Metal corrosion inhibitors

The present invention relates to the field of corrosion, by sulfonic acids, passivable metals and alloys, in particular based on iron, nickel, titanium, copper, aluminum, molybdenum, manganese, lead, and their alloys, as well than the couples of these metals or alloys obtained by contact (crimping, riveting, bolting, welding, brazing).

[0002] A more particular subject of the invention is the protection of said metals against corrosion by sulfonic acids, and in particular organosulphonic acids.

[0003] Sulfonic acids, more specifically organosulfonic acids, and in particular methanesulfonic acid (AMS), para-toluenesulfonic acid (APTS), benzenesulfonic acid (BS), trifluoromethanesulfonic acid are strong acids widely used in many applications, including catalysis and surface treatment (electroplating, pickling, cleaning, descaling, and others).

[0004] However, it has been observed that aqueous solutions of such sulphonic acids corrode metals, the corrosion rates depending both on the concentration of acid, on the temperature and on the nature of the metal. For example, at room temperature, type 304L or 1.4307 stainless steel is corrodible at AMS concentrations greater than 5% by weight in water. Such corrosion risks are unacceptable in many applications, and particularly for the storage of these acids mainly when they are in aqueous solution.

To protect stainless steels against corrosion by sulfonic acids (in particular APTS and poly (styrenesulfonic acid)), it has been proposed in patent application JP 07-278854 to add to these acids a copper salt. This document aims more particularly at the protection of stainless steel devices (types AISI 304 and 316) used in workshops for the synthesis of alcohols from olefins and water in the presence of a sulfonic acid as catalyst. The temperature range exemplified in this document is from room temperature up to about 100 C.

In the article entitled "Corrosion of stainless steel during acetate production" published in July 1996 in the journal "Corrosion Engineering", vol. 2, No. 7, page 558, by JS Qi and JC Lester, it is stated that the use of copper sulphate during esterification in the presence of sulfuric acid or para-toluenesulphonic acid makes it possible to considerably reduce the corrosion of AISI 304L and 316L stainless steels.

However, these copper salts, corrosion inhibitors, have drawbacks: the static tests carried out on compositions of AMS and copper (II) salts at temperatures between 100 ° C and 150 ° C show that '' on the surface of the materials tested (AISI 304L and 316L stainless steel), a thin layer of metallic copper is formed which is not very adherent. During the industrial implementation of this method, it was in fact observed a sedimentation, at the bottom of the reactor, of metallic copper particles liable to seriously damage the recycling pumps or to adversely affect the quality of the product manufactured. An additional filtration step is then necessary to remove these copper particles from the film deposited on the walls of the reactor.

In fact, during changes in operating conditions (for example, temperature, pressure, speed of agitation), this protective film peels off very easily. In addition, heavy metals are defined as pollutants for the environment and therefore the release of such types of compounds in the effluents is problematic.

[0009] It has also been disclosed, in EP-A-0 931 654, that it is possible to inhibit the corrosion of stainless steels in an organosulfonic medium, by adding at least one oxidant chosen from salts or oxides of cerium (IV), iron (III), molybdenum (VI) or vanadium (V), nitrites and persulfates. In addition, B. Gaur and HS Srinivasan (“British Corrosion Journal”, 34 (1), (1999), 63-66) have shown that the addition of ferric ions or nitrates makes it possible to produce a corrosion inhibiting effect by AMS on various steels.

It can therefore be seen that the various inhibitors of corrosion of metals by sulfonic acids, available today such as metal salts, are toxic for the environment. It is therefore highly desirable to be able to have available inhibitors of corrosion of metals by sulfonic acids which are more effective, less toxic and more respectful of the environment.

Certain applications, in particular pickling, descaling, use AMS-based solutions formulated with the addition of other products such as surfactants or complexing agents for metal ions (sulfamic, citric, oxalic acid). These can cancel the inhibitory effect of oxidizing metal salts or lead to high doses of inhibitors, not compatible with respect for the environment.

