Method for producing or converting alkanolamines

Abstract

alkanolamine production processes and / or alkanolamine conversion processes carried out on one or more items of equipment, wherein one or more steel parts of the one or more items of equipment having one or more surfaces in contact with the alkanolamines are made of duplex steel; and the use of duplex stainless steel as a material of construction for parts of equipment items used in alkanolamine and / or alkyleneamine production processes or separation processes having one or more surfaces in contact with the alkyleneamines and / or alkanolamines; and the use of duplex steel as a material of construction for steel parts of equipment items used in alkanolamine production or conversion processes.

Description

[Technical field]

[0001] The present invention relates to a process for the production of alkanolamines and a process for the conversion of alkanolamines, which process is carried out in one or more items of equipment, and in which one or more steel parts of the one or more items of equipment having one or more surfaces in contact with the alkanolamines are made of duplex steel. The present invention also relates to the use of duplex steel as a material of construction in a process for the production or conversion of alkanolamines. [Background technology]

[0002] Examples of alkanolamines are ethanolamine and propanolamine.

[0003] Ethanolamine and propanolamine are used as intermediates in the production of surfactants, and are also used as catalysts for polyurethanes, intermediates for agricultural and pharmaceutical products, cosmetics, corrosion inhibitors, cement additives and lubricants. Ethanolamine and propanolamine are also used in gas treating.

[0004] Alkanolamines are also converted to alkyleneamines.

[0005] The most important representatives of this group of compounds are the ethyleneamines, such as ethylenediamine, diethylenetriamine, triethylenetetramine, piperazine, aminoethylpiperazine, and the propyleneamines, such as propylene-1,2-diamine and propylene-1,3-diamine. Ethylenediamine is primarily used as an intermediate in the production of bleach activators, crop protection agents, pharmaceuticals, lubricants, textile resins, polyamides, papermaking aids, gasoline additives, and many other substances.

[0006] Propylene-1,2-diamine is an important intermediate for crop protection agents and is used as an additive in fuels and lubricants.

[0007] Propylene-1,3-diamine is used in the production of textile finishing agents or chelating agents.

[0008] Other commercially relevant alkanolamines and alkyleneamines are the aminodiglycols (ADG), polyglycolamines, polypropylene glycol amines and polyethylene glycol amines.

[0009] Alkanolamine production and conversion processes have in common that they are generally carried out at higher temperatures and pressures in the presence of ammonia or other aminating agents. Hydrogen is often also present in the reaction mixture.

[0010] Production and separation equipment items such as reactors, columns, tanks, pipes, heat exchangers, condensers, etc. used under such conditions must meet various requirements such as mechanical stability, temperature stability, corrosion resistance, and wear resistance.

[0011] In addition, the equipment items must be made from materials of construction that are easy to process and exhibit good resistance to withstand the conditions of the manufacturing process.

[0012] The literature rarely discusses the choice of materials for equipment used in alkanolamine production or conversion processes.

[0013] Most references in the literature refer only to the common use of stainless steel as a reactor material.

[0014] Some alkanolamines and alkyleneamines are used as corrosion inhibitors. This would seem to mean that the choice of materials for the manufacturing and / or separation equipment items used in the manufacture and / or separation of the alkanolamines and / or alkyleneamines is not particularly critical.

[0015] Despite this, it has been found that equipment items made of steel used in the alkanolamine production or conversion process are prone to corrosion and therefore require more frequent repairs and replacements, which significantly reduces the uptime of the alkanolamine production or conversion plant due to the higher frequency of repairs and replacements, which also increases the overall production costs. Summary of the Invention [Problem to be solved by the invention]

[0016] It was therefore an object of the present invention to find a material for an item of equipment used in the production, conversion or separation of alkanolamines, which has high resistance to the conditions of the production, conversion or separation process of alkanolamines.

[0017] In particular, the aim of the present invention was to find a material which is stable to temperature and pressure and which exhibits good resistance to corrosion and wear. In doing so, the aim was to extend the useful life of the equipment before replacement or repair.

[0018] It was also intended to reduce process downtime due to equipment repairs or due to material failure or weakening.

[0019] It was also an object to increase the operational safety of equipment used in such production or separation processes and to avoid and prevent failures of important equipment necessary for the safe operation of the production and separation processes.

[0020] The materials of construction need to exhibit good mechanical stability, enabling equipment designs to use less material compared to traditional steel equipment. Reducing the amount of structural material required is particularly beneficial as resources such as steel become increasingly scarce. [Means for solving the problem]

[0021] The object of the present invention has therefore been solved by a process according to claim 1 and the use of a duplex steel according to claims 1 and 17.

[0022] Surprisingly, it has been found that material selection for equipment used in the production or conversion of alkanolamines is not arbitrary, and advantages can be obtained using reactor materials selected for the conditions encountered during the alkanolamine production, conversion, or separation process.

[0023] Alkanolamines The process of the present invention is a process for the production or conversion of alkanolamines.

[0024] Alkanolamines are a class of compounds that contain both hydroxyl and amino functional groups in an alkane or alkoxyalkane backbone.

[0025] Preferred alkanolamines are ethanolamine, propanolamine and polyglycol monoamines.

[0026] Preferred ethanolamines are - monoethanolamine (MEOA), - Diethanolamine (DEOA), - Triethanolamine (TEOA), - N-Methylethanolamine (NMEA), - N-methyldiethanolamine (NMDEA), - dimethylethanolamine (DMEA), - Diethylethanolamine (DEEA), - n-butylethanolamine, - n-butyldiethanolamine, - dibutylethanolamine, - cyclohexylethanolamine, - cyclohexyldiethanolamine, - 1-(2-hydroxyethylpiperazine, - 4-(2-hydroxyethyl)-morpholine, - hydroxyethylaniline, - ethyl hydroxyethyl aniline, - N-ethylethanolamine, - n-propylethanolamine, - hydroxyethylpiperidine, - dihydroxyethylaniline, tert-butylethanolamine, - tert-Butyldiethanolamine The compound is selected from the group consisting of:

[0027] More preferred ethanolamines are MEOA, DEOA, TEOA, NMEA, NMDEA, DMEA and DEEA.

