NO864342L - PROCEDURE FOR INHIBITING THE HYDROGEN-CORROSION OF METALLIC MATERIALS. - Google Patents

Description

The invention relates to a method for inhibiting the hydrogen-induced corrosion of metallic materials in promoter-containing water, methanol or their mixtures.

In the case of the impact of, for example, acids on metallic materials, material consumption is the usual cause of corrosion damage. To avoid undesirably high removal rates, so-called corrosion inhibitors are therefore added to the mineral acids such as sulfuric acid or hydrochloric acid. Such inhibited acids are particularly used in the metal processing industry for cleaning, pickling, peeling and derusting of metallic surfaces. Often, however, they are used in natural gas and natural oil transportation technology during the so-called "aciding" of the borehole, where by acid flushing, clogged pores and flow channels in gas- or petroleum-bearing carbonate-containing formations are to be opened in order to improve the degree of transportation and to increase formation yields.

In order to avoid damage due to metal removal by the impact of corrosive media on metallic materials, a large number of inhibitors are available today (compare, for example, G. Schmitt, Brit. Corr. J. 19 (1985) 16).

Thus, e.g. in DE-PS 22 35 093 the corrosion protection agent for aqueous solutions and for antifreeze agents based on glycols, triols and their aqueous solutions with a content of imidazole or thiazole derivatives, preferably benzimidazole or benzthiazole derivatives.

Furthermore, it is mentioned in DE-PS 23 21 054 in column 11, lines 15-21, albeit without further details, that the 5- or 6-membered 2-(w-aminoalkyl)-1,3-heterocycles produced according to the invention are, for example, excellent corrosion inhibitors. Since under the general formula stated in DE-PS 23 21 054 also fall compounds that were mentioned as corrosion protection agents in the above-mentioned DE-PS 22 35 093, the two patents are therefore in a narrow relationship to each other, refers which also appears from the examples in DE-PS 22 35 093 the corrosion inhibition is an inhibition of metal removal under the influence of corrosive media.

However, it must be taken into account that corrosion damage with acids or metallic building parts affected by corrosive agents can not only act with material consumption, but also with hydrogen embrittlement (compare here Bernhard Olbertz, Untersuchungen zum Einfluss von Inhibitoren auf die Korrosion und Wassertsoff-aufnahme von Stahl in Salzsaure, doctoral work, TH Aachen 1980). for this form of damage is given when the atomic hydrogen forcibly formed by metal solutions in corrosive media does not recombine after its formation on the metal surface and molecularly escape from the medium, but diffuses atomically into the material and first e.g. recombines in the interior of the metal. This leads to strong stresses in the material which, especially when superimposed with an external tensile stress, can result in a sudden failure of the material when the building part breaks.

Numerous damage cases above all to steel have shown that too

in inhibited corrosive media a considerable hydrogen uptake by the material can nevertheless take place, especially when promoters of hydrogen absorption in the metal such as f^S are also present in the medium (see also the comparison tables in the experimental section from which it can be seen that in the technique usually and for inhibition of removing corrosion well effective inhibitors,

such as dibenzyl sulfoxide /"Preventol" CJ 5 from Bayer/, the benzo-triazole /"Preventol" CJ 8 - 100 from Bayer/ and the tolyltriazole /"Preventol" CJ 7 - 100 from Bayer/ have no sufficient effect for inhibiting hydrogen-induced corrosion of steel in f^S-containing methanol), and hydrogen-induced breakage (corrosion) can occur without further visible and measurable changes to the building component. In this connection, the assumption that the inhibitors used in individual cases obviously not only insufficiently prevent the hydrogen uptake, but in the meantime have even been able to stimulate it (compare to this the above-mentioned doctoral work by Bernhard Olbertz).

The hydrogen-induced corrosion of steel plays a special role there, for example, where methanol /W is used to remove acid gases such as H2S and CC>2 from gas mixtures in technical processes. Herbert, Erdol und Kohle 9 (1956) (2) 77, F. As-inger, die Petrolchemische Industrie, vol. 1, p. 143 Akade-mie-Verlag, Berlin 1971/. In special cases, such as in the extraction and transport of natural gas, methanol is used as an aid to avoid blockages due to gas hydrate formation. In the meantime, many cases have become known in which ^S-containing methanol on unalloyed and low-alloyed steel has led to hydrogen-induced corrosion as well as hydrogen-induced stress corrosion (Z.P. Semicolenova, A.P. Lupenskii, Chemical Abstracts, 89 (1978) 16733).

