Voltage Swing Method for Carbon Recovery Using Porous Carbon

Abstract

A method and system for carbon recovery by voltage swing are provided. The present invention can include recovering carbon dioxide from a gas mixture by physical adsorption by applying a positive charge to an adsorbent to enhance the selectivity and adsorption of the adsorbent, and releasing carbon dioxide from the adsorbent by removing the positive charge from the adsorbent and applying a desorption method to the adsorbent.

Description

Technical Field

[0001] The present invention generally relates to the field of mitigating global warming, and more particularly to carbon capture.

Background Art

[0002] As the Earth warms, technological advancements are becoming increasingly important in reducing the accumulation of carbon dioxide in the Earth's atmosphere. One promising technical field with the potential to have a significant impact is the field of carbon capture. Carbon capture is the process of capturing carbon dioxide before it enters the atmosphere or removing it from the atmosphere. Carbon dioxide can be recovered and separated from a mixed gas by a variety of different means such as absorption, adsorption, chemical looping, membrane gas separation, and gas hydrates. However, many challenges in the field need to be overcome before carbon capture can have a significant impact on atmospheric carbon dioxide levels.

Summary of the Invention

[0003] According to at least one embodiment, a method and system for carbon capture by a voltage swing method are provided. The present invention may include recovering carbon dioxide from a gas mixture by physical adsorption by applying a charge to an adsorbent to enhance the selectivity and adsorption of the adsorbent, and releasing carbon dioxide from the adsorbent by removing the charge from the adsorbent and applying a desorption method to the adsorbent.

[0004] These and other objects, features, and advantages of the present invention will become apparent from the following detailed description of its exemplary embodiments, read in conjunction with the accompanying drawings. The explanatory drawings are for the purpose of clarifying when those skilled in the art understand the present invention in conjunction with the detailed description, and thus the various features of the drawings are not to scale.

Brief Description of the Drawings

[0005]

Figure 1

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Figure 3A

Figure 3B

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[0006] Although detailed embodiments of the claimed structures and methods are disclosed herein, it is to be understood that the disclosed embodiments are merely illustrative examples of the claimed structures and methods that may be embodied in various forms. However, the present invention can be embodied in many different forms and should not be construed as limited to the exemplary embodiments described herein. In the description, well-known features and techniques may be omitted to avoid unnecessarily obscuring the presented embodiments.

[0007] As mentioned above, technological advancements are becoming increasingly important in mitigating the accumulation of carbon dioxide in the Earth's atmosphere. One promising technical field that can have a significant impact is the field of carbon capture. Carbon capture is the process of recovering carbon dioxide (e.g., present in flue gas from a power plant) before it enters the atmosphere or removing carbon dioxide from the atmosphere. Carbon dioxide can be recovered and separated from a mixed gas by a variety of different means such as absorption, adsorption, chemical looping, membrane gas separation, and gas hydrates. However, many challenges in the field need to be overcome before carbon capture can have a significant impact on atmospheric carbon dioxide levels.

[0008] Adsorption is an important carbon capture technology used in the art. Adsorption is the attachment of atoms, ions, or molecules from a gas, liquid, or dissolved solid to the surface of an adsorbent material made from an adsorbing material called an adsorbent. The adsorbent attaches to atoms, ions, or molecules by non-bonding electrostatic interactions called physical adsorption (in addition to van der Waals interactions) or by chemical bonds called chemisorption. To create an effective adsorbent, the material must have a property known as selectivity, i.e., the ability of the adsorbent to preferentially adsorb one gas over another. Materials with low selectivity lack the ability to separate carbon dioxide to a large extent and are thus not effective for carbon capture. Further, the adsorbent requires a regeneration step to remove carbon dioxide from the adsorbent when the adsorbent is recovered for reuse. One exemplary adsorbent is a metal-organic framework (MOF), which uses physical or chemisorption based on the porous atomic structure of the MOF to capture carbon dioxide. Subsequently, temperature swing adsorption or pressure swing adsorption is used in the regeneration step to remove carbon dioxide from the MOF. However, MOFs are very expensive and, at the time of writing this specification, can cost up to $500 per pound. Another exemplary adsorbent is activated carbon or amorphous carbon. Activated carbon is highly porous and thus one gram of activated carbon can potentially have a surface area greater than 3,000 square meters, resulting in a very high ability to capture carbon dioxide. In addition, activated carbon is inexpensive and, at the time of writing this specification, costs only a few dollars per pound. Activated carbon is also susceptible to chemical modifications such as N-doping or B-doping, oxidation, hydrogenation, metal doping, polymer functionalization, etc. However, unmodified activated carbon has little selectivity, which reduces its suitability for carbon capture applications.

