Corrosion inhibitor, preparation method and application thereof

Abstract

The invention provides a corrosion inhibitor as well as a preparation method and application thereof, and the preparation method comprises the following steps: pretreating an inactivated denitration catalyst to obtain a pretreated denitration catalyst; adding the regenerated liquid into the pretreated denitration catalyst, and reacting to obtain regenerated waste liquid; adding an inorganic salt solution into the regenerated waste liquid, and stirring and mixing to obtain a mixed solution A; filtering, washing and drying the mixed solution A to obtain the inorganic salt corrosion inhibitor; adding the auxiliary agent and the surfactant into the inorganic salt corrosion inhibitor according to the formula ratio, and carrying out magnetic stirring and ultrasonic dispersion to obtain a mixed solution B; and filtering and drying the obtained mixed solution B to obtain the product. The mass ratio of the auxiliary agent to the surfactant to the inorganic salt corrosion inhibitor is (5-10): (1-5): 100. The efficient and environment-friendly corrosion inhibitor for the CO2 absorbent is prepared by utilizing the regenerated waste liquid generated by regeneration of the denitration catalyst, and effective utilization of resources is realized. The corrosion inhibitor can effectively improve the stability of the CO2 absorbent.

Description

Technical Field

[0001] The present invention relates to the technical field of carbon sequestration and storage, and in particular to a CO2 corrosion inhibitor, a preparation method and an application thereof. Background Art

[0002] With the continued advancement of environmental protection policies, vanadium-based denitrification catalysts are widely used in industries such as thermal power and steel due to their excellent denitrification efficiency. However, the waste liquid containing heavy metals such as vanadium and titanium, generated during the regeneration process after catalyst deactivation, faces high hazardous waste disposal costs if treated using traditional methods such as neutralization, precipitation, and emission standards. This also leads to resource waste and potential environmental risks. According to statistics, a single 100-kilowatt unit can generate over 100 tons of this waste liquid annually, making its resource utilization a pressing need for the industry's green transformation.

[0003] Meanwhile, carbon dioxide corrosion in the industrial sector has long plagued critical facilities such as oil and gas pipelines and chemical equipment. The carbonic acid environment created by carbon dioxide dissolving in water accelerates electrochemical corrosion of metals, shortening equipment lifespan and even posing safety risks. Current mainstream solutions rely on the addition of corrosion inhibitors such as organic amines and molybdates, but these traditional corrosion inhibitors face bottlenecks such as high raw material costs and limited environmental compatibility.

[0004] Notably, research has shown that the active vanadium element in vanadium-based wastewater can form a dense passivation film on metal surfaces, effectively inhibiting corrosion reactions. This property offers a breakthrough for the high-value utilization of wastewater: by selectively extracting vanadium from wastewater and compounding it with functional additives, it is possible to recycle hazardous waste resources and develop low-cost, high-performance carbon dioxide corrosion inhibitors, forming a "waste-to-treat-hazard" recycling technology path. This research has dual practical significance for promoting the coordinated development of industrial pollution control and carbon emission reduction. Summary of the Invention

[0005] In view of the defects and shortcomings of the existing technology, the purpose of the present invention is to provide a corrosion inhibitor, a preparation method and its application, by extracting and converting the active components of the deactivated denitrification catalyst regeneration waste liquid to obtain a high-efficiency corrosion inhibitor that can be used to prepare CO2 absorbent, so as to achieve resource recycling and reduce environmental pollution.

[0006] The present invention is achieved by adopting the following technical solutions:

[0007] A method for preparing a corrosion inhibitor, characterized in that it comprises the following steps:

[0008] Step 1: performing soot blowing, cleaning and drying on the deactivated denitration catalyst in sequence to obtain a pretreated denitration catalyst;

[0009] Step 2: adding regeneration liquid to the pretreated denitration catalyst, reacting at a temperature of 50 to 80° C. and a stirring speed of 100 to 300 r / min for 2 to 6 hours, and filtering to obtain regeneration waste liquid;

[0010] The mass volume ratio of the pretreated denitration catalyst to the regeneration liquid is 1 (g): 5-20 (mL);

[0011] Step 3, adding an inorganic salt solution with a concentration of 0.01 to 0.3 mol / L to the regeneration waste liquid, stirring and mixing at a temperature of 80 to 120° C., a pressure of 0.1 to 0.5 MPa, and a speed of 200 to 400 r / min to obtain a mixed solution A; filtering, washing and drying the mixed solution A to obtain an inorganic salt corrosion inhibitor;

[0012] The volume ratio of the regeneration waste liquid to the inorganic salt solution is 1:(0.5-2);

[0013] Step 4: Add the formulated amount of the additive and the surfactant to the inorganic salt corrosion inhibitor, and obtain a mixed solution B by magnetic stirring and ultrasonic dispersion; and filter and dry the obtained mixed solution B.

[0014] The mass ratio of the auxiliary agent, the surfactant and the inorganic salt corrosion inhibitor is (5-10): (1-5):100.

[0015] The present invention also has the following technical features:

[0016] Specifically, in step 1, compressed air is used for soot blowing, the soot blowing pressure is 0.5-1.0 MPa, the gas flow rate is 15 m / s-25 m / s, and the time is 10 min-30 min; deionized water is used for cleaning, and the cleaning time is 5-10 min; the drying temperature is 80-100° C., and the time is 6-12 hours.

[0017] Furthermore, the regeneration liquid is compounded by an acid and a complexing agent, the acid is selected from one or more of sulfuric acid, hydrochloric acid and nitric acid; the complexing agent is selected from one or more of ethylenediaminetetraacetic acid, nitrilotriacetic acid, diethylenetriaminepentaacetic acid, hydroxyethyldiphosphonic acid, diethylenetriaminepentamethylenephosphonic acid, citric acid, gluconic acid, thiourea and dopamine, the molar ratio of the acid to the complexing agent is 1:(0.3-0.8); the concentration of the acid is 0.1-1.0 mol / L, and the concentration of the complexing agent is 0.01-0.1 mol / L.

[0018] Furthermore, the inorganic salt in the inorganic salt solution is selected from one or more of potassium nitrate, potassium sulfate, potassium hydrogen sulfate, potassium phosphate, dipotassium hydrogen phosphate, potassium dihydrogen phosphate, sodium nitrate, sodium sulfate, sodium hydrogen sulfate, sodium phosphate, disodium hydrogen phosphate, and sodium dihydrogen phosphate.

[0019] Furthermore, the inorganic salt in the inorganic salt solution is prepared by compounding potassium nitrate, sodium phosphate and sodium sulfate in a molar ratio of 1:1:1.

[0020] Furthermore, in step 3, deionized water is used for washing, the washing time is 5 to 10 minutes, the drying temperature is 60 to 80° C., and the drying time is 8 to 12 hours.

[0021] Furthermore, in step 4, the auxiliary agent is selected from one or both of nano-silicon dioxide with a particle size of 10 to 100 nm and polyethylene glycol with a molecular weight of 200 to 600; and the surfactant is sodium lauryl sulfate.

[0022] Furthermore, in step 4, the stirring speed of the magnetic stirring is 300-500 r / min, and the stirring time is 1-2 hours; the ultrasonic power of the ultrasonic dispersion is 200-400 W, and the dispersion time is 0.5-1 hour.

[0023] Furthermore, in step 2 and step 3, the pore size of the filter membrane used for filtration is 0.01 to 0.1 μm.

[0024] The present invention also provides a corrosion inhibitor, which is prepared by the above preparation method.

[0025] The present invention also protects the use of the corrosion inhibitor prepared by the above preparation method for preparing a CO2 absorbent, wherein the content of the corrosion inhibitor in the CO2 absorbent is 0.1 to 1.0% by mass.

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

[0027] (1) The method of the present invention realizes the regeneration of the deactivated denitrification catalyst by adopting processes such as soot blowing, cleaning, drying, and regeneration; inorganic salts, additives, and surfactants are added to the generated regeneration waste liquid to prepare a high-efficiency, environmentally friendly corrosion inhibitor for CO2 absorbent, thereby realizing the effective utilization of the regeneration waste liquid and reducing the processing cost of the enterprise.

[0028] (2) The corrosion inhibitor provided by the present invention can be used to prepare a CO2 absorbent, and the corrosion inhibitor of the present invention can effectively improve the stability of the CO2 absorbent, prevent the corrosive substances in the CO2 absorbent from directly contacting the metal, and slow down or inhibit the corrosion process of the metal. DETAILED DESCRIPTION

[0029] It should be emphasized that, unless otherwise specified, the raw materials used in the present invention are all commercially available.

[0030] The technical concept of the present invention is to use a multi-stage synergistic strategy of extracting metal ions through an acid-complexing agent, directional precipitation of inorganic salts to form a film, optimizing the membrane structure with an additive, and enhancing dispersion and adsorption with a surfactant. The regeneration waste liquid of the denitrified catalyst is used to prepare a corrosion inhibitor that can be used to prepare an absorbent. The prepared corrosion inhibitor is particularly suitable for corrosion protection of metal equipment in high-temperature and high-pressure environments. Specifically, it includes:

[0031] The role of acid in the regeneration liquid: Select strong acids such as sulfuric acid, nitric acid, and hydrochloric acid to dissolve the active metal oxides (such as V2O5, WO3, MoO3, TiO2) in the deactivated denitrification catalyst and release high-valent metal ions (V 5+ 、W 6+ 、Mo 6+ 、Ti 4+ ). These ions are the core components of the subsequent generation of corrosion inhibitors.

[0032] The role of complexing agent: Over-coordination with metal ions to form a stable soluble complex to prevent premature precipitation or oxidation. 5+ Formation of [V(EDTA)] - Complex, maintaining the activity of metal ions in solution.

[0033] Synergistic mechanism: The dual effects of acid dissolution and complex stabilization ensure efficient extraction of metal ions and maintain reaction activity, providing the raw material basis for the subsequent generation of corrosion inhibitors.

[0034] The role of inorganic salts: directional precipitation and film formation enhancement, among which phosphates (such as sodium phosphate): react with V in the regeneration solution 5+ 、W 6+ The reaction generates insoluble phosphates (such as VPO4, WPO4), forming a dense passivation film on the metal surface, physically isolating the contact between CO2 and the metal. The phosphate film has high chemical stability and can inhibit electrochemical corrosion reactions; sulfate / nitrate (such as sodium sulfate, potassium nitrate): provides SO4 2- 、NO3 - Ions regulate the solution's ionic strength and promote uniform phosphate nucleation. Sulfates may participate in the formation of complex salts (such as vanadium sulfate), enhancing the film's mechanical strength; the oxidizing properties of nitrates can assist in metal surface passivation. Mixed salts optimize the passive film's structure by balancing the film-forming ability of phosphates with the dispersing and film-forming assistance of sulfates and nitrates, avoiding film loosening or cracking caused by a single component.

[0035] The role of additives: nano-enhancement and flexible regulation. Nano-silica acts as a physical barrier: its high surface area adsorbs inorganic salt particles, increasing the coverage density of the passivation film on the metal surface; dispersion stabilization: preventing inorganic salt particle agglomeration, improving the uniformity and stability of the corrosion inhibitor system. Polyethylene glycol (PEG): Flexible filling: its molecular chains fill the micropores of the passivation film, reducing the CO2 permeation path; interface enhancement: PEG's hydrophilic groups bind to the hydroxyl groups on the metal surface, improving film adhesion; and hydrophobic chains form localized hydrophobic zones, inhibiting water molecule penetration.

[0036] Synergistic effect: The combination of rigid nanoparticles and flexible polymers constructs a "rigid and flexible" composite membrane layer that takes into account both mechanical strength and anti-permeability.

[0037] The role of surfactant (SDS):

[0038] Wetting, dispersion and dynamic repair: The anionic properties of sodium dodecyl sulfate (SDS) reduce the surface tension of the solution, promote the corrosion inhibitor to uniformly wetting the metal surface, and prevent the sedimentation of inorganic salt particles through electrostatic repulsion.

[0039] Dynamic protection: SDS is adsorbed on the metal surface to form a monolayer. Its long hydrophobic chain (C12) hinders the H generated by the dissolution of CO2. + Contact with metal; when the film layer is locally damaged, SDS can quickly migrate to the defect and achieve dynamic repair.

[0040] Synergistic effect: The dispersing effect of SDS complements the film-forming ability of inorganic salts, ensuring that the corrosion inhibitor can still stably exert its protective effect under complex working conditions (such as high temperature, high pressure, and high flow rate).

[0041] In the present invention, the method used for performance testing includes:

[0042] The film thickness uniformity test is carried out by non-contact measurement using a confocal laser scanning microscope (CLSM) or a profilometer: the corrosion inhibitor is applied to the surface of an N80 steel specimen, and after curing, 10 points are randomly selected to measure the film thickness, and the standard deviation (±μm) is calculated as the uniformity index.

[0043] Test standard: ISO 4287 surface roughness measurement specification.

[0044] The porosity was determined by mercury intrusion porosimetry combined with field emission scanning electron microscopy (FE-SEM) analysis.

[0045] Mercury intrusion porosimetry (ASTM D4404): Mercury is pressed into the pores of the membrane under high pressure, and the porosity (%) is calculated based on the pressure-volume curve.

[0046] FE-SEM (ISO 21363): Observe the membrane surface and cross-sectional morphology to assist in verifying the uniformity of pore distribution.

[0047] The adsorption capacity test used a quartz crystal microbalance (QCM) to monitor the adsorption process in real time.

[0048] The surface of an N80 steel specimen was modified into a QCM sensor and immersed in a CO2 saturated solution containing a corrosion inhibitor. The frequency change Δf was recorded and the adsorption capacity (mg / cm 2 ).

[0049] Adsorption rate measurements were based on dynamic gravimetric analysis combined with QCM data.

[0050] TGA (ISO 11358): monitor the mass change of the test piece in a CO2 environment in real time and calculate the adsorption amount per unit time and per unit area (mg / (cm 2 ·min)).

[0051] Data fitting: The adsorption rate constants were fitted using the existing Langmuir adsorption kinetic model.

[0052] Test method design basis:

[0053] Film thickness uniformity: The high resolution (nanometer level) of the laser confocal microscope and the fast scanning characteristics of the step profiler are suitable for industrial coating quality control.

[0054] Porosity: Mercury intrusion can cover the mesopore-macropore range (3nm to 400μm), matching the actual pore distribution of the corrosion inhibitor film; FE-SEM provides intuitive morphology verification.

[0055] Adsorption amount and rate: The real-time monitoring capability of QCM complements the mass change data of TGA to ensure the accuracy of adsorption kinetic parameters.

[0056] Specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent modifications made on the basis of the technical solution of this application fall within the protection scope of the present invention.

[0057] Example 1

[0058] In accordance with the above technical solution, this embodiment provides a method for preparing a corrosion inhibitor, comprising the following steps:

[0059] Step 1: Soot blowing treatment is performed on the deactivated vanadium-based catalyst of the denitrification process after use. Compressed air is used for soot blowing. The soot blowing pressure is 0.6 MPa and the gas flow rate is 18 m / s. The soot blowing time is 20 minutes to remove impurities and pollutants on the surface; the catalyst is washed with deionized water 5 times, each washing time is 10 minutes; and the catalyst is dried at 90° C. for 10 hours to obtain the pretreated denitrification catalyst.

[0060] Step 2: adding regeneration liquid to the pretreated denitration catalyst, wherein the mass volume ratio of the denitration catalyst to the regeneration liquid is 1:5 (g / mL), and the regeneration liquid is prepared by mixing sulfuric acid and ethylenediaminetetraacetic acid (EDTA) as a complexing agent, wherein the sulfuric acid concentration is 0.5 mol / L and the ethylenediaminetetraacetic acid (EDTA) concentration is 0.05 mol / L; reacting for 2 hours at a temperature of 80° C. and a stirring speed of 300 r / min; filtering out solid impurities and suspended matter with a filter membrane with a pore size of 0.5 μm to obtain a regeneration waste liquid.

[0061] Step 3. Add a potassium nitrate solution with a concentration of 0.1 mol / L to the regeneration waste liquid, wherein the volume ratio of the regeneration waste liquid to the potassium nitrate solution is 2:1, and stir the reaction at a temperature of 100°C and a pressure of 0.3 MPa at a stirring speed of 400 r / min for 2 hours. After the reaction is completed, filter using a filter membrane with a pore size of 0.1 μm, wash with deionized water 3 times, each washing time is 5 minutes, and then dry at 70°C for 10 hours to obtain an inorganic salt corrosion inhibitor.

[0062] Step 4: Add sodium lauryl sulfate and nano-silica with a particle size of 10 nm to the inorganic salt corrosion inhibitor, wherein the mass ratio of nano-silica, sodium lauryl sulfate and inorganic salt corrosion inhibitor is 5:1:100; perform magnetic stirring: the stirring speed is 500r / min, and the stirring time is 1 hour; combine ultrasonic dispersion, the ultrasonic power is 400W, and the dispersion time is 0.5 hours, to evenly disperse the additives in the corrosion inhibitor to enhance the adsorption capacity and film-forming quality of the corrosion inhibitor. Afterwards, use a ceramic membrane with a pore size of 0.1μm to filter out unreacted raw materials and impurities, and then vacuum dry at 80°C for 12 hours to obtain the product, wherein the purpose of vacuum drying is to prevent the components in the air from affecting the product under heating.

[0063] The corrosion inhibition effect of the corrosion inhibitor prepared in this example was measured:

[0064] Prepare multiple sets of N80 steel test pieces of the same material, shape, and size and place them in the same CO2 delivery environment. Then, add different types of corrosion inhibitors to the environment. After a certain period of corrosion, the metal test pieces are removed, cleaned, dried, and weighed. The corrosion rate is calculated based on the weight change of the metal test pieces before and after corrosion using the formula: Where υ is the corrosion rate, m0 is the mass of the metal specimen before corrosion, m1 is the mass of the metal specimen after corrosion, S is the surface area of the metal specimen, and t is the corrosion time. The corrosion inhibition efficiency calculation formula is: Where η is the corrosion rate, v0 is the corrosion rate of the blank control group without corrosion inhibitor, and v1 is the corrosion rate of the group with corrosion inhibitor. The results are shown in Table 1.

[0065] Example 2

[0066] This embodiment discloses a method for preparing a corrosion inhibitor. The steps of the method are the same as those of Example 1, except that the ratios and additives are different, including: in step 2, the mass volume ratio of the pretreated catalyst to the regeneration liquid is 1:10 (g / mL); in step 3, the volume ratio of the regeneration waste liquid to the inorganic salt solution is 1.0:1.0; in step 4, the additive is polyethylene glycol, and the mass ratio of polyethylene glycol, sodium lauryl sulfate, and inorganic salt corrosion inhibitor is 8:3:100;

[0067] The corrosion inhibition effect of the prepared corrosion inhibitor was measured using the method used in Example 1. The results are shown in Table 1.

[0068] Example 3

[0069] This embodiment discloses a method for preparing a corrosion inhibitor. The steps of the method are the same as those of Example 1, except that the ratios and additives are different, including: in step 2, the mass volume ratio of the pretreated catalyst to the regeneration liquid is 1:20 (g / mL); in step 3, the volume ratio of the regeneration waste liquid to the inorganic salt solution is 1:2; in step 4, the additive is polyethylene glycol, and the mass ratio of polyethylene glycol, sodium lauryl sulfate, and inorganic salt corrosion inhibitor is 2:1:20;

[0070] The corrosion inhibition effect of the prepared corrosion inhibitor was measured using the method used in Example 1. The results are shown in Table 1.

[0071] Comparative Example 1

[0072] In this comparative example, sodium phosphate, a common inorganic corrosion inhibitor, was used and tested using the method used in Example 1. The comparative results are shown in Table 1.

[0073] Comparative Example 2

[0074] In this comparative example, the existing organic corrosion inhibitor benzotriazole was used and tested using the method used in Example 1. The comparative results are shown in Table 1.

[0075] Comparative Example 3

[0076] In this comparative example, the existing polymer corrosion inhibitor polyethylene was used and tested using the method used in Example 1. The comparative results are shown in Table 1.

[0077] Comparative Example 4

[0078] In this comparative example, no corrosion inhibitor was added in the CO2 delivery environment, and the test was carried out using the method used in Example 1. The comparative results are shown in Table 1.

[0079]

[0080] Table 1. Comparison of corrosion inhibition effects of Examples 1 to 3 and Comparative Examples 1 to 4

[0081] As can be seen from Table 1, the corrosion inhibitors prepared using the method of the present invention significantly outperformed conventional inorganic, organic, and polymeric corrosion inhibitors in various key performance indicators. In particular, the corrosion inhibition efficiencies of the corrosion inhibitors prepared in Examples 1-3 were all no less than 85%, significantly higher than the 70% to 78% of the corrosion inhibitors prepared in Comparative Examples 1-4, demonstrating that the corrosion inhibitors provided by the present invention are more effective in mitigating metal corrosion than the existing corrosion inhibitors in the comparative examples.

[0082] Furthermore, Table 1 shows that the corrosion inhibitors prepared using the present invention exhibit superior film thickness uniformity, film density, and film adhesion when formed on the metal surface. This demonstrates that the corrosion inhibitors prepared using the present invention are more capable of forming a stable and highly protective film on the metal surface. The adsorption amounts and adsorption rates of the corrosion inhibitors prepared in Examples 1-3 were higher than those in Comparative Examples 1-4, demonstrating that the corrosion inhibitors exhibit better adsorption on the metal surface, allowing for faster and larger adsorption, resulting in a rapid corrosion inhibition effect.

[0083] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the scope of protection of the present invention.

[0084] In addition, the various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A method for preparing a corrosion inhibitor, characterized in that: The following steps are involved: Step 1: performing soot blowing, cleaning and drying on the deactivated denitration catalyst in sequence to obtain a pretreated denitration catalyst; Step 2: adding regeneration liquid to the pretreated denitration catalyst, reacting at a temperature of 50 to 80° C. and a stirring speed of 100 to 300 r / min for 2 to 6 hours, and filtering to obtain regeneration waste liquid; The mass volume ratio of the pretreated denitration catalyst to the regeneration liquid is 1 (g): 5-20 (mL); Step 3, adding an inorganic salt solution with a concentration of 0.01 to 0.3 mol / L to the regeneration waste liquid, stirring and mixing at a temperature of 80 to 120° C., a pressure of 0.1 to 0.5 MPa, and a speed of 200 to 400 r / min to obtain a mixed solution A; filtering, washing and drying the mixed solution A to obtain an inorganic salt corrosion inhibitor; The volume ratio of the regeneration waste liquid to the inorganic salt solution is 1:(0.5-2); Step 4: Add the formulated amount of the additive and the surfactant to the inorganic salt corrosion inhibitor, and obtain a mixed solution B by magnetic stirring and ultrasonic dispersion; and filter and dry the obtained mixed solution B. The mass ratio of the auxiliary agent, the surfactant and the inorganic salt corrosion inhibitor is (5-10): (1-5):

100.

2. The method for preparing the corrosion inhibitor according to claim 1, wherein In step 1, compressed air is used for soot blowing, the soot blowing pressure is 0.5-1.0 MPa, the gas flow rate is 15 m / s-25 m / s, and the time is 10 min-30 min; deionized water is used for cleaning, and the cleaning time is 5-10 min; the drying temperature is 80-100° C., and the time is 6-12 hours.

3. The method for preparing the corrosion inhibitor according to claim 1, wherein The regeneration liquid is prepared by compounding an acid and a complexing agent, wherein the acid is selected from one or more of sulfuric acid, hydrochloric acid and nitric acid; the complexing agent is selected from one or more of ethylenediaminetetraacetic acid, nitrilotriacetic acid, diethylenetriaminepentaacetic acid, hydroxyethyldiphosphonic acid, diethylenetriaminepentamethylenephosphonic acid, citric acid, gluconic acid, thiourea and dopamine, and the molar ratio of the acid to the complexing agent is 1:(0.3-0.8); the concentration of the acid is 0.1-1.0 mol / L, and the concentration of the complexing agent is 0.01-0.1 mol / L.

4. The method for preparing the corrosion inhibitor according to claim 1, wherein The inorganic salt in the inorganic salt solution is selected from one or more of potassium nitrate, potassium sulfate, potassium hydrogen sulfate, potassium phosphate, dipotassium hydrogen phosphate, potassium dihydrogen phosphate, sodium nitrate, sodium sulfate, sodium hydrogen sulfate, sodium phosphate, disodium hydrogen phosphate and sodium dihydrogen phosphate.

5. The method for preparing the corrosion inhibitor according to claim 1, wherein In step 3, deionized water is used for washing, the washing time is 5 to 10 minutes, the drying temperature is 60 to 80° C., and the drying time is 8 to 12 hours.

6. The method for preparing the corrosion inhibitor according to claim 1, wherein In step 4, the auxiliary agent is selected from one or both of nano-silicon dioxide with a particle size of 10 to 100 nm and polyethylene glycol with a molecular weight of 200 to 600; and the surfactant is sodium lauryl sulfate.

7. The method for preparing the corrosion inhibitor according to claim 1, wherein In step 4, the stirring speed of the magnetic stirring is 300-500 r / min, and the stirring time is 1-2 hours; the ultrasonic power of the ultrasonic dispersion is 200-400 W, and the dispersion time is 0.5-1 hour.

8. The method for preparing the corrosion inhibitor according to claim 1, wherein In step 2 and step 3, the pore size of the filter membrane used for filtration is 0.01 to 0.1 μm.

9. A corrosion inhibitor, characterized in that The method is as described in any one of claims 1 to 8.

10. Use of the corrosion inhibitor prepared by the preparation method according to any one of claims 1 to 8 for preparing a CO2 absorbent, characterized in that: In the CO2 absorbent, the content of the corrosion inhibitor is 0.1-1.0% by mass.

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