Use of a mycelium of a mycelium-forming fungal culture, direct-air capture system, and method for producing a direct-air capture system

Abstract

The present invention relates to the use of a mycelium of a mycelium-forming fungal culture as the sorbant in a CO2 separation device, in particular a direct-air capture system.

Description

[0001] Description

[0002] title -forming fungal culture, direct air a direct air

[0003] State of the art

[0004] The present invention relates to the use of a mycelium of a mycelium-forming fungal culture and a CO2 separation device, in particular a direct air capture system (hereinafter DAC system), which comprises a mycelium of a mycelium-forming fungal culture and a method for producing a CO2 separation device, in particular a DAC system.

[0005] One of the greenhouse gases responsible for global warming is carbon dioxide (CO2). There is therefore a worldwide effort to isolate CO2 from the air and then either convert it into other products through synthesis or to store it permanently in liquid or solid form, for example in underground storage facilities. There are systems with which CO2 can be removed and isolated from the air on a large scale. Such systems are called direct air capture systems (DAC systems) and consist of an adsorption or desorption chamber (ADC) into which ambient air is introduced, from which CO2 is selectively chemically or physically bound to a liquid or solid sorbent (also known as an adsorbent), thus removing it from the air. When the adsorbed CO2 is needed, it is desorbed from the sorbent by heating and, if necessary, suppression and can then either be stored or reused.

[0006] Conventional sorbents used in DAC systems are synthetic. Examples include activated carbon, cellulose, silica, zeolites, metal-organic frameworks, mixed metal oxides, covalent organic frameworks, or polymer-based ion-exchange resins. All conventional sorbents produced for direct air capture are manufactured in a more or less complex manner and involve multiple process steps, sometimes using organic solvents and synthesized, transported, and utilized / recycled / destroyed at elevated temperatures. This is associated with corresponding costs and also a high carbon dioxide footprint and high instrumentation expenditure.

[0007] Disclosure of the invention

[0008] The use according to the invention and the CO2 capture device according to the invention are characterized by the use of sustainable substances with a low carbon footprint. Furthermore, the substances used according to the invention are biodegradable and require only a few processing steps to be ready for their intended use. Furthermore, disposal and recycling are easily possible.

[0009] According to the invention, the use of a mycelium of a mycelium-forming fungal culture as a sorbent (adsorbent or absorption agent) in a CO2 separation device, in particular a direct air capture system, is disclosed. Mycelium-based materials as biobased materials are already in use in the context of the transition from a linear to a circular economy, for example, as sustainable packaging and as a leather substitute, or in architecture. The present invention goes further and specifically uses a mycelium of a mycelium-forming fungal culture as a CO2 sorbent. This not only uses sustainable products (the mycelium), but also actively reduces the CO2 content of the air (through its functionality as a CO2 sorbent).

[0010] Thus, according to the invention, a CO2 separation device, in particular a DAC system, is also described, which comprises an absorption or desorption chamber (hereinafter: ADK), wherein the ADK comprises at least one sorbent and the sorbent comprises a mycelium of a mycelium-forming fungal culture.

[0011] Unless explicitly stated, all information regarding mycelium applies both to the use according to the invention and to the CO2 separation device according to the invention. The mycelium can be present in various structures, for example as powder, spheres, fibers, filter mats, or a honeycomb structure, in order to generate the lowest possible pressure drop in the CO2 separation device or DAC system. Mycelium is particularly well suited for this purpose because it can grow in a specific shape, e.g., if it is introduced into corresponding negative molds of the mold to be produced (ADK) and grows there until it fills the negative mold. Furthermore, mycelium has a low carbon footprint because it is obtained from natural fungi, usually grows below room temperature, and is also safe to dispose of.

