System and method for processing coal for use in direct air capture systems

Abstract

Embodiments disclosed herein relate to a method of processing coal. The method includes subjecting raw coal to a liquefaction process effective to form a liquid pitch resin and subjecting the liquid pitch resin to a filtration process. The method further includes subjecting the liquid pitch resin to a low crystallinity spinning process to form raw fibers. The raw fibers are then further subjected to a stabilization process designed to oxygen crosslink the raw fibers to form stabilized fibers, and the stabilized fibers are further subjected to a carbonization process to form low thermal conductivity carbon fibers.

Description

[Technical Field]

[0001] This application is based on and claims priority to U.S. Provisional Patent Application No. 63 / 038,554, entitled "SYSTEMS AND METHODS FOR PROCESSING COAL FOR USE IN A DIRECT AIR CAPTURE SYSTEM," filed June 12, 2020, the disclosure of which is incorporated by reference in its entirety. The embodiments described herein generally relate to carbon products and methods for processing carbon-based materials. More particularly, the embodiments relate to low-density carbon fibers and systems and methods for producing same from coal. [Background technology]

[0002] Carbon fibers are used in many different applications across a wide range of industries, including commercial aviation, recreation, industry, and transportation. Carbon fibers are used in a variety of composite materials due to their excellent properties, including high strength, high modulus, and high electrical conductivity. Summary of the Invention [Problem to be solved by the invention]

[0003] Carbon fibers produced using conventional methods, such as conventional carbon fibers (e.g., polyacrylonitrile (PAN)-based carbon fibers, pitch-based carbon fibers, or cellulose-based carbon fibers) that can be produced by carbonizing organic fibers through heat treatment, exhibit low electrical conductivity and are expensive to develop. Therefore, carbon fiber manufacturers and users continue to seek new and advanced methods for forming carbon fibers. Many of the systems and methods described herein are capable of using low-cost, high-yield coal-based pitch precursors, which are advantageous over conventional high-cost, low-yield PAN-based or cellulose-based insulating fibers. The systems and methods described herein also enable the use of low-cost pitch-based carbon fibers, which can fulfill all useful applications at a significantly reduced cost relative to existing carbon fiber products. [Means for solving the problem]

[0004] Embodiments disclosed herein relate to methods for producing low-density carbon fibers from coal. Embodiments herein also relate to producing electroswing adsorption (ESA) systems. In some embodiments, the ESA system can be included in a direct air capture (DAC) system. The methods disclosed herein can include continuous processes. In one example, the methods disclosed herein can include a direct air capture system including a coal-derived electroactive polymer for capturing CO from a gas stream.

[0005] In some embodiments, a method for treating coal can include subjecting raw coal to a liquefaction process to form a liquid pitch resin and subjecting the liquid pitch resin to a filtration process. The filtration process can remove mineral matter and heavy metal impurities from the liquid pitch resin. The method can further include subjecting the liquid pitch resin to a low crystallinity spinning process to form raw fibers. In some embodiments, the method can also include subjecting the raw fibers to a stabilization process adapted to oxygen crosslink the fibers to form stabilized fibers, and subjecting the stabilized fibers to a carbonization process to form low thermal conductivity carbon fibers.

[0006] In some embodiments, the pitch resin has a melting point such that subjecting the liquid pitch resin to a low crystallinity spinning process to form raw fibers does not include a plasticizer. In some embodiments, the melting point of the liquid pitch resin is about 343°C (650°F) or less. In some embodiments, the melting point of the liquid pitch resin is between about 80°C and about 343°C. In some embodiments, the method can further include adding a blending additive to the liquid pitch resin before or during the low crystallinity spinning process. The blending additive can include one or more of an isotropic pitch, a pitch with a level of anisotropy, or a thermoplastic blending additive.

[0007] In some embodiments, the low crystallinity spinning process involves physically altering the spinning conditions. Physically altering the spinning conditions can include using a turbulent spinneret design, a low draw ratio for green spun fibers, a meltblown solvation spinning system, using a flow inverter or frit flow redistributor for the spinneret capillary channels, introducing voids into the spun fibers, using a special spinneret to form hollow fibers with one or more cross-sectional holes, using a special spinneret to promote shear, or a combination thereof. In some embodiments, the pitch resin can be treated with a blowing agent to promote expansion of the raw fibers, and the blowing agent can include a hydrocarbon, including at least one of pentane, cyclopentane, liquid carbon dioxide, chlorofluorocarbons (CFCs), or hydrochlorofluorocarbons (HCFCs).

[0008] In some embodiments, a method for manufacturing an electro-swing reactive adsorption (ESA) system can include forming a polyanthraquinone-activated carbon composite cathode electrode (negative electrode), forming a ferrocene-activated carbon composite anode electrode (anode electrode), and disposing one or more separator membranes between the cathode and anode electrodes. In some embodiments, the polyanthraquinone-activated carbon composite cathode electrode comprises low-conductivity carbon fiber, and the ferrocene-activated carbon composite anode electrode comprises low-conductivity carbon fiber.

