Carbon dioxide separation

Abstract

The present invention relates to a wet gas flow filter (10) for filtering carbon dioxide (CO2) from a water-containing exhaust gas flow, to a filter system (1) having a wet gas flow filter (10) of this type, and to a filtering method (100). A filter material (12) contains a microporous adsorbent (14) for the selective physisorption of carbon dioxide (CO2) from water-containing exhaust gas, which is flowing against the filter material (12), into micropores (16) of the adsorbent (14). The microporous adsorbent (14) comprises a phyllosilicate (18) and column molecules (20) which are intercalated in the phyllosilicate (18) and determine the size of the micropores (16).

Description

[0001] 2024PF00812

[0002] Description

[0003] Coal-stained! ox id - From divorce

[0004] The present invention relates to a wet gas stream filter for filtering carbon dioxide from a water-containing exhaust gas stream, a filter system with such a wet gas stream filter, a filter method, a synthesis method and the use of a filter material.

[0005] To reduce carbon dioxide emissions and limit global warming, processes for capturing carbon dioxide (CO2) from exhaust gas streams have been developed. One possible technical implementation relies on the covalent bonding of carbon dioxide to a filter material. This approach is widely used because it allows for the selective, i.e., targeted, filtering of carbon dioxide from an exhaust gas stream.

[0006] An example of such a separation process is the so-called amine scrubbing, in which alkaline aqueous solutions of amines (alkanolamines) are used. These bind the carbon dioxide chemically and reversibly as carbamate, bicarbonate, and / or carbonate. Other components of the exhaust gas stream, for example, nitrogen (N₂) or water (H₂O), cannot bind covalently to the amines, thus achieving the high selectivity for carbon dioxide.

[0007] However, this approach has room for improvement from both an economic and ecological perspective. For example, if the exhaust gas stream of a power plant combustion system is cleaned using amine scrubbing, up to 40% of the power plant's output can be required for filter material regeneration. This is because high temperatures exceeding 100 °C are necessary for the required breaking of the covalent bonds. Furthermore, the oxidative and thermal degradation of the amines, as well as the disposal of the resulting liquid waste, are also problematic. 2024PF00812

[0008] 2

[0009] Due to the high volatility of the amine components, separating them from the purified gas is also complex. Furthermore, the use of basic amines often leads to severe corrosion of the equipment.

[0010] As an alternative carbon dioxide capture process, physisorption was therefore also considered. The binding of carbon dioxide molecules to a solid surface by physical (van der Waals) forces is associated with a substantially lower adsorption energy and thus allows for a significant reduction in the energy required for regeneration compared to chemisorptive processes. A wide range of materials was investigated for the physisorptive capture of carbon dioxide, ranging from organic to inorganic materials and inorganic-organic hybrid structures. For example, metal-organic frameworks and zeolites were considered, both of which exhibit a high carbon dioxide uptake capacity. However, these material classes usually have only limited selectivity in the separation of carbon dioxide from nitrogen mixtures.Furthermore, these materials lose further selectivity for the separation of carbon dioxide from a water-containing exhaust gas stream, as the water molecules coordinate to the adsorption sites and displace the carbon dioxide from there.

[0011] Against this background, it is an object of the present invention to further improve the filtration of carbon dioxide from a moist gas stream, i.e., a water-containing exhaust gas stream, in particular to enable easy regeneration of a filter material while maintaining good filter properties. It is also an object to provide a suitable filter.

[0012] This task is solved by a wet gas stream filter for filtering carbon dioxide from a water-containing exhaust gas stream, a filter system with such a 2024PF00812

[0013] 3

[0014] A moist gas stream filter, a filtering method, a synthesis method and the use of a filter material according to the independent claims.

[0015] Preferred embodiments are the subject of the dependent claims and the following description.

[0016] According to a first aspect of the invention, the moist gas stream filter for filtering carbon dioxide from a water-containing exhaust gas stream comprises a filter material containing a microporous adsorbent for the selective physisorption of carbon dioxide, particularly water vapor, from the water-containing, i.e., moist, exhaust gas flowing onto the filter material into micropores of the adsorbent. The microporous adsorbent has a layered silicate and column molecules intercalated within the layered silicate, which determine the size of the micropores.

[0017] A microporous material according to the present invention is preferably a material which has (Schitz) pores with a height of 20 Å or less, preferably 10 Å or less, and particularly preferably 5 Å or less. The micropores need not be spherical, but may have an oval shape. For example, if the height is less than 5 Å, the micropores may have a length between 5 Å and 10 Å.

[0018] Selective physisorption according to the present invention is preferably a targeted physisorption of carbon dioxide, particularly in the presence of water vapor or a water-containing gas stream. Advantageously, in selective physisorption, the physisorption of carbon dioxide is greater than that of water, especially when the carbon dioxide concentration and the water concentration in the exhaust gas stream are essentially the same.

