Preparation method and application of imidazolyl ionic liquid corrosion inhibitor

Abstract

The invention relates to the field of chemical materials, in particular to metal protection in the metal pickling industry, and particularly relates to a preparation method and application of an imidazolyl ionic liquid corrosion inhibitor. The chemical structural formula of the imidazolyl ionic liquid corrosion inhibitor brominated 1-(4 '-biphenyl methyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazole-3-onium is # imgabs0. The imidazolyl ionic liquid corrosion inhibitor disclosed by the invention can be used for protecting metal materials from acid pickling corrosion, and can well bear the change of various cleaning conditions; particularly, the acid pickling corrosion inhibition liquid has the technical characteristics of low preparation cost, good solubility, good environmental compatibility, small corrosion inhibitor dosage, high corrosion inhibition efficiency, stable corrosion inhibition liquid performance, long lasting action time and the like, is wide in application range, and is worthy of large-scale popularization and application.

Description

Technical Field

[0001] The invention relates to the field of chemical materials, in particular to metal protection in the metal pickling industry, and specifically to a preparation method of an imidazole-based ionic liquid corrosion inhibitor and application thereof. Background Art

[0002] Metal materials are widely used in building structures, chemical pipelines, water supply systems, machinery and equipment due to their excellent machining properties. These equipment will be degreased and rusted after running for a period of time. Usually, inorganic acids such as hydrochloric acid and sulfuric acid are added during the degreasing and rusting process. However, metal materials are susceptible to corrosion when exposed to acidic environments for a long time, which will cause huge waste of resources and economic losses.

[0003] In the past few decades, various anti-corrosion methods have been applied to the protection of metal materials, such as protective coatings, cathodic protection, anodic protection, adding corrosion inhibitors, etc. Among them, adding corrosion inhibitors is one of the most commonly used methods to prevent or reduce the corrosion of metal materials in acidic media because of its convenience and high efficiency.

[0004] Corrosion inhibitors are generally divided into inorganic corrosion inhibitors and organic corrosion inhibitors. Inorganic corrosion inhibitors include cadmium salts, arsenic salts, nitrites, chromates, phosphates, dichromates and alkali metal sulfides, etc. They are added to corrosive solutions to protect various metal materials and their alloy materials. However, these inorganic corrosion inhibitors have defects such as large addition amount and poor environmental friendliness, which limits their scope of use. Heteroatoms such as N, O, S or unsaturated bonds in organic corrosion inhibitors can be adsorbed on the metal surface to form a protective film on the metal surface. Although some organic corrosion inhibitors have been widely used due to their significant effects, organic corrosion inhibitors with high toxicity do not meet the requirements of environmental protection laws and regulations and are gradually being eliminated.

[0005] Some of the organic corrosion inhibitors currently developed have poor water solubility due to the aromatic ring structure, and the corrosion inhibition effect is not ideal. It is generally believed that the concentration of organic corrosion inhibitors in acidic corrosive media to achieve the required corrosion inhibition should generally be less than 500ppm, but the dosage of some organic corrosion inhibitors still far exceeds this concentration requirement. Therefore, the design and synthesis of the molecular structure of high-efficiency, low-toxicity, and low-cost organic corrosion inhibitors is a research and development hotspot and technical difficulty 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, large liquid phase range, low volatility, high thermal stability, high water solubility and non-flammability. In the future, they will gradually become the main substitute for existing metal pickling organic corrosion inhibitors. Summary of the invention

[0007] To solve the above problems, the purpose of the present invention is to provide an imidazolyl ionic liquid corrosion inhibitor and a preparation method thereof. The imidazolyl ionic liquid corrosion inhibitor is 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-ium bromide, which is used as a metal pickling corrosion inhibitor. The imidazolyl ionic liquid has good water solubility, acid solubility and excellent corrosion inhibition performance.

[0008] In order to achieve the above invention object, the specific technical solution of the present invention is:

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

[0010]

[0011] An imidazole-based ionic liquid corrosion inhibitor, 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-ium bromide, is prepared by a method comprising 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 into a round-bottom flask and stir under heating in a water bath.

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

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

[0017] (4) The organic solvent is evaporated to obtain a light yellow oily substance. The oily substance is washed with n-hexane, petroleum ether or ethyl acetate, filtered, and dried in vacuo to obtain 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-ium bromide.

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

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

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

[0021] As a preferred embodiment of the present application, the organic solvent for dissolving the solid in step (2) is any one of dichloromethane and chloroform.

