Sheet product for capturing carbon emissions and process for using same

Abstract

An impregnated product is disclosed comprised of a nonwoven material impregnated with a carbon capture composition. When contacted with a gas stream, the impregnated product is well suited for removing gaseous carbon components from the gas stream, such as carbon dioxide. The impregnated product can be used in a direct air capture process. For instance, an air stream can be fed over a surface of the impregnated nonwoven product in a counter-current manner for removing carbon dioxide from the air stream. The carbon capture composition can then be removed from the nonwoven for releasing and collecting the carbon dioxide. The nonwoven and the carbon capture composition can then be recycled and reused in the process.

Description

[0001] 65121505PC01

[0002] SHEET PRODUCT FOR CAPTURING CARBON EMISSIONS AND PROCESS FOR USING SAME

[0003] BACKGROUND

[0004] Removal of carbon gases from the atmosphere is important for limiting global temperature increase and mitigating the consequences of greenhouse gases already in the atmosphere. Direct air capture (DAC) technologies bind and separate CO2 from air, and amine-based adsorbents are often used in DAC technologies due to their high affinity for CO2 in dilute CO2 concentrations. The high CO2 uptake of amines at low partial pressures typically necessitates their operation in temperature-swing adsorption (TSA) processes, as desorbing the CO2 through only a pressure reduction would be challenging given their high uptakes at low partial pressures. In temperature-swing adsorption processes, the sorbents are heated to release the CO2, relying on the decrease in CO2 affinity with increasing temperature.

[0005] Utilizing adsorbents in powder or pellet-packed beds is infeasible due to the high pressure drop, so adsorbents are typically implemented in structured contactors, such as monoliths and hollow fibers. Structured contactors not only have a lower pressure drop, but their geometry can also allow for thermal management during adsorption or indirect heating during desorption. However, these contactors often contain inactive supports or binders. In monoliths, binders (e.g., bentonite) or substrates (e.g., cordierite) are used to maintain the mechanical integrity of the sorbent contactor. Hollow fiber adsorbents, another example of a structured contactor, use a porous polymeric matrix (e.g., cellulose acetate) to support and distribute the adsorbent, enhancing CO2 transport through the material. For wash-coated contactors, the adsorbent is directly coated or grown onto the walls of an existing structure and makes up a small fraction of the overall contactor mass. In addition to the substrates used for contactor fabrication, polyamines are typically added to a high surface area support, such as silica or alumina that is embedded in the contactor. The high surface area support increases CO2 accessibility to the amines. One example of a direct air capture process utilizing a sorbent material functionalized on the surface with amino functionalities is disclosed in U.S. Patent Publication No. 2023 / 0233985, which is incorporated herein by reference.

[0006] While the support materials are advantageous for mechanical integrity and CO2 transport, they penalize the energy requirement of the carbon capture system. Even though the support materials are inactive for CO2 adsorption, they still must be heated each cycle along with the adsorbent, significantly increasing the sensible heat required. Thus, it would be advantageous to eliminate the required sensible heat for the support while maintaining its advantages for mechanical integrity and CO2 transport.

[0007] In U.S. Patent Publication No. 2022 / 0362737, which is incorporated herein by reference, a65121505PC01

[0008] packing is disclosed for capturing carbon dioxide. In the 737 application, a mesh material is wetted with a carbon dioxide capture solution for capturing carbon dioxide from a dilute gas source. The mesh packing is designed to produce a film of the solution when the solution is applied continuously or intermittently to the mesh packing.

[0009] Although various carbon capturing systems have been disclosed in the past, further improvements are still needed. In particular, a need exists for a carbon capturing product and to a process for using the product that is not only efficient at capturing carbon dioxide from an air stream, but also is simple and inexpensive to implement.

[0010] SUMMARY

[0011] In general, the present disclosure is directed to a sheet product for capturing carbon components from a gas stream. For instance, in one embodiment, the sheet product can remove carbon dioxide from an air stream even when the carbon dioxide concentrations are relatively low. The present disclosure is also directed to a system and process for removing a carbon component from a gas stream using the sheet product. In one aspect, the sheet product comprises a nonwoven web with particular qualities and characteristics such that the nonwoven web can absorb and / or hold relatively great amounts of a carbon capture composition, such as an amine. The nonwoven web is also designed to release the carbon capture composition after the carbon capture composition has removed carbon dioxide from a gas stream. In this manner, the nonwoven material can serve as a carrier for the carbon capture composition in order to contact the carbon capture composition with an air stream for removing carbon dioxide from the air stream. The nonwoven material can then release the carbon capture composition so that the carbon dioxide collected by the composition can be desorbed from the composition and collected while the nonwoven material can be fed back through the process and reused. Similarly, once the carbon dioxide is collected, the carbon capture composition can also be recycled and reused. In this manner, carbon dioxide can be removed from an air stream using a relatively simple process at very low energy requirements.

[0012] In one embodiment, for instance, the present disclosure is directed to a sheet product for capturing carbon dioxide from an air stream. The sheet product includes a nonwoven material comprising a bonded carded web, a spunbond web, a spunbond-meltblown-spunbond laminate, or a coform web. The nonwoven material has a basis weight of from about 20 gsm to about 200 gsm, such as from about 30 gsm to about 100 gsm. The sheet product further comprises a carbon capture composition impregnated into the nonwoven material. The carbon capture composition is contained in the impregnated nonwoven material in an amount greater than about 40% by weight, such as in an amount greater than about 50% by weight, such as in an amount greater than about 60% by weight, such as in an amount greater than about 70% by weight, such as in an amount greater than about65121505PC01

[0013] 80% by weight.

[0014] In one aspect, the nonwoven material has a density of less than about 0.1 g / cc, such as less than about 0.07 g / cc, such as less than about 0.04 g / cc, and greater than about 0.001 g / cc. The porosity of the nonwoven material can be greater than about 97%, such as greater than about 98%. The nonwoven material can display a compression resiliency of greater than about 60%, such as greater than about 65%, such as greater than about 70%.

[0015] In one aspect, the nonwoven material comprises a bonded carded web, such as a through-air bonded carded web. In one aspect, the bonded carded web can contain hollow fibers in combination with binder fibers. The hollow fibers, for instance, can comprise polypropylene fibers and / or polyester fibers. The binder fibers, on the other hand, can comprise bicomponent fibers. In one aspect, the bicomponent fibers include a core comprised of a polyester polymer surrounded by a sheath comprised of a polyethylene polymer. In still another embodiment, the through-air bonded web can be made entirely from polyester fibers including polyester staple fibers combined with polyester binder fibers.

[0016] The carbon capture composition can contain a carbon dioxide capturing substance. The carbon dioxide capturing substance, for instance, can comprise any substance capable of forming a thin surface coating on a nonwoven substrate and can remove a carbon component from a fluid stream. The carbon dioxide capturing substance can comprise an amine, an amino acid, or an inorganic alkali. In one embodiment, the carbon dioxide capturing substance comprises a polyethyleneimine. The polyethyleneimine, for instance, can have a molecular weight of less than about 2,000 g / mol , such as less than about 1 ,500 g / mol, such as less than about 1 ,000 g / mol, and greater than about 400 g / mol, such as greater than about 600 g / mol. In an alternative embodiment, the carbon dioxide capturing substance can comprise monoethanolamine, diethanolamine, methyldiethanolamine, piperazine, aminomethyl propanol, 2-aminomethyl piperidine, p-phenylenediamine, N,N-(butane-1 ,4-diyl)bis(propane-1 ,3-diamine), or mixtures thereof.

[0017] The sheet product of the present disclosure can display a carbon dioxide uptake when contacted with an air stream containing 400 ppm of carbon dioxide of greater than about 0.8 mmol CC>2 / g sheet product, such as greater than about 1 mmol of CC>2 / g sheet product, such as greater than about 1.2 mmol CWg sheet product.

