Methods for reducing or preventing corrosion or contamination caused by acidic compounds

Abstract

To provide a method for reducing or preventing corrosion or fouling in equipment for carrying out chemical processes. [Solution] A method of adding at least one quaternary ammonium hydroxide of formula (I) to an apparatus in which a chemical process is carried out. TIFF2026143541000020.tif34140 In the formula, R 1 ~R 3 C1-C is independent 10 It is an alkyl group, R 4 In particular, C1~C 18 Selected from the group consisting of 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, the monocycloalkyl, bicycloalkyl and tricycloalkyl are unsubstituted or substituted with 1 or 2 methyl groups or tri-C1-C4 alkylammonium groups.

Description

[Technical Field]

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

[0002] Corrosion and fouling are serious problems in chemical manufacturing facilities, particularly crude oil processing plants such as crude oil refineries and petrochemical plants, as they lead to the deterioration of process equipment and result in economic losses and health and environmental hazards. The main causes of corrosion and fouling are ammonium salts, such as organic and inorganic ammonium halides, ammonium sulfate, or ammonium bisulfate. They are corrosive in gaseous, solid, or dissolved forms and can contribute to the accumulation of deposits that can cause hydrostatic or thermal damage 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 caused by acidic compounds, particularly hydrogen chloride, that are produced during the process. For example, in crude oil distillation units, hydrogen chloride can be formed through the hydrolysis of calcium chloride or magnesium chloride still present in the desalted crude oil supplied to the unit.

[0003] U.S. Patents 7,279,089 and 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 each process unit. Choline hydroxide is said to have advantageous properties compared to ammonia and other amines that have been commonly used in such applications. Firstly, choline hydroxide is much more basic, allowing for lower molar dosages and more effective pH control. Furthermore, due to its higher basicity, choline hydroxide reacts with acidic compounds to form salts in aqueous solutions with higher pH values. In this way, the risk of secondary corrosion caused by neutralized salts is significantly reduced. In addition, the neutralized salts of choline hydroxide are highly hygroscopic and can therefore easily absorb even trace amounts of moisture to form fluid solutions, and the salts can be easily removed from the process flow. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] U.S. Patent No. 7,279,089 [Patent Document 2] U.S. Patent No. 8,177,962 [Overview of the initiative] [Problems that the invention aims to solve]

[0005] However, using choline hydroxide to reduce fouling and corrosion also comes with several drawbacks. Firstly, aqueous solutions of choline hydroxide have limited thermal stability at temperatures above 180°C, and furthermore, they develop unpleasant odors and discoloration during long-term storage.

[0006] Despite advances in the field of corrosion and fouling prevention and control, there is still a need for effective and economically viable methods to combat corrosion and fouling in chemical processes, particularly those involving high temperatures. Therefore, the object of the present invention is to provide a method that avoids the limitations of the aforementioned prior art procedures, while possessing all the advantages of those procedures, particularly those using choline hydroxide to mitigate corrosion and fouling. Accordingly, the corrosion and fouling reduction or prevention compound used in this method, as well as its aqueous solution, must 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 flows in refineries and petrochemical systems, such as hydrodesulfurization plants. Furthermore, the compound should have improved basicity and superior ability to dissolve ammonium salts compared to choline hydroxide. [Means for solving the problem]

[0007] This objective 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, wherein corrosion or fouling is present during the chemical process. The present invention relates to a method of adding at least one of the quaternary ammonium hydroxides of formula (I), which is caused by an acidic compound, to an apparatus in which a chemical process is carried out. [ka] In the formula, R 1 , R 2 , R 3 Each is independently C1-C 10 It is an alkyl group, R 4 C1-C 18selected from the group consisting of 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. Here, monocycloalkyl, bicycloalkyl and tricycloalkyl are unsubstituted or substituted with 1 or 2 methyl groups, and a group of formula R 4a and R 4b .

Chemical Formula

[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 an apparatus for carrying out a chemical process, wherein the corrosion or fouling is caused by acidic compounds present during the chemical process. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] [Figure 1] FIG. 1 is a partial GC / MS chromatogram of the pyrolysis product of DEDMA-Cl formed under the conditions of Example 10. MODE FOR CARRYING OUT THE INVENTION

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

[0011] The term "C1-C" used herein 18 The term "-alkyl" refers to 1 to 4 ("C1-C4-alkyl"), 1 to 6 ("C1-C6-alkyl"), and 1 to 10 ("C1-C 10 -alkyl) or 1-18 ("C1-C 18 C1-C4-alkyl refers to saturated linear or branched hydrocarbon radicals having a carbon atom. C1-C4-alkyls include methyl, ethyl, n-propyl, isopropyl, n-butyl, 1-methyl-n-propyl (sec-butyl), 2-methyl-n-propyl (isobutyl), or 1,1-dimethylethyl (tert-butyl). C1-C6-alkyls further include, for example, n-pentyl, 1-methyl-n-butyl, 2-methyl-n-butyl, 3-methyl-n-butyl, 2,2-dimethyl-n-propyl, 1-ethyl-n-propyl, 1,1-dimethyl-n-propyl, 1,2-dimethyl-n-propyl, n-hexyl, 1-methyl-n-pentyl, 2-methyl-n-pentyl, 3-methyl-n-pentyl, 4-methyl-n-pentyl, and 1,1-dimethylethyl These are 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. C1-C 10 -Alkyl also includes, for example, n-heptyl, n-octyl, 2-ethyl-n-hexyl, n-nonyl, n-decyl and their positional isomers. C1-C 18-Alkyl also includes, for example, n-undecyl, n-dodecyl, n-tridecyl, n-tetradecyl, n-pentadecyl, n-hexadecyl, n-heptadecyl, n-octadecyl and their positional isomers.

[0012] As used herein, the term “monocycloalkyl having 5, 6, 7 or 8 carbon atoms” refers to monocyclic C5-C8 cycloalkyl radicals, namely cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl.

[0013] As used herein, the term “bicycloalkyl having 6 to 8 carbon atoms” refers to a crosslinked 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 crosslinked alicyclic C7-C alkyl group, each having 4 bridgehead carbons common to three rings. 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 This includes, but is not limited to, decanil.

[0015] As used herein, the term "C2-C8-alkanediyl" refers to a divalent saturated aliphatic hydrocarbon diradical having 2 to 8 carbon atoms. Examples of C2-C8-alkanediyl include 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, and 2-ethyl-1,6-n-hexanediyl.

[0016] As used herein, the term “5 or 6-membered saturated nitrogen heterocycle” refers to saturated monocyclic rings containing one nitrogen atom as a ring member, namely pyrrolidinyl and piperidinyl rings.

