Sorbent lifetime improvement

Abstract

Described is a process for capturing carbon dioxide (CO2) using solid-sorbents coupled with a downstream CO2 upgrading process, where the CO2 capture process is regenerated with a sweep gas and the resulting mixture of sweep gas and desorbed gases is fed to the downstream CO­2 upgrading process, with optional adjustments to composition, pressure, and temperature. The use of a sweep gas for desorption prevents or slows sorbent degradation mechanisms, such as oxidation, thermal degradation, and water-mediated structural degradation, resulting in the extension of sorbent lifetime. Described is a multi-unit process where CO2 is captured and upgraded in one or several of the upgrading pathways described above. Additionally, a sweep gas is employed as a sweep and / or desorption gas in the CO2 capture process to recover the adsorbate (primarily CO2) while reducing or preventing oxidative degradation of the capture sorbents.

Description

SORBENT LIFETIME IMPROVEMENTFIELD OF THE INVENTION

[0001] The present disclosure relates to a carbon dioxide (CO2) capture and utilization process, in particular a CO2 capture and utilization process with improved sorbent lifetime and CO2 upgrading process integration options enabled by use of a sweep gas stream for sorbent regeneration.BACKGROUND

[0002] Solid-sorbent-based adsorption processes are one class of CO2 capture technology for applications including but not limited to post-combustion flue gas, ambient air (e.g., direct air capture (DAC)), compressed air, building air, fermentation gas, biogas, calcination gas, synthesis gas, hydrocarbon-derived hydrogen, and mixtures thereof. Such adsorption processes are regenerated by switching from an adsorption mode to a desorption mode (or step) to recover the adsorbate as product and ready the sorbent for reuse. Some adsorption processes may have many intermediate process steps, such as preheating, blowdown, purge, re-pressurization, heating, and cooling steps, or combinations thereof. The sum of these intermediate process steps and the associated adsorption and desorption steps is generally referred to as the adsorption step of an adsorption process. These intermediate process steps may employ sweep gases, process gases, vacuum, or other atmospheres to achieve the desired changes in the sorbent and its environment, often operated transiently according to a series of steps with control points determined programmatically with specific durations or triggered upon reaching conditional operating condition setpoints. Generally, adsorption processes are classified by the changes in operating conditions necessary to desorb the adsorbate, e.g., pressure-swing, vacuum-swing, temperature-swing, temperature-vacuum-swing, and moisture-swing adsorption processes.

[0003] Sorbent lifetime, or the duration for which a sorbent has useful separation performance characteristics, is an important parameter in the technoeconomic analysis of CO2 adsorption processes. All things being equal, as sorbent lifetime increases, sorbent replacement rate decreases, and the economics of a process improves. However, solid-supported amine sorbents (hereafter referred to as amine sorbents) have been demonstrated to degrade under typical temperature-swing adsorption (TSA) and temperature-vacuum-swing adsorption (TVSA) conditions. Guta, et al., (ACS Appl. Mater. Interfaces, 2023, 15, 46790-46802),teaches that the majority of PEI degradation under process-relevant conditions is caused by radical -mediated oxidation reactions, which result in the cleavage of carbon-nitrogen bonds and the loss of active amine adsorption sites. The presence of molecular oxygen, as well as other species that also may be present in the ambient air or flue gases, such as ozone, hydroperoxyl radical, and hydroxyl radical, has been shown to cause the degradation of polymers through the creation and propagation of peroxyl and hydroperoxide species. As with most chemical reactions, the rates of these oxidation reactions are accelerated with increasing temperature. Therefore, the desorption steps of TSA and TVS A processes are likely to accelerate oxidation if the sorbent is still exposed to an oxidizing environment.

[0004] Other CO2 sorbent classes, such as zeolites, silicas, and metal-organic frameworks, may be degraded by exposure to water, especially hot water vapor (steam). The degradation mechanisms for these materials may differ, but they all may degrade via structural changes that lead to loss of active adsorption sites, surface area, and / or pore volume.

