Enhance co 2 desorption efficiency over packing material prepared using dip-coating technology

Abstract

Herein disclosed is a packing material comprising: a substrate comprising a metal or a ceramic; and a coating on the substrate, wherein the coating comprises a catalyst which renders removal of carbon dioxide from an ammonia-based solution. A method for forming the packing material, and a method for removing carbon dioxide from an ammonia-based solution using the packing material, are also disclosed herein.

Description

ion No. 10202402274U, filed 30 July 2024, the content of it being hereby incorporated by reference in its entirety for all purposes.Technical Field

[0002] The present disclosure relates to a packing material, and a method for forming the packing material. The present disclosure also relates to a method for removing carbon dioxide from an ammonia-based solution.Background

[0003] In traditional processes that involve solvent(s) regeneration, there may be undesirable high energy consumption. For example, in a traditional carbon capture system, just the carbon dioxide desorption (recovery of the solvent from a carbon dioxide absorption solution) process may account for about 70% to about 80% of the total energy consumption of the entire carbon capture system.

[0004] Also, the low carbon dioxide desorption rate may lead to employment of oversized desorption column and increase in the number of operating equipment and units as well as operating costs.

[0005] For example, in a traditional carbon dioxide capture system, wherein commercially available methyl ethanolamine (MEA) was used, the operating temperature for the carbon dioxide desorption process was about 120°C to about 140°C. In another example, aqueous ammonia-based solution was used instead of MEA, and the operating temperature for the carbon dioxide desorption process was reduced to about 97 °C. While the aqueous ammonia-based solution was able to reduce energy consumption, the carbon desorption rate remains undesirable.

[0006] There is thus a need to provide for a solution that addresses one or more of the limitations mentioned above.Summary

[0007] In a first aspect, there is provided for a packing material comprising: a substrate comprising a metal or a ceramic; and a coating on the substrate, wherein the coating comprises a catalyst which renders removal of carbon dioxide from an ammonia-based solution.

[0008] In another aspect, there is provided for a method for forming the packing material described in various embodiments of the first aspect, the method comprising: providing the substrate comprising the metal or the ceramic; treating the substrate with an acid to form a treated substrate; and contacting the treated substrate with a coating mixture, wherein the coating mixture comprises the catalyst.

[0009] In another aspect, there is provided for a method for removing carbon dioxide from an ammonia-based solution, the method comprising: providing the packing material described in various embodiments of the first aspect; and contacting the packing material with the ammonia-based solution.Brief Description of the Drawings

[0010] The drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the present disclosure. In the following description, various embodiments of the present disclosure are described with reference to the following drawings, in which:

[0011] FIG. 1 is a diagram showing an overview of the method of the present disclosure for forming the packing material. Particularly, FIG. 1 shows the dip-coating process on structured substrates (e.g., a pall ring, a theta ring, and a substrate of silicon carbide denoted as SiC). The pall ring may be metal or ceramic, and may have a ring shape with holes or slots. The theta ring may be metal or ceramic, and may have a "star" or "theta" shape that may be described as having several projecting arms or wings extending from a central hub. The scale bar in the scanning electron microscopy (SEM) image (rightmost image) denotes 5 pm.

[0012] FIG. 2 shows a carbon dioxide absorption and desorption system using aqueous ammonia as the carbon dioxide absorption solution (CAS), except that the packing material in the desorption column is from the present disclosure.

[0013] FIG. 3 is a table comparing the operating temperatures for the carbon dioxide desorption processes with respect to (i) a traditional process using methyl cthanolaminc (MEA), (ii) traditional process using aqueous ammonia as the carbon dioxide absorption solution with bald packing (i.e., bald packing substrate or a packing material that has no coating layer), and (iii) a process using aqueous ammonia as the carbon dioxide absorption solution with a packing material of the present disclosure. The bald packing is traditional packing material without any coating.

[0014] FIG. 4 is a plot comparing the carbon dioxide desorption rate (versus time) for a traditional bald packing against a packing material of the present disclosure (i.e., “washcoated” packing). The results for this plot are obtained using a lab-scale reactor (e.g., a glass 3-neck round bottom flask).

