RU2354752C2 - Hydrogen sulphide corrosion steel protection technique - Google Patents

Abstract

FIELD: chemistry; metallurgy.

SUBSTANCE: invention refers to corrosion metal protection by using inhibitors in mineralised mediums of hydrogen sulphide to be used in oil industry. The method involves addition of 2,4,6-three-(11-methyl-21-butenyl)aniline concentrated 25-200 mg/l in mineralised mediums of hydrogen sulphide.

EFFECT: reduced steel corrosion rate.

1 tbl, 3 ex

Description

The invention relates to a method for protecting metals from corrosion in mineralized environments by inhibitors and can be used in corrosion protection of equipment in the oil industry in contact with waste water and emulsions containing hydrogen sulfide.

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 S.); a mixture of alkylbenzylpyridine and a cyclic amine (TU 6-46893387-34-90. Corrosion inhibitor KI-1. Introduced 01.07.90.12 p.); a mixture of derivatives of toluene diisocyanates (TU 6-03-31-81. Corrosion inhibitor TDA. Introduced 01.02.82.13 p.); derivatives of alkipyridinium chlorides (TU 6-01-530-70. Corrosion inhibitor Katapin B-300. Introduction. 01.01.71.13 s.); Quaternary pyridinium salt (TU 6-01-11-15-72. Corrosion inhibitor KPI-3. Introduced 01.02.73.14 p.).

However, these inhibitors do not have high protection efficiency in mineralized environments containing hydrogen sulfide.

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. PB-5 corrosion inhibitor. Introduced 01.01.93.11 p.) The disadvantage of this inhibitor is its low effectiveness in hydrogen sulfide-containing environments.

The claimed technical solution is aimed at increasing the efficiency of steel protection against corrosion in mineralized environments containing hydrogen sulfide.

The claimed technical solution proposes a method for protecting steel from hydrogen sulfide corrosion in mineralized environments, including adding 2,4,6-tri- (1 ¹ -methyl-2 ¹ -butenyl) aniline to a mineralized medium containing 25-200 mg / l 2,4,6-tri- (1 ¹ -methyl-2 ¹ -butenyl) aniline is obtained by direct alkenylation of aniline with piperylene in the presence of aluminum chloride (Abdrakhmanov I.B. Kleisen amino rearrangement and conversion of ortho-alkenylarylamines. - Dis .... Doctrine Chemistry. - Ufa: Ural Scientific Center, Institute of Chemistry, Academy of Sciences of the USSR, 1989)

Tests of the protective effect of 2,4,6-tri- (1 ^1- methyl-2 ^1- butenyl) aniline as an inhibitor of steel in mineralized media containing hydrogen sulfide were carried out under laboratory conditions by the gravimetric method.

As working media used models of mineralized water (MMW) composition, g / l: NaCl - 111.5; CaCl ₂ · 6H ₂ O — 10.8; MgCl ₂ · 2H ₂ O — 17.0; CaSO ₄ · 2H ₂ O - 0.3. The content of H ₂ S was 900-1500 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)

where m ₁ -m ₂ - change in mass, g;

S is the sample area, m ² ;

t is the test time, h

where p ₁ is the 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 2,4,6-tri- (1 ¹ -methyl-2 ¹ -butenyl) aniline.

To 0.5 moles of aniline in a solution of 50 ml of benzene, 2.5 moles of piperylene and 0.9 moles of aluminum chloride were added. The resulting mixture was thermostated at a temperature of 130 ° C for 5 hours. Received 60 g (99%) of 2,4,6-tri- (1 ¹ -methyl-2 ¹ -butenyl) aniline - an oily liquid with so on. 137 ° C.

Found,%: C 84.96; H 9.87; N, 4.52; C ₂₁ H ₃₁ N.

Calculated: C 84.85; H 10.43; N 4.71.

IR: 980, 1680, 3320, 3410.

H NMR spectrum, (CDCl, ppm, 1, Hz): 1.25 d (9H, 3CH ₃ ); 1.58 d (9H, 3CH ₃ ); 3.23 m (3H, 3CH); 3.42 s (2H, NH ₂ ); 5.38 m (6H, 3CH = CH); 6.58 s (2H, Ar).

Example 2

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

In an MMB containing 1500 mg / L H ₂ S, the corrosion rate without an inhibitor is 1.1 g / m ² h, and in the presence of 200 mg / L 2-, 4-, 6-tri- (1 ¹ -methyl-2 ^1- butenyl) aniline (hereinafter referred to as reagent) - 0.055 g / m ² h.

The degree of corrosion protection under these conditions is 95.0%.

Example 3

Tests of the effectiveness of the corrosion protection of the prototype (inhibitor PB-5) was carried out analogously to example 2.

The corrosion rate of steel in the MMW with a H ₂ S content of 1500 mg / l is 1.1 g / m ² h without a reagent and 0.56 g / m ² h in the presence of 200 mg / l of the prototype. The degree of protection under these conditions is 49.1%.

The table shows the rest of the test examples of 2,4,6-tri- (1 ^1- methyl-2 ^1- butenyl) aniline as an inhibitor of steel corrosion.

The test results shown in the table indicate the high efficiency of the proposed corrosion inhibitor of steel in mineralized environments containing hydrogen sulfide. The highest efficiency is achieved with an inhibitor concentration of 25 to 200 mg / L. With an increase in inhibitor concentration above 200 mg / L, the degree of protection does not change significantly, and with a decrease in its concentration below 25 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 0.53-0.61 g / m ² h and the degree of protection is 32.1-49.1%.

The advantages of the proposed corrosion inhibitor of steel in comparison with the prototype are as follows.

1. A high degree of corrosion protection of 2,4,6-tri- (1 ^1- methyl-2 ^1- butenyl) aniline (84.0-95.0%) compared with the prototype (32.1-49.1% )

2. The decrease in the corrosion rate of steel in the presence of 2,4,6-tri- (1 ^1- methyl-2 ¹ -butenyl) aniline is 6-20 times, and in the presence of the prototype - 1.5-1.9 times.

3. Effective dosages of the proposed inhibitor are 25-200 mg / l (degree of protection 84.0-95.0%), and in the prototype, even at dosages of 200 mg / l, the degree of protection does not exceed 49.1%.

The results obtained allow us to conclude that the proposed method for protecting steel from corrosion in mineralized environments containing hydrogen sulfide, which can be used in the oil industry, is highly effective.

Claims (1)

A method of protecting steel from hydrogen sulfide corrosion, including the addition of 2,4,6-tri- (1 ^1- methyl-2 ^1- butenyl) aniline to a mineralized medium containing hydrogen sulfide at a concentration of 25-200 mg / l.