Preparation method and application of quaternary ammonium salt type high-temperature acidification corrosion inhibitor

Abstract

This invention relates to the field of oilfield chemical additives technology, and discloses a method for preparing a 1-benzyl-10-phenylpyrrolo[1,2-a:3,4-b']dipyrazine-1-onium type quaternary ammonium salt high-temperature acidizing corrosion inhibitor. The method uses 2,2'-piperazine as the starting material, which undergoes a quaternization reaction with benzyl bromide to obtain a quaternary ammonium salt intermediate. The obtained intermediate undergoes an oxidative cyclization reaction with benzaldehyde and manganese dioxide in a dichloromethane system. After separation, drying, and purification, the target product is obtained. The preparation process of this invention is simple and easy to control, the product is easy to purify, and it is suitable for industrial production. It exhibits good synergistic effects with additives, excellent water solubility and compatibility, can stabilize and protect steel, reduce construction risks, and is suitable for various high-temperature acidizing operations.

Description

Technical Field

[0001] This invention relates to the field of oilfield chemical additives technology, specifically to a quaternary ammonium salt type high-temperature acidification corrosion inhibitor, its preparation method, and its application in acidification systems. Background Technology

[0002] Acidizing is a core technology for increasing production and efficiency in oil and gas fields. By injecting acid into the formation to dissolve rock minerals and widen oil flow channels, it can effectively reduce extraction resistance and improve formation permeability. High-concentration hydrochloric acid and other acids can severely corrode N80 casing steel, easily causing equipment damage and construction risks. Adding corrosion inhibitors is a key technical means to control acid corrosion. Quaternary ammonium salt corrosion inhibitors, with their good solubility and temperature resistance, have become the mainstream protective materials for high-temperature acidizing conditions. Developing high-performance quaternary ammonium salt corrosion inhibitors is crucial to ensuring the safety of acidizing operations.

[0003] Existing high-temperature acidizing corrosion inhibitors have been publicly disclosed. CN119192072A discloses a high-temperature acidizing corrosion inhibitor for oilfields, which uses aminochloropropanol hydrochloride, aldehyde compounds, quinoline, etc. as raw materials to prepare a corrosion inhibitor containing betaine groups through a multi-step reaction. It can form a hydrophobic protective film on the steel surface and has a corrosion inhibition effect in a 20% hydrochloric acid system at 150℃. However, application data at higher temperatures is not disclosed, and the upper limit of temperature resistance is significantly limited. CN121362572A discloses a multi-purpose high-temperature acidizing corrosion inhibitor for oilfields, which uses a bis-Schiff base quaternary ammonium salt as the main agent and is compounded with amides, alkynols, emulsifiers, etc. It can achieve metal protection in a hydrochloric acid system at 160℃. However, it also lacks performance verification under ultra-high temperature conditions.

[0004] Current quaternary ammonium salt corrosion inhibitors suffer from technical limitations. Most products can only withstand temperatures up to 150℃-160℃, making them unsuitable for the 200℃ ultra-high temperature deep well acidification environment. Furthermore, their simple molecular structures lead to easy film detachment under high temperature and strong acid conditions, resulting in rapid degradation of their corrosion inhibition performance. Some products have complex synthesis processes, with products exhibiting similar polarities to raw materials, making separation and purification difficult. The compatibility of compound systems is poor, making it difficult to maintain stable protective effects in 15%-20% high-concentration hydrochloric acid. As oil and gas extraction expands into deep and ultra-deep wells, ultra-high temperature and high-acid corrosion conditions place higher demands on the temperature resistance, film stability, and compatibility of corrosion inhibitors. Existing technologies cannot meet the needs of field applications, making the development of novel ultra-high temperature quaternary ammonium salt acidification corrosion inhibitors an urgent industry requirement. Summary of the Invention

