GB2028810A

GB2028810A - Corrosion-retarding compositions comprising hydrazine salts

Info

Publication number: GB2028810A
Application number: GB7844782A
Authority: GB
Original assignee: Malaco AG; Kemanobel AB
Current assignee: Malaco AG; Kemanobel AB
Priority date: 1977-11-16
Filing date: 1978-11-16
Publication date: 1980-03-12
Also published as: NO151045C; NO783851L; GB2028810B; NO151045B

Abstract

A corrosion retarding composition, useful for retarding corrosion of metals in contact with liquid systems, comprises a hydrazine salt of an amido carboxylic acid. The hydrazine salt, which may contain at least one hydrophobic group, is preferably used in combination with an ether amine or a quaternary ammonium compound. The hydrazine salt gives a substantial reduction of both general and localized corrosion and is particularly useful for preventing corrosion in different areas of oil recovery and in the petroleum industry.

Description

SPECIFICATION A method and a composition for inhibiting corrosion The present invention relates to a method of preventing corrosion of metals in contact with corrosive systems.

In order to preserve metals, and particularlyferrous metals, in contact with corrosive liquids, corrosion inhibitors are added to many systems including cooling systems refinery units, pipelines, steam generators, oil production units etc.

Nitrogen compounds such as quaternary ammonium compounds, amines, fatty amine salts, amine salts of sarcosine derivatives etc., are well known corrosion inhibitors. These compounds are film-forming inhibitors, i.e. they are absorbed on metal surfaces forming a protective film between the metal and the corrosive environment. Film-forming inhibitors of the mentioned kind are useful against corrosion arising from inorganic salts such as chlorides, sulfates, carbonates etc., dissolved gases such as carbon dioxide and hydrogen sulfide. Conventional nitrogen containing inhibitors do however often fail in systems containing certain combinations of dissolved gases such as hydrogen sulfide and oxygen, both important corrosion factors in liquid systems, especially in the petroleum industry.

An important type of corrosion is the serious localized corrosion caused by dissolved oxygen, carbon dioxide, hydrogen sulfide etc. Prevention of oxygen corrosion is usually effected by using oxygen scavangers, the most common ones being sulfite and dithionite. Hydrazine can be used as an oxygen scavenger but is not satisfactory as it is unstable and toxic. Furthermore hydrazine has the disadvantage of being a slow reactant and it does notfunction satisfactorily at temperatures below about 50"C.

According to the present invention it has been found that a substantial reduction in the corrosion of metal structures, such as ferrous pipes, tubings etc., is obtained by using hydrazine salts of amido carboxylic acids as corrosion inhibitors. The salts can be introduced into aqueous systems such as cooling systems, systems for hydrostatic testing, water flooding systems in oil recovery etc., and into organic systems, particularly hydrocarbon systems, such as pipelines and transmission lines, refinery units and chemical processing systems.

The present invention thus relates to a method of preventing corrosion of metals in contact with liquid systems which comprises providing in the systems an effective amount of a hydrazine salt of an amido carboxylic acid. The amido carboxylic acid preferably has the formula: R-X-(CH2)nCOOH wherein X is a group of the formula

wherein R is an organic hydrophobic group having from 5 to 22 carbon atoms, R1 is hydrogen, a lower alkyl group having from 1 to 4 carbon atoms, or an organic hydrophobic group having from 5 to 22 carbon atoms and n is a integer from 1 to 10. The organic hydrophobic group R may optionally contain inert substituents, i.e. substituents that do not adversely affect the anti corrosive properties of the molecule.Examples of inert, non-interfering substituents are ether and ester groups.

The group R is suitably a straight or branched aliphatic hydrocarbon group containing from 5 to 22 carbon atoms and preferably containing from 7 to 18 carbon atoms. R1 is suitably hydrogen, a methyl, ethyl, propyl or butyl group and n an integer from 1 to 5 and X the group.

wherein R, is as defined above Examples of suitable hydrophobic groups R are alkyl groups, such as octyl, decyl, hexadecyl and octadecyl, alkenyl groups, such as oleyl and linoleyl, and naturally corring mixtures of such groups.

