RU2398916C1 - Inhibitor of metal corrosion in sulphuric and hydrochloric acids - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: inhibitor contains wt %: α-oxynaftalampicillin 10.7-8.6; 3-isopropylbenzo-2,1,3-thiadiazinone-4-dioxide-2.2 21.2-17.1; 2-heptadecylimidazolinylacetate 31.5-22.5; urotropin 36.6-51.8.

EFFECT: retarded corrosion of steel, aluminium and indium; reduced hydrogen pickup of steel.

2 tbl, 3 ex

Description

The invention relates to the field of protection of metals from acid corrosion using inhibitors and can be used in metallurgy, mechanical engineering for pickling metals and acid cleaning of equipment in the energy sector.

It is known the use of urotropin to reduce the corrosion rate of steel in sulfuric and hydrochloric acids (Altsybeeva A.I., Levin SZ, Metal corrosion inhibitors. - L .: Chemistry, 1968, p. 28-29). However, when corrosion is inhibited in sulfuric and hydrochloric acids of steel and other metals (for example, aluminum and indium), the effectiveness of urotropine is insufficient. In addition, urotropin is recommended to be used in high concentrations reaching 2% (i.e., calculated in hundreds of millimoles per liter).

The closest to the proposed solution in terms of technical nature and the achieved result is a well-known acid corrosion inhibitor containing the condensation product of aniline with capric aldehyde (Turbina V.G., Klyuchnikov N.G. Steel protection against corrosion in hydrochloric acid by condensation products of amines and aldehydes, collection articles "Metal corrosion inhibitors", Central Research Institute of Technology, publishing house "Shipbuilding", 1965, p.124-129). A known inhibitor protects steel better than urotropin. However, the degree of protection for it is not large enough, amounting to 3, 5 and 7 N. hydrochloric acid, respectively 92.07%, 95.50%, 97.29%. For aluminum and indium, corrosion protection is even less effective. Also known inhibitor weakly protects steel from hydrogenation.

The technical task of the present invention is to increase the degree of protection of steel, aluminum and indium from corrosion in sulfuric and hydrochloric acids, as well as to reduce the hydrogenation of steel.

To achieve the technical task, it was proposed to add an inhibitor consisting of four components in sulfuric and hydrochloric acid solutions: the condensation product of amine and aldehyde (which is used as α-oxinaphthalampicillin), 3-isopropylbenzo-2,1,3-thiadiazinon-4-dioxide -2,2,2-heptadecylimidazolinyl acetate and urotropine. These substances are the following structures:

α-oxinaphthalampicillin (hereinafter condensation product)

3-isopropylbenzo-2,1,3-thiadiazinon-4-dioxide-2,2 (hereinafter the derivative of thiadiazinone)

2-heptadecylimidazolinyl acetate (hereinafter imidazoline derivative)

The composition of the proposed inhibitor components are in the following concentrations, wt.%:

condensation product 10.7-8.6 thiadiazinone derivative 21.2-17.1 imidazoline derivative 31.5-22.5 urotropin 36.6-51.8.

First, the condensation product and urotropin (in half the volume of acid) are dissolved in acids. Then, with vigorous stirring, derivatives of thiadiazinone and imidazoline are dissolved in the other half of the volume of the acid, after which both solutions merge with stirring. You can also pre-dissolve the last two components in acetone (5-10 ml), and then add the acetone solution to the second half of the acid volume and mix both halves of the acid solutions. The addition of acetone does not change the protective properties of the inhibitor.

The results of corrosion tests obtained by volumetric and gravimetric methods are shown in table 1 (for the proposed inhibitor) and table 2 (for the known inhibitor). These tables also contain data on the hydrogenation of steel, which was studied on a K-5 twisting machine (the number of revolutions of steel wire samples to the break of the sample was recorded). Some of the research data are given in examples 1-3.

