A mixed shiff base quaternary ammonium salt type corrosion inhibitor for sewage pipeline and a preparation method thereof

Abstract

The application discloses a mixed Schiff base quaternary ammonium salt type corrosion inhibitor for sewage pipeline corrosion protection, and relates to the field of corrosion inhibitors.The mixed Schiff base quaternary ammonium salt type corrosion inhibitor is prepared according to the following mass ratio: 35-40% of mixed type Schiff base quaternary ammonium salt derivative, 8-10% of epoxy succinic acid serine copolymer, 4-6% of acrylic acid, 6-8% of polyhydric alcohol phosphate, 2-4% of tartaric acid, 5-7% of ethylene glycol, 4-6% of surfactant and 21-36% of solvent.The preparation method comprises the following steps: S1, preparing the mixed type Schiff base quaternary ammonium salt derivative; S2, adding the epoxy succinic acid serine copolymer, the acrylic acid, the polyhydric alcohol phosphate, the ethylene glycol, the tartaric acid and the solvent into the mixed type Schiff base quaternary ammonium salt derivative, and stirring uniformly to obtain a mixture A; and S3, adding the surfactant into the mixture A, and uniformly mixing to obtain the Schiff base quaternary ammonium salt type corrosion inhibitor.The mixed Schiff base quaternary ammonium salt type corrosion inhibitor can reduce the corrosion speed of oilfield sewage pipelines and water injection pipelines, prolong the service life of the pipelines, improve the safe and reliable operation degree of the pipelines, and has the advantages of low dosage, low price and convenient use.

Description

Technical Field

[0001] This invention relates to the field of corrosion protection for sewage pipelines in oil and gas field surface systems, specifically to a mixed Schiff base quaternary ammonium salt type corrosion inhibitor for sewage pipeline corrosion protection and its preparation method. Background Technology

[0002] With rapid social development, the demand for and utilization of oil and gas resources at home and abroad are gradually increasing. In order to ensure the needs of social production, major oil and gas fields at home and abroad are constantly expanding the scale of exploration, development and production.

[0003] During the large-scale extraction of oil and gas, hundreds of millions of tons of produced water are often generated. The composition of produced water is complex. Not only does it differ between different strata and different extraction methods, but the composition of produced water also varies at different times when treated at the same treatment point.

[0004] Therefore, wastewater from oil and gas extraction shares several similar characteristics: it is contaminated with crude oil, has a high degree of mineralization, and contains salts such as sodium chloride, calcium chloride, sodium sulfate, and magnesium chloride. As most oilfields in my country have entered the mid-to-late stages of extraction, in recent years, oil and gas fields have adopted processes such as water injection, nitrogen flooding, and carbon dioxide flooding to increase production. The high-mineralization wastewater combined with corrosive gases creates a harsh media system, leading to corrosion, perforation, and cracking of wastewater pipelines. This not only increases the maintenance costs of oilfields but also pollutes the environment and affects the safe operation of oil and gas fields.

[0005] Therefore, corrosion control of sewage pipelines has become a prominent problem in oilfields. Adding corrosion inhibitors is one of the commonly used measures to address corrosion in oilfields. However, due to the high salinity of sewage, its obvious tendency to scale, and its oxygen content, the corrosive conditions are quite harsh. Currently used corrosion inhibitors in oilfields are effective against CO2 / H2S corrosion, but their inhibitory effect is poor in sewage conditions. Therefore, this invention provides a corrosion inhibitor suitable for surface sewage systems. Summary of the Invention

[0006] To address the problem that existing technologies suffer from severe corrosion conditions due to the high mineralization of wastewater, and that currently used corrosion inhibitors are ineffective against CO2 / H2S corrosion, this invention provides a mixed Schiff base quaternary ammonium salt corrosion inhibitor for wastewater pipeline corrosion protection and its preparation method. This corrosion inhibitor can reduce the corrosion rate of oilfield wastewater pipelines and water injection pipelines, extend pipeline service life, and improve the safe and reliable operation of pipelines. This corrosion inhibitor has advantages such as low dosage, low price, and ease of use.

[0007] This invention is achieved through the following technical solution: a mixed Schiff base quaternary ammonium salt type corrosion inhibitor for corrosion protection of sewage pipelines, wherein the mixed Schiff base quaternary ammonium salt type corrosion inhibitor is formulated according to the following mass ratio: 35-40% mixed Schiff base quaternized derivatives, 8-10% epoxy succinic acid serine copolymer, 4-6% acrylic acid, 6-8% polyol phosphate ester, 2-4% tartaric acid, 5-7% ethylene glycol, 4-6% surfactant, and 21-36% solvent.

