Carbon dioxide corrosion inhibitor, preparation method and application thereof
Patent Information
- Application Number
- CN202510173162.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-17
- Publication Date
- 2026-08-18
AI Technical Summary
[0004]但目前发现在超临界CO2环境下，传统咪唑啉缓蚀剂的缓蚀效果会出现明显差异
[0028] The carbon dioxide corrosion inhibitor described in this invention significantly reduces the corrosion rate of sample steel sheets during supercritical carbon dioxide pipeline transportation. The synthesis process is safe and efficient. Compared with existing carbon dioxide corrosion inhibitors on the market, the carbon dioxide corrosion inhibitor provided by this invention has a better corrosion inhibition effect and can be used in a wider range of operating conditions.
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Abstract
Description
Technical Field
[0001] This invention relates to a carbon dioxide corrosion inhibitor, its preparation method, and its application. Background Technology
[0002] Carbon capture, utilization, and storage (CCUS) is a crucial technological approach for achieving CO2 emission reduction. In CCUS projects, pipeline transportation is the primary mode of CO2 transport. The supercritical CO2 fluid transported via pipelines contains corrosive impurities such as H2O, posing a serious threat to the safe operation of CO2 pipelines. Among methods for inhibiting pipeline corrosion, corrosion inhibitors are substances that can significantly reduce the corrosion rate of metals in the medium with just a trace amount. Due to their simplicity, low dosage, and low cost, the addition of corrosion inhibitors has become the most widely used technique for suppressing CO2 corrosion.
[0003] Imidazoline corrosion inhibitors are widely used in oil wells, gas wells, and pipelines as CO2 corrosion inhibitors due to their excellent adsorption properties, which facilitate the formation of an inhibitory film on steel surfaces. They also possess bactericidal, scale-inhibiting, and low-toxicity properties. Imidazoline corrosion inhibitors are primarily composed of a nitrogen-containing five-membered heterocycle. This heterocycle contains a hydrophilic group R1 attached to nitrogen and hydrophobic side chains R2 composed of different carbon chains (see schematic diagram of imidazoline structure). Figure 1 (As shown). Imidazoline molecules have a unique molecular structure. Their hydrophilic groups, containing atoms with lone pairs of electrons (N, O, S, etc.), readily form coordination bonds with metal atoms, resulting in chemisorption and thus slowing down corrosion. Their hydrophobic side chains can form a hydrophobic film, effectively preventing further erosion by corrosive media.
[0004] However, it has been found that the corrosion inhibition effect of traditional imidazoline corrosion inhibitors varies significantly under supercritical CO2 conditions. Due to the unique physicochemical properties of supercritical CO2, the solubility of carbon dioxide increases dramatically in the supercritical state, affecting the stability of the corrosion inhibitor and its adsorption behavior on the metal surface, thus impacting its corrosion inhibition performance. Therefore, traditional imidazoline corrosion inhibitors should be modified by introducing functional groups to enhance their resistance to supercritical carbon dioxide dissolution and their adsorption and film-forming ability, thereby improving their corrosion inhibition performance. Summary of the Invention
[0005] To address the poor corrosion inhibition performance of traditional imidazoline corrosion inhibitors in supercritical CO2 environments, this study introduces dimer acids, a material with oligomerization properties, resulting in superior performance compared to traditional inhibitors, including higher surface activity, higher solubilization capacity, and synergistic effects. Modification with polar groups increases the surface adsorption of the inhibitor, effectively improving its corrosion inhibition performance. Modification of imidazoline corrosion inhibitors can be achieved through addition or condensation of the primary amine linked to the imidazoline ring. Introducing thiourea onto the primary amine linked to the imidazoline ring improves the film-forming properties of the inhibitor product. Furthermore, the introduction of thiourea groups into the imidazoline corrosion inhibitor enables it to self-repair even after the film on carbon steel surfaces is damaged. The imidazoline corrosion inhibitor designed in this way can better cope with supercritical carbon dioxide corrosion environments, resisting the dissolution and damage of the inhibitor film by supercritical carbon dioxide, and achieving better corrosion inhibition effects.
[0006] This invention provides a corrosion inhibitor for supercritical carbon dioxide transmission pipelines and its preparation method. The corrosion inhibitor provided by this invention can suppress some of the corrosion problems that occur during the operation of supercritical carbon dioxide pipelines, which is beneficial to improving the safety and economy of supercritical carbon dioxide pipeline transportation.
[0007] As one aspect of the present invention, there is a relation to a dimer acid imidazoline, said dimer acid imidazoline being as shown in formula (1):
[0008]
[0009] Wherein, R is selected from:
[0010]
[0011] As another aspect of the present invention, a method for preparing the above-mentioned dimer acid imidazoline is provided, the method comprising:
[0012] (1) Take dimer acid and diethylenetriamine with a mass ratio of 114:31 to 62, add water-carrying agent and stabilizer, and carry out amidation reaction under nitrogen atmosphere and stirring conditions;
[0013] (2) Under nitrogen atmosphere and stirring conditions, a cyclization and dehydration reaction was carried out to obtain dimer acid imidazoline.
[0014] In a feasible specific implementation, the water-carrying agent is xylene.
[0015] In a feasible specific implementation, the stabilizer is boric acid.
[0016] In a feasible specific embodiment, step (1) is carried out at 140–160 °C for the amidation reaction.
[0017] In a feasible specific implementation, step (2) is carried out at 220–240°C for the cyclization dehydration reaction.
[0018] As another aspect of the present invention, a carbon dioxide corrosion inhibitor is provided, characterized in that the carbon dioxide corrosion inhibitor is a thiourea-based dimer acid imidazoline, as shown in formula (2):
[0019]
[0020] Where R is:
[0021]
[0022] As another aspect of the present invention, a method for preparing the above-mentioned carbon dioxide corrosion inhibitor is provided, the method comprising:
[0023] Take 105-125 parts by mass of the above-mentioned dimer acid imidazoline and mix it with 13-21 parts by mass of thiourea. Under stirring conditions, carry out an addition reaction to obtain thiourea-based dimer acid imidazoline, which is a carbon dioxide corrosion inhibitor.
[0024] In a feasible specific embodiment, the addition reaction is carried out at 100–120°C.
[0025] As another aspect of the present invention, the application of the above-mentioned carbon dioxide corrosion inhibitor in supercritical carbon dioxide pipeline transportation is involved.