Example 1. In 500 ml of 3 N. H ₂ SO ₄ dissolved the proposed corrosion inhibitor (2.5 g), containing, wt.%:

condensation product 10.7 thiadiazinone derivative 21,2 imidazoline derivative 31.5 urotropin 36.6

A steel sample of 30 × 20 × 1 mm was processed with sandpaper, degreased with acetone, kept for two hours in a desiccator over calcined calcium chloride and then weighed on an analytical balance. All experiments on measuring the corrosion rate were carried out in at least three replicates in a solution of sulfuric acid and in a solution with the addition of an inhibitor at 20 ° C and 90 ° C (respectively, for 48 hours and 0.5 hours). The temperature was maintained using a liquid thermostat with an accuracy of ± 1 ° C. The corrosion rate was calculated from the decrease in the mass of the samples, and the corrosion braking coefficients γ for the inhibitor γ ₂₀ = 47.6 and γ ₉₀ = 250 were determined from them.

From the obtained values of γ, we calculate by the equation

степени защиты Z₂₀=97,9% и Z₉₀=99,6%.

degree of protection Z ₂₀ = 97.9% and Z ₉₀ = 99.6%.

With the introduction of 3 n. sulfuric acid of the individual components of the inhibitor obtained the following values of the coefficients of inhibition:

20 ° C 90 ° C condensation product 1.8 2,4 thiadiazinone derivative 2.0 3,7 imidazoline derivative 2.7 5,0 urotropin 1.4 2.2

The products of the partial braking coefficients are 13.6 at 20 ° C and 97.7 at 90 ° C. These quantities can be considered conditionally theoretical, i.e. obtained under the assumption of the absence of mutual enhancement of the protective action of the components in the mixture. Theoretical values of γ are 3.5 (20 ° С) and 2.56 (90 ° С) times less than the obtained experimental values for a four-component inhibitor. Such a significant superiority of the experimental coefficient of inhibition indicates that the components of the mixture constituting the inhibitor mutually reinforce the effect of each other. The observed synergism of inhibitors is indirectly confirmed by polarization measurements: the cathodic and anodic polarization increase in the presence of an inhibitor 2.5 and 4 times, respectively. Thus, the high efficiency of the proposed inhibitor is due to the synergism of its components. Comparison of the γ values obtained with the known (13.0) and the proposed (47.6) inhibitors for steel, indicates a significant superiority of the latter. Even more significantly, the proposed inhibitor is superior to steel that is known for protection against hydrogenation (degrees of protection, respectively, 36.9 and 6%).

Example 2. In 500 ml of 3 N. HCl was dissolved 2.5 g of the proposed inhibitor with the same content of components as in example 1. In this solution, according to the method described in example 1, experiments were carried out with aluminum, which gave the following results on corrosion inhibition coefficients: at 20 ° С γ = 415.1, at 50 ° C γ = 687.5. Based on the values given, the values of the degree of protection Z ₂₀ = 99.8% and Z ₅₀ = 99.9% were calculated. A comparison of these values with similar indicators for experiments with the known inhibitor Z ₂₀ = 41.9% and Z ₅₀ = 50.5% shows a clear superiority of the proposed inhibitor in protective action for aluminum.

Experiments with individual components of the proposed inhibitor gave the following values of the coefficient of inhibition of corrosion γ:

20 ° C 50 ° C condensation product 3.0 3,7 thiadiazinone derivative 2,4 3,1 imidazoline derivative 4.7 5.5 urotropin 1.9 2,3

The products of the γ values for individual inhibitors are 64.3 at 20 ° C and 145.1 at 50 ° C, which is 6.5 and 4.7 times less than the experimental values, respectively. Therefore, in the case of aluminum, synergism is also observed, which increases the effectiveness of the protective action of the four-component inhibitor.

Example 3. In 500 ml of 5 N. H ₂ SO _{4 was} dissolved 2.5 g of the proposed inhibitor with the same content of components as in examples 1 and 2. In the prepared solution, experiments were carried out with indium according to the same procedure as in examples 1 and 2. The obtained values of the coefficients of corrosion inhibition with the proposed inhibitor of γ ₂₀ = 5.1 and γ ₉₀ = 4.8 allowed us to calculate the degree of protection, which were equal to Z ₂₀ = 80.3% and Z ₉₀ = 79.2%. For a known inhibitor, the degree of protection is significantly lower than 44.9 and 48.3%. The synergy of the components is also manifested for indium, but to a lesser extent than for steel and aluminum.