[0005] To address the shortcomings of existing quaternary ammonium salt acidification corrosion inhibitors, such as low upper temperature resistance, easy detachment of adsorption film at high temperatures, difficulty in purification, and inability to adapt to high-concentration hydrochloric acid conditions at 200℃, this invention provides a method for preparing a quaternary ammonium salt-type high-temperature acidification corrosion inhibitor and its application.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A method for preparing a quaternary ammonium salt type high-temperature acid corrosion inhibitor includes the following steps: S1. Add 2,2'-piperazine to N,N-dimethylformamide solvent and stir until completely dissolved to form a homogeneous reaction solution; S2. Add benzyl bromide dropwise to the solution obtained in S1, control the reaction temperature at 25℃ to 50℃, and continue stirring for 24h-36h. S3. Cool the reaction system obtained in S2 to room temperature, perform vacuum filtration, collect the solid product, and dry the solid product in a dry environment for 24 hours to obtain intermediate solid material. S4. Add the intermediate solid material obtained in S3 to dichloromethane solvent and stir until completely dissolved to form a clear intermediate solution. S5. Add benzaldehyde and manganese dioxide to the intermediate solution obtained in S4, stir and mix evenly to form a multi-component reaction system. S6. Place the multi-component reaction system obtained in S5 at room temperature and stir continuously for 24-36 hours to allow the system to complete the synergistic reaction of oxidation cyclization and quaternization. S7. Cool the reaction system obtained in S6 to room temperature, perform vacuum filtration to remove insoluble solid impurities, and collect the target product in the filtrate. S8. Place the target product obtained in S7 into a constant temperature drying device and dry it continuously for 24 hours to remove residual solvent and moisture. S9. The dried product obtained in S8 is purified to obtain high-purity 1-benzyl-10-phenylpyrrolo[1,2-a:3,4-b']dipyrazine-1-onium, which is a quaternary ammonium salt type high-temperature acidification corrosion inhibitor.

[0007] Preferably, the ratio of 2,2'-piperazine to N,N-dimethylformamide in S1 is 0.8g:10mL, the stirring speed is controlled at 300r / min-600r / min, and the dissolution process is carried out in a closed container to avoid solvent evaporation.

[0008] Preferably, the dropping rate of benzyl bromide in S2 is controlled at 0.1 mL / min-0.3 mL / min, the added volume of benzyl bromide is 0.6 mL, the reaction process is carried out in the dark and in a closed environment to prevent oxidation and decomposition of the raw materials.

[0009] Preferably, the filtration operation in S3 uses a vacuum filtration device, the filtration time lasts for 15-30 minutes, the drying temperature is controlled at 40℃-60℃, and the relative humidity of the drying environment is less than 30%.

[0010] Preferably, in S4, the ratio of intermediate solid material to dichloromethane is 20 mL of dichloromethane for every 0.8 g of initial 2,2'-piperazine, and the mixture is stirred until no visible solid particles are visible and the system is homogeneous and transparent.

[0011] Preferably, the volume of benzaldehyde added in S5 is 0.5 mL, and the mass of manganese dioxide added is 0.5 g. Benzaldehyde and manganese dioxide are added in steps, with benzaldehyde added first and stirred for 10 min, and then manganese dioxide added and stirred for another 10 min.

[0012] Preferably, the stirring speed in S6 is controlled at 400r / min-700r / min, the entire reaction is carried out under normal pressure and closed conditions, the ambient temperature is maintained at 25℃, and there is no direct external light source.

[0013] Preferably, in step S7, qualitative filter paper with a pore size of 10μm-20μm is used for vacuum filtration. The vacuum filtration process is repeated twice to remove solid manganese dioxide and other insoluble impurities.

[0014] Preferably, the drying temperature in S8 is 50℃-70℃, the vacuum degree is controlled at 0.08MPa-0.095MPa, and the purification in S9 is carried out by recrystallization, with the solvent being a mixture of ethanol and dichloromethane, and the recrystallization is performed twice.

[0015] Preferably, the corrosion inhibitor is compounded with one or more of potassium iodide, surfactant, alkynol derivative, trivalent metal salt, unsaturated aldehyde, and cuprous iodide, and added to a hydrochloric acid solution with a mass fraction of 15%-20% to form a corrosion inhibition system, which is applied to high-temperature acidification operations at 200℃ to provide corrosion protection for N80 steel.

[0016] The present invention has the following beneficial effects: This invention employs a heteroatom polycyclic structure to design quaternary ammonium salt molecules, which can form a strong coordination adsorption film on the steel surface. The film is dense and uniform, effectively blocking the contact between acid and the metal substrate, and comprehensively inhibiting electrochemical corrosion and uniform corrosion.