[0026] In embodiments of this invention, thiourea-based imidazoline dimer acid is used as a carbon dioxide corrosion inhibitor. The thiourea group in this imidazoline exhibits excellent film-forming properties. Introducing the thiourea group into the imidazoline corrosion inhibitor allows it to self-repair even after the film on the carbon steel surface is damaged. Most organic corrosion inhibitors are adsorption film type inhibitors, and the formation of adsorption films can be divided into chemisorption and physisorption. Physicosorption refers to the corrosion inhibitor molecules adsorbing onto the metal surface through electrostatic attraction. Chemisorption mainly involves the formation of coordinate bonds between the lone pairs of electrons on the O, N, and S atoms in the corrosion inhibitor molecules and the d orbitals of the metal atoms, resulting in adsorption onto the metal surface. The O, N, S, and C=N groups on the thiourea-based imidazoline dimer acid molecules can donate electrons to the d orbitals of Fe on the metal surface, forming coordinate bonds and creating a dense protective film on the metal surface to slow corrosion. The organic chemical reaction between thiourea and the imidazoline dimer acid mainly forms an addition product; this reaction is commonly referred to as the Schotten-Baumann reaction. In this reaction, the lone pair of electrons on the sulfur atom of thiourea attacks the carbon atom on the imidazoline ring of oleic acid, thereby forming a new chemical bond. The products generated by this reaction typically have improved surface activity, corrosion inhibition properties, or other specific chemical properties.
[0027] Currently, imidazoline corrosion inhibitors are mainly oil-soluble. In oilfield production applications, imidazoline is often modified and compounded to improve its water solubility, thus meeting field application requirements. Both compounding and modification can improve the water solubility and stability of imidazoline, thereby enhancing its corrosion inhibition effect. However, in the context of pipeline carbon dioxide transportation, the use of water-soluble corrosion inhibitors faces many limitations. Modification by introducing polar groups can increase the surface adsorption of the corrosion inhibitor, effectively improving its corrosion inhibition performance. Modification of imidazoline corrosion inhibitors can be achieved by quaternizing the tertiary amine on the imidazoline ring or by addition or condensation of the primary amine attached to the imidazoline ring.
[0028] The carbon dioxide corrosion inhibitor described in this invention significantly reduces the corrosion rate of sample steel sheets during supercritical carbon dioxide pipeline transportation. The synthesis process is safe and efficient. Compared with existing carbon dioxide corrosion inhibitors on the market, the carbon dioxide corrosion inhibitor provided by this invention has a better corrosion inhibition effect and can be used in a wider range of operating conditions. Attached Figure Description
[0029] Figure 1 This is a schematic diagram of the imidazoline structure;
[0030] Figure 2 The infrared spectrum of the carbon dioxide corrosion inhibitor prepared in Example 1 of this invention;
[0031] Figure 3 The carbon dioxide corrosion inhibitor prepared in Example 1 of this invention 13 C10 NMR spectrum. Detailed Implementation
[0032] Unless otherwise specified, the parts referred to in this application are parts by mass, and the percentages referred to are percentages by mass.
[0033] The dimer acid described in this embodiment of the invention is from Shanghai Zhipu Chemical Co., Ltd., and is a mixture of the following three compounds:
[0034]
[0035]
[0036] Example 1
[0037] Preparation of imidazoline dimer:
[0038] 114 parts of dimer acid and 41 parts of diethylenetriamine were added to a three-necked flask equipped with a condenser, stirrer, and water separator. 50 parts of xylene (water-carrying agent) and 1 part of boric acid (stabilizer) were added to carry out an amidation reaction: under a nitrogen atmosphere and stirring, the mixture was kept at 160°C for 3 hours at a stirring rate of 400 rpm. Then, a cyclization and dehydration reaction was carried out: the temperature was raised to 240°C and the stirring rate was 400 rpm. The mixture was heated until the system was in a reflux water separation state, and heating was stopped when no water was precipitated. The reaction terminated naturally. After cooling, a vacuum pump was connected, and unreacted raw materials and un-flowed water-carrying agents were removed under reduced pressure to obtain dimer acid imidazoline.
[0039] The structural formula of the dimer acid imidazoline is shown in formula (1):
[0040]
[0041] Wherein, R is selected from:
[0042] Preparation of carbon dioxide corrosion inhibitor:
[0043] Thiourea and 112 parts of the prepared dimer acid imidazoline were added to a three-necked flask for an addition reaction: the mixture was kept at 110°C for 4 hours with a stirring speed of 500 rpm under stirring conditions to obtain crude thiourea-based dimer acid imidazoline. The synthesized crude thiourea-based dimer acid imidazoline was subjected to vacuum distillation, and then washed with a mixed solvent of acetone and toluene (acetone and toluene volume ratio of 1:1). The mixture was filtered at room temperature and repeated 3 times to obtain thiourea-based dimer acid imidazoline (carbon dioxide corrosion inhibitor).
[0044] Structural testing: The infrared spectrum of the carbon dioxide corrosion inhibitor prepared in this embodiment was tested. 13 C10 NMR spectrum.
[0045] The infrared spectrum of the carbon dioxide corrosion inhibitor prepared in this embodiment is as follows: Figure 2 As shown, 3297cm -1 The absorption peak at 2924 cm⁻¹ is the N-H stretching vibration peak of primary amines. -1 and 2853cm -1 The peaks at 1646 cm⁻¹ represent the vibrational absorption peaks of the C-H groups of methyl and methylene groups, respectively. -1 The absorption peak at 1466 cm⁻¹ is the C=N stretching vibration peak of the imidazoline ring. -1 This is the absorption peak for the bending vibrations of methyl and methylene groups. 1297 cm⁻¹ -1 The absorption peak at this point is the C=S stretching vibration. Based on the absorption peak analysis of the above groups, it can be seen that the carbon dioxide corrosion inhibitor prepared in this embodiment is thiourea-based dimer acid imidazoline.
[0046] The corrosion inhibitor prepared in this embodiment 13 The C NMR spectrum is as follows Figure 3 As shown, after analysis and comparison, δ183.73 (32C) is the characteristic absorption peak of C=S double bond, and δ48.53 (30C) is the characteristic absorption peak of secondary amine.
