Bio-based carbon foam

Abstract

The present invention relates to a bio-based carbon foam, a method for manufacturing the same, and uses thereof. The method includes foaming a slurry of cellulose fibers to obtain a cellulose fiber foam, adding a biomass component to the foam, and carbonizing the biomass-cellulose fiber foam.

Description

Technical Field

[0001] The present invention relates to bio-based carbon foams, methods for their manufacture, and uses thereof. Background Art

[0002] In our daily life, macroporous and microporous materials are used in various forms and compositions. Carbon foams are porous materials formed by a web of carbon atoms and can have an extremely high specific surface area and high adsorption capacity. These materials are expected to contribute to modern technologies, for example, as electrodes for electrochemical devices, adsorbents for macromolecules, thermal insulators for aerospace product components, and other applications that require lightweight, strong, and highly resistant materials.

[0003] Known techniques for preparing carbon foams involve mixing different precursors. Prior art precursors typically are based on fossil-based chemicals such as pitch, isocyanates, polyols, crosslinkers, chain extenders, and surfactants, as well as inorganic compounds such as catalysts. Each precursor requires different handling during the foaming process.

[0004] A conventional method for preparing carbon foams is the template approach, which involves using commercially available open-cell polyurethane foam as a template. The polyurethane foam is impregnated with a slurry (such as phenolic resin or pitch), and then cured and carbonized under an inert gas to form a carbon foam structure. This method is simple and can be easily scaled up, but both the template and the precursor are fossil-based. Another method is direct foaming, which involves generating gas bubbles within a liquid slurry containing a precursor and a foaming agent. During the first step of the foaming process, gas bubbles (typically CO2) are generated due to a chemical reaction of the foaming agent. When a stable porous network has been formed, it is dried and carbonized under an inert gas. The direct foaming approach uses a variety of fossil-based precursors. A third method is indirect foaming, which involves preparing a precursor slurry and then purging the precursor slurry with nitrogen in an adiabatic reactor under a pressurized atmosphere. Then, the obtained foam is dried and carbonized. This process is complex and expensive at large scales.

[0005] This creates a high motivation to replace fossil-based chemicals with more sustainable alternatives, such as using renewable raw material resources, and this is for environmental and human health reasons. As the most abundant renewable natural polymer on Earth, and due to the availability of methods for its large-scale preparation on an industrial scale, cellulose has special potential. Cellulose-based porous materials are typically produced by using an aqueous slurry of cellulose fibers as the starting material. The water should be removed during the drying of the wet porous cellulose material without causing collapse or shrinkage. Recently, cellulose foams have been prepared from only biomass precursors, biofoaming agents, water, and air, as described in WO2020 / 011587. WO 2020 / 049226 discloses a porous moldable material prepared from a lignin-containing fraction obtained from lignocellulosic materials. Patent publication US3894878 discloses a porous moldable material prepared from an aqueous solution of lignin. However, there is still a need for an environmentally friendly and inexpensive method for preparing carbon foams. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 The steps for preparing a lignin-cellulose-based carbon foam are shown: (a) foaming a cellulose slurry to provide a cellulose fiber foam, (b) adding lignin (●) to the cellulose fiber foam (---), and (c) carbonizing the dried lignin-cellulose foam (in Figure 1 (c), ○ represents carbonized lignin, and -·- represents carbonized cellulose fibers). DETAILED DESCRIPTION

[0007] The object of the present disclosure is to provide a carbon foam made from bio-based materials.

[0008] In a first aspect, the present invention relates to a bio-based carbon foam, which is characterized by having a density of 10 to 80 kg / m 3 、or 10 to 60 kg / m 3 and an average pore size of 0.5 - 10 mm, or 1 to 10 mm.

[0009] The carbon foam according to the present invention has the advantages of being lightweight, non-flammable, chemical-resistant, high-temperature-resistant, permeable to gases and liquids, and absorbent of sound and radiation.

[0010] In a second aspect, the present invention relates to a method for preparing a bio-based carbon foam, the method comprising:

[0011] a) suspending cellulose fibers in a liquid medium to obtain a cellulose slurry;

[0012] b) foaming the slurry to obtain a cellulose fiber foam;

[0013] c) Adding a biomass component to the cellulose fiber foam to obtain a biomass-cellulose fiber foam, wherein the biomass component is selected from lignin and lignocellulosic materials; and

[0014] d) Carbonizing the biomass-cellulose fiber foam to obtain a bio-based carbon foam.

