EA039954B1 - SYNERGETIC ACETAL COMPOSITIONS AND METHOD FOR RECOVERY OF SULFIDES AND MERCAPTANS - Google Patents

Abstract

The invention describes a composition comprising: I) at least one reaction product between a nitrogen-free monohydric alcohol and an aldehyde, II) at least one reaction product between a nitrogen-free polyhydric alcohol and an aldehyde and optionally III) at least one reaction product of IIIa) formaldehyde and IIIb) ammonia and/or an amine selected from the group consisting of primary alkylamines having from 1 to 4 carbon atoms and primary hydroxyalkylamines having from 2 to 4 carbon atoms and optionally IV) at least one solids suppressant selected from the group consisting of IV(a) alkali or alkaline earth metal hydroxides, IV(b)) ammonia; alkyl-, aryl- or alkylarylamines, IV(c)) hydroxyalkyl-, hydroxyaryl- or hydroxyalkylarylamines, IV(d)) multifunctional amines containing, in addition to the amino group, at least one additional functional group selected from the group consisting of amino groups, ether groups and acid groups, and their ester, amide or salt, and IV(e)) mixtures of compounds of groups IV(a)-IV(c), where alkyl is C1-C20-alkyl, aryl is C6-C20-aryl, and alkylaryl is C7-C20alkylaryl

Description

The invention relates to a composition and method for trapping (capturing) hydrogen sulfide from liquids and/or gas using a synergistic combination of acetals with a reaction product of formaldehyde and amines and a solids suppression agent. Compositions containing the composition of the invention are particularly well suited for scavenging hydrogen sulfide and/or mercaptans while preventing the formation of undesirable emulsions and/or precipitation of undesirable by-products often associated with the use of chemicals and/or formulations of the prior art.

The presence of compounds containing a sulfhydryl group (-SH), and in particular hydrogen sulfide, creates problems in many industries. The presence of such compounds can create serious health, safety and environmental problems. There are many different types of compounds containing a sulfhydryl group (sulfhydryl compounds). The most commonly encountered molecules of this type include hydrogen sulfide (H2S), organosulfur compounds containing R-SH groups (also called mercaptans), thiocarboxylic acids RC(O)SH, dithiocarboxylic acids RC(S)SH, and related compounds.

In the oil and gas industry, the content of H2S in crude oil and natural gas in many areas of the world is high enough that it poses a threat to the environment and safety. Hydrogen sulfide is a flammable, corrosive and highly toxic gas. H ₂ S is the most reduced form of sulfur and is produced by sulfate reducing bacteria (SRB), which are often found in anaerobic oil fields, or formed by thermal cracking and thermochemical sulfate reduction (TSR) by hydrocarbons. When crude oil is produced, depressurization occurs and dissolved H2S is released and then it can pass into, for example, oil drilling fluid during the drilling process, and this can become hazardous as the drilling fluid is recirculated from the well to the surface. During the production of crude oil and natural gas, H2S gas can pose a significant risk to production integrity because it is an acid gas and when dissolved in produced water creates a highly corrosive environment. In addition, the presence of H ₂ S increases the risk of sulfide stress corrosion cracking, hydrogen embrittlement, and pitting in some structural materials, and H ₂ S must be removed for safe handling of liquids and gases.

The odor of sulfhydryl compounds is also a problem, for example in metalworking environments, but equally in water treatment processes, whether in tap water (e.g. in waste water treatment) or industrial effluents (e.g. in mine water recycling). ). SRBs are often present in fluid recirculation systems, and while bacteria can usually be controlled with biocidal compositions, control of the biology in the system is often lost, resulting in the formation of hazardous H2S and/or mercaptans in the system. In addition, biocides are not effective in removing H2S after it has been formed, and result in only minor removal, either through oxidation (eg with sodium hypochlorite) or by releasing small amounts of aldehyde during their degradation (eg with glutaraldehyde). Sulfhydryl compounds and especially H ₂ S can present problems in terms of environmental, toxicity and integrity in gaseous phases in confined spaces, for example in wastewater treatment plants and especially in containers for the transport and storage of moisture sensitive materials, which can release H2S, which can accumulate in the gas free space. It is necessary to have an acceptor that will reduce the concentration of H ₂ S in such places.

The most commonly used sulfhydryl acceptors are based on metals such as copper, zinc or iron, which are converted to insoluble sulfides. A number of alternative non-metal methods have been proposed for removing hydrogen sulfide and controlling sulfhydryl odors in hydrocarbon containing systems, including:

WO-98/02501 describes the use of bis-oxazolidines obtained by the reaction of 1,2 or 1,3 amino alcohols containing from 3 to 7 carbon atoms with aldehydes containing 4 or less carbon atoms, such as 3,3'- methylenebis-5-methyloxazolidine. The relative oil and water solubility of these products can be controlled by the choice of starting materials. These bis-oxazolidines react with sulfhydryl compounds present in oil and gas streams, resulting in their neutralization and hence removal.

US-5,347,004 describes the use of the reaction products of an alkoxyalkyleneamine, optionally mixed with ammonia and/or alkylamines with aldehydes, to remove H ₂ S from gas streams that are bubbled into aqueous solutions of the reaction products.

WO-2014/031537 describes the use of an aldehyde releasing compound, preferably hydantoin, to remove sulfhydryl compounds from hydrocarbon liquids.

US-3,928,211 describes the use of inorganic zinc salts (most preferably zinc carbonate), preferably dispersed in aqueous or non-aqueous oil well drilling fluids with an organic dispersant such as lignin-containing materials, to capture hydrogen sulfide in aqueous drilling fluids.

WO-2002/051968 describes a method for reducing the level of hydrogen sulfide in a liquid or gas by

- 1 039954 liquid or gas with an H2S binding product obtained from the reaction of a compound containing a carbonyl group with an alcohol, thiol, amide, thioamide, urea or thiourea. The carbonyl group-containing compound is preferably formaldehyde, and preferably the product can be obtained by reacting formaldehyde with an amine-free alcohol or urea selected from ethylene glycol, propylene glycol, glycerol, diethylene glycol, triethylene glycol, ethyl alcohol, n-butanol, sugar, low molecular weight polyvinyl alcohol , fatty acid castor oil and urea. More specifically, the capture product is used with an amine, especially monoethanolamine or monoethanolaminetriazine.

US-4,978,512 describes a method for lowering H2S levels, comprising contacting an H2S containing medium with, inter alia, acetals and bis-oxazolidines.

It is an object of the present invention to provide compositions that can be used to remove sulfhydryl compounds from crude oil, gas production, water production, water injection, and combinations thereof, the sulfhydryl compounds being preferably, but not limited to, H2S and/or mercaptans. only this. The compositions of the invention should have improved safety and efficacy compared to prior art formulations and chemicals, i.e. they should contain low levels of toxic substances such as formaldehyde, even after prolonged storage; have a higher capture efficiency, especially for the treatment of gases, such as natural gas; provide effective capture of sulfhydryl compounds in a short contact time. In addition, it is necessary to have an acceptor that does not form undesirable solid by-products and/or does not form emulsions that can unintentionally contaminate the very systems they are treated with.

Surprisingly, a composition comprising at least one reaction product between a monohydric alcohol and an aldehyde and at least one reaction product between a polyhydric alcohol and an aldehyde has been found to improve the capturing capacity of sulfhydryl compounds compared to the reaction products of individual alcohols. Such a composition allows: (i) to lower the dose level of the scavenger to obtain the same level of residual sulfhydryl compound, and/or (ii) to achieve a lower level of residual sulfhydryl compound with the same dose level of the scavenger. In addition, in combination with at least one formaldehyde-amine reaction product (hereinafter also referred to as a synergist), the H2S and/or mercaptan removal kinetics provided by the reaction products of a monohydric alcohol and a polyhydric alcohol with an aldehyde can be significantly accelerated. Alternatively, or in addition to the first two components of the composition, the addition of a solids suppressant as an additional synergistic additive aids in the removal of sulfhydryl reaction products in continuous purification processes. In addition, such an additive prolongs the gas breakthrough time of sulfhydryl compounds in the contact tower containing the reaction product of monohydric alcohol and polyhydric alcohol with aldehyde.