[0017] The corrosion inhibitor molecules possess excellent thermal stability, maintaining their molecular structure integrity in ultra-high temperature acidification environments. The adsorption membrane is not easily desorbed or damaged, breaking through the temperature resistance bottleneck of traditional corrosion inhibitors and meeting the protection needs of extreme high temperature conditions.

[0018] The preparation process is mild and simple, the reaction conditions are easy to control, the raw materials are readily available and have high conversion efficiency, and the polarity difference between the product and the raw materials is significant. Separation and purification can be achieved through simple operation, making it suitable for industrial mass production.

[0019] The corrosion inhibitor exhibits good synergistic effects with various corrosion inhibitors, and the combination can enhance the protective performance of the corrosion inhibition system, making it suitable for use in acidification systems of different concentrations of hydrochloric acid.

[0020] The corrosion inhibitor has excellent water solubility and dispersibility. It can be quickly and uniformly dispersed in high-concentration hydrochloric acid systems without stratification, precipitation, or agglomeration. It also has excellent compatibility with acidification solutions, ensuring stable and convenient on-site construction.

[0021] Corrosion inhibitors have a wide range of applications and can meet the protection requirements of ultra-high temperature deep well acidizing operations. They can effectively extend the service life of steel, reduce equipment corrosion and construction safety risks, and provide reliable support for high-temperature acidizing production enhancement processes. Attached Figure Description

[0022] Figure 1 A schematic diagram illustrating the preparation process of the quaternary ammonium salt type corrosion inhibitor proposed in this invention; Figure 2 The infrared spectrum of the quaternary ammonium salt corrosion inhibitor proposed in this invention; Figure 3 The 1H NMR spectrum of the quaternary ammonium salt corrosion inhibitor proposed in this invention; Figure 4 This is a Tafel curve of the quaternary ammonium salt corrosion inhibitor proposed in this invention; Figure 5 The AC impedance curve of the quaternary ammonium salt corrosion inhibitor proposed in this invention is shown. Figure 6 SEM image (10 μm) of the uncorroded N80 steel sheet proposed in this invention. Figure 7 SEM image (5μm) of the N80 steel sheet after corrosion as proposed in this invention; Figure 8 The image shows a 10μm SEM image of the N80 steel sheet after corrosion, as proposed in this invention. Detailed Implementation

[0023] This specific embodiment details the preparation method of a quaternary ammonium salt-type high-temperature acidification corrosion inhibitor and its application in acidification systems. The entire preparation process is completed in a closed reaction vessel under normal pressure, with the ambient temperature controlled at 20℃-30℃. All raw materials used are of analytical grade, with a moisture content of less than 0.5% and no visible mechanical impurities. The core innovation of this invention lies in using 2,2'-piperazine as the starting material, and successively undergoing benzyl quaternization and oxidative cyclization reactions to obtain a 1-benzyl-10-phenylpyrrolo[1,2-a:3,4-b']dipyrazine-1-onium salt compound. This structure has polycyclic conjugation and multi-active-site coordination characteristics, which can significantly improve the adsorption stability and corrosion inhibition performance under high-temperature and strong acid environments. This embodiment includes three sets of preferred examples and one set of comparative examples. All steps are fully elaborated, the process parameters are comprehensively detailed, and all technical contents are covered. The prepared corrosion inhibitor can stably exert a protective effect in a 15%-20% hydrochloric acid system at 200℃.

[0024] Example 1 S1. Add 0.8g of 2,2'-piperazine to a sealed reaction vessel containing 10mL of N,N-dimethylformamide, turn on the stirrer, set the stirring speed to 400r / min, and continue stirring until the solid is completely dissolved to form a homogeneous and transparent reaction solution.

[0025] S2. Add 0.6 mL of benzyl bromide dropwise to the above reaction solution at a rate of 0.2 mL / min. After the addition is complete, raise the system temperature to 50 °C, keep the stirring speed constant, and react continuously for 24 h under light-proof and sealed conditions to complete the quaternization reaction.

[0026] S3. Allow the reaction system to cool naturally to room temperature, start the vacuum filtration device, maintain the filtration time for 20 minutes, and collect the obtained solid product. Place the solid product in a constant temperature drying device, control the temperature at 50℃, and dry continuously for 24 hours to obtain the intermediate solid material.

[0027] S4. Add the above intermediate solid material to a reaction vessel containing 20 mL of dichloromethane, start stirring, set the stirring speed to 500 r / min, and stir until the solid is completely dissolved to form a homogeneous intermediate solution.

