Selenium catalyzed carbon dioxide capture

Abstract

Embodiments described herein generally relate to compositions for CO2 absorption, desorption, and / or capture and processes for making such compositions. In one embodiment, a composition for absorbing or desorbing carbon dioxide (CO2) is disclosed. The composition includes an organic amine, selenium containing catalyst, and water. The method for capturing carbon dioxide (CO2) from a gas stream includes introducing a gas stream with a composition under absorption conditions and forming a CO2-enriched composition. The gas stream includes CO2. The method for desorption of carbon dioxide (CO2) from a CO2-enriched composition includes heating a CO2-enriched composition under desorption conditions and separating the CO2 from the CO2-enriched composition to form a CO2-depleted composition.

Description

PATENT Attorney Docket No.: UWYO / 0103PC SELENIUM CATALYZED CARBON DIOXIDE CAPTURE GOVERNMENT RIGHTS

[0001] The invention was made with government support under Grant No. 1632899 awarded by the National Science Foundation. The government has certain rights in the invention. BACKGROUND Field

[0002] Embodiments described herein generally relate to compositions for CO2absorption, desorption, and / or capture, and processes for making such compositions. Description of the Related Art

[0003] Figure 1 is a graph of the global temperature and CO2concentration over time. Carbon dioxide (CO2) is a primary greenhouse gas that contributes to global warming, owing to the emissions from the combustion of fossil fuels. Climate change poses an enormous technological challenge. The average global land and ocean temperature has increased by 1.18°C in the past 100 years, reaching a maximum temperature in 2016. Emissions of greenhouse gases caused by a humans are a central cause for atmospheric temperature increase, in part because of the carbon dioxide (CO2) produced by the combustion of fossil fuel. Moreover, the global monthly mean CO2 output has increased from 338.45 to 410.60 ppm from 1980 to 2019. A similar increase in the average global land and ocean temperature is seen over the same time frame. Therefore, an important component to addressing climate change may be to focus on controlling output CO2 emissions.

[0004] Carbon capture, utilization, and storage (CCUS) is a mature technology that can be used to alleviate CO2discharge to achieve the goals set in the Paris Climate Accord. Among the currently available CO2capture technologies (post-combustion, pre-combustion and oxy- fuel combustion), post-combustion capture may be the most easily applied technology for existing sources of emissions. Direct air capture (DAC) of CO2 is one method of post- 8920991_1 1PATENT Attorney Docket No.: UWYO / 0103PC combustion that may be used to combat global climate change. Chemical absorption using aqueous alkanolamines is a widely researched and mature technology for capturing CO2 in the industrial field. Amine-based CO2absorption is a cost-effective option for capturing CO2from both gas streams (e.g., flue gas) and the atmosphere. Furthermore, CO2capture has had an increasing importance as a resource for material and fuel synthesis.

[0005] A central problem of chemical absorption is the large energy demand for solvent regeneration. In recent decades, two main approaches to solve the energy demand problem have received significant attention. One approach is to improve solvents including redox-active sorbents, synthesis of novel amines. and blending of conventional amines. The other is the introduction of additives such as enzymes and catalysts. Some common additives (e.g., nanoparticles, soluble organic weak acids, and ionic liquids) have been added into amine solvents to reduce the energy consumption during the regeneration performance. Among those additives, nanostructured TiO(OH)2has been useful for monoethanolamine (MEA)-based solvents and K2CO3 / KHCO3-based CO2capture technology.

[0006] Chemisorption-based technologies, however, have slow absorption and desorption reaction kinetics when CO2desorption is at temperatures greater than 100°C. Excessive energies may be needed to vaporize a large amount of liquid water during the CO2desorption operation and to condense the same amount of water vapor prior to CO2desorption during cyclic CO2sorption and desorption. Oxidation-reduction-active sorbents, synthesized novel amines, blended conventional amines, and enzyme and catalyst additives are useful to reduce the energy consumption during the regeneration performance. The catalyzing effect of additives has been effective for both monoethanolamine (MEA)-based CO2capture technology and K2CO3 / KHCO3-based CO2capture technology. However, energy costs remain high. Solid catalysts may be a useful to improve the amine solutions used for CO2 desorption, thus reducing energy consumption and costs.

[0007] Therefore, there is a need for new and improved compositions for the absorption, desorption, and / or capture of CO2that overcome one or more deficiencies in the art. 8920991_1 2PATENT Attorney Docket No.: UWYO / 0103PC SUMMARY

[0008] In one embodiment, a composition for absorbing or desorbing carbon dioxide (CO2), is disclosed. The composition includes an organic amine, and selenium containing catalyst.

[0009] In another embodiment, a method for capturing carbon dioxide (CO2) from a gas stream is disclosed. The method includes introducing a gas stream with a composition under absorption conditions. The gas stream includes CO2. The composition includes an organic amine, a selenium containing catalyst, and water. A CO2-enriched composition is formed.

[0010] In yet another embodiment, a method for desorption of carbon dioxide (CO2) from a CO2-enriched composition is disclosed. The method includes heating a CO2-enriched composition under desorption conditions. The CO2-enriched composition includes an organic amine, an ion thereof, or a combination thereof, a selenium containing catalyst, and water. CO2is separated from the CO2-enriched composition to form a CO2-depleted composition. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only exemplary embodiments and are therefore not to be considered limiting of its scope, and may admit to other equally effective embodiments.

[0012] Figure 1 is a graph of the global temperature and CO2concentration over time.

[0013] Figure 2 is a flow diagram of a method for capturing carbon dioxide (CO2) from a gas stream, according to embodiments. 8920991_1 3PATENT Attorney Docket No.: UWYO / 0103PC

[0014] Figure 3 is a flow diagram of a method for desorption of carbon dioxide (CO2) from a CO2-enriched composition, according to embodiments.

[0015] Figure 4A is a graph of the effect of catalysts on the CO2absorption amount and CA / Co, according to embodiments.

[0016] Figure 4B is a graph of the effect of catalysts on the CO2 desorption amount and rate, according to embodiments.

[0017] Figure 5A is a graph of the effect of catalyst on CO2absorption, according to embodiments.

[0018] Figure 5B is a graph of the effect of the catalyst on CO2 desorption, according to embodiments.

[0019] Figure 5C is a graph of the CO2 desorption rates after about 6,000 s of CO2 absorption, according to embodiments.

[0020] Figure 5D is a graph of the CO2desorption rates after about 7,200 s of CO2absorption, according to embodiments.

[0021] Figure 6 is a graph of the absorption-desorption test, according to embodiments.

[0022] Figure 7A is a Raman profile of the MEA solution with 2.0 wt% Se at various cycles of the absorption-desorption test, according to embodiments.

[0023] Figure 7B is a Fourier transform infrared (FT-IR) spectra profile of the MEA solution with 2.0 wt% Se at various cycles of the absorption-desorption test, according to embodiments.

[0024] Figure 8A is a graph of the intensity-time profiles of Raman spectroscopy of the control, according to embodiments.

[0025] Figure 8B is a graph of the intensity-time profiles of Raman spectroscopy of the 2 wt% Se MEA solution, according to embodiments. 8920991_1 4PATENT Attorney Docket No.: UWYO / 0103PC

[0026] Figure 8C is a graph of the intensity-time profiles of FT-IR spectroscopy of the control, according to embodiments.

[0027] Figure 8D is a graph of the intensity-time profiles of FT-IR spectroscopy of the 2 wt% Se MEA solution, according to embodiments.

[0028] Figure 9A is a graph of the speciation distribution diagrams at a Se concentration of 0.2 wt%, according to embodiments.

[0029] Figure 9B is a graph of the speciation distribution diagrams at a Se concentration of 1.0 wt%, according to embodiments.

[0030] Figure 9C is a graph of the speciation distribution diagrams at a Se concentration of 2.0 wt%, according to embodiments.

