RU2303082C1 - Acid corrosion inhibitor, mainly hydrochloric acid corrosion (versions) - Google Patents

Abstract

FIELD: protection of metals against acid corrosion.

SUBSTANCE: proposed acid corrosion inhibitor contains, mass-%: organic quaternary salt of common formula [R₁R₂R₃R₄N]⁺R₅, where R₁ is hydrocarbon radical with carbon atoms from 8 to 16 or their mixture; R2 is hydrocarbon radical with carbon atoms from 1 to 7; R₃, R₄ - CH₃; R₅ - Cl, Br, 10-80; hydroiodide acid salt, 1-30; the remainder being water-soluble organic solvent. Acid corrosion inhibitor contains, mass-%: organic quarternary ammonium salt, 10-80; low-molecular carbonyl-containing compound and/or organic amines, 1-30; the remainder being water-soluble organic solvent. Inhibitor contains, mass-%: organic quarternary ammonium salt, 10-80; low-molecular carbonyl-containing compound and/or organic amines, 1-30; hydroiodide acid salt, 1-30; the remainder being water-soluble organic solvent. Proposed inhibitor may be used for protection of various metals, low-alloyed metals inclusive against corrosion in hydrochloric acid medium and in its mixture with fluohydric acid at technologically permissible concentration of inhibitor at normal and elevated temperature up to +90C.

EFFECT: enhanced efficiency.

12 cl, 2 tbl, 1 ex

Description

The invention relates to the field of protection of metals from acid corrosion, and in particular to compositions for protecting equipment from exposure to acidic environments - hydrochloric acid and its mixture with other acids, for example, hydrogen fluoride.

The inhibitor is intended for use mainly in the oil, gas and petrochemical industries at the facilities for the extraction, preparation, transport and processing of oil and gas.

Inhibitors are substances whose addition, even in small amounts, to an aggressive medium reduces the corrosion rate of metals in contact with this medium.

The introduction of an inhibitor in hydrochloric acid or its mixture with other acids reduces the corrosive acid effect, for example, on oilfield equipment, storage tanks, railway and tank trucks and other equipment to a safe level.

A known inhibitor of hydrogen sulfide corrosion and hydrogenation of metals, which includes a chlorine-containing organic quaternary ammonium salt, a tertiary amine salt and water (RF Patent No. 2064021, class C23F 11/14, 1992).

With a high protective effect from the hydrogenation of metals, this known inhibitor is ineffective in environments containing hydrochloric acid or its mixture with hydrofluoric acid.

Also known is an acid corrosion inhibitor containing a condensation product of primary or secondary amines, acetopherone and formaldehyde (a low molecular weight carbonyl-containing compound) (RF Patent No. 2147626, class C23F 11/04, 1998). The specified known inhibitor exhibits a sufficiently high inhibitory ability in hydrochloric acid at an effective concentration of at least 10 g / l.

The disadvantage of this known inhibitor is the lack of effectiveness when working in a mixture of hydrochloric acid with other acids, in particular hydrofluoric.

In addition, it is quite expensive and difficult to prepare, because involves the condensation reaction upon receipt.

The closest to the claimed invention by technical essence is an acid corrosion inhibitor containing an organic reagent - bottoms of the production of aniline or n-phenetidine or santohin and additionally a water-soluble organic solvent in the following ratio of components, wt.%: The mentioned bottoms - 5.0- 30.0; water-soluble organic solvent - the rest (RF Patent No. 2075543, CL C23F 11/04, from 1995).

However, for the specified known inhibitor, the following disadvantages are inherent:

- high consumption of inhibitor;

- insufficient degree of corrosion protection of especially low alloyed (black) steels in hydrochloric acid media and in a mixture with hydrogen fluoride at technologically acceptable concentrations of the inhibitor both at normal and elevated temperatures;

- low degree of aftereffect, especially at low concentrations of the inhibitor.

The technical result provided by the proposed variants of the inventions is to increase the efficiency of protection of various metals, including low alloys, from corrosion both in hydrochloric acid medium and in its mixture with hydrogen fluoride at technologically acceptable inhibitor concentrations by increasing the degree of protection both at normal and at elevated temperatures up to + 90 ° С and at the same time ensuring a high aftereffect.