[0012] Particularly suitable mycelia are those that already contain a particularly high number of amine groups, for example, in the form of amino acids with particularly high amine content, since these do not require additional modification to bind CO2. By selecting the fungal organism, the sustainability of the mycelia can be significantly improved. Suitable mycelia and the hyphae that form these mycelia are known, for example, from the following review articles: https: / / www.nature.com / articles / srep41292 and https: / / d0i.0rg / l 0.1016 / j.jece.2023.110396.

[0013] Furthermore, the mycelium used in the invention can be produced without significant technical and energy expenditure, thus protecting the environment and conserving instrumental and energy resources. Processes for modifying the mycelium for more efficient CO2 binding are also known.

[0014] Mycelium that is particularly well modifiable for CCh binding contains one or more of the following compounds: chitins, glucans (oligo- or polysaccharides), amino acids (especially cysteine, arginine, glutamine, histidine, lysine and tryptophan), proteins including glyco- and mannoproteins, tannins, cutin, lignin, lipids, cellulose and hydrophobins.

[0015] Particularly suitable mycelia include those that, due to natural or synthetic gene expression, contain particularly high levels of amine-containing amino acids in their peptides, such as arginine, cysteine, asparagine, glutamine, histidine, lysine, and tryptophan. Cellulose carries OH groups that can be functionalized. Chitin already contains a secondary amine in its structure for CCh adsorption; additional OH groups can be functionalized. Chitosan can be obtained by deacetylation of chitin, where amine groups are then available. Targeted control of the structure can also be achieved through gene expression.

[0016] Also suitable are myceliums formed from fungal species that react upon CO2 adsorption to form calcium carbonate, or promote the formation of calcium carbonate, thus effectively binding CO2, resulting in a net negative CO2 effect. This is known from the field of architecture. This mechanism differs from the basic mechanism with amines disclosed above.

[0017] Fungal species which convert CO2 into calcium carbonate (for example into the modifications calcite or aragonite) and are thus suitable according to the invention are, for example: Basidiomycetes, Ascomycetes, Zygomycetes and Mycoromycota from the Pleurotus, Trametes, Ganoderma and Schizophyllum families, with the following species being mentioned in particular: Ganoderma lucidum, Pleurotus ostreatus, and Schizophyllum commune.

[0018] The use according to the invention and the DAC system according to the invention are thus characterized by the use of sustainable products that are characterized by a low carbon footprint and also serve to isolate CO2 from the air. The carbon footprint is determined according to DIN EN ISO 14067 (Greenhouse gases - Carbon footprint of products - Requirements and guidelines for quantification (ISO 14067:2018); German and English versions EN ISO 14067:2018)) and DIN EN ISO 14040 (Environmental management - Life cycle assessment - Principles and framework (ISO 14040:2006 + Amd 1:2020); German version EN ISO 14040:2006 + A1:2020).

[0019] The subclaims show preferred developments of the invention.

[0020] According to an advantageous development, the mycelium is a composite mycelium material or a pure mycelium material. Pure mycelium materials (hereinafter: RMM) are materials that consist solely of the mycelium and do not contain any substrate or carrier on which the mycelium is located, for example, produced in a fermentation process. Composite mycelium materials (hereinafter: CMM) are materials in which the mycelium has grown on a carrier or substrate.

[0021] If the mycelium is a CMM, the support material is preferably selected from the group consisting of cellulose, (cordierite) monoliths, filter materials, porous metallic or ((bio)polymer) structures, and is especially lignocellulose. The advantage of these support materials is that they are already characterized by a desired shape, density, and porosity, which are selected with regard to application in a DAC system.

[0022] The use of lignocellulose is particularly preferred here. Lignocellulose consists of hemicellulose and lignin. Hemicellulose is a collective term for mixtures of polysaccharides (complex sugars) of varying composition found in plant biomass. The most common monomers (monosaccharides = simple sugars) are pentoses, such as D-xylose and L-arabinose. These sugars all contain hydroxyl (OH) groups. Lignin is a heterogeneous, highly cross-linked macromolecule similar to a phenol-formaldehyde resin. It consists of 3-4 monomers, the composition of which varies depending on the species. It is hydrophobic and, among other things, carries free OH groups. The free OH groups can be used for modification to form CCh binding sites. Lignocellulose can, for example, be obtained from organic waste products, so the sustainability of mycelium produced from it is particularly high.