[0047] The thiourea-based dimer acid imidazoline prepared in this embodiment is shown in formula (2):
[0048]
[0049] Wherein, R is selected from:
[0050] The corrosion rate and inhibition rate of the carbon dioxide corrosion inhibitor prepared in this embodiment were tested using the method specified in GB / T 35509-2017 "Application and Evaluation of Corrosion Inhibitors in Oil and Gas Fields". The carbon dioxide corrosion inhibitor prepared in this embodiment and X65 steel sheets were added to a high-temperature and high-pressure reactor. The operating conditions were set as follows: pressure 7.65 MPa, temperature 55℃, and corrosion time 6 h. 30 g of 3.5% NaCl solution was added to the reactor to simulate the corrosion situation during the pipeline transportation of supercritical carbon dioxide. The blank corrosion rate was 0.6171 mm / a, and the corrosion rate after adding the corrosion inhibitor was 0.0821 mm / a, with an inhibition rate of 86.7%.
[0051] Example 2
[0052] Preparation of imidazoline dimer:
[0053] 114 parts of dimer acid and 31 parts of diethylenetriamine were added to a three-necked flask equipped with a condenser, stirrer, and water separator. 50 parts of xylene (water-carrying agent) and 1 part of boric acid (stabilizer) were added to carry out an amidation reaction: under a nitrogen atmosphere and stirring, the mixture was kept at 150°C for 3 hours at a stirring rate of 400 rpm. Then, a cyclization and dehydration reaction was carried out: the temperature was raised to 240°C and the stirring rate was 400 rpm. The mixture was heated until the system was in a reflux state and water separation state was maintained until no water was separated. Heating was stopped and the reaction terminated naturally. After cooling, a vacuum pump was connected, and unreacted raw materials and un-flowed water-carrying agents were removed under reduced pressure to obtain dimer acid imidazoline, whose structural formula is the same as in Example 1.
[0054] Preparation of carbon dioxide corrosion inhibitor:
[0055] Thiourea and 112 parts of the prepared dimer acid imidazoline were added to a three-necked flask for an addition reaction: the mixture was kept at 110°C for 4 hours with a stirring speed of 500 rpm under stirring conditions to obtain crude thiourea-based dimer acid imidazoline. The synthesized crude thiourea-based dimer acid imidazoline was subjected to vacuum distillation, and then washed with a mixed solvent of acetone and toluene (acetone and toluene volume ratio of 1:1). The mixture was filtered at room temperature and repeated 3 times to obtain thiourea-based dimer acid imidazoline (carbon dioxide corrosion inhibitor).
[0056] Structural testing: The infrared spectrum of the carbon dioxide corrosion inhibitor prepared in this embodiment was tested and... 13 The C NMR spectrum and test results are consistent with those of Example 1. The carbon dioxide corrosion inhibitor prepared in this example is thiourea-based dimer acid imidazoline, and its structural formula is the same as that of Example 1.
[0057] The corrosion rate and inhibition rate of the carbon dioxide corrosion inhibitor prepared in this embodiment were tested using the method specified in GB / T 35509-2017 "Application and Evaluation of Corrosion Inhibitors in Oil and Gas Fields". The carbon dioxide corrosion inhibitor prepared in this embodiment and X65 steel sheets were added to a high-temperature and high-pressure reactor. The operating conditions were set as follows: pressure 7.65 MPa, temperature 55℃, and corrosion time 6 h. 30 g of 3.5% NaCl solution was added to the reactor to simulate the corrosion situation during the pipeline transportation of supercritical carbon dioxide. The blank corrosion rate was 0.6171 mm / a, and the corrosion rate after adding the corrosion inhibitor was 0.1327 mm / a, with an inhibition rate of 78.5%.
[0058] Example 3
[0059] Preparation of imidazoline dimer:
[0060] 114 parts of dimer acid and 35 parts of diethylenetriamine were added to a three-necked flask equipped with a condenser, stirrer, and water separator. 50 parts of xylene (water-carrying agent) and 1 part of boric acid (stabilizer) were added to carry out an amidation reaction: under a nitrogen atmosphere and stirring, the mixture was kept at 140°C for 4 hours at a stirring rate of 400 rpm. Then, a cyclization and dehydration reaction was carried out: the temperature was raised to 230°C and the stirring rate was 400 rpm. The mixture was heated until the system was in a reflux water separation state, and heating was stopped when no water was separated. The reaction terminated naturally. After cooling, a vacuum pump was connected, and unreacted raw materials and unflowed water-carrying agents were removed under reduced pressure to obtain dimer acid imidazoline, whose structural formula is the same as in Example 1.
[0061] Preparation of carbon dioxide corrosion inhibitor:
[0062] 15 parts of thiourea and 119 parts of the dimer acid imidazoline prepared above were added to a three-necked flask for an addition reaction: under stirring conditions, the mixture was kept at 110°C for 4 hours at a stirring speed of 500 rpm; crude thiourea-based dimer acid imidazoline was obtained; the synthesized crude thiourea-based dimer acid imidazoline was subjected to vacuum distillation, and then washed with a mixed solvent of acetone and toluene (the volume ratio of acetone and toluene was 1:1), filtered at room temperature, and repeated 3 times to obtain thiourea-based dimer acid imidazoline (carbon dioxide corrosion inhibitor).
[0063] Structural testing: The infrared spectrum of the carbon dioxide corrosion inhibitor prepared in this embodiment was tested and... 13 The C NMR spectrum and test results are consistent with those of Example 1. The carbon dioxide corrosion inhibitor prepared in this example is thiourea-based dimer acid imidazoline, and its structural formula is the same as that of Example 1.
[0064] The corrosion rate and inhibition rate of the carbon dioxide corrosion inhibitor prepared in this embodiment were tested using the method specified in GB / T 35509-2017 "Application and Evaluation of Corrosion Inhibitors in Oil and Gas Fields". The carbon dioxide corrosion inhibitor prepared in this embodiment and X65 steel sheets were added to a high-temperature and high-pressure reactor. The operating conditions were set as follows: pressure 7.65 MPa, temperature 55℃, and corrosion time 6 h. 30 g of 3.5% NaCl solution was added to the reactor to simulate the corrosion situation during the pipeline transportation of supercritical carbon dioxide. The blank corrosion rate was 0.6171 mm / a, and the corrosion rate after adding the corrosion inhibitor was 0.1290 mm / a, with an inhibition rate of 79.1%.