[0008] Furthermore, the solvent is isopropanol, ethanol, or a mixture of isopropanol and ethanol.

[0009] Furthermore, the surfactant is Span 80 or Tween 20.

[0010] A method for preparing a mixed Schiff base quaternary ammonium salt type corrosion inhibitor for corrosion protection of sewage pipelines, the preparation method comprising the following steps:

[0011] S1: Preparation of mixed Schiff base quaternized derivatives;

[0012] S2: Add epoxy succinate serine copolymer, acrylic acid, polyol phosphate, ethylene glycol, tartaric acid and solvent to a mixed Schiff base quaternized derivative and stir until homogeneous to obtain mixture A;

[0013] S3: Add a surfactant to mixture A and mix thoroughly to obtain a Schiff base quaternary ammonium salt type corrosion inhibitor.

[0014] Furthermore, when the surfactant is added to mixture A, a solvent is added.

[0015] Furthermore, the preparation of mixed Schiff base quaternized derivatives includes the following steps:

[0016] S1.1: Synthesis of mixed Schiff base intermediates

[0017] S1.2: The mixed Schiff base intermediate is processed to synthesize the mixed Schiff base quaternary ammonium salt derivative.

[0018] Furthermore, the synthesis of the mixed Schiff base intermediate includes the following steps:

[0019] S1.1.1: Tung oil, cinnamaldehyde, and hydroxyethyl ethylenediamine are added to a container in a molar ratio of 0.5:0.5:1.2, and then benzene is added and mixed evenly to obtain mixture B;

[0020] S1.1.2: Heat mixture B and maintain the reaction for 8-10 hours, then cool it down by 20°C;

[0021] S1.1.3: After cooling, distill under reduced pressure to obtain a mixed Schiff base intermediate.

[0022] Further processing of the mixed Schiff base intermediate includes the following steps:

[0023] S1.2.1: Add a quaternizing agent to the mixed Schiff base intermediate to obtain mixture C;

[0024] S1.2.2: Stir mixture C and heat it to react for a period of time;

[0025] S1.2.3: After reacting for a period of time, the temperature is lowered to room temperature to obtain a mixed Schiff base quaternary ammonium salt derivative.

[0026] Compared with the prior art, the present invention has the following beneficial technical effects:

[0027] This invention provides a mixed Schiff base quaternary ammonium salt corrosion inhibitor for corrosion protection of sewage pipelines and its preparation method. The corrosion inhibitor obtained by the method provided by this invention can reduce the corrosion rate of oilfield sewage pipelines and water injection pipelines, extend pipeline service life, and improve the safe and reliable operation of pipelines. This corrosion inhibitor has advantages such as low dosage, low price, and ease of use. Detailed Implementation

[0028] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of the invention. Therefore, the description is considered to be exemplary in nature and not restrictive.

[0029] The embodiments of the present invention will be described in detail below.

[0030] In a preferred embodiment of the present invention:

[0031] This invention provides a mixed Schiff base quaternary ammonium salt type corrosion inhibitor for corrosion protection of sewage pipelines. The corrosion inhibitor is provided by mass ratio as follows: 35-40% mixed Schiff base quaternized derivatives, 8-10% epoxy succinic acid serine copolymer, 4-6% acrylic acid, 6-8% polyol phosphate ester, 2-4% tartaric acid, 5-7% ethylene glycol, 4-6% surfactant, and 21-36% solvent isopropanol or ethanol; the surfactant is Span 80 or Tween 20.

[0032] The synthesis steps of the mixed Schiff base quaternized derivative are as follows: tung oil, cinnamaldehyde, and organic amine are added to a three-necked flask in a molar ratio of 0.5:0.5:1.2, then a certain amount of benzene is added and mixed evenly. The mixture is heated to a reflux temperature of 80°C and maintained for 8-10 hours. Then, the azeotrope of benzene and ethanol and the water produced in the reaction are removed by vacuum distillation at 60°C. After cooling, the Schiff base intermediate is obtained.

[0033] Add the quaternizing reagent to a three-necked flask equipped with a stirrer, thermometer, and condenser. Stir and heat to 90°C for 6 hours, then cool to obtain a mixed Schiff base quaternized derivative.