[0031] Figure 9D is a graph of the speciation distribution diagrams at a Se concentration of 3.0 wt%, according to embodiments.

[0032] Figure 10A is a graph of the Raman spectra of CO2desorption of the MEA solution with 2 wt% Se, according to embodiments.

[0033] Figure 10B is a graph of the SeO2 solution at different pHs, according to embodiments.

[0034] Figure 11 is a graph of the calculated Raman spectra of the Se species, according to embodiments.

[0035] Figure 12 is a graph of Se species proportion with different Se concentrations in the MEA solution, according to embodiments.

[0036] Figure 13A is a DFT based non-catalytic and catalytic OC2 capture reaction pathways, according to embodiments.

[0037] Figure 13B is a DFT based non-catalytic and catalytic OC2capture energy profiles, according to embodiments. 8920991_1 5PATENT Attorney Docket No.: UWYO / 0103PC

[0038] Figure 14 is an experimental setup for CO2absorption and desorption experiments, according to embodiments.

[0039] To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation. DETAILED DESCRIPTION

[0040] Embodiments of the present disclosure generally relate to compositions for CO2absorption, desorption, capture, and to processes for making such compositions.

[0041] Inventors have found new and improved compositions and methods of direct air capture (DAC) of CO2to combat global climate change. To address the significant challenges for sorption-based DAC technologies, such as low absorption efficiencies and the resultant dilute atmospheric CO2 concentration (about 400 ppm), a new composition can be used for DAC of CO2 that can overcome, at least, this challenge.

[0042] Embodiments described herein generally relate to compositions for CO2absorption, desorption, and / or capture and processes for making such compositions.

[0043] In one embodiment, a composition for absorbing or desorbing carbon dioxide (CO2) is provided. The composition includes at least an organic amine and selenium oxide (SeO2).

[0044] In one embodiment, a process for making a composition for absorbing or desorbing carbon dioxide (CO2) is provided. The process includes treating a mixture comprising SeO2particles, organic amine, and water.

[0045] In one embodiment, a process for capturing carbon dioxide (CO2) from a gas stream is provided. The process includes introducing a gas stream into a composition under absorption conditions, the gas stream comprising CO2, the composition comprising: an organic amine, an ion, thereof, or combinations thereof; selenium oxide (SeO2); and optionally water, an ion thereof, or a combination thereof; and forming a CO2-enriched composition. 8920991_1 6PATENT Attorney Docket No.: UWYO / 0103PC

[0046] As used herein, a “composition” can include component(s) of the composition, reaction product(s) of two or more components of the composition, a remainder balance of remaining starting component(s), or combinations thereof. Compositions of the present disclosure can be prepared by any suitable mixing process.

[0047] The use of headings is for purposes of convenience only and does not limit the scope of the present disclosure. Embodiments described herein can be combined with other embodiments. COMPOSITIONS

[0048] Embodiments of the present disclosure generally relate to compositions for absorbing and / or desorbing carbon dioxide (CO2), and more specifically to selenium dioxide (SeO2) catalyzed CO2capture technology.

[0049] Solid catalysts have been used in the amine solutions for CO2desorption to decrease energy consumption. Solid acid catalysts, include zeolite catalysts, metal oxides, metal hydroxide, sulfated metal oxide, and mixtures of various catalysts.

[0050] Selenium (Se), which is a nonmetal (or, more rarely, a metalloid), may be used in organic synthesis, biochemistry, and electrode materials. Se has similar electrophilicity as halogen ions, and Se has a better reactivity of the Brønsted acid.

[0051] In some embodiments described in the present disclosure, the effect of Se containing catalysts on the MEA aqueous solution regeneration during CO2desorption is defined. Embodiments are performed in consideration of the desorption process of CO2 in MEA solution.

[0052] In at least one embodiment, the optimized mixing ratios of SeO2catalysis introduced in MEA solution are investigated. The catalysis stability is verified by cyclic tests.

[0053] At least one embodiment of this disclosure provides a method of choosing catalysis for MEA solution to lower the energy of CO2capture. 8920991_1 7PATENT Attorney Docket No.: UWYO / 0103PC

[0054] A composition for absorbing or desorbing carbon dioxide (CO2) includes an organic amine and a Se containing catalyst. The Se containing catalyst may include a selenium oxide (SeO2). In some embodiments, the composition further includes water or an ion thereof. In some embodiments, the organic amine may be an ion thereof. The composition is about 0.2 wt% or less or 3.0 wt % or less Se containing catalyst based on a total weight of the composition. The composition has about 10 wt% to about 35 wt% organic amine, such as about 15 wt% organic amine to about 25 wt% organic amine, such as about 20 wt% organic amine. The composition is about 65 wt% to about 85 wt% water.

[0055] The organic amine includes a primary amine compound, a secondary amine compound, a tertiary amine compound, or combinations thereof. In some embodiments, the organic amine comprises monoethanolamine (MEA), diethanolamine (DEA), triethanolamine (TEA), diisopropanolamine (DIPA), monomethyl-ethanolamine (MMEA), methyldiethanolamine (MDEA), diethyl-monoethanolamine (DEMEA), or combinations thereof. In other embodiments, the organic amine comprises a polyethylene amine, the polyethylene amine comprising diethylenetriamine (DETA), triethylenetetramine (TETA), tetraethylenepentamine (TEPA), tetraacetylethylenediamine (TAED), polyethylenehexamine such as pentaethylenehexamine (PEHA), polyethyleneimine (PEI), or combinations thereof. In some embodiments, the composition may include one or more additives. The additives may include a surfactant, an antifoaming agent, or combinations thereof. In some embodiments, the composition may be treated.

[0056] In at least one embodiment, SeO2is introduced as a catalyst to a solution containing CO2-loaded monoethanolamine (MEA), and using about 0.1 wt% to about 3.5 wt% Se, such as about 1.0 wt% to about 3.0 wt%, such as about 2% Se. The solution has about 10 wt% to about 35 wt% MEA, such as about 15 wt% MEA to about 25 wt% MEA, such as about 20 wt% MEA. The introduction of SeO2may both accelerate the absorption rate and increase the amount of CO2 desorption by up to about ~700% to about ~7,100% at about 80°C to about 90°C, reducing overall CO2 capture technology energy consumption. Any of the foregoing numbers can be used singly to describe an open-ended range or in combination to describe a close-ended range. 8920991_1 8PATENT Attorney Docket No.: UWYO / 0103PC

[0057] The reactions of the catalytic mechanism of SeO2are shown as R1-R3. R1-R3 may occur during SeO2 dissolution in water, resulting in the decrease of solution pH, indicating the acidity of SeO2aqueous solution. SeO2+H2O ↔ H2SeO3(R1) H2SeO3 ↔ HSeO3-+H+(R2) HSeO3- ↔ SeO2-+H+(R3)

[0058] The catalytic mechanism of SeO2, which may be represented as the conversion of HSeO3- and H2Se2O62-with pH changes promoting CO2 desorption, may be obtained. Additionally, the catalytic mechanism is stable over at least 100 cycles. Embodiments described herein may enable diprotic acid catalysis theories, and clean energy technology developments.

[0059] Figure 2 is a flow diagram of a method 200 for capturing carbon dioxide (CO2) from a gas stream. At operation 201, a gas stream is introduced into a composition under absorption conditions. The gas stream includes CO2and the composition includes an organic amine and a selenium containing catalyst. In some embodiments the organic amine is a combination of amines or an ion thereof. The selenium containing catalyst includes selenium oxide (SeO2). In some embodiments, the composition includes water, an ion thereof, or a combination thereof.

