Preparation process of hydrotalcite as corrosion inhibitor

Abstract

The invention provides a preparation process of a hydrotalcite corrosion inhibitor, and relates to the technical field of metal corrosion protection. The preparation process of the hydrotalcite as the corrosion inhibitor comprises the following steps: raw material proportioning, coprecipitation reaction, hydrothermal crystallization, post-treatment and composite material preparation. According to the invention, the composite hydrotalcite containing organic phosphonate radicals and inorganic anions among layers is prepared by a coprecipitation-hydrothermal synthesis method. The corrosion inhibitor forms a compact protective film on the metal surface by utilizing the synergistic adsorption effect of composite anions, the corrosion inhibition efficiency can reach 95% or above, and the corrosion inhibitor has the characteristics of simple process, environmental protection and high efficiency, and is suitable for metal corrosion prevention in the fields of industrial circulating water, oilfield water injection and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metal corrosion protection, in particular to a preparation process of hydrotalcite as corrosion inhibitor. BACKGROUND

[0002] Metal corrosion is a major problem in the industrial field, and corrosion inhibitors are widely used as an efficient and economical anticorrosion method. Traditional organic corrosion inhibitors (such as imidazoline and thiourea) have high corrosion inhibition efficiency, but have environmental problems such as high toxicity and difficult degradation; inorganic corrosion inhibitors (such as chromate and nitrite) are limited by environmental regulations and have the defect of insufficient corrosion inhibition efficiency. Therefore, the development of environmentally friendly, efficient and degradable new corrosion inhibitors has become a research hotspot.

[0003] Hydrotalcite is a kind of inorganic nanomaterial with layered structure, and the interlayer anions of hydrotalcite have controllable properties, strong surface adsorption capacity and environmental friendliness, which makes it have potential application value in the field of corrosion inhibition. However, the existing preparation process of hydrotalcite-based corrosion inhibitor has the following shortcomings:

[0004] 1. The type of interlayer anion is single, and the corrosion inhibition mechanism is limited;

[0005] 2. The dispersion of nanoparticles is poor, which affects the adsorption efficiency on the metal surface;

[0006] 3. The preparation process is complex and the cost is high.

[0007] Therefore, it is urgent to develop a simple, excellent corrosion inhibition performance and environmentally friendly preparation method of hydrotalcite-based corrosion inhibitor. SUMMARY

[0008] (I) Technical problems to be solved

[0009] In view of the shortcomings of the prior art, the present application provides a preparation process of hydrotalcite as corrosion inhibitor, which adjusts the composition and structure of interlayer anions and optimizes the preparation conditions to obtain a corrosion inhibitor with high corrosion inhibition efficiency, strong adsorption capacity and environmental friendliness, solving the problems raised in the above background.

[0010] (II) Technical scheme

[0011] In order to achieve the above purpose, the present application is realized by the following technical scheme: a preparation process of hydrotalcite as corrosion inhibitor, comprising the following steps:

[0012] Step 1: Raw material ratio:

[0013] Mg 2+ , Al 3+The metal ions of the layer are layered metal ions, and the molar ratio of the two is 2-4:1. The interlayer anions are a complex system of organic phosphonate and inorganic anions, and the molar ratio of the total anions to the metal ions is 0.5-1.5:1.

[0014] Step two: co-precipitation reaction:

[0015] Dissolve the soluble salt of Mg 2+ , Al 3+ in deionized water to prepare a metal salt mixed solution, dissolve the organic phosphonic acid and inorganic anion salt in deionized water to prepare an anion mixed solution, and simultaneously drop the metal salt mixed solution and the anion mixed solution into the reaction container under constant temperature stirring at 25-60°C. During the dropping process, adjust the pH of the system to an alkaline environment with NaOH solution.

[0016] Step three: hydrothermal crystallization:

[0017] Transfer the reaction product of step two to a hydrothermal reaction kettle, recrystallize, and naturally cool to room temperature.

[0018] Step four: post-treatment:

[0019] Centrifugal wash the crystallization product, dry at 60-100°C for 12-24h, then grind and sieve to prepare the hydrotalcite particles.

[0020] Step five: composite material preparation:

[0021] (1) Nanoparticle dispersion: Mix the above hydrotalcite particles with the polymer matrix, add antioxidants and lubricants, and uniformly disperse by high-speed stirring.