It has now been found that we can effectively protect, in a wide temperature range, metals, in particular those mentioned above, such as ferric metals, copper, aluminum, and their alloys and in particular steels, against corrosion by sulfonic acids, more specifically organosulfonic acids, preferably alkanesulfonic acids, more preferably by AMS, by adding to the medium an effective amount of at least one compound chosen from acid nitrous or a compound capable of forming nitrous acid.

[0013] According to a first aspect, the present invention relates to the use of at least one compound of general formula (1):

O = N-OX (1),

in which X is chosen from:

• H;

. NO;

• an alkyl radical R, linear or branched, comprising from 1 to 6 carbon atoms;

• an aryl radical Ar optionally substituted, in particular by at least one alkyl radical R;

• a -SO 2 -G radical , where G represents H, OH, R, OR, OM, Ar, OAr, NH 2 , NHR and NRR ', where R and Ar are as defined above, R' represents an alkyl radical linear or branched, comprising from 1 to 6 carbon atoms, and M represents a mono- or bi-valent metal cation, preferably a cation of an alkali or alkaline earth metal; and

• a -CO-G radical, where G is as defined above,

to limit, or even prevent, corrosion of metals by sulfonic acids.

When X represents the hydrogen atom, the compound of formula (1) is nitrous acid. When X represents -NO, the compound of formula (1) is nitrous anhydride.

[0015] According to a preferred embodiment of the present invention, X represents -SO2-G, and more preferably -SO2-G where -G represents -OH, in which case the corrosion inhibitor is nitrosyl acid sulfate ( SHN; CAS No. 7782-78-7). According to another preferred aspect, X represents SO2-G, where G represents an alkyl radical R, preferably the methyl radical, in which case the corrosion inhibitor (CAS No. 1 17933-98-9) is the reaction product of methane sulfonic acid (or its chloride) with nitrous acid.

[0016] According to one embodiment, X is chosen from:

. NO;

• an alkyl radical R, linear or branched, comprising from 1 to 6 carbon atoms;

• an aryl radical Ar optionally substituted, in particular by at least one alkyl radical R;

• a -SO 2 -G radical , where G represents H, OH, R, OR, OM, Ar, OAr, NH 2 , NHR and NRR ', where R and Ar are as defined above, R' represents an alkyl radical linear or branched, comprising from 1 to 6 carbon atoms, and M represents a mono- or bi-valent metal cation, preferably a cation of an alkali or alkaline earth metal; and

• a -CO-G radical, where G is as defined above.

The work of Y. Cètre ("Prevention and fight against corrosion", ISBN 2-88074-543-8, (2004), Presses polytechniques et universitaire romandes, Lausanne, CH, pp. 661 -676) have shown that the corrosion of stainless steel type AISI 304L by 70% sulfuric acid can be inhibited due to the presence of nitrosyl acid sulfate (NHS), a presence inherent in the sulfuric acid synthesis process.

SHN which is therefore known to be an inherent impurity in the preparation of sulfuric acid, is, in pure form, a very hygroscopic solid, unstable, reacting violently with water and producing toxic fumes (NO x ) in the presence of moisture.

Still other derivatives of nitrous acid, as well as nitrous acid itself, are unstable, just like SHN.

[0020] In addition, it is well known to those skilled in the art of metal corrosion that corrosion inhibitors are specific to an acid. For example, the corrosion inhibitors described in the literature and effective for the protection of stainless steels in sulfuric acid, are ineffective for phosphoric acid and increase the rate of corrosion in hydrochloric acid. Conversely, hydrochloric acid corrosion inhibitors are totally unsuitable for sulfuric acid.

The research work of the present inventors has made it possible to discover that certain nitrosylated derivatives exhibit an activity which inhibits the corrosion of metals by sulfonic acids, and more particularly by organosulphonic acids. The metals considered are more specifically steels, and in particular common stainless steels (for example of the AISI 304L and AISI 316L type), but also more generally any stainless steel as defined in standard NF EN 10088-1.