[0017] The term "crude oil processing plant" includes plants where crude oil is processed, such as crude oil refining plants, petrochemical plants, and plants that combine crude oil refining and petrochemical processes in a network. In equation (I), the variable element 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', either individually or in any combination, preferably have the following meanings:

[0018] Regardless of their occurrence, the variable element R 1 , R 2 and R 3 These are the same or different, preferably selected from C1-C6 alkyl groups, particularly from C1-C4 alkyl groups, i.e., selected 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 These are identical or different and are selected from the group consisting of methyl, ethyl, n-propyl, and n-butyl.

[0019] Alternatively, R 3 and R 4 The variable element R is as defined herein and preferably has the meaning indicated as preferred, but 1 and R 2 These may bond with a nitrogen atom to form a saturated nitrogen heterocycle, preferably having one methyl group, or preferably an unsubstituted 5 or 6-membered saturated nitrogen heterocycle.

[0020] Regardless of their occurrence, the variable element R 11 , R 12 , R 13 , R 21 and R 22 When present in quaternary ammonium hydroxide of formula (I), is the same or different, and is preferably selected from C1-C4 alkyl groups, 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, and particularly from the group consisting of methyl and ethyl. Particularly preferred R 11 , R 12 , R 13 , R 21 and R 22 If present, each of them is methyl.

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

[0022] The variable element A' is preferably a linear C2-C8-alkanediyl diradical, and more preferably a linear C2-C6-alkanediyl diradical.

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

[0024] Variable element R 4b The dihydroxy salts are selected from the group consisting of 2-(trimethylammonium)ethyl-(dimethylammonium)ethyl, 3-(trimethylammonium)-n-prop-1-yl-(dimethylammonium)-n-propyl, 4-(trimethylammonium)-n-buto-1-yl-(dimethylammonium)-n-butyl, 5-(trimethylammonium)-n-pento-1-(dimethylammonium)-n-pentyl, and 6-(trimethylammonium)-n-hexa-1-yl-(dimethylammonium)-n-hexyl.

[0025] Variable element R 4 Preferably, C1-C 10 - Selected from the group consisting of alkyl, benzyl, cyclopentyl, cyclohexyl bicycloalkyl having 7 or 8 carbon atoms, and tricycloalkyl having 9 or 10 carbon atoms, where monocycloalkyl, bicycloalkyl and tricycloalkyl are unsubstituted or have 1 or 2 methyl groups, and formula R 4a It is substituted with the base of R. Here, equation R 4a The variable element R 11 , R 12 , R 13 And A have the meanings defined herein, particularly preferred meanings. More preferably, R 4This 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 hydroxide salts of 6-(trimethylammonium)hexyl. 4 The hydroxides are selected from the group consisting of methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, benzyl, cyclopentyl, cyclohexyl, norbornyl, adamantyl, and 6-(trimethylammonium)hexyl, and are particularly selected from the group consisting of methyl, ethyl, n-propyl, n-butyl, benzyl, adamantyl, and 6-(trimethylammonium)hexyl.

[0026] Alternatively, variable element R 3 and R 4 These, together with the nitrogen atom to which they are bonded, may preferably form a saturated nitrogen heterocycle having one methyl group, or preferably an unsubstituted 5 or 6-membered saturated nitrogen heterocycle, which is R 1 and R 2 In this specification, "preferred" has the meaning given as "preferred".

[0027] In one preferred group of embodiments, the variable element R in the quaternary ammonium hydroxide of formula (I) 1 , R 2 , R 3 and R 4 It is defined as follows: R 1 , R 2 and R 3 They are the same or different and selected from C1-C6 alkyl groups, and in particular from C1-C4 alkyl groups, i.e., selected 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 -alkyl, benzyl, cyclopentyl, cyclohexyl, bicycloalkyl having 7 or 8 carbon atoms, tricycloalkyl having 9 or 10 carbon atoms, wherein monocycloalkyl, bicycloalkyl and tricycloalkyl are unsubstituted or substituted with 1 or 2 methyl groups and a group of formula R 4a . Here, the variable R in formula R 4a R 11 , R 12 , R 13 and A have the meanings defined herein, particularly the preferred meanings. 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 hydroxide salts of 6-(trimethylammonium)hexyl. R 4 is in particular selected from the group consisting of methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, benzyl, cyclopentyl, cyclohexyl, norbornyl, adamantyl, and hydroxide salts of 6-(trimethylammonium)hexyl, and is particularly selected from methyl, ethyl, n-propyl, n-butyl, benzyl, adamantyl, and hydroxide salts of 6-(trimethylammonium)hexyl.

[0028] In another preferred group of embodiments, the variables R in the quaternary ammonium hydroxide of formula (I) 1 , R 2 , R 3 and R 4 are defined as follows: R 1 and R 2 , together with the nitrogen atom to which they are bonded, form a 5- or 6-membered saturated nitrogen heterocycle which has one methyl group or is preferably unsubstituted. R 3 is selected from C1-C6-alkyl, in particular C1-C4-alkyl, that is the group consisting of 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 substituted by 1 or 2 methyl groups and a group of formula R 4a , and is selected from the group consisting of the above. Here, the variables R in formula R 4a R 11 , R 12 , R 13 and A have the meanings defined herein, in particular the preferred meanings. 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 salt of 6-(trimethylammonium)hexyl. R 4The hydroxides are selected from the group consisting of methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, benzyl, cyclopentyl, cyclohexyl, norbornyl, adamantyl, and 6-(trimethylammonium)hexyl, and are particularly selected from the group consisting of methyl, ethyl, n-propyl, n-butyl, benzyl, adamantyl, and 6-(trimethylammonium)hexyl.

[0029] In a more preferred group of embodiments, the variable element R in the quaternary ammonium hydroxide of formula (I) 1 , R 2 , R 3 and R 4 It is defined as follows: R 1 and R 2 Together with the nitrogen atoms to which they are bonded, they form a 5 or 6-membered saturated nitrogen heterocycle having one methyl group or, preferably, being unsubstituted. R 3 and R 4 Together with the nitrogen atoms to which they are bonded, they form a 5 or 6-membered saturated nitrogen heterocycle having one methyl group or, preferably, being unsubstituted.

[0030] In a particular preferred group of embodiments, R 1 , R 2 , R 3 Each of these is independently a C1-C6 alkyl, preferably independently a C1-C4 alkyl, and is particularly 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 -A hydroxide salt of tricycloalkyl or 6-(trimethylammonium)hexyl, preferably C2-C 10 -It is an alkyl, benzyl, norbornyl, adamantyl, or 6-(trimethylammonium)hexyl hydroxide.