[0005] A common practice for TSA and TVSA processes is to sweep the sorbent, which is located in some type of sorbent contactor of unspecified dimensions, form, or factors, with a gas, either the adsorbate itself or a gas that is easily separated from the adsorbate. If heated, this sweep gas, or a different gas, can provide the heat necessary for desorption, hereafter referred to as a desorption gas. Steam is the most commonly envisioned desorption gas for CO2 capture applications because it is commonly produced in industrial plants and it is easily separated from CO2 (via condensation).SUMMARY OF THE INVENTION

[0006] Described is a process for capturing carbon dioxide (CO2) using solid-sorbents coupled with a downstream CO2 upgrading process, where the CO2 capture process is regenerated with a sweep gas and the resulting mixture of sweep gas and desorbed gases is fed to the downstream CO2 upgrading process, with optional adjustments to composition, pressure, and temperature. The use of a sweep gas for desorption prevents or slows sorbent degradation mechanisms, such as oxidation, thermal degradation, and water-mediated structural degradation, resulting in the extension of sorbent lifetime. Described is a multi-unit process where CO2 is captured and upgraded in one or several of the upgrading pathways described above. Additionally, a sweep gas is employed as a sweep and / or desorption gas in the CO2 capture process to recover the adsorbate (primarily CO2) while reducing or preventing degradation of the capture sorbents.

[0007] To that end, a process for capturing carbon dioxide (CO2) includes providing a solid-sorbent having CO2 as an adsorbate. The process further includes providing a sweep gas during the adsorption step. The process further includes desorbing CO2 from the solid-sorbent. The process further includes flowing the sweep gas over the solid-sorbent to produce resulting gas. The sweep gas slows at least a sorbent degradation mechanism.BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

[0008] The accompanying drawings are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention, and together with the description serve to explain the principles of the invention.

[0009] Figure 1 shows a block flow diagram of an embodiment of the instant invention.

[0010] Figure 2 shows a block flow diagram of an embodiment of the instant invention where a Gas Conditioning Step has been inserted between the CO2 Capture Contactor and the CO2 Upgrading Process.

[0011] Figure 3 shows a block flow diagram of a hydrogen enrichment embodiment of the instant invention where the Gas Conditioning Step is optional and an H2 Source is added for H2 enrichment into the CO2 Upgrading Process.

[0012] Figure 4 shows a block flow diagram of a hydrogen depletion embodiment of the instant invention where the Gas Conditioning Step is optional and an H2 Removal Process is inserted upstream of the CO2 Upgrading Process to deplete the H2 concentration.

[0013] Figure 5 shows a block flow diagram of a hydrogen depletion with recycling embodiment of the instant invention where the Gas Conditioning Step is optional and an H2 Removal Process is inserted upstream of the CO2 Upgrading Process to deplete the H2 concentration. The H2 Enriched Recycle Gas from the H2 Removal Process is recycled back to the CO2 Capture Contactor.

[0014] Figure 6 shows an embodiment of the instant invention in BFD form where the Gas Conditioning Step, H2 Removal Process, H2 Source and all recycle streams are optional.

[0015] Figure 7 is a flow chart illustrating a process for capturing carbon dioxide, in accordance with some embodiments.

[0016] Like reference numerals refer to corresponding parts throughout the drawings.DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

[0017] The instant invention comprises a process for capturing carbon dioxide (CO2) using solid-sorbents coupled with a downstream CO2 upgrading process, where the CO2 capture process progresses through an adsorption step utilizing a sweep gas during a desorption step or an intermediate process step. A fraction of the mixture of gases produced from the adsorption process during these steps (primarily comprising the sweep gas and desorbed gases) may be recycled internally, but the remainder fraction is fed to the downstream CO2 upgrading process, with optional adjustments to composition, pressure, and temperature. The use of a sweep gas prevents or slows sorbent degradation mechanisms, such as oxidation, thermal degradation, and water-mediated structural degradation, resulting in the extension of sorbent lifetime.

[0018] The instant invention comprises a multi-unit process where CO2 is captured and upgraded in one or several of the upgrading pathways described herein. Additionally, a sweep gas is employed as a sweep and / or desorption gas in the CO2 capture process to recover the adsorbate (primarily CO2) while reducing or preventing oxidative degradation of the capture sorbents.

[0019] The sweep gas may be a reducing gas that reacts with oxidizing agents in the gas phase or adsorbed phase, or with oxidized sites in the sorbent structure itself during a desorption step or an intermediate process step of the adsorption process, effectively terminating radical- mediated oxidation reactions before or shortly after they begin to propagate. Similarly, the sweep gas may assist in removing the presence of water molecules from proximity to the sorbent structure, either in the gas phase or the adsorbed phase, preventing or at least reducing the degree of water-mediated sorbent degradation.