Thus, according to another aspect, the invention relates to a composition comprising at least one compound of formula (1) as defined above, and at least one sulfonic acid, as defined above, preferably at least one acid. organosulphonic, preferably at least one alkanesulphonic acid, more preferably AMS.

By effective amount is meant an amount of compound (s) of formula (1) between 1 ppm and a few percent, for example 10%, preferably between 5 ppm and 1000 ppm, more preferably between 10 ppm and 800 ppm, by weight relative to the total weight of the composition.

The present invention also relates to a process for protecting metals against corrosion by sulfonic acids, in particular passivable metals and alloys, in particular those based on iron, nickel, titanium, copper, aluminum, molybdenum, manganese, lead, and their alloys, as well as the couples (in the galvanic sense) of these metals or alloys of these metals or alloys obtained by contact (crimping, riveting, bolting, welding, brazing), characterized in that the sulfonic acid coming from in contact with said metals is a composition as defined above comprising at least one compound of formula (1) as defined above.

Said compounds of formula (1) are either commercially available or, when they are unstable, prepared according to known procedures or procedures available in scientific literature, patent literature or on the internet. When they are unstable, the compounds of formula (1) are advantageously prepared immediately before being added to the sulfonic acid, or the composition containing it.

For example, nitrosyl acid sulfate (SHN) can be obtained according to various methods known to those skilled in the art, including bubbling a stoichiometric mixture of nitric oxide (NO) and d dioxide nitrogen (NO2) in oleum (mixture H2SO 4 , SO3). The SHN thus obtained in solution in oleum can then be added directly to the sulfonic acid, or the composition containing it.

Thus, at least one compound of formula (1) can be added in at least one sulfonic acid, which it is desired to limit, or even prevent, the corrosive effect on metals, according to any method known per se, by simple addition , and possible mixing.

According to an alternative, the compound of formula (1) can be generated in situ by adding a precursor of the compound of formula (1) which, in contact with the sulphonic acid (s), is transformed into said compound of formula ( 1). Thus, for example, the compound O = N-OSO 2 CH 3 (CAS Reg. No. 1 17933-98-9) can be prepared by adding a mixture of nitrogen oxide / nitrogen dioxide in nitrogen. methane sulfonic acid.

In the present invention, by sulfonic acid is preferably meant the acids of formula R-SO3H, where R represents a saturated, linear or branched hydrocarbon chain, comprising from 1 to 4 carbon atoms, or an aryl radical optionally substituted by a saturated linear or branched hydrocarbon chain comprising from 1 to 4 carbon atoms and optionally substituted, in whole or in part, by one or more halogen atoms, which are identical or different.

The saturated hydrocarbon chain, linear or branched, comprising from 1 to 4 carbon atoms can be substituted, in whole or in part, by one or more halogen atoms chosen from fluorine, chlorine and bromine, and in particular, the hydrocarbon chain possibly being perhalogenated, more particularly perfluorinated.

By "aryl" is meant an aromatic radical, preferably phenyl or naphthyl, more preferably phenyl.

[0032] Thus, and in a nonlimiting manner, the sulphonic acids included in the context of the present invention are organosulphonic acids preferably chosen from methanesulphonic acid, ethanesulphonic acid, acid n -propanesulfonic acid, / ' so-propanesulphonic acid, n-butanesulphonic acid, / ' so-butanesulphonic acid, sec-butanesulphonic acid, terf- butanesulfonic acid, trifluoromethanesulfonic acid, para-toluenesulfonic acid, benzenesulfonic acid and mixtures of two or more of them in all proportions.

According to a very particularly preferred embodiment, the sulfonic acid used in the context of the present invention is methanesulfonic acid, ethanesulfonic acid, trifluoromethanesulfonic acid or para-toluenesulfonic acid. , most preferably the sulfonic acid used is methanesulfonic acid. The compositions according to the present invention comprising at least one sulfonic acid and an effective amount of at least one corrosion inhibitor of formula (1) are acidic compositions which can be used in any field where said sulfonic acids are usually used. As indicated above, the acidic compositions according to the invention have the advantage of being less corrosive, or even non-corrosive,

The compositions according to the present invention can be of any type, liquid, in more or less dilute aqueous solutions, or else in the form of gels or foaming gels, the viscosities of which can vary widely.