[0031] In a more specific preferred group of embodiments, R 1 and R 2 It bonds with a nitrogen atom to form a 5 or 6-membered saturated nitrogen heterocycle having an unsubstituted or one or two methyl groups, preferably an unsubstituted 5 or 6-membered saturated nitrogen heterocycle, in particular an unsubstituted pyrrolidinium ring; R 3 is a C1-C6 alkyl group, preferably independently a C1-C4 alkyl group, and particularly independently selected from methyl, ethyl, n-propyl, and n-butyl; and, R 4 C1-C 18 -Alkyl, benzyl, cyclopentyl, cyclohexyl, C7-C8-bicycloalkyl, C9-C 10 -A hydroxide salt of tricycloalkyl or 6-(trimethylammonium)hexyl, preferably C2-C 10 -It is an alkyl, benzyl, norbornyl, adamantyl, or 6-(trimethylammonium)hexyl hydroxide.

[0032] Furthermore, in a particular group of preferred embodiments, R 1 and R 2 Together with the nitrogen atoms to which they are bonded, they form a 5 or 6-membered saturated nitrogen heterocycle having unsubstituted or 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 These bond to the nitrogen atom to which they are attached, forming a 5- or 6-membered saturated nitrogen heterocycle having an unsubstituted or 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 include 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-butyltrimethylammonium hydroxide, n-butyl Selected from the group consisting of triethylammonium hydroxide, tetraethylammonium hydroxide, tetra-n-propylammonium hydroxide, tetra-n-butylammonium hydroxide, hexamethonium hydroxide, and N,N-dimethylpyrrolidinium hydroxide; 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, the following are selected: 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 more preferred group of embodiments, the variable element R in the quaternary ammonium hydroxide of formula (I) 1 , R 2 , R 3 and R 4 It is defined as follows: R 1 , R 2 , R 3 Each of these is independently a C1-C6 alkyl group, preferably independently a C1-C4 alkyl group, and particularly independently selected from methyl, ethyl, n-propyl, and n-butyl groups; R 4 C1-C 18 -Alkyl, preferably C2-C 18 - Alkyl, particularly C2-C4-alkyl, specifically selected from ethyl, n-propyl, and n-butyl; Or instead: R 3 and R 4 These bond to the nitrogen atom to which they are attached, forming a 5- or 6-membered saturated nitrogen heterocycle having an unsubstituted or 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 the 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 element R in the quaternary ammonium hydroxide of formula (I) 1 , R 2 , R 3 and R 4 It is defined as follows: R 1 , R 2 , R 3 Each of these is independently a C1-C6 alkyl group, preferably independently a C1-C4 alkyl group, and is particularly independently selected from methyl, ethyl, n-propyl, and n-butyl; and, R 4 The alkyl group is C2-C6 alkyl, particularly C2-C4 alkyl, and 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 include 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 Selected from the group consisting of ammonium hydroxides and tetra-n-butylammonium hydroxides; in particular, 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), and in particular, selected from the group consisting of DEDMAH, TEMAH, TEAH, TPAH, and TBAH.

[0038] In particular, at least one quaternary ammonium hydroxide of formula (I) is selected from DEDMAH, TEMAH, TEAH, TPAH, and TBAH, as well as mixtures thereof, of which TEAH and one or more quaternary ammonium hydroxides of formula (I), mixtures of TEAH with one or more of DEDMAH, TEMAH, TPAH, and TBAH are preferred.

[0039] This invention provides a method for reducing or preventing corrosion or fouling in apparatus for performing chemical processes. Here, corrosion refers to the corrosive modification of metal parts that are part of the apparatus, and fouling refers to the accumulation and deposition of unwanted substances on the inner surfaces of the apparatus. 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 situations: - Acidic compounds are processed in chemical processes. Therefore, they are already present in the raw materials introduced into the apparatus for carrying out the chemical process, and / or - Acidic compounds are generated only during the process.

[0041] To achieve reduction or prevention of corrosion or fouling, this 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 preferred, to the apparatus in which the chemical process is carried out.

[0042] Typically, a mixture of one or more ammonium hydroxides of formula (I) is added. When such a mixture is used, a mixture comprising two or more ammonium hydroxides, particularly two or three, selected from the ammonium hydroxides referred to herein as preferred, especially TEAH, TPAH, TBAH, TEMAH, and DEDMAH, is preferred, with particular preference given to mixtures consisting of TEAH and DEDMAH, TEAH and TEMAH, or TEAH, DEDMAH, and TEMAH. However, other mixtures of ammonium hydroxide of formula (I) may also be used in the methods of the present invention to adjust the properties of the salt obtained after the reaction of an acidic compound present in the apparatus being processed with ammonium hydroxide of formula (I), as discussed herein below.

[0043] In a group of embodiments of the present invention, at least one ammonium hydroxide(I) is introduced into the fluid or gas flow of a chemical process carried out in the apparatus. Here, the ammonium hydroxide of formula (I) is added either on its own or, preferably, in solution. The addition can be achieved by metering one or more ammonium hydroxides of formula (I) into the raw materials entering the apparatus, or by inserting them at specific locations in apparatus, which are often located upstream of a section or unit of the apparatus, and which are already affected by or may be affected by corrosion or fouling.

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

[0045] Examples of acidic compounds that can 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, particularly hydrogen chloride, hydrogen sulfide, hydrogen cyanide, thiocyanic acid, sulfuric acid, SO2, SO3, nitrogen oxides, particularly NO and NO2, carbonic acid, CO2, organic acids, particularly carboxylic acids and sulfonic acids, acidic ammonium salts, acidic phosphorus compounds, and mixtures thereof. Protonic acids, derived from the aforementioned protic acids and oxides, are known to primarily promote corrosion processes but can also contribute to fouling in chemical plants, 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 and petrochemical processes, particularly crude oil refining. Acidic phosphorus compounds may also be present in crude oil grades such as shale oil. On the one hand, carbonic acid and CO2, along with organic acids, are the main corrosive substances in steam generating equipment such as boiler systems used in chemical processes. On the other hand, nitrogen oxides formed in combustion processes, for example, mainly cause corrosion problems on the flue gas side of combustion equipment such as diesel engines.