[0028] Preferred propanolamines are - 2-amino-1-propanol (2-AP), - 1-amino-2-propanol (1-AP), - isopropanolamine (IPA) (a mixture of 2-amino-1-propanol and 1-amino-2-propanol), - Diisopropanolamine (DIPA), - Triisopropanolamine (TIPA), - monomethylisopropanolamine, - methyldiisopropanolamine, - dimethylisopropanolamine, - diethylisopropanolamine, - dibutylisopropanolamine, - cyclohexylisopropanolamine, - cyclohexyl-diisopropanolamine, - cyclooctylisopropanolamine, - cyclooctyl-diisopropanolamine, - aminoethyl isopropanolamine, - 1-(2-hydroxypropyl)-piperazine, - 1,4-bis(2-hydroxypropyl)-piperazine, - 4-(2-hydroxypropyl)-morpholine, - N,N,N'N'-Tetrakis-(2-hydroxypropyl)-ethylenediamine The compound is selected from the group consisting of:

[0029] More preferred propanolamines are 2-AP, 1-AP, IPA, DIPA and TIPA.

[0030] The most preferred propanolamines are those obtained by reaction of propylene oxide with ammonia, namely 1-AP, 2-AP, IPA, DIPA and TIPA.

[0031] Another preferred alkanolamine is aminoglycolamine (ADG).

[0032] Preferred polyglycol monoamines are obtained from the reaction of polyglycols having a number average molecular weight of 200 to 5000, such as polyethylene glycol or polypropylene glycol.

[0033] Alkyleneamine Alkyleneamines are compounds that contain at least two amine functional groups (primary, secondary, or tertiary) in an alkane or alkoxyalkane backbone.

[0034] Preferred alkylene amines are ethylene amines, propylene amines and polyglycol diamines.

[0035] More preferred alkyleneamines are alkyleneamine compounds derived from MEOA (ethyleneamine), 1,2 aminopropanol (1,2-propyleneamine), 1,3-aminopropanol (1,3-propyleneamine) and polyether monoamines (polyetheramines).

[0036] The most preferred ethyleneamines are ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, piperazine and aminoethylpiperazine.

[0037] The most preferred 1,2-propylene amines are 1,2-propylene diamine, 1,2-dipropylene triamine, 1,2-tripropylene tetraamine, 1,2-tetrapropylene pentamine and 1,2-pentapropylene hexamine.

[0038] The most preferred 1,3-propylene amines are 1,3-propylene diamine, 1,dipropylene triamine, 1,3-tripropylene tetraamine, 1,3-tetrapropylene pentamine and 1,3-pentapropylene hexamine.

[0039] The most preferred polyglycol diamines are those of formula (I): R 1 R 2 N-(CHR 3 -CH 2 -O) l -CH 2 -CHR-OH (I) (In the formula, R 1 and R 2 has the meaning given below, R 3 is H, methyl or ethyl, and l is an integer of 2 to 70, preferably 2 to 10, and most preferably 2 to 6.

[0040] Alkanolamine Production Process and Alkanolamine Conversion Process Processes for the preparation and conversion of alkanolamines are known in the art. The most important routes are summarized below.

[0041] Alkanolamines can be prepared by conversion of alkylene oxides (the alkylene oxide process), polyols (the polyol amination process), hydroxyketones or hydroxyaldehydes (the reductive amination process) with an aminating agent.

[0042] The alkanolamines can be further converted to the corresponding alkyleneamines using an aminating agent (the alkanolamine amination process).

[0043] The aminating agent is a compound selected from the group consisting of ammonia, primary amines and secondary amines.

[0044] Preferably, the aminating agent is a compound of formula (II): NHR 1 R 2 (II) (In the formula, R 1 and R 2 is, independently, hydrogen, C 1 -C 20 -alkyl, in particular methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, n-pentyl, isopentyl, sec-pentyl, neopentyl, 1,2-dimethylpropyl, n-hexyl, isohexyl, sec-hexyl, n-heptyl, isoheptyl, n-octyl, 2-ethylhexyl, n-decyl, 2n-propyl-n-heptyl, n-tridecyl, 2-n-butyl-n-nonyl and 3-n-butyl-n-nonyl, more preferably C 1 -C 4 - alkyl, in particular methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl and sec-butyl, C 3 -C 12 -Cycloalkyl, in particular cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, preferably C 5 -C 8 -cycloalkyl, in particular cyclopentyl, cyclohexyl, cycloheptyl and cyclooctyl, R1 and R 2 combine to form -(C) j -X-(C) k where j and k are integers from 1 to 4, and in particular -(CH 2 ) 3 -, -(CH 2 ) 4 -, -(CH 2 ) 5 -, -(CH 2 ) 6 -, -(CH 2 ) 7 -, -(CH 2 )-O-(CH 2 ) 2 -, -(CH 2 )-NR 5 -(CH 2 ) 2 -, -(CH 2 )-CHR 5 -(CH 2 ) 2 -, -(CH 2 ) 2 -O-(CH 2 ) 2 -, -(CH 2 ) 2 -NR 5 -(CH 2 ) 2 -, -(CH 2 ) 2 -CHR 5 -(CH 2 ) 2 -, -CH 2 -O-(CH 2 ) 3 -, -CH 2 -NR 5 -(CH 2 ) 3 - and -CH 2 -CHR 5 -(CH 2 ) 3 --It could be.

[0045] The most preferred aminating agents are those selected from the group consisting of ammonia, methylamine, dimethylamine, ethylamine, diethylamine, n-propylamine, isopropylamine, di-n-propylamine, diisopropylamine, n-butylamine, isobutylamine, sec-butylamine, di-n-butylamine, diisobutylamine, di-sec-butylamine, n-pentylamine, n-hexylamine, cyclohexylamine and cyclooctylamine.

[0046] Particularly preferred aminating agents are those selected from the group consisting of ammonia, methylamine, ethylamine, n-propylamine, isopropylamine, n-butylamine, isobutylamine, sec-butylamine and cyclohexylamine.

[0047] Further processes for the production or conversion of alkanolamines are the amino acid process and the urea process (both identified below).

[0048] Detailed description of the process The alkylene oxide process, the polyol amination process, the reductive amination process, the amino acid process and the urea process are described in further detail below.

[0049] Alkylene Oxide Process In a preferred embodiment, the alkanolamines are obtained by conversion of alkylene oxides with an aminating agent (the "alkylene oxide process").

[0050] Preferred alkylene oxides are ethylene oxide, propylene oxide and butylene oxide.

[0051] The most preferred alkylene oxides are ethylene oxide and propylene oxide.

[0052] The alkylene oxide process is the most preferred process for the production of ethanolamine and 1,2-propanolamine.

[0053] The most preferred ethanolamines produced by the alkylene oxide process are monoethanolamine (MEOA), diethanolamine (DEOA), triethanolamine (TEOA), N-methylethanolamine (NMEA), N-methyl-diethanolamine (NMDEA), dimethylethanolamine (DMEA) and diethylethanolamine (DEEA).

[0054] Such ethanolamines are obtainable by reaction of ethylene oxide with the corresponding aminating agents, in particular ammonia and the corresponding alkylamines and dialkylamines, such as methylamine, dimethylamine, ethylamine and diethylamine.

