Silicate go intercalation corrosion inhibitor for quaternary nitric acid molten salt and preparation and application thereof

Abstract

The application discloses a silicate GO intercalation corrosion inhibitor for quaternary nitric acid molten salt and preparation and application, and relates to the technical field of heat storage materials.The GO layer is a main frame and is a two-dimensional layer, and the layered silicate is inserted between the GO layers, and the orientation of the layered silicate is parallel to the GO layer.The silicate GO intercalation corrosion inhibitor is added into the quaternary nitric acid molten salt, and the addition amount is 0.4 wt%-5.0 wt%.The application prepares a two-dimensional intercalation composite structure corrosion inhibitor by organicizing the silicate and alkylating the GO, promotes the stability and dispersibility of the high-temperature quaternary nitric acid molten salt, slows down the corrosion of the high-temperature quaternary nitric acid molten salt on the metal matrix in a concentrated solar power and other high-temperature energy systems, and supports long-term stable operation of the high-temperature molten salt energy system.

Description

Technical Field

[0001] This invention relates to the field of thermal storage materials technology, specifically to silicate GO intercalation corrosion inhibitors for quaternary nitrate molten salts, their preparation and application. Background Technology

[0002] In the current context of profound changes in the global energy landscape and the accelerated energy revolution, achieving efficient, clean, and sustainable energy utilization has become a core objective. Tetravalent nitrate molten salts, with their excellent thermal stability, high ionic conductivity, and suitable melting point range, demonstrate enormous application potential in high-temperature energy systems such as centralized solar power generation, becoming an essential material in the energy revolution.

[0003] However, the inherent corrosiveness of quaternary nitrate molten salts severely hinders their large-scale engineering application. In actual operation, quaternary nitrate molten salts come into direct contact with metal equipment, and their strong corrosiveness can cause rapid corrosion of metal materials, leading to equipment performance degradation, significantly shortened lifespan, and even serious safety accidents. This not only increases the operating costs of energy systems but also seriously threatens the safe and stable operation of the systems, becoming a key problem restricting the widespread application of quaternary nitrate molten salts.

[0004] For a long time, traditional protective technologies such as coating protection and adding corrosion inhibitors to quaternary nitrate molten salts have been widely used in the field of metal corrosion protection. However, these traditional technologies are inadequate in extreme environments of high temperature and strong corrosion. High temperature accelerates the aging and peeling of coatings, causing them to lose their protective function; at the same time, high temperature also interferes with the stability of electrochemical protection systems, resulting in a significant reduction in the protective effect. Existing organic corrosion inhibitors are prone to high-temperature deactivation, and traditional inorganic corrosion inhibitors rely solely on chemical passivation, which cannot block Cl-. - Penetration. It cannot meet the protection requirements of quaternary nitrate molten salts in high-temperature energy systems. Summary of the Invention

[0005] The purpose of this invention is to provide a silicate GO intercalation corrosion inhibitor for quaternary nitrate molten salts, its preparation and application. A two-dimensional intercalation composite corrosion inhibitor is prepared by organifying silicates and alkylating graphene oxide (GO), which promotes the stability and dispersibility of high-temperature quaternary nitrate molten salts, slows down their corrosion of metal substrates in high-temperature energy systems such as centralized solar power generation, and supports the long-term stable operation of high-temperature molten salt energy systems.

[0006] Based on the above objectives, the present invention discloses a silicate-GO intercalation corrosion inhibitor for quaternary nitrate molten salts. In the silicate-GO intercalation corrosion inhibitor, the GO layer is the main framework and is two-dimensional layered. The layered silicate is intercalated between the GO layers, and the orientation of the layered silicate is parallel to that of the GO layer.

[0007] Preferably, the layered silicate is any one or more of muscovite, phlogopite, or vermiculite.