An additional technical result is the improvement of the rheological properties of oil while protecting against corrosion during hydrochloric acid treatments of oil and gas condensate wells.

The specified technical result is achieved in three ways, namely: in the first embodiment - an acid corrosion inhibitor, mainly hydrochloric acid, containing an organic reagent and a water-soluble organic solvent, while it contains an organic quaternary ammonium salt of the general formula [R ₁ R ₂ R ₃ R ₄ N] ⁺ R ₅ ^- ,

where R ₁ is a hydrocarbon radical with the number of carbon atoms from 8 to 16 or a mixture thereof;

R ₂ is a hydrocarbon radical with the number of carbon atoms from 1 to 7;

R ₃ , R ₄ - CH ₃ ;

R ₅ is Cl, Br;

and also additionally contains a salt of hydroiodic acid in the following ratio of components, wt.%:

specified organic quaternary ammonium salt 10-80 hydrochloric acid salt 1-30 water soluble organic solvent rest

according to the second embodiment, an acid corrosion inhibitor, mainly hydrochloric acid, containing an organic reagent and a water-soluble organic solvent, while it contains an organic quaternary ammonium salt of the general formula [R ₁ R ₂ R ₃ R ₄ N] ⁺ R ₅ ^- ,

where R ₁ is a hydrocarbon radical with the number of carbon atoms from 8 to 16 or a mixture thereof;

R ₂ is a hydrocarbon radical with the number of carbon atoms from 1 to 7;

R ₃ , R ₄ - CH ₃ ;

R ₅ is Cl, Br;

and also it additionally contains a low molecular weight carbonyl-containing compound and / or organic amines in the following ratio of components, wt.%:

specified organic quaternary ammonium salt 10-80 low molecular weight carbonyl compound and / or organic amines 1-30 water soluble organic solvent rest

according to the third embodiment, an acid corrosion inhibitor, mainly hydrochloric acid, containing an organic reagent and a water-soluble organic solvent, it further comprises a salt of iodic acid, as well as a low molecular weight carbonyl-containing compound and / or organic amines, and it contains an organic quaternary as an organic reagent an ammonium salt of the general formula [R ₁ R ₂ R ₃ R ₄ N] ⁺ R ₅ ^- ,

where R ₁ is a hydrocarbon radical with the number of carbon atoms from 8 to 16 or a mixture thereof;

R ₂ is a hydrocarbon radical with the number of carbon atoms from 1 to 7;

R ₃ , R ₄ - CH ₃ ;

R ₅ is Cl, Br;

in the following ratio of components, wt.%:

specified organic quaternary ammonium salt 10-80 low molecular weight carbonyl compound and / or organic amines 1-30 hydrochloric acid salt 1-30 water soluble organic solvent rest

As a low molecular weight carbonyl-containing compound, the inhibitor contains formaldehyde, or acetaldehyde, or furfural.

As organic amines, the inhibitor contains polyethylene polyamine, or urotropine, or diphenylamine, or aniline.

As the salt of hydroiodic acid, the inhibitor contains potassium iodide, or sodium iodide, or ammonium iodide, or lithium iodide.

As a water-soluble organic solvent, the inhibitor contains methyl, or ethyl, or isopropyl alcohol, or polyglycol, or mixtures thereof.

The achievement of the specified technical result is ensured by the following.

The use of the proposed inhibitor (all three options) allows to increase the effectiveness of protection against acid corrosion, including in a mixture of hydrochloric acid with hydrogen fluoride at technologically acceptable concentrations, i.e. at sufficiently low levels in which inhibitory treatment is economically viable.

Due to the claimed qualitative composition of the inhibitors and the experimentally determined ratio in the indicated compositions of the components, the ability of these components to adsorb on a solid surface and form protective anticorrosion films increases, thereby providing a high inhibitor aftereffect.

