System and method for treating a material to be treated, involving the removal of carbon dioxide

Abstract

The invention relates to a system for treating a material to be treated, the system comprising: a treatment region in which the treatment of the material to be treated can be carried out; and an enclosure for isolating the treatment region from a surrounding region surrounding the enclosure, in which system impairment of the material to be treated due to undesired secondary reactions with CO2 present in the treatment region is largely avoided, characterised in that the system comprises at least one CO2 reduction device for at least partially removing carbon dioxide (CO2) from a gas mixture containing CO2.

Description

[0001] Plant and method for treating a material with removal of carbon dioxide

[0002] The present invention relates to a system for treating a material to be treated, wherein the system comprises a treatment area in which the treatment of the material to be treated can be carried out, and a casing for separating the treatment area from an ambient area surrounding the casing.

[0003] Such systems are used, for example, to carry out at least one treatment step in the production of a coated material web, for example a coating process and / or a drying process.

[0004] The coated material web can, for example, be an electrode material for a lithium-ion battery. In this case, the material to be treated can, in particular, comprise a metallic material web coated with an electrochemically active material, for example, a nickel-cobalt-manganese (NCM) material.

[0005] Several studies have shown that atmospheric H2O and CO2 in the treatment area can have a detrimental effect on the active NCM material through parasitic side reactions. Therefore, these atmospheric parameters should be monitored and preferably regulated during treatment of the material.

[0006] A problem caused by parasitic side reactions with the ambient air can be the formation of residual lithium compounds (RLCs) with strong alkalinity on the surface of the coating material.

[0007] It is assumed that a reduction reaction of Ni 3+ to Ni 2+ can lead to the formation of oxides on the surface of NCM particles in the coating. The Ni may react 2+ with H2O and CO2 from the atmosphere and with Li + forming the residual lithium compounds (RLCs) LiOH and U2CO3 according to the following reaction equations [1] and [2] :

[0008] LiNiO2+ x H2O Lii xHxNiO2+ x LiOH [1]

[0009] 2 Li NiO2+ x H2O + x CO2 2 Lii-xH x NiO2+ x U2CO3 [2]

[0010] It is known that the amount of residual lithium compounds (RLCs) increases with increasing Ni content and with increasing humidity.

[0011] It is assumed that the U2CO3 produced according to the above equation [2] is responsible for the swelling of a lithium-ion battery in which the electrode prepared in this way is used, especially during storage of the battery at high temperatures in the charged state, which increases the risk of fire.

[0012] A reaction of LiOH with polyvinylidene fluoride (PVDF)-based binders could lead to gelation of the cathode slurry during the electrode coating process.

[0013] It is also assumed that as a result of the residual lithium compounds (RLCs), a delithiation layer forms near the surface region in which the Li content is reduced.

[0014] Apart from that, residual lithium compounds (RLCs) can also be formed by an excess of LiOH during material synthesis to compensate for a loss of U2O. Further results indicate the formation of transition metal hydroxides and carbonates at the surfaces of the original NCM material in the presence of moisture and CO2 according to the following reaction equations [3] and [4]:

[0015] MO + H2O -> M(OH)2[3]

[0016] MO + CO2 -> MCO3[4]

[0017] In this context, it is assumed that the main carbonate surface contamination on Ni-rich NCM811 is nickel carbonate, which could also contribute to gassing behavior of the finished lithium-ion battery.

[0018] In addition, an amount of more than 150 pmol / g of NCM-l-hydroxides and carbonates in a liquid NCM(622) cathode suspension leads to flocculation and gelation and thus to a significant loss of capacity.

[0019] For a detailed discussion of the problems raised above, please refer to the article by Carina Amata Heck, Max-Wolfram von Horstig, Fabienne Hüttner, Julian Kristoffer Mayer, Wolfgang Haselrieder and Arno Kwade: "Review - Knowledge-Based Process Design for High Quality Production of NCM811 Cathodes" in Journal of The Electrochemical Society, 2020, Volume 167, from page 160521, as well as to the article by Johannes Sicklinger et al.: "Ambient Storage Derived Surface Contamination of NCM811 and NCM111 : Performance Implications and Mitigations Strategies" in Journal of The Electrochemical Society, 2019, Volume 166, pages A2322 to A2335.

[0020] There is therefore evidence that the coating treatment steps and the conveying of the metallic material webs into a dryer are critical. In most cases, the dryer is a floating dryer, in which the material web is continuously blown with warm air from above and below, keeping it suspended.

[0021] It can be assumed that, at a non-negligible CO2 content of the air in the dryer and a sufficient reaction temperature, a non-negligible proportion of metal oxides of the coating will be converted into carbonates, thus significantly reducing the performance of the batteries in which the electrodes produced in this way are used.

[0022] Although many flotation dryers are operated in recirculation mode for efficiency reasons, the negative pressure in the dryer means that fresh air with the CO2 content prevailing in the dryer's environment is constantly sucked into the dryer's interior.

[0023] The present invention is based on the object of creating a plant for treating a material to be treated of the type mentioned above, in which impairment of the material to be treated by undesirable side reactions with CO2 present in the treatment area is largely avoided.

[0024] This object is achieved according to the invention in a plant for treating a material to be treated having the features of the preamble of claim 1 in that the plant comprises at least one CO2 reduction device for at least partially removing carbon dioxide (CO2) from a CO2-containing gas mixture.

[0025] The present invention is based on the concept of minimizing the CO2 content in the treatment area of ​​the system, thus enabling the most CO2-free treatment of the material to be treated. The treatment of the material to be treated within the system's shell can, for example, comprise a treatment process such as a coating process, a calendering process, and / or a drying process.

[0026] By means of the CO2 reduction device, the CO2 content in the gas mixture emitted by the CO2 reduction device can be reduced preferably to less than half, in particular to less than a quarter, particularly preferably to less than a tenth, of the CO2 content in the gas mixture supplied to the CO2 reduction device.

[0027] During operation of the plant according to the invention for treating a material to be treated, the proportion of CO2 in the atmosphere in the treatment area of ​​the plant is preferably less than 200 ppm, in particular less than 100 ppm, particularly preferably less than 40 ppm.

[0028] In a particular embodiment of the invention, it is provided that the system comprises a fresh air supply, by means of which at least one of the at least one CC reduction devices can be supplied with fresh air from outside the treatment area.

[0029] Alternatively or additionally, it can be provided that the system comprises at least one lock through which the material to be treated can be fed to the treatment area (input lock) and / or removed from the treatment area (output lock), wherein the lock preferably comprises an air curtain generating device for generating an air curtain in the area of ​​the lock and a CO2-reduced gas mixture can be fed to the air curtain generating device by means of at least one of the at least one CO2 reducing devices.

[0030] If the system includes at least one lock through which the material to be treated can be fed into the treatment area (entrance lock) and / or removed from the treatment area (exit lock), such a lock can also include an inert gas curtain generation device for generating an inert gas curtain in the area of ​​the lock, so that less CO2 is fed from the lock in question to the treatment area of ​​the system. This preferably also requires less CO2 to be removed from the atmosphere in the treatment area of ​​the system.

[0031] Alternatively or additionally, it can be provided that the system comprises a recirculation circuit, wherein at least one CCh reduction device is arranged in the recirculation circuit.

[0032] In such a recirculation circuit, at least one air cleaning device and / or at least one air heating device can also be arranged.

[0033] The air purification device can be arranged upstream of the at least one CCh reduction device or downstream of the at least one CO2 reduction device in the recirculation circuit.

[0034] The air heating device can be arranged upstream of the at least one CCh reducing device or downstream of the at least one CCh reducing device in the recirculating air circuit.

[0035] The air cleaning device can be arranged upstream of the air heating device or downstream of the air heating device in the recirculation circuit.

[0036] Furthermore, it can be provided that by means of at least one of the at least one CCh reducing device, in addition to the CO2 content, the moisture content of the gas mixture passing through the CCh reducing device can also be reduced.

[0037] Alternatively or in addition to a reduction of the moisture content of the gas mixture passing through the CCh reducing device, it can also be provided that the system for treating a material to be treated comprises, in addition to the at least one CCh reducing device, a dehumidification device operating independently thereof, by means of which the moisture in the treatment area of ​​the system can be reduced.

[0038] The function of reducing the moisture in the gas mixture passing through the CC reduction device can be realized in particular when a metal-organic framework (MOF) is used as a sorbent for absorbing CO2 in the CC reduction device.

[0039] The system according to the invention offers the advantage that by reducing the CC content in the atmosphere present in the treatment area of ​​the system, an important disturbance variable which impairs the coating quality of the material to be treated, for example an electrode material for a battery cell, and thus the long-term stability of the battery cells in which the electrode material is used, can be reduced or preferably completely eliminated.

[0040] If only the lock air supplied to one or more locks of the shell of the plant is reduced in terms of its CC content by means of at least one CCh reducing device, the CCh reducing device can be designed compactly.