[0008] The present invention also provides the preparation of the above-mentioned silicate GO intercalation corrosion inhibitor for quaternary nitrate molten salts, comprising the following steps:

[0009] S1. Preparation of modified layered silicates;

[0010] Preparation of S2 and alkylated GO layers;

[0011] S3, Intercalation Assembly

[0012] The alkylated GO layer was dispersed in 1 mg / mL N,N-dimethylformamide (DMF) and sonicated for 30 min. Modified layered silicate was then added and stirred at 40 °C for 12-24 h. 0.1 mol / L calcium chloride (CaCl2) solution was added and stirred at 60 °C for 4-6 h. The precipitate was washed with DMF by centrifugation and placed in a tube furnace for heat treatment at 350-500 °C for 2 h under a nitrogen atmosphere to obtain the silicate-GO intercalation corrosion inhibitor.

[0013] Preferably, step S1 specifically includes the following steps:

[0014] S1-1, Organic Modification of Layered Silicates

[0015] The silicate was dispersed in a 5wt%-10wt% hexadecyltrimethylammonium bromide solution, the pH was adjusted to 9-10 with ammonia, and the mixture was stirred at 80℃ for 12-24 h. After centrifugation and washing, the mixture was dried under vacuum at 60℃. The dried mixture was then dispersed in anhydrous toluene, phenyltrimethoxysilane was added, and the mixture was refluxed at 110-150℃ for 6 h under nitrogen protection. The mixture was washed three times with ethanol to remove unreacted silane, and then dried to obtain the organosilicate.

[0016] S1-2, Carrier Modification

[0017] Organosilicates were dispersed in an ethanol solution of 0.1 mol / L cerium nitrate (Ce(NO3)3), refluxed at 80 °C for 12 h, and washed by centrifugation to obtain Ce-loaded silicates. 3+ silicates;

[0018] S1-3, High Temperature Stability

[0019] Modified layered silicate was obtained by calcination at 450°C for 2 hours in air atmosphere.

[0020] Preferably, step S2 specifically includes the following steps:

[0021] S2-1. Prepare a 1 mg / mL aqueous solution of GO prepared by the Hummers method and sonicate for 2 h; add 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) and N-hydroxysuccinimide (NHS); stir at room temperature for 1 h.

[0022] S2-2, Add octadecylamine and react at 70°C for 24 hours to obtain an alkylated GO layer.

[0023] Preferably, in step S3, the mass ratio of the alkylated GO layer to the modified layered silicate is 1:(2-5); the molar ratio of CaCl2 to the GO layer is (5-10):1.

[0024] Preferably, in step S1-1, the ratio of hexadecyltrimethylammonium bromide (CTAB) to silicate is 2-5 mmol: 1 g; and the ratio of phenyltrimethoxysilane to silicate is 0.1-0.5 ml: 1 g.

[0025] In steps S1-2, the ratio of organosilicon salt to Ce(NO3)3 ethanol solution is (1-2) g: 100 mL.

[0026] Preferably, in step S2-1, the mass ratio of GO to 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and N-hydroxysuccinimide is 1:(1-1.5):(0.1-1).

[0027] In step S2-2, the mass ratio of GO to octadecylamine (ODA) is 1:(2-5).

[0028] The silicate-GO intercalation corrosion inhibitor provided by this invention is added to a quaternary nitrate molten salt at an amount of 0.4 wt%-5.0 wt%.

[0029] Therefore, the present invention employs the above-mentioned silicate GO intercalation corrosion inhibitor for quaternary nitrate molten salts, its preparation and application, and has the following beneficial effects:

[0030] 1. This corrosion inhibitor uses alkylated graphene oxide (GO) as its main framework. Its two-dimensional layered structure provides excellent physical barrier properties, effectively extending the diffusion path of corrosive media to the metal surface. The alkylation treatment of GO significantly improves its dispersibility and compatibility in hydrophobic quaternary nitrate molten salts and enhances the material's high-temperature chemical stability. Layered silicates, as key intercalation components, are parallelly embedded between the GO layers, exhibiting high thermal stability and rigidity, preventing the GO layers from collapsing at high temperatures and maintaining and strengthening the overall dense barrier structure. Through complex organic modification and cerium ion loading, the silicate significantly improves its interfacial compatibility and hydrophobicity with the molten salt and GO, exhibiting highly efficient electrochemical corrosion inhibition activity. High-temperature calcination stabilizes the modified surface of the silicate and solidifies the loaded cerium species, ensuring its long-term effectiveness at molten salt operating temperatures.

