Process for the removal of acid gases from a fluid stream

Abstract

process for removing acid gases from a fluid stream, wherein the fluid stream is brought into contact with an absorbent to obtain a treated fluid stream and a charged absorbent, the absorbent comprising at least one diluent and a compound of general formula (i): wherein r1 is c1-c3 alkyl; r2 is c1-c3 alkyl; r3 is selected from hydrogen and c1-c3 alkyl; r4 is selected from hydrogen and c1-c3 alkyl and en is an integer in the range of 1 to 4.

Description

1 / 33 “PROCESS FOR REMOVING ACID GASES FROM A FLUID STREAM” Field of invention

[001] The present invention relates to the use of an absorbent and a process for removing acidic gases from a fluid stream. In certain embodiments, the present invention relates to the selective removal of hydrogen sulfide from a fluid stream comprising carbon dioxide (CO2) and hydrogen sulfide (H2S). Background of the Invention

[002] The removal of acidic gases, for example CO2, H2S, SO2, CS2, HCN, COS or mercaptans, from fluid streams such as natural gas, refinery gas or synthesis gas, is desirable for several reasons. Sulfur compounds in natural gas tend to form corrosive acids, particularly along with the water often carried along by the natural gas. For the transport of natural gas in a pipeline or further processing in a natural gas liquefaction plant (LNG = liquefied natural gas), the limits given for sulfur-containing impurities must therefore be observed. In addition, several sulfur compounds are foul-smelling and toxic, even at low concentrations.

[003] Carbon dioxide must be removed from natural gas because a high concentration of CO2 reduces the calorific value of the gas. In addition, CO2 in combination with moisture can cause corrosion in pipes and valves.

[004] Known processes for removing acid gases include scrubbing operations with aqueous absorbent solutions of inorganic or organic bases. When acid gases are dissolved in the absorbent, ions are formed with the bases. The absorbent can be regenerated by decompression to a lower pressure and / or by separation, in which the Petition 870240077914, dated 11 / 09 / 2024, page 12 / 50 2 / 33 Ionic species react in reverse, and the acidic gases are released and / or removed by means of an inert fluid, for example, steam. After the regeneration process, the absorbent can be reused.

[005] A process in which CO2 and H2S are substantially removed is referred to as “total absorption.” While CO2 removal may be necessary to avoid corrosion problems and provide the required heating value for the consumer, it is occasionally necessary or desirable to treat acid gas mixtures containing CO2 and H2S to selectively remove H2S from the mixture while minimizing CO2 removal. Natural gas pipeline specifications, for example, set stricter limits on H2S levels than on CO2, since H2S is more toxic and corrosive than CO2. Common natural gas pipeline specifications typically limit H2S content to 4 ppmv with a more lenient limitation on CO2 to 2% by volume. Selective H2S removal is often desirable to enrich the H2S level in the feed for sulfur recovery, such as a downstream Claus plant.

[006] Severely sterically hindered secondary amines, such as 2-(2-tert-butylaminoethoxy)ethanol (TBAEE), and tertiary amines, such as methyldiethanolamine (MDEA), exhibit kinetic selectivity for H2S over CO2. These amines are therefore suitable for the selective removal of H2S over CO2 from gas mixtures comprising CO2 and H2S and are generally used as aqueous mixtures. These amines do not react directly with CO2; instead, CO2 reacts in a slow reaction with the amine and with water to give a bicarbonate ion. The kinetics of the reaction allow H2S to react directly, more rapidly, with the amine groups of the sorbent to form a hydrosulfide ion in aqueous solution.

[007] The use of hydroxyl-substituted amines (alkanolamines), such as those mentioned above, has become common since the presence Petition 870240077914, dated 11 / 09 / 2024, page 13 / 50 The presence of 3 / 33 of hydroxyl groups tends to improve the solubility of the absorbent and its acid gas reaction products in widely used aqueous solvent systems, thus facilitating solvent circulation through the conventional absorption tower / regeneration tower unit by suppressing phase separation. The presence of hydroxyl groups can also reduce amine volatility and consequently reduce amine losses during operation.

[008] This preference may, however, present its own problems in certain circumstances.

[009] While alkanolamines will effectively remove acid gases at higher pressures, the selectivity for H2S removal can be expected to decrease sharply due to both direct physical absorption of CO2 in the liquid solvent and reaction with the hydroxyl groups with the amine compound. Although CO2 reacts preferentially with the amino nitrogen, higher pressures force the reaction with the oxygens, and under higher pressures, the bicarbonate / hemicarbonate / carbonate reaction product(s) formed by the reaction at the hydroxyl site is stabilized with a progressive loss in H2S selectivity with increasing pressure.

[010] Furthermore, although the presence of hydroxyl groups improves the aqueous solubility of amines, hydroxyl groups tend to impart surfactant properties to the absorbent gas / acid reaction products, thus potentially causing problematic foaming phenomena during the operation of the gas treatment unit.

[011] Another known problem with using aqueous amine mixtures in the absorption treatment of gas mixtures is that multi-phase separation can occur at temperatures that fall within the regeneration temperature range for aqueous amine mixtures, which Petition 870240077914, dated 11 / 09 / 2024, page 14 / 50 4 / 33 generally lies in the range of 50 °C to 170 °C.

[012] US documents 4,487,967, 4,665,195 and 4,894,178 refer to a process for preparing sterically hindered amino ether alcohols, or di-amino-polyalkylene ethers, in the presence of a hydrogenation catalyst.

[013] US patent 2015 / 0027055 describes a process for selectively removing H2S from a CO2-containing gas mixture by means of an absorbent comprising sterically hindered terminal etherified alkanolamines. It has been found that terminal etherification of the alkanolamines and exclusion of water allow for greater H2S selectivity.

[014] US patent 2010 / 0037775 describes an acid gas absorbent comprising an alkylaminoalkylaxi(alcohol) monoalkyl ether and a process for the selective removal of H2S from gas mixtures containing H2S and CO2 using an absorbent solution comprising said monoalkyl ether.

[015] WO 2013 / 181245 describes an absorbent composition useful in the selective removal of H2S, wherein the absorbent composition includes an aqueous amine mixture of a tert-butylamine amination reaction product and a polyethylene glycol mixture, as well as a co-solvent, selected from sulfones, sulfone derivatives and sulfoxides, and a strong acid to inhibit phase separation.

[016] Document WO 2014 / 001664 discloses absorbent solutions made of tertiary diamines belonging to the hindered aminoethyl morpholine family. These compounds comprise only tertiary amino groups, each featuring a basic nitrogen atom.

[017] US patent 2013 / 011314 describes compounds containing one or more diamines whose two amine functions are not connected to each other by rings and whose amine function in the α position is always Petition 870240077914, dated 11 / 09 / 2024, page 15 / 50 5 / 33 tertiary and the amine function in the ω position is always primary or secondary and the use of such compounds in the selective removal of H2S from a gas containing H2S and CO2. The compounds described therein have a secondary amino group and a tertiary amino group, both of which have a basic nitrogen atom.

[018] Document WO 2017 / 186466 discloses a process for removing acid gases from a fluid stream with morpholine-based hindered amine compounds.

