Method for reducing or preventing corrosion or fouling caused by acidic compound

Abstract

To provide a method for reducing or preventing corrosion or fouling in an apparatus for performing a chemical process.SOLUTION: Corrosion or fouling is caused by an acidic compound present in a chemical process. A method is provided in which at least one of quaternary ammonium hydroxide of formula (I) is added to an apparatus in which a chemical process is carried out. In the formula, R1, R2, and R3 are each independently a C1-C10 alkyl group, and R4 is selected from the group consisting of C1 to C18 alkyl, benzyl, monocycloalkyl having 5, 6, 7, or 8 carbon atoms, bicycloalkyl having 6 to 8 carbon atoms, and tricycloalkyl having 7 to 10 carbon atoms, among others.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for reducing or preventing corrosion or fouling caused by acidic compounds, such as acids, e.g., hydrogen chloride, or acidic ammonium salts, e.g., ammonium chloride, present or formed in a chemical process, e.g., a petrochemical process, comprising the step of adding at least one of the quaternary ammonium hydroxides of the present invention to an apparatus used to carry out the chemical process. [Background technology]

[0002] Corrosion and fouling are serious problems in chemical production facilities, especially crude oil processing plants such as crude oil refineries and petrochemical plants, because they lead to deterioration of process equipment, leading to economic losses and health and environmental hazards. The main causes of corrosion and fouling are ammonium salts, e.g., organic and inorganic ammonium halides, ammonium sulfate or ammonium hydrogen sulfate. They are corrosive in gaseous, solid, or dissolved form and can contribute to the accumulation of deposits that can cause hydraulic or thermal failures in various system components. Ammonium salts are usually introduced into the process as part of the feedstock, such as crude oil, but they can also be formed during chemical processes. Furthermore, corrosion in crude oil refineries, petrochemical plants, and other chemical facilities can be due to acidic compounds, especially hydrogen chloride, that are generated during the course of the process. For example, in a crude oil distillation unit, hydrogen chloride can be formed via hydrolysis of calcium chloride or magnesium chloride still present in the desalted crude oil that is fed to the unit.

[0003] US Patent No. 7,279,089 and US Patent No. 8,177,962 describe a method for preventing corrosion and fouling in petrochemical processes by neutralizing acidic components such as ammonium chloride or hydrogen chloride with choline hydroxide introduced into the respective process units. Choline hydroxide is said to have advantageous properties over ammonia and other amines that have been commonly used for such applications up to now. First of all, choline hydroxide is much more basic, thus allowing lower molar dosages and more effective pH control. Furthermore, due to its higher basicity, choline hydroxide reacts with acidic compounds to form salts whose aqueous solutions have higher pH values. In this way, the risk of secondary corrosion caused by the neutralizing salt is greatly reduced. Moreover, said neutralizing salt of choline hydroxide is strongly hygroscopic and therefore can easily absorb even trace amounts of moisture to form a flowable solution, allowing the salt to be easily removed from the process stream. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] U.S. Patent No. 7,279,089 Specification [Patent Document 2] U.S. Patent No. 8,177,962 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the use of choline hydroxide to mitigate fouling and corrosion also comes with several drawbacks: First, aqueous solutions of choline hydroxide have limited thermal stability above 180 °C, and furthermore develop unpleasant odors and discoloration during long-term storage.

[0006] Despite the progress made in the field of corrosion and fouling prevention and control, there is still a need for an effective and economically viable method to combat corrosion and fouling in chemical processes, especially those where high temperatures occur. The object of the present invention is therefore to provide, in a particular feature, a method that avoids the limitations of the aforementioned prior art procedures that use choline hydroxide to reduce corrosion and fouling, together with all the advantages of these procedures. The corrosion and fouling reducing or preventing compounds used in this method, as well as their aqueous solutions, must therefore have sufficient thermal and storage stability, and in particular be able to withstand temperatures well above 180°C without undergoing significant decomposition. Such temperatures are common, for example, in some fluid or gas streams in refineries and petrochemical systems, such as hydrodesulfurization plants. The compounds should furthermore have improved basicity and a better ability to dissolve ammonium salts, as compared to choline hydroxide. [Means for solving the problem]

[0007] This object is achieved by the method described in detail below. The present invention relates to a method for reducing or preventing corrosion or fouling in an apparatus for carrying out a chemical process, the corrosion or fouling being present during the chemical process. and wherein at least one quaternary ammonium hydroxide of formula (I) is added to an apparatus in which a chemical process is carried out. [ka] In the formula, R 1 , R 2 , R 3 are C1-C 10 is an alkyl group, R 4 is C1-C 18and aryl, benzyl, monocycloalkyl having 5, 6, 7 or 8 carbon atoms, bicycloalkyl having 6 to 8 carbon atoms, tricycloalkyl having 7 to 10 carbon atoms, where monocycloalkyl, bicycloalkyl and tricycloalkyl are unsubstituted or substituted with one or two methyl groups and a group of the formula R 4a and R 4b is substituted with the group [ka] In the formula, A is a C2-C8 alkanediyl. A' is a C2-C8 alkanediyl, and R 11 , R 12 , R 13 , R 21 , R 22 are each independently C1-C4 alkyl. R 1 and R 2 may together with the nitrogen atom form a 5- or 6-membered saturated nitrogen heterocycle which is unsubstituted or bears 1 or 2 methyl groups. and / or R 3 and R 4 may together with the nitrogen atom form a 5- or 6-membered saturated nitrogen heterocycle which is unsubstituted or bears 1 or 2 methyl groups.

[0008] The present invention further relates to the use of a quaternary ammonium hydroxide of formula (I) for reducing or preventing corrosion or fouling in equipment for carrying out chemical processes, where the corrosion or fouling is caused by acidic compounds present in the chemical process. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a partial GC / MS chromatogram of DEDMA-Cl pyrolysis products formed under the conditions of Example 10. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] In the context of the present invention, terms and phrases commonly used herein are defined as follows: Prefix “C” x -C y " indicates the number of carbon atoms possible in a particular case.

[0011] As used herein, "C1-C 18 The term "alkyl" includes alkyl groups having 1 to 4 ("C1-C4-alkyl"), 1 to 6 ("C1-C6-alkyl"), 1 to 10 ("C1-C 10 -alkyl") or 1 to 18 ("C1-C 18 C1-C4-Alkyl refers to a saturated linear or branched hydrocarbon radical having carbon atoms of 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 120, 112, 133, 140, 141, 152, 163, 170, C1-C are 1-ethyl-n-butyl, 1,2-dimethyl-n-butyl, 1,3-dimethyl-n-butyl, 2,2-dimethyl-n-butyl, 2,3-dimethyl-n-butyl, 3,3-dimethyl-n-butyl, 1-ethyl-n-butyl, 2-ethyl-n-butyl, 1,1,2-trimethyl-n-propyl, 1,2,2-trimethyl-n-propyl, 1-ethyl-1-methyl-n-propyl, or 1-ethyl-2-methyl-n-propyl. 10 -Alkyl is also, for example, n-heptyl, n-octyl, 2-ethyl-n-hexyl, n-nonyl, n-decyl and positional isomers thereof. 18-Alkyl is also, for example, n-undecyl, n-dodecyl, n-tridecyl, n-tetradecyl, n-pentadecyl, n-hexadecyl, n-heptadecyl, n-octadecyl and positional isomers thereof.

[0012] The term "monocycloalkyl having 5, 6, 7 or 8 carbon atoms" as used herein refers to monocyclic C5-C8-cycloalkyl radicals, i.e. cyclopentyl, cyclohexyl, cycloheptyl and cyclooctyl.

[0013] The term "bicycloalkyl having 6 to 8 carbon atoms" as used herein refers to a bridged alicyclic C6-C8-hydrocarbyl radical containing two bridgehead carbon atoms. Examples include, but are not limited to, bicyclo[2.1.1]hexyl, bicyclo[2.2.1]heptyl, also known as norbornyl, bicyclo[3.2.0]heptyl, bicyclo[4.1.0]heptyl, bicyclo[3.2.1]octyl and bicyclo[2.2.2]octyl.

[0014] As used herein, the term "tricycloalkyl having 7 to 10 carbon atoms" refers to a bridged alicyclic C7-C 10 - refers to a hydrocarbyl group. Examples include tricyclo[3.3.1.1], also known as adamantyl and tetrahydrodicyclopentadienyl, respectively. 3,7] Decanyl and tricyclo[5.2.1.0 2,6 ]decanyl.

[0015] The term "C2-C8-alkanediyl" as used herein refers to a divalent saturated aliphatic hydrocarbon diradical having 2 to 8 carbon atoms. Examples of C2-C8-alkanediyl include, in particular, linear alkanediyls such as 1,2-ethanediyl, 1,3-n-propanediyl, 1,4-n-butanediyl, 1,5-n-pentanediyl, 1,6-n-hexanediyl, 1,7-n-heptanediyl and 1,8-n-octanediyl, as well as branched alkanediyls such as 1-methyl-1,2-ethanediyl, 1-methyl-1,2-n-propanediyl, 2-methyl-1,3-n-butanediyl, 1,3-n-pentanediyl, 2-ethyl-1,6-n-hexanediyl, and the like.

[0016] The term "5- or 6-membered saturated nitrogen heterocycle" as used herein refers to saturated monocyclic rings containing one nitrogen atom as a ring member, i.e., pyrrolidinyl and piperidinyl.