[0009] In some embodiments, the method for manufacturing an electroswing reactive absorption (ESA) system can further include forming low-conductivity carbon fibers by subjecting raw coal to a liquefaction process to form a liquid pitch resin, subjecting the liquid pitch resin to a filtration process, subjecting the liquid pitch resin to a low-crystallinity spinning process to form raw fibers, subjecting the raw fibers to a stabilization process designed to oxygen-crosslink the fibers, and subjecting the stabilized fibers to a carbonization process to form low-conductivity carbon fibers. In some embodiments, the method further includes providing coal, beneficiating the coal to remove impurities therefrom, treating at least a portion of the beneficiated coal to produce a solid char, and treating at least a portion of the solid char to produce activated carbon. In some embodiments, the solid char can have a hydrogen-to-carbon ratio of about 0.05 to about 0.65.

[0010] In some embodiments, treating at least a portion of the solid char can include at least one of physical activation or chemical activation. In some embodiments, physical activation can include heating the char in an inert atmosphere. In some embodiments, physical activation can include heating the char in an oxidizing atmosphere. Chemical activation can include impregnating the char with one or more chemicals.

[0011] The electroswing reactive absorption (ESA) system can include a polyanthraquinone-activated carbon composite cathode electrode, a ferrocene-activated carbon composite anode electrode, and one or more separator membranes disposed between the cathode and anode electrodes. In some embodiments, the polyanthraquinone-activated carbon composite cathode electrode can include low-conductivity carbon fibers, and the ferrocene-activated carbon composite anode electrode can include low-conductivity carbon fibers. The low-conductivity carbon fibers can be coal-based low-conductivity carbon fibers. In some embodiments, the activated carbon is coal-based activated carbon.

[0012] In some embodiments, the ESA system may be included in a direct air capture (DAC) system.

[0013] Features from any of the disclosed embodiments may be used in combination with each other without limitation. Additionally, other features and advantages of the present disclosure will become apparent to those skilled in the art through a review of the following detailed description and accompanying drawings. [Brief explanation of the drawings]

[0014] The drawings illustrate several embodiments of the present disclosure, with the same reference numerals indicating the same or similar elements or features in different views or embodiments shown in the drawings.

[0015] [Figure 1] 1 is a flowchart of a method for treating coal, according to one embodiment.

[0016] [Figure 2] FIG. 1 illustrates a raw coal processing flow according to one embodiment.

[0017] [Figure 3] 1 is a flowchart of a method for manufacturing an electroswing reactive absorption (ESA) system, according to one embodiment.

[0018] [Figure 4] FIG. 4 is a schematic diagram of an electroswing reactive absorption (ESA) system that can be formed by the method illustrated in FIG. 3, according to one embodiment.

[0019] [Figure 5] 1 is a schematic diagram of a direct air capture system, according to one embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0020] This description provides examples of the present invention and is not intended to limit the scope, application, or configuration of the invention as defined by the appended claims. Accordingly, changes may be made in the function and arrangement of the disclosed elements, and various embodiments may omit, substitute, or add other steps or components as appropriate, without departing from the spirit and scope of the disclosure. For example, described methods may be performed in an order different from that described, and various steps may be added, omitted, or combined. Also, features described with respect to some embodiments may be combined in other embodiments.

[0021] Provided herein are systems and methods for processing coal to form carbon products for use in direct air capture (DAC) systems. The carbon products can include one or more of carbon fibers, activated carbon, coal-derived char, resins, graphene, materials for use in batteries, materials for use in building and construction, or combinations thereof. The systems and methods provided herein can include the processing of pitch made from coal, as well as products formed or manufactured by the systems and methods. The systems and methods described herein facilitate the production of low-cost, low-thermal-conductivity carbon fiber products. For example, many carbon fiber products produced in accordance with the present disclosure have lower densities than conventional carbon fiber products produced from similar materials. Low-density carbon fiber products retain heat, thereby imparting properties to the carbon fiber products that reduce their thermal conductivity compared to conventional carbon fibers.

[0022] The low thermal conductivity carbon fiber products produced according to many of the systems and methods described herein are unexpected to those skilled in the art. Many embodiments of the systems and methods described herein enhance the conversion of coal-based pitch intermediate products into useful conversion products, such as high-carbon content pitch fiber products with low thermal conductivity. These products may be suitable as insulation and / or low-density carbon fibers. In particular, the present technology utilizes a specially designed system and one or more blend additives to tailor the physical properties of the carbon fiber, such as at least one of the density (specific gravity) and / or thermal conductivity of the carbon fiber. Many of the systems and methods described herein are capable of using low-cost, high-yield coal-based pitch precursors, which are advantageous over traditional high-cost, low-yield PAN-based or cellulosic-based insulating fibers. The systems and methods described herein can also provide carbon fiber products in a manner that allows low-cost pitch-based carbon fibers to enable all useful applications while significantly reducing costs for existing companies. For example, the systems and methods can produce affordable carbon fiber insulation to improve energy efficiency in the built environment as an alternative to fiberglass insulation.