[0022] (2) Forming processing: Granulation is carried out by using a double-screw extruder at 170-190°C to prepare the hydrotalcite-based corrosion inhibitor.

[0023] Preferably, in step one, the organic phosphonate is one or more of aminotri-methylene phosphonate, ethylenediamine tetra-methylene phosphonate, and hydroxyethylidene diphosphonate.

[0024] Preferably, in step one, the inorganic anion is one or more of NO3 - , Cl - , SO4 2- , and the molar ratio of the organic phosphonate to the inorganic anion is 1-5:1.

[0025] Preferably, in step two, the concentration of the metal salt mixed solution is 0.1-0.5mol / L, and the concentration of the anion mixed solution is 0.1-0.5mol / L.

[0026] Preferably, in step two, the pH of the system is adjusted to 8-11 and stirred continuously for 1-3 hours.

[0027] Preferably, in step three, the crystallization temperature is 100-180℃ and the crystallization time is 12-48h.

[0028] Preferably, in step four, the centrifugal washing involves alternating washing with deionized water and ethanol 3-5 times, and the grinding and sieving process uses a sieve mesh of 80-200 mesh.

[0029] Preferably, in step five, the polymer matrix is ​​one or more of epoxy resin and polyethylene.

[0030] The present invention further discloses a hydrotalcite-based corrosion inhibitor prepared according to a hydrotalcite-based corrosion inhibitor preparation process as described above. The hydrotalcite-based corrosion inhibitor is used for surface protection of metals in neutral or weakly acidic corrosive environments, wherein the metals include steel, aluminum and their alloys.

[0031] (III) Beneficial Effects

[0032] This invention provides a process for preparing hydrotalcite as a corrosion inhibitor, which has the following beneficial effects:

[0033] 1. High corrosion inhibition efficiency: The interlayer composite anions (organic phosphonate + inorganic anions) work synergistically. The organic phosphonate forms a chemical adsorption with the metal surface through the phosphonate group, while the inorganic anions enhance the interlayer charge balance, thereby improving the adsorption density and stability of hydrotalcite on the metal surface.

[0034] 2. The main body of hydrotalcite is an inorganic material that is biodegradable, and the organic phosphonate is made with low-toxicity agents, avoiding the toxicity problems of traditional organic corrosion inhibitors. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the preparation process of the present invention. Detailed Implementation

[0036] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] Example 1:

[0038] like Figure 1 As shown, this embodiment of the invention provides a process for preparing hydrotalcite as a corrosion inhibitor, including the following steps:

[0039] Step one: raw material ratio:

[0040] Mg 2+ , Al 3+ as the metal ion of the layer, the molar ratio of the two is 2:1, the interlayer anion is a complex system of organic phosphonate and inorganic anion, wherein the organic phosphonate is aminotri-methylene phosphonate, the inorganic anion is NO3 - , Cl - , and the molar ratio of the organic phosphonate and the inorganic anion is 1:1, the molar ratio of the total anion and the metal ion is 0.5:1;

[0041] Step two: coprecipitation reaction:

[0042] Dissolve the soluble salt of Mg 2+ , Al 3+ in deionized water to prepare a metal salt mixed solution, the concentration of the metal salt mixed solution is 0.1 mol / L, dissolve the organic phosphonate and the inorganic anion salt in deionized water to prepare an anion mixed solution, the concentration of the anion mixed solution is 0.1 mol / L, under the condition of constant temperature stirring at 25℃, the metal salt mixed solution and the anion mixed solution are simultaneously dropped into the reaction container, the pH of the system is adjusted to 8 with NaOH solution during the dropping process, and the stirring is continued for 1h;

[0043] Step three: hydrothermal crystallization:

[0044] The reaction product of step two is transferred to a hydrothermal reaction kettle, and crystallized at 100℃ for 12h, and naturally cooled to room temperature;

[0045] Step four: post-processing:

[0046] The crystallization product is centrifuged and washed, the centrifugal washing is deionized water and ethanol alternating washing 3 times, dried at 60℃ for 12h, and then ground and sieved, and the mesh size of the ground and sieved is 80 meshes, and then the hydrotalcite particles are prepared;

[0047] Step five: composite material preparation:

[0048] (1) Nanoparticle dispersion: mix the above hydrotalcite particles with the polymer matrix, the polymer matrix is epoxy resin, add antioxidants and lubricants (0.5wt%), and uniformly disperse by high-speed stirring (300rpm);

[0049] (2) Forming processing: granulation is carried out by using a double screw extruder at 170℃, and a hydrotalcite-based corrosion inhibitor is prepared.

[0050] Further, the embodiment of the present application also provides a hydrotalcite-based corrosion inhibitor prepared according to the hydrotalcite corrosion inhibitor preparation process, the hydrotalcite-based corrosion inhibitor is used for surface protection of metal in neutral environment, and the metal includes steel, aluminum and its alloy.

[0051] Example Two:

[0052] As Figure 1 shown, the embodiment of the present application provides a preparation process of hydrotalcite as corrosion inhibitor, comprising the following steps:

[0053] Step One: Raw material ratio:

[0054] Mg 2+ , Al 3+ as the metal ions of the layer, the molar ratio of the two is 3:1, the interlayer anion is a composite system of organic phosphonate and inorganic anion, wherein the organic phosphonate is aminotri-methylene phosphonate, ethylenediamine tetra-methylene phosphonate, hydroxyethylidene diphosphonate, the inorganic anion is NO3 - , Cl - , SO4 2- , and the molar ratio of the organic phosphonate and the inorganic anion is 3:1, the molar ratio of the total anion and the metal ion is 1:1;

[0055] Step Two: Coprecipitation reaction:

[0056] Dissolve the soluble salt of Mg 2+ , Al 3+ in deionized water to prepare a mixed metal salt solution, the concentration of the mixed metal salt solution is 0.3 mol / L, dissolve the organic phosphonate and inorganic anion salt in deionized water to prepare a mixed anion solution, the concentration of the mixed anion solution is 0.3 mol / L, under the condition of constant temperature stirring at 40℃, the mixed metal salt solution and the mixed anion solution are simultaneously dropped into the reaction container, the pH of the system is adjusted to 10 with NaOH solution during the dropping process, and the stirring is continued for 2h;

[0057] Step Three: Hydrothermal crystallization:

[0058] Transfer the reaction product of Step Two to a hydrothermal reactor, crystallize at 150℃ for 36h, and naturally cool to room temperature;

[0059] Step Four: Post-processing:

[0060] Centrifugal wash the crystallization product, centrifugal wash is deionized water and ethanol alternately washed 4 times, dried at 80℃ for 24h, then ground and sieved, the sieve mesh of the ground and sieved is 120 mesh, and then the hydrotalcite particles are prepared;

[0061] Step Five: Composite material preparation:

[0062] (1) Nanoparticle dispersion: mix the above hydrotalcite particles with the polymer matrix, the polymer matrix is epoxy resin, polyethylene, add antioxidants and lubricants (amount 1wt%), and uniformly disperse by high-speed stirring (400rpm);

[0063] (2) Molding and processing: The hydrotalcite-based corrosion inhibitor was obtained by granulation at 180°C using a twin-screw extruder.

[0064] Furthermore, this embodiment of the invention also provides a hydrotalcite-based corrosion inhibitor prepared according to a hydrotalcite-based corrosion inhibitor preparation process as described above. The hydrotalcite-based corrosion inhibitor is used for surface protection of metals in a weakly acidic corrosive environment. The metals include steel, aluminum and their alloys.

[0065] Example 3:

[0066] like Figure 1 As shown, this embodiment of the invention provides a process for preparing hydrotalcite as a corrosion inhibitor, including the following steps:

[0067] Step 1: Raw material ratio:

[0068] With Mg 2+ Al 3+ The layers consist of metal ions in a molar ratio of 4:1. The interlayer anions are a complex system of organophosphonate and inorganic anions, wherein the organophosphonate is hydroxyethylidene diphosphonate and the inorganic anion is Cl. - SO4 2- Furthermore, the molar ratio of organophosphonate to inorganic anion is 5:1, and the molar ratio of total anion to metal ion is 1.5:1.

[0069] Step 2: Coprecipitation reaction:

[0070] Mg 2+ Al 3+ Soluble salts were dissolved in deionized water to prepare a mixed metal salt solution with a concentration of 0.5 mol / L. Organic phosphonic acid and inorganic anionic salts were dissolved in deionized water to prepare an anionic mixed solution with a concentration of 0.5 mol / L. Under constant temperature stirring at 60℃, the mixed metal salt solution and the mixed anionic solution were simultaneously added dropwise to the reaction vessel. During the dropwise addition, the pH of the system was adjusted to 11 with NaOH solution, and the stirring was continued for 3 hours.

[0071] Step 3: Hydrothermal crystallization:

[0072] The reaction product from step two was transferred to a hydrothermal reactor and crystallized at 180°C for 48 hours, then naturally cooled to room temperature.

[0073] Step 4: Post-processing:

[0074] The crystallized product was centrifuged and washed, with the centrifugation washing consisting of alternating washing with deionized water and ethanol five times. After drying at 100°C for 24 hours, it was ground and sieved through a 200-mesh sieve to obtain hydrotalcite particles.

[0075] Step five: composite material preparation:

[0076] (1) Nanoparticle dispersion: the above hydrotalcite particles are mixed with a polymer matrix, which is polyethylene, and antioxidants and lubricants (2 wt%) are added, and uniform dispersion is achieved by high-speed stirring (500 rpm);

[0077] (2) Forming processing: granulation is carried out at 190°C using a double-screw extruder to prepare a hydrotalcite-based corrosion inhibitor.

[0078] Further, the embodiment of the present application also provides a hydrotalcite-based corrosion inhibitor prepared according to the hydrotalcite-based corrosion inhibitor preparation process, and the hydrotalcite-based corrosion inhibitor is used for surface protection of metals in a neutral environment, and the metals include steel, aluminum and alloys thereof.

[0079] Comparative example one:

[0080] A hydrotalcite-based corrosion inhibitor preparation process, comprising the following steps:

[0081] Step one: raw material ratio:

[0082] Mg 2+ and Al 3+ are used as layer metal ions, the molar ratio of the two is 2:1, the interlayer anion is an organic phosphonate, wherein the organic phosphonate is an aminotrimethylene phosphonate, and the molar ratio of the total anion to the metal ion is 0.5:1;

[0083] Step two: coprecipitation reaction:

[0084] The soluble salts of Mg 2+ and Al 3+ are dissolved in deionized water to prepare a metal salt mixed solution, the concentration of the metal salt mixed solution is 0.1 mol / L, the organic phosphonate is dissolved in deionized water to prepare an anion mixed solution, the concentration of the anion mixed solution is 0.1 mol / L, under the condition of constant temperature stirring at 25°C, the metal salt mixed solution and the anion mixed solution are simultaneously dropped into a reaction container, the pH of the system is adjusted to 8 with a NaOH solution during the dropping process, and the stirring is continued for 1 h;

[0085] Step three: hydrothermal crystallization:

[0086] The reaction product of step two is transferred to a hydrothermal reaction kettle, and crystallization is carried out at 100°C for 12 h, and then the temperature is naturally cooled to room temperature;

[0087] Step four: post-treatment:

[0088] The crystallization product is centrifugally washed, centrifugally washed for 3 times by deionized water and ethanol alternately, dried at 60 DEG C for 12h, ground and sieved, and the sieving mesh is 80 mesh, and then the hydrotalcite particles are prepared;

[0089] Step five: composite material preparation:

[0090] (1) Nanoparticle dispersion: the above hydrotalcite particles are mixed with a polymer matrix, the polymer matrix is epoxy resin, an antioxidant and a lubricant (0.5wt%) are added, and the mixture is uniformly dispersed by high-speed stirring (300rpm);

[0091] (2) Forming processing: granulation is carried out by using a double screw extruder at 170 DEG C, and the hydrotalcite-based corrosion inhibitor is prepared.

[0092] Comparative example two:

[0093] The difference between the present comparative example two and the comparative example one is that the interlayer anion is an inorganic anion, wherein the inorganic anion is NO3 - , Cl - , the molar ratio of the total anion to the metal ion is 0.5:1, and the others remain unchanged.

