Patent Application
20250121325
The present disclosure relates to an electrochemical system for capturing carbon dioxide from the atmosphere and other carbon dioxide sources and the simultaneous storage of electrical storage.
Carbon dioxide (CO2) capture, utilization, and storage (CCUS) is a promising solution to the global challenges related to the excessive emission of CO2. Strategies for capturing CO2, including the direct air capture (DAC) of low concentration CO2 from the atmosphere and the capture of higher concentrations of CO2 from emissions from industrial manufacturing and agricultural sources, are important for addressing these challenges. Although DAC is a promising solution to the global challenges associated with the excessive emission of CO2, significant technical barriers exist for the efficient extraction of ultra-dilute (approximately 400 ppm) CO2 from the ambient atmosphere, e.g., air, and other CO2 sources.
In some aspects, the presently disclosed subject matter provides a system for capturing CO2 comprising:
In some aspects, the ion exchange membrane of the first membrane reactor and/or the ion exchange membrane of the second membrane reactor comprises a cation exchange membrane or a proton exchange membrane.
In some aspects, the ion exchange membrane of the first membrane reactor and/or the ion exchange membrane of the second membrane reactor comprises an anion exchange membrane or a hydroxyl exchange membrane.
In some aspects, the CO2 absorption reactor further comprises a water trap.
In other aspects, the presently disclosed subject matter provides a method for capturing CO2 from a CO2 source comprising:
In some aspects, the method further comprises transmitting an electricity output of the second membrane reactor to the first membrane reactor or to an external electricity grid.
In other aspects, the presently disclosed subject matter provides an eDAC system for capturing CO2 comprising:
In some aspects, the eDAC system further comprises a fifth chamber for a brine solution, wherein the fifth chamber comprises an anion exchange membrane (AEM) and a cation exchange membrane (CEM), wherein the fifth chamber is positioned (i) between the first and second chambers in the HER electrolyzer such that the AEM is contacting the redox mediate solution and the CEM is contacting the catholyte, or (ii) between the third and fourth chamber in the HOR fuel cell such that the AEM is contacting the anolyte and the CEM is contacting the redox mediate solution.
In some aspects, the eDAC system further comprises a second electrolyte storage tank that comprises (i) an inlet in fluid communication with the Mx+1 outlet of the fourth chamber and (ii) an Mx+ inlet in the first chamber.
In some aspects, the fifth chamber of the eDAC system is positioned between the first and second chambers in the HER electrolyzer and wherein the HOR fuel cell further comprises an AEM positioned between the third and fourth chambers such that the AEM is contacting the anolyte and the redox mediate solution.
In some aspects, the eDAC system further comprises a sixth chamber comprising hydrogen gas contacting the GDE.
In some aspects, the eDAC system further comprises directly introducing the hydrogen gas to the GDE.
In some aspects, the fifth chamber of the eDAC system is positioned between the third and fourth chambers in the fuel cell unit and wherein the electrolyzer unit further comprises a CEM between the first and second chambers such that the CEM is contacting the redox mediate solution and the catholyte.
In some aspects, the system further comprises a module for receiving an electricity output from the HOR fuel cell and providing the electricity output to the HER electrolyzer.
In certain aspects, M is Fe or V.
In other aspects, the presently disclosed subject matter provides a method for capturing carbon dioxide from a carbon dioxide source, the method comprising:
In some aspects, the method further comprises transmitting an electricity output of the HOR fuel cell to the HER electrolyzer or to an external electricity grid.
In some aspects of the one or more methods disclosed herein for capturing CO2 from a CO2 source, the carbon dioxide source comprises a dilute source of carbon dioxide. In certain aspects, the dilute source comprises ambient air. In certain aspects, the carbon dioxide source comprises a concentrated source of carbon dioxide. In particular aspects, the concentrated source of carbon dioxide comprises a point source of carbon dioxide. In more particular aspects, the point source of carbon dioxide comprises an effluent or gas stream from an industrial source. In yet more particular aspects, the industrial source is selected from the group consisting of an electrical power plant, a concrete plant, and a flue stack.
Certain aspects of the presently disclosed subject matter having been stated hereinabove, which are addressed in whole or in part by the presently disclosed subject matter, other aspects will become evident as the description proceeds when taken in connection with the accompanying Examples and Drawings as best described herein below.
The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee.
