RU2456374C1 - Inhibitor of metal corrosion in sulphuric and hydrochloric acids - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: inhibitor contains, wt % α-oxynaphtal-2-amino-4-bromophenol 23.0-17.1; ethoxy-3-trichloromethyl-1,2,4-thiadiazol 19.2-26.0, cetyl dimethyl benzyl ammonium bromide 13.3-24.6; urotropine 44.5-32.3.

EFFECT: inhibitor reduces corrosion of steel, aluminium and zinc, and reduces hydrogenation of steel.

2 tbl, 2 ex

Description

The invention relates to the protection of metals from acid corrosion and can be used for pickling metals and acid cleaning equipment.

It is known to use urotropin to reduce the rate of steel corrosion in hydrochloric and sulfuric acids (Altsybeeva A.I., Levin S.E. Metal corrosion inhibitors: - L., Chemistry, 1968, 28-29 pp.). However, when corrosion is slowed in the hydrochloric and sulfuric acids of steel and other metals (for example, aluminum and zinc), 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).

According to the technical nature and the results obtained, the closest to the proposed inhibitor is a known inhibitor, which is a condensation product of aniline and capric aldehyde with (V.G. Turbina, N.G. Klyuchnikov. Protection against steel corrosion in hydrochloric acid by condensation products of amines and aldehydes: in the collection of articles "Metal corrosion inhibitors", Central Research Institute of Shipbuilding Technology. Shipbuilding, 1965, p.124-129).

The known inhibitor protects steel to a greater extent than urotropin, but the degree of protection is still not large enough (92.07; 95.50; 97.29%, respectively, in 3.5 and 7 N. hydrochloric acid). The effectiveness of the known inhibitor for aluminum and zinc is even lower. It very weakly protects steel from hydrogenation.

The technical task of the present invention is to increase the efficiency of protection against acid corrosion of steel, aluminum and zinc, as well as reducing the hydrogenation of steel.

To achieve this technical problem, it is proposed to introduce an inhibitor into solutions of sulfuric and hydrochloric acids, which is a mixture of components that give a synergistic effect. As such components were taken: the condensation product of amine and aldehyde (azomethine), α-oxinaphthal-2-amino-4-bromophenol,

ethoxy-3-trichloromethyl-1,2,4-triadiazole (thiadiazole derivative)

,

,

cetyldimethylbenzylammonium bromide (tetra-substituted ammonium derivative),

and urotropin.

These components are included in the proposed inhibitor in the following concentrations, wt.%:

α-oxinaphthal-2-amino-4-bromophenol 23.0-17.1 ethoxy-3-trichloromethyl-1,2,4-thiadiazole 19.2-26.0 cetyldimethylbenzylammonium bromide 13.3-24.6 urotropin 44.5-32.3

The components are added to acid solutions with vigorous stirring. The last added thiadiazole derivative, a portion of which is previously dissolved in several milliliters of ethyl alcohol.

The results of corrosion tests of samples of steel, aluminum and zinc in acid solutions with the proposed inhibitor are collected in table 1 and examples. For a known inhibitor, the data are contained in table 2 and the same examples. The experimental data were obtained both by the gravimetric method (by the decrease in the mass of the samples) and by the volumetric method (by the volume of hydrogen evolved). Hydrogenation for steel samples was measured by counting the number of revolutions before breaking the latter on a K-5 twisting machine, samples that were not etched in acids, and etched in the absence and presence of inhibitors in acid solutions were used. Degrees of protection against both corrosion and hydrogenation are given in tables and examples.

Example I. Experiments with steel samples were carried out in 500 ml of 3 N. sulfuric acid at 20 ± 1 and 90 ± 1 ° C (the temperature was maintained using a liquid thermostat). The inhibitor was taken with the following concentrations of components: azomethine 17.1, thiadiazole derivative 26.0, 4-substituted ammonium derivative 24.0 and urotropin 32.3 wt.%. The experiments were carried out in at least three replicates with samples measuring 50 × 25 × 1 mm. The samples were treated with sandpaper, degreased with acetone, kept in a desiccator for 2 hours over calcined calcium chloride and weighed on an analytical balance. After the experiment, the samples were washed with water, wiped with a paper towel, kept in a desiccator and weighed again. The corrosion rate of steel was determined from the found mass loss of the samples, and then the corrosion braking coefficients were calculated, which amounted to 71.4 (for 20 ° C) and 250 (for 90 ° C, respectively). The degrees of protection z were calculated from these values: z ₁ = 98.6% and z ₂ = 99.6%.

