RU2805531C1 - Steel corrosion inhibitor based on substituted imidazoline - Google Patents

Abstract

FIELD: corrosion protection.

SUBSTANCE: invention can be used in the oil industry for acid treatment of boreholes, as well as for treatment of the bottomhole zone of oil and water injection wells. 1,3-dimethyl-2-(4-mercaptophenyl)imidazolidine compound with the formula is proposed to use St3 steel as a corrosion inhibitor in the concentration range of 100-400 mg/l in a 15% aqueous solution of hydrochloric acid at a temperature of 25°C.

EFFECT: corrosion rate of steel St3 in the presence of 1,3-dimethyl-2-(4-mercaptophenyl)imidazolidine is reduced from 13.5 mm/year in a non-inhibited solution to 1.8 mm/year.

1 cl, 1 tbl, 2 ex

Description

The invention relates to means of protecting metals from corrosion, namely to the use of 1,3-dimethyl-2-(4-mercaptophenyl)imidazolidine as a corrosion inhibitor for low-carbon steel in a 15% aqueous solution of hydrochloric acid, which can be used in the oil industry for acid treatment drilling wells, as well as for treating the bottomhole zone of oil and water injection wells.

The studied compound belongs to the class of substituted imidazolines, which contains N, S atoms, as well as unsaturated bonds. As inhibitors of acid corrosion of steel, imidazoline derivatives are used, which also contain N atoms or amino groups prone to protonation (RU 2 754 320 C1, RU 2754326 C1, RU 2754323 C1).

Various thiadiazole derivatives are being studied as corrosion inhibitors for carbon steel (G Bereket, E WITH Quantum chemical studies on some imidazole derivatives as corrosion inhibitors for iron in acidic medium. Elsevier, 2002, p.79-88), such research is promising in this industry, since this class of substances meets the environmental requirements for modern corrosion inhibitors (M. Ouakkiac, M. Galai, M. Cherkaoui. Imidazole derivatives as efficient and potential class of corrosion inhibitors for metals and alloys in aqueous electrolytes: A review (Elsevier, 2022). The purpose of the invention is to search for new heterocyclic compounds that reduce the corrosion rate of low-carbon steel in contact with metal equipment and have synthesis methods available for scaling, as well as expanding the range of possible compounds that slow down steel corrosion. The result obtained is that 1,3-dimethyl-2-(4-mercaptophenyl)imidazolidine suppresses corrosion of low-carbon steel St3 (GOST 380-2005) in a 15% aqueous solution of hydrochloric acid, at a concentration of 100 - 400 mg/l. The corrosion rate in the presence of 1,3-dimethyl-2-(4-mercaptophenyl)imidazolidine decreases from 13.5 mm/year in an uninhibited solution to 1.8 mm/year at 25°C at a concentration of 400 mg/l.

Example 1: 1,3-Dimethyl-2-(4-mercaptophenyl)imidazolidine

When 4-mercaptobenzaldehyde and N,N'-dimethylaniline are boiled, cyclization occurs to form the corresponding 1,3-dimethyl-2-(4-mercaptophenyl)imidazolidine. Next, a mixture of N,N'-dimethylethylenediamine and 4-mercaptobenzaldehyde (1:1) was boiled in dry toluene in the presence of a catalytic amount of p-toluenesulfonic acid. The resulting product was purified by vacuum distillation.

^1H NMR spectrum (400 MHz, CDCl ₃ ), d, ppm: 7.42 - 7.32 (m, 2H), 7.30 - 7.21 (m, 2H), 3.41 - 3.36 (m, 2H), 3.28 - 3.20 ( m, 2H), 2.57 - 2.46 (m, 6H), 2.22 - 2.14 (m, 6H).

¹³ C NMR spectrum (101 MHz, CDCl ₃ ), d, ppm: 138.83, 137.22, 129.65, 126.84, 92.30, 53.63, 39.72, 16.19.

Example 2. Corrosion tests are carried out in laboratory conditions using the gravimetric method (GOST 9.506-87) in a 15% aqueous solution of hydrochloric acid at standard temperature.

The corrosion rate was determined gravimetrically, i.e. according to the weight loss of St3 samples before and after exposure to test solutions for 24 hours at a temperature of 25°C. The corrosion rate (P), the degree of inhibition (γ) and the inhibitory effect (Z _gr ) were calculated using the formulas:

where m ₀ is the mass of the original sample, g; m is the mass of the sample after corrosion testing and removal of corrosion products, g; S is the surface area of the sample, ^m2 ; m - test time, h; ρ is the density of St3, P ₀ and P are the corrosion rates of steel, respectively, in a pure solution and with the addition of an inhibitor, mm/year.

Claims (3)

Application of 1,3-dimethyl-2-(4-mercaptophenyl)imidazolidine with formula as a corrosion inhibitor for St3 steel in the concentration range of 100-400 mg/l in a 15% aqueous HCl solution at a temperature of 25°C.