[0060] Absorption conditions may include: a deionized water that is about 65 wt% to about 85 wt% of the total mass of the composition; a MEA mass that is about 10 wt% to about 35 wt % of the composition; a mass percentages of Se that are about 0.1 wt% or more to about 5 wt% or less, such as about 0.2 wt%, about 1.0 wt%, about 2.0 wt% and about 3.0 wt%; a total flow rate of gas that is about 400 mL / min or more to about 600 mL / min or less, such as about 500 mL / min; a composition of gas that is about 5 vol% CO2 or more to about 15 vol% CO2 or less, such as about 10 vol% CO2, about 5 vol% O2 or less to about 15 vol% O2, such as about 10 vol% O2, and about 70 vol% N2or more to about 90 vol% N2or less, such as about 80 vol% N2; a temperature that is about 15°C or more to about 35°C or less, such as about 25°C; an 8920991_1 9PATENT Attorney Docket No.: UWYO / 0103PC absorption time is about 6,000 s or more to about 8000 s or less, such as about 7,200 s. The effective absorption time (i.e., the length of time for 90% CO2 capture), as a result of the catalytic mechanism of SeO2, may be decreased by about 1% to about 20% when compared to a MEA solution without Se containing catalyst. Any of the foregoing numbers can be used singly to describe an open-ended range or in combination to describe a close-ended range.

[0061] At operation 202, forming a CO2-enriched composition. In some embodiments, the CO2 absorption occurs via Pathway 1: MEA+CO2+H2O ↔ HCO3- + MEAH+(Pathway 1)

[0062] In other embodiments, the CO2absorption occurs via Pathway 2: 2MEA+CO2 ↔ MEACOO- + MEAH+(Pathway 2)

[0063] Figure 3 is a flow diagram of a method 300 for desorption of carbon dioxide (CO2) from a CO2-enriched composition. At operation 301, a CO2-enriched composition is heated under desorption conditions. The CO2-enriched composition includes an organic amine and selenium oxide (SeO2). In some embodiments, the composition includes water or an ion thereof. In some embodiments, the organic amine may include an ion thereof. The CO2- enriched composition may be the CO2-enriched composition formed in method 200.

[0064] Desorption conditions may include: a deionized water that is about 65 wt% to about 85 wt% of the total mass of the CO2-enriched composition, such as about 80 wt%; MEA, MEACOO-, and MEAH+that are about 11 wt% to about 34.9 wt % of the CO2-enriched composition; a mass percentages of Se that are about 0.1% or more to about 4% or less, such as about 0.2%, about 1.0%, about 2.0% and about 3.0%; a total flow rate of gas that is about 400 mL / min or more to about 600 mL / min or less, such as about 500 mL / min (a composition of the gas that is at least N2); a temperature that is about 75°C or more to about 95°C or less, such as about 85°C; a time that is about 800 s or more to about 3,000 s or less, such as about 1,800 s. As a result of the catalytic mechanism of Se containing catalyst, the MEA solution with the Se containing catalyst desorbed more CO2within the same temperature range after about 6,000 s or more to about 8000 s or less than the MEA solution without the Se containing 8920991_1 10PATENT Attorney Docket No.: UWYO / 0103PC catalyst. The amount of CO2desorbed by the MEA solution may be increased by about 12% or more to about 50% or less. The MEA solution with Se containing catalyst has a higher desorption rate at low temperatures, which may reach about 0.04 mmol^s-1or more to about 0.08 mmol^s-1or less. Any of the foregoing numbers can be used singly to describe an open- ended range or in combination to describe a close-ended range.

[0065] At operation 302, the CO2is separated from the CO2-enriched composition to form a CO2-depleted composition. The CO2 is separated and forms an almost-pure CO2 stream. The CO2-depleted stream mainly contains O2and N2.

[0066] The combination of method 200 and method 300 may result in the carbon capture, storage, and utilization of the CO2. Using method 200, CO2 that is produced, such as by the combustion of fossil fuel, may be fed through the composition to capture the CO2and prevent the emission of the CO2into the atmosphere. Subsequently, the method 300 may remove the CO2 captured in method 200 from the composition, allowing the composition to be reused in method 200. The combination of method 200 and method 300 may lead to a decrease in the amount of energy needed to perform CO2capture, and thus lead to a reduction in cost. In addition, the ability to reuse the composition may lead to a decrease in material costs. USES

[0067] Embodiments of the present disclosure also generally relate to uses of the compositions herein. Compositions herein can also be used for various applications.

[0068] Illustrate, but non-limiting, applications include carbon capture and carbon desorption. Applications for CO2capture and carbon desorption also include the use of solid catalysts in the amine solutions for CO2desorption to decrease energy consumption and catalysis for a MEA solution to lower the energy of CO2 capture.

[0069] The following examples are put forth so as to provide those of ordinary skill in the art with a complete disclosure and description of how to make and use embodiments of the present disclosure, and are not intended to limit the scope of the embodiments of the present 8920991_1 11PATENT Attorney Docket No.: UWYO / 0103PC disclosure. Efforts have been made to ensure accuracy with respect to numbers used but some experimental errors and deviations should be accounted for. EXAMPLES Chemicals

[0070] The MEA used in this disclosure was produced by ALDRICH Company, which purity is beyond 99.0%. The catalyst used in this test was Selenium (IV) oxide powder, 99.4% (metals basis), produced by Alfa Aesar Company. Test Methods

[0071] In order to investigate the catalytic effect of SeO2 on desorption, Raman spectroscopic investigation was conducted by using an Advantage 785 Raman Spectrometer with a 758 nm laser and up to 60 mW radiation power during test, and Fourier transform infrared (FT-IR) spectroscopy spectra were collected on a Nicolet Magna-IR 760 spectrometer with a resolution of 4 cm-1by scanning 60 times from 400 to 4000 cm-1.

[0072] Figure 14 is an experimental setup for CO2absorption and desorption experiments. The experimental setup for CO2 absorption and desorption experiments includes a mass flow controller 1, a mass flow controller control module 2, a thermocouple 3, a furnace 4, a glass reactor 5, a magnetically coupled stirrer 6, a condenser 7, a moisture remover 8, a data recorder 9, a gas analyzer 10, and a thermostatic water bath 11. The glass reactor 5 is a 250 mL glass reactor in the furnace 4, which is on the magnetically coupled stirrer 6. In each sorption experiment, MEA (about 100 g of about 20 wt%) in deionized (DI) water was used. Experiments were done without catalyst (control) and with Se containing catalysts (having weight percentages of, e.g., about 0.2, about 1.0, about 2.0, and about 3.0 wt% Se). The weight percentage in this disclosure means the ratio of Se element weight (not the SeO2weight) to the total solution weight.

[0073] CO2 absorption experiments were done at room temperature (~25 °C) and atmospheric pressure (about 0.78 bar at Laramie in Wyoming). The MEA solution (about 20 wt%) with or without catalyst was added into the reactor with a stirring rate of about 300 rpm. 8920991_1 12PATENT Attorney Docket No.: UWYO / 0103PC Three individual corresponding gas cylinders provided CO2(about 99.99%), O2(about 99.999%), and N2 (about 99.999%), respectively, which were controlled by three Parker mass flow controllers (Model 201) and a control module (CM-400). Then, three different gases were combined together and made using the simulated flue gas with a total flow of about 500 ml min-1, which was constituted with about 10 vol% CO2, about 10 vol% O2, and about 80 vol% N2. The simulated flue gas was bubbled into the MEA solution. The absorption time of fresh and cyclic MEA solutions were about 7,200 s and about 1,800 s, respectively. The CO2and O2concentrations of the outlet gas were measured with an inline gas analyzer (NDIR ZRE, California Analytical Instruments). The data of measured concentration, time, also and the temperature were recorded by a data recording unit (DataChart ® 2000, Monarch). Therefore, the CO2absorption percent curve and the accumulative CO2absorption amount could be drawn and calculated.

