Method for carbon dioxide capture

Abstract

The present invention relates to a novel sorption medium for removing CO2 from a gas mixture. In particular, the present invention relates to a method for separating CO2 from a gas mixture comprising CO2, said method comprising the steps of: a) providing a gas mixture comprising CO2; b) contacting the gas 5 mixture with at least one sorption medium under conditions suitable for the sorption medium to sorb the CO2 to obtain a CO2-enriched sorption medium; c) desorbing CO2 from the CO2-enriched sorption medium under conditions suitable for the CO2-enriched sorption medium to desorb CO2 to regenerate the sorption medium and obtain CO2; wherein said sorption medium comprises aminolysed 10 monomers and / or oligomers of Polyethylene Terephthalate (PET) of formula (I) herein.

Description

[0001] 84943PC01

[0002] 1

[0003] METHOD FOR CARBON DIOXIDE CAPTURE

[0004] Technical field of the invention

[0005] The present invention relates to the field of carbon dioxide (CO2) capture. In particular, the present invention relates to a method for separating CO2 from a gas mixture comprising CO2 using aminolysed monomer and / or oligomers of Polyethylene Terephthalate (PET) as a sorption medium. The PET derived complexes may capture CO2 from various sources, including flue gas stream and direct air capture, and even humid conditions and high temperatures.

[0006] Background of the invention

[0007] It has been estimated that to reach carbon neutrality by 2050, we must capture from 1.5 to 2.6 billion metric tons (Gt) of carbon dioxide annually. Therefore, any useful CO2-sorbents material must be produced, at least, in the order of Mt per year from cheap and abundant sources. Notably, PET upcycling for CO2 capture has been explored by using pyrolysis to produce activated carbons (Wang, J. et al. (2020) and Li, S. et al. (2022)). However, this process requires energy intensive pyrolysis (600-900 °C) and strictly anaerobic conditions to generate a high-quality product.

[0008] Due to their lower energy requirements for regeneration (172 kJ / mol for MEA) and high CO2 sorption capacity (0.4-0.6 moles of CO2 per mole of MEA, EDA), amine-based sorbents are commonly used in aqueous carbon capture. Cyclic amines or diamines have also been utilized as CO2 sorbents (WO09125943 Al, WO13075697 Al). However, one of the key limitations of MEA and similar amine- based sorbents is sorbent loss at absorption step and degradation under thermal regeneration conditions. This leads to significant operational costs for carbon capture.

[0009] Hence, an improved CO2 sorbent would be advantageous, and in particular a more efficient and thermally and chemically stable sorbent would be advantageous. 84943PC01

[0010] Summary of the invention

[0011] Thus, an object of the present invention relates to a method for capturing CO2. In particular, it is an object of the present invention to provide a method suitable for cyclic sorption / desorption of CO2 that solves the above-mentioned problems of the prior art with sorbent loss or sorbent degradation, e.g., during thermal regeneration. Another object of the present invention is to provide a method for capturing CO2, wherein the sorbent has a relatively low regeneration temperature compared with other CO2 sorbents (900°C for calcium oxide (CaO) and magnesium oxide (MgO); 300-400 °C for zeolites). Furthermore, it is an object of the present invention to provide a method for capturing CO2, wherein the sorption medium is available from low-cost recycled material.

[0012] Thus, one aspect of the invention relates to a method for separating CO2 from a gas mixture comprising CO2, said method comprising the steps of: a) providing a gas mixture comprising CO2; b) contacting the gas mixture with at least one sorption medium under conditions suitable for the sorption medium to sorb the CO2 to obtain a CO2-enriched sorption medium; c) desorbing CO2 from the CCh-enriched sorption medium under conditions suitable for the CCh-enriched sorption medium to desorb CO2 to regenerate the sorption medium and obtain CO2; wherein said sorption medium comprises a compound of formula (I): wherein 84943PC01

[0013] 3

[0014] R1, R2, and R3are independently selected from the group consisting of H and C1-C4 alkyl, or wherein Rx-N-R2forms a heterocycle selected from the group consisting of aziridine, azetidine, pyrrolidine, piperidine, and morpholine,

[0015] A is independently selected from the group consisting of an optionally substituted C1-C14 alkylene, a bond, wherein n is an integer selected from the range of 0-4, m is an integer selected from the range of 1-3, p is an integer selected from the range of 0-16,

[0016] Y is N-R4or O, wherein R4is selected from the group consisting of H, C1-C4 alkyl, and -CH2CH2NH2, q is an integer selected from the range of 0- 4,

[0017] X is N-R3or O, and

[0018] B is A or -CH2-CH2-.

[0019] Another aspect of the present invention relates to the use of a compound of formula (I) : 84943PC01 wherein

[0020] R1, R2, and R3are independently selected from the group consisting of H and C1-C4 alkyl, or wherein Rx-N-R2forms a heterocycle selected from the group consisting of aziridine, azetidine, pyrrolidine, piperidine, and morpholine,

[0021] A is independently selected from the group consisting of an optionally substituted C1-C14 alkylene, a bond, wherein n is an integer selected from the range of 0-4, m is an integer selected from the range of 1-3, p is an integer selected from the range of 0-16, 84943PC01

[0022] 5

[0023] Y is N-R4or O, wherein R4is selected from the group consisting of H, C1-C4 alkyl, and -CH2CH2NH2, q is an integer selected from the range of 0- 4,

[0024] X is N-R3or O, and

[0025] B is A or -CH2-CH2-. to sorb CO2 from a gas mixture comprising CO2.

[0026] Brief description of the figures

[0027] Figure 1 shows the reaction scheme and conditions for PET aminolysis using ethylene diamine (EDA).

[0028] Figure 2 shows thermal stability of BAETA-CO2 adduct compared to benchmark systems such as MEA and ESA. Amine-based sorbents such as ethylenediamine (EDA), ethanolamine (MEA), and 1,8-Diaminonaphthalene resulted in full decomposition at 100 °C while desorption of CO2. On the other hand, BAETA was releasing CO2 up to 200 °C, at which point it started to polymerize. Decomposition only started at 300 °C.

[0029] Figure 3A shows the CO2 uptake using BAETA at different temperatures. The experiment was performed using 100% CO2 90mL / min flow, at temperatures from 25 °C to 180 °C for 210 min.

[0030] Figure 3B shows CO2 uptake at different temperatures using a sample of oligomers obtained by aminolysis of PET using EDA. The experiment was performed using 100% CO2 90mL / min flow, at temperatures from 25 °C to 180 °C for 210 min.

[0031] Figure 3C shows CO2 uptake using BAETA at a constant temperature of 150 °C using a mixture of different CO2 and N2 gas mixtures. The experiment was performed using 90mL / min flow, at a temperature of 150 °C for 210 min.

[0032] Figure 3D shows BAETA efficiency after exposing it to oxidative stress: lh, 100 °C 90 ml / of air flow; followed by CO2 sorption at 150 °C at 90 ml / min with 100% CO2 flow and 90 ml / min N2 flow for CO2 desorption at 150 °C.

[0033] Figure 3E shows the BAETA recyclability profile at 150 °C, 90 mL / min flow of 15% CO2 + 85% N2 for sorption, 100% N2 for desorption. Both sorption and desorption were at 150 °C. Sorption was 2 min and desorption was 5 min with total cycle duration of 7 min. Top panel: Recyclability during 500 repetitive carbon 84943PC01

[0034] 6 dioxide capture cycles. Bottom panel: "zoomed in" recyclability profile showing full cycle of 7 min.

[0035] Figure 3F shows CO2 uptake and recyclability during 40 cycles using BAETA at a constant 150 °C temperature using a gas mixture of 15% CO2 and 85% N2 for absorption and 100% N2 for desorption. The experiment was performed using 90mL / min flow.

[0036] Figure 3G shows CO2 uptake dependance on relative humidity levels (RH%). Figure 3H shows CO2 uptake and recyclability during 2 cycles using a palletized BAETA sample at a constant temperature of 150 °C using 100% CO2 for absorption and 100% N2 for desorption. The experiment was performed using 90mL / min flow. A picture of the palletized BAETA sample is also shown in figure 3H.

[0037] Figure 4A shows BAETA CO2 physisorption profile using TGA at 25 °C at 90 mL / min flow for 180 cycles.

[0038] Figure 4B shows BAETA CO2 physisorption profile using TGA at 25 °C at 90 mL / min flow for 20 cycles followed by thermal regeneration at 150 °C and additional 20 cycles.

[0039] Figure 5 shows CO2 concentration depending on time during the BAETA sorbent DAC experiment. The grey line shows the CO2 concentration data obtained from CO2 sensor 1 (no DAC, reference), whereas the black line shows data from CO2 sensor 2 (after DAC using the BAETA sorbent filter).

[0040] Figure 6 shows the chemical structures, reaction conditions, yields, and melting points of the terephthalamide-derived sorbents synthesized from the reaction of PET with diamines.

[0041] Figure 7 shows the CO2 capture profiles of some tested PET-derived sorbents.

[0042] Figure 8 shows the recyclability profile of Nl,N4-bis(8- aminooctyl)terephthalamide at 150 °C, 90 mL / min flow; 100 cycles: 100% CO2 for sorption, 100% N2 for desorption; following 150 cycles 15% CO2 + 85% N2 for sorption, 100% N2 for desorption. Both sorption and desorption were at 150 °C. Sorption was 2 min and desorption was 20 min for the first 42 cycles and then time was reduced to 5 min. 100 cycles were performed with 100% CO2 flow; then CO2 concentration was reduced to 15% to mimic flue gas as cycles continued to 250. Top panel: Recyclability during 250 repetitive carbon dioxide capture cycles. Bottom panel: "zoomed in" recyclability profile showing full cycle of 7 min. 84943PC01

[0043] 7

[0044] Figure 9 shows plots of maximum CO2 uptake (black) of pelletized BAETA and BAETA CO2 capture efficiency (grey, weighted by the binder composition) over varying methyl cellulose amounts.

[0045] Figure IDA shows the thermal stability profile of pellets of BAETA-CO2 mixed with 50 wt% methyl cellulose binder.

[0046] Figure 1OB shows cyclic oxidative stability of pellets of BAETA-CO2 mixed with 50 wt% methyl cellulose binder. Repeated exposure to air at 100 °C for 60 min; CO2 capture performed at 150 °C, 90 mL / min 100% CO2 flow for sorption and 100% N2 for desorption, 90 mL / min flow.

