Alkoxylated polyalkylene imine, preparation and use

Abstract

Disclosed is a method for producing a composition comprising an alkoxylated polyalkylene imine, the composition and the use thereof. The present invention provides the use of a composition comprising an alkoxylated polyalkyleneimine, obtainable by a process for producing a composition comprising an alkoxylated polyalkyleneimine, comprising the steps of: (a) providing a reaction mixture for capturing a gas having a pKa greater than 5, preferably carbon dioxide, from a gas or gas mixture, the reaction mixture comprises (i) a polyalkylene imine; and (ii) an alkylene oxide; (b) carrying out a reaction between the (i) polyalkylene imine and the (ii) alkylene oxide at a temperature of at least 50 DEG C; and (c) optionally diluting the product of step (b) wherein the molar ratio of alkylene oxide to the NH of the polyalkylene imine in the reaction mixture is from 0.1 to 0.35, and wherein the reaction mixture comprises based on the weight lt of the reaction mixture; 55% of water, preferably 1t; 30% water, and the reaction mixture comprises less than 5%, preferably less than 1%, of polar organic solvent, based on the weight of the reaction mixture. Also claimed is a novel composition comprising an alkoxylated polyalkylene imine, which is obtainable by a process similar to the above, where the alkylene oxide comprises propylene oxide and / or butylene oxide. A method of producing the novel composition is also claimed. The novel composition has been found to be effective in capturing carbon dioxide from gas mixtures such as air.

Description

Technical Field

[0001] The present invention belongs to the field of alkoxylated polyalkyleneimines for capturing gases having a pKa greater than 5, in particular carbon dioxide, from one or more gases containing the same. The present invention also provides new compositions of alkoxylated polyalkyleneimines and provides a novel method for preparing these compositions. It has been found that these new compositions can absorb carbon dioxide particularly effectively. The method also has the advantage of avoiding the use of volatile organic compounds, especially polar organic solvents. Background Art

[0002] Given the expected impact on climate change, the increasing levels of greenhouse gases in the atmosphere have drawn growing global attention. This is particularly true given the increasing levels of carbon dioxide. It is generally believed that even the current concentration of carbon dioxide in the atmospheric air is the cause of the increasingly severe environmental changes, which include droughts, floods, and the destruction of global ecosystems. It is predicted that as the level of carbon dioxide continues to rise, a significant increase in the average temperature of the atmosphere and the oceans is expected, leading to an exacerbation of the melting of polar and glacial ice, which in turn leads to a rising sea level and the inevitable flooding of low-lying areas. An increase in atmospheric temperature is also expected to increase the likelihood of global severe cyclonic storms.

[0003] Many national governments aim to take action through legislation to reduce the emissions of greenhouse gases, especially carbon dioxide, and ultimately limit global warming. Many countries have adopted the Paris Agreement, which is a legally binding international climate change treaty. Its goal is to limit global warming to well below 2 °C, preferably to 1.5 °C, compared to pre-industrial levels.

[0004] In recent years, significant efforts have been made in developing technologies that can achieve the goal of reducing the level of carbon dioxide in atmospheric air and / or gas emissions. Capturing carbon dioxide at the source is generally considered the most cost-effective. Typically, this source can be large carbon-based energy facilities, natural gas processing, synthetic fuel plants, industries with mainly carbon dioxide emissions (such as steelmaking and cement production), and hydrogen production plants using fossil fuels.

[0005] A major carbon capture technology involves the absorption or sequestration of carbon dioxide. To date, the most common active compounds used for carbon dioxide absorption rely on amine chemistry. Typical amines for this purpose include alkanolamines (including monoethanolamine, diethanolamine, diisopropanolamine), pentaethylenehexamine, tetraethylenepentamine, triethylenetetramine, tetraethylenetetramine, bis(2-hydroxypropyl)amine, N,N'-bis(2-hydroxyethyl)ethylenediamine, alkylamines, methylamine, linear polyethylenimine, branched polyethylenimine, dimethylamine, diethylamine, methyldiethanolamine, methylethanolamine, polyethylenepolyamines, diethylenetriamine, N,N'-bis-(3-aminopropyl)ethylenediamine.

[0006] U.S. Patent No. 9,084,960 B2 discloses a method for reducing the CO2 content in a gas and uses a CO2 capture agent, which can include monoamines (especially secondary amines such as diethanolamine), polyamines, monoguanidines and polyguanidines, and mixtures of these compounds.

[0007] U.S. Patent No. 9,533,250 B2 relates to reducing CO2 from indoor air in an enclosed space. This reference describes amine-based compounds and proposes that the amine-based compounds can include any suitable amine (such as primary or secondary amines as will be described) or combinations thereof. This disclosure reveals that the amine-based compounds can range from simple single molecules (such as ethanolamine) to large molecular amine polymers (such as polyethylenimine). Proposed in this literature are any of monoethanolamine, ethanolamine, methylamine, branched polyethylenimine, linear polyethylenimine, diethanolamine, dimethylamine, diethylamine, diisopropanolamine, tetraethylenepentamine, methyldiethanolamine, methylethanolamine, and several polyamines (such as polyethylenimine), or combinations thereof.

[0008] U.S. Patent No. 11,229,897 B2 discloses a gas absorption material that includes polyamines produced using a method that does not include formaldehyde as a reaction product and / or reactant. This disclosure describes a reaction solution for producing a first amine compound and a reactant. It is said that the reactant includes a carbonate compound or a ketone compound. The first amine compound will react with the reactant to produce a second amine compound.

[0009] U.S. Patent No. 10,010,861 B2 describes polymer amines in the context of carbon dioxide absorption. It is said that the polymer amine consists of a polymer backbone containing nitrogen atoms and branched chains bonded to the nitrogen atoms of the polymer backbone. Each branched chain contains at least one nitrogen, and the polymer amine is modified by replacing the nitrogen atoms of the polymer backbone or at least one nitrogen atom in the branched chains with hydroxy-containing carbon chains. Example 1 describes the synthesis of polyethylenimine modified by partial substitution with butylene oxide. This synthesis involves dissolving polyethylenimine (MN = 1200, 19 mmol N / g) in methanol. The disclosure reveals adding butylene oxide in different amounts to the polyethylenimine / methanol solution such that the molar ratio of butylene oxide to the nitrogen atoms present in polyethylenimine is 0.15:1, 0.37:1, and 0.54:1. The disclosure reveals removing the solvent by subjecting the solution of the modified polyethylenimine to heating in a vacuum oven.

