Point source carbon capture system

Abstract

In one aspect, methods of removing CO2 from flue gas or exhaust gas streams generated from point sources, including but not limited to power generation facilities, concrete production facilities, chemical and food processing facilities, are described herein. A method, in some embodiments, includes an adsorption cycle for removing at least 70% of CO2 from an exhaust gas stream. The adsorption cycle includes flowing the exhaust gas stream through at least one adsorbent bed formed by a monolithic structured adsorber including an outer peripheral wall and a plurality of inner partition walls carrying an organic or inorganic compound that adsorbs CO2 from the exhaust gas stream.

Description

[0001] Cross - Reference to Related Applications

[0002] Under Article 8 of the Patent Cooperation Treaty, this application claims the benefit of priority of U.S. Provisional Patent Application No. 63 / 425,549, filed on November 15, 2022, the entire content of which is incorporated herein by reference. Technical Field

[0003] This application relates to carbon capture technology, and more particularly to technologies for removing and capturing carbon dioxide (CO2) from point - source flue gas streams. Background Art

[0004] Global warming and related climate change caused by human activities pose an existential threat to numerous ecosystems and current human lifestyles. The extraction and combustion of fossil fuels are the main causes of global warming as they release large amounts of heat - absorbing gases, including methane and CO2. CO2 is the main component of greenhouse gas emissions, and in recent years, the CO2 concentration has exceeded 400 ppm. Current CO2 levels exceed any concentration in the past 800,000 years.

[0005] Given this alarming trend in atmospheric CO2 concentration, countries and industries have initiated various mitigation strategies to reduce CO2 emissions as well as methane emissions. The electrification of transportation vehicles and systems has received wide attention. In addition, the transition to green / renewable energy such as wind and solar energy has received a large amount of private and public investment. Although these mitigation strategies are promising, they have not addressed the current CO2 in the atmosphere and the CO2 generated from current fossil fuel consumption. Therefore, existing CO2 levels rely on the slow natural degradation process. Summary of the Invention

[0006] On the one hand, this document describes a method for removing CO2 from flue gas or waste gas streams generated from point sources (including but not limited to power generation facilities, concrete production facilities, chemical and food processing facilities). Such CO2 removal is generally referred to as point source capture. One method, in some embodiments, the method includes an adsorption cycle for removing at least 70% of the CO2 from the waste gas stream. The adsorption cycle includes flowing the waste gas stream through at least one adsorption bed formed by a monolithic structure adsorber, the monolithic structure adsorber including an outer peripheral wall and a plurality of internal partition walls, the internal partition walls carrying an organic compound or an inorganic compound that adsorbs CO2 from the waste gas stream, wherein the inlet temperature of the waste gas stream is at least 60 °C, the CO2 content is 3% to 20%, and the water vapor content is 2% to 22%. The adsorption bed is isolated from the waste gas stream, and steam at a pressure of -2 psig to 2 psig and a maximum temperature of 120 °C flows through the adsorption bed in a direction opposite to the flow direction of the waste gas stream, providing the enthalpy for CO2 desorption to desorb the CO2 captured by the adsorption bed. The first part of the steam condenses in the pores of the monolithic structure adsorber, and the second part of the steam purges the desorbed CO2 out of the adsorption bed, forming a mixture of desorbed CO2 and purge steam. Then the CO2 is separated from the mixture, thereby providing a CO2 product gas of at least 90 wt.%. The isolation of the adsorption bed from the waste gas stream is stopped, the waste gas stream re-enters the monolithic structure adsorber, evaporates the condensed steam in the pores, and cools the adsorber to a temperature below 90 °C to start a new adsorption cycle.

[0007] In some embodiments, the method described herein employs at least two adsorption beds, wherein at any given time, the first adsorption bed removes CO2 from the waste gas stream, while the second adsorption bed is isolated from the waste gas stream and desorbs the CO2 captured by the monolithic structure adsorber. The adsorption of CO2 by the first bed and the desorption of CO2 by the second bed are carried out according to the procedures detailed above.

[0008] In addition, in some embodiments, a condensation heat exchanger is located downstream of one or more adsorption beds. In some embodiments, the heat exchanger is operable to recover water vapor from the waste gas stream of a combustion process, and / or evaporate the condensed steam from the monolithic structure adsorber of the bed.

[0009] These and other embodiments will be further described in the detailed description below. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 A honeycomb monolithic structure adsorber according to some embodiments herein is shown.

[0011] Figure 2 A flow channel 12 defined by an internal partition wall 11 in a honeycomb monolithic structure catalyst body according to some embodiments herein is shown.

[0012] Figure 3 A method for determining the average thickness of the outer peripheral wall 10 and the internal partition wall 11 is shown.

[0013] Figure 4 A plan view of a module including an integral structure adsorber according to some embodiments is shown.