[0017] The term "crude oil processing plant" includes plants where crude oil is processed, such as crude oil refineries, petrochemical plants, and plants that combine crude oil refining and petrochemical processes in a network. In formula (I), the variable R 1 , R 2 , R 3 , R 4 , R 4a , R 4b , R 11 , R 12 , R 13 , R 21 , R 22 , A and A', by themselves or in any combination, preferably have the following meanings:

[0018] Regardless of their occurrence, the variable R 1 , R 2 and R 3 are the same or different and are preferably selected from C1-C6-alkyl, in particular from C1-C4-alkyl, i.e. from the group consisting of methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl and tert-butyl. In particular, R1 , R 2 and R 3 are the same or different and are selected from the group consisting of methyl, ethyl, n-propyl and n-butyl.

[0019] Or, R 3 and R 4 are as defined herein and preferably have the meanings indicated as preferred, but the variable R 1 and R 2 may together with the nitrogen atom to which they are attached form a preferably unsubstituted 5- or 6-membered saturated nitrogen heterocycle, preferably having one methyl group.

[0020] Regardless of their occurrence, the variable R 11 , R 12 , R 13 , R 21 and R 22 are, when present in the quaternary ammonium hydroxide of formula (I), identical or different and are preferably selected from C1-C4-alkyl, i.e. from the group consisting of methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl and isobutyl, more preferably from the group consisting of methyl, ethyl, n-propyl and n-butyl, in particular from the group consisting of methyl and ethyl. Particularly preferred R 11 , R 12 , R 13 , R 21 and R 22 When present, each is methyl.

[0021] Variable A is preferably a linear C2-C8-alkanediyl diradical, more preferably a linear C2-C6-alkanediyl diradical. A particularly preferred variable A is hexanediyl.

[0022] Variable A' is preferably a linear C2-C8-alkanediyl diradical, more preferably a linear C2-C6-alkanediyl diradical.

[0023] Variable R 4a is selected from the group consisting of 2-(trimethylammonium)ethyl, 3-(trimethylammonium)-n-propyl, 4-(trimethylammonium)-n-butyl, 5-(trimethylammonium)-n-pentyl and 6-(trimethylammonium)-n-hexyl hydroxide salts, in particular 6-(trimethylammonium)-n-hexyl hydroxide salt.

[0024] Variable R 4b is selected from the group consisting of the dihydroxy salts of 2-(trimethylammonium)ethyl-(dimethylammonium)ethyl, 3-(trimethylammonium)-n-prop-1-yl-(dimethylammonium)-n-propyl, 4-(trimethylammonium)-n-but-1-yl-(dimethylammonium)-n-butyl, 5-(trimethylammonium)-n-pent-1-(dimethylammonium)-n-pentyl and 6-(trimethylammonium)-n-hex-1-yl-(dimethylammonium)-n-hexyl.

[0025] Variable R 4 is preferably C1-C 10 -alkyl, benzyl, cyclopentyl, cyclohexylbicycloalkyl having 7 or 8 carbon atoms, tricycloalkyl having 9 or 10 carbon atoms, where monocycloalkyl, bicycloalkyl and tricycloalkyl are unsubstituted or have one or two methyl groups and a group of formula R 4a where R 4a Variable element R 11 , R 12 , R 13 and A have the meanings, particularly preferred meanings, defined herein. More preferably, R 4is selected from the group consisting of C1-C4-alkyl, benzyl, cyclopentyl, cyclohexyl, norbornyl, 7,7-dimethylnorbornyl, bicyclo[3.2.0]heptyl, bicyclo[4.1.0]heptyl, bicyclo[3.2.1]octyl, bicyclo[2.2.2]octyl, adamantyl, 1-methyladamantyl, 1,3-dimethyladamantyl, tetrahydrodicyclopentadienyl, and the hydroxide salts of 6-(trimethylammonium)hexyl. 4 is in particular selected from the group consisting of the hydroxide salts of methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, benzyl, cyclopentyl, cyclohexyl, norbornyl, adamantyl, and 6-(trimethylammonium)hexyl, in particular selected from the hydroxide salts of methyl, ethyl, n-propyl, n-butyl, benzyl, adamantyl, and 6-(trimethylammonium)hexyl.

[0026] Or, the variable R 3 and R 4 may, together with the nitrogen atom to which they are attached, form a 5- or 6-membered saturated nitrogen heterocycle, preferably having one methyl group or preferably unsubstituted, which is represented by R 1 and R 2 are as defined herein and preferably have the meanings given as preferred.

[0027] In one preferred group of embodiments, the variable R in the quaternary ammonium hydroxide of formula (I) 1 , R 2 , R 3 and R 4 is defined as follows: R 1 , R 2 and R 3 are the same or different and are selected from C1-C6-alkyl, in particular C1-C4-alkyl, i.e. from the group consisting of methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl and tert-butyl. In particular, R 1 , R2 and R 3 are the same or different and are selected from the group consisting of methyl, ethyl, n-propyl and n-butyl. R 4 is C1-C 10 - selected from the group consisting of alkyl, benzyl, cyclopentyl, cyclohexyl, bicycloalkyl having 7 or 8 carbon atoms, tricycloalkyl having 9 or 10 carbon atoms, where monocycloalkyl, bicycloalkyl and tricycloalkyl are unsubstituted or have one or two methyl groups and a group of the formula R 4a where R 4a Variable element R 11 , R 12 , R 13 and A have the meanings, particularly preferred meanings, defined herein. More preferably, R 4 is selected from the group consisting of C1-C4-alkyl, benzyl, cyclopentyl, cyclohexyl, norbornyl, 7,7-dimethylnorbornyl, bicyclo[3.2.0]heptyl, bicyclo[4.1.0]heptyl, bicyclo[3.2.1]octyl, bicyclo[2.2.2]octyl, adamantyl, 1-methyl-adamantyl, 1,3-dimethyladamantyl, tetrahydrodicyclopentadienyl, and the hydroxide salts of 6-(trimethylammonium)hexyl. 4 is in particular selected from the group consisting of the hydroxide salts of methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, benzyl, cyclopentyl, cyclohexyl, norbornyl, adamantyl and 6-(trimethylammonium)hexyl, in particular selected from the hydroxide salts of methyl, ethyl, n-propyl, n-butyl, benzyl, adamantyl and 6-(trimethylammonium)hexyl.

[0028] In another preferred group of embodiments, the variable R in the quaternary ammonium hydroxide of formula (I) 1 , R 2 , R 3 and R 4 is defined as follows: R 1 and R 2 together with the nitrogen atom to which they are attached form a 5- or 6-membered saturated nitrogen heterocycle which carries one methyl group or is preferably unsubstituted. R 3 is selected from the group consisting of C1-C6-alkyl, in particular C1-C4-alkyl, i.e. methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl and tert-butyl. In particular, R 3 is selected from the group consisting of methyl, ethyl, n-propyl and n-butyl. R 4 is C1-C 10 - alkyl, benzyl, cyclopentyl, cyclohexyl, bicycloalkyl having 7 or 8 carbon atoms, tricycloalkyl having 9 or 10 carbon atoms, where monocycloalkyl, bicycloalkyl and tricycloalkyl are unsubstituted or have one or two methyl groups, and the formula R 4a wherein the formula R 4a Variable element R 11 , R 12 , R 13 and A have the meanings, particularly preferred meanings, defined herein. More preferably, R 4 is selected from the group consisting of C1-C4-alkyl, benzyl, cyclopentyl, cyclohexyl, norbornyl, 7,7-dimethylnorbornyl, bicyclo[3.2.0]heptyl, bicyclo[4.1.0]heptyl, bicyclo[3.2.1]octyl, bicyclo[2.2.2]octyl, adamantyl, 1-methyladamantyl, 1,3-dimethyladamantyl, tetrahydrodicyclopentadienyl, and the hydroxide salts of 6-(trimethylammonium)hexyl. 4is in particular selected from the group consisting of the hydroxide salts of methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, benzyl, cyclopentyl, cyclohexyl, norbornyl, adamantyl, and 6-(trimethylammonium)hexyl, in particular selected from the hydroxide salts of methyl, ethyl, n-propyl, n-butyl, benzyl, adamantyl, and 6-(trimethylammonium)hexyl.

[0029] In a further preferred group of embodiments, the variable R in the quaternary ammonium hydroxide of formula (I) 1 , R 2 , R 3 and R 4 is defined as follows: R 1 and R 2 together with the nitrogen atom to which they are attached form a 5- or 6-membered saturated nitrogen heterocycle which carries one methyl group or is preferably unsubstituted. R 3 and R 4 together with the nitrogen atom to which they are attached form a 5- or 6-membered saturated nitrogen heterocycle which carries one methyl group or is preferably unsubstituted.

[0030] In a particular preferred group of embodiments, R 1 , R 2 , R 3 are each independently C1-C6-alkyl, preferably each independently C1-C4-alkyl, in particular independently selected from methyl, ethyl, n-propyl and n-butyl; and R 4 is C1-C 18 -Alkyl, benzyl, cyclopentyl, cyclohexyl, C7-C8-bicycloalkyl, C9-C 10 -tricycloalkyl or 6-(trimethylammonium)hexyl hydroxide salts, preferably C2-C 10 -Alkyl, benzyl, norbornyl, adamantyl or 6-(trimethylammonium)hexyl hydroxide salts.