[0010] U.S. Patent No. 10,751,689 B2 discloses modified polyamines in the context of carbon dioxide absorption. The modified polyamine is a reaction product of an amine and an epoxide. Example 1 reveals the preparation of a modified polyamine material based on pentaethylenehexamine (PEHA) and propylene oxide (PO). This preparation describes dissolving 10 g of PEHA in 40 mL of water and adding 5 g of PO to the PEHA solution, followed by stirring at room temperature for 20 hours. It is said that the temperature of the reaction mixture is gradually increased to 60 °C and maintained for two hours. It is said that water is removed by a rotary evaporator and then it is vacuumed overnight at below 1 mmHg.

[0011] The alkoxylation of polyalkyleneimines is well-known and documented in the literature. For example, the alkoxylation of polyethylenimine using ethylene oxide, propylene oxide, and butylene oxide is described in Houben-Weyl, Methoden der organischen Chemie [Methods of Organic Chemistry], 4th Edition, Volume 14 / 2, pages 440 et seq. (1963) and Volume E 20, pages 1367 et seq. (1987).

[0012] U.S. Published Patent No. 2021309934A1 relates to a process for manufacturing ethoxylated polyethylenimine by reacting at least one polyethylenimine (PEI) with at least one ethylene oxide EO. In a first step (1), the polyethylenimine (PEI) is reacted with ethylene oxide EO in an amount less than one molar equivalent per PEI, and subsequently, in a second step (2), the product of step (1) is reacted with an additional amount of ethylene oxide EO in the presence of a basic catalyst. It is said that in step (1), ethylene oxide EO is added in an amount of 0.01 to 0.85 ethylene oxide units per NH group of the polyethylenimine (PEI). It is said that the polyethylenimine (PEI) has a molecular weight Mw in the range of 1000 to 5000 (before ethoxylation). This document seems to solve the following problem: Introducing ethoxylated polyethylenimine prepared by known methods into laundry formulations may reduce the viscosity of the resulting liquid, which leads to reduced consumer acceptance of the formulation and requires additional viscosity enhancement techniques. It is pointed out that using a two-step process for ethoxylating the initial PEI and adjusting the amount of EO added in the first (and second) step to a certain range (strongly under-hydroxyethylated) can significantly mitigate the problems of the prior art.

[0013] The inventors of the present invention have set forth the object of providing an alkoxylated polyethylenimine having improved activity for this purpose compared to conventional alkoxylated polyethylenimines of the prior art for capturing carbon dioxide. Another object of the present invention is to provide a convenient process for providing an alkoxylated polyethylenimine that is suitable for capturing carbon dioxide and preferably has improved activity for this purpose. Summary of the Invention

[0014] According to a first aspect of the present invention, there is provided the use of a composition comprising an alkoxylated polyalkyleneimine, preferably an alkoxylated polyethylenimine, for capturing a gas having a pKa greater than 5, preferably carbon dioxide, from a gas or gas mixture, the composition obtainable by a process comprising the following steps:

[0015] (a) Providing a reaction mixture comprising

[0016] (i) a polyalkyleneimine, preferably a polyethylenimine; and

[0017] (ii) an alkylene oxide;

[0018] (b) Carrying out the reaction between the (i) polyalkyleneimine, preferably the polyethylenimine, and the (ii) alkylene oxide at a temperature of at least 50 °C; and

[0019] (c) Optionally diluting the product of step (b),

[0020] wherein the molar ratio of the alkylene oxide to the NH units of the polyalkyleneimine and polyethyleneimine in the reaction mixture is from 0.1 to 0.35,

[0021] and wherein the reaction mixture comprises <55% by weight of water, preferably <30% by weight of water, based on the weight of the reaction mixture, and the reaction mixture comprises less than 5% by weight, preferably less than 1% by weight, of a polar organic solvent, based on the weight of the reaction mixture.

[0022] NH represents the amine value and is calculated by determining the secondary and primary amino groups, where NH = (number of secondary amino groups) + (2 x (number of primary amino groups)). NH is determined by titrating the corresponding polyalkyleneimine with trifluoromethanesulfonic acid.

[0023] A second aspect of the present invention relates to a process for preparing a composition comprising an alkoxylated polyalkyleneimine, preferably an alkoxylated polyethyleneimine, the composition obtainable by a process comprising the steps of:

[0024] (a) providing a reaction mixture comprising

[0025] (i) a polyalkyleneimine, preferably a polyethyleneimine; and

[0026] (ii) an alkylene oxide comprising propylene oxide and / or butylene oxide;

[0027] (b) carrying out the reaction between the (i) polyalkyleneimine, preferably polyethyleneimine, and the (ii) alkylene oxide at a temperature of at least 50 °C,

[0028] (c) optionally diluting the product of step (b),

[0029] wherein the molar ratio of the alkylene oxide to the NH units of the polyalkyleneimine, preferably polyethyleneimine, in the reaction mixture is from 0.1 to 0.35,

[0030] and wherein the reaction mixture comprises <55% by weight of water, preferably <30% by weight of water, based on the weight of the reaction mixture, and the reaction mixture comprises less than 5% by weight, preferably less than 1% by weight, of a polar organic solvent, based on the weight of the reaction mixture.

[0031] A third aspect of the present invention provides a composition comprising an alkoxylated polyalkyleneimine, preferably an alkoxylated polyethyleneimine, the alkoxylated polyalkyleneimine, preferably alkoxylated polyethyleneimine, the composition obtainable by a process comprising the steps of:

[0032] (a) providing a reaction mixture comprising

[0033] (i) A polyalkyleneimine, preferably a polyethyleneimine; and

[0034] (ii) An alkylene oxide, which alkylene oxide includes propylene oxide and / or butylene oxide;

[0035] (b) The reaction between the (i) polyalkyleneimine, preferably polyethyleneimine, and the (ii) alkylene oxide is carried out at a temperature of at least 50 °C,

[0036] (c) Optionally diluting the product of step (b),

[0037] wherein the molar ratio of the alkylene oxide to the NH units of the polyalkyleneimine, preferably polyethyleneimine, in the reaction mixture is from 0.1 to 0.35,

[0038] and wherein the reaction mixture contains <55% by weight of water, preferably <30% by weight of water, based on the weight of the reaction mixture, and the reaction mixture contains less than 5% by weight, preferably less than 1% by weight, of a polar organic solvent based on the weight of the reaction mixture. Detailed Description

[0039] The inventors of the present invention have found that, compared with alkoxylated polyalkyleneimines of the prior art, the alkoxylated polyalkyleneimines, in particular alkoxylated polyethyleneimines, provided by the newly developed method unexpectedly exhibit particularly improved results in capturing carbon dioxide.