When using the proposed inhibitor, a synergistic effect of corrosion inhibition is apparently observed due to the joint presence of cationic substances - organic quaternary ammonium salts of the claimed structural formula, capable of chemisorption on the metal surface, and the molecular effect of anionic organic molecules - low molecular weight carbonyl-containing compounds, and / or organic amines, and / or iodide ions (salts of hydroiodic acid). A likely explanation for such a synergistic effect may be due to the improvement (facilitation) of the adsorption of the quaternary ammonium salt (the claimed structural formula) in the presence of iodide ions or dipolar molecules - aldehydes and amines on the metal surface due to the formation of intermediate bridges or recharging of the metal surface, which leads to substantial hardening of the adsorbed film and effective braking of the corrosion process. In addition, nitrogen and oxygen-containing organic molecules are known to independently exhibit some inhibitory effect in acidic media. The overlapping effect of these factors, obviously, leads to the observed synergistic effect.

The quantitative ratio of the components of the proposed inhibitors was determined experimentally from the condition of ensuring the required inhibition efficiency in the medium of hydrochloric acid and its mixture with hydrofluoric acid, as well as on the basis of effective protection at small (technologically acceptable) inhibitor concentrations.

All the components that make up the proposed inhibitor are not classified as deficient and are characterized by a relatively low cost, which makes its production inexpensive and economically attractive. The latter is also explained by the fact that the proposed inhibitor is prepared by simple mechanical mixing of the components, i.e. for its preparation does not require sophisticated technological equipment, such as, for example, for the preparation of condensation products.

The proposed inhibitor was tested in laboratory conditions.

The following substances were used for its preparation:

organic quaternary ammonium salt:

- for the study we used imported samples produced by KAO Chemicals and Jiangsu Feixiang Chemical;

organic amines:

- polyethyleneamine according to TU 2413-214-00203312-2002;

- urotropin according to GOST 1381-73;

- diphenylamine according to GOST 194-80;

- aniline according to GOST 5819-78;

low molecular weight carbonyl compounds:

- formaldehyde according to GOST 1625-89;

- acetaldehyde according to TU 2422-608-00008064-2005;

- furfural according to GOST 10437-80;

hydrochloric acid salt:

- potassium iodide according to GOST 4232-74;

- sodium iodide according to GOST 8422-76;

- ammonium iodide according to TU 6-09-02-490-90;

water soluble organic solvent:

- methyl alcohol GOST 2222-95;

- ethyl alcohol GOST 18300-87;

- isopropyl alcohol GOST 17299-78;

- polyglycols TU 6-01-1352-88.

The proposed inhibitor is prepared as follows.

Example. Take 37.9 g of an aqueous-alcoholic solution of a quaternary ammonium compound [R ₁ R ₂ R ₃ R ₄ N] ⁺ R ₅ ^- (hereinafter HOUR) (with a basic substance content of 80%, R ₁ - a mixture of C ₁₀ -C ₁₂ , R ₂ - C ₂ H ₅ , R ₃ - CH ₃ , R ₄ - CH ₃ , R ₅ - Br), then 39.4 g of formaldehyde solution (with a basic substance (formaldehyde) content of 37%) are added to it, 1 g polyethylene polyamine (PEPA) and 5 g of potassium iodide, the resulting mixture is adjusted with an aqueous 50% solution of isopropyl alcohol to 100 g (for the preparation of the proposed inhibitor for the safety of work and to avoid ignition of the advantages continuously it can be used not pure alcohol and its 40-60% aqueous solution, and on the technical result is unaffected) and stirred vigorously for 10-15 minutes. The result was an inhibitor of the following component composition, wt.%: HOUR - 30.3%, formaldehyde - 14.6%, PEPA - 1%, potassium iodide - 5% and water-soluble organic solvent isopropyl alcohol - 49.1%.

Inhibitors of other options, with other components and other quantitative content was prepared in a similar way.

In laboratory conditions, the following properties of the claimed inhibitors were determined:

- homogeneity of the prepared inhibitor;

- freezing temperature;

- interfacial tension at the oil - inhibited hydrochloric acid interface;

- protective effect;

- aftereffect.

The homogeneity of the prepared inhibitor was checked visually in transmitted light.

The freezing temperature was controlled by placing the sample in the freezer of the refrigerator with a temperature of ~ minus 20 ° C.

Interfacial tension was determined by a stalagmometer according to GOST R50097-92.