[0031] In a further particular preferred group of embodiments, R 1 and R 2 is linked together with the nitrogen atom to form an unsubstituted or 5- or 6-membered saturated nitrogen heterocycle having one or two methyl groups, preferably an unsubstituted 5- or 6-membered saturated nitrogen heterocycle, in particular an unsubstituted pyrrolidinium ring; R 3 are C1-C6-alkyl, preferably each independently C1-C4-alkyl, in particular independently selected from methyl, ethyl, n-propyl and n-butyl; and R 4 is C1-C 18 -Alkyl, benzyl, cyclopentyl, cyclohexyl, C7-C8-bicycloalkyl, C9-C 10 -tricycloalkyl or 6-(trimethylammonium)hexyl hydroxide salts, preferably C-C 10 -Alkyl, benzyl, norbornyl, adamantyl or 6-(trimethylammonium)hexyl hydroxide salts.

[0032] In a further particular group of preferred embodiments, R 1 and R 2 form together with the nitrogen atom to which they are attached an unsubstituted or 5- or 6-membered saturated nitrogen heterocycle carrying one or two methyl groups, preferably an unsubstituted 5- or 6-membered saturated nitrogen heterocycle, in particular an unsubstituted pyrrolidinium ring; and R 3 and R 4 combine with the nitrogen atom to which they are attached to form an unsubstituted or 5- or 6-membered saturated nitrogen heterocycle bearing one or two methyl groups, preferably an unsubstituted 5- or 6-membered saturated nitrogen heterocycle, in particular an unsubstituted pyrrolidinium ring.

[0033] Examples of preferred quaternary ammonium hydroxides of formula (I) according to the group of embodiments described above for use in the method of the present invention are cyclopentyltrimethylammonium hydroxide, cyclohexyltrimethylammonium hydroxide, norbornyltrimethylammonium hydroxide, adamantyltrimethylammonium hydroxide, 5-azonia-spiro[4.4]nonane hydroxide, benzyltrimethylammonium hydroxide, diethyldimethylammonium hydroxide, ethyltrimethylammonium hydroxide, dimethyldi-n-propylammonium hydroxide, n-propyltrimethylammonium hydroxide, triethylmethylammonium hydroxide, tetramethylammonium hydroxide, diethyldi-n-propylammonium hydroxide, n-propyltriethylammonium hydroxide, dimethyldi-n-butylammonium hydroxide, n-butyltrimethyl ... and preferably selected from the group consisting of adamantyltrimethylammonium hydroxide, tetraethylammonium hydroxide, tetra-n-propylammonium hydroxide, tetra-n-butylammonium hydroxide, hexamethonium hydroxide and N,N-dimethylpyrrolidinium hydroxide; and preferably selected from adamantyltrimethylammonium hydroxide, 5-azonia-spiro[4.4]nonane hydroxide, benzyltrimethylammonium hydroxide, diethyldimethylammonium hydroxide, ethyltrimethylammonium hydroxide, dimethyldi-n-propylammonium hydroxide, triethylmethylammonium hydroxide, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetra-n-propylammonium hydroxide, tetra-n-butylammonium hydroxide, hexamethonium hydroxide and N,N-dimethylpyrrolidinium hydroxide.In particular, it is selected from adamantyltrimethylammonium hydroxide, 5-azonia-spiro[4.4]nonane hydroxide, benzyltrimethylammonium hydroxide, diethyldimethylammonium hydroxide, ethyltrimethylammonium hydroxide, dimethyldi-n-propylammonium hydroxide, triethylmethylammonium hydroxide, tetraethylammonium hydroxide, tetra-n-propylammonium hydroxide, tetra-n-butylammonium hydroxide, hexamethonium hydroxide and N,N-dimethylpyrrolidinium hydroxide.

[0034] In a further preferred group of embodiments, the variable R in the quaternary ammonium hydroxide of formula (I) 1 , R 2 , R 3 and R 4 is defined as follows: R 1 , R 2 , R 3 are each independently C1-C6-alkyl, preferably each independently C1-C4-alkyl, in particular independently selected from methyl, ethyl, n-propyl and n-butyl; R 4 is C1-C 18 -alkyl, preferably C-C 18 -alkyl, in particular C2-C4-alkyl, in particular selected from ethyl, n-propyl and n-butyl; Or alternatively: R 3 and R 4 combine with the nitrogen atom to which they are attached to form an unsubstituted or 5- or 6-membered saturated nitrogen heterocycle bearing one or two methyl groups, preferably an unsubstituted 5- or 6-membered saturated nitrogen heterocycle, in particular an unsubstituted pyrrolidinium ring.

[0035] Examples of preferred quaternary ammonium hydroxides of formula (I) according to this group of embodiments for use in the method of the present invention are selected from the group consisting of diethyldimethylammonium hydroxide, ethyltrimethylammonium hydroxide, dimethyldi-n-propylammonium hydroxide, n-propyltrimethylammonium hydroxide, triethylmethylammonium hydroxide, tetramethylammonium hydroxide, diethyldi-n-propylammonium hydroxide, n-propyltriethylammonium hydroxide, dimethyldi-n-butylammonium hydroxide, n-butyltrimethylammonium hydroxide, n-butyltriethylammonium hydroxide, tetraethylammonium hydroxide, tetra-n-propylammonium hydroxide, tetra-n-butylammonium hydroxide and N,N-dimethylpyrrolidinium hydroxide; in particular selected from diethyldimethylammonium hydroxide, ethyltrimethylammonium hydroxide, dimethyldi-n-propylammonium hydroxide, triethylmethylammonium hydroxide, tetraethylammonium hydroxide, tetra-n-propylammonium hydroxide, tetra-n-butylammonium hydroxide and N,N-dimethylpyrrolidinium hydroxide.

[0036] In a particularly preferred group of embodiments, the variable R in the quaternary ammonium hydroxide of formula (I) 1 , R 2 , R 3 and R 4 is defined as follows: R 1 , R 2 , R 3 are each independently C1-C6 alkyl, preferably each independently C1-C4 alkyl, in particular independently selected from methyl, ethyl, n-propyl and n-butyl; and R 4 is C2-C6 alkyl, in particular C2-C4-alkyl, specifically selected from ethyl, n-propyl and n-butyl.

[0037] Examples of preferred quaternary ammonium hydroxides of formula (I) according to the group of embodiments for use in the method of the present invention are diethyldimethylammonium hydroxide, ethyltrimethylammonium hydroxide, dimethyldi-n-propylammonium hydroxide, n-propyltrimethylammonium hydroxide, triethylmethylammonium hydroxide, diethyldi-n-propylammonium hydroxide, n-propyltriethylammonium hydroxide, dimethyldi-n-butylammonium hydroxide, n-butyltrimethylammonium hydroxide, n-butyltriethylammonium hydroxide, tetraethylammonium hydroxide, tetra-n-propylammonium hydroxide, in particular, it is selected from the group consisting of diethyldimethylammonium hydroxide (DEDMAH), ethyltrimethylammonium hydroxide (ETMAH), dimethyldi-n-propylammonium hydroxide (DMDPAH), triethylmethylammonium hydroxide (TEMAH), tetraethylammonium hydroxide (TEAH), tetra-n-propylammonium hydroxide (TPAH) and tetra-n-butylammonium hydroxide (TBAH), in particular, it is selected from the group consisting of DEDMAH, TEMAH, TEAH, TPAH, and TBAH.

[0038] In particular, the at least one quaternary ammonium hydroxide of formula (I) is selected from DEDMAH, TEMAH, TEAH, TPAH and TBAH, and mixtures thereof, of which preference is given to TEAH and mixtures of TEAH with one or more quaternary ammonium hydroxides of formula (I), different from TEAH, in particular DEDMAH, TEMAH, TPAH and TBAH.

[0039] The present invention provides a method for reducing or preventing corrosion or fouling in equipment for carrying out chemical processes, where corrosion refers to the corrosive modification of metal parts that are part of the equipment, and fouling refers to the accumulation and deposition of unwanted materials on the interior surfaces of the equipment. Corrosion and fouling are caused by acidic compounds present in the chemical process.

[0040] Here and below, the phrase "acidic compounds present in a chemical process" refers to the following situation. - the acidic compounds are to be treated in a chemical process and therefore are already contained in the feedstock introduced into the equipment for carrying out the chemical process; and / or - Acidic compounds are only produced during the process.

[0041] To achieve the reduction or prevention of corrosion or fouling, the method includes adding at least one quaternary ammonium hydroxide of formula (I), in particular at least one of the ammonium hydroxides of formula (I) described herein as being preferred, to the equipment in which the chemical process is carried out.

[0042] Typically, one or a mixture of two or more ammonium hydroxides (I) of formula (I) are added. When such mixtures are used, preference is given to mixtures containing two or more, especially two or three, selected from the ammonium hydroxides (I) mentioned as preferred herein, in particular TEAH, TPAH, TBAH, TEMAH and DEDMAH, and in particular mixtures consisting of TEAH and DEDMAH, TEAH and TEMAH, or TEAH, DEDMAH and TEMAH. However, other mixtures of ammonium hydroxides of formula (I) can also be used in the process of the present invention to adjust the properties of the salt obtained after reaction of the ammonium hydroxide of formula (I) with the acidic compounds present in the equipment to be treated, as discussed herein below.

[0043] In one group of embodiments of the invention, at least one ammonium hydroxide (I) is introduced into the fluid or gas stream of a chemical process carried out in an apparatus, where the ammonium hydroxide of formula (I) is added as such or preferably in the form of a solution. Addition can be accomplished by metering one or more ammonium hydroxides of formula (I) into the feed entering the apparatus, or by inserting them into specific locations in apparatus that are often located upstream of a section or unit of the apparatus that has already been or may be subject to corrosion or fouling.

[0044] By applying the method of the invention, it is in principle possible to largely eliminate acidic compounds from chemical processes or to largely prevent their formation during these processes, since the at least one quaternary ammonium hydroxide of formula (I) used neutralizes such acidic compounds and converts them into their corresponding salts, which generally promote corrosion and fouling to a much lesser extent than the respective acidic compounds.