[0055] The most preferred 1,2-propanolamines which may be produced by the alkylene oxide process are 2-amino-1-propanol (2-AP), 1-amino-2-propanol (1-AP), isopropanolamine (IPA) (a mixture of 2-amino-1-propanol and 1-amino-2-propanol), diisopropanolamine (DIPA) and triisopropanolamine (TIPA).

[0056] Such 1,2-propanolamines can be obtained by reaction of propylene oxide with the corresponding aminating agents, in particular ammonia or the corresponding alkylamines and dialkylamines.

[0057] An overview of the alkylene oxide process can be found in the chapter "Ethanolamines and Propanolamines" in Ullmann's Encyclopedia of Industrial Chemistry (https: / / doi.org / 10.1002 / 14356007).

[0058] According to this publication, ethanolamines are produced on an industrial scale by the reaction of ethylene oxide with excess ammonia. The reaction is facilitated by water. The ammonia concentration is typically 50-100%. Pressures typically range up to 160 bar and temperatures up to 150°C. The molar excess of ammonia is typically up to 40 moles per mole of ethylene oxide. The reaction produces monoethanolamine, diethanolamine and triethanolamine as by-products. Unconsumed ammonia and water are typically separated from the product in downstream purification processes and recycled to the reactor. A typical process flow diagram for ethylene oxide conversion is shown in Figure 2 of the Ullmann chapter cited above.

[0059] Further process variations can be found in PERP report 01 / 02S2 “Ethanolamines” (2002), available from Nexant Chem Systems or in the Sulzer Technical review 3 / 2008 (https: / / www.sulzer.com / - / media / files / products / process-techology / processes-and-applications / 2008_3_12_faessler_e.pdf?la=en).

[0060] Further details can also be found in patent documents such as US Patent No. 2,196,554, US Patent No. 3,697,598, US Patent No. 3,723,530, WO 2006 / 224417, WO 01 / 94290, EP 1291339, DE 1941859, EP 1652207, DE 1941859 and EP 1652207. The aforementioned references are incorporated herein by reference.

[0061] The production of isopropanolamine is similar to the production of ethanolamine, except that propylene oxide is used instead of ethylene oxide as the alkylene oxide component (see Ullmann, supra, Chapters 4.2 and 5.2).

[0062] Polyol Amination Process In a more preferred embodiment, the alkanolamines are prepared by converting a polyol with an aminating agent in the presence of an amination catalyst (the alcohol amination process).

[0063] A polyol is a compound that contains two or more hydroxyl groups.

[0064] Preferred polyols are Molyethylene glycol, Diethylene glycol, Polyol of formula (2) HO-CHR 3 -CH 2 -(O-CHR 3 -CH 2 ) l -OH(in the formula, R 3 and l have the meaning given above, in particular polyethylene glycol (PEG) and polypropylene glycol (PPG) with a number average molecular weight of from 200 g / mol to 5000 g / mol, preferably from 200 g / mol to 500 g / mol, 1,2-propanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, 1,2-butanediol, 1,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, It is selected from the group consisting of glycerin, trimethylolpropane, neopentyl glycol, and trimethylpentanediol.

[0065] Preferred aminating agents are those mentioned above.

[0066] The most preferred aminating agents for the polyol amination process are ammonia, methylamine, ethylamine, n-propylamine, diisopropylamine, n-butylamine, sec-butylamine, isobutylamine and tert-butylamine.

[0067] Details regarding the preparation of alkanolamines from polyols can be found in EP 0 382 049, EP 2 234 717, EP 2 225 030, EP 2 225 027 or EP 0 382 049, all of which are incorporated herein by reference.

[0068] In a particularly preferred embodiment, the polyol amination process comprises: - Ethylene glycol with ammonia (MEG amination process), - Diethylene glycol with ammonia (DEG amination process), 1,2-propanediol or 1,3-propanediol with ammonia (PDO amination process), or - a process for the conversion of polyglycols of formula (1), preferably PPG having a number molecular weight between 200 and 500 g / mol, with ammonia (polyglycol amination process).

[0069] The polyol amination process can be viewed as both an alkanolamine production process and an alkanolamine conversion process, since the intermediate alkanolamine can further react with the corresponding alkyleneamine. The product distribution between alkanolamines and alkyleneamines depends on the molar ratio of aminating agent to polyol. Excess aminating agent usually favors the formation of alkyleneamines.

[0070] MEG Process A preferred polyol amination process is the conversion of monoethylene glycol with ammonia to produce a mixture of alkanolamines and ethyleneamines (the MEG process).

[0071] The reaction of MEG with ammonia can be carried out in the liquid phase or in the gas phase.

[0072] Gas phase reactions are disclosed, for example, in CN102190588 and CN102233272.

[0073] Preferably, the conversion of MEG with ammonia is carried out in the liquid phase according to U.S. Pat. No. 4,111,840, U.S. Pat. No. 3,137,730, German Patent No. 172268, WO 2007 / 093514, WO 2007 / 093552, WO 2018 / 224316, WO 2018 / 224315, WO 2018 / 224321 and WO 2020 / 17085, all of which are incorporated herein by reference.

[0074] Preferred amination catalysts in the MEG process are: - nickel-rhenium catalysts as disclosed in U.S. Pat. No. 4,111,840; - nickel-copper catalysts as disclosed in U.S. Pat. No. 3,137,730; - ruthenium-cobalt catalysts as disclosed in WO2007093514; - A catalyst comprising cobalt, ruthenium and tin as disclosed in WO 2018224316; - a catalyst comprising tin and a further active metal as disclosed in WO 2018224315; - the impregnated catalysts disclosed in WO 2018224321, or - A rhenium-containing catalyst as disclosed in WO202017085.

[0075] The above documents disclosing suitable catalysts are expressly incorporated by reference. The catalysts disclosed in the examples of the above-referenced documents are particularly preferred.

[0076] DEG Process A more preferred polyol amination process is the conversion of diethylene glycol with ammonia (DEG process), producing a mixture of aminodiglycol (ADG) and morpholine.

[0077] Details regarding this process can be found in WO2008006752, WO03051508, EP0695572, EP1937625 and EP2506966, all of which are incorporated herein by reference.

[0078] PDO Process Yet another preferred polyol amination process is the conversion of 1,2-propanediol or 1,3-propanediol with ammonia in the presence of an amination catalyst (DEG process) to produce the corresponding propyleneamines and propanolamines. The process conditions and configuration are similar to those of the DEG process.

[0079] Polyglycol amination process A more preferred polyol amination process is the conversion of polyglycols with ammonia to produce a mixture of polyglycol-monoamines and polyglycol-diamines (the polyglycol amination process).