A method has now been found for inhibiting hydrogen-induced corrosion of metallic materials in promoter-containing water, methanol or their mixtures, the method being characterized by adding 2-(two-aminoalkyl)-1,3-heterocycles to the promoter-containing water, methanol or their mixtures of formula

in which

A means a bivalent chain of 2 or 3 carbon atoms which can also be part of a bivalent, optionally substituted aliphatic, cycloaliphatic, araliphatic or aromatic residue,

B means a single bond or the group and/or arylene residues,

X means oxygen, sulfur or the group

12 3 4

R , R , R and R are the same or different and mean hydrogen, the nitro group, an optionally substituted aliphatic, cycloaliphatic, araliphatic or aromatic residue,

5 6 7 8

R , R , R and R are the same or different and mean hydrogen or an optionally substituted aliphatic, cycloaliphatic, araliphatic or aromatic residue and

n. and m are the same or different and mean a number from o to 14,

as the sum of n and m does not exceed the number 15.

In particular, heterocycles with the formula are used in the method according to the invention

in which

X means oxygen, sulfur or the group

R^, R^, R^, R^ and R"^ are the same or different and mean hydrogen or an optionally substituted aliphatic, cycloaliphatic, araliphatic or aromatic residue, and

(n+m) means a number between 0 and 15,

or the formula

in which

5 6 8

R , R and R have the above meaning, D means a bivalent chain of 2 or 3 carbon atoms, which may be substituted with lower alkyl residues (C^ to ), and

(n+m) has the above meaning.

Particular preference is given to compounds of the formula

in which

X means oxygen, sulfur or the group

R"*, R<6>, R^, R^ and R1^ are the same or different and mean hydrogen or an optionally substituted aliphatic, cycloaliphatic, araliphatic or aromatic residue and

(n+m) means a number between 0 and 15. 12 3 The significance of the above-mentioned residues A, B, R , R , R , R^ R^ 6 7 8 9 10 ' ' R , R , R , R and R will be explained in more detail below.

Aliphatic residues are linear or branched, optionally substituted aliphatic residues with up to 18, preferably 12, especially 6, C atoms, since in the case of the residue A they must have at least two C atoms.

Cycloaliphatic residues include those with 4 to 12 C atoms which can also be substituted, especially the cyclopentyl and cyclohexyl residues.

Araliphatic residues include those with 7 to 15 C atoms, preferably those with up to 5 C atoms in the aliphatic part and 6 or 10 C atoms in the aromatic part, which may also be substituted, especially benzyl, phenylpropyl -and the phenylbutyl residue.

Aromatic residues include those with 6 to 14 carbon atoms, which can also be substituted, especially the phenyl and naphthyl residues.

As an aryl residue (B), mention should be made, for example, of phenyl, which can also be substituted.

As substituents of the aforementioned residues, the following should be mentioned, for example: Halogen, preferably chlorine, the nitro group, the amino group which can also be mono- or di-substituted with lower alkyl residues, the hydroxy group, alkoxy and aryloxy groups, alkyl mercapto and aryl mercapto<p >groups, alkyl and arylsulfonyl groups, the alkyl and aryl residue of the above-mentioned groups having the above-mentioned meaning and especially C-^-C^-alkyl as well as phenyl, toluene or benzyl.

As 5- or 6-membered•2-(w-aminoalkyl)-1,3-heterocycles the following should be mentioned: A 2-2-(e-aminopentyl)-lmidazoline, A 2-2-(e-meth<y> lamino<p>entyl)-4-methylimidazoline, A 2-1-(6-aminoethyl)-2-( -aminopentyl)-imidazoline, A 2-2-(e-aminopentyl)-tetrahydropyrimidine, A 2-2-( ε-aminopentyl)-1-methyl-tetrahydropyrimidine, V 2-2-(ε-aminopentyl)-thiazoline,

2-amino-benzimidazole,

2-aminomethyl-benzimidazole,

2-(3-aminoethyl)-benzimidazole,

2-(3-methylaminoethyl)-benzimidazole,

2-(3-Dimethylaminoethyl)-benzimidazole,

2-(γ-aminopropyl)-benzimidazole,

2-(γ-methylaminopropyl)-benzimidazole,

2-(γ-methylaminopropyl)-4-methyl-benzimidazole, 2-(γ-amino-γ-carboxypropyl)-benzimidazole, 2-(γ-phenylaminopropyl)-5-methyl-benzimidazole, 2-(3-amino-3 -methyl-propyl)-benzimidazole, 2-(<5-aminobutyl)-benzimidazole,