[0018] The present disclosure is also directed to a process for removing a carbon component from a gas stream using, for instance, the sheet product as described above. The process includes contacting a nonwoven material with a carbon capture composition. The carbon capture composition contains a carbon dioxide capturing substance. The nonwoven material is impregnated with the carbon capturing composition such that the impregnated nonwoven material contains the carbon65121505PC01

[0019] capturing composition in an amount of at least about 20% by weight, such as in an amount of at least about 40% by weight, such as in an amount of at least about 60% by weight. The impregnated nonwoven material is then contacted with an air stream containing carbon dioxide. The air stream is configured to flow over a surface of the impregnated nonwoven material. In one aspect, the air stream can have high humidity. For example, the air stream can have a relative humidity of greater than about 50%, such as greater than about 60%, such as greater than about 70%, such as greater than about 80%. The carbon dioxide capturing substance removes carbon dioxide from the air stream.

[0020] The impregnated nonwoven material is then compressed for removing the carbon capture composition laden with carbon dioxide. The nonwoven material can be compressed, for instance, by being fed through a nip formed between two rollers. The carbon capture composition laden with carbon dioxide or derivative thereof is collected as it is squeezed out of the nonwoven material. The carbon capture composition laden with carbon dioxide or derivative thereof is then heated causing carbon dioxide contained within the composition to be released. The carbon dioxide is then collected, such as being collected in a tank or container.

[0021] In accordance with the present disclosure, the carbon capture composition after being heated and cooled, and the nonwoven material after being compressed, can be recycled and reused in the process. For instance, the nonwoven material can then be re-impregnated with the carbon capture composition and contacted with air containing carbon dioxide. For instance, in one application, the nonwoven material can be fed to the process as a wound roll. The roll can be unwound and impregnated with the carbon capture composition. Once contacted with air and then compressed in order to remove the carbon capture composition, the nonwoven material can be rewound for reuse in the process. Alternatively, the nonwoven material can form a continuous loop that is impregnated with the carbon capture composition, contacted with air, and then compressed prior to being fed back into the process.

[0022] In one embodiment, the nonwoven material is impregnated with the carbon capture composition by being dipped into a bath containing the composition. The carbon capture composition can contain any suitable amine alone or in combination with a solvent, such as an alcohol or water. Once impregnated with the carbon capture composition, the impregnated nonwoven material can be conveyed through a chamber countercurrent to the direction of an air stream for contacting the material with the air.

[0023] Once the carbon capture composition has captured carbon dioxide from the air and removed from the nonwoven material, the carbon capture composition can be heated by being fed through a column and contacted with steam. A stream of steam and carbon dioxide is then produced that is condensed for recycling the water and collecting the carbon dioxide.65121505PC01

[0024] Other features and aspects of the present disclosure are discussed in greater detail below.

[0025] BRIEF DESCRIPTION OF THE DRAWINGS

[0026] A full and enabling disclosure of the present disclosure is set forth more particularly in the remainder of the specification, including reference to the accompanying figures, in which:

[0027] Figure 1 is a diagram illustrating one embodiment of a process and system for removing a carbon component from a gas stream in accordance with the present disclosure;

[0028] Figure 2 is a graphical representation of some of the results obtained in the example below; Figure 3 is a graphical representation of some of the results obtained in the example below; Figure 4 is a graphical representation of some of the results obtained in the example below; Figure 5 is a graphical representation of some of the results obtained in the example below; Figure 6 is a graphical representation of some of the results obtained in the example below; Figure 7 is a graphical representation of some of the results obtained in the example below; Figure 8 is a graphical representation of some of the results obtained in the example below; and

[0029] Figure 9 is a graphical representation of some of the results obtained in the example below. Repeat use of reference characters in the present specification and drawings is intended to represent the same or analogous features or elements of the present invention.

[0030] DEFINITIONS

[0031] As used herein, the term “bonded” refers to the joining, adhering, connecting, attaching, or the like, of two elements. Two elements will be considered bonded together when they are joined, adhered, connected, attached, or the like, directly to one another or indirectly to one another, such as when bonded to an intermediate element. The bonding can occur via, for example, adhesive, pressure bonding, thermal bonding, ultrasonic bonding, stitching, suturing, and / or welding.

[0032] As used herein, the term “bonded carded web” refers herein to webs that are made from staple fibers which are sent through a combing or carding unit which separates or breaks apart and aligns the staple fibers in the machine direction to form a generally machine direction oriented fibrous nonwoven web. This material may be bonded together by methods that can include point bonding, through air bonding, ultrasonic bonding, adhesive bonding, etc.

[0033] As used herein, the term “coform” refers herein to composite materials comprising a mixture or stabilized matrix of thermoplastic fibers and a second non-thermoplastic material. As an example, coform materials may be made by a process in which at least one meltblown die head is arranged near a chute through which other materials are added to the web while it is forming. Such other materials may include, but are not limited to, fibrous organic materials such as woody or non-woody pulp such as cotton, rayon, recycled paper, pulp fluff, and also superabsorbent particles, inorganic and / or organic65121505PC01

[0034] absorbent materials, treated polymeric staple fibers and so forth. Some examples of such coform materials are disclosed in U.S. Pat. No. 4,100,324 to Anderson, et al., U.S. Pat. No. 4,818,464 to Lau, U.S. Pat. No. 5,284,703 to Everhart, et al., and U.S. Pat. No. 5,350,624 to Georger, et al., each of which are incorporated herein in their entirety by reference thereto for all purposes.

[0035] As used herein, the term “conjugate fibers” refers herein to fibers which have been formed from at least two polymer sources extruded from separate extruders and spun together to form on fiber. Conjugate fibers are also sometimes referred to as bicomponent or multicomponent fibers. The polymers are arranged in substantially constantly positioned distinct zones across the cross-sections of the conjugate fibers and extend continuously along the length of the conjugate fibers. The configuration of such a conjugate fiber may be, for example, a sheath / core arrangement where one polymer is surrounded by another, or may be a side-by-side arrangement, a pie arrangement, or an “islands-in-the-sea” arrangement. Conjugate fibers are taught by U.S. Pat. No. 5,108,820 to Kaneko, et al., U.S. Pat. No. 4,795,668 to Krueger, et al., U.S. Pat. No. 5,540,992 to Marcher, et al., U.S. Pat. No. 5,336,552 to Strack, et al., U.S. Pat. No. 5,425,987 to Shawver, and U.S. Pat. No. 5,382,400 to Pike, et al., each being incorporated herein in their entirety by reference thereto for all purposes. For two component fibers, the polymers may be present in ratios of 75 / 25, 50 / 50, 25 / 75 or any other desired ratio. Additionally, polymer additives such as processing aids may be included in each zone.

[0036] As used herein, the term “machine direction” (MD) refers to the length of a fabric in the direction in which it is produced, as opposed to a “cross-machine direction” (CD) which refers to the width of a fabric in a direction generally perpendicular to the machine direction.

[0037] As used herein, the term “meltblown web” refers herein to a nonwoven web that is formed by a process in which a molten thermoplastic material is extruded through a plurality of fine, usually circular, die capillaries as molten fibers into converging high velocity gas (e.g., air) streams that attenuate the fibers of molten thermoplastic material to reduce their diameter, which may be to microfiber diameter. Thereafter, the meltblown fibers are carried by the high velocity gas stream and are deposited on a collecting surface to form a web of randomly disbursed meltblown fibers. Such a process is disclosed, for example, in U.S. Pat. No. 3,849,241 to Butin, et al., which is incorporated herein in its entirety by reference thereto for all purposes. Generally speaking, meltblown fibers may be microfibers that are substantially continuous or discontinuous, generally smaller than 10 microns in diameter, and generally tacky when deposited onto a collecting surface.

