DE102024111238B3 - Porous electrically conductive three-dimensional network, porous electrically conductive three-dimensional network manufacturing method and use - Google Patents

Abstract

The invention relates to a porous electrically conductive three-dimensional network, characterized in that the porous electrically conductive three-dimensional network is formed from a three-dimensionally formed chemically inert and electrically conductive material, wherein the three-dimensionally formed chemically inert and electrically conductive material has at least one partial or complete coating with an adsorbent.

Description

The invention relates to a porous, electrically conductive three-dimensional network. Furthermore, the invention relates to a production method for a porous, electrically conductive three-dimensional network and a use thereof.

To separate gases in large-scale industrial plants, so-called pressure or temperature swing adsorbers are commonly used today. These are containers made of nanoporous materials that are preferentially loaded with one of the gases to be separated in a thermodynamic state. If the pressure or temperature is then changed, the gas is released again. By cleverly switching valves, the two gases, for example, nitrogen and carbon dioxide, can be separated.

Pressure swing adsorbers are typically energetically inefficient due to the pumps required to generate low pressures. Temperature swing adsorbers are also energetically inefficient because they require heating the entire container containing the nanoporous material, the so-called adsorbent. The adsorbent is typically a large, monolithic block of activated carbon or other technically relevant adsorbents such as zeolites or metal-organic frameworks (MOFs). Their heat capacity must always be considered in the energy budget and is lost during heating and cooling, resulting in very slow cycles and large heat losses during loading and unloading.

The same applies to all filters used to separate or purify gases. These include, for example, water filters and/or humidity filters, which absorb atmospheric moisture and can only be regenerated through prolonged storage at temperatures up to 120 °C.

Typically, large-scale temperature swing adsorbers operate on the principle of high capacity, resulting in long loading and regeneration cycles. The duration of a cycle depends on the heating and cooling rates that can be imposed and is usually on a time scale of minutes to hours. The energy used per mass of product is measured. This consists of at least the desorption enthalpy of the stored gas, but in reality also the heat capacities of the adsorbents, the reactor, the carrier gases, and the heat losses due to heat flow and convection. The slower the heating is carried out, the more energy is put into the loss-making processes and the smaller the proportion of energy used for the process. For example, the adsorption enthalpy for carbon dioxide in a zeolite is given as 0.5 MJ/kg. However, according to Augustine Ntiamoah et al. (“ CO2 Capture by Temperature Swing Adsorption: Use of Hot CO2-Rich Gas for Regeneration", Ind. Eng. Chem. Res. 2016, 55(3), 703-713 ) more than 6 times higher at over 3 MJ/kg.

If the desorption times are shortened by a clever design of the adsorbents, the process becomes more efficient in terms of time and energy, and the large-scale enrichment of gases such as carbon dioxide, water, nitrogen, hydrogen sulfide and other gases becomes much more attractive.

According to the state of the art, temperature swing adsorption, also in combination with pressure swing adsorption, is a well-known principle for separating gas mixtures, especially carbon dioxide and water, as already described here. Temperature swing adsorption is used, for example, in exhaust gas purification for the trace-based separation of contaminants from flue gases from combustion plants.

The printed matter EP 3 437 734 A1 discloses an adsorber for indirectly heated temperature swing adsorption, comprising: at least one channel containing at least one adsorbent in the form of solid adsorbent particles, at least one insert made of a thermally conductive material and inserted into the at least one channel, wherein the at least one void portion has at least one void portion and the adsorbent particles at least partially fill the void portion of the insert.

From the printed publication EP 1 291 067 A2 is an adsorbent used for the temperature swing adsorption of contaminants such as water from a gas stream such as air packed in the tube-side passages of a shell-and-tube heat exchanger. After an adsorption phase, during regeneration, a heating fluid is passed through the shell-side passage of the adsorber and, upon exiting the adsorber, is returned to the adsorber shell via a heater. During the cooling phase, a cooling fluid is passed through the shell-side passage of the adsorber.

In addition, the publication describes US 2018 / 214817 A1 a device for adsorbing at least one component from a gas mixture by temperature swing adsorption, comprising a flow-through chamber and a cooling chamber for receiving a heat transfer fluid, wherein the flow-through chamber is separated from the Cooling chamber is separated, wherein the flow-through chamber has an adsorbent which contains a plurality of (two or more) adsorbent bodies which contain a porous and adsorptively additive first material and a second material with a better thermal conductivity compared to the first material and wherein the first material is at least partially surrounded by the second material.

