Bis-Mannich base corrosion inhibitor as well as preparation method and application thereof

Abstract

The invention relates to the technical field of CO2 utilization and storage, and discloses a bis-Mannich base corrosion inhibitor as well as a preparation method and application thereof. The method is carried out under the condition that the pH is 3-4. The method comprises the following steps: (1) in the presence of ethanol, carrying out first reaction on a compound as shown in a formula (A) and 1, 3, 5-trioxane to obtain an intermediate product; in formula (A), R is-(CH2) 7CH = CH (CH2) 7CH3; and (2) in the presence of ethanol, dropwise adding acetophenone into the intermediate product for a second reaction to obtain the bis-Mannich base corrosion inhibitor, the dropping rate of acetophenone is 0.0125-0.05 mL / s relative to 1 mol of the compound as shown in the formula (A); wherein the molar ratio of the compound shown in the formula (A) to the acetophenone to the 1, 3, 5-trioxane is 1: (2.0-2.3): (2.0-2.3). Formula (A).

Description

Technical Field

[0001] This invention relates to the field of CO2 utilization and storage technology, specifically to a bis-Mannich base corrosion inhibitor, its preparation method, and its application. Background Technology

[0002] Against the backdrop of global energy structure adjustment and carbon peaking and carbon neutrality strategies, CO2 enhanced oil recovery (EOR) and CO2 geological storage (CCS) technologies are receiving increasing attention. CO2 EOR is not only an important enhanced oil recovery (EOR) technology, but it also has the function of sequestering industrial waste gas CO2 within the oil field, achieving a win-win situation for energy extraction and carbon emission reduction. However, this process inevitably introduces serious corrosion risks. CO2 dissolves in the reservoir to form carbonic acid, exposing the well casing to a highly acidic environment. With increasing extraction depth, the temperature and pressure faced by the casing increase significantly (e.g., deep well casing can reach over 150°C), and the CO2 corrosion rate increases exponentially with increasing temperature.

[0003] While imidazoline corrosion inhibitors widely used in industry are effective under normal conditions, the stability and durability of their adsorbed films face challenges in the high-temperature and high-pressure environment of CO2-driven oil recovery. Furthermore, single-Mannich base corrosion inhibitors exhibit poor corrosion inhibition performance. For example, CN119954723A discloses a CO2-resistant tall oil imidazoline Mannich base corrosion inhibitor. This inhibitor is produced by synthesizing an imidazoline ring from tall oil mixed fatty acids and organic polyamines, followed by condensation with the terminal amine groups of the imidazoline ring side chains using aromatic ketones and trioxymethylene, resulting in an imidazoline Mannich base corrosion inhibitor with both hydrophilic and hydrophobic groups. When used in combination with surfactants and solubilizers, this inhibitor only achieves a corrosion inhibition efficiency of over 92% at an operating temperature of 50°C. Its corrosion inhibition effect needs further improvement, and its high-temperature adaptability needs to be enhanced.

[0004] Moreover, the traditional synthesis of bis-Mannich bases usually requires two independent Mannich reactions, which is cumbersome and has obvious defects: if the conversion rate of the first reaction is low or the intermediate is not completely separated, the residual raw materials often lead to side reactions such as over-alkylation (generating high molecular weight amine byproducts), self-condensation (generating unsaturated compounds or high molecular weight heterocycles), cyclization or decomposition, resulting in a relatively low corrosion inhibition rate of the final product, bis-Mannich base. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing corrosion inhibitors, such as low corrosion inhibition efficiency under high temperature conditions.

[0006] To achieve the above objectives, a first aspect of the present invention provides a method for preparing a bis-Mannich base corrosion inhibitor, the method being carried out under conditions of pH 3-4; the method comprising: (1) In the presence of ethanol, the compound shown in formula (A) was reacted with 1,3,5-trioxane in a first reaction to give an intermediate product; Formula (A); In equation (A), R is -(CH2)7CH=CH(CH2)7CH3; (2) In the presence of ethanol, the acetophenone is added dropwise to the intermediate product to carry out a second reaction to obtain the bis-Mannich base corrosion inhibitor; the dropping rate of the acetophenone is 0.0125-0.05 mL / s relative to 1 mol of the compound shown in formula (A); The molar ratio of the compound represented by formula (A), the acetophenone, and the 1,3,5-trioxane is 1:2.0-2.3:2.0-2.3.