[0041] The system according to the invention for treating a material to be treated is particularly suitable for carrying out a treatment process in which a material to be treated is coated.

[0042] The coated material to be treated can be a component of a battery cell, for example an electrode material, in particular an electrode material of a lithium-ion battery cell. However, the system according to the invention for treating a material to be treated is also suitable for carrying out other CCh-sensitive coating processes.

[0043] It is particularly advantageous if, with the system according to the invention for treating a material to be treated, the proportion of carbonate ions formed by reaction of the coating material with CO2 from the atmosphere is less than 2.5% by weight, preferably less than 1.5% by weight, in particular less than 1.0% by weight, particularly preferably less than 0.6% by weight, of the total coating material present in the finished treated material.

[0044] In a preferred embodiment of the invention, it is provided that the system for treating the material to be treated comprises a suspension device for keeping the material to be treated suspended.

[0045] The material to be treated can in particular be designed as a material web.

[0046] For example, it can be provided that the material to be treated is kept in suspension by blowing on it with a gas or a gas mixture, in particular air.

[0047] In principle, any conceivable treatment of the item being treated can be carried out in the treatment area.

[0048] In a preferred embodiment of the invention, the treatment area includes a drying area in which the material to be treated can be dried, preferably after a coating process. Alternatively or additionally, the system according to the invention may include a coating device arranged within the casing.

[0049] Alternatively or additionally, it can be provided that the system according to the invention comprises at least one film-forming device arranged within the casing.

[0050] Such a film-forming device may in particular comprise a pair of film-forming rollers, wherein a powdered starting material can be fed to a gap between the film-forming rollers.

[0051] Alternatively or additionally, it can be provided that the system according to the invention comprises at least one pair of calendering rollers and / or at least one pair of laminating rollers.

[0052] The plant according to the invention for treating a material to be treated can be designed in particular as a plant for producing a coated electrode material.

[0053] The electrode material can preferably be coated on at least one side, particularly preferably on both sides, with an electrochemically active coating material.

[0054] The coated electrode material produced is preferably a component for an electric battery, preferably an electric secondary battery, for example a lithium-ion secondary battery.

[0055] In a preferred embodiment of the invention, at least one of the at least one CO2 reduction devices is designed such that moisture contained in the gas mixture can also be at least partially removed from the gas mixture. Each of the at least one CO2 reduction devices of the system for treating a material can be designed like any device for the direct capture of CO2 from air ("Direct Air Capture"; DAC).

[0056] In contrast to a DAC system, where the goal is to capture CO2 as a material component and which is therefore designed for the highest possible efficiency, i.e. the lowest possible energy consumption for capturing a certain amount of CO2 from the air, the goal of a CC reduction device in the system for treating a material is to obtain process air that is as CO2-free as possible, which is why this CC reduction device is designed for the highest possible effectiveness, i.e. the highest possible CC purity of the air passed through the CC reduction device.

[0057] In a particular embodiment of the invention, it is provided that at least one of the at least one CCh reducing devices comprises a liquid sorbent for absorbing CO2.

[0058] For easy regeneration of such a liquid sorbent, the system may include an electrodialysis device to which sorbent loaded with CO2 can be fed.

[0059] For example, it can be provided that the liquid sorbent is an aqueous solution of an alkali hydroxide, from which an aqueous solution of an alkali carbonate and / or an alkali hydrogen carbonate is formed by absorption of CO2 from the gas mixture, which solution can be fed to an electrodialysis device in which an aqueous solution of an alkali hydroxide is again formed from the aqueous solution of the alkali carbonate and / or the alkali hydrogen carbonate.

[0060] The alkali metal used can be potassium, for example. In a particular embodiment of the invention, at least one of the at least one CCh reduction devices comprises a membrane contactor, wherein a liquid sorbent for absorbing CO2 can be supplied to a retentate side of the membrane contactor.

[0061] Compared to an air scrubber, in which the CO2-containing gas mixture comes into contact with a liquid, in particular with an aqueous solution, a membrane contactor offers the advantage that no significant amount of liquid, in particular water, is released into the gas mixture.

[0062] The membrane contactor comprises a membrane that is permeable to CO2 molecules but essentially impermeable to the liquid sorbent.

[0063] The membrane can, for example, comprise hollow fibers whose interior is permeated by the CO2-containing gas mixture, while the fibers are in contact with the liquid sorbent on their exterior. The CO2 then passes from the permeate side (interior of the hollow fibers) through the material of the hollow fibers to the retentate side (outside of the hollow fibers).

[0064] Alternatively, the membrane of the membrane contactor can also comprise hollow fibers, around which the CO2-containing gas mixture flows on their outside, while the liquid sorbent is arranged in the cavities inside the hollow fibers. In this case, the CO2 passes through the material of the hollow fibers from the permeate side (outside of the hollow fibers) to the liquid sorbent on the retentate side (inside of the hollow fibers). Such a membrane contactor, in which the liquid sorbent is arranged in the interior of the hollow fibers, is described, for example, in P.S. Kumar's dissertation: "Development and Design of Membrane Gas Absorption Processes," 2002, University of Twente, published by Twente University Press, particularly on page 4.

[0065] The use of a membrane contactor as a gas mixture contactor in a CC reduction device offers one or more of the following advantages over the use of an air scrubber:

[0066] The mass transfer coefficients and the mass transfer interface can be varied independently.

[0067] There are no operational limitations such as flooding, loading, wetting, or similar issues that occur with conventional gas-liquid contactors. Furthermore, there are no operational difficulties such as foaming, which can occur during dispersive contact of a gas with a viscous liquid.

[0068] The density difference between the contacting phases, which is necessary for phase separation after contact in conventional gas-liquid contactors, is irrelevant in membrane contactors. Consequently, the orientation of the membrane contactor relative to the direction of gravity is not an important criterion in the design of the membrane contactor.

[0069] The interfacial area per unit volume of the membrane contactor can be an order of magnitude larger than that of conventional gas-liquid contactors. This is particularly possible using hollow-fiber membrane modules, in which a large number of small-diameter hollow fibers (on the order of a few hundred micrometers) are packed into a very small volume. Commercially available membrane modules can achieve specific interfacial areas of up to 3,000 m². 1In hollow fibers with such a small diameter, the liquid flow is laminar. Consequently, the mass transfer coefficient is lower than in conventional gas-liquid contactors. Nevertheless, the product of the mass transfer coefficient and the interface area, which is the contactor-specific design parameter that largely influences the absorption rate in a contactor, is several times higher than in a conventional gas-liquid contactor.

[0070] The scaling behavior of a membrane contactor is essentially linear due to its modular nature.

[0071] Membrane contactors constructed from membrane modules can have a low density relative to their absorption capacity.

[0072] Alternatively or in addition to the use of a liquid sorbent for absorbing CO2, it can be provided that at least one of the at least one CC reducing devices comprises a solid-bound sorbent for absorbing CO2.

[0073] Such a solid-bound sorbent can, for example, be a polyethyleneimine (PEI) arranged on a solid support material.

[0074] Alternatively or in addition, a metal-organic framework (MOF) can also be used as a solid-bound sorbent.

[0075] The present invention further relates to a method for treating a material to be treated in a treatment area arranged within a casing for separating the treatment area from a surrounding area surrounding the casing. The present invention is further based on the object of creating such a method for treating a material to be treated of the aforementioned type, in which impairment of the material to be treated due to undesirable side reactions with CO2 present in the treatment area is largely avoided.

[0076] This object is achieved according to the invention in a method for treating a material to be treated in a treatment area which is arranged within a casing for separating the treatment area from an ambient area surrounding the casing, in that the method comprises the following: at least partial removal of carbon dioxide (CO2) from a gas mixture containing CO2.

[0077] Preferably, the method according to the invention additionally comprises the following:

[0078] Supplying the CO2-reduced gas mixture to the treatment area and / or to an air curtain generating device by means of which an air curtain is generated in the area of ​​a lock, wherein a material to be treated is supplied to the treatment area and / or removed from the treatment area through the lock.

[0079] The method according to the invention is based on the concept of minimizing the CO2 content in the treatment area in order to enable the material to be treated to be as CO2-free as possible.

[0080] Preferred embodiments of the method according to the invention have already been explained above in connection with particular embodiments of the system according to the invention for treating a material to be treated. The system according to the invention for treating a material to be treated is particularly suitable for carrying out the method according to the invention for treating a material to be treated.

[0081] The method according to the invention for treating a material to be treated is preferably carried out by means of a system according to the invention for treating a material to be treated.

[0082] The treatment of the material to be treated within the casing may, for example, comprise a treatment process such as a coating process, a calendering process and / or a drying process.

[0083] By means of the CC reduction device, the CO2 content in the gas mixture emitted by the CO2 reduction device is preferably reduced to less than half, in particular to less than a quarter, particularly preferably to less than a tenth, of the CO2 content in the gas mixture supplied to the CC reduction device.