[0020] There are several benefits to the instant invention. The lifetime of the CO2 sorbents will be increased, improving the economics of the capture process via the reduction of sorbent replacement costs, process downtime, and labor. The use of a sweep gas during the adsorption cycle may eliminate the need for steam generation equipment and its associated operating expenses if the sweep gas is used as the desorption gas, and some downstream CO2 upgrading process steps may produce or be run with excess sweep gases (e.g. molecular hydrogen, water vapor, light hydrocarbon paraffin gases (methane, ethane, propane, butane, pentane), alcohols (methanol, ethanol, propanol, butanol), carbon monoxide, carbon dioxide, sulfur dioxide, hydrazine, ammonia, formic acid, trace gases, and mixtures thereof.) There are multiplepotential embodiments of using a sweep gas at some point during the adsorption cycle. A resulting gas is produced when the sweep gas is flowed over the sorbent, and the composition of this resulting gas will vary depending on the step of the adsorption cycle that the sweep gas is introduced. Some examples include: 1. A sweep gas is flowed over the sorbent during the desorption step of the adsorption cycle, producing a resulting gas that is a mixture of the sweep gas, any residual gases in the sorbent contactor, and any gases that desorb from the sorbent., 2. A sweep gas is flowed over the sorbent during any intermediate process step after the adsorption step and before the desorption step, producing a resulting gas that is a mixture of the sweep gas and any residual gases in the sorbent contactor., 3. A sweep gas is flowed over the sorbent during any intermediate process step after the desorption step and before the adsorption step, producing a resulting gas that is a mixture of the sweep gas and any residual gases in the sorbent contactor.

[0021] The solid-sorbent lifetime can be characterized by one or more of the following factors, including but not limited to, equilibrium adsorption capacity of the desired adsorbate, working capacity of the desired adsorbate, structural integrity of the sorbent, heat transfer properties of the sorbent, and mass transfer properties of the sorbent. A reduction in the degradation rate of the selected characterization factor with respect to the absence of the use of a sweep gas during the adsorption cycle is considered to be an improvement of sorbent lifetime. The degradation rate may be reduced by as much as 25% or more, 50% or more, 75% or more or even 100% with respect to the degradation rates in absence of the use of a sweep gas during the adsorption cycle.

[0022] A preferred sweep gas comprises primarily molecular hydrogen with trace components. A sweep gas may consist essentially of molecular hydrogen having a concentration of at least 80% and preferably at least 90% as determined by partial pressure. Another preferred sweep gas mixture comprises any stoichiometric mixture of molecular hydrogen and carbon monoxide with trace component, commonly referred to as synthesis gas or syngas. This sweep gas from the downstream CO2 upgrading process could be used as a sweep gas for the upstream CO2 capture process, thereby recycling those gases into the CO2 upgrading process. Such recycling activities utilize streams for higher economic benefits than the alternative, which in most cases is combustion of the excess gases as fuel gas for process heat.

[0023] There are also many possible classes of sorbents that could be used in the CO2 adsorption processes. One of the most-commonly reported class of CO2 sorbent is solid-supported amines. There are many possible structural permutations of solid-supported amines, wherein the amines are selected from a class of amine-containing organic structures, comprising amine-containing polymers and oligomers, aminoalkyl groups, aminophenyl groups, and amine-containing small molecules. Known amines types include but are not limited to branched polyethyleneimine (PEI), linear PEI, polypropyleneimine, ethyleneamine oligomers, such as diethylenetriamine (DETA), triethylenetetramine (TETA), tetraethylenepentamine (TEPA), pentaethylenehexamine (PEHA), and hexaethyleneheptamine (HEHA). A preferred example solid-supported amine sorbent is PEI supported on porous silica or alumina. The branched form of PEI has a mixture of primary, secondary, and tertiary alkyl amines, while the linear form of PEI is mostly secondary alkylamines with primary alkyl amine chain terminations.

[0024] The solid structure for the sorbents is selected from a group of structures comprising metal-organic frameworks, carbons, solid-supported amines, fiber sorbents, polymeric sorbents, metal carbonates, metal silicates, metal oxides, aluminosilicates, silicoaluminophosphates, carbons, and their structural hybrids and physical mixtures. Specifically for solid-supported amines the support is selected from a class of solids materials that comprising alumina, silica, ceria, titania, aluminosilicates, silicoaluminophosphates, porous polymers, porous organic fibers, resins, and metal-organic frameworks. A preferred solid support is porous alumina. Another preferred solid support are metal-organic frameworks.