[0023] The mycelium also preferably contains amine groups. Amine groups are particularly well-suited for reversibly binding CO2 from the air. This significantly improves the functionality with regard to the isolation of CO2 from the air.

[0024] To improve long-term stability, the mycelium is preferably impregnated with an antimicrobial agent. Fungicides, in particular, are used as antimicrobial agents, which can be used individually or in suitable combinations. A combination of CaCl and chitosan can also be used. To improve the CCh adsorption capacity (for the purposes of the invention, this includes both physical adsorption and chemical absorption, as well as a mixture of these two binding mechanisms), the mycelium is advantageously impregnated with at least one CCh sorbent and / or covalently functionalized. Suitable CCh sorbents are known from the prior art. These can be used individually or in any desired mixtures.Examples include: AEATPMS ([N-(2-aminoethyl)-3-aminopropyl]trimethoxysilane), APDES (3-aminopropylmethyldiethoxysilane), linear and branched polyethyleneimine (PEI), polypropyleneimine (PPI), 3-aminopropyltrimethoxysilane (APTMS), triethylenetetramine (TETA), polypropyleneguanidine (PPG), tetraethylenepentamine (TEPA), triethylenetetramine (TETA), diethylenetriamine (DETA), ethylenediamine (EDA), polyglycidylamine (PGA), and polyallylamine (PAA).

[0025] Due to its high porosity, which is advantageous for CCh adsorption and desorption, the mycelium preferably has a nonwoven structure. Suitable nonwoven structures can be produced, for example, through fermentation processes.

[0026] Traditionally, CO2 is removed from the sorbent by heating and applying negative pressure. This is an energy-intensive process. The energy requirement for CO2 desorption can be advantageously reduced by incorporating photoactive groups into the mycelium, which enable CO2 desorption from the mycelium under the influence of light. Suitable photoreactive groups include: azobenzene, diarylethene and its derivatives, spiropyrans, hemothioindigo compounds, 1,2-dithienylethene and its derivatives.

[0027] To further inhibit germination and thus further improve the long-term stability of the mycelium, it is advantageous for the mycelium to be provided with a hydrophobic coating. The coating is not limited in its specific form. Waxes, including plant-based waxes such as coconut oil or carnauba wax, or other natural waxes such as beeswax, are particularly suitable, as these can further improve the sustainability of the mycelium.

[0028] Furthermore, the invention also describes a method for producing a CO2 separation device, in particular a DAC system. The CO2 separation device or DAC system comprises an adsorption or desorption chamber, and the method comprises a step of growing a mycelium-forming fungal culture as a sorbent in a negative mold of the adsorption or desorption chamber, and a step of introducing the formed mycelium into the adsorption or desorption chamber.

[0029] Any suitable mold that is comparable to the ADK in terms of dimensions, shape, and design is suitable as a negative mold. A mycelium-forming fungal culture (this can be a single fungal culture or a mixture of two or more fungal cultures) is introduced into the negative mold. Instead, the negative mold is inoculated with corresponding fungal spores. The negative mold can, if necessary, contain a nutrient substrate (e.g., a sugar solution) or a corresponding substrate that forms a suitable breeding ground, such as lignocellulose-containing materials from waste management, such as bamboo scraps, scraps from wood production, scraps from shredded Euro pallets, and the like. The fungus grows in the form of the negative mold due to the sugar contained in the nutrient substrate or nutrient medium. The growth process is interrupted by heating or sterilizing. The mycelium can be removed from the negative mold and inserted into the ADK.