The printed matter US 2012 / 222555 A1 and US 8 852 322 B2 disclose a gas separation process using a structured particle bed of adsorbent-coated shapes/particles that are deposited in an orderly manner in the bed to simulate a monolith by creating longitudinally extended gas passageways through which the gas mixture to be separated can pass along the length of the particles to the adsorbent. The particles can be deposited either directly in the bed or in locally structured packets/bundles that are similarly aligned, so that the bed particles behave similarly to a monolith. The adsorbent particles can be formed with a solid, non-porous core, with the adsorbent formed as a thin, adherent coating on the exposed outer surface. The particles can be cylindrical or hollow in shape to allow easy access to the adsorbent. Separation can be carried out as a kinetic or equilibrium-controlled process.

In addition, the publication describes DE 20 55 425 B2 an adsorption process for the separation of gas mixtures in an adsorption system consisting of separate, series-connected zones I and II, in which the non-adsorbed gas portion is removed at the end of the adsorption system, zones I and II are desorbed under pressure reduction and, after regeneration, during the pressure build-up in the adsorption system, the pressure increase in zone II is delayed compared to zone I, characterized in that during the separation of gas mixtures containing water vapor in zone I, the water vapor is removed and the adsorbed gas portion is withdrawn from zone II for the desorption of the water vapor in zone I in the opposite direction to the loading through zone I.

The printed matter EP 3 318 321 B1 shows a method for producing an adsorption device, a conversion method for an adsorption device, and an adsorption device produced according to the manufacturing method. In the method for producing an adsorption device, 1. an adsorber bed of the adsorption device is filled with a bed of an adsorbent selected from a plurality of adsorbents using a testing method; 2. a particle of each adsorbent is repeatedly loaded with a sorbate and regenerated, whereby the particle becomes an aged particle; and 3. a fracture property B of the aged particle of each adsorbent is determined, wherein the adsorbent for the bed is selected from the plurality of adsorbents depending on the determined fracture property B.

Furthermore, the publication discloses DE 3 702 190 A1 A process for the purification and drying of gas mixtures, particularly air upstream of air separation plants, by adsorption. Adsorbers for this purpose are equipped with two beds, the first of which binds the water and the second of which binds the component to be separated from the gas stream. The process is carried out in such a way that the adsorption heat generated during adsorption is largely retained in the adsorber to support desorption during subsequent regeneration.

The publication also reveals DE 199 35 383 A1 A method and apparatus for purifying air of contaminants such as water, carbon dioxide, nitrous oxide, ethylene, and/or propane by thermally regenerated adsorption. In an adsorption cycle, air to be purified is passed successively at a first temperature T1 through a first adsorption zone containing a first adsorbent and through a second adsorption zone containing a second adsorbent. In a regeneration cycle, a regeneration gas is introduced into the first adsorption zone at a second, higher temperature T2. In the first adsorption zone, water vapor and/or carbon dioxide are essentially completely removed from the air. The second adsorption zone has an adsorbent containing strongly nitrogen-binding metal ions.

The printed matter EP 3 102 308 B1 describes a process for producing or purifying a synthesis gas comprising carbon monoxide and at least hydrogen, carbon monoxide, methanol, water, and optionally nitrogen. The synthesis gas is produced according to the prior art by steam reforming or partial oxidation. To increase the carbon monoxide content in the synthesis gas, carbon monoxide separated from the synthesis gas can be recycled as a reactant prior to gas production.

Alternative electrical heating methods for temperature swing adsorption include electrical swing adsorption, which uses the Joule effect, induction heating and microwave heating. Here, a conductive adsorbent such as activated carbon is used in particular These alternative systems can be very fast and have large capacities, but heat losses occur due to the heat capacity of the carrier or adsorbent.

Y. Gomez-Rueda et al. describe in their publication "Rapid temperature swing adsorption using microwave regeneration for carbon capture," Chemical Engineering Journal, 2022, 446(4), 137345, ISSN 1385-8947, https://doi.org/10.1016/j.cej.2022.137345 For example, the use of microwave heating for the thermal regeneration of a porous carbon adsorbent in adsorptive carbon deposition. A multimode microwave oven is used here to accelerate the desorption of CO ₂ after the adsorption of a CO ₂ /N ₂ mixture (15/85 v/v).

The main problems with the current state of the art are that current temperature swing adsorbers are both energy inefficient and slow. Currently, the operation of temperature swing adsorbers only makes sense if the waste heat from process gases can be used to regenerate the adsorbents.

In smaller applications, the high temperatures required and the slow regeneration mean that regeneration can only take place outside of the actual filter application process. A filter cartridge filled with, for example, zeolite or activated carbon must be removed from an analytical setup and then heated for hours at 300 °C using ultra-dry, synthetic air to ensure that the adsorbate, such as water, is removed from the adsorbents. Therefore, the state-of-the-art temperature swing adsorber solution is not suitable for mobile devices and user-friendly applications.