From the data given in the tables and examples, it is possible to draw a well-founded conclusion that the proposed inhibitor is much more effective than that known both for protection against corrosion of steel, aluminum and indium, and for braking of hydrogenation of steel.

Additional experiments with the PB-5 inhibitor, which is widely used in the practice of protection against acid corrosion of steel, have revealed a significant advantage of the proposed inhibitor over the known one: for the first, the coefficient of inhibition of corrosion is about 60, and for the known - 44. In addition, the known inhibitor coagulates even with a small content salts of iron in the etching solution, while the proposed inhibitor under these conditions is not susceptible to coagulation.

The proposed inhibitor can be recommended for the etching of steel, aluminum and indium, as well as for acid leaching of equipment from these metals.

Table 1 The degree of protection against corrosion of steel, aluminum, indium and from hydrogenation of steel proposed inhibitor No. p / p Metal The concentration of inhibitor components, wt.% Acid, its concentration, equiv / l t, ° C Degree of protection, % condensation product thiadiazinone derivative imidazoline derivative urotropin against corrosion from hydrogenation one 2 3 four 5 6 7 8 9 10 one steel 8.6 17.1 22.5 51.8 H ₂ SO ₄ , 3 twenty 93.8 27.3 2 steel 9.6 19.2 27.0 44,2 H ₂ SO ₄ , 3 twenty 95.2 3 steel 10.7 21,2 31.5 36.6 H ₂ SO ₄ , 3 twenty 97.9 36.9 four steel 8.6 17.1 22.5 51.8 H ₂ SO ₄ , 3 90 97.8 5 steel 9.6 19.2 27.0 44,2 H ₂ SO ₄ , 3 90 98.7 6 steel 10.7 21,2 31.5 36.6 H ₂ SO ₄ , 3 90 99.6 7 steel 8.6 17.1 22.5 51.8 H ₂ SO ₄ , 5 twenty 98.7 39.2 8 steel 9.6 19.2 27.0 44,2 H ₂ SO ₄ , 5 twenty 99,2 9 steel 10.7 21,2 31.5 36.6 H ₂ SO ₄ , 5 twenty 99.6 46.3 10 steel 8.6 17.1 22.5 51.8 H ₂ SO ₄ , 5 90 97.5 eleven steel 9.6 19.2 27.0 44,2 H ₂ SO ₄ , 5 90 99.8 12 steel 10.7 21,2 31.5 36.6 H ₂ SO ₄ , 5 90 99.9 13 steel 8.6 17.1 22.5 51.8 HCl, 3 twenty 99,2 27.0 fourteen steel 9.6 19.2 27.0 44,2 HCl, 3 twenty 99.7 fifteen steel 10.7 21,2 31.5 36.6 HCl, 3 twenty 99.9 35.8 16 steel 8.6 17.1 22.5 51.8 HCl, 3 90 95.0 17 steel 9.6 19.2 27.0 44,2 HCl, 3 90 98.7 eighteen steel 10.7 21,2 31.5 36.6 HCl, 3 90 99.8 19 steel 8.6 17.1 22.5 51.8 HCl, 5 twenty 99.3 29.2 twenty steel 9.6 19.2 27.0 44,2 HCl, 5 twenty 99.8 21 steel 10.7 21,2 31.5 36.6 HCl, 5 twenty 99.9 42.9 22 steel 8.6 17.1 22.5 51.8 HCl, 5 90 95.7 23 steel 9.6 19.2 27.0 44,2 HCl, 5 90 96 24 steel 10.7 21,2 31.5 36.6 HCl, 5 90 99.6 25 steel 8.6 17.1 22.5 51.8 HCl, 7 twenty 97.9 25.7 26 steel 9.6 19.2 27.0 44,2 HCl, 7 twenty 