[0047] Figure 11A shows CO2 capture at 150 °C and in the presence of water vapour and desorption under steam conditions. CO2 concentration (in ppm) (solid line) and humidity levels (in RH%) (dashed line) are plotted against time (in min). The experiment was performed using a pre-mixed 15% CO2 + 85% N2 gas mixture at 150 °C with 5 mL / min gas flow, up to 15 wt% capture based on the weight of BAETA used.

[0048] Figure 11B shows the CO2 concentration (in ppm) as a function of time (in min). Desorption was conducted using humidified air, which was passed through heating jacket (120-130 °C) at a flow rate of 50 mL / min showing up to 5 wt% of CO2 desorbed.

[0049] Figure 12 shows structural changes of BAETA-CO2 adduct CO2 desorption using vacuum and temperature at different periods of time.13C-NMR data (left),XH-NMR data (right). The NMR spectra were recorded in D2O.

[0050] The present invention will now be described in more detail in the following.

[0051] Detailed description of the invention

[0052] Definitions

[0053] Prior to discussing the present invention in further details, the following terms and conventions will first be defined:

[0054] Carbon dioxide

[0055] Carbon dioxide is a chemical compound with the chemical formula CO2. It is a significant greenhouse gas in Earth's atmosphere, contributing to the greenhouse effect by trapping heat. Carbon dioxide thereby plays a crucial role in regulating 84943PC01

[0056] 8

[0057] Earth's temperature. Carbon dioxide is produced by the respiration of animals, the combustion of organic matter, and various industrial processes, such as combustion of fossil fuels, cement production, steel manufacturing, and oil refining. In the present context, 'CO2' and 'carbon dioxide' are used interchangeably.

[0058] Gas mixture comprising CO2

[0059] In the present context, the term 'Gas mixture comprising CO2' refers to a CO2 gas often with one or more different gases that are mixed together without any chemical bonding between them, however, it may also refer to pure CO2 gas. Each gas in the mixture retains its own chemical properties. A gas mixture comprising CO2 includes but is not limited to air, flue gas, post-combustion gas mixture, biogas and gas mixtures obtained through oxy-fuel combustion.

[0060] Air or ambient air is the gas mixture that surrounds the Earth. It is primarily composed of nitrogen (N2, about 78 %), oxygen (O2, about 21 %) and other gases (about 1 %), including argon, carbon dioxide, neon, and helium. In Direct Air Capture (DAC) applications, the gas mixture will preferably be air.

[0061] Flue gas is the exhaust gas that is emitted from the combustion process in industrial facilities, power plants, and other combustion systems. It is produced from the burning of fossil fuels such as coal, oil, natural gas, and biomass in boilers, furnaces, and other combustion equipment. Flue gas typically contains carbon dioxide (CO2), water vapor (H2O), nitrogen oxides (NOX), sulphur oxides (SOx), carbon monoxide (CO), and other trace pollutants.

[0062] Post-combustion gas mixture refers to the gases that are emitted after the combustion process in engines, power plants, or industrial facilities. It is produced from the burning of fossil fuels such as coal, oil, natural gas, and biomass in various combustion systems. Post-combustion gas mixture typically includes carbon dioxide (CO2), water vapor (H2O), nitrogen oxides (NOX), sulphur oxides (SOX), carbon monoxide (CO), unburned hydrocarbons, and other trace gases. Biogas is produced through the anaerobic digestion of organic matter by microorganisms. It is generated from the decomposition of organic materials like agricultural waste, manure, municipal waste, plant material, sewage, green waste, or food waste. Biogas primarily consists of methane (CF ) and carbon dioxide (CO2), with small amounts of other gases such as hydrogen sulphide (H2S) and ammonia (NHs). 84943PC01

[0063] 9

[0064] Oxy-fuel combustion is a process where fuel is burned using pure oxygen or a mixture of oxygen and recirculated flue gas instead of air. The gas mixtures obtained through oxy-fuel combustion primarily consists of carbon dioxide (CO2) and water vapor (H2O).

[0065] In an embodiment, the gas mixture comprising CO2 is an industrial gas mixture.

[0066] Sorption medium

[0067] A 'sorption medium' is a material used to capture substances through the processes of adsorption or absorption. Absorption involves the uptake of substances into the volume of the sorbent, while adsorption involves the accumulation of substances on the surface of the sorbent. In the present context, the captured substance is primarily CO2. As demonstrated in example 3, the sorption medium of the present invention can both absorb CO2 though chemisorption and adsorb CO2 though physisorption. The sorption medium of the present invention comprises a compound of formula (I): wherein

[0068] R1, R2, and R3are independently selected from the group consisting of H and C1-C4 alkyl, or wherein Rx-N-R2forms a heterocycle selected from the group consisting of aziridine, azetidine, pyrrolidine, piperidine, and morpholine,

[0069] A is independently selected from the group consisting of an optionally substituted C1-C14 alkylene, a bond, 84943PC01

[0070] 10 wherein n is an integer selected from the range of 0-4, m is an integer selected from the range of 1-3, p is an integer selected from the range of 0-16,

[0071] Y is N-R4or O, wherein R4is selected from the group consisting of H, C1-C4 alkyl, and -CH2CH2NH2, q is an integer selected from the range of 0- 4, X is N-R3or O, and

[0072] B is A or -CH2-CH2-.

[0073] The compound of formula (I) and formula (II) comprises at least two groups called 'A'. These groups are independently selected from the group consisting of an optionally substituted C1-C14 alkylene, a bond, , and

[0074] , wherein n is an integer selected from the range of

[0075] 0-4, m is an integer selected from the range of 1-3, p is an integer selected from the range of 0-16, Y is N-R4or O, wherein R4is selected from the group 84943PC01

[0076] 11 consisting of H, C1-C4 alkyl, and -CH2CH2NH2. Thus, the compound of formula (I) or (II) may be asymmetrical by having different 'A' groups on each side, i.e. each individual A may be independently selected. Said asymmetrical compounds are generated by using at least two different diamines during the aminolysis of PET. The compound of formula (I) or formula (II) is preferable symmetrical, i.e., the same diamine is added to each side of the terephthalic scaffold. Likewise, for each side of the compound, R1, R2, and R3are independently selected from a specified group. Thus, R1on one side may be different from R1on the other side; the same applies to R2and R3. Additionally, within the same molecule, R1, R2, and R3may also differ from each other.

[0077] The sorption medium might also be a mixture of compounds of formula (I). As demonstrated in example 3, both BAETA and oligomers obtained by aminolysis of PET using EDA could capture CO2. Thus, the sorption medium might be a mixture of a monomer and multiple different oligomers.

[0078] Sorb

[0079] The term 'Sorb' refers to the process of taking up or holding a substance, either by absorption or adsorption. In the present context, the substance is CO2. Absorption involves the uptake of substances into the volume of the sorbent, while adsorption involves the accumulation of substances on the surface of the sorbent. The sorption medium can sorb and desorb CO2 either in the same place or at different zones. The term 'Sorption zone' refers to a specific area or region within a system where the process of sorption (absorption or adsorption) occurs. If sorption is conducted in the same place as desorption, sorption / desorption is regulated by e.g. temperature and / or gas flow.

[0080] Desorb

[0081] The term 'Desorb' refers to the process of releasing or removing a substance that has been absorbed or adsorbed onto a surface (adsorption) or within a material (absorption). In the present context, the substance is CO2. The sorption medium of the present invention may desorb CO2 directly as a gas. However, the term 'desorb' also encompasses scenarios where CO2 reacts with another compound before leaving the sorption medium. In such cases, the resulting compound that detaches from the sorption medium contains CO2. 84943PC01

[0082] 12

[0083] The term 'Desorption zone' refers to a specific area or region within a system where the process of desorption occurs. If desorption is conducted in the same place as sorption, sorption / desorption is regulated by temperature and / or gas flow. Preferably the desorption is performed under steam, water vapor, CO2 gas flow, nitrogen gas flow, inert gas flow, or argon gas flow.

[0084] COz-enriched sorption medium

[0085] The term 'CCh-enriched sorption medium' refers to a sorption medium that has sorbed CO2 from the gas mixture comprising CO2. In the present context, the sorption medium sorbs CO2 using amine groups. A CCh-enriched sorption medium might be fully saturated with CO2 if every sorbent in a sorption medium mixture has sorbed CO2, but the term also covers sorption mediums that are not fully saturated, i.e., sorption mediums wherein some sorbent has sorbed CO2 whereas others have not.

[0086] C1-C4 alkyl

[0087] The term 'C1-C4 alkyl' refers to alkyl groups that contain between one and four carbon atoms. Ci Alkyl is an methyl group (CHs-), C2 Alkyl is an ethyl group (CH3CH2-); C3 Alkyl is either an n-propyl group (CH3CH2CH2-) or an isopropyl group ((CHS) 2CH-), and C4 Alkyl is any one of the compounds selected from the group consisting of n-butyl group (CH3CH2CH2CH2-), isobutyl group ((CH3)2CHCH2-), sec-butyl group (CH3CH2(-CH3)CH-), and tert-butyl group ((CH3)3C-).

[0088] Optionally substituted C1-C14 alkylene

[0089] An 'optionally substituted C1-C14 alkylene' refers to an alkylene group containing between 1 and 14 carbon atoms, which may or may not have additional substituents attached. An alkylene group is a bivalent radical derived from an alkene by opening of the double bond or derived from an alkane by removing two hydrogen atoms from different carbon atoms, resulting in a structure with two free valencies. It has the general formula -(CH2)n-. The substituent on the optionally substituted C1-C14 alkylene may be selected from the group consisting of C1-C4 alkyl, halide, NH2, carboxylic acid, amino acid, C1-C5 amide, and C1-C5 ester, or where two adjacent alkyl substituents unite to form a 5-6 membered ring. The amino acid and C1-C5 amide can bind to the C1-C14 alkylene using a -CO 84943PC01 or -CN bond, whereas the C1-C5 ester can bind to the C1-C14 alkylene using a -CO bond. The optionally substituted C1-C14 alkylene may have one or more substituents, e.g., 2 or 3 substituents. Preferably, the optionally substituted Ci- C14 alkylene does not have a substituent.