Having thus described the presently disclosed subject matter in general terms, reference will now be made to the accompanying Figures, which are not necessarily drawn to scale, and wherein:
The presently disclosed subject matter now will be described more fully hereinafter with reference to the accompanying Figures, in which some, but not all embodiments of the inventions are shown. Like numbers refer to like elements throughout. The presently disclosed subject matter may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Indeed, many modifications and other embodiments of the presently disclosed subject matter set forth herein will come to mind to one skilled in the art to which the presently disclosed subject matter pertains having the benefit of the teachings presented in the foregoing descriptions and the associated Figures. Therefore, it is to be understood that the presently disclosed subject matter is not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims.
I. Electrochemical Capture of Carbon Dioxide from Air with Electricity Storage
Carbon dioxide capture technology can be divided into several categories including, but not limited to, chemical absorption, physical adsorption, membrane separation, cryogenic separation, and the like. The strong binding force of chemical absorption achieved through acid-base reaction, host-guest recognition, and other chemical actions helps to achieve high-efficiency absorption of CO2 in a very low concentration CO2 environment, such as the ambient atmosphere. Fasihi et al., 2019. Reasonably designed chemical circulation systems generally include a CO2 absorption process and an absorbent regeneration process.
Existing DAC technologies typically rely on molecular adsorbents, for example, amine-based polymers, to selectively interact with CO2 in air to achieve chemical separation. In capture processes based on chemical absorption, however, the chemical absorbent primarily combines with CO2 through an acid-base interaction to achieve direct air capture. The capture process often is carried out spontaneously. The regeneration of the absorbent and release of CO2, however, are non-spontaneous processes that consume energy.
Processes known in the art are mainly based on the thermal decomposition of specific CO2 conjugates, such as calcium carbonate, Keith et al., 2018, and aniline bicarbonate with its derivatives. Hanusch et al., 2019. The heat energy required for these steps is often realized by a device driven by fossil energy, which, in turn, generates additional CO2 emissions.
Despite the extensive efforts deployed on research in this area, this method is still challenged by the high energy intensity associated with the liberation of CO2 and regeneration of sorbents. This process usually relies on temperature, pressure and/or humidity swing cycles. Molecular absorbents known in the art typically suffer from oxidative degradation during such swing cycles.
In contrast to DAC systems known in the art, the processes of absorbent regeneration and CO2 recovery in the presently disclosed subject matter are based on an electrochemical system and an acid-base neutralization reaction. As a result, the processes can be completely driven by renewable electricity and carried out at room or intermediate temperature.
Electrochemical methods utilizing reversible redox pairs or ion pumps have been studied for capturing CO2 from flue gas. Although some reversible redox pairs, such as 9,10-phenanthrenequinone (PAQ) and several organometallic complexes, have been shown to be more energy efficient than the amine-based thermochemical sorbents (owing to their relatively weak binding to CO2), sluggish capture kinetics and high costs of such molecular sorbents largely limit their large-scale implementation.
Meanwhile, electrochemical pumps have been reported for CO2 capture by using molten carbonate or aqueous alkaline fuel cells. Molten carbonate is a highly corrosive paste, however, and its operation requires high temperatures (for example, greater than 800° C.). An anion-exchange membrane in alkaline fuel cells has yet to be developed that is capable of tolerating the poisoning and deactivation caused by the high concentration of carbonate involved in the DAC process. Electrochemical pumps also suffer from the mismatching kinetics between the reaction with, for example, about 400 ppm CO2, and the oxygen reduction reaction (ORR) that is typically utilized to drive the ionic current. Therefore, existing electrochemical CO2 capture approaches are inappropriate for large-scale DAC applications.
Accordingly, there is a need for breakthroughs in the development of new sorbents that can be facilely (re)generated at high energy efficiency, new absorption chemistry that has fast kinetics for reaction with dilute CO2 from air, and robust systems that are compatible with intermittent energy sources and implementable under various field conditions.
A comprehensive technology assessment of DAC systems published by The American Physical Society (APS) pointed out that the only industrially viable sorbents are inorganic hydroxides (e.g., NaOH or KOH) and monoethanolamine (MEA). To this end, without wishing to be bound to any one particular theory, it is thought that the use of an inorganic base can substantially boost the rate and capacity performance of DAC owing to the high exothermic nature of the reaction. Based on the acid-base reaction equilibria (pKa1=6.35 for H2CO3/HCO3 and pKa2=10.33 for HCO3−/CO32−), the absorption capacity of 1 mol/L NaOH is estimated to range from about 6.8 to about 13.6 mmol-CO2/g-NaOH, corresponding to the pH range of about 10.01 to about 11.39 for the outlet solution. These values are substantially higher than the typical working capacity of less than about 3 mmol-CO2/g for amine-based sorbents. In addition, over 80% of the absorption capacity can be achieved over a short contact time by taking advantage of the fast kinetics of acid-base reactions.