[0034] The quaternizing agent is dimethyl sulfate or benzyl chloride.

[0035] The corrosion inhibitor is prepared by adding epoxy succinate serine copolymer, acrylic acid, polyol phosphate, ethylene glycol, surfactant, and solvent to a pre-synthesized mixed Schiff base quaternized derivative, and mixing and stirring until homogeneous.

[0036] The preparation method of the above corrosion inhibitor is as follows:

[0037] The first step is to synthesize a mixed Schiff base intermediate.

[0038] Tung oil, cinnamaldehyde, and hydroxyethyl ethylenediamine were added to a three-necked flask in a molar ratio of 0.5:0.5:1.2. Then, a certain amount of benzene was added and mixed evenly. The mixture was heated to a reflux temperature of 80°C and kept reacting for 8-10 hours. Then, the benzene and the water produced in the reaction were removed by vacuum distillation at 60°C. After cooling, a mixed Schiff base intermediate was obtained.

[0039] The second step is to synthesize mixed Schiff base quaternary ammonium salt derivatives.

[0040] A container equipped with a stirrer, thermometer, and condenser is used to add the synthesized Schiff base intermediate and quaternizing reagent. After stirring and heating to 90°C for 5-6 hours, the mixture is cooled to room temperature to obtain the Schiff base quaternized derivative.

[0041] The third step involves adding epoxy succinate serine copolymer, acrylic acid, polyol phosphate, ethylene glycol, tartaric acid, and solvent to the synthesized Schiff base quaternary ammonium salt derivative according to the weight ratio of the main corrosion inhibitor and the compound as described above. After stirring in an appropriate amount, the surfactant Span 80 or Tween 20 is added, and the mixture is stirred evenly to obtain the corrosion inhibitor product of the present invention. The solvent is isopropanol or ethanol.

[0042] Example 1:

[0043] First, add tung oil (0.5 mol) and cinnamaldehyde (0.5 mol) to a three-necked flask, then add a certain amount of benzene and mix well. Slowly add hydroxyethyl ethylenediamine (1.2 mol) and stir. Heat to reflux temperature of 80°C and maintain the reaction for 8-10 hours. Then, remove benzene and water produced by the reaction by vacuum distillation at 60°C. After cooling, the mixed Schiff base intermediate is obtained.

[0044] The second step involves adding the synthesized mixed Schiff base intermediate to a three-necked flask equipped with a stirrer, thermometer, and condenser, then adding 1 mol of dimethyl sulfate as a quaternizing agent. After stirring and heating to 90°C for 5-6 hours, the mixture is cooled to room temperature to obtain the mixed Schiff base quaternized derivative.

[0045] The third step involves adding epoxy succinate serine copolymer, acrylic acid, polyol phosphate, ethylene glycol, and solvent to the synthesized mixed Schiff base quaternary ammonium salt derivative according to the weight ratio of the corrosion inhibitor main agent and the compound as described above. After stirring in an appropriate amount, a surfactant is added and the mixture is stirred evenly to obtain the corrosion inhibitor product of the present invention.

[0046] To test the performance of the corrosion inhibitor, a configuration simulating the composition of on-site wastewater was prepared, and its performance was evaluated under different temperatures, water quality conditions, and varying amounts of inhibitor added. A specific implementation example is given below:

[0047] Example 2: Take 40g of the mixed Schiff base quaternary ammonium salt synthesized in Example 1, add 4g of acrylic acid and stir, then add 6g of polyol phosphate, 8g of epoxy succinate serine copolymer, 5g of ethylene glycol and stir, then add 6g of Span 80, 2g of tartaric acid, 20g of ethanol and 9g of isopropanol and stir evenly to obtain the corrosion inhibitor, code HM-W01.

[0048] Example 3: Take 38g of the mixed Schiff base quaternary ammonium salt synthesized in Example 1, add 5g of acrylic acid and stir, then add 7g of polyol phosphate, 9g of epoxy succinate serine copolymer, add 6g of ethylene glycol and stir, then add 5g of Span 80, 3g of tartaric acid, and 27g of isopropanol. Stir until uniform to obtain the corrosion inhibitor, code HM-W02.

[0049] Example 4: Take 37g of the mixed Schiff base quaternary ammonium salt synthesized in Example 1, add 6g of acrylic acid and stir, then add 8g of polyol phosphate, 9g of epoxy succinate serine copolymer, add 6g of ethylene glycol and stir, then add 5g of Span 80, 4g of tartaric acid, and 26g of ethanol. Stir until uniform to obtain the corrosion inhibitor, code HM-W03.