[019] Document WO 2018 / 146233 describes a process for removing acid gases from a fluid stream obtained from the reaction of glycidol derivatives with sterically hindered amines, such as tert-butylamine.

[020] Document WO 2019 / 043099 is directed to absorbent solutions derived from the reaction of tert-butylamine with hydroxyethylpyrrolidone and structurally related compounds and their use in gas treatment.

[021] US patent 2017 / 0320008 discloses a process for the selective removal of H2S from a gaseous mixture comprising H2S and CO2 by contacting the mixture with an absorbent comprising an amine, water and at least one C1-C4-thioalcohol. The disclosed process has high selectivity for the removal of H2S and also allows for enhanced removal of other sulfur components, in particular mercaptans.

[022] It is an object of the invention to provide other suitable processes for the removal of acid gases from fluid streams. The processes should be useful for total absorption applications, where CO2 and H2S are substantially removed, as well as for the selective removal of hydrogen sulfide from fluid streams. The absorbents used in the process should have high cyclic capacity and low volatility. Another object of the present invention was to provide a gas treatment process based on Petition 870240077914, dated 11 / 09 / 2024, page 16 / 50 6 / 33 solvents with improved thermal stability that can be operated at higher temperatures for a longer period of time. Another objective of the invention was to provide a gas treatment process with high selectivity for the removal of H2S from gas mixtures comprising H2S and CO2, which also allows the removal of other sulfur components that may additionally be included in gas mixtures comprising both H2S and CO2. In particular, the process of the present invention should also allow the removal of mercaptans in such a selective gas treatment process. Description of the Invention

[023] The objective is achieved by a process for removing acid gases from a fluid stream, in which the fluid stream is contacted with an absorbent to obtain a treated fluid stream and a charged absorbent, the absorbent comprising at least one diluent and a compound of general formula (I): R1 R3 where R1 is C1-C3 alkyl; R2 is C1-C3 alkyl; R3 is selected from hydrogen and C1-C3 alkyl; R4 is selected from hydrogen and C1-C3 alkyl and is an integer in the range of 1 to 4.

[024] The compounds of general formula (I) are based on thiodiglycol and its derivatives and comprise another functionality. Compared with prior art gas treatment solvents comprising oxy-ether functionalities, it was surprisingly found that the gas treatment process using solvents comprising compounds of formula (I) exhibits higher thermal stability while maintaining Petition 870240077914, dated 11 / 09 / 2024, page 17 / 50 7 / 33 favorable absorption properties. Absorbent:

[025] The process according to the invention is carried out in the presence of an absorbent.

[026] The absorbent comprises a compound of formula (I) and at least one diluent. Compound of Formula (I):

[027] The absorbent comprises a compound of formula (I).

[028] In formula (I), R1 is C1-C3 alkyl, preferably methyl, ethyl, propyl and isopropyl, and most preferably methyl; R2 is C1-C3 alkyl; preferably methyl, ethyl, propyl and isopropyl, and most preferably methyl; R3 is selected from hydrogen and C1-C3 alkyl groups, preferably methyl, ethyl, propyl and isopropyl, and most preferably methyl; R4 is selected from hydrogen and C1-C3 alkyl, preferably methyl, ethyl, propyl and isopropyl and most preferably methyl; en is an integer in the range of 1 to 4, preferably 1 or 2, and most preferably 1.

[029] In preferred embodiments, R1 and R2 are methyl and R3 is hydrogen; or R1, R2 and R3 are methyl; or R1 and R2 are methyl and R3 is ethyl. In a particularly preferred embodiment, R1, R2 and R3 are methyl.

[030] In a preferred embodiment, the compound of general formula (I) is selected from 2-[2-(tert-butylamino)ethylsulfanyl]ethanol; or N-[2-(2-methoxyethylsulfanyl)ethyl]-2-methyl-propan-2-amine; or N-[2-(2-ethoxyethylsulfanyl)ethyl]-2-methyl-propan-2-amine; or 2-[2(isopropylamino)ethylsulfanyl]ethanol; or N-[2-(2-methoxyethylsulfanyl)ethyl]propan-2-amine; or N-[2-(2-ethoxyethylsulfanyl)ethyl]propan-2-amine. Petition 870240077914, dated 11 / 09 / 2024, p. 18 / 50 8 / 33

[031] In the most preferred embodiment, the compound of general formula (I) is 2-[2-(tert-butylamino)ethylsulfanyl]ethanol.

[032] The absorbent preferably comprises 10% to 70% by weight, more preferably 15% to 65% by weight and most preferably 20% to 60% by weight of a compound of general formula (I), based on the total weight of the absorbent. Synthesis of compounds of formula (I):

[033] Compounds of formula (I) are commercially available or can be prepared in various ways.

[034] In a preferred embodiment, a compound of formula (I) is prepared by converting an amine of formula (II): R1 NH2(II); where R1 is C1-C3 alkyl; R2 is C1-C3 alkyl; R3 is selected from hydrogen and C1-C3 alkyl; with an alcohol of formula (III): R4 HO (IIII) where R4 is selected from hydrogen and C1-C3 alkyl; en is an integer in the range of 1 to 4; in the liquid phase and in the presence of a catalyst.

[035] Preferably, the amine of formula (II) is tert-butylamine or isopropylamine. More preferably, the amine of formula (II) is tert-butylamine.

[036] The alcohol of formula (III) is preferably 2-(2 Petition 870240077914, dated 11 / 09 / 2024, p. 19 / 50 9 / 33 hydroxyethylsulfanyl)ethanol (thiodiglycol), or 2-(2-methoxyethylsulfanyl)ethanol, or 2-(2ethoxyethylsulfanyl)ethanol.

[037] In the most preferred embodiment, the amine of formula (II) is tert-butylamine and the alcohol of formula (III) is thiodiglycol.

[038] In another embodiment, n equals 3 or 4 and R4 is methyl.

[039] Preferably, the molar ratio of amine of formula (II) to alcohol of formula (III) is in the range of 0.8:1 to 1.2:1, more preferably 0.9:1 to 1.1:1 and most preferably 1:1.

[040] Preferably, the reaction is carried out in the presence of a hydrogenation / dehydrogenation catalyst.

[041] Catalysts may, in principle, comprise nickel, cobalt, iron, copper, chromium, manganese, copper, molybdenum, tungsten and / or other metals from groups 8 and / or 9 and / or 10 and / or 11 of the periodic table of elements.

[042] Preference is given to the use of catalysts comprising at least one metal selected from the group consisting of Cu, Co, Ni, Pd, Pt, Ru, Rh, Ag, Au, Re and Ir.

[043] Preference is given to the use of catalysts comprising at least one metal selected from the group consisting of Cu, Co, Ni, Pd, Pt and Ru.

[044] The aforementioned catalysts can be doped in the usual way with promoters, for example, with chromium, iron, cobalt, manganese, molybdenum, titanium, tin, alkali metals, alkaline earth metals and / or phosphorus.

[045] The catalyst can be a supported or unsupported catalyst.