98.9 27 steel 10.7 21,2 31.5 36.6 HCl, 7 twenty 99.9 44.5 28 steel 8.6 17.1 22.5 51.8 HCl, 7 90 95.5 29th steel 9.6 19.2 27.0 44,2 HCl, 7 90 97.1 thirty steel 10.7 21.2 31.5 36.6 HCl, 7 90 98.3 31 aluminum 8.6 17.1 22.5 51.8 H ₂ SO ₄ , 3 twenty 85.3 32 aluminum 9.6 19.2 27.0 44,2 H ₂ SO ₄ , 3 twenty 86.3 33 aluminum 10.7 21,2 31.5 36.6 H ₂ SO ₄ , 3 twenty 88.7 34 aluminum 8.6 17.1 22.5 51.8 H ₂ SO ₄ , 3 fifty 87.9 35 aluminum 9.6 19.2 27.0 44,2 H ₂ SO ₄ , 3 fifty 89.5 36 aluminum 10.7 21,2 31.5 36.6 H ₂ SO ₄ , 3 fifty 91.5 37 aluminum 8.6 17.1 22.5 51.8 H ₂ SO ₄ , 5 twenty 82.0 38 aluminum 9.6 19.2 27.0 44,2 H ₂ SO ₄ , 5 twenty 90.2 39 aluminum 10.7 21,2 31.5 36.6 H ₂ SO ₄ , 5 twenty 92.3 40 aluminum 8.6 17.1 22.5 51.8 H ₂ SO ₄ , 5 fifty 88.5 41 aluminum 9.6 19.2 27.0 44,2 H ₂ SO ₄ , 5 fifty 91.2 42 aluminum 10.7 21,2 31.5 36.6 H ₂ SO ₄ , 5 fifty 92.9 43 aluminum 8.6 17.1 22.5 51.8 HCl, 3 twenty 93.3 44 aluminum 9.6 19.2 27.0 44,2 HCl, 3 twenty 97.1 45 aluminum 10.7 21,2 31.5 36.6 HCl, 3 twenty 99.8 46 aluminum 8.6 17.1 22.5 51.8 HCl, 3 fifty 94.9 47 aluminum 9.6 19.2 27.0 44,2 HCl, 3 fifty 98.7 48 aluminum 10.7 21,2 31.5 36.6 HCl, 3 fifty 99.9 49 aluminum 8.6 17.1 22.5 51.8 HCl, 5 twenty 93.6 fifty aluminum 9.6 19.2 27.0 44,2 HCl, 5 twenty 98.2 51 aluminum 10.7 21,2 31.5 36.6 HCl, 5 twenty 99.3 52 aluminum 8.6 17.1 22.5 51.8 HCl, 5 fifty 95.8 53 aluminum 9.6 19.2 27.0 44,2 HCl, 5 fifty 98.5 54 aluminum 10.7 21,2 31.5 36.6 HCl, 5 fifty 99.9 55 indium 8.6 17.1 22.5 51.8 H ₂ SO ₄ , 3 twenty 63.3 56 indium 9.6 19.2 27.0 44,2 H ₂ SO ₄ , 3 twenty 69.2 57 indium 10.7 21,2 31.5 36.6 H ₂ SO ₄ , 3 twenty 73.9 58 indium 8.6 17.1 22.5 51.8 H ₂ SO ₄ , 3 90 73.8 59 indium 9.6 19.2 27.0 44,2 H ₂ SO ₄ , 3 90 78.7 60 indium 10.7 21,2 31.5 36.6 H ₂ SO ₄ , 3 90 81.5 61 indium 8.6 17.1 22.5 51.8 H ₂ SO ₄ , 5 twenty 77.1 62 indium 9.6 19.2 27.0 44,2 H ₂ SO ₄ , 5 twenty 78.0 63 indium 10.7 21,2 31.5 36.6 H ₂ SO ₄ , 5 twenty 80.3 64 indium 8.6 17.1 22.5 51.8 H ₂ SO ₄ , 5 90 73.1 65 indium 9.6 19.2 27.0 44,2 H ₂ SO ₄ , 5 90 75.8 66 indium 10.7 21.2 31.5 36.6 H ₂ SO ₄ , 5 90 79.2 67 indium 8.6 17.1 22.5 51.8 HCl, 3 twenty 71 68 indium 9.6 19.2 27.0 44,2 HCl, 3 twenty 75,5 69 indium 10.7 21,2 31.5 36.6 HCl, 3 twenty 76.9 70 indium 8.6 17.1 22.5 51.8 HCl, 3 90 69.2 71 indium 9.6 19.2 27.0 44,2 HCl, 3 90 73.3 72 indium 10.7 21,2 31.5 36.6 HCl, 3 90 79.1 73 indium 8.6 17.1 22.5 51.8 HCl, 5 twenty 75.1 74 indium 9.6 19.2 27.0 44,2 HCl, 5 twenty 77.1 75 indium 10.7 21,2 31.5 36.6 HCl, 5 twenty 79.0 76 indium 8.6 17.1 22.5 51.8 HCl, 5 90 68.7 77 indium 9.6 19.2 27.0 44,2 HCl, 5 90 71.5 78 indium 10.7 21,2 31.5 36.6 HCl, 5 90 78.9