[0046] The methods of the present invention are 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. Acidic ammonium compounds and acidic phosphorus compounds may be either inorganic or organic compounds. Examples of acidic ammonium salts include, but are not limited to, inorganic and organic ammonium halides such as ammonium chloride and N-substituted ammonium chloride, ammonium fluoride or ammonium bromide, especially ammonium chloride, organic ammonium chloride, di- and tri-C1-C4-alkylammonium chlorides such as trimethylammonium chloride or triethylammonium chloride, alkylenediamine hydrochlorides such as ethylenediamine monohydrochloride, alkanolamine hydrochlorides such as dimethylethanolammonium chloride, and alkoxyalkylamine hydrochlorides such as 3-methoxylpropylammonium chloride, ammonium hydrogen sulfide, ammonium sulfide, ammonium bisulfate, 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, polyphosphate, acidic phosphates and acidic polyphosphates, phosphonic acids and acidic phosphonates. Polyphosphates and acidic polyphosphates have at least two, for example, an average of 2 to 1000, phosphorus atoms and can 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 acidic salts of polyphosphate, particularly acidic polyphosphates of alkali metals or alkaline earth metals.

[0047] Acidic compounds particularly relevant as causing corrosion or fouling include hydrogen chloride, hydrogen fluoride, sulfur trioxide, nitrogen oxides, ammonium chloride, trimethylammonium chloride, triethylammonium chloride, ethylenediamine monohydrochloride, dimethylethanolammonium chloride, and 3-methoxylpropylammonium chloride, as well as organic ammonium chlorides, ammonium sulfide, ammonium hydrogen sulfide, ammonium sulfate, and ammonium bisulfate, especially hydrogen chloride, ammonium chloride, and organic ammonium chlorides. The methods of the present invention are particularly suitable for combating the corrosive and fouling effects of these compounds in apparatus for carrying out chemical processes.

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

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

[0050] Therefore, unlike the corresponding solutions of choline hydroxide, they are characterized by high resistance to discoloration and odor development. In fact, a solution of ammonium hydroxide of formula (I) remains clear and colorless and has only a very faint odor after long-term storage at 40°C, while a solution of choline hydroxide turns yellow and emits a very strong fishy odor. Thus, aqueous solutions of ammonium hydroxide of formula (I) have higher storage stability than their respective choline hydroxide solutions and are particularly suitable for long-term storage even under unfavorable storage conditions.

[0051] A particular advantage related to the present invention is the fact that ammonium hydroxide of formula (I) and its aqueous solutions have good stability at temperatures far above 200°C, i.e., the decomposition rate of ammonium hydroxide of formula (I) is low under these conditions. Therefore, ammonium hydroxide of formula (I), especially its aqueous solutions, can be safely introduced into process streams having temperatures up to 250°C, because ammonium hydroxide of formula (I) remains 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 hydroxide of formula (I), because they can be injected into high-temperature locations, such as feed / outlet heat exchangers in hydrodesulfurization plants, without significantly losing their effectiveness against corrosion and fouling. This is difficult or impossible with choline hydroxide and its solutions, which already decompose very strongly at temperatures above 200°C.

[0052] Furthermore, due to their high stability, ammonium hydroxide of formula (I) and its aqueous solutions can be introduced into process streams further upstream than conventional corrosion and antifouling agents, and thus can enter hard-to-reach locations within equipment that were previously largely inaccessible, such as process plants.

[0053] Furthermore, ammonium hydroxide of formula (I) is a much stronger base than ammonia and any organic amine. Its basic strength is, in fact, equivalent to or greater than that of choline hydroxide. This property allows for the achievement of high anticorrosive and antifouling activity at lower molar doses compared to conventional methods. Due to this very strong basicity, ammonium hydroxide of formula (I) also readily reacts with protic acids such as hydrogen chloride, hydrogen sulfide, and organic acids to form 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] Here, the variable element R 1 , R 2 , R 3 and R 4 This has the same meaning, and especially the same preferred meaning, as defined in relation to formula (I).

[0054] Ammonium hydroxide of formula (I) also readily reacts with acidic ammonium salts, particularly ammonium chloride, and organic ammonium salts, to liberate ammonia or their respective amines, forming quaternary ammonium salts, particularly chloride of formula (II). Thus, the inventors of this application have found that ammonium chloride dissolves far more actively in a diluted solution of ammonium hydroxide of formula (I) than in those of choline hydroxide. In conclusion, ammonium hydroxide of formula (I) is very suitable for neutralizing protonic acids that induce corrosion, as well as for dissolving acidic ammonium salts in fouled systems and preventing the deposition of such fouling salts.

[0055] The suitability of ammonium hydroxide 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 selected from protic acids and acidic ammonium salts. Here, the melting and decomposition points of these salts derived from ammonium hydroxide of formula (I) are of particular interest because they strongly influence the outcome of the salts located at specific locations in the plant treated with ammonium hydroxide (I) according to the methods of the present 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, chlorides derived from ammonium hydroxide of formula (I), i.e., salts of formula (II), often have melting points below 80°C and decomposition points above 200°C, and even above 250°C. Thus, their melting points are often much lower than those of choline chloride, and their decomposition points are above temperatures common in most units of a chemical plant. For these reasons, the use of ammonium hydroxide of formula (I) is advantageous because, for example, the salts formed by their reaction with acidic compounds are already fluid at low temperatures and can therefore be easily transported and removed from plant units treated with ammonium hydroxide of formula (I). Furthermore, due to their very high decomposition points, the formed salts withstand high process temperatures without undergoing decomposition and are easily removed from the process unit in the form of aqueous solutions. Indeed, due to the excellent water solubility of the salts, even very small amounts of liquid water or vapor present in the treated process stream are sufficient to facilitate their removal.

[0056] From the above, it is clear that not only the ammonium hydroxide of formula (I) used in the processing by the method of the present invention, but also the salts converted by their reaction with acidic compounds present in the chemical process, have very high decomposition points. Therefore, the process stream in the apparatus in which the process is carried out can be heated to high temperatures without the risk of decomposition of the ammonium hydroxide of formula (I) or the salts formed therefrom. Thus, the flow of fluid or gas in the chemical process can be exposed to temperatures of at least 100°C, often at least 150°C, particularly at least 180°C, and especially at least 200°C or at least 250°C during or after the addition of ammonium hydroxide (I) to the flow.