[0014] Figure 5 It is a schematic diagram showing the method described herein according to some embodiments. Detailed Description

[0015] The embodiments described herein can be more readily understood by reference to the following detailed description and examples, as well as the description before and after them. However, the elements, devices, and methods described herein are not limited to the specific embodiments set forth in the detailed description and examples. It should be recognized that these embodiments are merely illustrative of the principles of the present invention. Various modifications and adaptations will be apparent to those skilled in the art without departing from the spirit and scope of the present invention.

[0016] On the one hand, a method for removing CO2 from a flue gas or waste gas stream generated from a point source (including but not limited to power generation facilities, concrete production facilities, chemical and food processing facilities) is described herein. In some embodiments, the method includes an adsorption cycle for removing at least 70% of the CO2 from the waste gas stream. The adsorption cycle includes flowing the waste gas stream through at least one adsorption bed formed by an integral structure adsorber, the integral structure adsorber including an outer peripheral wall and a plurality of internal partition walls, the internal partition walls carrying an organic compound or an inorganic compound for adsorbing CO2 from the waste gas stream, wherein the inlet temperature of the waste gas stream is at least 60 °C, the CO2 content is 3% to 20%, and the water vapor content is 2% to 22%. The adsorption bed is isolated from the waste gas stream, and steam at a pressure of -2 psig to 2 psig and a maximum temperature of 120 °C flows through the adsorption bed in a direction opposite to the flow direction of the waste gas stream, providing the enthalpy for CO2 desorption to desorb the CO2 captured by the adsorption bed. A first portion of the steam condenses in the pores of the integral structure adsorber, and a second portion of the steam sweeps out the desorbed CO2 in the adsorption bed to form a mixture of desorbed CO2 and sweep steam. Then the CO2 is separated from the mixture, thereby providing a product gas with at least 90 wt.% of CO2. The isolation of the adsorption bed from the waste gas stream is stopped, the waste gas stream re-enters the integral structure adsorber, evaporates the condensed steam in the pores, and cools the adsorber to a temperature below 90 °C to start a new adsorption cycle.

[0017] Turning now to the specific components, the adsorption bed employed in the point source capture method described herein utilizes a monolithic structure adsorber. The monolithic structure adsorber includes an outer peripheral wall and a plurality of internal dividing walls, and the internal dividing walls carry organic or inorganic compounds that adsorb CO2 from the waste gas stream. In some embodiments, the outer peripheral wall and the plurality of internal dividing walls are covered with a support containing an inorganic oxide component. In some embodiments, by being dispersed throughout the outer peripheral wall and the internal dividing walls, the support containing the inorganic oxide component forms the outer dividing walls and the internal dividing walls. The support can include any inorganic oxide that is not contradictory to the technical purposes described herein. In some embodiments, the inorganic oxide includes at least one of titanium dioxide (TiO2), aluminum oxide (Al2O3), and zirconium oxide (ZrO2). In some embodiments, the inorganic oxide component is titanium dioxide-based or aluminum oxide-based. The aluminum oxide of the inorganic oxide can include one or more polymorphs, including gamma alumina. In the case of being titanium dioxide-based or aluminum oxide-based, titanium dioxide or aluminum oxide is the inorganic oxide present in the highest amount in the component. In some embodiments, for example, the aluminum oxide-based inorganic oxide component contains 40 wt.% to 100 wt.% of aluminum oxide. Similarly, in some embodiments, the titanium dioxide-based inorganic oxide component contains 40 wt.% to 100 wt.% of titanium dioxide.

[0018] In some embodiments, the support contains 50 wt.% to 100 wt.% of the inorganic oxide component. In some embodiments, the inorganic oxide of the support substantially does not include oxides of tungsten, vanadium, and / or molybdenum. For example, the inorganic oxide of the support contains less than 5 wt.%, less than 3 wt.%, less than 1 wt.% of oxides of tungsten, vanadium, and / or molybdenum. Additionally, in some embodiments, the inorganic oxide component includes less than 100 ppm of iron or iron compounds, which can be used for the oxidation and / or other degradation of CO2 capture functional groups (such as amine functionalities) associated with the support. The support can also contain fillers and / or reinforcing agents, as further described herein.

[0019] In some embodiments, the support exhibits a hierarchical pore structure that has a macroporosity of at least 0.05 cc / g in pores with a diameter ranging from 600 to 5,000 angstroms. In some embodiments, in pores from 600 to 5,000 angstroms, the macroporosity ranges from 0.05 cc / g to 0.3 cc / g or from 0.08 cc / g to 0.2 cc / g. In some embodiments, the macroporosity of the support includes a first porosity distribution of at least 0.08 cc / g in pores with a diameter ranging from 600 to 5,000 angstroms and a second porosity distribution of at least 0.16 g / cc in pores with a diameter ranging from greater than 5,000 angstroms up to 50,000 angstroms, wherein the sum of the first and second porosity distributions falls within a total macroporosity range of 0.24 cc / g to 1.0 cc / g. In some embodiments, the macroporosity is bimodal or multimodal, where the sum of the individual peaks yields the total macroporosity. In some embodiments, the first porosity distribution is greater than the second porosity distribution of the macroporosity. Alternatively, the second porosity distribution of the macroporosity can be greater than the first porosity distribution.