Accordingly, the presently disclosed subject matter provides systems and methods of their use for the low-cost and highly-efficient direct air capture (DAC) of CO2 from the ambient atmosphere and other CO2 sources, including, but not limited to, low-concentration CO2 sources. As used herein, the terms “ambient air” or “ambient atmosphere” are used interchangeably and refer to “that portion of the atmosphere, external to buildings, to which the general public has access.” See 40 C.F.R. § 50.1(e). Further, the term “atmosphere” as used herein generally refers to the troposphere, which is the lowest region of the atmosphere, extending from the earth's surface to a height of about 3.7-6.2 miles (6-10 km), and is the lower boundary of the stratosphere. The current concentration of CO2 in the troposphere is about 400 ppm.
The presently disclosed systems and methods provide for CO2 release and absorbent regeneration based on electrochemistry and acid-base neutralization. Compared with the thermochemical decomposition method and the membrane exchange method known in the art, the presently disclosed systems and methods have the advantages of low energy consumption and simplicity of the system.
Importantly, the presently disclosed approach is based on robust acid-base chemistries. Carbon dioxide capture is highly cost-sensitive for both capital and operating costs. To address this cost-sensitivity, the presently disclosed subject matter is based on low-cost general chemicals rather than expensive specialized chemicals. As such, the presently disclosed technology can be combined with existing industrial environments, such as the existing brine/seawater electrolysis industry, to achieve low-cost and highly-efficient direct air capture (DAC) of CO2. In addition, the presently disclosed technology is scalable and can be directly applied to various existing renewable power generation equipment, in part, because the technology is based on room temperature or medium temperature reaction equipment and can achieve its own thermal energy balance through delicate heat exchange between multiple unit operations.
As used herein, the term “room temperature” refers to a temperature of about 25° C., including, in some embodiments, a temperature range from about 1° C. to about 30° C., including 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, and 30° C., in other embodiments, a temperature range from about 15° C. to about 30° C., including about 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, and 30° C., in other embodiments, a temperature range from about 15° C. to about 25° C., including about 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, and 25° C., and in some embodiments, a temperature range from about 20° C. to about 25° C., including about 20, 21, 22, 23, 24, and 25° C.
As used herein, the term “medium temperature” refers to a temperature between about 30° C. to about 250° C., including 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, and 250° C.
Accordingly, in some embodiments, the presently disclosed subject matter provides an electrochemistry-based CO2 capture system, which is significantly less energy intensive than the current state-of-the-art CO2 capture systems and has an all-liquid high efficiency reaction system with the capability to achieve large-scale chemical storage of electricity from an electrical grid or other electricity source. As a result, the presently disclosed system can be implemented to capture CO2 from the ambient atmosphere and other CO2 sources and store electrical energy simultaneously.
The utility of this approach is twofold. First, the direct capture of CO2 can address the problem of excessive CO2 emission in the atmosphere. Second, the storage of electrical energy can improve the efficiency of renewable energy. Accordingly, the presently disclosed subject matter can be used in clean energy, the chemical and petrochemical industry, and in smart electricity grids, and, in general, any factory or institution that implements industrialized carbon emission reduction.
A. Renewable Capture of CO2 from Air Using Electrochemically Produced Acid and Base
In one embodiment, the presently disclosed subject matter provides an electrochemical system including an electrolytic cell for chlor-alkali process, a hydrogen-chlorine fuel cell, a gas-liquid separator, a CO2 absorber, and an acid-base reactor.
Referring now to
More particularly, as provided in
Referring now to
One of ordinary skill in the art would recognize that different parameters and unit specifications can affect the performance of the CO2 capture system. Ion exchange membranes, absorbent concentration and flow rates are major factors that influence the efficiency and cost of carbon dioxide capture in this system.
A variety of ion exchange membranes as well as their combinations can meet the electrochemical reaction needs of the system. As shown in
Referring again to
In certain embodiments, the electrical energy output at least partially compensates an energy input required for electrolyzing the brine at membrane reactor (a).
As provided hereinabove, compared to existing DAC technologies known in the art, the presently disclosed eDAC takes advantage of an ambient-condition acid-base reaction to capture and release CO2. This process is believed to be much faster in kinetics with barrierless reactions, more energy-efficient by avoiding a high-temperature swing/calcination process, and more sustainable by leveraging renewable (but intermittent) energy sources.