[0040] Without being bound by theory, the inventors believe that, compared with methods of alkoxylating polyalkyleneimines using higher levels of solvents, by carrying out the method in the absence or almost absence of polar organic solvents (i.e., less than 5%, preferably less than 1%) and in the absence or presence of a limited amount of water (i.e., <55% by weight of water, preferably <30% by weight of water, based on the weight of the reaction mixture), competitive side reactions are avoided. In fact, at low alkylene oxide to NH ratios, such competitive reactions that may prevent alkoxylation are prevented in order to ensure at least substantially complete alkoxylation at the desired ratio.

[0041] The method is considered more suitable for the commercial-scale production of alkoxylated polyethyleneimines having a low alkylene oxide to NH ratio. The inventors have recognized that in the combination of the absence or almost absence of organic solvents and the absence or limited presence of water (where the narrow weight ratio of alkylene oxide to NH of the polyalkyleneimine is from 0.1 to 0.35), this provides an alkoxylated polyalkyleneimine that is more effective for the purpose of absorbing carbon dioxide. This could not have been inferred or predicted by those skilled in the art.

[0042] Desirably, the reaction mixture in the method suitably contains, by weight, less than 3%, typically less than 2%, preferably less than 1%, such as less than 7500 ppm, more preferably less than 5000 ppm, particularly preferably less than 1000 ppm, less than 500 ppm, even more particularly preferably less than 100 ppm, and most preferably less than 50 ppm of a polar organic solvent based on the weight of the reaction mixture. Most preferably, the reaction mixture is free of any polar organic solvent. The inventors believe that completely avoiding polar organic solvents most effectively avoids the risk of unwanted competing side reactions and will provide a more efficient product. In addition, the inventors unexpectedly found that the reaction rate is greater when carried out in the absence of polar organic solvents. Such an increased reaction rate will be beneficial to production time and cost and can be particularly useful when considering continuous processes. Additionally, the inventors have found that by avoiding the introduction of polar organic solvents into the reaction mixture, there will be less residual alkylene oxide remaining in the reaction product. Given the high toxicity of alkylene oxides, achieving a low level of alkylene oxide in alkoxylated polyalkyleneimines is important for product safety.

[0043] A polar organic solvent means an organic compound exhibiting polarity that is typically used as a solvent. Typically, such an organic solvent will be an organic liquid that dissolves or is miscible with polyalkyleneimine or alkoxylated polyalkyleneimine. Specific examples of such polar organic solvents include methanol, ethanol, isopropanol, acetone, DMF, and chloroform.

[0044] Accordingly, a composition comprising an alkoxylated polyalkyleneimine, preferably an alkoxylated polyethyleneimine, produced according to the present invention preferably contains, by weight, less than 150 ppm, suitably less than 100 ppm, more suitably less than 50 ppm, more preferably less than 20 ppm, particularly preferably less than 10 ppm, and even more particularly preferably less than 5 ppm of residual alkylene oxide based on the weight of the alkoxylated polyalkyleneimine in the composition.

[0045] These concentrations of alkylene oxide can be determined by thermal desorption, where the released volatiles are quantified by gas chromatography - mass spectrometry. According to the present disclosure, the GC / MS used for calculating the values is provided by Agilent. The system configuration is a GC - MS Kopplung (7890 / 5975 or 7890 / 5977) with an electron ionization ion source and a single quadrupole spectrometer.

[0046] The alkoxylated polyalkyleneimine according to the invention, preferably alkoxylated polyethyleneimine, can be obtained by a process in which the amount of water in the reaction mixture must be less than 55% by weight, based on the weight of the reaction mixture. Desirably, the amount of water in the reaction mixture should be less than 50% by weight of the reaction mixture, normally less than 40%, typically up to 36% or up to 35%, but usually less than 35% by weight of the reaction mixture. Preferably, the amount of water in the reaction mixture should be less than 30% by weight of the reaction mixture. Desirably, the amount of water should be less than 20% by weight of the reaction mixture. More desirably, the amount of water in the reaction mixture should be even lower, for example up to 17% by weight of the reaction mixture, typically up to 16% by weight of the reaction mixture, such as up to 15% by weight of the reaction mixture, but usually less than 15% based on the weight of the reaction mixture, preferably up to 13%, or up to 12%, usually less than 12%, more preferably up to 11%, or up to 10%, usually less than 10%, for example less than 5% by weight. Even more preferably, the amount of water present in the reaction mixture should be less than 2% by weight, in particular less than 1% by weight, based on the weight of the reaction mixture. Particularly preferably, the reaction mixture should be water-free.

[0047] In a preferred embodiment, the reaction mixture is solvent-free and contains only the amount of water as a reactant, suitably up to 1 mole of water per mole of NH groups of the polyalkyleneimine, preferably polyethyleneimine. This means that the amount of water present as a reactant in the reaction mixture is present in an amount of 1 mole of water per mole of NH groups on the polyalkyleneimine, preferably polyethyleneimine, to be alkoxylated.

[0048] The process for producing alkoxylated polyalkyleneimine, preferably alkoxylated polyethyleneimine, can be continuous, batchwise, semi-batchwise or fed-batchwise. Preferably, the process is fed-batchwise and / or continuous. Desirably, the fed-batch process will involve placing one or more of the reactants (one or more first reactants) in a reaction vessel, while feeding one or more additional reactants (one or more second reactants) into the reaction vessel at a defined rate and mixing with the first reactant to form a reaction mixture while allowing the reaction to proceed.

[0049] In a preferred embodiment, steps (a) and (b) of the process can be carried out partially, mostly or entirely simultaneously.

[0050] In one embodiment, in step (a) of the method, suitably, (i) a polyalkyleneimine, preferably a polyethyleneimine, is provided in a reaction vessel. Preferably, the polyalkyleneimine, preferably the polyethyleneimine, will be provided at a temperature of at least 50 °C. Suitably, the polyalkyleneimine, preferably the polyethyleneimine, can be provided at a temperature of 50 °C to 150 °C, preferably 60 °C to 140 °C, more preferably 60 °C to 110 °C. Desirably, (ii) an alkylene oxide will be provided at a temperature of at least 50 °C, suitably 50 °C to 110 °C, preferably 60 °C to 100 °C, and will be combined with (i) the polyalkyleneimine, preferably the polyethyleneimine, to form a reaction mixture.

[0051] Preferably, (ii) the alkylene oxide is combined with (i) the polyalkyleneimine, preferably the polyethyleneimine, by feeding it at a defined rate into (i) the polyalkyleneimine, preferably the polyethyleneimine, to form a reaction mixture. When (ii) the alkylene oxide is fed into (i) the polyalkyleneimine, preferably the polyethyleneimine, reaction (b) can commence. Thus, in this embodiment, the reaction will start and proceed when the alkylene oxide is fed into the reaction mixture.