[0007] Preferably, in step (1), the amount of ethanol used is 480-720 mL, based on the total amount of the compound shown in formula (A) and the 1,3,5-trioxane being 1 mol.

[0008] In a preferred embodiment, in step (2), the amount of ethanol used is 300-500 mL relative to 1 mol of acetophenone.

[0009] Preferably, in step (1), the conditions for the first reaction include: a rotation speed of 300-400 rpm, a temperature of 21-25℃, and a time of 0.5-1h.

[0010] Preferably, in step (2), the dropping rate of the acetophenone is 0.016-0.05 mL / s relative to 1 mol of the compound represented by formula (A).

[0011] Preferably, in step (2), the conditions for the second reaction include: a rotation speed of 300-400 rpm, a temperature of 80-90℃, and a time of 4-8 h.

[0012] In a preferred embodiment, in step (2), the method further includes: removing impurities from the material obtained from the second reaction to obtain the bis-Mannich base corrosion inhibitor.

[0013] Preferably, the impurity removal process is rotary distillation, and the conditions for rotary distillation include: a vacuum of 0.05-0.12 MPa, a temperature of 40-60°C, and a time of 1-2 hours.

[0014] A second aspect of the present invention provides a bis-Mannich base corrosion inhibitor prepared by the method described in the first aspect.

[0015] The third aspect of the present invention provides the application of the bis-Mannich base corrosion inhibitor described in the second aspect in CO2 flooding.

[0016] Through the above technical solution, the present invention has at least the following advantages over the prior art: The bis-Mannich base corrosion inhibitor prepared by the technical solution provided by the present invention has the advantages of good high-temperature corrosion inhibition performance, small dosage and low cost; among them, when the concentration is 10mg / L and 15mg / L, the uniform corrosion inhibition rate calculated by the laboratory high temperature and high pressure immersion dynamic corrosion inhibition rate test method reaches more than 96%. Attached Figure Description

[0017] Figure 1 This is the infrared spectrum of the bis-Mannich base corrosion inhibitor prepared in Example 1 of the present invention. Detailed Implementation

[0018] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0019] In this invention, the chemical formula of the 1,3,5-trioxane is C3H6O3, and its structural formula is shown in formula (B); the chemical formula of the acetophenone is C8H8O, and its structural formula is shown in formula (C).

[0020] Formula (B); Formula (C).

[0021] As previously stated, a first aspect of the present invention provides a method for preparing a bis-Mannich base corrosion inhibitor, the method being carried out under conditions of pH 3-4; the method comprising: (1) In the presence of ethanol, the compound shown in formula (A) was reacted with 1,3,5-trioxane in a first reaction to give an intermediate product; Formula (A); In equation (A), R is -(CH2)7CH=CH(CH2)7CH3; (2) In the presence of ethanol, the acetophenone is added dropwise to the intermediate product to carry out a second reaction to obtain the bis-Mannich base corrosion inhibitor; the dropping rate of the acetophenone is 0.0125-0.05 mL / s relative to 1 mol of the compound shown in formula (A); The molar ratio of the compound represented by formula (A), the acetophenone, and the 1,3,5-trioxane is 1:2.0-2.3:2.0-2.3.

[0022] During their research, the inventors of this invention discovered that the traditional synthesis of bis-Mannich bases typically requires two independent Mannich reactions, a cumbersome process with significant drawbacks: if the conversion rate of the first reaction is low or the intermediate separation is incomplete, residual raw materials can easily trigger side reactions in the second step, resulting in a relatively low corrosion inhibition rate for the final product, the bis-Mannich base. The invention unexpectedly discovered that this method, by using the compound shown in formula (A), 1,3,5-trioxane, and acetophenone as reactants, and precisely controlling the solvent type, feed rate, and ratio of reactants, can achieve a "one-pot" single-stage Mannich reaction to directly construct the bis-Mannich base skeleton. This significantly simplifies the synthetic route, avoids intermediate separation steps, and suppresses side reactions, thereby greatly improving reaction efficiency and atom economy.

