Preparation method of composite phosphorus-free water treatment corrosion inhibitor

Abstract

The invention discloses a preparation method of a composite non-phosphorus water treatment corrosion inhibitor, and relates to the technical field of corrosion inhibitors. Specifically, the corrosion inhibitor is a larger molecular product of an externally hydroxylated hexanal inner core, and the composite non-phosphorus water treatment corrosion inhibitor is uniformly mixed by stirring with p-toluenesulfonic acid, pentahydroxyaldehyde, and hydroxy acid, and reacted under reduced pressure to obtain a reaction intermediate product A, and then maleic anhydride and thiourea molybdenum complex dissolved in acetic acid are added to obtain a larger molecular product of an hexanal inner core with external hydroxyl-carboxylation. The thiourea molybdenum complex obtained by the thiol addition reaction with organic metal molybdenum has better corrosion inhibition performance. Because the complex has stronger coordination ability and better stability, it can be better adsorbed on the metal surface and form a protective film, thereby slowing down the process of metal corrosion.

Description

Technical Field

[0001] The invention relates to the technical field of corrosion inhibitors, and in particular to a method for preparing a composite phosphorus-free water treatment corrosion inhibitor. Background Art

[0002] With the enhancement of people's environmental awareness and national environmental protection requirements, the requirements for corrosion inhibitors used in water treatment development are gradually increasing, the requirements for phosphates are becoming more and more stringent, and the concept of "green corrosion inhibitor" has been proposed. Finding corrosion inhibitors with good corrosion inhibition effect and no phosphorus has become the focus of people's attention.

[0003] Patent CN 109879452 A discloses a phosphorus-free water treatment corrosion inhibitor, including a phosphorus-free corrosion inhibitor base component A and amphoteric surfactants B and C. The phosphorus-free corrosion inhibitor base component A is based on fatty acids and alcohol amine compounds as raw materials, and the fatty acids and alcohol amine compounds are mixed in a molar ratio of 1:1.1-2.2. The addition amount of the catalyst zinc chloride is 0.5-1.0%. The amphoteric surfactant B includes water, methanol, sodium hydroxide and chloroacetic acid, and the methanol aqueous solution is a solvent. The amphoteric surfactant C is a mixture of the phosphorus-free corrosion inhibitor base component A and polyethylene glycol with a mass component of 5% to 15% and epichlorohydrin with a mass component of 15% to 20%. The phosphorus-free corrosion inhibitor base component A, the amphoteric surfactants B and C are compounded in a mass percentage ratio of 3:1:2.5 to obtain a phosphorus-free water treatment corrosion inhibitor.

[0004] Patent CN 116554940 A belongs to the field of petrochemical technology, and more specifically, relates to an oily corrosion inhibitor and a preparation method thereof. 70-90 parts of imidazoline amide corrosion inhibitor, 10-13 parts of auxiliary agent, and 110-130 parts of solvent; the imidazoline amide corrosion inhibitor is prepared by dehydration and cyclization of neodecanoic acid and diethylenetriamine at a molar ratio of 1.1:1.52 at high temperature; the auxiliary agent includes an amide compound and dialkyl dithiophosphate oxymolybdenum; the amide compound is formed by the reaction of the diethylenetriamine and α (acetoxy) phenylacetyl chloride.

[0005] The present invention invents a composite phosphorus-free water treatment corrosion inhibitor, which has a simple preparation method, low cost, good slow-release effect in a water environment, and can be used in combination with other copolymer scale inhibitors. Summary of the invention

[0006] In order to meet the current demand for phosphorus-free corrosion inhibitors and overcome the shortcomings of the existing technology, this patent proposes a composite phosphorus-free water treatment corrosion inhibitor, which has a simple preparation method, low cost, and good slow-release effect in a water environment.

[0007] To achieve the above object, the present invention provides a composite phosphorus-free water treatment corrosion inhibitor, wherein the corrosion inhibitor is a relatively large molecular product of an externally hydroxylated hexanal inner core.