Examples of suitable amido carboxylic acids for salt formation with hydrazine are N-methyl, N-carboxymethyl dodecyl amide, succinic acid monohexadecyl amide and adipic acid N,N-dioctyl monoamide.

The hydrazine salts used in the present process can be prepared by mixing the amido carboxylic acid and the hydrazine at room temperature or slightly elevated temperatures. The reaction medium can be water and/or organic solvents. Examples of possible solvents are lower alcohols such as methanol, ethanol and isopropyl alcohol, glycols, and aliphatic and aromatic hydrocarbons. The hydrazine salts can be inserted as corrosion inhibitors as solutions or dispersions of varying concentrations in the inert diluent in which they are prepared or as concentrates.

The hydrazine salts of the amido carboxylic acids are effective because of the combined properties of corrosion inhibition and oxygen scavenging. It is believed that the effect depends on the transportation of the hydrazinetothe metallic surfaces by the amido carboxylic acids whereby reducing conditions are produced at the actual surface in contrasttothe conventional separate addition of an oxygen scavenger to corrosive systems. The introduction of hydrazine as a compound considerably lowers the toxic problems connected with the use of hydrazine by reducing the vapour pressure of the hydrazine.

It is within the scope of the invention that there might be a molar excess of the hydrazine or the amido carboxylic acid which for certain systems may enhance the effect. The hydrazine is suitably present in an excess of at least 0.1 moles with respect to the amido carboxylic acid, and preferably in a molar excess of from 0.1 to 1.

Although the hydrazine salts above give a satisfactory protection it has been found that the effect can be considerably enhanced by the presence of an amine or a quaternary ammonium compound and this constitutes another aspect of the invention. The amines can be primary, secondary or tertiary and may be mono-, di- or tri ether amines. The amines and the quaternary ammonium compounds suitably contain at least one hydrophobic organic group having 6 carbon atoms or more. The amines and the quaternary ammonium compounds may be substituted with hydroxyalkyl groups or be alkoxylated.

The method of the invention also comprises the addition to corrosive systems of a hydrazine salt of an amido carboxylic acid preferably an amido carboxylic acid as defined above, in combination with an amine or a quaternary ammonium compound.

The amine or the quaternary ammonium compound is suitably present in a molar ratio of at least 1:20 with respect to the hydrazine salt and preferably within the molar ratio of 1:10 to 10:10.

The quaternary ammonium compounds for use in combination with the salts can be represented by the general formula

wherein at least one of the groups R2, R3, R4 and R5 is an organic hydrophobic group having 8 to 20 carbon atoms. The other substituents are independently alkyl or hydroxyalkyl groups having 1 to 4 carbon atoms, benzyl groups or groups of the formula (C2H4O)pH or (CaH6O)pH where p is 2 to 10. The preferred anion in the quaternary ammonium compounds is chloride but this can of course be replaced by any other anion such as bromide- or ethylsulphate ion.

Examples of suitable quaternary ammonium compounds are dioctyl dimethyl ammonium chloride, dodecyl trimethyl ammonium chloride, cetyl trimethyl ammonium chloride, cetyl trimethyl ammonium bromide, dodecyl dimethyl benzyl ammonium chloride etc. Particularly good results have been obtained with quaternary ammonium compounds containing one organic hydrophobic group and one benzyl group, the other substituents being hydroxy alkyl or alkyl groups having from 1 to 4 carbon atoms.

The amines which may be used in combination with the salts are preferably ether amines having the general formula

wherein R6 is an organic hydrophobic group containing at least 6 carbon atoms, a is an integer from 1 to 5, m is O or 1, n is an integer from 2 to 10, the groups X independently of each other are hydrogen, an alkyl group having from 1 to 4 carbon atoms or the group (alkylene-O) H where y is from 1 to 10, p isO, 1 or2 and q isO or 1, provided that q is 0 when p is 2, and the alkylene group is an ethylene-, propylene or isopropylene group.

The ether amines may be used as free amines or in the form of water soluble salts such as chlorides, hydrochlorides, phosphates, su Ifites, acetates, benzoates etc. They are preferably used as free amines or as sulfites or bisulfites.