[0023] During their research, the inventors of this invention discovered that the mechanism by which the bis-Mannich base corrosion inhibitor prepared by the above method achieves a better corrosion inhibition effect lies in the fact that the obtained bis-Mannich base corrosion inhibitor contains a single Mannich base characteristic functional group, has a large molecular weight, and its long chain structure can more tightly cover the metal surface, resulting in higher corrosion inhibition efficiency. Specifically: First, the nitrogen atom with a lone pair of electrons on the imidazoline ring in the corrosion inhibitor molecule can exchange electrons with the metal surface to form a stable coordinate bond, allowing the molecule to be firmly adsorbed onto the metal surface and hindering the formation of corrosive ions (such as H+). + HCO3 - First, the diffusion of ions; second, the benzene ring in the molecule, due to its π-electron system, can overlap with the d orbital electrons on the metal surface to form anti-π bonds, which promotes the benzene ring to be adsorbed on the metal surface in a parallel manner, further enhancing the stability of the adsorption film; third, the long-chain alkyl provided by oleic acid imidazoline makes the corrosion inhibitor molecules adsorbed on the metal surface hydrophobic. These molecules are oriented on the metal surface to form a dense hydrophobic organic film, which effectively blocks the direct contact between water molecules, dissolved CO2 and its acidic products (such as H2CO3) and the metal matrix, thereby inhibiting the occurrence of electrochemical corrosion reactions.

[0024] In addition, the bis-Mannich base corrosion inhibitors prepared by the above method have the advantages of small dosage and low cost.

[0025] Preferably, in step (1), the total amount of the compound shown in formula (A) and the 1,3,5-trioxane is 1 mol, and the amount of ethanol is 480-720 mL. Under this preferred condition, the technical solution provided by the present invention can obtain a bis-Mannich base corrosion inhibitor with higher corrosion inhibition efficiency.

[0026] According to a preferred embodiment, in step (1), the purity of the compound represented by formula (A) is >98 wt%.

[0027] Preferably, in step (1), the conditions for the first reaction include: a rotation speed of 300-400 rpm, a temperature of 21-25℃, and a time of 0.5-1h.

[0028] In a preferred embodiment, in step (2), the amount of ethanol used is 300-500 mL relative to 1 mol of acetophenone. Under this preferred embodiment, the technical solution provided by the present invention can obtain a bis-Mannich base corrosion inhibitor with higher corrosion inhibition efficiency.

[0029] Preferably, in step (2), the dropping rate of the acetophenone is 0.016-0.05 mL / s relative to 1 mol of the compound represented by formula (A).

[0030] Preferably, in step (2), the conditions for the second reaction include: a rotation speed of 300-400 rpm, a temperature of 80-90℃, and a time of 4-8 h.

[0031] It should be noted that, in this invention, the time for the second reaction does not include the time for adding acetophenone.

[0032] According to a particularly preferred embodiment, the method includes: (S1) Dissolve the 1,3,5-trioxane in the ethanol and adjust the pH of the resulting material to 3-4 to obtain mixture I; Formula (A); In equation (A), R is -(CH2)7CH=CH(CH2)7CH3; The compound represented by formula (A) is then reacted with mixture I to obtain an intermediate product; (S2) The ethanol is used to dilute acetophenone, and the pH value of the resulting material is adjusted to 3-4 to obtain mixture II; (S3) The mixture II is added dropwise to the intermediate product to carry out a second reaction to obtain the bis-Mannich base corrosion inhibitor; the dropping rate of the mixture II is 0.0125-0.05 mL / s relative to 1 mol of the compound represented by formula (A); The molar ratio of the compound represented by formula (A), the acetophenone, and the 1,3,5-trioxane is 1:2.0-2.3:2.0-2.3.

[0033] In a preferred embodiment, in step (2), the method further includes: removing impurities from the material obtained from the second reaction to obtain the bis-Mannich base corrosion inhibitor.

[0034] Preferably, the impurity removal process is rotary distillation, and the conditions for rotary distillation include: a vacuum of 0.05-0.12 MPa, a temperature of 40-60°C, and a time of 1-2 hours.

[0035] Preferably, the equipment used for rotary distillation is a rotary evaporator.

[0036] In this invention, the synthetic route involved in the method for preparing bis-Mannich base corrosion inhibitors is as follows: ; where R is -(CH2)7CH=CH(CH2)7CH3.

[0037] As previously stated, a second aspect of the present invention provides a bis-Mannich base corrosion inhibitor prepared by the method described in the first aspect.

[0038] Preferably, the bis-Mannich base corrosion inhibitor is a compound with the structure shown in formula (I); Formula (I); In equation (I), R is -(CH2)7CH=CH(CH2)7CH3.

[0039] As previously stated, the third aspect of the present invention provides the application of the bis-Mannich base corrosion inhibitors described in the second aspect in CO2 flooding.