[0015] FIG. 5 is a plot of comparing the energy and operating cost for (i) a process based on methyl ethanolamine and the desorption unit utilizes traditional random packing materials, wherein the energy and operating cost are estimated to be and plausibly higher, against (ii) a process based on ammonia solution as the carbon dioxide absorption solution and the desorption unit utilizes a packing material of the present disclosure, wherein the energy and operating cost are estimated to be and plausibly lower. FIG. 5 shows the clean flue gas exiting from the absorption column and the carbon dioxide exiting from the desorption column.Detailed Description

[0016] The following detailed description refers to the accompanying drawings that show, by way of illustration, specific details and embodiments in which the present disclosure may be practised.

[0017] Features that are described in the context of an embodiment may correspondingly be applicable to the same or similar features in the other embodiments. Features that are described in the context of an embodiment may correspondingly be applicable to the other embodiments, even if not explicitly described in these other embodiments. Furthermore, additions and / or combinations and / or alternatives asdescribed for a feature in the context of an embodiment may correspondingly be applicable to the same or similar feature in the other embodiments.

[0018] The present disclosure relates to a packing material, and a method for forming the packing material. The packing material includes a coating on a substrate. In various embodiments, the coating may be porous. Advantageously, such packing material facilitates (e.g., increase) carbon dioxide (CO2) desorption from a CO2 absorption solution (also referred to herein as a CO2 absorption solvent). The CO2 absorption solution can be from a CO2 capture system. In other words, the present disclosure also relates to a method for removing carbon dioxide from an ammonia-based solution using the packing material.

[0019] The packing material of the present disclosure can be used in CO2 absorption and desorption technology capturing CO2 from dilute CO2 emission sources for related downstream applications. Advantageously, with the packing material of the present disclosure, the CO2 desorption rate in a desorption unit or column can be further improved (e.g., carbon dioxide desorption rate can be improved by about 30% to about 50 % compared to a traditional bald packing (i.e., a packing material that has no coating layer, and understandably also refers to a packing substrate that is not coated)). Accordingly, the energy consumption of a system or a process for carbon capture can be reduced by about 30% to about 50%. For example, in a traditional process involving methyl ethanolamine (MEA) used in carbon capturing, the operating temperature of the desorption unit to recover the carbon absorption solution is about 120°C to about 140°C. However, the desorption unit of such carbon capture system may be reduced to an operating temperature of 90°C, even for ammonia-based solution used as the carbon absorption solution.

[0020] The packing material of the present disclosure is prepared using a dip-coating method. The coated porous layer (e.g., AI2O3 and / or Ti(h) of the packing material, which resides on the surface of a substrate of the packing material, not only facilitates the CO2 desorption from, for example, ammonia (bi)carbonate, but also helps avoid the employment of oversized desorption column and helps reduce the equipment and operating costs.

[0021] In addition, with the method of the present disclosure for forming the packing material, the resultant packing material has strong mechanical strength and improvedresistance against exfoliation of the coating. In the present disclosure, the term “exfoliation” refers to removal of a layer from a surface.

[0022] Accordingly, advantages from the packing material are analogous to advantages from the method for forming the packing material, and vice versa. Accordingly, advantages from the packing material and the method for forming the packing material are analogous to advantages from the method for removing carbon dioxide from an ammonia-based solution, and vice versa.

[0023] Details of various embodiments of the packing material, the method for forming the packing material, and the method for removing carbon dioxide from an ammonia- based solution, advantages associated with the various embodiments are now described below. Where advantages of the embodiments and features are already demonstrated in one or more examples below, they shall not be reiterated for brevity.

[0024] In the present disclosure, there is provided for a packing material. The packing material may comprise a substrate comprising a metal or a ceramic, and a coating on the substrate, wherein the coating may comprise a catalyst which renders removal of carbon dioxide from an ammonia-based solution.

[0025] In various embodiments, the metal may comprise stainless steel (SS) or iron. That is to say, the substrate may comprise stainless steel or iron. In various embodiments, the substrate may comprise Fe (iron) and / or Al (aluminum).