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

[0058] Furthermore, as experiments by the inventors of this application have shown, even the addition of a small amount of the strongly hygroscopic chloride salt of formula (II) can significantly increase the hygroscopicity of the weakly hygroscopic chloride salt (II). This also applies to salts derived from ammonium hydroxide of formula (I) other than chlorides. Thus, by mixing two or more different ammonium hydroxides of formula (I) in specific, easily identifiable ratios, it is possible to form a salt mixture after treatment, whose hygroscopicity can be adjusted and fine-tuned to the specific requirements of "wet" or "dry" systems, i.e., systems with relatively high or low moisture content. An example of a wet system is the overhead section of a distillation column that uses stripping vapor, such as an atmospheric distillation column. An example of a dry system is the feed / outlet heat exchanger of a gasoline hydrodesulfurization unit. Thus, a group of embodiments of the present invention relates to the method of the present invention using a mixture of ammonium hydroxide (I) preferably in specific ratios with respect to each other. In this context, the mixture is preferred, and as a result, a mixture of salt (II) having specific desired physicochemical properties, e.g., optimized hygroscopicity, is formed.

[0059] The salts of formula (II), and salts derived from ammonium hydroxide (I) other than chloride (II), i.e., compounds of formula (IIa), have a near-neutral pH when dissolved in water and are far less corrosive than ammonium chloride and chloride salts formed from amines such as monoethanolamine (MEA), which are conventionally used to neutralize acidic compounds that cause corrosion. [ka] Here, X - These are non-basic and non-acidic counterions such as bromides, sulfates, or nitrates. Therefore, due to their extremely low corrosiveness, salts derived from ammonium hydroxide (I), particularly salts of formulas (II) and (IIa), which are formed within the chemical process unit when treated with ammonium hydroxide of formula (I) according to the method of the present invention, hardly adversely affect the metal surfaces within the unit. Thus, even if these salts remain in the process unit for a long period of time, they do not cause significant corrosion damage, and as mentioned above, they are usually already removed by the trace amounts of water or steam present in the process stream. In conclusion, using ammonium hydroxide of formula (I) as a corrosion and fouling agent has the added advantage of greatly reducing secondary corrosion often caused by salts resulting from the reaction of conventional agents with acidic compounds.

[0060] As outlined above, the salts produced by converting ammonium hydroxide of formula (I) with acidic compounds, particularly the salt of formula (II), not only have very high decomposition points but can also be easily removed from the chemical process stream. However, rarely, if such salts are exposed to temperatures above their decomposition point, they decompose into non-hazardous compounds. Thus, the inventors of this application were able to demonstrate that in all cases, the thermal decomposition of different salts of formula (II) yields the corresponding alkyl chlorides and trialkylamines as the main decomposition products. For example, tetraethylammonium chloride (TEA-Cl) decomposes mainly into ethyl chloride and triethylamine, and diethyldimethylammonium chloride (DEDMA-Cl) decomposes into methyl chloride, ethyl chloride, diethylmethylamine, and ethyldimethylamine. The formed alkyl chlorides are removed from the process via a gas stream, e.g., separators, columns, or heat exchangers, and therefore do not adversely affect the process or the apparatus on which the process is performed. On the other hand, the formed trialkylamine can function as a further base to neutralize the corrosive acidic compound and is then removed from the system as an ammonium salt. It is important to note that substantially no corrosive hydrogen chloride is formed during the thermal decomposition of the salt of formula (II). According to this thermal decomposition pathway of salt (II), chlorides derived 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 embodiment 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 solutions are preferably prepared by dissolving at least one ammonium hydroxide (I) in a solvent selected from water, methanol, ethanol, C1-C4 alkanols such as 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, as well as mixtures thereof such as 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, and particularly in the range of 10 to 40% by weight.

[0062] A solution of at least one ammonium hydroxide of formula (I) used to reduce or prevent corrosion or fouling by the method of the present invention optionally further comprises a dispersant, e.g., polyisobutylene succinimide; an antioxidant / depolymerizing agent, e.g., tert-butylphenol derivatives, phenylenediamine, N-oxyl compounds such as 2,2,6,6-tetramethyl-piperidine-N-oxyl (TEMPO), and a derivative of TEMPO such as 4-hydroxy-2,2,6,6-tetramethyl-piperidine-N-oxyl (4-OH-TEMPO); and an antifoaming agent, e.g., one or more additives selected from copolymers of ethylene oxide and propylene oxide, polypropylene glycol, or silicone oil. The solution may optionally further comprise additional active substances, e.g., further anticorrosive and antifouling agents such as choline hydroxide, and neutralizing amines such as alkylamines or alkanolamines.

[0063] Furthermore, solutions of at least one ammonium hydroxide of formula (I) may optionally contain active substances that have distinctly different functions but are not related to the control of corrosion or fouling. An example of such an active substance is 4-tert-butylcatechol (TBC), which is a polymerization inhibitor and therefore suitable as a monomer stabilizer. Solutions according to the present invention comprising TBC and at least one ammonium hydroxide of formula (I) are useful for antifouling applications in process plants or units containing monomers, such as process water systems in ethylene plants. The combination of quaternary ammonium hydroxide of formula (I) and TBC has the remarkable additional advantage that, due to their strong basicity, quaternary ammonium hydroxide of formula (I) promotes the dissolution of TBC in weakly acidic water. Therefore, other potentially harmful aids 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 a chemical process at one or more locations in the apparatus in which the chemical process is performed, for example, in different units of a process plant. Preferably, ammonium hydroxide (I) is introduced into the process by injecting its solution at one or more locations or into one or more units of the apparatus or process plant. Injection is usually performed by a continuous injection method such as metered injection or flow-proportional injection, or by an intermittent injection method such as suction injection or forced injection.

[0065] At least one ammonium hydroxide of formula (I) is introduced into the chemical process fluid stream, typically in amounts ranging from 1 to 5000 ppm, particularly from 1 to 2500 ppm, more preferably from 1 to 1000 ppm, and particularly from 1 to 500 ppm, based on the amount of the chemical process fluid or flow at each location where the addition is made. It is particularly preferable to adjust the amount of ammonium hydroxide of formula (I) added to the amount of corrosive species and / or contaminants in the fluid stream being treated, particularly 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 to neutralize corrosive acids, such as hydrogen chloride, present in the stream, or to dissolve ammonium chloride-containing deposits within the process unit. For example, it may be useful to measure the pH value or chloride concentration of a suitable portion of the process unit and determine the amount of ammonium hydroxide of formula (I) to be added based on the measurement. Alternatively, in other cases, it may be sufficient to add a fixed amount of ammonium hydroxide of formula (I) to an established process, which empirically has shown to be appropriate. In both of the above examples, the addition of ammonium hydroxide of formula (I) is preferably achieved by continuously or intermittently injecting 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, particularly a crude oil refining process and / or a petrochemical process, such as a crude oil refining process and / or a petrochemical process. In this regard, the crude oil refining process typically includes one or more processing units selected from crude oil atmospheric distillation units, crude oil vacuum distillation units, bisbreaker units, delayed coker units, fluid catalytic cracking units, reformers, hydrocracking units, alkanolamine units, sulfinol units, and hydrodesulfurization units.