[0074] CO2desorption step was achieved by heating the spent solution with CO2sorption. The heat was generated by a furnace (ZNHW heater, Gongyi City Yuhua Instrument Co., Ltd.) with a desired temperature (about 85 °C) gradually. Nitrogen, a carrier gas with a flow rate of about 500 mL min-1, with the CO2desorption from the spent solution went through a check value, a condenser, a moisture remover, and an inline gas analyzer (NDIR ZRE, California Analytical Instruments) which measured the CO2 concentration. The cold resource of condenser was provided by a thermostatic water bath (polystat, Cole-Parmer). The data of CO2 concentration in the mixture gas and the corresponding temperatures of the spent solution were record by the recording unit during the whole desorption step with the time of about 1,800 s. The time was enough for the concentration of CO2 dropping below about 0.01%, which indicated the end of the desorption step. When the spent solution and the furnace were cooled to the room temperature (about 25 °C), the following cyclic CO2absorption step began.

[0075] To test different Se species and how each species depended on different pH values, the mixture aqueous solution of SeO2and NaOH was prepared. The total solution volume was about 5 ml, the [Se] was about 0.258 mol / L (which is comparable to the CO2absorption experiment described above). 8920991_1 13PATENT Attorney Docket No.: UWYO / 0103PC

[0076] Density functional theory (DFT) studies on catalytic mechanism of CO2absorption and desorption processes may be performed by means of Dmol3program in Materials studio package. The Becke’s three-parameter hybrid (B3LYP) may be applied as exchange- correlation functional for Raman spectra calculation and the exchange-correlation interaction may be treated within the generalized gradient approximation by the Perdew-Burke-Ernzerh functional (GGA-PBE) as applied to geometry optimization and transition states searching.

[0077] Grimme method may be used for DFT-D correction and a double numerical basis set with polarization function on all atoms (the DNP basis set) may also be used. The following thresholds represent non-limiting examples that may be used for the geometry optimization: 1×105Hartree for the maximum energy change, 2×10-3Hartree / Å for the maximum force, and 5×10-3Å for the maximum displacement. The complete linear synchronous transit and quadratic synchronous transit (LST / QST) calculations may be performed to obtain the structures of transition state. Vibrational frequencies may be calculated at the optimized geometries to identify the nature of the stationary points (no imaginary frequency) and the transition state (only one imaginary frequency). EXPERIMENTAL

[0078] Figure 4A is a graph of the effect of catalysts on the CO2absorption amount and CA / Co. The total amounts of CO2 absorption without Se (hereinafter referred to as the control), with about 0.2 wt% Se, about 1.0 wt% Se, about 2.0 wt% Se, and about 3.0 wt% Se is about 165 mmol, about 167 mmol, about 159 mmol, about 149 mmol, and about 138 mmol, respectively. The results indicate that the addition of about 0.5 wt% Se or more to about 40 wt% Se or less, such as about 1.0 wt% Se to about 3.0 wt% Se does not increase the amount of CO2absorption, while that of about 0.1 wt% Se or more to about 0.4 wt% Se or less, such as about 0.2 wt% Se, may slightly increase the amount of CO2absorption by about 1% to about 2%, such as about 1.40%, compared to control used during sorption procedures.

[0079] The addition of about 0.2 wt% Se, about 1.0 wt% Se, about 2.0 wt%, and about 3.0 wt% Se as catalyst into the 2 wt% MEA solution may decrease the solution pH from values of about 12.10 (control) to about 11.9, about 11.4, about 11.2, and about 11.1, respectively. Additionally, the decrease of alkalinity in the absorption solution results in less CO2 absorption. 8920991_1 14PATENT Attorney Docket No.: UWYO / 0103PC

[0080] The length of period for 90% CO2capture, targeted by Department of Energy (DOE), without catalyst in MEA solution is 5,154 s. In some non-limiting embodiments, with about 0.2 wt% Se, about 1.0 wt% Se, about 2.0 wt% Se, and about 3.0 wt% Se, example values for 90% CO2capture are about 5,400, s about 5,100 s, about 4,400 s, and about 4,200 s, respectively. As the concentration of Se in a solution is increased, the effective absorption time decreases. The effective absorption time may decrease by about 1% or more to about 20% or less, such as about 2%, about 14%, and about 19% in solution with about 1.0 wt% Se, about 2.0 wt% Se, and about 3.0 wt% Se, respectively.

[0081] Figure 4B is a graph of the effect of catalysts on the CO2 desorption amount and rate. When compared with the MEA solution without Se (control), MEA solution with about 1.0 wt% Se or more to about 3.0 wt% Se or less, such as about 2.0 wt% Se could desorb more CO2 within the same temperature range after about 6,000 s or more to about 8000 s or less, such as about 7,200 s. Without Se, the MEA solution desorbs about 10 mmol CO2or more to about 13 mmol CO2or less, such as about 12 mmol CO2. However, with Se, the amounts of CO2 desorbed are about 12 mmol or more to 18 mmol or less, such as about 13.5 mmol, about 15.6 mmol, about 16.4 mmol, and about 14.6 mmol with about 0.2 wt% Se, about 1.0 wt% Se, about 2.0 wt% Se, and about 3.0 wt% Se respectively. This may produce an increase in desorption of about 12% or more to about 50% or less, such as about 15%, about 33%, about 39%, and about 23%, respectively, compared with the control. The MEA solution with about 2.0 wt% Se has a higher desorption rate at low temperatures, which may reach about 0.04 mmol^s-1or more to about 0.08 mmol^s-1or less, such as about 0.065 mmol^s-1, at as early as about 550 s or more, such as about 600 s. The desorption rates of the control, the about 0.2 wt% Se, about 1.0 wt% Se, about 2.0 wt% Se, and about 3.0 wt% Se are about 0.020 mmol^s-1, about 0.023 mmol^s-1, about 0.038 mmol^s-1, and about 0.030 mmol^s-1, respectively. Any of the foregoing numbers can be used singly to describe an open-ended range or in combination to describe a close-ended range.

[0082] Table 1 shows a summary of the absorption and desorption experimental details. Based on the same amount of CO2 absorption (130 mmol or more to about 160 mmol or less), a desorption test of the control and about 2.0 wt% Se is performed. 8920991_1 15PATENT Attorney Docket No.: UWYO / 0103PC Table 1: Summary of Absorption and Desorption Experimental Details.

[0083] Figure 5A is a graph of the effect of catalyst on CO2 absorption. Figure 5B is a graph of the effect of the catalyst on CO2desorption. The control has a CO2absorption amount at about 6,000 s (e.g., ~150 mmol), which is close to CO2absorption amount of the control at about 7,200 s. The CO2 absorption amount of the control at about 6,000 s (e.g., ~150 mmol) is lower than that of the about 2.0 wt% Se at about 7,200 s (e.g., ~150 mmol) solution. After 7,200 s of CO2absorption, the CO2desorption rate and amount with about 2.0 wt% Se at about 7,200 s solution is higher than the control. Therefore, the Se catalyzed solution had better desorption than the control.

[0084] Figure 5C is a graph of the CO2desorption rates after about 6,000 s of CO2absorption. After about 6,000 s of CO2 absorption, the CO2 desorption rate and amount of the MEA solution with about 2.0 wt% Se is about 555 s and about 614 s, respectively. Compared to the control, the 2.0 wt% solution has a desorption rate and amount at 555 s and 614 s, respectively. This is about 4,000% or more to about 8,000% or less, such as about ~7,000% and about ~4,600% higher, respectively, compared with the control. Any of the foregoing numbers can be used singly to describe an open-ended range or in combination to describe a close-ended range.

[0085] Figure 5D is a graph of the CO2 desorption rates after about 7,200 s of CO2 absorption. After about 7,200 s of CO2 absorption, the 2.0 wt% solution has a desorption rate 8920991_1 16PATENT Attorney Docket No.: UWYO / 0103PC and amount at about 555 s and about 591 s, respectively. This is about 400% or more to about 700% or less, such as about 650% and about 470%, respectively, higher than the control. Thus, with about 1.0 wt% Se or more to about 3.0 wt% Se or less, CO2desorption increases.