[0050] Example 5: Take 36g of the mixed Schiff base quaternary ammonium salt synthesized in Example 1, add 5g of acrylic acid and stir, then add 6g of polyol phosphate, 10g of epoxy succinate serine copolymer, add 5g of ethylene glycol and stir, then add 4g of Span 80, 2g of tartaric acid, and 32g of isopropanol. Stir until uniform to obtain the corrosion inhibitor, code HM-W04.

[0051] Example 6: Take 35g of the mixed Schiff base quaternary ammonium salt synthesized in Example 1, add 6g of acrylic acid and stir, then add 8g of polyol phosphate, 10g of epoxy succinate serine copolymer, add 7g of ethylene glycol and stir, then add 6g of Span 80, 4g of tartaric acid, and 24g of ethanol. Stir until uniform to obtain the corrosion inhibitor, code HM-W05.

[0052] Example 7:

[0053] To verify the protective effect of different corrosion inhibitors of this invention on sewage pipelines, the experiment used a simulated on-site aqueous solution. The simulated solution composition was: 5.6% NaCl, 0.5% CaCl2, 0.9% MgCl2, 1.6% Na2SO4, and 0.07% NaHCO3 to simulate the on-site water conditions. The test material was an L360 pipeline steel specimen, the test temperature was 60℃, the test time was 168h, and the corrosion inhibitor dosage was 100ppm.

[0054] 0 0.213 HM-W01 0.031 HM-W02 0.035 HM-W03 0.040 HM-W04 0.037 HM-W05 0.043

[0055] Example 8:

[0056] To verify the protective effect of the corrosion inhibitor concentration of this invention on sewage pipelines, corrosion inhibitor HM-W01 was selected for the experiment. A simulated on-site aqueous solution was used, with the following composition (mass ratio): 5.6% NaCl, 0.5% CaCl2, 0.9% MgCl2, 1.6% Na2SO4, and 0.07% NaHCO3. The solution was not deoxygenated to simulate the on-site water condition. The test material was L360 pipeline steel specimens, the test temperature was 60℃, and the test time was 168 hours. The corrosion inhibitor performance was tested as follows:

[0057] 0 0.213 20 0.112 30 0.083 50 0.064 80 0.046 100 0.031

[0058] Example 9:

[0059] To examine the effect of ambient temperature on the corrosion inhibition effect of the corrosion inhibitor of this invention, corrosion inhibitor HM-W01 was selected and added at a concentration of 100 ppm. The experiment used a simulated on-site aqueous solution with the following composition (mass ratio): 5.6% NaCl, 0.5% CaCl2, 0.9% MgCl2, 1.6% Na2SO4, and 0.07% NaHCO3. The solution was not deoxygenated to simulate the on-site water condition. The test material was an L360 pipeline steel specimen, and the test duration was 168 hours. The corrosion inhibitor performance under different temperature conditions is as follows:

[0060]

[0061] Example 10:

[0062] This invention provides a mixed Schiff base quaternary ammonium salt type corrosion inhibitor for corrosion protection of sewage pipelines. The corrosion inhibitor is provided by mass ratio as follows: 35-40% mixed Schiff base quaternized derivatives, 8-10% epoxy succinic acid serine copolymer, 4-6% acrylic acid, 6-8% polyol phosphate ester, 2-4% tartaric acid, 5-7% ethylene glycol, 4-6% surfactant, and 21-36% solvent isopropanol or ethanol; the surfactant is Span 80 or Tween 20.

[0063] The corrosion inhibitor is obtained by quaternization reaction of tung oil, cinnamaldehyde, organic amine, and quaternization reagent.

[0064] Furthermore, the main agent is prepared by the following method: tung oil, cinnamaldehyde, and organic amine are added to a three-necked flask in a molar ratio of 0.5:0.5:1.2, then a certain amount of benzene is added and mixed evenly. The mixture is heated to a reflux temperature of 80°C and maintained for 8-10 hours. Then, the azeotrope of benzene and ethanol and the water produced in the reaction are removed by vacuum distillation at 60°C. After cooling, the Schiff base intermediate is obtained.

[0065] Add the quaternizing reagent to a three-necked flask equipped with a stirrer, thermometer, and condenser. Stir and heat to 90°C for 6 hours, then cool to obtain a mixed Schiff base quaternized derivative.