[046] Suitable support materials consist of Petition 870240077914, dated 11 / 09 / 2024, page 20 / 50 10 / 33 carbon, such as graphite, carbon black and / or activated carbon, aluminum oxide (gamma, delta, theta, alpha, kappa, chi or mixtures thereof), silicon dioxide, zirconium dioxide, zeolites, aluminosilicates or mixtures thereof.

[047] In a preferred embodiment of the invention, Raney-type catalysts are used.

[048] As Raney catalysts, cobalt Raney catalysts, nickel Raney catalysts and / or copper Raney catalysts are preferably used. Cobalt Raney catalysts are particularly preferred.

[049] In another preferred embodiment of the invention, the catalysts are prepared by reducing a catalyst precursor, in which the aforementioned metals are present in the form of compounds comprising oxygen, such as their oxides, carbonates or hydrogen carbonates.

[050] Catalyst precursors can be prepared by known processes, for example, by precipitation, precipitant application or impregnation.

[051] In a particularly preferred embodiment, a supported copper, nickel, and cobalt-containing hydrogenation / dehydrogenation catalyst is used, wherein the catalytically active material of the catalyst, prior to its reduction with hydrogen, comprises aluminum, copper, nickel, and cobalt oxygen compounds and in the range of 0.2 to 5.0 wt% of oxygenated tin compounds, calculated as SnO. In a preferred embodiment, a catalyst according to the catalysts claimed in WO 2011 / 067199 is used.

[052] In a preferred embodiment, the reaction is carried out at a temperature of 150 to 260 °C. In a particularly preferred embodiment, the reaction is carried out at a temperature of 170 to 240 °C. In a Petition 870240077914, dated 11 / 09 / 2024, page 21 / 50 11 / 33 In the most preferred embodiment, the reaction is carried out at a temperature of 180 to 220 °C.

[053] The reaction can be carried out at pressures of 5·10⁵ to 3·10⁷ Pa (5 to 300 bar). In a preferred embodiment, the reaction is carried out at a pressure of 5·10⁶ to 2·10⁷ Pa (50 to 200 bar (abs)). In a particularly preferred embodiment, the reaction is carried out at a pressure of 6·10⁶ to 1.3-10⁷ Pa (60 to 130 bar (abs)).

[054] The conversion of the amine of formula (II) and the alcohol of formula (III) is preferably carried out in the liquid phase. In the meaning of the present invention, the conversion is carried out in the liquid phase if the amine of formula (II), the alcohol of formula (III) or the solvent are in the liquid phase under the reaction conditions.

[055] The conversion is preferably carried out in the presence of hydrogen. During the reaction, hydrogen is not consumed, but it has beneficial effects in maintaining the activity of the catalyst. The partial pressure of hydrogen is preferably in the range of 2.5·10⁵ to 2·10⁷ Pa (2.5 to 200 bar), more preferably in the range of 5-10⁵ to 1.5-10⁷ Pa (5 to 150 bar), even more preferably in the range of 1-10⁶ to 1-10⁷ Pa (10 to 100 bar) and most preferably in the range of 2-10⁶ to 5-10⁶ Pa (20 to 50 bar).

[056] The conversion can be carried out in the presence of a solvent. The solvent used may be any solvent that is inert under the reaction conditions and has sufficient solubility for the reactants and products of the reaction. Useful solvents do not comprise functional groups that may react with amine of formula (II) under amination reaction conditions, for example, hydroxyl groups. Preferably, one or more solvents are water, ethers, preferably methyl tert-butyl ether, ethyl tert-butyl ether, dioxane, tetrahydrofuran (THF), proglymide, diglymide, polyglymides and in general diethers of oligo- and polypropylene oxides and oligo- and oxides of polyethylene or oligo- or oxides of Petition 870240077914, dated 11 / 09 / 2024, p. 22 / 50 12Z33 mixed polyalkylenes.

[057] Useful solvents also include suitable mixtures of the solvents listed above.

[058] Particularly preferred solvents are glyphs, THF and water.

[059] The amount of solvent present in the reaction mixture is generally in the range of 1 to 95% by weight, preferably 2.5 to 70%, more preferably 5 to 40%, based on the total weight of the reaction mixture, wherein the total weight of the reaction mixture is composed of the sum of the masses of all components added to the conversion of the amine of formula (II), that is, the amine of formula (II) and the alcohol of formula (III) and the solvents.

[060] The reaction can be carried out using stirred tank reactors, fixed-bed tube reactors and multi-tube reactors. It can be carried out in batch, semi-batch and continuous mode and with and without recycling of the crude reaction mixture. In a preferred embodiment, the reaction is carried out in continuous mode in a fixed-bed tube reactor.

[061] The catalyst charge may vary in the range of 0.01 to 2 kgZ(Lfi), preferably in the range of 0.1 to 1.0 kgZ(Lfi), and in a particularly preferred embodiment in the range of 0.2 to 0.8 kgZ(Lb) of ether of formula (II).

[062] The reaction product comprises unreacted amine of formula (II), alcohol of formula (III) and compound of formula (III).

[063] The reaction product is preferably refined by conducting one or more distillation steps.

[064] On a laboratory scale, compounds of formula (I) can also be obtained by reacting compounds of formula (IV): Petition 870240077914, dated 11 / 09 / 2024, page 23 / 50 13 / 33 (IV) wherein R4 is selected from hydrogen and C1-C3 alkyl; en is an integer in the range of 1 to 4, and 2-chloro-N-tert-butylethylamine hydrochloride in the presence of sodium ethanolate.

[065] In a typical laboratory synthesis, the compound of formula (IV) is dissolved in a 10% by weight solution of sodium methylate in ethanol. 2-Chloro-N-tert-butylethylamine is generally added as a 5 to 10% by weight solution in ethanol. The mixing is generally conducted so that the temperature of the resulting mixture is maintained in a range of 35 to 40 °C. To complete the reaction, the resulting reaction mixture is typically stirred at 75 °C for 90 minutes for a further 6 to 12 hours at room temperature.

[066] Preferably, the reaction is carried out under inert conditions, such as a nitrogen atmosphere and using dry solvents. The resulting suspension is generally filtered through a laboratory filter and the filtrate is evaporated in a rotary evaporator to remove the ethanol and obtain the desired products. Diluent

[067] The compound of general formula (I) is diluted with a diluent, preferably a low-cost diluent. The diluent may be one that has only physical absorptivity for carbon dioxide and other gas constituents, such as H2S. Preferably, however, the diluent interacts with the acid-base chemistry of the process. In particular, the diluent is an aqueous diluent. Due to their steric hindrance, compounds of general formula (I) do not have a sufficiently nucleophilic amine site for a direct nucleophilic attack on the CO2 molecule. Thus, the oxygen from the water acts as the nucleophile forming Petition 870240077914, dated 11 / 09 / 2024, page 24 / 50 14 / 33 a Bronsted acid, H2CO3, which is neutralized by the compound of general formula (I) acting as a Bronsted base to form an ammonium bicarbonate.