[0020] In addition to the macroporosity, the support can have a mesoporosity of at least 0.15 cc / g or at least 0.20 cc / g in pores with a diameter ranging from 20 to 500 angstroms. In some embodiments, the support has a mesoporosity of at least 0.30 cc / g in pores from 20 to 500 angstroms. The mesoporosity of the support can also have values selected from Table 1.

[0021] Table 1 - Support Mesoporosity in Pores with a Diameter Ranging from 20 to 500 Angstroms

[0022] 0.15-0.70 0.20-0.60 0.20-0.55 0.20-0.50 0.25-0.45 0.30-0.55 0.35-0.60 0.15-0.30 0.15-0.25

[0023] The ratio of the mesoporosity to the macroporosity of the support can be greater than 1, such as greater than 1.1 or greater than 1.2. In other embodiments, the ratio of the mesoporosity to the macroporosity of the support is less than 1, such as 0.5 to 0.8. The macroporosity of the support can be measured by mercury intrusion porosimetry, while the mesoporosity can be measured by nitrogen (N2) adsorption.

[0024] As described herein, the support having the aforementioned hierarchical pore structure is dispersed on the entire outer peripheral wall and internal partition walls of the monolithic structure adsorber. In some embodiments, the support comprising an inorganic oxide component forms the outer peripheral wall and internal partition walls of the monolithic structure adsorber. The internal partition walls are disposed within the dimensions defined by the outer peripheral wall, and the internal partition walls define a plurality of flow channels that longitudinally extend through the monolithic structure adsorber. Figure 1 A honeycomb monolithic structure adsorber according to some embodiments herein is shown.Figure 1 The honeycomb-structured adsorber in the embodiments includes an outer peripheral wall 10 and a plurality of internal partition walls 11. The internal partition walls 11 define a plurality of flow channels 12 that longitudinally extend through the honeycomb monolithic-structured adsorber.

[0025] Figure 2 Shows the flow channels 12 defined by the internal partition walls 11 in a honeycomb monolithic-structured catalyst body according to some embodiments herein. The internal partition walls 11 and their junctions with the outer peripheral wall serve as boundaries for adjacent flow channels 12. When a portion of the outer peripheral wall 10 serves as a boundary for a flow channel 12, that portion may be referred to as an outer peripheral wall segment 13. As Figure 1 and Figure 2 shown, the flow channels 12 establish a flow channel density or cell density on the inlet and outlet faces of the monolithic-structured adsorber. The monolithic-structured adsorbers described herein can have any desired cell density or flow channel density. As described above, the cell density of the monolithic-structured adsorber is at least 85 cpsi. In some embodiments, the pore density of the monolithic-structured adsorber is from 100 cpsi to 900 cpsi. For example, the cell density of the monolithic-structured adsorber can be from 100 cpsi to 500 cpsi, from 140 cpsi to 450 cpsi, or from 170 cpsi to 500 cpsi. Additionally, in some embodiments, the length of the flow channels or cells is at least 100 mm or at least 110 mm. In some embodiments, the length of the flow channels of the cells of the monolithic-structured processing body is at least 120 mm or at least 125 mm.

[0026] Furthermore, as described above, the thickness of the internal partition walls of the monolithic-structured adsorber is from 0.1 mm to 0.3 mm. In some embodiments, the thickness of the internal partition walls can be from 0.1 mm to 0.25 mm, from 0.1 mm to 0.2 mm, from 0.1 mm to 0.25 mm, from 0.15 mm to 0.25 mm, or from 0.15 mm to 0.2 mm. The thicknesses of the outer peripheral wall and the internal partition walls are determined using a caliper or micrometer with a resolution of 0.01 mm. Figure 3 Shows a method for determining the average thicknesses of the outer peripheral wall 10 and the internal partition walls 11. The thickness of the outer peripheral wall 10 is measured at twelve (12) different locations on a catalyst body sample. The twelve measurement locations include three sites on each side of the square outer peripheral wall as shown in Figure 3 The average thickness of the outer peripheral wall 10 is calculated by taking the average of the values obtained from the twelve (12) measurements. Similarly, the average thickness of the internal partition walls 11 is determined by initially measuring the thickness of the internal partition walls 11 at twelve (12) different locations throughout the catalyst body. As Figure 3As shown, the internal dividing wall 11 is measured in the horizontal and vertical directions. The average thickness of the internal dividing wall 11 is calculated by taking the average of the values obtained from twelve measurements.

