Porous spacers for direct air capture sheets and parallel contactors

Abstract

The present disclosure provides porous spacers for a direct air capture sheet including carbon dioxide-sorbent particles distributed in a polymeric matrix. The porous spacer has a form of strips and / or dots. Parallel contactors are also provided, including spaced apart carbon dioxide-sorbent sheets. Directly adjacent carbon dioxide-sorbent sheets are spaced from each other by the porous spacers.

Description

[0001] POROUS SPACERS FOR DIRECT AIR CAPTURE SHEETS AND PARALLEL CONTACTORS

[0002] Summary

[0003] In a first aspect, a plurality of porous spacers for a direct air capture sheet is provided. The porous spacers each comprise a plurality of carbon dioxide-sorbent particles distributed in a polymeric matrix, the porous spacers having a form of a plurality of strips and / or dots.

[0004] In a second aspect, a parallel contactor is provided. The parallel contactor comprises a plurality of spaced carbon dioxide-sorbent sheets, wherein directly adjacent carbon dioxide-sorbent sheets are spaced from each other by a plurality of any of the porous spacers according to the first aspect.

[0005] The above summary of the present disclosure is not intended to describe each disclosed embodiment or every implementation of the present disclosure. The description that follows more particularly exemplifies illustrative embodiments. In several places throughout the application, guidance is provided through lists of examples, which examples may be used in various combinations. In each instance, the recited list serves only as a representative group and should not be interpreted as an exclusive list.

[0006] Brief Description of the Drawings

[0007] FIG. 1 is a photograph of a plurality of exemplary porous spacers each having a form of dots;

[0008] FIG. 2 is a photograph of a plurality of exemplary porous spacers each having a form of strips;

[0009] FIG. 3 is a schematic perspective view of an exemplary parallel contactor;

[0010] FIG. 4 is a schematic cross-sectional view of another exemplary parallel contactor; and

[0011] FIG. 5 is a schematic cross-sectional view of a further exemplary parallel contactor.

[0012] While the above-identified figures set forth various embodiments of the disclosure, other embodiments are also contemplated, as noted in the description. In all cases, this disclosure presents the invention by way of representation and not limitation. The figures are not necessarily to scale. Like numbers used in the figures refer to like components. However, it will be understood that the use of a number to refer to a component in a given figure is not intended to limit the component in another figure labeled with the same number.

[0013] Detailed Description

[0014] Glossary:

[0015] The term “carbon dioxide-sorbent” refers to a material that is capable of reversibly sorbing and desorbing carbon dioxide molecules.

[0016] The term “dot” refers to a generally round, spherical, or conical shape.

[0017] The term “strip” refers to a shape that has an aspect ratio of length to width of at least 2:1.

[0018] The term “length” refers to the longest dimension of an object. The term “sheet” refers to a layer that has a substantially larger length and width than height (e.g., substantially larger in the x-y plane than the z-plane).

[0019] The term “agglomerated” refers to a weak association of primary particles or aggregated particles usually held together by charge or polarity. Agglomerated particles can typically be broken down into smaller entities by, for example, shearing forces encountered during dispersion of the agglomerated particles in a liquid.

[0020] The terms “aggregated” and “aggregates” refer to a strong association of primary particles often bound together by, for example, residual chemical treatment, covalent chemical bonds, or ionic chemical bonds. Further breakdown of the aggregates into smaller entities is very difficult to achieve.

[0021] The term “alkyl” refers to a monovalent group that is a radical of an alkane, which is a saturated hydrocarbon. The alkyl can be linear, branched, cyclic, or combinations thereof and typically has 1 to 20 carbon atoms. In some embodiments, the alkyl group contains 1 to 18, 1 to 12, 1 to 10, 1 to 8, 1 to 6, or 1 to 4 carbon atoms. Examples of alkyl groups include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, n-hexyl, cyclohexyl, n-heptyl, n-octyl, ethylhexyl, n- dodecyl, 2-dodecyl, 3-dodecyl, 4-dodecyl, and 5-dodecyl.

[0022] The term “alkylene” is the multivalent (e.g., divalent or trivalent) form of the “alkyl” groups defined above.

[0023] The term “(meth)acrylate” refers to monomeric acrylic or methacrylic esters of alcohols. Acrylate and methacrylate monomers or oligomers are referred to collectively herein as "(meth)acrylates”. Materials referred to as “(meth)acrylate-based” are materials that contain one or more (meth)acrylate and may contain additional co-polymerized free radically polymerizable materials.

[0024] The terms “free radically polymerizable” and “ethylenically unsaturated” are used interchangeably and refer to a reactive group which contains a carbon-carbon double bond which is able to be polymerized via a free radical polymerization mechanism.

[0025] The term “branched” when used to describe an alkyl (meth)acrylate refers to the alkyl group, where the branching is not present at the carbon directly adjacent to the ester group, i.e. H2C=CR1-C(O)-O-CH2- Ra, where C(O) refers to a carbonyl group C=O, and the branching occurs in the Ragroup. This is in contrast to a secondary alkyl (methjacrylate where there are 2 alkyl groups bonded to the carbon directly adjacent to the ester group, i.e. H2C=CR1-C(O)-O-CRbRc, where C(O) refers to a carbonyl group C=O,and Rband Rcare each alkyl groups.

[0026] The term “amino-functionalized” refers to attachment of a moiety including at least one primary amine, secondary amine, and / or tertiary amine functional group, e.g., to a polymer, metal oxide particle, etc.

[0027] The terms “room temperature” and “ambient temperature” are used interchangeably to mean temperatures in the range of 20°C to 25°C.

[0028] The term “adjacent” as used herein when referring to two layers means that the two layers are in proximity with one another with no intervening open space between them. They may be in direct contact with one another (e.g., laminated together) or there may be intervening layers. The terms “polymer” and “macromolecule” are used herein consistent with their common usage in chemistry. Polymers and macromolecules are composed of many repeated subunits. As used herein, the term “macromolecule” is used to describe a group attached to a monomer that has multiple repeating units. The term “polymer” is used to describe the resultant material formed from a polymerization reaction.

[0029] As used herein, “film” or “layer” refers to a single stratum within a multilayer article.

[0030] As used herein, “thickness” refers to the smallest dimension of a film or layer, e.g., in a z-axis while a major surface of the film or layer is in the x- and y-axes.

[0031] As used herein, “substrate” encompasses films and layers, including microstructured films / layers.

[0032] As used herein, the term “essentially free” in the context of a composition being essentially free of a component, refers to a composition containing less than 1% by weight (wt.%), 0.5 wt.% or less, 0.25 wt.% or less, 0.1 wt.% or less, 0.05 wt.% or less, 0.001 wt.% or less, or 0.0001 wt.% or less of the component, based on the total weight of the composition.

[0033] The words “preferred” and “preferably” refer to embodiments of the disclosure that may afford certain benefits, under certain circumstances. However, other embodiments may also be preferred, under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful, and is not intended to exclude other embodiments from the scope of the disclosure.

[0034] In this application, terms such as “a”, “an”, and “the” are not intended to refer to only a singular entity, but include the general class of which a specific example may be used for illustration. The terms “a”, “an”, and “the” are used interchangeably with the term “at least one.” The phrases “at least one of’ and “comprises at least one of’ followed by a list refers to any one of the items in the list and any combination of two or more items in the list.

[0035] As used herein, the term “or” is generally employed in its usual sense including “and / or” unless the content clearly dictates otherwise.

[0036] The term “and / or” means one or all of the listed elements or a combination of any two or more of the listed elements.

[0037] Also herein, all numbers are assumed to be modified by the term “about” and preferably by the term “exactly.” As used herein in connection with a measured quantity, the term “about” refers to that variation in the measured quantity as would be expected by the skilled artisan making the measurement and exercising a level of care commensurate with the objective of the measurement and the precision of the measuring equipment used. Also herein, the recitations of numerical ranges by endpoints include all numbers subsumed within that range as well as the endpoints (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc.).