[068] In the most preferred embodiment, the diluent is water. Activator

[069] In a preferred embodiment, the absorbent comprises at least one activator selected from a sterically unhindered primary amine and / or a sterically unhindered secondary amine. A sterically unhindered primary amine is understood to mean compounds possessing primary amino groups to which only one primary or secondary carbon atom is attached. A sterically unhindered secondary amine is understood to mean compounds possessing secondary amino groups to which only primary carbon atoms are attached. Sterically unhindered primary amines or sterically unhindered secondary amines act as strong activators of CO2 absorption. Consequently, the presence of an activator may be desirable in applications aimed at the non-selective removal of acid gases or applications in which CO2 removal is especially important.

[070] The activator preferably does not comprise acidic groups, such as, in particular, phosphonic acid, sulfonic acid and / or carboxylic acid groups.

[071] The activator is, for example, selected from: alkanolamines, such as monoethanolamine (MEA), diethanolamine (DEA), ethylaminoethanol, 1-amino-2-methylpropan-2-ol, 2-amino-1-butanol, 2-(2aminoethoxy)ethanol and 2-(2-aminoethoxy)ethanamine, and polyamines, such as hexamethylenediamine, 1,4-diaminobutane, 1,3-diaminopropane, 3-(methylamino)propylamine (MAPA), N-(2hydroxyethyl)ethylenediamine, 3-(dimethylamino)propylamine (DMAPA), 3Petition 870240077914, of 09 / 11 / 2024, p. 25 / 50 15 / 33 (diethylamino)propylamine, N,N'-bis(2-hydroxyethyl)ethylenediamine.

[072] Saturated heterocycles of 5, 6 or 7 members having at least one NH group in the ring, which may comprise one or two other heteroatoms selected from nitrogen and oxygen in the ring, such as piperazine, 2-methylpiperazine, N-methylpiperazine, N-ethylpiperazine, N-(2-hydroxyethyl)piperazine, N-(2-aminoethyl)piperazine, homopiperazine, piperidine and morpholine.

[073] Particular preference is given to saturated heterocycles of 5, 6 or 7 members having at least one NH group in the ring, which may comprise one or two other heteroatoms selected from nitrogen and oxygen in the ring. Very particular preference is given to piperazine.

[074] In this preferred embodiment in which the absorbent comprises an activator, the absorbent preferably comprises 10% to 70% by weight, more preferably 15% to 65% by weight and most preferably 20% to 60% by weight of an activator. Absence of sterically unimpeded amines

[075] In another preferred embodiment, the absorbent does not comprise any sterically unhindered primary amine or sterically unhindered secondary amine. Since sterically unhindered primary amines or sterically unhindered secondary amines act as strong activators of CO2 absorption, their presence in the absorbent can result in a loss of the absorbent's H2S selectivity. Consequently, in applications where high H2S selectivity is desirable, an absorbent essentially free of such compounds is preferable. Additional sterically hindered amines

[076] In one embodiment, the absorbent comprises a tertiary amine or a primary amine that is severely sterically obstructed. Petition 870240077914, dated 11 / 09 / 2024, page 26 / 50 16 / 33 and / or severely sterically hindered secondary amine other than compounds of general formula (I). Severe steric hindrance is understood to mean a tertiary carbon atom directly adjacent to a primary or secondary nitrogen atom. In this embodiment, the absorbent comprises the tertiary amine or severely sterically hindered amine other than compounds of general formula (I) generally in an amount of 5% to 50% by weight, preferably 10% to 40% by weight and more preferably 20% to 40% by weight, based on the total weight of the absorbent.

[077] 1. Tertiary alkanolamines, such as: bis (2-hydroxyethyl) methylamine (methyldiethanolamine, MDEA), tris (2hydroxyethanol) amine (triethanolamine, TEA), tributanolamine, 2-diethylaminoethanol (diethylethanolamine, DEEA), 2-dimethylaminoethanol (dimethylethanolamine, DMEA), 3-dimethylamino-1-propanol (N,N-dimethylpropanolamine), 3-diethylamino-1-propanol, 2-diisopropylaminoethanol (DIEA), N,N-bis(2-hydroxypropyl) methylamine (methyldiisopropanolamine, MDIPA).

[078] 2. Tertiary amino ethers, such as: 3-methoxypropyldimethylamine.

[079] 3. Tertiary polyamines, for example bis-tertiary diamines, such as: Ν,Ν,Ν',Ν'-tetramethylethylenediamine, N,Ndiethyl-N', N'-dimethylethylenediamine, Ν,Ν,Ν',Ν'-tetraethylethylenediamine, N,N,N', N'-tetramethyl-1,3propanediamine (TMPDA), N,N,N',N'-tetraethyl-1,3-propanediamine (TEPDA) tetramethyl1,6-hexanediamine; and mixtures thereof.

[080] Tertiary alkanolamines, that is, amines with at least one hydroxyalkyl group attached to the nitrogen atom, are generally Petition 870240077914, dated 11 / 09 / 2024, page 27 / 50 17 / 33 preferred. Particular preference is given to methyldiethanolamine (MDEA).

[081] The severely hindered sterically suitable amines (i.e., amines with a tertiary carbon atom directly adjacent to a primary or secondary nitrogen atom), except for compounds of general formula (I), include especially: 1. Severely stereochemically inhibited secondary alkanolamines, such as: 2-(2-tert-butylaminoethoxy)ethanol (TBAEE), 2-(2-tert-butylamino)propoxyethanol, 2-(2-tert-amylaminoethoxy)ethanol, 2-(2-(1-methyl-1-ethylpropylamino)ethoxy)ethanol, 2-(tert-butylamino)ethanol, 2-tert-butylamino-1propanol, 3-tert-butylamino-1-propanol, 3-tert-butylamino-1-butanol and 3-aza-2,2-dimethylhexane-1,6-diol; 2. Primary alkanolamines that are severely sterically inhibited, such as: 2-amino-2-methylpropanol (2-AMP); 2-amino-2-ethylpropanol; and 2amino-2-propylpropanol; 3. Severely sterically hindered aminoethers such as: 1,2-bis(tert-butylaminoethoxy)ethane, bis(tert-butylaminoethyl)ether; and mixtures thereof; Severely sterically hindered secondary alkanolamines are generally preferred; and Particular preference is given to 2-(2-tert-butylaminoethoxy)ethanol and 2N-methylamino-2-methylpropan-1-ol. ACIDS

[082] In another preferred embodiment, the absorbent is an aqueous absorbent (meaning that the diluent comprises water) and the absorbent further comprises an acid.

[083] The acid helps regenerate the absorbent at low loads and Petition 870240077914, dated 11 / 09 / 2024, p. 28 / 50 18 / 33 increases the efficiency of the process. A protonation equilibrium is formed between the acid and the compound of general formula (I). The equilibrium position is temperature dependent, and the equilibrium is shifted at higher temperatures towards the free oxonium ion and / or amine salt having the lower protonation enthalpy. At relatively low temperatures, as prevail in the absorption step, the higher pH promotes the efficient absorption of acid gases, whereas at relatively high temperatures, as prevail in the desorption step, the lower pH supports the release of the absorbed acid gases.

[084] The acid preferably has a pKa less than 6, especially less than 5, measured at 25 °C at atmospheric pressure. In the case of acids with more than one dissociation stage and, consequently, more than one pKa, this requirement is met when one of the pKa values ​​is within the specified range. The acid is suitably selected from protic acids (Bronsted acids).