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

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

[0024] As a preferred embodiment of the present application, the heating condition in step (3) is 30-60°C.

[0025] Another invention object of the present application is to use the above-mentioned imidazole-based ionic liquid corrosion inhibitor 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-ium bromide in the field of metal pickling.

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

[0027] A certain amount of 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-ium bromide is added to an inorganic acid to obtain an acid pickling and corrosion inhibiting solution, and the acid pickling and corrosion inhibiting solution is used for pickling of various metal materials.

[0028] As a better implementation in the present application, the inorganic acid is any one of hydrochloric acid, sulfuric acid, phosphoric acid, hydrofluoric acid, nitric acid, and carbonic acid.

[0029] As a better implementation in the present application, the concentration of the inorganic acid in the pickling and corrosion inhibition solution is 1-4 mol / L.

[0030] As a better implementation mode in the present application, the metal material is any one of low carbon steel, magnesium alloy, copper and aluminum alloy.

[0031] As a better implementation in the present application, the concentration of 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-ium bromide in the inorganic acid in the pickling and corrosion inhibition solution is 0.02-0.2 mmol / L.

[0032] As a better implementation in the present application, the pickling temperature is 30-60°C, and the pickling immersion time is 4-48h.

[0033] The 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazole-3-ium bromide of the present invention can exert a good corrosion inhibition effect in 1-4mol / L of inorganic acid. At the same time, the concentration of the 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazole-3-ium bromide in the inorganic acid is 0.02-0.2mmol / L, which has the characteristics of small dosage and high corrosion inhibition efficiency. In addition, the 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazole-3-ium bromide of the present invention can withstand changes in various cleaning conditions (such as temperature, acid concentration, soaking time, etc.), and can meet the requirements of most pickling industries.

[0034] The 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-ium bromide of the present invention can inhibit the corrosion of various metals (such as low-carbon steel, magnesium alloy, copper, aluminum alloy, etc.) in acidic medium. Among them, especially for low-carbon steel, such as Q195, Q215, Q235, Q255 and Q275, it shows excellent corrosion inhibition performance.

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

[0036] Further, the present invention provides an application of the corrosion inhibition effect of 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-ium bromide in a metal pickling solution. Specifically, 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-ium bromide is added to an inorganic acid (hydrochloric acid, sulfuric acid, etc.) with a concentration of 1-4 mol / L to a concentration range of 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 present invention has the following beneficial effects:

[0038] (1) Good environmental compatibility. The molecular structure of the imidazolyl ionic liquid corrosion inhibitor of the present invention does not contain elements such as P and S, and it has good compatibility with the environment. The imidazolyl ionic liquid corrosion inhibitor of the present invention has high solubility in inorganic acid and can be dissolved in the pickling solution without adding an organic solvent, thus overcoming the problems of environmental pollution and cost increase caused by the use of organic solvents in some existing organic corrosion inhibitors.

[0039] (2) Small amount of corrosion inhibitor used, high corrosion inhibition efficiency. The imidazolyl ionic liquid corrosion inhibitor of the present invention can achieve a corrosion inhibition efficiency of more than 95% when the concentration is 0.1 mmol / L (ie 40 mg / L) in inorganic acid.

[0040] (3) The corrosion inhibitor has a long duration of action and the corrosion inhibitor has stable performance. The imidazolyl ionic liquid corrosion inhibitor of the present invention can maintain a corrosion inhibition efficiency of more than 90% at 30-60°C and can also adapt to changes in the concentration of inorganic acids. In addition, the corrosion inhibition efficiency of the corrosion inhibitor is almost unchanged after 48 hours of continuous action.

[0041] (4) The corrosion inhibitor has a wide range of applications for metal materials. The imidazolyl ionic liquid corrosion inhibitor of the present invention not only exhibits excellent corrosion inhibition performance for low carbon steel (Q195, Q215, Q235, Q255 and Q275, etc.), but also exhibits good corrosion inhibition performance for other metals (such as copper, magnesium alloy, aluminum alloy, etc.), and has a wide range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 This is the hydrogen nuclear magnetic resonance spectrum of 1-(4'-biphenylmethyl)-1H-imidazole prepared in Example 1.

[0043] Figure 2 This is the hydrogen nuclear magnetic resonance spectrum of 1-(4'-biphenylylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-ium bromide prepared in Example 2.

[0044] Figure 3 This is a graph showing the relationship between the corrosion inhibition efficiency and the concentration of Q235 steel after it is immersed in 1 mol / L hydrochloric acid containing 0.02-0.1 mmol / L 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-ium bromide at 30°C for 4 hours.