All tested variants of the proposed inhibitor with the stated ratios of the components showed good mutual solubility of the components (only in some cases there was a slight amount of suspension, which completely disappeared when the inhibitor was added to the acid), all had a freezing point below minus 20 ° C and reduced interfacial tension at the oil boundary - inhibited acid 5-10 times.

Testing the protective effect of the proposed inhibitor was carried out in laboratory conditions using plates of low-alloy carbon steel grade St-3 (or from other metals) with a size of 30 × 10 × 5 mm. The plates were placed in 25% hydrochloric acid (or in a mixture of hydrochloric and hydrofluoric acids taken in concentrations of 20 and 5%, respectively), to which an inhibitor of the proposed composition was added in order to ensure the total concentration of inhibitor in an acid solution of 0.5 wt. % The plates were kept in the resulting solution for 24 hours at a temperature of + 20 ° C (or at + 90 ° C). After 24 hours, the plates were removed from the solution, washed with water, then rinsed with acetone three times and dried on filter paper in an oven at a temperature of (100 ± 5) ° С for 20 minutes. Then the plates were cooled in a desiccator and weighed on a laboratory balance to the fourth decimal place. According to the test results, the corrosion rate was calculated. The specific corrosion rate of steel (α), in g / m ² h, was calculated by the formula:

where m is the mass of the plate before the test, g;

m ₁ is the mass of the plate after testing, g;

S is the surface area of the plate, m ² .

The area of the plate (S), in m ² , is calculated by the formula:

where a is the plate length, mm;

b is the width of the plate, mm;

C - plate thickness, mm.

The arithmetic average of the results of three parallel measurements is taken as the measurement result, the absolute value of the difference between which does not exceed the value of the permissible difference of 0.04 g / m ² h.

The determination of the aftereffect was carried out as follows. After 30 days of storage of the acid composition with the inhibitor in the presence of metal samples, fresh samples were placed in the test composition, old ones were removed and daily tests were carried out according to the above procedure.

The composition of the inhibitors involved in the tests are shown in table 1.

Data on the test results are presented in table 2.

As can be seen from tables 1 and 2, when using an inhibitor of the proposed composition (various options) (experiments 1-7 and 9-16 of table 2), the corrosion rate of the metal is significantly lower than when using the inhibitor of the prototype (at the same concentration in an acid solution). In addition, as follows from the results of the experiments, the inhibitory effect persists after storage of the inhibited acid in contact with a metal surface and subsequent contact with a fresh metal surface (the aftereffect is an order of magnitude higher).

When going beyond the claimed limits of any of the components, either incomplete solubility of the inhibitor components or poor reproducibility of the protective properties of the inhibitor is observed and therefore is irrational. Using as an inhibitor only one organic Quaternary ammonium salt of the claimed structure was also ineffective (experiment 8, table 2).

Thus, the use of the proposed inhibitor allows you to:

- to provide high efficiency inhibition both in hydrochloric acid and in a mixture of hydrochloric and hydrofluoric acids at technologically acceptable concentrations of the inhibitor;

- provide a high protective effect both at normal and at elevated temperatures up to + 90 ° C;

- to provide a high aftereffect even at low concentrations of the inhibitor, which exceeds the effect of the aftereffect of the prototype by almost an order of magnitude;

- to ensure a decrease in interfacial tension at the oil-acid boundary;

- ensure the homogeneity of the inhibitor.

