Compositions, Systems, and Methods for Sequestering CO2 from Combustion Flue Gas

Systems for recovering CO2 from a combustion gas stream are provided. Compositions are also provided; the compositions can include: a nanoporous framework composition; a ligand associated with the nanoporous framework composition; and CO2 associated with the one or both of the ligand and the nanoporous framework composition. Methods for separating CO2 from a combustion stream are also provided.

TECHNICAL FIELD

The field of the invention relates to the processing of building emissions that can include carbon dioxide management systems and methods, and more particularly, be utilized by multi-use or large footprint buildings that utilize large combustion energy sources for building systems such as steam heating, hot water, sorbent cooling, and combined heat and power with byproduct generation of emissions in the form of combustion streams.

BACKGROUND

Carbon dioxide generation in buildings, particularly in large metropolitan areas and/or industrial settings, is a significant contributor to carbon dioxide generation overall. Carbon dioxide is currently listed as a global warming compound whose reduction is sought worldwide. The generation of carbon dioxide is a necessary part of respiration, which is a necessary part of life, but it is important to limit the generation of carbon dioxide in an effort to address climate change. The present disclosure provides building emission processing and sequestration systems that can address carbon dioxide generation from combustion of fossil fuels and proliferation thereof in metropolitan areas.

SUMMARY

Systems for recovering CO2from a combustion gas stream are provided; the systems can include: a combustion stream having CO2and N2; a vessel operatively coupled to the combustion stream, with the vessel containing a nanoporous framework composition associated with a ligand; and a vessel outlet stream operatively engaged with the vessel.

Compositions also provided; the compositions can include: a nanoporous framework composition; a ligand associated with the nanoporous framework composition; and CO2associated with the one or both of the ligand and the nanoporous framework composition.

Methods for separating CO2from combustion streams are also provided. The methods can include: charging a vessel containing a nanoporous framework composition with components of a combustion stream, at least two of the components comprising CO2and N2; discharging in the first of at least two steps, at least some of the N2while retaining CO2associated with the metal organic composition; and discharging in a second of the at least two steps, at least some of the retained CO2to provide a stream of CO2substantially free of N2.

Systems for recovering CO2from a combustion gas stream are also provided that can include: a combustion stream comprising CO2and N2; a vessel operatively coupled to the combustion stream, the vessel containing material comprising one or more of activated carbons, carbon molecular sieves, carbon nanotubes, natural and synthetic zeolites (i.e., alkali metal aluminosilicates), aluminophosphate materials, and/or mesoporous silica; and a vessel outlet stream operatively engaged with the vessel.

Methods for separating CO2from a combustion stream are also provided that can include: charging a vessel with components of a combustion stream, at least two of the components comprising CO2and N2; and the vessel containing an adsorbent material comprising one or more of activated carbons, carbon molecular sieves, carbon nanotubes, natural and synthetic zeolites (i.e., alkali metal aluminosilicates), aluminophosphate materials, mesoporous silica or nanoporous framework composition; discharging in the first of at least two steps, at least some of the N2while retaining CO2associated with the chosen adsorbent; and discharging in a second of the at least two steps, at least some of the retained CO2to a provide a stream of CO2substantially free of N2.

DESCRIPTION

The present disclosure will be described with reference toFIGS.1-5. Referring first toFIG.1, a system10is depicted that includes three components, a dryer component14, a separator18, and a liquefier component22. In accordance with example implementations, system10can be configured to receive a gas combustion product12that can be a flue gas or combustion stream from an industrial and/or residential building, for example. In accordance with example implementations, this stream12can include nitrogen and carbon dioxide, and at this point can be what is considered minimally wet and in need of final drying. The stream can also include O2.