The use of the synergist and/or additional synergist of the invention allows mixed hemiacetals and acetals to react much more efficiently with sulfhydryl compounds and especially with H2S. The mechanism believed to be involved in this reaction, but which should not be construed as limiting the invention in any way, is based on the possibility that the synergistic component preferentially reacts with H2S to form an intermediate reaction complex which then, in turn, reacts with the hemiacetal or acetal molecule, reforming the synergist molecule and releasing the corresponding alcohol present in the acetal. After the H2S removal process, the residual synergist acts as a corrosion inhibitor, protecting the integrity of pipelines and equipment in which it is used.

Within the scope of this application, the expressions hemiacetal and acetal cover the reaction products of an alcohol with an aldehyde. The expression (hemi)acetals covers hemiacetals, acetals and mixtures thereof, which are often formed during the reaction of alcohols and carbonyl compounds.

In a first aspect of the invention, a composition is disclosed comprising:

I) at least one reaction product between a nitrogen-free monohydric alcohol and an aldehyde, and

II) at least one reaction product between a nitrogen-free polyhydric alcohol and an aldehyde.

In a second aspect of the invention, a composition is disclosed comprising:

I) at least one reaction product between a nitrogen-free monohydric alcohol and an aldehyde, and

ii) at least one reaction product between a nitrogen-free polyhydric alcohol and an aldehyde, and

iii) at least one reaction product of formaldehyde and ammonia and/or amine selected from the group consisting of primary alkylamines having from 1 to 4 carbon atoms and primary hydroxyalkylamines having from 2 to 4 carbon atoms.

In a third aspect of the invention, a composition is disclosed comprising:

I) at least one reaction product between a nitrogen-free monohydric alcohol and

- 2 039954 aldehyde,

ii) at least one reaction product between a nitrogen-free polyhydric alcohol and an aldehyde,

iii) at least one reaction product of formaldehyde and ammonia and/or amine selected from the group consisting of primary alkylamines having from 1 to 4 carbon atoms and primary hydroxyalkylamines having from 2 to 4 carbon atoms, and

IV) at least one inorganic or organic alkaline compound that functions as a solids suppressant.

A fourth aspect of the invention discloses the use of the composition of the first, second or third aspect of the invention as a scavenger for sulfhydryl compounds for use in oilfield operations and process systems.

In preferred embodiments of the invention, at least one demulsifier (V) and/or corrosion inhibitor (VI) is present in any aspect of the invention.

Group I

The group I compound is the reaction product of a monohydric alcohol and an aldehyde. Monohydric alcohol does not contain nitrogen.

Preferred monohydric alcohols used as starting materials are alkyl, aryl and arylalkyl alcohols containing one hydroxy group and from 1 to 15 carbon atoms, more preferably from 1 to 10 carbon atoms, and especially from 2 to 5 carbon atoms, for example from 1 up to 5, 2 to 15 or 2 to 10 carbon atoms. The hydroxyl group of preferred alcohols is linked to an aliphatic, alicyclic and/or aromatic moiety, preferably an aliphatic, alicyclic and/or aromatic hydrocarbon moiety, and more specifically to an aliphatic or cycloaliphatic moiety. Aliphatic and cycloaliphatic components may be saturated or unsaturated, preferably they are saturated. Aliphatic components with 3 or more carbon atoms may be linear or branched. More specifically, the monohydric alcohol may be aliphatic. In particular, the alcohol may be an alkyl alcohol. Examples of preferred alcohols are methanol, ethanol, propanol, isopropanol, n-butanol, isobutanol, t-butanol and the various isomers of pentanol, hexanol, heptanol and octanol, such as 2-ethylhexanol, and mixtures thereof. Particularly preferred are methanol and ethanol.

Preferred aldehydes used as starting materials contain one or more carbonyl groups, more preferably one or two carbonyl groups, and particularly preferably one carbonyl group. In addition, preferred aldehydes contain 1 to 10 carbon atoms, more preferably 1 to 7, and particularly preferably 1 to 4 carbon atoms. In preferred aldehydes, the carbonyl group bears one aliphatic, alicyclic and/or aromatic substituent, more preferably an aliphatic, alicyclic and/or aromatic hydrocarbon substituent. Preferred aliphatic and cycloaliphatic substituents may be saturated or unsaturated, most preferably they are saturated.

In a preferred embodiment, the carbonyl compound is an aldehyde, more preferably mono- or dialdehyde, and particularly preferably formaldehyde. The terms aldehyde and formaldehyde are to be understood to include precursors such as, for example, paraformaldehyde, formalin, and other chemical forms from which the basic HCHO structure can be released during reaction with an alcohol. Other suitable aldehydes include, for example, acetaldehyde, propionaldehyde, butyraldehyde, glutaraldehyde and glyoxal.

If necessary, mixtures of two or more carbonyl compounds can be used, for example two or more of the aldehydes mentioned above, for example formaldehyde and one or more other aldehydes.

In the reaction between a monohydric alcohol and an aldehyde, some or all of the alcohols may be converted to hemiacetals and/or acetals. In a preferred embodiment, the reaction product is a hemiacetal. In a preferred embodiment, at least 50 mole % alcohol, more preferably 60 to 99 mole % alcohol, especially 65 to 95 mole % alcohol, and particularly preferably 70 to 90 mole % alcohol, which corresponds, for example, to more than 60 mol.%, more than 65 mol.%, more than 70 mol.% alcohol or from 50 to 99 mol.%, from 50 to 95 mol.%, from 50 to 90 mol.%, from 60 to 95 mol.% , from 60 to 90 mol.%, from 65 to 99 mol.%, from 65 to 90 mol.%, from 70 to 99 mol.% or from 70 to 95 mol.% alcohol, turns into hemiacetals and/or acetals. If the degree of conversion is low, some unreacted monohydric alcohol remains in the composition. The presence of residual alcohol in the reaction mixture proved to be advantageous, since its reaction with sulfhydryl compounds often reduces the formation of a solid precipitate. In addition, the remaining alcohol will act as a solvent.

Group II.

The group II compound is the reaction product of a polyhydric alcohol and an aldehyde.

- 3 039954

Polyhydric alcohol does not contain nitrogen.

Preferred polyhydric alcohols used as starting materials contain from 2 to 20 carbon atoms and two or more hydroxyl groups. The preferred polyhydric alcohol contains from 2 to 6, more preferably from 3 to 6 hydroxyl groups. Preferred polyhydric alcohols contain 2 to 50, more preferably 2 to 20 and especially 3 to 10 carbon atoms, eg 2 to 10 carbon atoms, 3 to 50 carbon atoms or 3 to 20 carbon atoms. Preferably they are aliphatic. Examples of preferred polyhydric alcohols are ethylene glycol, propylene glycol, butylene glycol, pentanediol, neopentyl glycol, hexanediol, glycerin, pentaerythritol, diethylene glycol, triethylene glycol, glycerol oligomer with 215 and especially 3-10, such as with 2-10 or 3-15 repeating units, the molecule sugar (ie, a monosaccharide or disaccharide compound) or low molecular weight polyvinyl alcohol so that the reaction product with the carbonyl starting material remains a liquid. Preferably, the number of hydroxyl groups in the polyhydric alcohol is lower or does not exceed the number of carbon atoms. The most preferred polyols are ethylene glycol and glycerin.

The preferred aldehydes used as starting materials for Group II compounds are those already described above with respect to Group I. The most preferred aldehyde for Group II compounds is formaldehyde. The aldehyde used to react with the polyhydric alcohol may be the same as that used for the monohydric alcohol, or it may be different.

