Production of amine-containing polymer sorbent material

Abstract

A method is disclosed for producing crosslinked and alkylated amine-containing polymer sorbent material, comprising obtaining a mixture comprising primary and / or secondary amine-containing polymer dissolved in a polar solvent, a crosslinking agent having two or more epoxide groups, and haloalkane; and subjecting the mixture to a heat treatment at a temperature of 40 to 80 °C, preferably at 45 to 65 °C, more preferably at 50 to 60 °C, to obtain crosslinked and alkylated amine-containing polymer sorbent material.

Description

[0001] PRODUCTION OF AMINE-CONTAINING POLYMER SORBENT MATERIAL

[0002] FIELD OF THE INVENTION

[0003] The present invention relates to producing amine-containing polymer sorbent material.

[0004] BACKGROUND ART

[0005] The ever-increasing concentration of CO2 in Earth's atmosphere forms a threat for the human civilization. Despite the urgency and importance of the issue, technologies for capturing the gas are still in their infancy. This is especially true for durable CO2 sorption materials that can be produced in large quantities and with acceptable price. Various options for capturing CO2 exist, but they either are synthetically complex, require high amounts of energy, or release volatile organic compounds. Therefore, there is a clear demand for safer and more affordable methods for capturing CO2. Methods for capturing CO2 are available, however, these methods are not cost effective, or they release volatile organic compounds. Thus, improvements for sorbents are sorely needed.

[0006] SUMMARY

[0007] The scope of protection sought for various example embodiments is set out by the independent claims. The example embodiments and features, if any, described in this specification that do not fall under the scope of the independent claims are to be interpreted as examples useful for understanding various embodiments.

[0008] According to an aspect, there is provided a method for producing crosslinked and alkylated amine-containing polymer sorbent material, comprising obtaining a mixture comprising primary and / or secondary amine-containing polymer dissolved in a polar solvent, a crosslinking agent having two or more epoxide groups, and haloalkane; and subjecting the mixture to a heat treatment at a temperature of 40 to 80 °C, preferably at 45 to 65 °C, more preferably at 50 to 60 °C, to obtain crosslinked and alkylated amine-containing polymer sorbent material.

[0009] According to another aspect, there is provided a crosslinked and alkylated amine-containing polymer sorbent material obtained by the method.

[0010] According to yet another aspect, the crosslinked and alkylated amine- containing polymer sorbent material is used for carbon dioxide capture. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In the following the invention will be described in greater detail by means of preferred embodiments with reference to the attached drawings, in which

[0012] Figure 1 illustrates exemplary reaction mechanism;

[0013] Figure 2 illustrates exemplary CO2 sorption mechanism;

[0014] Figure 3 shows measurement results for crosslinking rate;

[0015] Figure 4 shows measurement results for sorbent CO2 uptakes with different bromoalkane chain lengths;

[0016] Figure 5 shows measurement results for sorbent CO2 uptakes with different bromoalkane molar ratios;

[0017] Figure 6 shows measurement results for thermogravimetric mass change of sorbent;

[0018] Figure 7 shows measurement results for sorbent CO2 uptakes as a function of time;

[0019] Figure 8 shows measurement results for sorbent glass transition temperatures with different bromoalkane molar ratios;

[0020] Figure 9 shows measurement results for sorbent swelling ratios as a function of time.

[0021] DETAILED DESCRIPTION OF EMBODIMENTS

[0022] The following embodiments are exemplifying. Although the specification may refer to “an”, “one”, or “some” embodiment(s) in several locations of the text, this does not necessarily mean that each reference is made to the same embodiment's), or that a particular feature only applies to a single embodiment. Single features of different embodiments may also be combined to provide other embodiments.

[0023] In an embodiment, a method is provided for producing crosslinked and alkylated amine-containing polymer sorbent material. The method may comprise obtaining a mixture comprising primary and / or secondary amine-containing polymer dissolved in a polar solvent, a crosslinking agent having two or more epoxide groups, and haloalkane. The mixture may be subjected to a heat treatment at a temperature of 40 to 80 °C, preferably at 45 to 65 °C, more preferably at 50 to 60 °C, to obtain crosslinked and alkylated amine-containing polymer sorbent material.