[0052] The reaction in step (b) will desirably be started by raising the temperature of the reaction mixture. Suitably, the reaction in step (b) can be carried out at a temperature of at least 60 °C, more suitably 60 °C to 140 °C, preferably 75 °C to 135 °C, more preferably 80 °C to 130 °C, still more preferably 80 °C to 130 °C.

[0053] Preferably, the reaction in step (b) can be carried out under high pressure (e.g., greater than 1 bar), suitably in a pressurized reaction vessel. Preferably, the reaction can be carried out at a pressure greater than 1.25 bar, preferably at a pressure of 1.5 bar to 3 bar.

[0054] It may be desirable to provide the composition comprising the alkoxylated polyalkyleneimine, preferably the alkoxylated polyethyleneimine, in a diluted form. Thus, in this regard, after reaction step (b), the composition comprising the reaction product so formed can be diluted with water in dilution step (c). In a preferred embodiment in which reaction step (b) is carried out under high pressure as indicated above, dilution step (c) should be carried out after the reaction mixture in the reaction vessel has been depressurized. Desirably, the product of reaction step (b) can be diluted with water to provide an aqueous solution of the alkoxylated polyalkyleneimine, preferably the alkoxylated polyethyleneimine, having a concentration of 50% to 70% by weight of the alkoxylated polyalkyleneimine, preferably the alkoxylated polyethyleneimine, based on the weight of the aqueous solution.

[0055] In this method, the molar ratio of the alkylene oxide to the NH of the polyalkyleneimine, preferably polyethyleneimine, is from 0.1 to 0.35. Preferably, the molar ratio of the alkylene oxide to NH is from 0.15 to 0.32. As described above, NH represents the amine value and is calculated by determining the secondary amino group and the primary amino group, where NH = (the number of secondary amino groups) + (2 x (the number of primary amino groups)). NH is determined by titrating the corresponding polyalkyleneimine with trifluoromethanesulfonic acid.

[0056] (i) The alkylene oxide can be any suitable alkylene oxide for alkoxylating polyalkyleneimine, preferably polyethyleneimine. Unless otherwise specified, the reference to alkylene oxide (such as propylene oxide or butylene oxide) used throughout this specification refers to 1,2-epoxy-substituted compounds. It has been found that (i) alkylene oxides containing at least three carbon atoms are particularly suitable for applications in capturing gases with a pKa greater than 5, preferably carbon dioxide. In a desired embodiment, the alkylene oxide can be more than one C3-C 12 -alkylene oxide, desirably C3-C 10 -alkylene oxide, more desirably C3-C8-alkylene oxide, preferably one or a mixture of propylene oxide and / or butylene oxide. Preferably, the alkylene oxide includes propylene oxide and / or butylene oxide. Thus, the alkylene oxide can be propylene oxide, or it can be butylene oxide, or it can be a mixture of propylene oxide and butylene oxide, or when containing propylene oxide and / or butylene oxide, the alkylene oxide can contain either or both of propylene oxide and butylene oxide and a mixture with higher alkylene oxides. In a desired embodiment, the alkylene oxide is a mixture including a C3-C4 alkylene oxide (i.e., propylene oxide or butylene oxide) and a C8-C 12 alkylene oxide mixture (preferably having a molar ratio of C3-C4 alkylene oxide to C8-C 12 of 2:1 to 20:1, 3:1 to 15:1, 4:1 to 12:1, more preferably 5:1 to 10:1 or 5:1 to 9:1). Particularly preferred alkylene oxide mixtures include propylene oxide with any one of 1-epoxyoctane, 1-epoxydecane, or 1-epoxydodecane, suitably within any of the above ratio ranges; or butylene oxide with any one of 1-epoxyoctane, 1-epoxydecane, or 1-epoxydodecane, suitably within any of the above ratio ranges.

[0057] The alkoxylated polyalkyleneimine contained in the composition of the present invention or prepared according to the method of the present invention can be linear or branched. In particular, for branched polyalkyleneimine, the branching can occur at its nitrogen moiety. Linear polyalkyleneimine is composed only of repeating units having the formula A; branched polyalkyleneimine has, in addition to linear repeating units, a tertiary nitrogen atom according to the formula B.

[0058]

[0059] wherein Q can be a C2-C8 alkylene group, suitably ethylene, propylene or butylene and preferably ethylene.

[0060] Polyalkyleneimines, especially polyethyleneimines, preferably having a degree of branching (DB) of more than 50, preferably more than 60. Polyalkyleneimines (including polyethyleneimines) can be characterized by their degree of branching (DB). For the definition of the degree of branching, reference is made to H. Frey et al., Acata Polym. 1997, 48, 30. The degree of branching DB is defined therein as

[0061] DB(%) = (T + Z) / (T + Z + L) x 100, where

[0062] T is the average number of terminally bound monomer units (primary amino groups),

[0063] Z is the average number of branched monomer units (tertiary amino groups),

[0064] L is the average number of linearly bound monomer units (secondary amino groups). T, Z and L can be determined via 13 13C-NMR in D2O. Reference is made to T. St Pierre and M. Geckle (1985) 13 13C-NMR Analysis of Branched Polyethyleneimine 13 13C-NMR analysis, Journal of Macromolecular Science: Part A-Chemistry, 22:5-7, 877-887, DOI: 10.1080 / 00222338508056641.

[0065] The degree of branching DB of the polyalkyleneimines, especially polyethyleneimines, according to the invention is preferably in the range from 55% to 95%, preferably in the range from 57% to 90% and more preferably in the range from 60% to 80%.

[0066] The polyalkyleneimines, preferably polyethyleneimines, used in the reaction mixture can desirably have a weight average molecular weight (MW) of from 300 to 20,000, for example from 300 to 15,000, suitably from 300 to 10,000, more suitably from 300 to 5000, preferably from 500 to 1500, more preferably from 500 to 1000 g / mol.

[0067] Polyalkyleneimines suitable for forming alkoxylated polyalkyleneimines can be prepared by various methods understood in the art. For example, polyethyleneimine can be prepared by ring-opening of aziridine under acid-catalyzed polymerization.

[0068] In various desired embodiments, the polyethyleneimine is preferably a branched polymer comprising groups represented by formulas C and D:

[0069] and / or

[0070] wherein n or m is typically from about 7 to about 500, such that the polyethyleneimine has a weight-average molecular weight (M w ) of from about 300 to about 20,000, such as from about 300 to 15,000, suitably 300 to 10,000, more suitably 300 to 5000, preferably 500 to 1500, more preferably 500 to 1000 g / mol. It is also contemplated that the polyethyleneimine can have any value or range of values (both whole and partial) within the ranges described above.