[0025] A CO2 capture process, whether point source or DAC, could be employed in a CO2 utilization scheme where the captured CO2 is sent to downstream upgrading processes, including but not limited to water-gas-shift (WGS), reverse-water-gas-shift (RWGS), methanation, electrolysis, and direct hydrogenation. Additional upgrading steps, including but not limited to methanol -to-olefins, methanol -to-gasoline, methanol -to-jet, Fischer-Tropsch, and dehydration / oligomerization, may be added further downstream to produce various hydrocarbon products. This use case for captured CO2 will hereafter be referred to as CO2 upgrading. Importantly, two necessary components of the feed to CO2 upgrading processes are CO2 and molecular hydrogen (H2), though different process configurations may be designed for different stoichiometric ratios.

[0026] The term sorbent is used interchangeably with solid-sorbents herein.

[0027] As used herein, the terms "comprises," "comprising," "includes," "including,""has," "having" or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a process, method, article, or apparatus that comprises a list of elements is notnecessarily limited to only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Also, use of "a" or "an" are employed to describe elements and components described herein. This is done merely for convenience and to give a general sense of the scope of the invention. This description should be read to include one or at least one and the singular also includes the plural unless it is obvious that it is meant otherwise.

[0028] Certain exemplary embodiments of the present invention are described herein and are illustrated in the accompanying figures. The embodiments described are only for purposes of illustrating the present invention and should not be interpreted as limiting the scope of the invention. Other embodiments of the invention, and certain modifications, combinations, and improvements of the described embodiments, will occur to those skilled in the art and all such alternate embodiments, combinations, modifications, improvements are within the scope of the present invention.

[0029] Figure 1 shows a simple embodiment of the instant invention in block flow diagram (BFD) form. Sweep gas 103 (the nature of which is described elsewhere in this document) is sent from a sweep gas source 102 to the CO2 Capture Contactor 104 (e.g., a gas / solid contactor), which contains the sorbent (e.g., a solid chemisorbent), while the CO2 Capture Contactor 104 is not in adsorption mode. The effluent from the CO2 Capture Contactor 104, a mixture or sequential effluent of Sweep gas and Desorbed Gas 105 is sent to a downstream CO2 Upgrading Process 106. Various options for CO2 upgrading processes are described elsewhere in this document. In some embodiments, during an adsorption step, the CO2 capture contactor 104 adsorbs CO2 from a feed, which may be air (e.g., atmospheric air rather than receiving feed directly from exhaust of a CO2 producing industrial process). In some embodiments, the feed is a low CO2 feed (e.g., less than 10000 ppm or 1% CO2, or less than 5000 ppm or 0.5% CO2, or less than 1000 ppm or 0.1 % CO2)

[0030] Figure 2 shows an embodiment of the instant invention in BFD form where a Gas Conditioning Step 108 has been inserted between the CO2 Capture Contactor 104 and the CO2 Upgrading Process 106. This Gas Conditioning Step 108 could comprise a single step or multiple conditioning steps in series to suitably adjust the stream properties (e.g., adjust of the stream temperature and pressure) prior to feeding the conditioned gas 107 to the CO2 Upgrading Process 106.

[0031] Figure 3 shows an embodiment of the instant invention in BFD form where the Gas Conditioning Step 108 is optional. In the case where the gas entering the CO2 UpgradingProcess 106 (either the Conditioned Gas 107 or the unconditioned Sweep gas + Desorbed Gas 105) contains less H2 than is required to perform the CO2 upgrading process (e.g., based on a stoichiometry of the CO2 upgrading process), additional H2 109 from a separate H2 source 110 is combined with the conditioned gas 107 (or unconditioned sweep gas + desorbed gas 105) to enrich the H2 composition to the desired value (e.g., to match a stoichiometric ratio of H2 to other components, including CO2, in the CO2 upgrading process).