[0019] One aspect of the invention is based on the approach of providing a filter material which is microporous. 2024PF00812

[0020] 4

[0021] The adsorbent consists of a layered silicate with intercalated column molecules. The column molecules, for example, 1,4-diaminobutane, especially its doubly protonated species 1,4-diammoniumbutane, are advantageously arranged between the silicate layers. Micropores can form between the column molecules within the plane between two layers of the layered silicate, in which carbon dioxide from a water-containing exhaust gas stream can physisorb. Experiments have shown that in such layered silicates with intercalated column molecules, the pore size can, in principle, be precisely controlled by selecting the column molecules. In particular, it has proven possible to adjust the pore height and width independently of each other with a resolution of less than 1 × 10⁻⁶, thus tailoring the system to the selective uptake of carbon dioxide compared to larger molecules in the exhaust gas stream, for example, nitrogen (N₂).Surprisingly, it was found that not only can carbon dioxide be separated from a stream of larger molecules in this way, but that the selectivity of carbon dioxide towards water is also at least partially and / or at least within a certain range dependent on the pore width, i.e., the distance between the column molecules in the plane between two layers of the phyllosilicate. While it was known that a microporous adsorbent made of phyllosilicate with intercalated column molecules can filter carbon dioxide from an exhaust gas stream with larger molecules through simple size exclusion, the selectivity with regard to the physisorption of carbon dioxide towards water was previously completely unknown.This behavior was also unexpected, since the smaller water molecule cannot be excluded using the size exclusion principle, and water is more hydrophilic than carbon dioxide, which should make selective, physisorptive carbon dioxide removal more difficult. Therefore, it was unexpected that such layered silicates with intercalated column molecules selectively removed carbon dioxide even from a water-containing, i.e., moist, exhaust gas stream.

[0022] 5

[0023] These filter materials can be filtered out and even optimized with regard to their selectivity and / or absorption capacity for carbon dioxide by selecting and sizing the column molecules. Therefore, such a filter material can be used to filter industrial exhaust gas streams, for example, from gas turbines, which typically also contain water vapor. The physisorption-based filter mechanism is advantageous compared to conventional methods such as amine scrubbing, in which the carbon dioxide is chemically bound, because the adsorption energy is significantly lower than the binding energy for chemical bonding to amines, and regeneration is correspondingly less energy-intensive. Furthermore, the regeneration of this filter material does not generate any environmental pollution from waste.

[0024] Preferred embodiments of the invention and their further developments are described below.

[0025] Unless expressly excluded, the various implementation forms can be combined with each other and with the aspects of the invention described below.

[0026] In a preferred embodiment, the column molecules have a small elliptical axis, also referred to as a semi-axis, between 2.7 Å and 3.4 Å, i.e., in the range of the kinetic diameter of carbon dioxide. The height of the micropores, i.e., the layer spacing in the layered silicate, is preferably determined by the length of this small semi-axis. This allows nitrogen, which typically constitutes the largest fraction in industrial, water-containing exhaust gas streams, to be separated from the carbon dioxide by size exclusion. This is because the kinetic diameter of nitrogen is approximately 3.64 Å and is therefore larger than the preferred height of the micropores. Consequently, nitrogen, or any other, even larger molecule from the exhaust gas stream, cannot penetrate the micropores of the adsorbent. 2024PF00812

[0027] 6

[0028] In another preferred embodiment, the filter material is or is made of sodium fluorohectorite.

[0029] ( [Na0,5] inter [Mg2.5Lio f 5 ] oct [Si4] tet Oi0F2). A material made from a substance or compound is, in this context, preferably a material in whose manufacture at least this substance or compound is used. It is therefore not excluded that the material is also made from other substances or compounds. The use of a filter material made from sodium fluorohectorite allows for a low-effort synthesis of the filter material, which makes it particularly easy to adjust the quality of the filter material and its carbon dioxide removal properties.

[0030] Advantageously, the sodium intercalated between the fluorohectorite layers is replaced by the column molecules during the synthesis of the filter material. This allows for the creation of micropores tailored to specific sizes, particularly height and width, between the fluorohectorite layers.

[0031] Alternatively, the filter material is made from vermiculite. Vermiculite is a naturally occurring layered silicate. Consequently, a filter material made from vermiculite is particularly inexpensive to produce, as no synthesis is required.

[0032] In another preferred embodiment, one of the following compounds is intercalated as column molecules into the layered silicate: i) ethylenediamine, ii) 1,3-diaminopropane, iii) spermidine, or iv) 5-(aminomethyl)-1H-1,2,4-triazol-3-amine. This allows for high carbon dioxide uptake capacities combined with high selectivity of carbon dioxide over water vapor.

[0033] The use of 1,3-diaminopropane as a column molecule is particularly advantageous here, as experiments have shown, 2024PF00812

[0034] 7

[0035] that this achieves the highest molar selectivity for carbon dioxide over water among the aforementioned compounds. At the same time, the layered silicate intercalated with 1,3-diaminopropane exhibits a comparatively high absorption capacity for carbon dioxide.

[0036] Spermidine has also proven to be very advantageous, although it has a lower selectivity for carbon dioxide towards water than 1,3-diaminopropane, but has an even higher absorption capacity for carbon dioxide.