In accordance with example implementations, dryer14can be utilized to dry the combustion gas12, reducing the water content. In at least one configuration, the combustion product12, for final drying can be less than 0.1% water. In accordance with another example configuration, the dryer can be configured to receive a stream24that comprises at least some nitrogen that can be recovered from separator18. In accordance with example configurations, dryer14can be operatively engaged with the nitrogen feed to be configured to regenerate desiccant within the dryer. Typically, the dryer can be a two-chamber cycle device, wherein one chamber is drying while the other chamber is re-generating for drying, and those cycles can run continuously. In accordance with example implementations, the nitrogen used to dry the desiccant after the desiccant is exhausted (no longer removing water) in the process of regenerating the desiccant can be provided from the separator18. Upon drying, the dried combustion product can include primarily nitrogen, oxygen, and carbon dioxide, and less than about 10 ppm water before being provided to separator18.

Separator18can be a Pressure Swing Adsorption assembly that includes an adsorbent within a vessel of the Pressure Swing Adsorption assembly. Other swing adsorptions can include vacuum pressure swing adsorption (VPSA), temperature swing adsorption (TSA), and/or electrical swing adsorption (ESA) assemblies, or any combination thereof. Typically, the adsorption assembly includes one or more vessels containing shaped solid phase adsorbent materials coupled and/or configured to work in concert to separate the carbon dioxide of incoming stream16from the nitrogen of the incoming stream16. Adsorption materials can be characterized by breakthrough response as a function of time and/or with isotherm (constant temperature) curves which indicate capacity as a function of pressure. These characteristics can be used to determine material working capacity when configuring process step cycles. Adsorbent materials with high CO2capacity and high selectivity of CO2with respect to nitrogen and oxygen can be preferred.

Systems and/or methods can utilize adsorbent materials such as one or more of the following: activated carbons, carbon molecular sieves, natural and synthetic zeolites (i.e., alkali metal aluminosilicates), aluminophosphate materials, nanoporous framework compositions such as Metal Organic Framework structures (MOF's), and Covalent Organic Framework structures (COF's) and/or mesoporous silica with self-assembled ligands. Nanoporous framework compositions can include at least two classes of materials: 1. Metal Organic Framework (MOF's) containing polynuclear metal clusters bonded to Organic linkers; and 2. Covalent Organic Frameworks (COF's) containing polynuclear non-metal clusters bonded to organic linkers. Polynuclear clusters can be referred to as secondary building units (SBU's) which impart structure and rigidity to the framework material. Nanoporous Framework compositions can be further functionalized with specialized ligands associated with the clusters and/or linkers.

Carbonaceous adsorbents are available, low cost, have high thermal stability, and low sensitivity to moisture. These materials can be enhanced to improve surface area and pore structure, include amine compound functionalization, and/or amine compound impregnation.

Zeolite adsorbents can be low cost, have high thermal stability, and can have characteristics of exchange cations. These materials can be enhanced to improve Al/Si composition ratios and/or exchange with alkali and alkaline earth cations. CO2has a high linear quadrupole moment which interacts with intra-zeolite cations.

Mesoporous Silica can have high surface area, high pore volume, tunable pore size, and good thermal and mechanical stability. These materials can be enhanced to provide new families such as SBA-n and ABS, altered to include amine compound loading, and/or self-assembly of amine functionalized components into larger pore structures.

Metal Organic Frameworks (MOF's) and Covalent Organic Frameworks (COF's) can have high surface areas, controllable pore structures and/or pore surface properties. These materials can be constructed to provide new types of MOF's and COF's, reduce cost of synthesis and production, and/or improve stability towards water vapor.

In addition, all materials can be evaluated for specific functionalization such as chemical attachment and/or self-assembly of amine adorned ligands, and control of aluminum to silicon ratios in synthesized zeolites.

Additionally, one or more of these adsorbent materials can be performance enhanced. Particular materials, including enhanced materials, can lower the pressure or temperature required for PSA and TSA assemblies thus providing a system that requires less energy to operate. For example, mesoporous silica can be enhanced to include self-assembled functionalized amine ligands. Accordingly, synthetic porous materials can be modified for enhanced CO2working capacity and selectivity through one or more of the following changes:a. Modification of the SI/AL ratio in Zeolite structures.b. Selection of various metal cations in Zeolites.c. Impregnation of Amine compounds within pores and cages.d. Chemical attachment of amine ligands to surface features.e. Self-assembly of amine ligands within pores (mesoporous silica).