In another series of experiments, the braking coefficients of steel in the same solutions were determined, but in the presence of only one component of the inhibitor

azomethine 2.0

thiadiazole derivative 2,4

4-substituted ammonium derivative 3.4

urotropin 1.8

The product of the obtained values is 27.6, i.e. more than 2.5 times less than the experimental value. Thus, the components of the proposed inhibitor significantly enhance the action of each other, which indicates the presence of a synergistic effect that sharply reduces the corrosion rate of steel. Indirect confirmation of this conclusion is provided by polarization curves, which show an increase in cathodic polarization by 120 mV, and the anodic one by 30 mV, while in the presence of individual components the polarization is 5-20 mV.

In the case of using a known inhibitor, the reduction in corrosion rate is only 92.3%, and for hydrogenation only 6%.

Thus, the proposed inhibitor significantly exceeds the known in both respects (for the suppression of corrosion and hydrogenation).

Example II The proposed and known inhibitors are used to slow corrosion of aluminum in 5 N. Hcl at 20 and 50 ° C at the same inhibitor concentrations as in Example I. Inhibition coefficients were 16.6 (20 ° C) and 100 (50 ° C), and the calculated degrees of protection were 94 and 99%.

A well-known inhibitor under the same conditions protects aluminum much weaker: 53.8 and 63.3%, respectively.

The indices (braking factors) for the individual components of the inhibitor were (50 ° C) the following values

azomethine 5.7

thiadiazole derivative 1.7

4-substituted ammonium derivative 2.9

urotropin 2

Their product 57.1 is much smaller than the value of the experimental drag coefficient of 100. Thus, synergism of the action of the components is also observed for aluminum.

Example III For zinc, the experiments were carried out in 3 N. hydrochloric acid solution with the same concentrations of inhibitor components as in examples I and II. The corrosion inhibition coefficient is 333 (for the proposed inhibitor) and 76.7 (for the known). Therefore, here a very significant superiority of the proposed inhibitor over known as the degrees of protection of 100 and 23.3, and braking factors.

From the above data (examples I-III and tables 1 and 2) it should be concluded that the proposed inhibitor is much more effective for corrosion processes of steel, aluminum and zinc in sulfuric and hydrochloric acids, as well as for hydrogenation of steel.

In additional experiments, it was shown that the proposed inhibitor was more effective in an acidic environment than PB-5, which is widely used to protect steel: if for the latter, the braking coefficients are 10-20, then for the proposed one it is 5 times greater. In addition, the proposed inhibitor is resistant to coagulation by the action of iron salts than is known.

It was also established that in the case of the proposed inhibitor, its components significantly enhance the effect of each other.

The proposed inhibitor is recommended for acid etching of steel, aluminum and zinc, as well as for acid cleaning equipment and flushing wells in gas and oil production.