[085] The acid is preferably added in an amount such that the pH of the aqueous solution measured at 120 °C is from 7.9 to less than 9.5, preferably 8.0 to less than 8.8, more preferably 8.0 to less than 8.5, more preferably 8.0 to less than 8.2.

[086] The amount of acid, in one embodiment, is from 0.1% to 5.0% by weight, preferably 0.2% to 4.5% by weight, more preferably 0.5% to 4.0% by weight and most preferably 1.0% to 2.5% by weight, based on the total weight of the absorbent.

[087] The acid is selected from organic and inorganic acids. Suitable organic acids include, for example, phosphonic acids, sulfonic acids, carboxylic acids, and amino acids. In particular embodiments, the acid is a polybasic acid.

[088] Suitable acids include, for example: mineral acids, such as hydrochloric acid, sulfuric acid, Petition 870240077914, dated 11 / 09 / 2024, page 29 / 50 19 / 33 starch sulfuric acid, phosphoric acid, partial esters of phosphoric acid, for example, mono- and dialkyl phosphates and mono- and diaryl phosphates, such as tridecyl phosphate, dibutyl phosphate, diphenyl phosphate and (2-ethylhexyl) phosphate; boric acid; carboxylic acids, for example, saturated aliphatic monocarboxylic acids, such as formic acid, acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, isovaleric acid, pivalic acid, caproic acid, n-heptanoic acid, caprylic acid, 2-ethylhexanoic acid, pelargonic acid, acid caproic, neodecanoic acid, undecanoic acid, lauric acid, tridecanoic acid, myristic acid, pentadecanoic acid, palmitic acid, margaric acid, stearic acid, isostaric acid, aracic acid, beênic acid; saturated aliphatic polycarboxylic acids, such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid; mono- and polycarboxylic cycloaliphatic acids, such as cyclohexanecarboxylic acid, hexahydrophthalic acid, tetrahydrophthalic acid, resin acids, naphthenic acids;aliphatic hydroxycarboxylic acids, such as glycolic acid, lactic acid, mandelic acid, hydroxybutyric acid, tartaric acid, malic acid, citric acid; halogenated aliphatic carboxylic acids, such as trichloroacetic acid or 2-chloropropionic acid; aromatic mono- and polycarboxylic acids, such as benzoic acid, salicylic acid, gallic acid, positionally isomeric toluic acids, methoxybenzoic acid, chlorobenzoic acid, nitrobenzoic acid, phthalic acid, terephthalic acid, isophthalic acid; mixtures of technical carboxylic acids, for example, versatic acids; Sulfonic acids, such as methylsulfonic acid, butylsulfonic acid, 3-hydroxypropylsulfonic acid, sulfoacetic acid, benzenesulfonic acid, p-toluenesulfonic acid, p-xylenesulfonic acid, 4-dodecylbenzenesulfonic acid, 1-naphthalenesulfonic acid, dinonylnaphthalenesulfonic acid and dinonylnaphthalenesulfonic acid - or nonafluoro-n-butylsulfonic acid, camphorsulfonic acid, 2-(4-(2-hydroxyethyl)-1-piperazinyl)ethanesulfonic acid (HEPES); and Petition 870240077914, dated 11 / 09 / 2024, page 30 / 50 20 / 33 organic phosphonic acids, for example, phosphonic acids of formula (IV): R4-PO3H (IV) wherein R4 is C1-18 alkyl optionally substituted by up to four substituents independently selected from carboxyl, carboxamide, hydroxyl and amino.

[089] These include alkylphosphonic acids, such as methylphosphonic acid, propylphosphonic acid, 2-methylpropylphosphonic acid, t-butylphosphonic acid, n-butylphosphonic acid, 2,3-dimethylbutylphosphonic acid, octylphosphonic acid; hydroxyalkylphosphonic acids, such as hydroxymethylphosphonic acid, 1-hydroxyethylphosphonic acid, 2-hydroxyethylphosphonic acid;arylphosphonic acids, such as phenylphosphonic acid, tolylphosphonic acid, xylphosphonic acid; amino alkylphosphonic acids, such as aminomethylphosphonic acid, 1-aminoethylphosphonic acid, 1-dimethylaminoethylphosphonic acid, 2-aminoethylphosphonic acid, 2-aminopropylphosphonic acid, 1-aminopropylphosphonic acid, 1-aminopropyl-2-chloropropylphosphonic acid, 2-aminobutylphosphonic acid, 3-aminobutylphosphonic acid, 1-aminobutylphosphonic acid, 4-aminobutylphosphonic acid, 4-aminobutylphosphonic acid, 2-aminopentylphosphonic acid, 5-aminopentylphosphonic acid, 2-aminohexylphosphonic acid, 5-aminohexylphosphonic acid. 2-aminooctylphosphonic acid, 1-aminooctylphosphonic acid, 1-aminobutylphosphonic acid; amidoalkylphosphonic acids, such as 3-hydroxymethylamino-3-oxopropylphosphonic acid; and phosphonocarboxylic acids, such as 2-hydroxyphosphonoacetic acid and 2-phosphonobutane-1,2,4-tricarboxylic acid; phosphonic acids of formula (V): PO3H2 R5--Q PO3H2 (V) Petition 870240077914, dated 11 / 09 / 2024, page 31 / 50 21 / 33 where R5 is H or C1-5 alkyl, Q is H, OH or NR62 and R6 is H or CH2PO3H2, such as 1-hydroxyethane-1,1-diphosphonic acid; phosphonic acids of formula (VI): Y (VI) wherein Z is C2-5 alkylene, cycloalkanediyl, phenylene, or C2-5 alkylene interrupted by cycloalkanediyl or phenylene, Y is CH2PO3H2 where is 0 to 4, such as ethylenediaminetetra(methylenephosphonic acid), diethylenetriaminepenta(methylenephosphonic acid) and bis(hexamethylene)triaminepenta-(methylenephosphonic acid); phosphonic acids of formula (VII): R7-NY2 (VII) wherein R7 is C1-5 alkyl, C2-5-hydroxyalkyl or R8, and R8 is CH2PO3H2, such as nitrilotris(methylenephosphonic acid) and 2-hydroxyethylimiminobis(methylenephosphonic acid); Aminocarboxylic acids having tertiary amino groups or amino groups having at least one secondary or tertiary carbon atom immediately adjacent to the amino group, such as: α-amino acids having tertiary amino groups or amino groups having at least one secondary or tertiary carbon atom immediately adjacent to the amino group, such as N,N-dimethylglycine (dimethylaminoacetic acid), N,N-diethylglycine, alanine (2-aminopropionic acid), N-methylalanine (2-(methylamino)propionic acid), N,N-dimethylalanine, N-ethylalanine, 2-methylalanine (2-aminoisobutyric acid), leucine (2-amino-4-methylpentanoic acid), N-methylleucine, N,N-dimethylleucine, isoleucine (1-amino-2-methylpentanoic acid), N-methylisoleucine, N,N-dimethylisoleucine, valine (2-aminoisovaleric acid), α-methylvaline (2-amino-2-methylisovaleric acid), N-methylvaline Petition 870240077914, dated 11 / 09 / 2024, page 32 / 50 22 / 33 (2-methylaminoisovaleric acid), N,N-dimethylvaline, proline (pyrrolidine-2-carboxylic acid), N-methylproline, N-methylserine, N,N-dimethylserine, 2-(methylamino)isobutyric acid, piperidine-2-carboxylic acid, N-methylpiperidine-2-carboxylic acid, β-amino acids having tertiary amino groups or amino groups having at least one secondary or tertiary carbon atom immediately adjacent to the amino group, such as 3-dimethylaminopropionic acid, N-methyliminodipropionic acid, N-methylpiperidine-3-carboxylic acid, γ-amino acids having tertiary amino groups or amino groups having at least one secondary or tertiary carbon atom immediately adjacent to the amino group, such as 4-dimethylaminobutyric acid, or aminocarboxylic acids having tertiary amino groups or amino groups having at least one secondary or tertiary carbon atom immediately adjacent to the amino group, such as N-methylpiperidine-4-carboxylic acid.