[0071] Preferably, the alkoxylated polyethyleneimine is derived from a branched polyethyleneimine. The polyethyleneimine is a branched polymer having the following exemplary structure:

[0072]

[0073] Still referring to the above exemplary structure, the branched structure of the polyethyleneimine provides primary, secondary, and tertiary amines. That is, the polyethyleneimine typically includes linear groups (L), dendritic groups (D), and terminal groups (T). The * in the above exemplary structure represents the remainder of the polyethyleneimine molecule.

[0074] In some embodiments, based on 100% of all the groups present in the branched polyethyleneimine, as determined by 13 13C-NMR in D2O, the branched polyethyleneimine contains: from about 20% to about 55%, or from about 30% to about 45% of linear groups (L); from about 10% to about 40%, or from about 20% to about 30% of dendritic groups (D); and from about 20% to about 55%, or from about 30% to about 45% of terminal groups (T). In additional non-limiting embodiments, all values and ranges of values (both whole and partial) within one or more of the above ranges are specifically contemplated herein.

[0075] Suitable alkoxylated polyethyleneimines can be derived from polyethyleneimines commercially available from BASF under the trade name and available commercially.

[0076] In a particularly preferred form of the invention, the alkoxylated polyalkylene imine, preferably the alkoxylated polyethylene imine, is derived from a polyol having a weight average molecular weight (M) of 500 to 10,000 g / mol. W ), preferably a branched polyethyleneimine, and the alkoxylation is provided by any of ethylene oxide, propylene oxide or butylene oxide, particularly preferably propylene oxide or butylene oxide and most preferably propylene oxide.

[0077] The alkoxylated polyalkylene imine, preferably the alkoxylated polyethylene imine, desirably has an OH / NH molar ratio of 0.20 to 0.35. The OH / NH ratio can be selected using 13 C NMR confirmed.

[0078] The composition comprising alkoxylated alkylene imine, preferably alkoxylated polyethylene imine according to the third aspect of the invention particularly preferably comprises <10 ppm, more particularly preferably <5 ppm, of alkylene oxide by weight, based on the weight of the alkoxylated polyalkylene imine in the composition. These concentrations can be determined by thermal desorption, wherein the released volatiles are quantified by gas chromatography-mass spectrometry. According to the present disclosure, the GC / MS used for calculating the values ​​is provided by Agilent. The system configuration is a GC-MS Kopplung (7890 / 5975 or 7890 / 5977) with an electron ionization ion source and a single quadrupole spectrometer.

[0079] The inventors have found that the composition comprising an alkoxylated polyalkyleneimine, preferably an alkoxylated polyethyleneimine, obtainable by the aforementioned method (including any preferred embodiments thereof) is useful for capturing gases having a pKa greater than 5. Preferably, the gas will be carbon dioxide. According to the use according to the invention, a gas having a pKa greater than 5, preferably carbon dioxide, will be captured from a gas or a gas mixture.

[0080] In a preferred embodiment of the use according to the invention, the alkoxylated polyalkyleneimines, preferably alkoxylated polyethyleneimines, can be used directly, as aqueous solution or incorporated into a liquid formulation.

[0081] In addition, once the alkoxylated polyalkyleneimine in the composition has been completely saturated with a gas having a pKa greater than 5, such as carbon dioxide, the composition may be subjected to a desorption step. The desorption step may be suitably performed by heating so that the gas (e.g., carbon dioxide) is released in a process in which the gas (e.g., carbon dioxide) is released and then more permanently sealed in a controlled environment. The desorption of gases (e.g., carbon dioxide) is well documented and known in the art. This absorption / desorption of gases (e.g., carbon dioxide) is referred to as an absorption / desorption cycle.

[0082] The inventors have found that compositions containing alkoxylated polyalkyleneimines are able to absorb carbon dioxide more rapidly. This is independent of whether the composition is a liquid composition (e.g., an aqueous solution containing an alkoxylated polyalkyleneimine) or is included as part of a solid article or product. Thus, compositions containing alkoxylated polyalkyleneimines are able to reach full capacity, i.e., be completely filled with CO2, in a shorter time interval, typically where the time is reduced by up to 80% or more compared to conventional alkoxylated polyalkyleneimines prepared by conventional routes. This means that the total time period of the absorption / desorption cycle can be reduced and the number of absorption / desorption cycles can be increased by at least 200%. This can have the benefit of reducing capital expenditure and process costs.

[0083] The increase in the rotation speed (i.e., the absorption / desorption cycle) is importantly caused by an increase in the uptake / absorption rate and the desorption rate.

[0084] More preferably, the gas or gas mixture is atmospheric air or any kind of exhaust flue gas. Typically, the exhaust flue gas can be, for example, the gas emitted from an industrial process (including a power plant), typically generated by the combustion of carbon-containing materials. Additionally, the exhaust flue gas can be generated by various other devices such as heating devices (including commercial boilers and domestic boilers) or other devices such as motion generating devices (e.g., the combustion engine of a vehicle). Capturing carbon dioxide from air typically means that any air in the atmosphere I can also include the air in an enclosed space (e.g., a building).

[0085] The following examples are intended to illustrate the invention and should not be construed in any way as limiting the scope of the invention.

[0086] Examples

[0087] Comparative Examples 1 - 3

[0088] Comparative Example 1

[0089] A 2 L glass flask equipped with a stirrer and a reflux condenser was charged with 465 g of polyethyleneimine (PEI, Mw 800 g / mol, amine value 18.2 mmol / g), and 500 g of methanol was added (300 rpm) while purging with nitrogen for 20 minutes, while heating the mixture to 30 °C. The temperature was maintained within 30 °C - 35 °C, and 147.3 g of propylene oxide (PO) was metered in over a period of 3 h. The mixture was stirred and gently refluxed at 40 °C overnight. Then the methanol was removed within 45 minutes. Finally, the temperature was raised to 80 °C for an additional 45 minutes and then a vacuum of 40 mbar was applied for 15 minutes. The resulting pale yellow mixture was quenched with nitrogen and cooled to room temperature (about 20 °C), and 615 g of a pale yellow viscous liquid was obtained.

[0090] Comparative Example 2

[0091] Charge a 2 L glass flask equipped with a stirrer and a reflux funnel with 470 g of polyethylenimine (PEI, Mw 1200 g / mol, amine value 17.9 mmol / g). Add (300 rpm) 115 g of water and 500 g of methanol, and purge with nitrogen for 20 minutes while heating the mixture to 30 °C. While maintaining the temperature within 30 °C - 35 °C, meteringly add 151.5 g of butylene oxide (BuO) over a 3 h period. Stir the mixture and reflux gently at 40 °C overnight. Then remove methanol and water while raising the temperature to 100 °C (90 minutes) and holding at 100 °C for 45 minutes, and then apply a vacuum of 40 mbar for 30 minutes. Quench the resulting pale yellow mixture with nitrogen and cool to room temperature (about 20 °C). Obtain 623.9 g of a pale yellow viscous liquid.