[0023] FIG. 1 is a flowchart of a method 100 for processing coal to form low thermal conductivity carbon fibers, according to one embodiment. For example, method 100 can include step 102, in which raw coal is subjected to a liquefaction process effective to form a liquid pitch resin. Coal liquefaction is a process in which coal is converted into a liquid. Several processes are used to accomplish this task, with the two most common being the indirect route and the direct route. In some embodiments, the indirect route consists of two steps: first, coal is gasified with steam and oxygen to produce synthesis gas (syngas), which is then scrubbed to remove dust, tar, and acid gases. In the next step, the synthesis gas is reacted with a catalyst in a Fischer-Tropsch process to convert it into various hydrocarbons. For example, the hydrocarbons can include pitch resin. In the direct route, coal is crushed and reacted with a catalyst, followed by the addition of hydrogen under high pressure and high temperature in the presence of a solvent to produce hydrocarbons such as liquid pitch resin. In another embodiment, pulverized coal can be suspended in a hydrogen-donor solvent and reacted under pressure in an inert atmosphere with or without a catalyst.

[0024] Method 100 may include step 104, which involves subjecting the liquid pitch resin to a filtration process. In some embodiments, the filtration process includes mechanical filtration. In some embodiments, the filtration process includes chemical filtration. Step 104 filters the liquid pitch resin to remove minerals and heavy metals contained in the previously filtered feed coal. In some embodiments, the filtration process may be carried out at an elevated temperature. The elevated temperature may include a temperature between about 60°C and about 300°C. In some embodiments, step 104 may include heating the liquid resin pitch temperature to about 60°C or higher, about 100°C or higher, about 150°C or higher, about 200°C or higher, or to a range of about 60°C to about 100°C, about 100°C to about 200°C, or about 200°C to about 300°C. The final temperature may be about 200°C or higher, about 250°C or higher, or about 300°C or higher.

[0025] In some embodiments, the melting point of the pitch resin may be about 343°C or less. In some embodiments, the melting point of the liquid pitch resin is between about 80°C and about 343°C. In some embodiments, the pitch resin comprises a melting point that allows the pitch resin to undergo a low crystallinity spinning process that is effective for forming raw fibers without the use of plasticizers. In some embodiments, including prior art, plasticizers can include substances added to a material to make it softer or more flexible, increase its plasticity, reduce its viscosity, or reduce friction during handling in manufacturing.

[0026] In embodiments, the liquid filtered pitch resin may then be subjected to a low crystallinity spinning process effective to form raw fibers in step 106. In many embodiments, the systems and methods include at least one of two processes for disrupting the densified crystalline graphite structure associated with the carbon fibers. The two processes for disrupting the densified crystalline graphite structure may include physically altering the spinning conditions in a variable crystallinity spinning process and chemically altering the pitch composition with one or more blend additives. The spinning conditions may be physically altered to be more conducive to disrupting liquid crystal formation in a low crystallinity spinning process. In some embodiments, spinning conditions can be physically altered by one or more of the following: turbulent spinneret design, low draw ratio on green spun fibers, meltblown solvation spinning systems versus neat resin melt spinning, use of flow inverters or frit flow redistributors in the spinneret capillary channels, introduction of voids (such as nano-sized bubbles) in the spun fibers via foaming, and / or use of specialized spinnerets with one or more cross-sectional holes for hollow fiber formation, or combinations thereof.

[0027] In some embodiments, method 100 can also include step 108, adding a blend additive to the pitch resin before or during the low-crystallinity spinning process of step 106. In some embodiments, the blend additive can include one or more of isotropic pitch, pitch with a level of anisotropy, or thermoplastic blend additive. Pitch is generally isotropic but can be made anisotropic by heat treatment. Isotropic and anisotropic pitch differ not only in the carbon precursor but also in optical texture, microstructure, and physical properties. Additives can improve the strength and stiffness of the raw fiber. The pitch composition can also be chemically altered with one or more blend additives to make it more conducive to breaking down liquid crystal formation. The inclusion of one or more blend additives can result in carbon fibers with lower densities than conventionally formed carbon fibers. The resulting carbon fibers can include properties more similar to or superior to those of rayon carbon fibers, such as lower thermal conductivity. In some embodiments, the pitch composition can be varied by utilizing isotropic pitch and / or anisotropic pitch having a degree of anisotropy between 0% and 80% as a blend additive (or neat) in place of the highly discotic liquid crystal-containing mesophase pitch. In some embodiments, the blend additive can include one or more of various degrees of anisotropic pitch.