In the reaction between a polyhydric alcohol and an aldehyde, some or all of the hydroxyl groups can be converted to hemiacetals and/or acetals. In a preferred embodiment, at least 50 mole % hydroxyl groups, more preferably 60 to 99 mole % hydroxyl groups, especially 65 to 95 mole % hydroxyl groups, and particularly preferably 70 to 90 mole % hydroxyl groups, e.g. more than 60 mol.%, more than 65 mol.%, more than 70 mol.% alcohol or from 50 to 99 mol.%, from 50 to 95 mol.%, from 50 to 90 mol.%, from 60 to 95%, from 60 to 90 mol%, 65 to 99 mol%, 65 to 90 mol%, 70 to 99 mol% or 70 to 95 mol% of the hydroxyl groups are converted to hemiacetals and/or acetals. If the degree of conversion is low, unreacted polyhydric alcohol remains in the composition. The presence of residual hydroxyl groups in the reaction mixture turned out to be advantageous, since their reaction with sulfhydryl compounds reduces the formation of a solid precipitate.

In a particularly preferred embodiment, the reaction product is predominantly a hemiacetal derived from a polyhydric alcohol. Particularly preferred are reaction products in which the ratio between hemiacetals and acetals on a molar basis is from 50:1 to 1:10 and preferably from 20:1 to 1:2, for example from 50:1 to 1:2 or from 20:1 until 1:10.

Preferred polyhydric hemiacetal compounds that can be used as an acceptor are described by structures (2)-(5) below:

Where

R1 is H or C ₁ -C ₈ -alkyl and

R2 is H or CH2OH;

HO^^O--(CH ₂ ) _P --O--R ₂ (2a) where p is a number from 2 to 10 and

R2 is H or CH2OH;

where ^R ⁴

BUT (3)

OR ³

R ₃ and R 4 are independently H or CH2OH;

where m is from 1 to 10, preferably 1 or 2.

Most preferred are structures derived from either glycerol or ethylene glycol. They correspond to formulas (3) and (4), or formula (2), where R1 is H.

In another specific preferred embodiment, the hemiacetal may have the structure shown below.

- 4 039954

Where

R5 is H, CH3, (CH2) _z CH ₃ , with the proviso that not all of R ₅ are hydrogen, z is 1 to 10, and x is 1 to 5.

The reactions of aldehydes and ketones with alcohols are described in the literature. Formaldehyde, p. 265, Joseph Frederic Walker, reprint 1975, Robert E. Krieger Publishing Company Inc. discloses that hemiacetals are produced when formaldehyde and alcohols are combined under neutral or basic conditions, and that they are easily formed in the case of primary and secondary alcohols.

The synthesis of group I and group II compounds may be separate reactions. Preferably, it is carried out in a single vessel simultaneous reaction by loading a mixture of a monohydric alcohol and a polyhydric alcohol and reacting this mixture with an aldehyde. The one-pot reaction is particularly preferred when the aldehyde used for the reaction with the monohydric alcohol is the same as the aldehyde used for the reaction with the polyhydric alcohol.

During the synthesis of compounds of group I and group II, the molar ratio of hydroxyl groups to carbonyl groups is preferably from 20:1 to 1:5 and more preferably from 10:1 to 1:2 and especially from 2:1 to 1:1, such as for example , 20:1 to 1:2 or 20:1 to 1:1 or 10:1 to 1:5 or 10:1 to 1:1 or 2:1 to 1:5 or 2:1 up to 1:2.

Group III.

The Group III component is optional. The group III compound is the reaction product of formaldehyde with ammonia and/or an amine, the amine being selected from the group consisting of primary alkylamines having 1 to 10 carbon atoms and primary hydroxyalkylamines having 2 to 10 carbon atoms. This group includes the synergistic component of the composition of the invention.

Preferred primary amines have 1 to 4 carbon atoms, preferred primary hydroxyamines have 2 to 4 carbon atoms. Particularly preferred primary hydroxyamines correspond to the formula (1)

HO-A-NH2 (1) where A is a linear or branched alkylene group with 2-4 carbon atoms.

Examples of nitrogen compounds suitable for the present invention include: ammonia, methylamine, ethylamine, propylamine, isopropylamine, monoethanolamine, 1-amino-2-propanol, 3-amino-1-propanol, 2-amino-1-butanol, 3-amino-1 -butanol, 3-amino-1-butanol, 2-ethoxypropylamine, 3ethoxypropylamine, 1-methoxyisopropylamine and 2-methoxyethylamine, but are not limited to.

The nitrogen-containing compound and formaldehyde can be reacted in any molar ratio, with a preferred ratio of 1 mol aldehyde per 10 mol nitrogen-containing compound to 10 mol aldehyde per 1 mol nitrogen-containing compound, with a more preferred ratio being from 1 mol aldehyde per 5 mol nitrogen-containing compound to 5 mol of aldehyde per 1 mol of nitrogen-containing compound, with an even more preferred ratio being from 1 mol of aldehyde per 3 mol of nitrogen-containing compound to 3 mol of aldehyde per 1 mol of nitrogen-containing compound, and the most preferred ratio is 1 mol of aldehyde per 1 mol of nitrogen-containing compound.

The structure of the aminal formed from the reaction of formaldehyde and a nitrogen-containing compound depends on the selected nitrogen-containing compound and the selected molar ratio between formaldehyde and nitrogen-containing compound, which is obvious to those skilled in the art. Similarly, it is also possible to carry out the reaction of a mixture of the above nitrogen-containing compounds with the formation of individual aminals or mixtures of different aminals, which is also obvious to the average person skilled in the art.

In one preferred embodiment, the reaction product is of formula (1a)

Where

R is H or methyl; and n is 1 or 2.

- 5 039954

In a particularly preferred embodiment, R is CH3. In another particularly preferred embodiment, n is 1 and R is CH3. The name of this compound is 3,3'-methylenebis-5-methyloxazolidine (MBO).

In another preferred embodiment, the reaction product corresponds to formula (1b)

I , R where each R ¹ represents C1-C ₄ -alkyl or C2-C ₄ -hydroxyalkyl. Examples of particularly preferred compounds are hexahydro-1,3,5-trimethyl-s-triazine, hexahydro-1,3,5-triethyls-triazine, hexahydro-1,3,5-tris(hydroxymethyl)-s-triazine and hexahydro- 1,3,5-tris(2-hydroxyethyl)-striazine.

Mixtures of different reaction products of structures 1a and 1b are equally suitable. The substituents R and R ¹ may be the same or different.

Group IV.

The Group IV component is optional. A group IV compound is an inorganic or organic alkaline compound. This group includes a solids suppressing agent.

The solid usually formed during the reaction of Group I and Group II compounds with hydrogen sulfide is 1,3,5-tritian. The addition of an alkaline compound to compounds of groups I and II prevents or at least slows down the formation of slightly soluble 1,3,5-tritian when reacted with sulfhydryl compounds. Without going into theory, the authors believe that various intermediate compounds, such as polyoxymethylene sulfide oligomers, are formed and stabilized due to the presence of a group IV alkaline compound. By preventing the formation of solids, the acceptor composition remains homogeneous, and especially the use in a contact tower allows more efficient and quantitative use of the (semi)acetals of the compounds of groups I and II and thereby reduces the amount of chemicals needed. This can lead to increased gas breakthrough times in such purification processes. In addition, in the case of a direct feed for continuous desulphurisation, such as in natural gas streams, the removal of liquid reaction products is much easier than the removal of solids, and such reaction products do not lead to clogging of the pipes.

In addition, in the presence of an alkaline compound of group IV, the stability of compounds I and II is increased and the carbonation of formaldehyde is reduced or even prevented. This leads to a reduction in the level of free formaldehyde in the space above the composition and thus improves the safety of personnel working with the composition according to the invention.

Preferably the group IV compound is soluble or miscible with a mixture of compounds of groups I and II. In another preferred embodiment, the group IV compound is soluble or miscible with a mixture of compounds of groups I and II in the presence of an aqueous solvent.

In a preferred embodiment, the alkaline compound is selected from the group consisting of: IV(a)) alkali metal salts or alkaline earth metal salts, IV(b)) ammonia, alkyl-, aryl- or alkylarylamines,

IV(c)) hydroxyalkyl-, hydroxylaryl- or hydroxyalkylarylamines,

IV(d)) multifunctional amines and

IV(e)) mixtures of compounds of groups IV(a)-IV(c).