2-(γ-amino-γ-methylbutyl)-benzimidazole,

2-(e-aminopentyl)-benzimidazole,

2-(e-aminopentyl)-4-methyl-benzimidazole,

2-fe -aminopentyl)-5-methyl-benzimidazole,

2-fe-aminopentyl-4(5)-methyl-benzimidazole, 2-fe-aminopentyl)-2,6-dimethyl-benzimidazole, 2-fe-aminopentyl)-5-chloro-benzimidazole,

2-(e-aminopentyl)-1-methyl-benzimidazole,

2-fe -aminopentyl)-1-phenyl-benzimidazole,

2-fe-methylaminopentyl)-benzimidazole,

2-fe-dimethylaminopentyl)-benzimidazole,

2-(e-methylaminopentyl)-1-methyl-benzimidazole, 2-(e-dimethylaminopentyl)-1-methyl-benzimidazole, 2-(^-aminohexyl)-benzimidazole, 2-(n-aminoheptyl)-benzimidazole, 2- (ε-aminodecyl)-benzimidazole, 2-(α-aminoundecyl)-benzimidazole, 2-(6-aminoethylthio)-benzimidazole, 2-(3-aminoethylthiomethyl)-benzimidazole, 2-(p-aminobenzyl)-benzimidazole,

2-(p-aminophenyl)-benzimidazole, 2-(m-aminophenyl)-benzimidazole, 2-(p-aminophenyl)-benzimidazole, 2-(p-aminophenyl)-1-methyl-benzimidazole,

2-(£-aminopentyl)-naphthimidazole,

, 2 - ('Y'-aminopropyl )-benzthiazole, 2-(g-amino-3-methyl-propyl)-benzthiazole, 2-(g-aminopentyl)-benzthiazole, 2-(y-methylaminopropyl)-benzthiazole, 2 -(3-aminoethylthio)-benzthiazole, ) 2-(e-aminopentyl)-benzoxazole,

Preferred:

2-aminobenzimidazole,

52-aminomethyl-benzimidazole, 2-(^-aminoethyl)-benzimidazole, 2-(Y-aminopropyl)-benzimidazole, 2- ff -amino-Y-carboxypropyl)-benzimidazole, 2-(e-aminopentyl)-benzimidazole,

(0 2-( -aminopentyl)-4 ( 5 )-methyl-benzimidazole, 2-(p-aminobenzyl)-benzimidazole, 2-(p-aminophenyl)-benzimidazole, 2-(£ -aminopentyl)-benzthiazole, A - 2-f^-aminopentyl)-amidazoline, 35A 2-2-(£-methylaminopentyl)-4-methylimidazoline, A 2-1-(3-aminoethyl)-2-( -aminopentyl)-imidazoline, A 2-2- (e-aminopentyl)-tetrahydropyrimidine, A 2-2-(^-aminopentyl)-1-methyl-tetrahydropyrimidine,

Especially preferred:

2-(e-aminopentyl)-benzimidazole.

The inhibitors can be added in amounts of approx. 0.00001 to 0.1, preferably 0.001 to 0.05 mol/l to the promoter-containing water, methanol or their mixtures.

The inhibitors can be added as well as cleaning substances that are also dissolved in a suitable solvent such as methanol, water and/or acetone to the corrosive medium. They can thereby be used individually or in admixture with each other or in admixture with other common corrosion inhibitors and/or common additives, such as surfactants.

The inhibitors used according to the invention can, for example, be produced according to the method described in DE-PS 23 21 054.

Promoters of the hydrogen-induced corrosion are all substances that favor the penetration of atomic hydrogen. in the metallic material. For example, promoters should be mentioned: hydrogen sulphide, carbon monoxide and rhodanide and cyanide ions, preferably hydrogen sulphide.

The following should be mentioned as metallic material: unalloyed and low-alloyed steel (DIN 17 100, 17 200, 17 155 and SEP 089), light metals such as aluminum and magnesium, as well as all hydride-forming metals, such as titanium, zirconium, niobium and tantalum. Unalloyed or low-alloy steels should preferably be mentioned as metallic materials.