[0009] Another carbon capture technology is absorption, which is the attachment of atoms, ions, or molecules from a gas, liquid, or dissolved solid to a solution made from an absorbent material called a solvent. One absorption method is amine gas treatment, which refers to a group of processes that use aqueous solutions of various alkylamines to remove carbon dioxide from a gas. However, amine gas treatment absorbs carbon dioxide by forming a chemical bond between the solvent and carbon dioxide (chemisorption). Chemisorption, therefore, requires significant energy to break that chemical bond and desorb the carbon dioxide from the adsorbent or solvent, resulting in high energy costs to regenerate the adsorbent or solvent.

[0010] Carbon may also be recovered using membrane gas filters that block the molecules of a particular gas while allowing other gases to pass through using a number of permeable membranes. However, membrane gas filters are limited in performance due to the fact that selectivity must be sacrificed for permeability and vice versa. Therefore, membrane gas filters are not suitable for separating carbon dioxide from flue gas streams. This is because the membrane gas filter must sacrifice an appropriate level of permeability in order to achieve a level of selectivity sufficient to preferentially separate carbon dioxide from other gases. This results in so many gas filters being required to achieve carbon capture that it becomes a limiting factor in the large-scale transport of filters and makes the regeneration of used filters extremely expensive.

[0011] Therefore, it may be advantageous to implement a system that, among other things, electrostatically captures carbon dioxide by physical adsorption, resulting in significantly lower energy costs for adsorbent regeneration compared to those of electrochemical technologies using chemisorption. Further, by using the voltage swing method on activated carbon to enable direct air capture and enhance the selectivity of activated carbon to a level that significantly improves adsorption, it may be advantageous to implement a system that overcomes the main drawbacks of activated carbon and allows the system to benefit from the low cost and high storage capacity inherent in activated carbon. Further, by using the voltage swing method in the regeneration step to reduce the selectivity of activated carbon, it may be advantageous to reduce the energy requirements for releasing the captured carbon dioxide during the regeneration step.

[0012] According to at least one embodiment, the present invention is a method for capturing carbon dioxide from a gas mixture by applying a voltage to an adsorbent to enhance the selectivity and adsorption of the adsorbent, and when the adsorbent becomes saturated under the applied external conditions (such as pressure and temperature), lowering the voltage to reduce the selectivity and adsorption of the adsorbent, facilitating the low-energy release of the captured carbon dioxide molecules during the regeneration step. Although activated carbon is envisioned in embodiments of the present invention, those skilled in the art will understand that any conductive adsorbent may have the same advantages of adsorption and selectivity as activated carbon. However, activated carbon may offer further advantages from the perspective of cost and low environmental impact.

[0013] In some embodiments of the present invention, the gas mixture may be any combination of two or more gases, one of which contains carbon dioxide. The gas mixture may, for example, include flue gas, which may mainly include a combination of nitrogen and carbon dioxide. The gas mixture may also be air, which may be a combination of nitrogen, oxygen, carbon dioxide, etc. In some embodiments of the present invention, the present system can be used in industrial sites, cement manufacturing sites, or chemical sites, or combinations thereof, where carbon dioxide will be released and separated and captured from the air.

[0014] In some embodiments of the present invention, the voltage swing method is a method of changing the properties of activated carbon by applying charge to the activated carbon. As the charge per carbon atom in the porous carbon increases beyond zero, the adsorption loading of carbon dioxide increases dramatically with voltage, from a loading of approximately 5 moles per kilogram at a charge of 0.0 electrons per atom to a loading of over 20 moles per kilogram at a charge of 0.1 electrons per atom. Also, since the adsorption loading is very low at charge densities below zero, there may be cases where it is not necessary to actively remove the adsorbed gas from the porous carbon at such charge densities. Furthermore, the selectivity increases as the charge density increases. Unmodified activated carbon has a selectivity of less than 20, but as the charge density increases to 0.1 electrons per atom, its selectivity increases approximately 50-fold to approximately 1000 (based on the inventors' computer modeling). The high selectivity of the charged activated carbon for adsorbing molecules with large charge quadrupole moments (due to favorable charge-quadrupole interactions) results in more carbon dioxide being adsorbed than nitrogen. By releasing the initially adsorbed gas into a separate chamber with charged amorphous carbon and then subjecting it to a second adsorption and desorption, the selectivity of carbon dioxide over nitrogen can be further enhanced, and the gas adsorbed the second time will have an even higher purity. In the charged activated carbon, the charge may localize at the spike ends or defect sites, and such a non-uniform charge distribution results in a stronger local electric field than a uniform charge, and these stronger fields can facilitate higher carbon dioxide selectivity and adsorption.