[0026] hi various embodiments, the substrate may be configured to have a honeycomb structure and / or an open-cell structure, wherein the open-cell structure may comprise a three-dimensional network with interconnected channels that may be either regular or irregular in pattern. For instance, in various embodiments, the ceramic may be structurally configured as a honeycomb and / or as an open-cell structure. Said differently, the substrate may comprise a ceramic that may be structurally configured as a honeycomb. In various embodiments, the substrate may comprise a pall ring or a theta ring, wherein the pall ring and the theta ring may be metal or ceramic. In various embodiments, the substrate may also have a monolithic structure, that is, the substrate is a single continuous solid structure that may be metal or ceramic with a honeycomblike open-cell structure.

[0027] In various embodiments, the ceramic may comprise cordierite, silicon carbide (SiC), silicon nitride (SislS ), or zirconium oxide (Z1O2). The cordierite may bemagnesium iron aluminum cyclosilicate mineral. The cordierite may have a chemical formula represented by (MgFe^AhSisOis. The main phase for cordierite (e.g., monolithic) may comprise 2MgO-2A12O3-5SiO2.

[0028] In various embodiments, the catalyst may comprise aluminum oxide, titanium oxide, acid-modified silicon dioxide, and / or a molecular sieve, wherein the molecular sieve may comprise an acid-modified zeolite and / or silicoaluminophosphate.

[0029] In the present disclosure, aluminum oxide may be referred to as alumina, titanium oxide may be referred to as titania, silicon dioxide may be referred to as silica. The aluminum oxide may comprise y-alumina.

[0030] In the present disclosure, the acid-modified silica may refer to silica (silicon dioxide, S i O 2) particles that may have been chemically modified through treatment with acidic substances. The modification may involve contacting or exposing the silica particles to an acid, such as hydrochloric acid, sulfuric acid, or other acids, that may alter the surface properties of silica. For example, acid treatment may introduce silanol (Si-OH) groups onto the silica surface and / or increase surface area and porosity of silica particles.

[0031] In the present disclosure, the molecular sieve may be in the form of powder. The acid-modified zeolite may comprise a zeolite that was treated with acid wherein some aluminum atoms of the zeolite may be replaced with protons, rendering the acid- modified zeolite acidic. A non-limiting example of such acid-modified zeolite molecular sieve may be H-Zeolite Socony Mobil-5 (HZSM-5). The silicoaluminophosphate may comprise silicon, aluminum, and phosphorus, in their framework. Said differently, silicoaluminophosphate may be similar to zeolite in that instead of just silicon and aluminum, silicon (Si), aluminum (Al), and phosphorus (P) atoms may be included. A non-limiting example of such silicoaluminophosphate molecular sieve may be silicoaluminophosphatc-34 (SAPO-34). Molecular sieves, for example, comprising the acid-modified zeolite and / or the silicoaluminophosphate may have a microporous structure (e.g., average pore size of 2 nm or less).

[0032] In various embodiments, the substrate and / or the coating may be porous. The regular or irregular porous structure of the substrate helps to improve the mass transfer during reactions leading to a low pressure drop in the reactor. The coating (e.g., porous) on the substrate can increase the surface area of the packing material (and also improvemass transfer) and enhance the desorption / reaction rate by improving the contact between gas / liquid and the packing material.

[0033] The present disclosure provides for a method for forming the packing material described in various embodiments of the fust aspect. Embodiments and advantages described for the packing material can be analogously valid for the method for forming the packing material as subsequently described herein, and vice versa. As the various embodiments and advantages have already been described above and in examples demonstrated herein, they shall not be iterated for brevity.

[0034] In various embodiments, the method may comprise providing the substrate comprising the metal or the ceramic, treating the substrate with an acid to form a treated substrate, and contacting the treated substrate with a coating mixture, wherein the coating mixture may comprise the catalyst. For the purpose of illustration and to facilitate a better understanding of the method, FIG. 1 shows a non-limiting example of the steps involved in the method.