[0090] BAETA

[0091] The term 'BAETA' is used to describe a monomer obtained by aminolysis of PET using Ethylene diamine (EDA). The full name of BAETA is N,N'-Bis(2- aminoethyl)terephthalamide or N,N'-Di(2-aminoethyl)terephthalamide. BAETA has the following chemical structure (formula (IV)):

[0092] Relative humidity (RH)

[0093] In the present context relative humidity represents the amount of water vapour in a gas as compared to the maximum amount of water vapour said gas could potentially contain. RH is often expressed as a percentage and is calculated as the partial pressure of water vapour (p) in the gas divided by the saturation vapour pressure (ps) of the gas, i.e. RH = 100% ■ p / ps. RH can be controlled by the gas temperature, as e.g. warm air can contain more vapour than cold air (a well- known meteorological phenomenon). Thus, in the present context RH may be controlled by controlling the temperature. There may be other ways of controlling or adjusting RH, e.g. by changing the composition of the gas mixture, pressure changes, volume changes, etc. In the present context RH is thus RH as measured in gas mixture comprising CO2 in the absorption / desorption zone, whether this is the same zone or not.

[0094] The present inventors have surprisingly found that the incorporation of EDA into the PET scaffold results in compounds that are more thermal stable than 84943PC01

[0095] 14 conventional used amine scrubbers (EDA, MEA and 1,8-diaminonaphthalene) when CO2 is sorbed (Fig. 2). The higher thermal stability of the sorbents of the present invention ensures that they remain effective and intact at elevated temperatures, making them more reliable for prolonged CO2 capture operations. It is likely that other compounds obtained through aminolysis of PET would have similar technical effects. Further, the sorbent has a relatively low regeneration temperature (approximately 120-130 °C) compared with other CO2 sorbents (900°C for calcium oxide (CaO) and magnesium oxide (MgO); 300-400 °C for zeolites). Consequently, integrating BAETA into flue gas treatment infrastructures could pave the way for more energy-efficient and cost-effective carbon capture solutions. It is a further (technical and commercial) advantage that the sorbents may be obtained from waste PET rather than e.g. fossil sources.

[0096] Thus, an aspect of the present invention relates to a method for separating CO2 from a gas mixture comprising CO2, said method comprising the steps of: a) providing a gas mixture comprising CO2; b) contacting the gas mixture with at least one sorption medium under conditions suitable for the sorption medium to sorb the CO2 to obtain a CO2-enriched sorption medium; c) desorbing CO2 from the CCh-enriched sorption medium under conditions suitable for the CCh-enriched sorption medium to desorb CO2 to regenerate the sorption medium and obtain CO2; wherein said sorption medium comprises a compound of formula (I): 84943PC01

[0097] 15 wherein

[0098] R1, R2, and R3are independently selected from the group consisting of H and C1-C4 alkyl, or wherein Rx-N-R2forms a heterocycle selected from the group consisting of aziridine, azetidine, pyrrolidine, piperidine, and morpholine,

[0099] A is independently selected from the group consisting of an optionally substituted C1-C14 alkylene, a bond, wherein n is an integer selected from the range of 0-4, m is an integer selected from the range of 1-3, p is an integer selected from the range of 0-16,

[0100] Y is N-R4or O, wherein R4is selected from the group consisting of H, C1-C4 alkyl, and -CH2CH2NH2, q is an integer selected from the range of 0- 4,

[0101] X is N-R3or O, and

[0102] B is A or -CH2-CH2-.

[0103] An alternative aspect of the present invention relates to a method for separating CO2 from a gas mixture comprising CO2, said method comprising the steps of: a) providing a gas mixture comprising CO2; 84943PC01

[0104] 16 b) contacting the gas mixture with at least one sorption medium under conditions suitable for the sorption medium to sorb the CO2 to obtain a CO2-enriched sorption medium; c) desorbing CO2 from the CCh-enriched sorption medium under conditions suitable for the CCh-enriched sorption medium to desorb CO2 to regenerate the sorption medium and obtain CO2; wherein said sorption medium comprises a compound of formula (la): wherein

[0105] R1and R2are independently selected from the group consisting of H and C1-C4 alkyl, or wherein Rx-N-R2forms a heterocycle selected from the group consisting of aziridine, azetidine, pyrrolidine, piperidine, and morpholine,

[0106] A is selected from the group consisting of an optionally substituted C1-C10 alkylene,

[0107] , and 84943PC01 wherein n is an integer selected from the range of 0-4, m is an integer selected from the range of 1-3, p is an integer selected from the range of 0-16,

[0108] Y is N-R4or O, wherein R4is selected from the group consisting of H and C1-C4 alkyl, q is an integer selected from the range of 0- 4,

[0109] X is NH or O, and

[0110] B is A or -CH2-CH2-.

[0111] Another aspect of the present invention relates to the use of a compound of formula (I) : wherein

[0112] R1, R2, and R3are independently selected from the group consisting of H and C1-C4 alkyl, or wherein Rx-N-R2forms a heterocycle selected from the group consisting of aziridine, azetidine, pyrrolidine, piperidine, and morpholine, 84943PC01

[0113] 18

[0114] A is independently selected from the group consisting of an optionally substituted C1-C14 alkylene, a bond, wherein n is an integer selected from the range of 0-4, m is an integer selected from the range of 1-3, p is an integer selected from the range of 0-16, Y is N-R4or O, wherein R4is selected from the group consisting of H, C1-C4 alkyl, and -CH2CH2NH2, q is an integer selected from the range of 0- 4,

[0115] X is N-R3or O, and

[0116] B is A or -CH2-CH2-. to sorb CO2 from a gas mixture comprising CO2.

[0117] An alternative aspect of the present invention relates to the use of a compound of formula (la) : 84943PC01 wherein R1and R2are independently selected from the group consisting of H and C1-C4 alkyl, or wherein Rx-N-R2forms a heterocycle selected from the group consisting of aziridine, azetidine, pyrrolidine, piperidine, and morpholine,

[0118] A is selected from the group consisting of an optionally substituted C1-C10 alkylene, wherein n is an integer selected from the range of 0-4, m is an integer selected from the range of 1-3, p is an integer selected from the range of 0-16, 84943PC01

[0119] 20

[0120] Y is N-R4or O, wherein R4is selected from the group consisting of H and C1-C4 alkyl, q is an integer selected from the range of 0- 4,

[0121] X is NH or O, and

[0122] B is A or -CH2-CH2-. to sorb CO2 from a gas mixture comprising CO2.

[0123] The compounds of formula (I) may preferably have a relatively short alkyl or H in the R1, R2, or R3position. Thus, in an embodiment, R1, R2, and R3are independently selected from the group consisting of H and C1-C4 alkyl, preferably H or C1-C3 alkyl, more preferably H, Ci alkyl, or C2 alkyl, more preferably H or Ci alkyl, most preferably H.

[0124] The C3 and C4 alkyl may be either linear or branched, e.g. C3 alkyl may be either n-propyl (CH3CH2CH2-, linear) or isopropyl group ((CHs)2CH-, branched). Similarly, C4 alkyl may be a n-butyl group (CH3CH2CH2CH2-), isobutyl group ((CHS)2CHCH2-), sec-butyl group (CH3CH2(-CH3)CH-), or tert-butyl group ((CH3)SC-). Thus, in an embodiment, C3-C4 alkyls are independently linear or branched, preferably linear. In another embodiment, C3 alkyl is selected from n- propyl or isopropyl. In another embodiment, C4 alkyl is selected from the group consisting of n-butyl, isobutyl, sec-butyl, and tert-butyl.

[0125] As demonstrated in the examples, the monomer, BAETA, had a higher CO2 capture efficiency than the oligomers (15 wt% for BAETA, Fig. 3A and 4 wt% for oligomers, Fig. 3B). Hence, in an embodiment, q is an integer selected from the range of 0-3, preferably 0-2, more preferably 0 or 1, most preferably 0.

[0126] In another embodiment, the sorption medium comprises a compound of formula (II):

[0127] 84943PC01

[0128] 21 wherein

[0129] R1, R2, and R3are independently selected from the group consisting of H and C1-C4 alkyl, or wherein Rx-N-R2forms a heterocycle selected from the group consisting of aziridine, azetidine, pyrrolidine, piperidine, and morpholine,

[0130] A is independently selected from the group consisting of an optionally substituted C1-C14 alkylene, a bond, wherein n is an integer selected from the range of 0-4, m is an integer selected from the range of 1-3, p is an integer selected from the range of 0-16, 84943PC01

[0131] 22

[0132] Y is N-R4or O, wherein R4is selected from the group consisting of H, C1-C4 alkyl, and -CH2CH2NH2.

[0133] In another embodiment, the sorption medium comprises a compound of formula (Ha): wherein

[0134] R1and R2are independently selected from the group consisting of H and C1-C4 alkyl, or wherein Rx-N-R2forms a heterocycle selected from the group consisting of aziridine, azetidine, pyrrolidine, piperidine, and morpholine,

[0135] A is selected from the group consisting of an optionally substituted C1-C10 alkylene, wherein n is an integer selected from the range of 0-4, m is an integer selected from the range of 1-3, 84943PC01 p is an integer selected from the range of 0-16,

[0136] Y is N-R4or O, wherein R4is selected from the group consisting of H and C1-C4 alkyl.

[0137] In one embodiment, A is an optionally substituted C1-C14 alkylene or

[0138] , preferably an optionally substituted C1-C14 alkylene. In an embodiment, the optionally substituted C1-C14 alkylene is an optionally substituted C1-C12 alkylene, such as an optionally substituted C1-C10 alkylene, such as an optionally substituted Ci-Cs alkylene, an optionally substituted Ci-Ce alkylene, such as an optionally substituted Ci-Ce alkylene, preferably an optionally substituted C1-C4 alkylene, more preferably an optionally substituted C1-C3 alkylene, most preferably an optionally substituted C2 alkylene.

[0139] During the aminolysis of PET several different types of oligomers might be formed. For example, some oligomers might contain partially degraded PET, where parts of the core structure of PET have not been aminolysed.