[0028] S5. First, add 0.5 mL of benzaldehyde to the intermediate solution and stir for 10 min. Then add 0.5 g of manganese dioxide and continue stirring for 10 min to ensure that all materials are fully mixed and form a homogeneous multi-component reaction system.

[0029] S6. Place the multi-component reaction system at room temperature, maintain a stirring speed of 600 r / min, and react continuously for 24 h under normal pressure, sealed and dark conditions to complete the oxidation cyclization and molecular reconstruction process.

[0030] S7. Cool the reaction system to room temperature, and perform vacuum filtration using qualitative filter paper with a pore size of 15 μm. Repeat the filtration twice to remove insoluble solid impurities and collect the target product in the filtrate.

[0031] S8. Place the target product into a vacuum drying device, control the temperature at 60℃ and the vacuum degree at 0.09MPa, and dry continuously for 24 hours.

[0032] S9. The dried product was purified by recrystallization twice using a mixed solvent of ethanol and dichloromethane to finally obtain high-purity 1-benzyl-10-phenylpyrrolo[1,2-a:3,4-b']dipyrazine-1-onium, which is a quaternary ammonium salt type high-temperature acidification corrosion inhibitor.

[0033] S10. Measure 183 mL of concentrated hydrochloric acid (37% by mass), add 318 mL of deionized water, and mix thoroughly to prepare a 15% hydrochloric acid solution. Add 10 g of the above corrosion inhibitor, 2.5 g of potassium iodide, 5 g of surfactant, 10 g of alkynol derivative, and 2.5 g of trivalent metal salt to the hydrochloric acid solution, stir thoroughly to obtain the corrosion inhibition system, and perform corrosion protection application at 200℃ for 4 hours.

[0034] Example 2 S1. Add 0.8g of 2,2'-piperazine to a sealed reaction vessel containing 10mL of N,N-dimethylformamide, turn on the stirrer, set the stirring speed to 450r / min, and continue stirring until the solid is completely dissolved to form a homogeneous and transparent reaction solution.

[0035] S2. Add 0.6 mL of benzyl bromide dropwise to the above reaction solution at a rate of 0.15 mL / min. After the addition is complete, raise the system temperature to 40 °C, keep the stirring speed constant, and react continuously for 30 h under light-proof and sealed conditions to complete the quaternization reaction.

[0036] S3. Allow the reaction system to cool naturally to room temperature, start the vacuum filtration device, maintain the filtration time for 25 minutes, and collect the obtained solid product. Place the solid product in a constant temperature drying device, control the temperature at 55℃, and dry continuously for 24 hours to obtain the intermediate solid material.

[0037] S4. Add the above intermediate solid material to a reaction vessel containing 20 mL of dichloromethane, start stirring, set the stirring speed to 550 r / min, and stir until the solid is completely dissolved to form a homogeneous intermediate solution.

[0038] S5. First, add 0.5 mL of benzaldehyde to the intermediate solution and stir for 10 min. Then add 0.5 g of manganese dioxide and continue stirring for 10 min to ensure that all materials are fully mixed and form a homogeneous multi-component reaction system.

[0039] S6. Place the multi-component reaction system at room temperature, maintain a stirring speed of 650 r / min, and react continuously for 30 h under normal pressure, sealed and dark conditions to complete the oxidation cyclization and molecular reconstruction process.

[0040] S7. Cool the reaction system to room temperature, and perform vacuum filtration using qualitative filter paper with a pore size of 15 μm. Repeat the filtration twice to remove insoluble solid impurities and collect the target product in the filtrate.

[0041] S8. Place the target product into a vacuum drying device, control the temperature at 65℃ and the vacuum degree at 0.085MPa, and dry continuously for 24 hours.

[0042] S9. The dried product was purified by recrystallization twice using a mixed solvent of ethanol and dichloromethane to finally obtain high-purity 1-benzyl-10-phenylpyrrolo[1,2-a:3,4-b']dipyrazine-1-onium, which is a quaternary ammonium salt type high-temperature acidification corrosion inhibitor.