[0045] Examples of acidic compounds that may cause corrosion and / or fouling in equipment for chemical processes include, but are not limited to, hydrogen halides such as hydrogen chloride, hydrogen fluoride or hydrogen bromide, especially hydrogen chloride, hydrogen sulfide, hydrogen cyanide, thiocyanic acid, sulfuric acid, SO2, SO3, nitrogen oxides, especially NO and NO2, carbonic acid, CO2, organic acids, especially carboxylic and sulfonic acids, acidic ammonium salts, acidic phosphorus compounds, and mixtures thereof. The aforementioned protonic acids and protonic acids derived from the aforementioned oxides are known to primarily promote corrosion processes, but may also contribute to chemical plant fouling, and acidic ammonium salts are often involved in both corrosion and fouling. More specifically, hydrogen halides, hydrogen sulfide, hydrogen cyanide, thiocyanic acid, organic acids, and acidic ammonium salts are corrosive species and contaminants frequently found in crude oil refining processes and petrochemical processes, especially crude oil refining processes. Acidic phosphorus compounds may also be found in crude oil grades such as shale oil. On the one hand, carbonic acid and CO2, together with organic acids, are the main corrosive species in steam generating equipment such as boiler systems typically used in chemical processes, while on the other hand, nitrogen oxides, formed for example in combustion processes, cause corrosion problems mainly on the flue gas side of combustion equipment such as diesel engines.

[0046] The method of the present invention is particularly suitable for reducing or preventing corrosion caused by acidic compounds selected from the group consisting of hydrogen chloride, hydrogen fluoride, SO3, nitrogen oxides, acidic ammonium salts and acidic phosphorus compounds. The acidic ammonium compounds and acidic phosphorus compounds can be either inorganic or organic compounds. Examples of acidic ammonium salts include, but are not limited to, ammonium chloride and N-substituted ammonium chlorides, inorganic and organic ammonium halides such as ammonium fluoride or ammonium bromide, especially ammonium chloride, organic ammonium chlorides, di- and tri-C1-C4-alkylammonium chlorides such as trimethylammonium chloride or triethylammonium chloride, hydrochlorides of alkylenediamines such as ethylenediamine monohydrochloride, hydrochlorides of alkanolamines such as dimethylethanolammonium chloride, and hydrochlorides of alkoxyalkylamines such as 3-methoxylpropylammonium chloride, ammonium hydrogen sulfide, ammonium sulfide, ammonium hydrogen sulfate, ammonium sulfate, and ammonium salts of carboxylic acids having 1 to 10 carbon atoms such as ammonium formate, ammonium acetate, ammonium propionate or ammonium butyrate, especially ammonium acetate. Acidic phosphorus compounds include, but are not limited to, phosphoric acid, polyphosphoric acid, acidic phosphates and acidic polyphosphates, phosphonic acid and acidic phosphonates. Polyphosphoric acid and acidic polyphosphates have at least two P atoms, for example, an average of 2 to 1000 P atoms, and may be linear, branched, or cyclic. Examples of acidic phosphates include partial esters of phosphoric acid, as well as monohydrogen phosphates and dihydrogen phosphates of alkali metals or alkaline earth metals. Examples of acidic polyphosphates include acid salts of polyphosphoric acid, particularly acidic polyphosphates of alkali metals or alkaline earth metals.

[0047] Of particular relevance as acidic compounds causing corrosion or fouling are hydrogen chloride, hydrogen fluoride, sulfur trioxide, nitrogen oxides, ammonium chloride, organic ammonium chlorides such as trimethylammonium chloride, triethylammonium chloride, ethylenediamine monohydrochloride, dimethylethanolammonium chloride and 3-methoxypropylammonium chloride, ammonium sulfide, ammonium hydrogen sulfide, ammonium sulfate and ammonium hydrogen sulfate, in particular hydrogen chloride, ammonium chloride and organic ammonium chlorides. The method of the invention is particularly suitable for combating the corrosive and fouling effect of these compounds in equipment for carrying out chemical processes.

[0048] The quaternary ammonium hydroxides of formula (I) used in the process of the present invention are highly soluble in water and also in mixtures of water with C1-C4-alkanols such as methanol, ethanol, propanol or butanol. As the inventors of the present application have discovered, aqueous solutions of ammonium hydroxide (I), especially those with high concentrations of about 10 to 60% by weight or 20 to 40% by weight, are very stable during storage, even at elevated temperatures up to 50° C.

[0049] The term aqueous solution is understood as a solution of a compound of formula (I) in water or in a mixture of water with one or more water-miscible organic solvents, such as a mixture of water with one or more C1-C4-alkanols, in which water is the main component of the mixture of water and organic solvent, i.e. the amount of water is at least 50% by weight, based on the total weight of the mixture of water and organic solvent.

[0050] Thus, unlike the corresponding solutions of choline hydroxide, they are characterized by a high resistance to discoloration and odor development. Indeed, the solutions of ammonium hydroxide of formula (I) remain clear and colorless and have only a very weak odor after long-term storage at 40° C., while the choline hydroxide solutions turn yellow and emit a very strong fishy odor. Thus, the aqueous solutions of ammonium hydroxide of formula (I) have a higher storage stability than the respective choline hydroxide solutions and are particularly well suited for long-term storage even under adverse storage conditions.

[0051] A particular advantage associated with the present invention is the fact that ammonium hydroxides of formula (I) and their aqueous solutions have good stability at temperatures well above 200 ° C, i.e. under these conditions the rate of decomposition of ammonium hydroxide of formula (I) is low. Thus, ammonium hydroxides of formula (I), and especially their aqueous solutions, can be safely introduced into process streams having temperatures up to 250 ° C, because ammonium hydroxides of formula (I) remain unchanged for long periods at such temperatures and can therefore effectively combat corrosion and fouling. Their stability at high temperatures is a very beneficial property of aqueous solutions of ammonium hydroxides of formula (I), because they can be injected into high-temperature locations, such as, for example, the feed / effluent heat exchangers of hydrodesulfurization plants, without significantly losing their effectiveness against corrosion and fouling. This is difficult or impossible with choline hydroxide and its solutions, which decompose very strongly already at temperatures above 200 ° C.

[0052] Furthermore, due to their high stability, the ammonium hydroxides of formula (I) and their aqueous solutions can be introduced into process streams upstream of conventional corrosion and antifouling agents, thus allowing them to enter hard-to-reach places in equipment that were previously largely inaccessible, such as process plants.

[0053] Moreover, ammonium hydroxides of formula (I) are much stronger bases than ammonia and any organic amines. Their base strength is in fact equal to or even greater than that of choline hydroxide. This property makes it possible to achieve high anticorrosion and antifouling activity at lower molar dosages compared to prior art methods. Due to this very strong basicity, ammonium hydroxides of formula (I) also react readily with protonic acids such as hydrogen chloride, hydrogen sulfide and organic acids to form the corresponding salts. The most relevant acid here is usually hydrogen chloride, which, when converted with ammonium hydroxide of formula (I), produces quaternary ammonium chloride salts of formula (II). [ka] where the variable R 1 , R 2 , R 3 and R 4 has the same meaning, in particular the same preferred meaning, as defined in connection with formula (I).

[0054] Ammonium hydroxide of formula (I) also reacts easily with acidic ammonium salts, such as ammonium chloride, and organic ammonium salts, to liberate ammonia or the respective amines and form quaternary ammonium salts, such as chlorides of formula (II), in particular. Thus, the inventors of the present application have found that ammonium chloride is dissolved much more actively by dilute solutions of ammonium hydroxide of formula (I) than those of choline hydroxide. In conclusion, ammonium hydroxide of formula (I) is highly suitable for neutralizing corrosion-inducing protonic acids, as well as dissolving acidic ammonium salts in fouled systems and preventing the deposition of such fouling salts.

[0055] The suitability of ammonium hydroxides of formula (I) for controlling corrosion and fouling in chemical plants also depends on the physicochemical properties of the salts they form when reacting with acidic compounds, in particular selected from protonic acids and acidic ammonium salts. Here, the melting point and decomposition point of these salts derived from ammonium hydroxide of formula (I) are of particular interest, since they strongly influence the fate of said salts located at specific locations in the plant treated with ammonium hydroxide (I) according to the method of the invention. More specifically, the melting point determines the temperature at which the salts significantly improve their flow behavior, while the decomposition point defines the temperature at which potentially troublesome decomposition products are formed. After all, in particular the chlorides derived from ammonium hydroxide of formula (I), i.e. the salts of formula (II), often have melting points below 80°C and decomposition points above 200°C and even above 250°C. Their melting points are therefore often much lower than that of choline chloride and their decomposition points are above the temperatures prevalent in most units of chemical plants. For these reasons, the use of ammonium hydroxides of formula (I) is advantageous, since the salts formed, for example, by their reaction with acidic compounds, are already mobile at low temperatures and can therefore be easily transported and removed from the plant units treated with ammonium hydroxide of formula (I). Moreover, due to their very high decomposition points, the salts formed withstand high process temperatures without undergoing decomposition and are easily removed from the process units in the form of aqueous solutions. Indeed, due to the very good water solubility of the salts, even very small amounts of liquid water or steam present in the treated process streams are sufficient to facilitate their removal.