[0036] According to one embodiment, the compositions according to the present invention are used in pure or diluted form with the aid of various components, as indicated below.

As a general rule, the compositions comprise from 0.01% to 100% by weight of sulphonic acid (s) in combination with at least one corrosion inhibitor of formula (1) defined above, more generally of 0.05% to 90% by weight, in particular from 0.5% to 75% by weight, relative to the total weight of said composition, the remainder of the composition comprising a solvent and / or a diluent, preferably a solvent and / or aqueous diluent, more preferably water, and optionally one or more additives, as defined later in the present description.

According to a preferred embodiment, the composition of the present invention comprises at least one sulfonic acid chosen from methane-sulfonic acid, ethane-sulfonic acid, n-propane-sulfonic acid, acid. / ' so-propane-sulfonic acid, n-butane-sulfonic acid, / 'so-butanesulfonic acid, sec-butane-sulfonic acid, terf-butanesulfonic acid, trifluoromethanesulfonic acid, para-toluenesulfonic acid, benzenesulfonic acid and mixtures of two or more d 'between them in all proportions, preferably from methanesulfonic acid, ethanesulfonic acid, trifluoromethanesulfonic acid and para-toluenesulfonic acid, most preferably methane-sulfonic acid, in association with at least one corrosion inhibitor compound of formula O = N-OX, where X is chosen from H, NO, an alkyl radical R, linear or branched, comprising from 1 to 6 carbon atoms and an -SO2-G radical or -CO-G, where G represents OH or R as defined above, the sulfonic acid and corrosion inhibitor group representing 0,05% to 90% by weight, in particular from 0.5% to 75% by weight, of the total weight of said composition, the remainder of the composition being water.

According to a very particularly preferred embodiment, the composition of the present invention comprises methanesulphonic acid, nitrosyl acid sulphate and water.

The compositions according to the present invention can optionally comprise one or more additives or auxiliaries commonly used in the field concerned and according to the targeted applications.

Examples of additives and auxiliaries include, without limitation, viscosity modifiers, rheology, foaming agents, anti-foaming agents, surfactants, and the like, disinfectants, biocides, stabilizers, oxidizing agents , enzymes, pigments, dyes, flame retardants, flame retardant, and the like.

[0042] Thus, according to the envisaged uses, and if this is desirable or necessary, the compositions according to the invention can thus comprise one or more additives, such as those chosen from:

• solvents, hydrotropic agents or solubilizers (eg alcohols, esters, ketones, amides, and others);

• biocides, disinfectants (bromo-acetic acid, peracetic acid, hydrogen peroxide, chlorine dioxide, chlorine, bromine, and others);

• rheological, texturizing, thickening, gelling agents (sugars, polysaccharides, alginates, silica, amorphous silica, gums and others);

• complexing agents;

• organic or mineral acids (eg sulfuric, phosphoric, nitric, sulfamic, acetic, citric, acetic, ascorbic, formic, lactic, glycolic, oxalic and others);

• flame retardants;

• preservatives;

• anionic, cationic, nonionic or amphoteric surfactants (such as ethoxylated alcohols and / or amines, alkyl- and / or aryl-sulfonates), emulsifiers, detergents, soaps, and others;

• foaming agents, anti-foaming agents;

• anti-freezes (eg ethylene glycol, propylene glycol, and others);

• dyes, pigments;

• perfumes, odorous agents;

and other additives known to those skilled in the art.

Among the complexing agents optionally present in the compositions according to the invention, there may be mentioned in particular the complexing agents of metals, for example organic complexing agents, such as ethylenediaminetetra-acetic (EDTA), diethylenetriaminepenta- acid. acetic (DTPA), (2-hydroxyethyl) -ethylenediaminetriacetic acid (HEDTA), methylglycinediacetic acid (MGDA) or even nitrilotriacetic acid (NTA).