[0066] Furthermore, the organic amine is hydroxyethyl ethylenediamine.

[0067] Furthermore, the surfactant is Span 80 or Tween 20.

[0068] Furthermore, the solvent is isopropanol or ethanol.

[0069] The second aspect of this invention provides a method for preparing a mixed Schiff base quaternary ammonium salt type corrosion inhibitor for corrosion protection of sewage pipelines, comprising the following steps:

[0070] Step 1, Synthesis of corrosion inhibitor main agent: Tung oil, cinnamaldehyde, and organic amine are added to a three-necked flask in a molar ratio of 0.5:0.5:1.2. Then, a certain amount of benzene is added and mixed evenly. The mixture is heated to the reflux temperature of 80°C and kept reacting for 8-10 hours. Then, the azeotrope of benzene and ethanol and the water produced in the reaction are removed by vacuum distillation at 60°C. After cooling, the Schiff base intermediate is obtained.

[0071] Add the quaternizing reagent to a three-necked flask equipped with a stirrer, thermometer and condenser, stir and heat to 90°C for 6 hours, then cool to obtain the mixed Schiff base quaternized derivative.

[0072] Step 2: Add solvent and stir, then add surfactant;

[0073] Step 3: After adding epoxy succinate serine copolymer and stirring, add acrylic acid;

[0074] Step 4: Add polyol phosphate ester and stir, then add tartaric acid;

[0075] Step 5: Add ethylene glycol and stir, then add triethanolamine and stir again.

[0076] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or basic characteristics. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0077] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can be appropriately combined to form other embodiments that can be understood by those skilled in the art. The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A mixed Schiff base quaternary ammonium salt type corrosion inhibitor for sewer pipelines, characterized by, The mixed Schiff base quaternary ammonium salt corrosion inhibitor is formulated according to the following mass ratio: 35-40% mixed Schiff base quaternized derivatives, 8-10% epoxy succinic acid serine copolymer, 4-6% acrylic acid, 6-8% polyol phosphate ester, 2-4% tartaric acid, 5-7% ethylene glycol, 4-6% surfactant, and 21-36% solvent. The preparation of mixed Schiff base quaternized derivatives includes the following steps: S1.1: Synthetic intermediates of mixed Schiff bases; S1.1.1: Tung oil, cinnamaldehyde, and hydroxyethyl ethylenediamine are added to a container in a molar ratio of 0.5:0.5:1.2, and then benzene is added and mixed evenly to obtain mixture B; S1.1.2: Heat mixture B and maintain the reaction for 8-10 hours, then cool it down by 20°C; S1.1.3: After cooling, distill under reduced pressure to obtain a mixed Schiff base intermediate; S1.2: The mixed Schiff base intermediate is processed to synthesize the mixed Schiff base quaternary ammonium salt derivative; S1.2.1: Add a quaternizing agent to the mixed Schiff base intermediate to obtain mixture C; S1.2.2: Stir mixture C and heat it to react for a period of time; S1.2.3: After reacting for a period of time, the temperature is lowered to room temperature to obtain a mixed Schiff base quaternary ammonium salt derivative; The quaternizing agent is dimethyl sulfate or benzyl chloride.

2. A mixed Schiff base quaternary ammonium salt type corrosion inhibitor for sewer pipelines according to claim 1, characterized in that, The solvent is isopropanol, ethanol, or a mixture of isopropanol and ethanol.

3. A mixed Schiff base quaternary ammonium salt type corrosion inhibitor for sewer pipelines according to claim 1, characterized in that, The surfactant is Span 80 or Tween 20.

4. A process for the preparation of mixed Schiff base quaternary ammonium salt type corrosion inhibitor for sewer pipeline corrosion protection according to any one of claims 1 to 3, characterized in that, The preparation method includes the following steps: S1: Preparation of mixed Schiff base quaternized derivatives; S2: Add epoxy succinate serine copolymer, acrylic acid, polyol phosphate, ethylene glycol, tartaric acid and solvent to a mixed Schiff base quaternized derivative and stir until homogeneous to obtain mixture A; S3: Add a surfactant to mixture A and mix thoroughly to obtain a Schiff base quaternary ammonium salt type corrosion inhibitor.

5. A process for the preparation of a mixed Schiff base quaternary ammonium salt type corrosion inhibitor for the protection of sewer pipelines according to claim 4, characterized in that, When a surfactant is added to mixture A, a solvent is added.

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