RU2488647C1 - Method of inhibiting metal corrosion - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: method involves adding an inhibitor to aqueous media, the inhibitor being 2,6-di-(1'-methyl-2'-butenyl)-4-methoxyaniline. The inhibitor has concentration of 50-200 mg/l in aqueous media which differ on degree of mineralisation.

EFFECT: high degree of protecting metals from corrosion while reducing concentration of the inhibitor.

5 cl, 1 tbl, 3 ex

Description

The invention relates to a method of protecting metals from corrosion in mineralized aqueous media by inhibitors and can be used to protect equipment and pipelines in contact with wastewater in the oil industry from corrosion.

Known methods of protecting steel from corrosion using inhibitors based on aromatic and heterocyclic compounds: the condensation product of benzylamine with urotropine (TU 6-02-1192-79. Corrosion inhibitor BA-6. Introduction. 01.01.80. 13 C.); a mixture of alkylbenzylpyridine and a cyclic amine (TU 6-46893387-34-90. Corrosion inhibitor KI-1. Introduced 01.07.90. 12 sec.); a mixture of derivatives of toluene diisocyanates (TU 6-03-31-81. Corrosion inhibitor TDA. Int. 01.02.82. 13 sec.); derivatives of alkipyridinium chlorides (TU 6-01-530-70. Catania corrosion inhibitor B-300. Introduction. 01.01.71. 13 p.); Quaternary pyridinium salt (TU 6-01-11-15-72. Corrosion inhibitor KPI-3. Introduced 01.02.73. 14 sec.).

However, these inhibitors do not have a high protection efficiency in mineralized aqueous media.

The closest analogue in structure and effectiveness is the PB-5 corrosion inhibitor, which is a condensation product of aniline and urotropin (TU 6-01-28-92. The PB-5 corrosion inhibitor. Introduction. 01.01.93. 11 pp.).

The disadvantage of this inhibitor is low efficiency in mineralized aqueous media.

The objective of the present invention is to provide an effective method of protecting metals from corrosion in aqueous media of varying degrees of mineralization, providing a high degree of protection of metals from corrosion while reducing the concentration of inhibitor.

The solution of this problem is achieved by the fact that the method of inhibiting metal corrosion involves adding a corrosion inhibitor to aqueous media, which is used 2,6-di- (1'-methyl-2′-butenyl) -4-mstoxyaniline.

The specified corrosion inhibitor is used with a concentration of 50-200 mg / l in aqueous media, varying in degree of mineralization. Aqueous media are water-oil emulsions with a hydrogen sulfide content of 100-150 mg / l.

2,6-di- (1′-methyl-2′-butenyl) -4-methoxyaniline inhibitor of the formula

prepared by direct alkenylation of aniline with 4-chloro-2-pentene in the presence of aluminum chloride.

The protective effect of 2,6-di- (1′-methyl-2′-butenyl) -4-methoxyaniline as a metal corrosion inhibitor in mineralized aqueous media was tested under laboratory conditions by the gravimetric method in accordance with GOST 9506-89 “Corrosion inhibitors” .

As working media, a model of wastewater (hereinafter - MSV) of the composition was used, g / l: NaCl - 111.5; CaCl ₂ · 6H ₂ O — 10.8; CaSO ₄ · 2H ₂ O - 0.3; MgCl ₂ · 6H ₂ O - 6.0; and oil in a ratio of 80:20. The hydrogen sulfide content in the MSV was 100-150 mg / L. Samples of steel grade 3 (GOST 380-90) were used as witness samples.

Fat-free and dried to constant weight samples of steel 3 were placed in a working environment for 6 hours at 20 ° C with the addition of the proposed inhibitor and without it. After the aging time, the samples were thoroughly washed in a stream of water, immersed for 5-10 minutes in an alkali solution and again washed with running water and dried to constant weight. Next, the samples were weighed to the nearest 0.0002 g.

The corrosion rate (p), the degree of corrosion protection of steel (Z) was determined in accordance with formulas (1) and (2)

$$P=\frac{m_{\mathrm{one}}-m_2}{S\cdot t},(\mathrm{one})$$

where m ₁ -m ₂ - change in mass, g;

S is the sample area, m ² ;

t is the test time, h

$$P=\frac{p_{\mathrm{one}}-p_2}{p_{\mathrm{one}}}\mathrm{one\; hundred,}(2)$$

where p ₁ - corrosion rate in a medium without an inhibitor, g / m ² h;

p ₂ - corrosion rate in an inhibited medium, g / m ²

The essence of the claimed technical solution is confirmed by examples of specific performance.

Example 1

Synthesis of 2,6-di- (1'-methyl-2′-butenyl) -4-methoxyaniline.

2,6-di- (1′-methyl-2′-butenyl) -4-methoxyaniline was prepared by reacting methoxyaniline with 4-chloro-2-pentene at a temperature of 150 ° C in the presence of aluminum chloride AlCl ₃ . The compound is a viscous brown mass.

61.58 g (0.5 mol) of 4-methoxyaniline and 10.45 g (0.1 mol) of 4-chloro-2-pentene were heated at 150 ° C for 6 hours. After cooling, a KOH solution was added to the reaction mixture, stirred for 10 min, the organic layer was separated, dried over KOH. After distillation in vacuo, 1.4 g (10.8%) of the product are obtained in the form of a viscous dark brown mass. T.kip. 143 ° C (3 mmHg).