[0028] In some embodiments, the pitch composition can be varied by utilizing an oxygen-containing additive, such as an oxygen-containing polymeric material. In some embodiments, the pitch composition can be varied by utilizing one or more compounds containing heteroatoms such as oxygen or nitrogen. In some embodiments, the pitch composition can be varied by utilizing one or more thermoplastic blending additives (e.g., phenolic resins, lignin, etc.) containing heteroatoms such as oxygen or nitrogen. Mixing materials containing heteroatoms (e.g., oxygen) into the pitch during fiber spinning can reduce the fiber density. Examples of one or more thermoplastic blending additives containing heteroatoms such as nitrogen or oxygen include (but are not limited to) polyphenol formaldehyde resin, lignin, polyethylene oxide, polyvinyl alcohol, poly DL-lactide, polymethyl methacrylate, or combinations thereof. In some embodiments, one or more of the heteroatom-containing additives can be derived from coal. TIFF0007768903000001.tif66168Polyphenol formaldehyde resin TIFF0007768903000002.tif64168Lignin TIFF0007768903000003.tif17168Polyethylene oxide (PEO) TIFF0007768903000004.tif14168Polyvinyl alcohol TIFF0007768903000005.tif22168Poly DL-lactide (PLA)

[0029] The physical and chemical processes described above to disrupt the dense crystalline graphite structure associated with carbon graphite fibers can modify pitch-based carbon fibers to approach the microstructural characteristics and resulting density and insulating properties more commonly associated with cellulosic (rayon-based) carbon fibers. Tables 1 and 2 provide a comparison of the properties of PAN-, pitch-, and rayon-based carbon fibers. TIFF0007768903000006.tif55169TIFF0007768903000007.tif51168

[0030] Method 100 can also include step 110. Step 110 can include treating the pitch resin with a blowing agent to promote foaming of the raw carbon fibers. In some embodiments, the blowing agent can include at least one hydrocarbon. The blowing agent can include at least one of pentane, cyclopentane, liquid carbon dioxide, chlorofluorocarbons (CFCs), and hydrochlorofluorocarbons (HCFCs). However, several other materials can also serve as blowing agents. In some embodiments, the blowing agent can create a cellular structure through the foaming process. The cellular structure of the matrix reduces density, increases thermal and acoustic insulation, and increases the relative stiffness of the pitch resin and carbon fibers.

[0031] In some embodiments, method 100 may also include step 112, which involves subjecting the raw fibers to a stabilization process designed to oxygen crosslink the fibers to form stabilized fibers. In some embodiments, the raw fibers may undergo a stabilization process in which air (oxygen), and possibly additional gases or vapors, are introduced to convert the linear atomic bonding of the fibers to a more thermally stable form. The raw carbon fibers must be stabilized before the calcination step in step 114, described below. This stabilization prevents the molecules in the carbon fibers from relaxing and becoming misaligned during the calcination step. Stabilization maintains molecular integrity and allows the fibers to remain in their solid form through final processing steps.

[0032] In some embodiments, stabilization of the fibers can be performed at temperatures between 200 and 300°C and include a resonance time of 30 to 120 minutes. During this resonance time, the fibers can be exposed to an air atmosphere containing approximately 21% oxygen. Additional gases or vapors can be added to the stabilization atmosphere to alter the reactions occurring within the pitch of the fibers. During step 112, which includes stabilization, the fibers can be maintained under tension to prevent relaxation and misalignment of the pitch molecules. Pitch-based carbon fibers typically form ester and anhydride compounds within the pitch during step 112. Pitch-based fibers can also be freed of aromatics during step 112.

[0033] Method 100 may also include step 114, in which the stabilized fibers are subjected to a carbonization process effective to form low thermal conductivity carbon fibers. In some embodiments, carbonization is a process in which the stabilized fibers are heated and any volatile products (liquids and gases) are driven off, leaving behind solid, low thermal conductivity carbon fibers.

[0034] While systems and methods for producing low thermal conductivity carbon fiber insulation are described above, other systems and methods for manufacturing, producing, or otherwise forming various advanced carbon materials are contemplated in this disclosure. These various advanced carbon materials may include other carbon fibers, activated carbon, resins, graphene, materials for use in batteries, materials for use in building and construction, or combinations thereof. Methods for producing carbon fibers, resins, graphene, and other advanced carbon materials (including activated carbon) from coal are disclosed in PCT Patent International Application No. PCT / US2018 / 067341, filed December 21, 2018, the disclosure of which is incorporated herein by reference in its entirety.