[0037] In another preferred embodiment, the column molecules have an equivalent area between including 18 Ω 2 per charge and 29 Ä 2 per charge. The

[0038] The equivalent area conveniently determines the pore size, in particular the pore width.

[0039] The equivalent surface area of ​​a column molecule, as defined in the present invention, is preferably understood as the area required by this column molecule in the plane between two silicate layers (per charge). With increasing area requirement of the individual column molecules per charge, the specific surface area available for the adsorption of carbon dioxide decreases, at least when the charge density of the layered silicate remains constant.

[0040] Accordingly, the absorption capacity for carbon dioxide correlates with the equivalent area.

[0041] Experiments have shown that the pore sizes corresponding to equivalent areas in the aforementioned range can lead to an optimum in selectivity of carbon dioxide towards water vapor and absorption capacity of carbon dioxide in the filter material.

[0042] In another preferred embodiment, the absorption capacity of the filter material for carbon dioxide is greater than 0.74 mmol / g. With such a high absorption capacity, efficient filtration can be maintained even over extended periods. Accordingly, the intervals between necessary regenerations of the filter material can be reduced.

[0043] 8

[0044] be enlarged.

[0045] According to a second aspect of the invention, the filter system for filtering carbon dioxide from a water-containing exhaust gas stream comprises a wet gas stream filter according to the first aspect of the invention for connection to a carbon dioxide point source. The wet gas stream filter can, for example, be connected to a combustion device, such as a turbine or a power plant combustion system. With such a filter system, carbon dioxide can also be separated from water-containing exhaust gas streams by means of physisorption. The filter system can thus be operated significantly more energy-efficiently than comparable systems based on chemisorptive processes. At the same time, this can achieve the avoidance or at least reduction of waste, particularly environmentally harmful waste.

[0046] The filter system expediently comprises at least two filter chambers, each with a wet gas stream filter. In addition, a supply line for feeding the water-containing exhaust gas stream from the combustion device, for example an internal combustion engine or a combustion plant, to the filter chambers and / or a discharge line for removing the filtered exhaust gas stream from the filter chambers may be provided.

[0047] In a preferred embodiment, at least two fixed beds formed from the filter material, in particular powder-layer fixed beds, are provided. These fixed beds are preferably independently accessible to or permeable by the water-containing exhaust gas. The fixed beds are expediently arranged in each of the at least two filter chambers. This enables continuous filter operation. In particular, the filter material in the fixed bed can thus be easily removed from the exhaust gas flow after decoupling the corresponding fixed bed or filter chamber by adjusting, for example, the prevailing pressure and / or temperature.

[0048] 9

[0049] be regenerated.

[0050] For this purpose, the supply line and / or the discharge line can have corresponding shut-off devices to regulate the exhaust gas flow through the fixed beds or through the filter chambers. It is also preferred to provide a corresponding control device that controls the regeneration process or is designed to control the regeneration process.

[0051] According to a third aspect of the invention, in the filtering process for filtering carbon dioxide from a water-containing exhaust gas stream, a microporous filter material containing an adsorbent is passed through or over by the water-containing exhaust gas stream. The microporous adsorbent comprises a layered silicate and columnar molecules intercalated within the layered silicate, which determine the size of the adsorbent's micropores. By passing through or over the filter material, the carbon dioxide from the exhaust gas stream is selectively physisorbed in the micropores, particularly in relation to water contained in the exhaust gas stream. Surprisingly, a larger quantity of carbon dioxide can be captured in the micropores in this way. In particular, more carbon dioxide than water can be captured in this way, at least when the concentrations of carbon dioxide and water in the exhaust gas stream are essentially the same.This process can therefore be used to efficiently remove carbon dioxide from a water-containing exhaust gas stream or at least to significantly reduce the carbon dioxide concentration in the exhaust gas stream.

[0052] If necessary, the adsorption energy can be optimized via the width of the micropores, thereby reducing the energy required for regeneration of the filter material and thus making the regeneration process more cost-effective.

[0053] According to a fourth aspect of the invention, the synthesis process for a microporous adsorbent for 2024PF00812

[0054] 10

[0055] Use in or as a filter material for a wet gas stream filter according to the first aspect of the invention, starting from a synthesis starting material comprising one of the chloride compounds ethylenediamine dihydrochloride, 1,3-diaminopropane dihydrochloride, 1,4-diaminobutane dihydrochloride, spermidine trihydrochloride or 5-(aminomethyl)-1H-1,2,4-triazol-3-amine dihydrochloride, or formed by dissolving one of these compounds in water, intercalating the amine compounds ethylenediamine, 1,3-diaminopropane, 1,4-diammoniumbutane, spermidine or 5-(aminomethyl)-1H-1,2,4-triazol-3-amine or their doubly protonated species as column molecules by cation exchange, in particular a cation exchange reaction, and subsequent chloride removal in a layered silicate.

[0056] Exchanged cations, e.g. from the layered silicate sodium fluorohectorite ([Na0,5] inter [Mg2.5Lio f 5 ] oct [Si4] tetOi0F2), as well as the counterions from the synthesis starting materials, in particular chloride ions, and / or excess cations or

[0057] Synthesis starting materials that are present in solution after the exchange reaction can simply be washed out.