[0035] In various embodiments, the method may be referred to as a method for preparing an “upgraded packing material” (i.e., the resultant packing material) with porous coating outside an overcrossing skeletal surface, wherein dip-coating is involved, during which a metal-based and / or ceramic -based substrate is used to form the packing material. The term “overcrossing” in the present context means that the skeleton of the substrate includes a continuous network having internal pores that may be regular or irregular in shape. The substrate may have a regular structure or a random structure (hence the resultant packing material may have a regular structure or a random structure). Said differently, the method of the present disclosure for forming the packing material is versatile in that it is compatbile with a substrate having any structure. The obtained “upgraded packing material” prepared from the present method may involve the substrate undergo certain chemical pretreatment and deposited with a sol and / or slurry. The sol and / or slurry may include one or more dispersing components, a surfactant, a binder, and / or a pore-forming agent. The resultant packing material having a coating layer formed from the sol and / slurry exhibits strong mechanical strength and characteristics that prevent coating detachment, and with the coating having a porous surface porous, the CO2 releasing rate from a CO2 absorption solution (e.g., ammonia (bi)carbonate) in a desorption column can be enhanced. In other words, even when thecoating layer is porous (and even if the substrate is porous), the mechanical strength (of the coating layer and substrate) and resistance to exfoliation (of the coating layer) is not compromised, and yet still able to improve desorption rate of carbon dioxide (accelerate CO2 desorption) from a carbon dioxide absorption solution in a desorption unit using less energy.

[0036] hi various embodiments, treating the substrate with the acid may comprise etching the substrate with the acid to form the treated substrate.

[0037] Tn various embodiments, the acid may comprise nitric acid or sulfuric acid.

[0038] In various embodiments, the method may further comprise rinsing the treated substrate with an alcohol or acetone prior to contacting the treated substrate with the coating mixture.

[0039] hi various embodiments, the alcohol may comprise ethanol.

[0040] In various embodiments, the method may further comprise, after contacting the treated substrate with the coating mixture, drying the treated substrate, or calcining the treated substrate.

[0041] In various embodiments, contacting the treated substrate with the coating mixture may comprise applying a sol or colloid containing a precursor of the coating on the substrate surface, followed by the drying and / or the calcining. The precursor refers to a substance that converts into or forms the coating of the resultant packing material. The sol or colloid containing the precursor may comprise one or more components to be applied, for example, aluminum hydroxide (A100H as a precursor for forming aluminum oxide as the catalyst coating), a surfactant, and / or a binder.

[0042] In various embodiments, drying the treated substrate may be carried out at a temperature in a range of 100°C to 200°C, 100°C to 150°C, 150°C to 200°C, etc., or wherein calcining the treated substrate may be carried out at a temperature in a range of 500°C to 600°C, 500°C to 55O°C, 550°C to 600°C, etc.

[0043] hi various embodiments, drying the treated substrate may be carried out at ambient pressure (e.g., atmospheric pressure). The drying may be carried out in absence of an inert environment.

[0044] In various embodiments, calcining the treated substrate may be carried out at ambient pressure (e.g., atmospheric pressure). The calcining may be carried out in absence of an inert environment.

[0045] In various embodiments, the coating mixture may comprise a surfactant and / or a binder. In various embodiments, the surfactant and the binder, in general, may be organic substances. Such organic substances may be burned off completely during the drying and / or the calcining. The term “organic” in the context of the present disclosure, refers to a substance (c.g., a compound) that may contain a carbon atom bonded to one or more hydrogen atoms (and may include other elements like oxygen, nitrogen, sulfur, etc.), forming covalent bonds of carbon-carbon and carbon-hydrogen bonds.

[0046] In various embodiments, the surfactant may comprise cetyltrimethylammonium bromide, polyethylene glycol, or polyvinyl alcohol. In various embodiments, surfactants of the present disclosure, advantageously, confer dispersing properties, promoting uniform dispersion of various components in a sol or colloid for coating and so as to form a stable sol or colloid coating solution (i.c. , the coating mixture). In various instances, the surfactant may not reside in the coating of the resultant packing material, as the surfactant may be removed and / or burned off during drying and / or during calcination.

[0047] In various embodiments, the binder may comprise polyvinyl alcohol, polyvinyl butyral, poly(vinylpyrrolidone), ethyl cellulose, silica gel, or aluminum gel.