table 2 Inhibition of corrosion of steel, aluminum and indium and inhibition of hydrogenation of steel in sulfuric and hydrochloric acids by a known inhibitor (aniline condensation product with capric aldehyde), the inhibitor concentration is 5 g / l No. Metal Acid, its concentration, equiv / l t, ° C Degree of protection, % Against corrosion From hydrogenation one 2 3 four 5 6 one steel HCl, 3 twenty 92.1 2 2 steel HCl, 5 twenty 95.5 3 3 steel HCl, 7 twenty 97.3 four four steel HCl, 3 90 94.3 5 steel HCl, 5 90 93.1 6 steel HCl, 7 90 96.0 7 steel H ₂ SO ₄ , 3 twenty 92.3 6 8 steel H ₂ SO ₄ , 5 twenty 93.1 8 9 steel H ₂ SO ₄ , 3 90 90.2 10 steel H ₂ SO ₄ , 5 90 93.7 eleven aluminum HCl, 3 twenty 41.9 12 aluminum HCl, 5 twenty 53.8 13 aluminum HCl, 3 fifty 50,5 fourteen aluminum HCl, 5 fifty 63.3 fifteen aluminum H ₂ SO ₄ , 3 twenty 65.9 16 aluminum H ₂ SO ₄ , 5 twenty 62,2 17 aluminum H ₂ SO ₄ , 3 fifty 46.6 eighteen aluminum H ₂ SO ₄ , 5 fifty 52.0 19 indium HCl, 3 twenty 39.0 twenty indium HCl, 5 twenty 36.3 21 indium HCl, 3 90 42.9 22 indium HCl, 5 90 40.5 23 indium H ₂ SO ₄ , 3 twenty 34.5 24 indium H ₂ SO ₄ , 5 twenty 44.9 25 indium H ₂ SO ₄ , 3 90 44.8 26 indium H ₂ SO ₄ , 5 90 48.3

Claims (1)

Corrosion inhibitor of metals in sulfuric and hydrochloric acids containing the product of the condensation of an amine with an aldehyde, characterized in that it further comprises 3-isopropylbenzo-2,1,3-thiadiazinon-4-dioxide-2,2, 2-heptadecylimidazolinyl acetate and urotropine, and as a condensation product of α-oxinaphthalampicillin, in the following ratio of components, wt.%:
α-oxinaphthalampicillin 10.7-8.6 3-isopropylbenzo-2,1,3-thiadiazinon-4-dioxide-2,2 21.2-17.1 2-heptadecylimidazolinyl acetate 31.5-22.5 urotropin 36.6-51.8