In arylamine, the N atom is bonded to the aromatic system. In alkylarylamine, the N atom can be bonded to either an aromatic system or an alkyl group.

Preferred alkali and alkaline earth metal salt cations IV(a) are derived from lithium, sodium, potassium, rubidium, beryllium, magnesium, calcium and strontium, with sodium, potassium and calcium being particularly preferred. Preferred anions are hydroxyl and carbonate groups, with hydroxyl being particularly preferred. Examples of preferred alkali or alkaline earth metal salts are LiOH, NaOH, KOH, Mg(OH) ₂ , Ca(OH) ₂ , Be(OH)2, Na2CO3, K2CO3, NaHCO3, KHCO3, BeCO3, MgCO3, CaCO3, Mg( HCO3h, Cα(HCO3)2 and mixtures thereof Particularly preferred group IVa alkali and alkaline earth metal salts are NaOH, KOH, Mg(OH)2 and Ca(OH)2.

Group IV(b) amines may be primary, secondary or tertiary amines. Preferred amines have up to 20 carbon atoms, more preferably 1 to 10 and especially 2 to 4 carbon atoms, such as 1 to 20, 1 to 4, 2 to 20 or 2 to 10 carbon atoms. Preferred hydrocarbyl radicals are alkyl, aryl and alkylaryl radicals, with alkyl radicals being particularly preferred. Particularly preferred amines are alkylamines with 1-4 carbon atoms per alkyl moiety. Examples of particularly preferred amines are methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, propy

- 6 039954 lamin, isopropylamine and butylamine.

The Group IV(c) hydroxyamine may be a primary, secondary or tertiary amine. It may contain one, two or three hydroxyl groups. In a preferred embodiment, each hydrocarbyl nitrogen substituent is substituted with no more than one hydroxy group. Preferred amines have up to 20 carbon atoms, more preferably 1 to 10 and especially 2 to 4 carbon atoms, such as 1 to 20, 1 to 4, 2 to 20 or 2 to 10 carbon atoms. Preferred hydrocarbyl radicals are alkyl, aryl and alkylaryl radicals, with alkyl radicals being particularly preferred. Particularly preferred hydroxyamines are hydroxyalkylamines with 1-4 carbon atoms per alkyl moiety. Examples of particularly preferred Group IV(c) hydroxyamines are monoethanolamine, diethanolamine, 1-amino-2-propanol, 3-amino-1-propanol, 2-amino-1-butanol, 3-amino-1-butanol, 2-ethoxypropylamine, 3ethoxypropylamine , 1-methoxyisopropylamine, 2-methoxyethylamine, 2-(2-aminoethoxy)ethanol, dimethylethanolamine, N-methyldiethanolamine, and monomethylethanolamine.

Preferred group IV(d) multifunctional amines contain, in addition to the amino group, at least one additional functional group selected from the group consisting of amino groups, ether groups and acid groups or an ester, an amide or a salt thereof. Preferred multifunctional amines have up to 50 carbon atoms, more preferably 1 to 20 and especially 2 to 10 carbon atoms, such as 1 to 50, 1 to 10, 2 to 50 or 2 to 20 carbon atoms. Hydrocarbon chains may be linear, branched and/or cyclic. In a preferred embodiment, they contain from 1 to 10 and especially from 2 to 5, for example from 1 to 5 additional amino groups and/or ether groups. Preferably the amino and/or ether groups are separated by at least two carbon atoms. Examples of particularly preferred group IV(d) multifunctional amines are ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, poly(ethyleneimine), propylenediamine, dipropylenetriamine, N,N-dimethyldipropylenetriamine, aminoethylenepiperazine, aminoethylethanolamine; tallow fatty propylenediamine ethoxylated with 2-20 moles of ethylene oxide; oleylamine ethoxylated with 2-20 moles of ethylene oxide; morpholine and piperazine.

In yet another preferred embodiment, the group IV(d) multifunctional amines contain, in addition to the amino group, an acid group or an ester, an amide or a salt. Preferred acid groups are sulfonic acids, phosphoric acids and carboxylic acids. Particularly preferred multifunctional amines bearing a carboxylic acid group are amino acids. Preferred amino acids include proteinogenic and non-proteinogenic amino acids. The amino group and the carboxylic acid group may be located on the same or different carbon atoms. The carboxylic acid groups and other acidic groups are particularly preferred in their neutralized form, for example in the form of alkali or alkaline earth salts. Particularly preferred amino acids contain additional functional groups, including hydroxyl, carboxyl, amide, ether, guanidino, hydroxyphenyl, imidazolyl and/or additional amino groups. Examples of preferred multifunctional amines bearing an acidic group are glycine, alanine, leucine, isoleucine, proline, serine, threonine, asparagine, glutamine, phenylalanine, tryptophan, tyrosine, valine, aspartic acid, glutamic acid, methionine, sarcosine, and taurine, and their carboxylate compounds. salts with sodium and/or potassium. Particularly preferred amino acids are glycine, lysine, histidine and arginine.

When mixtures IV(d) of alkaline compounds of groups IV(a)-IV(c) are used, they may contain 2 or more, preferably 2 to 10 and especially 3 to 5, for example two, three, four or five different components, selected from groups IV(a)-IV(c). The proportion of each individual compound in the mixture of compounds IV(a)-IV(c) is preferably 5 to 95 wt.%, more preferably 10 to 90 wt.% and especially 20 to 80 wt.%, for example 5 to 90 wt.%, from 5 to 80 wt.%, from 10 to 95 wt.%, from 10 to 80 wt.%, from 20 to 95 wt.% or from 20 to 90 wt.%.

Group V

The V group component is optional. This group includes anti-emulsifiers, demulsifiers and/or non-emulsifiers. The purpose of the presence of the group V compounds is to prevent the formation of emulsions during the cleaning process and to increase the efficiency of the cleaning process. Often, metal sulfides, such as iron sulfide, are formed, for example, during corrosion of pipelines and equipment in the presence of sulfhydryl compounds. As fine solids, these substances accumulate at the interface between oil and water, thereby stabilizing the water present in the oil and forming a stable emulsion that can affect phase separation and the availability of sulfhydryl compounds to be removed. The purpose of the anti-emulsifier, demulsifier and/or non-emulsifier is to break the oil/water emulsion by creating a preferred water wetted surface on the metal sulfide, and to change the surface tension at the oil/water interface stabilized by the metal sulfides to coalesce the emulsion.

In a preferred embodiment, the group V anti-emulsifier is part of a composition of the invention containing compounds of groups I and II; groups I, II and III; groups I, II and IV or groups I, II,

- 7 039954

III and IV. Preferred anti-emulsifiers are polymeric non-ionic surfactants, including polysorbates; polymers containing ethylene oxide; polymers containing propylene oxide; copolymers of ethylene oxide and propylene oxide; alkyl polyglucosides such as decyl maltoside; alkylphenol ethoxylates; and, but not limited to, ethoxylated and/or propoxylated alkylphenol formaldehyde resins. The anti-emulsifier can also be a fatty alcohol alkoxylated with 1-200 moles, preferably 2-100 moles and especially 5-50 moles, for example with 1-100 moles or 1-50 moles or 2-50 moles or 5-100 moles of alkylene oxide. . Examples of preferred alkylene oxides are ethylene oxide, propylene oxide and mixtures thereof; preferred fatty alcohols have a C ₄ -C ₃₆ alkyl radical and especially a C ₈ -C ₂₄ alkyl radical, for example a _{C 4} -C ₂₄ alkyl radical or a C ₈ -C ₃₂ alkyl radical, such as cetyl alcohol and oleyl alcohol.

In a preferred embodiment, the anti-emulsifier is a compound of formula (6)

Where

R ₁₀ is C ₂ -C ₄ alkylene;

R11 is C ₁ -C ₁₈ alkyl;

k is a number from 1 to 200;

m is a number from 1 to 100.

In a preferred embodiment, R ₁₀ is an ethylene or propylene group. R ₁₀ may be mixtures of various C ₂ -C ₄ alkylene groups, preferably ethylene and propylene groups.