[0086] Figure 6 is a graph of the absorption-desorption test. About 100 cycles of the absorption-desorption test are performed to evaluate the stability of the SeO2 catalyst. There are no decreasing trends in absorption or desorption within about 100 cycles. The average CO2 capture capacity during 100 cycles is about 14 mmol or more to about 16 mmol or less, such as about 16 mmol, which is close to the mmol value obtained in the first run.

[0087] Figure 7A is a Raman profile of the MEA solution with 2.0 wt% Se at various cycles of the absorption-desorption test. Figure 7B is a Fourier transform infrared (FT-IR) spectra profile of the MEA solution with 2.0 wt% Se at various cycles of the absorption-desorption test. After the 1st, 5th, 10th, and 100th cycle, the MEA solution with 2.0 wt% Se has similar Raman and FT-IR profiles, indicating that there is little change in the structure of components in MEA solution, including MEA and Se species. Therefore, the SeO2as a catalyst in MEA based CO2 capture system demonstrated good stability and reversibility. Processes for Absorbing and / or Desorbing Carbon Dioxide

[0088] Figure 8A is a graph of the intensity-time profiles of Raman spectroscopy of the control. Figure 8B is a graph of the intensity-time profiles of Raman spectroscopy of the 2 wt% Se MEA solution. Figure 8C is a graph of the intensity-time profiles of FT-IR spectroscopy of the control. Figure 8D is a graph of the intensity-time profiles of FT-IR spectroscopy of the 2 wt% Se MEA solution. Raman and FI-IR spectroscopies are utilized to investigate the SeO2 catalytic effect on CO2 desorption. The Raman spectroscopy shows four peaks at about 1,000 cm-1or more to about 1,200 cm-1or less. A peak at about 1,018 cm-1may be attributed to C-O(H) stretching of HCO3-, a peak at 1,068 cm-1may be attributed to symmetric C-O stretching of CO32-, 1,102 cm-1may be attributed to attributed MEA, and 1,160 cm-1may be attributed to symmetric C-O stretching of MEACOO-. The peak of HCO3- at 1018 cm-1in control decreases as CO2desorption occurs, while the changes in that of CO32-at 1,068 cm-1and MEACOO−at 1,102 cm-1are irregular. In MEA solutions with about 2.0 wt%, peaks of CO32-and MEACOO−change irregularly, but the peaks of HCO3- decrease quicker than the 8920991_1 17PATENT Attorney Docket No.: UWYO / 0103PC control. Therefore, the use of 2.0 wt% Se may result in more CO2desorption. Any of the foregoing numbers can be used singly to describe an open-ended range or in combination to describe a close-ended range.

[0089] The FT-IR spectra indicate a similar trend of the HCO3- peaks during the desorption process. As shown in FT-IR results at Figure 8C and Figure 8D, there are peaks at 1,323 cm-1, 1,488 cm-1, and 1,561 cm-1respectively attributed to the stretching of N-COO-, the symmetric stretching asymmetric stretching of COO-, and MEACOO-. The peaks at 1,384 cm-1and 1,634 cm-1are attributed to CO32-and HCO3-, respectively. The peak of HCO3- in the control first decreases slowly at about 0-8 min, then quickly at about 8-10 min, and decreases slowly again at about 10-30 min. This trend of change is consistent with that of CO2the desorption rate, which is up to the highest value around about 11 min, as shown in Figure 4B. In the MEA solution with about 2.0 wt% Se, the peak of HCO3- decreasing quickly at about 0-10 min, and then decreases slowly at about 10-30 min. Therefore, both Raman and FT-IR spectroscopies indicate that SeO2catalysis in the CO2desorption process impacts on HCO3- change.

[0090] Figure 9A is a graph of the speciation distribution diagrams at a Se concentration of 0.2 wt%. Figure 9B is a graph of the speciation distribution diagrams at a Se concentration of 1.0 wt%. Figure 9C is a graph of the speciation distribution diagrams at a Se concentration of 2.0 wt%. Figure 9D is a graph of the speciation distribution diagrams at a Se concentration of 3.0 wt%. Se species generally exist in aqueous solution both in different valence states and species, such as SeO32-, HSeO3-, HSe2O63-, H2Se2O62-, H3Se2O6-, H5Se2O6+, H4Se2O6, H2SeO3as Se (IV), depended on the different pH. In some embodiments, to clarify which specific Se species is playing as catalyst in CO2 desorption process, the speciation calculations are performed to present the relationship between Se species and solution pH. The speciation calculations are based on the equilibrium between different Se species. At lower pH (e.g., lower than about 8.5), H2Se2O62-and HSeO3- are dominant, while at higher pH (e.g., higher than about 9.5) SeO32-is dominant over the other species.

[0091] Figure 10A is a graph of the Raman spectra of CO2desorption of the MEA solution with 2 wt% Se. Figure 10B is a graph of the SeO2 solution at different pHs. In some embodiments, a series of Raman spectra of the solutions during CO2 desorption process with 8920991_1 18PATENT Attorney Docket No.: UWYO / 0103PC SeO2are obtained to determine the specific catalyst. After addition of MEA into water, three new absorption peaks appear at about 900 cm-1or less to about 400 cm-1or more, such as about 870 cm-1, about 844 cm-1, and about 493 cm-1, which track to the reported characteristic peaks of MEA at about 900 cm-1or less to about 400 cm-1or more, such as about 873 cm-1, about 845 cm-1, and about 481 cm-1, and therefore may be attributable to MEA. Moreover, the peaks at about 870 cm-1and about 844 cm-1are also shown in the Raman spectra of MEA solution in Figure 9A-9D. However, after CO2absorption, the peak at about 485 cm-1or more to about 495 cm-1or less, such as about 493 cm-1disappears, which may result from the changes in the structure of MEA to MEACOO- and MEAH+. And after CO2 absorption, a peak at about 550 cm-1or more to about 650 cm-1or less, such as about 598 cm-1appears, which may be attributed to the absorption products MEACOO- and MEAH+. Any of the foregoing numbers can be used singly to describe an open-ended range or in combination to describe a close-ended range.

[0092] In some embodiments, after addition of about 2.0 wt% Se, a new absorption peak appears at about 800 cm-1or more to about 820 cm-1or less, such as about 809 cm-1. To ensure this peak is attributed to SeO32-, the Raman spectra of the about 2.0 wt% Se MEA solution with different pH values are used to distinguish Se species. According to the Se distribution with pH shown in Figures 9A-9D, when solution pH is higher than about 11.0, SeO32-is the only component in the solution. As shown in Figure 10B, when solution pH is higher than about 8.5, there is a peak at about 800 cm-1or more to about 820 cm-1or less, such as about 807 cm-1, which appears after SeO2addition. Therefore, it is likely that the peak at about 800 cm-1or more to about 820 cm-1or less, such as about 807 cm-1is the characteristic peak of SeO32-. A peak at about 850 cm-1or more to about 860 cm-1or less, such as about 854 cm-1, appears when solution is lower than about 8.0, as shown in Figure 10B. According to the Se speciation distribution, when solution pH is lower than about 8.0 in about 2.0 wt% Se MEA solution, H2Se2O62-accounts for 80% of the solution composition. The characteristic peaks of H2Se2O62-are at about 850 cm-1or more to about 860 cm-1or less, such as 857 cm-1, which is close to the about 854 cm-1in the Raman spectra. Thus, peaks at about 854 cm-1are likely attributed to H2Se2O62-. However, the characteristic peak of H2Se2O62-at about 850 cm-1or more to about 860 cm-1 or less, such as about 854 cm-1are found in the Raman spectra of the desorption solution. The Raman spectra further show that when H2Se2O62-combines with absorption 8920991_1 19PATENT Attorney Docket No.: UWYO / 0103PC product HCO3- or MEACOO-, the characteristic peak of 854 cm-1will move slightly towards the higher frequency. Because MEA has a characteristic peak at 873 cm-1, and the amount of MEA is much larger than that of H2Se2O62-, the characteristic peak of H2Se2O62-is blocked from display. In addition, there is no other distinct characteristic peak, which may be attributed to HSeO3- and HSe2O63-. This is likely because the amount of HSeO3- and HSe2O63-are too small compared with H2Se2O62-or SeO32-to be detected in the about 2.0 wt% Se solution. Any of the foregoing numbers can be used singly to describe an open-ended range or in combination to describe a close-ended range.