[0024] In an embodiment, the method may comprise subjecting the mixture to the heat treatment for at least 1.5 hours, preferably at least 2 hours. The polar solvent may be methanol, ethanol, propanol, and / or water. The method may comprise washing the produced crosslinked and alkylated amine-containing polymer sorbent material with water, ethanol, propanol, and / or methanol.

[0025] In an embodiment, the haloalkane may be bromoalkane or chloroalkane, preferably bromoalkane. The haloalkane may be monohaloalkane. The haloalkane may be C8, C9, CIO, Cll and / or C12 haloalkane. The amount of haloalkane in the mixture may be 10 to 40 mol-% relative to amine groups in the primary and / or secondary amine-containing polymer.

[0026] In an embodiment, the method may comprise a crosslinking and alkylation reaction of amine groups. The crosslinking reaction may occur between the crosslinking agent and the primary and / or secondary amine-containing polymer. The alkylation reaction may occur between the haloalkane and the primary and / or secondary amine-containing polymer.

[0027] In an embodiment, the crosslinking agent may be at least one of 1,4-bu- tanediol diglycidyl ether, neopentyl glycol diglycidyl ether, 3,4-epoxycyclohexyl- methyl 3,4-epoxycyclohexanecarboxylate, glycerol diglycidyl ether, 4,4'-meth- ylenebis(N,N-diglycidylaniline), N,N-diglycidyl-4-glycidyloxyaniline, 1,3-butadi- ene diepoxide, 1,4-butanediol diglycidyl ether, tris(2,3-epoxypropyl) isocyanurate, tris(4-hydroxyphenyl)methane triglycidyl ether, 1,2,7,8-diepoxyoctane, bisphenol A propoxylate diglycidyl ether, bis [4- (glycidyloxy) phenyl] methane, and 2, 4,6,8- tetramethyl-2,4,6,8-tetrakis(propyl glycidyl ether) cyclotetrasiloxane. For example, the crosslinking agent may be a crosslinking agent having at least three epoxide groups, such as triglycidyl trimethylolpropane ether (TTE). The amount of the crosslinking agent in the mixture may be 1 to 5 mol-%, such as 3 mol-%, relative to amine groups in the primary and / or secondary amine-containing polymer.

[0028] In an embodiment, the primary and / or secondary amine-containing polymer may be at least one of polyethylene imine), polypropylene imine), polyvinylaniline (i.e. polyaminostyrene), poly(aminoalkylmetacrylate), polyfaminoal- kylacrylate), polyaminoacrylamide, polyallylamine, and polyvinylamine.

[0029] The primary and / or secondary amine-containing polymer may contain primary and / or secondary amine groups.

[0030] In an embodiment, the mixture may be obtained by mixing together the primary and / or secondary amine-containing polymer dissolved in the polar solvent, the crosslinking agent, and the haloalkane, at room temperature. In an embodiment, the mixing may be carried out for a time period sufficient to obtain an evenly mixed mixture, before the heat treatment. For example, the mixing time may be 15 to 25 min, or even shorter. The crosslinking agent may be dissolved in the polar solvent before the mixing.

[0031] In an embodiment, a crosslinked and alkylated amine-containing sorbent polymer material is disclosed, obtained by the above method. The crosslinked and alkylated amine-containing polymer sorbent material may be carbon dioxide sorbent material with an increased carbon dioxide sorption capacity compared to non-crosslinked and non-alkylated amine-containing polymer sorbent material. In an embodiment, the crosslinked and alkylated amine-containing polymer sorbent material may have increased carbon dioxide uptake compared to noncrosslinked and non-alkylated amine-containing polymer sorbent material. In an embodiment, the crosslinked and alkylated amine-containing polymer sorbent material may have a carbon dioxide sorption capacity of at least 1 mmol / g (as measured in dry conditions, i.e. with 0 vol-% water content). In an embodiment, the crosslinked and alkylated amine-containing polymer sorbent material may have a decreased water sorption capacity (and / or water uptake) compared to non-alkylated crosslinked amine-containing polymer sorbent material. In an embodiment, the crosslinked and alkylated amine-containing polymer sorbent material may be used for carbon dioxide capture.