According to a preferred embodiment of the invention, the compositions can comprise one or more other acids, organic or inorganic, among which there may be mentioned, by way of nonlimiting examples, phosphoric acid, acid sulfuric, nitric acid, carboxylic acids such as sulfamic, citric, oxalic, glycolic, acetic, ascorbic, formic, lactic acids and mixtures of two or more of them, in all proportions.

Among the solubilizing or hydrotropic agents which can be used in the formulations according to the invention, there may be mentioned, by way of example and without limitation, sodium xylene or cumenesulphonates. However, such agents are not essential in the compositions of the invention.

The amounts of additives and / or auxiliaries in the compositions of the invention can vary widely and will be easily adjusted by those skilled in the art according to the specific applications envisaged.

In general, the compositions according to the present invention are in the form of an aqueous, organic or even hydro-organic formulation, which can be prepared in the form of a concentrated, concentrated mixture which can be diluted with water by the final user. Alternatively, the formulation can also be a ready-to-use formulation, i.e. it does not need to be diluted.

[0048] According to another aspect, the compositions of the present invention can be formulated in the form of gels or foaming gels.

[0049] In the case of formulations in the form of gel or foaming gel, the use of at least one ethoxylated amine oxide, such as, in a nonlimiting manner the Cecajel ® OX100 from CECA, or "Aromox ® T12 from Akzo alone or combination with at least one oxide of dimethylalkylamine helps provide stability to the gel, in particular foaming gel.

An aqueous, organic or hydro-organic formulation, in the form of a solution, a gel or else in the form of a foaming gel, which is particularly preferred is a formulation comprising from 0.01% to 97%, preferably from 0.05% at 75%, more preferably from 0.5% to 70% by weight of methanesulfonic acid, combined with at least one compound of formula (1) as defined above.

Depending on the field and the mode of application, the formulation can be prepared in the form of a concentrate, and with an appropriate viscosity, then diluted before use until the expected efficiency is obtained, as regards the viscosity and possibly the power. foaming.

The compositions of the present invention can for example be prepared from commercial acid solutions, and by way of nonlimiting examples from methanesulfonic acid in aqueous solution marketed by the company Arkema under the name Scaleva ® , or under the name Lutropur ® marketed by BASF, ready for use or diluted with water in the proportions indicated above.

[0053] According to one aspect of the present invention, the compositions comprising at least one sulfonic acid and at least one corrosion inhibitor of formula (1) as defined above further comprise a disinfectant, in particular chlorine dioxide.

According to a preferred embodiment, the chlorine dioxide can be generated in situ by adding sodium chlorite to the composition of the invention. Sodium chlorite, in contact with a sulfonic acid, such as for example AMS, is converted into chlorine dioxide, a disinfecting agent, as indicated in patent application WO 2002/46095.

The compositions according to the present invention further comprising a disinfecting agent as indicated above find very particularly interesting applications for the cleaning and disinfection of cooling water circuits, the disinfection of sanitary water and for disinfecting equipment. hospital.

According to another aspect, the compositions according to the invention find a very particularly advantageous use in the storage of sulfonic acids, or solutions, in particular aqueous, of sulfonic acids. Indeed, the presence, in said compositions of the present invention, of at least one corrosion inhibitor agent makes it possible to dispense with plastic coating films, which are generally used for the storage of said acids in metal tanks, in particular in stainless steel tanks.

Another advantage of the compositions according to the present invention is their very good storage stability, as well as their very good temperature stability. Thus the compositions of the invention, which can be used in many fields of application, can in particular be implemented in chemical reactions, requiring the use of sulfonic acids and carried out in metal reactors, at temperatures for example between -10 ° C and 200 ° C.

More generally, the compositions according to the present invention find applications in all fields where acidic compositions are required, in particular aqueous acidic solutions coming into contact with the metals mentioned above and for which it is desired to limit or avoid corrosion.