[0093] Table 2 is a summary of the speciation calculations. Table 3 is a summary of the properties the MEA solution. As illustrated in Figure 10A, three new peaks at about 700 cm-1or less to about 400 cm-1or more, such as about 691 cm-1, about 642 cm-1, and about 429 cm-1, appear in the solution when CO2 has been desorbed for 8 minutes. After CO2 desorption is carried out for 8 minutes, the solution pH is about 9. According to the Se speciation distribution with pH, when pH is around 9.0, HSe2O63-reaches the highest proportion. As a result, these three new peaks may be attributed to HSe2O63-. Table 2: Summary of the Speciation Calculations.8920991_1 20PATENT Attorney Docket No.: UWYO / 0103PC Table 3: The Properties of MEA Solution (SeO2and NaOH, [Se]=0.258 mol / L).

[0094] Figure 11 is a graph of the calculated Raman spectra of the Se species. The theoretical Raman spectra are calculated to identify the characteristic peak of HSe2O63-, as well as that of SeO32-, HSeO3- and H2Se2O62-. By comparing our calculated Raman with the other’s experimental Raman of SeO32-, HSeO3- and H2Se2O62-, the reliability of the calculated Raman spectra is demonstrated. Although HSe2O63-is structurally composed of HSeO3- and SeO32-, the calculated Raman shows that HSe2O63-has two peaks at 610 cm-1and 687 cm-1without overlap with the characteristic peaks of other Se species, which are respectively attributed to the stretching vibration of Se-OH in HSeO3- and Se-O in SeO32-. Additionally, they are close to the two peaks appearing at about 630 cm-1or more to 700 cm-1or less, such as about 642 cm-1and about 691 cm-1, in experimental Raman of the solution CO2 desorbed for 8 minutes. And in the calculated Raman, the peak at about 390 cm-1may be attributed to the SeO-H bending and symmetrical deformation modes of SeO32-. Moreover, after the combination of HSe2O63with HCO3- and MEACOO-, this peak moves to the higher frequency, about 400 cm- 8920991_1 21PATENT Attorney Docket No.: UWYO / 0103PC1or more to about 430 cm-1or less, such as about 411 cm-1and about 423 cm-1, respectively, which are close to the new band at 429 cm-1in the experimental Raman. Thus, the new peaks at about 700 cm-1or less to 400 cm-1or more, such as about 691 cm-1, about 642 cm-1, and about 429 cm-1appeared in the solution after CO2has desorbed for about 8 minutes are attributed to the characteristic peak of HSe2O63-. As desorption progresses, Se species transfer from each other depended on the solution pH. In some cases, the characteristic peak of HSe2O63can be detected, and may not be detected in the SeO2aqueous solution. This may result from an attenuation caused by interaction of the components in desorption solution with SeO3- and HSe2O63-. As a result, the interaction weakens the signal of SeO32-and HSe2O63-, and may enable the signal of HSe2O63-to be obtained under the same signal-to-noise ratio of Raman. Any of the foregoing numbers can be used singly to describe an open-ended range or in combination to describe a close-ended range. Theoretical Examples

[0095] The FT-IR spectroscopies of the MEA solution in Figure 8 illustrate that the absorbed products may include MEACOO- and HCO3-. Accordingly, CO2 absorption may proceed according to the following: MEA+CO2+H2O ↔ HCO3- + MEAH+(Pathway 1) 2MEA+CO2 ↔ MEACOO- + MEAH+(Pathway 2)

[0096] Figure 12 is a graph of Se species proportion with different Se concentrations in the MEA solution. In some embodiments, when SeO2is added into the CO2adsorption and desorption system, the different Se species are formed, including SeO32-, HSeO3-, H2Se2O62-and HSe2O63-. Depending on the pH of a solution and the total concentration of selenium, these Se species may transfer between each other, resulting in a variety of species proportions, some of which may play the role of catalyst. Considering the difficulty in studying their separate catalytic mechanism by experimental methods, the density functional theory (DFT) calculations may be performed to further understand the catalytic mechanism of Se species. 8920991_1 22PATENT Attorney Docket No.: UWYO / 0103PC

[0097] Figure 13A is a DFT based non-catalytic and catalytic OC2capture reaction pathways. Figure 13B is a DFT based non-catalytic and catalytic OC2 capture energy profiles. Table 4 is a summary of the relative energies in the reaction pathways. The specific role of each Se species in Pathway 1 and Pathway 2 may be studied by Transition Searching (TS) separately. Table 4: Summary of the Relative Energies in the Reaction Pathways.

[0098] In some embodiments, the catalytic CO2 desorption processes may begin from the interaction of desorption complexes and HCO3- (Pathway 1) or MEACOO- (Pathway 2), which may be composed of Se species and MEAH+and end with CO2escape from the absorption complexes. Absorption complexes may be composed of a Se catalyst and MEA or H2O. 8920991_1 23PATENT Attorney Docket No.: UWYO / 0103PC

[0099] In some embodiments, which may represent an inversion of the above catalytic CO2desorption processes, the catalyzed CO2 absorption processes may begin from the absorption complex and end with the decomposition of absorption product from the desorption complex. The non-catalytic pathways may also be calculated for the purpose of comparison. The relative energies are shown in Figure 13B, including the energy barriers (Ebarrier), maximum energy change of the reaction (Emax), and desorption reaction energies (Ereaction). The Emax of the pathways are compared to illustrate the effect of the Se species step requiring the most energy in the reaction process, as this step may be the rate-determining step of the reaction,.

[0100] In some embodiments, Emax in the desorption process of Pathway 1 catalyzed by SeO32-, HSeO3-, H2Se2O62-, and HSe2O63-is about 30 kJ^mol-1or more to about 80 kJ^mol-1or less, such as about 71 kJ^mol-1, about 33 kJ^mol-1, about 40 kJ^mol-1, and about 95 kJ^mol-1, respectively. Meanwhile, the Emax in the desorption process of Pathway 2 catalyzed by SeO32-, HSeO3-, H2Se2O62-, and HSe2O63-is about 40 kJ^mol-1or more to about 140 kJ^mol-1or less, such as about 133 kJ^mol-1, about 47 kJ^mol-1, about 65 kJ^mol-1, and about 131 kJ^mol-1, respectively. The Emax in the catalyzed Pathway 1 is generally smaller than that in catalyzed Pathway 2. Moreover, Ereactionin Pathway 1 is smaller than that in the catalyzed Pathway 2, indicating the catalyzed desorption preferentially proceeds in Pathway 1, which is consistent with the experimental results. For example, as shown in Figures 8A-8D, during CO2 desorption, HCO3- as the reactant of Pathway 1 results in a decrease in the amount of HCO3-, while MEACOO- does not change significantly. Any of the foregoing numbers can be used singly to describe an open-ended range or in combination to describe a close-ended range.

