Method for removing gas

Abstract

The invention relates to a method for removing gas. The subject of the invention is a process for removing at least one gas from a fluid stream, in which an absorbent is brought into contact with the fluid stream, the absorbent comprising at least one amino group-containing compound, the amino group-containing compound being an aminoalkylated isophorone diamine.

Description

Technical Field

[0001] The present invention relates to a method for removing at least one gas from a fluid stream. Background Art

[0002] In recent decades, removing gases from fluid streams has become very important. In particular, for various reasons, it is desirable to remove carbon dioxide (CO 2 ) from flue gases and exhaust gases. In this context, reducing carbon dioxide emissions is crucial because they are considered the main cause of the greenhouse effect.

[0003] The prior art includes using amines to remove CO 2 from a fluid stream. Here, for example, a gas stream containing CO 2 (exhaust gas stream) can be contacted with an amine solution. In the reaction of the amine + CO 2 , different products are formed here: carbamates are formed with primary or secondary amines, and carbonates are formed with tertiary amines. These products precipitate or go into solution, thereby removing CO 2 from the gas. In order to release the bound CO 2 again, the precipitated or dissolved carbamate or carbonate is heated at a suitable location. The formed CO 2 is either stored or undergoes a direct chemical reaction.

[0004] WO 2010 / 149599 A1 discloses a method for removing gases from a fluid stream, in which an absorption liquid containing an amine, a stripping aid, and water is used. The gas to be removed is preferably CO 2 , H 2 S, COS, mercaptans, SO 3 , SO 2 , CS 2 , and HCN. Very particularly preferably, the amine is monoethanolamine, piperazine, methylaminopropylamine, diethanolamine, or 1-hydroxyethylpiperazine.

[0005] WO 2016 / 068698 A1 and WO 2016 / 068699 A1 disclose CO 2 absorption methods, in which primary, secondary, or tertiary amines in aqueous solution can be used. Preferably available amines are monoamines. These amines can also be substituted by functional groups, preferably by hydroxyl groups. These amines can also be cyclic amines. Very particularly preferably, the amine is N,N-dimethylcyclohexylamine (DMCA), N-methylcyclohexylamine (MCA), or a mixture thereof.

[0006] WO 2014 / 140108 A1 discloses a method for absorbing CO 2 from a gas stream containing CO 2 , in which a CO containing a thermoresponsive copolymer is used2 An absorbent, the thermoresponsive copolymer comprising an amine monomer. The amine monomer can be various polymerizable monomers having at least one primary, secondary or tertiary amino functional group. Preferred amine monomers can be selected from amine-functionalized acrylamides, amine-functionalized methacrylamides, amine-functionalized acrylates, amine-functionalized methacrylates and cyclic amine monomers. However, a disadvantage of the method is the laborious synthesis of the copolymer. The disclosed CO 2 absorbent may also comprise an amine component dissolved in water. Compounds mentioned in this regard include in particular 3,3,5-trimethylcyclohexylamine, N-methylcyclohexylamine, N,N-dimethylcyclohexylamine, N-methyldiethanolamine, piperazine and 2-aminoethanol.

[0007] WO 2015 / 053619 A1 discloses a method for absorbing CO 2 from a gas stream containing CO 2 wherein a CO 2 absorbent comprising an amine component, an inorganic salt and water is used. The amine component has a boiling point of at least 100 °C. The amine component can be an organic compound having 2-20 carbon atoms. Compounds mentioned include in particular 3,3,5-trimethylcyclohexylamine, N-methylcyclohexylamine, N,N-dimethylcyclohexylamine, N-methyldiethanolamine, piperazine and 2-aminoethanol.