[0038] As used herein, the term “nonwoven fabric” or “nonwoven web” refers herein to a web having a structure of individual fibers or threads which are interlaid, but not in an identifiable manner as in a knitted fabric. Nonwoven fabrics or webs have been formed from many processes such as, for example, meltblowing processes, spunbonding processes, through-air bonded carded web (also65121505PC01

[0039] known as BCW and TABCW) processes, etc. The basis weight of nonwoven webs may generally vary, such as, from about 5, 10, or 20 gsm to about 120, 125, or 150 gsm.

[0040] As used herein, the term “spunbond web” refers herein to a web containing small diameter substantially continuous fibers. The fibers are formed by extruding a molten thermoplastic material from a plurality of fine, usually circular, capillaries of a spinneret with the diameter of the extruded fibers then being rapidly reduced as by, for example, eductive drawing and / or other well-known spunbonding mechanisms. The production of spunbond webs is described and illustrated, for example, in U.S. Pat. No. 4,340,563 to Appel, et al., U.S. Pat. No. 3,692,618 to Dorschner, et al., U.S. Pat. No. 3,802,817 to Matsuki, et al., U.S. Pat. No. 3,338,992 to Kinney, U.S. Pat. No. 3,341,394 to Kinney, U.S. Pat. No. 3,502,763 to Hartman, U.S. Pat. No. 3,502,538 to Levy, U.S. Pat. No. 3,542,615 to Dobo, et al., and U.S. Pat. No. 5,382,400 to Pike, et al., which are each incorporated herein in their entirety by reference thereto for all purposes. Spunbond fibers are generally not tacky when they are deposited onto a collecting surface. Spunbond fibers may sometimes have diameters less than about 40 microns, and often between about 5 to about 20 microns.

[0041] The term "pulp" as used herein refers to fibers from natural sources such as woody and non-woody plants. Woody plants include, for example, deciduous and coniferous trees. Non-woody plants include, for example, cotton, flax, esparto grass, milkweed, straw, jute, hemp, and bagasse. Pulp fibers can include hardwood fibers, softwood fibers, and mixtures thereof.

[0042] The term "average fiber length" as used herein refers to an average length of fibers, fiber bundles and / or fiber-like materials determined by measurement utilizing microscopic techniques. A sample of at least 20 randomly selected fibers is collected. For example, the fibers can be separated from a liquid suspension of fibers. The fibers are set up on a microscope slide prepared to suspend the fibers in water. A tinting dye is added to the suspended fibers to color cellulose-containing fibers so they may be distinguished or separated from synthetic fibers. The slide is placed under a Fisher Stereomaster II Microscope-S19642 / S 19643 Series. Measurements of 20 fibers in the sample are made at 20X linear magnification utilizing a 0-20 mils scale and an average length, minimum and maximum length, and a deviation or coefficient of variation are calculated. In some cases, the average fiber length will be calculated as a weighted average length of fibers (e.g., fibers, fiber bundles, fiberlike materials) determined by equipment such as, for example, a Kajaani fiber analyzer Model No. FS-200, available from Kajaani Oy Electronics, Kajaani, Finland. According to a standard test procedure, a sample is treated with a macerating liquid to ensure that no fiber bundles or shives are present. Each sample is disintegrated into hot water and diluted to an approximately 0.001% suspension. Individual test samples are drawn in approximately 50 to 100 ml portions from the dilute suspension when tested using the standard Kajaani fiber analysis test procedure. The weighted average fiber65121505PC01

[0043] length may be an arithmetic average, a length weighted average or a weight weighted average and may be expressed by the following equation:

[0044]

[0045] where

[0046] k=maximum fiber length

[0047] x fiber length

[0048] ni-number of fibers having length xi

[0049] n=total number of fibers measured.

[0050] One characteristic of the average fiber length data measured by the Kajaani fiber analyzer is that it does not discriminate between different types of fibers. Thus, the average length can represent an average based on lengths of all different types of fibers in the sample or of a single fiber type.

[0051] As used herein the term "staple fibers" means discontinuous fibers made from synthetic polymers or regenerated cellulose, such as polypropylene, polyester, post consumer recycle (PCR) fibers, polyester, nylon, viscose, rayon, and the like, and those not hydrophilic may be treated to be hydrophilic. Staple fibers may be cut fibers or the like. Staple fibers can have cross-sections that are round, bicomponent, multicomponent, shaped, hollow, or the like.

[0052] As used herein, “binder fibers” are fibers that can bond to other fibers in a substrate using chemical, mechanical, or thermal means. The binder fibers may comprise thermally bondable fibers that, when heated, form thermal bonds with other fibers at their point of intersection. In one aspect, the binder fibers include a surface polymer having a lower melting temperature. For instance, the binder fibers can be made from a polymer, such as a polyolefin, having a melting temperature of less than 200°C, such as less than 180°C, such as less than 160°C, such as less than 140°C, such as less than 120°C, such as less than 100°C, and greater than 80°C, such as greater than 90°C. In one aspect, the binder fibers comprise conjugate fibers, such as bicomponent fibers. The conjugate fibers can have a core and sheath structure, including a core polymer surrounded by a sheath polymer. The core polymer can have a higher melting temperature than the sheath polymer. The core polymer can be selected for its strength and high melting point and the sheath polymer can be made from a polymer selected for its lower melting temperature. The core polymer, for instance, can have a melting temperature higher than the sheath polymer. In this manner, the sheath polymer, when subjected to heat, melts and bonds to other fibers within the web at intersecting points. The core polymer, however, allows the bicomponent binder fiber to retain its shape and provide strength.65121505PC01

[0053] As used herein, “synthetic polymer fibers” refers to fibers made from polymers that are not binder fibers. Synthetic polymer fibers can include polyester fibers, such as fibers made from a polyethylene terephthalate polymer. Other polymer synthetic fibers include polyolefin fibers, such as polyethylene fibers, polypropylene fibers, and fibers made from copolymers of the above.

[0054] As used herein, density and percent void volume are determined as follows. To determine density and percent void volume, the width (W / ) and thickness (T / ) of the specimen may be initially measured prior to drawing. The length (L) before drawing may also be determined by measuring the distance between two markings on a surface of the specimen. Thereafter, the specimen may be drawn to initiate pore formation. The width (Wf), thickness (Tr), and length (Lf) of the specimen may then be measured to the nearest 0.01 mm utilizing Digimatic Caliper (Mitutoyo Corporation). The volume (Vi) before drawing may be calculated by W / XT / XL V / . The volume (Vr) after drawing may also be calculated by WfxT / xLF f. The density (Pr) may be calculated by PFP / AP, where P, is density of precursor material, and the percent void volume (% V ) was calculated by: % VI (1-1 / ( )X100.

[0055] As used herein, the compression resiliency of a nonwoven material is measured according to the Resiliency Test. This test measures the resiliency of a sample specimen. The thickness of the sample is first measured under a force of 166 gr for 3 seconds to obtain the Initial Thickness of the sample. A force of 11 kgr is then applied to the sample using suitable means for 30 seconds and the thickness is measured as the Compressed Thickness. The 11 kgr is then removed and the sample is allowed to expand for 5 minutes. After the 5 minutes, the thickness of the sample is again measured under a force of 166 gr for 3 seconds to obtain the Final Thickness. Suitable means for measuring the thickness include the Thickness and the Elongated Member Compression Test described above, or equivalent, modified appropriately to fulfill the requirements of this Resiliency Test. The Resilient Compression and the Resilient Expansion are then calculated using the following formulas:

[0056] Resilient Compression (%)=[(lnitial Thickness (mm)-Compressed Thickness (mm) / lnitial Thickness (mm)]x100%

[0057] Resilient Expansion (%)=Final Thickness (mm) / lnitial Thickness (mm)

[0058] DETAILED DESCRIPTION

[0059] It is to be understood by one of ordinary skill in the art that the present discussion is a description of exemplary embodiments only and is not intended as limiting the broader aspects of the present disclosure.