[0067] A crude oil distillation unit (CDU), also known as a crude oil atmospheric pressure distillation unit, is generally the first processing unit in any oil refinery. In a CDU, the introduced crude oil is distilled into various fractions with different boiling point ranges, each of which may be further processed in other refinery processing units. Distillation in a CDU is typically carried out at a pressure slightly above atmospheric pressure. A CDU typically consists, as its main components, a heat exchanger, a desalination unit, a furnace, a distillation column mounted in series, and side strippers and reflux drums. A 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 desalination unit. The introduction of ammonium hydroxide of formula (I) at this location serves as a partial or complete substitution of sodium hydroxide, which is commonly used to remove calcium chloride and magnesium chloride from crude oil exiting the desalination unit by converting them to their corresponding hydroxides. If calcium chloride and magnesium chloride remain in the crude oil, they undergo hydrolysis in the furnace, producing hydrogen chloride gas that dissolves in condensate water, thus leading to corrosion in the overhead section of the distillation column. However, the use of sodium hydroxide has drawbacks, one of which is that the sodium salt can contaminate catalysts used in subsequent treatment devices such as hydrodesulfurization or catalytic cracking units. In particular, since ammonium hydroxide of formula (I) is also a strong base but does not contain sodium, these drawbacks can be avoided or mitigated by completely or partially replacing sodium hydroxide with ammonium hydroxide of formula (I).

[0068] More preferable administration points where one or more ammonium hydroxides (I), preferably solutions thereof, can 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 to counteract corrosion and salt damage.

[0069] In a crude oil vacuum distillation unit (VDU), the high-boiling bottom fraction from atmospheric distillation is generally separated by vacuum distillation. The main component of the VDU is the distillation column. Preferred dosing 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 hydroxides of formula (I) at these locations helps to counteract corrosion and salt damage.

[0070] In a bisbreaker unit, also called a bisbreaker, the residue from vacuum distillation is thermally decomposed into higher-value, lighter-boiling components. The main components of a bisbreaker are feed / outlet heat exchangers, furnaces, retention vessels (soakers), and distillation columns or a series of distillation columns. Preferred dosing points where one or more ammonium hydroxide of formula (I), preferably a solution thereof, can be beneficially introduced into a bisbreaker are the overhead sections and distillation columns, as well as the connecting pipes, condensers, heat exchangers, receiving tanks, and other components attached to them. Introducing ammonium hydroxide of formula (I) at these locations helps to counteract corrosion and salt damage.

[0071] Fluid catalytic cracking (FCC) units use solid acidic catalysts, such as zeolites, to crack high-boiling residues, particularly from crude oil distillates, into various low-boiling fractions. An FCC generally comprises a first section, including reactors and regenerators, and a second section, primarily similar to a CDU unit. Preferred docking 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 distillation columns, to which connecting pipes, condensers, heat exchangers, receiving tanks, and other components are attached. Introducing ammonium hydroxides of formula (I) at these locations helps to counteract corrosion and salt damage.

[0072] In a delayed coker unit, residues from vacuum distillates are converted into petroleum coke and lighter boiling distillates by thermal decomposition. A delayed coker unit mainly consists of feed / outlet heat exchangers, furnaces, fractionation columns, and several coker rams. Preferred dosing points where one or more ammonium hydroxide of formula (I), preferably a solution thereof, can be beneficially introduced into a delayed coker unit are the overhead sections and distillation columns, as well as the connecting pipes, condensers, heat exchangers, receiving tanks, and other components attached to them. Introducing ammonium hydroxide of formula (I) at these locations helps to counteract corrosion and salt damage.

[0073] Reforming units typically use catalytic processes to convert naphtha fractions from crude oil distillates containing relatively low-boiling-point hydrocarbons with low octane numbers into high-octane reformers containing branched alkanes and aromatic hydrocarbons. Reforming units generally include feed / outlet heat exchangers, furnaces, a series of reactors, gas separators, safety devices, and reflux drums as their main components. Preferred dosing points where one or more ammonium hydroxides of formula (I), preferably a solution thereof, can be beneficially introduced into the reformer are the feed / outlet heat exchangers, 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 connected connecting pipes, condensers, heat exchangers, receiving tanks, and other components.

[0074] Hydrocrackers use a catalytic cracking process in the presence of hydrogen gas to produce mainly saturated hydrocarbons from high molecular weight petroleum distillation fractions. Hydrocrackers typically include, as their main components, two reactors, a furnace, a feed / outlet heat exchanger, and a distillation subunit that is in principle similar to a CDU unit. Preferred dosing points where 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, the overhead section of the distillation column, as well as the attached connecting pipes, condensers, heat exchangers, receiving tanks, and other components.

[0075] In a hydrodesulfurization system (HDS), mineral oil products are desulfurized by catalytic hydrogenation. An HDS generally includes, as its main components, feed / outlet heat exchangers, a furnace, a fixed-bed reactor, a gas separator, a stripper, and a reflux drum. Preferred dosing points where one or more ammonium hydroxides of formula (I), or preferably a solution thereof, can be beneficially introduced into the HDS are the overhead sections of the feed / outlet heat exchangers and stripper, as well as attached connecting pipes, condensers, heat exchangers, receiving tanks, and other components.

[0076] Alkanolamine and sulfinol plants are gas scrubbing plants that remove acidic components such as CO2 and H2S from useful gas streams, such as natural gas and refinery fuel gas. Alkanolamine and sulfinol plants are commonly referred to as acid gas scrubbing units. Such plants mainly consist of absorption columns, lean / rich heat exchangers, regeneration columns, reflux drums, and connected piping. Typically, a solvent solution containing an amine solution circulates within the plant. Acidic gases are absorbed into the solvent solution in the absorption column at low temperature and high pressure, and then released into the regeneration column at high temperature and low pressure. Heat exchange takes place between the loaded (rich) and unloaded (lean) solutions as the solvent moves between the columns. The purified gas is obtained at the top of the absorption column, and the acidic gases are recovered at the top of the regeneration column. Preferred dosing points where one or more ammonium hydroxides of formula (I), or preferably a solution thereof, can be beneficially introduced into the acidic gas cleaning unit are rich / lean heat exchangers, the overhead section of the regenerator, the absorber, and the regenerator column, and associated connecting pipes, condensers, heat exchangers, receiving tanks, and other components.