Further, to avoid energy-intensive desorption using a temperature swing, the regeneration of captured CO2 also can be achieved by adding in-situ produced HCl to the sodium (bi)carbonate solution, where the acid-base reaction can be accomplished under ambient conditions (for example, see
The presently disclosed electrochemical systems possess high energy conversion efficiencies as compared to conventional thermochemical syntheses, and moreover, when integrated, can substantially reduce the energy consumption for the simultaneous production of acid and base demanded for the eDAC. Together with the closed mass balance by recirculation of NaCl (derived from the CO2 regeneration reactions, R1 or R2 immediately herein below, the presently disclosed acid-base chemistries can enable robust, energy-efficient and cost-effective DAC under various field conditions.
NaHCO3+HCl→NaCl+H2O+CO2 R1:
Na2CO3+2HCl→2NaCl+H2O+CO2 R2:
In some embodiments, the CO2 absorption reactor captures CO2 from a gas source comprising carbon dioxide and reacts the CO2 with the electro-synthesized caustic soda. In some embodiments, the CO2 absorption reactor comprises a device wherein the gas source comprising CO2 comes in contact with at least a portion of the as-synthesized caustic soda from the first membrane reactor to produce an aqueous solution comprising a solubilized carbonate, e.g., NaHCO3/Na2CO3. CO2 absorption reactors are well known in the art. For example, in some embodiments, a CO2 absorption reactor comprises a column, wherein the column is packed with beads or comprises a membrane contactor.
The gas source comprising CO2 is contacted with at least a portion of the caustic soda in a column of the CO2 absorption reactor removing some of the CO2 from the gas source and producing a carbonate solution, which is directed to acid-base reactor of the eDAC system. In some embodiments, the gas source comprising CO2 is contacted with at least a portion of the as-synthesized caustic soda in a countercurrent manner within the CO2 absorption reactor.
In some embodiments, the gas source is air. In some embodiments, the gas source is obtained from various industrial sources that release carbon dioxide including carbon dioxide from combustion gases of fossil fueled power plants, e.g., conventional coal, oil and gas power plants, or IGCC (Integrated Gasification Combined Cycle) power plants that generate power by burning syngas; cement/concrete manufacturing plants that convert limestone to lime; ore processing plants; fermentation plants; and the like. In some embodiments, the gas source may comprise other gases, e.g., nitrogen, oxides of nitrogen (nitrous oxide, nitric oxide), sulfur and sulfur gases (sulfur dioxide, hydrogen sulfide), and vaporized materials. In some embodiments, the system includes a gas treatment system that removes at least a portion of the other gases in the gas source before the gas source is introduced to the CO2 absorption reactor.
The carbonate solution, e.g., NaHCO3/Na2CO3, from the CO2 absorption reactor can be introduced into the acid-base reactor with at least a portion of the as-synthesized HCl from the second membrane reactor to produce a brine solution and CO2(g). In some embodiments, the acid-base reactor comprises a continuously stirred tank reactor. In some embodiments, at least a portion of the brine solution can be directed to the brine source in fluid communication with the first membrane reactor. The CO2 is vented from the acid-base reactor. Neutralizers are well known in the art.
Although not shown in
It should be noted that the eDAC system and methods disclosed herein are distinct from the previously reported electrochemical pumps. Referring once again to
Further, the chlor-alkali electrolyzer (
For example, in representative embodiments, starting from a laboratory-scale membrane reactor, the electrolyzer can be stepwise scaled-up to 200 cm2 to achieve the production of 1-M NaOH at 60 L/day. In combination with the development of advanced ClER and hydrogen evolution reaction (HER) electrocatalysts, a high Faradaic efficiency of greater than 96% and lower cell voltage of less than 3 V can be achieved at a high current density of 400 mA/cm2 in a laboratory-scale reactor. The energy efficiency for the system can reach up to 70.5% in such chlor-alkali systems.
With the two side-product streams, H2 and Cl2, derived from the chlor-alkali process, HCl can be facilely generated via direct electrolysis using a proton-exchanged membrane fuel cell (PEMFC) (
Since H2 and Cl2 are produced synchronously in a 1:1 stoichiometric ratio from the chlor-alkali process, the coupling of a H2—Cl2 fuel cell with the electrolyzer can close the mass balance and produces HCl stoichiometrically, which can then be used to neutralize the (bi)carbonate solution derived from the CO2 absorption reactor (
Absorbent concentration is an important factor that can affect the absorption process efficiency of CO2 in the absorption unit. A high-concentration caustic soda solution will greatly improve the absorption efficiency and obtain a solution with high total CO2 absorption. Caustic soda solution with a concentration between about 0.01 mol/L to about 15 mol/L, including 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9. 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 10.5, 11, 11.5, 12, 12.5, 13, 13.5, 14, 14.5, and 15 mol/L can effectively absorb CO2.