Table 1 The degree of protection against corrosion of steel, aluminum, zinc and from hydrogenation of steel by the proposed inhibitor No. p / p Metal The concentration of inhibitor components, wt.% Acid, its concentration, equiv / l t ° C Degree of protection, % azomethine thiadiazole derivative 4-substituted ammonium derivative urotropin against corrosion from hydrogenation one 2 3 four 5 6 7 8 9 10 one steel 23.0 19.2 13.3 44.5 H ₂ SO ₄ , 3 twenty 96.9 24.9 2 - // - 20.3 22.9 18.7 38.1 - // - 97.1 3 - // - 17.1 26.0 24.0 32.3 - // - 98.6 37.5 four - // - 23.0 19.2 13.3 44.5 H ₂ SO ₄ , 3 90 94.9 5 - // - 20.3 22.9 18.7 38.1 - // - 97.7 6 - // - 17.1 26.0 24.0 32.3 - // - 99.6 7 - // - 23.0 19.2 13.3 44.5 H ₂ SO ₄ , 5 twenty 96.5 24.5 8 - // - 20.3 22.9 18.7 38.1 - // - 97.3 9 - // - 17.1 26.0 24.0 32.3 - // - 99.5 47.5 10 - // - 23.0 19.2 13.3 44.5 - // - 90 98.0 eleven - // - 20.3 22.9 18.7 38.1 - // - 99,2 12 - // - 17.1 26.0 24.0 32.3 - // - 99.6 13 - // - 23.0 19.2 13.3 44.5 Hcl, 3 twenty 99,2 29.1 fourteen - // - 20.3 22.9 18.7 38.1 - // - 99.7 fifteen - // - 17.1 26.0 24.0 32.3 - // - 99.9 37.0 16 - // - 23.0 19.2 13.3 44.5 - // - 90 94.5 17 - // - 20.3 22.9 18.7 38.1 - // - 98.8 eighteen - // - 17.1 26.0 24.0 32.3 - // - 99.7 19 - // - 23.0 19.2 13.3 44.5 Hcl, 5 twenty 98.5 27.1 twenty - // - 20.3 22.9 18.7 38.1 - // - 98.7

one 2 3 four 5 6 7 8 9 10 21 steel 17.1 26.0 24.0 32.3 Hcl, 5 twenty 99.9 38,0 22 - // - 23.0 19.2 13.3 44.5 - // - 90 96.0 23 - // - 20.3 22.9 18.7 38.1 - // - 96.9 24 - // - 17.1 26.0 24.0 32.3 - // - 97.8 25 - // - 23.0 19.2 13.3 44.5 Hcl, 7 twenty 98.3 26 - // - 20.3 22.9 18.7 38.1 - // - 99,2 27 - // - 17.1 26.0 24.0 32.3 - // - 99.7 28 - // - 23.0 19.2 13.3 44.5 - // - 90 96.7 29th - // - 20.3 22.9 18.7 38.1 - // - 98.6 thirty aluminum 17.1 26.0 24.0 32.3 - // - 99.6 31 - // - 23.0 19.2 13.3 44.5 H ₂ SO ₄ , 3 twenty 85.1 32 - // - 20.3 22.9 18.7 38.1 - // - 86.5 33 - // - 17.1 26.0 24.0 32.3 - // - 88.3 34 - // - 23.0 19.2 13.3 44.5 - // - fifty 87.7 35 - // - 20.3 22.9 18.7 38.1 - // - 89.2 36 - // - 17.1 26.0 24.0 32.3 - // - 91.3 37 - // - 23.0 19.2 13.3 44.5 - // - twenty 81.7 38 - // - 20.3 22.9 18.7 38.1 - // - 90.2 39 - // - 17.1 26.0 24.0 32.3 - // - 90.5 40 - // - 23.0 19.2 13.3 44.5 - // - fifty 88.0 41 - // - 20.3 22.9 18.7 38.1 - // - 91.3 42 - // - 17.1 26.0 24.0 32.3 - // - 92.5 43 - // - 23.0 19.2 13.3 44.5 Hcl, 3 twenty 92.9 44 - // - 20.3 22.9 18.7 38.1 - // - 96.9 45 - // - 17.1 26.0 24.0 32.3 - // - 99.8 46 - // - 23.0 19.2 13.3 44.5 - // - fifty 94.5 47 - // - 20.3 22.9 18.7 38.1 - // - 98.3