[0008] The specific technical solutions of the present invention are as follows:

[0009] 1) Under inert gas protection and room temperature, 0.01-0.15 parts of p-toluenesulfonic acid, 0.18-3.3 parts of pentahydroxyaldehyde, and 0.76-12.9 parts of hydroxy acid are mixed uniformly by stirring, and the temperature is gradually raised to 130-155° C., and the reaction is continued at this temperature under normal pressure for 2-6 hours, and then a reduced pressure reaction is carried out for 2-6 hours to obtain a reaction intermediate A;

[0010] 2) The intermediate product A in step 1 is naturally cooled to 60-75° C., glacial acetic acid is added, and then 0.98-14.7 parts of maleic anhydride are dissolved in 5-75 parts of acetic acid and added to the mixed solution, and stirred thoroughly to obtain an intermediate product B.

[0011] 3) The intermediate product B described in step 2 is naturally cooled to 30-65° C., and then 0.16-3.44 parts of thiourea molybdenum complex are added to the cooled intermediate product B, and then 5-75 parts of acetic acid are added, and the mixture is stirred again. After the reaction is sufficient, the solution is allowed to cool to room temperature naturally. It will be found that the solution gradually generates a solid product. The solid product is washed and dried to obtain a larger molecular product having an external hydroxyl-carboxylated hexanal inner core.

[0012] Preferably, the pentahydroxyaldehyde in step 1 is at least one of 2,3,4,5,6-pentahydroxyhexanal, 2,3,4,5,6-pentahydroxy-benzaldehyde, 1,3,5,6,7-pentahydroxy-8-methylanthraquinone, 3,5,7,3',4'-pentahydroxyflavanone, (2R,3R,4R,5S)-2,3,4,5,6-pentahydroxyhexyl 4-hydroxybenzoate, pentahydroxytryptophan, sucrose pentahydroxystearate and pentapentanol.

[0013] Preferably, the hydroxy acid in step 1 is at least one of p-hydroxyphenylacetic acid, 5-hydroxythiophene-2-carboxylic acid, 2,2-dihydroxymethylpropionic acid, 4-hydroxynaphthalene-2-carboxylic acid, sodium 2,3-dihydroxybenzoate, 4-hydroxy-1,2-phthalic acid, and 2-hydroxyphosphorylacetic acid.

[0014] Preferably, the stirring time in steps 2 and 3 is 2 to 10 hours, and further optimized to 2 to 6 hours.

[0015] Another aspect of the present invention provides a method for preparing a thiourea-based molybdenum complex:

[0016] S1. Weigh 9-16 parts of molybdenum source, 7-13 parts of 2,5-dimercaptoterephthalic acid, 0.05-0.5 parts of thiophene-2,5-dicarboxylic acid, and 0.8-3.2 parts of acetic acid in parts by weight, and place them in 100-120 parts of N,N-dimethylformamide. After ultrasonic dispersion, stir at 50-65°C for 2-4 hours, and add sodium hydroxide to pH = 9-11 to generate a reaction intermediate product C.

[0017] S2, add 24-38 parts of 1,3-diallyl-2-thiourea, 0.04-0.5 parts of 3-(2-carboxyvinyl)phenylboric acid, and 3-7 parts of sodium ethoxide to the intermediate product C, stir at 65-77° C. for 50-120 minutes, and distill off N,N-dimethylformamide to obtain a thiourea-based molybdenum complex;

[0018] Preferably, the molybdenum source in step S1 is one of molybdenum nitrate, ammonium tetrathiomolybdate, ammonium molybdate, molybdenum chloride, molybdenum acetate, and molybdenum acetylacetonate.

[0019] Technical Effects

[0020] (1) It is understood that organic corrosion inhibitors inhibit corrosion through interface transformation. The corrosion inhibitor of the present invention has a large number of hydroxyl and carboxyl groups on the outside and has a strong corrosion inhibition effect. In addition, corrosion inhibitors with polar groups such as carboxyl and hydroxyl groups play a protective role by forming a coordination chelate film with metal surface ions. The generated surface complex has a stable structure and low solubility, which can play an excellent protective role. In addition, the generated complex film is very compact and can be well adsorbed on the surface of the material.