[0040] The present invention will be described in detail below through examples. In the following examples, the instruments and equipment used are all commercially available products.

[0041] Cis-oleic aminoethyl imidazoline: purchased from Dongying Keling Chemical Co., Ltd., grade 171852116, purity >98wt%, CAS number 20565-75-7, chemical formula C 22 H 43 N3, the structural formula is as follows:

[0042] Imidazoline: Purchased from Shanghai Maclean Biochemical Technology Co., Ltd., purity 96wt%, CAS number 504-75-6, chemical formula C3H6N2, structural formula [not specified]. .

[0043] 2-Methylimidazoline: Purchased from Shanghai Maclean Biochemical Technology Co., Ltd., CAS No. 534-26-9, chemical formula C4H8N2, structural formula [not specified]. .

[0044] 1,3,5-Trioxane: Purchased from Shanghai Maclean Biochemical Technology Co., Ltd., CAS No. 110-88-3.

[0045] Acetophenone: Purchased from Shanghai Maclean Biochemical Technology Co., Ltd., CAS No. 98-86-2.

[0046] Ethanol: Purchased from Sinopharm Chemical Reagent Co., Ltd., CAS No. 64-17-5.

[0047] In the following examples, room temperature refers to a temperature of 23±2℃.

[0048] Example 1 (S1) Dissolve 1,3,5-trioxane completely in ethanol, and add hydrochloric acid to adjust the pH of the resulting material to 4, to obtain mixture I; At room temperature, cis-oleoylaminoethylimidazoline I (0.025 mol) was reacted with mixture I in the first reaction (300 rpm, 0.5 h) to obtain the intermediate product; Of which, based on a total amount of cis-oleoylaminoethylimidazoline and 1,3,5-trioxane of 1 mol, the total amount of ethanol is 588.2 mL; (S2) Acetophenone was diluted with ethanol and hydrochloric acid was added to adjust the pH of the resulting material to 4, thus obtaining mixture II; wherein, the amount of ethanol used was 300 mL relative to 1 mol of acetophenone.

[0049] (S3) Adjust the temperature of the constant temperature digital display oil bath of the heat-collecting magnetic stirrer to the temperature of the second reaction. After the temperature rises to the set temperature, add the aforementioned mixture II to the intermediate product through the constant pressure funnel to carry out the second reaction (speed is 300 rpm, temperature is 85℃, time is 4h) to obtain the crude product. The crude product was rotary distilled using a rotary evaporator (vacuum degree 0.09 MPa, temperature 50℃, time 1 h) to obtain the bis-Mannich base corrosion inhibitor; Among them, the dropping rate of mixture II is 0.025 mL / s relative to 1 mol of cis-oleoylaminoethyl imidazoline; The molar ratio of cis-oleoylaminoethylimidazoline, acetophenone and 1,3,5-trioxane is 1:2.1:2.1.

[0050] Example 2 (S1) Dissolve 1,3,5-trioxane completely in ethanol, and add hydrochloric acid to adjust the pH of the resulting material to 3, to obtain mixture I.

[0051] At room temperature, cis-oleoylaminoethylimidazoline I (0.025 mol) was reacted with mixture I in the first reaction (350 rpm, 1 h) to obtain an intermediate product; wherein, based on the total amount of cis-oleoylaminoethylimidazoline and 1,3,5-trioxane being 1 mol, the total amount of ethanol being 480 mL. (S2) Acetophenone was diluted with ethanol and hydrochloric acid was added to adjust the pH of the resulting material to 4, thus obtaining mixture II; wherein, the amount of ethanol used was 400 mL relative to 1 mol of acetophenone.

[0052] (S3) Adjust the temperature of the constant temperature digital display oil bath of the heat-collecting magnetic stirrer to the temperature of the second reaction. After the temperature rises to the set temperature, add the aforementioned mixture II to the intermediate product through the constant pressure funnel to carry out the second reaction (speed is 350 rpm, temperature is 90℃, time is 6h) to obtain the crude product. The crude product was rotary distilled using a rotary evaporator (vacuum degree 0.09 MPa, temperature 50℃, time 1 h) to obtain the bis-Mannich base corrosion inhibitor; Among them, relative to 1 mol of cis-oleoylaminoethylimidazoline, the dropping rate of mixture II is 0.0167 mL / s; The molar ratio of cis-oleoylaminoethylimidazoline, acetophenone, and 1,3,5-trioxane is 1:2:2.