Furthermore, the invention relates to an agent for inhibiting the hydrogen-induced corrosion of metallic materials in promoter-containing water, methanol or their mixtures, containing 2-(co-aminoalkyl)-1, 3-heterocycles of the formula

in which

A means a bivalent chain of 2 or 3 carbon atoms,

which can also be part of a bivalent, optionally substituted aliphatic, cycloaliphatic, araliphatic or aromatic residue,

B means a single bond or the group

and/or arylene residue,

X means oxygen, sulfur or the group

12 3 4

R , R , R and R are the same or different and mean hydrogen, the nitro group, an optionally substituted aliphatic, cycloaliphatic, araliphatic or aromatic residue,

R^, R^, R^ and R^ are the same or different and mean hydrogen or an optionally substituted aliphatic, cycloaliphatic, araliphatic or aromatic residue, and

n and m are the same or different and mean an integer from 0 to 14,

as the sum of n and m does not exceed the number 15.

Also, the use of 2-(co-aminoalkyl)-1,3-heterocycles of formula

in which

A means a bivalent chain of 2 or 3 carbon atoms, which can also be part of a bivalent, optionally substituted aliphatic, cycloaliphatic, araliphatic or aromatic residue,

B means a single bond or the group

X means oxygen, sulfur or the group

12 3 4

R , R , R and R are the same or different and mean hydrogen, the nitro group, an optionally substituted aliphatic, cycloaliphatic, araliphatic or aromatic residue,

R^, R^, R^ and R^ are the same or different and mean hydrogen or an optionally substituted aliphatic, cycloaliphatic, araliphatic or aromatic residue and

n and m are the same or different and mean an integer from 0 to 14,

as the sum of n and m does not exceed the number 15,

for inhibiting hydrogen-induced corrosion of metallic materials in promoter-containing water, methanol or their mixtures, the object of the invention.

That the compounds used according to the invention, especially •2-(co-aminopentyl)-benzimidazole, are able to noticeably inhibit the hydrogen-induced corrosion of e.g. steel in promoter-containing methanol is particularly surprising, since, as can be seen from the comparison table, other inhibitors common in the art do not show sufficient effect for the exhausting corrosion. These comparative experiments underpin what has previously been established that there is no correlation between the effect of an inhibitor on the kinetics of metal dissolution and its effect on the condensation of a material for hydrogen uptake, above all not in the presence of promoters such as hydrogen sulphide.

Example

For the hydrogen permeation measurement, an electrochemical double cell was used according to Devanathan and Stachurski, which was described in detail in the literature in connection with inhibition studies (G. Schmitt, B. Olbertz, Werkstoffe und Korrosion 35 (1984) 99). The permeation measurements are carried out at room temperature on 0.5 mm thick steel tin samples (material no. 1.1624), whose surfaces affected by the media amounted to 395 mm2. Technical methanol with a water content of 0.07% by mass served as corrosion medium. During the experiment, the methanol was constantly flushed through with a f^S stream. The mass loss measurements were carried out on samples of the same steel (dimensions 2.5 x 5 x 1 in mm) at a test time of 24 hours. For each measurement, three coupons were used and from the mean value of the surface-referenced mass loss, the release degree was determined. Results of comparative tests are listed in the following table and make clear the outstandingly good effect of the inhibitor according to the invention with regard to hydrogen permeation (measure for hydrogen uptake). In addition, the triggering corrosion is also inhibited very well.

Furthermore, from the comparison with known corrosion inhibitors, the triggering corrosion, such as benztriazole, tolyltriazole and dibenzyl sulphoxide, becomes clear, as these show an unexpectedly poor inhibition effect in the case of hydrogen-induced corrosion.

Claims (12)