[0043] S10. Measure 253 mL of concentrated hydrochloric acid (37% by mass), add 250 mL of deionized water, and mix thoroughly to prepare a 20% hydrochloric acid solution. Add 10 g of the above corrosion inhibitor, 5 g of potassium iodide, 5 g of surfactant, 5 g of alkynol derivative, and 5 g of trivalent metal salt to the hydrochloric acid solution, stir thoroughly to obtain the corrosion inhibition system, and perform corrosion protection application at 200℃ for 4 hours.

[0044] Example 3 S1. Add 0.8g of 2,2'-piperazine to a sealed reaction vessel containing 10mL of N,N-dimethylformamide, turn on the stirrer, set the stirring speed to 500r / min, and continue stirring until the solid is completely dissolved to form a homogeneous and transparent reaction solution.

[0045] S2. Add 0.6 mL of benzyl bromide dropwise to the above reaction solution at a rate of 0.25 mL / min. After the addition is complete, raise the system temperature to 30 °C, keep the stirring speed constant, and react continuously for 36 h under light-proof and sealed conditions to complete the quaternization reaction.

[0046] S3. Allow the reaction system to cool naturally to room temperature, start the vacuum filtration device, maintain the filtration time for 30 minutes, and collect the obtained solid product. Place the solid product in a constant temperature drying device, control the temperature at 60℃, and dry continuously for 24 hours to obtain the intermediate solid material.

[0047] S4. Add the above intermediate solid material to a reaction vessel containing 20 mL of dichloromethane, start stirring, set the stirring speed to 600 r / min, and stir until the solid is completely dissolved to form a homogeneous intermediate solution.

[0048] S5. First, add 0.5 mL of benzaldehyde to the intermediate solution and stir for 10 min. Then add 0.5 g of manganese dioxide and continue stirring for 10 min to ensure that all materials are fully mixed and form a homogeneous multi-component reaction system.

[0049] S6. Place the multi-component reaction system at room temperature, maintain a stirring speed of 700 r / min, and react continuously for 36 h under normal pressure, sealed and light-proof conditions to complete the oxidation cyclization and molecular reconstruction process.

[0050] S7. Cool the reaction system to room temperature, and perform vacuum filtration using qualitative filter paper with a pore size of 15 μm. Repeat the filtration twice to remove insoluble solid impurities and collect the target product in the filtrate.

[0051] S8. Place the target product into a vacuum drying device, control the temperature at 70℃ and the vacuum degree at 0.08MPa, and dry continuously for 24 hours.

[0052] S9. The dried product was purified by recrystallization twice using a mixed solvent of ethanol and dichloromethane to finally obtain high-purity 1-benzyl-10-phenylpyrrolo[1,2-a:3,4-b']dipyrazine-1-onium, which is a quaternary ammonium salt type high-temperature acidification corrosion inhibitor.

[0053] S10. Measure 253 mL of concentrated hydrochloric acid (37% by mass), add 250 mL of deionized water, and mix thoroughly to prepare a 20% hydrochloric acid solution. Add 10 g of the above corrosion inhibitor, 2.5 g of potassium iodide, 5 g of surfactant, 5 g of alkynol derivative, 5 g of trivalent metal salt, 5 g of unsaturated aldehyde, and 2.5 g of cuprous iodide to the hydrochloric acid solution, stir thoroughly to obtain the corrosion inhibition system, and perform corrosion protection application at 200℃ for 4 hours.

[0054] Comparative Example S1. Add 0.8g of 2,2'-piperazine to a sealed reaction vessel containing 10mL of N,N-dimethylformamide, turn on the stirrer, set the stirring speed to 400r / min, and continue stirring until the solid is completely dissolved to form a homogeneous and transparent reaction solution.

[0055] S2. Add 0.6 mL of benzyl bromide dropwise to the above reaction solution at a rate of 0.2 mL / min. After the addition is complete, raise the system temperature to 50 °C, keep the stirring speed constant, and react continuously for 24 h under light-proof and sealed conditions to complete the quaternization reaction.

[0056] S3. Allow the reaction system to cool naturally to room temperature, start the vacuum filtration device, maintain the filtration time for 20 minutes, and collect the obtained solid product. Place the solid product in a constant temperature drying device, control the temperature at 50℃, and dry continuously for 24 hours to obtain the intermediate solid material.

[0057] S4. The above intermediate solid materials are used directly as corrosion inhibitors without the oxidative cyclization reaction involving benzaldehyde and manganese dioxide, and without subsequent purification treatment.