For example, in a system using 1-mol/L caustic soda as an absorbent, each ton of carbon dioxide captured from the air will consume 505 kWh of electricity, including 1333 kWh of electricity consumed by the chlor-alkali electrolysis cell and −828 kWh of electricity compensated by hydrogen-chlorine fuel cells. This power utilization efficiency far exceeds the existing thermochemical process-based capture system.
Further, it has been shown that the aqueous fuel cell adopting flowing liquid catholyte can accommodate higher current density and provide better cell stability as compared to the anhydrous cell. Owing to the high hydrophilicity of the product HCl, most of the water will be removed from the cell when it is operated under anhydrous conditions, and this process increases the membrane resistance and ultimately causing membrane damage, which decreases the cell performance.
By using (Ru0.09Co0.91)3O4 as the electrocatalyst for chlorine reduction, this type of H2—Cl2 fuel cell exhibited extremely low activation losses even with low precious metal loading (approximately 0.15 mg Ru/cm2). It delivered 0.4 W/cm2 with 90% Faradaic efficiency, and the maximum power density exceeded 1 W/cm2. The cell operating pressure also plays an important role in the discharge performance. Increasing the pressure from 12 psig to 70 psig results in a maximum power density increasing from 0.4 W/cm2 to 1 W/cm2. The primary impact of increasing cell pressure is dissolving more Cl2 into the electrolyte, consequently, improving the mass transfer to the electrochemical interface and catalyst.
Further, the development of aqueous H2—Cl2 fuel cells uses diluted HCl as feeding anolyte to derive a concentrated HCl solution. According to the literature, an output current density of up to 400 mA/cm2 can be achieved at a voltage of 1.0 V with the production of 3 mol/L HCl. By coupling with a best-performing chloro-alkali electrolyzer, an overall energy efficiency of 61% (calculated as 1−(2.19 V—1.36 V)/(2.19 V/EEchlor-alkali−1.36V*EEfuel cell) can be targeted for the production of base and acid media for the eDAC, which is substantially higher than the typical energy efficiency of 10-20% (2 MWh/ton in use versus the theoretical energy consumption of approximately 250 kWh/ton) for existing DAC technologies.
A techno-economic assessment (TEA)-driven approach can be applied to achieve optimal parameters for the presently disclosed eDAC technology. This approach will be achieved by first performing mass and energy balance calculations and modeling the (electro)chemical processes using ASPEN Plus. A preliminary TEA shows that building a commercial plant with the process capability of 1 MtCO2 per year will generate a capital cost of $320-363/ton-CO2 per year. The key instruments for such a plant are the electrolyzer/fuel cell and the adsorption towers as CO2 absorption reactor. Electricity is a major part of the operation cost which is highly dependent on the electricity price and system energy efficiency. In general, the energy cost will be less than $50 per ton of captured CO2 with 60% energy efficiency at the electricity price of $0.02 per kWh. In our preliminary TEA with $0.02/kWh, a first-of-a-kind (FOAK) DAC plant in this scale without a large government incentive (e.g., carbon credit) would be at ˜$142/tCO2 in total while the Nth DAC plant can reduce the levelized cost to ˜$107/ton-CO2 (Table 1). If off-peak electricity can be used at lower prices, the levelized cost of the eDAC can even go substantially lower in practice, e.g., <$100/ton at $0.015/kWh.
In some embodiments, the presently disclosed subject matter provides an electrochemistry-based CO2 capture system and flow battery system. This system can be operated with various types of flow batteries based on different redox pairs, e.g., redox mediates, including, but not limited to, Fe2+/Fe3+, V2+/V3+, V4+/V5+, Cr(III)/Cr(VI), Mn(II)/Mn(III), and the like, which can be represented as Mx+/M(x+1), wherein M is a metal selected from the group consisting of Fe, V, Cr, and Mn and X is an integer selected from 2, 3, and 4.
Referring now to
In some embodiments, the system further comprises an energy recovery unit for receiving an electricity output from the HOR fuel cell and providing the electricity output to the HER electrolyzer. As such, the HOR fuel cell is capable of generating electricity during operation. The generated electricity can be applied to the electrolyzer so that the energy consumption or energy needed from an electricity grid is reduced. Generally, any of the systems disclosed herein can include an energy recovery unit.