[0058] According to a fifth aspect of the invention, a filter material is used for filtering carbon dioxide from a water-containing exhaust gas stream, wherein the filter material contains a microporous adsorbent for selective physisorption from water-containing exhaust gas flowing onto the filter material into micropores of the adsorbent, and the microporous adsorbent comprises a layered silicate and column molecules intercalated in the layered silicate, which determine the size of the micropores.

[0059] Surprisingly, it has been shown that such a filter material is also suitable for filtering carbon dioxide from water-containing exhaust gas streams, such as those flowing from a turbine. The suitability of the filter material was not expected, as experts had previously assumed that the water molecules in the 2024PF00812

[0060] 11

[0061] The exhaust gas stream penetrates the micropores of the adsorbent and displaces the carbon dioxide there. The expected carbon dioxide removal rate in the micropores was therefore considered negligible or insufficient for effective filtration.

[0062] The properties, features, and advantages of the invention described above, as well as the manner in which they are achieved, are explained in more detail in the following description of exemplary embodiments of the invention in conjunction with the figures. Where appropriate, the same reference numerals are used in the figures for the same or corresponding elements of the invention. The exemplary embodiments serve to illustrate the invention and do not limit the invention to the combinations of features specified therein, including functional features. Furthermore, all features specified in the exemplary embodiments can be considered in isolation and combined appropriately with the features of any claim.

[0063] They show, at least partially schematically:

[0064] FIG 1 shows an example of a filter system; and

[0065] FIG 2 shows an example of a filter material for a wet gas flow filter.

[0066] FIG 1 shows an example of a filter system 1 for filtering carbon dioxide from a water-containing exhaust gas stream with at least one, in this example two, wet gas stream filters 10 for connection to a combustion device V. The combustion device V, which can be considered the wet gas stream source, can be, for example, a turbine arrangement consisting of one or more turbines or the combustion chamber of a power plant. The filter system 1 comprises two filter chambers 2, which are connected to the 2024PF00812

[0067] 12

[0068] The combustion unit V can also be supplied with a water-containing exhaust gas stream, and each chamber contains one of the moist gas stream filters 10. The filter chambers 2 are fluidly connected to the combustion unit V via a supply line 4 at the inlet. An outlet line 6 is also provided, which is connected to the filter chambers 2 at the outlet and serves to discharge the filtered exhaust gas stream. The flow of exhaust gas into and out of the filter chambers 2 can be controlled by shut-off devices 8, which can be actuated by a control device S.

[0069] In a process for filtering carbon dioxide from a water-containing exhaust gas stream, which is carried out using the filter system, water-containing exhaust gas expediently flows through the filter chambers 2. The exhaust gas must flow onto or through a filter material 12 of the wet gas stream filters 10. This causes at least some of the carbon dioxide contained in the water-containing exhaust gas stream to be deposited on the filter material 12, in particular in micropores of an adsorbent contained in the filter material 12, by means of physisorption. As a result, the exhaust gas stream can be at least partially freed of carbon dioxide. If the carbon dioxide absorption capacity of one of the wet gas stream filters 10 is exhausted, the control device S expediently causes the corresponding shut-off devices 8 in the supply line 4 and the discharge line 6 to close.The moist gas stream filter 10 in the filter chamber 2, which is thus decoupled from the water-containing exhaust gas stream, can then be regenerated, for example by adjusting the pressure and / or temperature in the corresponding filter chamber 2. For example, carbon dioxide escaping from the filter material 12 by increasing the temperature can be extracted from the filter chamber 2 by means of an extraction device (not shown). Such an extraction device can also be actuated by the control device S. The same applies to a heating device (also not shown) for 2024PF00812.

[0070] 13

[0071] Increasing the temperature in filter chamber 2. Saturation of the filter material 12 or the microporous adsorbent contained therein with carbon dioxide can be detected by means of carbon dioxide-sensitive sensors arranged in the filter chambers 2 (not shown): when the carbon dioxide concentration in the gas stream that has already passed through the respective wet gas stream filter 10 begins to rise, in particular to a predetermined carbon dioxide threshold or above, it can be assumed that the absorption capacity of the filter material 12 has been exhausted. Advantageously, these sensors are also connected to the control device S, in particular via signal or data transmission. The control device S is advantageously configured to carry out the regeneration of the wet gas stream filters 10 essentially fully automatically.

[0072] FIG. 2 shows an example of a filter material 12 for a wet gas stream filter for filtering carbon dioxide from a water-containing exhaust gas stream. The filter material 12 contains an adsorbent 14 that has a plurality of micropores 16. One of these micropores 16 is highlighted in the adsorbent 14 for illustration and is shown enlarged from the side. The adsorbent 14 has a layered silicate 18 in which column molecules 20 are intercalated. The micropores 16 correspond to the spaces between the intercalated column molecules 20. Consequently, the column molecules 20 determine the size, namely the height h and the width b, of the micropores 16.