Table 1
The composition of the inhibitors involved in the trials No. of composition Organic Quaternary ammonium salt [R ₁ R ₂ R ₃ R ₄ N] ⁺ R ₅ -, wt.% Organic amines, wt.% Low molecular weight carbonyl-containing compounds, wt.% Salt of iodic acid, wt.% Water-soluble organic solvent, wt.% one R ₁ - C ₁₀ -C ₁₂ ,
R ₂ , R ₃ - CH ₃ ,
R ₄ - C ₂ H ₅ , R ₅ - Br,
30.3% polyethyleneamine - 1% formaldehyde - 14.6% KI - 5% Water ethyl alcohol 2 R ₁ - C ₁₀ -C ₁₂ ,
R ₃ - CH ₃ , R ₂ - C ₃ H ₇ ,
R ₄ - C ₂ H ₅ , R ₅ - Br,
fifty% urotropin - 5% acetaldehyde - 5% KI - 1% Water ethyl alcohol 3 R ₁ - C ₈ -C ₁₀ ,
R ₂ , R ₃ - CH ₃ ,
R ₄ - CH ₂ C ₆ H ₅ , R ₅ - Cl,
40% aniline - 5% acetaldehyde - 25% NH ₄ I - 1% Water ethyl alcohol four R ₁ - C ₁₂ -C ₁₄ ,
R ₃ - CH ₃ , R ₂ - C ₅ H ₁₁ ,
R ₄ is CH ₃ , R ₅ is Cl,
25% diphenylamine - 29% furfural -1% NaI - 10% Polyglycols 5 R ₁ - C ₁₀ -C ₁₂ ,
R ₂ , R ₃ - CH ₃ ,
R ₄ - C ₄ H ₉ , R ₅ - Br,
25% aniline - 5% furfural - 5% NaI - 5% Water isopropyl alcohol 6 R ₁ - C ₁₀ -C ₁₂ ,
R ₂ , R ₃ - CH ₃ ,
R ₄ - CH ₂ C ₆ H ₅ , R ₅ - Cl,
60% - - - Water isopropyl alcohol 7 R ₁ - C ₁₂ -C ₁₄ ,
R ₂ , R ₃ - CH ₃ ,
R ₄ - CH ₂ C ₆ H ₅ , R ₅ - Cl,
thirty% - formaldehyde - 30% Water isopropyl alcohol 8 R ₁ - C ₁₀ -C ₁₂ ,
R ₂ , R ₃ - CH ₃ ,
R ₄ - CH ₂ C ₆ H ₅ , R ₅ - Cl,
40% - KI - 15% Water isopropyl alcohol 9 R ₁ - C ₁₀ -C ₁₂ ,
R ₂ , R ₃ - CH ₃ ,
R ₄ - CH ₂ C ₆ H ₅ , R ₅ - Cl,
25% polyethyleneamine - 30% - - Polyglycols 10 R ₁ - C ₁₀ -C ₁₂ ,
R ₂ , R ₃ - CH ₃ ,
R ₄ - CH ₂ C ₆ H ₅ , R ₅ - Cl,
40% - formaldehyde - 10% KI - 15% Water isopropyl alcohol eleven R ₁ - C ₁₀ -C ₁₂ ,
R ₂ , R ₃ - CH ₃ ,
R ₄ - C ₃ H ₅ , R ₅ - Cl,
40% urotropin - 5% formaldehyde - 10% Water isopropyl alcohol 12 R ₁ - C ₁₀ -C ₁₂ ,
R ₂ , R ₃ - CH ₃ ,
R ₄ - CH ₂ C ₆ H ₅ , R ₅ - Cl,
10% urotropin - 10% - KI - 30% Water isopropyl alcohol

table 2
Data on the test results of the claimed and known prototype inhibitors №№ Composition No. from table 1 Protective effect The aftereffect (specific corrosion rate after holding the solution for 30 days), g / m ² h Note acid t ° C solution specific corrosion rate, g / m ² h For the proposed inhibitor one one Hcl twenty 0.14 0.14 2 one Hcl 90 0.37 - 3 one Mixture of HCl, HF twenty 0.22 0.2 four 2 Mixture of HCl, HF twenty 0.3 0.25 5 3 Hcl twenty 0.21 0.24 6 four Hcl twenty 0.24 0.24 7 5 Hcl twenty 0.24 0.24 8 6 Hcl twenty 2.66 - 9 7 Hcl twenty 0.28 - 10 7 Mixture of HCl, HF twenty 0.25 - eleven 7 Mixture of HCl, HF 90 0.45 - 12 8 Hcl twenty 0.3 - 13 9 Hcl twenty 0.29 - fourteen 10 Mixture of HCl, HF twenty 0.17 0.15 fifteen eleven Mixture of HCl, HF twenty 0.11 0.15 16 12 Mixture of HCl, HF twenty 0.15 0.3 17 eleven Mixture of HCl, HF 90 0.29 - For the prototype inhibitor eighteen Hcl twenty 0.47 5.25 19 Mixture of HCl, HF twenty 0.73 2.15 Note: Corrosion protection indicators of the proposed inhibitor of other metals, such as stainless steel grade 12X8H10T, nickel and titanium, are slightly better than the results given in the table.