[0048] The present disclosure provides for a method for removing carbon dioxide from an ammonia- based solution, wherein the method involves the packing material described in various embodiments of the first aspect. Embodiments and advantages described for the packing material and the method for forming the packing material can be analogously valid for the method for removing carbon dioxide as subsequently described herein, and vice versa. As the various embodiments and advantages have already been described above and in examples demonstrated herein, they shall not be iterated for brevity.

[0049] hi various embodiments, the method for removing carbon dioxide from an ammonia-based solution may comprise providing the packing material described in various embodiments mentioned above, and contacting the packing material with the ammonia-based solution.

[0050] In various embodiments, providing the packing material may comprise having the packing material disposed in a desorption unit which the ammonia-based solution flows through to render removal of carbon dioxide from the ammonia-based solution.

[0051] In various embodiments, contacting the packing material with the ammonia- based solution may be carried out at a temperature of 70°C to 100°C, 70°C to 90°C, 70°C to 80°C, less than 90°C and to about 70°C, etc.

[0052] In various embodiments, the ammonia-based solution may comprise an aqueous solution that may comprise ammonia or an ammonium carbonate.

[0053] hi various embodiments, removal of carbon dioxide from the ammonia-based solution via the present method can include desorption of the carbon dioxide from the ammonia-based solution. The coating may comprise a catalyst, wherein the catalyst may render removal of carbon dioxide from an ammonia-based solution. The catalyst, and understandably the coating which includes such catalyst, are able to catalyze decomposition of the ammonia-based solution (e.g., an ammonium carbonate solution such as ammonium (bi)carbonatcs) for carbon dioxide to be released and / or desorbed therefrom, at the same time improving such desportion / reaction rate and decreasing the temperature needed for such desorption / reaction. In various instances, the ammonia- based solution may be a carbon dioxide absorption solution (abbreviated “CAS” in the present disclosure), which absorbs carbon dioxide in the first instance, and removal of the carbon dioxide from the carbon dioxide absorption solution allows the carbon dioxide absorption solution to be recycled.

[0054] hi various embodiments, the ammonium carbonate may be ammonium carbonate or ammonium bicarbonate, hi other words, the ammonium carbonate may include (NH^COi or (NH^HCOs.

[0055] Advantages of aforesaid embodiments and features of the packing material and methods are already demonstrated in one or more examples below, hence not reiterated for brevity. Also, the various steps involved in the methods are described in the examples and hence not reiterated for brevity.

[0056] The word “substantially” docs not exclude “completely” e.g. a composition which is “substantially free” from Y may be completely free from Y. Where necessary, the word “substantially” may be omitted from the definition of the present disclosure.

[0057] In the context of various embodiments, the articles “a”, “an” and “the” as used with regard to a feature or element include a reference to one or more of the features or elements.

[0058] In the context of various embodiments, the tilde symbolthe term “about”, and the term “approximately”, as applied to a numeric value encompasses the exact value and a reasonable variance. The variance may be ±20%, ±10%, ±5%, ±1%, ±0.5%, ±0.1%, etc.

[0059] As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed items.

[0060] Unless specified otherwise, the terms "comprising" and "comprise", and grammatical variants thereof, are intended to represent "open" or "inclusive" language such that they include recited elements but also permit inclusion of additional, unrecited elements.Examples

[0061] The packing material, method for forming the packing material, and method for removal of carbon dioxide from an ammonia-based solution, are described in further details, by way of non-limiting examples, as set forth below.

[0062] Example 1: Packing material and method for forming the packing material of the present disclosure

[0063] A general overview of the packing material and method for forming the packing material are discussed in this example. The method renders a coating layer on surface of a substrate, involving mainly 3 steps (also see FIG. 1):

[0064] (1) A chemical pretreatment on a pristine packing substrate (metal-based and / or ceramic-based substrate, e.g., a pall ring, a theta ring, a substrate of stainless steel, and a substrate of silicon carbide) before sol and / or slurry deposition. For brevity, in the present disclosure, the packing substrate may be referred to as a substrate. The chemical pretreatment helps to improve coating adhesion.