[0140] Consequently, these oligomers would have oxygen at the X position in formula (I). In this situation B would be -CH2-CH2- when X is O, because the ethylene is a part of PET core structure. Thus, in an embodiment, B is -CH2-CH2- when X is O. On the other hand, some oligomers might be formed by complete aminolysis of PET followed by oligomerization of the aminolysed PET. In this case, B is A when X is N-R3, since the amine used during aminolysis is incorporated into the oligomer structure. Thus, in an embodiment, B is A when X is N-R3. In another embodiment, X is N-R3, wherein R3is H or C1-C3 alkyl, preferably H, Ci alkyl, or C2 alkyl, more preferably H or Ci alkyl, most preferably H. In a preferred embodiment, B is -CH2-CH2- when X is O. It should be noted that some compounds might be a combination of the two situations. Thus, some oligomers might have both X=O, B—CH2-CH2- and X=N-R3, B=A. 84943PC01

[0141] 24

[0142] The A group in formula (I) can be an optionally substituted C1-C14 alkylene, i.e., an C1-C14 alkylene with or without a substituent. In an embodiment, the substituent on the optionally substituted C1-C14 alkylene is selected from the group consisting of C1-C4 alkyl, halide, NH2, carboxylic acid, amino acid, C1-C5 amide, and C1-C5 ester, or where two adjacent alkyl substituents unite to form a 5-6 membered ring. In an embodiment, said halide is selected from the group consisting of chloride, fluoride, bromine, and iodide. In a preferred embodiment, the substituent on the optionally substituted C1-C14 alkylene is selected from the group consisting of C1-C4 alkyl, and carboxylic acid, or where two adjacent alkyl substituents unite to form a 5-6 membered ring. In a preferred embodiment, the optionally substituted C1-C14 alkylene is a C1-C14 alkylene. Hence, in a preferred embodiment, the optionally substituted C1-C14 alkylene does not comprise a substituent.

[0143] A can might be N-R4, wherein R4is preferably a small alkyl or H. Thus, in an embodiment, R4is selected from the group consisting of H and C1-C4 alkyl, preferably H or C1-C3 alkyl, more preferably H, Ci alkyl, or C2 alkyl, most preferably H. In another embodiment, Y is N-R4, wherein R4is selected from the group consisting of H and C1-C4 alkyl, preferably H or C1-C3 alkyl, more preferably H, Ci alkyl, or C2 alkyl, most preferably H.

[0144] In an embodiment, p is an integer selected from the range of 0-14, such as 0- 12, such as 0-10, preferably 0-8, such as 8, such as 7, such as 6, such as 5, preferably 0-6, more preferably 0-4, such as 3, such as 2, such as 1, such as 0, most preferably 2. In a preferred embodiment, n is 0 and p is an integer selected from the range of 0-14, such as 0-12, such as 0-10, preferably 0-8, such as 8, such as 7, such as 6, such as 5, preferably 0-6, more preferably 0-4, such as 3, such as 2, such as 1, such as 0, most preferably 2.

[0145] In an embodiment, n is an integer selected from the range of 0-3, preferably 0- 2, more preferably 0 or 1, most preferably 0. In another embodiment, m is an integer selected from the range of 0-8, such as 7, such as 6, such as 5, preferably 0-6, more preferably 0-4, such as 3, such as 2, such as 1, such as 0, most preferably 2. 84943PC01

[0146] 25

[0147] In an embodiment, p is an integer selected from the range of 0-4, n is an integer selected from the range of 0-3, m is 2, and Y is O. In another embodiment, p is 2, n is 2, m is 2, and Y is O. In yet another embodiment, p is an integer selected from the range of 0-4, n is an integer selected from the range of 0-3, m is 2, and Y is Y is N-R4, wherein R4is H. In a further embodiment, p is 2, n is 2, m is 2, and Y is N-R4, wherein R4is H.

[0148] In an embodiment, the sorption medium comprises a compound of formula

[0149] (HI): wherein p is an integer selected from the range of 0-10, and

[0150] R1R2, and R3are independently selected from the group consisting of I and C1-C4 alkyl, or wherein Rx-N-R2forms a heterocycle :cted from the group consisting of aziridine, azetidine, rolidine, piperidine, and morpholine.

[0151] The monomer used in example 3 is BAETA which has the structure of formula (Iv). Thus, in an embodiment, the sorption medium comprises a compound of formula (IV): 84943PC01

[0152] The compounds of formula (I) are typically solid at room temperature. Thus, in embodiment, the sorption medium is solid at a temperature in the range of 20 °C to 200 °C. In a preferred embodiment, the sorption medium is solid at 20 °C.

[0153] Example 5 shows that the sorption medium can be pelletized, optionally using a binder. Thus, in an embodiment, the sorption medium comprises a binder. In another embodiment, the binder is selected from the group consisting of methyl cellulose, polyamide-6 (PA-6), polyacrylamide (PAM), graphite, K2CO3, xanthan gum, guar gum, microcrystalline cellulose, sodium carboxy methyl cellulose, chitin, polyamide 6.6 (PA 6.6), sodium silicate, sodium alginate, branched polyethylenimine (branched PEI), polyvinyl acetate (PVAc), polytetrafluoroethylene (PTFE), polylactic acid (PLA), polyvinyl alcohol (PVA), ethyl cellulose (EC), polyethylene glycol (PEG), silica, epoxy resin, aliminam, polyvinylpyrrolidone (PVP), and polyacrylic acid (PAA), preferably methyl cellulose, polyamide-6 (PA-6), polyacrylamide (PAM), or graphite, more preferably methyl cellulose or graphite, most preferably methyl cellulose. In yet another embodiment, the sorption medium comprises a binder in an amount selected from the range of 1 wt% to 80 wt%, such as 2 wt% to 80 wt%, such as 3 wt% to 80 wt%, such as 4 wt% to 80 wt%, such as 5 wt% to 80 wt%, 10 wt% to 80 wt%, such as 20 wt% to 80 wt%, such as 40 wt% to 80 wt%, preferably 50 wt% to 80 wt%, such as 50 wt% to 60 wt% relative to the total weight of the sorption medium. 84943PC01

[0154] 27

[0155] The sorption medium may be a mixture of different compounds of formula (I). Thus, in an embodiment, the sorption medium comprises two or more different compounds of formula (I). For example, the sorption medium may comprise a monomer, such as BAETA, and oligomers generated by aminolysis of PET. Thus, in an embodiment, the sorption medium comprises a compound of formula (V): wherein

[0156] R1, R2, and R3are independently selected from the group consisting of H and C1-C4 alkyl, or wherein Rx-N-R2forms a heterocycle selected from the group consisting of aziridine, azetidine, pyrrolidine, piperidine, and morpholine, p is an integer selected from the range of 0-16, q is an integer selected from the range of 0- 4,

[0157] X is N-R3or O, and

[0158] B is -CH2-CH2-, wherein p is an integer selected from the range of 0-16.

[0159] In an embodiment, when X is N-R3or B is -CH2-CH2- when X is

[0160] O. 84943PC01

[0161] 28

[0162] The nature of the gas mixture from which carbon dioxide is extracted in the method of the present invention may depend on whether the method is part of e.g. post-combustion gas carbon capture system, a system comprising e.g. flue gas or e.g. a direct air capture (DAC) system. Thus, in an embodiment, the gas mixture is selected from the group consisting of air, flue gas, post-combustion gas mixture, and biogas, or any mixture thereof. Preferably the gas mixture is flue gas or air, more preferably the gas mixture is flue gas. As demonstrated in figure 3G, the gas mixture can preferably comprise water vapor. Thus, in an embodiment, the gas mixture comprises water, such as water vapor or steam. In a preferred embodiment, the gas mixture has a relative humidity (RH) in the range of 0-100%, such as 5-100%, such as 10-100%, such as 20-100%, such as 30-100%, preferably in the range of 40-100%, such as 50-100%, more preferably in the range of 60-100%, most preferably in the range of 70-100%, such as 75-100%. As demonstrated in figure 5, the present invention can be used for direct air capture (DAC) to capture CO2 from air. Thus, in an embodiment, the CO2 concentration in the gas mixture is at least 200 ppm, such as at least 300 ppm, at least 400 ppm, such as preferably at least 420 ppm (0.042%). However, the sorption medium of the present invention can also be used to capture CO2 from a flue gas system as demonstrated in figure 3C. Thus, in an embodiment, the CO2 concentration in the gas mixture is at least 1,000 ppm (0.1%), such as at least 3,000 ppm (0.3%), such as at least 5,000 ppm (0.5%), such as at least 8,000 ppm (0.8%), such as at least 10,000 ppm (1%), such as 50,000 ppm (5 %), such as 100,000 ppm (10 %), such as 150,000 ppm (15 %), such as 200,000 ppm (20 %), preferably in the range of 1,000 ppm (0.1 %) to 1,000,000 ppm (100%), more preferably in the range of 10,000 ppm (1%) to 300,000 ppm (30%), most preferably in the range of 10,000 ppm (1%) to 200,000 ppm (20%).

[0163] The sorption medium of the present invention begins to slowly degrade at 200 °C. Thus, in an embodiment, the temperature in step b) is below 200 °C, such as below 190 °C, such as below 180 °C, such as below 170 °C, such as in the range of 0 °C to 190 °C, such as in the range of 0 °C to 180 °C, such as in the range of 10 °C to 170 °C, such as in the range of 20 °C to 170 °C, such as in the range of 100 °C to 160 °C, such as preferably in the range of 120 °C to 160 °C. 84943PC01

[0164] 29

[0165] Further, example 3 demonstrates that the sorption medium of the present invention can uptake CO2 through chemisorption (absorption) and physisorption (adsorption) or by a combination of the two. Hence, in an embodiment, the sorption medium absorbs CO2 to obtain a CCh-enriched sorption medium in step b) and / or the sorption medium adsorbs CO2 to obtain a CCh-enriched sorption medium in step b).

[0166] Desorption can e.g. be controlled by regulating the temperature of by regulation the gas flow as demonstrated in figure 3D, 3H and figure 4. Hence, in an embodiment, the temperature in step c) is above 10 °C, such as above 20 °C, such as in the range of 10 °C to 250 °C, such as in the range of 20 °C to 200 °C, such as in the range of 25 °C to 180 °C, such as in the range of 30 °C to 170 °C, such as above 50 °C, such as above 80 °C, preferably above 100 °C, such as in the range of 100 °C to 160 °C, such as above 110 °C, such as in the range of 120 °C to 160 such as in the range of 100 °C to 160 °C. In another embodiment, the desorption in step c) is performed under steam, water vapor, CO2 gas flow, nitrogen gas flow, inert gas flow, or argon gas flow, preferably steam, CO2 gas flow, or nitrogen gas flow, more preferably steam or CO2 gas flow, most preferably steam.