[090] Among inorganic acids, phosphoric acid and sulfuric acid are preferred, especially sulfuric acid.

[091] Among carboxylic acids, preference is given to formic acid, acetic acid, benzoic acid, succinic acid and adipic acid.

[092] Among sulfonic acids, preference is given to methanesulfonic acid, p-toluenesulfonic acid and 2-(4-(2-hydroxyethyl)-1-piperazinyl)ethanesulfonic acid (HEPES).

[093] Among the phosphonic acids, preference is given to 2-hydroxyphosphonoacetic acid, 2-phosphonobutane-1,2,4-tricarboxylic acid, 1-hydroxyethane-1,1-diphosphonic acid, ethylenediaminetetra (methylenephosphonic acid), diethylenetriaminepenta (methylenephosphonic acid), bis(hexamethylene)triaminepenta (methylenephosphonic acid) (HDTMP) and nitrilotris (methylenephosphonic acid), among which 1-hydroxyethane-1,1-diphosphonic acid is Petition 870240077914, dated 11 / 09 / 2024, page 33 / 50 23 / 33 particularly preferred.

[094] Among aminocarboxylic acids possessing tertiary amino groups or amino groups possessing at least one secondary or tertiary carbon atom immediately adjacent to the amino group, preference is given to N,N-dimethylglycine and N-methylalanine.

[095] More preferably, the acid is an inorganic acid. Non-Aqueous Organic Solvent

[096] In one embodiment, the absorbent diluent comprises at least one non-aqueous organic solvent. In particular cases, the diluent contains only a limited amount of water, or essentially no water other than the non-aqueous organic solvent. It may be desirable to limit the water content of the absorbent, for example, to a maximum of 20% by weight, alternatively to a maximum of 10% by weight, preferably to a maximum of 5% by weight, or a maximum of 2% by weight.

[097] The non-aqueous organic solvent is preferably selected from: C4-C10 alcohols, such as n-butanol, n-pentanol, and n-hexanol; ketones, such as cyclohexanone; esters such as ethyl acetate and butyl acetate; lactones, such as y-butyrolactone, o-valerolactone and ecaprolactone; amides, such as tertiary carboxamides, for example N,N-dimethylformamide; or N-formylmorpholine and N-acetylmorpholine; lactams, such as γ-butyrolactam, o-valerolactam, ecaprolactam, and N-methyl-2-pyrrolidone (NMP); sulfones, such as sulfolan; sulfoxides, such as dimethyl sulfoxide (DMSO); Glycols, such as ethylene glycol (EG) and propylene glycol; Petition 870240077914, dated 11 / 09 / 2024, p. 34 / 50 24 / 33 polyalkylene glycols, such as diethylene glycol (DEG) and triethylene glycol (TEG); di- or mono (C1-C4 alkyl ether)glycols, such as ethylene glycol dimethyl ether; di- or mono (C1-C4 alkyl ether)polyalkylene glycols, such as diethylene glycol dimethyl ether, dipropylene glycol monomethyl ether and triethylene glycol dimethyl ether; cyclic ureas, such as N,N-dimethylimidazolidin-2-one and dimethylpropylene urea (DMPU); Thioalkanols, such as ethylenedithioethanol, thiodiethylene glycol (thiodiglycol, TDG), and methylthioethanol; and mixtures thereof.

[098] More preferably, the non-aqueous solvent is selected from sulfones, glycols and polyalkylene glycols. More preferably, the non-aqueous solvent is selected from sulfones. A preferred non-aqueous solvent is sulfolane. Other additives

[099] The absorbent may also comprise additives, such as corrosion inhibitors, enzymes, antifoaming agents, etc. In general, the amount of such additives is in the range of about 0.005% to 3%, based on the total weight of the absorbent. Uses of sanitary pads

[0100] The present invention also relates to the use of the absorbent described herein for the removal of acidic gases from a fluid stream.

[0101] In one embodiment, the present invention relates to the use of the absorbent described herein for the non-selective removal of acid gases from a fluid stream. In this case, it is preferred that the absorbent comprise at least one activator selected from a primary amine. Petition 870240077914, dated 11 / 09 / 2024, page 35 / 50 25 / 33 sterically unhindered and / or a sterically unhindered secondary amine, as described above.

[0102] In another embodiment, the present invention relates to the use of the absorbent described herein for the selective removal of hydrogen sulfide from a fluid stream comprising carbon dioxide and hydrogen sulfide. In this case, it is preferred that the absorbent does not comprise any sterically unhindered primary amine or sterically unhindered secondary amine.

[0103] In one embodiment, the process is a process for the non-selective removal of acid gases from a fluid stream. In this case, it is preferred that the absorbent comprise at least one activator selected from a sterically unhindered primary amine and / or a sterically unhindered secondary amine, as described above.

[0104] In another embodiment, the process is a process for the selective removal of hydrogen sulfide from a fluid stream comprising carbon dioxide and hydrogen sulfide. In this case, it is preferred that the absorbent does not comprise any sterically unhindered primary amine or sterically unhindered secondary amine.

[0105] In the present context, “selectivity for hydrogen sulfide” is understood to mean the value of the following quotient: [mol (H2S) / mol (CO2)]liquid phase / [mol (H2S) / mol (CO2)]gas phase where [mol (H2S) / mol (CO2)]liquid phase is the molar ratio of H2S / CO2 in a liquid phase that is in contact with a gas phase; and where [mol (H2S) / mol (CO2)]gas phase is the molar ratio of H2S / CO2 in the gas phase.

[0106] In a standard gas purification process, the liquid phase is the absorbent loaded at the bottom of the absorber and the gas phase is the fluid stream to be treated. Petition 870240077914, dated 11 / 09 / 2024, page 36 / 50 26 / 33

[0107] A process is understood to be selective for H2S when the value of the above quotient is greater than 1. When the process is a process for the selective removal of hydrogen sulfide from a fluid stream comprising carbon dioxide and hydrogen sulfide, the selectivity for hydrogen sulfide is preferably at least 1.1, even more preferably at least 2, and most preferably at least 4.