In another preferred embodiment, R11 is a C ₄ -C ₁₂ alkyl group, more preferably a tertiary butyl group or an isononyl group.

In formula (6), R ₁₀ , R11 and k may be the same in each of the repeating units, or they may differ from one to one.

In another preferred embodiment, k is a number from 2 to 20.

In another preferred embodiment, m is a number from 3 to 20.

In another specific preferred embodiment, the anti-emulsifier is an alkylbenzenesulfonic acid, such as dodecylbenzenesulfonic acid (7) or its salt with an alkali metal, ammonia or a primary, secondary or tertiary amine, such as methylamine, ethylamine, propylamine, diethylamine, dimethylamine, trimethylamine, ethanolamine, diethanolamine or triethanolamine.

In another preferred embodiment, the demulsifier is a mixture of at least one compound of formula (6) and alkylbenzenesulfonic acid (7) or a salt thereof. Such a mixture preferably contains (6) and sulfonic acid (7), respectively its salt, in a weight ratio of 5:1 to 1:5, more preferably in a weight ratio of 3:1 to 1:3.

The polymeric non-ionic surfactant may be added to the additional components of the composition according to the invention in pure form, or preferably may be dissolved or suspended in a solvent. Any solvent suitable for dissolving or suspending the polymeric non-ionic surfactant can be used. Examples of suitable solvents include water, ethylene glycol, propylene glycol, butylene glycol, oligoethylene glycols, oligopropylene glycols; ethers, including glycol ethers such as methoxyethane, dimethoxyethane and butoxyethanol; alcohols, toluene, xylene, aromatic naphtha, or any combination thereof. The alcohol may include any alcohol suitable for use in oil recovery and for dissolving the polymeric non-ionic surfactant, and may preferably be selected from the group consisting of methanol, ethanol, propanol, isopropyl alcohol, butanol, 2-ethylhexanol, or any of them. combinations.

Group VI.

The Group VI component is optional. This group includes corrosion inhibitors and

- 8 039954 zhit for adding the functionality of corrosion inhibition in the composition according to the invention. The addition of a corrosion inhibitor may not be necessary as the Group III synergist provides sufficient corrosion inhibition to protect the integrity of the entire system.

However, often the addition of an additional corrosion inhibitor is recommended to reduce overall corrosiveness, protect pipes and production equipment from corrosion caused by petroleum fluids and gases to which the present invention is applied.

A preferred embodiment of the present invention is the use of alkyldimethylbenzylammonium chloride of formula (8) as a corrosion inhibitor which also reduces surface tension.

^R9

Cl /N-CH, 0' where R ⁹ represents C ₈ -C ₁₈ -alkyl.

The composition of the invention may additionally contain biocides such as formaldehyde or glutaraldehyde, aqueous dispersants such as polyacrylamide dispersants, oxygen scavengers, defoamers such as acetylenic diols, silicones or polyethoxylated defoamers, and/or flocculants. Preferably, their content is less than 10 wt.% and particularly preferably less than 5 wt.%, compared with the components of groups I-VI.

In a preferred embodiment, the proposed composition contains from 5 to 60 wt.% of the reaction product of the monohydric alcohol described above in group I, preferably from 10 to 50 wt.% and especially from 15 to 40 wt.%, for example from 5 to 50 wt. % or from 5 to 40 wt.% or from 10 to 60 wt.% or from 10 to 40 wt.% or from 15 to 60 wt.% or from 15 to 50 wt.%.

In a preferred embodiment, the composition according to the invention contains from 10 to 90 wt.% of the reaction product of the polyhydric alcohol described above in group II, preferably from 20 to 80 wt.% and especially from 25 to 75 wt.%, for example from 10 to 80 wt. .% or from 10 to 75 wt.% or from 20 to 90 wt.% or from 20 to 75 wt.% or from 25 to 90 wt.% or from 25 to 80 wt.%.

The molar ratio between the reaction product of monohydric alcohol and aldehyde (group I) and the reaction product of polyhydric alcohol and aldehyde (group II) is preferably 20:1 to 1:20, preferably 10:1 to 1:10 and especially 5:1 to 1:5, e.g. 20:1 to 1:10, 20:1 to 1:5, 10:1 to 1:20, 10:1 to 1:5, 5:1 to 1:20 or from 5:1 to 1:10.

In a preferred embodiment, the composition according to the invention contains from 0.1 to 15 wt.% of the synergist described above in group III, preferably from 0.5 to 10 wt.% and especially from 1 to 8 wt.%, for example from 0.1 up to 10 wt.% or from 0.1 to 8 wt.%, or from 0.5 to 15 wt.%, or from 0.5 to 8 wt.%, or from 1 to 15 wt.%, or from 1 up to 10 wt.%.

In a preferred embodiment, the composition according to the invention contains from 1 to 25 wt.% of at least one solids suppression agent described above in group IV, preferably from 5 to 20 wt.% and especially from 7 to 18 wt.%, for example from 1 to 20% by weight or 1 to 18% by weight or 5 to 25% by weight or 5 to 18% by weight or 7 to 25% by weight or 7 to 20% by weight .

In a preferred embodiment, the composition according to the invention contains from 0.1 to 10 wt.% of at least one anti-emulsifier described above in group V, preferably from 0.5 to 5 wt.%.

In a preferred embodiment, the composition according to the invention contains from 0.1 to 10 wt.% of the corrosion inhibitor described above in group VI, preferably from 0.2 to 5 wt.%.

Preferred proportions of individual compounds of groups I-VI in the composition according to the invention are given in relation to the total number of compounds of groups I-VI. In a preferred embodiment, the compounds of groups I-IV add up to 100% by weight.

The composition of the invention is preferably applied to the oil or gas to be treated in amounts of 0.5 to 50 ppmw, more preferably 1 to 30 ppmw and especially 2 to 20 ppmw. /ppm, for example 0.5 to 3 ppmw, 0.5 to 20ppm wt, 1 to 50ppm wt, 1 to 20ppm wt./ ppm, 2 to 50 ppm wt, or 2 to 30 ppm wt per 1 ppm sulfur contained in the oil or gas.

The use of undiluted compositions according to the invention has proved particularly successful in gas contact towers.

In a preferred embodiment, the compositions in accordance with various aspects of the invention are used in compositions additionally containing water. Water in the composition may be formed during the preparation of the hemiacetals, or may be added to the composition to balance the composition. Preferably water is present in a concentration of from 1 to 90 wt.%, preferably from 5 to 80 wt.%, for example from 1 to 80 wt.% or 5 and 90 wt.% of the composition. In another preferred embodiment, water is present to balance up to 100% by weight of the composition.

- 9 039954

Alternatively, any formulation according to various aspects of the invention is adjusted to 100% with water and/or glycol and/or alcohol based solvents in accordance with the amounts given above for water alone. Preferred alcohols and glycols are selected from, but not limited to, methanol, ethanol, propan-1-ol, propan-2-ol, ethylene glycol, diethylene glycol, triethylene glycol, neopentyl glycol, 2-butoxyethanol, and mixtures thereof.

The compositions of the invention can be obtained by mixing compounds of groups I and II, groups I, II and III, groups I, II and IV, respectively, groups I, II, III and IV, each of which, if necessary, is further mixed with compounds of groups V and/or VI. The order in which the individual compounds are added is not important. In a preferred embodiment, compounds from groups I and II are formed simultaneously in a one-pot reaction, and then compounds of groups III and/or IV and, if necessary, groups V and/or VI are added to them. To obtain a particular composition, water and/or other solvents may be added to the composition of the invention. Alternatively, some or all of the ingredients for preparing the composition of the invention may contain a solvent.