Referring again to
Once needed, the charged anolyte and hydrogen is introduced into a membrane-based fuel cell (e) to produce discharged catholyte containing Fe2+ in the HOR cathode chamber and hydrochloric acid solution in the HOR anode chamber. The electrical energy output partially compensates the energy of the membrane reactor (a) electrolysis or puts into the electricity grid for other usage, and the hydrochloric acid solution generated at the same time neutralizes the reaction in the acid and alkali reactor (g) by reacting with sodium carbonate or sodium bicarbonate produced after absorption, and CO2 is released as a pure gas.
In another embodiment, the electrolyzer/fuel cell combination of
In the electrolyzer/fuel cell combination illustrated in
In the electrolyzer/fuel cell combination illustrated in
One of ordinary skill in the art would recognize that further modifications of the presently disclosed system can be made to improve its performance without changing the chemical reactions of the system and accommodate other important gaseous capture processes.
In some embodiments, the acid produced is selected from the group consisting of hydrochloric acid, hydrobromic acid, hydroiodic acid, sulfurous acid, sulfuric acid, nitric acid, phosphorous acid, phosphoric acid, hypochlorous acid, chlorous acid, chloric acid, perchloric acid, formic acid, and acetic acid. In some embodiments, the acid produced is HCl. In some embodiments, the base produced is selected from the group consisting of sodium hydroxide, lithium hydroxide, potassium hydroxide, magnesium hydroxide, calcium hydroxide, and sodium acetate.
Although reference is made in
In some embodiments, some or all of the hydrogen gas produced at the cathode in the HER electrolyzer is eventually directed to the gas-diffusion electrode in the HOR fuel cell, where it is oxidized to produce hydrogen ions. In some embodiments, utilizing hydrogen gas at the gas-diffusion electrode from hydrogen generated at the HER cathode, eliminates the need for an external supply of hydrogen; consequently, the utilization of energy by the system is reduced. In some embodiments, the hydrogen may be obtained from the HER cathode and/or may be obtained from an external source, e.g., from a commercial hydrogen gas supplier, e.g., at start-up of the system when the hydrogen supply from the HER cathode is insufficient.
Cation exchange membranes (CEM) are conventionally known in the art and are available from, for example, Asahi Kasei of Tokyo, Japan; or from Membrane International of Glen Rock, N.J., or DuPont, USA. In some embodiments, the polymeric cation-exchange membranes comprise —SO3−, —COO−, —PO32−, —PO3H−, or —C6H4O− cation exchange functional groups. The polymers for the preparation of cation-exchange membranes can be perfluorinated ionomers such as NAFION (a perfluorosulfonic-based membrane), FLEMION, and NEOSEPTA-F, partially fluorinated polymers, non-fluorinated hydrocarbon polymers, non-fluorinated polymers with aromatic backbone, or acid-base blends. It will be appreciated that in some embodiments, depending on the need to restrict or allow migration of a specific cation or an anion species between the electrolytes, a cation exchange membrane that is more restrictive and thus allows migration of one species of cations while restricting the migration of another species of cations may be used as, e.g., a cation exchange membrane that allows migration of potassium ions into the cathode electrolyte while restricting migration of other cations into the cathode electrolyte, may be used. Such restrictive cation exchange membranes are commercially available and can be selected by one ordinarily skilled in the art.
Anion exchange membranes (AEM) are conventionally known in the art. In some embodiments, the polymeric anion-exchange membranes comprise —NH3+, —NRH2+, —NR2H+, —NR3+, or —SR2+ anion exchange functional groups. The polymers for the preparation of anion-exchange membranes can be perfluorinated ionomers such as NAFION (a perfluorosulfonic-based membrane), FLEMION, and NEOSEPTA-F, partially fluorinated polymers, non-fluorinated hydrocarbon polymers, non-fluorinated polymers with aromatic backbone, or acid-base blends. It will be appreciated that in some embodiments, depending on the need to restrict or allow migration of a specific cation or an anion species between the electrolytes, an anion exchange membrane that is more restrictive and thus allows migration of one species of anions while restricting the migration of another species of anions may be used as, e.g., an anion exchange membrane that allows migration of chloride ions into the anode electrolyte while restricting migration of other anions into the anode electrolyte, may be used. Such restrictive anion exchange membranes are commercially available and can be selected by one ordinarily skilled in the art.