[0167] Several experiments of the present invention have demonstrated that the sorption medium of the present invention can be recycled, e.g., figure 4A shows that the sorption medium can be used for at least 180 cycles. Thus, in an embodiment, the method is a cyclic sorption-desorption process. The sorption medium retains its effectiveness throughout these cycles, indicating that the sorption medium loss throughout the cycles is rather low. Hence, in an embodiment, the loss of sorption medium per cycle in the cyclic sorptiondesorption process is less than 10%, such as less than 5%, such as less than 1%, such as preferably less than 0.1%, such as more preferably less than 0.01%, such as most preferably less than 0.001 %.

[0168] The cyclic process may occur in the same spatial volume, i.e. where the absorption zone and desorption zone are spatially the same zone, and where the conditions are changed in that zone to activate absorption or desorption of carbon dioxide. Hence, in an embodiment, the sorption and desorption is performed in the same zone. On the other hand, the cyclic process may also occur in two separate zones, i.e., two separate spatial volume. Thus, in an embodiment, the 84943PC01

[0169] 30 sorption is performed in a sorption zone and the desorption is performed in a desorption zone. In example 3, desorption is primarily controlled by the gas flow. Thus, in an embodiment, the desorption of CO2 is controlled by the gas flow in the desorption zone. In another embodiment, the gas flow in the desorption zone is steam, water vapor, CO2 gas flow, nitrogen gas flow, inert gas flow, or argon gas flow, preferably steam, CO2 gas flow, or nitrogen gas flow, more preferably steam or CO2 gas flow, most preferably steam.

[0170] The present method results in a potential up-concentration of CO2 gas as attained during desorption. Thus, in an embodiment, the CO2 obtained in step c) is subsequently used to produce a CCh-rich gas-stream and / or in carbon sequestration.

[0171] The method of the present invention is rather versatile as it can be used for both flue gas and DAC as demonstrates in example 3. Hence, in an embodiment, the method is applied in carbon capture from post-combustion gas, oxy-fuel combustion, biogas or flue gas or in Direct Air Capture (DAC), preferably Direct Air Capture (DAC) or flue gas, more preferably flue gas.

[0172] In another embodiment, the method is performed at a pressure in the range of 5.5 bar to 2 bar, such as 1 bar, preferably the method is performed under ambient pressure.

[0173] It should be noted that embodiments and features described in the context of one of the aspects of the present invention also apply to the other aspects of the invention.

[0174] All patent and non-patent references cited in the present application, are hereby incorporated by reference in their entirety.

[0175] The invention will now be described in further details in the following non-limiting examples.

[0176] Examples

[0177] Example 1 - Materials and methods

[0178] Materials and methods 84943PC01

[0179] 31

[0180] All chemicals, unless explicitly specified, were sourced from reputable commercial suppliers and used as received. Carbon dioxide (CO2) was employed directly from a cylinder with a purity of 99.7%, without any further treatment for reactions. The solvents utilized were of HPLC (High-performance liquid chromatography) grade. Analytical thin-layer chromatography was conducted on pre-coated Merck DC- Alufolien SiO? 60 F254 TLC plates, which had a thickness of 0.2 mm. Column chromatography was carried out using SiO? obtained from ROCC (SI 1721, particle size 60 A, 40-63 pm). LiquidXH and13C Nuclear Magnetic Resonance (NMR) spectra were acquired using a 500 MHz Ultrashield Plus 500 spectrometer and a 125 MHz Bruker spectrometer. Additionally,XH and13C NMR spectra were recorded at 500 MHz and 126 MHz, respectively, on a Bruker Avance 3 spectrometer equipped with a BBFO probe. Chemical shifts (6) were reported in parts per million (ppm) and coupling constants (J) were expressed in Hertz (Hz). The notation for NMR multiplicity included s (singlet), bs (broad singlet), d (doublet), t (triplet), q (quartet), and m (multiplet). Liquid Chromatography-Mass Spectroscopy (LC-MS) analysis was performed. FT-Infrared spectra were recorded using a Bruker ALPHA-P FT-IR spectrometer with a single reflection ATR module. Unless otherwise specified, all solvents and reagents were procured from commercial suppliers and used without additional purification. Ethylenediamine was obtained from Sigma-Aldrich. Drinking bottles were collected directly from end-users. Thermogravimetric analysis (TGA) was conducted using a Discovery TGA instrument from TA Instruments in New Castle, DE, USA. The samples were subjected to a constant nitrogen flow of 25 mL / min and heated in platinum TGA pans from room temperature to 600 °C at a heating rate of 10 °C / min. TGA results were analyzed to determine the thermal decomposition and the first derivative of TGA (dTGA) temperatures of the samples, using Trios v5.1.1.46572 software from TA Instruments. Differential scanning calorimetry (DSC) analysis was carried out using a Discovery DSC instrument from TA Instruments in New Castle, USA. Samples weighing 4-5 mg were placed in Tzero aluminum pans with a perforated lid. Analyses were conducted under a nitrogen flow of 50 mL / min, with a linear heating rate of 10 °C / min from 30 to 300 °C. Melting point temperatures (Tm) and melting enthalpy (AHm) were determined using Trios v5.1.1.46572 software. The purity of the isolated BHET (bis(hydroxyethyl)terephthalate) was assessed using HPLC with a Kromasil 5- AmyCoat column (4.6 x 250 mm), iso-propanol / n-heptane (60 / 40, v / v) mobile 84943PC01

[0181] 32 phase, a flow rate of 0.5 mL / min, and detectors A (220 nm) and B (254 nm). X- ray powder diffraction (PXRD) patterns were recorded for 2 hours using a Bruker AXS D8 powder diffractometer from Germany, equipped with CuKa radiation (ACuKa = 1.5406 A, 40 kV, 40mA). The measurement covered a 20 range from 5 to 50°. All measurements were conducted at 25 °C.

[0182] Example 2 - Synthesis and characterization of PET-derived CO2 sorbents Aim of study

[0183] The aim of this study was to synthesize and characterize different terephthalic amides obtained from aminolysis of PET.

[0184] Materials and methods

[0185] Drinking bottles pre-treatment

[0186] Various consumer-grade PET bottles were collected and cut into small pieces with a pair of scissors. PET flakes were then washed with H2O, rinsed with acetone and left under air to dry.

[0187] Optimization of aminolysis with drinking bottles as starting material.

[0188] General procedure: A vial (40 mL) was flushed with nitrogen flow, equipped with a magnet and charged with pre-treated bottle flakes (2.6 mmol) and ethylene diamine (2 equiv.). The top of vial was then wrapped with electric tape to avoid any gas leak. The reaction mixture was stirred at 60-140 °C for 0.25-72 h. BAETA was isolated by dissolving in hot methanol or hot isopropanol followed by hot filtration and solvent evaporation. The side product ethylene glycol was removed using Schlenk line (5 mbar) with heat (140 °C). The oligomers after the filtration were dried and weighted. The optimized conditions were 2 equivalents of EDA at 60 °C in air for 24 hours (Fig. 1).

[0189] Large-scale aminolysis with drinking bottles as starting material

[0190] The large-scale reaction was conducted following the general procedure as described above using optimized conditions of 2 eq. of EDA, PET (5 g, 10 g, 20 g, or 1 kg), 60 °C, N2 atmosphere for 24h. The reaction could also be performed at 25 °C under N2 atmosphere for 2-6 weeks.

[0191] After the reaction to 1 Kg scale, methanol was added and the mixture was filtered to remove unreacted PET. Unreacted PET was washed with methanol and weighed 84943PC01

[0192] 33 to determine the yield (483 g which represents 48% of unreacted PET). Methanol fractions were combined and concentrated. The resulting mixture contained oligomers, BAETA and ethylene glycol (EG) in a total of 792 g. To determine the yield, 3 g of the mixture was taken and subjected to vacuum-distillation apparatus to remove EG (7 mbar, 100 °C, 5 min). BAETA and oligomer mixture was then heated up in methanol, filtered to result in oligomer, while methanol was concentrated to result in pure BAETA.

[0193] Scope of PET waste

[0194] Different sources, such as drinking bottles, food packaging, toy stuffing, and leggings, were used as PET waste. The reaction followed the general procedure described above. Two grams of each PET source were subjected to optimized conditions: 2 equivalents of EDA at 60 °C in air for 24 hours. BAETA was isolated by adding hot water to the mixture, followed by hot filtration and cooling to room temperature. CO2 was purged into the water to saturate the BAETA sample, and acetone was added to precipitate BAETA-CO2. CO2 was then desorbed with N2 flow at 130°C, resulting in clean, off-white BAETA powder.

[0195] Trash mimicking experiment

[0196] Several types of commonly found trash were mixed together: food packaging (100% PET), food waste (chili mayo), disposable cup (100% PS), paper (100% cotton), aluminum foil (100% Al), disposable glove (100% NBR), wrapping paper (100% PE), and cotton ball (100% cotton). The reaction followed the general procedure described above. The entire trash mixture was subjected to optimized conditions: 2 equivalents of EDA at 60 °C in air for 24 hours. BAETA was isolated by adding hot water to the mixture, followed by hot filtration and cooling to room temperature. CO2 was purged into the water to saturate the BAETA sample, and acetone was added to precipitate BAETA-CO2. CO2 was then desorbed with N2 flow at 130 °C, resulting in clean, off-white BAETA powder.

[0197] Thermal stability of BAETA-CO2 adduct

[0198] 1 mmol of different sorbents were added to a vial and mixed with acetonitrile. CO2 balloon was then added to a vial and mixture was left stirring overnight. Resulting solid sorbent-CC>2 adduct was filtered and subjected to CO2 decomposition. 84943PC01

[0199] 34

[0200] Results

[0201] By incorporating amine within the terephthalic scaffold, the inventors aimed to avoid these drawbacks; low boiling point (116 °C) and thermal stability (< 120 °C), high vapor pressure (16 mmHg at 25 °C), volatility, corrosiveness and toxicity, which are all associated with environmental concerns of carbon capture solvents systems. In line with the low cost and abundance of PET substrate, the inventors envisioned that amine reagent had to fulfill the same criteria while retaining a strong affinity for CO2. Ethylene diamine (EDA) was selected due to its abundance from feedstock materials (ammonia, ethylene oxide). EDA is also known for its high CO2 capture capacity, outperforming monoethanol amine (MEA) that is considered the benchmark compound in CCh-capture.