Particularly preferred are the ether amines which can be represented by the general formula

where the substituents and integers are as defined above.

The organic hydrophobic group is suitably a straight or branched aliphatic hydrocarbon group containing from 6 to 22 carbon atoms, preferably from 8 to 18 carbon atoms and most preferably from 8 to 12 carbon atoms.

Examples of suitable groups are alkyl groups, such as heptyl, octyl, nonyl, decyl, dodecyl, hexadecyl, octadecyl, 2-ethylhexyl, 2-ethyl-4-methyl-pentyl, isononyl, isodecyl, isotridecyl, isohexadecyl, isooctadecyi, and alkenyl groups such as oleyl and linoleyl. The organic hydrophobic groups may also be mixtures of naturally occurring groups. It is to be understood that the groups (O-alkylene) and (alkylene-O)y may contain mixtures of alkylene groups, such as mixtures of ethylene, propylene and isopropylene groups.

The substituent X in the ether amines suitably represents hydrogen or the group (alkylene-O)y, wherein y is from 1 to 10. PreferablyX is hydrogen.

The integer a is preferably 1 or 2 and m is preferably 0 when a is 1 and 0 or 1 when a is greater than 1. The integer n is preferably 2 or 3.

Examples of suitable ether amines are 3 - octoxypropyl amine, N(3-octoxypropyl) propylene diamine, N(3-decoxypropyl) propylene diamine, N(3dodecoxypropyl) propylene diamine, N(2octoxyethyl) ethylene diamine and N(2-decoxyethyl) ethylene diamine.

According to the invention, the hydrazine salt of the amido carboxylic acids is preferably used together with an ether amine. Besides the particularly good corrosion inhibiting effect of the combination, the ether amines have advantageous miscibility and solubility properties in water systems and they also have useful bactericidal properties.

In a particular embodiment of the present invention the amido carboxylic acid salts are used in combination with sulfites or bisulfites of the ether amines. The sulfites of the ether amines have good reducing properties and thus give excellent protection against localized corrosion. These compounds can be prepared by reacting sulfur dioxide or sulfurous acid with the ether amines in water, alcohols or mixtures of these at room temperature or slightly elevated temperatures. The ether amine can be reacted with one mole or less of SO2 or H2SO3 per nitrogen atom in the amine.

The combination of the hydrazine salt of the amido carboxylic acid and ether amine or quaternary ammonium compound can be added to a corrosive system in the form of solutions or dispersions in water and/or organic solvents. As examples of solvents can be mentioned lower alcohols such as methanol, ethanol and isopropyl alcohol, glycols and aliphatic and aromatic hydrocarbons. Mixing of the components in the diluent can be carried out at room temperature or slightly elevated temperatures.

The invention also relates to compositions for prevention of corrosion of metals said compositions comprising the above defined hydrazine salts of the amido carboxylic acids in combinations with the above defined ether amines or quaternary ammonium compounds. The ether amines or the quaternary ammonium compounds are suitably present in the compositions in a molar amount with respect to the hydrazine salt of at least 1:20, preferably within the molar range offrom 1:5 to 5:1. Preferred compositions contain the ether diamines.

The amount of hydrazine salts or active ingredients in composition containing these required for sufficient protection does of course vary with the corrosiveness of the systems. Methods for monitoring the severity of corrosion in different systems are well known and serve as a basis for deciding the effective amount.

The hydrazine salts generally give a substantial reduction of corrosion when present in amounts of about 1 ppm based on the weight of the corrosive liquid. The upper limit is not critical but depends on the particular compound and the particular system.

Amounts up to and above 1000 ppm can be used but preferably the concentration is within the range of 1 to 200 ppm.

The hydrazine salts of the present invention and compositions containing the same are particularly useful in the different areas of oil recovery and petroleum industry. They can be used in primary, secondary and tertiary oil recovery and added in a manner known per se. They can also be incorporated in water-soluble capsules which are introduced in the wells and when the capsules dissolve the inhibitor is slowly released into the corrosive fluid. Another technique in primary oil recovery where the salts can be used is the squeeze treating technique whereby they are injected under pressure into the producing formation, are absorbed on the strata and desorbed as the fluids are produced. They can further be added in the water flooding operations of secondary oil recovery as well as added to pipelines, transmission lines and refinery units.