[0101] In some embodiments, and as compared with the non-catalytic pathways, with HSeO3- and H2Se2O62-, Ebarrierin Pathway 1 decreased by about 25 kJ^mol-1or more to about 35 kJ^ mol-1or less, such as about 28.3 kJ^mol-1and about 29.5 kJ^mol-1, respectively, presenting the promotion effect on CO2 desorption. As shown in Figure 13A, with HSeO3- or H2Se2O62-, accompanying the process of the proton transfer from MEAH+to HSeO3- and that from HSeO3- to HCO3- completed in one step, CO2desorbs. Thus, CO2desorption process may be the proton transfer process, which indicates that the catalyst may be helpful to proton transfer to promote CO2 desorption. Compared with other Se species, H2Se2O62-, which is associated by two HSeO3-, obtains the most protons. As Bronsted acid catalyst, the most positive effect of 8920991_1 24PATENT Attorney Docket No.: UWYO / 0103PC H2Se2O62-may come from abundant protons. Thus, from this point of view, the catalytic effect may be H2Se2O62-> HSeO3- ≈ HSe2O63-> SeO32-. Any of the foregoing numbers can be used singly to describe an open-ended range or in combination to describe a close-ended range.

[0102] In some embodiments, as shown in Figure 13B, a HCO3- from HSe2O63-desorption complex requires energy of about 70 kJ^mol-1or more to about 80 kJ^mol-1or less, such as about to 73 kJ^mol-1. Moreover, because of a strong attraction to protons, HSe2O63-may capture protons from week acid, such as MEAH+, which may result in a structure of the desorption complex composed of HSe2O63-and MEAH+is H2Se2O62-and MEA. In some cases, the energy for regeneration of HSe2O63-about 100 kJ^mol-1or more to about 110 kJ^mol-1or less, such as about 105 kJ^mol-1. Similarly, SeO32-, which may have strong regeneration energy, may be about 125 kJ^mol-1or more to about 135 kJ^mol-1or less, such as about 128.1 kJ^mol-1. Any of the foregoing numbers can be used singly to describe an open-ended range or in combination to describe a close-ended range.

[0103] Table 5 is a summary of the solution pHs at different conditions. In some embodiments, according to pH change during CO2 desorption, pH may be about 8 or more to 9 or less, such as about 8.85 to about 9.33, when desorption begins. Within this range, Se species may exist as H2Se2O62-, which may result in an increase of CO2desorption. In general, the higher total Se concentration may bring the better catalytic effect on desorption. However, in some cases, high total Se concentration may not always be conducive to CO2 desorption where proton-attracted HSe2O63-is present in larger quantities. Any of the foregoing numbers can be used singly to describe an open-ended range or in combination to describe a close-ended range. Table 5: Solution pHs at Different Conditions.8920991_1 25PATENT Attorney Docket No.: UWYO / 0103PC

[0104] In some embodiments, the absorption process may be catalyzed by SeO32-, HSeO3- , H2Se2O62-, and HSe2O63-in Pathways 1 and / or 2. The Emax may be about 20 kJ^mol-1or more to about 75 kJ^mol-1or less, such as about 21.7 kJ^mol-1for SeO32-, about 48.0 kJ^mol-1for HSeO3-, about 62.5 kJ^mol-1for H2Se2O62-, and about 73.0 kJ^mol-1for HSe2O63-. The Emaxof Pathway 2 may be about 103 kJ^mol-1or more to about 603 kJ^mol-1or less, such as about 12.1 kJ^mol-1for SeO32-, about 53.0 kJ^mol-1for HSeO3-, about 33.6 kJ^mol-1for H2Se2O62-, and about 40.3 kJ^mol-1for HSe2O63-. Compared with the desorption processes, Emaxin the adsorption process of Pathway 1 and Pathway 2 are closer to one another, indicating CO2 absorption could follow both pathways. This may be corroborated in experimental results in which MEACOO- and HCO3- simultaneously exist in absorption solution, as shown in Figures 8A-8D. In some cases, EReaction in catalytic Pathway 2 may be higher, which in the process catalyzed by SeO32-, HSeO3-, H2Se2O62-and HSe2O63-may be about -140 kJ^mol-1or more to about -50 kJ^mol-1or less, such as about -141.5 kJ^mol-1for SeO32-, about -58.7 kJ^mol-1for HSeO3-, about -101.4 kJ^mol-1for H2Se2O62-, and about -119.1 kJ^mol-1for HSe2O63-. Any of the foregoing numbers can be used singly to describe an open-ended range or in combination to describe a close-ended range.

[0105] In some embodiments, compared with the non-catalytic pathways, the decrease of Emax is largest in the absorption process of Pathway 1 and Pathway 2 with SeO32-. Values for Emax in these conditions may be about 50 kJ^mol-1or less to about 20 kJ^mol-1or more, such as about 47.3 kJ^mol-1in Pathway 1 and about 28.8 kJ^mol-1in Pathway 2, respectively, showing the positive effect of SeO32-on CO2 absorption. In some cases, the promotional effect of SeO32-on CO2 absorption may be due to its prevention of direct interaction between MEAH and HCO3- or MEACOO- to form the stable absorption product, which is beneficial to the decomposition of HCO3- or MEACOO- from the desorption complex to complete the absorption process. In some cases, the specific role of SeO32-is determined by its prevention 8920991_1 26PATENT Attorney Docket No.: UWYO / 0103PC of direct interaction between MEAH and HCO3- or MEACOO- and its effect on pH. As shown in the Table 5, the pH of the solution used to absorb CO2 is about 9 or more to about 10 or less, such as about 9.5 to about 9.9. According to a distribution rule of Se species, as shown in Figure 12, SeO32-may dominate in the solution, and the proportion of SeO32-may increase with the decrease of total Se concentration. In the solutions with different Se concentrations, the order of SeO32-proportion from large to small may be described according to the following relationship: about 0.2 wt% > about 1.0 wt% > about 2.0 wt% > about 3.0 wt%. In some cases, the order of H+concentration in the solution with different Se concentration from small to large may be described according to the following relationship: about 0.2 wt% < about 1.0 wt% < about 2.0 wt% < about 3.0 wt%. These relationships are generally consistent with the experimental result that CO2absorption increases as the total Se concentration decreases. When the total Se concentration is very low (e.g., about 0.2%), and the total H+concentration is very low, the promotion effect of SeO32-with high proportions may exceed any the inhibition effect of H+, generating positive results from the solution having low Se concentration. In some cases, CO2 absorption amount in the different concentrations may be described according to the following non-limiting relationship: about 0.2 wt% > control > about 1.0 wt% > about 2.0 wt% > about 3.0 wt% in the absorption experiment.

[0106] In some embodiments, an SeO2 catalyst may exhibit different performances at different pH values according to different Se species. In some cases, at the beginning of CO2 absorption, higher pH exists in at least the form of SeO32-. This may have a positive effect on absorption. In some cases, at the beginning of desorption, higher pH exists in the form at least of HSeO3- and H2Se2O62-, which may promote desorption. As a result, the use of a SeO2 catalyst may significantly advance the development of a new generation of CO2capture technology. For example, the use of a SeO2catalyst may decrease the parasitic penalty of these systems, capital investment, and environmental protection. The Se catalyst can make CO2 capture less demanding for high quality energy, and thus may be made widely available using low-temperature heat (e.g., those from solar collectors or waste heat), which may be used for CO2 capture. This may lead to a significant decrease in parasitic energy penalty, capital and operating costs, as well as creating a benefit by the elimination of the secondary environmental pollutant resulting from MEA degradation during high-temperature CO2desorption of 8920991_1 27PATENT Attorney Docket No.: UWYO / 0103PC conventional CO2 capture technologies. Accordingly, SeO2is a green transcendent catalyst for CO2 capture technology. SeO2Aqueous Solution at Different pHs Se Speciation Calculation

[0107] Table 6 is the equilibrium constants of deprotonation and protonation reaction of the Se species. Based on the reactions and the K value in the reference, the equilibrium relationships between different Se species. Table 6: Equilibrium Constants of Deprotonation and Protonation Reaction of Se Species.