[0092] Comparative Example 3

[0093] Charge a 2 L glass flask equipped with a stirrer and a reflux funnel with 500 g of polyethylenimine (PEI, Mw 5000 g / mol, amine value 17.7 mmol / g), and add (300 rpm) 935 g of water, and purge with nitrogen for 20 minutes while heating the mixture to 50 °C. While maintaining the temperature within 50 °C - 65 °C, meteringly add 135 g of butylene oxide (BuO) over a 3 h period. Stir the mixture at 60 °C overnight. Then partially remove water while raising the temperature to 100 °C - 105 °C (30 minutes) and holding at 100 °C for 45 minutes, and then apply a vacuum of 40 mbar for 10 minutes. Quench the resulting pale yellow mixture with nitrogen and cool to room temperature (about 20 °C). Obtain 1250 g of a pale yellow viscous liquid, which is diluted with 20 g of water to obtain a 50% aqueous solution.

[0094] Examples 1 - 13 of the present invention

[0095] Example 1

[0096] Charge a 5 L stainless steel reactor equipped with a stirrer with 2700 g of polyethylenimine (PEI) (Mw 800 g / mol, amine value 18.2 mmol / g). Evacuate the reactor (60 mbar) and purge with nitrogen three times while increasing the temperature to 110 °C. Pressurize the reactor to 2 bar, and start the metering addition of propylene oxide (PO) with 125 g of PO within 5 minutes. While stirring at 150 rpm, meteringly add an additional 720 g of PO over a 3.5 h period. Raise the temperature to 120 °C and stir for another 3 hours. Then cool the reactor to 60 °C and reduce the pressure. Finally, treat the reactor at 100 mbar for 20 minutes and purge with nitrogen. Obtain 3551 g of a slightly pale yellow viscous liquid.

[0097] Example 2

[0098] Charge 2700 g of PEI (Mw 800 g / mol, amine value 18.2 mmol / g) into a 5 L stainless steel reactor equipped with a stirrer. Evacuate the reactor (60 mbar) and purge it with nitrogen three times while increasing the temperature to 100 °C. Pressurize the reactor to 2 bar and start the metered addition of 112 g of PO (propylene oxide) within 5 minutes. While stirring at 150 rpm, meter in an additional 700 g of PO over a 3-hour period. Raise the temperature to 115 °C and stir for an additional 3 hours. Then cool the reactor to 60 °C and reduce the pressure. Finally, treat the reactor at 100 mbar for 20 minutes and purge it with nitrogen. Obtain 3409 g of a slightly pale yellow viscous liquid.

[0099] Example 3

[0100] Charge 2700 g of PEI (Mw 800 g / mol, amine value 18.2 mmol / g) into a 5 L stainless steel reactor equipped with a stirrer. Evacuate the reactor (60 mbar) and purge it with nitrogen three times while increasing the temperature to 100 °C. Pressurize the reactor to 2 bar and start the metered addition of 125 g of BuO (butylene oxide) within 5 minutes. While stirring at 150 rpm, meter in an additional 760 g of BuO over a 3-hour period. Raise the temperature to 115 °C and stir for an additional 4 hours. Then cool the reactor to 60 °C and reduce the pressure. Finally, treat the reactor at 100 mbar for 20 minutes and purge it with nitrogen. Obtain 3581 g of a clear viscous liquid.

[0101] Example 4

[0102] Charge 2700 g of PEI (Mw 1200 g / mol, amine value 17.9 mmol / g) into a 5 L stainless steel reactor equipped with a stirrer. Evacuate the reactor (60 mbar) and purge it with nitrogen three times while increasing the temperature to 100 °C. Pressurize the reactor to 2 bar and start the metered addition of 117 g of PO (propylene oxide) within 5 minutes. While stirring at 150 rpm, meter in an additional 640 g of PO over a 3-hour period. Raise the temperature to 115 °C and stir for an additional 3 hours. Then cool the reactor to 60 °C and reduce the pressure. Finally, treat the reactor at 100 mbar for 20 minutes and purge it with nitrogen. Obtain 3452 g of a slightly pale yellow viscous liquid.

[0103] Example 5

[0104] Charge 2700 g of PEI (Mw 1200 g / mol, amine value 17.9 mmol / g) into a 5 L stainless steel reactor equipped with a stirrer. Evacuate the reactor (60 mbar) and purge it with nitrogen three times while increasing the temperature to 110 °C. Pressurize the reactor to 2 bar and start the metered addition of propylene oxide (PO) with 105 g of PO within 5 minutes. While stirring at 150 rpm, meter in an additional 400 g of PO over a 2.5-hour period. Raise the temperature to 115 °C and stir for another 3 hours. Then cool the reactor to 60 °C and reduce the pressure. Finally, treat the reactor at 100 mbar for 20 minutes and purge it with nitrogen. Obtain 3202 g of a slightly pale yellow viscous liquid.

[0105] Example 6

[0106] Charge 2700 g of PEI (Mw 1200 g / mol, amine value 17.9 mmol / g) into a 5 L stainless steel reactor equipped with a stirrer, followed by 470 g of water. Evacuate the reactor (60 mbar) and purge it with nitrogen three times while increasing the temperature to 100 °C. Pressurize the reactor to 2 bar and start the metered addition of propylene oxide (PO) with 117 g of PO within 5 minutes. While stirring at 150 rpm, meter in an additional 640 g of PO over a 3.5-hour period. Raise the temperature to 115 °C and stir for another 3 hours. Then cool the reactor to 60 °C and reduce the pressure. Finally, treat the reactor at 100 mbar for 10 minutes and purge it with nitrogen. Obtain 3913 g of a slightly pale yellow liquid.

[0107] Example 7

[0108] Charge 2700 g of PEI (Mw 5000 g / mol, amine value 17.7 mmol / g) into a 5 L stainless steel reactor equipped with a stirrer, followed by 385 g of water. Evacuate the reactor (60 mbar) and purge it with nitrogen three times while increasing the temperature to 100 °C. Pressurize the reactor to 2 bar and start the metered addition of butylene oxide (BuO) with 129 g of BuO within 5 minutes. While stirring at 150 rpm, meter in an additional 600 g of BuO over a 3.5-hour period. Raise the temperature to 120 °C and stir for another 3 hours. Then cool the reactor to 60 °C and reduce the pressure. Finally, treat the reactor at 100 mbar for 10 minutes and purge it with nitrogen. Obtain 3799 g of a clear liquid.