[0060] In general, the present disclosure is directed to a carbon capture system and process for removing gaseous carbon components from a fluid stream, such as an air stream. In accordance with65121505PC01

[0061] the present disclosure, a carbon capturing composition, which can be a liquid or solution, is impregnated into a nonwoven material. In accordance with the present disclosure, the nonwoven material is designed to absorb copious amounts of the carbon capture composition in relation to the basis weight of the material. The nonwoven material, for instance, can have a relatively high porosity, can have an affinity for the carbon capture composition, and can have a relatively large void volume. Once the carbon capture composition is loaded into the nonwoven material, the nonwoven material acts as a carrier or substrate for contacting the carbon capture composition with a gas stream containing a carbon component, such as carbon dioxide. The carbon capture composition contains at least one carbon dioxide capturing substance that can capture carbon dioxide from the gas stream. The carbon component or carbon dioxide, for instance, can be adsorbed by the carbon capture composition and / or can be converted into a carbon dioxide derivative, such as a carbamate or carbonate.

[0062] After a substantial portion of the carbon dioxide capturing substance has captured carbon dioxide, the nonwoven material is compressed so as to remove the carbon capture composition. In one aspect, for instance, the nonwoven material can be relatively resilient so that the material can be impregnated with the carbon capture composition and then compressed to remove the carbon capture composition without undergoing dramatic changes and various characteristics, such as porosity or void volume.

[0063] Once the carbon capture composition laden with carbon dioxide is released from the nonwoven material, the carbon capture composition can be subjected to a desorption process for releasing and capturing the carbon dioxide. In accordance with the present disclosure, both the nonwoven material and the carbon capture composition can then be recycled for repeating the process. In one aspect, the nonwoven material and / or the carbon capture composition can be recycled repeatedly which simplifies the process and reduces cost.

[0064] The impregnated sheet product of the present disclosure and the process and system of the present disclosure offer various advantages and benefits, especially when used in a direct air capture system. In particular, the process of the present disclosure can function utilizing relatively inexpensive materials. In addition, the materials can be recycled numerous times which further leads to cost reductions. Removing the carbon capture composition from the nonwoven material prior to desorption also reduces energy costs. For instance, the carbon capture composition laden with a carbon component, such as carbon dioxide or derivative thereof, can be fed to a stripping column alone where heat is applied to release the adsorbed carbon dioxide. The removal of the carbon dioxide from the carbon capture composition is done without having to heat the nonwoven material or any other substrates. In this manner, the amount of energy needed to heat and release the carbon dioxide from65121505PC01

[0065] the carbon capture composition is dramatically reduced.

[0066] The nonwoven material selected for use in the present disclosure should possess various characteristics and properties. The nonwoven material, for instance, should be capable of absorbing or holding significant amounts of the carbon capture composition. Thus, the nonwoven material should be compatible with the carbon dioxide capturing substance and the other components contained in the carbon capturing composition. Nonwoven materials made according to the present disclosure, for instance, can absorb the carbon capture composition such that the sheet product contains the carbon capture composition in an amount greater than about 20% by weight, such as less than about 40% by weight, such as in an amount greater than about 50% by weight, such as in an amount greater than about 60% by weight, such as in an amount greater than about 70% by weight, such as in an amount greater than about 80% by weight, such as in an amount greater than about 90% by weight, such as in an amount greater than about 95% by weight. The amount of carbon capture composition contained within the nonwoven material, for instance, can be optimized for maximizing the amount of carbon dioxide that can be captured from a gas stream, such as an air stream, based on the mass of the carbon capture composition or on the mass or area of the nonwoven material.

[0067] The nonwoven material should also be capable of releasing the carbon capture composition once the carbon capture composition has adsorbed or otherwise removed carbon dioxide from a gas stream. For instance, when compressed or squeezed, nonwoven materials according to the present disclosure can release greater than 60% by weight, such as greater than about 70% by weight, such as greater than about 80% by weight, such as greater than about 90% by weight of the carbon capture composition. Once compressed, the nonwoven material should also be resilient to the compressive forces such that the properties of the nonwoven material are not degraded during the process. For instance, nonwoven materials made according to the present disclosure can be compressed or squeezed without losing their ability to absorb the carbon capture composition. For instance, the nonwoven materials can be compressed without any significant impact on void volume or porosity. The nonwoven materials also have sufficient strength and integrity such that the materials can withstand the forces exerted on the material during the process.

[0068] Examples of nonwoven materials that can be used in the process of the present disclosure include bonded carded webs, spunbond webs, spunbond-meltblown-spunbond laminates, coform webs, and the like.

[0069] In one aspect, for instance, the nonwoven material can comprise a bonded carded web. The bonded carded web, for instance, can be through-air bonded which produces webs with significant amounts of void volume in combination with compression resilience.

[0070] In general, bonded carded webs are made from staple fibers which are typically provided in65121505PC01

[0071] bales. The bales are placed in a picker which separates the fibers. Next, the fibers are sent through a combing or carding unit which further breaks apart the lines of staple fibers in the machine direction so as to form a machine direction-oriented fibrous nonwoven web. Once the web has been formed and aligned, it is then bonded by one or more of several bonding methods. The carded web, for instance, can be bonded with an adhesive, such as a powder adhesive. The powder adhesive is distributed throughout the web and then activated, usually by heating which causes the fibers to bond together where they intersect.

[0072] Alternatively, the carded webs can be bonded using through-air bonding. During through-air bonding, heated air is forced through the web to melt and bond together binder fibers contained in the web at the crossover points. For instance, the hot air can be at a temperature of greater than about 130°C, such as greater than about 140°C, such as greater than about 150°C, and less than about 200°C, such as less than about 160°C. The web can be bonded together at very fast throughputs. For instance, bonding can occur in less than about 6 seconds, such as less than about 4 seconds. In one embodiment, the unbonded web is supported on a forming wire or drum. A vacuum can be pulled through the web to further contain the fibrous web during the bonding process. Through-air bonding may provide various advantages and benefits including the production of a web with greater loft.

[0073] The bonded carded nonwoven web can be made entirely from polymer synthetic fibers. In one aspect, the bonded carded web contains polymer staple fibers in combination with binder fibers. For instance, the binder fibers can be present in the web in an amount greater than about 10% by weight, such as in an amount greater than about 20% by weight, such as in an amount greater than about 30% by weight, such as in an amount greater than about 40% by weight, and in an amount less than about 70% by weight, such as in an amount less than about 60% by weight. The remainder of the web can comprise polymer synthetic fibers. In one aspect, for instance, the binder fibers can comprise bicomponent fibers, while the staple polymer fibers can comprise polyester fibers or polyolefin fibers. In one aspect, the staple fibers can comprise polypropylene hollow fibers or polyester hollow fibers.

[0074] In other embodiments, the nonwoven material can comprise a spunbond web. The spunbond web can be used alone or contained in a laminate as one of the layers. For instance, the nonwoven material can comprise a spunbond-meltblown-spunbond laminate.

[0075] In still another embodiment, the nonwoven material can comprise a pulp coform web having a basis weight of greater than about 20 gsm, such as greater than about 30 gsm, such as greater than about 40 gsm. The pulp coform web can have a density of from about 0.03 g / cc to about 0.05 g / cc. In one aspect, the coform web can be made from pulp fibers, such as wood pulp fibers, combined with polymer synthetic fibers, such as polymer microfibers. For example, the coform web can contain pulp65121505PC01

[0076] fibers in an amount greater than about 40% by weight, such as in an amount greater than about 50% by weight, such as in an amount greater than about 60% by weight, such as in an amount greater than about 70% by weight, and in an amount less than about 90% by weight, such as in an amount less than about 80% by weight. The polymer synthetic fibers, which can comprise polypropylene microfibers, can comprise the rest of the coform web and can be present in an amount from about 60% by weight to about 20% by weight, including all increments of 1% by weight therebetween.