[0065] (2) Preparations of the blended coating sol and / or slurry, which include one or more components to be dispersed, at least one surfactant, at least one binder, and optionally at least one pore-forming agent. That is to say, either a sol or a slurry, or a mixture of both, can be prepared from a blend of one or more of aforesaid components.

[0066] (3) Immersion of the packing materials into the sol or slurry for formation of the coating layer.

[0067] Among the 3 steps, the proportion of dispersed components, surfactants, and binders in the preparation process of the sol and slurry may confer one or more advantages mentioned above. Said differently, the ratio between these constituents may contribute to enhancing the mechanical strength (e.g., preventing detachment) of the resulting coating layer from the substrate and the dispersion of the dispersed components in the sol or the slurry so as to avoid any aggregation of the coating layer formed on the substrate. A non-limiting example of a weight ratio between the dispersed component(s), surfactant(s), and binder(s), may be 1 to 5 : 85 to 98 : 1 to 10.

[0068] More details for each step of the method for forming the coating layer on the substrate to form the packing material are discussed below. In the context of the present disclosure, as the coating layer advantageously accelerates CO2 desorption from a CO2 absorption solution, the coating layer is referred herein as a “an upgraded packing material catalyst”. Such “upgraded packing material catalyst” may be termed “high efficiency structured catalyst” (e.g., due to their porous structure hence the high efficiency with accelerated CO2 desorption) that can be formed as coatings for CO2 desorption. Accordingly, the details of the steps include:

[0069] (1) Chemical pretreatment: Pretreatments like acid etching and / or ethanol rinse on the selected pristine packing substrate (metal-based and / or ceramic -based) before a sol or a slurry deposition helps improve adhesion of the coating layer thereon.

[0070] (2) Sol / Slurry preparation: The coating sol / slurry may be formed by blending one or more dispersing components (e.g., AhCh / TiCh), surfactant (e.g., cetyltrimethylammonium bromide denoted as CT AB), binder (e.g., silica / aluminium gel), and pore-forming agent (e.g., polymethyl methacrylate). Other examples of these constituents are already described in various embodiments mentioned above and hence for brevity not reiterated.

[0071] (3) Dip-coating: Immersion of the packing materials into the sol or the slurry for coating layer formation, followed by drying or calcination. To obtain the desired loading amount of coating and to achieve a more even coating on the surface of the packing materials, several times of immersion and drying / calcination may be carried out.

[0072] In any case, these steps and their details are also described in various embodiments mentioned above.

[0073] Example 2: Discussion on non-limiting example for preparation of sol (or colloid) for coating

[0074] In various examples, and in various embodiments mentioned above, the coating mixture (which is used exchangably with the “sol”, “slurry” and “colloid”) may further comprise a pore-forming agent for forming pores in the coating. The pore-forming agent may be removed, hence absent in the resultant coating (and absent from the resultant packing material). In various instances, the coating mixture may comprise the surfactant, the binder, and / or the pore-forming agent. In various instances where the surfactant can also form pores in the coating, the pore-forming agent may not be involved. The surfactant may act as pore-forming agent in certain non-limiting instances, as the surfactant may be removed (e.g., burned off), leaving behind voids (i.c., pores) in the coating of the packing material.

[0075] In various examples, and in various embodiments mentioned above, the coating mixture may further comprise one or more dispersing components. The dispersing component may be used to form the catalyst. The dispersing component may be dispersed in water (e.g., deionized water), in the coating mixture. The dispersing component may comprise, for example, boehmite (A1OOH) and / or titanium oxyhydroxide (TiOOH). Other dispersing components to form the respective catalyst mentioned above may be used. The dispersing component may be present in the coating mixture at a concentration of 5 wt% to 10 wt%. As a non-limiting example, boehmite may be present in the coating mixture at 6.8 wt%. The term “wt%” denotes weight percentage. In the coating mixture, the concentration ratio of protons (H+) to the dispersing component (e.g., A100H) may be 0.05 to 0.15. For example, [H+] / [A1OOH] = 0.1. The pH of the coating mixture may be in a range of 3 to 4, which may be adjusted to using an acid, e.g., 1 M HNO3.