[0038] As used herein as a modifier to a property or attribute, the term “generally”, unless otherwise specifically defined, means that the property or attribute would be readily recognizable by a person of ordinary skill but without requiring absolute precision or a perfect match (e.g., within + / - 20 % for quantifiable properties). The term “substantially”, unless otherwise specifically defined, means to a high degree of approximation (e.g., within + / - 10% for quantifiable properties) but again without requiring absolute precision or a perfect match. Terms such as same, equal, uniform, constant, strictly, and the like, are understood to be within the usual tolerances or measuring error applicable to the particular circumstance rather than requiring absolute precision or a perfect match.

[0039] In a first aspect, a plurality of porous spacers is provided. The porous spacers comprise: a plurality of carbon dioxide-sorbent particles distributed in a polymeric matrix, the porous spacers having a form of a plurality of strips and / or dots.

[0040] Referring to FIG. 1, a photograph is provided of numerous porous spacers 100 each having a shape of a dot 110, made according to the present disclosure. The dots 110 are substantially spherical. Referring to FIG. 2, a photograph is provided of numerous porous spacers 200 each having a shape of a strip 220, made according to the present disclosure. The strips 220 have both a length L and a width W, with an aspect ratio significantly greater than 2 : 1 for length to width. These were printed as described in the Examples below, in particular SiN2Modified P-SiO2printed on a 25 gsm carbon fiber veil.

[0041] It has been discovered that it is possible to achieve greater carbon dioxide sorption, for instance via direct air capture of carbon dioxide, by including spacers between carbon dioxide-sorbent sheets that are themselves carbon dioxide-sorbent. Advantageously, spacers according to at least certain embodiments of the present disclosure have sufficient structural integrity to be suitable for use as spacers between adjacent carbon dioxide-sorbent sheets, despite the porosity of the spacers.

[0042] In a second aspect, a parallel contactor is provided. The parallel contactor comprises a plurality of spaced carbon dioxide-sorbent sheets, wherein directly adjacent carbon dioxide-sorbent sheets are spaced from each other by a plurality of any of the porous spacers according to the first aspect. Also advantageously, the porous spacers having porosity and CO2sorption / desorption functionality similar to the carbon dioxide-sorbent sheets means that the area the porous spacers cover is also functional so the carbon dioxide sorption capacity of the parallel contactor is not negatively impacted by the presence of the porous spacers.

[0043] Each of the materials used to form porous spacers and parallel contactors are described in detail below.

[0044] Carbon Dioxide-Sorbent Particles

[0045] The porous spacers comprise a plurality of carbon dioxide-sorbent particles distributed in a polymeric matrix. It is to be understood that the carbon dioxide-sorbent particles are present throughout the bulk of the polymeric matrix of each porous spacer, not just on an exterior surface (e.g., in a coating on the surface of the polymeric matrix). In some cases, the carbon dioxide-sorbent particles are substantially homogeneously distributed throughout the polymeric matrix.

[0046] The spacers are porous at least due to gaps present between adjacent agglomerated or aggregated particles that do not get filled by polymeric material. In certain embodiments, the carbon dioxide-sorbent particles themselves have pores in their structure, providing additional porosity. Optionally, the porous spacers have a porosity of 10% or greater, 15%, 20%, 25%, 30%, 35%, 40%, 45%, or 50% or greater; and 80% or less, 75%, 70%, 65%, 60%, 55%, 50%, 45%, 40%, 35%, 30%, or 25% or less, as determined by mercury (Hg) intrusion porosimetry In some cases, the porous spacers have a porosity of 40% or greater, 45%, or 50% or greater; and 60% or less, as determined by Hg intrusion porosimetry.

[0047] By “carbon dioxide-sorbent” it is to be understood that the particles not only sorb carbon dioxide, but also desorb carbon dioxide when subjected to desorption conditions (e.g., pressure, moisture, and / or temperature swings). This allows the porous spacers, parallel contactors, etc., to be repeatedly reused. In certain embodiments, sorbed carbon dioxide can be removed from the porous spacers at or below 110 degrees Celsius (e.g., using ohmic heating), typically under vacuum and / or flowing steam. Representative examples of suitable carbon dioxide-sorbent particles include metal oxide particles, non- metal oxide particles, and amino-functionalized ion exchange particles. Any combination of carbon dioxide-sorbent particles may be employed in the porous spacers.

[0048] Some suitable carbon dioxide-sorbent particles include for instance and without limitation, metal oxide particles selected from the group consisting of silicon dioxide (silicon is considered to be a metalloid and thus is included in the list of metal oxides), zirconium oxide, aluminum oxide, titanium oxide, calcium oxide, zinc oxide, cadmium oxide, magnesium oxide, tin oxide, nickel oxide, manganese oxide, iron oxide, copper oxide, beryllium oxide, vanadium oxide, chromium oxide, boron oxide, phosphorus oxide, any metal oxide particles which have oxygen vacancies, and combinations thereof. Oxide vacancies can be determined by techniques like X-ray Photoelectron Spectroscopy or Raman Spectroscopy, but also other techniques as described in Gunkel et al. Appl. Phys. Lett. 116, 120505 (2020).

[0049] In some embodiments, the metal oxide particles are amino-functionalized. Amino functionalization can be performed using various materials, such as amino-functional silanes, aminopolymers, or combinations thereof.

[0050] Suitable amino-functional silanes include for instance and without limitation, 3- aminopropyltrimethoxysilane, [3-(2-aminoethylamino)propyl]trimethoxysilane, 3-[2-(2- aminoethylamino)ethylamino]propyltrimethoxysilane, bis(3-trimethoxysilylpropyl)amine, bis(3- triethoxysilylpropyljamine, N-methyl-bis(3-trimethoxysilylpropyl)amine, N,N’-bis[3- trimethoxysilylpropyl]-ethylenediamine, N,N-bis[3-trimethoxysilylpropyl]-ethylenediamine, and combinations thereof.

[0051] Suitable aminopolymers, for instance, may be selected from the group consisting of polyethylenimine, polylysine, polyaminoamides, polyallylamine, polyvinylamine, polydimethylamine- epichlorohydrin-ethylenediamine, polydiallyldimethylammonium chloride, cationic polyacrylamide (CP AM), and poly aminosiloxanes.

[0052] Optionally, a crosslinker may be employed, for example to crosslink the functionalized particles to each and / or to the polymeric matrix. Suitable crosslinkers include for instance and without limitation, alkoxysilanes, (methjacrylate alkoxysilanes (e.g., methacrylate trimethoxysilanes), glycerol diglycidyl ether (GDGE), butanediol diglycidyl ether (BUDGE), ethylene glycol diglycidyl ether (EDGE), polyethylene glycol) diglycidyl ether (PEGDGE), and combinations thereof. In certain embodiments, a crosslinker may be used in an amount of up to a ratio of 1 : 1 with the total amount of aminosilane(s) and aminopolymer(s) present.

[0053] Amino-functionalization of the metal oxide particles can be carried out, for instance as described in detail in the Examples below.

[0054] Suitable non-metal oxide particles include for instance and without limitation silicon carbide, clays, polystyrene (co)polymers, cellulose, metal organics, desiccant, activated carbon, graphite, carbon molecular sieve, molecular sieve, aluminophosphate, silicoaluminophosphate, zeolite adsorbent, ion exchanged zeolite, hydrophilic zeolite, hydrophobic zeolite, modified zeolite, natural zeolites, faujasite, clinoptilolite, mordenite, metal-exchanged silico-aluminophosphate, uni-polar resin, bi polar resin, brominated aromatic matrix, methacrylic ester copolymer, carbon fiber, carbon nanotube, nano-materials, metal salt adsorbent, perchlorate, oxalate, alkaline earth metal particle, supported alkali carbonates, alkali-promoted hydrotalcites, chemisorbent, organo-metallic reactant, metal organic framework adsorbent, or combinations thereof. Such particles provide scaffolds to be amine functionalized for use for carbon dioxide sorption and desorption.