[0077] One particular example of a nonwoven material that can be used in accordance with the present disclosure comprises a through-air bonded carded web comprised of a blend of hollow polymer fibers, such as polypropylene fibers or polyester fibers, combined with bicomponent fibers, such as bicomponent fibers including a polyethylene sheath and a polyester core. The bonded carded web can have a basis weight of from about 35 gsm to about 100 gsm. The fibers contained in the web can form a homogenous blend containing from about 55% by weight to about 65% by weight hollow polymer fibers having a denier of from about 2 to about 8 and having an average fiber length of from about 30 mm to about 50 mm. The bicomponent fibers can be present in an amount from about 35% by weight to about 45% by weight and can have a size of from about 1 denier to about 7 denier and an average fiber length of from about 30 mm to about 50 mm. Optionally, the fibers contained within the bonded carded web can include a coating or finish which makes them more hydrophilic.

[0078] Alternatively, the nonwoven material can comprise a spunbond web comprised of polypropylene fibers. The polypropylene fibers can have a circular cross-section or, alternatively, can have a multi-lobal cross-sectional shape, such as a tri-lobal shape. The spunbond web can have a bulk density of from about 0.05 g / cc to about 0.12 g / cc.

[0079] In another aspect, the nonwoven material can comprise a pulp coform web. The pulp coform web can contain from about 45% by weight to about 75% by weight cellulose fluff and from about 25% by weight to about 55% by weight meltblown fibers of polypropylene.

[0080] In another embodiment, the nonwoven material may comprise a through-air bonded carded web made of bicomponent binder fibers and polyester fibers. The bicomponent fibers can be present in an amount from about 55% by weight to about 65% by weight and can have a size of about 2 denier to about 6 denier. The bicomponent fibers can have a polypropylene core and a polyethylene sheath. The polyester fibers can comprise the remainder of the web and can have a size of from about 4 denier to about 8 denier. Alternatively, the polyester fibers can be replaced with hollow polypropylene fibers having a size of from about 3 denier to about 9 denier.

[0081] Whether the nonwoven material contains a bonded carded web, a spunbond web, a coform web, or a laminate, the nonwoven material generally has a basis weight of greater than about 20 gsm, such as greater than about 30 gsm, such as greater than about 35 gsm, such as greater than about 4065121505PC01

[0082] gsm, and less than about 200 gsm, such as less than about 150 gsm, such as less than about 100 gsm, such as less than about 90 gsm, such as less than about 80 gsm, such as less than about 70 gsm. When tested at 0.01 psi, the nonwoven material can display a surface area per void volume of greater than about 10 cm2 / cm3, such as greater than about 15 cm2 / cm3, such as greater than about 20 cm2 / cm3, such as greater than about 25 cm2 / cm3, such as greater than about 30 cm2 / cm3, such as greater than about 35 cm2 / cm3, such as greater than about 40 cm2 / cm3, such as greater than about 45 cm2 / cm3, and less than about 60 cm2 / cm3.

[0083] The nonwoven material can display a porosity of greater than about 90%, such as greater than about 93%, such as greater than about 95%, such as greater than about 97%, such as greater than about 98%, such as greater than about 98.5%, such as greater than about 99%. The density of the nonwoven material can be less than about 0.1 g / cc, such as less than about 0.07 g / cc, such as less than about 0.04 g / cc, such as less than about 0.01 g / cc, and generally greater than about 0.001 g / cc.

[0084] Nonwoven materials selected in accordance with the present disclosure can also have resilient properties. For instance, the nonwoven material can display a compression resiliency of greater than about 60%, such as greater than about 65%, such as greater than about 70%, such as greater than about 72%, such as greater than about 75%, and generally less than about 95%.

[0085] The nonwoven material can also have an affinity for the carbon capture composition. For instance, when tested against a polyethyleneimine having an average molecular weight of 800 g / mol, the nonwoven material can display a contact angle of less than about 40, such as less than about 35, such as less than about 30, such as less than about 25, such as less than about 20, such as less than about 15, such as less than about 10.

[0086] The carbon capture composition as described above contains a carbon dioxide capturing substance. The carbon dioxide capturing substance can be any suitable material capable of removing carbon dioxide from an air stream, capable of being absorbed by the nonwoven material, and capable of being released from the nonwoven material after capturing carbon dioxide from an air stream. In one aspect, the carbon dioxide capturing substance can comprise an amino acid, an inorganic alkali, or a liquid amine. Liquid amines are capable of selectively removing carbon dioxide from gas streams. Amines are nitrogen-containing compounds that can chemically react with carbon dioxide. For instance, the carbon dioxide can be converted to a carbon dioxide derivative, such as a carbamate or a carbonate. Once the amines have captured carbon dioxide, the amines can be heated for reversing the reaction and releasing the carbon dioxide for collection.

[0087] In one aspect, for instance, an amine can be selected that captures carbon dioxide through chemical absorption. When contacted with a gas stream containing carbon dioxide, the amine chemically reacts with the carbon dioxide forming carbamates and / or bicarbonates. This reaction65121505PC01

[0088] binds the carbon dioxide to the liquid phase. The carbon dioxide-rich or laden amine solution is then heated to reverse the chemical reaction. The released species is carbon dioxide which can be captured and stored. The regenerated amine can then be recycled back to the process for reuse.

[0089] A variety of different types of amines can be used and incorporated into the carbon capture composition of the present disclosure. For instance, the amine can be a monoethanolamine, which is a primary amine that is effective at capturing carbon dioxide. Monoethanolamine reacts with carbon dioxide to form a stable carbamate. Alternatively, the amine can comprise a diethanolamine, which is a secondary amine. Diethanolamine also forms carbamates with carbon dioxide. A tertiary amine that can be used in the process is methyldiethanolamine. Methyldiethanolamine reacts with carbon dioxide to form bicarbonate ions, a carbonate, a carbamate and / or a carbamic acid. Methyldiethanolamine may be preferred in some processes because it requires low energy for regeneration.

[0090] In still another aspect, the carbon dioxide capture substance can comprise a piperazine. The piperazine can be used alone or in combination with other amine blends to enhance the absorption rate of carbon dioxide. For instance, piperazine can improve the performance of monoethanolamine or methyldiethanolamine.

[0091] Another amine that can be used in the process is aminomethyl propanol. Further examples include 2-aminomethyl piperidine, p-phenylenediamine, N,N-(butane-1 ,4-diyl)bis(propane-1 ,3-diamine), or mixtures thereof In still another embodiment, the amine can be a hyperbranched amino polymer.

[0092] Preferred amines for use in the carbon capture composition include liquid polyamines, such as a polypropyleneimine or a polyethyleneimine. Polyethyleneimines, for instance, contain numerous amine groups along its backbone. The amine groups can comprise primary, secondary, and tertiary amines. Consequently, polyethyleneimine is highly reactive towards carbon dioxide. For example, due to its high density of amine groups, polyethyleneimine can efficiently capture carbon dioxide from gas streams. Polyethyleneimines can interact with carbon dioxide in multiple ways. For instance, polyethyleneimines can capture carbon dioxide and form carbamates or bicarbonates.