[0027] The thin internal dividing wall can help achieve a high cpsi without sacrificing the open frontal area of the monolithic structure adsorber and / or causing an unacceptable pressure drop when the gas flows through the monolithic structure body. The open frontal area (OFA) of the monolithic structure adsorber is the part of the body cross-section available for gas flow in the cross-section perpendicular to the gas flow direction. Increasing the open frontal area can make the fluid flow characteristics in the monolithic body more efficient, thereby reducing the pressure drop experienced by the fluid flowing through the monolithic structure adsorber. The OFA of the monolithic structure adsorber described herein is at least 65%. In some embodiments, the OFA of the monolithic structure adsorber is at least 70% or at least 80%. In some embodiments, the OFA range of the monolithic structure adsorber can be 65 to 90%, 65 to 85%, 70% to 90%, 70% to 80%, 75% to 85%, or 80% to 90%.

[0028] As described above, the hydraulic diameter of the monolithic structure adsorber is also at least 100 mm. The hydraulic diameter of the catalyst body is defined as the cross-sectional area perpendicular to the flow direction of the catalyst body multiplied by 4 and then divided by the outer perimeter value of the outer peripheral wall. When the monolithic structure catalyst body has a circular cross-sectional geometry, the hydraulic diameter is equal to the diameter of the circular cross-sectional area. For a square cross-sectional geometry, the hydraulic diameter is equal to the length or width of the side. Therefore, the hydraulic diameter characterizes the size of the monolithic structure adsorber, and the larger the value of the hydraulic diameter, the larger the corresponding monolithic structure adsorber. In some embodiments, the hydraulic diameter of the monolithic structure adsorber is at least 120 mm or at least 130 mm. The range of the hydraulic diameter of the monolithic structure adsorber can be 100 mm to 150 mm, 120 mm to 150 mm, or 130 mm to 150 mm. In some embodiments, the hydraulic diameter of the monolithic structure adsorber can be greater than 150 mm. In some embodiments, the upper limit of the hydraulic diameter of the monolithic structure adsorber can be 300 mm.

[0029] In addition to the thin internal dividing wall, high OFA, large hydraulic diameter, and high porosity provided by the hierarchical pore structure, the monolithic structure adsorber also exhibits sufficient transverse compressive strength to allow the monolithic body to be used in industrial gas treatment applications. Insufficient transverse compressive strength may prevent the arrangement or packaging of the monolithic structure adsorber in modules and / or other configurations for industrial gas treatment applications.

[0030] Figure 4A plan view of a module including an integral structure adsorber according to some embodiments is shown. Module 20 includes an open metal frame 22 for carrying the integral structure adsorber 24 disposed therein. The integral structure adsorbers 24 are arranged side by side. In some embodiments, a packing material, cement, or silicone resin is located between one or more sides of adjacent integral adsorbers to prevent gas from flowing around the integral adsorbers. Modules containing integral structure adsorbers can be arranged to form the adsorption beds described herein.

[0031] When arranged in module form, as Figure 4 shown, the integral structure adsorbers are subject to compressive forces generated by the pressure between the adsorbers when assembled side by side (whether or not a sealing material is used), and also when stacked together to form a large enough array to handle a large volume of gas (whether or not a sealing material is used).

[0032] In some embodiments, the integral structure adsorbers exhibit a transverse compressive strength of at least 500 g / cm 2 . The transverse compressive strength of the integral structure adsorbers can also have a value selected from Table 2.

[0033] Table 2 - Transverse Compressive Strength (g / cm 2 )

[0034] ≥600 ≥750 ≥800 ≥1,000 500-1,000 750-1,300

[0035] The transverse compressive strength of the integral structure catalyst body of the present invention can be measured using a compression testing device such as a Tinius Olson 60,000 lb. Super "L" type compression testing machine with a maximum compression load of 30,000 kg can be obtained from Tinius Olsen Company, Willow Grove, Pa. Transverse compressive strength test samples can be prepared by cutting the integral structure catalyst into segments typically 150 mm in length but at least 50 mm in length, where each segment can be used as a separate test sample.

[0036] Ceramic wool 6 mm thick can be placed under and above the pressure surface of the sample, and the wrapped sample can be placed in a vinyl bag at the center of the pressure plate. The pressure plate used in the test can be stainless steel with dimensions of 160 mm x 160 mm. The transverse compressive strength is quantified by applying a compressive load in a direction parallel to the cross-section of the honeycomb structure and perpendicular to the dividing wall on the bottom side. Thus, the compressive load is applied in a direction perpendicular to the flow direction in the flow channels. The compressive load can be applied as shown in Table 3.

[0037] Table 3 - Compressive Load

[0038] Compression speed 25 kg / s 50 kg / s

[0039] The instrument records the maximum lateral compression load W (g) endured by the sample. Subsequently, the lateral compressive strength is calculated based on the maximum compression load (in gram-force (gf)) by dividing the value of the maximum compression load by the surface area of the applied load.

[0040] When producing the monolithic structure adsorber described herein, lubricants and other extrusion aids are used to reduce the shear stress and pressure during the processing. The mixing energy can be monitored through the motor current, and the mixing cycle can be optimized to minimize the mixing energy. The extruder tolerance can be maintained, the flow transition can be minimized, and / or a more positive pressure extruder can be used to minimize the shear stress during the extrusion process. The die can be designed to minimize the internal pressure loss during the extrusion process, for example, a tapered inlet is used for the open channel at the die inlet. The die surface can also be designed to minimize the friction within the die, for example, by polishing the inner surface and using nickel plating. The conveying system downstream of the extruder can be designed to minimize the force applied to the extrudate to minimize the hardness required for the batch, for example, using a foam conveyor surface or an air bearing.

[0041] In some embodiments, the monolithic structure adsorber described herein may further comprise an inorganic binder and / or a reinforcing agent. In some embodiments, the inorganic binder and / or one or more reinforcing agents may be present in the monolithic structure adsorber in an amount of 3 wt.% to 30 wt.%. The reinforcing agent may include reinforcing fibers, including glass (SiO2) fibers, carbide fibers, ceramic fibers, and mixtures thereof. In some embodiments, the diameter of the reinforcing fibers is 3 μm to 10 μm. The inorganic binder and / or the reinforcing agent can be added to the inorganic oxide extrusion batch. When using fiber-reinforcing materials, the extrusion conditions described herein are carefully controlled because such reinforcing materials can complicate or interfere with the mesopore porosity and macropore porosity that produce the desired hierarchical pore structure. The extrusion system can include an extruder, a filter or sieve, and an extrusion die. A filter or sieve can be used to facilitate the passage of the mixture through the die while minimizing the shear stress. Particles clogging the die can be removed without removing the filler, binder, glass fiber, and / or other reinforcing agents that can provide favorable product properties. In some embodiments, for example, a wedge-shaped sieve is used to prevent or slow down the removal of the fiber-reinforcing material from the mixture.

[0042] The monolithic structured adsorber described herein contains one or more organic or inorganic chemical substances and can be used to capture CO2 from the gas stream flowing through the monolithic structured adsorber. The internal partition walls and the outer peripheral wall can carry organic or inorganic chemical substances that can be used to capture CO2. Therefore, a monolithic structured adsorber that does not contain one or more chemical substances that can be used to capture CO2 can be regarded as a substrate for one or more chemical substances that can be used to capture CO2. One or more chemical substances that can be used to adsorb CO2 from the waste gas stream can be associated with a support that exhibits the above-described hierarchical pore structure. One or more chemical substances for CO2 adsorption can be dispersed throughout the support, in the mesopores, macropores, or a combination thereof, of the hierarchical pore structure. After association with the support, the chemical substances for CO2 adsorption can be dispersed throughout the internal partition walls. Such a structure is fundamentally different from a support coating, which is a refractory oxide layer coated on a substrate as a support for the adsorption chemical substances.

[0043] The chemical substances for CO2 adsorption can be organic compounds or inorganic compounds. In some embodiments, the chemical substances include one or more organic compounds containing amine functional groups for CO2 adsorption. For example, the chemical substances can include one or more polymeric substances containing amine functional groups. In some embodiments, the polymeric substances contain polyalkyleneimines, including polyethyleneimine, polypropyleneimine, or a combination thereof. The polymeric substances containing amine functional groups for CO2 adsorption can be linear, branched, or hyperbranched (dendrimers). The polymeric substances containing amine functional groups for CO2 adsorption can include homopolymers, copolymers, and graft copolymers. The organic compounds containing amine functional groups for CO2 adsorption can also include small molecules (non-polymers), such as tetra(ethylene pentamine) (TEPA).

[0044] As described herein, the organic compounds containing amine functional groups for CO2 adsorption can be dispersed throughout the support, in the mesopores, macropores, or a combination thereof, of the hierarchical pore structure. In some embodiments, the ratio of the organic compounds containing CO2 capture functional groups located in the mesopores to the organic compounds containing CO2 capture functional groups located in the macropores is greater than 1. In some embodiments, the ratio ranges from 1.5 to 10 or 2 to 5. Additionally, in some embodiments, at least 80% of the organic compounds containing CO2 capture functional groups are located in the mesopores. In some embodiments, 80% to 90% of the organic compounds containing CO2 capture functional groups are located in the mesopores. Furthermore, in some embodiments, at least 75% of the organic compounds containing CO2 capture functional groups are located in the mesopores, where the total mesopore volume reduction due to the inclusion of the organic compounds does not exceed 70%.

[0045] Organic compounds containing amine functional groups for CO2 adsorption can form one or more interactions with the inorganic oxide components of the support. In some embodiments, the organic compound forms van der Waals interactions and / or ionic interactions with the support inorganic oxide component, thereby forming mesopores and / or macropores. In other embodiments, the organic compound can be covalently bound to the inorganic oxide component. For example, the organic compound can contain one or more functional groups for reacting with surface functional groups of the inorganic oxide, such as hydroxide, oxide, and / or carboxyl surface functional groups. In some embodiments, a chemical linker can be employed to covalently bind the organic compound containing amine functional groups to the support inorganic oxide component.

[0046] Organic compounds containing amine functional groups for CO2 adsorption can partially fill the mesopores and / or macropores of the support hierarchical pore structure. Additionally, in some embodiments, the organic compound can be uniformly or substantially uniformly distributed within the mesopores and / or macropores along the entire length of the flow channels or cells of the monolithic structure adsorber. In some embodiments, the organic compound containing amine functional groups for CO2 adsorption can be present in the monolithic structure adsorber in an amount of at least 10 wt.%. In some embodiments, the organic compound is present in the monolithic structure adsorber in an amount of 10 wt.% to 30 wt.%.

[0047] In some embodiments, adding an organic compound containing amine functional groups for CO2 adsorption to the support hierarchical pore structure can increase the transverse compressive strength of the monolithic structure adsorber relative to the bare monolithic body. For example, in some embodiments, including one or more organic compounds in at least 40% of the mesopore porosity increases the transverse compressive strength of the monolithic body by at least 50% relative to the transverse compressive strength of the bare or empty monolithic body.

[0048] To facilitate an improvement in the performance life of the monolithic structure adsorber described herein, the inorganic oxide component of the support can be free or substantially free of metal-containing compounds that can be used to oxidize the organic compound containing amine functional groups for CO2 adsorption. In some embodiments, the inorganic oxide component is free or substantially free of compounds, including oxides, containing metals selected from the group consisting of tungsten, vanadium, iron, chromium, and / or molybdenum. For example, the inorganic oxide of the support includes less than 5 wt.%, less than 3 wt.%, less than 1 wt.% of compounds of tungsten, vanadium, and / or molybdenum. Additionally, in some embodiments, the inorganic oxide component includes less than 100 ppm of iron or iron compounds that can be used for the oxidation and / or other degradation of CO2 capture functional groups (such as amine functional groups) associated with the support.

[0049] As an alternative to organic compounds containing amine functional groups, the monolithic structured adsorbers described herein can include one or more alkali metal-based functional groups for CO2 adsorption. In some embodiments, the alkali metal-based functional groups include alkali metal oxides that can be used for CO2 adsorption. The alkali metal oxides can be dispersed throughout the inorganic oxide component of the support and are thus located in the mesopores and / or macropores of the hierarchical pore structure. Any alkali metal oxide compound can be used with the monolithic structured adsorbers described herein. In some embodiments, for example, the alkali metal oxides include alkali metal carbonates, including sodium carbonate and / or potassium carbonate.

[0050] A monolithic structured adsorber containing an organic or inorganic compound for CO2 capture can exhibit a mesopore porosity greater than 0.05 cc / g in pores with a diameter ranging from 20 to 500 angstroms. The mesopore porosity of a monolithic structured adsorber containing an organic or inorganic compound for CO2 capture is measured by nitrogen (N2) adsorption.

[0051] As described herein, an exhaust gas stream flows through at least one bed formed by a monolithic structured adsorber to remove at least 70% of the CO2 from the exhaust gas stream, where the inlet temperature of the exhaust gas stream is at least 60 °C, the CO2 content is 3% to 20%, and the water vapor content is 2% to 22%. In some embodiments, the inlet temperature of the exhaust gas stream is 60 to 95 °C. Upstream treatment can be performed on the exhaust gas stream before it enters one or more adsorption beds. For example, the exhaust gas stream can be subjected to selective catalytic reduction (SCR) treatment to remove nitrogen oxides and / or mercury from the exhaust gas stream. Additionally, the exhaust gas stream can be mixed with other gases (such as ambient air) to cool, dry, and / or dilute the CO2 content in the exhaust gas stream. In some embodiments, the exhaust gas stream flows through one or more filters upstream of the inlet to one or more adsorption beds. The filters can remove particulate matter that is harmful to the monolithic structured adsorber, including metal oxide particles that promote the degradation of the CO2 adsorption functional groups and particles that may clog or otherwise impede the gas flow channels of the monolithic structured adsorber. In some embodiments, one or more filters remove 20% to 95% of the particles with a size of 0.3 μm or larger.

[0052] After the exhaust gas stream has flowed through one or more beds and CO2 has been adsorbed from the exhaust gas stream using the monolithic structured adsorber, the adsorption bed is isolated from the exhaust gas stream. The one or more beds that have adsorbed CO2 can be isolated from the gas stream by closing valves, louvers, or other panels through which the exhaust gas stream flows. The valves, louvers, or other panels can have a fixed position, i.e., the valves, louvers, or other panels do not move or change position within the CO2 removal system. Additionally, in some embodiments, the adsorption beds are also fixed and do not move. These principles are further illustrated in the following discussion. Figure 5 These principles are further illustrated.

[0053] Once isolated, steam at a pressure of -2 psig to 2 psig and a temperature of 96 °C to 120 °C will flow through the adsorption bed in a direction opposite to the flow of the waste gas stream, providing the enthalpy for CO2 desorption to desorb the CO2 captured by the adsorption bed. The first portion of the steam condenses in the pores of the monolithic structure adsorber, and the second portion of the steam sweeps out the desorbed CO2 from the adsorption bed, thereby providing a mixture of desorbed CO2 and sweep steam. The CO2 is then separated from the mixture, thereby providing a product gas with at least 90 wt.% CO2. In some embodiments, the mixture of desorbed CO2 and sweep steam is cooled to condense the steam, thereby providing a product gas with at least 90 wt.% CO2. In some embodiments, the product gas contains 90 wt.% to 99 wt.% CO2.

[0054] In some embodiments, after the steam desorption process, at least 1% or at least 10% of the adsorbed CO2 remains on the monolithic structure adsorber. The remaining CO2 can protect the organic or inorganic CO2 adsorption functional groups of the monolithic structure adsorber from degradation, thereby extending the service life of the structure adsorber. In some embodiments, after the steam desorption process, 1% to 20% of the desorbed CO2 remains on the monolithic structure adsorber. Additionally, during the adsorption of CO2 from the waste gas stream, the change in ammonia concentration in the waste gas stream from the inlet to the outlet of the adsorption bed is less than 2 ppm on average. In a high water content gas stream, an FTIR multi-gas analyzer with ppb-level sensitivity is used to measure the ammonia content in the waste gas stream. An increase in ammonia concentration at the outlet of the adsorption bed can indicate the decomposition or degradation of the amine CO2 adsorption functional groups in the bed.

[0055] The isolation of the adsorption bed from the waste gas stream is stopped, the waste gas stream re-enters the monolithic structure adsorber, the condensed steam in the evaporation pores is evaporated, and the adsorber is cooled to a temperature below 90 °C to start a new adsorption cycle.

[0056] In some embodiments, the method described herein employs at least two adsorption beds, where at any given time, the first adsorption bed removes CO2 from the waste gas stream, while the second adsorption bed is isolated from the waste gas stream and desorbs the CO2 captured by the monolithic structure adsorber. The adsorption of CO2 by the first bed and the desorption of CO2 by the second bed are carried out according to the procedures detailed above.

[0057] Figure 5 is a schematic diagram showing the method described herein according to some embodiments. In Figure 5In an embodiment, a first adsorption bed (adsorption) having the structure and characteristics described herein is removing CO2 from an exhaust gas stream or a flue gas stream. The cooled flue gas (70 °C) flows through a louver valve and into the adsorption bed, where CO2 (black dots) is removed from the flue gas stream by adsorption through the monolithic structure adsorber of the adsorption bed. A second adsorption bed (desorption) having the structure and characteristics described herein undergoes a CO2 desorption process by exposure to steam (gray circles). The louver valve that allows the flue gas to flow into the second adsorption bed is closed, thereby isolating the second adsorption bed from the flue gas stream during the CO2 desorption process. As described herein, the steam flows into the second adsorption bed in a direction opposite to the flue gas path through the second adsorption bed. The resulting mixture of desorbed CO2 and purge steam (black and gray circles) is sent to a condenser for cooling, thereby condensing the steam and providing a product gas containing at least 90 wt.% of CO2.

[0058] Additionally, in some embodiments, a condensation heat exchanger (not shown in Figure 5 ) may be installed downstream of the adsorption bed in order to recover the steam that condenses in the adsorption bed during the desorption process. The total amount of water recovered from the condensation heat exchanger plus the amount removed during the separation of the CO2 product from the desorption is equivalent to at least 90% of the steam introduced into the adsorption bed during the desorption process. In some embodiments, the heat exchanger also recovers at least 2% of the water vapor in the exhaust gas stream generated during the combustion process.

[0059] The following non-limiting examples further illustrate these and other embodiments.

[0060] Example 1 - Removal of CO2 from an Exhaust Gas Stream

[0061] A monolithic structure adsorber having the parameters in Table 4 was placed in a test chamber to quantify the amount of CO2 removed from an exhaust gas stream.

[0062] Table 4 - Monolithic Structure Adsorber

[0063] Parameter Value Composition Titanium dioxide cpsi 170 Inner partition wall thickness 0.23 mm Open frontal area 77％ Hydraulic diameter 145 mm Porosity 0.08 cc / g PEI loading 14 wt.%

[0064] One CO2 adsorption / desorption cycle on the test system was run as follows. A simulated feed gas containing CO2 was injected into the monolithic adsorber section at a space velocity of 2483 h-1. The average CO2 content of the exhaust gas stream at the inlet of the monolithic structure adsorber was 4.2%, the average water content was 17.4%, and the average inlet temperature was 88.4 °C. The CO2 capture efficiency was quantified by simultaneously measuring the inlet and outlet CO2 concentrations and using the following formula: C.E. = [1 - (∑CO2 out * Δt) / (∑CO2 in * Δt)] * 100%, where Δt = 5 seconds; the sum was from 0 to 120 seconds.

[0065] After the adsorption step is completed, the feed gas is cut off (by diverting it to the second adsorption chamber), and steam is passed through the monolithic adsorber from the other side of the adsorber section; this steam provides both the heat required to desorb CO2 from the monolithic adsorber and the purge gas for collecting the desorbed CO2. The steam / CO2 mixture flows through a condensation heat exchanger to remove moisture; the resulting CO2 stream is compressed and stored in a tank. A slipstream flow withdrawn from the transfer line between the compressor and the storage tank is analyzed by a high-concentration range CO2 analyzer to quantify the CO2 purity. The outlet gas of this CO2 analyzer is then fed back to the compressor inlet to recover the analyzed CO2. The test results show that the CO2 capture efficiency (C.E.) is 97.7% and the CO2 content in the product gas is 94.6 wt.%.

[0066] To achieve the various objects of the present invention, various embodiments of the present invention have been described. It should be recognized that these embodiments are merely for illustrative purposes of the principles of the present invention. For those skilled in the art, various modifications and adjustments of the present invention will be obvious without departing from the spirit and scope of the present invention.

Claims

1. A method for removing CO2 from an exhaust gas stream, comprising: Passing the exhaust gas stream generated from a point source through at least one adsorption bed formed by a monolithic structure adsorber, the monolithic structure adsorber including an outer peripheral wall and a plurality of internal partition walls, the internal partition walls carrying an organic compound or an inorganic compound for adsorbing CO2 from the exhaust gas stream, wherein the inlet temperature of the exhaust gas stream is at least 60 °C, the CO2 content is 3% to 20%, and the water vapor content is 2% to 22%; Isolating the adsorption bed from the exhaust gas stream; Passing steam at a pressure of -2 psig to 2 psig and a maximum temperature of 120 °C through the monolithic structure adsorber in a direction opposite to the flow direction of the exhaust gas stream to desorb the CO2 captured by the adsorption bed by providing the enthalpy for CO2 desorption; Condensing a first portion of the steam in the pores of the monolithic structure adsorber; Purging the desorbed CO2 from the adsorption bed with a second portion of the steam to obtain a mixture of the desorbed CO2 and the purge steam; Separating the desorbed CO2 from the mixture to obtain a product gas having at least 90 wt.% of CO2; and Stopping the isolation of the adsorption bed from the exhaust gas stream, wherein the exhaust gas stream re-enters the monolithic structure adsorber to evaporate at least a portion of the first portion of the steam condensed in the pores and cool the adsorber to a temperature below 90 °C to start a new adsorption cycle.

2. The method according to claim 1, wherein the at least one adsorption bed includes a first adsorption bed for removing CO2 from the exhaust gas stream, while a second adsorption bed is simultaneously isolated from the exhaust gas stream and desorbs the CO2 captured by the monolithic structure adsorber.

3. The method according to claim 1, wherein at least 1% of the CO2 captured from the exhaust gas stream remains on the monolithic structure adsorber after desorption and before stopping the isolation of the adsorption bed from the exhaust gas stream.

4. The method according to claim 3, wherein at least 1% to 10% of the CO2 captured from the exhaust gas stream remains on the monolithic structure adsorber after desorption and before stopping the isolation of the adsorption bed from the exhaust gas stream.

5. The method according to claim 3, wherein the organic compound is present on the monolithic structure adsorber and contains an amine functional group.

6. The method according to claim 5, wherein the organic compound includes a polyalkyleneimine.

7. The method according to claim 6, wherein the polyalkyleneimine is a polyethyleneimine.

8. The method according to claim 5, wherein during the adsorption of CO2 from the exhaust gas stream, the change in the ammonia concentration in the exhaust gas stream from the inlet to the outlet of the adsorption bed is less than an average value of 2 ppm.

9. The method according to claim 1, further comprising placing at least one filter upstream of the adsorption bed, the filter removing at least 50% of the particles having a size of 0.3 μm or larger.

10. The method according to claim 1, further comprising installing a condensation heat exchanger downstream of the adsorption bed, wherein the condensation heat exchanger recovers at least 2% of the water vapor in the exhaust gas stream generated by the combustion process.

11. The method according to claim 1 further includes installing a condensation heat exchanger downstream of the adsorption bed to recover the steam condensed in the adsorption bed during the desorption process, wherein the total amount of water recovered from the condensation heat exchanger plus the amount removed during the separation of the CO2 product generated from the desorption is equal to at least 90% of the steam introduced into the adsorption bed during the desorption process.

12. The method according to claim 1, wherein the monolithic structure adsorber has a mesopore porosity of at least 0.05 cc / g in pores with a diameter of 20 angstroms to 500 angstroms.

Images