[0080] Preferred polyglycols are polyols of formula (2), in particular polypropylene glycols or polyethylene glycols having a number average molecular weight of 200 to 5000 g / mol, preferably 200 to 500 g / mol. Preferred propylene glycols have number average molecular weights of 230, 400, 2000 and 4000.

[0081] Details can be found in EP 696572, WO 09092724, WO 2008067857 and WO 2016091643, which are incorporated herein by reference.

[0082] Reductive Amination Process In a further preferred embodiment, the alkanolamine is They are prepared by the conversion of a hydroxyketone or hydroxyaldehyde with an aminating agent in the presence of an amination catalyst (reductive amination process).

[0083] A hydroxyketone is a compound that contains at least one hydroxyl group and one keto group. Hydroxyaldehydes are aldehydes that contain one or more hydroxyl groups.

[0084] Preferably, the hydroxyketones and hydroxyaldehydes are selected from the group consisting of hydroxypivalaldehyde, dimethylolpropionaldehyde and dimethylolbutyraldehyde.

[0085] Further details can be found in EP 1 487 573, EP 1 999 099 and EP 2 225 029, all of which are incorporated herein by reference.

[0086] Glycolaldehyde Process A particularly preferred embodiment of the reductive amination process is the conversion of glycolaldehyde with an aminating agent, preferably ammonia, monoethanolamine or diethanolamine.

[0087] Details are disclosed in U.S. Patent Application Publication No. 20120259139, U.S. Patent No. 8,772,548, WO 2019193117, WO 20200028322, WO 2020249426, WO 2020249427 and WO 2020249428, all of which are incorporated herein by reference.

[0088] Amino Acid Process A preferred route to alkanolamines is the hydrogenation of amino acids.

[0089] Preferred amino acids are serine, alanine and valine.

[0090] Details regarding process conditions can be found in Pimparkar et al., "Hydrogenation of Amino Acid Mixtures to Amino Alcohols" (ind. Eng. Chem. Res. 2008, 47, 20, 7648-7653, Publication Date: September 12, 2008, https: / / doi.org / 10.1021 / ie800351x), U.S. Pat. No. 6,310,254, EP 0 696 575, WO 99 / 38838, or U.S. Patent Application Publication No. 20070142648, all of which are incorporated herein by reference.

[0091] Alkanolamine amination process A preferred embodiment of the alkanolamine conversion process is a process in which the alkanolamine is converted to the corresponding diamine or polyamine with an aminating agent (alkanol amination process).

[0092] MEOA Process: A preferred alkanol amination process is the conversion of monoethanolamines to ethyleneamines with ammonia in the presence of an amination catalyst (the MEOA process).

[0093] The reaction of MEOA with ammonia is described, for example, in US Pat. No. 2,861,995, DE-A-1 172 268 and US Pat. No. 3,112,318. A summary of the various process variants of the reaction of MEA with ammonia can be found, for example, in PERP Report No. 138 "Alkylamines", SRI International, 03 / 1981 (in particular pages 81-99, 117), all of which are incorporated herein by reference.

[0094] The reaction of MEOA with ammonia is preferably carried out at 150-250 bar and 160-210° C. in the presence of a transition metal catalyst or at 1-20 bar and 280-380° C. over a zeolite catalyst.

[0095] The transition metal catalyst preferably used is an oxide support (e.g., Al 2 O 3 ,TiO 2 ,ZrO 2 ,SiO 2 ) Ni, Co, Cu, Ru, Re, Rh, Pd or Pt, or a mixture of two or more of these metals.

[0096] Preferred zeolite catalysts are mordenite, faujasite and chabazite.

[0097] To achieve maximum EDA selectivity, a molar ratio of ammonia to MEOA of 6-20, preferably 8-15, is generally used for transition metal catalysts, and 20-80, preferably 30-50, is generally used for zeolite catalysts.

[0098] The conversion of MEOA is generally maintained between 10% and 80%, preferably between 40% and 60%.

[0099] In continuous operation, a catalyst space velocity in the range of 0.3-0.6 kg / (kg·hr) (kg MEOA per kg catalyst per hour) is preferably established.

[0100] To maintain catalytic activity, when using metal catalysts, 0.05 to 0.5 weight percent hydrogen (MEOA+NH 3 +H 2 It is preferred to additionally feed 100 ml of ethanol (based on the reaction charge) to the reactor.

[0101] MPOA Process A more preferred alkanol amination process is the conversion of 1,2-propanolamine or 1,3-propanolamine to the corresponding propyleneamines with ammonia in the presence of an amination catalyst (the MPOA process).

[0102] The reaction conditions are similar to those disclosed for the MEOA process.

[0103] Urea Process A preferred alkanolamine conversion process is the so-called urea process, which converts ethanol-functional compounds with primary amines in the presence of a carbon dioxide delivery agent.Details of such processes are disclosed in WO 2017 / 137532, WO 2019 / 030191 and WO 2019 / 011710, which are also incorporated herein by reference.

[0104] Disclaimer The present invention renounces any process in which alkanolamines are used as absorbents for gas treatment. Specifically, the process involves the addition of alkanolamines to a packed absorbent and CO 2 , H 2 Any reaction with acid gases, such as S or COS, and regeneration of the packed absorbent to alkanolamines is not considered an alkanolamine production or conversion process.

[0105] Equipment items The process according to the invention is carried out in one or more items of equipment. Equipment items include all items, apparatus, machinery, or equipment necessary for the proper functioning of the plant in which alkanolamines are produced or converted and separated. Equipment items are usually summarized in the process flow sheet and listed in the equipment list.

[0106] Equipment items may include agitators, air filters, bins, blenders, blowers, centrifuges, compressors, condensers, conveyors, cooling columns, crushers, crystallizers, cyclone separators, decanters, dispersers, drums, dryers, evaporators, feeders, filters, furnaces, grinders, heat exchangers, kettles, kilns, mixers, ovens, pumps, reboilers, reactors, separators, spray discs, nozzles, tanks, towers, tray vacuum pumps, valves, and pipes.

[0107] Such equipment items used to convert one or more extracts into a desired product are commonly referred to as manufacturing equipment.

[0108] Such equipment items that are used to separate one or more components from one or more manufactured items, where the extract is at least partially converted to a desired product, are typically referred to as separation equipment items.

[0109] Parts of Equipment Items An equipment item may consist of a single piece, or it may consist of two or more pieces connected or adjacent to form the equipment item.

[0110] One or more parts of an equipment item can be made of steel (a "steel part") or can be made of a different material (a "non-steel part").