[0045] Figure 4This is a graph showing the relationship between the corrosion inhibition efficiency and the concentration of Q235 steel after it is immersed in 1 mol / L hydrochloric acid containing 0.02-0.1 mmol / 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-ium bromide at 40°C for 4 hours.

[0046] Figure 5 This is a graph showing the relationship between the corrosion inhibition efficiency and the concentration of Q235 steel after it is immersed in 1 mol / L hydrochloric acid containing 0.02-0.1 mmol / L 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-ium bromide at 50°C for 4 hours.

[0047] Figure 6 This is a graph showing the relationship between the corrosion inhibition efficiency and the concentration of Q235 steel after it is immersed in 1 mol / L hydrochloric acid containing 0.02-0.1 mmol / L 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-ium bromide at 60°C for 4 hours.

[0048] Figure 7 This is a graph showing the relationship between the corrosion inhibition efficiency and the concentration of Q235 steel after it is immersed in 1 mol / L sulfuric acid containing 0.02-0.1 mmol / L 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-ium bromide at 30°C for 4 hours.

[0049] Figure 8 This is a graph showing the relationship between the corrosion inhibition efficiency and the concentration of Q235 steel after it is immersed in 1 mol / L hydrochloric acid containing 0.02-1.0 mmol / L 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-ium bromide at 30°C for 4 hours. DETAILED DESCRIPTION

[0050] The invention carries out the hanging piece weight loss experiment according to GB10124-88 (metal material laboratory uniform corrosion full immersion test method).

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

[0052] Any feature disclosed in this specification, unless otherwise stated, can be replaced by other equivalent or alternative features with similar purposes. That is, unless otherwise stated, each feature is only an example of a series of equivalent or similar features.

[0053] Example 1

[0054] Add 5mmol 4-bromomethylbiphenyl, 10mmol imidazole and 10mmol potassium hydroxide to a 250mL round-bottom flask and dissolve with 50mL isopropanol. Stir the reaction for 6h in a water bath at 60℃. Cool and filter, remove the organic solvent by rotary evaporation, dissolve the obtained solid in 30mL dichloromethane, and extract repeatedly with water until the water phase is neutral. Then dry the dichloromethane phase with anhydrous magnesium sulfate, filter, and evaporate the solvent to obtain a light yellow solid, i.e. 1-(4'-biphenylmethyl)-1H-imidazole. See the nuclear magnetic resonance spectrum for details. 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-imidazole prepared in Example 1 and 5 mmol of ethyl bromoacetate were added to a 100 mL round-bottom flask, dissolved with 30 mL of chloroform, and stirred for 6 h under heating conditions at 50°C. The solvent was evaporated, washed three times with n-hexane, filtered, and vacuum dried to obtain 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazole-3-ium bromide. The nuclear magnetic resonance spectrum is shown in 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 is used as the inorganic acid with a concentration of 1 mol / L and an amount of 200 mL of the inorganic acid. 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazole-3-ium bromide (0.02-0.1 mmol / L) prepared in Example 2 with different concentration gradients is added to the inorganic acid solution to obtain an acid pickling solution. The Q235 steel to be cleaned is immersed in the acid pickling solution for 4 hours at 30°C. The experimental results are shown in Figure 3 The highest corrosion inhibition efficiency obtained in the test is 96.32%.

[0059] Example 4

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

[0061] Example 5

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

[0063] Example 6

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

[0065] Example 7

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

[0067] The above examples show that the imidazolyl ionic liquid corrosion inhibitor of the present invention can exhibit excellent corrosion inhibition effect in both hydrochloric acid and sulfuric acid, and can also have excellent corrosion inhibition effect on Q235 steel at higher temperatures.

[0068] Example 8

[0069] In this embodiment, hydrochloric acid is used as the inorganic acid, the concentration is 1-4 mol / L, and the amount of the inorganic acid is 200 mL. To the inorganic acid solution, 0.1 mmol of 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazole-3-ium bromide prepared in Example 2 is added to obtain an acid pickling solution. At 30°C, the Q235 steel to be cleaned is soaked in the acid pickling solution for 4 hours. 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 imidazolyl ionic liquid corrosion inhibitor of the present invention can adapt to a wider range of acid concentrations and can meet the requirements of the pickling industry.