[0015] In some embodiments of the present invention, the voltage swing method is a method of changing the properties of an adsorbent by applying charge to the adsorbent, and any conductive adsorbent can exhibit the same adsorption and selectivity advantages as activated carbon.

[0016] In some embodiments of the present invention, the adsorbent is any solid material that adsorbs carbon dioxide by physical adsorption and whose carbon dioxide adsorption increases when charged. In other words, it is any adsorbent in which carbon dioxide binds to the adsorbent by electric force or van der Waals force or both, instead of chemisorption that forms a molecular bond between the adsorbent and carbon dioxide using electrochemical means. The adsorbent can be activated carbon, a specific metal-organic framework (MOF), or any other suitable adsorbent.

[0017] The amount of activated carbon required to remove carbon dioxide from the gas mixture can be expressed as follows, that is, the number of moles of carbon dioxide adsorbed is MCO2 = C (mol / kg of activated carbon) * which can be expressed as m (kg mass of activated carbon). Setting this equal to the number of moles of carbon dioxide in the supply chamber results in the following equation, that is, MCO2 = V (volume of the supply chamber m 3 ) * f (CO2 fraction in the input gas) / 0.0224 (m 3 / mol at SPT). Therefore, the amount of air required to fill the activated carbon with carbon dioxide is V = 0.0224Cm / f.

[0018] In an exemplary embodiment where the above system recovers carbon dioxide from flue gas, f = 0.1, and thus, from our calculations, for C = 20 mol / kg, V = 4.48 m 3 per kg of activated carbon. Since most of the carbon dioxide is in the activated carbon, the remainder is almost pure nitrogen and can be discharged into the air. The activated carbon will be contaminated with nitrogen. For the selectivity S, the ratio of CO2 / N2 in the activated carbon is Sf. When S is approximately 1000 (see above) and f = 0.1, the ratio of CO2 / N2 in the activated carbon is 100, and thus, the CO2 is 99% pure.

[0019] In some embodiments of the present invention, after the system adsorbs carbon dioxide to the adsorbent by any of the carbon recovery methods described herein or any other method, the initially adsorbed residual gas is first released into a separate chamber having charged amorphous carbon, and then, by subjecting it to a second adsorption and release, the selectivity of the adsorbent for carbon dioxide over nitrogen can be further enhanced, and the gas adsorbed the second time will have an even higher purity. For example, when the system recovers carbon from the atmosphere by direct air capture, f = 0.0004, and the amount of air required to contain sufficient carbon dioxide to fill 1 kg of activated carbon is 1120 m 3 3, and the CO2 / N2 ratio in the activated carbon is 4. For reference, 1 kg of activated carbon distributed over 1 square meter of floor will be 0.4 mm thick at its typical density of 2.5 gm / cc. Such a high air volume requires a fan to blow air through the activated carbon so that it is exposed to 1120 m 3 3 of air per kg within the time it takes for the activated carbon to adsorb carbon dioxide. The activated carbon in this case may still be highly contaminated with nitrogen, in which case the system can send the recovered mixture of carbon dioxide and nitrogen to another filtration unit, where the carbon dioxide fraction in the second activated carbon is the carbon dioxide fraction in the first activated carbon multiplied by S, i.e., S 2 f = 400. In that case, the CO2 in the second filtration unit is 99.75% pure.

[0020] The exemplary embodiments described below provide a system, method, and program product for recovering carbon dioxide in a mixed gas by increasing the selectivity of an adsorbent by applying a charge, adhering carbon dioxide to the adsorbent by physical adsorption, and then removing the recovered carbon dioxide by reducing the charge in the adsorbent.

[0021] Referring to FIG. 1, an exemplary voltage swing carbon capture system 100 according to at least one embodiment is shown. Here, the voltage swing carbon capture system 100 includes four chambers. The first chamber 102 includes an inlet 104 for receiving a high-pressure gas mixture, an outlet 106 for discharging nitrogen, and a valve 110 connecting the first chamber 102 to the second chamber 108. The second chamber 108 includes an outlet 112 for discharging carbon dioxide and a first capacitor plate 114. The first capacitor plate 114 may include an adsorbent that can be charged, for example, by a battery. The first capacitor plate 114 may include any conductive adsorbent, such as activated carbon, a metal-organic framework (MOF), zeolite, etc. The third chamber 116 is a mirroring of the first chamber 102. The third chamber 116 includes an inlet 118 for receiving a high-pressure gas mixture, an outlet 120 for discharging nitrogen, and a valve 124 connecting the third chamber 116 to the fourth chamber 122. The fourth chamber 122 includes an outlet 126 for discharging carbon dioxide and a second capacitor plate 128. The second capacitor plate 128 may include an adsorbent that can be charged, for example, by a battery. The first capacitor plate 128 may include any conductive adsorbent. The voltage swing carbon capture system 100 may further include a voltage regulator 130 that is electrically connected to both capacitor plates 114 and 128 and adjusts the charge on them. The capacitor plates 114 and 128 may be part of a single capacitor, or may be connected such that when one holds a negative charge, the other holds a positive charge and vice versa, or both. The voltage regulator 130 may be connected to a power source or an outlet, such as a battery. For example, in some embodiments of the present invention where the voltage swing carbon capture system 100 captures carbon from the atmosphere, the outlet 106 may be for discharging gas residues, which may include a gas mixture from which all or most of the carbon dioxide has been removed by the voltage swing carbon capture process.