[0035] 2 illustrates a flow diagram for processing raw coal, for example, from a highwall coal mine, to form various advanced carbon materials, such as activated carbon, graphene, materials for use in batteries, and building and construction materials, according to one embodiment. As shown, according to some embodiments, processing of coal can produce advanced carbon materials, which can themselves be further processed to form other advanced carbon materials. Furthermore, in some embodiments, by-products in the production of advanced carbon materials can themselves be further processed to produce other advanced carbon materials, as described herein.

[0036] More specifically, the feedstock coal can be provided to a processing facility, which may have the capability to store the feedstock coal for use as needed, or which may receive the feedstock coal as needed to produce a desired amount of an advanced carbon material, such as activated carbon. The feedstock coal can be beneficiated to remove contaminants or impurities, such as water, heavy metals, and / or volatile compounds, from the feedstock coal, thereby producing beneficiated or upgraded coal.

[0037] Beneficiated coal may contain significantly reduced amounts of mercury, cadmium, other heavy metals, water, and / or other impurities. As used herein, an impurity may be any element or compound other than carbon or hydrogen. For example, beneficiating coal may reduce the amount of mercury in the coal by at least about 70%, 75%, 80%, 85%, 90%, or 92% or more. In some cases, beneficiating coal may reduce the water or moisture content of the coal to about 5 wt%, 4 wt%, 3 wt%, 2 wt%, or 1.5 wt% or less. In some cases, beneficiating coal may remove one or more of hydrogen, sulfur, oxygen, arsenic, selenium, cadmium, or volatile matter from the coal. The amount of one or more of these elements in the coal may be reduced by about 25% to about 90%.

[0038] In some embodiments, coal can be beneficiated to produce a variety of other products that can be captured and used in subsequent treatment processes or that can be subjected to further processing. For example, in some embodiments, coal can also be beneficiated to produce a solid material known as ash or char. In some cases, this char can be subjected to further processing to form activated carbon, which is described in more detail below.

[0039] The beneficiated coal, also referred to as upgraded coal, can be processed through a processing facility. In some embodiments, processing the beneficiated coal includes subjecting the upgraded coal to a liquid extraction process, such as a pyrolysis process, a direct liquefaction process, an indirect liquefaction process, or a process involving one or more membranes. In some embodiments, one or more additives can be added to the beneficiated coal. In some embodiments, one or more other gases or liquids can be used in the process. For example, a hydrogen-containing gas can be added to or used in the coal liquefaction process. In some cases, natural gas, CO2, or petroleum products can be used as additives. In some embodiments, the one or more additives can include materials or compounds that were generated during previous processing or that can be generated or captured during interactions prior to the liquid extraction process.

[0040] The pitch, char, gas, and / or coal liquor can be produced through a processing facility. In some embodiments, the pitch can be produced through a processing facility. Pitch, as used herein, is also known as coal pitch, coal tar, or coal tar pitch and can refer to a mixture of one or more typical viscoelastic polymers, as well understood by those skilled in the art. In some embodiments, the produced pitch can be a direct result of processing beneficiated coal. The produced pitch can include one or more high molecular weight polymers. In some embodiments, the pitch can have a melting point not exceeding about 650°F. In some embodiments, the pitch can have a melting point high enough that the pitch can be used, for example, in a carbon fiber spinning process as described herein, without the need for a plasticizer. In some embodiments, the melting point of the liquid pitch resin is between about 80°C and about 343°C.

[0041] In some embodiments, char can be produced through processing facilities. Char, as used herein, can refer to any solid material remaining after gases, liquids, and / or pitch have been removed from the feed coal. In some embodiments, at least a portion of the produced char can be effectively processed to produce an enhanced carbon material such as activated carbon. For example, at least a portion of the char can be carbonized or heated (e.g., in a rotary kiln).

[0042] In some embodiments, activated carbon can also be produced from coal by utilizing isotropic pitch that is processed to form a foam. This foam can be activated to produce high surface area activated carbon. Additional systems and methods for producing activated carbon are disclosed in U.S. Patent No. 7,070,755, filed January 29, 2002, the disclosure of which is incorporated herein by reference in its entirety.

[0043] FIG. 3 is a flowchart of a method 300 for fabricating an electroswing reactive absorption (ESA) system, according to one embodiment. In some embodiments, method 300 includes forming a polyanthraquinone-activated carbon composite cathode electrode, as shown in block 302. In some embodiments, method 300 includes forming a ferrocene-activated carbon composite anode electrode, as shown in block 304. Method 300 further includes disposing one or more separator membranes between the cathode electrode and the anode electrode, as shown in block 306. In some embodiments, the polyanthraquinone-activated carbon composite cathode electrode includes low-conductivity carbon fibers, and the ferrocene-activated carbon composite anode electrode also includes low-conductivity carbon fibers. In some embodiments, the low-conductivity carbon fibers can be formed in block 308 and are formed by the process described with reference to FIG. 1. Forming the low conductivity carbon fibers can include subjecting raw coal to a liquefaction process to form a liquid pitch resin, subjecting the liquid pitch resin to a filtration process, subjecting the liquid pitch resin to a low crystallinity spinning process to form raw fibers, subjecting the raw fibers to a stabilization process adapted to oxygen crosslink, and subjecting the stabilized fibers to a carbonization process to form the low conductivity carbon fibers.