[0093] In one aspect, a polyethyleneimine or polypropyleneimine is selected for use in the present disclosure that has a relatively low molecular weight. For instance, the molecular weight of the polyethyleneimine or polypropyleneimine can be less than about 25,000 g / mol, such as less than about 10,000 g / mol, such as less than about 5,000 g / mol, such as less than about 2,000 g / mol, such as less than about 1 ,500 g / mol, such as less than about 1 ,000 g / mol, and greater than about 500 g / mol, such as greater than about 600 g / mol. The polyethyleneimine or polypropyleneimine can be a branched polyethyleneimine or polypropyleneimine or a linear polyethyleneimine or

[0094] polypropyleneimine.65121505PC01

[0095] The carbon capture composition can contain a carbon dioxide capturing substance alone or in combination with various other components. For instance, other components that can be contained in the carbon capture composition include solvents, surfactants, and wetting agents. In one embodiment, for instance, an amine, such as a polyethyleneimine, can be combined with a solvent that is impregnated into the nonwoven material. The solvent can comprise, for instance, an alcohol or other volatile species that can evaporate during the process. In one aspect, for instance, the solvent can comprise methanol. When combined with an amine, such as a polyethyleneimine, the solvent can be present generally in an amount of greater than about 10% by weight, such as greater than about 20% by weight, and in an amount less than about 60% by weight, such as less than about 40% by weight, such as less than about 30% by weight.

[0096] An impregnated nonwoven material made in accordance with the present disclosure can be used in numerous processes and systems for capturing a carbon component from a gas stream. In one aspect, for instance, the impregnated nonwoven material can be used to capture carbon dioxide from an air stream in a direct air capture process.

[0097] For instance, referring to FIG. 1, one embodiment of a process and system for capturing carbon dioxide from a gas stream is shown. As illustrated, the process can include an unwind station 10 for unwinding a roll of nonwoven material 12 for feeding the material into the process. The nonwoven material 12 can be any of the nonwoven materials described above and can comprise, for instance, a through-air bonded carded web. The nonwoven material can be impregnated with a carbon capture composition using any suitable method or technique. In FIG. 1, for instance, the nonwoven material 12 is fed into a dip tank 14 for contact with a carbon capture composition 16 containing one or more carbon dioxide capturing substances. The carbon dioxide capturing substance, for instance, may comprise a polyethyleneimine or polypropyleneimine. The carbon capture composition 16, in one embodiment, can comprise more than one carbon dioxide capturing substances. Alternatively, the carbon capturing composition 16 can contain one or more solvents, surfactants, or wetting agents.

[0098] After the nonwoven material 12 is impregnated with the carbon capturing composition 16, the impregnated nonwoven material 18 can optionally be fed through a nip roller 20. The nip roller 20, for instance, can be used to remove or squeeze out excess carbon capture composition from the nonwoven material. The nip roller 20, for instance, can include a gap nip for applying a selected amount of pressure onto the nonwoven material 18 to remove excess composition while ensuring that the nonwoven material contains copious amounts of the carbon capture composition. In this manner, the nip roller 20 can control the amount of carbon capture composition contained within the nonwoven material 12. For example, the impregnated nonwoven material 18 can contain the carbon capture65121505PC01

[0099] composition 16 in an amount greater than about 40% by weight, such as in an amount greater than about 60% by weight, such as in an amount greater than about 70% by weight, such as in an amount greater than about 80% by weight, such as even in an amount greater than about 90% by weight. The nip roller 20 can also be used to ensure that the carbon capture composition 16 is uniformly impregnated within the nonwoven material 12.

[0100] The impregnated nonwoven material 18 is then fed into a chamber 24 and contacted with a gas stream, such as an air stream 26. In one embodiment, the impregnated nonwoven material 18 can be fed through the chamber 24 on a conveyor including a carrier belt 22. The carrier belt 22 can be porous or non-porous. The carrier belt 22, for instance, may not only convey the impregnated nonwoven material 18 at a desired rate but may also cause agitation that further improves performance of the impregnated nonwoven material in capturing carbon dioxide. The nonwoven material can be conveyed through the chamber in one pass or can be fed through the chamber multiple times in a back and forth motion or any other suitable pattern.

[0101] As shown, the chamber 24 is in fluid communication with a fan 28. The fan 28 produces the air flow 26. In the embodiment illustrated in FIG. 1 , the air flow 26 is countercurrent to the direction of movement of the impregnated nonwoven material 18. Optionally, the chamber can include one or more air filters, such as a first air filter 30 and a second air filter 32. The air filters 30 and 32 can filter the air flow 26 prior to entering the chamber 24 and as the air flow 26 exits the chamber 24.

[0102] As shown, the air flow 26 is blown such as counter-currently across the surface of the impregnated nonwoven material 18. The configuration of the chamber, the speed of the impregnated nonwoven material 18 and other factors can be used to tune the residence time or the length of time needed for capturing carbon dioxide from the air stream 26. The residence time, for instance, can be greater than about 2 seconds, such as greater than about 4 seconds, such as greater than about 6 seconds, such as greater than about 10 seconds, such as greater than about 12 seconds, and less than about 60 seconds, such as less than about 40 seconds, such as less than about 30 seconds, such as less than about 20 seconds. Of particular advantage, the carbon dioxide is removed from the air stream 26 with little or no resistance by being contacted with the surface of the impregnated nonwoven web 18 instead of being filtered through the nonwoven web. In this manner, energy requirements are reduced regarding the amount of force needed by the fan 28 for creating the air flow 26.

[0103] As shown in FIG. 1, the impregnated nonwoven material 18 exits the chamber 24 and is then compressed for removing the carbon dioxide loaded carbon capture composition. The impregnated nonwoven material 18 can be compressed using any suitable method or technique. In the embodiment illustrated in FIG. 1, for instance, the impregnated nonwoven material 18 is fed through a65121505PC01

[0104] second nip roller 34 for squeezing the impregnated nonwoven material 18 and removing the carbon capture composition 16. The nip roller 34 can be comprised of two opposing rolls that apply sufficient pressure to the impregnated nonwoven material 18 for removing a substantial amount of the carbon capture composition. For instance, during the process, at least 40% by weight, such as at least about 60% by weight, such as at least about 70% by weight, such as at least about 80% by weight, such as at least about 90% by weight of the carbon capture composition is removed from the nonwoven material 12 when compressed. The nonwoven material 12, after being compressed, can then be fed to a wind station and wound into a roll of material for reuse in the process. Alternatively, the nonwoven material 12 can form a continuous and endless loop that recycles through the process.

[0105] After the carbon dioxide laden carbon capture composition 16 is removed from the nonwoven material 12, the composition can be collected and fed to a desorption process. For instance, as shown in FIG. 1, the carbon capture composition 16 can be pumped using a pumping device 38 to a steam column 40 where the composition is heated by direct contact with steam. When using an amine as the carbon dioxide capturing substance, the carbon dioxide captured by the amine can be released by heating the amine. In general, the carbon capture composition can be heated using any suitable method or technique. In FIG. 1 , however, the carbon capture composition is fed to the top of the column 40 through a column inlet 48 and steam at a desired temperature is fed to the bottom of the column 40 through a steam inlet 46. Within the column 40, the carbon capture composition combines with the steam and is heated causing the carbon capture composition to release carbon dioxide. The carbon capture composition 16 then exits the column through a column outlet 42 and recycled back to the dip tank 14. As shown in FIG. 1 , in one embodiment, a heat exchanger 44 can be used to remove heat from the heated carbon capture composition and preheat the carbon dioxide laden carbon capture composition that just exited the chamber 24.

[0106] Within the column 40, steam and carbon dioxide can be fed to a condenser 50. The condenser 50 can condense the steam for recovering the water. The carbon dioxide remains as a gas and exits through the top of the condenser 50 and can be collected in tanks or any other suitable collection device. The water exiting the condenser 50 can then be recycled and reused as steam that is fed to the column 40.