one 2 3 four 5 6 7 8 9 10 48 aluminum 17.1 26.0 24.0 32.3 Hcl, 5 90 99.8 49 - // - 23.0 19.2 13.3 44.5 - // - twenty 94.0 fifty - // - 20.3 22.9 18.7 38.1 - // - 98.9 51 - // - 17.1 26.0 24.0 32.3 - // - 99.0 52 - // - 23.0 19.2 13.3 44.5 - // - fifty 94.9 53 - // - 20.3 22.9 18.7 38.1 - // - 98.0 54 - // - 17.1 26.0 24.0 32.3 - // - 99.9 55 zinc 23.0 19.2 13.3 44.5 H ₂ SO ₄ , 3 twenty 97.8 56 - // - 20.3 22.9 18.7 38.1 - // - one hundred 57 - // - 17.1 26.0 24.0 32.3 - // - one hundred 58 - // - 23.0 19.2 13.3 44.5 H ₂ SO ₄ , 3 twenty 93.3 59 - // - 20.3 22.9 18.7 38.1 - // - 98.9 60 - // - 17.1 26.0 24.0 32.3 - // - one hundred 61 - // - 23.0 19.2 13.3 44.5 H ₂ SO ₄ , 1 90 83.5 62 - // - 20.3 22.9 18.7 38.1 - // - 87.9 63 - // - 17.1 26.0 24.0 32.3 - // - 90.9 64 - // - 23.0 19.2 13.3 44.5 Hcl, 1 twenty 96.0 65 - // - 20.3 22.9 18.7 38.1 - // - 99.8 66 - // - 17.1 26.0 24.0 32.3 - // - one hundred 67 - // - 23.0 19.2 13.3 44.5 Hcl, 3 94.1 68 - // - 20.3 22.9 18.7 38.1 - // - 96.9 69 - // - 17.1 26.0 24.0 32.3 - // - 99.7 70 - // - 23.0 19.2 13.3 44.5 Hcl, 1 90 79.2 71 - // - 20.3 22.9 18.7 38.1 - // - 83.0 72 - // - 17.1 26.0 24.0 32.3 - // - 87.3

table 2 The inhibition of corrosion of steel, aluminum and zinc in HCl and H ₂ SO ₄ , as well as the deceleration of hydrogenation became a known inhibitor (the product of the condensation of aniline with capric aldehyde, 5 g / l) No. p / p Metal Acid and its concentration, equiv / l t, ° C Degree of protection, % against corrosion from hydrogenation one 2 3 four 5 one steel H ₂ SO ₄ , 3 twenty 92.3 6 2 - // - H ₂ SO ₄ , 5 - // - 93.1 8 3 - // - H ₂ SO ₄ , 3 90 90.2 four - // - H ₂ SO ₄ , 5 - // - 93.7 5 - // - Hcl, 3 twenty 92.1 2 6 - // - Hcl, 5 - // - 95.5 3 7 - // - Hcl, 7 97.3 four 8 - // - Hcl, 3 90 94.3 9 - // - Hcl, 5 95.1 10 - // - Hcl, 7 96.0 eleven aluminum H ₂ SO ₄ , 3 twenty 65.9 12 - // - H ₂ SO ₄ , 5 65,2 13 - // - H ₂ SO ₄ , 3 fifty 46.6 fourteen - // - H ₂ SO ₄ , 5 52.0 fifteen - // - Hcl, 3 twenty 41.9 16 - // - Hcl, 5 53.8 17 - // - Hcl, 3 fifty 50,5 eighteen - // - Hcl, 3 63.3 19 zinc H ₂ SO ₄ , 1 twenty 37.5 twenty - // - H ₂ SO ₄ , 3 41.9 21 - // - H ₂ SO ₄ , 1 90 30.6 22 - // - HCl, 1 twenty 25.8 23 - // - Hcl, 3 23.3 24 - // - Hcl, 1 90 20.9

Claims (1)

Corrosion inhibitor of metals in sulfuric and hydrochloric acids, containing the product of the condensation of amine and aldehyde, characterized in that it further comprises ethoxy-3-trichloromethyl-1,2,4-thiadiazole, cetyl dimethylbenzylammonium bromide and urotropine, and α-oxynaphthal as a condensation product -2-amino-4-bromophenol at the following concentrations of components, wt.%:
α-oxinaphthal-2-amino-4-bromophenol 23.0-17.1 ethoxy-3-trichloromethyl-1,2,4-thiadiazole 19.2-26.0 cetyldimethylbenzylammonium bromide 13.3-24.6 urotropin 44.5-32.3