[0056] From the above, it is clear that not only the ammonium hydroxides of formula (I) used in the treatment according to the method of the invention, but also the salts into which they are converted by reaction with acidic compounds present in the chemical process, have very high decomposition points. Thus, the process streams in the equipment in which the process is carried out can be heated to high temperatures without the risk of decomposing the ammonium hydroxide of formula (I) or the salts formed therefrom. Thus, the fluid or gas stream of the chemical process can be exposed to a temperature of at least 100°C, often at least 150°C, in particular at least 180°C, especially at least 200°C or at least 250°C during or after the addition of ammonium hydroxide (I) to this stream.

[0057] Furthermore, salts derived from ammonium hydroxide (I), particularly the chloride salts of formula (II), are generally not only highly water soluble but are also typically hygroscopic, although the degree of hygroscopicity varies between different salts (II). Due to their hygroscopicity, salts derived from ammonium hydroxide (I), such as salt (II), readily absorb the minimal amount of water present in the treated process stream, resulting in the formation of a flowable solution. This allows for easy removal of the salt from the stream, for example, via aqueous solutions discharged from various process units, such as gas-liquid and oil-water separators. As a result, by applying ammonium hydroxide (I) according to the method of the present invention, deposits including corrosion- or fouling-causing salts, such as ammonium chloride and organic ammonium chlorides, can be effectively removed from the treated system.

[0058] Moreover, as experiments by the inventors of the present application have shown, the addition of even small amounts of strongly hygroscopic chloride salts of formula (II) can significantly increase the hygroscopicity of weakly hygroscopic chloride salts (II). This also applies to salts derived from ammonium hydroxides of formula (I) other than chlorides. Thus, the mixing of two or more different ammonium hydroxides of formula (I) in specific and easily identifiable ratios allows the formation of a mixture of salts after processing, whose hygroscopicity is adjusted and fine-tuned to the special requirements of "wet" or "dry" systems, i.e. systems with relatively high or low water content. An example of a wet system is the overhead section of a distillation column using stripping steam, such as an atmospheric distillation column. An example of a dry system is the feed / effluent heat exchanger of a gasoline hydrodesulfurization unit. Thus, one group of embodiments of the present invention relates to the method of the present invention, which uses a mixture of ammonium hydroxides (I) preferably in a specific ratio to each other. In this context, preference is given to mixtures, which result in the formation of a mixture of salts (II) with specific sought-after physicochemical properties, for example optimized hygroscopicity.

[0059] The salts of formula (II) and salts derived from ammonium hydroxide (I) other than the chloride (II), i.e., the compound of formula (IIa), have a near-neutral pH when dissolved in water and are much less corrosive than ammonium chloride and the chloride salts formed from amines such as monoethanolamine (MEA), which are traditionally used to neutralize corrosive acidic compounds. [ka] Where X - is a nonbasic and nonacidic counterion such as bromide, sulfate, or nitrate. Therefore, due to their very low corrosivity, the salts derived from ammonium hydroxide (I), especially those of formulae (II) and (IIa), which are formed in chemical process units when treated with ammonium hydroxide of formula (I) according to the method of the present invention, hardly have a detrimental effect on the metal surfaces in the units. These salts therefore do not cause significant corrosion damage even if they remain in the process units for a long period of time, but are already removed by the traces of water or steam usually present in the process stream, as mentioned above. In conclusion, the use of ammonium hydroxide of formula (I) as a corrosion and antifouling agent has the additional advantage that the secondary corrosion often caused by salts derived from the reaction of conventional agents with acidic compounds is greatly reduced.

[0060] As outlined above, the salts produced by converting ammonium hydroxide of formula (I) with acidic compounds, especially salts of formula (II), not only have very high decomposition points but can also be easily removed from chemical process streams. However, in rare cases, if such a salt is exposed to temperatures above its decomposition point, it decomposes into non-hazardous compounds. Thus, the inventors of the present application have been able to demonstrate that in all cases, the thermal decomposition of different salts of formula (II) leads to the corresponding alkyl chlorides and trialkylamines as the main decomposition products. For example, tetraethylammonium chloride (TEA-Cl) decomposes mainly into ethyl chloride and triethylamine, while diethyldimethylammonium chloride (DEDMA-Cl) decomposes into methyl chloride, ethyl chloride, diethylmethylamine, and ethyldimethylamine. The alkyl chlorides formed are removed from the process, e.g., separators, columns, or heat exchangers, via the gas stream and therefore do not adversely affect the process or the equipment in which the process is carried out. On the other hand, the trialkylamines formed may act as additional bases to neutralize corrosive acidic compounds, which are then removed from the system as ammonium salts. It is important to note that during the thermal decomposition of the salt of formula (II), substantially no corrosive hydrogen chloride is formed. According to this thermal decomposition pathway of salt (II), chlorides originating from corrosive or fouling species such as hydrogen chloride and ammonium chloride are safely and permanently removed from the process plant in the form of alkyl chlorides.

[0061] In one group of embodiments of the present invention, at least one quaternary ammonium hydroxide of formula (I) is added to a chemical process as a solution of one or more ammonium hydroxides (I). Such a solution is preferably prepared by dissolving at least one ammonium hydroxide (I) in a solvent selected from water, C1-C4-alkanols such as methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol or isobutanol, and mixtures thereof. Preferred solvents here are water, ethanol, n-propanol, isopropanol, n-butanol, isobutanol and sec-butanol, and mixtures thereof, such as mixtures of water with ethanol, propanol, isopropanol, n-butanol, isobutanol or sec-butanol. The total concentration of at least one ammonium hydroxide (I) in these solutions is often in the range of 10 to 60% by weight, preferably in the range of 10 to 50% by weight, in particular in the range of 10 to 40% by weight.

[0062] At least one solution of ammonium hydroxide of formula (I) used in the method of the present invention to reduce or prevent corrosion or fouling may optionally further comprise one or more additives selected from dispersants, such as polyisobutylene succinimides, antioxidants / depolymerization agents, such as tert-butylphenol derivatives, phenylenediamines, N-oxyl compounds such as 2,2,6,6-tetramethyl-piperidine-N-oxyl (TEMPO) and derivatives of TEMPO, such as 4-hydroxy-2,2,6,6-tetramethyl-piperidine-N-oxyl (4-OH-TEMPO), and antifoaming agents, such as copolymers of ethylene oxide and propylene oxide, polypropylene glycol or silicone oil. The solution may optionally comprise additional active substances, including, for example, further anticorrosive and antifouling agents, such as choline hydroxide, and neutralizing amines, such as alkylamines or alkanolamines.

[0063] Furthermore, the solution of at least one ammonium hydroxide of formula (I) may optionally contain an active substance that is not related to the control of corrosion or fouling, but has a clearly different function. An example of such an active substance is 4-tert-butylcatechol (TBC), which is a polymerization inhibitor and is therefore suitable as a stabilizer for monomers. The solution according to the invention containing TBC and at least one ammonium hydroxide of formula (I) is useful for antifouling applications in process plants or units thereof that contain monomers, such as the process water system of an ethylene plant. The combination of quaternary ammonium hydroxide of formula (I) and TBC has the surprising additional advantage that the quaternary ammonium hydroxide of formula (I) promotes the dissolution of the weakly acidic TBC in water due to their strong basicity. Thus, other potentially harmful auxiliaries for dissolving TBC are not required to prepare a bifunctional formulation containing both ammonium hydroxide of formula (I) and TBC.

[0064] At least one ammonium hydroxide of formula (I) can be introduced into the chemical process at one or more locations in the equipment in which the chemical process is carried out, for example, in different units of a process plant. Preferably, the ammonium hydroxide (I) is introduced into the process by injecting its solution into one or more locations or into one or more units of the equipment or process plant. Injection is usually carried out by continuous injection methods such as metered injection or flow-proportional injection, or by intermittent injection methods such as suction injection or forced injection.

[0065] At least one ammonium hydroxide of formula (I) is introduced into the fluid stream of the chemical process based on the amount of the fluid or stream of the chemical process at each location where the addition is made, usually in an amount ranging from 1 to 5000 ppm, in particular in the range from 1 to 2500 ppm, more preferably in the range from 1 to 1000 ppm, in particular in the range from 1 to 500 ppm. It is particularly preferred to adjust the amount of ammonium hydroxide of formula (I) added to the amount of corrosive species and / or contaminants in the fluid stream to be treated, in particular the amount of protonic acids and / or acidic ammonium salts. In this way, ammonium hydroxide of formula (I) is added only in the amount necessary, for example, to neutralize corrosive acids such as hydrogen chloride contained in the stream or to dissolve deposits containing ammonium chloride in the process unit. For example, it may be useful to measure the pH value or chloride concentration of the appropriate part of the process unit and determine the amount of ammonium hydroxide of formula (I) to be added based on the measured value. Alternatively, in other cases, it may be sufficient to add a certain amount of ammonium hydroxide of formula (I) to an established process, which experience has shown to be appropriate. In both of the above examples, the addition of ammonium hydroxide of formula (I) is preferably accomplished by continuous or intermittent injection of a solution of ammonium hydroxide of formula (I) into one or more locations in the plant.

[0066] According to a preferred group of embodiments of the method of the present invention, the chemical process is a crude oil treatment, such as a crude oil refining process and / or a petrochemical process, in particular a crude oil refining process and / or a petrochemical process. In this context, a crude oil refining process typically comprises one or more processing units selected from a crude oil atmospheric distillation unit, a crude oil vacuum distillation unit, a visbreaker unit, a delayed coker unit, a fluid catalytic cracking unit, a reformer unit, a hydrocracker unit, an alkanolamine unit, a sulfinol unit and a hydrodesulfurization unit.