[0073] The column molecules 20 are intercalated in planes 22 between the layers 24 of the phyllosilicate 18. The column molecules 20 conveniently allow physisorption of carbon dioxide CO2 in the micropores 16 formed between them. A small elliptical axis 20h of the column molecules 20, which defines the height h of the micropores 16 or the distance between the layers 24 of the phyllosilicate 18, is therefore conveniently shown in the 2024PF00812

[0074] 14

[0075] Essentially as large as the kinetic diameter of carbon dioxide CO2, i.e., about 3.3 Å. Conveniently, however, the small elliptical axis 20h is smaller than the kinetic diameter of other molecules contained in the water-containing exhaust gas stream, for example, nitrogen N2 with a kinetic diameter of about 3.64 Å. When the water-containing exhaust gas flows onto the adsorbent 14 as part of a filtering process 100 for filtering carbon dioxide CO2 from the water-containing exhaust gas stream, the carbon dioxide CO2 can thus be physisorbed in the micropores 16, while larger molecules such as nitrogen N2 cannot penetrate the space between two layers 24 of the layered silicate 18 due to their size.

[0076] The filter material 12 can be obtained, for example, by the intercalation of ethylenediamine, 1,3-diaminopropane, 1,4-diaminobutane, spermidine or 5-(aminomethyl)-1H-1,2,4-triazol-3-amine or their doubly protonated species in sodium fluorohectorite [Na0,5] inter [Mg2,5Li0,5] oct [Si4] tet Oi0F2. During intercalation, the sodium ions, i.e., the interlayer cations, are replaced by the column molecules 20. While sodium fluorohectorite can be synthesized, intercalation of the aforementioned column molecules 20 in a natural layered silicate, e.g., vermiculite, is also conceivable or even advantageous with regard to manufacturing effort.

[0077] Surprisingly, experiments have shown that by selecting the column molecules 20, selectivity of carbon dioxide (CO2) over water (H2O) in the exhaust gas stream can also be achieved. The appropriate column molecules 20 thus make the micropores 16 less hydrophilic. This was unexpected, since the kinetic diameter of water (H2O) is approximately 2.65 Å, which is even smaller than that of carbon dioxide (CO2), and the water molecules can therefore penetrate the micropores 16. It was previously assumed that this would lead to the displacement of carbon dioxide (CO2) by water (H2O), as water (H2O) preferentially physisorbs onto the adsorbent 14. However, this does not appear to be the case. 2024PF00812

[0078] 15

[0079] Although some water (H2O) is also separated from the exhaust gas stream at adsorbent 14, thus at least partially "drying" the exhaust gas stream, as can be clearly seen in connection with Table 2 below, the proportion of separated carbon dioxide (CO2) exceeds that of separated water (H2O).

[0080] Surprisingly, the enthalpy of adsorption also varies with the pore width b, which is essentially determined by the "length" of the column molecules 20. The enthalpy of adsorption for the filter material 12 can thus be effectively optimized, reducing the energy required for regenerating the filter material 12, especially the microporous adsorbent 14, and thereby making the regeneration process less complex and more economical.

[0081] It has also been shown that the adsorption capacity of the adsorbent 14 for carbon dioxide CO2 is defined by the so-called equivalent area 26, which is shown as an example in FIG. 2 for one of the column molecules 20. The equivalent area 26 corresponds to the area required by the column molecule 20 in the plane 22.

[0082] With increasing surface area requirement of a column molecule 20 per charge, i.e., with increasing equivalent surface area 26, at a constant charge density of a layered silicate, the specific surface area SBE available for physisorption (determined by the BET method, see below) should decrease. Consequently, the uptake capacity for carbon dioxide CO2 in static single-gas adsorption should also decrease. This trend was confirmed in experiments with sodium fluorohectorite as the starting material for the adsorbent 14 and various column molecules 20 with different equivalent surface areas 26:

[0083] Both the specific surface area S B ET as well as the carbon dioxide uptake in static single-gas adsorption decrease with increasing equivalent area 26 of the column molecules used 20. This can be seen in Table 1:2024PF00812

[0084]

[0085] Table 1

[0086] In test material 1, ethylenediamine, in test material 2, 1,3-diaminopropane, in test material 3, 1,4-diaminobutane, in test material 4, spermidine, and in test material 5, 5-(aminomethyl)-1H-1,2,4-triazol-3-amine or their doubly protonated species were used as column molecules 20. The carbon dioxide uptake from Table 1, i.e., the uptake capacity for carbon dioxide (CO2), was measured in static single-gas adsorption at a temperature of 313 K and a pressure of 1 bar.

[0087] For test material 1 with the largest specific surface area S BEFor test material T (smallest equivalent surface area 26 of the column molecules 20) and the highest carbon dioxide uptake in static single-gas adsorption, a mean pore width b of approximately 14 Å was measured. For test material 2 with the next largest column molecules 20, the pore width b halved to approximately 7 Å. Counterintuitively, however, the pore width did not decrease further in test materials 3 and 4 with even larger column molecules 20. Test material 5 shows almost no argon uptake in argon physisorption measurements, which explains the specific surface area S values ​​listed in Table 1. BE T and the pore width b cannot be determined. Surprisingly, this behavior is not associated with a lack of microporosity. Rather, 2024PF00812

[0088] 17

[0089] Test material 5 is also very capable of adsorbing large quantities of carbon dioxide (CO2) and water (H2O) (see Table 1 and Table 2). This suggests that kinetic effects also play a significant role in adsorption.

[0090] The isosteric heat of adsorption Q st For carbon dioxide CO2, the range for all five test materials is between 28 kJ / mol and

[0091] 56 kJ / mol and is therefore significantly lower compared to the high energy contribution in amine scrubbing, which allows a reduction in process effort.

[0092] To test the filter properties of the five test materials, dynamic breakthrough experiments were conducted using synthetic exhaust gas. The exhaust gas consisted of

[0093] Carbon dioxide (CO2), water (H2O), nitrogen (N2), and helium were combined; helium was used as an internal standard and carrier gas because it is considered a non-adsorbable component. A powder bed fixed bed of the respective test material was flowed over or through. The breakthrough time was determined, after which an increase in the carbon dioxide concentration of the gas stream could be detected downstream of the fixed bed. Surprisingly, the breakthrough times, the adsorption capacities for the individual gases, and the selectivities of carbon dioxide (CO2) towards water (H2O) yielded an unpredictable picture. This can be seen in Table 2.

[0094]

[0095] 2024PF00812

[0096] 18

[0097]

[0098] Table 2

[0099] Despite the results from the static single-gas experiments

[0100] (Table 1) determined highest carbon dioxide uptake capacity of test material 1 with column molecules 20 of the smallest equivalent area 26, the carbon dioxide uptake up to the time of carbon dioxide breakthrough was lower at 0.64 mmol / g and the carbon dioxide breakthrough time was shorter at 468 s / g compared to

[0101] The three test materials 2, 3, and 4 with the next largest equivalent areas 26. For these test materials 2, 3, and 4, the carbon dioxide uptake until breakthrough time ranged between 0.74 mmol / g and 0.79 mmol / g, and the carbon dioxide breakthrough time ranged between 526 s / g and 559 s / g. These test materials 2, 3, and 4 differed only slightly from each other in their carbon dioxide uptake until breakthrough time and breakthrough time.

[0102] With an even larger equivalent area 26 of the column molecules 20, both the carbon dioxide uptake up to the breakthrough time and the carbon dioxide breakthrough time surprisingly decreased again.

[0103] For filter applications, in addition to the uptake capacity for carbon dioxide (CO2) ("carbon dioxide uptake"), selectivity, and especially selectivity towards water (H2O), is a crucial parameter. Nitrogen uptake is suppressed in all test materials due to the size exclusion principle, as all investigated column molecules (20j) lead to micropores (16) with a height (h) smaller than the kinetic diameter of a nitrogen molecule (3.64 Å). The selectivity for carbon dioxide (CO2) over nitrogen (N2) in the breakthrough experiments is therefore ideal. 2024PF00812

[0104] 19

[0105] The selectivity towards water (H₂O) at breakthrough time did not correlate with the pore width (b) or any other characteristic parameter of the test material. For test material 1, with column molecules (20) of the lowest equivalent area (26), the lowest molar selectivity of 1.1 was measured. Surprisingly, the maximum molar selectivity of 1.3 was found for test material 2, with a column molecule equivalent area (26) of 19. 2 / Charge measured. For test materials 3, 4 and 5 with even larger values

[0106] The selectivity decreased again when the equivalent area 26 of the column molecules 20 was increased. Consequently, an ideal, unpredictable equivalent area 26 of the column molecules 20 was determined, at which the carbon dioxide uptake from the synthetic exhaust gas stream and the selectivity towards water H2O reach an optimum. Surprisingly, this optimum does not correlate with characteristic properties of the micropores 16.

[0107] In the case of the synthetic fluorohectorite used, the ideal equivalent area 26 of the column molecules 20 lies in the range of 18 Ω. 2 / Charge up to 29 Ä 2 / Charge. This could not be derived from the prior art, which only considered the selectivities of a single material for carbon dioxide (CO2) over nitrogen (N2). Accordingly, in addition to test material 3, test materials 2 and 4 are particularly promising. Test material 2 exhibits both a higher molar selectivity for carbon dioxide (CO2) over water (H2O) and a higher carbon dioxide uptake compared to test material 3. With test material 4, an even higher carbon dioxide uptake is observed at the same molar selectivity compared to test material 3. Test material 2 therefore appears particularly promising for use in a wet gas stream filter due to the comparatively small diameter of the column molecules 20. This applies especially to its incorporation into a natural layered silicate 18, e.g., .2024PF00812.

[0108] 20

[0109] Vermiculite, for which the smaller column molecules 20 should lead to the best possible carbon dioxide uptake due to the higher charge density.

[0110] Synthesis of the investigated test materials

[0111] Following a previously published method (Breu et al. , Charge homogeneity in synthetic fluorohectorite, Chemistry of Materials 2001, 13 ( 11 ) , 4213-4220) Na-fluorohectorite of the nominal composition

[0112] [Na0.5] inter [Mg2,5Lio,5] oct [Si4] tetOiOF2 with a cation exchange capacity (CEC) of 118 mEq / 100 g was obtained by melt synthesis in a closed molybdenum crucible. The test materials were synthesized by clay exchange of the interlayer cation (sodium) in the aforementioned fluorohectorite. For this purpose, a 25% excess of the starting materials of the respective column molecules 20 (294 mg ethylenediamine dihydrochloride, 325 mg 1,3-diaminopropane dihydrochloride, 356 mg 1,4-diaminobutane dihydrochloride, 376 mg spermidine trihydrochloride, or 412 mg 5-(aminomethyl)-1H-1,2,4-triazol-3-amine dihydrochloride) was dissolved in 30 ml of double-distilled water, and 3 g of the fluorohectorite were added. The suspension was shaken upside down at room temperature for 24 h and the product was washed free of chloride ions with double-distilled water and dried.

[0113] Calculation of equivalent areas 26

[0114] The equivalent areas 26 of the column molecules 20 were calculated after simulation and geometry optimization of the molecular structure of each column molecule 20 using Jmol (version 16.1.11) and subsequent measurement of the interatomic distances. It was assumed that the column molecules 20 lie flat in the interlayer space or the planes 22 with their shortest axis, i.e., the small elliptical axis or semi-axis 20h, perpendicular to the silicate layers 24. For the calculation of the equivalent areas 26, a rectangular projection surface of the 2024PF00812 was also used.

[0115] 21

[0116] Column molecules 20 assumed.

[0117] Determination of pore height h via powder X-ray diffraction

[0118] To determine the pore heights h, powder X-ray diffractograms were recorded using an EMPYREAN diffractometer (PANalytical) in Bragg-Brentano geometry, operated with nickel-filtered Cu-Kal radiation (X = 1.540598 Å) and a PIXcel 1D Medipix3 detector. The samples were prepared by drop-feeding a suspension of the test materials onto an object support (Menzel glasses) and then dried at 90 °C for 24 h. All X-ray diffractograms were evaluated using PANalytical's Highscore Plus software. The height h of the micropores 16 was calculated by subtracting the van der Waals thickness of the silicate layer (9.6 Å) from the basal distance in the respective test material (determined from the position of the 001 reflection).

[0119] Ar gon physi sorption measurements

[0120] Argon physisorption isotherms were recorded using a Quantachrome Autosorb 1 at an Ar(I) temperature of 87.35 K. The Autosorb 1 was equipped with the CryoSync cryostat (Quantachrome). The test materials were baked out under high vacuum at 120 °C for at least 24 h prior to measurement. The data were analyzed using the ASiQwin software package (version 3.0). The specific surface areas were determined using the Brunauer-Emmett-Teller (BET) method in a sample according to Rouquerol et al. (Rouquerol et al., Is the BET equation applicable to microporous adsorbents, Stud.

[0121] Surf. Sei. Catal 2007, 160 ( 07 ) , 49-56) valid relative pressure range determined. The mean pore widths b were derived using nonlocal density functional theory (NLDFT) based on spherical / cylindrical pore models for zeolite / silica materials.

[0122] Carbon dioxide single gas experiments 2024PF00812

[0123] 22

[0124] Carbon dioxide adsorption isotherms were measured at temperatures of 273 K, 298 K, and 313 K using a Quantachrome Nova surface analyzer. The test materials were baked out under vacuum at 130 °C for at least 24 h prior to measurement. The data were analyzed using the ASiQwin software package (version 3.0). The adsorption isotherms were fitted using the IAST++ software package. Depending on the desired minimization of the fitting error, the adsorption isotherms were fitted using either the dual-site Langmuir-Freundlich model, the dual-site Langmuir model, the Langmuir-Freundlich model, or the Langmuir isotherm model. The calculations were based on the Clausius-Clapeyron equation.

[0125]

[0126] The isosteric heats of adsorption Q were determined for a given adsorbed quantity n. st calculated. Here, T is the respective measured temperature, p is the pressure, and R is the universal gas constant.

[0127] Dynamic gas absorption breakthrough experiments

[0128] The dynamic breakthrough experiments were performed on a 3P Instruments mixSorb S Dynamic Sorption Analyzer. The gas phase at the outlet of the adsorber column was analyzed using a mass-selective detector. The mass spectrometer used was a Pfeiffer Vacuum Omnistar GSD 320. Prior to the measurement, the test materials were purged in a helium stream (100 ml / min) for 6 h at a temperature of 80 °C. Subsequently, the adsorber column was equilibrated to the measurement temperature using a PolyScience recirculating bath. Measurements were taken at 40 °C and a pressure of 1 bar. The composition of the simulated exhaust gas stream was as follows: carbon dioxide 6.74%, water 6.64%, nitrogen 52.80%, and helium 33.82%. The total flow rate was 32 ml / min. Helium was used as the internal standard and carrier gas. It was considered a non-adsorbable component. The measurements were taken after reaching equilibrium. 2024PF00812

[0129] 23

[0130] Completed. All data were evaluated using a combination of the mixSorb Manager software package from 3P Instruments (version 1.3.0.8) and the QUADERA software package from Pfeiffer Vacuum (version 4.62). The amount of adsorbed gas was determined by integrating the breakthrough curves according to the input volume fraction of the analysis gases and using the "Advanced compute flowrate changes" (ACFC) module. The breakthrough curves were corrected by subtracting the corresponding dead times. The dead times were determined by integrating a measured breakthrough experiment with an inert fixed bed (glass beads with a diameter of 2 mm; Merck) under the same conditions as during the experiment. The molar selectivities were calculated as follows:

[0131]

[0132] with Qi, 2 as the adsorption capacity of the respective gas and pi,2 as the molar fraction of the respective gas in the feed mixture.