[0077] According to another preferred embodiment of the method of the present invention, a chemical process carried out in an apparatus to which at least one ammonium hydroxide of formula (I) is added is a steam generation process. Apparatus for carrying out such a process is any unit capable of generating steam, such as a general boiler, a waste heat recovery boiler in a petrochemical plant also called a waste heat boiler, a dilution steam generator in an ethylene plant, a steam turbine boiler, a pressurized water reactor boiler, and other waste heat recovery boilers. Boilers or steam generators come in various variations, 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 internal surfaces of a boiler that come into contact with steam or water are susceptible to corrosion, especially if acidic components are present in the boiler's aqueous system. Therefore, measures to reduce or prevent boiler corrosion are of great importance.

[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 aqueous systems. Ammonium hydroxide of formula (I) neutralizes acids and other acidic compounds present in the water or aqueous solution within the boiler, and thus can maintain a pH value high enough to completely or at least largely prevent corrosion. Generally, ammonium hydroxide (I) can be added to or injected into any part of the boiler's interior, such as one of the three usual water systems, i.e., the feedwater system, the boiler water system, and the boiler steam / condensate system. However, it is generally preferred to add at least one ammonium hydroxide (I) to the feedwater system, as the neutralization is more widespread if it is added further upstream.

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

[0080] The following embodiments serve as further examples of the present invention. [Examples]

[0081] Abbreviation ASNH 5-azoniaspiro[4.4]-nonanehydroxy 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-propylammonium hydroxide wt% weight%

[0082] Analysis procedure: i. Ion chromatography: Metrosep C4-250 / 4.0-silica-based weak cation exchange column. Diameter 5 μm. Substrate is surface-polymerized polybutadiene maleic acid to provide carboxylic acid functional groups. Volume 29 μEq / column or higher. Pre-column Metrosep C4 Guard Autosampler 863 Compact Autosampler Temperature 20~25℃ Detected conductivity @ 40℃ Flow rate 0.9ml / min Eluent: 0.7 mmol / l dipicolinic acid, 1.7 mmol / l HNO3, 0.05 mmol / l 18-crown-6, 1% acetone; Balance: ultrapure water Injection volume 20μl Duration: 40 minutes Typical conductivity: 635±5μS System pressure: 12.5 ± 0.5 MPa ii.TGA: TGA was performed using the TAInstrumentsTGAQ5000 TGA instrument. The measurement parameters were as follows: Heating rate: 10K / min Sample weight: 6-7 mg Purge gas: 3 l / h N2 Sample container: Aluminum crucible, open Single heating cycle: From room temperature to 600°C iii. DSC DSC was performed using the TAInstrumentspDSCQ20 DSC instrument. The measurement parameters were as follows: Heating rate: 10K / min Cooling speed: manual Sample weight: 6-8 mg Purge gas: 3 l / h N2 Sample container: Aluminum crucible, open Initial heating step: Approximately -30°C to 200-400°C (varies depending on the sample) First cooling step: From 200°C-400°C to approximately -30°C Second heating step: Approximately -30°C to 200-400°C (varies depending on the sample)

[0083] Example 1: Storage stability of aqueous solution of quaternary ammonium hydroxide of formula (I) The commercially available ammonium hydroxide aqueous solutions (I) shown in Table 1 were placed in small glass vials and stored at 5°C, 20°C, and 40°C for two months, with periodic visual inspections. 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 choline hydroxide solution, after being stored at 40°C, turned yellow over time. It also emitted a distinctive fishy odor. In contrast, the tested aqueous solutions of ammonium(I) hydroxide remained clear and colorless and did not produce a strong odor. Similar results were obtained with mixed solutions of these ammonium(I) hydroxides.

[0086] Example 2: Thermal stability of quaternary ammonium hydroxide of formula (I) Solutions of several ammonium hydroxides (I) in deionized water at a concentration of 100 ppm (by weight) were prepared, packed into a stainless steel autoclave, purged with nitrogen, heated at 220°C for 4 hours, and then cooled to room temperature. The solutions were analyzed before and after heat treatment using ion chromatography by 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 amount of ammonium hydroxide of formula (I).

[0087] [Table 2]

[0088] The above experiments on thermal stability were repeated at a temperature of 240°C for 1 hour. The average results of the two 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] Tables 2 and 3 clearly show that the thermal stability of a diluted aqueous solution of ammonium(I) hydroxide is significantly higher than that of the corresponding choline hydroxide solution.

[0091] Example 3: pH value of aqueous solution of quaternary ammonium hydroxide of formula (I) Ammonium(I) hydroxide 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 ammonium hydroxide solution of formula (I) tested was much more alkaline (approximately 10 to 100 times) than the ammonia and MEA solutions, and that their basicity was comparable to or higher than that of choline hydroxide.

[0094] Example 4: Dissolution of ammonium chloride in a diluted aqueous solution of quaternary ammonium hydroxide of formula (I) Ammonium chloride (0.1 g) was placed in a watch glass, and in all cases, 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 the solutions tested were able to dissolve ammonium chloride, resulting in the generation of ammonia gas. However, a considerably smaller amount of ammonium hydroxide(I) solution was required for complete dissolution compared to the amount of choline hydroxide solution needed for complete dissolution.

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

[0098] [Table 6]

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

[0100] Example 6: Hygroscopicity of chloride salts formed from quaternary ammonium hydroxide of formula (I) Chloride salts derived from ammonium hydroxide(I) were prepared by carefully neutralizing a 5 wt% hydrochloric acid solution to a slightly acidic pH (pH 5.5–6.5) with equimolar amounts of ammonium hydroxide of formula (I), removing water using a rotary evaporator (absolute pressure 15 mbar, 80°C), taking 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 by using an isopropanol washing step in several steps.

[0101] The corresponding dry chloride salts of ammonium(I) hydroxide, prepared in this manner, were placed on watch glasses and stored open in the ambient air of a laboratory at 50% relative humidity 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 hygroscopic properties of the salt were evaluated according to the following scale. 1. Highly hygroscopic: Dissolves in less than 10 minutes. 2. Strong hygroscopic properties: Dissolves in less than an hour. 3. Moderate hygroscopicity: Dissolves in 1 to 6 hours. 4. Weak hygroscopicity; dissolves in 6 to 24 hours. 5. Non-hygroscopic: No visible changes after 24 hours.

[0103] The results are summarized in Table 7.