[0032] Figure 4 shows an embodiment of the instant invention in BFD form where the Gas Conditioning Step 108 is optional. In the case where the gas entering the CO2 Upgrading Process 106 (either the Conditioned Gas 107 or the Sweep gas + Desorbed Gas 105) contains more H2 than is required (e.g., based on a stoichiometry of the CO2 upgrading process), H2 is removed in an H2 Removal Process 112, likely either an H2 pressure-swing adsorption unit or an H2 gas separation membrane, producing an H2 Depleted Gas 111 with the desired H2 composition to the CO2 Upgrading Process 106 (a composition matching a stoichiometric ratio of H2 to other components, including CO2, in the CO2 upgrading process), as well as an H2 enriched gas 113 (which is separated from the H2 depleted gas 111). The H2 depleted gas 111 is provided to the CO2 upgrading process 106, whereas in this example, the H2 enrich gas 113 is discarded or reserved for other purposes and processes. The pressure of the feed (e.g., conditioned gas 107 or sweep gas + desorbed gas 105) to the H2 Removal Process 112 may have to be compressed or expanded to a suitable operating pressure for the H2 Removal Process.

[0033] Figure 5 shows an embodiment of the instant invention in BFD form where the Gas Conditioning Step 108 is optional. In the case where the gas entering the CO2 Upgrading Process 106 (either the Conditioned Gas 107 or the Sweep gas + Desorbed Gas 105) contains more H2 than is required (e.g., based on a stoichiometry of the CO2 upgrading process), H2 is removed in an H2 Removal Process, likely either an H2 pressure-swing adsorption unit or an H2 gas separation membrane, producing an H2 Depleted Gas 111 with the desired H2 composition to the CO2 Upgrading Process 106 (a composition matching a stoichiometric ratio of H2 to other components, including CO2, in the CO2 upgrading process 106). The pressure of the feed to the H2 Removal Process 112 may have to be compressed or expanded to a suitable operating pressure for the H2 Removal Process. The H2-enriched gas 113 leaving the H2 Removal Process 112 is sent back around to the CO2 Capture Contactor 104 and combined with the sweep gas 103 from the Sweep gas Source 102 for use in sorbent regeneration.

[0034] Figure 6 shows an embodiment of the instant invention in BFD form where the Gas Conditioning Step 108, H2 Removal Process 112, and H2 Source 110 are optional. In the case where the gas entering the CO2 Upgrading Process 106 (either the Conditioned Gas 107 or the Sweep gas + Desorbed Gas 105) contains less H2 than is required, additional H2 from a separate H2 source is combined with this gas to enrich the H2 composition to the desired value. In the case where the gas entering the CO2 Upgrading Process 106 (either the Conditioned Gas or the Sweep gas + Desorbed Gas) contains more H2 than is required, H2 is removed in an H2 Removal Process, likely either an H2 pressure-swing adsorption unit or an H2 gas separation membrane, producing an H2 Depleted Gas with the desired H2 composition to the CO2 Upgrading Process. The pressure of the feed to the H2 Removal Process may have to be compressed or expanded to a suitable operating pressure for the H2 Removal Process. The H2- enriched gas leaving the H2 Removal Process may be sent back around to the CO2 Capture Contactor 104 and combined with the Sweep gas Source 102 for use in sorbent regeneration. In the case where the CO2 Upgrading Process produces a sweep gas byproduct, it can be recycled back to the CO2 Capture Contactor 104 and combined with Sweep gas 103 from the Sweep gas Source 102 for use in regeneration of the CO2 Capture Contactor. In the case where the composition of Desorbed Gas or CO2 Upgrading Process Recycle Gas changes transiently due to operational fluctuations, the optional Gas Conditioning Step, H2 Removal Process, and / or H2 Source may be transiently operated to levelize gas species compositions over time. This fully flexible transient operational mode could result in improved utilization rates for the downstream CO2 Upgrading Process.

[0035] Figure 7 is a flow chart illustrating a solid-sorbent-based carbon dioxide capture process 700.

[0036] The process includes providing (702) a solid-sorbent (e.g., a chemisorbent) having CO2 as an adsorbate (e.g., in CO2 capture contactor 104). In some embodiments, the solidsorbents are selected from a group consisting of: metal-organic frameworks, solid-supported amines, fiber sorbents, polymeric sorbents, metal carbonates, metal silicates, metal oxides, aluminosilicates, silicoaluminophosphates, carbons, porous polymers, porous organic fibers, resins, and their structural hybrids and physical mixtures. In some embodiments, the solidsorbent comprises alumina. In some embodiments, the solid-sorbent comprises metal-organic frameworks.

[0037] Chemisorbents are sorbents that form predominantly chemical bonds (covalent, ionic, or metallic bonds) with the adsorbate (in this case CO2), in contrast to physisorbentswhich form bonds based predominantly on Van der Waals / electrostatic interactions, such as dipole-dipole interactions. Stated another way, chemisorbents undergo a chemical reaction to bond with the adsorbate, and that chemical bond must be undone during the desorption process.