[0008] US 4,112,050 A in particular discloses various alicyclic amines such as N 1 -cyclohexylpropane-1,2-diamine, 1-amino-1-(2-aminopropyl)cyclohexane, 1-methylamino-1-aminomethylcyclopentane, 1-amino-1-aminomethylcycloheptane, N-isopropyl-1,2-diaminocyclohexane, N 2 -cyclohexylbutane-1,2-diamine, N 2 -cyclohexylpropane-1,2-diamine, N-cycloheptyl-1,2-ethylenediamine, N 1 -cyclohexyl-2-methylpropane-1,2-diamine, 1-(2-aminopropyl)-2-amino-3-methylcyclopentane, N-isopropyl-1,4-diaminocyclohexane, N 1 -cyclohexyl-N 2 -methylethylenediamine, N-cyclohexylethylenediamine, N 1 -cyclohexyl-N 2 -ethylenediamine, N 1 -cyclohexyl-N 2 -methylpropane-1,2-diamine, N-cyclohexylpropane-1,3-diamine, p-menthane-1,8-diamine, 1-amino-1-aminomethylcyclohexane, 1,3-diamino-1-methylcyclohexane and N 2 -cyclohexyl-2-methylpropane-1,2-diamine for absorbing CO2 Applicability. The method uses an aqueous solution of the amine.

[0009] WO 2013 / 075697 A1 discloses a method for separating CO from a fluid mixture and / or a fluid stream, in which a cyclic amine is used. The disclosed cyclic amines include 1,2-diaminocyclohexane, 1,3-diaminocyclohexane, 1,4-diaminocyclohexane, 1,2,3-triaminocyclohexane, 1,2,4-triaminocyclohexane, 1,3,5-triaminocyclohexane, 1,8-diazabicyclo[5.4.0]undec-7-ene, 1,5-diazabicyclo[4.3.0]non-5-ene, N-methylcyclohexanediamine, N 2 ,N 1 ,N 2 -1,2-dimethylcyclohexanediamine, N 1 ,N 1 ,N 2 -trimethylcyclohexane-1,2-diamine, N-methyl-1,3-cyclohexanediamine, N 1 ,N 1 -dimethyl-1,3-cyclohexanediamine, N 1 ,N 3 -dimethyl-1,3-cyclohexanediamine, N-methylcyclohexane-1,4-diamine, N 1 ,N 1 -dimethylcyclohexane-1,4-diamine, N 1 ,N 4 -dimethylcyclohexane-1,4-diamine, N 1 ,N 4 ,N 4 -trimethylcyclohexane-1,4-diamine, indole and isophorone diamine. Isophorone diamine is very particularly preferred. The preferred amines, especially isophorone diamine, form carbamates with CO, which are at least partially insoluble in the solvent used and can be separated out as a solid phase or a liquid phase. This enables the bound CO to be released again more easily and with less energy consumption. 2 . 2 .

[0010] WO 2022 / 085789 A1 also discloses a method for sequestering CO, in which an amine with a cyclic hydrocarbon backbone is used. Exemplary compounds mentioned and used in experiments include isophorone diamine, cyclohexylamine, cyclohexane-1,2-diamine, cyclohexane-1,4-diamine and 4,4'-methylenebis(2-methylcyclohexylamine). 2 .

[0011] ACS Environ. Au 2022, 2, 354 - 362 discloses a study in which the absorption capacities of different amines were compared. Primary amines showed higher storage efficiencies than secondary and tertiary amines, which may be due to steric hindrance. However, primary aromatic amines such as aniline hardly absorb CO 2 . Diamines with aminocyclohexyl have higher storage capacities than monoamines and, unlike monoamines, also have the advantage of producing insoluble precipitates. Furthermore, it was surprisingly disclosed that isophorone diamine has a particularly high CO 2 storage capacity and a particularly favorable long efficiency period (T 90 ). In combination with the also observed lower desorption temperature, isophorone diamine was found to be particularly preferred compared to monoethanolamine.

[0012] However, it is desirable to provide a method in which the amines used are equally suitable for sequestering CO 2 , but the energy required to separate CO 2 from the carbamate of the amines used can be further reduced. Summary of the Invention

[0013] Surprisingly, it has now been found that aminoalkylated isophorone diamines achieve the purpose of absorbing CO 2 particularly well and desorbing again at particularly low temperatures.