Found (%): C 78.70; H, 9.70; N, 5.40; C ₁₇ H ₂₅ NO.

Calculated (%): C 78.70; H 9.71; N, 5.40.

IR spectrum (v, cm ^-1 ): 3433, 3367 (NH ₂ ).

¹ H NMR Spectrum (CDCl ₃ , δ / ppm): 1.28 (d, 6H, 2CH ₃ , J = 6.86 Hz); 1.69 (d, 6H, 2CH ₃ , J 5.69 Hz); 3.46 (m, 2H, 2CH); 3.49 (br s, 2H, NH ₂ ); 3.77 (s, 3H, OCH ₃ ); 5.52-5.56 (m, 4H, CH = CH); 6.65 (s, 2H, Ar-H). ¹³ C NMR Spectrum: (CDCl ₃ , δ / ppm): 17.8 (2CH ₃ ); 19.7 (2CH ₃ ); 30.0 (2CH); 55.5 (OCH ₃ ); 110.4 (C ² , C ^{2 ′ ′} ); 134.8 (C ³ , C ⁵ ); 132.3 (C ^{3 ′} , C ^{3 ′ ′} ); 124.3, 135.6, 152.5 (C-arom.).

Example 2

Testing the effectiveness of the protective effect of 2,6-di- (1′-methyl-2′-butenyl) -4-methoxyaniline as an inhibitor of steel corrosion was carried out according to the method described above.

In a mineralized water-oil emulsion (water: oil ratio of 80:20, respectively) containing 100-150 mg / l of hydrogen sulfide, the corrosion rate without inhibitor is 0.61 g / m ² h, and in the presence of 200 mg / l 2, 6-di- (1′-methyl-2′-butenyl) -4-methoxyaniline (hereinafter reagent) - 0.027 g / m ² h. The degree of protection against corrosion under these conditions is 95.6%. The table shows the rest of the test results of 2,6-di- (1′-methyl-2′-butenyl) -4-methoxyaniline as an inhibitor of steel corrosion.

Example 3

Tests of the effectiveness of the corrosion protection of the prototype (PB-5 inhibitor) were carried out analogously to example 2. The corrosion rate in the mineralized oil-water emulsion is 0.61 g / m ² h without reagent and 0.366 g / m ² h in the presence of 200 mg / l of the prototype . The degree of protection under these conditions is 40.0%.

The test results shown in the table indicate the high efficiency of the proposed metal corrosion inhibitor in mineralized aqueous media, representing water-in-oil emulsions with a hydrogen sulfide content of 100-150 mg / l. The highest efficiency is achieved when the inhibitor concentration is from 50 to 200 mg / l (degree of protection 93.8-95.6). With an increase in the inhibitor concentration above 200 mg / L, the degree of protection does not change significantly, and with a decrease in its concentration below 50 mg / L, a sharp decrease in the degree of protection is observed. In the case of the prototype at a concentration of 200 mg / l, the corrosion rate is 0.366 g / m ² h and the degree of protection is 40.0%.

Table Test results of 2,6-di- (1′-methyl-2′-butenyl) -4-methoxyaniline as a corrosion inhibitor No. p / p Dosage, mg / l Corrosion rate, g / m ² h Degree of protection, % The control - 0.61 - 2 200,0 0,027 95.6 3 prototype 200,0 0.366 40,0 four 100.0 0,030 95.1 5 50,0 0,038 93.8 6 25.0 0.058 90.5 7 300,0 0,0268 95.61

The advantages of the proposed metal corrosion inhibitor compared with the prototype are as follows:

a high degree of corrosion protection with 2,6-di- (1'-methyl-2′-butenyl) -4-methoxyaniline (93.8-95.6%) but compared with the prototype (40.0%);

- a decrease in the corrosion rate of steel in the presence of 2,6-di- (1′-methyl-2′-butenyl) -4-methoxyaniline by 10–20 times or more, and in the presence of the prototype by 1.67 times;

- effective dosages of the proposed inhibitor are 50-200 mg / l (degree of protection 93.8-95.6%), and in the prototype, even at dosages of 200 mg / l, the degree of protection does not exceed 40.0%.

The results obtained allow us to conclude that the proposed method for protecting metals from corrosion in aqueous media of various degrees of mineralization, represented by water-oil emulsions, which can be used in the oil industry, is highly effective.

Claims (5)

1. A method of inhibiting metal corrosion, comprising adding an inhibitor to aqueous media, characterized in that 2,6-di- (1′-methyl-2′-butenyl) -4-methoxyaniline is used as the inhibitor. 2. The method according to claim 1, characterized in that 2,6-di- (1′-methyl-2′-butenyl) -4-methoxyaniline is used with a concentration of 50-200 mg / L. 3. The method according to claim 1, characterized in that the inhibitor is introduced into aqueous media that vary in degree of mineralization. 4. The method according to claim 1, characterized in that the aqueous medium is water-in-oil emulsions. 5. The method according to claim 1, characterized in that in aqueous media the content of hydrogen sulfide is 100-150 mg / L.