[0076] hi various examples, and in various embodiments mentioned above, the coating mixture may comprise a binder. The binder may be present in the coating mixture at a concentration of 3 wt% to 5 wt%. For example, the binder may be present in the coating at 4 wt%.

[0077] Generally, for preparation of a sol (or a slurry or a colloid or the coating mixture), an aging process may be needed. The obtained mixed solution may berefluxed at, for example, 84°C for at least 5 hours and then kept statically for at least 1 day to complete the aging process before use.

[0078] For some of the substrates, a second coating may be applied on the coating layer described above (termed the “first coating layer” or “first coating”). The composition of the sol (the slurry or the colloid or the coating mixture) used for the second coating may vary, for example, it could be a mixture of A100H, y-AhCh. alumina gel, polyvinyl alcohol (PVA), and water. Accordingly, the coating mixture used for the second coating may be referred to as a second coating mixture (a second sol, a second slurry, and a second colloid), and it follows that the coating mixture used to formed the earlier coated layer (i.e., the first coating layer) is referred to as the first coating mixture (“the first sol”, “the first slurry”, and “the first colloid”).

[0079] Example 3: Non-limiting example of procedure for the coating of treated substrate

[0080] The procedures for coating the treating substrate in various examples are described as follows.

[0081] Immerse substrate into the sol / colloid obtained above. Pull out the substrate at a uniform speed of 3 cm / min. Hang the substrate to air dry, followed by drying at 120°C for 3 hours, then calcine at 450°C for 4 hours.

[0082] Repeat the procedure, once the desired film thickness is achieved, high- temperature heat treatment is carried out in a high-temperature furnace to get the final coating layer (600°C for 4 hours).

[0083] For some of the substrates that need a second coating procedure using different sol / colloid in composition (it could be a mixture of A100H, y-AhOi, Alumina gel, PVA, and water), with the same procedure for immersion, drying and calcination carried out.

[0084] hi various examples, and in various embodiments mentioned above, contacting the treated substrate with the coating mixture may be carried out at least one time, or two or more times. Tn various embodiments, contacting the treated substrate with the coating mixture may comprise having the treated substrate immersed in the coating mixture for a duration of 3 hours to 7 hours. For example, the treated substrate may be submerged in the coating mixture for 5 hours. The duration may be shorter or longer, depending on the number of times (of contacting the treated substrate with the coatingmixture) needed to form the coating on the substrate. The number of times may depend on the substrate used.

[0085] In various examples, and in various embodiments mentioned above, contacting the treated substrate with the coating mixture may be canned out with the coating mixture having a temperature of 70°C to 90°C. For example, the coating mixture may be at 84°C.

[0086] Example 4: Non-limiting example on the procedure for the test of coated packing material for ammonia (bi)carbonate solution decomposition for pure CO2

[0087] In various examples, and in various embodiments mentioned above, contacting the packing material with the ammonia-based solution may be canied out at a temperature of 90°C to 97°C (or less than 90°C).

[0088] In various examples, and in various embodiments mentioned above, the ammonia-based solution may contain absorbed CO2. In various embodiments, the ammonia-based solution may be an ammonium carbonate (e.g., ammonium (bi)carbonate) solution obtained from a CO2 absorption process that used an ammonia solution. The ammonia solution is a non-limiting example of the absorption solvent.

[0089] A non-limiting example of the absorption-desorption system configured with the packing material of the present disclosure is shown in FIG. 2 and FIG. 5.

[0090] Example 5: Discussion of results

[0091] In general, the present method for forming the packing material confers a protection mechanism to the coating layer and the substrate of the packing material in that the coating layer formed on the substrate has improved resistance to exfoliation during the desorption process. Advantageously, this avoids the loss of the coating layer, which can in turn lead to poor desorption rates if the coating layer is compromised.

[0092] The present method for forming the packing material is also advantageous in that the method can be applied to any traditional bald packing substrates to convert the traditional bald packing substrates into a packing material having the characteristics of the packing material of the present disclosure.