The finished composition containing the composition according to the invention and the solvent is preferably used in concentrations from 5 to 40,000 mg/l, preferably from 50 to 30,000 mg/l, especially from 100 to 25,000 mg/l, for example from 5 to 40,000 mg /l, 5 to 25,000 mg/l, 50 to 40,000 mg/l, 50 to 25,000 mg/l, 100 to 40,000 mg/l and 100 to 30,000 mg/l, calculated on the volume of oil or gas produced, intended for processing. The preferred and most appropriate concentration of a formulation depends on the potency of the formulation itself, the type and amount of sulfhydryl compounds to be captured, the static conditions, the temperature and salinity of the system. In addition, the material class of the equipment used to operate the cleaning process should be taken into account: if, for example, the contact tower is made of stainless steel, a more concentrated product can be used, while it has been proven that if a poor material of construction is used, such as carbon steel, it is preferable to use more dilute product formulations, preferably containing a Group VI corrosion inhibitor.

In the specified range of concentrations, the composition according to the invention provides a significant removal of sulfhydryl compounds from the resulting liquids and provides a certain sulfur content in the produced hydrocarbon as it enters the market and, therefore, the safety of working with it. In addition, the fluidity of the treated hydrocarbon is not deteriorated due to the fact that the formation of solid reaction products is prevented.

The present invention also includes a method of using the composition of the invention to trap sulfhydryl compounds present in drilling and mineral oil production cycles, particularly as a component of well workover, well maintenance, production expansion and flow assurance operations.

The composition of the invention can be introduced into the stream containing the sulfhydryl compound, along with other ingredients known to those skilled in the art. Such other ingredients include acids, dispersants, thickeners, lubricating agents, scale inhibitors, friction reducers, crosslinking agent, surfactants, pH adjuster, iron control agents, degraders; this is particularly advantageous since any produced water (or recycled water) is in contact with the compositions of the present invention.

The use of embodiments of the present invention allows either (i) at a lower dosage of acceptor to obtain the same level of residual amount of sulfhydryl compound, or (ii) to achieve a lower level of residual amount of sulfhydryl compound using the same dose of acceptor, compared with hemiacetals and/or acetals in accordance with the prior art. Furthermore, in combination with the reaction product of formaldehyde and amine, the uptake kinetics of H ₂ S and/or mercaptans provided by a mixture of hemiacetals and/or acetals of a monohydric alcohol and a polyhydric alcohol with an aldehyde can be significantly accelerated. This allows much better capture of sulfhydryl compounds, especially in applications where the contact time between the oil or gas and the scavenger is short, such as in contact towers and direct feed gas treatment applications. Adding a solids suppressant as an additional synergistic additive increases the gas breakthrough time in a system containing sulfhydryl compounds. By improving the capture of sulfhydryl compounds, the formation of complex and difficult to process emulsions is not observed. In addition, embodiments of the present invention will not corrode the oilfield equipment with which they come into contact and will not allow the deposition of unwanted solids such as polymethylene sulfide oligomers and metal sulfide deposits often found in prior art solutions. Other applications of embodiments of the present invention include treatment of water for injection into a well under pressure, treatment during drilling and processing operations, changing wettability and cleaning the well.

Within the present description, percentages are weight percent unless otherwise indicated.

- 10 039954

Examples Preparation of hemiacetals

Alcohols were loaded into the stirred reactor in the amount indicated in Table 1. 1, together with 0.25 wt.% sodium hydroxide solution with a concentration of 50 wt.%. This mixture was homogenized for 10 min before the addition of paraformaldehyde (93 wt.%) in the amounts indicated in table. 1 for approximately 30 minutes. The reaction mixture was heated with stirring for 2 hours at 80 to 85°C. After the reaction time, the mixture was cooled to 30°C.

In the reaction products, the molar amounts of hemiacetals relative to the total number of charged hydroxyl groups and the content of free formaldehyde (CH ₂ O) were determined using ¹ H-NMR spectroscopy.

Table 1. Preparation of hemiacetals and acetals

Hemiacetal Loading react reaction product Monohydric alcohol, loading (g) Polyhydric alcohol, loading (g) Paraformaldehyde (g) (semi-)acetal CH ₂ O (wt%) A1 methanol 500 — 500 98.00% 0.07 A2 ethanol 600 — 420 99% 0.06 AZ iso-propanol 600 — 320 99% 0.08 A4 2-EG 800 — 200 98% 0.11 A5 — ethylene glycol 500 520 97% 0.12 Ab — diethylene glycol 600 360 96% 0.16 A7 — glycerol 600 410 66% 0.05 A8 — pentaerythritol 500 480 98% 0.12 A9 — pentaerythritol 600 430 75% 0.04 AYu ethanol 100 ethylene glycol 490 430 75% 0.02 AP ethanol 80 ethylene glycol 400 470 99% 0.03 A12 methanol 70 glycerol 550 450 70% 0.02 A13 methanol 80 glycerol 570 370 55% 0.02 A14 ethanol 120 glycerol 450 440 80% 0.02 A15 ethanol 160 pentaerythritol 350 440 98% 0.03

2-EG = 2-ethylhexanol

Other materials used are hexahydro-1,3,5-trimethyl-s-triazine (HTT) and 3,3'-methylenebis-5-methyloxazolidine (MBO) as synergists according to group III.

NaOH (5 wt.% aqueous solution), triethylamine (TEA), monoethanolamine (MEA) and piperazine (PIP) were used as solids suppression agents according to group IV. All of these materials were commercial.

Acceptor Efficiency Tests

In order to demonstrate the improved efficiency of the present invention in removing sulfhydryl compounds compared to the group I and group II compounds, respectively, the removal of H2S from the oil and from the oil/water mixture was measured.

The oil used was a mixture of kerosene with 10% xylene without bottom sediment and water (BS&W) to simulate oil field conditions.

The oil/water mixture was a mixture of the above oil and brine (in a 50:50 volume ratio of oil to water phase) to mimic the performance in hydrated crude oil.

In a 500 ml autoclave (Parr reactor), 350 ml of oil, respectively, oil/brine mixtures were deaerated for 1 h with N2, then saturated with an acid gas mixture of 0.2 wt.% H2S and 99.8 wt.% CO2, blowing this gas through the oil, respectively, the oil/brine mixture with a flow rate of 0.6 l/min. After equilibration with an acid gas mixture of 1,000 ppm, the test composition was introduced into the autoclave using an HPLC pump. If mixtures of (semi)acetals were used, their weight ratios are given in Table 1. 2 and 3; the amounts of synergist and solids suppressant are relative to their proportion in the composition and are therefore included in the stated dosage.

Performance tests were carried out at 30°C and less than 1 bar using a gas chromatograph to measure the H2S output in the gas phase every two minutes. Then a plot of the measured H2S content (ppm) versus time (min) was plotted. The amount of hydrogen sulfide removed is the area above the resulting performance curve, which was calculated by integrating the curve. For all samples, curve integration was performed up to 60 min after the introduction of the H ₂ S acceptor. As an output parameter of this test, the performance was determined by L _acc /kg H2S (liters of the H2S acceptor required to remove 1 kg of H2S from the system) for 6 min and 1 h analysis. All consumption values are the average of three repeated tests. The test results are summarized in table. 2 and 3. Percentage refers to the average percentage unless otherwise noted.

- 11 039954

Table 2. Performance Tests for H ₂ S Acceptor in Oil (BS&W Zero)