[0067] The crude distillation unit (CDU), also called the crude atmospheric distillation unit, is generally the first processing unit in every oil refinery. In the CDU, the incoming crude oil is distilled into various fractions with different boiling ranges, each of which may be further processed in other refinery processing units. Distillation in the CDU is usually carried out at a pressure slightly higher than atmospheric pressure. The CDU usually consists of, as its main components, a heat exchanger, a desalter, a furnace, a distillation column mounted in series, and a side stripper and a reflux drum. The first preferred dosing point, i.e., where one or more ammonium hydroxides (I), or preferably a solution thereof, can be beneficially added to the CDU, is the pipe exiting the desalter. The introduction of ammonium hydroxide of formula (I) at this location serves as a partial or complete replacement of sodium hydroxide, which is often used to remove calcium chloride and magnesium chloride from the crude oil exiting the desalter by converting them to their corresponding hydroxides. If calcium chloride and magnesium chloride remain in the crude oil, they will undergo hydrolysis in the furnace, producing hydrogen chloride gas that dissolves in the condensed water, thus leading to corrosion in the overhead section of the distillation column. However, the use of sodium hydroxide is associated with disadvantages, one of which is that the sodium salt may contaminate catalysts used in downstream processing units such as hydrodesulfurization or catalytic cracking units. These disadvantages can be avoided or mitigated by completely or partially replacing the sodium hydroxide with ammonium hydroxide of formula (I), especially since ammonium hydroxide of formula (I) is also a strong base but does not contain sodium.

[0068] Further preferred administration points where one or more ammonium hydroxides (I), preferably solutions thereof, may be beneficially introduced into the CDU are the overhead sections and distillation columns, as well as the connecting pipes, condensers, heat exchangers, receiving tanks, and other components attached thereto. Introducing ammonium hydroxide of formula (I) at these locations helps combat corrosion and salt damage.

[0069] In a crude vacuum distillation unit (VDU), generally, the high boiling bottom fraction from the atmospheric distillation is fractionated by subjecting it to vacuum distillation. The main component of the VDU is the distillation column. Preferred administration points where one or more ammonium hydroxides of formula (I), preferably a solution thereof, can be beneficially introduced into the VDU are the overhead section and the distillation column, as well as the connecting pipes, condensers, heat exchangers, receiving tanks and other components attached thereto. Introducing ammonium hydroxide of formula (I) into these locations helps combat corrosion and salt damage.

[0070] In the visbreaker unit, also called visbreaker, the residue from the vacuum distillation is thermally cracked into more valuable lighter boiling components. The main components of the visbreaker are a feed / effluent heat exchanger, a furnace, a holdup vessel (soaker), a distillation column or a series of distillation columns. Preferred administration points where one or more ammonium hydroxides of formula (I), preferably a solution thereof, can be beneficially introduced into the visbreaker are the overhead section and the distillation column, as well as the connecting pipes, condensers, heat exchangers, receiving tanks and other components attached thereto. Introducing ammonium hydroxide of formula (I) at these locations helps combat corrosion and salt attack.

[0071] Fluid catalytic cracking units (FCCs) use solid acid catalysts such as zeolites to crack high boiling residues, especially from crude oil distillates, into various low boiling fractions. FCCs generally include a first section, including a reactor and a regenerator, and a second section, which is mainly similar to a CDU unit. The preferred dosing points where one or more ammonium hydroxides of formula (I), preferably solutions thereof, can be beneficially introduced are mainly located in the second section of the FCC, such as the overhead section and the distillation column, which are fitted with connecting pipes, condensers, heat exchangers, receiving tanks and other components. Introducing ammonium hydroxide of formula (I) into these locations helps combat corrosion and salt damage.

[0072] In the delayed coker unit, the residue from the vacuum distillate is converted by thermal cracking into petroleum coke and lighter boiling fractions. The delayed coker unit is mainly composed of a feed / effluent heat exchanger, a furnace, a fractionation tower, and several coker drums. Preferred dosing points where one or more ammonium hydroxides of formula (I), preferably a solution thereof, can be beneficially introduced into the delayed coker unit are the overhead section and the distillation tower, as well as the connecting pipes, condensers, heat exchangers, receiving tanks and other components attached thereto. Introducing ammonium hydroxide of formula (I) into these locations helps combat corrosion and salt damage.

[0073] Reformers typically use catalytic processes to convert naphtha fractions from crude oil distillates, which contain relatively low boiling hydrocarbons with low octane numbers, into high octane reformates containing branched alkanes and aromatic hydrocarbons. Reformers generally include as major components a feed / outlet heat exchanger, a furnace, a series of reactors, a gas separator, a safety device, and a reflux drum. Preferred dosing points at which one or more ammonium hydroxides of formula (I), preferably solutions thereof, can be beneficially introduced into the reformer are the feed / outlet heat exchanger, the recycle gas line leaving the gas separator, the intermediate reforming pipeline between the gas separator and the safety device, the overhead section of the safety device, and the connected connecting pipes, condensers, heat exchangers, receiving tanks, and other components.

[0074] A hydrocracker uses a catalytic cracking process in the presence of hydrogen gas to produce primarily saturated hydrocarbons from high molecular weight petroleum distillate fractions. A hydrocracker typically includes as its main components usually two reactors, a furnace, a feed / outlet heat exchanger, and a distillation subunit similar in principle to a CDU unit. Preferred administration points at which one or more ammonium hydroxides of formula (I), or preferably a solution thereof, can be beneficially introduced into the hydrocracker unit are the feed / outlet heat exchanger, and the overhead section of the distillation column, as well as associated connecting pipes, condensers, heat exchangers, receiving tanks, and other components.

[0075] In the hydrodesulfurization unit (HDS), mineral oil products are desulfurized by catalytic hydrogenation. HDS generally includes as major components feed / effluent heat exchangers, furnaces, fixed bed reactors, gas separators, strippers, and reflux drums. Preferred administration points at which one or more ammonium hydroxides of formula (I), or preferably solutions thereof, can be beneficially introduced into the HDS are the overhead sections of the feed / effluent heat exchangers and strippers, as well as attached connecting pipes, condensers, heat exchangers, receiving tanks, and other components.

[0076] Alkanolamine and sulfinol units are gas cleaning plants in which acidic components such as CO2 and H2S are removed from useful gas streams such as natural gas and refinery fuel gas. Alkanolamine and sulfinol units are commonly called acid gas cleaning units. Such units mainly consist of an absorber tower, a "lean / rich" heat exchanger, a regenerator tower, a reflux drum, and connected piping. A solvent solution, usually containing an amine solution, circulates through the plant. Acid gases are absorbed into the solvent solution in the absorber tower at low temperature and high pressure, and then released into the regenerator tower at high temperature and low pressure. Heat exchange is performed between the loaded (rich) and unloaded (lean) solutions as the solvent passes back and forth between the columns. Purified gas is obtained at the top of the absorber tower, and acid gases are recovered at the top of the regenerator tower. Preferred administration points at which one or more ammonium hydroxides of formula (I), or preferably solutions thereof, may be beneficially introduced into the acid gas scrubbing unit are the rich / lean heat exchangers, the overhead section of the regenerator, the absorber, and the regenerator columns, and associated connecting piping, condensers, heat exchangers, receiving tanks, and other components.

[0077] According to another preferred embodiment of the method of the invention, the chemical process carried out in the device to which at least one ammonium hydroxide of formula (I) is added is a steam generation process. The device for carrying out such a process is any unit capable of generating steam, such as a general boiler, a heat recovery boiler of a petrochemical plant, also called a waste heat boiler, a dilution steam generator of an ethylene plant, a boiler of a steam turbine, a boiler of a pressurized water reactor, etc. There are many variations of boilers or steam generators, such as cylindrical boilers, water tube boilers, once-through boilers, cast iron boilers, and special boilers, such as indirect heating boilers, waste heat boilers, or special fuel boilers. In general, all the internal surfaces of the boiler that come into contact with steam or water are prone to corrosion, especially if acidic components are present in the water system of the boiler. Therefore, measures to reduce or prevent corrosion of the boiler are very important.

[0078] Corrosion in boilers and steam generators can be beneficially prevented by adding at least one quaternary ammonium hydroxide of formula (I), or preferably a solution thereof, to their water systems. The ammonium hydroxide of formula (I) neutralizes acids and other acidic compounds present in the water or aqueous solutions in the boiler, and can thus maintain a pH value high enough to completely or at least largely prevent corrosion. In general, the ammonium hydroxide (I) can be added or injected into any part of the boiler's interior, such as one of the boiler's three usual water systems: the feedwater system, the water system in the boiler, and the steam / condensate system in the boiler. However, it is generally preferred to add it to the feedwater system, since the neutralization is more extensive if at least one ammonium hydroxide (I) is added further upstream.

[0079] A further aspect of the present invention relates to the use of quaternary ammonium hydroxides of formula (I) as defined herein, particularly those as defined herein as preferred, to reduce or prevent corrosion or fouling caused by acidic compounds present in the chemical process in an apparatus for carrying out the chemical process. Such use of quaternary ammonium hydroxides of formula (I) in any of the methods of the present invention described herein is preferred.