Such fields of application are, for example and without limitation, storage, catalytic reactions (such as esterification reactions in acid catalysis), cleaning, descaling, detergency, pickling, electroplating, surfacing ("plating" in English, especially in the electronic field), and others.

By way of nonlimiting examples, the fields of application are the pickling, cleaning, descaling and detergency of mineral and / or organic soiling in the food industries, such as dairies, cheese factories, packaging of early and meat products, breweries, as well as the stripping, cleaning and descaling of mineral residues, in cement factories, in all areas where it is necessary and desirable to remove rust, or in oil and gas operations where acidic solutions are required for the dissolution of subterranean rocks, especially carbonate rocks.

The fields of application targeted by the compositions according to the present invention are all fields where at least one sulphonic acid is stored or conveyed in containers, drums, vats, receptacles, reactors, fermenters, pipes, pipes, tubes, valves, liable to be corroded and whose corrosion it is desired to limit or even avoid.

According to another aspect, the present invention relates to the use of a composition comprising at least one sulfonic acid and at least one corrosion inhibitor of said (or said) sulfonic acid (s) as defined above for the storage of said acids, catalytic reactions or even cleaning, descaling, detergency, pickling, disinfection, electroplating, surfacing, catalytic reactions, and others, at temperatures varying from -10 ° C to 200 ° C , preferably 0 ° C to 160 ° C.

The compositions according to the present invention, whether in liquid form, of gels or of foaming gels, concentrated or diluted, can be applied according to any method known to those skilled in the art, and in particular under pressure, or again using a spray gun.

As indicated above, the sulfonic acid comprising the corrosion inhibitor defined above is advantageously implemented in the form of a formulation, for example aqueous, organic or hydro-organic formulation, in liquid, gel or gel form. foaming gel, as defined above.

The present invention is now illustrated by means of the examples which follow, without presenting any limiting nature, and which cannot therefore be understood as capable of restricting the scope of the invention as claimed.

Example 1: Protocols for electrochemical tests

The electrochemistry test is carried out using a conventional assembly with 3 electrodes (reference electrode (ECS saturated calomel electrode), working electrode made of the material to be studied and platinum counter-electrode ) connected to a BIOLOGIC VMP3 or EGG 273A potentiostat.

The specimen of the material to be tested is polished with P1000 abrasive paper, in order to have a reproducible initial state, then left in the open air for at least 24 hours.

The working electrode is installed on a rotating system which makes it possible to fix the speed of rotation: the speed of rotation is set at 1000 revolutions per minute.

Several types of tests using this assembly were used during this study: • Potentio-kinetic (or voltammetric) sweep I = f (E): the variation of the potential E of the material and the measurement of the current I between it and the counter-electrode makes it possible to estimate the behavior of the material in the environment: quality of the passive layer, estimation of the corrosion rate (Tafel method at corrosion-free potential and direct reading of the current measured at other potentials), etc. .

• Monitoring of the abandonment potential (or potential-time curve) of the material as a function of time E = f (t): monitoring the abandonment potential of a stainless material allows to know if the material is passive (negligible corrosion ) or active (passive layer destroyed, significant corrosion) provided that the potentiokinetic polarization curve has been drawn beforehand. This type of test also makes it possible to follow the behavior of the material according to the conditions present in the environment: influence of deaeration, temperature, addition of inhibitors, etc.).

Example 2: Electrochemical test showing the persistence of the effect of the inhibitor

[0070] The long term effect of inhibition by NHS in 70% AMS (Scaleva ® , Arkema) is demonstrated by monitoring the corrosion potential versus time at 40 ° C.

A 316L stainless steel specimen of dimensions 35 x 23 x 3 mm is in standard condition (polished P320 and passivated in air for at least 24 hours).

• When immersed in 70% AMS at 40 ° C, the 316L stainless steel test piece is immediately depassivated (potential around -250 mV / ECS).

• The addition of 400 ppm of SHN in the medium, passive the 316L stainless steel of the test piece: the potential becomes greater than 500 mV / ECS.