[0109] Example 8

[0110] Charge 2700 g of PEI (Mw 5000 g / mol, amine value 17.7 mmol / g) into a 5 L stainless steel reactor equipped with a stirrer. Evacuate the reactor (60 mbar) and purge it with nitrogen three times while increasing the temperature to 100 °C. Pressurize the reactor to 2 bar and start the metered addition of 105 g of propylene oxide (PO) over 5 minutes. While stirring at 150 rpm, meter in an additional 200 g of PO over a period of 1.5 hours. As a next step, meter in 380 g of butylene oxide (BuO) over 2 h, then raise the temperature to 120 °C and stir for another 3 h. Then cool the reactor to 60 °C and reduce the pressure. Finally, treat the reactor at 100 mbar for 20 minutes and purge it with nitrogen. Obtain 3380 g of a clear liquid.

[0111] Example 9

[0112] Charge 2700 g of PEI (Mw 1200 g / mol, amine value 17.9 mmol / g) into a 5 L stainless steel reactor equipped with a stirrer. Evacuate the reactor (60 mbar) and purge it with nitrogen three times while increasing the temperature to 100 °C. After adding 291 g of 1,2-epoxydecane (DO), pressurize the reactor to 2 bar. Perform the metered addition of propylene oxide (PO) (648 g) over 3.5 h. Raise the temperature to 115 °C and stir for another 3 h. Then cool the reactor to 60 °C and reduce the pressure. Finally, treat the reactor at 100 mbar for 20 minutes and purge it with nitrogen. Obtain 3636 g of a slightly pale yellow viscous liquid.

[0113] Example 10

[0114] Charge 2700 g of PEI (Mw 1200 g / mol, amine value 17.9 mmol / g) into a 5 L stainless steel reactor equipped with a stirrer. Evacuate the reactor (60 mbar) and purge it with nitrogen three times while increasing the temperature to 100 °C. After adding 201 g of 1,2-epoxydecane (DO), pressurize the reactor to 2 bar. Perform the metered addition of butylene oxide (BuO) (742 g) over 3.5 h. Raise the temperature to 115 °C and stir for another 3 h. Then cool the reactor to 60 °C and reduce the pressure. Finally, treat the reactor at 100 mbar for 20 minutes and purge it with nitrogen. Obtain 3640 g of a clear viscous liquid.

[0115] Example 11

[0116] Charge 2500 g of PEI (Mw 800 g / mol, amine value 18.2 mmol / g) into a 5 L stainless steel reactor equipped with a stirrer, followed by 590 g of water. Evacuate the reactor (60 mbar) and purge it with nitrogen three times while increasing the temperature to 100 °C. Pressurize the reactor to 2 bar and start the metered addition of butylene oxide (BuO) with 152 g of BuO within 5 minutes. While stirring at 150 rpm, meter in an additional 700 g of BuO over a 3-hour period. Raise the temperature to 120 °C and stir for an additional 3.5 hours. Then cool the reactor to 60 °C and reduce the pressure. Finally, treat the reactor at 100 mbar for 10 minutes and purge it with nitrogen. Obtain 3933 g of a clear liquid.

[0117] Example 12

[0118] Charge 2700 g of PEI (Mw 5000 g / mol, amine value 17.7 mmol / g) and 375 g of water into a 5 L stainless steel reactor equipped with a stirrer. Evacuate the reactor (60 mbar) and purge it with nitrogen three times while increasing the temperature to 100 °C. After adding 293 g of 1,2-dodecene oxide (DDO), pressurize the reactor to 2 bar. Perform the metered addition of propylene oxide (PO) (462 g) over 3.5 hours. Raise the temperature to 115 °C and stir for an additional 3 hours. Then cool the reactor to 60 °C and reduce the pressure. Finally, treat the reactor at 200 mbar for 10 minutes and purge it with nitrogen. Obtain 3826 g of a slightly pale yellow viscous liquid.

[0119] Example 13

[0120] Charge 500 g of polyethylenimine (PEI, Mw 5000 g / mol, amine value 17.7 mmol / g) into a 2 L glass flask equipped with a stirrer and a reflux funnel, and add (300 rpm) 342 g of water, and purge with nitrogen for 20 minutes while heating the mixture to 50 °C. While maintaining the temperature within 50 °C - 65 °C, meter in 135 g of butylene oxide (BuO) over a 3-hour period. Stir the mixture at 60 °C overnight. Then partially remove the water while raising the temperature to 100 °C - 105 °C (30 minutes) and holding at 100 °C for 30 minutes, and then apply a vacuum of 40 mbar for 10 minutes. Quench the resulting pale yellow mixture with nitrogen and cool to room temperature (about 20 °C). Obtain 825 g of a pale yellow viscous liquid, which is diluted with 445 g of water to obtain a 50% aqueous solution.

[0121] In the descriptions of Comparative Examples 1 - 3 and Examples 1 - 13, the mention of the amine value refers to polyethylenimine before alkoxylation.

[0122] Table 1

[0123]

[0124]

[0125] In Table 1, the reference to amine value refers to the amine value of the alkoxylated polyethyleneimine. The reference to PO means propylene oxide, and the reference to BuO means butylene oxide.

[0126] The alkoxylated polyethyleneimines prepared in Examples 1 to 13 and Comparative Examples 1 to 3 were evaluated using the equilibrium and absorption of a 15% CO2 gas mixture containing 5% O2 and 80% N2 at 40 °C. The results are presented in Table 2.

[0127] Determination of the equilibrium loading with CO2

[0128] The equilibrium loading was determined in a bubble column reactor as described in: BRECHTEL, K. Einfluss der Molekülstruktur auf die - Abtrennung mit aus Rauchgasen fossiler befeuerter Kraftwerke. Dissertation / PhD, University of Stuttgart ( Stuttgart), 2011; A. Amine und Aminmischungen zur - Absorption aus Kraftwerksrauchgasen und ihr Energiebedarf zur Regeneration Dissertation / PhD, University of Stuttgart ( Stuttgart), 2013].

[0129] Therein, 0.15 kg of the sample was diluted with 0.15 kg of water to obtain a 50% aqueous solution. The sample was heated in a water bath on an adjustable hot plate and exposed to a synthetic flue gas stream at 2 l / min, which had a composition of 15% C=2, 5% O2 and 80% N2 by volume. The flue gas was injected into the sample via a frit (pore size 1) using a mass flow controller, thus achieving good mixing and a large mass transfer area. The exiting (excess) low - CO2 gas stream was fed via a reflux and sample gas cooler to an infrared gas analyzer. The reflux cooler condensed the evaporated water or solvent and fed it back into the sample. The gas composition was continuously measured with the infrared gas analyzer and recorded via a computer interface.