[0055] In some cases, when amino-functionalized ion exchange particles are employed, the aminofunctionalized ion exchange particles are milled. Milling decreases the particle size, which advantageously increases the surface area of the ion exchange particles. Some suitable commercially available amino-functionalized ion exchange particles include for instance and without limitation, Lewatit VPOC1065 from Lanxess AG (Cologne, Germany) and Purolite Al lOfrom Purolite LLC (King of Prussia, PA).

[0056] The size of the porous spacers is not particularly limited, particularly in their length and width (e.g., along the x-axis and y-axis). In some embodiments, a suitable size with respect to a height of a porous spacer (e.g., in the z-axis in between two adjacent carbon dioxide-sorbent sheets) is 0.5 millimeters (mm) or greater; 0.75 mm, 1.0 mm, 1.25 mm, 1.5 mm, 1.75 mm, 2.0 mm, 2.25 mm, 2.5 mm, 2.75 mm, 3.0 mm, 3.25 mm, 3.5 mm, 3.75 mm, or 4.0 mm or greater; and 6 mm or less, 5.75 mm, 5.5 mm, 5.25 mm, 5.0 mm, 4.75 mm, 4.5 mm, 4.25 mm, 4.0 mm, 3.75 mm, 3.5 mm, 3.25 mm, 3.0 mm, 2.75 mm, 2.5 mm, 2.25 mm, or 2 mm or less. In some cases, a height of a porous spacer may range from 0.5 mm to 6 mm.

[0057] Polymeric Matrix

[0058] The type of polymer(s) used for the polymeric matrix of the porous spacers is not particularly limited. In certain embodiments, the polymeric matrix comprises a reaction product of a polymerizable composition comprising a multifunctional (methjacrylate, an amino-containing polymer, and optionally a crosslinker. Suitable aminopolymers, for instance, may be selected from the group consisting of polyethylenimine, polylysine, polyaminoamides, polyallylamine, polyvinylamine, polydimethylamine- epichlorohydrin-ethylenediamine, polydiallyldimethylammonium chloride, cationic polyacrylamide (CP AM), and poly aminosiloxanes. In some embodiments, the polymeric matrix comprises at least one component selected from the group consisting of a (meth)acrylic polymer a polyethyleneimine, a polyaminosiloxane, a polypropyleneimine, a polylysine, a polyaminoamide, a polyvinylamine, a polyallylamine, and a latex rubber. Again, a crosslinker is optional or the polymeric matrix may be otherwise crosslinked if desired (e.g., using e-beam crosslinking).

[0059] Suitable crosslinkers include for instance and without limitation, certain of the crosslinkers listed above for amino functionalization of metal oxide particles: alkoxy silanes, (meth)acrylate alkoxy silanes, GDGE, BUDGE, EDGE, PEGDGE, and combinations thereof.

[0060] Examples of useful multifunctional (meth)acrylate monomers include, but are not limited to, di(meth)acrylates, tri(meth)acrylates, and tetra(meth)acrylates, such as, for example, 1,6 -hexanediol di(meth)acrylate, polyethylene glycol) di(meth)acrylates, polybutadiene di(meth)acrylate, polyurethane di(meth)acrylates, and propoxylated glycerin tri(meth)acrylate, and mixtures thereof.

[0061] Examples of useful monofunctional (meth)acrylate monomers include, but are not limited to, ethoxyethyl acrylate, phenoxyethyl acrylate, cyanoethyl (mono)acrylate, isobomyl acrylate, octadecyl acrylate, isodecyl acrylate, lauryl acrylate, beta-carboxyethyl acrylate, tetrahydrofurfuryl acrylate, dinitrile acrylate, pentafluorophenyl acrylate, nitrophenyl acrylate, 2-phenoxyethyl acrylate, 2,2,2- trifluoromethyl acrylate, phenylthioethyl acrylate, naphthloxyethyl acrylate, the corresponding methacrylates of the acrylates listed above, and mixtures thereof.

[0062] Carbon Dioxide-Sorbent Sheets

[0063] In some cases, a carbon dioxide-sorbent sheet comprises a nonwoven substrate and a plurality of carbon dioxide-sorbent particles attached to (e.g., at a substrate surface) and / or in (e.g., within the bulk thickness of the substrate) the nonwoven substrate. Suitable nonwoven substrates may comprise at least one of carbon fibers, glass fibers, ceramic fibers, of polymer fibers. For example, the nonwoven substrate may include at least one of polymer-coated glass fibers or polymer-coated carbon fibers.

[0064] Exemplary suitable carbon dioxide-sorbent sheets include for instance and without limitation, any commercially available carbon dioxide-sorbent sheets and any carbon dioxide-sorbent sheets described in detail in PCT Application Publications Nos. WO 2021 / 239747 (Spiteri et al.), WO 2021 / 259760 (Vargas et al.), and / or WO 2021 / 240476 (Cizeron et al.), incorporated herein by reference in their entireties. For instance, the sheets could be inorganic or organic, non-polymeric or polymeric materials (e.g., crosslinked polystyrene sorbents), that are functionalized with amino groups (e.g., primary and / or secondary amine functionalities). In some cases, a sheet could be a composite including fibers, binders, and carbon dioxide-adsorbent particles. Some more specific examples include weak-base ion exchange resins or amine-functionalized: carbon, cellulose, silica, polymer adsorbents, and / or metal organic frameworks.

[0065] Carbon dioxide-sorbent sheets may be commercially available (either alone or as part of a direct air capture system) from the following vendors: Global Thermostat (Commerce City, CO), Carbon Engineering (Squamish, Canada), C2CNT (Ashburn, Virginia), Shell PLC (London, England), and Babcock & Wilcox (Akron, OH). Parallel Contactors

[0066] As noted above, a parallel contactor comprises a plurality of spaced carbon dioxide-sorbent sheets, in which directly adjacent carbon dioxide-sorbent sheets are spaced from each other by a plurality of any of the porous spacers according to the first aspect described in detail above. It is noted that each of the plurality of porous spacers is attached to one of the plurality of carbon dioxide-sorbent sheets (e.g., attached to just one side). It is possible to affix the porous spacers to both adjacent carbon dioxide- sorbent sheets but is not usually needed and / or convenient. The porous spacers can be attached to a carbon dioxide-sorbent sheet by various methods, including printing the porous spacers directly onto a carbon dioxide-sorbent sheet (e.g., through a screen). If the porous spacers are already formed, an adhesive or uncured polymeric matrix (with or without carbon dioxide-sorbent particles present in the polymeric matrix) may optionally be used to attach the porous spacers to a carbon dioxide-sorbent sheet, followed by curing the adhesive or polymeric matrix. In certain embodiments, the porous spacers may be present such that one porous spacer is located in each square inch of a carbon dioxide-sorbent sheet.

[0067] Referring to FIG. 3, is a schematic perspective view is provided of an exemplary parallel contactor 3000. For simplicity, just four spaced carbon dioxide-sorbent sheets 330a, 330b, 330c, and 330d, are depicted in the parallel contactor 3000 of FIG. 3. The number of carbon dioxide-sorbent sheets 330 is not particularly limited and may be selected due to space and / or weight constraints for the application. The top carbon dioxide-sorbent sheets 330a is shown in phantom so the porous spacers 310 and 320 in between the adjacent carbon dioxide-sorbent sheets 330a and 330b are visible. Strips tend to impart greater rigidity to a parallel contactor than dots. In this particular embodiment, the porous spacers 310 and 320 have a form of both dots 310 and strips 320, although these two shapes are not strictly necessary. Rather, any one or more shapes, including known shapes other than dots and strips, may be employed.