[0111] One or more steel parts of the item of equipment may have one or more surfaces that are in contact with the alkanolamine ("exposed steel parts"), or one or more steel parts may have surfaces that are not in contact with the alkanolamine (non-exposed steel parts).

[0112] The present invention relates to parts of equipment items that are usually made of steel, therefore parts of equipment items that, due to their purpose and requirements, are usually made of materials different from steel, such as rubber or Teflon fittings, can still be used in the process according to the invention and do not have to be made of duplex steel.

[0113] The present invention does not require that all steel components of an equipment item be made of duplex steel. In accordance with the present invention, only one or more of the exposed steel components of one or more equipment items need to be made of duplex steel, while the non-exposed steel components can be made of a non-duplex steel grade.

[0114] Additionally, the present invention does not require that all exposed steel components of all equipment items used in the manufacturing and / or separation process must be made from duplex steel.

[0115] The advantages of the present invention can already be obtained if at least one exposed steel part of one or more equipment items is made of duplex steel, however, the more exposed steel parts of an equipment item are made of duplex steel, the more advantages can be utilized.

[0116] If all exposed steel parts of an equipment item are made of duplex steel, it is avoided that one non-duplex steel part of the equipment item becomes a bottleneck for that particular equipment item.

[0117] If all exposed steel parts of all equipment items are made of duplex steel, then one equipment item is prevented from becoming a bottleneck in the manufacturing or separation process, and problems caused by combining or joining different material grades are typically avoided.

[0118] In a preferred embodiment, one or more non-exposed steel components of one or more equipment items are also made from duplex steel, which has the advantage of reducing issues such as interface cracking or wear caused by using different material grades.

[0119] Made from duplex steel According to the present invention, one or more steel components of one or more items of production and separation equipment having one or more surfaces in contact with the alkanolamine are made of duplex steel.

[0120] In the sense of this specification, the term "made of duplex steel" does not require that the entire steel part consists of duplex steel, it also includes steel parts coated with duplex steel or having an inliner made of duplex steel.

[0121] In a preferred embodiment, the term "made of duplex steel" in relation to a steel part having an exposed surface is intended to mean that the steel part is completely made of or consists of duplex steel.

[0122] This has the advantage that the manufacturing process for equipment parts can be simplified and more economical when only one steel grade is used when forming, spinning, pressing, bending or welding the steel into the desired steel part.

[0123] Main and auxiliary equipment items Equipment items can be further distinguished into major and auxiliary equipment items.

[0124] Major equipment items are typically non-standard equipment items that are customized to meet required process specifications.

[0125] Ancillary equipment items are typically items of equipment used to support or assist a primary equipment item in fulfilling its functional duties. Ancillary equipment is more commonly available off-the-shelf.

[0126] Major Equipment Items The following list of major equipment items is illustrative and not exhaustive as major equipment items may vary depending on the exact implementation of the manufacturing or conversion process.

[0127] Also, the list of steel parts with exposed surfaces for the major equipment is merely illustrative and not exhaustive, as the parts may vary depending on the exact design of the major equipment item.

[0128] In a preferred embodiment, the one or more major equipment items for the alkanolamine production process and / or conversion process are one or more items selected from the group consisting of reactors, vessels, heat exchangers, condensers, agitators, and columns.

[0129] Preferred reactors are tubular reactors, fixed bed reactors and stirred tank reactors.

[0130] Preferred steel components of the reactor having an exposed surface are preferably one or more components selected from the group consisting of the reactor vessel or mantle, distributor, outlet collector, support grid, quench pipe, support beam, diffuser, nozzle, baffle, center pipe, scallops, tray, reactor lid, inlet head, and outlet head.

[0131] As previously mentioned, it is preferred that all exposed steel components of major equipment items are made of duplex steel. If all exposed steel components are made of duplex steel, it is avoided that non-duplex steel components get in the way of major equipment needing replacement or repair before other duplex steel components need replacement or repair.

[0132] Preferred vessels are flash vessels, storage vessels, buffer vessels and separation vessels.

[0133] The preferred steel parts of the vessel having an exposed surface are preferably one or more parts selected from the group consisting of the vessel housing itself, the inlet, the outlet, the degassing mesh, the vortex stopper, the baffle and the diffuser.

[0134] Preferred heat exchangers and condensers are tube-shell heat exchangers, double-pipe heat exchangers and plate heat exchangers.

[0135] The preferred steel parts of the heat exchanger having an exposed surface are preferably one or more parts selected from the group consisting of plates, covers, coils, baffles, tubes, shells, heads and sheets.

[0136] Preferred agitators are turbine agitators, anchor agitators, paddle agitators, propeller agitators and helical agitators.

[0137] The preferred steel parts of the agitator having an exposed surface are preferably one or more parts selected from the group consisting of the shaft, the impeller and the impeller blades.

[0138] Preferred columns are bubble cap tray columns, sieve tray columns, dual flow tray columns, valve tray columns, baffle tray columns, or columns having random or structured packing.

[0139] The preferred steel components of the column having an exposed surface are preferably one or more components selected from the group of shell or mantle, column head, trays, packing, support grids, distributors, collectors, inlets and outlets.

[0140] The column is also preferably connected to a reboiler, such as a natural or forced circulation evaporator, or alternatively, it is possible to use evaporators with a short residence time, such as falling film, helical tube, wiped-film or short-path evaporators.

[0141] The preferred steel parts of the reboiler having an exposed surface are preferably one or more parts selected from the group of baffles, heating coils, heating plates, tube bundles, weirs, support plates, partitions, shells, heads, outlets and inlets.

[0142] Auxiliary equipment In a preferred embodiment, not only the steel parts having exposed surfaces of the primary equipment items but also the steel parts having exposed surfaces of the auxiliary equipment items are made from duplex steel.

[0143] The auxiliary equipment items are preferably selected from the group consisting of pumps, compressors, pipes and valves.

[0144] In a more preferred embodiment, the fastening means having an exposed surface is also made of duplex steel.

[0145] A fastening means is a means for connecting separate parts of an equipment item to form the equipment item.

[0146] Preferably, the fastening means is one or more means selected from the group of nuts, bolts, fittings, sealing rings, flanges and screws.

[0147] Parts made from duplex steel As mentioned above, the advantages of the present invention can already be exploited if at least one steel part of at least one equipment item is made of duplex steel.

[0148] However, the advantages of the present invention can be better utilized if one or more exposed steel components of one or more major equipment items are made of duplex steel, which is usually tailored to a specific manufacturing or conversion process and therefore makes it more difficult to replace such items compared to standardized equipment items or equipment items available in racks.