[0015] The cellulose pulp in step (a) can be prepared by soaking dry cellulose fibers in a liquid medium and then mixing using standard cellulose disintegration equipment. The liquid medium for suspending the cellulose fibers can be an aqueous solution or water, preferably water. The suspension of cellulose fibers and the biomass component in the liquid medium can be prepared at a temperature of 10 to 50 °C, 15 to 50 °C, or 20 to 50 °C. The cellulose pulp can have a concentration of 0.1-40 wt% cellulose, or 0.1-5 wt%, or 0.2-2 wt% based on the total weight of cellulose and the liquid medium in the pulp.

[0016] An additive can also be added to the cellulose pulp. The additive can be suspended in the liquid medium before adding the cellulose fibers, suspended together with the cellulose fibers, or added to the cellulose pulp after the cellulose fibers have been suspended. The additive can be a foaming agent, a thickening agent, or a plasticizer, preferably the additive is a bio-based additive. Examples of bio-based foaming agents are proteins such as gluten, casein, hydrophobin, and gelatin. The additive can be added to the cellulose pulp as a powder or as a blend to obtain a pulp of cellulose fibers and the additive, wherein the total solid content is 0.1-40 wt%, or 0.1-5 wt%, or 0.2-2 wt% based on the total weight of the pulp. The ratio of cellulose fibers to the additive can affect the degree of flocculation and separation of the cellulose fibers.

[0017] The foaming of the cellulose slurry can be carried out by introducing gas into the slurry. The gas can be introduced into the slurry by whipping or vigorous stirring, by adding a foaming agent, by pressurizing the slurry with gas, or by directly introducing gas (such as bubbling gas through the slurry). The gas introduced into the slurry can be selected from carbon dioxide, nitrogen, inert gas, and air, or a mixture thereof. Preferably, the gas is air. Air can be introduced by whipping or vigorous stirring, which is an inexpensive and direct method for generating foam. The foaming can be carried out at ambient temperature, or at a temperature of 5 to 100 °C, 10 to 100 °C, 10 to 80 °C, 10 to 60 °C, 10 to 40 °C, 15 to 60 °C, or 15 to 40 °C. The foaming can be carried out at ambient pressure. The foaming can also be carried out by applying high pressure and then releasing the pressure, such as by applying a pressure in the range of 102 - 500 kPa, or 102 - 300 kPa. When foaming, the volume of the slurry can increase by several hundred percent, such as greater than 200%, or even up to 1000% or more, depending on the amount of the dry weight of the cellulose. The advantage of the method according to the present invention is that only moderate heating, or even no heating, is required to obtain the cellulose fiber foam.

[0018] The biomass component can be added to the cellulose fiber foam in the form of dry particles (such as powder) or as particles dispersed in a liquid medium (such as an aqueous solvent or water), and as a biomass dispersion to the cellulose fiber foam. The biomass component is selected from lignin; and lignocellulosic materials, such as wood particles, pulp and wood fibers (for example, dry lignocellulosic fibers), wood powder, shredded cellulose pulp, sawdust, and lignin powder; and different combinations thereof. The biomass component is preferably lignin. The lignin can be added to the foam containing cellulose fibers in the form of dry particles (such as powder) or as particles suspended in a liquid medium (such as an aqueous solvent or water). The average particle size can be in the range of 0.1 μm to 20 μm, 0.1 μm to 10 μm, 0.1 μm to 5 μm, or 0.1 to 1 μm. The weight ratio of the biomass component to the cellulose fiber is 3:1 to 1:3 by dry material, preferably 2:1 to 1:2, and more preferably 1:1.