[0108] The absorbent described herein is suitable for the treatment of all types of fluids. The fluids are, firstly, gases such as natural gas, synthesis gas, coke oven gas, cracking gas, coal gasification gas, cycle gas, landfill gases and combustion gases and, secondly, liquids that are essentially immiscible with the absorbent, such as LPG (liquefied petroleum gas) or NGL (natural gas liquids). The process of the invention is particularly suitable for the treatment of hydrocarbon fluid streams. The hydrocarbons present are, for example, aliphatic hydrocarbons such as C1-C4 hydrocarbons, such as methane, unsaturated hydrocarbons such as ethylene or propylene, or aromatic hydrocarbons such as benzene, toluene or xylene.

[0109] The absorbent of the invention is suitable for the removal of acidic gases, for example, CO2, H2S, SO3, SO2, CS2, HCN, COS and mercaptans. It is also possible that other acidic gases are present in the fluid stream, such as COS and mercaptans.

[0110] The absorbent is suitable for the selective removal of hydrogen sulfide from a fluid stream comprising carbon dioxide and hydrogen sulfide and allows for high selective H2S cleanup at low solvent circulation rates. The absorbent is useful in sulfur plant waste gas treatment unit (TGTU) applications, in acid gas enrichment (AGE) processes to upgrade poor acid waste gas from treatment units for plant feed. Petition 870240077914, dated 11 / 09 / 2024, page 37 / 50 27 / 33 high quality, or for the treatment of associated tied gases and refinery gases.

[0111] In the invention process, the fluid stream is contacted with the absorbent in an absorption step in an absorber, as a result of which carbon dioxide and hydrogen sulfide are at least partially eliminated. This gives a fluid stream depleted of CO2 and H2S and an absorbent loaded with CO2 and H2S.

[0112] The absorber used is a scrubbing apparatus used in typical gas scrubbing processes. Suitable scrubbing apparatuses are, for example, random packings, columns with structured packings and with trays, membrane contactors, radial flow scrubbers, jet scrubbers, Venturi scrubbers and rotary spray scrubbers, preferably columns with structured packings, having random packings and having trays, more preferably columns with trays and random packings. The fluid stream is preferably treated with the absorbent in a countercurrent column. The fluid is generally fed in the lower region and the absorbent in the upper region of the column. Installed in tray columns are sieve trays, bubble cap trays or valve trays, over which the liquid flows. Columns with random packings can be filled with bodies of different shapes.Heat and mass transfer is improved by the increased surface area caused by the molded bodies, which are generally about 25 to 80 mm in size. Well-known examples are the Raschig ring (a hollow cylinder), Pali ring, Hiflow ring, Intalox saddle, and similar items. Random packings can be introduced into the column in an ordered manner, or randomly (like a bed). Possible materials include glass, ceramics, metal, and plastics. Structured packings are a further development of ordered random packings. They have a... Petition 870240077914, dated 11 / 09 / 2024, page 38 / 50 28 / 33 regular structure. This makes it possible, in the case of gaskets, to reduce pressure drops in the gas flow. There are several models of structured packaging, for example, woven packaging or foil packaging. The materials used can be metal, plastic, glass, and ceramic.

[0113] The absorbent temperature in the absorption stage is generally around 30 to 100 °C, and when a column is used it is, for example, 30 to 70 °C at the top of the column and 50 to 100 °C at the bottom of the column.

[0114] The invention process may comprise one or more, especially two, successive absorption stages. Absorption may be conducted in a plurality of successive component stages, in which case the raw gas comprising the acid gas constituents is brought into contact with a subflow of the absorbent in each of the component stages. The absorbent with which the raw gas is contacted may already be partially loaded with acid gases, meaning that it may, for example, be an absorbent that has been recycled from a downstream absorption stage to the first absorption stage, or be a partially regenerated absorbent. With regard to the two-phase absorption performance, reference is made to publications EP 0 159 495, EP 0 190 434, EP 0 359 991 and WO 00 / 100271.

[0115] A person skilled in the art can achieve a high level of hydrogen sulfide removal with a defined selectivity by varying the conditions in the absorption step, such as, more particularly, the absorbent / fluid flow ratio, the absorber column height, the type of internal contact-promoting components in the absorber, such as random packing, trays or structured packing, and / or the residual load of the regenerated absorbent. Because CO2 is absorbed more slowly than H2S, more CO2 is absorbed at a longer residence time than at a shorter residence time. Conversely, at longer residence times, the Petition 870240077914, dated 11 / 09 / 2024, page 39 / 50 29 / 33 H2S selectivity is reduced. A taller column, therefore, results in less selective absorption. Structured trays or packaging with relatively high liquid retention also lead to less selective absorption. The heating energy introduced during regeneration can be used to adjust the residual load of the regenerated absorbent. A lower residual load of regenerated absorbent leads to better absorption.

[0116] The process preferably comprises a regeneration step in which the absorbent loaded with CO2 and H2S is regenerated. In the regeneration step, CO2 and H2S and, optionally, other constituents of acid gases are released from the CO2 and H2S loaded absorbent to obtain a regenerated absorbent. Preferably, the regenerated absorbent is subsequently recycled to the absorption step. In general, the regeneration step comprises at least one of the measures of heating, decompression and removal with an inert fluid.

[0117] The regeneration step preferably comprises heating the absorbent loaded with the constituents of the acid gas, for example, by means of a boiler, natural circulation evaporator, forced circulation evaporator or forced circulation flash evaporator. The absorbed acid gases are removed by means of the steam obtained by heating the solution. Instead of steam, an inert fluid such as nitrogen can also be used. The absolute pressure in the desorbent is normally 1·10⁴ to 3.5-10⁵ Pa (0.1 to 3.5 bar), preferably 1·10⁵ to 2.5·10⁵ Pa (1.0 to 2.5 bar). The temperature is normally 50 °C to 170 °C, preferably 80 °C to 130 °C, the temperature being obviously dependent on the pressure. In some cases, an additional regeneration step of a slip stream of the regenerated absorption solvent is necessary. In the presence of SOx, NOx, and CO in the fluid stream, heat-stable salts such as sulfates, nitrates, and formates can be formed.To reduce the concentration of these components. Petition 870240077914, dated 11 / 09 / 2024, pages 40 / 50 30 / 33 undesirable, an additional distillation step at elevated temperatures can be applied or, alternatively, the heat-stable salts can be removed by the ion exchange process.

[0118] The regeneration stage may alternatively or additionally comprise decompression. This includes at least one decompression of the absorber under load from a high pressure, as exists in the conductive absorption stage, to a lower pressure. Decompression may be carried out, for example, by means of a butterfly valve and / or a decompression turbine. Regeneration with a decompression stage is described, for example, in US Publications 4,537,753 and 4,553,984.

[0119] The constituents of the acid gas can be released in the regeneration stage, for example, in a decompression column, for example, a flash vessel installed vertically or horizontally, or a countercurrent column with internals.

[0120] The regeneration column can also be a column with random packing, with structured packing or with trays. The regeneration column has a heater at the bottom, for example, a forced circulation evaporator with a circulation pump. At the top, the regeneration column has an outlet for the released acid gases. The vapors from the retained absorption medium are condensed in a condenser and recirculated to the column.