[0031] 2. The corrosion inhibitor provided by this invention has good thermal stability and dispersion compatibility, and can maintain long-term effectiveness under CSP conditions of >400℃; at the same time, it has dual corrosion inhibition effects of physical barrier and electrochemical passivation, which significantly improves the inhibition effect on harsh chloride salt corrosion; and minimizes the negative impact on the heat transfer / heat storage performance of molten salt.

[0032] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0033] Figure 1 A flowchart illustrating the preparation process of the silicate GO intercalation corrosion inhibitor for quaternary nitrate molten salts provided by this invention.

[0034] Figure 2 This is a SEM image of the alkylated GO layer prepared in Example 2 of the present invention;

[0035] Figure 3 This is a SEM image of the silicate-GO intercalation corrosion inhibitor prepared in Example 3 of the present invention. Detailed Implementation

[0036] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0037] This invention discloses a silicate-GO intercalation corrosion inhibitor for quaternary nitrate molten salts. In the silicate-GO intercalation corrosion inhibitor, the GO layer forms the main framework and is two-dimensionally layered. Layered silicates are intercalated between the GO layers, and the orientation of the layered silicates is parallel to that of the GO layers. The layered silicates are any one or more of muscovite, phlogopite, or vermiculite.

[0038] The preparation process of the silicate GO intercalation corrosion inhibitor for quaternary nitrate molten salts is as follows: Figure 1 As shown, it includes the following steps:

[0039] S1. Preparation of modified layered silicates.

[0040] Preparation of S2 and alkylated GO layers.

[0041] S3, intercalation assembly.

[0042] The alkylated GO layer was dispersed in 1 mg / mL DMF and sonicated for 30 min. Modified layered silicate was then added, and the mixture was stirred at 40 °C for 12-24 h. 0.1 mol / L CaCl2 solution was added, and the mixture was stirred at 60 °C for 4-6 h. The precipitate was washed with DMF by centrifugation and then heat-treated in a tube furnace at 350-500 °C for 2 h under a nitrogen atmosphere to obtain a silicate-GO intercalation corrosion inhibitor. After this intercalation assembly, an interleaved structure of "alkylated GO layer-modified layered silicate" is formed.

[0043] Step S1 specifically includes the following steps:

[0044] S1-1, Organic Modification of Layered Silicates

[0045] The silicate was dispersed in a 5wt%-10wt% hexadecyltrimethylammonium bromide solution, the pH was adjusted to 9-10 with ammonia, and the mixture was stirred at 80℃ for 12-24 h. After centrifugation and washing, the mixture was dried under vacuum at 60℃. The dried mixture was then dispersed in anhydrous toluene, phenyltrimethoxysilane was added, and the mixture was refluxed at 110-150℃ for 6 h under nitrogen protection. The mixture was washed three times with ethanol to remove unreacted silane, and then dried to obtain the organosilicate.

[0046] S1-2, Carrier Modification

[0047] Organosilicates were dispersed in a 0.1 mol / L Ce(NO3)3 ethanol solution, refluxed at 80 °C for 12 h, and washed by centrifugation to obtain Ce-loaded silicates. 3+ silicates.

[0048] S1-3, High Temperature Stability

[0049] Modified layered silicate was obtained by calcination at 450°C for 2 hours in air atmosphere.

[0050] Organic modification of CTAB and phenyl groups is first performed on layered silicates to expand the layers, while also making them hydrophobic and dispersible to improve their high-temperature resistance to collapse. Then, cerium oxide nanoparticles and carbonized phenyl groups are formed through inorganic carrier and high-temperature calcination, which maintains the interlayer spacing and forms a high-temperature corrosion inhibitor.