[0014] Accordingly, the subject matter of the present invention is a method for removing at least one gas from a fluid stream, in which an absorbent is brought into contact with the fluid stream, wherein the absorbent comprises at least one amino - containing compound, and the amino - containing compound is an aminoalkylated isophorone diamine.

[0015] The fluid stream from which at least one gas is to be removed can be a fluid stream selected from gases and liquids. If the fluid is a gas, the fluid is preferably selected from gases such as natural gas, syngas, coke oven gas, cracked gas, coal gasification gas, recycle gas, landfill gas, and combustion gas. If the fluid is a liquid, the liquid is preferably selected from liquefied petroleum gas (LPG, autogas) and liquefied natural gas (LNG, liquefied natural gas) or one of the above - preferred gases in liquefied form.

[0016] The method according to the invention is particularly suitable for removing gases from a fluid stream that is also gaseous.

[0017] The gas to be removed is a gaseous compound that is present under the conditions of the method and further preferably under SATP conditions (298.15 K, 1.013 bar). Preferably, the gas is selected from CO 2 , H 2 S, COS, gaseous thiols, SO 3 , SO 2 , CS2 and gases such as HCN. Advantageously, the process according to the invention is particularly suitable for removing CO 2 .

[0018] In the process according to the invention, a fluid stream is brought into contact with an absorbent comprising at least one amino-containing compound. This means that the fluid stream can be brought into contact with an absorbent comprising one, two, three or more than three amino-containing compounds. Particularly preferably, the fluid stream is brought into contact with an absorbent comprising only one amino-containing compound. For achieving advantageous performance, it may alternatively be advantageous for the fluid stream to be brought into contact with an absorbent comprising two amino-containing compounds.

[0019] The absorbent is to be understood as meaning a liquid or gaseous composition capable of absorbing the gases contained in the fluid stream. Further preferably, the absorbent is in liquid form under the conditions of the process, and more preferably also in liquid form under SATP conditions.

[0020] At least one of the amino-containing compounds in the absorbent is an alkylated isophorone diamine. If the absorbent comprises only one amino-containing compound, then this amino-containing compound is thus an aminoalkylated isophorone diamine. If the absorbent comprises more than one amino-containing compound, then all the amino-containing compounds can be differently alkylated aminoalkylated isophorone diamines. Alternatively, the absorbent can also comprise a plurality of differently aminoalkylated isophorone diamines and other amino-containing compounds.

[0021] Preferred are aminoalkylated isophorone diamines alkylated only on the amino group in the 1-position on the ring. These aminoalkylated isophorone diamines are able to absorb and release CO very particularly well 2 . The corresponding aminoalkylated isophorone diamines have the formula (I) as shown below,

[0022]

[0023] wherein R is

[0024] - the alkyl group of formula -C n H 2n R' where n = 1 - 10 and R' = H, OH or C 1 -C 3 alkyl, or

[0025] - an aromatic group R = -C 6 H 4 R” where R” = H, OH or C 1 -C 3 alkyl.

[0026] This synthesis can be achieved by the reaction of isophorone nitrile with the corresponding primary amine and subsequent hydrogenation, similar to the disclosure of DE 102011113395 A1.

[0027] Very particularly preferably, it is a methylated or ethylated isophorone diamine, i.e., a compound of formula (I) in which R = -CH 3 or -C 2 H 5 of formula (I).

[0028] When the at least one aminoalkylated isophorone diamine is used together with at least one other amino-containing compound, in principle, various arbitrary amino-containing compounds can be used as the latter. Preferred are primary, secondary, and tertiary amines which are optionally hydroxy-substituted and optionally aminoalkylated. Very particularly preferred other amino-containing compounds can be selected from isophorone diamine, 4,4'-diaminodicyclohexylmethane (PACM), aminoalkylated 4,4'-diaminodicyclohexylmethane (aminoalkylated PACM), N,N-dimethylcyclohexylamine, N-methyldiethanolamine, piperazine, and 2-aminoethanol.