[0068] FIG. 4 is a schematic cross-sectional view of another exemplary parallel contactor 4000. Again, for simplicity, just four spaced carbon dioxide-sorbent sheets 430a, 430b, 430c, and 430d, are depicted in the parallel contactor 4000 of FIG. 4. Additionally, porous spacers 410, 420 having a form of each of dots 410 and strips 420 are present in this embodiment between adjacent carbon dioxide-sorbent sheets 430. However, any one or more shapes, including known shapes other than dots and strips, may be employed. The spacing and arrangement of the porous spacers is not particularly limited. For example, in some cases porous spacers 420 having a form of strips 420 may be placed with the length L of one porous spacer 420 being perpendicular to the length of the next porous spacer 420 (parallel to the width W), as shown in FIG. 4. In this embodiment, the porous spacers 410 in between carbon dioxide-sorbent sheets 430a and 430b, are directly in line with the porous spacers 410 in between carbon dioxide-sorbent sheets 430c and 430d, while the porous spacers 420 inbetween carbon dioxide-sorbent sheets 430b and 430c are offset (horizontally) from the porous spacers 410. Many alternate arrangements are clearly possible while keeping adjacent carbon dioxide-sorbent sheets spaced apart from each other. Typically, each of the plurality of porous spacers 410, 420 is attached to just one of the carbon dioxide-sorbent sheets, for instance if a porous spacer 410 is attached to the major surface 432a of the carbon dioxidesorbent sheet 430a, then it is usually not also attached to the major surface 434b of the carbon dioxidesorbent sheet 430b, and vice versa.

[0069] As shown in each of FIGS. 3 and 4, optionally at least some of the carbon dioxide-sorbent sheets are flat. In contrast, referring to FIG. 5, a schematic cross-sectional view is provided of an exemplary parallel contactor 5000 in which at least some of the carbon dioxide-sorbent sheets 530 are pleated or corrugated. For simplicity, just three carbon dioxide-sorbent sheets 530a, 530b, and 530c are shown in this embodiment. The first carbon dioxide-sorbent sheet 530a is pleated, the second carbon dioxide- sorbent sheet 530b is corrugated, and the third carbon dioxide-sorbent sheets 530c is flat. Various porous spacers 520 are shown in between the adjacent carbon dioxide-sorbent sheets 530a, 530b, and 530c. Many varying arrangements of carbon dioxide-sorbent sheets and porous spacers can be suitable for parallel contactors according to the present disclosure.

[0070] Exemplary Embodiments

[0071] In a first embodiment, the present disclosure provides a plurality of porous spacers for a direct air capture sheet. The porous spacers each comprise a plurality of carbon dioxide-sorbent particles distributed in a polymeric matrix. The porous spacers have a form of a plurality of strips and / or dots.

[0072] In a second embodiment, the present disclosure provides porous spacers according to the first embodiment, having a form of a plurality of strips.

[0073] In a third embodiment, the present disclosure provides porous spacers according to the first embodiment or the second embodiment, having a form of a plurality of dots.

[0074] In a fourth embodiment, the present disclosure provides porous spacers according to any of the first through third embodiments, wherein the plurality of carbon dioxide-sorbent particles comprises metal oxide particles, non-metal oxide particles, amino-functionalized ion exchange particles, or combinations thereof.

[0075] In a fifth embodiment, the present disclosure provides porous spacers according to the fourth embodiment, wherein the amino-functionalized ion exchange particles are milled.

[0076] In a sixth embodiment, the present disclosure provides porous spacers according to the fourth embodiment or the fifth embodiment, wherein the metal oxide particles are selected from the group consisting of silicon dioxide, zirconium oxide, aluminum oxide, titanium oxide, calcium oxide, zinc oxide, cadmium oxide, magnesium oxide, tin oxide, nickel oxide, manganese oxide, iron oxide, copper oxide, beryllium oxide, vanadium oxide, chromium oxide, boron oxide, phosphoms oxide, any metal oxide particles which have oxygen vacancies, and combinations thereof.

[0077] In a seventh embodiment, the present disclosure provides porous spacers according to any of the fourth through six embodiments, wherein the metal oxide particles are amino-functionalized.

[0078] In an eighth embodiment, the present disclosure provides porous spacers according to any of the first through seventh embodiments, wherein the polymeric matrix comprises a reaction product of a polymerizable composition comprising a multifunctional (meth)acrylate, an amino-containing polymer, and optionally a crosslinker.

[0079] In a ninth embodiment, the present disclosure provides porous spacers according to any of the first through seventh embodiments, wherein the polymeric matrix comprises at least one component selected from the group consisting of a (meth)acrylic polymer, a polyethyleneimine, a polyaminosiloxane, a polypropyleneimine, a polylysine, a polyaminoamide, a polyvinylamine, a polyallylamine, and a latex rubber.

[0080] In a tenth embodiment, the present disclosure provides porous spacers according to any of the first through ninth embodiments, having a height of 0.5 millimeters (mm) to 6 mm.

[0081] In an eleventh embodiment, the present disclosure provides porous spacers according to any of the first through eleventh embodiments, having a porosity in a range of 10% to 80%, or 40% to 60%, as determined by Hg intrusion porosimetry.

[0082] In a twelfth embodiment, the present disclosure provides a parallel contactor. The parallel contactor comprises a plurality of spaced carbon dioxide-sorbent sheets, wherein directly adjacent carbon dioxide-sorbent sheets are spaced from each other by a plurality of any of the porous spacers according to any of the first through eleventh embodiments.

[0083] In a thirteenth embodiment, the present disclosure provides a parallel contactor according to the twelfth embodiment, wherein each of the plurality of porous spacers is attached to one of the plurality of carbon dioxide-sorbent sheets.

[0084] In a fourteenth embodiment, the present disclosure provides a parallel contactor according to the twelfth embodiment or the thirteenth embodiment, wherein at least some of the carbon dioxide-sorbent sheets are flat.

[0085] In a fifteenth embodiment, the present disclosure provides a parallel contactor according to any of the twelfth through fourteenth embodiments, wherein at least some of the carbon dioxide-sorbent sheets are pleated or corrugated.

[0086] In a sixteenth embodiment, the present disclosure provides a parallel contactor according to any of the twelfth through fifteenth embodiments, wherein at least some of the carbon dioxide-sorbent sheets comprise a nonwoven substrate and a plurality of carbon dioxide-sorbent particles attached to and / or in the nonwoven substrate.

[0087] In a seventeenth embodiment, the present disclosure provides a parallel contactor according to the sixteenth embodiment, wherein the nonwoven substrate comprises at least one of carbon fibers, glass fibers, ceramic fibers, of polymer fibers.

[0088] In an eighteenth embodiment, the present disclosure provides a parallel contactor according to the seventh embodiment, wherein the nonwoven substrate comprises at least one of polymer-coated glass fibers or polymer-coated carbon fibers. EXAMPLES

[0089] The following Examples are merely for illustrative purposes and are not meant to be overly limiting on the scope of the appended claims. Unless otherwise noted or otherwise apparent from the context, all parts, percentages, ratios, and the like in the Examples and the rest of the specification are provided on the basis of weight.

[0090] Materials Used in the Examples

[0091] Preparation of SiN2 Modified P-SiCf (A-SiO SiN^):

[0092] In a 1000-mL glass bottle, charged with 102.19g P-SiCh and 500 g ACN (from opened bottle with moisture) under N2, then added 102.29 g SiN2 (0.46 mol) at room temperature via an addition funnel in 30 minutes while stirring. The solution was stirred and reacted overnight (24 hours) at room temperature, then in a 60°C water-bath for another two hours. The solvent was removed by rotary evaporation, then the obtained solid was further dried in an oven set at 60°C under nitrogen for 6 hours. 178 g of dried solid (SiN2modified P-SiCh) was transferred to a polypropylene bottle for formulation.