[0065] Example 4
[0066] Preparation of imidazoline dimer:
[0067] 114 parts of dimer acid and 40 parts of diethylenetriamine were added to a three-necked flask equipped with a condenser, stirrer, and water separator. 50 parts of xylene (water-carrying agent) and 1 part of boric acid (stabilizer) were added to carry out an amidation reaction: under a nitrogen atmosphere and stirring, the mixture was kept at 140°C for 5 hours at a stirring rate of 400 rpm. Then, a cyclization and dehydration reaction was carried out: the temperature was raised to 220°C and the stirring rate was 400 rpm. The mixture was heated until the system was in a reflux and water-separating state, and heating was stopped when no water was precipitated. The reaction terminated naturally. After cooling, a vacuum pump was connected, and unreacted raw materials and un-flowed water-carrying agents were removed under reduced pressure to obtain dimer acid imidazoline, whose structural formula is the same as in Example 1.
[0068] Preparation of carbon dioxide corrosion inhibitor:
[0069] 16 parts of thiourea and 125 parts of the dimer acid imidazoline prepared above were added to a three-necked flask for an addition reaction: under stirring conditions, the mixture was kept at 100°C for 4 hours at a stirring speed of 500 rpm; crude thiourea-based dimer acid imidazoline was obtained; the synthesized crude thiourea-based dimer acid imidazoline was subjected to vacuum distillation, and then washed with a mixed solvent of acetone and toluene (the volume ratio of acetone and toluene was 1:1), filtered at room temperature, and repeated 3 times to obtain thiourea-based dimer acid imidazoline (carbon dioxide corrosion inhibitor).
[0070] Structural testing: The infrared spectrum of the carbon dioxide corrosion inhibitor prepared in this embodiment was tested and... 13 The C NMR spectrum and test results are consistent with those of Example 1. The carbon dioxide corrosion inhibitor prepared in this example is thiourea-based dimer acid imidazoline, and its structural formula is the same as that of Example 1.
[0071] The corrosion rate and inhibition rate of the carbon dioxide corrosion inhibitor prepared in this embodiment were tested using the method specified in GB / T 35509-2017 "Application and Evaluation of Corrosion Inhibitors in Oil and Gas Fields". The carbon dioxide corrosion inhibitor prepared in this embodiment and X65 steel sheets were added to a high-temperature and high-pressure reactor. The operating conditions were set as follows: pressure 7.65 MPa, temperature 55℃, and corrosion time 6 h. 30 g of 3.5% NaCl solution was added to the reactor to simulate the corrosion situation during the pipeline transportation of supercritical carbon dioxide. The blank corrosion rate was 0.6171 mm / a, and the corrosion rate after adding the corrosion inhibitor was 0.1135 mm / a, with an inhibition rate of 81.6%.
[0072] Example 5
[0073] Preparation of imidazoline dimer:
[0074] 114 parts of dimer acid and 44 parts of diethylenetriamine were added to a three-necked flask equipped with a condenser, stirrer, and water separator. 50 parts of xylene (water-carrying agent) and 1 part of boric acid (stabilizer) were added to carry out an amidation reaction: under a nitrogen atmosphere and stirring, the mixture was kept at 160°C for 5 hours at a stirring rate of 400 rpm. Then, a cyclization and dehydration reaction was carried out: the temperature was raised to 240°C and the stirring rate was 400 rpm. The mixture was heated until the system was in a reflux water separation state, and heating was stopped when no water was separated. The reaction terminated naturally. After cooling, a vacuum pump was connected, and unreacted raw materials and unflowed water-carrying agents were removed under reduced pressure to obtain dimer acid imidazoline, whose structural formula is the same as in Example 1.
[0075] Preparation of carbon dioxide corrosion inhibitor:
[0076] 17 parts of thiourea and 125 parts of the dimer acid imidazoline prepared above were added to a three-necked flask for an addition reaction: under stirring conditions, the mixture was kept at 120°C for 4 hours at a stirring speed of 500 rpm; crude thiourea-based dimer acid imidazoline was obtained; the synthesized crude thiourea-based dimer acid imidazoline was subjected to vacuum distillation, and then washed with a mixed solvent of acetone and toluene (the volume ratio of acetone and toluene was 1:1), filtered at room temperature, and repeated 3 times to obtain thiourea-based dimer acid imidazoline (carbon dioxide corrosion inhibitor).
[0077] Structural testing: The infrared spectrum of the carbon dioxide corrosion inhibitor prepared in this embodiment was tested and... 13 The C NMR spectrum and test results are consistent with those of Example 1. The carbon dioxide corrosion inhibitor prepared in this example is thiourea-based dimer acid imidazoline, and its structural formula is the same as that of Example 1.
[0078] The corrosion rate and inhibition rate of the carbon dioxide corrosion inhibitor prepared in this embodiment were tested using the method specified in GB / T 35509-2017 "Application and Evaluation of Corrosion Inhibitors in Oil and Gas Fields". The carbon dioxide corrosion inhibitor prepared in this embodiment was mixed with X65 steel sheets and added to a high-temperature, high-pressure reactor. The operating conditions were set as follows: pressure 7.65 MPa, temperature 55 °C, and corrosion time 6 h. 30 g of 3.5% NaCl solution was added to the reactor to simulate the corrosion during the pipeline transport of supercritical carbon dioxide. The blank corrosion rate was 0.6171 mm / a, and the corrosion rate after adding the corrosion inhibitor was 0.1320 mm / a, with an inhibition rate of 78.6%.
[0079] Example 6
[0080] Preparation of imidazoline dimer:
[0081] 114 parts of dimer acid and 48 parts of diethylenetriamine were added to a three-necked flask equipped with a condenser, stirrer, and water separator. 50 parts of xylene (water-carrying agent) and 1 part of boric acid (stabilizer) were added to carry out an amidation reaction: under a nitrogen atmosphere and stirring, the mixture was kept at 160°C for 3 hours at a stirring rate of 400 rpm. Then, a cyclization and dehydration reaction was carried out: the temperature was raised to 240°C and the stirring rate was 400 rpm. The mixture was heated until the system was in a reflux water separation state, and heating was stopped when no water was precipitated. The reaction terminated naturally. After cooling, a vacuum pump was connected, and unreacted raw materials and unflowed water-carrying agents were removed under reduced pressure to obtain dimer acid imidazoline, whose structural formula is the same as in Example 1.