[0149] However, it is more preferred that all exposed steel parts of at least one major equipment item are made of duplex steel, which has the advantage that non-duplex steel parts do not interfere with the stability of the entire equipment item.

[0150] It is also preferred that all exposed steel parts of all major equipment items are made of duplex steel, as this has the advantage that major equipment items that are not made of duplex steel would be bottlenecks in the process.

[0151] Even more preferably, all steel parts (exposed and non-exposed) of at least one equipment item are made of duplex steel, in which case possible drawbacks caused by joining or combining different grades of materials can be avoided.

[0152] It is further preferred that all steel components of all major equipment items are made from duplex steel.

[0153] In addition to the high duplex steel content in the primary equipment as outlined above, it is further preferred that one or more exposed steel components of one or more auxiliary equipment items are also made from duplex steel.

[0154] It is particularly preferred that all exposed steel parts of one or more auxiliary equipment items are made from duplex steel, more preferred that all exposed steel parts of all auxiliary equipment items are made from duplex steel. Even more preferred, all steel parts (exposed and non-exposed steel parts) of one or more, and even more preferred all, auxiliary equipment items are made from duplex steel.

[0155] In another preferred embodiment, all exposed steel parts of all primary and auxiliary equipment items are made of duplex steel, preferably all steel parts (exposed and non-exposed) of all auxiliary and primary equipment items are made of duplex steel.

[0156] Hydrogen exposure In the most preferred embodiment, only the steel parts having exposed surfaces are made of duplex steel, which is further in contact with a liquid phase, where the hydrogen concentration in the liquid phase is 0.1 weight percent or less, preferably 0.05 weight percent or less, more preferably 0.01 weight percent or less. Duplex steel is not a preferred material choice, since if the manufacturing or conversion process is carried out with hydrogen concentrations above the aforementioned limits, hydrogen can cause undesirable hydrogen embrittlement of the duplex steel parts.

[0157] Therefore, if steel components are to be exposed to hydrogen beyond the aforementioned values, it is preferred that such steel components be made from conventional stainless steels which have good resistance to hydrogen embrittlement.

[0158] It is therefore also preferred that for alkanolamine production processes and alkanolamine conversion processes carried out in the presence of hydrogen exceeding the aforementioned limits, only the separation equipment items downstream of the production items are made of duplex steel, after the separation step which results in a sufficient reduction of the hydrogen concentration in the liquid phase.

[0159] Exposure to water In a further preferred embodiment, only the bare steel parts are made of duplex steel exposed to a liquid phase comprising water. Exposed to water within the meaning of the present invention means that the water concentration in the liquid phase comprising water and alkanolamine is 10 weight percent or more, preferably 20 weight percent or more, most preferably 30 weight percent or more. Aqueous alkanolamine solutions appear to have a particularly adverse effect on the service life of manufacturing and separation equipment items.

[0160] Exposure to temperature In yet another preferred embodiment, only the exposed steel parts are made of duplex steel that is exposed to temperatures of 30° C. or more, more preferably 40° C. or more, even more preferably 50° C. or more, and most preferably 75° C. or more. When exposed to such temperatures, the exposed steel parts have been found to be particularly susceptible to corrosion if they are not made of duplex steel.

[0161] Exposure to pressure In yet another preferred embodiment, only exposed steel parts are made of duplex steel exposed to pressures between 10 mbar and 300 bar, more preferably between 20 mbar and 250 bar, most preferably between 40 and 200 bar.

[0162] Corrosive Compounds In yet another preferred embodiment, the effluent obtained by the method according to any one of the claims comprises at least one corrosive compound selected from the group consisting of: (i) acids selected from the group consisting of formic acid, acetic acid, oxalic acid, glycolic acid, glyoxylic acid, propionic acid and glycine, (ii) the corresponding ammonium salts of such acids, (iii) carbamic acid, and (iv) ammonium carbamate.

[0163] The method and process of the present invention are preferably carried out in the absence of oxygen and carbon dioxide, i.e. under conditions where the respective concentrations of oxygen and carbon dioxide are preferably 500 ppm or less, more preferably 400 ppm or less, most preferably 300 ppm or less. Surprisingly, it has been found that, even though the method according to the present invention is preferably carried out in the absence of oxygen and carbon dioxide, trace contaminants of oxygen and carbon dioxide in the process can cause the formation of decomposition products of the alkanolamine, especially when the alkanolamine is MEOA. These decomposition products can be corrosive compounds.

[0164] Preferably, the corrosive compound is an acid selected from the group consisting of formic acid, acetic acid, propionic acid, oxalic acid, glycolic acid, glyoxylic acid and glycine.

[0165] Other corrosive compounds are the corresponding ammonium salts of the aforementioned acids, obtained by reaction of the aforementioned acids with primary, secondary or tertiary amines, preferably alkanolamines, present in the process according to the invention or with the amines obtained by conversion thereof.

[0166] The corrosive compound may also be a carbamic acid. The carbamic acid may be obtained by reaction of a primary, secondary or tertiary amine with carbon dioxide in the process according to the invention. Carbon dioxide may be formed by decarboxylation of an alkanolamine, in particular MEOA and its corresponding conversion products. Preferred carbamic acids are the acids obtained by reaction of carbon dioxide with MEOA or the corresponding amines obtained by conversion of MEOA.

[0167] Further corrosive compounds that may cause corrosion are carbamates. Preferably, the carbamates are formed by reaction of the aforementioned carbamic acids with primary, secondary or tertiary amines in the process according to the invention. In particular, the carbamates are formed by reaction of the aforementioned carbamic acids with alkanolamines, in particular MEOA, or amines obtained from their conversion.

[0168] Surprisingly, it has been found that corrosion of stainless steel in the method according to the invention can occur when the concentration of the aforementioned corrosive compounds is low. Therefore, it is preferred to carry out the method according to the invention when the effluent of the method according to the invention contains the aforementioned corrosive compounds, and the concentration of the aforementioned corrosive compounds in the effluent is in the range of 10 ppm to 500 ppm, preferably 20 ppm to 400 ppm, more preferably 30 to 350 ppm, and most preferably 40 to 300 ppm.

[0169] Process-specific design Considering exposure to water, pressure, and temperature, both production and separation equipment used in alkylene oxide processes can include one or more exposed steel parts made of duplex steel according to the present invention. Since the process is typically carried out in the absence of additional hydrogen, the production equipment items are typically not exposed to hydrogen. It is therefore preferred that at least one exposed steel part of at least one production equipment item and at least one separation equipment item is made of duplex steel according to the present invention. This also applies to the urea process.