The hydrazine salts of the invention can be used in combination with known inhibitors and oxygen scavengers and also in combination with additives generally used in the field such as anti-freezing agents, anti-fouling agents, surface active agents, e.g. nonionic dispersant and chelating agents.

The invention is further illustrated in the following examples which however are not intended to limit the same.

Example 1 A hydrazine salt of N-methyl, N-carboxymethyl oleylamide was prepared by dissolving 20 grams of the amidoacid in 50 grams of isopropanol and 25 grams of water. 1.75 grams of hydrazine dissolved in 3.25 grams of water was added and a clear solution of the hydrazine salt was obtained.

Example 2 Corrosion Test The product from example 1 and the separate components of the formulated product as well as the corresponding sodium salt and several other inhibitors were tested. All inhibitor formulations were made up in isopropanol and water as solvent.

The dosage in ppm refers to the active part of the inhibitor i.e. not the solvent.

Test Method 50 ml of crude oil and 950 ml of a brine solution with the following composition were poured into a 1000 ml E-flask.

Component NaCI 4.4 NaHCO3 0.08 CaCI2 0.06 MgCl2 0.03 MgSO4 0.01 water 95.43 The mixture was vigorously stirred and CO2 was bubbled through for 15 minutes giving a mixture saturated with CO2 and with an oxygen content less than 0.5 ppm. The temperature was kept at 25"C. A polarisation resistance instrument (Magna Corrater) equipped with 1010 mild steel electrodes was used for the corrosion measurements. At the end of the period of 15 minutes, the electrodes were put into the brine solution. After 1 hour of stabilization of the corrosion rate a corrosion reading (CA) was taken, then the inhibitor was added. After a further 6 hours a final corrosion reading was taken (cub). During the test the brine was kept saturated with CO2 by continued injection of CO2 into the solution.

Since different electrodes give different initial corrosion readings, a relative corrosion rate at the end of the test period was calculated.

CB Relative corrosion rate = -x 100.

CA In the table the following abbreviations have been used: N-methyl, N-carboxymethyl-oleyl amide CMO Hydrazine H Sodium salt of N-methyl, N-carboxymethyl oleyl amide CMONa Hydrazine salt of N-methyl, N-carboxymethyl oleyl amide CMOH N-methyl, N-carboxymethyl lauryl amide CML Hydrazine salt of N-methyl, N-ca rboxymethyl lauryl amide CMLH

RELATIVE | MOLE DOSAGE CORROSION INHIBITOR RATIO ppm RATE 0 - - 100 cHO - 30 30 cML - 39 50 CMOH - 30 1.5 CMONa - 30 40 CMLH - 30 3.0 CMLH + 3-octoxy propylamine 1: :1 30 1.0 CMLH + dodecyl dimethyl benzyl ammonium chloride 1:1 30 0.2 3-octoxypropylamine - 30 80 dodecyl dimethyl benzyl ammonium chloride - 30 40 Included herein as a part of the disclosure hereof is the disclosure of Swedish Patent Application No.

7712954-2, a certified copy of which is filed herewith.

Claims

1. A corrosion retarding composition, which comprises a hydrazine salt of an amido carboxylic acid.

2. A composition as claimed in claim 1, wherein the amido carboxylic acid, has formula: R-X-(CH2)n COOH wherein Xis a group of the formula

wherein R is an organic hydrophobic group having from 5 to 22 carbon atoms, R1-is hydrogen, a C14 alkyl group or an organic hydrophobic group having from 5 to 22 carbon atoms, and n is an integer from 1 to 10.

3. A composition as claimed in claim 2, wherein R is a straight or branched aliphatic group having from 7 to 18 carbon atoms, R1 is an alkyl group having from 1-4 carbon atoms and n is from 1 to 5.