[0082] Preparation of carbon dioxide corrosion inhibitor:
[0083] 14 parts of thiourea and 105 parts of the prepared dimer acid imidazoline were added to a three-necked flask for an addition reaction: under stirring, the temperature was raised to 110°C and the addition reaction was carried out at 110°C for 4 hours with a stirring speed of 500 rpm; crude thiourea-based dimer acid imidazoline was obtained; the synthesized crude thiourea-based dimer acid imidazoline was subjected to vacuum distillation, and then washed with a mixed solvent of acetone and toluene (the volume ratio of acetone and toluene was 1:1), filtered at room temperature, and repeated 3 times to obtain thiourea-based dimer acid imidazoline (carbon dioxide corrosion inhibitor).
[0084] Structural testing: The infrared spectrum of the carbon dioxide corrosion inhibitor prepared in this embodiment was tested and... 13 The C NMR spectrum and test results are consistent with those of Example 1. The carbon dioxide corrosion inhibitor prepared in this example is thiourea-based dimer acid imidazoline, and its structural formula is the same as that of Example 1.
[0085] The corrosion rate and inhibition rate of the carbon dioxide corrosion inhibitor prepared in this embodiment were tested using the method specified in GB / T 35509-2017 "Application and Evaluation of Corrosion Inhibitors in Oil and Gas Fields". The carbon dioxide corrosion inhibitor prepared in this embodiment and X65 steel sheets were added to a high-temperature and high-pressure reactor. The operating conditions were set as follows: pressure 7.65 MPa, temperature 50℃, and corrosion time 10 h. 30 g of 3.5% NaCl solution was added to the reactor to simulate the corrosion of steel by supercritical carbon dioxide. The blank corrosion rate was 0.6171 mm / a, the corrosion rate after adding the corrosion inhibitor was 0.1080 mm / a, and the inhibition rate was 82.5%.
[0086] Example 7
[0087] Preparation of imidazoline dimer:
[0088] 114 parts of dimer acid and 52 parts of diethylenetriamine were added to a three-necked flask equipped with a condenser, stirrer, and water separator. 50 parts of xylene (water-carrying agent) and 1 part of boric acid (stabilizer) were added to carry out an amidation reaction: under a nitrogen atmosphere and stirring, the mixture was kept at 160°C for 3 hours at a stirring rate of 400 rpm. Then, a cyclization and dehydration reaction was carried out: the temperature was raised to 240°C and the stirring rate was 400 rpm. The mixture was heated until the system was in a reflux state and water separation state was maintained until no water was separated. Heating was stopped and the reaction terminated naturally. After cooling, a vacuum pump was connected, and unreacted raw materials and un-flowed water-carrying agents were removed under reduced pressure to obtain dimer acid imidazoline, whose structural formula is the same as in Example 1.
[0089] Preparation of carbon dioxide corrosion inhibitor:
[0090] 15 parts of thiourea and 105 parts of the dimer acid imidazoline prepared above were added to a three-necked flask for an addition reaction: under stirring conditions, the mixture was kept at 110°C for 5 hours at a stirring speed of 500 rpm; crude thiourea-based dimer acid imidazoline was obtained; the synthesized crude thiourea-based dimer acid imidazoline was subjected to vacuum distillation, and then washed with a mixed solvent of acetone and toluene (the volume ratio of acetone and toluene was 1:1), filtered at room temperature, and repeated 3 times to obtain thiourea-based dimer acid imidazoline (carbon dioxide corrosion inhibitor).
[0091] Structural testing: The infrared spectrum of the carbon dioxide corrosion inhibitor prepared in this embodiment was tested and... 13 The C NMR spectrum and test results are consistent with those of Example 1. The carbon dioxide corrosion inhibitor prepared in this example is thiourea-based dimer acid imidazoline, and its structural formula is the same as that of Example 1.
[0092] The corrosion rate and inhibition rate of the carbon dioxide corrosion inhibitor prepared in this embodiment were tested using the method specified in GB / T 35509-2017 "Application and Evaluation of Corrosion Inhibitors in Oil and Gas Fields". The carbon dioxide corrosion inhibitor prepared in this embodiment and X65 steel sheets were added to a high-temperature and high-pressure reactor. The operating conditions were set as follows: pressure 7.65 MPa, temperature 55℃, and corrosion time 10 h. 30 g of 3.5% NaCl solution was added to the reactor to simulate the corrosion of steel by supercritical carbon dioxide. The blank corrosion rate was 0.6171 mm / a, and the corrosion rate after adding the corrosion inhibitor was 0.1043 mm / a, with an inhibition rate of 83.1%.
[0093] Example 8
[0094] Preparation of imidazoline dimer:
[0095] 114 parts of dimer acid and 56 parts of diethylenetriamine were added to a three-necked flask equipped with a condenser, stirrer, and water separator. 50 parts of xylene (water-carrying agent) and 1 part of boric acid (stabilizer) were added to carry out an amidation reaction: under a nitrogen atmosphere and stirring, the mixture was kept at 160°C for 3 hours at a stirring rate of 400 rpm. Then, a cyclization and dehydration reaction was carried out: the temperature was raised to 240°C and the stirring rate was 400 rpm. The mixture was heated until the system was in a reflux state and water separation state was maintained until no water was separated. Heating was stopped and the reaction terminated naturally. After cooling, a vacuum pump was connected, and unreacted raw materials and un-flowed water-carrying agents were removed under reduced pressure to obtain dimer acid imidazoline, whose structural formula is the same as in Example 1.
[0096] Preparation of carbon dioxide corrosion inhibitor:
[0097] 19 parts of thiourea and 123 parts of the dimer acid imidazoline prepared above were added to a three-necked flask for an addition reaction: under stirring conditions, the mixture was kept at 110°C for 4 hours at a stirring speed of 500 rpm; crude thiourea-based dimer acid imidazoline was obtained; the synthesized crude thiourea-based dimer acid imidazoline was subjected to vacuum distillation, and then washed with a mixed solvent of acetone and toluene (the volume ratio of acetone and toluene was 1:1), filtered at room temperature, and repeated 3 times to obtain thiourea-based dimer acid imidazoline (carbon dioxide corrosion inhibitor).
[0098] Structural testing: The infrared spectrum of the carbon dioxide corrosion inhibitor prepared in this embodiment was tested and... 13 The C NMR spectrum and test results are consistent with those of Example 1. The carbon dioxide corrosion inhibitor prepared in this example is thiourea-based dimer acid imidazoline, and its structural formula is the same as that of Example 1.