[0021] (2) The ability of S atoms in the corrosion inhibitor of the present invention to provide lone pairs of electrons is stronger than that of N atoms, so theoretically, the binding force between the dendritic polymer containing S atoms and the metal surface should be stronger. The thiourea molybdenum complex containing S and N has the ability to adsorb iron in the metal.

[0022] (3) The thiourea molybdenum complex obtained by the addition reaction with the thiol group of organic metal molybdenum has better corrosion inhibition performance. This is because the complex has stronger coordination ability and better stability, and can be better adsorbed on the metal surface and form a protective film, thereby slowing down the process of metal corrosion. DETAILED DESCRIPTION

[0023] The technical solutions in the embodiments of the present invention are clearly and completely described below in conjunction with the embodiments. Obviously, the embodiments described below are only descriptions of some embodiments of the present invention, do not represent all embodiments, and cannot constitute any limitation to the protection scope of the present invention.

[0024] Corrosion inhibition test method: in accordance with the standard GB / T18175-2014 "Determination of corrosion inhibition performance of water treatment agents - Rotating hanging plate method".

[0025] Example 1

[0026] A preparation method of a composite phosphorus-free water treatment corrosion inhibitor:

[0027] 1) Under inert gas protection and room temperature, 0.01 g of p-toluenesulfonic acid, 0.18 g of 2,3,4,5,6-pentahydroxyhexanal, and 0.76 g of p-hydroxyphenylacetic acid were mixed uniformly by stirring, and the temperature was gradually raised to 130° C., and the reaction was continued at this temperature under normal pressure for 2 hours, and then a reduced pressure reaction was carried out for 2 hours to obtain a reaction intermediate A;

[0028] 2) The intermediate product A in step 1 is naturally cooled to 60° C., glacial acetic acid is added, and then 0.98 g of maleic anhydride is dissolved in 5 g of acetic acid and added to the mixed solution, and stirred thoroughly to obtain an intermediate product B.

[0029] 3) The intermediate product B described in step 2 is naturally cooled to 30°C, and then 0.16g of thiourea molybdenum complex is added to the cooled intermediate product B, and then 5g of acetic acid is added, and the mixture is stirred again. After the reaction is sufficient, the solution is allowed to cool to room temperature naturally. It will be found that the solution gradually generates a solid product. The solid product is washed and dried to obtain a larger molecular product having an external hydroxyl-carboxylated hexanal core.

[0030] Another aspect of the present invention provides a method for preparing a thiourea-based molybdenum complex:

[0031] S1. Weigh 9 g of molybdenum nitrate, 7 g of 2,5-dimercaptoterephthalic acid, 0.05 g of thiophene-2,5-dicarboxylic acid, and 0.8 g of acetic acid, place them in 100 g of N,N-dimethylformamide, disperse them by ultrasonication, stir them at 50°C for 2 hours, add sodium hydroxide until the pH is 9, and generate a reaction intermediate C;

[0032] S2, add 24g 1,3-diallyl-2-thiourea, 0.04g 3-(2-carboxyvinyl)phenylboric acid, and 3g sodium ethoxide to the intermediate product C, stir at 65°C for 50min, and distill off N,N-dimethylformamide to obtain a thiourea-based molybdenum complex;

[0033] Example 2

[0034] A preparation method of a composite phosphorus-free water treatment corrosion inhibitor:

[0035] 1) Under inert gas protection and room temperature, 0.5 g of p-toluenesulfonic acid, 1.45 g of 1,3,5,6,7-pentahydroxy-8-methylanthraquinone, and 4.55 g of 4-hydroxy-1,2-phthalic acid were uniformly mixed by stirring, and the temperature was gradually raised to 140° C., and the reaction was continued at this temperature under normal pressure for 3 h, and then a reduced pressure reaction was carried out for 2.5 h to obtain a reaction intermediate A;

[0036] 2) The intermediate product A in step 1 is naturally cooled to 65° C., glacial acetic acid is added, and then 4.9 g of maleic anhydride is dissolved in 25 g of acetic acid and added to the mixed solution, and stirred thoroughly to obtain an intermediate product B.