[0107] As shown in FIG. 1, in one embodiment, multiple impregnated nonwoven materials 18 can be fed to the chamber 24 for contact with the air stream 26. In the embodiment illustrated in FIG. 1, for instance, a second impregnated nonwoven material 18 is fed to the chamber 24 above the first impregnated nonwoven material 18. The first impregnated nonwoven material 18 and the second impregnated nonwoven material 18 can be spaced apart for forming an air channel through which the air flow 26 is directed. In this manner, the air flow 26 can be contacted with more than one65121505PC01

[0108] impregnated product made in accordance with the present disclosure. For instance, the chamber 24 can include at least two impregnated products, such as at least three, such as at least four, such as at least five, such as at least six, such as at least about eight impregnated products that form air channels within the chamber.

[0109] Impregnated nonwoven webs made according to the present disclosure are well suited for capturing and removing carbon dioxide from a gas stream. For instance, when contacted with an air stream containing 400 ppm CO2, the impregnated nonwoven material can capture at least about 0.5 mmol CO2 / g sheet product, such as greater than about 0.7 mmol CCh / g sheet product, such as greater than about 0.8 mmol CC / g sheet product, such as greater than about 0.9 mmol CC / g sheet product, such as greater than about 1 mmol CWg sheet product, such as greater than about 1.1 mmol CWg sheet product, such as greater than about 1 .2 mmol CC / g sheet product, and generally less than about 5 mmol CWg sheet product.

[0110] The present disclosure may be better understood with reference to the following examples.

[0111] Example No. 1

[0112] Different nonwoven materials were constructed and impregnated with a carbon capture composition in accordance with the present disclosure. The nonwoven material and the impregnated nonwoven material were subjected to various tests. The carbon capture composition contained a polyethyleneimine having a molecular weight of 800 g / mol and was acquired from Sigma Aldrich. The following tests were conducted.

[0113] Contact Angle of Water and PEI on Nonwovens

[0114] Contact angles for water and PEI were measured using a Rame-hart NA CA goniometer (100-0-115) with an Olympus TBHM back light. First, small samples of nonwoven were placed under a syringe containing the liquid. Droplets of liquid were released onto the nonwoven, and the contact angle was quickly measured through the microscope before evaporation could occur. Three trials were performed for each nonwoven and liquid combination, allowing average contact angles to be calculated.

[0115] Liquid Water Uptake of Nonwovens

[0116] To measure water uptake, the dry weight of the nonwoven samples was first measured as a reference. The samples were dipped into a beaker of water for approximately 15 seconds and then weighed again. Three trials were performed for each nonwoven. Using the differences in weight, the weight percentage increase due to water was calculated using the difference between the dry and wet weights.

[0117] Polyamine Release Capability of Nonwovens65121505PC01

[0118] To measure the polyamine release or “squeezability”, the samples were first loaded with PEI. The initial dry weight was measured, and then the nonwoven samples were dipped in PEI for about 15 seconds before weighing again. PEI was then squeezed out using tweezers onto a KimWipe. The samples were weighed once again, and the difference in weight was used to calculate the percentage of the PEI that was squeezed out.

[0119] CO2 Adsorption Performance of PEI-Loaded Nonwovens

[0120] The gravimetric CO2 uptake of the PEI-loaded nonwovens was assessed on TA Instruments TGA 550. This involved a series of trials with various nonwovens and PEI loadings. Nonwoven samples were weighed and then dipped in PEI for approximately 15 seconds. Specific amounts of PEI were then either squeezed out or using the dilution method below (section 2.6) to achieve specific PEI loadings. The TGA procedure was as follows: (1) isothermal flow of nitrogen at 100 mL / min for 30 minutes to purge furnace, (2) temperature increase to 60 °C at a ramp rate of 5 °C / min, (3) isothermal at 60 °C for 180 minutes to desorb CO2 and H2O, (4) temperature decrease to 50 °C at a ramp rate of 10 °C / min, (5) equilibration at 50 °C, (6) isothermal flow of 400 ppm CO2 at 500 mL / min for 1300 minutes

[0121] Dilution of PEI

[0122] A dilution method was used to fabricate PEI-nonwoven samples with low amounts of PEI and ultimately create a broader range of PEI loadings. Mixtures of differing fractions of PEI and methanol (MeOH) were created. Samples of TABCW and 56 gsm coform nonwovens were dipped into the liquid mixtures, and the methanol was allowed to evaporate to achieve the desired PEI loading Thermogravimetric analysis

[0123] Combustion thermogravimetric analysis was performed for PEI-nonwoven samples. The TGA procedure for combustion analysis was as follows: (1) 90 mL / min air flow (10 mL / min balance N2 flow) while increasing temperature to 100 °C at a ramp rate of 10°C / min, (2) isothermal for 30 minutes to desorb water and CO2 (and evaporate methanol in dilution samples), (3) increase in temperature to 400 °C at a ramp rate of 3 °C / min, (4) increase in temperature to 700 °C at a ramp rate of 5 °C / min, (5) decrease in temperature to 30 °C at a ramp rate of 20 °C / min. TGA runs were also performed on dry nonwoven samples with an identical procedure excluding the increase in temperature to 400 °C at a ramp rate of 3 °C / min, which instead was done at a ramp rate of 10 °C / min. PEI loadings were calculated using measured weights once all methanol had burned off during the TGA runs.

[0124] Three different nonwoven materials were tested and evaluated including coform webs, a spunbond-meltblown-spunbond laminate (SMS), and a through-air bonded carded web (TABCW).

[0125]

[0126] 65121505PC01

[0127]

[0128] Combustion profiles for each dry nonwoven are shown in FIG. 2, which display the derivative weight change versus temperature. Differences in decomposition maxima resulted from the varying materials used to form the nonwovens. For example, the cellulose pulp and polypropylene components of the coform nonwovens each contain a corresponding decomposition maximum at approximately 210 °C (polypropylene) and 315 °C (cellulose pulp). TABCW shares the same decomposition maximum at 210 °C for polypropylene, along with a polyethylene maximum at slightly higher temperatures.

[0129] Contact angle measurements were performed for both water and polyethyleneimine (PEI) on the nonwovens. The contact angle evaluates the hydrophobicity of the nonwovens. Contact angles for both PEI and water are highest for SMS, second highest for coform, and lowest for TABCW (FIG.

[0130] 3). All of the samples were hydrophobic, as expected since polypropylene and polyethylene are both hydrophobic (with polypropylene being slightly more hydrophobic). Cellulose pulp, found in the coform samples, is hydrophilic.

[0131] Surprisingly, PEI on TABCW exhibited high wettability with a contact angle of zero, while the other samples exhibited some resistance to spreading.

[0132] Water uptake measurements were also used to evaluate the hydrophilicity of the nonwovens (FIG.4). Despite their hydrophobicity, most of the nonwovens held an appreciable amount of water. The liquid water uptake was highest for TABCW, second highest for coform, and lowest for SMS; this trend is opposite that of the water contact angle measurements. As the density of coform increased, the liquid water uptake decreased, again consistent with the contact angle measurements.65121505PC01

[0133] The "squeezability", or how much PEI could be squeezed from each nonwoven (FIG. 5). Most of the nonwovens, with the exception of 60 gsm coform, released over 60% of the initial PEI loading when squeezed. There was a relationship between coform density and PEI released; as coform density increased, PEI released decreased. This suggests that (1) polyamine-nonwoven interactions play a vital role in the amount of PEI released and (2) that lower nonwoven densities could be favorable for increasing the nonwoven's release properties, or ’’squeezability.”

[0134] Notably, TABCW had the highest amount of PEI released compared to other nonwovens, despite having a similar density.