[0093] Milling of Modified P-SiCT (A-SiCh / Sibb):

[0094] To a 500-mL Nalgene polyethylene jar was charged 100 g of SiN2 Modified P-SiCh, 1200 g of 15 mm Yttria Stabilized Zirconia spherical milling media (MSE Supplies, Tucson, AZ) and 150 g of water. The admixture was shaken and agitated and placed on a roller-mill (U.S. Stoneware, East Palestine, OH) for 6 hours. An additional 50 g of water of was added to reduce the viscosity and milling was continued for an additional 8 hours.

[0095] The particle size of the milled slurry was measured by laser diffraction using a HORIB A LA-950 Particle (Horiba, Ltd., Kyoto, Japan). Approximately 1% dispersion of the milled slurry was prepared for the measurement and the particle size distribution showed a volume average D50 of 7.04 pm and D90 of 11.38 pm.

[0096] The milled slurry (approximately 25 g) was coated onto 12-inch x 5-inch (30.48 centimeter x 12.7 centimeter) glass fiber (21 gsm, Technical Fibre Products, Ltd., Schenectady, NY) non-woven and spread across top and bottom of the substrate using a doctor blade. Preparation of Printing Slurry

[0097] 20.2 g of SiN2Modified P-SiO2and 11.3 g of water were charged into 40 mL speedmixer cups along with 2 ceramic cylindrical milling media beads, ! ” diameter x ! ” height (Burundum Grinding Media, Cole- Parmer NA, Vernon Hills, IL). The mixture was agitated at 3000 RPM for 1 min and aliquots were taken and printed onto the non-woven substrate.

[0098] Method of Screen Printing Slurry

[0099] A polyethylene terephthalate (PET) screen (laser cut to the design of choice) approximately 8-inch by 12- inch (20.32 centimeter x 30.48 centimeter) in size was taped to the desired substrate for printing. Approximately 2 grams of the slurry was poured onto the top portion of the screen, and the slurry was spread with a plastic squeegee approximately 6 inches (15.24 centimeters) wide, traversing in the downweb direction. During this process, the slurry was pushed though the holes of the screen, creating features that are approximately the same dimensions and design as the cut-out portions of the screen. The dimensions of the screen patterns used in printing are listed in the Pattern Table below.

[0100] Pattern Table

[0101] Table 1. CO2Capacity of SiN2Modified P-SiO2

[0102] Example 1

[0103] In a 2-L tri-neck round bottom flask, 124.16 g P-SiO2at 100% solids, was diluted to 1,004.72 g with distilled water and stirred with a stir rod with an electric motor at 250 revolutions per minute (RPM). In a 1-L beaker, a mixture comprising 951.38 g 1 -methoxy -2 -propanol and mixed with 98.82 g 3-Amine was prepared. This mixture was slowly added to the stirred 2-L tri-neck flask. The mixture was stirred for 5 minutes without heating. A lab chiller was turned on with a reflux coil to condense solvent back to the flask during the reaction. A heated hot oil heater controlled by a J-Kem temperature controller (J-Kem Scientific, Inc., St. Louis MO) was set at 85°C for 16 hours to heat the flask for the reaction to proceed. After reaction, the sol was concentrated on a Buchi rotovap (model R-300) from (Buchi Corporation New Castle, DE United States). 1,223.06 g of modified sol was poured into a 2L round bottom flask and stripped to 329.58 g and then 862.12 g distilled water was back added. The sol was stripped to 117.45 g at a pressure of 6 mbar and 110 RPM with a bath temperature of 60°C.

[0104] Example 2

[0105] Colloidal 5 nm silica in water (Nalco 2326) was functionalized following the procedure described below. In a 2-L tri-neck round bottom flask, 400.00 g Nalco 2326 at 15.87% solids, was stirred with a stir rod with an electric motor at 250 RPM. In a 1-L beaker, a mixture comprising 460.52 g l-methoxy-2- propanol, 0.10 g of 5% 4-hydroxy -tempo in water, and 29.48 g 3-Amine was prepared. The mixture was stirred for 5 minutes without heating. A lab chiller was turned on with a reflux coil to condense solvent back to the flask during the reaction. A heated hot oil heater controlled by a J-Kem temperature controller (J-Kem Scientific, Inc., St. Louis MO) was set at 85°C for 16 hours to heat the flask for the reaction to proceed.

[0106] After reaction, the sol was concentrated on a Buchi rotovap. 5 nm SiO2 was functionalized following the procedure described below. In a 2-L tri-neck round bottom flask, 400.00 g 5 nm SiO2at 15.87% solids, was stirred with a stir rod with an electric motor at 250 RPM. In a 1-L beaker, a mixture comprising 460.52 g 1 -methoxy -2 -propanol, 0.10g of 5% 4-hydroxy-tempo in water, and 29.48 g 3-Amine was prepared.

[0107] The modified sol, 822.02 g, was poured into a 2L round bottom flask and stripped to 551.22 g and then 664 g distilled water was back added. The sol was stripped to 339.34 g at a pressure of 6 mbar and 110 RPM with a bath temperature of 60°C. Using a Despatch Oven (model #LFDl-42-3) (Despatch, Lakeville, MN) at 120°C for 45 min, the concentration of the resulting sol was measured to be an average of 23.056% solids.

[0108] Table 2. CO2 Capacity of amine functionalized SiO2 Table 3, Percent solids of amino functionalized colloidal silica disclosed in Example 2.

[0109] Thermo gravimetric analysis (TGA) Test Method 1: CO2 capture performance

[0110] Samples for CO2 capture performance, approximately 25-50 mg of dried composition described above were evaluated by gravimetric analysis. The sample was loaded on a clean and tared platinum TGA pan. The thermogravimetric analyzer (a Q500 model from TA Instruments New Castle, DE) was plumbed with house nitrogen (supplied by Praxair, Danbury, CT) in gas line #1 and a mixed gas canister on gas line #2 regulated to 20 psi (0.138 MPa). The mixed gas canister was 20 volume % CO2 with a balance of N2obtained from Airgas, Randor, PA.

[0111] First, house nitrogen was flowed over the sample at 80 °C for 90 minutes at 267 mL / min to drive off CO2 and get a baseline weight %. Then, the gas composition supplied at a flow rate of 200 mL / min was adjusted (by splitting gas lines #1 and #2) to supply 15 vol.% CO2 to the sample in the chamber while holding the chamber at 80°C. The 15 vol.% CO2 was flowed across the sample for a set time (either 10 or 30 minutes) and the weight gain of the sample was monitored. Then, the CO2 gas supply was stopped, and the sample was regenerated with house nitrogen flow for 10 minutes while held at 80°C.

[0112] Then, the gas in the sample chamber was adjusted to 15 vol.% CO2 and the chamber was cooled to 65°C. The 15 vol.% CO2 was flowed across the sample at a flow rate of 200 mL / min for a set time (either 10 or 30 minutes) and the weight gain of the sample was monitored. The sample was then regenerated by flowing house nitrogen and ramping the chamber up to 80 °C at 10°C / min for 10 minutes to remove CO2 from the sorbent.

[0113] Then, the gas in the sample chamber was adjusted to 15 vol.% CO2 and the chamber was cooled to 50°C. The 15 vol.% CO2 was flowed across the sample at a flow rate of 200 mL / min for a set time (either 10 or 30 minutes) and the weight gain of the sample was monitored. The sample was then regenerated by flowing house nitrogen and ramping the chamber up to 80 °C at 10°C / min for 10 minutes to remove CO2 from the sorbent.