[0084] In the method according to the invention for treating a material to be treated, the proportion of CO2 in the atmosphere in the treatment area is preferably less than 200 ppm, in particular less than 100 ppm, particularly preferably less than 40 ppm.

[0085] In a special embodiment of the method, it is provided that fresh air is supplied to at least one CC reduction device from outside the treatment area.

[0086] Alternatively or additionally, it can be provided that at least one lock is provided through which the material to be treated can be fed to the treatment area (input lock) and / or removed from the treatment area (output lock), wherein the lock preferably comprises an air curtain generating device for generating an air curtain in the area of ​​the lock and a gas mixture reduced by means of at least one CC reducing device is supplied to the air curtain generating device.

[0087] If at least one lock is provided through which the material to be treated can be fed into the treatment area (entrance lock) and / or removed from the treatment area (exit lock), such a lock can also include an inert gas curtain generating device for generating an inert gas curtain in the area of ​​the lock, so that less CO2 is fed into the treatment area from the lock in question. This preferably also requires less CO2 to be removed from the atmosphere in the treatment area.

[0088] Alternatively or additionally, it may be provided that a recirculating air circuit is provided, wherein at least one CC reducing device is arranged in the recirculating air circuit.

[0089] In such a recirculation circuit, at least one air cleaning device and / or at least one air heating device can also be arranged.

[0090] The air purification device can be arranged upstream of the at least one CO2 reduction device or downstream of the at least one CO2 reduction device in the recirculation circuit.

[0091] The air heating device can be arranged upstream of the at least one CO2 reduction device or downstream of the at least one CO2 reduction device in the recirculation circuit.

[0092] The air purification device can be arranged upstream of the air heating device or downstream of the air heating device in the recirculation circuit. Furthermore, it can be provided that, by means of at least one CO2 reduction device, not only the CO2 content but also the moisture content of the gas mixture passing through the CO2 reduction device is reduced.

[0093] Alternatively or in addition to a reduction of the moisture content of the gas mixture passing through the CCh reducing device, it can also be provided that in addition to the at least one CCh reducing device, a dehumidifying device operating independently thereof is provided, by means of which the moisture in the treatment area is reduced.

[0094] The function of reducing the moisture in the gas mixture passing through the CCh reducing device can be realized in particular when a metal-organic framework (MOF) is used as a sorbent for absorbing CO2 in the CCh reducing device.

[0095] The method according to the invention offers the advantage that by reducing the CCh content in the atmosphere present in the treatment area, an important disturbance variable which impairs the coating quality of the material to be treated, for example an electrode material for a battery cell, and thus the long-term stability of the battery cells in which the electrode material is used, can be reduced or preferably completely eliminated.

[0096] If only the air supplied to one or more locks of the casing is reduced in terms of its CCh content by means of at least one CCh reduction device, the CCh reduction device can be designed compactly. The method according to the invention for treating a material to be treated is preferably a treatment method in which the material to be treated is coated.

[0097] The coated material to be treated can be a component of a battery cell, for example an electrode material, in particular an electrode material of a lithium-ion battery cell.

[0098] However, the method according to the invention for treating a material to be treated can also be another CC-sensitive coating method.

[0099] It is particularly advantageous if, in the method according to the invention for treating a material to be treated, the proportion of carbonate ions formed by reaction of the coating material with CO2 from the atmosphere is less than 2.5% by weight, preferably less than 1.5% by weight, in particular less than 1.0% by weight, particularly preferably less than 0.6% by weight, of the total coating material present in the finished treated material.

[0100] In a preferred embodiment of the method, a suspension device is provided for keeping a material to be treated in suspension.

[0101] The material to be treated can in particular be designed as a material web.

[0102] For example, it can be provided that the material to be treated is kept in suspension by blowing on it with a gas or a gas mixture, in particular air.

[0103] In principle, any conceivable treatment of the material to be treated can be carried out in the treatment area. In a preferred embodiment of the method, the treatment area includes a drying area in which the material to be treated is dried, preferably after a coating process.

[0104] Alternatively or additionally, it can be provided that a coating device arranged within the casing is used in the method according to the invention.

[0105] Alternatively or additionally, it can be provided that in the method according to the invention at least one film forming device arranged within the casing is used.

[0106] Such a film forming apparatus may in particular comprise a pair of film forming rollers, wherein a powdered starting material is fed to a gap between the film forming rollers.

[0107] Alternatively or additionally, it can be provided that at least one pair of calendering rollers and / or at least one pair of laminating rollers is used in the method according to the invention.

[0108] The method according to the invention for treating a material to be treated can be used in particular for producing a coated electrode material.

[0109] The electrode material is preferably coated on at least one side, particularly preferably on both sides, with an electrochemically active coating material.

[0110] The coated electrode material produced is preferably a component for an electric battery, preferably an electric secondary battery, for example a lithium-ion secondary battery. In a preferred embodiment of the method, at least one CC reduction device is designed such that moisture contained in the gas mixture is at least partially removed from the gas mixture.

[0111] Each of the at least one CC reduction device can be designed like any device for the direct capture of CO2 from air ("Direct Air Capture"; DAC).

[0112] In a particular embodiment of the process, it is provided that a liquid sorbent is used to absorb CO2 in at least one CC reduction device.

[0113] For easy regeneration of such a liquid sorbent, provision can be made for sorbent loaded with CO2 to be fed into an electrodialysis device.

[0114] For example, it can be provided that the liquid sorbent is an aqueous solution of an alkali hydroxide, from which an aqueous solution of an alkali carbonate and / or an alkali hydrogen carbonate is formed by absorption of CO2 from the gas mixture, which solution is fed to an electrodialysis device in which an aqueous solution of an alkali hydroxide is again formed from the aqueous solution of the alkali carbonate and / or the alkali hydrogen carbonate.

[0115] The alkali metal used can be potassium, for example.

[0116] In a particular embodiment of the process, at least one CO2 reduction device comprises a membrane contactor, wherein a liquid sorbent for absorbing CO2 is supplied to a retentate side of the membrane contactor. Compared to an air scrubber, in which the CO2-containing gas mixture comes into contact with a liquid, in particular an aqueous solution, a membrane contactor offers the advantage that no significant amount of liquid, in particular water, is released into the gas mixture.

[0117] The membrane contactor comprises a membrane which is permeable to CO2 molecules but essentially impermeable to the liquid sorbent.

[0118] The membrane can, for example, comprise hollow fibers whose interior is permeated by the CO2-containing gas mixture, while the fibers are in contact with the liquid sorbent on their exterior. The CO2 then passes from the permeate side (interior of the hollow fibers) through the material of the hollow fibers to the retentate side (outside of the hollow fibers).

[0119] Alternatively, the membrane of the membrane contactor can also comprise hollow fibers, around which the CO2-containing gas mixture flows on their outside, while the liquid sorbent is arranged in the cavities inside the hollow fibers. In this case, the CO2 passes through the material of the hollow fibers from the permeate side (outside of the hollow fibers) to the liquid sorbent on the retentate side (inside the hollow fibers).

[0120] Such a membrane contactor, in which the liquid sorbent is arranged in the interior of the hollow fibers, is described, for example, in the dissertation by PS Kumar: "Development and Design of Membrane Gas Absorption Processes," 2002, University of Twente, published by Twente University Press, particularly on page 4. Alternatively or in addition to the use of a liquid sorbent for absorbing CO2, it may be provided that a solid-bound sorbent is used to absorb CO2 in at least one CO2 reduction device.

[0121] Such a solid-bound sorbent can, for example, be a polyethyleneimine (PEI) arranged on a solid support material.

[0122] Alternatively or in addition, a metal-organic framework (MOF) can also be used as a solid-bound sorbent.

[0123] In each of the CO2-reducing devices of the plant according to the invention and / or in each CO2-reducing device used in carrying out the method according to the invention, a process or at least a partial step of a process is carried out by means of which CO2 can be at least partially, preferably substantially completely, removed from a gas mixture containing CO2 in order to largely or preferably completely avoid the above-described harmful effects of CO2 on the material being treated in the treatment area, in particular due to the formation of carbonates and hydrogen carbonates.

[0124] For at least partial removal of carbon dioxide from a gas mixture, in principle, all processes developed for the direct capture of CO2 from air ("Direct Air Capture"; DAC) can be used. A very good overview of all currently available and currently under development DAC processes is provided in the article by Maria Erans, Eloy S. Sanz-Perez, Dawid P. Hanak, Zeynep Clulow, David M. Reiner, and Greg A. Mutch: "Direct air capture: process technology, techno-economic and socio-political challenges" in Energy Environ. Sci., 2022, Vol. 15, pages 1360 to 1405. In this DAC process, CO2 is absorbed or adsorbed on a sorbent.

[0125] There are DAC processes in which the sorbent is not regenerated, but is only exposed to CO2 once and then has to be replaced.

[0126] This must be distinguished from DAC processes, in which the sorbent, after being coated with CO2, is regenerated by desorbing the CO2 from the sorbent.

