0.02-0.1 mmol / L) prepared in Example 2 were added to this inorganic acid solution to obtain a pickling solution. The Q235 steel to be cleaned was immersed in this pickling solution for 4 hours at 60°C. Experimental results are shown below. Figure 6 The highest corrosion inhibition efficiency obtained in the test was 92.50%.

[0065] Example 7

[0066] In this embodiment, sulfuric acid was used as the inorganic acid, with a concentration of 1 mol / L and a volume of 200 mL. Different concentration gradients of 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-onium bromide (0.02-0.1 mmol / L) prepared in Example 2 were added to this inorganic acid solution to obtain a pickling solution. The Q235 steel to be cleaned was immersed in this pickling solution for 4 hours at 30°C. Experimental results are shown below. Figure 7 The highest corrosion inhibition efficiency obtained in the test was 95.36%.

[0067] The above embodiments show that the imidazole-based ionic liquid corrosion inhibitor of this invention exhibits excellent corrosion inhibition effects in both hydrochloric acid and sulfuric acid, and also maintains excellent corrosion inhibition effect on Q235 steel at higher temperatures.

[0068] Example 8

[0069] In this embodiment, hydrochloric acid was used as the inorganic acid, with a concentration of 1-4 mol / L, and the volume of inorganic acid was 200 mL. 0.1 mmol of 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-onium bromide prepared in Example 2 was added to this inorganic acid solution to obtain a pickling solution. The Q235 steel to be cleaned was immersed in this pickling solution for 4 hours at 30°C. The test results are as follows:

[0070] Hydrochloric acid concentration (mol / L) 1 2 3 4 Corrosion inhibition efficiency (%) 96.32 95.36 92.25 91.35

[0071] The results of this embodiment show that the imidazole-based ionic liquid corrosion inhibitor of the present invention can adapt to a wide range of acid concentrations and can meet the requirements of the pickling industry.

[0072] Example 9

[0073] In this embodiment, hydrochloric acid with a concentration of 1 mol / L was used, and the volume of inorganic acid was 200 mL. 0.1 mmol of 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-onium bromide prepared in Example 2 was added to this inorganic acid solution to obtain a pickling solution. The corrosion inhibition efficiency of the Q235 steel to be cleaned was tested by immersing it in this pickling solution for different immersion times at 30°C. The test results are as follows:

[0074] Soaking time (h) 4 8 12 24 36 48 Corrosion inhibition efficiency (%) 96.32 96.89 97.35 98.12 98.34 98.45

[0075] The results of this embodiment show that the imidazole-based ionic liquid corrosion inhibitor of the present invention can exert a high-efficiency corrosion inhibition effect for a long time and can meet the long-term operation requirements of the pickling industry.

[0076] Example 10

[0077] In this embodiment, the solubility of 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-onium bromide was tested. The measured solubility of 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-onium bromide in water was 0.005 g / mL, and its solubility in 1 mol / L hydrochloric acid was 0.012 g / mL.

[0078] The results of this embodiment show that the imidazole-based ionic liquid corrosion inhibitor of this invention can be dissolved in pickling solution without the need for additional organic solvents, thus avoiding the environmental pollution and cost increases caused by the use of organic solvents in some existing organic corrosion inhibitors.

[0079] Example 11

[0080] In this embodiment, the limiting corrosion inhibition efficiency of 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-onium bromide was determined. The measured limiting corrosion inhibition efficiency of 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-onium bromide in 1 mol / L hydrochloric acid was 98.77%. However, considering that excessive dosage would lead to increased costs, the optimal dosage of 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-onium bromide was 0.1 mmol / L.

[0081] The results of this embodiment show that the imidazole-based ionic liquid corrosion inhibitor of the present invention can achieve its maximum corrosion inhibition efficiency with a very small amount of additive, and has the advantages of low dosage and high corrosion inhibition effect.

[0082] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention.

[0083] Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0084] This invention is not limited to the specific embodiments described above. The invention extends to any new feature or combination disclosed in this specification, as well as any new method or process step or combination disclosed herein.

Claims

1. A corrosion inhibitor of imidazole-based ionic liquid, 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-onium bromide, characterized in that, The structural formula of 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-onium bromide is: 。 2. A method for preparing 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazolium-3-onium bromide, an imidazolium-based ionic liquid corrosion inhibitor, characterized in that... Includes the following steps: (1) Add 4-bromomethylbiphenyl, imidazole, potassium hydroxide and organic solvent to a round-bottom flask and stir the reaction under water bath heating conditions; (2) Cool and filter, remove organic solvent by rotary evaporation, dissolve the obtained solid in organic solvent, extract repeatedly with water until the aqueous phase is neutral; then dry the organic phase with anhydrous magnesium sulfate, filter, evaporate the solvent to obtain pale yellow 1-(4'-biphenylmethyl)-1H-imidazole. (3) Carefully add the 1-(4'-biphenylmethyl)-1H-imidazolium and ethyl bromoacetate obtained in step (2) into a round-bottom flask, then add an organic solvent and react under stirring and heating conditions; (4) Evaporate the solvent to obtain a pale yellow oily substance; wash the oily substance with n-hexane, petroleum ether or ethyl acetate, filter, and vacuum dry the oily substance to obtain 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-onium bromide.

3. The method for preparing the imidazole-based ionic liquid corrosion inhibitor 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-onium bromide as described in claim 2, characterized in that: In step (1), the molar ratio of 4-bromomethylbiphenyl, imidazole and potassium hydroxide is 1:1-3:1-3; the organic solvent used is any one of methanol, ethanol, isopropanol and acetonitrile; the stirring and heating temperature is 40-80℃ and the reaction time is 4-8h.

4. The method for preparing the imidazole-based ionic liquid corrosion inhibitor 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-onium bromide as described in claim 2, characterized in that: In step (2), the organic solvent used to dissolve the solid is either dichloromethane or trichloromethane.

5. The method for preparing the imidazole-based ionic liquid corrosion inhibitor 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-onium bromide as described in claim 2, characterized in that: In step (3), the molar ratio of 1-(4'-biphenylmethyl)-1H-imidazolium to ethyl bromoacetate is 1:1-1.3; the organic solvent is any one of methanol, ethanol, isopropanol, and acetonitrile; the stirring and heating temperature is 30-60℃, and the reaction time is 4-8h.

6. The application of the imidazole-based ionic liquid corrosion inhibitor 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-onium bromide as described in claim 1 in metal pickling corrosion inhibitors.

7. The application as described in claim 6, characterized in that... The process includes the following steps: adding 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-onium bromide to an inorganic acid to obtain a pickling solution, which is then used for pickling metallic materials.

8. The application as described in claim 7, characterized in that: The inorganic acid is any one of hydrochloric acid, sulfuric acid, phosphoric acid, hydrofluoric acid, and nitric acid; the metallic material is any one of low-carbon steel, magnesium alloy, copper, and aluminum alloy.

9. The application as described in claim 7 or 8, characterized in that: The concentration of inorganic acid in the pickling solution is 1-4 mol / L; the concentration of 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-onium bromide is 0.02-0.2 mmol / L.

10. The application according to claim 6 or 9, characterized in that, The pickling temperature is 30-60℃, and the pickling time is 4-48h.

Images