1. Process for inhibiting hydrogen-induced corrosion of metallic materials in promoter-containing water, methanol or their mixtures, characterized in that 2-(w-aminoalkyl)-1,3-heterocycles of the formula are added to the promoter-containing water, methanol or their mixtures A means a bivalent chain of 2 or 3 carbon atoms which can also be part of a bivalent, optionally substituted aliphatic, cycloaliphatic, araliphatic or aromatic residue, B means a single bond or the group and/or arylene residue, X means oxygen, sulfur or the group 12 3 4 R , R , R and R are the same or different and mean hydrogen, the nitro group, an optionally substituted aliphatic, cycloaliphatic, araliphatic or aromatic residue, R^, R^, R^ and R^ are the same or different and mean hydrogen or an optionally substituted aliphatic, cycloaliphatic, araliphatic or aromatic residue, and n and mc are the same or different and mean an integer from 0 to 14, as the sum of n and m does not exceed the number 15. 2. Method according to claim 1, characterized in that heterocycles of formula are added in which X means oxygen, sulfur or the group R~*, R^, R^, R^ and R"^ are the same or different and mean hydrogen or an optionally substituted aliphatic, cycloaliphatic, araliphatic or aromatic residue and (n+m) means a number between 0 and 15, or the formula in which R^, R^ and R^ have the above meaning, D means a bivalent chain of 2 or 3 carbon atoms, which may be substituted with lower alkyl residues (C^ to ), and (n+m) has the above meaning. 3. Method according to claims 1 and 2, characterized in that heterocycles of the formula are added in which X means oxygen, sulfur or the group R^, R^, R^, R^ and R^ are the same or different and mean hydrogen or an optionally substituted aliphatic, cycloaliphatic, araliphatic or aromatic residue, and (n+m) means a number between 0 and 15. 4. Method according to claims 1 to 3, characterized in that 2-aminobenzimidazole is added, 2-aminomethyl-benzimidazole, 2-(3-aminoethyl)-benzimidazole, 2-(Y-aminopropyl)-benzimidazole, 2-(Y-amino-Y-carboxypropyl)-benzimidazole, 2-(e-aminopentyl)-benzimidazole, 2 -(£-aminopentyl )-4(5)-methyl-benzimidazole, 2 -(p-aminobenzyl)-benzimidazole, 2-(p-aminophenyl)-benzimidazole, 2-(e-aminopentyl)-benzthiazole, A 2-2-(e-aminopentyl )-lmidazoline, A 2-2-(e-methylaminopentyl)-4-methylimidazoline, -A 2-1-( 3-aminoethyl) - 2 - (e -aminopentyl)-imidazoline, A 2-2-(e-aminopentyl )-tetrahydropyrimidine and/or A 2-2-(ε-aminopentyl)-1-methyl-tetrahydropyrimidine. 5. Process according to claims 1 to 4, characterized in that 2-(co-aminopentyl)-benzimidazole is added. 6. Process according to claims 1 to 5, characterized in that 2-(two-aminoalkyl)-1, 3-heterocycles are added in amounts of 0.00001 to 0.1 mol/l. 7. Method according to claims 1 to 6, characterized in that 2-(co-aminoalkyl)-1, 3-heterocycles are used in a mixture with common corrosion inhibitors. 8. Means for inhibiting the hydrogen-induced corrosion of metallic materials in promoter-containing water, methanol or their mixtures containing 2-(two-aminoalkyl)-1,3-heterocycles of the formula wherein A means a bivalent chain of 2 or 3 carbon atoms, which can also be part of a bivalent, optionally substituted aliphatic, cycloaliphatic, araliphatic or aromatic residue, B means a single bond or the group and/or arylene residues, X means oxygen, sulfur or the group 12 3 4 R , R , R and R are the same or different and mean hydrogen, the nitro group, an optionally substituted aliphatic, cycloaliphatic, araliphatic or aromatic residue, R 5 , R 6 , R 7 and R 8 are the same or different and mean hydrogen or an optionally substituted aliphatic, cycloaliphatic, araliphatic or aromatic residue, and n and m are the same or different and mean an integer from 0 to 14, as the sum of n and m does not exceed the number 15. 9. Use of 2-(two-aminoalkyl)-1, 3-heterocycles of formula in which A means a bivalent chain of 2 or 3 carbon atoms which can also be part of a bivalent, optionally substituted aliphatic, cycloaliphatic, araliphatic or aromatic residue, B means a single bond or the group and/or arylene residues, • X means oxygen, sulfur or the group 12 3 4 R , R , R and R can be the same or different and mean hydrogen, the nitro group, an optionally substituted aliphatic, cycloaliphatic, araliphatic or aromatic residue, 5 6 7 8 R , R , R and R can be the same or different and mean hydrogen or an optionally substituted aliphatic, cycloaliphatic, araliphatic or aromatic residue, and n and m are the same or different and mean an integer from 0 to 15, as the sum of n and m does not exceed the number 15, for inhibiting the hydrogen-induced corrosion of metallic materials in promoter-containing water, methanol or their mixtures.