[0094] Experimental example:

[0095] The hydrotalcite-based corrosion inhibitors prepared in example one, example two, example three, comparative example one and comparative example two are detected for corrosion inhibition performance, specifically, each corrosion inhibitor is added into a 3.5% NaCl solution, the concentration is 50mg / L, Q235 steel is used as a test piece, the weight loss method is used to test the corrosion inhibition efficiency, and the results are as follows:

[0096] Group Corrosion rate (mm / a) Inhibition efficiency (%) Example 1 0.02 96.3 Example 2 0.01 97.1 Example 3 0.02 96.4 Comparative Example 1 0.11 78.4 Comparative Example 2 0.14 78.1

[0097] In summary, the hydrotalcite prepared by the present application as a corrosion inhibitor can significantly improve the corrosion inhibition efficiency, compared with the comparative examples in which only organic phosphonate or inorganic anion is used as the interlayer anion, the corrosion inhibition performance is better. At the same time, the hydrotalcite main body is a degradable inorganic material, and the low-toxicity organic phosphonate agent is selected, which avoids the toxicity problem of traditional organic corrosion inhibitors, and has a wide application prospect in the field of metal protection. The synergistic mechanism of the interlayer composite anion provides a new idea and method for developing efficient and environmentally friendly corrosion inhibitors.

[0098] Although the embodiments of the present application have been shown and described, it can be understood by those skilled in the art that various changes, modifications, replacements and variations can be made to these embodiments without departing from the principles and spirits of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A process for the preparation of water-slides as corrosion inhibitors, characterized in that: The method comprises the following steps: Step 1: raw material proportioning Mg 2+ , Al 3+ as the metal ions of the layer, the molar ratio of the two being 2-4:1, the interlayer anion being a complex system of organic phosphonate and inorganic anion, the molar ratio of the total number of the anions to the metal ions being 0.5-1.5:1; Step 2: coprecipitation reaction Mg 2+ , Al 3+ soluble salts are dissolved in deionized water to prepare a metal salt mixed solution, and an organic phosphonic acid and an inorganic anion salt are dissolved in deionized water to prepare an anion mixed solution. The metal salt mixed solution and the anion mixed solution are simultaneously dropped into a reaction container under constant temperature stirring at 25-60°C. During the dropping process, the pH of the system is adjusted to an alkaline environment by using a NaOH solution. Step 3: hydrothermal crystallization The reaction product of Step 2 is transferred to a hydrothermal reactor, recrystallized, and naturally cooled to room temperature; Step 4: post-treatment The crystallization product is centrifuged and washed, dried at 60-100℃ for 12-24h, and then ground and sieved to obtain hydrotalcite particles; Step 5: composite material preparation (1) nanoparticle dispersion: the hydrotalcite particles and a polymer matrix are mixed, antioxidants and lubricants (0.5-2wt%) are added, and high-speed stirring (300-500rpm) is performed for uniform dispersion; (2) molding processing: a double-screw extruder is used to granulate at 170-190℃ to obtain the hydrotalcite-based corrosion inhibitor.

2. A process for the preparation of a hydrotalcite as an inhibitor, according to claim 1, characterized in that: In Step 1, the organic phosphonate is one or more of aminotri(methylene)phosphonate, ethylenediamine tetra(methylene)phosphonate, and hydroxyethylidene diphosphonate.

3. A process for the preparation of a hydrotalcite as an inhibitor, according to claim 1, characterized in that: In step one, the inorganic anion is NO3 - , Cl - , SO4 2- or a combination thereof, and the molar ratio of the organic phosphonate to the inorganic anion is 1-5:

1.

4. The process for preparing hydrotalcite as an inhibitor according to claim 1, characterized in that: In Step 2, the concentration of the metal salt mixed solution is 0.1-0.5mol / L, and the concentration of the anion mixed solution is 0.1-0.5mol / L.

5. The process for preparing hydrotalcite as an inhibitor according to claim 1, characterized in that: In Step 2, the pH of the system is adjusted to 8-11, and stirring is continued for 1-3h.

6. A process for the preparation of a hydrotalcite as an inhibitor according to claim 1, characterized in that: In Step 3, the crystallization temperature is 100-180℃, and the crystallization time is 12-48h.

7. A process for the preparation of a hydrotalcite as an inhibitor according to claim 1, characterized by: In Step 4, the centrifugal washing is alternating washing with deionized water and ethanol for 3-5 times, and the sieving mesh size of the ground and sieved product is 80-200 mesh.

8. The process for preparing hydrotalcite as an inhibitor according to claim 1, characterized in that: In Step 5, the polymer matrix is one or more of epoxy resin and polyethylene.

9. A hydrotalcite based corrosion inhibitor prepared according to the process of any one of claims 1 to 8, characterized in that, The hydrotalcite-based corrosion inhibitor is used for surface protection of metals, including steel, aluminum, and their alloys, in neutral or weakly acidic corrosive environments.

Images