The operation of temperature swing adsorbers can currently only be effectively implemented in large-scale industrial plants and, as described, is not suitable for smaller setups capable of enriching gases on a local scale. However, in many cases, direct air capture processes using adsorbents prove to be completely energy-inefficient, even in large-scale plants. Currently, there is no adequate solution to this problem based on the state of the art, as the energy required for regeneration is too high. Furthermore, the enrichment of water in arid regions to produce drinking water, for example, is a particularly difficult task for existing temperature swing adsorbers, as the necessary process gases and equipment are often unavailable.

The present invention is based on several objects.

The invention aims to provide a temperature swing adsorber design with improved regeneration. Desorption in the adsorbers is to be simplified and accelerated, enabling short filter cycle times.

A further object of the invention is to make the principle of temperature swing adsorption more energy efficient.

A further objective is to provide a temperature swing adsorber assembly that allows for regeneration of the adsorber within the assembly, eliminating the need to remove the adsorber for regeneration. Ideally, the temperature swing adsorber should also be miniaturized for mobile applications.

A further task can be seen in heating essentially only the adsorbent and not the entire space around the adsorbent.

These objects are achieved with a porous, electrically conductive three-dimensional network according to the main claim and two porous, electrically conductive three-dimensional network production methods according to the independent claims.

The porous, electrically conductive three-dimensional network is characterized in that the porous, electrically conductive three-dimensional network is formed from a three-dimensionally porous, chemically inert and electrically conductive material, wherein the three-dimensionally formed chemically inert and electrically conductive material has at least one partial or complete coating with an adsorbent.

In a preferred embodiment, the network can be designed as a temperature swing adsorber.

The three-dimensional chemically inert and electrically conductive material can also be made of carbon in particular.

In a preferred embodiment, the individual carbon arms in the network can have a diameter of 0.5 to 8 µm and/or 1 to 5 µm and the pores between the individual carbon arms can be between 30 and 120 µm and/or 50 and 100 µm in size.

The adsorbent may be formed from a nanoporous material, in particular from a metal-organic framework structure and/or a zeolite and/or a silica gel and/or a porous carbon and/or porous silica and/or porous polymers and/or covalent organic frameworks and/or nanoparticles with high specific surface areas and/or porous salts.

The network can have a porosity of at least 50% or more than 80%. Porosity refers to the ratio of the volume of voids in a porous material to its total volume.

Furthermore, the adsorbent can exhibit nanoporosity. Nanoporosity means that a material has structural or random pores that are on the atomic scale. Examples of structural, nanoporous materials are zeolites and MOFs.

In addition, the network can additionally contain conductive carbon nanotubes and conductive graphene nanoplatelets.

1. 1. Suspendieren und/oder Dispergieren von Adsorbensmaterial und ggf. Kohlenstoffnanoröhrchen in einem Dispersionsmedium;
2. 2. Infiltrieren eines dreidimensional ausgebildeten chemisch inerten und elektrisch leitfähigen Materials mit der Suspension/Dispersion aus Schritt 1.;
3. 3. Trocknen des infiltrierten dreidimensional ausgebildeten chemisch inerten und elektrisch leitfähigen Materials aus Schritt 2., wobei sich das in Schritt 1. suspendierte und/oder dispergierte Adsorbensmaterial auf das infiltrierte dreidimensional ausgebildete chemisch inerte und elektrisch leitfähige Material legt und so eine abschnittsweise oder vollständige Beschichtung ausbildet.

The porous, electrically conductive three-dimensional network manufacturing process comprises at least the following steps:

1. 1. Suspending and/or dispersing adsorbent material and, if applicable, carbon nanotubes in a dispersion medium;
2. 2. Infiltrating a three-dimensional chemically inert and electrically conductive material with the suspension/dispersion from step 1.;
3. 3. Drying the infiltrated three-dimensionally formed chemically inert and electrically conductive material from step 2, wherein the adsorbent material suspended and/or dispersed in step 1 is deposited on the infiltrated three-dimensionally formed chemically inert and electrically conductive material and thus forms a partial or complete coating.

In particular, the porous, electrically conductive three-dimensional network produced by the porous, electrically conductive three-dimensional network production method can preferably be the porous, electrically conductive three-dimensional network according to the invention.

Drying can be carried out for a period of 20 to 28 hours and/or 24 hours. Drying can also be carried out in a significantly shorter time, for example, in an oven, especially just below the boiling point of the dispersion medium.

The dispersion medium in step 1 can in particular be formed as a solution of water and/or alcohol.

Furthermore, in step 1, conductive carbon nanotubes can be introduced into the solution in addition to the adsorbent material.

A further porous, electrically conductive three-dimensional network production method comprises at least the step of synthesizing adsorbent as a partial or complete coating on a three-dimensional, chemically inert and electrically conductive material to form a porous, electrically conductive three-dimensional network. In particular, this porous, electrically conductive three-dimensional network produced using the second porous, electrically conductive three-dimensional network production method can also preferably be the porous, electrically conductive three-dimensional network according to the present invention.