[0044] Method 300 may also include forming activated carbon, as shown in block 310. In some embodiments, the activated carbon may be formed by providing coal, beneficiating the coal to remove impurities therefrom, treating at least a portion of the beneficiated coal to form a solid char, and treating at least a portion of the solid char to form the activated carbon.

[0045] In some embodiments, the beneficiation process includes heating the feed coal to a desired temperature for a first duration. In some embodiments, the beneficiation also includes heating the feed coal to a higher desired temperature for a second duration. In some embodiments, the coal can be heated in a halogen gas atmosphere. In some embodiments, the beneficiation can include subjecting the feed coal to the WRITECoal beneficiation process, for example, as described in U.S. Pat. No. 9,181,509, which is incorporated herein by reference in its entirety. In some other embodiments, the coal can be beneficiated by heating the coal to a desired temperature in the presence of one or more catalytic compounds. In some aspects, beneficiating the coal can include, for example, pyrolyzing the coal in the presence of a catalyst. In some cases, the coal can be beneficiated by a BenePlus system, such as that described in U.S. Patent Publication No. 2017 / 0198221, developed and licensed by LP Amina and incorporated herein by reference in its entirety.

[0046] In some embodiments, the char can be produced during beneficiation of raw coal, by earlier process steps described above, or by any combination thereof. In some embodiments, the char can be composed of solid high surface area carbonaceous material. In some aspects, the char can have a relatively low H:C ratio, for example, an H:C ratio lower than the H:C ratio of pitch produced during coal processing. In some aspects, the char can have an H:C ratio of about 0.05 to about 0.65. In some embodiments, the H:C ratio can be about 0.05 or greater, about 0.15 or greater, about 0.25 or greater, about 0.4 or greater, about 0.55 or greater, or within the range of about 0.05 to about 0.2, about 0.20 to about 0.40, or about 0.40 to about 0.65.

[0047] In some cases, the char may further include at least some pitch material, which may be referred to herein as intrinsic binder impregnation. In some cases, residual pitch or other gas or liquid material may be removed from the char prior to subsequent processing of the char.

[0048] The char can then be activated, for example, by a physical activation process or a chemical activation process. In some embodiments, physical activation can include heating the char in an atmosphere containing argon and / or nitrogen, or heating the char in an oxidizing atmosphere. In some embodiments, chemical activation can include impregnating the char with one or more chemicals, such as an acid, a base, or a salt. In some embodiments, chemical activation can further include carbonizing or heating the char to activate it. In some embodiments, chemical activation requires lower temperatures and less energy than physical activation. Additionally, in some embodiments, other chemical by-products produced by other processes for producing advanced carbon can be utilized during the chemical activation process.

[0049] Referring to FIG. 4, an electroswing reactive absorption (ESA) system 400 according to one embodiment is disclosed. The ESA system 400 can include a sealed chamber and a flow cell. The capture and release of CO2 during electrochemical activation and deactivation of quinones, respectively, can be indicated by concomitant pressure changes within the chamber. The flow cell houses a stack of electrochemical cells to enable CO2 capture.

[0050] In some embodiments, an electroswing reactive absorption (ESA) system 400 includes a polyanthraquinone-activated carbon composite cathode electrode 402, a ferrocene-activated carbon composite anode electrode 404, and one or more separator membranes 406 disposed between the cathode electrode 402 and the anode electrode 404. The electrochemical cell can include the polyanthraquinone-activated carbon composite cathode electrode and captures CO2 upon charging and releases CO2 upon discharging via carboxylation of reduced quinone. The electrochemical cell including the quinone-activated carbon composite can operate as an ESA process.

[0051] The activated carbon of the polyanthraquinone-activated carbon composite cathode electrode 402 can comprise carbon activated according to one or more of the coal treatment systems and methods described herein. The cell can include two cathode electrode (cathode) substrates coated with a CO2-binding quinone-activated carbon composite sandwiching an anode electrode (anode) substrate. The anode electrode 404 substrate can be coated with a ferrocene-activated carbon composite, such as the activated carbon composite comprising activated carbon formed from coal described herein, and a separator membrane 406 can be disposed between the electrodes. That is, the polyanthraquinone-activated carbon composite cathode electrode 402 comprises low-conductivity carbon fibers, and the ferrocene-activated carbon composite anode electrode 404 comprises low-conductivity carbon fibers. In some embodiments, the low-conductivity carbon fibers are coal-based low-conductivity carbon fibers. In some embodiments, the activated carbon is coal-based activated carbon.