[0127] An example of a DAC process without sorbent regeneration is the chemisorption of CO2 on a fixed bed of so-called "soda lime." Such a DAC process can be used, for example, to reduce the CO2 content in the interior of a submarine.

[0128] In this case, the gas mixture loaded with CO2 is preferably passed through at least one disposable exchangeable container in which the soda lime is arranged, which at least partially absorbs the CO2 from the gas mixture passed through.

[0129] In particular, soda lime can be a mixture of calcium hydroxide (Ca(OH)2) and sodium hydroxide (NaOH) or a mixture of potassium hydroxide (KOH) and barium hydroxide (Ba(OH)2).

[0130] When using a mixture of calcium hydroxide and sodium hydroxide, the CO2 from the gas mixture in the disposable exchange container reacts with water to form carbonic acid, which then reacts further with sodium hydroxide to form sodium carbonate and water. The sodium carbonate reacts with calcium hydroxide to form calcium carbonate and sodium hydroxide, so that the CO2 is finally bound in the form of calcium carbonate (CaCO3). Such a soda lime can be mixed with a pH indicator that changes color at low pH values, for example, from white to violet, thus indicating that the CO2-absorbing soda lime has been used up.

[0131] Further details on soda lime and its use for absorbing CO2 from a gas mixture can be found in the Wikipedia article on the keyword "Soda Lime" as of December 4, 2023, to which reference is made in this regard.

[0132] Processes for the absorption or adsorption of CO2 on a sorbent with subsequent regeneration of the sorbent can be divided into the following:

[0133] Type A processes, which use a liquid sorbent, are classified as low-temperature desorption processes (at a desorption temperature of 100°C or less) and high-temperature desorption processes (at a desorption temperature of more than 100°C or less up to 900°C).

[0134] Type B processes, which use a solid-bound sorbent. These processes can be divided into temperature swing desorption processes (at a desorption temperature of no more than 100°C) and humidity swing desorption processes (at a desorption temperature of preferably no more than 100°C).

[0135] The gas mixture in which the CCh content is to be reduced is preferably passed through a gas mixture contactor.

[0136] The gas mixture contactor may include an air scrubber. When using a Type A DAC process, the CO2 is removed from the incoming gas mixture by absorption in a liquid sorbent.

[0137] The liquid sorbent can, for example, be an aqueous solution of monoethanolamine (MEA).

[0138] As an alternative to an aqueous solution of MEA, another basic reagent can be used, such as an aqueous solution of polyethyleneimine (PEI).

[0139] From the above-mentioned liquid sorbents such as MEA or PEI, the CO2 can be desorbed from the sorbent in question in the low-temperature range, i.e. at a desorption temperature of up to 100°C.

[0140] Alternatively or additionally, an aqueous solution of a water-soluble base (e.g., an alkali hydroxide) can be used as the sorbent, onto which the CO2 is absorbed in the form of a carbonate and / or a hydrogen carbonate in an aqueous solution in an absorption loop. The carbonate and / or the hydrogen carbonate reacts in a desorption loop with a precipitation reagent, such as calcium hydroxide, so that calcium carbonate, for example, is released as a precipitate. The calcium carbonate is regenerated in the high-temperature desorption region, i.e., at a desorption temperature of more than 100°C, preferably in a calciner, whereby gaseous CO2 is released and CaO remains.

[0141] The CaO can be slaked with liquid water in a lime slaker to form the precipitating agent, particularly calcium hydroxide, which is then brought back into contact with the aqueous solution of carbonate and / or bicarbonate from the gas mixture contactor to precipitate calcium carbonate. In this case, the gas mixture contactor can be designed as a simple scrubber.

[0142] The aqueous solution of carbonate and / or hydrogen carbonate discharged from the gas mixture contactor can be transported to a location remote from the plant for treating a material to be treated in order to carry out the precipitation reaction.

[0143] Instead of high-temperature desorption at elevated temperatures of more than 100°C, for example, in a calciner, regeneration can also be carried out using an electrodialysis cell. In this case, only the provision of electrical energy, preferably at a potential difference that corresponds at least to the dissociation potential of water, is required to prepare for the desorption of CO2, and no precipitation reaction is required.

[0144] An example of a DAC process using a solid sorbent and low-temperature desorption is a high-molecular-weight polyethyleneimine (PEI) coated and fixed onto a solid support material, which acts as a "CO2 sponge" that absorbs CO2 from the gas mixture passing through it. Such a polyethyleneimine exhibits high chemical stability.

[0145] After all coordination sites of the polyethyleneimine (PEI) have been filled with CO2, the solid adsorption bed containing the PEI is separated from the supplied gas mixture containing CO2 and preferably subjected to a vacuum. By adding heat energy and / or increasing the temperature, the CO2 detaches from the coordination sites of the PEI. The released CO2 can be released into the environment or compressed for further use. Instead of polyethyleneimine (PEI), other sorbents, such as metal-organic frameworks (MOFs), can also be used. However, desorption of CO2 from such MOFs requires large amounts of heat at a high desorption temperature level (in the range of approximately 120°C to approximately 150°C).

[0146] Further features and advantages of the present invention are the subject of the following description and the drawings of exemplary embodiments.

[0147] The drawings show:

[0148] Fig. 1 is a schematic representation of a system for treating a material to be treated, wherein the system comprises a treatment area in which the treatment of the material to be treated can be carried out, and a shell for separating the treatment area from an ambient area surrounding the shell, wherein the system further comprises a CO2 reduction device for at least partially removing carbon dioxide (CO2) from a CO2-containing gas mixture, wherein fresh air can be supplied to the CO2 reduction device from outside the treatment area by means of a fresh air supply, and wherein the system comprises a lock at an inlet area of ​​the shell and at an outlet area of ​​the shell, through which the material to be treated can be supplied to the treatment space within the shell or discharged from the treatment space,wherein each of the locks comprises an air curtain generating device for generating an air curtain in the region of the respective lock, and each of the air curtain generating devices can be supplied with a CO2-reduced gas mixture by means of the CO2 reduction device; Fig. 2 is a schematic representation of a second embodiment of a system for treating a material to be treated, wherein the system comprises a recirculating air circuit, and an air cleaning device, an air heating device, and / or a CO2 reduction device are arranged in the recirculating air circuit;

[0149] Fig. 3 is a schematic representation of a third embodiment of a system for treating a material to be treated, wherein the system is designed as an encapsulated system for producing a laminate from a film and two coating films, each of which is laminated to one side of the film, wherein the system comprises a lock through which the non-laminated film can be fed to a treatment area within a casing of the system, and a lock through which the film laminated on both sides can be removed from the treatment area within the casing, wherein each of the locks comprises an air curtain generating device for generating an air curtain in the region of the respective lock, and each of the air curtain generating devices can be supplied with a gas mixture reduced by means of a CC reducing device,and wherein in the interior of the casing there are provided two film-forming devices for forming a film each from a powdered starting material, calendering rollers for calendering a film each and laminating rollers for laminating one or more films to the film to be coated;,

[0150] Fig. 4 is a schematic diagram illustrating the basic structure of a CC reduction device for at least partially removing carbon dioxide from a CO2-containing gas mixture by means of a liquid sorbent (e.g., an aqueous solution of potassium hydroxide (KOH)) for absorbing CO2. The reaction of the sorbent with CO2 produces an aqueous solution of potassium carbonate, which is brought into contact with solid calcium hydroxide (Ca(OH)2) in a reactor to regenerate the aqueous potassium hydroxide solution, thereby producing calcium carbonate (CaCCh), which is converted into calcium oxide (CaO) in a calciner with the elimination of CO2. This calcium oxide is converted into calcium hydroxide (Ca(OH)2) in a so-called "slaker" (lime slaking device) with the addition of water. This calcium hydroxide is then fed to the reactor to precipitate calcium carbonate (CaCO3) from the aqueous potassium carbonate solution formed in the gas mixture contactor.so that the aqueous potassium hydroxide (KOH) solution remaining after precipitation can be fed back to the gas mixture contactor;,

[0151] Fig. 5 is a schematic representation of an alternative embodiment of a CO2 reduction device in which an aqueous alkali hydroxide solution formed in a gas mixture contactor is regenerated in an electrodialysis device containing bipolar membranes, whereby an acidic solution is formed which is discharged from the electrodialysis device and fed to a gas separator in which gaseous CO2 is separated from the acidic solution, wherein the CO2-reduced acidic solution is then fed back to the electrodialysis device;

[0152] Fig. 6 is a schematic representation of an alternative embodiment of a CO2 reduction device, in which the gas mixture contactor is designed as a membrane contactor and which otherwise corresponds to the embodiment of a CO2 reduction device shown in Fig. 5; and

[0153] Fig. 7 is a schematic representation of a further alternative embodiment of a CCh reduction device, in which a CO2-containing gas mixture is passed through an adsorption device during an adsorption phase of the CCh reduction device, in which CO2 is adsorbed from the gas mixture passed through, and in a regeneration phase of the CC reduction device the adsorption device is regenerated by supplying heat and reducing the pressure, wherein gaseous CO2 and water escape from the adsorption device.