[0037] 3) The intermediate product B described in step 2 is naturally cooled to 35° C., and then 0.48 g of the thiourea molybdenum complex is added to the cooled intermediate product B, and then 25 g of acetic acid is added, and the mixture is stirred again. After the reaction is sufficient, the solution is allowed to cool to room temperature naturally. It will be found that the solution gradually generates a solid product. The solid product is washed and dried to obtain a larger molecular product having an external hydroxyl-carboxylated hexanal inner core.

[0038] Another aspect of the present invention provides a method for preparing a thiourea-based molybdenum complex:

[0039] S1. Weigh 9.9 g of molybdenum nitrate, 7.7 g of 2,5-dimercaptoterephthalic acid, 0.55 g of thiophene-2,5-dicarboxylic acid, and 0.88 g of acetic acid, place them in 110 g of N,N-dimethylformamide, disperse them by ultrasonication, stir them at 55°C for 2.5 hours, add sodium hydroxide until the pH is 9.2, and generate a reaction intermediate C.

[0040] S2, add 26.4g of 1,3-diallyl-2-thiourea, 0.044g of 3-(2-carboxyvinyl)phenylboronic acid, and 3.3g of sodium ethoxide to the intermediate product C, stir at 67°C for 60 minutes, and distill off N,N-dimethylformamide to obtain a thiourea molybdenum complex;

[0041] Example 3

[0042] A preparation method of a composite phosphorus-free water treatment corrosion inhibitor:

[0043] 1) Under inert gas protection and room temperature, 0.1 g of p-toluenesulfonic acid, 1.70 g of 2,3,4,5,6-pentahydroxy-benzaldehyde, and 9.409 g of 4-hydroxynaphthalene-2-carboxylic acid were uniformly mixed by stirring, and the temperature was gradually raised to 140° C., and the reaction was continued at this temperature under normal pressure for 3.5 hours, and then a reduced pressure reaction was carried out for 4 hours to obtain a reaction intermediate A;

[0044] 2) The intermediate product A in step 1 is naturally cooled to 66° C., glacial acetic acid is added, and then 9.8 g of maleic anhydride is dissolved in 50 g of acetic acid and added to the mixed solution, and stirred thoroughly to obtain an intermediate product B.

[0045] 3) The intermediate product B described in step 2 is naturally cooled to 46° C., and then 1.6 g of the thiourea molybdenum complex is added to the cooled intermediate product B, and then 50 g of acetic acid is added, and the mixture is stirred again. After the reaction is sufficient, the solution is allowed to cool to room temperature naturally. It will be found that the solution gradually generates a solid product. The solid product is washed and dried to obtain a larger molecular product having an external hydroxyl-carboxylated hexanal inner core.

[0046] Another aspect of the present invention provides a method for preparing a thiourea-based molybdenum complex:

[0047] S1. Weigh 13.5 g of molybdenum nitrate, 10.5 g of 2,5-dimercaptoterephthalic acid, 0.075 g of thiophene-2,5-dicarboxylic acid, and 1.2 g of acetic acid, place them in 150 g of N,N-dimethylformamide, disperse them by ultrasonication, stir them at 58°C for 3 hours, add sodium hydroxide until the pH is 10, and generate a reaction intermediate C.

[0048] S2, add 36g of 1,3-diallyl-2-thiourea, 0.36g of 3-(2-carboxyvinyl)phenylboronic acid, and 3.7g of sodium ethoxide to the intermediate product C, stir at 69°C for 80 minutes, and distill off N,N-dimethylformamide to obtain a thiourea-based molybdenum complex;

[0049] Example 4

[0050] A preparation method of a composite phosphorus-free water treatment corrosion inhibitor:

[0051] 1) Under inert gas protection and room temperature, 0.15 g of p-toluenesulfonic acid, 3.30 g of pentahydroxytryptophan, and 12.9 g of 2-hydroxyphosphorylacetic acid were mixed uniformly by stirring, and the temperature was gradually raised to 155° C., and the reaction was continued at this temperature under normal pressure for 6 hours, and then a reduced pressure reaction was carried out for 6 hours to obtain a reaction intermediate A;

[0052] 2) The intermediate product A in step 1 is naturally cooled to 75° C., glacial acetic acid is added, and then 14.7 g of maleic anhydride is dissolved in 75 g of acetic acid and added to the mixed solution, and stirred thoroughly to obtain an intermediate product B.