[0038] In some embodiments, the chemisorbent comprises solid-supported amines comprising amine groups. In some embodiments, the solid-supported amines is selected from the group consisting of: amine-containing organic structures, amine-containing polymers, aminoalkyl groups, aminophenyl groups, and amine-containing small molecules. In some embodiments, the amine group is selected from the group consisting of: branched polyethyleneimine (PEI), linear PEI, polypropyleneimine, ethyleneamine oligomers, diethylenetriamine (DETA), triethylenetetramine (TETA), tetraethylenepentamine (TEPA), pentaethylenehexamine (PEHA), and hexaethyleneheptamine (HEHA). In some embodiments, the amino groups comprise polyethyleneimine (PEI). In some embodiments, the polyethyleneimine (PEI) is a branched polyethyleneimine (PEI).

[0039] In some embodiments, process 700 includes performing a carbon capture cycle (using the solid-sorbent) that includes an adsorption step and a desorption step. The process 700 further includes providing (704) a sweep gas during the adsorption cycle. In some embodiments, the sweep gas further comprises molecular hydrogen. In some embodiments, the sweep gas consists essentially of molecular hydrogen having a concentration of at least 90% (e.g., by partial pressure). In some embodiments, sweep gas comprises trace agents. In some embodiments, the sweep gas further comprises carbon monoxide. In some embodiments the sweep gas comprises trace agents selected from the group consisting of: water vapor, light hydrocarbon paraffin gases, alcohols, carbon monoxide, carbon dioxide, sulfur dioxide, hydrazine, ammonia, and formic acid.

[0040] In some embodiments, the carbon monoxide and molecular hydrogen are in an appropriate stoichiometric mixture as feed to a downstream process step. In some embodiments, one or more components of the sweep gas are enriched or depleted before being provided to the downstream processing step, as described with reference to Figures 1-6 with respect to enrichment and / or depletion of hydrogen before being provided to a CO2 upgrading process. In some embodiments, the downstream process step is a step in a CO2 upgrading process. In some embodiments, the downstream process further comprises a reverse-water-gas- shift (RWGS) of the resulting gas, wherein CO2 and hydrogen in this gas are converted to syngas. In some embodiments, the downstream process comprises one or more of the group consisting of additional gas separation processes, storage, and combustion. In someembodiments, the downstream CO2 upgrading process further comprises at least one unit operation step selected from the group consisting of: water-gas-shift, reverse-water-gas-shift, electrolysis, direct hydrogenation, or methanation.

[0041] The process 700 further includes desorbing (706) CO2 from the solid-sorbent (during the desorption step of the carbon capture cycle). In some embodiments, the process further includes adsorbing CO2 from a feed gas before desorbing the CO2 and wherein the solid-sorbents selectively adsorb CO2 from said feed gas. In some embodiments, desorbing the CO2 comprises providing conditions (e.g., increasing the temperature of the sorbent) to break chemical bonds between the CO2 and the sorbent that were formed during the adsorbing of CO2. In some embodiments, the feed gas comprises air. In some embodiments, the feed gas further comprises at least one additional component selected from the group consisting of: molecular nitrogen, molecular oxygen, noble gases, light hydrocarbons, and carbon monoxide. In some embodiments, the feed does not include exhaust from a CO2 producing industrial process, or includes less than 50% exhaust from a CO2 producing process.

[0042] The process 700 further includes flowing the sweep gas over the solid-sorbent to produce resulting gas.

[0043] The sweep gas slows at least a sorbent degradation mechanism. In some embodiments, a solid-sorbent degradation rate is reduced by at least 25% (or 10%, 50%, 75%, or 100%) with respect to the solid-sorbent-based CO2 capture process without the use of said sweep gas.

[0044] In some embodiments, the sweep gas comprises molecular hydrogen. Process 700 includes enriching a concentration of molecular hydrogen in the resulting gas (e.g., by adding hydrogen from a hydrogen source 110 downstream of the CO2 capture contactor 104) to achieve an appropriate stoichiometric mixture as feed to a downstream process step, thereby producing a hydrogen enriched resulting gas. Process 700 further includes providing the hydrogen-enriched resulting gas to the downstream process step.