Both porous electrically conductive three-dimensional network manufacturing processes described above produce a porous electrically conductive three-dimensional network with identical properties. The user can thus obtain a porous electrically conductive network of the same shape with defined properties using both manufacturing processes.

A porous, electrically conductive three-dimensional network application has the following steps:

• - feeding a gas mixture with different gas components into a temperature swing adsorber with a porous electrically conductive three-dimensional network formed as previously described;
• - Adjustable alternating adsorption and desorption of gas components in the temperature swing adsorber, wherein the adsorption is carried out at a lower temperature and the desorption is carried out by applying a power to the chemically inert and electrically conductive material of the porous, electrically conductive, three-dimensional network and thereby heating the network from the inside out and thus at a higher temperature;
• - Removal of gas components from the temperature swing adsorber.

The temperatures required for adsorption and desorption depend on the adsorbents used and the gases to be adsorbed (host-guest interaction). In any case, however, desorption occurs at higher temperatures than adsorption.

The use may additionally include the step of purging the adsorbent with a purge gas during the desorption process. The application of power to the chemically inert and electrically conductive material of the porous, electrically conductive three-dimensional network may be carried out in the form of power pulses.

In particular, the adjustable alternating adsorption and desorption in the temperature swing adsorber can be carried out continuously in continuous operation or in batch operation.

• - als Temperaturwechseladsorber und/oder
• - zur Filterung / Trennung / Abscheidung von Kohlenstoffdioxid aus der Atemluft und/oder
• - zur Filterung / Trennung / Abscheidung von Kohlenstoffdioxid aus der Umgebungsluft und/oder
• - zur Filterung / Trennung / Abscheidung von Kohlenstoffdioxid aus einem Gasgemisch und/oder Luftstrom und/oder
• - zur Filterung von Gasen und/oder
• - zur Reinigung von Gasen und/oder
• - zur Trennung von Gasen und/oder
• - zur Trocknung von Luft in Analytikgeräten und/oder
• - zur Trocknung von Luft in Verbraucherprodukten und/oder
• - zur Wasseranreicherung und/oder Wassergewinnung in wasserarmen Gegenden.

The porous, electrically conductive three-dimensional network can be used

• - as a temperature swing adsorber and/or
• - for filtering / separating / capturing carbon dioxide from the breathing air and/or
• - for filtering / separating / capturing carbon dioxide from the ambient air and/or
• - for filtering / separating / capturing carbon dioxide from a gas mixture and/or air stream and/or
• - for filtering gases and/or
• - for the purification of gases and/or
• - for the separation of gases and/or
• - for drying air in analytical devices and/or
• - for drying air in consumer products and/or
• - for water replenishment and/or water extraction in water-scarce areas.

The existing gas filters or adsorber cartridges, including the temperature swing adsorbers according to the state of the art, can be replaced by networks according to the invention.

In a particularly preferred embodiment, the networks consist of micrometer-thin carbon arms coated with a desired adsorbent micro- or nanoparticle system. By applying an external voltage, the entire network is heated from within. The adsorbents absorb the heat. This forces the stored gas to desorb. The open structure of the adsorbents makes this easy to do, allowing the entire unit to be regenerated in just a few seconds.

This approach makes the temperature swing adsorber/filter more energy-efficient. Heating the vessel and a large amount of the material is unnecessary, as the heat capacity of all structures is low, and the heat can be transferred directly from the porous, electrically conductive, three-dimensional network to the adsorbent via short paths. During desorption, the gas loses the energy needed to break the bond and therefore does not heat up significantly. This prevents excess heat from being generated, which reduces energy efficiency. Furthermore, the absence of heating of the structure allows for short cycle times, as it can be recharged with process gas immediately after desorption.

After production, the porous, electrically conductive, three-dimensional network can be flushed with gas as a complete system and thus used as a temperature swing adsorber and/or filter. When a gas mixture flows through the network, the adsorbents absorb the preferred gas due to their large and accessible surface area, and the non-preferred gas is thus enriched in the gas phase.

By switching valves in the reactor, it is possible to separate the reaction chamber from the gas mixture. If the network according to the invention located in the reaction chamber is then electrically contacted and heated, the heat is transferred from the three-dimensional, chemically inert and electrically conductive material to the adsorbents, and the gases stored therein are desorbed.

It is now possible to regenerate adsorbents from the inside out using defined electrical heating, so that heat does not have to be introduced from the outside through the material. Power pulses can even be used to suddenly release large quantities of the adsorbed gas without significantly heating the temperature swing adsorber and/or filter itself for a long time. During pulsed operation, the heat is transferred directly to the adsorbents, so that only minimal energy loss can occur through the removal of heat. At the same time, the material can be flushed with gas to transport the desorbed gas out of the framework structure. Due to the rapid desorption and the low heat capacity of the Thanks to the frame, the filter can then cool down quickly and without active cooling, making it immediately ready for another cycle of adsorption and desorption. Ideally, the temperature swing adsorber can also be miniaturized for mobile applications.

