RU2543018C1 - Method of protecting steel from hydrogen sulphide corrosion - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: method includes adding, to a mineralised medium containing hydrogen sulphide, 1.3-diamyl-5-aminobenzoyl-6-methyluracil in concentration of 25-200 mg/l.

EFFECT: lower corrosion rate of steel.

1 tbl

Description

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

Known methods for protecting steel from corrosion in acidic environments containing hydrogen sulfide using inhibitors based on nitrogen-containing heterocyclic compounds, for example, catapines, which are alkylbenzylpyridinium chlorides that differ in the number of carbon atoms in the alkyl chain. The following brands of catapines are known: A, K, B-300, BPV, EPV (TU 6-01-530-70), condensation products of benzylamine with urotropine. The KPI-3 corrosion inhibitor is a quaternary pyridinium salt (TU 6-01-11-15-72). The corrosion inhibitor BA-6 is a mixture of alkylbenzylpyridine and a cyclic amine according to TU 6-46893387-34-90. Corrosion inhibitor KI-1 - a mixture of 25% catapine B-300, 25% urotropine and 50% water.

However, these inhibitors do not have a sufficiently high protection efficiency in hydrogen sulfide environments.

A known analogue is the inhibitor Penazolin 10-16, which is a mixture of imidazolines and amides of fatty acids obtained by condensation of polyethylene polyamines with high molecular weight fatty acids [Ivanov ES Metal corrosion inhibitors in acidic environments. M .: Metallurgy, 1986, p.150-151]. The disadvantage of this inhibitor is its low efficiency in hydrogen sulfide environments.

Closest to the described by the technical nature and the achieved result is a method of protecting steel from hydrogen sulfide corrosion [US Pat. RF №2354752, cl. C23F 11/14, publ. 05/10/2009. Bull. No. 17], including the addition of a nitrogen-containing heterocyclic compound to a mineralized medium containing hydrogen sulfide, in which 2,4,6-tri- (1 ¹ -methyl-2 ¹ -butenyl) aniline is used at a concentration of 25-200 as a nitrogen-containing heterocyclic compound mg / l

The disadvantage of this method is its insufficiently high inhibitor effectiveness.

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

In the claimed technical solution, a method of protecting steel from hydrogen sulfide corrosion involves adding a nitrogen-containing heterocyclic compound to a mineralized medium containing hydrogen sulfide, wherein 1,3-diamyl-5-aminobenzoyl-6-methyluracil is used at a concentration of 25-200 mg / l In a mineralized environment, the content of hydrogen sulfide is up to 1000 mg / l.

1,3-Diamyl-5-aminobenzoyl-6-methyluracil (DABMU)

prepared by reacting 5-aminobenzoyl-6-methyluracil with amyl bromide in dimethylformamide (DMF) and in the presence of tetrabutylammonium bromide and potassium carbonate according to the following procedure.

A three-necked flask equipped with a mechanical stirrer was charged with 1 g (0.0045 mol) of 5-aminobenzoyl-6-methyluracil, 1.24 g of potassium carbonate K ₂ CO ₃ , 100 ml of dimethylformamide and tetrabutylammonium bromide; the reaction mass was stirred at room temperature for 3 hours and left overnight. Then, 1.53 ml (0.012 mol) of amyl bromide was added and heated for 16 h at 160 ° C. The cooled reaction mixture was filtered, the filtrate was evaporated under reduced pressure, the residue was dissolved in chloroform, washed with water and dried over magnesium sulfate MgSO ₄ . The solvent was removed under reduced pressure to obtain 1.5 g (86%) of 1,3-diamyl-5-aminobenzoyl-6-methyluracil as a thick oil. ¹ H NMR Spectrum (CDCl ₃ , δ, ppm): 0.88-0.93 (m, 6H, 2 CH ₃ (CH ₂ ) ₄ N ¹ , CH ₃ (CH ₂ ) ₄ N ³ ); 1.33-1.40 (m, 8H, CH ₂ (CH ₂ ) ₃ N ¹ , CH ₃ (CH ₂ ) ₃ N ³ CH ₂ (CH ₂ ) ₂ N ¹ , CH ₂ (CH ₂ ) ₂ N ³ ); 1.63-1.79 (m, 4H, CH ₂ CH ₂ N ¹ , CH ₂ CH ₂ N ³ ); 2.28 (s, 3H, CH ₃ C ⁶ ); 3.89 (t, 2H, CH ₂ N ¹ , J = 7.6 Hz); 3.95 (t, 2H, CH ₂ N ³ , J = 7.6 Hz); 7.68 (s, 1H, NH); 7.40-7.95 (m, 5H, ArH).

Tests of the protective effect of 1,3-diamyl-5-aminobenzoyl-6-methyluracil as a steel corrosion inhibitor in hydrogen sulfide media were carried out under laboratory conditions by the gravimetric method in accordance with GOST 9506-89 “Acid corrosion inhibitors”.

As working media, a wastewater model 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. The hydrogen sulfide content in the wastewater was 1000 mg / L. As witness samples used plates made of steel grade Art. (GOST 380-90). Fat-free and dried to constant weight samples of steel grade 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, washed again with running water and dried to constant weight. Next, the samples were weighed to an accuracy of 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 is the change in mass, g S is the area of the sample, m ² ; t is the duration of the test, 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 · h

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

Table No. p / p The concentration of DABMU, mg / l The corrosion rate, g / m ² · h Degree of protection, % The control - 0.84 0 one 250 0.036 95.7 2 200 0.037 95.6 3 one hundred 0.063 92.5 four fifty 0.087 89.6 5 25 0.128 84.8 6 twenty 0.386 54.0

The test results shown in the table indicate the high efficiency of the proposed corrosion inhibitor of steel in hydrogen sulfide environments. The highest efficiency is achieved with an inhibitor concentration of 25 to 200 mg / L. With an increase in the inhibitor concentration above 200 mg / L, the degree of protection does not change significantly (experiment 1), and when its concentration drops below 25 mg / L, a sharp decrease in the degree of protection is observed (experiment 6).

The proposed inhibitor exhibits anticorrosive activity at concentrations of hydrogen sulfide in wastewater up to 1000 mg / L.

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 1,3-diamyl-5-aminobenzoyl-6-methyluracil (84.8-95.6%) in a mineralized medium containing hydrogen sulfide.

2. The decrease in the corrosion rate of steel in the presence of 1,3-diamyl-5-aminobenzoyl-6-methyluracil is 6-20 times.

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

Claims (1)

A method of protecting steel from hydrogen sulfide corrosion, comprising adding a nitrogen-containing heterocyclic compound to a mineralized medium containing hydrogen sulfide, characterized in that 1,3-diamyl-5-aminobenzoyl-6-methyluracil is used as a nitrogen-containing heterocyclic compound at a concentration of 25-200 mg / l