[0053] 3) The intermediate product B described in step 2 is naturally cooled to 65° C., and then 3.44 g of the thiourea molybdenum complex is added to the cooled intermediate product B, and then 75 g of acetic acid is added, and the mixture is stirred again. After the reaction is sufficient, the solution is allowed to cool to room temperature naturally. It will be found that the solution gradually generates a solid product. The solid product is washed and dried to obtain a larger molecular product having an external hydroxyl-carboxylated hexanal core.

[0054] Another aspect of the present invention provides a method for preparing a thiourea-based molybdenum complex:

[0055] S1. Weigh 16 g of molybdenum nitrate, 13 g of 2,5-dimercaptoterephthalic acid, 0.5 g of thiophene-2,5-dicarboxylic acid, and 3.2 g of acetic acid, place them in 120 g of N,N-dimethylformamide, disperse them by ultrasonication, stir them at 65°C for 4 h, add sodium hydroxide until the pH is 11, and generate a reaction intermediate C.

[0056] S2, add 38g of 1,3-diallyl-2-thiourea, 0.5g of 3-(2-carboxyvinyl)phenylboronic acid, and 7g of sodium ethoxide to the intermediate product C, stir at 77°C for 120min, and distill off N,N-dimethylformamide to obtain a thiourea molybdenum complex;

[0057] Comparative Example 1

[0058] A preparation method of a composite phosphorus-free water treatment corrosion inhibitor:

[0059] 1) Under inert gas protection and room temperature, 0.01 g of p-toluenesulfonic acid, 0.18 g of 2,3,4,5,6-pentahydroxyhexanal, and 0.76 g of p-hydroxyphenylacetic acid were mixed uniformly by stirring, and the temperature was gradually raised to 130° C., and the reaction was continued at this temperature under normal pressure for 2 hours, and then a reduced pressure reaction was carried out for 2 hours to obtain a reaction intermediate A;

[0060] 2) The intermediate product A in step 1 is naturally cooled to 60° C., glacial acetic acid is added, and then 0.98 g of maleic anhydride is dissolved in 5 g of acetic acid and added to the mixed solution, and stirred thoroughly to obtain an intermediate product B.

[0061] 3) The intermediate product B described in step 2 is naturally cooled to 30°C, and then 0.16g of thiourea molybdenum complex is added to the cooled intermediate product B, and then 5g of acetic acid is added, and the mixture is stirred again. After the reaction is sufficient, the solution is allowed to cool to room temperature naturally. It will be found that the solution gradually generates a solid product. The solid product is washed and dried to obtain a larger molecular product having an external hydroxyl-carboxylated hexanal core.

[0062] The corrosion inhibition performance of the corrosion inhibitors prepared in the above embodiments and comparative examples was tested by the rotating coupon measurement method in the standard "Rotating coupon method for determination of corrosion inhibition performance of water treatment agents GB / T18175-2014" and A3 steel coupons. The results are shown in Table 1.

[0063] Table 1 Corrosion inhibition test results

[0064]

[0065] From the data in the table, it can be seen that the corrosion inhibitor prepared by the embodiment of the present invention shows excellent corrosion inhibition performance. When the addition concentration is 40ppm, the corrosion inhibitor obtained in Example 1 can achieve a corrosion inhibition rate of 93.1%, which is significantly higher than the corrosion inhibition effect of the same concentration in Comparative Example 1. In addition, the maximum corrosion inhibition effect of the corrosion inhibitor obtained in the embodiment can reach 98.5% when its concentration is 200ppm. It can be obtained that the corrosion inhibitor of the present invention has a significant corrosion inhibition effect.