[0022] Next, referring to FIG. 2, an operational flowchart showing a voltage swing carbon recovery process 200 according to at least one embodiment is shown. The voltage swing carbon recovery process 200 uses the voltage swing carbon recovery system 100 to alternately exchange charges between two sides 114 and 128 of a capacitor plate. At 202, the voltage swing carbon recovery system 100 positively charges a first capacitor plate disposed within a second chamber and negatively charges a second capacitor plate disposed within a fourth chamber. Here, the voltage swing carbon recovery system 100 can positively charge the first capacitor plate 114 disposed within the second chamber 108 to increase the selectivity and carbon recovery rate of the first capacitor plate 114. At the same time, the voltage swing carbon recovery system 100 can negatively charge or discharge the second capacitor plate 128 disposed within the fourth chamber 122 to release the recovered carbon dioxide from the second capacitor plate 128. The capacitor plates 114, 128 can be adsorbents that can be any conductive solid material that adsorbs carbon dioxide by physical adsorption. In other words, instead of chemisorption that forms a molecular bond between the adsorbent and carbon dioxide using electrochemical means, carbon dioxide binds to the adsorbent by electric force or van der Waals force or both. The adsorbent can be activated carbon, a conductive metal-organic framework (MOF), or any other suitable adsorbent. By positively charging the capacitor plate 114, the voltage swing carbon recovery system 100 enables the capacitor plate 114 to adsorb a high proportion and amount of carbon dioxide from the gas mixture within the second chamber 108 by increasing the selectivity and adsorption of the capacitor plate 114. By negatively charging or grounding the second capacitor plate 128, the voltage swing carbon recovery system 100 makes it easier to remove carbon dioxide molecules from the second capacitor plate 128 by reducing the selectivity and adsorption load of the second capacitor plate 128, thereby regenerating the second capacitor plate 128.

[0023] The voltage swing carbon capture system 100 can use any number or form of desorption method such as temperature swing adsorption or pressure swing adsorption in combination with the voltage swing. Temperature swing adsorption may involve heating the adsorbent to add sufficient thermal energy for the recovered molecules to escape from the surface of the adsorbent, while pressure swing adsorption may involve reducing the pressure around the adsorbent to cause desorption from the adsorbent. For example, the high-pressure gas mixture may be configured to provide a pressure swing regime when the output gas (carbon dioxide, nitrogen, gas residue) is maintained at a pressure below atmospheric pressure, and the voltage swing carbon capture system 100 includes high-pressure adsorption and low-pressure desorption.

[0024] In 204, the voltage swing carbon capture system 100 receives a high-pressure gas containing nitrogen and carbon dioxide into the first chamber 102 and the second chamber 108. Here, the voltage swing carbon capture system 100 closes the outlet 106, opens the inlet 104 and the valve 110 to allow the gas mixture to flow into the first chamber 102 and the second chamber 108, and can recover carbon dioxide from the gas mixture in the first chamber 102 and the second chamber 108. The outlet portions 106 and 112 may remain closed at this time. As a result of the voltage swing carbon capture system 100 flowing the gas mixture from the first chamber 102 to the second chamber 108 through the valve 110, the gas mixture is exposed to the positively charged first capacitor plate 114. Immediately, as the constituent molecules of the gas mixture move uniformly around both the first chamber 102 and the second chamber 108 by molecular diffusion, the positively charged first capacitor plate 114 can begin to adsorb carbon dioxide from the gas mixture in the chambers 102 and 108. The gas mixture may be flue gas which can be a combination of nitrogen and carbon dioxide. The gas mixture may also be air which can be a combination of nitrogen, oxygen, carbon dioxide, etc. The gas mixture can be pressurized to facilitate its movement into the voltage swing carbon capture system 100, and the voltage swing carbon capture system 100 can lower the pressure in the first chamber 102 or the second chamber 108 or both to further facilitate the movement of the gas mixture. The voltage swing carbon capture system 100 can maintain a positive charge on the first capacitor plate 114 while receiving the high-pressure gas mixture so as to adsorb as much carbon dioxide as possible from the gas mixture. In some embodiments of the present invention, when the first capacitor plate 114 reaches the threshold saturation of carbon dioxide, the voltage swing carbon capture system 100 closes the valve 110 to separate the first chamber 102 and the second chamber 108 from each other, thereby confining nitrogen in the first chamber 102 and ensuring that carbon dioxide is confined and separated in the second chamber 108 when it desorbs from the first capacitor plate 114.And the voltage swing carbon capture system 100 can further close the inlet 104 to stop the input of any further gas mixture.