[0108] The detailed calculation is presented as follows:  8920991_1 28PATENT Attorney Docket No.: UWYO / 0103PC

[0109] If the solution is composed of 80g H2O, 20 g MEA and 2.8679g SeO2.

[0110] All the concentration of Se2+,

[0111] E4 indicates the relationship between pH (=7~14) and [HSeO3-]. 8920991_1 29PATENT Attorney Docket No.: UWYO / 0103PC

[0112] Thus, the relationship of pH and concertation of [HSeO3-] are obtained. Moreover, according (E1)~(E3), the relationship of pH and concentration of [SeO32-], [H2Se2O62-] and [HSe2O63-] are obtained.

[0113] All documents described herein are incorporated by reference herein, including any priority documents and / or testing procedures to the extent they are not inconsistent with this text. As is apparent from the foregoing general description and the specific embodiments, while forms of the embodiments have been illustrated and described, various modifications can be made without departing from the spirit and scope of the present disclosure. Accordingly, it is not intended that the present disclosure be limited thereby. Likewise, the term “comprising” is considered synonymous with the term “including.” Likewise whenever a composition, an element, a group of elements, or a method is preceded with the transitional phrase “comprising,” it is understood that we also contemplate the same composition, method, or group of elements with transitional phrases “consisting essentially of,” “consisting of,” “selected from the group of consisting of,” or “Is” preceding the recitation of the composition, element, elements, or method, and vice versa, such as the terms “comprising,” “consisting essentially of,” “consisting of” also include the product of the combinations of elements listed after the term.

[0114] In the foregoing, reference is made to embodiments of the disclosure. However, it should be understood that the disclosure is not limited to specific described embodiments. Instead, any combination of the following features and elements, whether related to different embodiments or not, is contemplated to implement and practice the disclosure. Furthermore, although embodiments of the disclosure may achieve advantages over other possible solutions and / or over the prior art, whether or not a particular advantage is achieved by a given embodiment is not limiting of the disclosure. Thus, the foregoing aspects, features, embodiments and advantages are merely illustrative and are not considered elements or 8920991_1 30PATENT Attorney Docket No.: UWYO / 0103PC limitations of the appended claims except where explicitly recited in a claim(s). Likewise, reference to “the disclosure” shall not be construed as a generalization of any inventive subject matter disclosed herein and shall not be considered to be an element or limitation of the appended claims except where explicitly recited in a claim(s).

[0115] For purposes of this present disclosure, and unless otherwise specified, all numerical values within the detailed description and the claims herein are modified by “about” or “approximately” the indicated value, and consider experimental error and variations that would be expected by a person having ordinary skill in the art. For the sake of brevity, only certain ranges are explicitly disclosed herein. However, ranges from any lower limit may be combined with any upper limit to recite a range not explicitly recited, as well as, ranges from any lower limit may be combined with any other lower limit to recite a range not explicitly recited, in the same way, ranges from any upper limit may be combined with any other upper limit to recite a range not explicitly recited. For example, the recitation of the numerical range 1 to 5 includes the subranges 1 to 4, 1.5 to 4.5, 1 to 2, among other subranges. As another example, the recitation of the numerical ranges 1 to 5, such as 2 to 4, includes the subranges 1 to 4 and 2 to 5, among other subranges. Additionally, within a range includes every point or individual value between its end points even though not explicitly recited. For example, the recitation of the numerical range 1 to 5 includes the numbers 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, among other numbers. Thus, every point or individual value may serve as its own lower or upper limit combined with any other point or individual value or any other lower or upper limit, to recite a range not explicitly recited.

[0116] As used herein, the indefinite article “a” or “an” shall mean “at least one” unless specified to the contrary or the context clearly indicates otherwise. For example, embodiments comprising “an organic amine” include embodiments comprising one, two, or more organic amines, unless specified to the contrary or the context clearly indicates only one organic amine is included.

[0117] While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow. 8920991_1 31PATENT Attorney Docket No.: UWYO / 0103PC

[0118] Certain molecules disclosed herein may contain one or more ionizable groups [groups from which a proton can be removed (e.g., –COOH) or added (e.g., amines) or which can be quaternized (e.g., amines)]. All possible ionic forms of such molecules and salts thereof are intended to be included individually in the disclosure herein.

[0119] While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow. 8920991_1 32

Claims

PATENT Attorney Docket No.: UWYO / 0103PC What is claimed is:

1. A composition for absorbing or desorbing carbon dioxide (CO2), comprising: an organic amine; and selenium containing catalyst.

2. The composition of claim 1, further comprising water.

3. The composition of claim 2, wherein, the water is deionized water.

4. The composition of claim 1, wherein selenium containing catalyst is a selenium oxide (SeO2), and wherein an amount of selenium in the composition is about 0.2 wt% or less or 3.0 wt % or less based on a total weight of the composition.

5. The composition of claim 1, wherein the organic amine comprises a primary amine compound, a secondary amine compound, a tertiary amine compound, or combinations thereof.

6. The composition of claim 5, wherein the organic amine comprises monoethanolamine (MEA), diethanolamine (DEA), triethanolamine (TEA), diisopropanolamine (DIPA), monomethyl-ethanolamine (MMEA), methyldiethanolamine (MDEA), diethyl- monoethanolamine (DEMEA), a polyethylene amine, the polyethylene amine comprising diethylenetriamine (DETA), triethylenetetramine (TETA), tetraethylenepentamine (TEPA), tetraacetylethylenediamine (TAED), polyethylenehexamine such as pentaethylenehexamine (PEHA), polyethyleneimine (PEI), or combinations thereof.

7. The composition of claim 1, further comprising one or more additives, the one or more additives comprising a surfactant, an antifoaming agent, or combinations thereof.

8. A method for capturing carbon dioxide (CO2) from a gas stream, comprising: introducing a gas stream with a composition under absorption conditions, the gas stream comprising CO2, the composition comprising: 8920991_1 33PATENT Attorney Docket No.: UWYO / 0103PC an organic amine; a selenium containing catalyst; and water; and forming a CO2-enriched composition.

9. The method of claim 8, wherein the organic amine comprises a primary amine compound, a secondary amine compound, a tertiary amine compound, or combinations thereof.

10. The method of claim 8, wherein the selenium containing catalyst comprises selenium oxide (SeO2).

11. The method of claim 8, wherein absorption conditions comprise: a total flow rate of a gas that is about 400 mL / min or more to about 600 mL / min or less; a composition of the gas comprising: about 5 vol% CO2to about 15 vol% CO2; about 10 vol% CO2, about 5 vol% O2 to about 15 vol% O2; and about 70 vol% N2 to about 90 vol% N2; a temperature from about 15°C to about 35°C; and an absorption time of about 6,000 s to about 8000 s.

12. A method for desorption of carbon dioxide (CO2) from a CO2-enriched composition, comprising: heating a CO2-enriched composition under desorption conditions, the CO2-enriched composition comprising: an organic amine, an ion thereof, or a combination thereof; a selenium containing catalyst; and water; and separating CO2from the CO2-enriched composition to form a CO2-depleted composition. 8920991_1 34PATENT Attorney Docket No.: UWYO / 0103PC 13. The method of claim 12, wherein the organic amine comprises a primary amine compound, a secondary amine compound, a tertiary amine compound, or combinations thereof.

14. The method of claim 12, wherein the selenium containing catalyst comprises selenium oxide (SeO2).

15. The method of claim 12, wherein desorption conditions comprise: a total flow rate of a gas that is about 400 mL / min to about 600 mL / min, wherein the gas comprises at least N2; a temperature that is about 75°C to about 95°C; and a time that is about 800 s to about 3,000 s. 8920991_1 35

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