[0052] The cell structure serves to maximize the surface area exposed to the gas while allowing for easy stacking of the cells in a parallel passage contactor. The ferrocene-activated carbon composite electrode 404 serves as an electron source and sink, respectively, for the reduction and oxidation of the quinone-activated carbon composite electrode 402, allowing for modulation of CO2 uptake and release.

[0053] In other embodiments, the ESA system 400 does not include a ferrocene-activated carbon composite electrode 404. Wetting of the porous nonwoven carbon fiber mat used as the electrode substrate by the room temperature ionic liquid (RTIL) electrolyte allows for a net ionic current to flow through the electrolyte during electrode activation and deactivation, and allows for diffusion of CO2 to the electrolyte-wetted negative electrode (cathode) during capture.

[0054] In some embodiments, the ESA system 400 can be included in a direct air capture (DAC) system 500. FIG. 5 is a schematic diagram of a DAC system, according to an embodiment. Advanced carbons, including low-density carbon fibers and / or activated carbon, formed according to one or more of the methods and systems described herein can be utilized in a DAC system 500, such as a thermoelectric DAC, a DAC using a coal-derived electroactive polymer (EAP), or any combination thereof. Accordingly, also disclosed herein is a DAC system 500 having at least one of low-density carbon fibers, activated carbon, or another advanced carbon according to any of the above-described systems and methods. In some embodiments, a DAC system 500 using a coal-derived EAP may not include low-density carbon fibers and may additionally or alternatively include other coal-derived materials, such as coal-derived graphene or graphene oxide.

[0055] Coal-derived EAPs can be formed from anthracene. In some embodiments, the coal can be subjected to liquefaction effective to produce anthracene and / or other polycyclic aromatic hydrocarbons (PAHs). The coal-derived anthracene can then be subjected to oxidation effective to form anthraquinone or similar products. The anthraquinone can then be chlorinated, for example, with hydrochloric acid, effective to form dichloroanthraquinone. The dichloroanthraquinone can then be polymerized to form the EAP.

[0056] Coal-derived EAPs can possess ketone functionality, which facilitates the binding of CO2 to the EAP when a voltage is applied across them. Once the binding sites of the EAP are saturated with bound or adsorbed CO2, the polarity of the voltage can be reversed, resulting in desorption of the bound CO2, i.e., release of a large amount of CO2 from the EAP. Furthermore, because polarity can be reversed, systems such as batteries using EAPs do not require separate materials for the positive and negative electrodes (anode and cathode). These properties allow the use of feed gases with relatively low concentrations of CO2 (e.g., 415 ppm in air), and the amount of CO2 bound can be increased by passing the feed gas over the EAP multiple times. In some embodiments, carbon nanotubes, graphene, graphene oxide, and / or other coal-derived conductive carbon materials may also be added to the system to enhance the conductivity of components containing the EAP.

[0057] FIG. 5 illustrates a DAC system 500 with low-density carbon fibers. In some embodiments, the DAC system 500 includes an electroswing reactive absorption (ESA) system 502, consisting of an electrochemical cell that utilizes the reductive addition of CO to a quinone for carbon capture. In some embodiments, the system can rely on an electric field to facilitate CO adsorption or capture and subsequent desired release. The ESA system 502 can eliminate the requirement for complex flow systems and can be effective for treating both high-concentration and low-concentration feed streams. The DAC system 500 includes a voltage source 504. In one example, the voltage source 504 can include a generator, a battery, or a cell. In some embodiments, the voltage source 504 can include a DC voltage source or an AC voltage source. The voltage source 504 can include a voltage-controlled voltage source or a current-controlled voltage source for applying an electric field. The DAC system 500 is configured to couple carbon dioxide from a gas stream 506. The carbon dioxide couples to the ESA system 502 when an electric field is applied. The polarity of the voltage can be reversed to release the bound carbon dioxide from ESA 302 and / or DAC system 500. DAC system 500 is configured to produce gas stream 508 having a lower concentration of CO than gas stream 506. In some embodiments, gas stream 508 is CO-free.

[0058] Thermoelectric DACs, DACs using coal-derived electroactive polymer EAPs, and electroswing reactive absorption can be used in a variety of applications. For example, thermoelectric DACs, DACs using coal-derived electroactive polymer EAPs, and electroswing reactive absorption can be used to combat the negative impacts of CO2 during the construction of buildings and structures. Adding panels containing thermoelectric DACs, DACs using coal-derived electroactive polymer EAPs, and electroswing reactive absorbers to buildings can capture CO2 during and after construction. Buildings can then capture CO2 using thermoelectric DACs, DACs using coal-derived electroactive polymer EAPs, and electroswing reactive absorbers. The CO2 captured by thermoelectric DACs, DACs using coal-derived electroactive polymer EAPs, and electroswing reactive absorption integrated into buildings can be used with many materials, such as hydrocarbon materials or reverse water-gas shift to convert CO2 into syngas and densified liquids.