An example adsorbent configuration is provided that includes an example synthetic zeolites (i.e. alkali metal aluminosilicates)40as shown inFIG.2A, with cage structures42as shown inFIG.2Bthat could include amine functionality44. Ligands can be attached to adsorbent surfaces, to pore fringes, or assembled within larger pores as in the case of mesoporous silica, for example. Examples of ligands with this amine functionality are given inFIGS.2C-E. An example pore or cage impregnation compound is polyethylenimine (PEI) is shown inFIG.2F. As can be seen, this amine functionality can extend to within the openings of the porous material, and this amine functionality can enhance the selectivity of trapping or retention of carbon dioxide in preference to or rather than nitrogen. Utilizing cyclic sorption and desorption in combination with weak molecular attractions, separation of CO2 and N2 can be achieved.

Referring toFIGS.3,4A, and4B, nanoporous framework compositions are shown. These compositions can include metal organic compositions and/or structures for use as adsorbents within separation vessel(s). The nanoporous framework composition60can be configured as a metal organic framework or as a covalent organic framework. The nanoporous framework composition can include both clusters62and linkers64. The clusters can include metals. The clusters can be considered secondary building units (SBU's) comprising poly-nuclear clusters62coupled by organic linkers64. The SBU clusters can include either metal or non-metal elements68, and provide structural rigidity to the framework.

As shown, composition60can include ligands66associated with one or both of clusters62and linkers64. Ligand66can include at least one —NH— (i.e., amine) moiety70. For example, ligand66can be CH3NHCH2CH2NHCH3(dimethylethylenediamine). In accordance with example implementations, the lone pairs of the —NH— moiety can be associated with at least one of the metals68of nanoporous framework composition60.

InFIG.4B, for example, the MOF can define one-dimensional channels with approximate dimensions of 3.6×7.6 Å2throughout the framework. Pairs of ligands (Haip) can be connected by strong hydrogen bonds. Adsorption sites for CO2molecules are provided for in the pores of the MOF.

MOF materials can be prepared from inexpensive precursors; for example from isophthalic acid and its derivatives. The MOF can be built up from cobalt(II) ions and 5-aminoisophthalic acid by combining 5-aminoisophthalic acid (H2aip) linker, with cobalt(II) salts in methanol to form [Co(Haip)2].

The MOF material can crystalize in a monoclinic system with the I2/a space group. The framework can be of M(II) ions with an octahedral geometry lined up into a 1D chain. Adjacent chains can be pillared into two-dimensional (2D) sheets by the Haip ligands. The deprotonated carboxyl group of each Haip ligand can be coordinated to the cobalt ion, while the other engages in hydrogen bonding with a neighboring carboxyl group. This hydrogen-bonding array can connect the sheets in a three-dimensional (3D) supramolecular open framework featuring one-dimensional channels.

Referring next toFIG.5, an example gas separation vessel bed layout is shown wherein stream16is entering the lower portion of the vessel30that includes sidewalls32, and within vessel30can be a guard bed33which can include a layer of activated alumina configured to trap any remaining water vapor entering the system.

This guard bed can be about 8 inches in depth, which is underneath in relation to approximately a 49-inch layer of adsorbent34. In accordance with example implementations, a top layer35above the adsorbent layer34can be provided that includes bed support media (ie. ¼″ Denstone beads) which can facilitate prevention of fluidization of the bed during operation. In accordance with example implementations, the vessel30can be configured to house at least 3 layers of material, a bottom layer33, an adsorbent layer34, and a top layer35, with appropriately sized screen separators. In accordance with example implementations, the ratio of the depths of these layers can range from 8 inches of the bottom layer, 49 inches of the adsorbent layer, and 6.5 inches of the top layer.