4. A composition as claimed in claim 2, wherein R1 has the same meaning as R.

5. A composition as claimed in claim 2 or claim 3 wherein X is the group

R where where R1 is a C14 alkyl group

6. A composition as claimed in any one of the preceding claims which also comprises a diluent.

7. A composition which comprises up to 1000 parts per million by weight of the salt specified in any one of claims 1 to 6, the balance being a corrosive liquid.

8. A composition as claimed in claim 7, which comprises from 1 to 200 parts per million by weight of the salt specified in claim 1.

9. A composition as claimed in claim 7 or claim 8, wherein the balance comprises oil or an oil-based product.

10. Acomposition as claimed in any one of claims 7 to 9, wherein the balance comprises brine.

11. A composition as claimed in any one of the preceding claims, which also comprises an ether amine or a salt thereof, or a quaternary ammonium compound.

12. A composition as claimed in claim 11, wherein the mole ratio of the ether amine or its salt or quaternary ammonium compound to the hydrazine salt is at least 1:20.

13. A composition as claimed in claim 12 wherein the molar ratio of the ether amine or its salt or the quarternary ammonium compound to the hydrazine salt is from 1:5 to 5:1.

14. A composition as claimed in claim 11 or claim 12, wherein the ether amine (or its salt) or quaternary ammonium compound contains an organic hydrophobic group having at least 6 carbon atoms.

15. A composition as claimed in any one of claims 11 to 14, wherein the ether amine has the

general formula R lkYlene{}a - (C.2) - < - Ni - X N[cfl2)n - - x wherein R2 is an organic hydrophobic group containing at least 6 carbon atoms, a is an integer from 1 to 5, m isO or 1, each group X independently is hydrogen, an alkyl group having from 1-4 carbon atoms orthe group (alkylene-O)yH whereby is from 1 to 10, p is 0, 1 or 2 and q is 0 or 1, provided that q is 0 when p is 2, and each alkylene group independantly is an ethylene-, propylene or isopropylene group.

16. A composition as claimed in any one of claims 11 to 13, comprising the sulfite or bisulfite of an ether amine as defined in claim 14.

17. A composition as claimed in any one of claims 11 to 13, wherein the quaternary ammonium compound has the general formula

wherein at least one of the groups R3, R4, R5 and R6 is an organic hydrophobic group having 6 carbon atoms or more and each other of these substituents independently is an alkyl or hydroxyalkyl group having from 1 to 4 carbon atoms, a benzyl groups or a group of the formula (C2H4O)pH or (C3H6O)pH wherein p is from 2 to 10, and Xis an anion.

18. A composition as claimed in claim 1 and substantially as hereinbefore described in any one of the specific Examples.

19. A method of decreasing the corrosion of a metal by a liquid, which method comprises providing in the liquid an effective concentration of a hydrazine salt of an amido carboxylic acid.

19. A method of decreasing the corrosion of a metal by a liquid, which method comprises providing in the liquid an effective concentration of a hydrazine salt of a carboxylic acid.

20. A method as claimed in claim 19, wherein the salt is as defined in any one of claims 2 to 5.

21. A method as claimed in claim 19 or claim 20 wherein an ether amine or a salt thereof, or a quaternary ammonium compound is also provided in the liquid.

22. A method as claimed in claim 21 wherein the ether amine, salt, or quaternary ammonium compound is as defined in any one of claims 14 to 17.

23. A method as claimed in any one of claims 19 to 22, wherein the salt is added to the liquid during or priorto its passage through a pipeline.

24. A method as claimed in any one of claims 19 to 23 wherein the said salt is added in the form of a composition as claimed in any one of claims 1 to 6, or 11 to 18 when appendantto any one of claims 1 to 6.

25. A method as claimed in any one of claims 19 to 24 wherein the said compounds are added in the form of slow-release capsules.

26. A method as claimed in any one of claims 19 to 25, wherein the liquid is crude oil.

27. A method as claimed in claim 26, wherein the said compounds are added to the oil before its extraction from an oil well.

28. A method as claimed in claim 19 and substantially as hereinbefore described.

29. A method of transporting oil, which comprises conveying the oil through a pipeline, the oil being a composition as claimed in claim 3.

New claims or amendments to claims filed on 26th October 1979.

Superseded claim, 19.

New or amended claims: