CO2 adsorption system and method using humidity-stable polystyrene-divinylbenzeneamine functionalized polymer adsorbent

Abstract

A method for separating gaseous carbon dioxide from air, in particular from ambient air (1), by cyclic adsorption / desorption using an adsorbent (3), said adsorbent (3) being a solid, inorganic or organic, non-polymeric or polymeric support material, surface functionalized with amino functional groups, capable of reversibly binding carbon dioxide, preferably with a solubility of 10 to 25 m as measured by nitrogen adsorption method. 2 / g and a cumulative pore volume in the range of 50 to 350 nm of 0.3 to 1.5 cm 3 / g range of pore volume distribution.

Description

[Technical field]

[0001] The present invention relates to the use of an adsorbent material for separating gaseous carbon dioxide from a gas mixture, in particular for direct air capture (DAC), and to a corresponding method, in particular for the direct capture of carbon dioxide from the atmosphere. [Background technology]

[0002] The Paris Agreement created a consensus on the threat of climate change and the need for a global response to keep the increase in global temperatures well below 2°C above pre-industrial levels. A range of possibilities have been presented to achieve this goal, from planting new forests to technological measures. Although afforestation has received widespread public sympathy, there is debate about the scope and feasibility of such projects, and it may not be as simple an approach as some may think.

[0003] The most advanced technological approaches include CO2 sequestration from point sources, such as flue gas capture, and the direct capture of CO2 from the air, known as direct air capture (DAC). Both technological strategies have the potential to mitigate climate change.

[0004] Air CO2 capture has specific advantages over flue gas capture: (i) DACs can accommodate emissions from distributed sources (e.g., cars, airplanes), (ii) can be installed independently of the source rather than attached to it, and (iii) can accommodate historical emissions, allowing negative emissions when combined with a method to safely and permanently store CO2 (e.g., underground mineralization).DACs are also used as one of several means to provide key reactants for the synthesis of renewable materials and fuels, as described, for example, in US Pat. No. 5,399,363.

[0005] Concerning suitable capture materials, several DAC techniques are described in the literature, for example the formation of calcium carbonate using alkaline earth oxides in water, as described in US Pat. No. 5,399,633. A different approach is the use of solid CO2 adsorbents (hereafter referred to as adsorbents), which are characterized by the use of packed beds to capture CO2 at the gas-solid interface. Such adsorbents can include various types of amine-functionalized and polymeric adsorbents, such as immobilized aminosilane-based adsorbents as reported in US Pat. No. 5,399,633 and amine-functionalized cellulose as disclosed in US Pat. No. 5,399,633.

[0006] US Pat. No. 5,399,633 describes the use of ion exchange materials comprising aminoalkylated bead polymers to remove carbon dioxide from industrial applications.

[0007] Patent Document 6 describes an adsorbent for reversibly adsorbing CO2 from a gas mixture, the adsorbent being composed of a polymeric adsorbent having primary amino functional groups and a molecular weight of 25 to 75 mg. 2 / g (calculated by the Brunauer-Emmet-Teller method) and a specific average pore size. After recovery, the material is regenerated by applying pressure or humidity swing methods.

[0008] Patent Document 7 describes a method for removing carbon dioxide using a polymer adsorbent having a primary amine unit immobilized on a solid support. In this case, the adsorbent is regenerated by heating the adsorbent in a temperature range of 55 to 75°C under aeration.

[0009] Patent documents 8 and 9 describe a method in which ground ion exchange resin is introduced into a polymer binder that melts at a temperature of 125-130°C, and the heterogeneous mixture is molded into a sheet having a maximum thickness of 0.125 mm for water purification applications.

[0010] Patent Document 10 discloses a structure including an adsorbent having amine groups capable of reversible adsorption-desorption cycles for recovering CO2 from a gas mixture, the structure being composed of fiber filaments, the fiber material being carbon and / or polyacrylonitrile.

[0011] Patent Document 11 discloses a porous adsorbent structure capable of reversible adsorption / desorption cycles for capturing CO2 from a gas mixture, comprising a support matrix formed by a web of surface-modified cellulose nanofibers. The support matrix has a porosity of at least 20%. The surface-modified cellulose nanofibers are made of cellulose nanofibers with a diameter of about 4 nm to about 1000 nm and a length of 100 nm to 1 mm, and are covered with a coupling agent covalently bonded to the surface. The coupling agent comprises at least one monoalkyldialkoxyaminosilane.

[0012] US Patent No. 5,999,366 provides a novel solid adsorbent synthesized by the reaction of polyamines with polyaldehyde dendrimer (P-dendrimer) compounds. The adsorbent is stable and exhibits rapid reaction kinetics with carbon dioxide, making it applicable for carbon capture and easily regenerative for further use. The material is stable in aqueous and organic media as well as strong acids and bases. The adsorbent maintains full capacity even after long-term use. The material can be used for CO2 capture from pure CO2 streams, mixed gas streams, simulated flue gases and ambient air. In addition, the material can be attached to surfaces for reversible CO2 capture applications other than bulk particle processes.

[0013] Patent Document 13 discloses a method for separating gaseous carbon dioxide from a mixture by cyclic adsorption and desorption using a unit including an adsorbent structure having an adsorbent, the method comprising the steps of: (a) contacting the mixture with an adsorbent to adsorb the gaseous carbon dioxide under ambient conditions; (b) evacuating the unit to a pressure in the range of 20-400 mbarabs and heating the adsorbent to a temperature in the range of 80-130°C using an internal heat exchanger; and (c) repressurizing the unit to ambient atmospheric conditions and actively cooling the adsorbent to a temperature above ambient temperature; wherein in step (b), steam is injected into the unit to flow through and contact the adsorbent under saturated steam conditions, wherein the molar ratio of injected steam to released gaseous carbon dioxide is less than 20:1.

[0014] Irani et al. (Non-Patent Document 1) proposed an effective adsorbent (polyHIPE / PEI) for CO2 capture technology applications. For this purpose, a porous polymer was prepared by high internal phase emulsion (HIPE) using 2-ethylhexyl methacrylate (EHMA) and divinylbenzene (DVB). The prepared porous polymer (polyHIPE) was then used as a new support for wet impregnation of polyethyleneimine (PEI), resulting in polyHIPE / PEI adsorbent. The prepared adsorbent was characterized. The CO2 adsorption capacity of polyHIPE at an optimal loading of 60 wt% PEI reached 4 mmol CO2 / g adsorbent at 70 °C with 10 vol.% CO2 and 3 vol.% H2O in N2. Kinetic and thermodynamic adsorption studies showed that the activation energies for CO2 adsorption and desorption of polyHIPE / PEI were 13.74 kJ / mol and 36.12 kJ / mol, respectively.

[0015] Jung et al. reported in Non-Patent Document 2 that a solid amine adsorbent with suitable particle size was prepared with high CO2 adsorption capacity using poly(ethyleneimine) (PEI) as the amine and mesoporous poly(methyl methacrylate) (PMMA) beads as the support. The PMMA-supported adsorbent impregnated with PEI showed a maximum CO2 adsorption capacity of 4.26 mmol / g at 75°C in pure CO2 gas flow. The effect of temperature on the adsorption capacity of PMMA-55 was investigated, and the maximum adsorption capacity was obtained at 50°C and 180 min of CO2 exposure time, which was different from the trend of many silica-supported adsorbents. The effect of surfactant addition on the adsorption performance of PMMA-supported adsorbents was different from that of silica-supported adsorbents, due to the different surface properties of PMMA and silica. Adsorption / desorption cycles were also performed to investigate the suitability of this amine adsorbent for potential applications.

[0016] Hammache et al. report in Energy & fuels that an amine sorbent, produced by impregnating silica with polyethyleneimine, was tested for steam stability. The stability of the sorbent was investigated in a fixed-bed reactor using multiple steam cycles of 90% vol. H2O / He at 105 °C, and the gas effluent was monitored by mass spectrometry. The CO2 uptake of the sorbent was found to decrease with repeated exposure to steam. Characterization of the spent sorbent using N2 physisorption, SEM, and thermogravimetric analysis (TGA) revealed that the decrease in CO2 loading could be attributed to re-aggregation of the amine within the silica pores. No effect of the carrier was observed in this study. The commercial SiO2 used, Cariact G10, was found to be stable under the conditions used. Subjecting the sorbent to several steam cycles was found to decrease the CO2 uptake, but continuous exposure of the sorbent to steam did not significantly affect its performance. The steam stability of a silane-based adsorbent consisting of a mixture of PEI and aminopropyltriethoxysilane on a SiO2 support was also investigated. Similar to the non-silane-based adsorbents, the CO2 loading of this adsorbent decreased upon steam exposure, but the mechanism of this change was not postulated.

[0017] No. 5,999,333 relates to a regenerative absorption device for removing CO2 from exhaled gases during anesthesia. The device comprises a vessel having an inlet for the exhaled gases and an outlet for exhaust gases with CO2 substantially removed therefrom. The device comprises an ion exchanger having a CO2 absorption capacity disposed within the vessel, through which gas flows from the inlet to the outlet. A novel anesthesia method includes the use of a CO2 absorption device.

[0018] Liu et al. reported a method for preparing a solid amine adsorbent by modifying a porous polystyrene resin (XAD-4) with chloroacetyl chloride via Friedel-Crafts acylation reaction and then amminating it with tetraethylenepentamine (TEPA) in Non-Patent Document 3. The adsorption behavior of CO2 from simulated flue gas onto the solid amine adsorbent was evaluated. Factors that may determine the CO adsorption performance of the adsorbent, such as amine species, adsorption temperature, and moisture, were investigated. Experimental results showed that the longer-chain solid amine adsorbent (XAD-4-TEPA), modified with TEPA, exhibited better amine efficiency than the other two amine species with shorter chains. Because the reaction between CO2 and amine groups is an exothermic reaction, the CO2 adsorption capacity obviously decreased with increasing temperature, and the adsorption amount reached 1.7 mmol / g at 10 °C in the dry state. The presence of water could significantly increase the CO2 adsorption amount of the adsorbent, thereby promoting the chemical adsorption of CO2 onto XAD-4-TEPA. The adsorbent maintained almost the same adsorption capacity after 10 adsorption-desorption cycles. These results indicate that the amine-functionalized XAP-4 resin is a promising CO2 adsorbent.

[0019] Patent Document 13 discloses a method for separating gaseous carbon dioxide from a mixture by cyclic adsorption / desorption using a unit including an adsorbent structure having an adsorbent, the method comprising the steps of: (a) contacting the mixture with an adsorbent to adsorb the gaseous carbon dioxide under ambient conditions; (b) evacuating the unit to a pressure in the range of 20-400 mbar and heating the adsorbent to a temperature in the range of 80-130° C.; and (c) repressurizing the unit to ambient atmospheric conditions and actively cooling the adsorbent to a temperature above ambient temperature; wherein in step (b), steam is injected into the unit to flow through and contact the adsorbent under saturated steam conditions, wherein the molar ratio of injected steam to released gaseous carbon dioxide is less than 20:1. [Prior art documents] [Patent documents]

[0020] [Patent Document 1] International Publication No. 2016 / 161998 [Patent Document 2] US Patent Application Publication No. 2010 / 034724 [Patent Document 3] U.S. Patent No. 8,834,822 [Patent Document 4] International Publication No. 2012 / 168346 [Patent Document 5] International Publication No. 2011 / 049759 [Patent Document 6] International Publication No. 2016 / 037668 [Patent Document 7] International Publication No. 2016 / 038339 [Patent Document 8] U.S. Patent No. 6,716,888 [Patent Document 9] U.S. Patent No. 6,503,957 [Patent Document 10] US Patent Application Publication No. 2012 / 076711 [Patent Document 11] US Patent Application Publication No. 2018 / 043303 [Patent Document 12] US Patent Application Publication No. 2019 / 224647 [Patent Document 13] US Patent Application Publication No. 2017 / 203249 [Patent Document 14] U.S. Patent No. 6,279,576 [Non-patent literature]

[0021] [Non-Patent Document 1] “Facilely synthesized porous polymer as support of poly (ethyleneimine) for effective CO2 capture”, Energy (157), p. 1-9 (2018) [Non-Patent Document 2] Energy Fuels 2014, 28, 3994-4001 [Non-Patent Document 3] J. APPL. POLYM. SCI. 2017, 134, 45046 Summary of the Invention

[0022] The present invention relates to a process, in particular a DAC process, for the separation of gaseous carbon dioxide from a gas mixture, preferably from at least one of ambient air, flue gas and biogas, using a particular adsorbent material, and to the use of such a particular adsorbent material for gas separation purposes, in particular for DAC.

[0023] It is shown herein that the prior art claims that in particular crosslinked polystyrene adsorbents substituted with primary aminoalkyl functional groups and characterized by a high specific surface area, as well as other adsorbents based on inorganic or organic non-polymeric or polymeric materials with high specific surface area, are particularly useful for DAC applications. Surprisingly, and contrary to this perception, it has now been found that inorganic or organic non-polymeric or polymeric materials, in particular (but not exclusively) crosslinked polystyrene adsorbents, such as crosslinked polystyrene adsorbents based on divinylbenzene (DVB), e.g. poly(styrene-co-divinylbenzene) functionalized with amino groups, have a very specific median range of specific surface area and a specific range of pore volume distribution (i.e. a cumulative pore volume in the range of 50-350 nm of 0.28-1.5 cm3). 3It has been found that inorganic or organic non-polymeric or polymeric materials, which combine a hygroscopicity of 0.01 to 0.15 m / g, exhibit an unexpectedly stable carbon dioxide adsorption behavior in the vapor desorption process that is substantially independent of humidity conditions. This is crucial for the stability of the process under various weather conditions and input gas composition conditions, i.e., under conditions of varying relative humidity (RH is defined, for example, as the amount of water vapor present in the air, expressed as a percentage of the amount required for saturation at the same temperature, where this temperature is usually taken to be 15° C. in the experiments using vapor desorption at the inlet airstream of a DAC device equipped with a corresponding adsorbent; the relative humidity given here was generated using a humidifier system that mixes a dry stream (RH 0%) with a saturated stream in different ratios depending on the target RH. The saturated stream was generated by bubbling the dry gas through a water column. The relative humidity was measured using a Vaisala Humidity and Temperature Probe HMP110 type device). In an exemplary adsorption test performed after air purge thermal swing desorption, the reactor temperature was kept at 30°C and RH was controlled by varying the temperature of the bubbler supplying the inlet gas to reach the target RH value at 30°C.

[0024] Specifically, according to the invention, the adsorbent is a solid, inorganic or organic, non-polymeric or polymeric support material, surface functionalized with amino functional groups, capable of reversibly binding carbon dioxide, and having a BET specific surface area of ​​10 to 25 m. 2 / g, and the cumulative pore volume in the pore diameter range of 50 to 350 nm is 0.28 to 1.5 cm 3 / g or 0.3~1.5cm 3 / g.

[0025] Indeed, one of the unexpected findings of this study was that, for vapor desorption, there exist adsorbents suitable for high relative humidity (RH% above 60%) and low relative humidity (RH% in the range of 0-60%). 2 / g, the latter being 25 m 2It is characterized by having a specific surface area of ​​more than 100 nm / g.

[0026] Surprisingly, in contrast to this, the BET specific surface area of ​​such adsorbents, i.e. adsorbents based on inorganic or organic non-polymeric or polymeric materials, is within the range of 10 to 25 m as claimed in the claims. 2 / g range, and such adsorbents have a cumulative porosity in the range of 50-350 nm as detailed below, the corresponding adsorbents have been found to be substantially stable in terms of carbon dioxide adsorption behavior over the entire relative humidity range of 0-100% without experiencing overall capacity fade failure.

[0027] This behavior is specific to the vapor desorption situation: in fact, when vapor-free desorption, and in particular thermal desorption processes, are used, this surprisingly stable behavior of the relative humidity independent retention capacity selective for this type of porosity is not observed, as will be demonstrated in detail below.

[0028] The stable carbon dioxide capture capacity over varying relative humidity allows for a highly efficient, correspondingly stable and controllable process independent of relative humidity conditions, and optimized process control for adsorbents based on inorganic or organic non-polymeric or polymeric materials.

[0029] Interestingly, all these adsorbents, which behave differently in the vapor desorption process, regardless of the specific surface area value, show practically the same carbon dioxide capture behavior when used in air-purged thermal swing, i.e. when desorption is performed only by heating and not by introducing vapor. For these adsorbents, the amount of carbon dioxide adsorbed under these conditions increases slightly with increasing relative humidity over the entire range. This behavior is likely due to the increase in amine efficiency at higher RH, as is well documented in the literature. In such a process, the adsorbent bed is heated (resistively heated) and desorbed by passing air and / or N2 through it in each cycle.

[0030] Alternatively, if the adsorbent bed is regenerated by condensing the vapor instead of inductively heating it, an unexpectedly different behavior is obtained. Specifically, a completely different dependence on RH% is observed. The low surface area adsorbent performs best at high RH% but does not perform well at low RH%, whereas the high surface area adsorbent performs well at low RH% but loses capacity at high RH%.

[0031] In contrast, an adsorbent having the claimed features exhibits much more consistent behavior across the RH% range.

[0032] This is due to the particular surface and porosity characteristics of the claimed adsorbents, in particular the greater cumulative pore volume present in the larger pore ranges.

[0033] Thus, the present invention relates to a sorbent that also has a suitable morphology (surface area, and preferably total pore volume and pore size distribution) to function over a wide range of RH% without undue fluctuations in cycle CO capture capacity, thus allowing continuous and relatively constant plant operation through different times of day (e.g., humid nights and dry days) and seasonal changes (hot and humid summers and dry and cold winters).

[0034] Specific characteristics of such adsorbents are that they have a surface area of ​​10 to 25 or 10 to 20 m 2 / g, and the pore volume of the large pores is large (especially when the pore diameter is >100 nm and the pore volume in the range of 50 to 350 nm is 0.28 to 1.5 cm 3 / g or 0.3~1.5cm 3 / g).

[0035] These adsorbents can be polymeric or non-polymeric based, they can be organic or inorganic and can be hybrid types, and the main feature of these adsorbents is the physical rather than chemical nature of the porous structure.

[0036] In particular, the functionalized solid support of the adsorbent has a porosity in the ranges described in the claims, with a high proportion and volume of macropores (pores with a diameter greater than 50 nm), and more preferably also has a low proportion or substantially no mesopores, i.e. pores with a diameter between 2 and 50 nm, and / or preferably also has a low proportion or substantially no micropores, i.e. pores with a diameter not greater than or below 2 nm, which reduces the accumulation of condensed water in the porosity and provides a much higher capacity in cyclic operation for the carbon dioxide capture process in the presence of water and / or steam.

[0037] In the context of the present disclosure, the expressions "ambient atmospheric pressure" and "ambient atmospheric temperature" refer to the pressure and temperature conditions to which a plant operated outdoors is exposed, i.e. typically, ambient atmospheric pressure means a pressure in the range of 0.8 to 1.1 barabs, and typically, ambient atmospheric temperature means a temperature in the range of -40 to 60°C, more typically -30 to 45°C. The gas mixture used as input to the process is preferably ambient air, i.e. air at ambient atmospheric pressure and ambient atmospheric temperature, which typically has a CO2 concentration in the range of 0.03 to 0.06% by volume. However, air with a lower or higher CO2 concentration, for example with a concentration of 0.1 to 0.5% by volume, can also be used as input to the process, so generally speaking, the input CO2 concentration of the input gas mixture is preferably in the range of 0.01 to 0.5% by volume. However, exhaust gas may also be used as the source, in which case the input CO2 concentration of the input gas mixture will typically be in the range of up to 20% by volume or up to 12% by volume, preferably in the range of 1-20% by volume or 1-12% by volume.

[0038] In the carbon dioxide capture process step sequence (a) to (e) detailed herein, reference is made in steps (a) and (e) to ambient atmospheric pressure and temperature conditions. This only applies if the feed gas mixture is provided under these conditions, e.g. in the case of direct air capture where the source of the gas mixture is atmospheric air. However, if the source of the gas mixture is another source, it is quite possible that the feed conditions are not ambient atmospheric pressure and / or not ambient atmospheric temperature conditions. In particular in the case of flue gases, the gas mixture may and often is at an elevated temperature, e.g. above room temperature, even above 50°C. The temperature may go up to 70°C, in which case the setup is usually adjusted so that the temperature at which carbon dioxide is desorbed from the adsorbent in step (c) is at least 10°C, preferably at least 20°C, higher than the temperature of the feed gas. Under these non-atmospheric temperature and pressure conditions in steps (a) and (e), the pressure and temperature conditions will therefore typically be different, in particular the contacting in step (a) is carried out under the temperature and pressure conditions of the feed gas mixture and in step (e) the adsorbent is brought to the temperature and pressure conditions of the feed gas mixture.

[0039] The temperature and humidity range characteristics of the ambient air to which the adsorbent is exposed strongly influence the performance of amine-based adsorbents. For example, in dry conditions (i.e., relative humidity RH=0%), amines exhibit an efficiency, defined as the stoichiometric coefficient of reaction between amino groups and CO2, of 2:1, whereas in humid conditions this efficiency is 1:1. High relative humidity of the gas stream containing carbon dioxide is advantageous in terms of the adsorption capacity, defined as the number of moles of CO2 captured per kilogram of adsorbent, during the adsorption process. The prior art does not disclose the effect of high relative humidity of the gas stream containing CO2 on the cycle adsorption / desorption performance when the adsorbent is desorbed using steam.

[0040] More generally, the invention proposes a method for separating gaseous carbon dioxide from a gas mixture comprising said gaseous carbon dioxide and further gases other than gaseous carbon dioxide, preferably from ambient air, by cyclic adsorption-desorption using an adsorbent which adsorbs said gaseous carbon dioxide in a unit. When ambient air is mentioned below, this also includes other gas mixtures such as flue gas or biogas.

[0041] The method comprises repeating at least the following steps (a) to (e) sequentially and in this order: (a) contacting said gas mixture, preferably ambient air, with an adsorbent material to adsorb at least said gaseous carbon dioxide onto the adsorbent material by flow-through of said unit in an adsorption step, preferably under ambient atmospheric pressure conditions (if ambient air is forced out of the apparatus using a ventilator or the like, even if the air forced out of the reactor by the ventilator has a pressure slightly higher than the surrounding ambient atmospheric pressure, this is also considered to be ambient atmospheric pressure conditions in accordance with the present application, the pressure being within the ranges detailed above in the definition of "ambient atmospheric pressure") and ambient atmospheric temperature conditions; (b) separating the adsorbent having adsorbed carbon dioxide within the unit from the throughflow, preferably while substantially maintaining the temperature of the adsorbent; (c) injecting a saturated or superheated steam stream through said unit, thereby inducing an increase in the temperature of the adsorbent to a temperature of 60-110°C to initiate desorption of CO2; (d) removing at least the desorbed gaseous carbon dioxide from the unit and separating the gaseous carbon dioxide from the vapor by condensation downstream of the unit; (e) subjecting the adsorbent to ambient air temperature conditions (even if the adsorbent is not cooled to ambient air temperature conditions strictly in this step, this is still considered to be the case, and preferably the ambient air temperature established in step (e) is within +25°C, preferably +10°C or +5°C of the ambient air temperature). Includes.

[0042] As pointed out above, according to the invention, the adsorbent is a solid, inorganic or organic, non-polymeric or polymeric support material, functionalized on the surface with amino functional groups, capable of reversibly binding carbon dioxide, which has a carbon dioxide adsorption capacity of 10 to 25 m, determined by applying the BET method according to ISO 9277, preferably based on measurements by nitrogen adsorption. 2 / g. BET (Brunauer, Emmett und Teller) surface area analysis was used to determine the BET specific surface area by applying the method described in ISO 9277, and the pore volume distribution was determined to have a cumulative pore volume in the range of 50-350 nm of 0.28-1.5 cm 3 / g or 0.3~1.5cm 3 / g range.

[0043] According to a first preferred embodiment, the adsorbent has a molecular weight of 10 to 20 m, preferably measured by nitrogen adsorption. 2 / g, preferably 12 to 20 m 2 / g.

[0044] More preferably, the adsorbent has a pore size distribution, as measured by mercury porosimetry, such that 90%, preferably 95%, of the pore volume is in the range of 50 to 400 nm, preferably 80 to 350 nm. For parameters used in mercury porosimetry measurements, see details provided later in this specification.

[0045] Alternatively or additionally, the adsorbent preferably has a pore volume distribution, measured by mercury intrusion porosimetry, such that the maximum pore volume lies in a pore diameter range of 80 to 150 nm, preferably in a pore diameter range of 100 to 150 nm, such that preferably 90%, more preferably 95% of the total pore volume of the distribution lies in the range of -50 nm to +150 nm, preferably -40 nm to +100 nm, of the diameter of said maximum of the pore volume distribution.

[0046] According to yet another preferred embodiment, the adsorbent has a viscosity of 0.3 to 1 cm as measured by mercury intrusion porosimetry.3 / g, preferably 0.35 to 0.80 cm 3 / g, most preferably 0.4 to 0.7 cm 3 / g range of total pore volume.

[0047] The adsorbent can also be characterized by its nitrogen content. Thus, according to another preferred embodiment, said adsorbent has a nitrogen content in the range of 5-50 wt.%, preferably in the range of 6-15 wt.% or 8-15 wt.% or 10-12 wt.%, respectively, of dry adsorbent. Drying in this measurement is defined as treating 6 g of adsorbent at 90° C. for 90 min under a N2 flow of 2 L / min.

[0048] As noted above, the method using the particular adsorbent can essentially be carried out at any practical relative humidity (RH%), but has the advantage that it is particularly suitable and stable under conditions of fluctuating relative humidity, i.e., conditions where the RH% is in the range of 20-80%.

[0049] The solid inorganic or organic non-polymeric or polymeric support material of the adsorbent can be based on an organic or inorganic, preferably organic polymeric support, such as a thermoplastic or thermosetting material. Thermoplastic materials are also possible, which are crosslinked in a later step of the synthesis. The solid polymeric support material can be a crosslinked polymeric material, such as a polystyrene material or a polyvinyl material, which can be crosslinked with a divinyl aromatic compound, preferably a styrene-divinylbenzene copolymer (poly(styrene-co-divinylbenzene), PS-DVB). The solid support material can be in the form of beads, which can be monodisperse or heterodisperse.

[0050] For example, to introduce an aminomethyl functionality into the PS-DVB backbone, the following reaction pathway can be carried out:

[0051] [ka]

[0052] In the first step, PS-DVB can be chloromethylated using chloromethyl ether and a catalyst such as AlCl3 (a) to form a chloromethyl group attached to the backbone of PS-DVB. An amino group can then be introduced by reaction with hexamethylenetetramine (b). As can be seen from the structure of step c, this results in the formation of a quaternary ammonium salt that cannot covalently bond with CO2. To obtain a primary amine capable of binding with CO2, the intermediate of step c can be hydrolyzed with HCl, which not only provides the primary amine but also causes reaction of the amine in an acid-base reaction to form ammonium chloride. A final reaction with NaOH can be carried out to bring the amine to its final state as a free base for capture. The final structure of the aminomethyl PS-DVB sorbent used in the DAC process shown in the experimental proof below is shown in step d.

[0053] The solid inorganic or organic non-polymeric or polymeric support material of the adsorbent may also be an inorganic non-polymeric support, preferably selected from the group consisting of silica (SiO2), alumina (Al2O3), titania (TiO2), magnesia (MgO), clay and mixed forms thereof, such as silica-alumina (SiO2-Al2O3), or mixtures thereof.

[0054] The solid support material of the adsorbent may be in the form of hollow or solid particles, beads, microspheres, monolithic structures, sheets, hollow or solid fibers, preferably hollow or solid fibers in a woven or nonwoven structure, or extrudates.

[0055] The solid inorganic or organic non-polymeric or polymeric support material of the adsorbent can also be in the form of particles of such support material (e.g. powder or granules having an average size (D50) of 0.002 to 4.0 mm), which particles can be embedded in a solid matrix in the form of a composite.

[0056] The adsorbent is provided by a support material whose surface is functionalized with amino functional groups, and which exhibits a specific surface area as claimed and a pore volume distribution as claimed. Such adsorbents can take various three-dimensional forms as mentioned above, and can take the form of monoliths, layers, sheets, hollow or solid fibers or particles. These structures can also form or be embedded in higher-order structures without further elements, preferably when, for example, the fibers take the form of woven or nonwoven structures or when the particles are formed into monolithic structures made of adsorbent particles. However, the higher-order structures can also include further structural elements. For example, the higher-order structures can have a laminate structure that includes a layer of a porous material that is not itself an adsorbent, for example a polymeric woven or nonwoven material, and one or more layers of adsorbent, either in the form of a powder or a particulate structure, can be added to one or both sides of such a layer. Alternatively, one layer of adsorbent is embedded in two outer layers of porous material. In the latter preferred case, the adsorbent is sandwiched between two or more outer layers of air permeable / porous material, preferably polymeric air permeable / porous material, which may also take the form of layers with semipermeable membranes, and these laminates, which may be flexible or rigid, can then be structured to form further higher order structures, e.g. panels with air channels, in the form of such laminates with adsorbents arranged in, for example, zigzag or wavy patterns. Such panels can also form more advanced higher order structures, such as modules with a rigid frame and a mesh covering the outer surface, thereby providing structures that are easy to handle and replace.

[0057] It should be noted that the porosity characteristics, i.e. the specific surface area and pore volume distribution, as well as the total pore volume, and other characteristic parameters detailed herein in relation to the adsorbent itself, can and very often do differ for such a superstructure as a whole. Thus, such a superstructure containing a particular adsorbent as a whole may and very often has porosity characteristics that differ from those claimed, for example due to additional layers. However, it is the specific surface area and pore volume distribution of the embedded adsorbent that is important for the actual carbon dioxide capture properties, and such a superstructure must meet the specific surface area and pore volume distribution characteristics mentioned above (and preferably further characteristics detailed herein). In particular, for example, when there is a stack with an outer non-adsorbing porous layer and a central layer of an adsorbent according to the invention, the cumulative pore volume contributed by the non-adsorbing layers of the complete structure can be significantly larger than that of the embedded adsorbent alone.

[0058] In the context of this aspect of the invention, when reference is made to a solid matrix forming a composite solid inorganic or organic non-polymeric or polymeric support material, this means that it is the solid matrix that ultimately provides the actual three-dimensional structure forming the solid inorganic or organic non-polymeric or polymeric support material of the adsorbent itself (although this does not exclude the adsorbent being embedded in or attached to further structural elements that do not contribute to carbon dioxide capture). This aspect may include situations where a separate structure provides the actual support, which is then coated, impregnated or soaked with a binder to form a composite solid matrix with the adsorbent particles and then dried, crosslinked or solidified in another manner, or where the binder provides for the attachment of the adsorbent particles to the actual support and / or the formation of a coating on that support together with the adsorbent particles.

[0059] Such composites, preferably formed only by the solid matrix and the sorbent particles, can take the form of a sheet or foil, although granular or monolithic structures are also possible. These elements providing a solid inorganic or organic non-polymeric or polymeric composite can be mounted in or on a corresponding support structure, such as a frame of some kind for the actual carbon dioxide capture process.

[0060] In particular, foils or sheets of such composite materials comprising a solid inorganic or organic, non-polymeric or polymeric carrier material of the adsorbent can be obtained by extrusion, for example said particles of surface-functionalized adsorbent being added for example to a thermoplastic matrix material after its melting and before thermoforming, this is possible by melt mixing or solution casting, but also by sputtering the adsorbent particles onto a liquid layer or at least a surface-softened layer of the solid matrix thermoplastic material, if necessary followed by a lamination process between rolls.

[0061] Alternatively, it is possible to use a solid matrix precursor material, add the adsorbent particles to the precursor material, mix it, and then solidify the material, for example by a cross-linking, sintering or drying process, to obtain, for example, a thermoset structure.

[0062] Preferably, such processes involving heating ensure that the residence time of the adsorbent particles in the molten or precursor material is sufficiently short to avoid degradation of the surface and / or porosity properties and / or functionalization of the particles.

[0063] Furthermore, starting from adsorbent particles, it is possible to generate the actual adsorbent structure in a sintering process, for example by bringing the adsorbent particles into a corresponding desired three-dimensional shape (for example in the form of a layer of substantially the desired thickness of the resulting foil), and then heating and / or irradiating and / or chemically treating the corresponding structure in a manner similar to a sintering process to generate a coherent macroscopic adsorbent structure. This is particularly suitable for adsorbents based on organic thermoplastic polymeric materials. However, other materials are also possible, provided that they are provided at their surface with a corresponding binder that allows such a sintering process. Such sintering can be assisted by slight pressure, for example in a lamination process.

[0064] The solid matrix may also be the same or a different solid inorganic or organic non-polymeric or polymeric support material surface functionalized with amino functional groups, which itself has the surface and porosity properties defined above. However, the solid matrix may also be a material which, unlike any of the particles, does not have carbon dioxide capture properties and / or the matrix does not have the surface area and porosity properties defined above. Preferably, the solid matrix in this case is a different material to the sorbent particles, which does not have surface functionalization but is preferably porous and exposed at the surface, with the sorbent particles having surfaces functionalized to act as carbon dioxide capture sites.

[0065] Such composite morphological materials having adsorbent particles embedded in a solid matrix can also be in the form of hollow or solid particles, beads, microspheres, monolithic structures, sheets, hollow or solid fibers, preferably hollow or solid fibers in woven or nonwoven structures, meshes, or extrudates.

[0066] The corresponding powders for embedding in the matrix can be obtained by grinding or milling particulate resin materials that have already been surface-functionalized.

[0067] Such sheets or foils preferably have a thickness in the range of 0.01 to 5 mm or 0.05 to 3 mm, preferably in the range of 0.1 to 1 mm, in order to provide the required mechanical properties for the envisaged DAC applications.

[0068] In order to withstand the conditions of a typical DAC process, it is further preferred that the solid matrix material with embedded adsorbent particles forming the composite structure and / or the solid inorganic or organic non-polymeric or polymeric support material in general do not lose, or at least do not lose significantly, their mechanical properties under typical DAC processing conditions to an extent that would impair their performance in the DAC process.

[0069] Thus, typically, for amorphous thermoplastic polymeric materials of the solid matrix or carrier material in general, the glass transition temperature should be higher than 100°C, and for thermoplastic systems with a melting point, the melting point should be higher than 100°C. On the other hand, especially considering particles that are already functionalized when combined with the matrix, especially surface-functionalized polymeric particles, such as those based on polystyrene, the matrix material should not have an excessively high processing temperature, because otherwise the polymeric particles would also melt in the melt mixing process and / or the surface functionalization of the particles would be destroyed. With this in mind, the matrix material and / or carrier material of the adsorbent in general should preferably have a glass transition temperature of less than 180°C for amorphous thermoplastic polymeric materials. Thus, for amorphous thermoplastic polymeric materials, the glass transition temperature is preferably in the range of 120-160°C, more preferably in the range of 130-150°C. In the case of matrix systems and / or support materials in general (e.g. microcrystalline or partially crystalline polymeric systems) that have a melting point, the melting or softening point should be in the same temperature range and therefore be higher than 100° C. and / or lower than 180° C., preferably in the range of 120-160° C., more preferably in the range of 130-150° C. Glass transition temperatures and melting temperatures in this context should be considered as being measured according to DIN EN ISO 11357 (2012). Amorphous within the meaning of the present invention means that the system has a melting enthalpy determined according to ISO 11357 (2012) of less than or equal to 3 J / g.

[0070] It should be noted and reemphasized that the above surface area and porosity properties should be considered insofar as they are relevant to the carbon dioxide capture process. Thus, for example, if the matrix material is permeable to carbon dioxide, the composite may have a porosity and / or surface structure that is not within the scope of the claims and given above. However, sorbent particles embedded in such a material will certainly have the porosity and / or surface structure defined above, and these properties can be utilized in the carbon dioxide capture process by virtue of the fact that the matrix material is permeable to carbon dioxide and allows access to the capture active particles by diffusion.

[0071] Such composite structures may therefore be produced, for example, by blending the adsorbent particles with a solid matrix material or a precursor thereof, followed by solidification and / or extrusion, whereby the solid matrix material may, for example, be a thermoplastic material or a material that solidifies only during post-mixing processing, such as a crosslinking or drying or sintering process.

[0072] In this case, the surface functionalization for carbon dioxide capture can be carried out either before or after blending to form the corresponding composite. For example, a process is also possible in which non-functionalized particles are mixed with a matrix material to produce a corresponding porous composite structure with the desired porosity properties, and then functionalization with amino functional groups is carried out on the surface of the embedded particles in the solid composite structure. This has the advantage that a matrix material that cannot be functionalized can be combined with functionalizable particles in a composite, which is produced first and which is functionalized only later, and only on the corresponding available surfaces of the particles, with amino functional groups as defined above. The particles embedded in the composite should be considered as adsorbents in the above sense.

[0073] Such solid supports are preferably surface functionalized to form the adsorbent, preferably the surface functionalization provides amine groups available for reversible carbon dioxide capture, which can be achieved by impregnation or by grafting to the surface species of the solid support, or a combination thereof. The surface functionalization is preferably provided with aminomethyl moieties, such as benzylamine moieties, and the solid polymeric support material is preferably obtained by a suspension polymerization process. Emulsion polymerization can be effectively used to establish the porosity in the claimed range by adapting the reactants and reaction conditions, preferably suspension polymerization is carried out in water, with or without surfactants such as dimethyldioctadecaylammonium chloride, preferably in the presence of a pore former, which can be isooctane, toluene, wax or mixtures thereof. However, other methods and reagents are possible. Functionalization can be achieved, for example, by phthalimide addition or chloromethylation. Preferably, the primary amine moieties are in the form of terminal aminomethyl, for example in the form of the benzylamine moieties mentioned above. For carbon dioxide capture, primary amines are, according to the present invention, converted to carbamic acid compounds, which dissociate at high temperature and / or humidity to release carbon dioxide.

[0074] The solid inorganic or organic non-polymeric or polymeric support material can be a polymeric support material in at least one of the following forms: monolith (typically having a sponge-like structure for the throughflow of the gas mixture / ambient air), one or more layers, the form of a sheet, hollow or solid fibers, for example in the form of hollow or solid fibers in a woven or non-woven (layer) structure, but can also be in the form of hollow or solid particles (beads). Preferably, the solid inorganic or organic non-polymeric or polymeric support material is in the form of beads, preferably substantially spherical, with a particle size (D50) in the range of 0.002-4 mm, 0.005-2 mm, or 0.01-1.5 mm, preferably in the range of 0.30-1.25 mm. Particles with a particle size (D50) in the range of 0.002-1.5 mm, 0.005-1.6 mm are also possible.

[0075] When the adsorbent is in the form of beads or powder in the range of 0.002-4 mm, the unit may contain the adsorbent in a layered structure / container having air permeable side walls in the form of a membrane, metal grid or the like, typically having a mesh width large enough to provide a low pressure drop across the corresponding structure, yet small enough to ensure that the particles of the adsorbent are retained within the corresponding container.

[0076] The adsorbent may have a water retention in the range of 3-60% by weight, preferably 3-30% or 5-30% by weight, as determined using a moisture analyzer in which the adsorbent is heated to 110° C. until the detected weight change does not exceed 0.002 g / 15 sec.

[0077] Furthermore, the adsorbent is 750 to 400 kg / m 3 , preferably 450 to 650 kg / m 3 The bulk density (EN ISO 60 (DIN 53468)) may be in the range of 0.01 to 0.05.

[0078] The removal step (d) is preferably carried out by injecting and / or circulating saturated or superheated steam through said unit, while keeping the adsorbent in contact with the steam, to flush and purge both steam and CO2 from the unit, preferably while adjusting the removal and / or steam supply so that the temperature of the adsorber at the end of the preceding step (c) is substantially maintained and / or the pressure of the adsorber at the end of the preceding step (c) is substantially maintained. "Substantially maintaining the pressure of the adsorber at the end of the preceding step" means in practice that the pressure is not allowed to deviate from the pressure at the end of step (c) by more than ±100 mbar, preferably more than ±50 mbar, more preferably more than ±20 mbar. In practice, very brief deviations beyond this range may occur after the transition from step c) to d) due to the process of pressure equalization, depending on the exact realization of the equipment for carrying out the process. They are, however, of short duration, of the order of less than 15% of the duration of step d).

[0079] To carry out the method, preferably a unit containing the adsorbent is used, which unit and the adsorbent are capable of maintaining a temperature of at least 60° C. for desorption of at least the gaseous carbon dioxide, and which unit is openable for the flow-through of the gas mixture / ambient air and for contacting the gas mixture / ambient air with the adsorbent in the adsorption step.

[0080] The unit used may comprise an array of individual adsorber elements, each of which comprises at least one carrier layer and at least one adsorber layer comprising or consisting of at least one adsorbent material providing selective adsorption of CO2 in the presence of moisture or water vapor, the adsorber elements of the array may be arranged substantially parallel to one another and spaced apart from one another such that parallel fluid paths are formed for the throughflow of the gas mixture / ambient air and / or vapor. Substantially parallel in this context means that the angle between the planes of the adsorber elements when viewed over their entire length does not exceed a value of 10°, preferably does not exceed a value of 5°, preferably is less than 2°. Individual adsorber elements in this context means that the adsorber elements are not monolithic structures but can be arranged independently of one another, thereby forming the substantially parallel channels of the array, the layers being connected to one another by corresponding connecting structures, for example by racks into which the layers are inserted or fixed or on which the carrier layer can be pleated repeatedly at desired intervals.

[0081] The unit is preferably evacuable to a vacuum pressure of 400 mbar (abs) or less, step (b) may comprise separating the adsorber having adsorbed carbon dioxide therein from the throughflow while maintaining the adsorber temperature, and then evacuating the unit to a pressure in the range of 20 to 400 mbar (abs), step (c) injecting a saturated or superheated steam stream also induces an increase in the internal pressure of the reactor unit, and step (e) comprises bringing the adsorbent to ambient atmospheric pressure and temperature conditions.

[0082] Preferably, after step (d) and before step (e), the following step is carried out: (d1) stopping the steam injection and, if used, the circulation and evacuating the unit until the pressure value within the unit is in the range of 20-500 mbar (abs), preferably 50-250 mbar (abs), thereby evaporating the water from the adsorbent and drying and cooling the adsorbent.

[0083] Step (e) is preferably carried out exclusively by contacting said ambient air with the adsorbent under ambient atmospheric pressure and temperature conditions to evaporate and remove water within the unit and bring the adsorbent to ambient atmospheric temperature conditions.

[0084] After step (b) and before step (c), the following step may be carried out: (b1) flushing the unit of non-condensable gas with a non-condensable vapour stream whilst substantially maintaining the pressure of step (b), preferably whilst maintaining the pressure of step (b) within a range of ±50 mbar, preferably within a range of ±20 mbar, and / or whilst maintaining the temperature below 75°C or below 70°C or below 60°C, preferably below 50°C.

[0085] In a further embodiment of step b1, the temperature of the adsorber structure is increased from the conditions of step (a) to a range of 80-110°C, preferably 95-105°C.

[0086] In step (b1), the reactor can be purged to remove residual gas mixture / ambient air, preferably by flushing the unit with saturated steam or steam superheated at most 20° C. at a rate of 1 kg / h to 10 kg / h of steam per liter of adsorber structure volume while maintaining the pressure of step (b1). The purpose of removing this part of the ambient air is to improve the purity of the captured CO2.

[0087] In step (c), steam can be injected in the form of steam introduced via a corresponding inlet of said unit, and the steam can be recycled (partially or completely) from the outlet of said unit to said inlet, preferably with reheating of the recycled steam or by recycling of steam from another reactor.

[0088] It should be noted that the heating for the desorption by this process in step (c) is provided solely by this steam injection and no additional external or internal heating, for example by piping with a hot fluid, is provided.

[0089] More preferably in step (c), the adsorbent may be heated to a temperature in the range of 80 to 110°C or 80 to 100°C, preferably to a temperature in the range of 85 to 98°C.

[0090] According to yet another preferred embodiment, in step (c), the pressure in the unit is in the range of 700 to 950 mbar (abs), preferably in the range of 750 to 900 mbar (abs).

[0091] Furthermore, the present invention relates to the use of an adsorbent having a solid inorganic or organic, non-polymeric or polymeric support material, the surface of which is functionalized with amino functional groups, capable of reversibly binding carbon dioxide, preferably with a carbon dioxide concentration of 10 to 25 m, as measured by nitrogen adsorption. 2 / g and a cumulative pore volume in the range of 50 to 350 nm of 0.28 to 1.5 cm 3 / g, in particular for use in direct air capture using temperature, vacuum or temperature / vacuum swing processes.

[0092] This uses a process in which once-through injection of saturated or superheated steam is used to induce an increase in the temperature of the adsorbent to a temperature of 60-110°C to initiate desorption of CO2.

[0093] Preferably, the adsorbent for this use has the characteristics detailed above, such as in terms of pore size, pore volume and / or nitrogen content.

[0094] Finally, the invention relates to a direct air recovery unit comprising at least one reactor unit containing an adsorbent suitable and adapted for the throughflow of a gas mixture, preferably ambient air, wherein: The reactor unit has an inlet for the gas mixture / ambient air being adsorbed and an outlet for the gas mixture / ambient air; the reactor unit can be heated to a temperature of at least 60° C. for desorption of at least said gaseous carbon dioxide, the reactor unit can be opened for the flow-through of the gas mixture / ambient air and for contacting the gas mixture / ambient air with the adsorbent in the adsorption step, preferably the reactor unit can further be evacuated to a vacuum pressure of up to 400 mbar (abs), The adsorbent preferably takes the form of an adsorbent structure comprising an array of individual adsorbent elements, each of which preferably comprises at least one support layer and at least one adsorbent layer comprising or consisting of at least one adsorbent material, said adsorbent comprising a solid inorganic or organic non-polymeric or polymeric support material surface functionalized with amino functional groups capable of reversibly binding carbon dioxide, the support material preferably having a sorption capacity of 10 to 25 m as measured by nitrogen adsorption. 2 / g and a cumulative pore volume in the range of 50 to 350 nm of 0.28 to 1.5 cm 3 / g, said adsorbent providing selective adsorption of CO2 in the presence of moisture or water vapor, and preferably the adsorbent elements of the array are arranged substantially parallel to one another and spaced apart from one another so as to provide parallel fluid pathways for the flow therethrough of the gas mixture / ambient air and / or vapor; The unit comprises at least one device for separating carbon dioxide from water, preferably a cooler; Preferably, the device for separating carbon dioxide from water, preferably the cooler, is provided at the gas outlet side with at least one, preferably both, of a carbon dioxide concentration sensor and a gas flow sensor for controlling the desorption process. Regarding direct air recovery units.

[0095] The present application also relates to methods for the preparation of surface-functionalized solid support materials suitable and adapted for these processes, including in particular surface impregnation or grafting for surface functionalization.

[0096] Further embodiments of the invention are defined in the dependent claims. [Brief description of the drawings]

[0097] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will now be described with reference to the drawings, which are intended to illustrate, but not to limit, the present preferred embodiments of the present invention. [Figure 1] FIG. 1 is a schematic diagram of a direct air recovery unit. [Diagram 2] FIG. 1 shows pore size distribution measured by Hg porosimetry. [Diagram 3] FIG. 1 shows pore volume as a function of pore size measured by Hg intrusion. [Figure 4] FIG. 1 shows the equilibrium adsorption capacity of the adsorbent at 30° C. with an air flow rate of 2 L / min and 60% RH after air purge thermal swing desorption at 94° C. [Diagram 5] FIG. 1 shows the cycle adsorption capacity of the adsorber at 15° C. and RH with a gas flow of 11 L / min containing 450 ppm CO2 after vapor desorption. [Figure 6] FIG. 1 shows the cycle adsorption capacity of the adsorbent at 30° C. with an air flow rate of 2 L / min at each RH after air purge thermal swing desorption at 94° C. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0098] The proposed adsorbent can be manufactured by the following process: For a general reaction scheme for introducing an aminomethyl functional group into the PS-DVB backbone, reference is made to the above scheme of this disclosure.

[0099] The morphology of PS-DVB beads can be controlled by the amount of DVB in the monomer phase, and the amount and type of porogen. Generally speaking, if the type and amount of porogen are constant, the more the amount of DVB, the larger the specific surface area. On the other hand, the more the amount of porogen, the larger the pore size and the smaller the specific surface area. In order to obtain a specific morphology (e.g., surface area, pore volume, and pore size), it is necessary to adjust the optimal conditions of the amount of DVB, the amount of porogen, and the type of porogen.

[0100] The porosities in the following examples IER_A to IER_D were set using these guidelines.

[0101] Synthetic procedure IER_A: In a 1 L reactor, 1% gelatin (by weight) and 2% sodium chloride (by weight) are dissolved in 350 mL of water at 45 °C for 1 h. In a separate flask, 1 g of benzoyl peroxide is dissolved in 55.4 g of styrene, 8.2 g of divinylbenzene (content 80%) and C 11 ~C 13 The mixture is dissolved in a mixture of 52.6 g of isoparaffin. The resulting mixture is then added to a reactor. The reaction mixture is then stirred and heated to 70°C and the temperature is maintained for 2 hours, after which the temperature is increased to 80°C and maintained for 3 hours, and then increased to 90°C over 6 hours. The reaction mixture is cooled to room temperature and the beads are filtered off using a funnel glass filter and vacuum suction. The beads are washed with toluene and dried in a rotavapor.

[0102] These polystyrene-divinylbenzene beads are functionalized by a chloromethylation reaction. 5 g of the beads thus obtained are added to a three-necked flask containing 50 mL of chloromethyl methyl ether. The mixture is stirred for 1 hour, 2 g of zinc chloride is added, heated to 40° C. and maintained for 24 hours. The beads are then filtered off and washed with 25% HCl and water to obtain the chloromethylated beads. To obtain the benzylamine units, these chloromethylated beads are aminated as follows: The chloromethylated beads are added to a three-necked flask together with 27 g of methylal and the mixture is stirred for 1 hour. To this mixture are added 16 g of hexamethylenetetramine and 13 g of water and maintained under gentle reflux for 24 hours. The beads are filtered off and washed with water. To obtain the primary amines, a hydrolysis step and subsequent treatment with a base are necessary. The beads are placed in a three-neck flask containing 140 mL of a solution of hydrochloric acid (30%) and ethanol (95%) (volume ratio 1:3) and the reaction mixture is heated to 80° C. and kept at this temperature for 20 hours. The beads are then filtered off and washed with water. In order to protonate the amines at this stage and liberate the bases, the beads are treated with 50 mL of a 2 M NaOH solution and stirred at 80° C. for 1 hour. The aminated beads are filtered off and washed with demineralized water until a neutral pH is reached.

[0103] Synthesis procedure IER_B: In a 1 L reactor, 1% gelatin (by weight) and 2% sodium chloride (by weight) are dissolved in 340 mL of water at 45 °C for 1 h. In a separate flask, 1 g of benzoyl peroxide is dissolved in 59.7 g of styrene, 3.9 g of divinylbenzene (content 80%) and C 11 ~C 13The mixture is dissolved in a mixture of 65.3 g of isoparaffin. The resulting mixture is then added to a reactor. The reaction mixture is then stirred and heated to 70°C and the temperature is maintained for 2 hours, after which the temperature is increased to 80°C and maintained for 3 hours, and then increased to 90°C over 6 hours. The reaction mixture is cooled to room temperature and the beads are filtered off using a funnel glass filter and vacuum suction. The beads are washed with toluene and dried in a rotavapor.

[0104] These polystyrene-divinylbenzene beads are functionalized by a chloromethylation reaction. 5 g of the beads thus obtained are added to a three-necked flask containing 50 mL of chloromethyl methyl ether. The mixture is stirred for 1 hour, 2 g of zinc chloride is added, heated to 40° C. and maintained for 24 hours. The beads are then filtered off and washed with 25% HCl and water to obtain the chloromethylated beads. To obtain the benzylamine units, these chloromethylated beads are aminated as follows: The chloromethylated beads are added to a three-necked flask together with 27 g of methylal and the mixture is stirred for 1 hour. To this mixture are added 16 g of hexamethylenetetramine and 13 g of water and maintained under gentle reflux for 24 hours. The beads are filtered off and washed with water. To obtain the primary amines, a hydrolysis step and subsequent treatment with a base are necessary. The beads are placed in a three-neck flask containing 140 mL of a solution of hydrochloric acid (30%) and ethanol (95%) (volume ratio 1:3) and the reaction mixture is heated to 80° C. and kept at this temperature for 20 hours. The beads are then filtered off and washed with water. In order to protonate the amines at this stage and liberate the bases, the beads are treated with 50 mL of a 2 M NaOH solution and stirred at 80° C. for 1 hour. The aminated beads are filtered off and washed with demineralized water until a neutral pH is reached.

[0105] Synthesis procedure IER_C: In a 1 L reactor, 1% gelatin (by weight) and 2% sodium chloride (by weight) are dissolved in 340 mL of water at 45 °C for 1 h. In a separate flask, 1 g of benzoyl peroxide is dissolved in 58.8 g of styrene, 4.9 g of divinylbenzene (content 80%) and C 11 ~C 13 The mixture is dissolved in a mixture of 63.2 g of isoparaffin. The resulting mixture is then added to a reactor. The reaction mixture is then stirred and heated to 70°C and the temperature is maintained for 2 hours, after which the temperature is increased to 80°C and maintained for 3 hours, and then increased to 90°C over 6 hours. The reaction mixture is cooled to room temperature and the beads are filtered off using a funnel glass filter and vacuum suction. The beads are washed with toluene and dried in a rotavapor.

[0106] These polystyrene-divinylbenzene beads are functionalized by a chloromethylation reaction. 5 g of the beads thus obtained are added to a three-necked flask containing 50 mL of chloromethyl methyl ether. The mixture is stirred for 1 hour, 2 g of zinc chloride is added, heated to 40° C. and maintained for 24 hours. The beads are then filtered off and washed with 25% HCl and water to obtain the chloromethylated beads. To obtain the benzylamine units, these chloromethylated beads are aminated as follows: The chloromethylated beads are added to a three-necked flask together with 27 g of methylal and the mixture is stirred for 1 hour. To this mixture are added 16 g of hexamethylenetetramine and 13 g of water and maintained under gentle reflux for 24 hours. The beads are filtered off and washed with water. To obtain the primary amines, a hydrolysis step and subsequent treatment with a base are necessary. The beads are placed in a three-neck flask containing 140 mL of a solution of hydrochloric acid (30%) and ethanol (95%) (volume ratio 1:3) and the reaction mixture is heated to 80° C. and kept at this temperature for 20 hours. The beads are then filtered off and washed with water. In order to protonate the amines at this stage and liberate the bases, the beads are treated with 50 mL of a 2 M NaOH solution and stirred at 80° C. for 1 hour. The aminated beads are filtered off and washed with demineralized water until a neutral pH is reached.

[0107] Synthesis procedure IER_D: In a 1 L reactor, 1% gelatin (by weight) and 2% sodium chloride (by weight) are dissolved in 340 mL of water at 45 °C for 1 h. In a separate flask, 1 g of benzoyl peroxide is dissolved in 57.8 g of styrene, 5.86 g of divinylbenzene (content 80%) and C 11 ~C 13 The mixture is dissolved in a mixture with 63.84 g of isoparaffin. The resulting mixture is then added to a reactor. The reaction mixture is then stirred and heated to 70°C and the temperature is maintained for 2 hours, then the temperature is increased to 80°C and maintained for 3 hours, then increased to 90°C over 6 hours. The reaction mixture is cooled to room temperature and the beads are filtered off using a funnel glass filter and vacuum suction. The beads are washed with toluene and dried in a rotavapor.

[0108] These polystyrene-divinylbenzene beads are functionalized by a chloromethylation reaction. 5 g of the beads thus obtained are added to a three-necked flask containing 50 mL of chloromethyl methyl ether. The mixture is stirred for 1 hour, 2 g of zinc chloride is added, heated to 40° C. and maintained for 24 hours. The beads are then filtered off and washed with 25% HCl and water to obtain the chloromethylated beads. To obtain the benzylamine units, these chloromethylated beads are aminated as follows: The chloromethylated beads are added to a three-necked flask together with 27 g of methylal and the mixture is stirred for 1 hour. To this mixture are added 16 g of hexamethylenetetramine and 13 g of water and maintained under gentle reflux for 24 hours. The beads are filtered off and washed with water. To obtain the primary amines, a hydrolysis step and subsequent treatment with a base are necessary. The beads are placed in a three-neck flask containing 140 mL of a solution of hydrochloric acid (30%) and ethanol (95%) (volume ratio 1:3) and the reaction mixture is heated to 80° C. and kept at this temperature for 20 hours. The beads are then filtered off and washed with water. In order to protonate the amines at this stage and liberate the bases, the beads are treated with 50 mL of a 2 M NaOH solution and stirred at 80° C. for 1 hour. The aminated beads are filtered off and washed with demineralized water until a neutral pH is reached.

[0109] The beads according to the examples were tested in an experimental setup in which the beads were contained in a packed bed reactor or in an air permeable bed. The experimental setup is shown diagrammatically in Figure 1. There is an ambient air inlet structure 1 and an actual reactor unit 8, which comprises a container or wall 7 in which a layer of adsorbent 3 is arranged. There is an inlet structure 4 for desorption, if for example steam is used for desorption, and there is a reactor outlet 5 for removal. Furthermore there is a vacuum unit 6 for reactor evacuation.

[0110] For adsorption measurements using dry gas to desorb the adsorber, 6 g of dry sample was packed into a cylinder with an internal diameter of 40 mm and height of 40 mm and placed in a CO2 adsorption / desorption apparatus where it was exposed to 2.0 NL / min airflow at 30°C and 20, 40, 60 and 80% relative humidity containing 450 ppmv CO2 for 600 min. Prior to adsorption, the adsorbent layer was desorbed by heating the adsorber to 94°C with an airflow of 2.0 NL / min. The amount of CO2 adsorbed on the adsorber was determined by integration of the signal of an infrared sensor measuring the CO2 content of the airflow exiting the cylinder.

[0111] For the adsorption measurements using steam to desorb the adsorbent, 15 g of dried sample was loaded into a rectangular reactor with an internal diameter of 60 mm and height of 60 mm and placed in a CO2 adsorption / desorption apparatus where it was exposed to an 11 NL / min airflow at 15°C with 450 ppmv CO2 and relative humidity of 20, 40, 60 and 80% for 600 min. Prior to adsorption, the adsorbent bed was brought to 200 mbarabs, after which 3 mL / min of steam was injected into the reactor to bring the temperature of the adsorbent bed to approximately 95°C, and the adsorbent was held at this temperature for 6 min. The reactor was then closed and the pressure was set to 200 mbarabs, and once the target pressure was reached the reactor was repressurized to atmospheric pressure. The amount of CO2 adsorbed in the adsorbent was determined by integration of the signal of an infrared sensor measuring the CO2 content of the air stream exiting the reactor.

[0112] Examples: In this example section, four samples were analyzed and compared: one with a BET specific surface area >25 m 2 / g, hereafter referred to as high surface area polymer (IER_A), and the other has a BET specific surface area of ​​<25 m 2 / g, hereafter referred to as low surface area polymer (IER_B).

[0113] Furthermore, two samples with the same basic structure but with optimal surface area and porosity distribution, namely IER_C and IER_D, are analyzed.

[0114] Pore ​​size, pore volume and specific surface area of ​​the adsorbent: How to measure specific surface area: Nitrogen adsorption measurements were performed at 77 K using a Quantachrome ASiQ. The mass of the samples used ranged from 0.2 to 1.0 g. As the samples contain significant amounts of water, it is important to use a treatment that does not alter their inherent porosity and pore structure. Therefore, prior to degassing, the samples were treated using an elution series method. This method involves the removal of water and its replacement by organic solvents with low boiling points in the following order: methanol, acetone and n-heptane. 2 g of sample was placed in a fritted chromatography column and 20 cm of each solvent was eluted in order of increasing polarity. 3 The samples were then spread on a Petri dish and placed in a vacuum oven at 40 °C for 24 h. The samples were then degassed under vacuum at 70 °C for 12 h before measurements.

[0115] BET (Brunauer, Emmett und Teller) surface area analysis was used adapting the method of ISO 9277.

[0116] The results of the specific surface area measurements are shown in Table 1 below:

[0117] [Table 1]

[0118] Mercury porosimetry measurements: Mercury porosimetry measurements were performed to analyze the pore size and pore volume that cannot be obtained by N2 adsorption measurements. The following parameters were used to perform the mercury porosimetry measurements: ·Mercury surface tension: 0.48N / m ·Mercury contact angle: 150° Maximum pressure: 400MPa ·Acceleration: 6~19MPa / min.

[0119] Prior to Hg porosimetry, the samples were degassed under vacuum at 70° C. for 12 h.

[0120] The results of the Hg porosimetry analysis are shown in Figures 2 and 3 and summarized in Table 2 below:

[0121] [Table 2]

[0122] Elemental analysis: Elemental analysis of the materials was performed using a LECO CHN-900 combustion furnace. Prior to the measurement, the samples were ground in a mortar and treated at 90 °C for 2 h under N2 flow (2 L / min).

[0123] The analytical results of the materials are summarized in Tables 3 to 6.

[0124] [Table 3]

[0125] [Table 4]

[0126] [Table 5]

[0127] [Table 6]

[0128] Adsorption measurement: 6 g of the dried sample was packed into a cylinder with an inner diameter of 40 mm and a height of 40 mm and placed in a CO2 adsorption / desorption apparatus, where it was exposed for 600 min to an airflow of 2.0 NL / min at 30 °C containing 450 ppmv CO2 and 60% relative humidity corresponding to a temperature of 30 °C. Prior to adsorption, desorption of the adsorbent layer was carried out by heating the adsorbent to 94 °C under an airflow of 2.0 NL / min. The amount of CO2 adsorbed in the adsorbent was determined by integration of the signal of an infrared sensor measuring the CO2 content of the airflow leaving the reactor. The CO2 equilibrium capacity at 30 °C and 60% RH is shown in Figure 4. It can be seen that the IER_B adsorbent exhibits the highest cumulative CO2 capacity (1.7 mmol / g) while the other adsorbents exhibit equilibrium capacities of 1.1 to 1.3 mmol / g. The difference in equilibrium capacity is due to the different amine loadings in the samples, as evident from the different nitrogen contents of the adsorbents (see Tables 3 to 6). As the inlet gas RH is varied between 20 and 80%, all adsorbents show a linear increase in cycle CO2 capacity, as shown in Figure 6. This behavior is consistent with what is known about the RH dependence of amine-based adsorbents.

[0129] The results of the CO2 adsorption measurements are summarized in Table 7.

[0130] [Table 7]

[0131] Cycle adsorption / desorption measurements: The cycle adsorption / desorption capacity was measured by continuous operation at ambient air relative humidity ranging from 20 to 80%. The temperature of the adsorbent was increased by performing the desorption process using a warm fluid. In this specific example, saturated water vapor was used. The adsorbent bed was first adsorbed for 200 minutes using ambient air. Once adsorption was completed, the pressure of the system was reduced to 200 mbarabs. As soon as this pressure was reached, saturated steam was fed to the adsorbent bed until a temperature of approximately 95°C was reached. The adsorbent was then brought to 200 mbarabs until a temperature of 60°C was reached. This cycle was repeated multiple times, and the results are shown in Figure 5.

[0132] Figure 6 shows the results of a similar experiment, but in this case the desorption process was carried out by heating the adsorber to 94°C with an air flow of 2.0 NL / min. This cycle was repeated multiple times.

[0133] By applying steam to the desorption of the adsorbent and using air in the RH range of 20-80%, the desorption capacity of IER_A shows a constant decrease in the cycle adsorption / desorption capacity, while IER_B shows a constant increase in the cycle adsorption / desorption capacity until it becomes constant at an RH of around 80%. Only IER_C and IER_D show a substantially constant behavior in the measured RH range.

[0134] The adsorbent is generally a solid inorganic non-polymeric support material that is surface functionalized with amino functional groups and is capable of reversibly binding carbon dioxide, and has a surface area of ​​10 to 25 m. 2 / g and a cumulative pore volume in the range of 50 to 350 nm of 0.3 to 1.5 cm 3 The pore volume distribution may be in the range of 1 / g.

[0135] Possible materials include silica (SiO2), alumina (Al2O3), silica-alumina (SiO2-Al2O3), titania (TiO2), magnesia (MgO), clays, and mixtures of the above.

[0136] For organic polymeric materials, preferably for these organic or non-organic polymeric support materials, the total pore volume measured by mercury intrusion porosimetry is between 0.3 and 0 and 7 cm 3 / g and / or the pore size distribution, measured by mercury porosimetry, is such that 90%, preferably 95% of the pore volume is in the range of 50-300 nm.

[0137] For silica microspheres with such porosity characteristics, they can be produced by the following scheme: Monodispersed colloidal SiO2 was prepared by a seeded growth method. Commercially available Ludox AS-40 silica sol particle seeds were added to a mixture of ammonia (2 mol / L), deionized water (6 mol / L), and ethanol to form a suspension. To this mixture, tetraethyl orthosilicate (TEOS, 2.2 mol / L) was added under stirring at a controlled rate while keeping the reaction mixture at 25 °C. Monodispersed SiO2 particles were obtained by seeded growth. After obtaining monodispersed SiO2 microspheres with a diameter of 500 nm, they were calcined at 700 °C for 2 h, followed by hydrothermal treatment at 220 °C for 5 h to restore the surface silanol groups lost during calcination.

[0138] The obtained silica material was 10 2 / g specific surface area, 95 nm median pore size, 0.3 cm determined by Hg intrusion porosimetry 3 / g total pore volume, and an average particle size of 500 μm.

[0139] In the case of alumina microspheres with such porosity characteristics, these are catalyst supports available, for example, from Saint Gobain Nor Pro. α-alumina without surface hydroxyl groups is available for modification by impregnation.

[0140] In the case of titania microspheres with such porosity characteristics, these are catalyst supports commercially available from Saint Gobain Nor Pro. Rutile titania, which does not have surface hydroxyl groups, is available for modification by impregnation. [Explanation of symbols]

[0141] 1. Ambient air, ambient air inlet structure 2. Ambient air discharge behind the adsorption unit in adsorption once-through mode 3. Adsorbents 4. Steam inlet structure for steam and desorption 5. Reactor outlet for removal 6 Vacuum unit / separator 7. Wall 8. Reactor Unit

Claims

1. A method for separating gaseous carbon dioxide from a gas mixture comprising said gaseous carbon dioxide and a further gas other than said gaseous carbon dioxide by cyclic adsorption / desorption using an adsorbent (3) in a unit (8) for adsorbing said gaseous carbon dioxide, wherein said gas mixture may be at least one of ambient air (1), flue gas and biogas; The method comprises repeating at least the following steps (a) to (e) sequentially and in this order: (a) contacting the gas mixture with the adsorbent (3) to adsorb at least the gaseous carbon dioxide onto the adsorbent (3) by flowing it through the unit (8) under ambient atmospheric pressure and temperature conditions if the gas mixture is ambient air, or under the temperature and pressure conditions of the feed gas mixture in other cases; (b) separating the adsorbent (3) in the unit (8) that has adsorbed carbon dioxide from the through-flow while maintaining the temperature of the adsorbent; (c) injecting a saturated or superheated steam stream (4) through the unit (8), thereby inducing an increase in the temperature of the adsorbent (3) to a temperature of 60-110°C, thereby producing CO ２ initiating desorption of (d) at least removing the desorbed gaseous carbon dioxide from the unit (8) and separating the gaseous carbon dioxide from the vapor by condensation downstream of the unit (8); (e) subjecting said adsorbent (3) to ambient temperature conditions if the gas mixture is ambient air, or to the temperature and pressure conditions of said feed gas mixture otherwise; Including, The adsorbent (3) is a solid inorganic or organic non-polymer or polymer carrier material whose surface is functionalized with an amino functional group and can reversibly bind carbon dioxide, and has a BET specific surface area in the range of 10 to 25 m ２ / g, and has a pore volume distribution such that the cumulative pore volume in the range of 50 to 350 nm is in the range of 0.28 to 1.5 cm ３ / g, method.

2. The adsorbent (3) has a viscosity of 10 to 20 m as measured by a nitrogen adsorption method. ２ / g range, or 12 to 20 m ２ 10. The method of claim 1, wherein the sintered body has a BET specific surface area in the range of 1 / g.

3. the adsorbent (3) has a pore size distribution, as measured by mercury porosimetry, such that 90% or 95% of the pore volume is in the range of 50 to 400 nm, or in the range of 80 to 350 nm; and / or the adsorbent (3) has a pore volume distribution measured by mercury porosimetry such that the maximum pore volume is in the pore diameter range of 80 to 150 nm or in the pore diameter range of 100 to 150 nm; and / or the adsorbent (3) has a surface area of ​​0.3 to 1 cm as measured by mercury intrusion porosimetry. ３ / g range, or 0.35 to 0.8 cm ３ / g range, or 0.4 to 0.7 cm ３ 3. The method of claim 1 or 2, wherein the total pore volume is in the range of 1 / g.

4. 3. The method of claim 1 or 2, wherein the adsorbent (3) has a nitrogen content in the range of 5 to 50 wt.%, or in the range of 8 to 15 wt.%, or in the range of 10 to 12 wt.%, respectively, based on the dry adsorbent.

5. 3. The method of claim 1, wherein the gas mixture is ambient air.

6. 3. The method of claim 1 or 2, wherein the solid inorganic or organic non-polymeric or polymeric support material of the adsorbent is an organic or inorganic polymeric support, or an inorganic non-polymeric support.

7. the solid inorganic or organic, non-polymeric or polymeric support material of the adsorbent surface-functionalized with amino functional groups is in the form of at least one of a monolith, a layer or sheet, a hollow or solid fiber, a hollow or solid particle, or an extrudate, and the hollow or solid fiber may be a woven or non-woven structure; 3. The method according to claim 1 or 2, wherein the adsorbent (3) of the solid inorganic or organic, non-polymeric or polymeric support material, surface functionalized with or amino functional groups, is embedded in or attached to a porous / air-permeable or non-porous matrix or support structure.

8. The adsorbent (3) has a cumulative pore volume in the range of 50 to 350 nm of 0.3 to 1.2 cm ３ / g range, or 0.35 to 0.7 cm ３ 3. The method according to claim 1, wherein the pore volume distribution is in the range of 1 / g.

9. The adsorbent (3) has a water retention rate in the range of 3 to 60% by weight, or in the range of 3 to 30% by weight, or in the range of 5 to 30% by weight, and / or a water retention capacity of 750 to 400 kg / m ３ or 450 to 650 kg / m ３ and having a bulk density (EN ISO 60 (DIN 53468)) in the range of and / or the method according to claim 1 or 2, wherein the method is carried out under conditions in which the gas mixture or the ambient air passing through the adsorbent in step (a) has a relative humidity that varies in the range of 20 to 80% RH for at least 5%, 10%, or 50% of the cycle in a day, month, and / or year.

10. Step (d) is carried out by injecting and / or circulating saturated or superheated steam into the unit while keeping the adsorbent (3) in contact with the steam, thereby separating the steam and CO ２ and (c) performing both flushing and purging from the unit while adjusting the withdrawal and / or steam supply so as to substantially maintain the temperature of the adsorber at the end of the preceding step (c) and / or to substantially maintain the pressure of the adsorber at the end of the preceding step (c).

11. 3. The method according to claim 1, wherein a unit containing the adsorbent (3) is used, the unit and the adsorbent being capable of maintaining a temperature of at least 60° C. for the desorption of at least the gaseous carbon dioxide, the unit being openable for the flow of the gas mixture through and for contacting the gas mixture with the adsorbent in the adsorption step, the gas mixture being optionally the ambient air.

12. 3. The method according to claim 1 or 2, wherein the unit is capable of being evacuated to a vacuum pressure of 400 mbar (abs) or less, step (b) comprises separating the adsorbent having adsorbed carbon dioxide in the unit from the throughflow while maintaining the temperature of the adsorbent, and then evacuating the unit to a pressure in the range of 20 to 400 mbar (abs), and in step (c), the injection of a saturated or superheated steam stream also induces an increase in the internal pressure of the reactor unit, and step (e) comprises bringing the adsorbent to ambient atmospheric pressure and temperature conditions.

13. 3. The method of claim 1 or 2, wherein step (e) is carried out exclusively by contacting the ambient air with the adsorbent under ambient atmospheric pressure and temperature conditions to evaporate and remove water within the unit and bring the adsorbent to ambient atmospheric temperature conditions.

14. Use of an adsorbent (3) for separating gaseous carbon dioxide from a gas mixture, comprising: The gas mixture may be at least one of ambient air (1), flue gas and biogas; Inducing a temperature increase in the adsorbent (3) to a temperature of 60-110°C using a temperature, vacuum, or temperature / vacuum swing process or utilizing the injection of a saturated or superheated steam stream (4) through a once-through process to remove CO ２ It may be a direct air capture using a process of initiating desorption of The adsorbent (3) comprises a solid inorganic or organic, non-polymeric or polymeric support material, surface functionalized with amino functional groups, capable of reversibly binding carbon dioxide, and has a reversibility of 10 to 25 m as measured by nitrogen adsorption. ２ / g and a cumulative pore volume in the range of 50 to 350 nm of 0.28 to 1.5 cm ３ / g or 0.3 to 1.5 cm ３ / g, The adsorbent (3) is used as is or attached to or embedded in a porous and / or non-porous matrix and / or support structure.

15. A unit for separating gaseous carbon dioxide from a gas mixture, the gas mixture being at least one of ambient air (1), flue gas and biogas, the unit being optionally a direct air recovery unit; The unit comprises at least one reactor unit (8) containing an adsorbent material (3) suitable and adapted for the flow of the gas mixture (1), said reactor unit comprising an inlet for said gas mixture, which may be the ambient air (1), and an outlet for said gas mixture, which may be the ambient air during adsorption (2); the reactor unit is heatable to a temperature of at least 60°C for desorption of at least the gaseous carbon dioxide, the reactor unit is openable for flowing the gas mixture, which may be the ambient atmosphere, through and contacting the gas mixture with the adsorbent in an adsorption step, and the reactor unit is evacuable to a vacuum pressure of not more than 400 mbar (abs); The adsorbent (3) takes the form of at least a portion of an adsorbent structure comprising an array of individual adsorbent elements, each adsorbent element comprising at least one monolith or support layer or sheet and at least one adsorbent layer or adsorbent monolith comprising or consisting of at least one adsorbent (3) or packed bed, the adsorbent comprising a solid inorganic or organic, non-polymeric or polymeric support material surface functionalized with amino functional groups capable of reversibly binding carbon dioxide, the support material having a surface functionalized with amino functional groups capable of reversibly binding carbon dioxide, the surface functionalized with amino functional groups being at least 10 to 25 m as measured by nitrogen adsorption. ２ / g and a cumulative pore volume in the range of 50 to 350 nm of 0.28 to 1.5 cm ３ / g range, or 0.3 to 1.5 cm ３ / g, and the adsorbent elements of the array are arranged substantially parallel to and spaced apart from one another to form parallel fluid pathways for the flow therethrough of the gas mixture, which may be ambient air and / or vapor; the unit comprises at least one device, which may be a chiller, for separating carbon dioxide from water; A unit, wherein at a gas outlet side of the device, which may be the cooler, for separating carbon dioxide from water, at least one or both of a carbon dioxide concentration sensor and a gas flow sensor may be provided for controlling the desorption process.

16. The method according to claim 1 or 2, wherein the adsorbent (3) has a pore volume distribution measured by mercury intrusion porosimetry, in which the maximum pore volume lies in a pore diameter range of 80 to 150 nm, or in a pore diameter range of 100 to 150 nm, and 90% or 95% of the total pore volume of the distribution lies in the range of -50 nm to +150 nm, or in the range of -40 nm to +100 nm, of the diameter of the maximum value of the pore volume distribution.

17. The organic polymeric support is a polystyrene-based material, which may be a styrene-divinylbenzene copolymer, and is formed with an adsorbent surface-functionalized with a primary amine, which may be a methylamine or benzylamine moiety; or the solid polymeric support material is obtained by a suspension polymerization process and / or an emulsion polymerization process; Or the method of claim 6, wherein the inorganic non-polymeric support is selected from the group consisting of silica (SiO 2 ), alumina (Al 2 O 3 ), titania (TiO 2 ), magnesia (MgO), clay, and mixed forms thereof including silica-alumina (SiO 2 -Al 2 O 3 ), or mixtures thereof.

18. The adsorbent of claim 17, wherein the solid polymeric carrier material of the adsorbent is in the form of substantially spherical beads having a particle size (D50) in the range of 0.002 to 4 mm, or in the range of 0.01 to 1.5 mm, or in the range of 0.30 to 1.25 mm; 3. A method according to claim 1 or 2, wherein the adsorbent (3) takes the form of a layer of adsorbent material, which may be in the form of a layer of particulate and / or fibrous adsorbent material, which layer is attached to at least one further layer of porous / air-permeable support material, which may be a porous / air-permeable polymeric support material, or embedded between two layers of porous / air-permeable support material layers to form a laminate, which itself can be further structured to form a panel or module.

19. The method of claim 11, wherein the unit comprises an array of individual adsorbent elements, each adsorbent element comprising at least one carrier layer and at least one adsorbent layer comprising or consisting of at least one adsorbent material, the adsorbent material providing selective adsorption of CO2 in the presence of moisture or water vapor, the adsorbent elements of the array being arranged substantially parallel to and spaced apart from one another so as to form parallel fluid passages for the flow therethrough of ambient air and / or a gas mixture comprising vapor.

20. After step (d) and before step (e), (d1) stopping the steam injection and, if used, the circulation, and evacuating the unit until the pressure in the unit is in the range of 20 to 500 mbar (abs), or in the range of 50 to 250 mbar (abs), thereby evaporating water from the adsorber and drying and cooling the adsorber; 13. The method of claim 12, wherein:

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