[0202] After optimization, the solid CO2 sorbent monomer BAETA and polyamide oligomers were prepared by aminolysis of untreated post-consumer PET flakes by employing 2 equivalents of EDA compared to the therephthalic moiety, which is the theoretical minimum amount required for depolymerization. The reaction was performed either at 60 °C under stirring for 24 hours or at room temperature for up to 2 weeks. BAETA was obtained in up to 55% yield together with oligomers (40 %) (Table 1). Notably, both products - BAETA and oligomers - are active for CO2 capture and the reaction by-product (ethylene glycol) can be collected for recycling.

[0203] Table 1: BAETA and oligomer yield following aminolysis of PET using EDA

[0204] After establishing the optimal conditions, the inventors scaled up the synthesis of BAETA from 20 g to 1 kg of PET. The reactions were performed in a glass jar without pressure buildup, affording high purity product after simple work-up procedure affording 0.80 kg of BAETA (approximately 61% yield). Moreover, various sources of post-consumer PET such as PET bottles, PET fibers, PET food packaging, and PET textile waste were successfully converted to BAETA (Table 1). Considering the diverse range of waste to be recycled, including additives, 84943PC01

[0205] 35 impurities, and complexities arising from sourcing the waste, the inventors also subjected the synthesis procedure to a trash mimic experiment. This experiment included food packaging (100% PET, 10 g), food waste (chili mayo, 2 g), disposable cups (100% polystyrene, 1 g), paper (100% cotton, 1 g), aluminum foil (0.5 g), disposable laboratory gloves (100% nitrile butadiene rubber, 1 g), wrapping paper (100% polyethylene, 1 g), and cotton balls (0.5 g). The results showed only a slight decrease in the yield of BAETA (38 % BAETA yield), showcasing the applicability and scalability of this process.

[0206] The obtained BAETA and oligomers were tested for thermal stability and CO2 capture performances. BAETA stands up to 220 °C under air with a consistent decomposition starting at around 250 °C. TGA analysis of oligomers presented a similar profile to BAETA, although higher temperature (300 °C) was required for the full decomposition underlining the high stability of this polyamide material. Both BAETA and oligomers can withstand temperatures up to 250 °C in CO2, N2, and air, whereas conventional amine solvents fully decompose at 100°C (Fig. 2). Thus, BAETA and oligomers could withstand typical temperature used in CC flue gas stripping process (120 - 150 °C).

[0207] Conclusion

[0208] The present example demonstrates that the components obtained through aminolysis of PET have a higher thermal stability compared with conventional amine absorbents. Thus, the monomers and oligomers of the present invention could be used to capture CO2 in post-combustion gas, such as flue gas, since they could withstand typical temperatures used in CCh flue gas stripping processes (120 - 150 °C).

[0209] Example 3 - Carbon dioxide capture and desorption

[0210] Aim of study

[0211] The aim of this study was to investigate whether the monomer (BAETA) and oligomer obtained through aminolysis of PET with ethylene diamine could capture CO2 in flue gas and DAC conditions.

[0212] Materials and methods

[0213] CO2 capture dependance upon humidity 84943PC01

[0214] 36

[0215] A 4 mL vial was prepared by adding 0.100 g of sorbent (BAETA or oligomers) and a magnetic stir bar. The total mass of the setup was then measured. The vial was then placed into a preheated 40 mL vial at 25 °C, which contained either wetted salt or water to control the relative humidity. The salts used for this purpose included LiCI (11% RH), MgCI2(33% RH), Mg(NO3)2(53% RH), NaCI (75% RH), KCI (84% RH), and deionized water (100% RH). A CO2balloon was then introduced using a newly prepared double-wrapped balloon. The vials were insulated with cotton and aluminum foil to ensure a constant temperature of 25 °C and left stirring for 7 days.

[0216] The amount of water uptake was determined by repeating the same experiment but under N2. It was observed that BAETA and oligomers absorbed up to 4 wt% of water, however, all of it was released from the system before the temperature reached 100°C. From the total amount of water and CO2absorbed, the water amount was subtracted, and the CO2sorption amount depicted in Figure 3G. Using ss-NMR and ED, the inventors determined that BAETA forms a carbamate during CO2absorption, ensuring that co-absorption with water is not occurring. Therefore, all the weight loss that happens above 100 °C is due to pure CO2.

[0217] Palletizing and CO2 capture

[0218] Pallets were prepared using 100% BAETA powder and PIKE Technologies Hand Press, 7 mm diameter. After palletizing, the BAETA pallet was subjected to TGA for a CO2capture experiment.

[0219] Direct Air Capture (DAC) experiment

[0220] The Direct Air Capture experiment was conducted using an aquarium air pump, a BAETA filter, and two CO2sensors that recorded CO2levels in real-time. CO2sensor 1 was placed at the inlet of the air pump. Tubing connected the pump to a humidifier to maintain a stable 75% RH (saturated NaCI solution). The humidifier was then connected with tubing containing BAETA powder (a total of 1.5 g). The filter led to a closed 250 mL container with CO2sensor 2 inside. The closed compartment was connected to a flow meter to constantly record the flow rate, which was maintained at 5 mL / min.

[0221] Results 84943PC01

[0222] 37

[0223] The inventors observed CO2 chemisorption in a sample of BAETA after it was exposed to ambient humid air (data not shown). The13C-NMR spectra of the CO2 adduct indicated the presence of a mixture of BAETA, carbamate (RNH-CO2) and bicarbonate salt. To assess the preliminary CO2 capacity of BAETA and oligomers obtained by aminolysis of PET with EDA, these were subjected to TGA-MS-FTIR analysis. From the desorption experiments, the inventors observed that the CO2 adducts of BAETA were thermally stable, requiring considerable energy for desorption and decomposition (up to 150°C with N2 90 ml / min flow) (Fig. 2). The inventors hypothesized that the organic sorbents might be suitable for direct flue gas CO2 capture, where temperatures can be between 120-200°C. Subsequent TGA experiments were conducted, wherein BAETA and oligomers were exposed to a 100% CO2 flow at varying temperatures (25-170°C) for 210 minutes. Here the inventors observed enhanced performance at elevated temperatures, with peak gravimetric uptake observed at 150 °C (15 wt% for BAETA, Fig. 3A and 4 wt% for oligomers, Fig. 3B). This behaviour is unique since the high thermal stability of BAETA not only offers chemisorption at high reaction temperatures but also the reaction equilibrium provides a tool to assess its reaction mechanism. Apparent rate constant and Gibbs free energy analysis show 200 kJ / mol confirming high heat of sorption and high capacity of BAETA.

[0224] Further investigations into the CO2 capture capabilities of BAETA under flue gas conditions were conducted using 5-10% CO2 in N2 flow. The rate and capacity of CO2 sorption exhibited only a small decrease in performance, achieving up to 10- 12wt% CO2 absorption (Fig. 3C). More importantly, gas mixtures of 15% CO2 and 85% air applied to BAETA samples at 120-150 °C (Fig. 3C) led to approximately the same results showcasing the oxidative stability of BAETA and applicability for flue gas systems. The durability of BAETA under flue gas conditions was further studied by performing 40 consecutive cycles of CO2 capture and desorption via TGA at an elevated temperature (150 °C). A gas mixture comprising 15% CO2 and 85% N2 was selected for the absorption phase (30 min), and a 100% N2 flow (20 min) was used for the desorption phase (Fig. 3D). Over this range of 40 cycles, the CO2 capture capacity of BAETA exhibited no detectable decrease, indicating its effectiveness as a recyclable and durable CO2 sorbent. The inventors have also subjected BAETA to 500 repetitive carbon capture and release cycles under mimic of flue gas conditions using TGA: 15% CO2 + 85% CO2 for capture and 100% N2 flow for desorption. Over 500 cycles BAETA shows stable 2.5-2.75 wt% sorption 84943PC01

[0225] 38 without loss of efficiency (Fig. 3E). These durability tests reinforced the practicality of using BAETA in real-world flue gas treatment applications. After exposing BAETA sorbent to oxidative stress (1 hour at 100°C with 90 ml / min air flow), the material demonstrated strong stability. The subsequent CO2 sorption cycles at 150°C under 100% CO2 flow (90 ml / min) followed by desorption using 90 ml / min N2 flow at the same temperature confirmed that the sorbent retained its efficiency. Even after repeated cycles, BAETA maintained its oxidative stability, ensuring consistent CO2 capture and desorption performance (Fig. 3F).

[0226] To verify the applicability of BAETA in humid carbon capture conditions, the inventors conducted a performance evaluation of BAETA and oligomers in relation to relative humidity (RH), ranging from 0% to 100% RH, at 25 °C for 120 hours. Both BAETA and oligomers showed an increase in CO2 capture capacity as humidity levels rose. Specifically, the optimal CO2 capture capacity was 12 wt% at 100% RH for BAETA and 4 wt% at 100% RH for oligomers at 1 atm CO2 (Fig. 3G). Notably, despite their lower capacity at lower humidity levels, both absorbents were effective in capturing CO2 across the entire RH range from 10% to 100%. These findings highlight the significant potential of these solid-state amine-based sorbents to function efficiently. To enhance the processibility of BAETA, a preliminary palletization test was conducted wherein the CO2 capture efficiency was the same as observed in powder form (Fig. 3H).

[0227] In addition to BAETA's efficient CO2 capture at high temperatures, the inventors also noticed that BAETA had a wide range temperature operational mode: To the inventors' surprise, sorption at 25 °C exhibited different behaviour compared to the temperature range of 50-90 °C. The CO2 uptake was faster but slightly lower (up to 4 wt%). The inventors investigated this through TGA cycles, subjecting the sample to 100% CO2 flow at 25 °C for sorption and 100% N2 flow for desorption. Remarkably, the CO2 uptake remained relatively constant at 5 wt% for all 180 cycles without any thermal energy input, indicating physisorption on BAETA (Fig. 4A). To confirm this hypothesis, ss-NMR analysis and TGA experiments were conducted. The combination of physisorption and chemisorption in BAETA offers new CO2 capture mechanisms, creating opportunities to enhance material performance through advanced material design and crystal engineering. It is noteworthy here that under physisorption conditions, a slight decrease of gravimetric uptake was observed. However, a simple thermal activation (150 °C) 84943PC01

[0228] 39 effectively regenerated the material, indicating a fraction of chemisorption occuring under physisorption conditions (Fig. 4B)

[0229] To test the capacity of BAETA for direct air capture, the inventors designed the following reaction setup: 1.5 g of BAETA was employed to absorb CO2 from a continuous airflow of 5.4 mL / min passing through a filter containing the BAETA sorbent. The RH was monitored and maintained at 75%, while a CO2 sensor positioned before and after the BAETA filter constantly measured the carbon dioxide concentration. It was observed that 1.5 g of BAETA was capable of purifying air from CO2 for more than 13 days resulting in 95 liters of air processed and 0.0594 g of CO2 captured (90 mmol / g; 4 wt%) (Fig. 5).