[0059] As used herein, the terms "about" or "substantially" refer to a tolerance of ±10% or ±5% of the term modified by "about" or "substantially." Furthermore, the terms "less than," "fewer," "greater than," and "more than" include the endpoint values ​​modified by those terms.

[0060] While various aspects and embodiments have been disclosed herein, other aspects and embodiments are also contemplated. The foregoing description, for purposes of explanation, used specific terminology to provide a thorough understanding of the described embodiments. However, it will be apparent to those skilled in the art that specific details are not required to practice the described embodiments. Thus, the foregoing descriptions of the specific embodiments described herein are presented for purposes of illustration and description. They are not limited to the precise forms disclosed. It will be apparent to those skilled in the art that numerous modifications and variations are possible in light of the above teachings.

[0061] Features of any disclosed embodiment can be used in combination with each other without limitation. In addition, other features and advantages of the present disclosure will become apparent to those skilled in the art through a review of the following detailed description and the accompanying drawings. Various inventions have been described herein with reference to certain specific embodiments and examples. However, those skilled in the art will recognize that many variations are possible without departing from the scope and spirit of the inventions disclosed herein, in that the inventions as set forth in the following claims are intended to cover all variations and modifications of the disclosed inventions without departing from the spirit of the inventions. As used in this specification and the claims, the terms "including" and "having" shall have the same meaning as the inclusive term "comprising."

[0062] Terms of degree (e.g., "about," "substantially," "generally," etc.) indicate acceptable structural or functional variations. In one example, when a term of degree is included with a term of quantity, the term of degree is interpreted to mean ±10%, ±5%, or +2% of the term of quantity. As an example, when a term of degree is used to modify a shape, the term of degree indicates that the shape modified by the term of degree has the appearance of the disclosed shape. For example, the term of degree can be used to indicate that a shape has rounded corners instead of sharp corners, curved edges instead of straight edges, one or more protrusions extending therefrom are rectangular, the same as the disclosed shape, etc.

Claims

1. 1. A method of manufacturing an electroswing reactive absorption (ESA) system, comprising: forming a polyanthraquinone-activated carbon composite cathode electrode containing low thermal conductivity carbon fibers; forming a ferrocene-activated carbon composite anode electrode containing low thermal conductivity carbon fibers; disposing one or more separator membranes between the cathode electrode and the anode electrode; A method comprising:

2. The low thermal conductive carbon fiber, subjecting the raw coal to a liquefaction process to form a liquid pitch resin; subjecting the liquid pitch resin to a filtration process; subjecting the liquid pitch resin to a low crystallinity spinning process to form raw fibers; subjecting the raw fibers to a stabilization process designed to oxygen crosslink the raw fibers; subjecting the stabilized fibers to a carbonization process to form low thermal conductivity carbon fibers; The method of claim 1 further comprising forming by:

3. The activated carbon of the polyanthraquinone-activated carbon composite cathode electrode and the ferrocene-activated carbon composite anode electrode providing coal; beneficiating the coal to remove impurities from the coal; treating at least a portion of the beneficiated coal to form a solid char; treating at least a portion of the solid char to produce the activated carbon; The method of claim 1 or 2, further comprising forming by

4. 4. The method of claim 3, wherein the solid char has a hydrogen to carbon ratio of from 0.05 to 0.

65.

5. 4. The method of claim 3, wherein treating at least a portion of the solid char comprises at least one of physical activation or chemical activation.

6. 6. The method of claim 5, wherein the physical activation comprises heating the solid char in an inert atmosphere.

7. 6. The method of claim 5, wherein the physical activation comprises heating the solid char in an oxidizing atmosphere.

8. 6. The method of claim 5, wherein the chemical activation comprises impregnating the solid char with one or more chemicals.

9. A polyanthraquinone-activated carbon composite cathode electrode containing low thermal conductivity carbon fiber; a ferrocene-activated carbon composite anode electrode containing low thermal conductivity carbon fibers; one or more separator membranes disposed between the cathode electrode and the anode electrode; Electroswing reactive absorption (ESA) system having:

10. The system of claim 9 , wherein the low thermal conductivity carbon fiber is a coal-based low thermal conductivity carbon fiber.

11. 11. The system according to claim 9, wherein the activated carbon of the polyanthraquinone-activated carbon composite cathode electrode and the ferrocene-activated carbon composite anode electrode is a coal-based activated carbon.

12. The system of claim 9 , wherein the ESA system is included in a direct air capture (DAC) system.

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