[0019] In one embodiment, the cellulose fiber foam is dried by removing the liquid medium before adding the biomass component. The cellulose fiber foam can be cast into a desired shape, such as a plate, a 3D structure, a thin layer, etc., before it is dried. The cellulose fiber foam can be dried until it contains less than 15 wt%, or less than 10 wt%, of the liquid medium based on the total weight of the cellulose fiber foam. In some embodiments, the first step of removing the liquid medium can be draining, which can be facilitated by gravity or by vacuum. The drying of the cellulose fiber foam can be carried out by various methods. Depending on the liquid medium that has been used, the liquid medium can be evaporated as follows: by convective drying or by radiation at room temperature (such as 15 °C to 30 °C, or 15 °C to 25 °C); or by subjecting the cellulose fiber foam to an elevated temperature, such as a temperature above 20 °C, for example 25 to 130 °C, 30 to 100 °C, 30 to 80 °C, or 50 to 80 °C. Lower and higher temperatures can also be used depending on the stability of the cellulose fiber foam. Only moderate heating or even no heating is required to obtain the foam containing cellulose fibers, but elevated temperatures will shorten the time used to dry the foam. The residence time for drying the cellulose fiber foam can be 4 to 60 hours, or 4 to 48 hours, or 4 to 24 hours, or 4 to 12 hours, but can be adjusted depending on the drying method used. Different ovens can be used, such as baking ovens, curing ovens, drying ovens, vacuum drying ovens, or industrial batch and continuous ovens. Heating the cellulose fiber foam from its interior using microwaves or a combination of microwaves and heat flow can further accelerate the drying time. However, too high a temperature can make the cellulose fiber foam uneven or even damage the foam, such as causing delamination or collapse of the structure. The drying temperature can also be changed during drying, for example, a lower initial temperature can be used and the temperature can be increased over time. The liquid medium can also be removed by solvent exchange, for example, water can be removed by solvent exchange with ethanol.

[0020] The dried cellulose fiber foam can be impregnated with the biomass component in the form of a biomass dispersion. Impregnating the cellulose fiber foam with the biomass dispersion may take from 1 hour up to 16 hours. The impregnation can be enhanced by suction to ensure that the biomass dispersion reaches the deepest pores of the cellulose fiber foam. After impregnation, the obtained biomass-cellulose fiber foam can be dried to reduce the content of the liquid medium, such as reducing it to less than 15 wt% or less than 10 wt% of the liquid medium based on the total weight of the biomass-cellulose fiber foam before carbonization.

[0021] In another embodiment of the method according to the present invention, before drying the foam, the biomass component is added to the cellulose fiber foam as a powder. The powder may have an average particle size in the range of 0.1 μm to 20 μm, 0.1 to 10 μm, 0.1 μm to 5 μm, or 0.1 to 1 μm. By adding the powder to the foam containing cellulose fibers at a low shear rate over a long period of time, collapse of the foam bubbles can be prevented and the bubble size can remain substantially unchanged. Adding the biomass component to the foam containing cellulose fibers before drying allows the biomass-cellulose fiber foam to be cast into a desired shape, such as a plate, a 3D structure, a thin layer, etc. before its drying and carbonization.

[0022] In any of the embodiments disclosed herein, the biomass-cellulose fiber foam may be dried until it contains less than 15 wt% or less than 10 wt% of a liquid medium, based on the total weight of the biomass-cellulose fiber foam. Drying of the biomass-cellulose fiber foam may be carried out by various methods, such as by draining, convective drying, or by radiation, or a combination of these. Drying may be carried out at room temperature (such as 15 to 30 °C, or 15 to 25 °C); or by subjecting the biomass-cellulose fiber foam to an elevated temperature, such as a temperature above 20 °C, for example 25 °C to 130 °C, 30 °C to 100 °C, 30 °C to 80 °C, or 50 °C to 80 °C. Only moderate heating or even no heating is required to obtain the foam containing biomass-cellulose fibers, but elevated temperatures will shorten the time used to dry the foam. Draining may be facilitated by gravity or vacuum. The residence time for drying the biomass-cellulose fiber foam may be 4 to 60 hours, or 4 to 48 hours, or 4 to 24 hours, or 4 to 12 hours, but may be adjusted depending on the drying method used. Different ovens may be used, such as baking ovens, curing ovens, drying ovens, vacuum drying ovens, or industrial batch and continuous ovens. Heating the biomass-cellulose fiber foam from its interior using microwaves or a combination of microwaves and heat flow can further accelerate the drying time. However, too high a temperature may make the biomass-cellulose fiber foam non-uniform or even damage the foam, such as causing delamination or collapse of the structure. The drying temperature may also be changed during drying, for example, a lower initial temperature may be used and increased over time. The liquid medium may also be removed by solvent exchange, for example, water may be removed by solvent exchange with ethanol.