[0135] Polyamine solutions with varying concentrations were used to dictate the amount of polyamine loading on the nonwoven. Higher concentrations of polyamine in methanol were expected to result in higher polyamine loadings. PEI loadings were measured through combustion analysis of each combination of nonwoven and PEI / methanol sample, and FIG. 6 shows the PEI loading as a function of the weight fraction of PEI in each PEI / methanol solution. As expected, PEI loadings increase with PEI weight fraction in solution for all nonwovens. However, there are diminishing returns for solutions greater than 40 wt.% PEI in methanol. Specifically, increasing the PEI concentration from 5 to 40 wt.% can increase the PEI loading by almost 60 wt.%, while increasing the PEI concentration from 40 to 90 wt.% increases the PEI loading by less than 20 wt.% PEI loadings are highest for TABCW, second highest for 56 gsm coform, and lowest for SMS. These results illustrate the range of PEI loadings possible for each nonwoven type.

[0136] FIG. 7 (7a, 7b, and 7c) depicts combustion analyses of the three different nonwoven types for varying PEI loadings, used to calculate the PEI loading. The derivative weight change is shown as a function of temperature. Although the general shape for each profile is similar, the maxima location changed with different amounts of PEI. This could indicate morphological changes for the PEI in the nonwovens as the PEI loading is increased.

[0137] The CO2 adsorption performance of the PEI-nonwoven samples was evaluated through gravimetric CO2 uptake measurements. FIG. 8 (8a and 8b) shows the CO2 uptake per mass of polyamine-nonwoven (Fig. 8a) and per mole of nitrogen (FIG. 8b, amine efficiency) as a function of exposure time. TABCW exhibited the highest CO2 uptake, followed by SMS and coform.

[0138] Squeezability measurements for specific nonwovens were collected and analyzed alongside the CO2 uptake results. As expected, squeezability and CO2 uptake followed opposite trends, with squeezability increasing and CO2 uptake decreasing as PEI loading increased (FIG. 9). Squeezability dictates the recyclability of the PEI and nonwoven, and the CO2 uptake determines the efficiency of the process. An optimal range for maximizing recyclability and efficiency approximately falls between 85% and 95% PEI loading. These values represented the ability of the nonwovens to release PEI, therefore65121505PC01

[0139] acting as an assessment of both the PEI's and the nonwoven's recyclability in the process.

[0140] These and other modifications and variations to the present invention may be practiced by those of ordinary skill in the art, without departing from the spirit and scope of the present invention, which is more particularly set forth in the appended claims. In addition, it should be understood that aspects of the various embodiments may be interchanged both in whole or in part. Furthermore, those of ordinary skill in the art will appreciate that the foregoing description is by way of example only, and is not intended to limit the invention so further described in such appended claims.

Claims

65121505PC01What Is Claimed:

1. A sheet product for capturing carbon dioxide from an air stream comprising:a nonwoven material comprising a bonded carded web, a spunbond web, a spunbond-meltblown-spunbond laminate, or a coform web, the nonwoven material having a basis weight of from about 20 gsm to about 200 gsm; anda carbon capture composition impregnated into the nonwoven material, the carbon capture composition being contained in the impregnated nonwoven material in an amount of greater than about 20% by weight.2 A sheet product as defined in claim 1 , wherein the nonwoven material comprises the bonded carded web.

3. A sheet product as defined in claim 1 , wherein the carbon capture composition comprises an amine.

4. A sheet product as defined in claim 1 , wherein the carbon capture composition comprises monoethanolamine, diethanolamine, methyldiethanolamine, piperazine, aminomethyl propanol, 2-aminomethyl piperidine, p-phenylenediamine, N,N-(butane-1 ,4-diyl)bis(propane-1 ,3-diamine), or mixtures thereof.

5. A sheet product as defined in claim 1 , wherein the carbon capture composition comprises a liquid or gel comprising polyethyleneimine or polypropyleneimine.

6. A sheet product as defined in claim 1 , wherein the sheet product displays a carbon dioxide uptake when contacted with an air stream containing 400 ppm of carbon dioxide of greater than about 0.8 mmol of CWg sheet product, such as greater than 1.0 mmol of CWg sheet product, such as greater than about 1.2 mmol of CCte / g sheet product.

7. A sheet product as defined in claim 2, wherein the bonded carded web is through-air bonded.

8. A sheet product as defined in claim 1 , wherein the nonwoven material displays a compression resiliency of greater than about 60%, such as greater than about 65%, such as greater than about 70%.

9. A sheet product as defined in claim 1 , wherein the carbon capture composition is contained in the sheet product in an amount greater than about 50% by weight, such as in an amount greater than about 60% by weight, such as in an amount greater than about 70% by weight, such as in an amount greater than about 80% by weight.

10. A sheet product as defined in claim 1, wherein the nonwoven material has a density of less than about 0.1 g / cc, such as less than about 0.07 g / cc, such as less than about 0.04 g / cc, and greater than about 0.001 g / cc, and displays a porosity of greater than about 97%, such as greater than65121505PC01about 98%.

11. A sheet product as defined in claim 2, wherein the bonded carded web contains hollow synthetic polymer fibers combined with binder fibers, the hollow synthetic polymer fibers comprising polypropylene fibers, polyester fibers, or mixtures thereof.

12. A sheet product as defined in claim 11, wherein the binder fibers comprise bicomponent fibers.

13. A process for removing carbon dioxide from a gas stream comprising: contacting a nonwoven material with a carbon capture composition, the carbon capture composition containing a carbon dioxide capturing substance, the nonwoven material being impregnated with the carbon capture composition such that the impregnated nonwoven material contains the carbon capture composition in an amount of at least about 20% by weight;contacting the impregnated nonwoven material with an air stream containing carbon dioxide, the air stream flowing over a surface of the impregnated nonwoven material, the carbon dioxide capturing substance removing carbon dioxide from the air stream;compressing the impregnated nonwoven material for removing the carbon capture composition laden with carbon dioxide or derivative thereof;heating the carbon capture composition laden with carbon dioxide causing carbon dioxide to be released from the carbon dioxide capturing substance; andrecycling the carbon capture composition after releasing the carbon dioxide for reapplication to the nonwoven material.

14. A process as defined in claim 13, wherein the nonwoven material is contacted with the carbon capturing composition by being dipped into a bath containing the carbon capturing composition.

15. A process as defined in claim 13, wherein the impregnated nonwoven material is conveyed through a chamber countercurrent to the direction of flow of the air stream.

16. A process as defined in claim 13, wherein the nonwoven material is unwound from a roll and contacted with the carbon capture composition and is later rewound into a roll for reuse after the impregnated nonwoven material is compressed for removing the carbon capture composition.

17. A process as defined in claim 13, wherein the nonwoven material is in the form of a continuous loop that is contacted with the carbon capture composition, then contacted with the air stream containing carbon dioxide, and then compressed to remove the carbon capture composition and then contacted with the gas capture composition for repeating the process.

18. A process as defined in claim 13, wherein the impregnated nonwoven material is compressed by being fed through a nip for removing the carbon capture composition laden with carbon dioxide.65121505PC0119. A process as defined in claim 13, wherein the carbon capture composition laden with carbon dioxide is heated by being fed to a column and contacted with steam.

20. A process as defined in claim 13, further comprising the step of collecting the carbon dioxide released from the carbon dioxide capturing substance.

21. A process as defined in claim 19, wherein the steam and carbon dioxide mixture are cooled causing the steam to condense and separate from the carbon dioxide and wherein the carbon dioxide is collected.

22. A process as defined in claim 13, wherein the nonwoven material comprises a bonded carded web23. A process as defined in claim 13, wherein the carbon capture composition comprises an amine.

24. A process as defined in claim 13, wherein the carbon capture composition comprises monoethanolamine, diethanolamine, methyldiethanolamine, piperazine, aminomethyl propanol, 2-aminomethyl piperidine, p-phenylenediamine, N,N-(butane-1 ,4-diyl)bis(propane-1 ,3-diamine), or mixtures thereof.

25. A process as defined in claim 13, wherein the carbon capture composition comprises polyethyleneimine or polypropyleneimine.

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