In some embodiments, the gas diffusion electrode comprises a conductive substrate infused with a catalyst that is capable of catalyzing the oxidation of hydrogen gas to protons. In some embodiments, the GDE comprises a first side that interfaces with hydrogen gas provided to the GDE, and an opposed second side that interfaces with the anolyte. In some embodiments, the portion of the substrate that interfaces with the hydrogen gas is hydrophobic and is relatively dry; and the portion of the substrate that interfaces with the anolyte is hydrophilic and may be wet, which facilitates migration of protons from the GDE to the anolyte. In various embodiments, the substrate is porous to facilitate the movement of gas from the first side to the catalyst that may be located on second side of the GDE. In some embodiments, the catalyst may also be located within the body of the substrate. The substrate may be selected for its porosity to ion migration, e.g., proton migration, from the GDE to the anolyte. In some embodiments, the catalyst may comprise platinum, ruthenium, iridium, rhodium, manganese, silver or alloys thereof. Suitable gas diffusion electrodes are available commercially, e.g., from E-TEK (USA) and other suppliers.
In some embodiments, a cathode comprises an electrocatalyst selected from platinum, a single-crystal nickel, Raney nickel, platinized nickel, a metal carbide (W2C, Pt—W2C), a platinum group metal alloy (Pt-M, where M=Fe, Mn, Cr, Co, Au), a transition metal, a nickel alloy, sintered nickel, a platinum group metals (Pt, Pd, Ru, Rh), gold, silver, a precious or non-precious chalcogenides, a discrete macrocyclic complex of transition metals, and biological complexes.
Following long-standing patent law convention, the terms “a,” “an,” and “the” refer to “one or more” when used in this application, including the claims. Thus, for example, reference to “a subject” includes a plurality of subjects, unless the context clearly is to the contrary (e.g., a plurality of subjects), and so forth.
Throughout this specification and the claims, the terms “comprise,” “comprises,” and “comprising” are used in a non-exclusive sense, except where the context requires otherwise. Likewise, the term “include” and its grammatical variants are intended to be non-limiting, such that recitation of items in a list is not to the exclusion of other like items that can be substituted or added to the listed items.
For the purposes of this specification and appended claims, unless otherwise indicated, all numbers expressing amounts, sizes, dimensions, proportions, shapes, formulations, parameters, percentages, quantities, characteristics, and other numerical values used in the specification and claims, are to be understood as being modified in all instances by the term “about” even though the term “about” may not expressly appear with the value, amount or range. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are not and need not be exact, but may be approximate and/or larger or smaller as desired, reflecting tolerances, conversion factors, rounding off, measurement error and the like, and other factors known to those of skill in the art depending on the desired properties sought to be obtained by the presently disclosed subject matter. For example, the term “about,” when referring to a value can be meant to encompass variations of, in some embodiments, ±100% in some embodiments ±50%, in some embodiments ±20%, in some embodiments ±10%, in some embodiments ±5%, in some embodiments ±1%, in some embodiments ±0.5%, and in some embodiments ±0.1% from the specified amount, as such variations are appropriate to perform the disclosed methods or employ the disclosed compositions.
Further, the term “about” when used in connection with one or more numbers or numerical ranges, should be understood to refer to all such numbers, including all numbers in a range and modifies that range by extending the boundaries above and below the numerical values set forth. The recitation of numerical ranges by endpoints includes all numbers, e.g., whole integers, including fractions thereof, subsumed within that range (for example, the recitation of 1 to 5 includes 1, 2, 3, 4, and 5, as well as fractions thereof, e.g., 1.5, 2.25, 3.75, 4.1, and the like) and any range within that range.
The present subject matter described herein may be a system, a method, and/or a computer program product. In some embodiments, the computer program product may include a computer readable storage medium (or media) having computer readable program instructions thereon for causing a processor to carry out aspects of the present subject matter.
In some embodiments, the computer readable storage medium can be a tangible device that can retain and store instructions for use by an instruction execution device. The computer readable storage medium may be, for example, but is not limited to, an electronic storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination of the foregoing. A non-exhaustive list of more specific examples of the computer readable storage medium includes the following: a portable computer diskette, a hard disk, a RAM, a ROM, an erasable programmable read-only memory (EPROM or Flash memory), a static random access memory (SRAM), a portable compact disc read-only memory (CD-ROM), a digital versatile disk (DVD), a memory stick, a floppy disk, a mechanically encoded device such as punch-cards or raised structures in a groove having instructions recorded thereon, and any suitable combination of the foregoing. A computer readable storage medium, as used herein, is not to be construed as being transitory signals per se, such as radio waves or other freely propagating electromagnetic waves, electromagnetic waves propagating through a waveguide or other transmission media (e.g., light pulses passing through a fiber-optic cable), or electrical signals transmitted through a wire.