[0025] In 206, the voltage swing carbon capture system 100 discharges the released carbon dioxide from the fourth chamber 122 and discharges nitrogen from the third chamber 116. Here, the previously captured carbon dioxide has desorbed from the second capacitor plate 128 as a result of using negative charging or grounding and yet another desorption method. Thus, the fourth chamber 122 can be filled with substantially pure carbon dioxide. This carbon dioxide can be released from the system, for example, by opening the outlet 126. When the carbon dioxide is released into a certain storage container, it can be stored for isolation or industrial use, etc. The voltage swing carbon capture system 100 can maintain a negative or neutral charge on the second capacitor plate 128 while continuing the discharge of carbon dioxide so as to hardly re-adsorb the desorbed carbon dioxide as much as possible. The voltage swing carbon capture system 100 can discharge nitrogen from the third chamber 116 by opening the outlet 120. The nitrogen in the third chamber 116 can be a gas mixture from which all or most of the carbon dioxide has been removed by the positively charged second capacitor plate 128. Nitrogen may alternatively refer herein to the remaining nitrogen-rich gas residue remaining after removing carbon dioxide from the gas mixture, which may be released into the atmosphere or recovered and stored. When the carbon dioxide is discharged from the fourth chamber 122 and the nitrogen is discharged from the third chamber 116, as determined through a sensor, for example, or as estimated after a predetermined time, the voltage swing carbon capture system 100 can close the outlets 126 and 120.

[0026] In 208, the voltage swing carbon capture system 100 negatively charges the first capacitor plate 114 and positively charges the second capacitor plate 128. Here, the voltage swing carbon capture system 100 can switch the polarity of the voltage regulator 130 so as to negatively charge or ground the first capacitor plate 114 to release the captured carbon dioxide, and to positively charge the second capacitor plate 128 disposed in the fourth chamber 122 to capture carbon dioxide. Here, by negatively charging or grounding the first capacitor plate 114, the voltage swing carbon capture system 100 reduces the energy required to regenerate the first capacitor plate 114 by reducing the energy required to remove carbon dioxide molecules from the first capacitor plate 114 by reducing the selectivity and adsorption of the first capacitor plate 114. By positively charging the second capacitor plate 128, the voltage swing carbon capture system 100 enables the second capacitor plate 128 to adsorb a high percentage and amount of carbon dioxide when exposed to the gas mixture by increasing the selectivity and adsorption of the second capacitor plate 128.

[0027] The voltage swing carbon capture system 100 can use any number or form of desorption method such as temperature swing or pressure swing in combination with negative charging or grounding. Temperature swing adsorption may include heating the adsorbent to add sufficient thermal energy for the recovered molecules to escape from the surface of the adsorbent, while pressure swing adsorption may include reducing the pressure around the adsorbent to cause desorption from the adsorbent.

[0028] In 210, the voltage swing carbon capture system 100 discharges the released carbon dioxide from the second chamber 108 and discharges nitrogen from the first chamber 102. Here, the previously captured carbon dioxide has desorbed from the first capacitor plate 114 as a result of a negative charge or zero charge and any other desorption means. Thus, the second chamber 108 can be filled with substantially pure carbon dioxide. The voltage swing carbon capture system 100 can release this carbon dioxide from the third chamber 116 by opening the outlet 112, after which the carbon dioxide can be stored for isolation or industrial use, etc. On the other hand, with most of the carbon dioxide adsorbed, the voltage swing carbon capture system 100 can open the outlet 106 and discharge the nitrogen, which was the residue after the carbon dioxide was adsorbed onto the first capacitor plate 114, from the first chamber 102. When the carbon dioxide is discharged from the second chamber 108 and the nitrogen is discharged from the first chamber 102, as determined through a sensor, for example, or estimated after a predetermined time, the voltage swing carbon capture system 100 can close the outlets 106 and 112.