[0045] In some embodiments, process 700 further includes depleting a concentration of molecular hydrogen in the resulting gas to achieve an appropriate stoichiometric mixture as feed to a downstream process step, thereby producing a hydrogen-depleted resulting gas (e.g., through H2 removal process 112). Process 700 includes providing the hydrogen-depleting resulting gas to the downstream process step.

[0046] In some embodiments, depleting the concentration of molecular hydrogen in the resulting gas further produced a hydrogen-enriched resulting gas (e.g., hydrogen-enriched gas113) and the method further comprises re-using the hydrogen-enriched resulting gas as a portion of the sweep gas in subsequent flowing of the sweep gas over the solid-sorbent (thus recycling a portion of the hydrogen gas).

[0047] In some embodiments, the sweep gas comprises molecular hydrogen and the process 700 further comprises monitoring transient changes in a composition of the resulting gas (e.g., in real-time). The process 700 further comprises based on the monitoring of transient changes in the composition of the resulting gas, selecting one of: depleting a concentration of molecular hydrogen in the resulting gas to achieve an appropriate stoichiometric mixture as feed to a downstream process step; and enriching the concentration of molecular hydrogen in the resulting gas to achieve the appropriate stoichiometric mixture as feed to the downstream process step. The process 700 further comprises performing the selected one of depleting or enriching the concentration of molecular hydrogen, thereby producing a compositionally- modified resulting gas. The process 700 further comprises providing the compositionally- modified resulting gas to the downstream process step. The process 700 further comprises continuing the monitoring step and periodically (e.g., from time-to-time, based on the monitoring) repeating the steps of selecting between enriching and depleting and performing the subsequent actions.

[0048] It will be apparent to those skilled in the art that various modifications, combinations and variations can be made in the present invention without departing from the scope of the invention. Specific embodiments, features and elements described herein may be modified, and / or combined in any suitable manner. Thus, it is intended that the present invention cover the modifications, combinations and variations of this invention provided they come within the scope of the appended claims and their equivalents.

Claims

What is claimed is:

1. A solid-sorbent-based carbon dioxide (CO2) capture process, comprising: a) providing a solid-sorbent having CO2 as an adsorbate; b) providing a sweep gas during an adsorption step; c) desorbing CO2 from the solid-sorbent; and d) flowing the sweep gas over the solid-sorbent to produce resulting gas; e) providing the resulting gas to a CO2 upgrading process, wherein the sweep gas slows at least a sorbent degradation mechanism.

2. The solid-sorbent-based CO2 capture process according to claim 1, wherein the sweep gas further comprises molecular hydrogen.

3. The solid-sorbent-based CO2 capture process according to claim 1, wherein the sweep gas consists essentially of molecular hydrogen having a concentration of at least 90%.

4. The solid-sorbent-based CO2 capture process according to claim 1, wherein the sweep gas comprises trace agents.

5. The solid-sorbent-based CO2 capture process according to claim 4, wherein the sweep gas further comprises carbon monoxide.

6. The solid-sorbent-based CO2 capture process according to claim 5, wherein the sweep gas further comprises molecular hydrogen.

7. The solid-sorbent-based CO2 capture process according to claim 6, wherein the carbon monoxide and molecular hydrogen are in an appropriate stoichiometric mixture as feed to the CO2 upgrading process.

8. The solid-sorbent-based CO2 capture process according to claim 7, wherein the sweep gas consists essentially of molecular hydrogen having a partial pressure concentration of at least 90%.

9. The solid-sorbent-based CO2 capture process according to claim 1, wherein the solidsorbent comprises a chemisorbent.

10. The solid-sorbent-based CO2 capture process according to claim 10, wherein the chemisorbent comprises solid-supported amines comprising amine groups.

11. The solid-sorbent-based CO2 capture process according to claim 11, wherein the solid-supported amines is selected from the group consisting of: amine-containing organic structures, amine-containing polymers, aminoalkyl groups, aminophenyl groups, and amine-containing small molecules.

12. The solid-sorbent-based CO2 capture process according to claim 12, wherein the amine groups are selected from the group consisting of: branched polyethyleneimine (PEI), linear PEI, polypropyleneimine, ethyleneamine oligomers, diethylenetriamine (DETA), triethylenetetramine (TETA), tetraethylenepentamine (TEPA), pentaethylenehexamine (PEHA), and hexaethyleneheptamine (HEHA).

13. The solid-sorbent-based CO2 capture process according to claim 11 wherein the amino groups comprise polyethyleneimine (PEI).