[0114] Then, the gas in the sample chamber was adjusted to 15 vol.% CO2 and the chamber was cooled to 35°C. The 15 vol.% CO2 was flowed across the sample at a flow rate of 200 mL / min for a set time (either 10 or 30 minutes) and the weight gain of the sample was monitored. The sample was then regenerated by flowing house nitrogen and ramping the chamber up to 80 °C at 10°C / min for 10 minutes to remove CO2 from the sorbent. While at 80°C, the gas composition was switched and 15 vol.% CO2 was flowed across the sample at a flow rate of 200 mL / min for a set time (either 10 or 30 minutes) and the weight gain of the sample was monitored. The mmol of CO2 per gram of sample at each temperature isotherm (80°C, 65°C, 50°C, and 35°C) was calculated based on equation 1:

[0115] 1000 44.01

[0116] Equation 1

[0117] Examples 3 through 6 (EX-3 to EX-6)

[0118] Method of Making a Printing Slurry with Oxides

[0119] Two sources of colloidal zirconia, Alfa Aesar 40123 (Z1O2-I) and Nissan ZR-40BL (Z1O2-2), were used in slurry preparation. These samples were dried down and then calcined to the following temperatures: 300°C, 325°C, 350°C.

[0120] Polyethylene imine of 600 g / mol molecular weight was used (PEI-600). Polyvinylamine (VA) was used. A crosslinker, 1,4-butanediol diglycidyl ether (BUDGE) was examined to make the composite more resistant to water. The PEI-600 was dissolved in methanol (MeOH) at either 2 or 10 wt.%. VA was used at 10 wt.% in MeOH. BUDGE was used at 5 wt.% in MeOH.

[0121] Table 4, CO2

[0122] The amounts used for EX-3 through EX-6 are given in Table 4. The polymer / MeOH mixture was added to the zirconia sample. This was stirred 1.5 h. The solid was filtered onto a glass frit and rinsed with MeOH. The solid was isolated, combined with the BUDGE solution, and heated to 65°C for 1.5 h. The solid was isolated by either centrifugation or filtration over a glass frit and rinsed with MeOH. The solids were tested for carbon dioxide sorption according to the TGA Test Method and the results at 35 °C are reported in Table 4 above. Example 7

[0123] Method of Making a Printing Slurry with Modified Silica with silane

[0124] A screen of aminosilanes were modified onto different size nanosilica sols to prepare printing slurries, printed and dried, then measured for CO2 capacity with a TGA. 1, 2, and 3 amines per silane were reacted onto Nalco 2326 (5 nm), Nalco 2327 (20 nm) and Nalco 2329K (75 nm). The aminosilanes were hydrolyzed onto the surface of silica amine silane and stripped to make higher viscosity or in the case of 5 nm SiCh-deta silane I Silverson model SL2T mixed it as it to make it have greater than 50% solids. Print it and dry in an oven, and measure on TGA for CO2 capacity.

[0125] Table 5. CO2 uptake from the TGA Test Method expressed as mmol CO2 / g sample.

[0126] Method of Measuring Oven Solids

[0127] A forced air oven from Despatch located in Minneapolis, MN was preheated to 80 °C to evaporate water and solvent. To a tared petri dish, about 4.0 grams of sol was added and the weight was recorded. Duplicate samples were put in a forced air oven for 45 min at 80 °C. Each petri dish was calculated for percent solids using the equation using the equation: [(final weight - petri dish tare) / initial weight of sample] and averaged to get the percent solids content.

[0128] Method of Making a Printing Slurry with a Weak-Base Anion Exchange Resin - Examples 8-15 (EX-8 to EX- 15)

[0129] A printing slurry was prepared including a weak-base anion resin comprising a polymer with the following general structure: The weak-base anion resin had a matrix comprising microporous polystyrene crosslinked with divinylbenzene and having primary amine functional groups. The resin was in the form of crushed beads having an average diameter of 200 pm measured by laser light scattering using a Mastersizer 3000 Hydro MV wet DLS system, Malvern Panalytical, Malvern, UK). 1.6 kilograms (kg) of the resin was mixed with 4 kg DI water using a high shear mixer for 30 minutes. 120 grams (g) of dispersant and 1 g defoamer were added to the slurry. This slurry mixture was then pumped through a high energy ball mill (PML2, Buhler, Uzwil, Switzerland) that was charged with 2 mm yttria stabilized zirconia media. The slurry was milled for 6 hours, resulting in a volume average particle size ranging between 5 pm and 20 pm, measured using laser diffraction.

[0130] Example 8: In a 10 mL speed cup and a 5 mm Pyrex glass bead (obtained from Coming (Coming, NY)), 5.9 g M543 at 22.30% solids and 0.8 g U9190 were charged to the speed cup and speed-mixed at 3,500 RPM for 60 seconds to mix. Using a pipette, a single drop of Laponite SL25 was added, and the cup was speed-mixed at 3500 RPM for another 60 seconds. A sample of the mixture was spread evenly over a 3D printed stencil placed over a substrate. The stencil was released carefully and the print dried in a Despatch oven set at 80 degrees C for 10 minutes.

[0131] Example 9: In a 10 mL speed cup and a 5 mm Pyrex glass bead, 6.4 g M543 at 22.30% solids and 1 g M8100 were charged to the speed cup and speed-mixed at 3,500 RPM for 60 seconds to mix. Using a pipette, a single drop of Laponite SL25 was added, and the cup was speed-mixed at 3500 RPM for another 60 seconds. A sample of the mixture was spread evenly over a 3D printed stencil placed over a substrate. The stencil was released carefully and the print dried in a Despatch oven set at 80 degrees C for 10 minutes.

[0132] Example 10: In a 10 mL speed cup and a 5 mm Pyrex glass bead, 8.1 g M543 at 22.30% solids and 1.1 g Joncryl 9533 were charged to the speed cup and speed-mixed at 3,500 RPM for 60 seconds to mix. Using a pipette, two drops of Laponite SL25 were added, and the cup was speed-mixed at 3500 RPM for another 60 seconds. A sample of the mixture was spread evenly over a 3D printed stencil placed over a substrate. The stencil was released carefully and the print dried in a Despatch oven set at 80 degrees C for 10 minutes.

[0133] Example 11: In a 10 mL speed cup and a 5 mm Pyrex glass bead, 8.3 g M543 at 22.30% solids and 1.3 g Encor 2721 were charged to the speed cup and speed-mixed at 3,500 RPM for 60 seconds to mix. Using a pipette, a single drop of Laponite SL25 was added, and the cup was speed-mixed at 3500 RPM for another 60 seconds. A sample of the mixture was spread evenly over a 3D printed stencil placed over a substrate. The stencil was released carefully and the print dried in a hood at room temperature. Example 12: In a 10 mL speed cup and a 5 mm Pyrex glass bead, 7.08 g M543 at 22.30% solids and 1.99 g Joncryl 9533 were charged to the speed cup and speed-mixed at 3,500 RPM for 60 seconds to mix. Using a pipette, three drops of Laponite SL25 were added, and the cup was speed-mixed at 3500 RPM for another 60 seconds. A sample of the mixture was spread evenly over a 3D printed stencil placed over a substrate. The stencil was released carefully and the print dried in a hood at room temperature.

[0134] Example 13: In a 10 mL speed cup and a 5 mm Pyrex glass bead, 6.5 g M543 at 22.30% solids and 1.43 g U9190 were charged to the speed cup and speed-mixed at 3,500 RPM for 60 seconds to mix. Using a pipette, two drops of Laponite SL25 were added, and the cup was speed-mixed at 3500 RPM for another 60 seconds. A sample of the mixture was spread evenly over a 3D printed stencil placed over a substrate. The stencil was released carefully and the print dried in a hood at room temperature.

[0135] Example 14: In a 10 mL speed cup and a 5 mm Pyrex glass bead, 7.67 g M543 at 22.30% solids and 1.71 g M8100 were charged to the speed cup and speed-mixed at 3,500 RPM for 60 seconds to mix. Using a pipette, two drops of Laponite SL25 were added, and the cup was speed-mixed at 3500 RPM for another 60 seconds. A sample of the mixture was spread evenly over a 3D printed stencil placed over a substrate. The stencil was released carefully and the print dried in a hood at room temperature.

[0136] Example 15: Printing slurry from Example #12 was used with a double stacked stencil. The stencil was released carefully and the print dried in a hood at room temperature.