• After 21 days in these conditions the 316L is still passive (potential greater than 500 mV / ECS).

Figure 1 shows the passivation curve as a function of time: at time t = 0, the 316L stainless steel test piece is immersed in a 70% AMS solution (Scaleva ® , Arkema) at 40 ° C. . 316L stainless steel becomes active upon immersion. At t = 1200 seconds, 400 ppm SHN (via an approximately 60% solution of SHN in sulfuric acid) is added using an automatic micropipette, into the acid solution to 40 ° C. 316L stainless steel becomes passive immediately.

The nitrosyl acid sulfate used here is a 60% by weight solution in sulfuric acid prepared by bubbling a 1/1 stoichiometric mixture of nitric oxide (NO) and nitrogen dioxide (NO2) (70 g and 110 g respectively), in 830 g of oleum (H 2 SO / SO 3 mixture: 77/23 by weight).

After 21 days, the steel specimen is still passivated, indicating an absence of corrosion, even after this period of time.

Example 3: Persistence of the inhibitory effect despite the worsening of the test conditions (Temperature effect: 90 ° C)

This test consists of monitoring the corrosion potential as a function of time:

• The sample of freshly polished 316L stainless steel is immersed in AMS 70% Scaleva ® + 100 ppm SHN at 40 ° C: the sample immediately becomes passive.

• The temperature of the medium is gradually increased in increments of 10 ° C: after 5 days, the medium is at 90 ° C: 316L stainless steel is still passive.

• After 460 hours (approximately 19 days), the sample is still passive.
Claims

1. Use of at least one compound of general formula (1):

O = N-OX (1),

in which X is chosen from:

• H;

. NO;

• an alkyl radical R, linear or branched, comprising from 1 to 6 carbon atoms;

• an aryl radical Ar optionally substituted, in particular by at least one alkyl radical R;

• a -SO 2 -G radical , where G represents H, OH, R, OR, OM, Ar, OAr, NH 2 , NHR and NRR ', where R and Ar are as defined above, R' represents an alkyl radical linear or branched, comprising from 1 to 6 carbon atoms, and M represents a mono- or bi-valent metal cation, preferably a cation of an alkali or alkaline earth metal; and

• a -CO-G radical, where G is as defined above,

to limit, or even prevent, corrosion of metals by sulfonic acids.

2. Use according to claim 1, in which X represents -SO2-G, preferably -SO2-G where -G represents -OH or R, R representing an alkyl radical, preferably a methyl radical.

3. Use according to claim 1 or claim 2, in which the sulfonic acid is an acid of formula R-SO3H, where R represents a saturated, linear or branched hydrocarbon chain, comprising from 1 to 4 carbon atoms, optionally substituted. , in whole or in part, by one or more halogen atoms, identical or different, or an aryl radical optionally substituted by a saturated, linear or branched hydrocarbon chain, comprising from 1 to 4 carbon atoms, optionally substituted, in full or in part, by one or more halogen atoms, which are identical or different.

4. Use according to any one of the preceding claims, in which the sulfonic acid is chosen from methanesulfonic acid, ethanesulfonic acid, n-propane-sulfonic acid, acid / ' so -propanesulphonic acid, n-butanesulphonic acid, / ' so-butanesulphonic acid, sec-butanesulphonic acid, terf-butanesulphonic acid, trifluoromethanesulphonic acid, para-toluenesulfonic acid, benzenesulfonic acid and mixtures of two or more of them in all proportions, preferably the sulfonic acid is chosen from methane-sulfonic acid, ethanesulfonic acid, acid trifluoromethanesulfonic and para-toluenesulfonic acid,most preferably the sulfonic acid is methanesulfonic acid.

5. Composition, in the form of an aqueous formulation, comprising at least one compound of formula (1) as defined in any one of claims 1 or 2, and at least one sulfonic acid as defined in any one of claims. 3 or 4, preferably at least one alkanesulfonic acid, more preferably AMS.