[0154] Identical or functionally equivalent elements are designated by the same reference numerals in all figures.

[0155] A system for treating a material to be treated 105, shown schematically in Fig. 1 and designated as a whole by 100, comprises a treatment area in which a treatment of a material to be treated 105 can be carried out, and a casing 102 for separating the treatment area from an ambient area 103 surrounding the casing 102.

[0156] The material 105 to be treated can be formed, for example, as a film or material web 104.

[0157] The untreated material web 104 can be stored, for example in roll form, in an unwinding device 106 and delivered from this.

[0158] The material web 104 delivered by the unwinding device 106 passes through an entrance lock 108 in an entrance area of ​​the sleeve 102 into an interior of the sleeve 102, which comprises the treatment area of ​​the system 100.

[0159] The material web 104' treated in the treatment area of ​​the system 100 exits the interior of the sleeve 102 through an exit lock 110 in an exit area of ​​the sleeve 102 and is taken up by a winding device 110 and held in the winding device 112, for example, in roll form. To condition the air in the treatment area within the sleeve 102, the system 100 includes a recirculation circuit 114.

[0160] The recirculating air circuit 114 comprises a recirculating air discharge line 116, via which recirculating air can be discharged from the interior of the casing 102 and fed to an air cleaning device 118.

[0161] From an outlet of the air cleaning device 118, the circulating air can be fed to an air heating device 122 via a circulating air line 120.

[0162] From the circulating air heating device 122, the circulating air can be supplied to the interior of the casing 102 via a circulating air supply line 124, whereby the circulating air circuit 114 is closed.

[0163] In the exemplary embodiment illustrated in the drawing, the air cleaning device 118 is arranged upstream of the air heating device 122; however, in principle, the air heating device 122 can also be arranged upstream of the air cleaning device 118.

[0164] The recirculation circuit 114 further preferably comprises a recirculation fan, which is not shown in Fig. 1, but is preferably arranged in the recirculation discharge line 116, in the recirculation line 120 or in the recirculation supply line 124.

[0165] For the amount of fresh air supplied to the interior of the shell 102, an equivalent amount of exhaust air must be supplied to a post-treatment in a post-treatment device 129.

[0166] For this purpose, the system 100 comprises an exhaust air line 125, which can, for example, branch off from a point in the recirculation circuit 114 and lead to the aftertreatment device 129. The exhaust air line 125 can, for example, branch off from the recirculation circuit 114 downstream of the air cleaning device 118 and / or upstream of the air heating device 122.

[0167] Furthermore, the system 100 comprises a CO2 (carbon dioxide) reduction device 126, to which ambient air can be supplied via an ambient air supply 128 from the ambient area 103 surrounding the casing 102.

[0168] The CC reduction device 126 is designed to effect at least partial removal of carbon dioxide (CO2) from a CO2-containing gas mixture, in this case the ambient air.

[0169] The possible structure and possible mode of operation of such a CO2 reduction device 126 are described in more detail below.

[0170] A gas mixture reduced in CO2 content by means of the CC reducing device 126 can be fed via a first feed line 128 to an air curtain generating device (not shown) of the inlet lock 108 of the casing 102 and via a second feed line 130 to an air curtain generating device (not shown) of the outlet lock 110 of the casing 102.

[0171] The air curtain generating devices of the entrance lock 108 and the exit lock 110, respectively, supplied with a CO2-reduced gas mixture, each generate an air curtain in the area of ​​the entrance lock 108 and the exit lock 110, respectively, through which the material web 104 to be treated passes upon entering the interior of the casing 102, and the treated material web 104' passes upon exiting the interior of the casing 102. The air curtain generated in each case causes an overpressure at the entrance lock 108 and the exit lock 110, respectively, which seals off the interior of the casing 102 from the surrounding area 103.

[0172] From the air curtain of the entrance lock 108 and from the air curtain of the exit lock 110, a portion of the CC-reduced gas mixture used to generate the air curtain enters the interior of the shell 102, thereby reducing the CO2 content of the air in the interior of the shell 102.

[0173] The treatment of the material to be treated 105 carried out in the interior of the casing 102 can, for example, comprise drying of the material to be treated 105.

[0174] The material to be treated 105 can in particular be a material web 104 coated on one or both sides.

[0175] The uncoated material web 104 can be formed as a foil, for example as a metal foil.

[0176] The coating of the material web 104 with a coating material can be carried out before the material web 104 enters the casing 102 of the system 100 by means of one or more coating devices 132a, 132b.

[0177] In this case, a first coating device 132a can be used to coat a first side of the material web 104, while a second coating device 132b can be used to coat a second side of the material web 104 opposite the first side. As shown in the drawing, the coating devices 132a and 132b can be arranged offset from one another along a direction of movement 134 of the material web 104 or can be arranged directly opposite one another.

[0178] The treatment area of ​​the system 100 arranged in the interior of the casing 102 is in this case designed as a dryer.

[0179] In particular, this dryer can be designed as a floating dryer in which the material to be treated 105 in the form of the coated material web 104 is kept suspended and dried by blowing warm air from both sides of the material web 104.

[0180] By reducing the CO2 content of the air in the treatment area of ​​the system 100 serving as a dryer, undesirable changes in the material 105 being treated due to contact with carbon dioxide, in particular due to reaction with carbon dioxide, are reduced.

[0181] If, for example, the material to be treated 105 is a metal foil that is coated with one or more metal oxides before entering the casing 102 of the system 100, there is a risk that, at the temperature prevailing in the interior of the casing 102, which is higher than the temperature in the ambient area 103 of the system 100, a reaction between the CO2 present in the interior of the casing 102 and the respective metal oxide(s) will occur, converting the metal oxide(s) into carbonates. These carbonates can impair the performance of the material to be treated 105 in the treatment area of ​​the system 100, for example, if the material to be treated 105 is an electrode for use in an electrochemical cell, such as a battery cell.By reducing the CO2 content of the air in the interior of the shell 102, which is achieved by supplying CO2-reduced gas mixture to the air curtain generating devices of the entrance lock 108 and the exit lock 110, such impairment of the material to be treated 105 in the treatment area of ​​the system 100 due to the CO2 content of the air present in the treatment area is reduced or, if the CO2 content in the CO2-reduced gas mixture is largely reduced to zero, is avoided altogether.

[0182] In the most favorable case, the CO2-reducing device 126 reduces the CO2 content of the CO2-reduced gas mixture supplied to the inlet lock 108 and the outlet lock 110 to such an extent that a substantially CO2-free treatment operation is possible in the treatment area of ​​the plant 100.

[0183] A second embodiment of a system 100 for treating a material to be treated 105, shown schematically in Fig. 2, differs from the first embodiment shown in Fig. 1 in that a CC reduction device 126 is arranged in the recirculating air circuit 114 of the system 100.

[0184] In the embodiment of this second embodiment shown in Fig. 2, the CO2 reduction device 126 is arranged in the recirculating air supply line 124, via which the recirculating air guided in the recirculating air circuit 114 is fed back into the interior of the casing 102.

[0185] In principle, however, the CC reduction device 126 can be arranged at any desired location in the recirculating air circuit 114, for example in the recirculating air discharge line 116, via which the recirculating air is discharged from the interior of the casing 102, or in the recirculating air line 120, via which recirculating air from the air cleaning device 118 is supplied to the air heating device 122. As already mentioned above in connection with the first embodiment of the system 100 shown in Fig. 1, the order of the air cleaning device 118 and the air heating device 122 in the recirculating air circuit 114 can also be changed, so that the air heating device 122 is arranged upstream of the air cleaning device 118.

[0186] However, in the second embodiment of a system 100 for treating a material 105 to be treated, shown in Fig. 2, the gas mixture reduced in CO2 by means of the CC reduction device 126 in the recirculating air circuit 114 cannot in many cases be used to generate the air curtains in the inlet lock 108 and / or in the outlet lock 110 of the casing 102, since even after the recirculating air has passed through the air cleaning device 118, in particular through a condenser of the air cleaning device 118, traces of solvent may still be present in the recirculating air and thus in the CO2-reduced gas mixture leaving the CC reduction device 126.These traces of solvents would be forced into the ambient area 103 of the enclosure 102 when used as part of an air curtain in the entry lock 108 or in the exit lock 110, which could result in the permissible maximum workplace concentration (MAK value) of the solvent in question being exceeded in the ambient area 103 of the enclosure 102.

[0187] In addition, traces of solvent in the gas mixture supplied to the CO2 reduction device 126 may disrupt the operation of the CO2 reduction device 126.