[0058] S5. Measure 253 mL of concentrated hydrochloric acid (37% by mass), add 250 mL of deionized water, and mix well to prepare a 20% hydrochloric acid solution. Add 10 g of the above-mentioned uncyclized intermediate to the hydrochloric acid solution, without adding any compounding additives, and conduct a corrosion test at 200℃ for 4 hours.

[0059] Table 1 Comparison of preparation process parameters between Examples 1-3 and Comparative Example 1 Explanation of the table: This table fully presents the core parameter differences in preparation process and application conditions between Examples 1-3 and the comparative example. Examples 1-3 all fully implemented the entire process of quaternization, oxidative cyclization, double filtration, vacuum drying, and two recrystallizations. The reaction temperature and time were adjusted step by step according to the operating conditions. The compound system contained multiple synergistic agents, respectively adapted to 15% and 20% hydrochloric acid systems. The comparative example only completed the first step of quaternization reaction, lacking the key steps of oxidative cyclization, purification, and compounding, and thus could not form a stable multi-ring conjugated structure. The table intuitively demonstrates the technical characteristics of this invention: multi-step reaction, precise structural construction, and synergistic compounding, which is fundamentally different from traditional non-cyclized intermediates and provides complete process support for improving high-temperature corrosion inhibition performance.

[0060] Table 2 Comparison of corrosion inhibition performance between Examples 1-3 and Comparative Example 1 Explanation of the table: This table compares the core corrosion inhibition performance of Examples 1-3 and the comparative example under high-temperature and strong acid conditions. Examples 1-3, due to the formation of a polycyclic conjugated quaternary ammonium salt structure and the combination of a highly efficient compound system, exhibit strong high-temperature stability and a dense and robust adsorption film, maintaining high corrosion inhibition efficiency at 200℃ and stably adapting to 15% to 20% hydrochloric acid systems. Example 3, due to the synergistic effect of the addition of unsaturated aldehyde and cuprous iodide, achieves optimal overall performance. The comparative example is an uncyclized intermediate, lacking a polycyclic structure and synergistic effect of additives, resulting in rapid decomposition and desorption at high temperatures, leading to loss of protective capability. The table fully verifies that this invention, through molecular structure innovation and compound system optimization, overcomes the bottlenecks of traditional corrosion inhibitors' low temperature resistance and weak film formation, meeting the stringent protection requirements of ultra-high temperature deep well acidizing operations, and possessing significant technological advancement and engineering application value.

[0061] refer to Figure 2 3027cm -1 The absorption peak at 2816 cm⁻¹ is due to the absorption caused by the stretching vibration of CH in the aromatic ring structure of the compound. -1 This infrared absorption is produced by the stretching vibration of CH in the methylene (saturated alkane). 1968cm -1 The absorption peak is due to the structure of benzyl bromide, indicating the presence of substitution on the benzene ring. (1632 cm⁻¹) -1 The peaks on the left and right represent the stretching vibrations generated by the C=C double bond in the aromatic ring. (1495 cm⁻¹) -1 The stretching vibration peak generated by the C=N double bond. 1453 cm⁻¹ -1 The location is CN + The characteristic peaks of -C quaternary ammonium compounds were observed. The infrared spectrum preliminarily indicates that the product was successfully synthesized and its structure matches the expected product structure.

[0062] refer to Figure 3The peaks at 9.58 ppm correspond to H1, 9.37 ppm to H2, 8.68 ppm to H14, 15, and 16, 7.64 ppm to H9 and 13, 7.50 ppm to H3-7 and 10-12, and 5.97 ppm to H8. The peak at 2.52 ppm is the solvent peak for deuterated DMSO. Infrared and nuclear magnetic resonance spectroscopy results indicate that the product structure is similar to... Figure 1 Since the structures shown are consistent, the quaternary ammonium salt corrosion inhibitor is 1-benzyl-10-phenylpyrrolo[1,2-a:3,4-b']dipyrazine-1-onium.