[0023] In any of the embodiments disclosed herein, the amount of the biomass component in the biomass-cellulose fiber foam may be 20 - 70 wt%, preferably 30 - 60 wt%, more preferably 40 - 60 wt%, based on the total weight of the dry components in the foam.

[0024] In the method according to the invention, the carbonization of the biomass-cellulose fiber foam can be carried out by increasing the temperature at a rate of 1 to 100 °C / minute in one or more steps until a maximum temperature T in the range of 700 to 1500 °C is reached. max This can be carried out, more preferably with a maximum temperature of 800 °C to 1300 °C, and most preferably with a maximum temperature of 950 °C to 1150 °C. The total time for carbonization (including cooling) can be 15 to 20 hours. Carbonization can be carried out under an inert gas such as nitrogen, helium, neon, or argon, or a mixture thereof. One advantage of the method according to the invention is that carbonization can also be carried out on a moist biomass-cellulose foam (such as a foam that has only undergone liquid medium drainage). The carbonization of the dry biomass-cellulose fiber foam provides a carbon foam that substantially has the same porous structure as the dry biomass-cellulose fiber foam. The moist biomass-cellulose fiber foam can be collected and stored for subsequent use or to fill a mold, or shaped into a desired shape by any other means, which allows the preparation of a carbon foam with a predetermined shape after carbonization. Thus, one embodiment of the method of the invention encompasses the carbonization of a shaped biomass-cellulose fiber foam to provide a shaped carbon foam. After carbonization, the carbon foam can be maintained in the shape obtained or processed into a desired shape.

[0025] Using the method according to the invention, the cellulose fiber foam acts as a porous template and a mechanical and structural carrier for the biomass component during carbonization. The pores present in the cellulose fiber foam can be retained during mixing with or impregnation with the biomass component and during carbonization, which provides a low-density carbon foam. The carbon foam obtained after carbonization can substantially have the same porous structure as the biomass-cellulose fiber foam. A further effect of using a cellulose fiber-containing foam as a template is the smaller pore size and uniform pore size distribution of the final carbon foam. The amount and type of the added biomass component allow for the tailoring of the pore size, pore characteristics, and final chemical composition of the carbon foam. The biomass component and especially lignin also prevent the foam from shrinking during carbonization. In summary, the method of the invention allows for the tailoring of the properties and characteristics of the carbon foam, such as pore size, density, open cell area per volume, stiffness, and hardness.

[0026] The carbon foam prepared by the method according to the present invention can be modified with additional components such as hydrophobic agents, activation gases, coatings or other chemicals; by post-heat treatment; or a combination of these. The carbon foam can be activated to impart desired properties to the foam such as specific absorbance properties or increased specific surface area. Activation can be carried out by treating the foam with an activation chemical and heating to a temperature of 400 to 800 °C, or by treating the foam with a gas at a temperature of about 800 to 1100 °C. Suitable activation chemicals are selected from alkali metal salts, phosphoric acid, zinc chloride and sulfuric acid or mixtures thereof. The activation chemical can help remove residual moisture from the material. Suitable gases for activation are selected from water vapor and carbon dioxide or mixtures thereof.

[0027] The present invention specifically encompasses a method for preparing a bio-based carbon foam, wherein the method comprises suspending cellulose fibers in a liquid to obtain a slurry; foaming the slurry to obtain a foam containing cellulose fibers; adding lignin powder to the foam containing cellulose fibers; optionally casting the foam into a certain shape, namely a plate, a 3D structure, a thin layer or others; drying the lignin-cellulose fiber foam; and carbonizing the foam.

[0028] The present invention also encompasses a method for preparing a bio-based carbon foam, wherein the method comprises suspending cellulose fibers in a liquid to obtain a slurry; foaming the slurry to obtain a foam containing cellulose fibers; drying the foam containing cellulose fibers; dispersing lignin particles in a liquid medium (such as an aqueous solvent or water) to obtain a lignin dispersion; impregnating the dried foam containing cellulose fibers with the lignin dispersion to obtain a lignin-cellulose fiber foam; drying the lignin-cellulose fiber foam; and carbonizing the lignin-cellulose fiber foam.

[0029] The advantages of the method of the present invention are that it is environmentally friendly, involves simple techniques and can be easily scaled up. The main components used in the method are bio-based and renewable. The liquid medium can be an aqueous solution or water.