[0029] In 212, a voltage swing carbon capture system 100 receives a high-pressure gas containing nitrogen and carbon dioxide into a third chamber 116. Here, the second chamber 108 and the fourth chamber 122 are both empty of carbon dioxide, with the second chamber 108 emptied by release and the fourth chamber 122 emptied by adsorption. The voltage swing carbon capture system 100 opens an inlet 118 and a valve 124 to allow the gas mixture to flow into the third chamber 116 and then through the valve 124 into the fourth chamber 122, such that the gas mixture is exposed to a second capacitor plate 128. The gas mixture can be pressurized to facilitate its movement into the voltage swing carbon capture system 100, and the voltage swing carbon capture system 100 can reduce the pressure within the third chamber 116 or the fourth chamber 122 or both to further facilitate the movement of the gas mixture. The voltage swing carbon capture system 100 can maintain a positive charge at the second capacitor plate 128 while receiving the high-pressure gas mixture so as to adsorb as much carbon dioxide as possible from the gas mixture. In some embodiments of the present invention, when the second capacitor plate 128 reaches a threshold saturation of carbon dioxide, the voltage swing carbon capture system 100 closes the valve 124 to separate the fourth chamber 122 and the third chamber 116 from each other, thereby confining nitrogen within the third chamber 116 and ensuring that carbon dioxide is confined within and separated within the fourth chamber 122 as it desorbs from the second capacitor plate 128. Then, the voltage swing carbon capture system 100 can further close the inlet 118 to stop the introduction of any further gas mixture.

[0030] At 214, the voltage swing carbon capture system 100 determines whether the carbon capture cycle has ended. In some embodiments of the present invention, as long as a carbon dioxide gas mixture is provided, i.e., potentially as long as a power plant is burning fuel or an industrial site is generating a gas mixture, the voltage swing carbon capture system 100 can operate periodically. Thus, the voltage swing carbon capture system 100 can operate continuously until it receives an end command. The voltage swing carbon capture system 100 can receive an end command from an authorized user, where the authorized user can be a user authenticated in one or a combination of ways. The end command can be a digital transmission received by the voltage swing carbon capture system 100 through a network, a specific input entered into a user interface device incorporated into the voltage swing carbon capture system 100, or both. According to one embodiment, if the voltage swing carbon capture system 100 determines that the carbon capture cycle has not received an end command and thus has not ended (branch "no" in step 214), it can proceed to step 202 of positively charging the first capacitor plate 114 disposed within the second chamber 108 and negatively charging the second capacitor plate 128 disposed within the fourth chamber 122. If the voltage swing carbon capture system 100 determines that the voltage swing carbon capture system 100 has received an end command from an authorized user, and as a result the carbon capture cycle has ended (branch "yes" in step 214), it can terminate the voltage swing carbon capture process 200.

[0031] Next, referring to FIG. 3A, an exemplary voltage swing carbon capture system 300 according to at least one embodiment is shown. Here, the voltage swing carbon capture system 300 includes a first chamber 302 having two chambers, namely, an inlet 304 for a gas mixture that can be air or flue gas and an outlet 306 for discharging residual gas, and a second chamber 308 including an outlet 310 for the regenerated gas. A porous carbon adsorbent 312 is disposed within the first chamber. The porous carbon adsorbent 312 can be an adsorbent made of activated carbon, and it can also be disposed within a conductive container 314 that can slide between the first chamber 302 and the second chamber 308. The voltage swing carbon capture system 300 can be electrically connected to a voltage source 316 and ground 318.

[0032] Next, referring to FIG. 3B, an exemplary voltage swing carbon capture system 300 according to at least one embodiment is shown. FIG. 3B represents the voltage swing carbon capture system 300 in a state during the voltage swing carbon capture process, where the porous carbon adsorbent 312 has been transferred from the first chamber 302 to the second chamber 308.

[0033] Next, referring to FIG. 4, an operational flowchart showing a voltage swing carbon capture process 400 according to at least one embodiment is shown. The voltage swing carbon capture process 400 moves carbon dioxide from the first chamber 302 to the second chamber 308 by moving a porous carbon adsorbent 312 between two chambers 302, 308. At 402, the voltage swing carbon capture system 300 charges the porous carbon adsorbent 312 disposed within the first chamber 302. Here, the voltage swing carbon capture system 300 can apply a uniform positive charge to the porous carbon adsorbent 312 via a voltage source 316. According to the inventors' computer modeling, the voltage swing carbon capture system 300 can increase adsorption to approximately 20 mol / kg by charging the porous carbon adsorbent 312 to, for example, 0.1 electron charges per atom. Since 20 mol / kg is close to the saturation value, increasing the charge further may not necessarily result in recovering more carbon dioxide. However, since the charge at saturation may vary for different activated carbon structures, deviations from this value can be envisioned as long as they do not depart from the scope of the present invention.