[0137] Table 6. Observed print quality of Examples 8-15

[0138] It is noted that the above Examples 8-15 have not been optimized to achieve the best print quality possible with the materials used in the examples. To determine carbon dioxide absorption, the porous spacers were removed from the substrates and analyzed using the TGA Test Method 2 described below. Table 7. CO2 absorption in units of mmol CO2 per gram of printed Example

[0139] Methods of Making Porous Spacers with Inorganic Particles - Control and Examples 16-23 (EX-16 to

[0140] EX-23)

[0141] Control: In a 10 mL speed cup and 5 mm Pyrex glass bead, 10.00 g Sartomer CN9004 and 1.46 g Encor 2721 were charged to the speed cup and speed mixed at 3,500 RPM for 60 seconds to mix. A sample of the mixture was spread evenly over a 3D printed stencil placed on a DAC sheet. The stencil was released carefully and the print dried in a Despatch oven set at 80°C for 10 minutes.

[0142] Example 16: In a 250 mL round bottom flask, charge 132.85 g 5 nm SiCh at 15.943% solids was charged, then stripped on a rotovap until it got thick like honey. TGA was measured for % solids and % silica content. In a 10 mL speed cup and a 5 mm Pyrex glass bead, 9.4 g unmodified 5 nm SiCh at 32.12% solids, 28.43% SiCh, and 1.4 g GL618 were charged to the speed cup and speed mixed at 3,500 RPM for 60 seconds to mix. A sample of the mixture was spread evenly over a 3D printed stencil placed on a DAC sheet. The stencil was released carefully and the print dried in a Despatch oven set at 80°C for 10 minutes.

[0143] Solids TGA method: In a TGA (model Q500 acquired from TA Instruments New Castle, DE) compressed air was supplied to the furnace at 60 mL / min and N2to the counterbalance at 40 mL / min. Ramped 20°C / min to 200°C and held at 200°C for 20 min. The weight fraction after the 20 min hold was the dried solids fraction. Ramped 20°C / min to 900°C to decompose organics off the particles. The weight fraction at 900°C was the oxide fraction.

[0144] Example 17: In a 20 L glass kettle, 3,500.00 g 5 nm SiO2 at 16.205% solids was charged and stirring at 110 RPM was started. 2,000.00 g DI H2O was added to the sol in the stirring kettle. The chiller with a cold finger reflux on the kettle set to +20°C was turned on. In a 4 L glass beaker, 1,937.48 g 1-methoxy- 2-propanol was charged to the 20 L glass kettle. 2,0005.79 g 1 -methoxy -2 -propanol and 263.43 g 3- Amine were charged, pouring the silane / alcohol into the kettle slowly, forming a soft gel. The mixture was allowed to stir and react at 85°C with a timer on for 16 hours.

[0145] The next day, the modified sol was drained into a 20 L flask, using extra water and 1 -methoxy -2 -propanol to help pour it into the flask. 2,111.1 g DI H2O and 654 g 1 -methoxy -2 -propanol were charged into the flask, then stripped on the rotovap to 19.66% solids. The 20 L flask tare was 4,578.9 g. The mixture was stripped at 110 RPM, with a 40°C water bath, and a vacuum level of 26 inches of Hg, until it thickened up on the walls, resulting in 9,035.8g - tare = 4,456.9 g sol. Flowing compressed air, the temperature was ramped 20°C / min to 200°C, then an isotherm for 20 min, then ramped 20°C / min to 900°C.

[0146] In a 10 mL speed cup and a 5 mm Pyrex glass bead, 9.4 g 5 nm SiCh functionalized with 3 -Amine at 19.66% solids, 16.11% SiCh and 1.4 g Joncryl 9533 were charged to the speed cup and speed mixed at 3,500 RPM for 60 seconds to mix. A sample of the mixture was spread evenly over a 3D printed stencil placed on a DAC sheet. The stencil was released carefully and the print dried in a Despatch oven set at 80°C for 10 minutes.

[0147] Example 18: In a 16 oz jar, 200.00 g 75 nm SiCh at 40.49% solids was charged and magnetically stirred in the jar. In a 500 mL beaker, 225.98g 1 -methoxy -2 -propanol and 2.70g 2-Amine were charged. The silane / alcohol mixture was slowly stirred into the stirring jar of sol. The stir bar was removed and the 16 oz jar placed in a Despatch oven set at 85°C for 16 hours.

[0148] The next day, some of the 1 -methoxy -2 -propanol was stripped on the rotovap to prepare for printing. The 500 mL flask tare was 212.69 g. Charged 138.83 g sol to the flask and striped to 290.54 g - tare = 78 g sol. Flowing compressed air, the temperature was ramped 20°C / min to 200°C, then an isotherm for 20 min, then ramped 20°C / min to 900°C.

[0149] In a 10 mL speed cup and a 5 mm Pyrex glass bead, 10.09 g 75 nm SiCh functionalized with 2-Amine at 36.64% solids, 35.75% SiCh, and 1.43 g GL618 were charged to the speed cup and speed mixed at 3,500 RPM for 60 seconds to mix. A sample of the mixture was spread evenly over a 3D printed stencil placed on a DAC sheet. The stencil was released carefully and the print dried in a Despatch oven set at 80°C for 10 minutes.

[0150] Example 19: In a 10 mL speed cup and a 5 mm Pyrex glass bead, charged 6.3002 g 75 nm SiCh functionalized with 2-Amine and 0.5734 g DI H2O were charged, diluting the slurry from 36.64% solids to 33.58% solids. 2.3800 g GL818 was charged to the speed cup and speed mixed at 3,500 RPM for 60 seconds to mix. A sample of the mixture was spread evenly over a 3D printed stencil placed on a DAC sheet. The stencil was released carefully and the print dried overnight ambiently in a fume hood. Example 20: In a 10 mL speed cup and a 5 mm Pyrex glass bead, 7.0300 g unmodified 5 nm SiO2at 32.12% solids and 2.3500 g GL618 were charged to the speed cup and speed mixed at 3,500 RPM for 60 seconds to mix. A sample of the slurry was spread evenly over a 3D printed stencil placed on a DAC sheet. The stencil was released carefully and the print dried in a N2purged oven set at 80°C overnight.

[0151] Example 21: In a 10 mL speed cup and a 5 mm Pyrex glass bead, charged 7.0609 g 5 nm SiO2functionalized with 3-Amine at 19.66% solids was charged. 2.3502 g Joncryl 9533 was charged to the speed cup and speed mixed at 3,500 RPM for 60 seconds to mix. A sample of the slurry was spread evenly over a 3D printed stencil placed on a DAC sheet. The stencil was released carefully and the print dried in a N2purged oven set at 80°C overnight.

[0152] Example 22: In a 10 mL speed cup and a 5 mm Pyrex glass bead, 7.0200g 75 nm SiO2functionalized with 2-Amine at 36.64% solids was charged. 2.3900 g GL618 was charged to the speed cup and speed mixed at 3,500 RPM for 60 seconds to mix. A sample of the slurry was spread evenly over a 3D printed stencil placed on a DAC sheet. The stencil was released carefully and the print dried in a Despatch oven set at 80°C for 10 minutes.

[0153] Example 23: In a 10 mL speed cup and a 5 mm Pyrex glass bead, 6.8400 g 5 nm SiO2functionalized with 3-Amine and 0.6030 g DI H2O were charged, diluting the slurry from 19.66% solids to 18.067% solids. 2.3388 g Joncryl 9533 was charged to the speed cup and speed mixed at 3,500 RPM for 60 seconds to mix. A sample of the mixture was spread evenly over a 3D printed stencil placed on a DAC sheet. The stencil was released carefully and the print dried overnight ambiently in a fume hood.

[0154] Table 8. CO2absorption in units of mmol CO2per gram of printed Example. Table 9. Observed print quality of Control and Examples 16-26

[0155] It is noted that the above Examples 16-23 have not been optimized to achieve the best print quality possible with the materials used in the examples.