[0170] Polyol amination processes, in particular the MEG, DEG and polyglycol processes, as well as processes for the conversion of alkanolamines, in particular the MEOA and MPOA processes, as well as reductive amination processes, in particular the GA process, as well as amino acid processes, are usually carried out in the presence of hydrogen. For these processes, it is preferred that only the steel parts of the equipment items that are not additionally exposed to hydrogen (within the meaning of the present invention) are made of duplex steel. Therefore, it is preferred that the exposed steel parts of the equipment items that are additionally exposed to hydrogen, such as reactors, flash vessels, heat exchangers, piping, valves, coolers, etc., located upstream of the steps where the hydrogen concentration is sufficiently reduced, are not made of duplex steel.

[0171] On the other hand, exposed steel parts of items of equipment located downstream of one or more hydrogen separation steps where the hydrogen concentration in the liquid phase is reduced to the abovementioned hydrogen concentrations are preferably made of the duplex steel according to the invention.

[0172] Duplex Stainless Steel: According to the invention, one or more parts of one or more items of equipment are made from duplex steel.

[0173] Duplex steels are stainless steels that contain both austenite and ferrite phases in their metallurgical structure.

[0174] The weight ratio of the austenite phase to the ferrite phase is preferably in the range of 30:70 to 70:30, more preferably in the range of 40:60 to 60:40, and most preferably these phases are in approximately equal ratio.

[0175] The duplex steel preferably contains chromium in the range of 10 to 35 weight percent, and more preferably in the range of 20 to 30 weight percent.

[0176] The duplex steel preferably contains molybdenum in the range of 0.1 to 5 weight percent, more preferably 0.3 to 4 weight percent.

[0177] The duplex steel preferably contains nickel in the range of 1 to 10 weight percent, more preferably 1.5 to 7 weight percent.

[0178] The duplex steel also contains nitrogen, preferably in the range of 0.05 to 0.5 weight percent, more preferably 0.1 to 0.4 weight percent.

[0179] Preferably, the duplex steel comprises two or more of the abovementioned elements in the ranges mentioned above.

[0180] More preferably, the duplex steel comprises all of the above mentioned elements in the above mentioned ranges.

[0181] In addition, the duplex steel contains one or more of the following elements in the amounts specified below: Carbon, preferably in an amount of 0.05 weight percent or less; Silicon, preferably in an amount of 1 weight percent or less; manganese, preferably in an amount of 10 weight percent or less; a phosphor, preferably in an amount of 0.05 weight percent or less; sulfur, preferably in an amount of 0.03 weight percent or less; Wolfram, preferably in an amount of 0.25 to 1.5 weight percent; Cobalt, preferably in an amount of 0.25 to 3 weight percent, 3275 Copper, preferably in an amount of 0.05 to 5 weight percent.

[0182] Preferred duplex steels are those having the following UNS (Uniform Numbering System) designations: Selected from S31200, S31260, S31803, S32001, S32003, S32101, S32202, S32205, S32304, S32506, S32520, S32550, S32750, S32760, S32808, S32900, S32906, S32950, ​​S39274, S81921, S82011, S82012, S82013, S82031, S82122, S82441.

[0183] More preferred duplex steels are those having the following UNS designations: S31803 and S32750 is selected from the group consisting of:

[0184] The scope of the present invention covers embodiments in which different exposed steel components of an equipment item or different equipment items are made from two or more duplex steel grades.

[0185] However, to avoid residual risks arising from the use of materials with slightly different properties, it is preferred that all exposed steel parts of an equipment item made from duplex steel be made from the same duplex steel grade.

[0186] The present invention also relates to the use of duplex stainless steel as a material of construction for parts of equipment items used in alkanolamine and / or alkyleneamine production or separation processes having one or more surfaces in contact with alkyleneamines and / or alkanolamines.

[0187] The present invention also relates to the use of duplex stainless steel as a material of construction for main and / or auxiliary equipment items and / or parts of fastening means used in alkanolamine and / or alkyleneamine production processes or separation processes having one or more surfaces in contact with alkyleneamines and / or alkanolamines.

[0188] The present invention also relates to the use of duplex stainless steel as a material of construction for parts of major equipment items used in the production process or separation process of alkanolamines and / or alkyleneamines having one or more surfaces in contact with the alkyleneamines and / or alkanolamines selected from the group of reactors, vessels, heat exchangers, condensers, agitators and columns.

[0189] The present invention also relates to the use of duplex stainless steel as a material of construction for parts of auxiliary equipment items used in the production process or separation process of alkanolamines and / or alkyleneamines, having one or more surfaces in contact with alkyleneamines and / or alkanolamines, selected from the group of pumps, compressors, valves and pipes.

[0190] The present invention also relates to the use of duplex stainless steel as a material of construction for fastening means having one or more surfaces in contact with alkyleneamines and / or alkanolamines, selected from the group consisting of nuts, bolts, fittings, sealing rings, flanges and screws, used in the production process or separation process of alkanolamines and / or alkyleneamines.

[0191] Furthermore, the present invention also relates to the use of duplex stainless steel as a material of construction for parts of equipment items used in alkanolamine and / or alkyleneamine production or separation processes having one or more surfaces in contact with alkyleneamines and / or alkyleneamines, wherein the effluent from the alkanolamine production or alkanolamine conversion process contains 10 to 500 ppm of corrosive compounds selected from the group consisting of: (i) acids selected from the group consisting of formic acid, acetic acid, oxalic acid, glycolic acid, glyoxylic acid, propionic acid and glycine, (ii) the corresponding ammonium salts of such acids, (iii) carbamic acid, and (iv) ammonium carbamate.

[0192] Additionally, the present invention relates to the use of duplex stainless steel in alkanolamines and / or in processes for the conversion of alkanolamines, in which the process for the production of alkanolamines or the process for the conversion of alkanolamines is carried out according to at least one embodiment of the present invention, in particular by a method according to any one of the claims of the present invention.

[0193] The advantage of the present invention is that reactors for the preparation process of ethyleneamines and / or ethanolamines can be reduced in thickness of material compared to conventional stainless steel. The reactors are also found to be more resistant to corrosion and wear. Thus, the intervals between service or maintenance can be increased. Also, the useful life of the reactor is increased. Equipment items are less susceptible to damage. Thus, equipment failures are less likely to occur. Thus, the capacity of the alkyleneamines and / or alkanolamines production process or the alkyleneamines and / or alkanolamines separation process can be increased, since the operating time during which products can be produced and / or separated is increased.

[0194] The advantages of the present invention are demonstrated by the following examples. EXAMPLES

[0195] Comparative Example 1: A plant for producing ethyleneamines from monoethanolamine and ammonia, comprising: (i) a step of converting ammonia and monoethanolamine in the presence of hydrogen and an amination catalyst; (ii) a working section comprising: a) a section for removing hydrogen and ammonia; b) a section for removing water; and c) a section for separating value products comprising: 1) a section for separating EDA and PIP from high boiling components; 2) a section for separating EDA and PIP; 3) a section for separating MEOA and DETA from high boiling components; and 4) a section for separating AEEA from high boiling components.