[0029] Preferably, based on the total mass of the amino-containing compounds present in the absorbent, the mass proportion of the aminoalkylated isophorone diamine is 50 - 100% by weight, more preferably 70 - 100% by weight, and even more preferably 90 - 100% by weight, because the gas can be absorbed particularly well and desorbed again at a particularly low temperature in this way. As mentioned above, very particularly preferably, only the method using aminoalkylated isophorone diamine is used. At this time, based on the total mass of the amino-containing compounds present in the absorbent, the mass proportion of the aminoalkylated isophorone diamine is correspondingly 100% by weight.

[0030] In principle, a solvent can be present in the absorbent. Preferred solvents are water and organic solvents with a boiling point below that of water at 1.013 bar (especially the corresponding alcohols and ethers). Very particularly preferably, solvents selected from water, methanol, ethanol, n-propanol, isopropanol, tetrahydrofuran, diethyl ether, diisopropyl ether, methyl tert-butyl ether, and toluene are used.

[0031] Preferably, based on the mass of the other components present, the mass proportion of the solvent in the absorbent is 0 - 50% by weight, preferably 0 - 30% by weight, and very particularly preferably 0 - 10% by weight.

[0032] Even more preferably, the method is carried out without a solvent. Therefore, very particularly preferably, based on the mass of the other components present, the mass proportion of the solvent in the absorbent is no added solvent, i.e., 0% by weight.

[0033] Surprisingly, it can be found that the products formed from the aminoalkylated isophorone diamine and the gas to be removed, in particular the carbamate formed from the aminoalkylated isophorone diamine and CO 2 precipitate not only from common solvents, but also from the aminoalkylated isophorone diamine present in liquid form and used as a solvent. Thus, the solvent-free process variant surprisingly enables the process to be carried out as a particularly preferred two-stage process, in which the energy consumption is reduced because the solvent does not need to be laboriously separated, purified or heated together with the resulting product. In addition, the use of solvents is generally disadvantageous due to the desire to reduce the VOC content. Thus, a particularly preferred process is a process for removing at least one gas (preferably CO 2 ) from a fluid stream, in which an absorbent is brought into contact with the fluid stream, where

[0034] - the absorbent comprises at least one amino-containing compound which is an aminoalkylated isophorone diamine, and

[0035] - the absorbent is solvent-free, and

[0036] - the absorbent is brought into contact with the fluid stream,

[0037] - the product formed from

[0038] o the amino-containing compound (in particular the aminoalkylated isophorone diamine) and

[0039] o the gas to be removed (in particular CO 2 ),

[0040] o in particular the carbamate formed from the aminoalkylated isophorone diamine and CO 2 is precipitated,

[0041] - from the absorbent,

[0042] - separated from the absorbent and optionally dried, and

[0043] - the separated and optionally dried product is treated so that the absorbed gas is released again.

[0044] Preferably, the absorbent is brought into contact with the fluid stream such that the fluid stream is passed through the absorbent. For better distribution, the fluid stream can be passed through a percolator or by another suitable measure that increases the interface between the liquid absorbent and the gas. More preferably, this is achieved by spraying the absorbent onto the fluid stream.

[0045] The preferred reaction time is from 5 minutes to 48 hours, preferably from 10 minutes to 12 hours. The preferred reaction temperature is from ambient temperature (i.e., without heating) to 80 °C. The reaction temperature is preferably from room temperature to 50 °C.

[0046] By adding a substance that promotes precipitation, the precipitation of aminoalkylated isophorone diamine and the product of the gas to be removed can be promoted. Particularly suitable solvents for promoting precipitation can be selected from alcohols and ethers.

[0047] Preferably, the formed product is separated out by filtration or centrifugation.

[0048] The release of the absorbed gas can be carried out in types and manners known to those skilled in the art. The released gas can be stored in types and manners known to those skilled in the art, or can directly undergo a chemical reaction. If the absorbent is recovered in the same form during gas release, it is preferably supplied again to the method of the present invention.