This allows filters to be operated continuously, even in small, non-large-scale industrial setups, that can clean, filter, or separate gases with high energy efficiency. This is not possible with conventional filters, which always require laborious regeneration outside of their installation. This opens up a wide range of applications, such as drying air for analytical devices, drying air in consumer products such as plastics drying in 3D printers, and filtration and possibly separation of carbon dioxide from the air we breathe.

• eine beispielhafte rasterelektronenmikroskopische Aufnahme eines dreidimensional ausgebildeten chemisch inerten und elektrisch leitfähigen Materials aus Kohlenstoff,
• eine beispielhafte schematische Darstellung des erfindungsgemäßen porösen, elektrisch leitfähigen dreidimensionalen Netzwerk-Herstellungsverfahrens,
• beispielhafte rasterelektronenmikroskopische Aufnahmen von a) einem dreidimensional ausgebildeten chemisch inerten und elektrisch leitfähigen Material aus Kohlenstoff, b) einem porösen, dreidimensionalen elektrisch leitfähigen Netzwerk mit einem dreidimensional ausgebildeten chemisch inerten und elektrisch leitfähigen Material aus Kohlenstoff und mit Zeolith als Adsorbens, c) eines vergrößerten Ausschnitts aus und in d) eine beispielhafte thermographische Abbildung eines erfindungsgemäßen porösen, dreidimensionalen elektrisch leitfähigen Netzwerks,
• eine beispielhafte rasterelektronenmikroskopische Aufnahme eines Ausschnitts eines porösen, dreidimensionalen elektrisch leitfähigen Netzwerks mit einem dreidimensional ausgebildeten chemisch inerten und elektrisch leitfähigen Material aus Kohlenstoff und mit einer metallorganischen Gerüststruktur als Adsorbens,
• eine beispielhafte fotographische Darstellung eines erfindungsgemäßen porösen, dreidimensionalen elektrisch leitfähigen Netzwerks mit einem dreidimensional ausgebildeten chemisch inerten und elektrisch leitfähigen Material aus Kohlenstoff,
• eine beispielhafte schematische Darstellung der Verwendung eines erfindungsgemäßen porösen, dreidimensionalen elektrisch leitfähigen Netzwerks als Temperaturwechseladsorber und
• beispielhafte rasterelektronenmikroskopische Aufnahmen von dem porösen, dreidimensionalen elektrisch leitfähigen Netzwerk mit einem dreidimensional ausgebildeten chemisch inerten und elektrisch leitfähigen Material aus Kohlenstoff und mit einer metallorganischen Gerüststruktur (MOF) als Adsorbens mit a) CAU-10 H, b) MOF 303 und c) MOF 801 als metallorganische Gerüststruktur.

The invention is described below with reference to the accompanying figure in the description of the figure, which is intended to illustrate the invention and is not to be considered limiting. It shows:

• an exemplary scanning electron micrograph of a three-dimensional chemically inert and electrically conductive carbon material,
• an exemplary schematic representation of the porous, electrically conductive three-dimensional network manufacturing process according to the invention,
• exemplary scanning electron micrographs of a) a three-dimensionally formed chemically inert and electrically conductive material made of carbon, b) a porous, three-dimensional electrically conductive network with a three-dimensionally formed chemically inert and electrically conductive material made of carbon and with zeolite as adsorbent, c) an enlarged section of and in d) an exemplary thermographic image of a porous, three-dimensional electrically conductive network according to the invention,
• an exemplary scanning electron micrograph of a section of a porous, three-dimensional electrically conductive network with a three-dimensionally formed chemically inert and electrically conductive material made of carbon and with a metal-organic framework structure as adsorbent,
• an exemplary photographic representation of a porous, three-dimensional electrically conductive network according to the invention with a three-dimensionally formed chemically inert and electrically conductive material made of carbon,
• an exemplary schematic representation of the use of a porous, three-dimensional electrically conductive network according to the invention as a temperature swing adsorber and
• exemplary scanning electron micrographs of the porous, three-dimensional electrically conductive network with a three-dimensionally formed chemically inert and electrically conductive material made of carbon and with a metal-organic framework (MOF) as adsorbent with a) CAU-10 H, b) MOF 303 and c) MOF 801 as metal-organic framework.