[0230] Conclusion

[0231] Overall, these CO2 sorption experiments highlight the versatility of the PET-based solid CO2 sorbents of the present invention, in particular BAETA and oligomers obtained through aminolysis of PET using EDA. These compounds demonstrate efficiency and cost-effectiveness, making them scalable and readily available for various applications. These sorbents can capture CO2 from flue gas at high temperatures and operate efficiently across a wide range of temperatures.

[0232] Additionally, they perform well under different relative humidity levels, making them highly adaptable. Their applicability extends to DAC as well, showcasing their broad potential in both industrial and environmental CO2 capture scenarios, with high stability and reproducibility. By integrating ethylenediamine (EDA) within the terephthalic scaffold, the inventors have addressed the issue of low temperature degradation while improving the absorption capacity.

[0233] Example 4 - Carbon dioxide capture using PET-derived CO2 sorbents

[0234] Aim of study

[0235] The aim of this study was to investigate whether other PET-derived CO2 sorbents were as effective as BAETA in capturing CO2.

[0236] Materials and methods

[0237] Synthesis of PET-derived CO2 sorbents

[0238] As displayed in Figure 6, several terephthalamide-derived sorbents have been synthesized from PET by reacting with various diamines. A general procedure for the synthesis of the sorbents is provided here. To a 40 mL vial containing a 84943PC01

[0239] 40 magnetic stirring bar, clear PET flakes (1 g, 1 eq.) and diamine (2-8 eq.) were added. The vial was closed with a screw-lid having a septum and purged with a balloon of N2. Alternatively, the atmosphere was kept under air by simply closing the vial. Using a heating block, the vial was heated to 60-100 °C and stirred for 20-120 h. After cooling to room temperature, the mixture in the vial was partially solubilized in hot MeOH, and the mixture was filtered by hot filtration. The leftover solids, potentially oligomers and / or unreacted PET, were collected and dried. On a rotary evaporator, the filtrate was concentrated to remove the solvent. The resulting mixture was redissolved in MeOH and an anti-solvent (e.g. THF) was slowly added at room temperature, which lead to precipitation of solids. The solids were filtered and washed with antisolvent, and then dried under vacuum, to give the desired white to off-white solid products. In some cases, the desired product would be isolated by recrystallization.

[0240] CO2 capture using the PET-derived CO? sorbents

[0241] The resulting PET-derived CO2 sorbents were mainly characterized using nuclear magnetic resonance (NMR) spectroscopy and thermal gravimetric analysis (TGA). The CO2 capture performance of each so-far obtained aminolysed PET-based sorbent was tested using TGA to quantify gravimetric uptake at different temperatures.

[0242] Results

[0243] All the analyzed sorbents have either a similar or higher decomposition temperature compared to BAETA (Table 2). Longer C-chain derivatives such as the compounds called C8, C7, C6, C3, and C4 (See Figure 6) have shown the ability to capture CO2 at even higher temperatures than BAETA. For example, the C8 compound can capture CO2 at 190 °C and reach 1 moICCh / molSorbent capacity, which is equivalent to BAETA at 150 °C (Fig. 7). Longer C-chain compounds could therefore be valuable to use for flue gas CO2 capture. Despite the promising sorption profile at high temperatures, these compounds were harder to synthesize, and yields were lower compared to BAETA. Therefore, the inventors concluded that BAETA was still the preferred candidate for further processing and analysis. 84943PC01

[0244] 41

[0245] Table 2: Results from TGA of CO 2 uptake by the synthesized sorbents at different temperatures. TGA conditions: 100% CO2 gas, 90 mL / min. flowrate, 210 min. interval for CO2 capture. aValues are approximated from the TGA profiles.

[0246] While some sorbents do not possess CO2 capture performance under the same conditions, which are ideal for BAETA, their nature and resulting properties may allow them to capture CO2 under alternative conditions (e.g. low temperatures). The inventors also subjected Nl,N4-bis(8-aminooctyl)terephthalamide (compound called 'C8' in Figure 6) to a total of 250 repetitive carbon capture and release cycles. At 100% CO2 sorption was stable over 100 cycles and reached 9.5 wt%; while at 15% CO2 concentration the CO2 uptake was 8 wt% and was stable over 150 cycles without the loss in efficiency (Fig. 8). These durability tests reinforced the practicality of using Nl,N4-bis(8-aminooctyl)terephthalamide in real-world flue gas treatment applications.

[0247] Conclusion

[0248] This example demonstrates that a variety of PET-derived sorbents can be synthesized by varying the diamine used, each showing potential for CO2 capture under different operational conditions. Notably, while several sorbents exhibited high thermal stability and effective CO2 uptake, BAETA remained the preferred candidate due to its superior yield, ease of synthesis and effective CO2 uptake. These findings highlight the versatility and adaptability of PET-derived sorbents for carbon capture. 84943PC01

[0249] 42

[0250] Example 5 - Pelletization optimization

[0251] Aim of study

[0252] For industrial use, it is important to be able to convert BAETA powder into mechanically stable pellets, retaining >80% of CO2 capture efficiency while resisting degradation in humid or high-pressure environments. Powdered sorbents, though effective in lab-scale experiments, are less suitable for commercial systems due to its powder form (hard to handle, clogging) and poor flowability. Pelletizing improves usability in packed-bed or modular systems. The aim of this example was therefore to improve the pelletization of BAETA CO2 sorbents.

[0253] Materials and methods

[0254] Pelletization

[0255] For the pelletization, a hand press and accompanying die set (7 mm) from Pike Technologies was used as the pressing tool. For pellet pressing, pressure was applied by pressing the hand press handle fully down. To facilitate a time efficient pelletization procedure, the holding time was 0 seconds. The applied pressure was determined by the holding time (0 seconds) and by the setting of a 12-number dial (dial turns from the tightest position) on the hand press.

[0256] If the pellet could withstand being dropped on a bench from a height of ~40 cm at least once, it would be pass the drop test.

[0257] For the screening of binders, BAETA-CO2 adduct powder was used. Unless otherwise stated, BAETA-CO2 powder and the binder materials were mixed by using an agate mortar and pestle. A hand press and accompanying 7 mm die set from Pike Technologies was used as the pressing tool. The amount of used mixed powdered material was equal to the amount able to fit in the sample well by packing it tightly (with a spatula) and without going over the brim of the well. For pellet pressing, pressure was applied by squeezing the hand press handle fully down. The setting of a 12-number dial (loosening from the tightest position) on the hand press was set to "20". Unless stated otherwise, the handle would be opened / loosened immediately after closing it fully. The handling durability of a pressed pellet was assessed by being able to remove the pellet from the die set and gently rolling it between two fingers with minimum applied pressure without 84943PC01

[0258] 43 the pellet breaking (here given an "Medium" or "Low" rating). If the pellet could withstand being dropped on a table from a height of 40-50 cm at least three times, it would be given a "High" rating.

[0259] Wet mixing procedure

[0260] 100 mg of powder sample was measured directly in 8 mL vial with a stirring bar. 2 mL water or isopropanol was added to the vial which then was closed with a screwcap. The vial was stirred at 500 rpm for 24 h. The vial was then opened and heated to 40 °C, and the contents were allowed to stir for >24 h until deemed sufficiently dry. Additional very gentle blowing with N2 was applied when using water.

[0261] CO2 capture capability

[0262] To assess the CO2 capture capability and cyclability of the pellets, the thermal gravimetric analysis (TGA) was used (Table 3). For each pellet, a small piece would be broken off and subjected to TGA. The CO2 capture capability at 150 °C was noted as the maximum gain in wt% during a CO2 gas flow (sorption). The cyclability was assessed by two CO2 sorption-desorption cycles in total and was noted as the difference in wt% (Awt%) between the first and second cycle (subtracting C02(wt%max) of cycle 1 from C02(wt%max) of cycle 2).

[0263] Procedure for determining compression strength (crush strength)

[0264] To measure the compression strength, a Sauter FK100 digital force gauge was used with the cone-shaped punch attachment. The tip of this attachment has a surface area of ~3.14 mm (2 mm in diameter). The pellet to be tested was placed on a flat tile (benchtop of fume hood) and the force gauge was then pressed down on the centre of the pellet until it broke, or the force gauge maximum measuring limit (100 N) was met (equivalent to 31.8 N / mm2). The force gauge was zeroed and put in "PEAK" mode just before pressing down on the pellet.

[0265] Results

[0266] Thermogravimetric analysis (TGA) of selected BAETA-CO2 pellets show that these maintain almost the same CO2 capture efficiency and cyclability (over two cycles) (Table 3). 84943PC01

[0267] 44

[0268] Table 3: Initial optimization of pelletization conditions by evaluation of pellets physical properties aNote that the given values were obtained from the raw data without adjustments. Following these results, a vast number of pellets of BAETA-CO2 mixed with binders were tested for their durability in qualitative terms along with the CO2 capture performance through TGA. Some of the most promising candidates were then submitted to compression strength measurements (Table 4). Table 4: Determination of compression strength for selected binder-mixed pellets aNote that the given values were obtained from the raw data without adjustments

[0269] (PA6: polyamide-6, PAM: polyacrylamide). 84943PC01

[0270] 45

[0271] The binder methyl cellulose was selected for additional investigation regarding the CO2 capture performance for pellets with varying amounts of the binder (Table 5 and Fig. 9). From the results, it is apparent that using methyl cellulose as a binder produces pellets with high durability (by qualitative assessment) regardless of wt% amount. A pellet consisting entirely of methyl cellulose does not capture CO2. Importantly, while pellets with >50 wt% methyl cellulose have a lower CO2 uptake, the CO2 capture efficiency of BAETA is maintained to a high degree (~73- 78 %).