[0104] [Table 7]

[0105] The data summarized in Table 7 shows that the hygroscopicity of chloride salts derived from ammonium hydroxide (I) ranges from weak to very strong. Therefore, these chloride salts absorb ambient moisture and are converted into fluid solutions in the presence of water. A further series of tests were conducted using salt mixtures consisting of TEA-Cl, a weakly hygroscopic salt, and one of the highly hygroscopic salts, such as choline chloride, DEDMA-Cl, TEMA-Cl, or TPA-Cl, in a weight ratio of 9:1. These mixtures showed higher hygroscopicity compared to, for example, TEA-Cl alone.

[0106] Further experiments conducted using chloride(II) salts in gasoline spiked with ppm amounts of water demonstrated the salts' ability to absorb moisture even from nonpolar hydrocarbon fluids.

[0107] Example 7: pH value of chloride salt solution derived from quaternary ammonium hydroxide of formula (I) 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 reference values. The results are shown in Table 8.

[0108] [Table 8]

[0109] The results summarized in Table 8 show that aqueous solutions of chloride salts derived from ammonium hydroxide (I) are not acidic, but have a nearly neutral pH value.

[0110] Example 8: Corrosiveness of chloride salts derived from quaternary ammonium hydroxide of formula (I) A 30 wt% aqueous solution of purified chloride salt derived from ammonium hydroxide was filled into test tubes (capacity: 15 ml). To allow hydrogen gas to escape from corrosion, pre-weighed carbon steel coupons were placed in each semi-closed tube and immersed vertically in a 70°C oil bath for 24 hours. The coupons were removed from the solution, and corrosion products were removed from the surface by carefully treating them with 10 wt% hydrochloric acid for 1 minute, 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 the two experiments are summarized in Table 9.

[0111] [Table 9]

[0112] Table 9 shows that the corrosiveness of chloride salts derived from quaternary ammonium hydroxide(I) is much lower than that of ammonium chloride and MEA-Cl, and therefore coincides with the low corrosiveness of choline chloride.

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

[0114] [Table 10]

[0115] Table 10 shows that the stability of chloride salts is generally higher than that of their originating hydroxides (comparing the results listed in Table 2). Furthermore, the stability of chloride salts derived from dissolved ammonium hydroxide is higher than that of choline chloride solution. The low stability of choline chloride in aqueous solution is quite surprising considering the high thermal stability of solid choline chloride (see Table 6).

[0116] Example 10: Thermal decomposition of chloride salts derived from quaternary ammonium hydroxide of formula (I) A small amount of pure chloride salt derived from quaternary ammonium hydroxide (I) was subjected to thermal decomposition, and the resulting composition was analyzed by gas chromatography combined with mass spectrometry (thermal decomposition GC / MS). The conditions were as follows: Pyrolysis temperature: 760℃, Pyrolysis time: 20 seconds; Column: CP-select624CB capillary column (Agilent Technologies), length: 30m, film thickness: 1.8μm, inner diameter: 320μm; Detector: Mass-sensitive detector; Compound identification: By comparison with the NIST17 spectral database.

[0117] Table 11 shows the main decomposition products of the compound.

[0118] [Table 11]

[0119] Table 11 shows that chloride salts derived from quaternary ammonium hydroxide (I) decompose into corresponding organic chlorides and tertiary amines, and in particular, substantially no hydrogen chloride is formed in all cases. 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; K. M. Armonetal., 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 typical example, Figure 1 shows the GC / MS partial chromatogram of the pyrolysis of DEDMA-Cl. If present, HCl appears with a very short retention time. HCl was not detected in the pyrolysis of DEDMA-Cl.

[0121] Example 11: Ability of chloride salts derived from ammonium hydroxide to retain hydrogen chloride The hydrogen chloride retention capacity of chloride salts derived from quaternary ammonium hydroxide(I) was tested in the same manner as described in U.S. Patent No. 8,177,962 (see Test Example 1). Specifically, an automated distillation apparatus, similar to those used for the automated distillation of crude oil samples (compared to ASTM D86, IP123, and ISO 3405), was used. Each sample consisted of 95 wt% heavy aromatic solvent with a boiling point range of 180 to 210°C and 5 wt% aqueous phase containing 9 mmol of a chloride salt derived from TEAH, i.e., ammonium hydroxide(I). Ammonium chloride, monoethanolammonium chloride, and choline chloride were used as reference chloride salts. The samples were distilled to the dry point of the automated distillation apparatus while maintaining a constant distillation rate. The aqueous phase of the obtained 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] Table 12 shows that choline chloride and TEA-Cl release far fewer chloride ions 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. A method for reducing or preventing corrosion or fouling in an apparatus for carrying out a chemical process, wherein the corrosion or fouling is caused by an acidic compound present in the chemical process, and the method involves adding at least one of the quaternary ammonium hydroxides 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 Each is independently C １ -C １０ It is an alkyl group, R ４ is C １ -C １８ 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. Wherein monocycloalkyl, bicycloalkyl and tricycloalkyl are unsubstituted or substituted with 1 or 2 methyl groups and groups of formula R ４ａ and R ４ｂ . 【Chemistry 2】 In the formula, A is C ２ -C ８ Alkanzil, A' is C ２ -C ８ Alkanzil, R １１ , R １２ , R １３ , R ２１ , R ２２ Each is independently C １ -C ４ It is alkyl. R １ and R ２ Together with the nitrogen atom, it may form a 5- or 6-membered saturated nitrogen heterocycle that is unsubstituted or has one or two methyl groups. R ３ and R ４ Together with the nitrogen atom, it may form a 5- or 6-membered saturated nitrogen heterocycle that is unsubstituted or has one or two methyl groups.

2. In equation (I), R １ , R ２ , R ３ Each is independently C １ -C ６ Alkyl, R ４ is C ２ -C １８ It is alkyl, R ３ and R ４ The method according to claim 1, wherein the nitrogen atom may form a 5- or 6-membered saturated nitrogen heterocycle that is unsubstituted or has one or two methyl groups.

3. In equation (I), R １ , R ２ , R ３ Each is independently C １ -C ６ Alkyl, R ４ is C ２ -C ６ The method according to claim 2, wherein the alkyl group is alkyl.

4. The method according to 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. The method according to 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, and SO2. ２ SO ３ , nitrogen oxides, CO ２ The method according to any one of claims 1 to 5, selected from the group consisting of carbonic acid, organic carboxylic acids, acidic phosphorus compounds, acidic ammonium salts, and mixtures thereof.

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

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

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

10. The method according to any one of claims 1 to 7, wherein the chemical process is a vapor generation process.

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

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

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

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

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

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

17. Use of a compound according to any one of claims 1 to 5 for reducing or preventing corrosion or fouling in an apparatus for performing a chemical process, wherein the corrosion or fouling is caused by an acidic compound present in the chemical process.

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

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