[0121] It is possible to connect a plurality of decompression columns in series, in which regeneration is carried out at different pressures. For example, regeneration can be carried out in a preliminary decompression column at a high pressure, typically about 1.5 x 10⁵ Pa (1.5 bar) above the partial pressure of the acid gas constituents in the absorption stage, and in a main decompression column at a low pressure. Petition 870240077914, dated 11 / 09 / 2024, page 41 / 50 31 / 33 pressure, for example, 1·105 to 2·105 Pa (1 to 2 bar) absolute. Regeneration with two or more stages of decompression is described in US publications 4,537,753, US 4,553,984, EP 0 159 495, EP 0 202 600, EP 0 190 434 and EP 0 121 109.

[0122] The process of the present invention using compounds of formula (I) shows high selectivity in the treatment of gas streams comprising H2S and CO2. The process of the present invention additionally allows a high removal rate of mercaptans or other sulfur compounds that may be present in such gas streams. The compounds of formula (i) exhibit high thermal stability, allowing regeneration at higher temperatures and more complete regeneration of the absorbent solutions for lower load factors. Examples

[0123] The invention is illustrated in detail by the following examples. Example 1: Preparation of 2-[2-(tert-butylamino)ethylsulfanyl]ethanol

[0124] 1,7 of sodium methylate were dissolved in 15 ml of dry ethanol. Mercaptoethanol was added to the solution with stirring. After mixing was complete, the mixture was stirred for a further 15 minutes, and a solution of 2.5 g of 2-chloro-N-tert-butylethylamine hydrochloride dissolved in 50 ml of dry ethanol was added dropwise to maintain a temperature in the range of 35 to 40 °C. After the mixing process was complete, the resulting suspension was heated to 75 °C and stirred for a further 90 minutes. After overnight stirring at room temperature, the suspension was filtered and the filtrate was evaporated at 90 °C and 6^103 Pa (60 mbar) in a rotary evaporator.

[0125] 2.5 g of 2-[2-(tert) Petition 870240077914, dated 11 / 09 / 2024, pp. 42 / 50 32 / 33 butylamino)ethylsulfanyl]ethanol. The yield was calculated to be 97%. The structure of the compound was confirmed by 1H-NMR. Example 2: Comparison of the properties of 2-[2-(tert-butylamino)ethylsulfanyl]ethanol (TBAESE) and 2-[2-(tert-butylamino)ethoxy]ethanol (TBAEE) a) Thermal stability

[0126] The thermal stability of TBAESE was compared to TBAEE and MDEA with and without acid gas loading.

[0127] A cylinder (10 mL) was initially loaded with the respective solution (8 mL) and the cylinder was closed. The cylinder was heated to 150 °C for 125 h. In the experiments conducted under acid gas loading, the acid gas loading of the solutions was 20 Nm3 / tsolvent of CO2 and 20 Nm3 / tsolvent of H2S. The level of amine decomposition was calculated from the amine concentration measured by gas chromatography before and after the experiment. The results are shown in Table 1. Table 1 Aqueous Solution Degradation Ratio Without Acid Gas Charge With Acid Gas Charge 40% by weight MDEA + 60% by weight H2O * 0.98 0.89 30% by weight TBAEE + 70% by weight H2O * 0.99 0.92 20% by weight TBAESE + 75% by weight H2O 0.99 0.96 * comparative example

[0128] It is evident that TBAESE has superior thermal stability to MDEA and TBAEE in aqueous solutions in the presence of an acid gas charge. b) Charging and regeneration of acid gas

[0129] pKa values ​​for TBAESE and TBAEE were measured Petition 870240077914, dated 11 / 09 / 2024, pp. 43 / 50 33 / 33 in the temperature range between 20 °C and 120 °C. The results are shown in Figure 1. For this, an aqueous solution of the amine with a concentration of 0.01 mol / l was neutralized to 50% by a 0.005 mol / l HCl solution. Thus, the measured pH of the 50% neutralized amine solution is equal to the pKa value of the amine.

[0130] The measurement was performed in a glass vessel pressurized with nitrogen to prevent any loss of water and solvent.

[0131] It can be seen that the pKa values ​​of TBAESE and TBAEE are comparable across the measured range and significantly higher than the pKa value of MDEA. From these measurements, it can be concluded that the acid gas charging and regeneration of TBAESE are comparable to TBAEE.

[0132] In summary, while TBAESE and TBAEE have similar absorption properties, TBAESE shows slightly improved thermal stability. This allows TBAESE to be handled under slightly higher regeneration temperatures, enabling more complete regeneration of the absorbent.

[0133] In addition, TBAESE combines the benefits of sterically hindered amines, such as high selectivity for H2S and thioalcohols, and a high removal rate of other sulfur compounds that may be present in the feed gas, particularly mercaptans, in a single molecule. Petition 870240077914, dated 11 / 09 / 2024, pp. 44 / 50

Claims

1 / 2 Claims 1. PROCESS FOR REMOVING ACID GASES FROM A FLUID STREAM, characterized in that the fluid stream is brought into contact with an absorbent to obtain a treated fluid stream and a charged absorbent, the absorbent comprising at least one diluent and a compound of general formula (I): wherein R1 is C1-C3 alkyl; R2 is C1-C3 alkyl; R3 is selected from hydrogen and C1-C3 alkyl; R4 is selected from hydrogen and C1-C3 alkyl and n is an integer in the range of 1 to 4.

2. PROCESS, according to claim 1, characterized in that each of R1, R2 and R3 is C1 alkyl.

3. PROCESS, according to any one of claims 1 to 2, characterized in that the compound of general formula (I) is 2[2-(tert-butylamino)ethylsulfanyl]ethanol.

4. PROCESS, according to any one of claims 1 to 3, characterized in that the diluent comprises water.

5. PROCESS, according to claim 4, characterized by the absorbent further comprising an acid.

6. PROCESS, according to any one of claims 1 to 5, characterized in that the diluent comprises a non-aqueous organic solvent.

7. PROCESS, according to claim 6, characterized by the organic solvent being selected from C4-10 alcohols, Petition 870240077914, dated 11 / 09 / 2024, p. 45 / 50 2 / 2 ketones, esters, lactones, amides, lactams, sulfones, sulfoxides, glycols, polyalkylene glycols, di- or mono (C1-C4 alkyl ether) glycols, di- or mono (C1-C4 alkyl ether) polyalkylene glycols, cyclic ureas, thioalkanols and mixtures thereof.

8. PROCESS, according to any one of claims 1 to 7, characterized by the absorbent comprising at least one activator selected from a sterically unhindered primary amine and / or a sterically unhindered secondary amine.

9. PROCESS, according to claim 8, characterized in that the activator is piperazine.

10. PROCESS, according to any one of claims 1 to 7, characterized in that it is for the selective removal of hydrogen sulfide from a fluid stream comprising carbon dioxide (CO2) and hydrogen sulfide (H2S).

11. PROCESS, according to any one of claims 1 to 10, characterized in that the loaded absorbent is regenerated by means of at least one of the measures of heating, decompression and removal with an inert fluid. Petition 870240077914, dated 11 / 09 / 2024, pp. 46 / 50

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