[0051] Step S2 specifically includes the following steps:

[0052] S2-1. Prepare a 1 mg / mL aqueous solution of GO prepared by the Hummers method and sonicate for 2 h; add 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and N-hydroxysuccinimide; stir at room temperature for 1 h to activate the carboxyl group.

[0053] S2-2, Add octadecylamine and react at 70°C for 24 hours to obtain an alkylated GO layer.

[0054] In step S3, the mass ratio of the alkylated GO layer to the modified layered silicate is 1:(2-5); the molar ratio of CaCl2 to the GO layer is (5-10):1.

[0055] EDC / NHS and ODA are modified on the graphene oxide layer to activate the carboxyl groups on the surface of the GO layer and stabilize the intermediate. The amino groups on the surface of ODA form amide bonds with the activated carboxyl groups, and long alkyl chains are branched onto the surface of the GO layer to complete the hydrophobication of GO and the interaction with the alkyl chains of silicate, thus maintaining interlayer stability.

[0056] In step S1-1, the ratio of hexadecyltrimethylammonium bromide to silicate is 2-5 mmol: 1 g; the ratio of phenyltrimethoxysilane to silicate is 0.1-0.5 ml: 1 g.

[0057] In steps S1-2, the ratio of organosilicon salt to Ce(NO3)3 ethanol solution is (1-2) g: 100 mL.

[0058] In step S2-1, the mass ratio of GO to 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and N-hydroxysuccinimide is 1:(1-1.5):(0.1-1).

[0059] In step S2-2, the mass ratio of GO to octadecylamine is 1:(2-5).

[0060] The silicate-GO intercalation corrosion inhibitor provided by this invention is added to a quaternary nitrate molten salt at an amount of 0.4 wt%-5.0 wt%.

[0061] 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. These other embodiments are also covered within the scope of protection of this invention.

[0062] The present invention will be further described below with reference to the embodiments and accompanying drawings. All chemicals and reagents used in the embodiments were purchased commercially. In this embodiment, the blanks are all slab blanks.

[0063] Example 1

[0064] This embodiment provides a modified silicate, the preparation of which includes the following steps:

[0065] (1) 10g of dolomite silicate was dispersed in 200ml of 5wt% cetyltrimethylammonium bromide solution, the pH was adjusted to 9 with ammonia water, and stirred at 80℃ for 12h; centrifuged, washed and vacuum dried at 60℃; then the dried mixture was dispersed in anhydrous toluene, 5ml of phenyltrimethoxysilane was added, and refluxed at 110℃ for 6h under nitrogen protection; washed 3 times with ethanol to remove unreacted silane, and dried to obtain organosilicone.

[0066] (2) The organosilicate was dispersed in 1000 mL of 0.1 mol / L Ce(NO3)3 ethanol solution, refluxed at 80 °C for 12 h, centrifuged and washed to obtain Ce-loaded silicate. 3+ The silicate was calcined at 450°C for 2 hours in air to obtain modified layered silicate.

[0067] Example 2

[0068] This embodiment provides an alkylated GO layer, the preparation of which includes the following steps:

[0069] (1) 1g of GO prepared by the Hummers method was placed in 1000mL of water to prepare an aqueous solution of 1mg / mL and sonicated for 2h; 1g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and 0.5g of N-hydroxysuccinimide were added; the carboxyl group was activated by stirring at room temperature for 1h.

[0070] (2) Take 1g of the preliminarily activated GO from step (1) and add it to 100ml of organic solvent. Add 2g of octadecylamine and react at 70℃ for 24h to obtain an alkylated GO layer. The SEM image of the alkylated GO layer prepared in this example is shown below. Figure 2 As shown, Figure 2 The results show that the wrinkled morphology conforms to the characteristics of a single layer of GO, with multiple layers of GO stacked and a certain degree of surface roughness, proving the successful grafting of organic chains.