An example scanning electron micrograph of a three-dimensional, chemically inert and electrically conductive carbon material 2. The individual carbon arms have a diameter of approximately 1-5 µm, and the pores between the carbon arms are between 50 and 100 µm in size. The micrograph demonstrates the high connectivity of the carbon arms, which leads to the macroporous network.

shows an exemplary schematic representation of the porous, electrically conductive three-dimensional network manufacturing process according to the invention. In An adsorbent 3 and optionally carbon nanotubes 5 are added to a solution of, in this example, water and alcohol as the dispersion medium 4. Subsequently, the micro- and/or nanoparticles of the adsorbent 3 are dispersed and/or suspended in the dispersion medium 4, so that a dispersion and/or suspension 6 is formed. One possible method is the use of ultrasound. ) a three-dimensional chemically inert and electrically conductive material 2 is mixed with the dispersion and/or suspension 6 of infiltrated. In ) the drying of the infiltrated three-dimensionally formed chemically inert and electrically conductive material 2 takes place, wherein the suspended and/or dispersed adsorbent material 3 is deposited on the infiltrated three-dimensionally formed chemically inert and electrically conductive material 2 and thus forms a coating, so that the porous, electrically conductive three-dimensional network 1 according to the invention is formed.

The three-dimensionally formed chemically inert and electrically conductive material 2 can preferably be made of carbon and can be loaded on the surface with micro- or nanoparticles of any adsorbents 4. For example, The material class of zeolites, which is already used on an industrial scale, can be used. The conductive carbon nanotubes 5 that may be used serve to fix the particles and entangle them with the surface.

In exemplary scanning electron micrographs of a) a three-dimensionally formed chemically inert and electrically conductive material 2 made of carbon, b) a porous three-dimensional electrically conductive network with a three-dimensionally formed chemically inert and electrically conductive material 2 made of carbon and with zeolite as adsorbent 3, c) an enlarged section of ) and in d) an exemplary thermographic image of a porous, three-dimensional electrically conductive network 2 according to the invention in which the different temperature zones present when voltage is applied can be seen.

In The three-dimensional chemically inert and electrically conductive material 2 was coated with zeolite 13X particles with a size of approximately 2 µm.

In ) is an enlarged image of a single coated carbon arm from The particles are tightly packed here. The smaller the particles, the better the individual carbon arms can be coated.

In ) is the three-dimensional, chemically inert and electrically conductive material 2, here made of carbon, of the porous, electrically conductive three-dimensional network 1 according to the invention. It is a material with a volume of 20 mm x 20 mm x 5 mm, which is contacted by the flat sides. By applying power, the material can be heated from the inside. The temperature distribution is very uniform and limited at most by the heat dissipation at the contacts.

In addition, an exemplary scanning electron micrograph of a section of a porous three-dimensional electrically conductive network 1 with a three-dimensionally formed chemically inert and electrically conductive material 2 made of carbon and with a metal-organic framework structure as adsorbent 3.

As shown here, in addition to zeolites, other adsorbents 3 can also be decorated on the carbon arms. The image shows a porous salt of the CAU-55 type. These particles are significantly smaller and can therefore adhere much more closely to the carbon arms present here. This adsorbent 3 is carbon with a metal-organic framework structure.

shows an exemplary photographic representation of a porous three-dimensional electrically conductive network 1 according to the invention with a three-dimensionally formed chemically inert and electrically conductive material 2 made of carbon and the adsorbent zeolite 13X.

In an exemplary schematic representation of the use of a porous three-dimensional electrically conductive network 1 according to the invention as a temperature swing adsorber is shown.

A gas mixture A+B passes through a valve into a left and right reaction chamber 8 of a reactor filled with the porous, three-dimensional, electrically conductive network 1 according to the invention. A voltage source is connected to each reaction chamber 8 in an electrical circuit 7. The electrical circuit 7 at the left reaction chamber 81 is open. No voltage is applied. Adsorption takes place in the left reaction chamber 81 filled with the porous, three-dimensional, electrically conductive network 1. The electrical circuit 7 at the right reaction chamber is closed. Voltage is applied, and the porous, three-dimensional, electrically conductive network 1 is heated from the inside out. Desorption takes place in the right reaction chamber 82 filled with the porous, three-dimensional, electrically conductive network 1.

During adsorption, the adsorbents 3 absorb the preferred gas A due to their large and accessible surface and the non-preferred gas B is enriched in the gas phase.

By switching valves, the reaction chamber can be separated from the gas mixture A+B.

During desorption, the gas A stored therein is desorbed by heating the adsorbents 3, which leads to the regeneration of the adsorbent 3 and thus of the porous, three-dimensional electrically conductive network 1 according to the invention.

shows exemplary scanning electron micrographs of the porous, three-dimensional electrically conductive network 1 with a three-dimensionally formed chemically inert and electrically conductive material 2 made of carbon and with a metal-organic framework (MOF) as adsorbent 3 with a) CAU-10 H, b) MOF 303 and c) MOF 801 as metal-organic framework.

The porous, three-dimensional electrically conductive networks 1 comprise a three-dimensionally formed chemically inert and electrically conductive material 2 made of carbon and are covered with adsorbent crystallites 3.