[0032] In an embodiment, branched polyethylenimine (PEI) may be used as raw material to prepare CO2 sorbent material. Branched polyethylenimine (PEI) is low cost material and has high amine density. Triglycidyl trimethylolpropane ether (TTE) may be used as the crosslinking agent. Bromoalkanes may be used as the haloalkane for introduction of alkyl groups into PEI. The use of these materials may increase the rigidity of the produced CO2 sorbent, and enable to maintain the pore structure during water evaporation.

[0033] In an embodiment, crosslinking by multifunctional epoxide and classical amine alkylation may be performed. The materials may be synthesized in a one- pot reaction with no further purification other than washing with e.g. methanol and / or water. The obtained sorbent product may be prepared from simple starting materials that are commercially available and may reach the same CO2 sorption level as commercial resins. As the raw materials are solids, they may be easier to handle than liquid sorbents and do not release volatiles.

[0034] In an embodiment, an amine-containing polymer may be dissolved into polar solvent such as water or methanol. To the solution, a multifunctional epoxide and an alkyl bromide may be added. Both reagents may be used in sub-stoichio- metric amounts in relation to the amine groups. The epoxy may crosslink the amine, and the alkyl bromide may react with the amine groups. The obtained sorbent product may be ground and / or washed with water and / or methanol. The water may be removed from the product by drying, e.g. by freeze drying, or air drying. The process may rely on different reaction rates: the crosslinking with the epoxy may take place much faster than the alkylation. In this way, the properties of the crosslinked material may be tuned.

[0035] In an embodiment, hydrophilicity and stiffness may be modified with the bromoalkane, but also functional groups may be introduced in this way. The polymer with amino groups that may be poly(ethyleneimine) (PEI), but also other materials e.g. poly(propyleneimine), poly(allylamine), or poly(vinylamine) maybe used.

[0036] In an embodiment, a CO2 sorbent is produced using poly(ethylene- imine) (PEI). The process may involve simultaneous crosslinking and partial alkylation of the amine groups. The sorbent materials obtained may reach similar sorption levels as commercial resins in post-combustion capture (PCC). The material properties may be tuned over a wide range by varying the reagents. The reactions may be fast and rely on commercially available starting materials. Thus a fast and cost-effective method for CO2 sorbent synthesis may be provided. To synthesize crosslinked and alkylated PEI sorbent, a simple and fast method with affordable commercial materials may be provided involving simultaneous crosslinking and alkylation in one-pot. The obtained sorbents do not release volatiles and are easy to handle. High sorption rate may be reached, which is competitive with commercial resins. The obtained sorbent material may be regenerable such that the material may re-capture CO2. Regeneration of the sorbent material may involve desorbing the captured CO2. Amine groups in the branched PEI may be able to capture CO2 via chemical sorption. The simultaneous crosslinking and alkylation may result in increased sorption capacities compared to non-alkylated crosslinked PEI. Lower bromoalkene loading may result in higher sorption capacities due to more free amine groups.

[0037] Crosslinking and alkylation of amine groups may occur simultaneously. The crosslinking reaction may take place faster than the alkylation reaction. During and / or after the crosslinking, at least part of the amine groups may be alkylated with bromoalkene(s). An embodiment enables easy modification of mechanical properties and hydrophilicity of the sorbent material. The produced sorbent may be washed with methanol and water, and dried with a freeze dryer or air dryer. The crosslinking may provide the obtained CO2 sorption material with high integrity. The alkylation may provide increased hydrophobicity of the obtained CO2 sorption material compared to non-alkylated material, and thereby an improved CO2 sorption capacity.

[0038] The term sorption may refer to adsorption or absorption, or both. The term sorbent may refer to adsorbent or absorbent, or both.

[0039] Figure 1 illustrates exemplary reaction mechanism between the epoxide and amine groups to obtain the crosslinked structure of the sorbent material.