[0156] CO? Capture Performance via Thermo gravimetric Analysis (TGA) Test Method 2

[0157] Thermogravimetric analysis (TGA) was used to measure the CO2 capture performance of the samples of porous spacers printed on a DAC sheet. A hole punch of ~6 mm diameter was cut out of each of the samples using a die-punch cutter. A sample was loaded on a tared platinum TGA pan. The thermogravimetric analyzer (a Q550 model with a blending gas delivery module PN#956550.901 from TA Instruments New Castle, DE) was plumbed with house N2(supplied by Praxair, Danbury, CT) in channel A and a blended with a pure CO2gas canister on channel B regulated to 20 psi (0.138 MPa). The 100% CO2 gas canister was obtained from Airgas (Airgas, Radnor, PA). House N2, not blended with CO2, was flowed over the sample at 80 °C for 90 minutes at 222 mL / min to get a baseline weight %. Then, the gas composition supplied at a flow rate of 222 mL / min was adjusted (by blending channel A (N2) with 15% channel B (CO2)) to supply a 15 vol% CO2 to the sample in the chamber while holding the chamber at 80°C. The 15 vol% CO2 was flowed across the sample for a set time (either 10 or 30 minutes) and the weight gain of the sample was monitored. Then, the CO2gas supply was stopped, and the sample was regenerated with house N2flow for 10 minutes while held at 80°C. Then, the gas in the sample chamber was adjusted to 15 vol% CO2 and the chamber was cooled to 65°C. The 15 vol% CO2 was flowed across the sample at a flow rate of 222 mL / min for a set time (either 10 or 30 minutes) and the weight gain of the sample was monitored. The sample was then regenerated by flowing house N2and ramping the chamber up to 80 5 °C at 10°C / min for 10 minutes to remove CO2 from the sorbent. Then, the gas in the sample chamber was adjusted to 15 vol% CO2and the chamber was cooled to 50°C. The 15 vol% CO2 was flowed across the sample at a flow rate of 222 mL / min for a set time (either 10 or 30 minutes) and the weight gain of the sample was monitored. The sample was then regenerated by flowing house N2and ramping the chamber up to 80°C at 10°C / min for 10 minutes to remove CO2 from the sorbent. Then, the gas in the sample chamber was adjusted to 15 vol% CO2and the chamber was cooled to 35°C. The 15 vol% CO2 was flowed across the sample at a flow rate of 222 mL / min for a set time (either 10 or 30 minutes) and the weight gain of the sample was monitored. The sample was then regenerated by flowing house N2and ramping the chamber up to 80°C at 10°C / min for 10 minutes to remove CO2from the sorbent. While at 80°C, the gas composition was switched and 15 vol% CO2was flowed across the sample at a flow rate of 222 mL / min for a set time (either 10 or 30 minutes) and the weight gain of the sample was monitored. The mmol of CO2per gram of sample at each temperature isotherm (80°C, 65°C, 50°C, 35°C, 20 and 80°C) was calculated based on equation 2: mmol CO2 > peak wt-baseline wtv1000

[0158] Equation 2 X - g sorbent baseline wt 44.01

[0159] Example 24: Four hole punches, each with a diameter of 4 mm, were taken from the dried laminate of Example 16 including spacer dots and strips to allow an air gap during TGA CO2 uptake testing. The 4 mm hole punches were stacked on top of each other 4 layers high and tested on TGA with the TGA Test Method 2.

[0160] Example 25: One hole punch with a diameter of 4 mm was taken from the dried laminate of Example 17 including spacer dots and strips. The 4 mm hole punch was placed on the TGA pan and tested on TGA with the TGA Test Method 2.

[0161] Example 26: Three hole punches, each with a diameter of 4 mm, were taken from the dried laminate of Example 17 including spacer dots and strips to allow an air gap during TGA CO2 uptake testing. The 4 mm hole punches were stacked on top of each other 3 layers high and tested on TGA with the TGA Test Method 2.

[0162] Table 10. CO2sorbed in mmol CO2 / g sample

[0163] Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and / or equivalent implementations can be substituted for the specific embodiments shown and described without departing from the scope of the present disclosure. This application is intended to cover any adaptations or variations of the specific embodiments discussed herein. Therefore, it is intended that this disclosure be limited only by the claims and the equivalents thereof. Furthermore, all publications and patents referenced herein are incorporated by reference in their entirety to the same extent as if each individual publication or patent was specifically and individually indicated to be incorporated by reference. In the event of inconsistencies or contradictions between portions of the incorporated references and this application, the information in the preceding description prevails.

Claims

What is claimed is:

1. A plurality of porous spacers for a direct air capture sheet, the porous spacers each comprising: a plurality of carbon dioxide-sorbent particles distributed in a polymeric matrix, the porous spacers having a form of a plurality of strips and / or dots.

2. The porous spacers of claim 1, having a form of a plurality of strips.

3. The porous spacers of claim 1 or claim 2, having a form of a plurality of dots.

4. The porous spacers of any of claims 1 to 3, wherein the plurality of carbon dioxide-sorbent particles comprise metal oxide particles, and non-metal oxide particles, amino-functionalized ion exchange particles, or combinations thereof.

5. The porous spacers of claim 4, wherein the amino-functionalized ion exchange particles are milled.

6. The porous spacers of claim 4 or claim 5, wherein the metal oxide particles are selected from the group consisting of silicon dioxide, zirconium oxide, aluminum oxide, titanium oxide, calcium oxide, zinc oxide, cadmium oxide, magnesium oxide, tin oxide, nickel oxide, manganese oxide, iron oxide, copper oxide, beryllium oxide, vanadium oxide, chromium oxide, boron oxide, phosphorus oxide, any metal oxide particles which have oxygen vacancies, and combinations thereof.

7. The porous spacers of any of claims 4 to 6, wherein the metal oxide particles are amino- functionalized.

8. The porous spacers of any of claims 1 to 7, wherein the polymeric matrix comprises a reaction product of a polymerizable composition comprising a multifunctional (meth)acrylate, an aminocontaining polymer, and optionally a crosslinker.

9. The porous spacers of any of claims 1 to 7, wherein the polymeric matrix comprises at least one component selected from the group consisting of a (meth)acrylic polymer, a polyethyleneimine, a polyaminosiloxane, a polypropyleneimine, a polylysine, a polyaminoamide, a polyvinylamine, a polyallylamine, and a latex rubber.

10. The porous spacers of any of claims 1 to 9, having a height of 0.5 millimeters (mm) to 6 mm.

11. The porous spacers of any of claims 1 to 10, having a porosity of 40% to 60% as determined by Hg intrusion porosimetry.

12. A parallel contactor comprising:a plurality of spaced carbon dioxide-sorbent sheets, wherein directly adjacent carbon dioxide- sorbent sheets are spaced from each other by a plurality of any of the porous spacers of claims 1 to 11.

13. The parallel contactor of claim 12, wherein each of the plurality of porous spacers is attached to one of the plurality of carbon dioxide-sorbent sheets.

14. The parallel contactor of claim 12 or claim 13, wherein at least some of the carbon dioxide- sorbent sheets are flat.

15. The parallel contactor of any of claims 12 to 14, wherein at least some of the carbon dioxide- sorbent sheets are pleated or corrugated.

16. The parallel contactor of any of claims 12 to 15, wherein at least some of the carbon dioxide- sorbent sheets comprise a nonwoven substrate and a plurality of carbon dioxide-sorbent particles attached to and / or in the nonwoven substrate.

17. The parallel contactor of claim 16, wherein the nonwoven substrate comprises at least one of carbon fibers, glass fibers, ceramic fibers, of polymer fibers.

18. The parallel contactor of claim 17, wherein the nonwoven substrate comprises at least one of polymer-coated glass fibers or polymer-coated carbon fibers.

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