[0196] Section c) for separating the value products consisted of several distillation columns designed as conventional distillation columns (comprising a reboiler, a condenser, a stripping section and a rectification section) or as dividing wall columns.

[0197] The appropriate separation equipment was made of stainless steel.

[0198] After two or three years of operation, several parts of section (3), which is for separating valuable products, had to be replaced due to severe corrosion.

[0199] In particular, equipment in the sumps of the appropriate columns used in sections 1), 2), and 3), such as reboilers, fittings and piping, as well as internals such as column packing, showed signs of corrosion.

[0200] Example 1: The corroded equipment items of the plant described in Comparative Example 1 were replaced with suitable equipment items made of duplex steel, and no substantial signs of corrosion were observed even after more than seven years of operation since the relevant equipment items were replaced.

[0201] Surprisingly, equipment items made of conventional stainless steel in an ethyleneamines manufacturing plant were found to be subject to significant corrosion after less than three years of operation. Replacement of these equipment items with equivalent equipment items made of duplex steel resulted in no substantial signs of corrosion being detected in operation, even after more than seven years of operation since replacement of the relevant equipment items.

Claims

1. 1. A process for the production of alkanolamines and / or the conversion of alkanolamines carried out on one or more items of equipment, wherein one or more steel components of said one or more items of equipment having one or more surfaces in contact with alkanolamines are made of duplex steel, meaning that a feature made of duplex steel consists of duplex steel.

2. The process for producing alkanolamine or the process for converting alkanolamine comprises: (i) a process for the production of alkanolamines which involves the conversion of an alkylene oxide with an aminating agent (the alkylene oxide process); (ii) a process for the production of alkanolamines, which comprises the conversion of a polyol with an aminating agent (polyol amination process); (iii) a process for the production of alkanolamines by conversion of hydroxyaldehydes or hydroxyketones with an aminating agent (reductive amination process); (iv) A process for producing alkanolamines by hydrogenation of amino acids (amino acid process); (v) processes for the conversion of alkanolamines with an aminating agent (alkanolamine amination); and (vi) the process of claim 1, wherein the ethanolamine functional compound is converted by a primary amine in the presence of a carbon delivery agent, the process being selected from the group consisting of alkanolamine conversion processes.

3. The polyol amination process comprises: (i) A process for the conversion of ethylene glycol with ammonia in the presence of an amination catalyst (MEG process); (ii) a process for the conversion of diethylene glycol with ammonia in the presence of an amination catalyst (DEG process); (iii) a process for the conversion of 1,2-propanediol or 1,3-propanediol with ammonia in the presence of an amination catalyst (PDO process); or (iv) a process for the conversion of polyglycols with ammonia in the presence of an amination catalyst (polyglycol amination); or The reductive amination process comprises: (v) a process for the conversion of glycolaldehyde with an aminating agent (GA process); or The alkanolamine amination process comprises: (vi) A process for the conversion of monoethanolamine with ammonia in the presence of an amination catalyst (MEOA process), (vii) A process according to claim 2, which is a process for the conversion of 1,2-propanolamine or 1,3-propanolamine with ammonia in the presence of an amination catalyst (MPOA process).

4. 4. The process of any one of claims 1 to 3, wherein one or more steel parts of the one or more major items of equipment having surfaces in contact with the alkanolamine are made of duplex steel.

5. 5. The process of claim 4, wherein all steel components of the one or more major items of equipment having one or more surfaces that come into contact with the alkanolamine are made of duplex steel.

6. 5. The process of claim 4, wherein one or more steel components of at least one or more auxiliary equipment items having one or more surfaces that come into contact with the alkanolamine are made of duplex steel.

7. 4. The process of any one of claims 1 to 3, wherein all steel parts of all items of equipment having one or more surfaces that come into contact with the alkanolamine are made of duplex steel.

8. 4. The process of any one of claims 1 to 3, wherein only steel components of all items of equipment having one or more surfaces in contact with the alkanolamine are made of duplex steel in contact with a liquid phase comprising hydrogen, the hydrogen concentration in said liquid phase being equal to or less than 0.1 percent by weight.

9. (i) in an alkylene oxide process, at least one steel component having one or more surfaces in contact with alkanolamine of at least one item of production equipment and at least one item of separation equipment is made of duplex steel; or (ii) The process of claim 8, wherein in the alkanol amination process, the MEG process, the DEG process, the polyglycol amination process, the GA process, the reductive amination process, and the amino acid process, the separation equipment is downstream of one or more hydrogen separation steps, and the hydrogen concentration in liquid phase 1 is reduced to the hydrogen concentration of claim 8.

10. 4. The process of any one of claims 1 to 3, wherein (i) only steel components of one or more items of equipment are made of duplex steel in contact with a liquid phase comprising an alkanolamine and water, and the concentration of water in the liquid phase is 10 weight percent or more, or (ii) only steel components of one or more items of equipment are made of duplex steel in contact with a liquid phase, and the hydrogen concentration is 0.1 weight percent or less.

11. 4. The process according to any one of claims 1 to 3, wherein the steel part in contact with the alkanolamine is further exposed to a temperature of at least 30°C and / or a pressure of from 10 mbar to 300 bar.

12. The process according to any one of claims 1 to 3, wherein the weight ratio of austenite to ferrite phases in the duplex steel is in the range of 30:70 to 70:

30.

13. The duplex steel is Chromium: 20 to 30 weight percent; Molybdenum: 0.1 to 5 weight percent; Nickel: 1 to 10 weight percent; Nitrogen: 0.05 to 0.5 weight percent The process according to any one of claims 1 to 3, comprising:

14. The process of any one of claims 1 to 3, wherein the duplex steel is of Unified Numbering System (UNS) designation S31803 or S3270.

15. 10. The process of claim 1, wherein the reaction effluent obtained by the method of claim 1 comprises at least one corrosive compound selected from the group consisting of (i) acids selected from the group consisting of formic acid, acetic acid, oxalic acid, glycolic acid, glyoxylic acid, propionic acid, and glycine, (ii) the corresponding ammonium salts of such acids, (iii) carbamic acid, and (iv) ammonium carbamate.

16. 16. The process of claim 15, wherein the concentration of the corrosive compounds is from 5 ppm to 500 ppm.

17. The process according to any one of claims 1 to 3, carried out under conditions in which the concentrations of oxygen and carbon dioxide are preferably each not more than 500 ppm.