[0049] In particular, when the gas to be removed is CO 2 in the case of, CO can be released by heating the formed carbamate. 2 . The initially used amino-containing compound (especially the recovered aminoalkylated isophorone diamine) that is also released at this time can be supplied again to the absorbent of the method. In principle, a basic or acidic catalyst can be supplied to eliminate CO 2 . However, it is preferred to carry out the method without using a catalyst. In addition, the pH value can also be adjusted by an electrolysis method to thereby further reduce the elimination temperature. Additionally, it may be advantageous to introduce an inert gas, especially nitrogen, to eliminate CO 2 . Specific embodiments

[0050] Experimental part:

[0051] a) Comparative example:

[0052] Air was blown through isophorone diamine for 24 hours until crystals were formed. According to the NMR spectrum, these crystals consisted of the carbamate of IPD and CO 2 . The crystals were stable in air. DSC showed decomposition (eliminating CO 2 ) at 144 - 149 °C (848 J / g). When these crystals were heated in air (30 minutes, 150 °C), pure IPD (NMR) was recovered.

[0053] b) Comparative example:

[0054] CO 2 was blown through N-methylcyclohexylamine for 24 hours until crystals were formed. The obtained crystals were unstable and quickly liquefied in air. DSC showed decomposition (eliminating CO 2)。The first peak indicates a lack of stability at room temperature, while the second peak indicates an increase in energy input compared to Example c) of the present invention.

[0055] c) Example of the present invention:

[0056] Air was blown over N-methyl-IPD for 24 hours until crystals formed. According to the NMR spectrum, these crystals consisted of the carbamate of N-methyl-IPD and CO 2 The crystals were stable in air. DSC showed decomposition (eliminating CO 2 ) at 123 - 126 °C (742 J / g). When these crystals were heated in air (30 minutes, 130 °C), pure N-methyl-IPD (NMR) was recovered.

Claims

1. A process for removing at least one gas from a fluid stream, wherein an absorbent is brought into contact with the fluid stream, Features The absorbent comprises at least one amino group-containing compound, which is an aminoalkylated isophoronediamine.

2. The method according to claim 1, Features The fluid stream is a stream of a fluid selected from the group consisting of natural gas, synthesis gas, coke oven gas, cracking gas, coal gasification gas, cycle gas, landfill gas, combustion gas, liquefied petroleum gas and liquefied natural gas.

3. The method according to claim 1 or 2, Features The gas is selected from CO2, H2S, COS, gaseous mercaptans, SO3, SO2, CS2 and HCN.

4. The method according to any one of the preceding claims, Features The absorbent comprises an amino group-containing compound.

5. The method according to any one of claims 1 to 3, Features The absorbent comprises two amino group-containing compounds.

6. The method according to any one of the preceding claims, Features The aminoalkylated isophorone diamine is of formula (I) - Where R = -C n H 2n R' o Where n = 1-10 and o R'=H, OH or C1-C3 alkyl - or R is an aromatic group of formula -C6H4R" oWherein R"=H, OH or C1-C3 alkyl.

7. The method according to claim 6, Features R=-CH3 or -C2H5.

8. The method according to any one of the preceding claims, Features The at least one aminoalkylated isophoronediamine is used together with at least one other amino group-containing compound selected from the group consisting of isophoronediamine, 4,4'-diaminodicyclohexylmethane (PACM), aminoalkylated 4,4'-diaminodicyclohexylmethane (aminoalkylated PACM), N,N-dimethylcyclohexylamine, N-methyldiethanolamine, piperazine and 2-aminoethanol.

9. The method according to any one of the preceding claims, Features The mass proportion of the aminoalkylated isophoronediamine is 50 to 100% by weight, based on the total mass of the amino-containing compounds present in the absorbent.

10. The method according to any one of the preceding claims, Features The process is carried out in the absence of solvent.

11. The method according to any one of the preceding claims, Features - the absorbent contains no solvent, and - contacting the absorbent with a fluid stream, - a product formed from oAmino compounds and oGas to be removed, - precipitation from the absorbent, - and separated from the absorbent and optionally dried, and The separated and optionally dried product is treated in such a way that the absorbed gases are released again.

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