14. The solid-sorbent-based CO2 capture process according to claim 14, wherein the polyethyleneimine (PEI) is a branched polyethyleneimine (PEI).

15. The solid-sorbent-based CO2 capture process according to claim 1, wherein the solidsorbent is selected from a group consisting of: metal-organic frameworks, solid- supported amines, fiber sorbents, polymeric sorbents, metal carbonates, metal silicates, metal oxides, aluminosilicates, silicoaluminophosphates, carbons, porous polymers, porous organic fibers, resins, and their structural hybrids and physical mixtures.

16. The solid-sorbent-based CO2 capture process according to claim 1, wherein the solidsorbent comprises alumina.

17. The solid-sorbent-based CO2 capture process according to claim 1, wherein the solidsorbent comprises metal-organic frameworks.

18. The solid-sorbent-based CO2 capture process according to claim 1, wherein the sweep gas comprises trace agents selected from the group consisting of: water vapor, light hydrocarbon paraffin gases, alcohols, carbon monoxide, carbon dioxide, sulfur dioxide, hydrazine, ammonia, and formic acid.

19. The solid-sorbent-based CO2 capture process according to claim 1, further comprising adsorbing CO2 from a feed gas before desorbing the CO2 and wherein the solidsorbent selectively adsorbs CO2 from said feed gas.

20. The solid-sorbent-based CO2 capture process according to claim 19, wherein the feed gas comprises air.

21. The solid-sorbent-based CO2 capture process according to claim 20, wherein the feed gas further comprises at least one additional component selected from the group consisting of: molecular nitrogen, molecular oxygen, noble gases, light hydrocarbons, and carbon monoxide.

22. The solid-sorbent-based CO2 capture process according to claim 1, wherein the CO2 upgrading process comprises a reverse-water-gas-shift (RWGS) of the resulting gas, wherein CO2 and hydrogen in this gas are converted to syngas.

23. The solid-sorbent-based CO2 capture process according to claim 1, wherein a solidsorbent degradation rate is reduced by at least 25% with respect to the solid-sorbent- based CO2 capture process without the use of said sweep gas.

24. The solid-sorbent-based CO2 capture process according to claim 1, wherein the CO2 upgrading process is selected from the group consisting of: additional gas separation processes, storage, and combustion.

25. The solid-sorbent-based CO2 capture process according to claim 1, wherein the CO2 upgrading process comprises at least one unit operation step selected from the group consisting of: water-gas-shift, reverse-water-gas-shift, electrolysis, direct hydrogenation, or methanation.

26. The solid-sorbent-based CO2 capture process of claim 1, wherein the sweep gas comprises molecular hydrogen and the process further comprising: a) enriching a concentration of molecular hydrogen in the resulting gas to achieve an appropriate stoichiometric mixture as feed to the CO2 upgrading process, thereby producing a hydrogen enriched resulting gas; and b) providing the hydrogen-enriched resulting gas to the CO2 upgrading process.

27. The solid-sorbent-based CO2 capture process of claim 1, wherein the sweep gas comprises molecular hydrogen and the process further comprises: a) depleting a concentration of molecular hydrogen in the resulting gas to achieve an appropriate stoichiometric mixture as feed to the CO2 upgrading process, thereby producing a hydrogen-depleted resulting gas; and b) providing the hydrogen-depleting resulting gas to the CO2 upgrading process.

28. The solid-sorbent-based CO2 capture process of claim 27, wherein depleting the concentration of molecular hydrogen in the resulting gas further produced a hydrogen-enriched resulting gas and the process further comprises re-using the hydrogen-enriched resulting gas as a portion of the sweep gas in subsequent flowing of the sweep gas over the solid-sorbent.

29. The solid-sorbent-based CO2 capture process of claim 1, wherein the sweep gas comprises molecular hydrogen and the process further comprises: a) monitoring transient changes in a composition of the resulting gas;b) based on the monitoring of transient changes in the composition of the resulting gas, selecting one of: i. depleting a concentration of molecular hydrogen in the resulting gas to achieve an appropriate stoichiometric mixture as feed to the CO2 upgrading process; and ii. enriching the concentration of molecular hydrogen in the resulting gas to achieve the appropriate stoichiometric mixture as feed to the CO2 upgrading process; c) performing the selected one of depleting or enriching the concentration of molecular hydrogen, thereby producing a compositionally-modified resulting gas; and d) providing the compositionally-modified resulting gas to the CO2 upgrading process.

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