[0066] The comparative examples and embodiments described above are only partial implementation methods of the present invention and do not constitute a limitation on the protection scope of the present invention. Further modifications or supplements made by researchers in the technical field of the present invention on this basis, but not deviating from the spirit of the present invention or exceeding the scope of the contents of the appended claims of the present invention, are within the protection scope of the present invention.

Claims

1. A method for preparing a composite phosphorus-free water treatment corrosion inhibitor, characterized in that: The following steps are involved: 1) Under inert gas protection and room temperature, 0.01-0.15 parts of p-toluenesulfonic acid, 0.18-3.3 parts of pentahydroxyaldehyde, and 0.76-12.9 parts of hydroxy acid are mixed uniformly by stirring, and the temperature is gradually raised to 130-155° C., and the reaction is continued at this temperature for 2-6 hours under normal pressure, and then a reduced pressure reaction is carried out for 2-6 hours to obtain a reaction intermediate A; 2) The intermediate product A in step 1 is naturally cooled to 60-75°C, glacial acetic acid is added, and then 0.98-14.7 parts of maleic anhydride are dissolved in 5-75 parts of acetic acid and added to the mixed solution, and stirred thoroughly to obtain an intermediate product B; 3) The intermediate product B described in step 2 is naturally cooled to 30-65°C, and then 0.16-3.44 parts of thiourea molybdenum complex are added to the cooled intermediate product B, and then 5-75 parts of acetic acid are added, and the mixture is stirred again. After the reaction is sufficient, the solution is allowed to cool to room temperature naturally. It will be found that the solution gradually generates a solid product. The solid product is washed and dried to obtain a product having an external hydroxyl-carboxylated hexanal inner core.

2. The method for preparing a composite phosphorus-free water treatment corrosion inhibitor according to claim 1, characterized in that: The pentahydroxyaldehyde includes at least one of 2,3,4,5,6-pentahydroxyhexanal, 2,3,4,5,6-pentahydroxy-benzaldehyde, 1,3,5,6,7-pentahydroxy-8-methylanthracnone, 3,5,7,3',4'-pentahydroxyflavanone, (2R,3R,4R,5S)-2,3,4,5,6-pentahydroxyhexyl 4-hydroxybenzoate, pentahydroxytryptophan, sucrose pentahydroxystearate and pentapentanol.

3. The method for preparing a composite phosphorus-free water treatment corrosion inhibitor according to claim 1, characterized in that: The hydroxy acid includes at least one of p-hydroxyphenylacetic acid, 5-hydroxythiophene-2-carboxylic acid, 2,2-dihydroxymethylpropionic acid, 4-hydroxynaphthalene-2-carboxylic acid, sodium 2,3-dihydroxybenzoate, 4-hydroxy-1,2-phthalic acid, and 2-hydroxyphosphorylacetic acid.

4. The method for preparing a composite phosphorus-free water treatment corrosion inhibitor according to claim 1, characterized in that: The preparation method of the thiourea molybdenum complex: S1. Weigh 9-16 parts of molybdenum source, 7-13 parts of 2,5-dimercaptoterephthalic acid, 0.05-0.5 parts of thiophene-2,5-dicarboxylic acid, and 0.8-3.2 parts of acetic acid in parts by weight, and place them in 100-120 parts of N,N-dimethylformamide. After ultrasonic dispersion, stir at 50-65°C for 2-4 hours, and add sodium hydroxide to pH = 9-11 to generate a reaction intermediate C. S2. Add 24-38 parts of 1,3-diallyl-2-thiourea, 0.04-0.5 parts of 3-(2-carboxyvinyl)phenylboric acid, and 3-7 parts of sodium ethoxide to the intermediate product C, stir at 65-77° C. for 50-120 minutes, and distill off N,N-dimethylformamide to obtain a thiourea-based molybdenum complex.

5. The method for preparing a composite phosphorus-free water treatment corrosion inhibitor according to claim 4, characterized in that: The molybdenum source in the step includes one of molybdenum nitrate, ammonium tetrathiomolybdate, ammonium molybdate, molybdenum chloride, molybdenum acetate, and molybdenum acetylacetonate.

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