[0030] In a third aspect, the present invention relates to a bio-based carbon foam obtained by the method according to the second aspect of the present invention. Another aspect of the present invention is an integral bio-based carbon foam, which comprises a porous core having a certain density, and wherein the foam becomes denser closer to its surface. The integral structure is similar to the structure of mammalian bone and can therefore be used as a bone implant material and a scaffold for osteogenic cells.

[0031] Another aspect is the use of the bio-based carbon foam according to the present invention in electrodes for electrochemical devices, adsorbents for macromolecules, adsorbents, thermal insulators for high-temperature applications, aerospace product components, energy storage, catalyst substrates, and stealth technology.

[0032] Unless otherwise indicated, all words and abbreviations used in this application shall be construed to have the meanings commonly ascribed to them in the relevant art. However, for clarity, some terms are specifically defined below.

[0033] The term bio-based material is used herein for any material made from substances derived from living or once-living organisms, plants, such as materials obtained from wood, lignocellulosic materials, cellulose fibers, lignin, starch, proteins, polylactic acid, etc.

[0034] Cellulose is a major component in the cell walls of all plants. Depending on the type or part of the plant, it may be present with different components. For example, in wood, cellulose is present with lignin and hemicellulose. In leaves, cellulose is present, without lignin, but with a substantial amount of hemicellulose. In the seed hairs of cotton, cellulose is present in an almost pure form, without lignin. The cellulose fibers suitable for preparing the carbon foam according to the present invention can be derived from wood, such as softwood or hardwood, leaves or fiber crops (including cotton, flax, and hemp). Suitable cellulose fibers can also be derived from regenerated cellulose, such as rayon and Lyocell. Preferably, the cellulose fibers are derived from wood, and more preferably, the cellulose fibers are pulp fibers obtained by a pulping process that releases the fibers from the wood matrix. The pulp fibers can be released by mechanical pulping, thereby obtaining mechanical pulp such as thermomechanical pulp (TMP) or chemi-thermomechanical pulp (CTMP), or chemical pulping, such as kraft pulp or pulp obtained by the sulfite process, the soda process, or the organic solvent pulping process. More preferably, the cellulose fibers are pulp fibers released by a chemical pulping process. Even more preferably, the cellulose fibers are obtained from softwood kraft pulp or dissolving pulp. The cellulose fibers used in the present invention can be free of lignin and hemicellulose. The different characteristics of each cellulose will affect the properties of the final carbon foam. The cellulose fibers are significantly longer than their width. The cellulose fibers can have an average width of 0.01 to 0.05 mm. The average fiber length of softwood can be 2.5 to 4.5 mm, while hardwood can have an average fiber length of 0.7 to 1.6 mm, and Eucalyptus can have an average fiber length of 0.7 to 1.5 mm. However, the fiber length can vary significantly depending on different growing locations, etc. The cellulose fibers used for preparing the carbon foam disclosed herein can have an average fiber length of 0.1 mm to 65 mm, 0.1 mm to 10 mm, or 0.5 mm to 65 mm, or 0.5 mm to 10 mm, or 0.5 mm to 7 mm. Different fiber lengths can provide different mechanical characteristics to the material. Due to the length of the fibers, they can be entangled with each other and impart inter-fiber bonding to the fibers, which gives strength to the foam structure. The aspect ratio (i.e., the ratio of fiber length to fiber width) of the cellulose fibers used for preparing the carbon foam according to the present invention can be at least 10, at least 25, at least 50, at least 75, or at least 100, which provides the retention and stability of the foam structure during the drying process. The aspect ratio can be up to 6500, or preferably up to 2000.

[0035] The higher aspect ratio (i.e., length-to-width ratio) of cellulose fibers can provide flexibility to the final bio-based carbon foam. The main orientation of cellulose fibers allows for the formation of different macroscopic structures in the foam, which may affect the degassing during carbonization and thus the carbonization kinetics, which in turn may affect the properties of the final bio-based carbon foam.

[0036] Lignin is a cross-linked phenolic polymer that provides rigidity in the formation of cell walls, especially in wood and bark, as it fills the spaces between cellulose, hemicellulose, and pectin components in the cell wall. This polymer lacks a defined primary structure, and the exact chemical composition of lignin varies by species, but it is relatively hydrophobic and rich in aromatic subunits. Lignin is often an undesired by-product in cellulose manufacturing and is the second-largest renewable carbon source in the world after cellulose. The lignin used in the method of the present invention preferably has a specific average particle size in the range of 0.1 to 10 μm. Particles within the preferred size range provide good adhesion to cellulose fibers. For some applications, the ash content of lignin should preferably be as low as possible.