[0034] At 404, the voltage swing carbon capture system 300 receives a gas mixture into the first chamber 302. The gas mixture can be flue gas or air. Here, the voltage swing carbon capture system 300 opens an inlet 304 to receive the gas mixture, and the gas mixture can be pressurized to facilitate the gas mixture moving through the voltage swing carbon capture system 300. This gas mixture then contacts the charged porous carbon adsorbent 312, and the porous carbon adsorbent 312 can adsorb carbon dioxide from the gas mixture. At this stage, the outlet 306 can be assumed to be closed.

[0035] At 406, the voltage swing carbon capture system 300 moves the charged porous carbon adsorbent 312 to the second chamber 308. The charged porous carbon adsorbent 312 can be housed within a conductive container 314, and the conductive container 314 can slide from the first chamber 302 to the second chamber 308 using pneumatic means, motor-driven means, or any other means. When the charged porous carbon adsorbent 312 becomes saturated with carbon dioxide, the charged porous carbon adsorbent 312 can be moved, and this carbon dioxide may be conclusively detected by a sensor or approximated at equal intervals for each cycle depending on the input rate of the input gas mixture and the adsorption rate of the charged porous carbon adsorbent 312. Thereby, the voltage swing carbon capture system 300 can reciprocate the recovered carbon dioxide from the first chamber 302 and leave a gas residue that contains the original gas mixture but no carbon dioxide.

[0036] At 408, the voltage swing carbon capture system 300 regenerates the gas within the second chamber 308 by discharging the voltage from the porous carbon adsorbent 312. Here, the porous carbon adsorbent 312 is saturated with carbon dioxide from the first chamber 302. The voltage swing carbon capture system 300 discharges the porous carbon adsorbent 312 such that the charge of the porous carbon adsorbent 312 decreases to zero, then reduces the selectivity and adsorption of the porous carbon adsorbent 312, lowers the energy cost of releasing the recovered carbon dioxide from the surface of the porous carbon adsorbent 312, and reduces the effect and ratio by which the porous carbon adsorbent 312 can re-adsorb carbon dioxide that has previously been released from the porous carbon adsorbent 312. The voltage swing carbon capture system 300 can remove the recovered carbon dioxide from the surface of the porous carbon adsorbent 312 by using any number or combination of desorption techniques such as pressure swing adsorption and temperature swing adsorption. The voltage swing carbon capture system 300 can fill the second chamber 308 with free carbon dioxide gas by desorbing / regenerating the porous carbon adsorbent 312.

[0037] At 410, the voltage swing carbon capture system 300 discharges the residual gas from the first chamber 302 by reducing the pressure within the first chamber 302. Here, the first chamber 302 can contain the residual gas, which can be the remainder of the original gas mixture when the porous carbon adsorbent 312 adsorbs and removes carbon dioxide from the gas mixture. The voltage swing carbon capture system 300 can discharge this residual gas, for example, by opening the outlet 306. The residual gas may be discharged directly into the atmosphere or recovered for isolation or other purposes. The voltage swing carbon capture system 300 can discharge the residual gas by reducing the pressure outside the outlet 306 so that the gas escapes.

[0038] At 412, the voltage swing carbon capture system 300 moves the porous carbon adsorbent 312 into the first chamber 302. Here, the voltage swing carbon capture system 300 moves the discharged and newly regenerated porous carbon adsorbent 312 from the second chamber 308 into the first chamber 302, where it is recharged and begins to adsorb additional carbon dioxide from the gas mixture.

[0039] At 414, the voltage swing carbon capture system 300 discharges carbon dioxide from the second chamber 308 by reducing the pressure outside the outlet 310. Here, the voltage swing carbon capture system 300 opens the outlet 310 to release the contents of the chamber 308, which can be the carbon dioxide desorbed from the porous carbon adsorbent 312 during the regeneration process. This carbon dioxide may be isolated or used for industrial applications.

[0040] At 416, the voltage swing carbon capture system 300 determines whether the efficiency of the porous carbon adsorbent 312 has dropped below a threshold value. The threshold value can represent the efficiency of the porous carbon adsorbent 312 in separating carbon dioxide from the gas mixture and can be measured by measuring the proportion of carbon dioxide remaining in the gas residue discharged from the outlet 306. According to one embodiment, if the voltage swing carbon capture system 300 determines that the efficiency of the porous carbon adsorbent 312 has not dropped below the threshold value (branch of "No" in step 416), the voltage swing carbon capture system 300 can proceed to step 402 of charging the porous carbon adsorbent 312 disposed in the first chamber. If the voltage swing carbon capture system 300 determines that the efficiency of the porous carbon adsorbent 312 has dropped below the threshold value (branch of "Yes" in step 416), the voltage swing carbon capture system 300 can terminate the voltage swing carbon capture process 400. In some embodiments of the present invention, the voltage swing carbon capture system 300 may alternatively or additionally determine whether the carbon dioxide capture cycle has ended by determining whether the voltage swing carbon capture system 300 has received an end command from a user who has been permitted to issue such a command.