[0053] Example 3 (S1) Dissolve 1,3,5-trioxane completely in ethanol, and add hydrochloric acid to adjust the pH of the resulting material to 3, to obtain mixture I.

[0054] At room temperature, cis-oleoylaminoethylimidazoline I (0.025 mol) was reacted with mixture I in the first reaction (400 rpm, 1 h) to obtain an intermediate product; wherein, based on the total amount of cis-oleoylaminoethylimidazoline and 1,3,5-trioxane being 1 mol, the total amount of ethanol being 679.25 mL. (S2) Acetophenone was diluted with ethanol and hydrochloric acid was added to adjust the pH of the resulting material to 3, thus obtaining mixture II; wherein, the amount of ethanol used was 400 mL relative to 1 mol of acetophenone.

[0055] (S3) Adjust the temperature of the constant temperature digital display oil bath of the heat-collecting magnetic stirrer to the temperature of the second reaction. After the temperature rises to the set temperature, add the aforementioned mixture II dropwise to the intermediate product through the constant pressure funnel to carry out the second reaction (speed is 400 rpm, temperature is 80℃, time is 8h) to obtain the crude product. The crude product was rotary distilled using a rotary evaporator (vacuum degree 0.09 MPa, temperature 50℃, time 1.5 h) to obtain the bis-Mannich base corrosion inhibitor; Among them, the dropping rate of mixture II is 0.025 mL / s relative to 1 mol of cis-oleoylaminoethyl imidazoline; The molar ratio of cis-oleoylaminoethylimidazoline, acetophenone and 1,3,5-trioxane is 1:2.3:2.3.

[0056] Example 4 (S1) Dissolve 1,3,5-trioxane completely in ethanol, and add hydrochloric acid to adjust the pH of the resulting material to 4, to obtain mixture I.

[0057] At room temperature, cis-oleoylaminoethylimidazoline I (0.025 mol) was reacted with mixture I in the first reaction (400 rpm, 0.5 h) to obtain the intermediate product; wherein, based on the total amount of cis-oleoylaminoethylimidazoline and 1,3,5-trioxane being 1 mol, the total amount of ethanol being 600 mL. (S2) Acetophenone was diluted with ethanol and hydrochloric acid was added to adjust the pH of the resulting material to 4, thus obtaining mixture II; wherein, the amount of ethanol used was 500 mL relative to 1 mol of acetophenone.

[0058] (S3) Adjust the temperature of the constant temperature digital display oil bath of the heat-collecting magnetic stirrer to the temperature of the second reaction. After the temperature rises to the set temperature, add the aforementioned mixture II to the intermediate product through the constant pressure funnel to carry out the second reaction (speed is 400 rpm, temperature is 85℃, time is 6h) to obtain the crude product. The crude product was rotary distilled using a rotary evaporator (vacuum degree 0.09 MPa, temperature 50℃, time 1.5 h) to obtain the bis-Mannich base corrosion inhibitor; Among them, the dropping rate of mixture II is 0.05 mL / s relative to 1 mol of cis-oleoylaminoethyl imidazoline; The molar ratio of cis-oleoylaminoethylimidazoline, acetophenone, and 1,3,5-trioxane is 1:2:2.

[0059] Example 5 (S1) Dissolve 1,3,5-trioxane completely in ethanol, and add hydrochloric acid to adjust the pH of the resulting material to 3.5 to obtain mixture I.

[0060] At room temperature, cis-oleoylaminoethylimidazoline I (0.025 mol) was reacted with mixture I in the first reaction (300 rpm for 1 h) to obtain an intermediate product; wherein, based on the total amount of cis-oleoylaminoethylimidazoline and 1,3,5-trioxane being 1 mol, the total amount of ethanol being 600 mL. (S2) Acetophenone was diluted with ethanol and hydrochloric acid was added to adjust the pH of the resulting material to 3.5 to obtain mixture II; wherein, the amount of ethanol used was 300 mL relative to 1 mol of acetophenone.