Claims (12)

1. An acid corrosion inhibitor, mainly hydrochloric acid, containing an organic reagent and a water-soluble organic solvent, characterized in that it contains an organic quaternary ammonium salt of the general formula [R ₁ R ₂ R ₃ R ₄ N] ⁺ R ₅ ^- , where R ₁ is a hydrocarbon radical with the number of carbon atoms from 8 to 16 or a mixture thereof; R ₂ is a hydrocarbon radical with the number of carbon atoms from 1 to 7; R ₃ , R ₄ —CH ₃ ; R ₅ - Cl, Br, and also additionally contains a salt of hydroiodic acid in the following ratio of components, wt.%: Specified Organic Quaternary Ammonium Salt 10-80 Hydrochloric Acid Salt 1-30 Water soluble organic solvent Rest 2. The inhibitor according to claim 1, characterized in that as the salt of hydroiodic acid it contains potassium iodide, or sodium iodide, or ammonium iodide, or lithium iodide. 3. The inhibitor according to claim 1, characterized in that as a water-soluble organic solvent it contains methyl, or ethyl, or isopropyl alcohol, or polyglycol, or mixtures thereof. 4. An acid corrosion inhibitor, mainly hydrochloric acid, containing an organic reagent and a water-soluble organic solvent, characterized in that it contains an organic quaternary ammonium salt of the general formula [R ₁ R ₂ R ₃ R ₄ N] ⁺ R ₅ ^- , where R ₁ is a hydrocarbon radical with the number of carbon atoms from 8 to 16 or a mixture thereof; R ₂ is a hydrocarbon radical with the number of carbon atoms from 1 to 7; R ₃ , R ₄ —CH ₃ ; R ₅ - Cl, Br, and also it additionally contains a low molecular weight carbonyl-containing compound and / or organic amines in the following ratio of components, wt.%: Specified Organic Quaternary Ammonium Salt 10-80 Low molecular weight carbonyl compound and / or organic amines 1-30 Water soluble organic solvent Rest 5. The inhibitor according to claim 4, characterized in that as a low molecular weight carbonyl-containing compound, it contains formaldehyde, or acetaldehyde, or furfural. 6. The inhibitor according to claim 4, characterized in that as organic amines it contains polyethylene polyamine, or urotropine, or diphenylamine, or aniline. 7. The inhibitor according to claim 4, characterized in that, as a water-soluble organic solvent, it contains methyl, or ethyl, or isopropyl alcohol, or polyglycol, or mixtures thereof. 8. An acid corrosion inhibitor, mainly hydrochloric acid, containing an organic reagent and a water-soluble organic solvent, characterized in that it further comprises a salt of iodic acid, as well as a low molecular weight carbonyl-containing compound and / or organic amines, and as an organic reagent it contains an organic quaternary an ammonium salt of the general formula [R ₁ R ₂ R ₃ R ₄ N] ⁺ R ₅ ^- , where R ₁ is a hydrocarbon radical with the number of carbon atoms from 8 to 16 or a mixture thereof; R ₂ is a hydrocarbon radical with the number of carbon atoms from 1 to 7; R ₃ , R ₄ —CH ₃ ; R ₅ - Cl, Br, in the following ratio of components, wt.%: Specified Organic Quaternary Ammonium Salt 10-80 Low molecular weight carbonyl compound and / or organic amines 1-30 Hydrochloric Acid Salt 1-30 Water soluble organic solvent Rest 9. The inhibitor according to claim 8, characterized in that it contains formaldehyde, or acetaldehyde, or furfural as a low molecular weight carbonyl-containing compound. 10. The inhibitor according to claim 8, characterized in that it contains polyethylene polyamine, or urotropine, or diphenylamine, or aniline as organic amines. 11. The inhibitor according to claim 8, characterized in that as the salt of hydroiodic acid it contains potassium iodide, or sodium iodide, or ammonium iodide, or lithium iodide. 12. The inhibitor according to claim 8, characterized in that as a water-soluble organic solvent it contains methyl, or ethyl, or isopropyl alcohol, or polyglycol, or mixtures thereof.