[0272] Table 5: Durability and CO2 capture performance of pellets with varying amounts of methyl cellulose as binder aNote that the given values were obtained from the raw data without adjustments.bCalculation based on maximum CO? uptake and ratio of BAETA in the given pellet.

[0273] The thermal (Fig. IDA) and oxidative stability (Fig. 1OB) of a 50 wt% methyl cellulose pellet was evaluated by TGA. This pellet possessed a similar thermal stability as purely BAETA powder (data not shown), and it displayed sufficient oxidative stability under the tested conditions.

[0274] Conclusion

[0275] This example demonstrates that binder-mixed BAETA pellets can be reliably produced with high durability and stability, making them suitable for industrial carbon capture applications under various operational conditions. 84943PC01

[0276] Example 6 - CO2 desorption optimization

[0277] Aim of study

[0278] The aim of this example was to develop an energy-efficient desorption method using steam regeneration or vacuum. Steam offers a low-cost, scalable alternative, especially if integrated with industrial heat streams. The inventors therefore established an experimental setup and conducted steam conditiondesorption testing for BAETA after CO2 capture by simply using heated humid air as stripping-off gas.

[0279] Materials and methods

[0280] Steam desorption

[0281] The steam desorption experiments were carried out using a custom-built laboratory setup designed to expose the sorbent to a continuous flow of water vapor. The setup consisted of a round-bottom flask (500 mL) partially filled with deionized water and positioned on a heating plate equipped with a temperature controller. The flask served as the steam generator. The water inside the flask was maintained at a constant temperature (130 °C) to ensure continuous production of saturated water vapor. Above the neck of the flask, a sintered glass filter was placed. The sorbent BAETA-CO2 sample (2g) was uniformly spread on the surface of the filter. The generated steam from water passed through the BAETA-CO2 continuously. Samples of the sorbent were taken at predetermined time intervals (0, 15, 30, 45, 60 min) for NMR analysis to determine the degree of CO2 desorption.

[0282] Reaction scheme for CO2 desorption using steam

[0283] Vacuum desorption

[0284] 1 g of the BAETA-CO2 adduct was placed in a 3-neck flask. The flask was continuously heated to 150 °C (the same temperature as used for CO2 capture), while one end was connected to a vacuum pump and the pressure was constantly monitored (maintained between 80-120 mbar to mimic industrial vacuum 84943PC01 pumps). After different time intervals, small fractions were taken for sampling and analyzed by NMR.

[0285] Reaction scheme for CO desorption using vacuum

[0286] Results

[0287] BAETA was exposed to CO2 (15% CO2 + 85% N2) at 150 °C in the desorption set up, showing the identical capture efficiency as described previously (up to 15 wt%). Then the sample was exposed to desorption conditions (Figure 11A-B), indicating at least 35% of captured CO2 being liberated.

[0288] Structural changes occur when applying vacuum to the BAETA-CO2 adduct, i.e., vacuum can be used to desorb CO2 from the BAETA-CO2 adduct (Figure 12).

[0289] Conclusion

[0290] This example demonstrates that steam and vacuum can be used as a stripping-off gas to desorb CO2 from the BAETA-CO2 adduct.

[0291] References

[0292] • Wang, J. et al. -. Waste polyethylene terephthalate (PET) plastics-derived activated carbon for CO2 capture: a route to a closed carbon loop. Green Chem. 22, 6836-6845 (2020)

[0293] • Li, S. et air. Diamond in the rough: Polishing waste polyethylene terephthalate into activated carbon for CO? capture. Sci. Total Environ. 834, 155262 (2022)

[0294] • WO09125943 Al

[0295] • WO13075697 Al

Claims

84943PC01Claims1. A method for separating CO2 from a gas mixture comprising CO2, said method comprising the steps of: a) providing a gas mixture comprising CO2; b) contacting the gas mixture with at least one sorption medium under conditions suitable for the sorption medium to sorb the CO2 to obtain a CO2-enriched sorption medium; c) desorbing CO2 from the CCh-enriched sorption medium under conditions suitable for the CO2-enriched sorption medium to desorb CO2 to regenerate the sorption medium and obtain CO2; wherein said sorption medium comprises a compound of formula (I) :whereinR1, R2, and R3are independently selected from the group consisting of H and C1-C4 alkyl, or wherein Rx-N-R2forms a heterocycle selected from the group consisting of aziridine, azetidine, pyrrolidine, piperidine, and morpholine,A is independently selected from the group consisting of an optionally substituted C1-C14 alkylene, a bond,84943PC01wherein n is an integer selected from the range of 0-4, m is an integer selected from the range of 1-3, p is an integer selected from the range of 0-16,Y is N-R4or O, wherein R4is selected from the group consisting of H, C1-C4 alkyl, and -CH2CH2NH2, q is an integer selected from the range of 0- 4,X is N-R3or O, andB is A or -CH2-CH2-.

2. The method according to claim 1, wherein R1, R2, R3and R4are independently selected from the group consisting of H and C1-C4 alkyl, preferably H or C1-C3 alkyl, more preferably H, Ci alkyl, or C2 alkyl, more preferably H or Ci alkyl, most preferably H.

3. The method according to any one of the preceding claims, wherein A is anoptionally substituted C1-C14 alkylene or , preferably an optionally substituted C1-C14 alkylene.84943PC01504. The method according to any one of the preceding claims, wherein the substituent on the optionally substituted C1-C14 alkylene is selected from the group consisting of C1-C4 alkyl, halide, NH2, carboxylic acid, amino acid, C1-C5 amide, and C1-C5 ester, or where two adjacent alkyl substituents unite to form a 5-6 membered ring.

5. The method according to any one of the preceding claims, wherein q is an integer selected from the range of 0-3, preferably 0-2, more preferably 0 or 1, most preferably 0.

6. The method according to any one of the preceding claims, wherein B is A when X is N-R3or B is -CH2-CH2- when X is O, preferably B is -CH2-CH2- when X is O.

7. The method according to any one of the preceding claims, wherein p is an integer selected from the range of 0-14, such as 0-12, such as 0-10, preferably 0-8. such as 8, such as 7, such as 6, such as 5, preferably 0-6, more preferably 0-4, such as 3, such as 2, such as 1, such as 0, most preferably 2.

8. The method according to any one of the preceding claims, wherein n is an integer selected from the range of 0-3, preferably 0-2, more preferably 0 or 1, most preferably 0.

9. The method according to any one of the preceding claims, wherein m is an integer selected from the range of 0-8, such as 7, such as 6, such as 5, preferably 0-6, more preferably 0-4, such as 3, such as 2, such as 1, such as 0, most preferably 2.

10. The method according to any one of the preceding claims, wherein the sorption medium comprises a compound of formula (II):84943PC0151whereinR1, R2, and R3are independently selected from the group consisting of H and C1-C4 alkyl, or wherein Rx-N-R2forms a heterocycle selected from the group consisting of aziridine, azetidine, pyrrolidine, piperidine, and morpholine,A is independently selected from the group consisting of an optionally substituted C1-C14 alkylene, a bond,wherein n is an integer selected from the range of 0-4, m is an integer selected from the range of 1-3, p is an integer selected from the range of 0-16,84943PC0152Y is N-R4or O, wherein R4is selected from the group consisting of H, C1-C4 alkyl, and -CH2CH2NH2.

11. The method according to any one of the preceding claims, wherein the sorption medium comprises a compound of formula (IV):

12. The method according to any one of the preceding claims, wherein the sorption medium comprises two or more different compounds of formula (I).

13. The method according to any one of the preceding claims, wherein the sorption medium is solid at 20 °C.

14. The method according to any one of the preceding claims, wherein the sorption medium comprises a binder.

15. The method according to claim 14, wherein the binder is selected from the group consisting of methyl cellulose, polyamide-6 (PA-6), polyacrylamide (PAM), graphite, K2CO3, xanthan gum, guar gum, microcrystalline cellulose, sodium carboxy methyl cellulose, chitin, polyamide 6.6 (PA 6.6), sodium silicate, sodium alginate, branched polyethylenimine (branched PEI), polyvinyl acetate (PVAc), polytetrafluoroethylene (PTFE), polylactic acid (PLA), polyvinyl alcohol (PVA), ethyl cellulose (EC), polyethylene glycol (PEG), silica, epoxy resin, aliminam, polyvinylpyrrolidone (PVP), and polyacrylic acid (PAA),84943PC0153 preferably methyl cellulose, polyamide-6 (PA-6), polyacrylamide (PAM), or graphite, more preferably methyl cellulose or graphite, most preferably methyl cellulose.

16. The method according to any one of claims 14 or 15, wherein the sorption medium comprises a binder in an amount selected from the range of 1 wt% to 80 wt%, such as 2 wt% to 80 wt%, such as 3 wt% to 80 wt%, such as 4 wt% to 80 wt%, such as 5 wt% to 80 wt%, such as 10 wt% to 80 wt%, such as 20 wt% to 80 wt%, such as 40 wt% to 80 wt%, preferably 50 wt% to 80 wt%, such as 50 wt% to 60 wt% relative to the total weight of the sorption medium.

17. The method according to any one of the preceding claims, wherein the gas mixture has a relative humidity (RH) in the range of 0-100%, such as 5-100%, such as 10-100%, such as 20-100%, such as 30-100%, preferably in the range of 40-100%, such as 50-100%, more preferably in the range of 60-100%, most preferably in the range of 70-100%, such as 75-100%.

18. The method according to any one of the preceding claims, wherein the method is applied in carbon capture from post-combustion gas, oxy-fuel combustion, biogas or flue gas or in Direct Air Capture (DAC), preferably Direct Air Capture (DAC) or flue gas, more preferably flue gas.

19. Use of a compound of formula (I) :wherein84943PC0154R1, R2, and R3are independently selected from the group consisting of H and C1-C4 alkyl, or wherein Rx-N-R2forms a heterocycle selected from the group consisting of aziridine, azetidine, pyrrolidine, piperidine, and morpholine,A is independently selected from the group consisting of an optionally substituted C1-C14 alkylene, a bond,wherein n is an integer selected from the range of 0-4, m is an integer selected from the range of 1-3, p is an integer selected from the range of 0-16,Y is N-R4or O, wherein R4is selected from the group consisting of H, C1-C4 alkyl, and -CH2CH2NH2, q is an integer selected from the range of 0- 4,X is N-R3or O, andB is A or -CH2-CH2-. to sorb CO2 from a gas mixture comprising CO2.

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