[0071] Example 3

[0072] This embodiment provides a silicate-GO intercalation corrosion inhibitor, the preparation process of which includes the following steps:

[0073] (1) The preparation of the modified silicate is the same as in Example 1, and will not be repeated here;

[0074] (2) The preparation of the alkylated GO layer is the same as in Example 2, and will not be repeated here;

[0075] (3) Take 1g of alkylated GO prepared in step (2) and disperse it in 500ml of DMF and sonicate for 30 minutes. Add 3g of modified silicate prepared in step (1) and stir at 40℃ for 12h. Add 35ml of 0.1mol / L CaCl2 solution and stir at 60℃ for 4h. Centrifuge and wash the precipitate with DMF. Place the precipitate in a tube furnace and heat treat at 400℃ for 2h under nitrogen atmosphere to obtain silicate-GO intercalation corrosion inhibitor.

[0076] The SEM image of the silicate-GO intercalation corrosion inhibitor prepared in this embodiment is shown below. Figure 3 As shown in the figure, the corrosion inhibitor exhibits a clear layered overlapping structure with a layered framework. Irregular undulations and wrinkles exist on the surface and between layers, and lamellar silicate edges are visible between the layers. This proves that the modified layered silicate is inserted into the alkylated GO layer, changing the original alkylated GO layer structure. This indicates that the silicate-GO intercalation corrosion inhibitor was successfully prepared in this embodiment.

[0077] Example 4

[0078] This embodiment provides a modified silicate, and the preparation process is the same as that in Example 1, except that the muscovite in step (1) is replaced with phlogopite.

[0079] Example 5

[0080] This embodiment provides a silicate-GO intercalation corrosion inhibitor, which is prepared in the same way as in Example 3, except that only organic silicate is obtained in step (1).

[0081] Application examples

[0082] The products prepared in Examples 1-3 and Example 5 were used as corrosion inhibitors and mixed with quaternary nitrate molten salts at an addition amount of 5.0 wt%. The quaternary nitrate molten salts were prepared by the following method:

[0083] NaNO3, KNO3, NaNO2, and Ca(NO3)2 were dried in an oven at 150°C for 48 hours to remove moisture. The dried samples were then mixed and ground in a planetary ball mill for 30 minutes. The samples were then transferred to a silicon carbide crucible and placed in a muffle furnace. The temperature was increased from 30°C to 400°C at a rate of 10°C / min and held at 400°C for 4 hours to ensure complete melting and thorough mixing of the nitrates. This process is called the static melting method. The muffle furnace was then cooled to 280°C, and the molten salt mixture was removed and allowed to cool naturally to room temperature. Finally, the mixture was ground in a mill for 2 minutes to obtain the final product.

[0084] The above mixture was heated to 500℃ in an argon atmosphere for a high-temperature corrosion test. 316L stainless steel substrates were immersed in the mixture, and a control group was set up by directly immersing 316L stainless steel substrates in an equal volume of quaternary nitrate molten salt. After 1000 hours, the surface corrosion degree of the stainless steel was calculated, and the results are shown in Table 1 below.

[0085] Table 1

[0086] ;

[0087] The above results demonstrate that the corrosion inhibitor in Example 3, possessing a complete structure, exhibits superior performance. Its dense, tortuous channels, formed by the insertion of silicates between the GO layers, extend the diffusion path of corrosion ions, while its cerium ions provide electrochemical protection. Example 1, consisting only of modified silicates, lacks the channels formed between the silicates and the GO layers, thus only possessing chemical blocking capabilities. Example 2, with its alkylated GO layer, suffers from edge carboxyl groups that adsorb corrosion ions, creating a localized acidic environment that exacerbates pitting corrosion and increases the degree of corrosion.

[0088] Therefore, this invention provides a silicate GO intercalation corrosion inhibitor for quaternary nitrate molten salts, its preparation and application. A two-dimensional intercalation composite corrosion inhibitor is prepared by organifying silicate and alkylating GO, which promotes the stability and dispersibility of high-temperature quaternary nitrate molten salts, slows down their corrosion of metal substrates in high-temperature energy systems such as centralized solar power generation, and supports the long-term stable operation of high-temperature molten salt energy systems.