[0037] The density of the carbon foam is determined by Equation (1):

[0038]

[0039] where m is the mass of the carbon foam block and V is the volume of the carbon foam block.

[0040] The void space in the carbon foam according to the present invention can be in the form of interconnected pores, such as at least 50%, at least 70%, or at least 80% of the total volume of the void space of the porous material according to the present invention can contain interconnected pores. The average pore diameter and pore volume can be determined by conventional methods, such as by image analysis using a microscope. The porosity of the carbon foam can be in the range of 50 to 99%. The term "porosity" for the total volume V of pores P is the ratio to the total volume V of the carbon foam. The porosity can be determined by conventional methods, such as by image analysis using a microscope.

[0041] "Specific surface area" represents the total surface area per unit mass of the solid material and can be determined by pycnometry. The carbon foam according to the present invention can have a specific surface area of 500 to 1500 m 2 / g.

[0042] It should be noted that the embodiments and / or features and / or advantages described in the context of one aspect and / or embodiment of the present invention can also be applied, with necessary modifications, to all other aspects and / or embodiments of the present invention.

[0043] Examples

[0044] The features of the present invention are further illustrated in the following examples.

[0045] Material

[0046] The dry cellulose foam was provided by Cellutech AB, and the kraft lignin powder was obtained from Stora Enso AB.

[0047] Examples

[0048] The lignin powder was dispersed in water to obtain a lignin dispersion. Additives were optionally added to improve the solubility of lignin. The cellulose foam was impregnated with the lignin dispersion. The impregnated lignin-cellulose foam was dried and then carbonized. The density and pore size distribution of the foam were measured.

Claims

1. A method for preparing a bio-based carbon foam, comprising: a) suspending cellulose fibers in a liquid medium to obtain a cellulose slurry; b) foaming the slurry to obtain a cellulose fiber foam; c) adding a biomass component to the cellulose fiber foam to obtain a biomass-cellulose fiber foam, wherein the biomass component is selected from lignin and lignocellulosic materials; and d) carbonizing the biomass-cellulose fiber foam to obtain a bio-based carbon foam.

2. The method according to claim 1, wherein the weight ratio of the biomass component to the cellulose fibers is from 3:1 to 1:3 based on dry materials.

3. The method according to claim 1 or 2, wherein the liquid medium for suspending the cellulose fibers is water.

4. The method according to any one of claims 1-3, wherein the cellulose slurry has a concentration of 0.1-40% by weight of cellulose based on the total weight of the cellulose and the liquid medium in the slurry.

5. The method according to any one of claims 1-4, wherein the cellulose fiber foam is cast into a desired shape.

6. The method according to any one of claims 1-5, wherein the cellulose fiber foam is dried.

7. The method according to claim 6, wherein the dried cellulose fiber foam is impregnated with a biomass component dispersed in a liquid medium.

8. The method according to any one of claims 1-4, wherein the biomass component is added as a powder to the cellulose fiber foam.

9. The method according to claim 8, wherein the biomass-cellulose fiber foam is cast into a desired shape.

10. The method according to any one of claims 1-9, wherein the biomass-cellulose fiber foam is dried.

11. The method according to any one of the preceding claims, wherein the biomass component is lignin.

12. The method according to any one of the preceding claims, wherein the carbonization is carried out by raising the temperature at a rate of 1 to 100 °C per minute in one or more steps until a maximum temperature T in the range of 700 to 1500 °C is reached max is carried out.

13. The method according to any one of claims 1-12, wherein the carbonization is carried out under an inert gas.

14. A bio-based carbon foam obtained by the method according to any one of claims 1-13.

15. The bio-based carbon foam according to claim 14, which comprises a porous core having a certain density, and wherein the foam becomes denser closer to its surface.

16. Use of the bio-based carbon foam according to any one of claims 14-15 in an application selected from at least one of the following: electrodes for electrochemical devices, adsorbents for macromolecules, adsorbents, thermal insulators for high-temperature applications, aerospace product components, energy storage, catalyst substrates, and stealth technology.

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