[0063] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a quaternary ammonium salt type high-temperature acidification corrosion inhibitor, characterized in that, Includes the following steps: S1. Add 2,2'-piperazine to N,N-dimethylformamide solvent and stir until completely dissolved to form a homogeneous reaction solution; S2. Add benzyl bromide dropwise to the solution obtained in S1, control the reaction temperature at 25℃-50℃, and continue stirring for 24h-36h. S3. Cool the reaction system obtained in S2 to room temperature, perform vacuum filtration, collect the solid product, and dry the solid product in a dry environment for 24 hours to obtain intermediate solid material. S4. Add the intermediate solid material obtained in S3 to dichloromethane solvent and stir until completely dissolved to form a clear intermediate solution. S5. Add benzaldehyde and manganese dioxide to the intermediate solution obtained in S4, stir and mix evenly to form a multi-component reaction system. S6. Place the multi-component reaction system obtained in S5 at room temperature and stir continuously for 24-36 hours to allow the system to complete the synergistic reaction of oxidation cyclization and quaternization. S7. Cool the reaction system obtained in S6 to room temperature, perform vacuum filtration, and collect the target product in the filtrate. S8. Place the target product obtained in S7 into a constant temperature drying device and dry it continuously for 24 hours. S9. The dried product obtained in S8 is purified to obtain high-purity 1-benzyl-10-phenylpyrrolo[1,2-a:3,4-b']dipyrazine-1-onium, which is a quaternary ammonium salt type high-temperature acidification corrosion inhibitor.

2. The preparation method of the quaternary ammonium salt type high-temperature acidification corrosion inhibitor according to claim 1, characterized in that, The ratio of 2,2'-piperazine to N,N-dimethylformamide in S1 is 0.8 g: 10 mL. The stirring speed is controlled at 300 r / min-600 r / min, and the dissolution process is carried out in a closed container.

3. The preparation method of the quaternary ammonium salt type high-temperature acidification corrosion inhibitor according to claim 1, characterized in that, The dropping rate of benzyl bromide in S2 was controlled at 0.1 mL / min-0.3 mL / min, and the added volume of benzyl bromide was 0.6 mL. The reaction was carried out in a completely dark and sealed environment.

4. The preparation method of the quaternary ammonium salt type high-temperature acidification corrosion inhibitor according to claim 1, characterized in that, In S3, the filtration operation uses a vacuum filtration device, the filtration time lasts for 15-30 minutes, the drying temperature is controlled at 40℃-60℃, and the relative humidity of the drying environment is below 30%.

5. The preparation method of the quaternary ammonium salt type high-temperature acidification corrosion inhibitor according to claim 1, characterized in that, In S4, the ratio of intermediate solid material to dichloromethane is 0.8g of initial 2,2'-piperazine to 20mL of dichloromethane. Stir until no visible solid particles are visible and the system is homogeneous and transparent.

6. The preparation method of the quaternary ammonium salt type high-temperature acidification corrosion inhibitor according to claim 1, characterized in that, In S5, the volume of benzaldehyde added is 0.5 mL, and the mass of manganese dioxide added is 0.5 g. Benzaldehyde and manganese dioxide are added in steps: first, benzaldehyde is added and stirred for 10 min, then manganese dioxide is added and stirred for another 10 min.

7. The preparation method of the quaternary ammonium salt type high-temperature acidification corrosion inhibitor according to claim 1, characterized in that, In S6, the stirring speed is controlled at 400r / min-700r / min, and the entire reaction is carried out under normal pressure and closed conditions, with the ambient temperature maintained at 25℃ and no direct external light source.

8. The preparation method of the quaternary ammonium salt type high-temperature acidification corrosion inhibitor according to claim 1, characterized in that, In S7, qualitative filter paper with a pore size of 10μm-20μm is used for vacuum filtration, and the vacuum filtration process is repeated twice.

9. The preparation method of the quaternary ammonium salt type high-temperature acidification corrosion inhibitor according to claim 1, characterized in that, In S8, the drying temperature is 50℃-70℃, and the vacuum degree is controlled at 0.08MPa-0.095MPa. In S9, purification is carried out by recrystallization, and the solvent is a mixture of ethanol and dichloromethane. The recrystallization is performed twice.

10. The application of the quaternary ammonium salt type high-temperature acidification corrosion inhibitor prepared according to any one of claims 1 to 9 in an acidification system, characterized in that, The corrosion inhibitor is compounded with one or more of potassium iodide, surfactant, alkynol derivatives, trivalent metal salts, unsaturated aldehydes, and cuprous iodide, and added to a 15%-20% hydrochloric acid solution to form a corrosion inhibition system, which is then applied to high-temperature acidification operations at 200℃.

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