[0040] Figure 2 illustrates exemplary sorption mechanism to capture CO2 using exemplary PEl-based sorbent. The CO2 sorption mechanism in absence of water maybe as follows: R-NH2 / R2-NH + CO2 -> H++ R-NHCO2 / R2-NCO2- (carbamate). The CO2 sorption mechanism in presence of water may be as follows: R-NH2 / R2- NH / R3-N + CO2+ H2O -> R-NH3+ / R-NH2+ / R-NH+ + HCO3- (bicarbonate).

[0041] In an embodiment, amine-containing polymer sorbents may be produced, having high selectivity to CO2 from an anthropogenic source and / or air. Captured CO2 may be desorbed, and / or the sorbent may be regenerated, at elevated temperatures for CO2 storage and / or for CO2 utilization.

[0042] Example 1

[0043] 20 wt% homogeneous PEI (2.5 g, 58.09 mmol of repeating units) methanol solution was prepared first. 3 mol% TTE (0.5 g, 1.74 mmol) in relation to amine groups was dissolved in 1 mL methanol. The two solutions were mixed together to initiate the crosslinking at room temperature (RT). After 20 minutes, the reaction mixture was heated to 60 °C. 10, 20, 30, or 40 mol% bromoalkane in relation to amine groups was added to the mixture. The reaction was allowed to proceed at 60 °C overnight. The product was ground and washed with methanol and water. The product was then dried under air at RT overnight, and after that it was dried in a freeze dryer for another night to obtain PEl-based sorbent materials.

[0044] Figure 3 shows a FT1R spectrum measured for PEl-based sorbent material supported on a silica support. In Figure 3, the curves have been shifted along the y-axis. The crosslinking rate refers to the 1R intensity change over time. Crosslinking rate was noticeable even after 1 min. The time varied without silica support, but was still much faster than alkylation. The properties of crosslinked gels could then be modified with alkylation reactions.

[0045] Figure 4 shows CO2 uptakes of alkylated sorbents in consistent ratios to amines: 20 mol% for bromoalkanes and 3 mol% for TTE. Capture capacities of the alkylated PEI sorbents increased compared to the unmodified sorbent ("None” in Figure 4). It could be rationalized that the longer chains make the materials more rigid without diluting the amine sorbents too much. The highest CO2 uptakes were obtained for CsHiyBr (C8, bromooctane), CioEhiBr (CIO, bromodecane), and Ci2H2sBr (C12, bromododecane) as the haloalkane.

[0046] The sorbents with the highest CO2 uptakes (i.e. CsHiyBr, CioEhiBr or Ci2H2sBr as the haloalkane) were further optimized by varying the bromide ratio in relation to the amine groups, while maintaining the molar ratio of TTE in relation to amine groups at 3 %. More alkyl bromides diluted or deactivated the amine groups, thus lowering the ability to capture CO2. 20 mol-% of bromoalkane was optimal for CsHiyBr, but the optimum was less for C^FhsBr and CioEhiBr. See Figure 5 for the obtained CO2 uptakes as a function of the amount of bromoalkane (mol% in relation to amine groups) that was used in the preparation of the sorbent material.

[0047] Figure 6 shows thermogravimetric mass change. Sorbent regeneration, CO2 sorption, and CO2 desorption were performed. The mass loss for PEl-based sorbents in 3 mol% TTE and varied molar ratios of bromododecane (C12) was different. Sorbents with lower alkyl content were more hydrophilic. Thus, they captured more water which could be seen as more pronounced evaporation at the beginning. Captured CO2 was desorbed at a temperature of about 100 °C (desorption). The sorbents were regenerated ata temperature of about 100 °C (regeneration).

[0048] Figure 7 shows CO2 uptakes as a function of time for the PEl-based sorbents. Saturation with CO2 was achieved during the first 30 min for most of the studied sorbents. PEl-based sorbent prepared with 10 mol-% C^FhsBr in relation to amine groups was an exception, as the CO2 sorption was still increasing after 2 hours.

[0049] Figure 8 shows measurement results for sorbent glass transition temperatures (°C) as a function of the amount of bromoalkane (mol% in relation to amine groups) that was used in the preparation of the sorbent material. As seen in Figure 8, a higher amount of bromoalkane lead to a higher glass transition temperature, and thereby to a more rigid or stiffer sorbent material, which enables a higher CO2 uptake and higher CO2 sorption capacity of the sorbent material.