[0041] Figures 1-4 merely present examples of individual embodiments and do not imply any limitation regarding how various embodiments can be implemented. Many modifications to the illustrated environment may be made based on design and implementation requirements. For example, in at least one embodiment of the present invention, only one side of the voltage swing carbon capture system 100 having chambers 102 and 108, inlet 104, valve 110, and outlets 106 and 112 may be used. The capacitor plate 114 can alternately exchange charges between positive and negative or zero charges, along with carbon dioxide adsorption during the positive charge stage and carbon dioxide desorption during the negative or zero charge stage. During the positive charge stage, the inlet 104 and valve 110 are opened while the outlets 106 and 112 are closed to receive a high-pressure gas containing nitrogen and carbon dioxide. On the other hand, during the negative or zero charge stage, the inlet 104 and valve 110 are closed while the outlets 106 and 112 are opened to release the separated gas.

[0042] Descriptions of various embodiments of the present invention have been presented for purposes of illustration, but are not intended to be exhaustive or limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope of the described embodiments. The terms used herein are selected to best explain the principles of the embodiments, practical applications, or technological improvements over technologies found in the market, or to enable other skilled artisans to understand the embodiments disclosed herein.

Claims

1. A method for carbon recovery, comprising: recovering carbon dioxide from a gas mixture by applying a positive charge to an adsorbent to enhance the selectivity and adsorption of the adsorbent; releasing the carbon dioxide from the adsorbent by removing the positive charge from the adsorbent and applying a desorption method to the adsorbent. A method comprising the above steps.

2. The method according to claim 1, wherein the adsorbent comprises activated carbon, a conductive metal-organic framework (MOF), or a conductive zeolite.

3. The method according to claim 1, wherein the adsorbent recovers carbon dioxide from the gas mixture by physical adsorption.

4. The method according to claim 1, wherein the desorption method comprises pressure swing and temperature swing.

5. The method according to claim 1, wherein the gas mixture is flue gas or air.

6. The method according to claim 1, wherein the recovery is responsive to a determination that the efficiency of the adsorbent has not dropped below a threshold value.

7. The method according to claim 1, wherein the adsorbent comprises activated carbon and the positive charge comprises a charge density of 0.1 electrons per atom in the adsorbent.

8. A method for carbon recovery, comprising: charging a capacitor including two plates having opposite charges such that when a first one of the two plates is negatively charged, a second one of the two plates is positively charged and when the first one of the two plates is positively charged, the second one of the two plates is negatively charged; recovering carbon dioxide from a gas mixture using the positively charged side of the capacitor; desorbing previously recovered carbon dioxide using the negatively charged side of the capacitor and one or more desorption methods; alternately switching the charges of the two capacitor plates at equal intervals. A method comprising the above steps.

9. The method according to claim 8, wherein the adsorbent comprises activated carbon, a conductive metal-organic framework (MOF), or a conductive zeolite.

10. The method according to claim 8, wherein the adsorbent recovers carbon dioxide from the gas mixture by physical adsorption.

11. The method according to claim 8, wherein the desorption method comprises pressure swing and temperature swing.

12. The method according to claim 8, wherein the gas mixture is flue gas or air.

13. The method according to claim 8, wherein the recovering is responsive to a determination that the efficiency of the adsorbent has not dropped below a threshold value.

14. The method according to claim 8, wherein the adsorbent includes activated carbon, and the positive charge includes a charge density of 0.1 electrons per atom of the adsorbent.

15. A method for carbon recovery, comprising: recovering carbon dioxide from a gas mixture to produce a residual gas by applying a positive charge to an adsorbent disposed in a first chamber to enhance the selectivity and adsorption of the adsorbent; moving the charged adsorbent to a second chamber; discharging the charged adsorbent; desorbing the recovered carbon dioxide from the discharged adsorbent into the second chamber; discharging the residual gas from the first chamber; moving the discharged adsorbent to the first chamber; and discharging the desorbed carbon dioxide from the second chamber.

16. The method according to claim 15, wherein the adsorbent includes activated carbon, a conductive metal-organic framework (MOF), or a conductive zeolite.

17. The method according to claim 15, wherein the adsorbent recovers carbon dioxide from the gas mixture by physical adsorption.

18. The method according to claim 15, wherein the desorption method includes pressure swing and temperature swing.

19. The method according to claim 15, wherein the gas mixture is flue gas or air.

20. The method according to claim 15, wherein the recovering is responsive to a determination that the efficiency of the adsorbent has not dropped below a threshold value.

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