Example (Hemi)acetal Synergist (2 wt%) Solids suppression agent Eacc./ΚΓ H ₂ S 6 MIN 1 hour P1 (compar.) A2 — — 20.76 9.56 R2 (compar.) AZ — — 21.23 10.04 RZ (compar.) A4 — — 32.60 16.20 P4 (compar.) A5 — — 18.65 9.01 P5 (compar.) Ab — — 18.09 8.47 P6 (compar.) Al + A2 (1:1) — — 19.12 9.85 P7 (compar.) A5 + A6 (2:1) — — 17.24 8.86 R8 A2 + A5 (1:4) — — 14.10 7.02 R9 A2 + A5 (1:1) — — 14.48 7.35 Ryu A4 + A5 (1:3) — — 13.86 7.13 R11 AYu — — 12.95 6.89 R12 AP — — 13.22 6.70 R13 AZ + A6 — — 14.27 7.54 P14 (compar.) A2 mvo — 5.65 4.63 P15 (compar.) AZ mvo — 5.86 4.86 P16 (compar.) A4 mvo — 9.98 8.05 P17 (compar.) A5 mvo — 5.10 4.21 P18 (compar.) Ab mvo — 5.28 4.36 R19 A2 + A5 (1:4) mvo 3.10 2.72 R20 A2 + A5 (1:1) mvo — 3.21 2.86 R21 A4 + A5 (1:3) mvo — 3.25 2.80 R22 AYu mvo — 2.98 2.61 R23 AP mvo — 2.92 2.55 R24 AZ + A6 (1:3) mvo — 3.11 2.75 P25 (compar.) A2 mvo 5% MEA 4.76 4.06 P26 (compar.) AZ mvo 8% PIP 4.80 4.12 P27 (compar.) A4 mvo 10% TEA 8.12 6.95 P28 (compar.) A5 mvo 5% MEA 4.29 3.68 P29 (compar.) Ab mvo 8% PIP 4.23 3.57 RZO A2 + A5 (1:4) mvo 5% MEA 2.27 1.97 R31 A2 + A5 (1:1) mvo 5% MEA 2.35 2.04 R32 A4 + A5 (1:3) mvo 10% TEA 2.64 2.25 RZZ AYu mvo 5% MEA 2.12 1.89 R34 AP mvo 5% MEA 2.26 2.00 R35 AZ + A6 (1:3) mvo 8% PIP 2.49 2.21

- 12 039954

Table 3. Performance tests for H2S removal in a mixture of oil and brine ________________ (50:50 volume ratio of oil to water phase) _________

Example (Hemi)acetal Synergist Solids suppression agent Acc./kg H ₂ S 6 MIN 1 hour P36 (compar.) A1 — — 23.36 10.04 P37 (compar.) A2 — — 23.82 10.20 P38 (compar.) A5 — — 23.11 9.50 P39 (compar.) A7 — — 20.80 8.91 P40 (compar.) A8 — — 19.64 8.52 P41 (compar.) A9 — — 19.22 8.20 R42 A2 + A5 (1:4) — — 15.22 6.69 R43 AYu — — 15.47 6.77 R44 Al + A7 (1:3) — — 14.96 6.61 R45 Al + A7 (1:1) — — 15.82 6.96 R46 A12 — — 14.92 6.48 R47 A13 — — 15.44 6.88 R48 A2 + A8 (1:1) — — 15.71 6.90 R49 A2 + A8 (1:5) — — 14.88 6.56 P50 A2 + A9 (1:1) — — 16.05 7.01 P51 A14 — — 14.66 6.50 P52 (compar.) A1 NTT — 8.76 7.04 P53 (compar.) A2 MVO — 8.40 6.88 P54 (compar.) A5 MVO — 8.56 6.80 P55 (compar.) A7 NTT — 9.30 7.56 P56 (compar.) A8 NTT — 8.07 6.52 P57 (compar.) A9 NTT — 8.41 6.92 R58 A2 + A5 (1:4) MVO — 6.28 5.44 R59 AYu MVO — 6.15 5.26 P60 Al + A7 (1:3) NTT — 6.25 5.30 R61 Al + A7 (1:1) NTT — 6.38 5.45 R62 A12 NTT — 5.84 5.12 R63 A13 NTT — 6.50 5.78 R64 A2 + A8 (1:1) NTT — 5.95 5.17 R65 A2 + A8 (1:5) NTT — 5.85 5.03 R66 A2 + A9 (1:1) NTT — 5.92 5.28 R67 A14 NTT — 6.14 5.19 P68 (compar.) A1 NTT 5%NaOH 6.91 5.72 P69 (compar.) A2 MVO 10%MEA 6.52 5.56 P70 (compar.) A5 MVO 10%MEA 7.05 5.92 P71 (compar.) A7 NTT 5%NaOH 7.33 6.24 P72 (compar.) A8 NTT 10%MEA 6.31 5.25 P73 (compar.) A9 NTT 10%MEA 6.73 5.57 R74 A2 + A5 (1:4) MVO 10%MEA 4.42 3.86 R75 AYu MVO 10%MEA 3.96 3.54 R76 Al + A7 (1:3) NTT 5%NaOH 4.26 3.68 R77 Al + A7 (1:1) NTT 5%NaOH 4.49 3.89 R78 A12 NTT 5%NaOH 3.93 3.47 R79 A13 NTT 5%NaOH 4.07 3.62 P80 A2 + A8 (1:1) NTT 10%MEA 4.18 3.65 R81 A2 + A8 (1:5) NTT 10%MEA 3.72 3.35 R82 A2 + A9 (1:1) NTT 10%MEA 4.10 3.67 R83 A15 NTT 10%MEA 3.86 3.38 R84 A2 + A5 (1:4) — 10%MEA 7.86 4.42 R85 AYu — 10%MEA 7.73 4.28 R86 A14 NTT — 6.23 5.35 R87 A14 — 10% TEA 7.82 4.38

In tests involving synergist, the proportion of MBO was 2 wt.%, the proportion of HTT was 6 wt.% of the capture composition.

In table. 2 and 3, the lower was the consumption of the acceptor to remove 1 kg of H2S, the more efficient was the acceptor. In the examples of the invention, mixtures of acetals based on mixtures of monohydric alcohols and polyhydric alcohols are more effective than individual components. Efficiency is further improved by the inclusion of a synergist and/or solids suppression agent. In addition, the incorporation of the synergist increases the rate of reaction in the initial phase of the test, as can be seen from the difference in removal efficiency after 6 minutes compared to 1 hour.

Acceptor Performance Tests - Gas Breakthrough

The performance of the H ₂ S scavengers of the invention was evaluated by their ability to remove H ₂ S from a fluid gas stream by passing a gas containing H 2 S through a liquid column containing the scavenger chemical. A mixture of acid gas 0.2% H 2 S and 99.8% CO ₂ was purged at a flow rate of 60 ml/min through 440 ml of a 22% active solution of the scavenger composition in water. Under these conditions, the average time of contact between the gas and the acceptor was about 4 s. Initially, all H2S was removed from the gas pipeline.

- 13 039954 current, and no H2S was detected in the flue gas. At some point in time (breakthrough time or TBT) the chemical could no longer completely capture H2S from the gas stream and H2S was detected in the off-gas. This parameter is a measure of the efficiency of an acceptor, especially for use in contact towers with short contact times. The longer the breakthrough time, the more effective the chemical acceptor.

The effect of the solids suppressing agent was evaluated by visual inspection of the waste fluid with the scavenger after the gas breakthrough test. The degree of solids formation was characterized as opaque > hazy > opalescent > clear.

The total concentration of the acceptor compositions in all examples is 22% by weight, i. e. in examples where a synergist and/or solids suppressor is present, the concentration of (semi)acetals decreases accordingly.