[0093] From FIG. 3 and FIG. 4, it can be seen that the present packing material, the method for forming the packing material, and the method for removing carbon dioxide involving the present packing material, advantageously facilitate CO2 desorption rate(CAS decomposition rate) in a single run (increased by 30%-50% compared to bald ones), reduce desorption process operating cost by -30% compared to a commercial MEA process (90°C v.s. 120°C-140°C), and avoids the employment of oversized desorption tower, reduce the equipment unit costs.

[0094] The present packing material can be configured in (e.g., housed in) the desorption unit (desorption column) of a carbon capture system (also see FIG. 2 and FIG. 5). The regeneration temperature (the operating temperature for the desorption column used to regenerate the CO2 absorption solution) can be decreased by at least about 27% (e.g., 120°C-140°C reduced to 90°C-95°C), saving energy.

[0095] While the present disclosure has been particularly shown and described with reference to specific embodiments, it should be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the present disclosure as defined by the appended claims. The scope of the present disclosure is thus indicated by the appended claims and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced.

Claims

CLAIMS1. A packing material comprising: a substrate comprising a metal or a ceramic; and a coating on the substrate, wherein the coating comprises a catalyst which renders removal of carbon dioxide from an ammonia-based solution.

2. The packing material of claim 1 , wherein the metal comprises stainless steel.

3. The packing material of claim 1 or 2, wherein the ceramic is structurally configured as a honeycomb and / or as an open-cell structure, wherein the open-cell structure comprises a three-dimensional network with interconnected channels which are regular or irregular in pattern.

4. The packing material of any one of claims 1 to 3, wherein the ceramic comprises cordierite, silicon carbide (SiC), silicon nitride (SisN4), or zirconium oxide (Z1O2).

5. The packing material of any of claims 1 to 4, wherein the catalyst comprises aluminum oxide, titanium oxide, acid-modified silicon dioxide, and / or a molecular sieve, wherein the molecular sieve comprises an acid-modified zeolite and / or silicoaluminophosphate.

6. The packing material of any of claims 1 to 5, wherein the substrate and / or the coating is porous.

7. A method for forming the packing material of any of claims 1 to 6, the method comprising: providing the substrate comprising the metal or the ceramic; treating the substrate with an acid to form a treated substrate; and contacting the treated substrate with a coating mixture, wherein the coating mixture comprises the catalyst.

8. The method of claim 7, wherein treating the substrate with the acid comprises etching the substrate with the acid to form the treated substrate.

9. The method of claim 7 or 8, wherein the acid comprises nitric acid or sulfuric acid.

10. The method of any of claims 7 to 9, further comprising rinsing the treated substrate with an alcohol or acetone prior to contacting the treated substrate with the coating mixture.

11. The method of claim 10. wherein the alcohol comprises ethanol.

12. The method of any of claims 7 to 11, further comprising, after contacting the treated substrate with the coating mixture: drying the treated substrate; or calcining the treated substrate.

13. The method of claim 12, wherein drying the treated substrate is carried out at a temperature in a range of 100°C to 200°C, or wherein calcining the treated substrate is carried out at a temperature in a range of 500°C to 600°C.

14. The method of any of claims 9 to 13, wherein the coating mixture comprises a surfactant and / or a binder.

15. The method of claim 14, wherein the surfactant comprises cctyltrimcthylammonium bromide, polyethylene glycol, or polyvinyl alcohol.

16. The method of claim 14 or 15, wherein the binder comprises polyvinyl alcohol, polyvinyl butyral, poly(vinylpyrrolidone), ethyl cellulose, silica gel, or aluminum gel.

17. A method for removing carbon dioxide from an ammonia-based solution, the method comprising: providing the packing material of any of claims 1 to 6; and contacting the packing material with the ammonia-based solution.

18. The method of claim 17, wherein providing the packing material comprises having the packing material disposed in a desorption unit which the ammonia-based solution flows through to render removal of carbon dioxide from the ammonia-based solution.

19. The method of claim 17 or 18. wherein contacting the packing material with the ammonia-based solution is carried out at a temperature of 70°C to 100°C.

20. The method of any of claims 17 to 19, wherein the ammonia-based solution comprises an aqueous solution comprising ammonia or an ammonium carbonate.

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