[0072] Example 9

[0073] In this embodiment, hydrochloric acid is used as the inorganic acid, the concentration is 1 mol / L, and the amount of the inorganic acid is 200 mL. To the inorganic acid solution, 0.1 mmol of 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazole-3-ium bromide prepared in Example 2 is added to obtain an acid pickling solution. At 30°C, the Q235 steel to be cleaned is immersed in the acid pickling solution for different immersion times to test its corrosion inhibition efficiency. 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 imidazolyl 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 example, the solubility of 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-ium bromide was tested. According to actual measurements, the solubility of 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-ium bromide in water is 0.005 g / mL, and the solubility in 1 mol / L hydrochloric acid is 0.012 g / mL.

[0078] The results of this embodiment show that the imidazolyl ionic liquid corrosion inhibitor of this invention can be dissolved in the pickling solution without adding an organic solvent, thereby avoiding the environmental pollution and cost increase problems caused by the use of organic solvents in some existing organic corrosion inhibitors.

[0079] Embodiment 11

[0080] In this embodiment, the limiting corrosion inhibition efficiency of 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazole-3-ium bromide is determined. According to actual measurement, the limiting corrosion inhibition efficiency of 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazole-3-ium bromide in 1mol / L hydrochloric acid is 98.77%. However, considering that excessive dosage will increase the cost, the optimal dosage of 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazole-3-ium bromide is 0.1mmol / L.

[0081] The results of this embodiment show that the imidazolyl ionic liquid corrosion inhibitor of the present invention can reach its ultimate corrosion inhibition efficiency at a very small addition amount, and has the advantages of small 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 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 present invention will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

[0084] The present invention is not limited to the above-mentioned specific embodiments, but extends to any new features or any new combination disclosed in this specification, as well as any new method or process steps or any new combination disclosed.

Claims

1. An imidazole-based ionic liquid corrosion inhibitor, 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-ium bromide, characterized in that: The structural formula of 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-ium bromide is:

2. A method for preparing an imidazole-based ionic liquid corrosion inhibitor 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-ium bromide, characterized in that The following steps are involved: (1) Add 4-bromomethylbiphenyl, imidazole, potassium hydroxide and an organic solvent into a round-bottom flask, and stir to react under heating in a water bath; (2) cooling and filtering, removing the organic solvent by rotary evaporation, dissolving the obtained solid with an organic solvent, and repeatedly extracting with water until the aqueous phase is neutral; then drying the organic phase with anhydrous magnesium sulfate, filtering, and evaporating the solvent to obtain light yellow 1-(4'-biphenylmethyl)-1H-imidazole; (3) carefully adding the 1-(4'-biphenylmethyl)-1H-imidazole and ethyl bromoacetate obtained in step (2) into a round-bottom flask, and then adding an organic solvent to react under stirring and heating conditions; (4) The solvent is evaporated to obtain a light yellow oily substance; the oily substance is washed with n-hexane, petroleum ether or ethyl acetate, filtered, and the oily substance is dried under vacuum to obtain 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-ium bromide.

3. A method for preparing an imidazolyl-based ionic liquid corrosion inhibitor 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-ium bromide as claimed 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° C., and the reaction time is 4-8 hours.

4. A method for preparing an imidazolyl-based ionic liquid corrosion inhibitor 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-ium bromide as claimed in claim 2, characterized in that: The organic solvent for dissolving the solid in step (2) is any one of dichloromethane and chloroform.

5. A method for preparing an imidazolyl-based ionic liquid corrosion inhibitor 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-ium bromide as claimed in claim 2, characterized in that: In step (3), the molar ratio of 1-(4'-biphenylmethyl)-1H-imidazole 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° C., and the reaction time is 4-8 hours.

6. Use of the imidazolyl-based ionic liquid corrosion inhibitor 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-ium bromide as claimed in claim 1 in a metal pickling corrosion inhibitor.

7. The use according to claim 6, characterized in that The method comprises the following steps: adding 1-(4'-biphenylmethyl)-3-(2-ethoxy-2-oxoethyl)-1H-imidazol-3-ium bromide into an inorganic acid to obtain an acid washing solution, and using the acid washing solution for acid washing of metal materials.

8. The use according to claim 7, characterized in that: The inorganic acid is any one of hydrochloric acid, sulfuric acid, phosphoric acid, hydrofluoric acid, nitric acid, and carbonic acid; the metal material is any one of low-carbon steel, magnesium alloy, copper, and aluminum alloy.

9. The use according to claim 7 or 8, characterized in that: The concentration of the 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-ium bromide is 0.02-0.2 mmol / L.

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

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