In some embodiments, computer readable program instructions described herein can be downloaded to respective computing/processing devices from a computer readable storage medium or to an external computer or external storage device via a network, for example, the Internet, a local area network, a wide area network and/or a wireless network, or Near Field Communication. The network may comprise copper transmission cables, optical transmission fibers, wireless transmission, routers, firewalls, switches, gateway computers and/or edge servers. A network adapter card or network interface in each computing/processing device receives computer readable program instructions from the network and forwards the computer readable program instructions for storage in a computer readable storage medium within the respective computing/processing device.
In some embodiments, computer readable program instructions for carrying out operations of the present subject matter may be assembler instructions, instruction-set-architecture (ISA) instructions, machine instructions, machine dependent instructions, microcode, firmware instructions, state-setting data, or either source code or object code written in any combination of one or more programming languages, including an object oriented programming language such as Java, Smalltalk, C++, Javascript or the like, and conventional procedural programming languages, such as the “C” programming language or similar programming languages. The computer readable program instructions may execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer may be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection may be made to an external computer (for example, through the Internet using an Internet Service Provider). In some embodiments, electronic circuitry including, for example, programmable logic circuitry, field-programmable gate arrays (FPGA), or programmable logic arrays (PLA) may execute the computer readable program instructions by utilizing state information of the computer readable program instructions to personalize the electronic circuitry, in order to perform aspects of the present subject matter.
In some embodiments, the computer readable program instructions may be provided to a processor of a computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks. In some embodiments, the computer readable program instructions may also be stored in a computer readable storage medium that can direct a computer, a programmable data processing apparatus, and/or other devices to function in a particular manner, such that the computer readable storage medium having instructions stored therein comprises an article of manufacture including instructions which implement aspects of the function/act specified in the flowchart and/or block diagram block or blocks.
In some embodiments, the computer readable program instructions may also be loaded onto a computer, other programmable data processing apparatus, or other device to cause a series of operational steps to be performed on the computer, other programmable apparatus or other device to produce a computer implemented process, such that the instructions which execute on the computer, other programmable apparatus, or other device implement the functions/acts specified in the flowchart and/or block diagram block or blocks.
The following Examples have been included to provide guidance to one of ordinary skill in the art for practicing representative embodiments of the presently disclosed subject matter. In light of the present disclosure and the general level of skill in the art, those of skill can appreciate that the following Examples are intended to be exemplary only and that numerous changes, modifications, and alterations can be employed without departing from the scope of the presently disclosed subject matter. The specific examples that follow are only intended for the purposes of illustration, and are not to be construed as limiting in any manner to make compounds of the disclosure by other methods.
Effect of Different Ion-Exchange Membranes on the Electrochemical System A variety of ion exchange membranes, as well as their combinations, can meet the electrochemical reaction needs of the system. As shown in
Absorbent concentration is an important factor that affects absorption process efficiency of CO2 in the absorption unit. High-concentration caustic soda solution will greatly improve the absorption efficiency and obtain a solution with high total carbon dioxide absorption. Caustic soda solution with a concentration of 0.01 mol/L to 15 mol/L can effectively absorb CO2.
In a system using 1 mol/L caustic soda as an absorbent, each ton of CO2 captured from the air will consume 505 kWh of electricity, including 1333 kWh of electricity consumed by the chlor-alkali electrolysis cell and −828 kWh of electricity compensated by hydrogen-chlorine fuel cells. This power utilization efficiency far exceeds the existing thermochemical process-based capture system.
A representative example of a presently disclosed CO2 capture system is provided in
Referring now to
According to the acid-base reaction equilibria of CO2/HCO3−/CO32−, the maximal concentration of carbon (HCO3−+CO32−) can reach approximately 1.8 M (hits the limit of Na2CO3 solubility limit). It is noted that the maximum microalgae growth rate can be as high as 0.88 day−1 by using 29.7 mM NaHCO3. This value could be readily achieved with longer-time and more efficient air-liquid contact (e.g., using an CO2 absorption reactor shown in
All publications, patent applications, patents, and other references mentioned in the specification are indicative of the level of those skilled in the art to which the presently disclosed subject matter pertains. All publications, patent applications, patents, and other references are herein incorporated by reference to the same extent as if each individual publication, patent application, patent, and other reference was specifically and individually indicated to be incorporated by reference. It will be understood that, although a number of patent applications, patents, and other references are referred to herein, such reference does not constitute an admission that any of these documents form part of the common general knowledge in the art.
Although the foregoing subject matter has been described in some detail by way of illustration and example for purposes of clarity of understanding, it will be understood by those skilled in the art that certain changes and modifications can be practiced within the scope of the appended claims.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2022/076642 | 9/19/2022 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 63245538 | Sep 2021 | US |