The figures show that the metal-organic framework particles densely cover the surface of carbon sponge 2, while leaving a large amount of free space between the carbon arms. This arrangement is very advantageous because energy transfer between adsorbent 3 and the carbon framework can occur directly, without heating additional space or relying on the poor thermal conductivity of adsorbent 3.

In addition, the free space of the network allows for faster diffusion of air through the material and maximizes the exposed surface of the adsorbents 3.

In The MOF crystallites appear to agglomerate into larger particles with diameters of up to 5 µm. This leads to a slightly reduced surface contact compared to the networks 1 in the ). However, since the individual particles are evenly distributed on the surface of the carbon sponge 2, the macropores do not become clogged.

The adsorbent 3 in MOF-303 exhibits the densest coverage of the carbon arms, leaving almost no exposed surface, thus ensuring good thermal contact. Furthermore, the MOF-303 particles are located very close to the carbon arms, maximizing the free space for diffusion. The enlarged section shows the close contact of the MOF-303 crystallites with the carbon arms.

In ), the crystallites of adsorbent 3 MOF-801 adhere closely to the surface of carbon sponge 2 without blocking the macropores, although some agglomeration of the MOF particles is visible.

• Nachfolgend erfolgt die Beschreibung der Erfindung anhand eines konkreten Ausführungsbeispiels unter Hinzunahme der zuvor erläuterten Abbildungen:
  • Das poröse elektrisch leitfähige dreidimensionale Netzwerk-Herstellungsverfahren wurde beispielhaft durchgeführt zur Herstellung von den porösen elektrisch leitfähigen dreidimensionalen Netzwerken gemäß .

Further example:

• The invention is described below using a specific embodiment with reference to the previously explained figures:
  • The porous electrically conductive three-dimensional network manufacturing process was carried out as an example to produce the porous electrically conductive three-dimensional networks according to .

Carbon sponges were produced by heating Basotect melamine foam to a temperature of 1000 °C for 90 minutes in a nitrogen atmosphere. The temperature was maintained for 20 minutes to completely carbonize the polymer. The sponges were thoroughly washed with deionized water before further use.

The carbon sponges and the metal-organic frameworks were combined into a composite material by liquid infiltration. For this purpose, 100 mg of MOF particles were suspended in 20 mL of water together with 10 wt.% of the polysiloxane binder SILRES® MP 50 E by ultrasonic treatment for 30 minutes. The dispersion was then dropped onto the carbon substrate, which was heated to 50 °C to accelerate solvent evaporation. This procedure was repeated until a loading of approximately 70 wt.% was reached, ensuring that the free volume of the substrate was not exceeded during infiltration to prevent the dispersion from drying out on the surface. The weight percentages of the MOFs in the final inventive networks according to were 70% for CAU-10-H, 71% for MOF-303 and 74% for MOF-801.

The exemplary porous, electrically conductive three-dimensional networks according to the invention produced in this exemplary embodiment can be used in particular for water extraction from gaseous water, water vapor, or moisture, since the water sorption isotherms of the exemplary porous, electrically conductive three-dimensional networks according to the invention are almost identical to those of the MOF powders, and these MOF powders are also very well suited for water enrichment due to their sorption behavior. However, this represents only one application among many.

Due to the porous structure of the network according to the invention and the resulting increased surface area compared to monoliths in particular, it is possible to reduce the times required for adsorption and thus to accelerate the cycle times.

In addition to the sorption performance, the thermal desorption behavior is also an important parameter for the regeneration of the network according to the invention.

The percolation property of the three-dimensional chemically inert and electrically conductive material, in particular carbon, enables even and rapid heating and cooling of the materials.

For example, in the The preferably desired regeneration temperature of approximately or at least T=70°C for the networks produced according to the invention can be achieved, depending on the design of the network, for example, in less than two minutes at a heating power of 0.9 W (6 V and 0.15 A). Cooling takes place within a similar timeframe, so that the network reaches a temperature of T<30°C, for example, in less than three minutes.

By skillfully selecting the adsorbents, it is possible to adapt the porous, electrically conductive three-dimensional network according to the invention, in particular for use as a temperature swing adsorber and/or as a filter, to the respective requirements in the individual case.

There are a wide variety of adsorbents that can be used. For example, adsorbents can be used for the separation of sulfur dioxide, nitrogen oxides, or volatile organic compounds, i.e., pollutants such as acetone, hydrocarbons, formaldehyde, and others. The separation of propene/propane, for example, represents a large-scale, industrially important example.

