RU2147625C1 - Acid corrosion inhibitor - Google Patents

Abstract

FIELD: protection of metals against acid corrosion with use of chemical reagents. SUBSTANCE: invention can find use in petroleum and petrochemical industries. Composition of proposed inhibitor includes product of condensation of primary or secondary amines, acetophenon and formaldehyde in molar proportion 1: 1-2: 1.2-2.4 to make inhibitor cheaper and to enhance its efficiency in acid environment. Urotropine in the amount of 10-90 per cent by mass is added into prepared composition. EFFECT: cheapened inhibitor with enhanced efficiency in acid environment. 1 tbl

Description

 The invention relates to the field of protection of metals from acid corrosion with the help of chemicals and can be used to prevent corrosion of steel in the oil and petrochemical industries, for example, in pipelines and containers for storing various products.

 Known corrosion inhibitor of steel in acidic solutions - Catapine KI-1, in which to increase the inhibitory properties contains urotropin in the following ratio of its components, wt.%: Catapine (the product of the interaction of chloromethyl derivatives of aromatic hydrocarbons with pyridine) - at least 25, urotropin - no more than 25, hydrochloric acid (30%) - 25, water - the rest, produced according to TU 6-01-4689387-34-90 [Corrosion inhibitors. The nomenclature reference under the editorship of E.S. Ivanova et al. Cherkasy, 1988, p. 48].

Also known is the "Acid Corrosion Inhibitor" according to RF patent N 2063478 IPC ⁶ C 23 F 11/04, 07/10/96, containing an ethoxylated condensation product of alkyl phenols, polyalkylene polyamines and formaldehyde in the following ratio, wt.%: Alkyl phenols 16 - 22 ; polyalkylene polyamines 12 to 20; formaldehyde 2 to 3; ethylene oxide 55 - 70.

 Closest to the claimed solution is a corrosion inhibitor in acidic environments (European application N 0139567, class C 23 F 11/04, 1985), containing the product of the interaction (condensation) of amine, formaldehyde and acetophenone.

 A disadvantage of the known inhibitors is their comparative high cost and lack of effectiveness in protecting metals from acid corrosion.

 The objective of the invention is to reduce the cost of the inhibitory composition and increase the effectiveness of corrosion protection.

 The problem is solved by an acid corrosion inhibitor containing a condensation product of amine, formaldehyde and acetophenone, in which, unlike the prototype, it contains primary or secondary amines as an amine with the ratio of amine: acetophenone: formaldehyde = 1: 1 - 2: 1,2 - 2.4, and urotropin is additionally introduced into the obtained condensation product, the amount of which in the composition is 10 - 90 wt.%.

 The introduction of the composition of the composition of the cheap component of urotropin can reduce the cost of the inhibitor and at the same time increase its effectiveness in protecting against corrosion.

 The analysis of patent and scientific and technical information showed that technical solutions are unknown that use a combination of acetophenone, formaldehyde and urotropin to create highly effective inhibitory compositions.

 Example 1

A 37% aqueous solution of formaldehyde was added dropwise to a mixture of amine with acetophenone at room temperature for 30 minutes, the molar ratio of amine, acetophenone and formaldehyde, respectively, 1: 2: 2.4. The reaction mass was heated to 85 - 90 ^o C, was given a two-hour exposure and distilled off water and other volatile impurities under vacuum at a residual pressure of 20 - 30 mm Hg and a temperature of 85 - 90 ^o C. To the resulting condensation product was added an aqueous solution of urotropine with a content in the total amount of the product of 10 wt.%. The mixture was stirred until a homogeneous solution for 1 hour and cooled to 20 ^o C.

 Example 2

An aqueous solution of formaldehyde in a molar ratio of amine, acetophenone and formaldehyde of 1: 1: 1.2 was added dropwise to the mixture of amine with acetophenone in the reactor for 30 minutes. The reaction mass was heated to 85 - 90 ^o C, was given a two-hour exposure and distilled off water and other volatile impurities under vacuum at a pressure of 20 - 30 mm RT. Art. and a temperature of 85 - 90 ^o C. To the resulting condensation product was added an aqueous solution of urotropine with a content of the latter in the total amount of the product of 90 wt.%. The mixture was stirred until a homogeneous solution for 1 hour and cooled to 20 ^o C.

где V_k - скорость коррозии металла, г/м² в час;
m₁ - масса образца металла до помещения в агрессивную среду, г;
m₂ - масса образца металла после окончания опыта, г;
S - площадь поверхности образца, м²;
t - время экспозиции образца, ч;
Э - эффективность ингибитора коррозии, %;
V_k1 - скорость коррозии образцов металла в неингибированной и V_k2 - ингибированной агрессивной среде, г/м² в час.Tests of the protective effect of the compositions proposed as acid corrosion inhibitors were carried out under laboratory conditions using metal plates made of carbon steel grade St-3 with a size of 50x10x10.5 mm. The plates were placed in 20% hydrochloric acid inhibited by the studied compositions, kept there for 24 hours at a temperature of 20 ^o C. In parallel, a control experiment was conducted with the plate placed in hydrochloric acid that did not contain an inhibitor. According to the test results, the corrosion rate and inhibitor efficiency were calculated using the formulas

where V _k is the corrosion rate of the metal, g / m ² per hour;
m ₁ is the mass of the metal sample before being placed in an aggressive environment, g;
m ₂ is the mass of the metal sample after the end of the experiment, g;
S is the surface area of the sample, m ² ;
t is the exposure time of the sample, h;
E - the effectiveness of the corrosion inhibitor,%;
V _k1 - corrosion rate of metal samples in non-inhibited and V _k2 - inhibited aggressive environment, g / m ² per hour.

The test results are summarized in table
As can be seen from the tabular data, the use of the proposed compositions with urotropine as corrosion inhibitors can reduce the concentration of aminopropiophenones by 5-10 times while maintaining the effectiveness of inhibition.

Claims (1)

 An acid corrosion inhibitor containing a condensation product of amine, formaldehyde and acetophenone, characterized in that it contains primary or secondary amines as an amine with a molar ratio of amine: acetophenone: formaldehyde = 1: 1 - 2: 1,2 - 2,4, and urotropin is additionally introduced into the obtained condensation product, the amount of which in the composition is 10 - 90 wt.%.

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