[0099] The corrosion rate and inhibition rate of the carbon dioxide corrosion inhibitor prepared in this embodiment were tested using the method specified in GB / T 35509-2017 "Application and Evaluation of Corrosion Inhibitors in Oil and Gas Fields". The carbon dioxide corrosion inhibitor prepared in this embodiment and X65 steel sheets were added to a high-temperature and high-pressure reactor. The operating conditions were set as follows: pressure 7.65 MPa, temperature 60℃, and corrosion time 10 h. 30 g of 3.5% NaCl solution was added to the reactor to simulate the corrosion of steel by supercritical carbon dioxide. The blank corrosion rate was 0.6171 mm / a, and the corrosion rate after adding the corrosion inhibitor was 0.1178 mm / a, with an inhibition rate of 80.9%.
[0100] Example 9
[0101] Preparation of imidazoline dimer:
[0102] 114 parts of dimer acid and 60 parts of diethylenetriamine were added to a three-necked flask equipped with a condenser, stirrer, and water separator. 50 parts of xylene (water-carrying agent) and 1 part of boric acid (stabilizer) were added to carry out an amidation reaction: under a nitrogen atmosphere and stirring, the mixture was kept at 150°C for 4 hours at a stirring rate of 400 rpm. Then, a cyclization and dehydration reaction was carried out: the temperature was raised to 230°C and the stirring rate was 400 rpm. The mixture was heated until the system was in a reflux water separation state, and heating was stopped when no water was precipitated. The reaction terminated naturally. After cooling, a vacuum pump was connected, and unreacted raw materials and un-flowed water-carrying agents were removed under reduced pressure to obtain dimer acid imidazoline, whose structural formula is the same as in Example 1.
[0103] Preparation of carbon dioxide corrosion inhibitor:
[0104] 21 parts of thiourea and 123 parts of the dimer acid imidazoline prepared above were added to a three-necked flask for an addition reaction: under stirring conditions, the mixture was kept at 110°C for 5 hours at a stirring speed of 500 rpm; crude thiourea-based dimer acid imidazoline was obtained; the synthesized crude thiourea-based dimer acid imidazoline was subjected to vacuum distillation, and then washed with a mixed solvent of acetone and toluene (the volume ratio of acetone and toluene was 1:1), filtered at room temperature, and repeated 3 times to obtain thiourea-based dimer acid imidazoline (carbon dioxide corrosion inhibitor).
[0105] Structural testing: The infrared spectrum of the carbon dioxide corrosion inhibitor prepared in this embodiment was tested and... 13 The C NMR spectrum and test results are consistent with those of Example 1. The carbon dioxide corrosion inhibitor prepared in this example is thiourea-based dimer acid imidazoline, and its structural formula is the same as that of Example 1.
[0106] The corrosion rate and inhibition rate of the carbon dioxide corrosion inhibitor prepared in this embodiment were tested using the method specified in GB / T 35509-2017 "Application and Evaluation of Corrosion Inhibitors in Oil and Gas Fields". The carbon dioxide corrosion inhibitor prepared in this embodiment and X65 steel sheets were added to a high-temperature and high-pressure reactor. The operating conditions were set as follows: pressure 7.65 MPa, temperature 65℃, and corrosion time 10 h. 30 g of 3.5% NaCl solution was added to the reactor to simulate the corrosion of steel by supercritical carbon dioxide. The blank corrosion rate was 0.6171 mm / a, and the corrosion rate after adding the corrosion inhibitor was 0.1166 mm / a, with an inhibition rate of 81.1%.
[0107] Example 10
[0108] Preparation of imidazoline dimer:
[0109] 114 parts of dimer acid and 62 parts of diethylenetriamine were added to a three-necked flask equipped with a condenser, stirrer, and water separator. 50 parts of xylene (water-carrying agent) and 1 part of boric acid (stabilizer) were added to carry out an amidation reaction: under a nitrogen atmosphere and stirring, the mixture was kept at 160°C for 3 hours at a stirring rate of 400 rpm. Then, a cyclization and dehydration reaction was carried out: the temperature was raised to 240°C and the stirring rate was 400 rpm. The mixture was heated until the system was in a reflux water separation state, and heating was stopped when no water was precipitated. The reaction terminated naturally. After cooling, a vacuum pump was connected, and unreacted raw materials and un-flowed water-carrying agents were removed under reduced pressure to obtain dimer acid imidazoline, whose structural formula is the same as in Example 1.
[0110] Preparation of carbon dioxide corrosion inhibitor:
[0111] 19 parts of thiourea and 114 parts of the dimer acid imidazoline prepared above were added to a three-necked flask for an addition reaction: under stirring conditions, the mixture was kept at 120°C for 6 hours at a stirring speed of 500 rpm; crude thiourea-based dimer acid imidazoline was obtained; the synthesized crude thiourea-based dimer acid imidazoline was subjected to vacuum distillation, and then washed with a mixed solvent of acetone and toluene (the volume ratio of acetone and toluene was 1:1), filtered at room temperature, and repeated 3 times to obtain thiourea-based dimer acid imidazoline (carbon dioxide corrosion inhibitor).
[0112] Structural testing: The infrared spectrum of the carbon dioxide corrosion inhibitor prepared in this embodiment was tested and... 13 The C NMR spectrum and test results are consistent with those of Example 1. The carbon dioxide corrosion inhibitor prepared in this example is thiourea-based dimer acid imidazoline, and its structural formula is the same as that of Example 1.
[0113] The corrosion rate and inhibition rate of the carbon dioxide corrosion inhibitor prepared in this embodiment were tested using the method specified in GB / T 35509-2017 "Application and Evaluation of Corrosion Inhibitors in Oil and Gas Fields". The carbon dioxide corrosion inhibitor prepared in this embodiment was added to an X65 steel sheet in a high-temperature and high-pressure reactor. The operating conditions were set as follows: pressure 7.65 MPa, temperature 55℃, and corrosion time 24 h. 30 g of 3.5% NaCl solution was added to the reactor to simulate the corrosion process of supercritical carbon dioxide on steel. The blank corrosion rate was 0.6171 mm / a, and the corrosion rate after adding the corrosion inhibitor was 0.1308 mm / a, with an inhibition rate of 78.8%.
[0114] Comparative Example 1
[0115] The carbon dioxide corrosion inhibitor used in this comparative example is imidazoline oleate.
[0116] The corrosion rate and inhibition rate of the carbon dioxide corrosion inhibitor in this comparative example were tested using the method specified in GB / T 35509-2017 "Application and Evaluation of Corrosion Inhibitors in Oil and Gas Fields". The carbon dioxide corrosion inhibitor (imidazoline oleate) of this comparative example was added to an X65 steel sheet in a high-temperature and high-pressure reactor. The operating conditions were set as follows: pressure 7.65 MPa, temperature 55℃, and corrosion time 24 h. 30 g of 3.5% NaCl solution was added to the reactor to simulate the corrosion process of supercritical carbon dioxide on steel. The blank corrosion rate was 0.6171 mm / a, and the corrosion rate after adding the corrosion inhibitor was 0.1808 mm / a, with an inhibition rate of 70.7%.
[0117] Comparative Example 2
[0118] The carbon dioxide corrosion inhibitor used in this comparative example is thiourea-based dimer acid imidazoline.
[0119] Preparation of imidazoline dimer:
[0120] 114 parts of dimer acid and 58 parts of triethylenetetramine were added to a three-necked flask equipped with a condenser, stirrer, and water separator. 50 parts of xylene (water-carrying agent) and 1 part of boric acid (stabilizer) were added to carry out an amidation reaction: under a nitrogen atmosphere and stirring, the mixture was kept at 160°C for 3 hours at a stirring rate of 400 rpm. Then, a cyclization and dehydration reaction was carried out: the temperature was raised to 200°C and the stirring rate was 400 rpm. The mixture was heated until the system was in a reflux state and water separation state was maintained until no water was separated. Heating was stopped and the reaction terminated naturally. After cooling, a vacuum pump was connected, and unreacted raw materials and unexplained water-carrying agents were removed under reduced pressure to obtain dimer acid imidazoline.
[0121] Preparation of carbon dioxide corrosion inhibitor:
[0122] 19 parts of thiourea and 114 parts of the dimer acid imidazoline prepared above were added to a three-necked flask for an addition reaction: under stirring conditions, the mixture was kept at 120°C for 4 hours at a stirring speed of 500 rpm; crude thiourea-based dimer acid imidazoline was obtained; the synthesized crude thiourea-based dimer acid imidazoline was subjected to vacuum distillation, and then washed with a mixed solvent of acetone and toluene (the volume ratio of acetone and toluene was 1:1), filtered at room temperature, and repeated 3 times to obtain thiourea-based dimer acid imidazoline (carbon dioxide corrosion inhibitor).
[0123] The corrosion rate and inhibition rate of the carbon dioxide corrosion inhibitor in this comparative example were tested using the method specified in GB / T 35509-2017 "Application and Evaluation of Corrosion Inhibitors in Oil and Gas Fields". The carbon dioxide corrosion inhibitor (thiourea-based dimer acid imidazoline) and X65 steel sheets were added to a high-temperature, high-pressure reactor. The operating conditions were set as follows: pressure 7.65 MPa, temperature 55 °C, and corrosion time 24 h. 30 g of 3.5% NaCl solution was added to the reactor to simulate the corrosion process of supercritical carbon dioxide on steel. The blank corrosion rate was 0.6171 mm / a, and the corrosion rate after adding the corrosion inhibitor was 0.1388 mm / a, with an inhibition rate of 77.5%.
[0124] Comparative Example 3
[0125] The carbon dioxide corrosion inhibitor used in this comparative example is thiourea-based dimer acid imidazoline.
[0126] Preparation of imidazoline dimer:
[0127] 114 parts of dimer acid and 76 parts of tetraethylenepentamine were added to a three-necked flask equipped with a condenser, stirrer, and water separator. 50 parts of xylene (water-carrying agent) and 1 part of boric acid (stabilizer) were added to carry out an amidation reaction: under a nitrogen atmosphere and stirring, the mixture was kept at 160°C for 3 hours at a stirring rate of 400 rpm. Then, a cyclization and dehydration reaction was carried out: the temperature was raised to 200°C and the stirring rate was 400 rpm. The mixture was heated until the system was in a reflux state and water separation state was maintained until no water was separated. Heating was stopped and the reaction terminated naturally. After cooling, a vacuum pump was connected, and unreacted raw materials and unexplained water-carrying agents were removed under reduced pressure to obtain dimer acid imidazoline.
[0128] Preparation of carbon dioxide corrosion inhibitor:
[0129] 19 parts of thiourea and 114 parts of the dimer acid imidazoline prepared above were added to a three-necked flask for an addition reaction: under stirring conditions, the mixture was kept at 120°C for 4 hours at a stirring speed of 500 rpm; crude thiourea-based dimer acid imidazoline was obtained; the synthesized crude thiourea-based dimer acid imidazoline was subjected to vacuum distillation, and then washed with a mixed solvent of acetone and toluene (the volume ratio of acetone and toluene was 1:1), filtered at room temperature, and repeated 3 times to obtain thiourea-based dimer acid imidazoline (carbon dioxide corrosion inhibitor).
[0130] The corrosion rate and inhibition rate of the carbon dioxide corrosion inhibitor in this comparative example were tested using the method specified in GB / T 35509-2017 "Application and Evaluation of Corrosion Inhibitors in Oil and Gas Fields". The carbon dioxide corrosion inhibitor (thiourea-based dimer acid imidazoline) of this comparative example was added to an X65 steel sheet in a high-temperature and high-pressure reactor. The operating conditions were set as follows: pressure 7.65 MPa, temperature 55℃, and corrosion time 24 h. 30 g of 3.5% NaCl solution was added to the reactor to simulate the corrosion process of supercritical carbon dioxide on steel. The blank corrosion rate was 0.6171 mm / a, and the corrosion rate after adding the corrosion inhibitor was 0.1777 mm / a, with an inhibition rate of 71.2%.
[0131] Comparative Example 4
[0132] The carbon dioxide corrosion inhibitor used in this comparative example is imidazoline lauryl acid.
[0133] Preparation of imidazoline lauryl acid:
[0134] 40 parts of lauric acid and 24 parts of diethylenetriamine were added to a three-necked flask equipped with a condenser, stirrer, and water separator. 40 parts of xylene (water-carrying agent) and 1 part of boric acid (stabilizer) were added to carry out an amidation reaction: under a nitrogen atmosphere and stirring, the mixture was kept at 160°C for 3 hours at a stirring rate of 400 rpm. Then, a cyclization and dehydration reaction was carried out: the temperature was raised to 200°C and the stirring rate was 400 rpm. The mixture was heated until the system was in a reflux state and water separation state was maintained until no water was separated. Heating was then stopped and the reaction terminated naturally. After cooling, a vacuum pump was connected, and unreacted raw materials and unexplained water-carrying agents were removed under reduced pressure to obtain lauric acid imidazoline.
[0135] The corrosion rate and inhibition rate of the carbon dioxide corrosion inhibitor in this comparative example were tested using the method specified in GB / T 35509-2017 "Application and Evaluation of Corrosion Inhibitors in Oil and Gas Fields". The carbon dioxide corrosion inhibitor (imidazoline laurate) and X65 steel sheets were added to a high-temperature, high-pressure reactor. The operating conditions were set as follows: pressure 7.65 MPa, temperature 55℃, and corrosion time 24 h. 30 g of 3.5% NaCl solution was added to the reactor to simulate the corrosion process of supercritical carbon dioxide on steel. The blank corrosion rate was 0.6171 mm / a, and the corrosion rate after adding the corrosion inhibitor was 0.2043 mm / a, with an inhibition rate of 66.9%.
[0136] Comparative Example 5
[0137] The carbon dioxide corrosion inhibitor used in this comparative example is imidazoline dimer acid.
[0138] Preparation of imidazoline dimer:
[0139] 114 parts of dimer acid and 41 parts of diethylenetriamine were added to a three-necked flask equipped with a condenser, stirrer, and water separator. 50 parts of xylene (water-carrying agent) and 1 part of boric acid (stabilizer) were added to carry out an amidation reaction: under a nitrogen atmosphere and stirring, the mixture was kept at 160°C for 3 hours at a stirring rate of 400 rpm. Then, a cyclization and dehydration reaction was carried out: the temperature was raised to 200°C and the stirring rate was 400 rpm. The mixture was heated until the system was in a reflux state and water separation state was maintained until no water was separated. Heating was stopped and the reaction terminated naturally. After cooling, a vacuum pump was connected, and unreacted raw materials and unexplained water-carrying agents were removed under reduced pressure to obtain dimer acid imidazoline.
[0140] The corrosion rate and inhibition rate of the carbon dioxide corrosion inhibitor in this comparative example were tested using the method specified in GB / T 35509-2017 "Application and Evaluation of Corrosion Inhibitors in Oil and Gas Fields". The carbon dioxide corrosion inhibitor (imidazoline oleate) of this comparative example was added to an X65 steel sheet in a high-temperature and high-pressure reactor. The operating conditions were set as follows: pressure 7.65 MPa, temperature 55℃, and corrosion time 24 h. 30 g of 3.5% NaCl solution was added to the reactor to simulate the corrosion process of supercritical carbon dioxide on steel. The blank corrosion rate was 0.6171 mm / a, and the corrosion rate after adding the corrosion inhibitor was 0.1629 mm / a, with an inhibition rate of 73.6%.
[0141] As can be seen from the above examples and comparative examples, compared with comparative examples 1-5, the carbon dioxide corrosion inhibitors prepared in examples 1-10 have a corrosion rate of less than 0.133 mm / a and a corrosion inhibition rate of greater than 78%, showing better corrosion inhibition effect. The preparation methods of examples 1-10 can be summarized as follows:
[0142] Preparation method of dimer acid imidazoline:
[0143] (1) Take dimer acid and diethylenetriamine in a mass ratio of 114:31 to 62, add xylene (water-carrying agent) and boric acid (stabilizer), and carry out amidation reaction under nitrogen atmosphere and stirring conditions;
[0144] (2) Under nitrogen atmosphere and stirring conditions, a cyclization and dehydration reaction was carried out to obtain dimer acid imidazoline.
[0145] In step (1), the amidation reaction is carried out at 140–160 °C; in step (2), the cyclization dehydration reaction is carried out at 220–240 °C.
[0146] Preparation method of carbon dioxide corrosion inhibitor:
[0147] Take 105-125 parts by mass of the above-mentioned dimer acid imidazoline and mix it with 13-21 parts by mass of thiourea. Under stirring conditions, carry out an addition reaction to obtain thiourea-based dimer acid imidazoline, which is a carbon dioxide corrosion inhibitor.
[0148] In the preparation method of carbon dioxide corrosion inhibitor, the addition reaction is carried out at 100-120°C.
Claims
1. A dimer acid imidazoline, characterized in that, The dimer acid imidazoline is as shown in formula (1): Wherein, R is selected from:
2. A method for preparing dimer acid imidazoline, characterized in that, The method includes: (1) Take dimer acid and diethylenetriamine in a mass ratio of 114:31 to 62, add water-carrying agent and stabilizer, and carry out amidation reaction under nitrogen atmosphere and stirring conditions; (2) Under nitrogen atmosphere and stirring conditions, a cyclization and dehydration reaction was carried out to obtain dimer acid imidazoline.
3. The method according to claim 2, characterized in that, The water-carrying agent is xylene.
4. The method according to claim 2, characterized in that, The stabilizer is boric acid.
5. The method according to claim 2, characterized in that, Step (1) is carried out at 140–160 °C.
6. The method according to claim 2, characterized in that, Step (2) involves carrying out the cyclization dehydration reaction at 220–240 °C.
7. A carbon dioxide corrosion inhibitor, characterized in that, The carbon dioxide corrosion inhibitor is a thiourea-based dimer acid imidazoline, as shown in formula (2): Wherein, R is selected from:
8. A method for preparing a carbon dioxide corrosion inhibitor, characterized in that, The method includes: Take 105-125 parts by mass of the dimer acid imidazoline of claim 1 or the dimer acid imidazoline prepared by any of claims 2-6, mix with 13-21 parts by mass of thiourea, and carry out an addition reaction under stirring to obtain thiourea-based dimer acid imidazoline, which is a carbon dioxide corrosion inhibitor.
9. The method according to claim 8, characterized in that, The addition reaction is carried out at 100–120 °C.
10. The application of carbon dioxide corrosion inhibitors in supercritical carbon dioxide pipeline transportation, characterized in that, The carbon dioxide corrosion inhibitor is the carbon dioxide corrosion inhibitor of claim 7 or the carbon dioxide corrosion inhibitor prepared by any of the methods of claims 8-9.