A very interesting application possibility can be seen in the formation of a carbon dioxide-binding porous, electrically conductive three-dimensional network, wherein this carbon dioxide-binding porous, electrically conductive three-dimensional network is designed as a temperature swing adsorber and wherein this has a three-dimensionally formed, chemically inert and electrically conductive material and a carbon dioxide-binding adsorbent, and wherein the three-dimensionally formed, chemically inert and electrically conductive material has at least one sectionally or completely coating with the carbon dioxide-binding adsorbent and the three-dimensionally formed, chemically inert and electrically conductive material is formed from carbon and the carbon dioxide-binding adsorbent consists of a metal-organic framework structure and/or a zeolite and/or a silica gel and/or a porous carbon and/or porous silica and/or porous polymers and/or covalent organic frameworks and/or nanoparticles with high specific surface areas and/or porous salts.

List of reference symbols:

1

Porous electrically heatable three-dimensional network

2

three-dimensional chemically inert and electrically conductive material, carbon sponge

3

Adsorbent, adsorbents

4

Dispersion medium

5

Carbon nanotubes

6

Dispersion and/or suspension of 3+4 or 3+4+5

7

Circuit with voltage source

8

Reaction chamber

A+B

Gas mixture with the gas components A+B

A

Gas component A

B

Gas component B

Claims (12)

Porous electrically conductive three-dimensional network (1), characterized in that the porous electrically conductive three-dimensional network (1) is formed from a three-dimensionally formed chemically inert and electrically conductive material (2), wherein the three-dimensionally formed chemically inert and electrically conductive material (2) has at least one partial or complete coating with an adsorbent (3). Network (1) to Claim 1 characterized in that the network (1) is designed as a temperature swing adsorber. Network (1) to Claim 1 or2, characterized in that - the three-dimensionally formed chemically inert and electrically conductive material (2) is formed from carbon and/or - the adsorbent (3) is formed from a metal-organic framework structure and/or a zeolite and/or a silica gel and/or a porous carbon and/or porous silica and/or porous polymers and/or covalent organic frameworks and/or nanoparticles with high specific surface areas and/or porous salts. Network (1) to Claim 3 , characterized in that the individual carbon arms in the network have a diameter of 0.5 to 8 µm and/or 1 to 5 µm and the Pores between the individual carbon arms are between 30 and 120 µm and/or 50 and 100 µm in size. Network (1) according to one of the preceding claims, characterized in that the network (1) has a porosity of at least 50% or more than 80% and/or the adsorbent has a nanoporosity. Network (1) according to one of the preceding claims, characterized in that the network (1) additionally comprises conductive carbon nanotubes (5). A method for producing a porous, electrically conductive three-dimensional network (1) comprising at least the following steps: 1. Suspending and/or dispersing adsorbent material (3) in a dispersion medium (4); 2. Infiltrating a three-dimensional, chemically inert and electrically conductive material (2) with the dispersion medium (4) from step 1; 3. Drying the infiltrated, three-dimensional, chemically inert and electrically conductive material (2) from step 2, wherein the adsorbent material (3) suspended and/or dispersed in step 1 is deposited on the infiltrated, three-dimensional, chemically inert and electrically conductive material (2), thus forming a partial or complete coating. Manufacturing process according to Claim 7 , characterized in that - the drying is carried out for a period of 20 to 28 hours and/or 24 hours and/or - the dispersion medium (4) in step 1 is designed as a solution of water and/or alcohol and/or - in step 1, in addition to the adsorbent material (3), conductive carbon nanotubes (5) are introduced into the dispersion medium (4). A method for producing a porous, electrically conductive three-dimensional network (1), comprising at least the step of: Synthesizing adsorbent (3) as a partial or complete coating on a three-dimensionally formed, chemically inert and electrically conductive material (2) to form a porous, electrically conductive three-dimensional network (1). Porous electrically conductive three-dimensional network (1) use comprising the following steps: - feeding a gas mixture with different gas components into a temperature swing adsorber with a porous electrically conductive three-dimensional network (1) according to one of the Claims 1 until 5 - Adjustable alternating adsorption and desorption of gas components in the temperature swing adsorber, wherein the adsorption is carried out at a lower temperature and the desorption is carried out by applying a power to the chemically inert and electrically conductive material (2) of the porous electrically conductive three-dimensional network (1) and thereby heating the network (1) from the inside out to a higher temperature; - Discharge of gas components from the temperature swing adsorber. Use according to Claim 10 , characterized in that - during the desorption process the adsorbent (3) is flushed with a flushing gas and/or - the power is applied in the form of power pulses and/or - the adjustable alternating adsorption and desorption in the temperature swing adsorber is carried out continuously in continuous operation or in batch operation. Use of the porous electrically conductive three-dimensional network (1) according to one of the Claims 1 until 6 - as a temperature swing adsorber and/or - for filtering carbon dioxide from the breathing air and/or - for filtering carbon dioxide from the ambient air and/or - for filtering carbon dioxide from a gas mixture and/or air stream and/or - for filtering gases and/or - for cleaning gases and/or - for separating gases and/or - for drying air in analytical devices and/or - for drying air in consumer products and/or - for water enrichment and/or water extraction in water-scarce areas.