[0030] The process is characterized by a few process steps, each requiring low instrumental and energetic expenditure, while using a high proportion of natural substances, so that the process can be classified as environmentally friendly and leaving a low CCh footprint.

[0031] In addition, the method according to the invention has the advantage that the fungal spores can be easily transported without high volumetric expenditure, so that the mycelium can also be produced on site, in particular since this requires little instrumental expenditure.

[0032] The advantages, beneficial effects and further links of the use of the CO2 separation device, in particular the DAC system, and the process are mutually applicable.

[0033] The mycelium can be used as is, provided it possesses CO2 functionality. However, the mycelium can advantageously be modified using mechanical, physical, chemical, or genetic engineering methods to improve the CCh functionality and thus increase its efficiency as a CCh sorbent, or to introduce additional functionalities into the mycelium. These methods can be performed individually or in combination to improve the CCh adsorption capacity.

[0034] Advantageously, amine functionalization of the mycelium is carried out to increase the binding capacity for CO2.

[0035] In addition, it may be advantageous to impregnate the mycelium with at least one CO2 sorbent, and in particular with carbonates, in order to improve the CO2 adsorption capacity.

[0036] To improve long-term stability, it may be advantageous to impregnate the mycelium with an antimicrobial agent, in particular with at least one fungicide and / or a combination of CaCl and chitosan.

[0037] Applying a hydrophobic coating can also be beneficial, as it allows water to drain away, which can act as a carrier of germs. Particularly suitable hydrophobic agents include coconut oil, carnauba wax, or beeswax, or combinations thereof.

[0038] Particularly good amine functionalization mechanisms of mycelium are presented below. The respective steps can be used alternatively or additively.

[0039] Amine functionalization of the mycelium by impregnation with appropriate amine-containing solutions: This is particularly suitable for PEI-containing adsorbents.

[0040] Covalent amine functionalization of the mycelium by functionalizing existing surface OH groups with appropriate amine-containing reagents in a silanization reaction or in a radical polymerization. The radical polymerization corresponds to a so-called "grafting" process, which results in grafted polymers. Amine functionalization of the mycelium by deacetylation of chitin to produce chitosan with primary amine groups and OH groups for further amine functionalization.

[0041] Amine functionalization of the mycelium through gene expression: By using genetically modified mycelium-forming organisms, it is possible to create mycelium networks in whose protein structure amino acids are expressed that contain a particularly high number of functional groups that are suitable for binding CO2, such as amine groups for the direct sorption of CO2 or OH groups for simultaneous or subsequent functionalization with amine-bearing agents. Functionalization, for example via click chemistry or coupling with glutaraldehyde, for example, is also possible for this purpose. Furthermore, by using synthetic biology methods such as CRISPR-Cas systems, it is possible to control gene expression using artificial transcription factors, so that hyphae are expressed with amino acids that are particularly suitable for CO2 sorption, such as arginine orin sequences that have a chemical structure or porosity particularly suitable for CO2 sorption, e.g. determined in simulation calculations.

[0042] A specific functionalization process of a mycelium is described below, but the invention is not limited thereto.

[0043] As stated below, how a chemical covalent attachment of amine groups to the mycelium surface is obtained by way of example as follows: For example, the amine functionalization of an OH group with APDES or AEATPMS is achieved by: 1. Hydrolyzing the silane, 2. Forming a chemical bond between the silane and the surface OH group of the substrate.

[0044] For example, APDES can be bound to OH groups of chitosan, increasing the amine density of the polysaccharide chain by a factor of two to three. The amine-amine distance should be close to 0.3 nm for particularly effective CO2 binding. This means that per m2 internal sorbent surface at least 18 * 10' 6 mol of covalently bound amines should be available. The amine density should be at least 18 * 10' 6 mol amine / m 2 surface and preferably closer to 180 * 10' 6 mol amine / m 2 lay.