[0188] In principle, it is possible, in a variant of the second embodiment of a system 100 for treating a material to be treated 105 shown in Fig. 2, to provide an additional CO2 reduction device 126, to which ambient air is supplied through an ambient air supply 127 and which delivers a CO2-reduced gas mixture via a first supply line 128 and a second supply line 130 to an air curtain generating device of the entrance lock 108 or to an air curtain generating device of the exit lock 110, as has been described above in connection with the first embodiment of the system 100 shown in Fig. 1.

[0189] Otherwise, the second embodiment of a system 100 for treating a material to be treated 105 shown in Fig. 2 corresponds in terms of structure, function and method of manufacture to the first embodiment shown in Fig. 1, to the above description of which reference is made in this respect.

[0190] A third embodiment of a system 100 for treating a material 105 to be treated, shown schematically in Fig. 3, differs from the first embodiment shown in Fig. 1 in that the treatment of the material 105 to be treated in the interior of the casing 102 of the system 100 not only comprises drying the material 105 to be treated, but also coating the initially uncoated material 105 to be treated and pressing the material 105 to be treated to produce a laminate from a material web 104 and one or more coating films in a system encapsulated by the casing 102.

[0191] This third embodiment of a system 100 comprises an unwinding device 106 which delivers an untreated material web 104.

[0192] The material web 104 passes through an entrance lock 108 into the interior 138 of the casing 102, which separates the interior 138 of the casing 102 serving as the treatment area 140 of the system 100 from the surrounding area 103 surrounding the casing 102.

[0193] In the treatment area 140, the material web 104 comes into contact with two coating films 136, of which a first coating film 136a is applied to a first side of the material web 104 and a second coating film 136b is applied to a second side of the material web 104 opposite the first side. After further movement of the combination of material web 104 and the coating films 136a and 136b along the direction of movement 134 of the material web 104, these layers enter a nip 142 between two laminating rollers 144, thereby forming a laminate of the material web 104 and the coating films 136a and 136b.

[0194] This laminate, which represents the treated material web 104', exits the interior 138 of the casing 102 through an exit lock 110.

[0195] Via an optional deflection roller 146, the treated material web 104' reaches a winding device 112, in which the treated material web 104' is provided in the form of a roll.

[0196] To produce the first coating film 136a, the system 100 comprises a first film forming device 146a, which is arranged in the interior space 138 of the shell 102.

[0197] The first film-forming device 146a is designed to form a coherent first coating film 136a from a powdery material, in particular an electrochemically active material.

[0198] For example, the first film-forming device 146a may include a pair of film-forming rollers 148. The powdered active material 147 is drawn into a nip between the film-forming rollers 148 and discharged from the nip between the film-forming rollers 148 as a continuous coating film 136.

[0199] The first coating film 136a is guided through a gap between two calendering rollers 150 and toward the first side of the material web 104 to be joined thereto. Blow-off devices 152 are arranged along the path of travel of the first coating film 136a, by means of which the coating film 136a, consisting of initially wet active material, can be dried by blowing it off with warm drying air. Alternatively or in addition to the blow-off devices 152, other heating devices for heating the first coating film 136a can also be provided.

[0200] The maintenance of a predetermined interval of tensile stresses in the first coating film 136a is monitored by means of one or more tensile stress sensors 154 which are arranged along the movement path of the first coating film 136a.

[0201] To produce the second coating film 136b, the system 100 comprises a corresponding second film forming device 146b, which is also arranged in the interior space 138 of the shell 102 of the system 100.

[0202] By means of the second film-forming device 146b, which comprises, for example, a pair of film-forming rollers 148, the second coating film 136b is formed from a powdered electrochemically active material 147, which is then passed through the gap between two calendering rollers 150 and fed to the second side of the material web 104 in order to be bonded thereto.

[0203] Blow-off devices 152 are arranged along the movement path of the second coating film 136b, by means of which the second coating film 136b, consisting of initially wet electrochemically active material, can be dried by blowing it off with warm, dry air. Alternatively or in addition to the blow-off devices 152, other heating devices for heating the second coating film 136b can also be provided. Maintaining a predetermined interval of tensile stresses in the second coating film 136b is monitored by one or more tensile stress sensors 154 arranged along the movement path of the second coating film 136b.

[0204] For the reasons already mentioned above, it is advantageous if the treatment in the interior space 138 of the casing 102 serving as the treatment area 140 of the system 100 is carried out in a CO2-free atmosphere or an atmosphere at least with a reduced CO2 content compared to the ambient air.

[0205] For this purpose, the third embodiment of a system 100 for treating a material to be treated 105, like the first embodiment shown in Fig. 1, comprises a CO2 reduction device 126, to which ambient air from the surrounding area 103 of the casing 102 can be supplied via an ambient air supply 127.

[0206] The CO2 content of this ambient air is reduced by means of the CC reduction device 126.

[0207] The CO2-reduced gas mixture from the CO2-reducing device 126 can be fed via a first feed line 128 to an air curtain generating device (not shown) of the entrance lock 108 and via a second feed line 130 to an air curtain generating device (also not shown) of the exit lock 110.

[0208] The CO2-reduced gas mixture from which the air curtains in the entrance lock 108 and in the exit lock 110 are formed partially enters the interior space 138 of the shell 102, thereby reducing the CO2 content in the atmosphere in the interior space 138 of the shell 102.

[0209] For the fresh air supplied to the interior 138 of the enclosure 102 via the ambient air supply 127, an equivalent amount of exhaust air must be supplied to a post-treatment device 129. For this purpose, the system 100 can comprise an exhaust air line 125 through which exhaust air from the interior 138 of the enclosure 102 reaches the post-treatment device 129.

[0210] Otherwise, the third embodiment of a system 100 for treating a material to be treated 105 shown in Fig. 3 corresponds in terms of structure, function and method of manufacture to the first embodiment shown in Fig. 1, to the above description of which reference is made in this respect.

[0211] In all three embodiments of systems 100 for treating a material 105 to be treated described above, harmful effects of CO2 on the respective treatment process are reduced or completely avoided by supplying CO2-reduced gas mixtures into the interior 138 of the shell 102 of the system.

[0212] For example, in the production of electrodes for electrochemical cells, especially battery cells, the harmful influence of CO2 is reduced or preferably completely avoided by the formation of carbonates and hydrogen carbonates in the electrode materials.

[0213] If CO2 is to be reduced in a gas mixture consisting of the ambient air in the respective CC reduction device 126, in principle all processes for the direct separation of CO2 from air ("Direct Air Capture"; DAC) can be used.

[0214] Preferably, CO2 is adsorbed or absorbed by a sorbent, and the CO2 is desorbed from the sorbent through a desorption process to regenerate and reuse the sorbent. These desorption processes can be divided into the following:

[0215] Type A processes, which use a liquid sorbent, can be divided into low-temperature desorption processes (at a desorption temperature of 100°C or less) and high-temperature desorption processes (at a desorption temperature of more than 100°C or up to 900°C).

[0216] Type B processes, which use a solid-bound sorbent. These processes can be divided into temperature swing desorption processes (at a desorption temperature of no more than 100°C) and humidity swing desorption processes (at a desorption temperature of preferably no more than 100°C).

[0217] Suitable processes for CC reduction using a CC reduction device 126 are described, for example, in the study by Maria Erans, Eloy S. Sanz-Perez, Dawid P. Hanak, Zeynep Clulow, David M. Reiner, and Greg A. Mutch: "Direct air capture: process technology, techno-economic and sociopolitical challenges," published in Energy Environ. Sci., 2022, Volume 15, pages 1360 to 1405, to which reference is made in this regard.

[0218] In all "Direct Air Capture" processes, the gas mixture in which the CO2 content is to be reduced is brought into contact with a sorbent in a gas mixture contactor 156 (see, for example, Fig. 4).

[0219] When using a type A DAC process, the CO2 is removed from the supplied gas mixture by absorption in a liquid sorbent.

[0220] The liquid sorbent can, for example, be an aqueous solution of monoethanolamine (MEA). Disadvantages of using MEA as a liquid sorbent, which are known from the literature, include high water loss through evaporation, the reaction of the sorbent with atmospheric oxygen, and the formation of heat-stable salts.

[0221] The use of MEA as a liquid sorbent is described, for example, in the report by Edward S. Rubin and Anand B. Rao: "A Technical, Economic and Environmental Assessment of Amine-based CO2 Capture Technology for Power Plant Greenhouse Gas Control" for the US Department of Energy (Contract No. DE-FC26-00NT40935) from October 2002, to which reference is made in this regard.

[0222] As an alternative to an aqueous solution of MEA, another basic reagent can be used, such as an aqueous solution of polyethyleneimine (PEI). An aqueous solution of PEI shows a lower efficiency loss than an aqueous solution of MEA.

[0223] All DAC processes in which sorbents are used and regenerated have in common that the respective sorbent is cyclically converted from an unloaded state in which the CO2 is desorbed from the sorbent to a loaded state in which the CO2 is absorbed in the sorbent.

[0224] In this way, the CO2 absorption capacity of the respective sorbent is used multiple times by regenerating the sorbent.