[0133] Although the invention has been further illustrated and described in detail by the preferred embodiments, the invention is not limited by the disclosed examples and other variations can be derived from them by a person skilled in the art without leaving the scope of protection of the invention.

[0134] Regardless of the grammatical gender of a particular term, persons with male, female or other gender identities are included.

Claims

2024PF00812 24 Patent claims 1. Wet gas stream filter (10) for filtering carbon dioxide (CO2) from a water-containing exhaust gas stream, comprising a filter material (12) containing a microporous adsorbent (14) for selective physisorption from water-containing exhaust gas flowing onto the filter material (12) in micropores (16) of the adsorbent (14), wherein the microporous adsorbent (14) comprises a layered silicate (18) and column molecules (20) intercalated in the layered silicate (18), which determine the size of the micropores (16).

2. Moist gas stream filter (10) according to claim 1, wherein the column molecules (20) have a small elliptical axis (20h) between 2.7 Å and 3.4 Å and the height (h) of the micropores (16) is determined by the length of this small The semi-axis (20h) is determined.

3. Moist gas flow filter ( 10 ) according to one of claims 1 or 2 , wherein the filter material ( 12 ) is made of Na fluorohectorite .

4. Moist gas flow filter ( 10 ) according to one of claims 1 or 2 , wherein the filter material ( 12 ) is made of vermiculite .

5. Moist gas stream filter ( 10 ) according to any of the preceding claims, wherein ethylenediamine, 1 ,3-diaminopropane, spermidine or 5-(aminomethyl )-1H-1 ,2 ,4-triazol-3-amine is intercalated into the layered silicate ( 18 ) as column molecules ( 20 ).

6. Wet gas stream filter (10) according to one of the preceding claims, wherein the column molecules (20) are a Equivalent area ( 26 ) between including 18 Ä 2 / Charge and 29 Ä 2 / carrying a load.

7. Moist gas stream filter ( 10 ) according to one of the preceding claims , wherein an absorption capacity of the 2024PF00812 25 filter material ( 12 ) for carbon dioxide ( CO2 ) more than The value is 0.74 mmol / g.

8. Filter system (1) for filtering carbon dioxide (CO2) from a water-containing exhaust gas stream, comprising a wet gas stream filter (10) according to one of the preceding claims for connection to a carbon dioxide point source, in particular e.g. a combustion device (V).

9. Filter system ( 1 ) with at least two fixed beds formed from the filter material ( 12 ) which can be independently supplied with water-containing exhaust gas .

10. Filtering method ( 100 ) for filtering of Carbon dioxide (CO2) from a water-containing exhaust gas stream, in which the water-containing exhaust gas stream flows towards a filter material (12) with a microporous adsorbent (14) which has a layered silicate (18) and column molecules (20) intercalated in the layered silicate (18) which determine the size of micropores (16), so that the carbon dioxide (CO2) is selectively physisorbed in the micropores (16) of the adsorbent (14).

11. Synthesis process for a microporous adsorbent (14) for use in or as a filter material (12) for a wet gas stream filter (10) according to any one of claims 1 to 7, wherein, starting from a synthesis starting material comprising one of the chloride compounds ethylenediamine dihydrochloride, 1,3-diaminopropane dihydrochloride, 1,4-diaminobutane dihydrochloride, spermidine trihydrochloride or 5-(aminomethyl)-1H-1,2,4-triazol-3-amine dihydrochloride or formed by dissolving one of these compounds in water, the amine compounds ethylenediamine, 1,3-diaminopropane, 1,4-diaminobutane, spermidine or 5-(aminomethyl)-1H-1,2,4-triazol-3-amine are obtained, respectively. whose doubly protonated species are intercalated as column molecules ( 20 ) by cation exchange and subsequent chloride removal in a layered silicate ( 18 ).2024PF00812 26 12. Use of a filter material ( 12 ) for filtering carbon dioxide ( CO2 ) from a water-containing exhaust gas stream, wherein the filter material ( 12 ) contains a microporous adsorbent ( 14 ) for selective physisorption from water-containing exhaust gas flowing onto the filter material ( 12 ) in micropores ( 20 ) of the adsorbent ( 14 ) and the microporous adsorbent ( 14 ) comprises a layered silicate ( 18 ) and column molecules ( 20 ) intercalated in the layered silicate ( 18 ) which determine the size of the micropores ( 20 ).

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