[0061] (S3) Adjust the temperature of the constant temperature digital display oil bath of the heat-collecting magnetic stirrer to the temperature of the second reaction. After the temperature rises to the set temperature, add the mixture II dropwise to the aforementioned intermediate product through the constant pressure funnel to carry out the second reaction (speed is 300 rpm, temperature is 90℃, time is 8h) to obtain the crude product. The crude product was rotary distilled using a rotary evaporator (vacuum degree 0.09 MPa, temperature 50℃, time 1 h) to obtain the bis-Mannich base corrosion inhibitor; Among them, relative to 1 mol of cis-oleoylaminoethylimidazoline, the dropping rate of mixture II is 0.0167 mL / s; The molar ratio of cis-oleoylaminoethylimidazoline, acetophenone and 1,3,5-trioxane is 1:2.2:2.3.

[0062] Example 6 The procedure was carried out in a similar manner to that of Example 1, except that in step (S1), the total amount of ethanol used was 300 mL, based on a total amount of cis-oleoylaminoethylimidazoline and 1,3,5-trioxane of 1 mol. In step (S2), the amount of ethanol used is 200 mL relative to 1 mol of acetophenone. Everything else is the same, resulting in a bis-Mannich base corrosion inhibitor.

[0063] Comparative Example 1 The procedure was carried out in a similar manner to that of Example 1, except that in step (S1), an equimolar amount of imidazoline was used to replace cis-oleoylaminoethyl imidazoline. Everything else is the same, resulting in a bis-Mannich base corrosion inhibitor.

[0064] Comparative Example 2 The procedure was carried out in a similar manner to that of Example 1, except that in step (S1), an equimolar amount of 2-methylimidazoline was used to replace cis-oleoylaminoethylimidazoline. Everything else is the same, resulting in a bis-Mannich base corrosion inhibitor.

[0065] Comparative Example 3 The procedure was carried out in a similar manner to that in Example 1, except that the molar ratio of cis-oleoylaminoethyl imidazoline, acetophenone, and 1,3,5-trioxane was 1:2.5:2. Everything else is the same, resulting in a bis-Mannich base corrosion inhibitor.

[0066] Comparative Example 4 The procedure was carried out in a similar manner to that of Example 1, except that in steps (S1) and (S2), equimolar amounts of methanol were used to replace ethanol. Everything else is the same, resulting in a bis-Mannich base corrosion inhibitor.

[0067] Comparative Example 5 The process was carried out in a similar manner to Example 1, except that in step (S3), the dropping rate of mixture II was 0.1 mL / s relative to 1 mol of cis-oleoaminoethylimidazoline. Everything else is the same, resulting in a bis-Mannich base corrosion inhibitor.

[0068] Test case The corrosion inhibition effects of the bis-Mannich base corrosion inhibitors prepared in the above examples and cis-oleic acid aminoethyl imidazoline alone as corrosion inhibitors were tested. The test method referred to the dynamic corrosion inhibition rate determination by high-temperature and high-pressure immersion method in GB / T 35509-2017 "Application and Evaluation of Corrosion Inhibitors in Oil and Gas Fields". The test water was produced water from a CO2-driven oil well in Shengli Oilfield, with a salinity of approximately 35,000 mg / L; the corrosion inhibitor concentrations were 10 mg / L and 15 mg / L, respectively; the test specimen material was N80, with dimensions of 50 mm × 10 mm × 3 mm, conforming to SY / T 5273-2014; the experimental conditions were: CO2 pressure of 6 MPa, temperature of 120℃, and linear velocity of 1 m / s. The test results are shown in Table 1.

[0069] The calculation formulas involved are as follows: Uniform corrosion rate r of corrosion inhibitor c : ; Where, r c m1 represents the uniform corrosion rate of the corrosion inhibitor (mm / a); m2 represents the weight of the specimen before the test (g); m3 represents the weight of the specimen after the test (g); and S represents the surface area of ​​the specimen (cm²). 2 ); t is the experimental time, taken as 72h; ρ is the density of the sample material (g / cm³). 3 ).

[0070] Uniform corrosion inhibition rate η of the corrosion inhibitor: ; Where η is the uniform corrosion inhibition rate of the corrosion inhibitor (%); r0 is the uniform corrosion rate without corrosion inhibitor, taken as 2.4716 mm / a; r c This indicates the uniform corrosion rate (mm / a) after the addition of a corrosion inhibitor.