[0225] The cyclical alternation between loading and unloading of the sorbent with CO2 is achieved by a swing process, in which pressure, temperature, humidity, and / or another parameter is cyclically modulated temporally and / or spatially. The respective sorbent can be applied in a stationary bed, a moving bed, or a fluidized bed, or can be arranged on a support with a large surface area, where the support can be a monolith or a plurality of fibers.

[0226] In general, the aim is to shift the majority of the energy consumed by the DAC process to the desorption process, in which the CO2 is present in a more concentrated form than in the gas mixture from which the CO2 is separated by means of the gas mixture contactor 156.

[0227] An absorption and desorption process usable in a CC reduction device 126 is shown schematically in Fig. 4.

[0228] In a first step, which takes place in the gas mixture contactor 156, an aqueous alkali hydroxide solution reacts with CO2 from the gas mixture 158 supplied to the CO2 reduction device 126 to form a solution containing an alkali carbonate species. In the illustrated embodiment, an aqueous potassium hydroxide solution is used, with which the CO2 reacts to form water and potassium carbonate (K2CO3) in aqueous solution.

[0229] By this reaction of the gaseous CO2 from the supplied gas mixture 158 with the alkali hydroxide solution, the content of CO2 in the gas mixture is reduced, and a CO2-reduced gas mixture 160 is released from the gas mixture contactor 156.

[0230] The aqueous alkali carbonate solution is fed to a reactor 162, in which the alkali carbonate, for example, K2CO3, reacts with calcium hydroxide (Ca(OH)2), preferably in the form of solid pellets, to form an alkali hydroxide in aqueous solution and precipitated calcium carbonate (CaCO3) in solid form. The aqueous solution of alkali hydroxide, for example, potassium hydroxide, is returned to the gas mixture contactor 156, thereby completing the first material cycle for the absorption process in Fig. 4.

[0231] The precipitated calcium carbonate (CaCC ) is fed to a calciner 164.

[0232] In the calciner 164, the calcium carbonate (CaCC) is calcined by adding heat, releasing gaseous CO2 and leaving behind solid calcium oxide (CaO).

[0233] The gaseous CO2 is released into the environment, for example into the ambient area 103.

[0234] The calcium oxide (CaO) is fed to a lime slaking device 166 in which it is slaked with liquid water to form calcium hydroxide (Ca(OH)2) in solid form.

[0235] The calcium hydroxide (Ca(OH)2) is then fed back to the reactor 162, thereby closing the second material cycle for the desorption process in Fig. 4.

[0236] Details of this DAC process are described in Keith et al., "A processing for capturing CO2 from the atmosphere," Joule, 2018, Volume 2, pages 1573 to 1594. This description is incorporated herein by reference.

[0237] In the DAC process described above with reference to Fig. 4, the CO2 to be separated from the gas mixture 158 is thus bound in a carbonate or hydrogen carbonate in an absorption loop 168 and precipitated in the reactor 162 by means of a precipitation reagent.

[0238] The precipitation product calcium carbonate (CaCC) is itself regenerated at a higher temperature (preferably higher than 100°C and / or preferably at most 900°C), with gaseous CO2 being separated as a pure substance. It can be provided that only the local absorption of the CO2 into the base (the aqueous solution of alkali hydroxide) is carried out by means of a gas mixture contactor 156 in the form of a simple scrubber in the CO2 reduction device 126 of the system 100 for treating a material 105, and that the carbonate / hydrogen carbonate solution produced in the gas mixture contactor 156 of the CO2 reduction device 126 is transported to another location for the precipitation of the calcium carbonate (CaCC) where the reactor 162, the calciner 164, and the lime slaking device 166 are located, and where preferably higher temperatures can also be generated for the regeneration.

[0239] In the variant of a DAC process shown schematically in Fig. 5, an electrochemical regeneration of the aqueous alkali hydroxide solution is carried out instead of a thermal regeneration in order to make the regeneration of the liquid sorbent less energy-intensive.

[0240] In this variant, the CO2 reduction device 126 also comprises a gas mixture contactor 156, which can be designed in particular as an air washer.

[0241] A CO2-laden gas mixture 158 is fed to the gas mixture contactor 156, and a CO2-reduced gas mixture 160 exits the gas mixture contactor 156.

[0242] In the gas mixture contactor 156, an aqueous alkali hydroxide solution reacts with CO2 from the supplied gas mixture 158 to obtain an aqueous solution containing alkali ions (for example K + ), carbonate ions (CO3 2) and hydrogen carbonate ions (HCO3). This aqueous solution of alkali carbonate and alkali hydrogen carbonate is fed to an electrodialysis device 176 via a discharge line 172, in which a pump 174 is arranged. The electrodialysis device 176 comprises a cathode 178 and an anode 180, between which an electrical potential difference is applied.

[0243] Between the cathode 178 and the anode 180 are arranged a cation exchange membrane 182, a first bipolar membrane 184, an anion exchange membrane 186, a second bipolar membrane 188 and a second anion exchange membrane 190.

[0244] Each of the bipolar membranes 184 and 188 comprises a cation exchange layer 192 and an anion exchange layer 194.

[0245] If the potential difference applied between the cathode 178 and the anode 180 is greater than twice the dissociation potential for water, each of the bipolar membranes 184 and 188 splits water into protons (H + ) and hydroxide ions (OH ).

[0246] The anion exchange membrane 186 arranged between the two bipolar membranes 184 and 188 separates a basic compartment 196 of the electrodialysis device 176 from an acidic compartment 198.

[0247] The aqueous solution of alkali ions, carbonate ions (CO3 2 ) and hydrogen carbonate ions (HCO3 ) from the gas mixture contactor 156 is fed to the basic compartment 196 of the electrodialysis device 176.

[0248] An acidic buffer solution is supplied to the acidic compartment 198 of the electrodialysis device 176 via a supply line 200 in which a pump 202 is arranged.

[0249] In the basic compartment 196 of the electrodialysis device 176, the alkali ions (for example K + ) and the hydroxide ions (OH ) resulting from the electrodialysis of water in the first bipolar membrane 184 to an alkali hydroxide (for example KOH) in aqueous solution, which is removed from the basic compartment 196 of the electrodialysis device 176 and fed via a feed line 204 to the gas mixture contactor 156 of the CC reduction device 126.

[0250] The carbonate ions (CO3 2 ) and hydrogen carbonate ions (HCO3 ) diffuse in the electric field generated in the electrodialysis device 176 through the anion exchange membrane 186 into the acidic compartment 198 of the electrodialysis device 176. There, these CO2-carrying ions react with protons (H + ), which are produced by electrodialysis in the second bipolar membrane 188 to produce CO2 dissolved in the acidic buffer solution.

[0251] The CO2-enriched acidic buffer solution is removed from the acidic compartment 198 of the electrodialysis device 176 via a discharge line 206 and fed to a gas separator 208, which separates the CO2 dissolved in the acidic buffer solution from the solution and releases it into the ambient area 103 of the casing 102 via a CO2 outlet 209.

[0252] The acidic buffer solution from which the CO2 has been separated by means of the gas separator 208 is fed back to the acidic compartment 198 of the electrodialysis device 176 via the feed line 200.

[0253] In the variant of a DAC process shown in Fig. 5, only the supply of electrical energy is required and no precipitation reaction is carried out.

[0254] As indicated by the dots in the right-hand part of the electrodialysis device 176 in Fig. 5, a stack 220 of electrochemical cells can be connected to the right of the second bipolar membrane 188, with each electrochemical cell comprising a basic compartment 196, an anion exchange membrane 186, an acidic compartment 198, and a bipolar membrane 188. Branches of the discharge line 172 and the supply line 204 are then connected to the basic compartments 196, and branches of the supply line 200 and the discharge line 206 are connected to the acidic compartments 198 of these additional electrochemical cells. As indicated by the dots in the left-hand part of the electrodialysis device 176 in Fig.As indicated in Figure 5, a stack 222 of electrochemical cells can be connected to the left of the first bipolar membrane 184, with each electrochemical cell comprising (from right to left) an acidic compartment 198, an anion exchange membrane 186, a basic compartment 196, and a bipolar membrane 184. Branches of the discharge line 172 and the supply line 204 are then connected to the basic compartments 196, and branches of the supply line 200 and the discharge line 206 are connected to the acidic compartments 198 of these additional electrochemical cells.

[0255] For each electrochemical cell added to the electrodialysis device 176, the electrical potential difference between the cathode 178 and the anode 180 must be increased by the dissociation potential of water.

[0256] A detailed description of the DAC process shown in Fig. 5 can be found in the article by F. Sabatino, M. Mehta, A. Grimm, M. Gazzani, F. Gallucci, G.

[0257] J. Kramer and M. Van Sint Annaland in Ind. Eng. Chem. Res., 2020, Volume 59, pages 7007 to 7020, to which reference is made.