Table 4. Gas breakthrough time for various (semi)acetals

Example (Hemi)acetal Synergist Solids suppression agent TBT [min] visual analysis B1 (compar.) A1 — — 31 opaque B2 (compar.) A2 — — 29 opaque VZ (compar.) AZ — — 27 opaque B4 (compar.) A5 — — 17 opaque B5 (compar.) A7 — — 35 opaque Wb (compar.) Al + A2 (1:1) — — 31 opaque B7 (compar.) A5 + A7 (1:1) — — 37 opaque AT 8 A2 + A5 (1:1) — — 45 opaque AT 9 A2 + A5 (1:4) — — 47 opaque AT 10 AYu — — 52 opaque AT 11 AP — — 58 opaque AT 12 A12 — — 55 opaque B13 Al + A7 (1:4) — — 58 opaque B14 AZ + A7 (1:2) — — 49 opaque B15 A1 7% MVO — 76 muddy B16 A2 3%NTT — 69 muddy B17 AZ 5%NTT — 74 muddy B18 A5 3%NTT — 78 muddy B19 A7 7% MVO — 77 muddy IN 20 A2 + A5 (1:1) 3%NTT — 82 muddy AT 21 A2 + A5 (1:4) 3%NTT — 89 muddy B22 AYu 3%NTT — 87 muddy B23 AP 3%NTT — 84 muddy B24 A12 7% MVO — 81 muddy B25 A1+A7(1:4) 5% MVO 85 muddy B26 AZ + A7 (1:2) 5%NTT — 80 muddy B27 A1 — 10%MEA 149 opalescent B28 A2 — 15% PIP 146 opalescent B29 AZ — 15% PIP 134 opalescent VZO A5 — 15% PIP 157 opalescent B31 A7 — 10%MEA 150 opalescent B32 A2 + A5 (1:1) — 15% PIP 164 opalescent VZZ A2 + A5 (1:4) — 15% PIP 182 opalescent B34 AYu — 15% PIP 169 opalescent B35 AP — 15% PIP 178 opalescent B36 A12 — 10%MEA 171 opalescent B37 Al + A7 (1:4) — 15% PIP 172 opalescent B38 A3 + A7(1:2) — 15% PIP 163 opalescent B39 A1 7% MVO 10%MEA 215 transparent B40 A2 3%NTT 15% PIP 200 transparent B41 AZ 5%NTT 15% PIP 192 transparent B42 A5 3%NTT 15% PIP 226 transparent B43 A7 7% MVO 10%MEA 222 transparent B44 A2 + A5 (1:1) 3%NTT 15% PIP 298 transparent B45 A2 + A5 (1:4) 3%NTT 15% PIP 321 transparent B46 AYu 3%NTT 15% PIP 334 transparent B47 AP 3%NTT 15% PIP 348 transparent B48 A12 7% MVO 10%MEA 342 transparent B49 Al + A7 (1:4) 5% MVO 15% PIP 346 transparent B50 AZ + A7 (1:2) 5%NTT 15% PIP 316 transparent

A comparison of the examples according to the invention and the comparative examples shows that mixtures of (po- 14 039954 lu) acetals containing the reaction products of monohydric and polyhydric alcohols have a higher TBT than individual components or mixtures of components of the same group. The addition of a group III synergist increases the H2S uptake activity of (semi)acetals and especially mixtures of (semi)acetals. The cleaning process becomes faster and more efficient. The addition of a solids suppression agent further greatly improves the performance of the scavenger. Substantially suppresses the formation of solids, which would otherwise obstruct the accessibility of the acceptor portion, and in addition, create a risk of blocking the lines for the effluent stream. Increasing the removal efficiency significantly increases the stoichiometric ability of the added synergist to capture H2S.

Claims (20)

CLAUSES OF THE INVENTION 1. A composition for capturing hydrogen sulfide and/or mercaptans, comprising: I) at least one reaction product between a nitrogen-free monohydric alcohol and an aldehyde and II) at least one reaction product between a nitrogen-free polyhydric alcohol and an aldehyde, wherein the reaction products I and II are hemiacetals or acetals and the aldehyde is selected from the group consisting of formaldehyde, paraformaldehyde, glyoxal, acetaldehyde, propionaldehyde, butyraldehyde and glutaraldehyde, and the monohydric alcohol is selected from the group consisting of methanol, ethanol, propanol, isopropanol, n-butanol, isobutanol, tert-butanol, pentanol, hexanol, heptanol and octanol, and any mixture thereof, and the polyhydric alcohol is selected from the group consisting of monoethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butylene glycol, neopentyl glycol, pentaerythritol, glycerol and oligomers of glycerol. 2. The composition according to paragraph 1, additionally comprising: III) at least one reaction product of formaldehyde and ammonia and/or an amine selected from the group consisting of primary alkylamines having from 1 to 4 carbon atoms and primary hydroxyalkylamines having from 2 to 4 carbon atoms. 3. The composition according to claim 1 or 2, further comprising: IV) at least one inorganic or organic alkaline compound that functions as a solids suppression agent, wherein the alkaline compound IV is selected from the group consisting of: IV(a)) alkali metal salts and alkaline earth metal salts; IV(b)) ammonia; alkyl-, aryl- or alkylarylamines; IV(c)) hydroxyalkyl-, hydroxyaryl- or hydroxyalkylarylamines; IV(d)) multifunctional amines containing, in addition to the amino group, at least one additional functional group selected from the group consisting of amino groups, ether groups and acid groups, and an ester, amide or salt thereof; IV(e)) mixtures of compounds from groups IV(a)-IV(c); where alkyl means C ₁ -C ₂₀ -alkyl, aryl means C ₆ -C ₂₀ -alkyl, and alkylaryl means C ₇ -C _2O alkylaryl. 4. The composition according to one or more of claims 1 to 3, wherein the aldehyde is formaldehyde. 5. The composition according to one or more of claims 1 to 4, wherein the reaction product of a polyhydric alcohol and an aldehyde is selected from the group consisting of compounds of formulas (2) to (5) HO^ o ^R _{2 (2)} ^R 1 HO^^o--(CH ₂ ) _p --O--R ₂ (2a) where p is a number from 2 to 10, R1 is H or C ₁ -C ₈ -alkyl, R2 is CH2OH and HO (3) OR ³ where R ³ and R ⁴ independently represent H or CH2OH - 15 039954 where m is from 1 to 10, preferably 1 or 2, and Where R5 is H, _CH3 , ( _CH2 ) _zCH3 , z _is from 1 to 10, x is from 1 to 5. 6. The composition according to one or more of claims 2-5, in which the reaction product III of the amine and formaldehyde corresponds to formula (1b) where each R ¹ is C ₁ -C ₄ -alkyl or C ₂ -C ₄ -hydroxyalkyl. 7. The composition according to one or more of claims 2 to 6, in which the reaction product III of the amine and formaldehyde corresponds to formula (1a) Where R is H or methyl and n is 1 or 2. 8. The composition according to claim 7, wherein the compound of formula (1a) is 3,3'-methylenebis-5methyloxazolidine. 9. The composition according to one or more of claims 2 to 8, wherein the reaction product III of an amine and formaldehyde is present in the composition in an amount of from 1 to 20 wt.%, preferably from 5 to 15 wt.%. 10. The composition according to one or more of claims 1 to 9, further comprising alkyl dimethyl benzyl ammonium chloride of formula (8) as a corrosion inhibitor where R ⁹ is C ₈ -C ₁₈ -alkyl. 11. The composition according to claim 10, wherein the compound of formula (8) is present in an amount of from 0.01 to 5 wt.%, preferably from 0.5 to 2 wt.%. 12. The composition according to one or more of claims 1 to 11, further comprising a demulsifier in an amount of from 0.1 to 10 wt.%, preferably from 0.5 to 2 wt.%. 13. The composition according to claim 12, wherein the demulsifier is selected from the group consisting of polysorbates, fatty alcohols; polymers comprising ethylene oxide; polymers comprising propylene oxide; copolymers of ethylene oxide and propylene oxide; alkyl polyglucosides, alkyl phenol ethoxylates, alkyl polyethylene oxide, alkyl benzene sulfonic acid and ethoxylated and/or propoxylated alkyl phenol formaldehyde resins. 14. The composition according to claim 12 or 13, in which the demulsifier corresponds to formula (6) Where R ₁₀ is C ₂ -C ₄ -alkylene, - 16 039954 Ri 1 is C1- _C18 alkyl, k is a number from 1 to 200, and w is a number from 1 to 100. 15. The composition according to claim 12, wherein the demulsifier is dodecylbenzenesulfonic acid, it (7) 16. A composition according to one or more of claims 12 to 15, wherein the demulsifier is a mixture of at least one compound of formula (6) and at least one compound of formula (7) in a weight ratio of from 5:1 to 1:5, preferably in a weight ratio of from 3:1 to 1:3. 17. A composition according to one or more of claims 1 to 16, comprising from 1 to 50 wt.% of the reaction product of a monohydric alcohol and an aldehyde, preferably from 5 to 25 wt.%. 18. A composition according to one or more of claims 1 to 17, comprising from 1 to 95% by weight of a reaction product of a polyhydric alcohol and an aldehyde, preferably from 20 to 75% by weight. 19. A composition according to one or more of claims 3 to 18, comprising from 0.1 to 10 wt.%, preferably from 0.5 to 5 wt.% of at least one solids suppressant. 20. A composition according to one or more of claims 1-19, comprising water up to 100% by weight.