[0080] The following examples serve to further illustrate the invention. EXAMPLES

[0081] Abbreviation ASNH 5-Azoniaspiro[4.4]-nonane hydroxide ATMAH Adamantyltrimethylammonium hydroxide BTMAH Benzyltrimethylammonium hydroxide Choline hydroxide N,N,N-trimethyl-N-(2-hydroxyethyl)ammonium hydroxide DEDMAH Diethyldimethylammonium hydroxide DMDPAH Dimethyldi-n-propylammonium hydroxide DMPH 1,1-Dimethylpyrrolidinium hydroxide DSC Dynamic Scanning Calorimetry ETMAH Ethyltrimethylammonium hydroxide HMH Hexamethonium hydroxide MEA Monoethanolamine (2-aminoethanol) nd Not measured TBAH Tetra-n-butylammonium hydroxide TEAH Tetraethylammonium hydroxide TEMAH Triethylmethylammonium hydroxide TGA thermogravimetric analysis TPAH Tetra-n-propyl ammonium hydroxide wt% weight%

[0082] Analytical Procedure: i. Ion Chromatography: Column Metrosep C4-250 / 4.0 - Silica-based weak cation exchange material. Diameter 5 μm. Substrate is polybutadiene maleate surface polymerized to provide carboxylic acid functional groups. Capacity >29 μEq / column Pre-column Metrosep C4 Guard Autosampler 863 Compact Autosampler Temperature 20~25℃ Detection Conductivity @ 40℃ Flow rate 0.9ml / min Eluent: 0.7mmol / l dipicolinic acid, 1.7mmol / l HNO3, 0.05mmol / l 18-crown-6, 1% acetone; balance: ultrapure water Injection volume 20μl Duration: 40 minutes Typical conductivity 635±5μS System pressure 12.5±0.5MPa ii.TGA: TGA was performed using a TGA instrument TAInstruments TGAQ5000. The measurement parameters were as follows: Heating rate: 10K / min Sample weight: 6-7mg Purge gas: 3l / h N2 Sample container: Aluminum crucible, open One heating: from room temperature to 600℃ iii.DSC DSC was carried out using a DSC instrument TAInstrumentspDSCQ20. The measurement parameters were as follows: Heating rate: 10K / min Cooling speed: manual Sample weight: 6-8mg Purge gas: 3l / h N2 Sample container: Aluminum crucible, open First heating step: from about -30°C to 200-400°C (depending on the sample) First cooling step: from 200℃-400℃ to about -30℃ Second heating step: from about -30℃ to 200-400℃ (depending on the sample)

[0083] Example 1: Storage stability of aqueous solutions of quaternary ammonium hydroxide of formula (I) The commercially available aqueous ammonium hydroxide solutions (I) shown in Table 1 were placed in small glass vials and stored at 5°C, 20°C, and 40°C, respectively, for two months and periodically visually inspected. A concentrated choline hydroxide solution was used as a reference. The results are shown in Table 1.

[0084] [Table 1]

[0085] As can be seen from Table 1, the solutions of choline hydroxide after storage at 40°C turned yellow over time. They also had a distinctive fishy odor. In contrast, the aqueous solutions of ammonium hydroxide (I) tested remained clear and colorless and did not emit a strong odor. Similar results were obtained with mixed solutions of these ammonium hydroxides (I).

[0086] Example 2: Thermal stability of quaternary ammonium hydroxides of formula (I) Several solutions of ammonium hydroxide (I) in deionized water at a concentration of 100 ppm (by weight) were prepared and charged into a stainless steel autoclave, which was subsequently purged with nitrogen and heated at a temperature of 220° C. for 4 hours and then cooled to room temperature. The solutions were analyzed before and after the heat treatment using ion chromatography according to the method described above. Choline hydroxide was used as a reference. The average results of two experiments are shown in Table 2. The stability percentages shown in Table 2 correspond to the measured residual amounts of ammonium hydroxide of formula (I).

[0087] [Table 2]

[0088] The thermal stability experiment described above was repeated for 1 hour at a temperature of 240° C. The average results of the duplicate experiments are shown in Table 3. The stability percentages shown in Table 3 correspond to the measured residual amount of ammonium hydroxide (I).

[0089] [Table 3]

[0090] From Tables 2 and 3 it is apparent that the thermal stability of dilute aqueous solutions of ammonium hydroxide (I) is significantly higher than that of the corresponding choline hydroxide solutions.

[0091] Example 3: pH value of aqueous solutions of quaternary ammonium hydroxide of formula (I) Ammonium hydroxide (I) was dissolved in deionized water at a concentration of 8.25 mmol / l, and the pH values ​​of these solutions were measured using a calibrated pH electrode. For comparison, the pH values ​​of the corresponding solutions of ammonia, MEA, and choline hydroxide were also measured. The results are shown in Table 4.

[0092] [Table 4]

[0093] The results summarized in Table 4 show that the tested solutions of ammonium hydroxide of formula (I) are much more alkaline (approximately 10-100 times) than the solutions of ammonia and MEA, and are comparable or more basic than choline hydroxide.

[0094] Example 4: Dissolution of ammonium chloride in a dilute aqueous solution of quaternary ammonium hydroxide of formula (I) Ammonium chloride (0.1 g) was placed on a watch glass and in each case a 1 wt% aqueous solution of ammonium hydroxide (I) was added dropwise using a plastic pipette until the ammonium chloride was completely dissolved. A 1 wt% solution of choline hydroxide was used as a reference. The results are summarized in Table 5 as the number of drops required to completely dissolve the salt.

[0095] [Table 5]

[0096] All solutions tested were able to dissolve ammonium chloride with the evolution of ammonia gas. However, significantly less ammonium hydroxide (I) solution was required for complete dissolution compared to the amount of choline hydroxide solution required for complete dissolution.

[0097] Example 5: Melting and decomposition points of chloride salts formed from quaternary ammonium hydroxides of formula (I) The melting and decomposition points of the chloride derived from ammonium hydroxide (I), and several equivalent chloride salts, were measured using DSC and TGA as described above. The results obtained are summarized in Table 6. As indicated, some values ​​were obtained from the literature.

[0098] [Table 6]

[0099] As is evident from Table 6, the chloride salts derived from quaternary ammonium hydroxides of formula (I), particularly those derived from TEAH, TPAH, TBAH, DEDMAH and TEMAH, have melting points that are significantly lower than those of ammonium chloride and choline chloride. It can also be seen that the chloride salts derived from ammonium hydroxides of formula (I) decompose only at elevated temperatures.

[0100] Example 6: Hygroscopicity of chloride salts formed from quaternary ammonium hydroxides of formula (I) Chloride salts derived from ammonium hydroxide (I) were prepared by carefully neutralizing a 5 wt% hydrochloric acid solution with an equimolar amount of ammonium hydroxide of formula (I) to a slightly acidic pH (pH 5.5-6.5), removing the water using a rotary evaporator (15 mbar absolute pressure, 80 °C), taking up the resulting crude salt in isopropanol and evaporating the solvent in a clean flask using a rotary evaporator. For high-precision analytical studies, such as pH value and corrosion studies, some salts were purified in several steps by using an isopropanol washing step.

[0101] The corresponding dried chloride salts of ammonium hydroxide (I) thus prepared were placed on watch glasses and kept open in ambient laboratory air at 50% relative humidity and observed for 24 hours. The solubility of the salts was evaluated. Ammonium chloride, MEA-Cl (monoethanolammonium chloride) and choline chloride were used as references.

[0102] The hygroscopicity of the salts was rated according to the following scale: 1 Very hygroscopic: dissolves in less than 10 minutes 2 Strong hygroscopicity: Dissolves in less than an hour 3 Moderately hygroscopic: dissolves in 1 to 6 hours 4 Slightly hygroscopic; dissolves in 6 to 24 hours 5 Non-hygroscopic: No visible change in 24 hours

[0103] The results are summarized in Table 7.

[0104] [Table 7]

[0105] The data summarized in Table 7 show that chloride salts derived from ammonium hydroxide (I) have a hygroscopicity ranging from weak to very strong. Thus, they absorb the surrounding moisture and are converted into a flowable solution in the presence of moisture. A further series of tests was carried out using salt mixtures consisting of TEA-Cl, a weakly hygroscopic salt, and either choline chloride, DEDMA-Cl, TEMA-Cl, or TPA-Cl, a very hygroscopic salt, in a weight ratio of 9:1. These mixtures showed a higher hygroscopicity compared to, for example, TEA-Cl alone.

[0106] Further experiments carried out using the chloride salt(II) in gasoline spiked with ppm amounts of water demonstrated the salt's ability to absorb water even from non-polar hydrocarbon fluids.

[0107] Example 7: pH Values ​​of Chloride Salt Solutions Derived from Quaternary Ammonium Hydroxides of Formula (I) The purified chloride salts derived from ammonium hydroxide (I) were dissolved in deionized water at a concentration of 10% by weight, and the pH values ​​of these solutions were measured using a calibrated pH electrode. Ammonium chloride, MEA-Cl and choline chloride were used as references. The results are shown in Table 8.

[0108] [Table 8]

[0109] The results summarized in Table 8 indicate that aqueous solutions of chloride salts derived from ammonium hydroxide (I) are not acidic and have near neutral pH values.

[0110] Example 8: Corrosivity of chloride salts derived from quaternary ammonium hydroxides of formula (I) Test tubes (volume: 15 ml) were filled with a 30 wt. % aqueous solution of purified chloride salt derived from ammonium hydroxide (I). To allow hydrogen gas to escape from the corrosion, a pre-weighed carbon steel coupon was placed in each semi-closed tube and immersed vertically in an oil bath at 70 °C for 24 h. The coupons were removed from the solution, the corrosion products were removed from the surface by careful treatment with 10 wt. % hydrochloric acid for 1 min, rinsed with deionized water, dried with acetone and weighed. The corrosion rate was then calculated from the weight loss of the coupons. The average results of two experiments are summarized in Table 9.