[0089] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and does not limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. Preparation of silicate GO intercalation corrosion inhibitor for quaternary nitric acid molten salt, characterized in that, The GO layer is a main frame and is a two-dimensional layer, and the layered silicate is inserted between the GO layers, and the layered silicate is parallel to the orientation of the GO layer; The layered silicate is any one or more of muscovite, phlogopite or vermiculite; The method comprises the following steps: S1, preparation of modified layered silicate; S2, preparation of alkylated GO layer; S3, intercalation assembly After the alkylated GO layer is dispersed in 1 mg / mL DMF and ultrasonated for 30 min, the modified layered silicate is added, and stirring is performed at 40℃ for 12-24 h; 0.1 mol / L CaCl2 solution is added, and stirring is performed at 60℃ for 4-6 h; the precipitate is washed with DMF by centrifugation, and the precipitate is placed in a tube furnace, and heat treatment is performed at 350-500℃ for 2 h in a nitrogen atmosphere to obtain the silicate-GO intercalation corrosion inhibitor; Step S1 specifically comprises the following steps: S1-1, organic modification of layered silicate The silicate is dispersed in a 5wt%-10wt% cetyltrimethylammonium bromide solution, ammonia water is used to adjust the pH to 9-10, and stirring is performed at 80℃ for 12-24 h; the product is washed by centrifugation and dried at 60℃ under vacuum; then the dried mixture is dispersed in anhydrous toluene, phenyltrimethoxysilane is added, and refluxing is performed at 110-150℃ under nitrogen protection for 6 h; the product is washed with ethanol for 3 times to remove the unreacted silane, and drying is performed to obtain the organic silicate; S1-2, carrier modification The organosilicate was dispersed in a 0.1 mol / L Ce(N03)3 solution in ethanol and refluxed at 80°C for 12 h, centrifuged and washed to obtain the silicate loaded with Ce 3+ . S1-3, high-temperature stability Calcination is performed at 450℃ in an air atmosphere for 2 h to obtain the modified layered silicate.

2. The preparation of silicate GO intercalation corrosion inhibitor for quaternary nitrate molten salt according to claim 1, characterized in that, Step S2 specifically comprises the following steps: S2-1, a GO prepared by the Hummers method is prepared into a 1 mg / mL aqueous solution, and ultrasonation is performed for 2 h; 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide and N-hydroxysuccinimide are added; stirring is performed at room temperature for 1 h; S2-2, octadecylamine is added, and reaction is performed at 70℃ for 24 h; the alkylated GO layer is obtained.

3. The preparation of silicate GO intercalation corrosion inhibitor for quaternary nitrate molten salt according to claim 1, characterized in that, In step S3, the mass ratio of the alkylated GO layer to the modified layered silicate is 1:(2-5); the molar ratio of CaCl2 to the GO layer is (5-10):

1.

4. The preparation of silicate GO intercalation corrosion inhibitor for quaternary nitrate molten salt according to claim 1, characterized in that, In step S1-1, the input ratio of cetyltrimethylammonium bromide to the silicate is 2-5 mmol:1 g; the input ratio of phenyltrimethoxysilane to the silicate is 0.1-0.5 ml:1 g; In step S1-2, the input ratio of the organic silicate to the ethanol solution of Ce(NO3)3 is (1-2) g:100 mL.

5. The preparation of silicate GO intercalation corrosion inhibitor for quaternary nitrate molten salt according to claim 2, characterized in that, In step S2-1, the mass ratio of GO to 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide and N-hydroxysuccinimide is 1:(1-1.5):(0.1-1); In step S2-2, the mass ratio of GO to octadecylamine is 1:(2-5).

6. Use of silicate GO intercalation corrosion inhibitors for quaternary nitric acid molten salts, characterized in that, The silicate-GO intercalation corrosion inhibitor is obtained by the preparation of the silicate-GO intercalation corrosion inhibitor for quaternary nitric acid molten salt according to any one of the above claims 1-5, and the silicate-GO intercalation corrosion inhibitor is added into the quaternary nitric acid molten salt, and the addition amount is 0.4 wt%-5.0 wt%.

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