[0045] The amount of carbonates, hydrogen carbonates or oxides (KHO) should be at least 18 * 10' 6 mol KHO / m 2 surface and preferably at 180 * 10' 6 mol KHO / m 2 lay.

[0046] The internal BET surface area of ​​the mycelium should be at least 10 m 2 / g and preferably closer to 100 m 2 / g.

[0047] To generate an optimal sorbent 3D structure or amine packing density, the functionalized mycelium is annealed / processed, for example, in a CO2 atmosphere.

[0048] To suppress urea formation during dry regeneration of the sorbent, it is preferably impregnated with, for example, nitrogen-bearing heterocycles such as piperazine in a weight ratio of at least 1:1 piperazine / sorbent and preferably 5:1.

[0049] The functionalization process creates a homogeneous coverage of the inner sorbent surface with CO2-binding functionalities and avoids composition gradients or cover layers.

Claims

Claims 1 . Use of a mycelium of a mycelium-forming fungal culture as a sorbent in a CO2 separation device, in particular a direct air capture system.

2. CO2 separation device comprising an absorption or desorption chamber, wherein the absorption or desorption chamber comprises at least one sorbent and the sorbent comprises a mycelium of a mycelium-forming fungal culture.

3. Use and CO2 separation device according to claim 1 or 2, wherein the mycelium is a composite mycelium material or a pure mycelium material.

4. Use and CO2 separation device according to one of the preceding claims, wherein a carrier material of the composite mycelium material is selected from the group consisting of cellulose, (cordierite) monolith, filter materials, porous metallic or ((bio)polymer) structures and in particular lignocellulose.

5. Use and CO2 separation device according to any one of the preceding claims, wherein the mycelium comprises amine groups.

6. Use and CO2 separation device according to one of the preceding claims, wherein the mycelium is impregnated with an antimicrobial agent, in particular with at least one fungicide and / or a combination of CaCl and chitosan.

7. Use and CO2 separation device according to one of the preceding claims, wherein the mycelium is impregnated and / or covalently functionalized with at least one CO2 sorbent.

8. Use and CO2 separation device according to one of the preceding claims, wherein the mycelium has a nonwoven structure.

9. Use and CO2 separation device according to one of the preceding claims, wherein the mycelium comprises photoactive groups which enable desorption of CO2 from the mycelium under the influence of light.

10. Use and CO2 separation device according to one of the preceding claims, wherein the mycelium comprises a hydrophobic coating, in particular comprising coconut oil, carnauba wax or beeswax. 11 . Method for producing a CO2 separation device, in particular a direct air capture system comprising an adsorption or Desorption chamber, comprising a step of growing a mycelium-forming fungal culture as a sorbent in a negative mold of the adsorption or desorption chamber and a step of introducing the formed mycelium into the adsorption or desorption chamber.

12. The method according to claim 11, comprising at least one further step selected from: Amine functionalization of the mycelium Impregnating the mycelium with at least one CCh sorbent, especially with carbonates Impregnating the mycelium with an antimicrobial agent, in particular with at least one fungicide and / or a combination of CaCl and chitosan Applying a hydrophobic coating, in particular comprising coconut oil, carnauba wax or beeswax.

13. The method according to claim 12, wherein the amine functionalization of the mycelium comprises at least one of the following steps: amine functionalization of the mycelium by impregnation with appropriate amine-containing solutions, covalent amine functionalization of the mycelium by functionalizing existing surface OH groups with appropriate amine-containing reagents in a silanization reaction or in a radical polymerization Amine functionalization of the mycelium by deacetylation of chitin to produce chitosan with primary amine groups and OH groups for further amine functionalization Amine functionalization of the mycelium by gene expression.

14. The method according to any one of claims 11 to 13, wherein the mycelium-forming fungal culture is grown on a carrier material, wherein the carrier material is in particular selected from the group consisting of Celluloses, (cordierite) monoliths, filter materials, porous metallic or ((bio)polymer) structures and in particular lignocellulose.

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