[0130] Then a sample of mass [kg] is equilibrated with the CO2 concentration in the flue gas or with the current CO2 partial pressure. The volume of CO2 absorbed by the solvent [m] is derived from the integrated formation over time [min]. The inlet flue gas volumetric flow rate [l / min] is constant. Then the equilibrium loading is calculated in terms of weight % of CO2 relative to the mass of the 50% sample solution. For this purpose, the equilibrium loading is determined at a temperature of 50 °C.

[0131] All carbon dioxide absorbents used (alkoxylated polyethyleneimine, polyethyleneimine or ethanolamine) were used in the test work as 50% aqueous solutions by weight.

[0132] The rotation speed (i.e., the adsorption / desorption cycle) is importantly generated by the uptake / absorption rate and the desorption rate.

[0133] Table 2

[0134]

[0135]

[0136] Compared to the comparative alkoxylated polyethyleneimine and the non-alkoxylated amine containing monoethanolamine (MEA) (ethoxylated ammonia), the alkoxylated polyethyleneimine of the present invention demonstrates a significantly improved ability to absorb carbon dioxide. Although the non-alkoxylated amine and ethanolamine show a higher total CO2 absorption capacity, the cycle speed (i.e., the rotation speed or rate of the absorption / desorption cycle) and the absorption volume per time are much lower.

Claims

1. Use of a composition comprising an alkoxylated polyalkyleneimine for capturing a gas having a pKa greater than 5, preferably carbon dioxide, from a gas or gas mixture, wherein the composition is obtainable by a process comprising the following steps: (a) Providing a reaction mixture comprising (i) a polyalkyleneimine; and (ii) an alkylene oxide; (b) Reacting the (i) polyalkyleneimine with the (ii) alkylene oxide at a temperature of at least 50 °C; and (c) Optionally diluting the product of step (b), wherein the molar ratio of alkylene oxide to NH of the polyalkyleneimine in the reaction mixture is from 0.1 to 0.35, and wherein the reaction mixture comprises < 55% by weight, preferably < 30% by weight, of water based on the weight of the reaction mixture, and the reaction mixture comprises less than 5% by weight, preferably less than 1% by weight, of a polar organic solvent based on the weight of the reaction mixture.

2. Use according to claim 1, wherein The alkoxylated polyalkyleneimine is an alkoxylated polyethyleneimine, and the (i) polyalkyleneimine in step (a) is polyethyleneimine.

3. Use according to claim 1 or claim 2, wherein The reaction mixture contains <20% by weight of water, more preferably <10% by weight of water, based on the weight of the reaction mixture.

4. Use according to any one of claims 1 to 3, wherein The reaction mixture does not contain any polar organic solvents.

5. Use according to any one of claims 1 to 4, wherein The reaction mixture is solvent-free and contains water only in the amount of a reactant, suitably up to 1 mole of water per mole of the NH groups of the polyalkyleneimine, preferably polyethyleneimine.

6. Use according to any one of claims 1 to 5, wherein In step (a), the (i) polyalkyleneimine, preferably polyethyleneimine, is provided at a temperature of at least 50 °C, preferably 60 °C to 140 °C, more preferably 60 °C to 110 °C, and the (ii) alkylene oxide is provided at a temperature of at least 50 °C, preferably 60 °C to 100 °C and combined with the (i) polyalkyleneimine, preferably polyethyleneimine, to form the reaction mixture.

7. Use according to any one of claims 1 to 6, wherein The reaction in step (b) is carried out at a temperature of 60 °C to 140 °C, preferably 80 °C to 130 °C.

8. Use according to any one of claims 1 to 7, wherein The reaction in step (b) is carried out at a pressure greater than 1.25 bar, preferably at a pressure of 1.5 to 3 bar.

9. Use according to claim 8, wherein The dilution in step (c) is carried out after the reaction mixture has been depressurized.

10. Use according to any one of claims 1 to 9, wherein The weight ratio of alkylene oxide to NH of the polyalkyleneimine, preferably polyethyleneimine, in the reaction mixture is 0.15 to 0.

32.

11. Method according to any one of claims 1 to 10, wherein The alkylene oxide includes propylene oxide and / or butylene oxide.

12. Use according to any one of claims 1 to 11, wherein The polyalkyleneimine, preferably polyethyleneimine, and the reaction mixture have a weight-average molecular weight (M W ) of from 300 to 10,000 g / mol, preferably from 500 to 1500 g / mol.

13. Use according to any one of claims 1 to 12, wherein The polyalkyleneimine, preferably polyethyleneimine, in the reaction mixture is branched.

14. Use according to any one of claims 1 to 13, wherein, The alkoxylated polyalkyleneimine, preferably alkoxylated polyethyleneimine, has an OH / NH molar ratio of 0.20 to 0.

35.

15. Use according to any one of claims 1 to 14, wherein, The composition contains <10 ppm by weight, preferably <5 ppm by weight, of alkylene oxide, based on the weight of the alkoxylated polyalkyleneimine in the composition.

16. Use according to any one of claims 1 to 15, wherein, The alkoxylated polyalkyleneimine, preferably alkoxylated polyethyleneimine, is incorporated into a formulation for direct carbon dioxide capture.

17. Use according to any one of claims 1 to 16, wherein, The gas or gas mixture is atmospheric air or flue gas.

18. A method for preparing a composition comprising an alkoxylated polyalkyleneimine, the composition obtainable by a method comprising the following steps: (a) Providing a reaction mixture comprising (i) a polyalkyleneimine, preferably a polyethyleneimine; and (ii) an alkylene oxide, the alkylene oxide comprising propylene oxide and / or butylene oxide; (b) Carrying out the reaction between the (i) polyalkyleneimine, preferably polyethyleneimine and the (ii) alkylene oxide at a temperature of at least 50 °C, (c) Optionally diluting the product of step (b), wherein the molar ratio of the alkylene oxide to the NH of the polyalkyleneimine, preferably polyethyleneimine, in the reaction mixture is from 0.1 to 0.35, and wherein the reaction mixture comprises < 55% by weight of water, preferably < 30% by weight of water, based on the weight of the reaction mixture, and the reaction mixture comprises less than 5% by weight, preferably less than 1% by weight, of a polar organic solvent based on the weight of the reaction mixture.

19. The method according to claim 18, the method comprising any one of the features in any one of claims 2 to 10 and any one of claims 12 to 17.

20. A composition comprising an alkoxylated polyalkyleneimine, the composition obtainable by the method as claimed in claim 18.

21. The composition according to claim 20, the composition comprising any one of the features in any one of claims 2 to 10 or any one of claims 12 to 17.

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