[0258] A variant of the DAC process from Fig. 5, schematically illustrated in Fig. 6, differs from the DAC process from Fig. 5 in that the gas mixture contactor 156 is not designed as an air scrubber, but as a membrane contactor 230. The membrane contactor 230 comprises a permeate space 232, through which the CO2-laden gas mixture 158 can flow, and a retentate space 236 separated from the permeate space 232 by a membrane 234. The retentate space 236 can be flowed through by a liquid sorbent, for example an alkali hydroxide (in particular KOH) in aqueous solution, which is fed to the membrane contactor 230 via the feed line 204.

[0259] The membrane 234 of the membrane contactor 230 is permeable to CO2 molecules from the gas mixture on the permeate side of the membrane contactor 230, but not to the liquid sorbent arranged on the retentate side of the membrane contactor 230.

[0260] Compared to an air washer in which the CO2-containing gas mixture comes into contact with a liquid, in particular with an aqueous solution, the membrane contactor 230 offers the advantage that no significant amount of liquid, in particular water, is released into the gas mixture.

[0261] The membrane 234 can, for example, comprise hollow fibers whose interior is permeated by the CO2-containing gas mixture, while the fibers are in contact with the liquid sorbent on their exterior. The CO2 then passes from the permeate side (interior of the hollow fibers) through the material of the hollow fibers to the retentate side (outside of the hollow fibers).

[0262] Alternatively, the membrane 234 of the membrane contactor 230 can also comprise hollow fibers, around which the CO2-containing gas mixture flows on their outside, while the liquid sorbent is arranged in the cavities inside the hollow fibers. In this case, the CO2 passes through the material of the hollow fibers from the permeate side (outside of the hollow fibers) to the liquid sorbent on the retentate side (cavities inside the hollow fibers). Such a membrane contactor 230, in which the liquid sorbent is arranged in the interior of the hollow fibers, is described, for example, in the dissertation by P.S. Kumar: "Development and Design of Membrane Gas Absorption Processes," 2002, University of Twente, published by Twente University Press, particularly on page 4.

[0263] In another variant of a

[0264] In the DAC process, which can be used in a CC reduction device 126, the gas mixture loaded with CO2 is passed in a gas mixture contactor 156 through a disposable exchange container in which so-called soda lime is arranged, which at least partially absorbs the CO2 from the gas mixture.

[0265] Soda lime is also used in anesthesia machines and in rebreathers to bind CO2 contained in exhaled air.

[0266] In particular, a mixture of calcium hydroxide (Ca(OH)2) and sodium hydroxide (NaOH) or a mixture of potassium hydroxide (KOH) and barium hydroxide (Ba(OH)2) can be used as soda lime.

[0267] When using the first mixture, the CO2 from the gas mixture reacts with water in the disposable swap container to form carbonic acid, which then reacts further with sodium hydroxide to form sodium carbonate and water.

[0268] The sodium carbonate reacts with calcium hydroxide to form calcium carbonate and sodium hydroxide, so that the CO2 is finally bound in the form of calcium carbonate (CaCO3).

[0269] A pH indicator may be added to the soda lime, which changes color at low pH values, for example, from white to violet, thereby indicating that the CO2-absorbing soda lime has been used up. Further details on soda lime and its use for absorbing CO2 from a gas mixture can be found in the Wikipedia article on the keyword "Soda Lime" as of December 4, 2023, which is incorporated herein by reference.

[0270] A solid-bound sorbent suitable for use as soda lime is marketed under the name "Drägersorb Free - Soda Lime" by Drägerwerk AG & Co. KGaA, Moislinger Allee 53-55 in 23558 Lübeck, Germany.

[0271] In a variant of a DAC process shown schematically in Fig. 6, the CO2 from a supplied gas mixture 158 is passed through an adsorption bed 210 in a gas mixture contactor 156 of a CC reduction device 126.

[0272] The adsorption bed 210 comprises a solid support material onto which, for example, polyethyleneimine (PEI) is applied as a sorbent.

[0273] The PEI acts as a "CO2 sponge" and adsorbs CO2 from the gas mixture passed through the adsorption bed 210 until all coordination sites of the PEI for CO2 are occupied.

[0274] A CO2-reduced gas mixture 160 exits the adsorption bed 210.

[0275] When the adsorption capacity of the adsorption bed 210 is reached, the CC reduction device 126 is switched from the adsorption mode shown in Fig. 6 above to the desorption mode shown in Fig. 6 below.

[0276] This is achieved, in particular, by separating the adsorption bed 210 from the stream of gas mixture 158 and applying a vacuum. Furthermore, heat 212 is supplied to heat the adsorption bed 210 to a desorption temperature, preferably in the range of approximately 80°C to 100°C. Heating under vacuum causes the CO2 to detach from the PEI coordination sites in the adsorption bed 210 and be released from the adsorption bed 210 as a gaseous CC stream 214. This CC stream 214 can be released into the ambient region 103 of the shell 102 of the system 100 or compressed for further use or storage.

[0277] During the desorption of CO2, water 216 is usually also released from the adsorption bed 210.

[0278] When all coordination sites of the adsorption bed 210 are available for CO2 again, the CC reduction device 126 is returned to the adsorption mode shown in Fig. 6 above and can be used again to adsorb CO2 from the supplied gas mixture 158.

[0279] Instead of polyethyleneimine (PEI), another sorbent, for example a so-called "metal organic framework" (MOF), can be used as a component of the adsorption bed 210.

[0280] In this case, too, large amounts of heat are required for the desorption of the adsorbed CO2 at a temperature level in the range of approximately 120° C to approximately 150° C.

[0281] All of the above-described methods for separating CO2 from a gas mixture, in particular the methods schematically illustrated in Figs. 4 to 6, can be used in each of the CO2 reduction devices 126 of each of the above-described embodiments of a plant 100 for treating a material to be treated 105.

Claims

Patent claims 1. A system for treating a material to be treated (105), comprising a treatment area (140) in which the treatment of the material to be treated (105) can be carried out, and a casing (102) for separating the treatment area (140) from an ambient area (103) surrounding the casing (102), characterized in that the system (100) comprises at least one CCh reduction device (126) for at least partially removing carbon dioxide (CO2) from a gas mixture (158) containing CO2.

2. System according to claim 1, characterized in that the system (100) comprises a fresh air supply (127) by means of which at least one of the at least one CC reducing devices (126) can be supplied with fresh air from outside the treatment area (140).

3. Plant according to one of claims 1 or 2, characterized in that the plant (100) comprises at least one lock (108, 110) through which the material to be treated (105) can be fed to the treatment area (140) and / or removed from the treatment area (140), wherein preferably the lock (108, 110) comprises an air curtain generating device for generating an air curtain in the area of the lock (108, 110) and a gas mixture (160) reduced in CO2 by means of at least one of the at least one CC reducing devices (126) can be fed to the air curtain generating device.

4. System according to one of claims 1 to 3, characterized in that the system (100) comprises a recirculating air circuit (114), wherein at least one CO2 reducing device (126) is arranged in the recirculating air circuit (114).

5. System according to claim 4, characterized in that at least one air cleaning device (118) and / or at least one air heating device (122) is arranged in the recirculating air circuit (114).

6. Installation according to one of claims 1 to 5, characterized in that the installation (100) comprises a suspension device for keeping a material to be treated (105) in suspension.

7. Plant according to one of claims 1 to 6, characterized in that the treatment area (140) comprises a drying area in which a material to be treated (105) can be dried.

8. Plant according to one of claims 1 to 7, characterized in that the plant (100) comprises a coating device arranged within the casing (102).

9. Plant according to one of claims 1 to 8, characterized in that the plant (100) comprises at least one film-forming device (146a, 146b) arranged within the casing (102).

10. Plant according to one of claims 1 to 9, characterized in that the plant (100) is a plant for producing a coated electrode material.

11. Plant according to one of claims 1 to 10, characterized in that at least one of the at least one CCh reducing devices (126) is designed such that moisture contained in the gas mixture (158) can be at least partially removed from the gas mixture (158) with the same.

12. Plant according to one of claims 1 to 11, characterized in that at least one of the at least one CO2 reducing devices (126) comprises a liquid sorbent for absorbing CO2.

13. Plant according to claim 12, characterized in that the plant (100) comprises an electrodialysis device (176) to which sorbent loaded with CO2 can be fed.

14. Plant according to one of claims 1 to 13, characterized in that at least one of the at least one CO2 reducing devices (126) comprises a membrane contactor (230), wherein a liquid sorbent for absorbing CO2 can be supplied to a retentate side of the membrane contactor (230).

15. Plant according to one of claims 1 to 14, characterized in that at least one of the at least one CO2 reducing devices (126) comprises a solid-bound sorbent for absorbing CO2.

16. A method for treating a material to be treated (105) in a treatment area (140) which is arranged within a casing (102) for separating the treatment area (140) from an ambient area (103) surrounding the casing (102), comprising the following: at least partially removing carbon dioxide (CO2) from a gas mixture (158) containing CO2.

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