[0071] Table 1

[0072] The present invention exemplarily in Figure 1 The infrared spectrum of the bis-Mannich base corrosion inhibitor prepared in Example 1 is provided. Figure 1 Middle, 2924cm -1 2849cm -1 Corresponding to the symmetric and asymmetric stretching vibration peaks of methylene (-CH2-), 1683 cm⁻¹ -1 The peak represents the stretching vibration of the carbonyl group (C=O), at 1640 cm⁻¹. -1 The peak corresponds to the stretching vibration of the C=N bond on the imidazole ring, at 1541 cm⁻¹. -1 The bending vibration peak of NH is 1446 cm⁻¹. -1 It is a characteristic vibration of the imidazole ring and benzene ring skeleton, 1359 cm⁻¹ -1 Bending vibrations attributed to -CH3 and CH2, 759 cm -1 and 683cm -1 This is the characteristic vibrational peak of a monosubstituted benzene ring, at 591 cm⁻¹. -1 These are vibrational peaks belonging to the fingerprint region of benzene ring groups; in addition, 3310 cm⁻¹ -1 The peak corresponds to the symmetric stretching vibration of NH, and this peak also appears in the spectra of cis-oleic aminoethyl imidazoline and mono-Mannich bases; 1265 cm⁻¹ -1 The peak represents the stretching vibration of the CN bond, and this peak was detected in the spectra of both single-Mannig bases and double-Mannig bases. This indicates that the method provided in this invention successfully prepared double-Mannig base corrosion inhibitors.

[0073] The results above show that the bis-Mannich base corrosion inhibitor prepared by the method provided by the present invention has a uniform corrosion inhibition rate of over 96% when the concentration is 10 mg / L, with the highest reaching 96.83%; while the uniform corrosion inhibition rate of cis-oleic aminoethyl imidazoline alone as a corrosion inhibitor is only 68.15%, which is significantly lower than that of the present invention. The bis-Mannich base corrosion inhibitor achieved a uniform corrosion inhibition rate of over 96% at a concentration of 15 mg / L, with a maximum of 98.19%; while the uniform corrosion inhibition rate of cis-oleic aminoethyl imidazoline alone as a corrosion inhibitor was only 75.61%, significantly lower than that of this invention.

[0074] This demonstrates that the bis-Mannich base corrosion inhibitor prepared by the method provided in this invention has the advantages of good corrosion inhibition performance under high temperature conditions, small dosage, and low cost, and has significantly better effect than the prior art.

[0075] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing bis-Mannich base corrosion inhibitors, characterized in that, The method is carried out under conditions of pH 3-4; the method includes: (1) In the presence of ethanol, the compound shown in formula (A) was reacted with 1,3,5-trioxane in a first reaction to give an intermediate product; Formula (A); In equation (A), R is -(CH2)7CH=CH(CH2)7CH3; (2) In the presence of ethanol, the acetophenone is added dropwise to the intermediate product to carry out a second reaction to obtain the bis-Mannich base corrosion inhibitor; the dropping rate of the acetophenone is 0.0125-0.05 mL / s relative to 1 mol of the compound shown in formula (A); The molar ratio of the compound represented by formula (A), the acetophenone, and the 1,3,5-trioxane is 1:2.0-2.3:2.0-2.

3.

2. The method according to claim 1, characterized in that, In step (1), the total amount of the compound shown in formula (A) and the 1,3,5-trioxane is 1 mol, and the amount of ethanol is 480-720 mL.

3. The method according to claim 1, characterized in that, In step (2), the amount of ethanol used is 300-500 mL relative to 1 mol of acetophenone.

4. The method according to any one of claims 1-3, characterized in that, In step (2), the dropping rate of the acetophenone is 0.016-0.05 mL / s relative to 1 mol of the compound represented by formula (A).

5. The method according to any one of claims 1-3, characterized in that, In step (1), the conditions for the first reaction include: a rotation speed of 300-400 rpm, a temperature of 21-25℃, and a time of 0.5-1h.

6. The method according to any one of claims 1-3, characterized in that, In step (2), the conditions for the second reaction include: a rotation speed of 300-400 rpm, a temperature of 80-90℃, and a time of 4-8h.

7. The method according to any one of claims 1-3, characterized in that, In step (2), the method further includes: removing impurities from the material obtained from the second reaction to obtain the bis-Mannich base corrosion inhibitor.

8. The method according to claim 7, characterized in that, The impurity removal process is performed by rotary distillation, and the conditions for rotary distillation include: a vacuum of 0.05-0.12 MPa, a temperature of 40-60°C, and a time of 1-2 hours.

9. A bis-Mannich base corrosion inhibitor prepared by the method according to any one of claims 1-8.

10. The application of the bis-Mannich base corrosion inhibitor as described in claim 9 in CO2 flooding.

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