6. Composition according to claim 5, in which the amount of compound (s) of formula (1) is between 1 ppm and 10%, preferably between 5 ppm and 1000 ppm, more preferably between 10 ppm and 800 ppm, by weight relative to the total weight of the composition.

7. Composition according to any one of claims 5 or 6, comprising from 0.01% to 100% by weight of sulfonic acid (s) in combination with at least one corrosion inhibitor of formula (1) according to any one of claims 1 or 2, more generally from 0.05% to 90% by weight, in particular from 0.5% to 75% by weight, relative to the total weight of said composition, the remainder of the composition comprising a solvent and / or a diluent, preferably an aqueous solvent and / or diluent, more preferably water, and optionally one or more additives.

8. Composition according to any one of claims 5 to 7, comprising at least one sulfonic acid selected from methanesulfonic acid, ethanesulfonic acid, n-propane-sulfonic acid, acid / ' so-propane-sulfonic acid

n-butane-sulfonic acid, / ' so-butane-sulfonic acid, sec-butane-sulfonic acid, terf-butane-sulfonic acid, trifluoromethanesulfonic acid, para-toluenesulfonic acid, benzenesulfonic acid and mixtures of two or more of them in all proportions, preferably methanesulfonic acid, in combination with at least one corrosion inhibitor compound of formula O = N-OX, where X is chosen from H, NO, an alkyl radical R, linear or branched, comprising from 1 to 6 carbon atoms and an -SO2-G or -CO-G radical, where G represents OH or R as defined above, the sulfonic acid group and corrosion inhibitor representing from 0.05% to 90% by weight, in particular from 0.5% to 75% by weight, of the total weight of said composition,the rest of the composition being water.

9. A composition according to any one of claims 5 to 8, comprising methanesulfonic acid, acid nitrosyl sulfate and water.

10. Composition according to any one of claims 5 to 9, further comprising one or more additives chosen from:

• solvents, hydrotropic or solubilizing agents,

• biocides, disinfectants (bromo-acetic acid, peracetic acid, hydrogen peroxide, chlorine dioxide, chlorine, bromine, and others),

• rheological, textural, thickening and gelling agents,

• complexing agents;

• organic or mineral acids;

• flame retardants,

• preservatives,

• anionic, cationic, nonionic or amphoteric surfactants (such as ethoxylated alcohols and / or amines, alkyl- and / or aryl-sulfonates), emulsifiers, detergents, soaps, and others;

• foaming and anti-foaming agents,

• anti-freezes (eg ethylene glycol, propylene glycol, and others);

• dyes, pigments; and

• perfumes, odorous agents.

11. A method of protecting metals against corrosion by sulfonic acids, in particular passivable metals and alloys, characterized in that the sulfonic acid coming into contact with said metals is a composition according to any one of claims 5 to 10. .

12. The method of claim 11, wherein the metal is selected from stainless steels or alloys iron base or nickel base, titanium, copper, aluminum, molybdenum, manganese, lead and their alloys, as well as than the couples (in the galvanic sense) of these metals or alloys.

13. Use of a composition according to any one of claims 5 to 10 for storage, catalytic reactions or even cleaning, descaling, detergency, pickling, disinfection, electroplating, surfacing, catalytic reactions. , and the like, at temperatures varying from -10 ° C to 200 ° C, preferably from 0 ° C to 160 ° C.

14. Use according to claim 13, for stripping, cleaning, descaling and detergency of mineral and / or organic soiling in food industries such as dairies, cheese factories, packaging of early vegetables and meat products, breweries, as well as the stripping, cleaning, and descaling of mineral residues, in cement plants, in all areas where it is necessary and desirable to remove rust, or in oil and gas operations where acid solutions are necessary for the dissolution of rocks underground, particularly carbonate rocks.

15. Use according to one of claims 13 or 14, to limit, or even avoid, the corrosion of containers, drums, vats, receptacles, reactors, fermenters, pipes, pipes, tubes, valves, where at least one sulphonic acid is stored. or conveyed.