[0050] Figure 9 shows measurement results for sorbent swelling ratios (%) as a function of time. As seen in Figure 9, an increased amount of bromoalkane led to a lower swelling ratio, and thereby to a more hydrophobic sorbent material, which enables an increased CO2 uptake and decreased water uptake of the sorbent material.

[0051] It will be obvious to a person skilled in the art that, as the technology advances, the inventive concept can be implemented in various ways. The invention and its embodiments are not limited to the examples described above but may vary within the scope of the claims.

Claims

CLAIMS1. A method for producing crosslinked and alkylated amine-containing polymer sorbent material, comprising obtaining a mixture comprising primary and / or secondary amine-containing polymer dissolved in a polar solvent, a crosslinking agent having two or more epoxide groups, and haloalkane; and subjecting the mixture to a heat treatment at a temperature of 40 to 80 °C, preferably at 45 to 65 °C, more preferably at 50 to 60 °C, to obtain crosslinked and alkylated amine-containing polymer sorbent material.

2. A method of claim 1, comprising subjecting the mixture to the heat treatment for at least 1.5 hours, preferably at least 2 hours.

3. A method of claim 1 or 2, comprising washing the produced crosslinked and alkylated amine-containing polymer sorbent material with water, ethanol, propanol, and / or methanol.

4. A method of claim 1, 2 or 3, wherein the haloalkane is bromoalkane and / or chloroalkane, preferably bromoalkane.

5. A method of any of the preceding claims, wherein the haloalkane is monohaloalkane.

6. A method of any of the preceding claims, wherein the haloalkane is C8 haloalkane, C9 haloalkane, CIO haloalkane, Cll haloalkane, and / or C12 haloalkane.

7. A method of any of the preceding claims, wherein the polar solvent is methanol, ethanol, propanol, and / or water.

8. A method according to any of the preceding claims, wherein the crosslinking agent is a crosslinking agent having at least three epoxide groups, such as triglycidyl trimethylolpropane ether (TTE).

9. A method according to any of the preceding claims, wherein the method comprises a crosslinking and alkylation reaction of amine groups.

10. A method according to any of the preceding claims, wherein the amount of haloalkane in the mixture is 10 to 40 mol-% relative to amine groups in the primary and / or secondary amine-containing polymer.

11. A method according to any of the preceding claims, wherein the amount of the crosslinking agent in the mixture is 1 to 5 mol-%, such as 3 mol-%,relative to amine groups in the primary and / or secondary amine-containing polymer.

12. A method according to any of the preceding claims, wherein the primary and / or secondary amine-containing polymer is at least one of polyethylene imine), polypropylene imine), polyvinylaniline, poly(aminoalkylstyrene), poly(aminoalkylmetacrylate), poly(aminoalkylacrylate), polyaminoacrylamide, polyallylamine, and polyvinylamine.

13. A method according to any of the preceding claims, wherein the mixture is obtained by mixing together the primary and / or secondary amine-containing polymer dissolved in the polar solvent, the crosslinking agent, and the haloalkane, at room temperature, preferably for 15 to 25 min.

14. A method according to any of the preceding claims, wherein the crosslinking agent is dissolved in the polar solvent before mixing with the primary and / or secondary amine-containing polymer dissolved in the polar solvent and the haloalkane.

15. A crosslinked and alkylated amine-containing polymer sorbent material obtained by the method according to any of the preceding claims.

16. A crosslinked and alkylated amine-containing polymer sorbent material of claim 15, wherein it is a carbon dioxide sorbent material with an increased carbon dioxide sorption capacity, and a decreased water sorption capacity, compared to non-alkylated crosslinked amine-containing polymer sorbent material.

17. A crosslinked and alkylated amine-containing polymer sorbent material of claim 15 to 16, wherein it has a carbon dioxide sorption capacity of at least 1 mmol / g.

18. Use of the crosslinked and alkylated amine-containing polymer sorbent material of claim 15, 16 or 17 for carbon dioxide capture.

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