[0111] [Table 9]

[0112] From Table 9 it can be seen that the corrosivity of the chloride salts derived from quaternary ammonium hydroxide (I) is much lower than that of ammonium chloride and MEA-Cl, thus coinciding with the low corrosivity of choline chloride.

[0113] Example 9: Thermal stability of solutions of chloride salts derived from quaternary ammonium hydroxides of formula (I) The experiment described in Example 2 was repeated using a 100 ppm (by weight) aqueous solution of the chloride salt derived from quaternary ammonium hydroxide (I) at a temperature of 220° C. for 4 hours. Choline chloride was used as a reference. The results of the two experiments are shown in Table 10.

[0114] [Table 10]

[0115] From Table 10, it can be seen that the stability of chloride salts is generally higher than that of their hydroxide origin (compare the results listed in Table 2). Furthermore, it can be seen that the stability of chloride salts derived from dissolved ammonium hydroxide (I) is higher compared to the stability of choline chloride solutions. The low stability of choline chloride in aqueous solution is quite surprising in view of the high thermal stability of solid choline chloride (see Table 6).

[0116] Example 10: Thermal decomposition of chloride salts derived from quaternary ammonium hydroxides of formula (I) A small amount of pure chloride salt derived from quaternary ammonium hydroxide (I) was subjected to pyrolysis, and the resulting composition was then analyzed by gas chromatography coupled with mass spectrometry (pyrolysis GC / MS). The conditions were as follows: Pyrolysis temperature: 760℃, Pyrolysis time: 20 seconds; Column: CP-select624CB capillary column (Agilent Technologies), length: 30 m, film thickness: 1.8 μm, inner diameter: 320 μm; Detector: Mass-sensitive detector; Compound identification: By comparison with NIST 17 spectral database

[0117] The main decomposition products of the compounds are shown in Table 11.

[0118] [Table 11]

[0119] Table 11 shows that chloride salts derived from quaternary ammonium hydroxide (I) decompose into the corresponding organic chlorides and tertiary amines, and in particular, in all cases, practically no hydrogen chloride is formed.This is supported by what has been stated in N.Collie et al., J.Chem.Soc., Trans.1890,57,767-782; J.Blazejowski et al., Thermochim.Acta 1985,92,811-814; KM Armonet al., Inorg.Chem. 1981,20(11),4013-4015; K.M Armonet al., Journal of Molecular Structure 1989,213,193-200 and J. Blazejowski et al., Thermochim.Acta 1986,105,257-285.

[0120] As a representative example, the pyrolysis GC / MS partial chromatogram of DEDMA-Cl pyrolysis is shown in Figure 1. HCl, if present, appears at a very short retention time. No HCl was detectable in the pyrolysis of DEDMA-Cl.

[0121] Example 11: Ability of chloride salts derived from ammonium hydroxide (I) to retain hydrogen chloride The hydrogen chloride retention capacity of chloride salts derived from quaternary ammonium hydroxide (I) was tested similarly to the method described in US Pat. No. 8,177,962 (see Test Example 1). Specifically, an automatic distillation apparatus was used, as used for the automatic distillation of crude oil samples (compare ASTM D86, IP123 and ISO 3405). Each sample consisted of 95% by weight of heavy aromatic solvents with a boiling range of 180 to 210° C. and 5% by weight of an aqueous phase containing 9 mmol of chloride salts derived from TEAH, i.e. ammonium hydroxide (I). The chloride salts ammonium chloride, monoethanolammonium chloride and choline chloride were used as references. The samples were distilled to the dry point in the automatic distillation apparatus, while maintaining a constant distillation rate. The aqueous phase of the resulting distillate was separated from the supernatant organic phase and the chloride ion concentration therein was measured by titration with silver nitrate. The average results of three experiments are shown in Table 12.

[0122] [Table 12]

[0123] From Table 12, it can be seen that choline chloride and TEA-Cl release much less chloride ion than ammonium chloride and monoethanolammonium chloride, therefore the HCl retention capacity of TEA-Cl is at least as high as that of choline chloride.

Claims

1. 1. A method for reducing or preventing corrosion or fouling in an apparatus for carrying out a chemical process, the corrosion or fouling being caused by acidic compounds present in the chemical process, comprising adding at least one quaternary ammonium hydroxide of formula (I) to the apparatus in which the chemical process is carried out. 【Chemistry 1】 In the formula, R １ , R ２ , R ３ are each independently C １ -C １０ is an alkyl group, R ４ is C １ -C １８ and aryl, benzyl, monocycloalkyl having 5, 6, 7 or 8 carbon atoms, bicycloalkyl having 6 to 8 carbon atoms, tricycloalkyl having 7 to 10 carbon atoms, where monocycloalkyl, bicycloalkyl and tricycloalkyl are unsubstituted or substituted with one or two methyl groups and a cyclic alkyl group of the formula R ４ａ and R ４ｂ is substituted with the group 【Chemistry 2】 In the formula, A is C ２ -C ８ Alkanediyl, A' is C ２ -C ８ Alkanediyl, R １１ , R １２ , R １３ , R ２１ , R ２２ are each independently C １ -C ４ It is an alkyl. R １ and R ２ may together with the nitrogen atom form a 5- or 6-membered saturated nitrogen heterocycle which is unsubstituted or bears one or two methyl groups. R ３ and R ４ may together with the nitrogen atom form a 5- or 6-membered saturated nitrogen heterocycle which is unsubstituted or bears one or two methyl groups.

2. In formula (I), R １ , R ２ , R ３ are each independently C １ -C ６ Alkyl, R ４ is C ２ -C １８ is alkyl, R ３ and R ４ The method of claim 1 , wherein together with the nitrogen atom, may form a 5- or 6-membered saturated nitrogen heterocycle which is unsubstituted or has one or two methyl groups.

3. In formula (I), R １ , R ２ , R ３ are each independently C １ -C ６ Alkyl, R ４ is C ２ -C ６ The method of claim 2, wherein the alkyl group is an alkyl group.

4. 2. The method of claim 1, wherein the compound of formula (I) is selected from the group consisting of adamantyltrimethylammonium hydroxide, 5-azonia-spiro[4.4]nonane hydroxide, benzyltrimethylammonium hydroxide, diethyldimethylammonium hydroxide, ethyltrimethylammonium hydroxide, dimethyldipropylammonium hydroxide, triethylmethylammonium hydroxide, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetra-n-propylammonium hydroxide, tetra-n-butylammonium hydroxide, hexamethonium hydroxide and N,N-dimethylpyrrolidinium hydroxide.

5. 5. The method of claim 4, wherein the compound of formula (I) is selected from the group consisting of diethyldimethylammonium hydroxide, ethyltrimethylammonium hydroxide, dimethyldipropylammonium hydroxide, triethylmethylammonium hydroxide, tetraethylammonium hydroxide, tetra-n-propylammonium hydroxide and tetra-n-butylammonium hydroxide.

6. Acidic compounds present in chemical processes include hydrogen halides such as hydrogen chloride, hydrogen fluoride or hydrogen bromide, hydrogen sulfide, hydrogen cyanide, thiocyanic acid, sulfuric acid, SO ２ , S.O. ３ , nitrogen oxides, CO ２ 6. The method according to claim 1, wherein the acid is selected from the group consisting of carbonic acid, organic carboxylic acid, acidic phosphorus compounds and acidic ammonium salts and mixtures thereof.

7. 7. The method of claim 6, wherein the acidic compounds present in the chemical process comprise at least one acidic compound selected from the group consisting of ammonium halides, ammonium hydrogen sulfide, ammonium sulfide, ammonium hydrogen sulfate, ammonium sulfate, and acidic ammonium salts such as ammonium salts of carboxylic acids having from 1 to 10 carbon atoms, and acidic phosphorus compounds selected from phosphoric acid, acidic phosphates, polyphosphoric acids, and acidic polyphosphates.

8. 8. The method of any one of claims 1 to 7, wherein the chemical process is a crude oil refining process or a petrochemical process.

9. 9. The method according to claim 8, wherein the compound of formula (I) is added to at least one unit selected from a crude oil atmospheric distillation unit, a crude oil vacuum distillation unit, a visbreaker unit, a delayed coker unit, a fluid catalytic cracking unit, a reforming unit, a hydrocracking unit, an alkanolamine unit, a sulfinol unit and a hydrodesulfurization unit.

10. 8. The method of claim 1, wherein the chemical process is a steam generation process.

11. 11. The method of any one of claims 1 to 10, wherein the compound of formula (I) is added to a fluid or gas stream of a chemical process.

12. 12. The process according to claim 11, wherein during or after the addition of the compound of formula (I), the fluid or gas stream is exposed to a temperature of at least 100°C, often at least 150°C, in particular at least 180°C.

13. 13. The method according to claim 11 or 12, wherein the compound of formula (I) is added in an amount of from 1 to 1000 ppm by weight relative to the amount of the fluid or gas stream of the chemical process.

14. 14. The method according to any one of claims 1 to 13, wherein the compound of formula (I) is added to the chemical process as a solution of at least one compound of formula (I).

15. At least one compound of formula (I) is １ -C ４ 15. The method of claim 14, wherein the compound is dissolved in a solvent selected from an alkanol, water, and mixtures thereof.

16. 16. The method according to claim 14 or 15, wherein the total concentration of the compounds of formula (I) in the solution is in the range of 10 to 60% by weight.

17. 6. Use of a compound according to any one of claims 1 to 5 for reducing or preventing corrosion or fouling in equipment for carrying out chemical processes, the corrosion or fouling being caused by acidic compounds present in the chemical process.

18. Use according to claim 17, further characterized by at least one of the features of claims 6 to 16.

Images