In accordance with at least one particular implementation, 13X APG III adsorbent or JLPM3 adsorbent can be utilized in a multiple vessel (i.e., nine or twelve) vacuum pressure swing adsorption (VPSA) system with the vessel bed fill shown inFIG.5. Three layers of functional material are shown. Accordingly, the bottom layer in each vessel can include activated alumina configured to capture any trace water vapor in the mixed gas input stream. Following a screen separator, the second layer can be defined by 49 inches of 13X APG III (specialized sodium metal aluminosilicate), or JLPM3 adsorbent configured for CO2separation from N2. Following another screen separator, the top layer can be defined by 12 inches of bed support media (ie. Denstone) to prevent the bed from fluidizing. For all of these solid materials the optimum shapes (beads, rods, prills, etc.) and dimensions can be selected.

Stream16can be used to both charge and discharge vessel32and adsorbent34. In accordance with example implementations, vessel32and adsorbent34can be charged with components of the combustion stream. These gaseous components can include at least CO2and N2, but may also include O2, as well as H2O. Once charged, the material can be discharged in steps, and/or the discharge can be separated while monitoring discharge content. When charged, composition60can include CO2. The CO2can be associated with one or both of ligand66, metal68, cluster62, and/or linker64. In accordance with example configurations, CO2can be within porous openings72of a MOF or COF framework structure. For example, initial discharge will contain more N2than CO2as the CO2is retained by the adsorbent to greater extent than N2. This initial for first step discharge or waste stream can be provided for drying as discussed above, for example. Subsequent discharge will contain greater amounts of CO2, for example, relatively N2free CO2. Subsequent discharge or product stream obtained in the second step can be provided for liquefaction and/or storage. Multiple vessels have the same step cycle sequence adjusted in time relationship to provide continuous product separation.

In accordance with example implementations and with reference again toFIG.1, separator18can be configured to separate nitrogen from carbon dioxide, leaving a product stream20of substantially pure carbon dioxide that can range in purity from at least 90% but as high as 98% to 100% when utilizing aluminosilicates such as 13X APG, 13X APG III and/or JLPM3. In accordance with at least one example implementation, 13X APG III or JLPM3 adsorbent can be loaded in the VPSA system. This adsorbent can perform at approximately 1.7 times the capacity of industry standard 13X materials. The cyclic pressure (vacuum) swing working window can be positioned for optimum performance in accordance with inflection on adsorbent isotherm curves.

In accordance with the system ofFIG.1, CO2output purity can be consistently >95% and CO2recovery can be >85%. Heat of adsorption can be transferred primarily to the output waste nitrogen stream. Thus, dryer bed regeneration is enhanced with the higher temperature nitrogen (>90 deg. F.) slip stream. In addition, product CO2output temperature can be lower in temperature (<90 deg F.) which complements the downstream liquefaction process of cooling and compression.

In accordance with example implementations, utilizing this particular material can generate a warm or even hot nitrogen waste stream24that can be split off and partially provided to dryer14, which can enhance regeneration of desiccant dryer beds. Compressed nitrogen waste gas can also be expanded for energy recovery. In accordance with example configurations as well, this material has also been shown to provide substantially cooler or almost ambient temperature CO220to liquefier22which greatly lessens the energy required to condense the carbon dioxide to a liquid phase in liquefier22.

Systems and/or methods of the present disclosure can reduce carbon dioxide emissions into the atmosphere while producing a valuable product which can be sequestered in concrete (carbonates), utilized in production of carbon neutral fuels (eFuels), platform chemicals, support waste water treatment, and a variety of other beneficial applications.

In compliance with the statute, embodiments of the invention have been described in language more or less specific as to structural and methodical features. It is to be understood, however, that the entire invention is not limited to the specific features and/or embodiments shown and/or described, since the disclosed embodiments comprise forms of putting the invention into effect. The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims appropriately interpreted in accordance with the doctrine of equivalents.