Selective Capture Of Carbon Dioxide Research Articles

Bimetallic Copper-Cerium-Based Metal-Organic Frameworks for Selective Carbon Dioxide Capture.

Metal-organic frameworks (MOFs) are highly regarded as valuable adsorbent materials in materials science, particularly in the field of CO2 capture. While numerous single-metal-based MOFs have demonstrated exceptional CO2 adsorption capabilities, recent advancements have explored the potential of bimetallic MOFs for enhanced performance. In this study, a CuCe-BTC MOF was synthesized through a straightforward hydrothermal method, and its improved properties, such as high surface area, smaller pore size, and larger pore volume, were compared with those of the bare Ce-BTC. The impact of the Cu/Ce ratio (1:4, 1:2, 1:1, and 3:2) was systematically investigated to understand how adding a second metal influences the CO2 adsorption performance of the Ce-BTC MOF. Various characterization techniques, including scanning electron microscopy, transmission electron microscopy, powder X-ray diffraction, thermogravimetric analysis, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and N2 BET surface area analysis, were employed to assess the physical and chemical properties of the bare Ce-BTC and CuCe-BTC samples. Notably, CuCe-BTC-1:2 exhibited superior surface area (133 m2 g-1), small pore size (3.3 nm), and large pore volume (0.14 cm3 g-1) compared to the monometallic Ce-BTC. Furthermore, CuCe-BTC-1:2 demonstrated a superior CO2 adsorption capacity (0.74 mmol g-1), long-term stability, and good CO2/N2 selectivity. This research provides valuable insights into the design of metal-BTC frameworks and elucidates how introducing a second metal enhances the properties of the monometallic Ce-BTC-MOF, leading to improved CO2 capture performance.

Selective Carbon Dioxide Capture and Ultrahigh Iodine Uptake by Tetraphenylethylene-Functionalized Nitrogen-Rich Porous Organic Polymers

Selective Carbon Dioxide Capture and Ultrahigh Iodine Uptake by Tetraphenylethylene-Functionalized Nitrogen-Rich Porous Organic Polymers

Design and Synthesis of N-Doped Porous Carbons for the Selective Carbon Dioxide Capture under Humid Flue Gas Conditions.

The design of novel porous solid sorbents for carbon dioxide capture is critical in developing carbon capture and storage technology (CCS). We have synthesized a series of nitrogen-rich porous organic polymers (POPs) from crosslinking melamine and pyrrole monomers. The final polymer's nitrogen content was tuned by varying the melamine ratio compared to pyrrole. The resulting polymers were then pyrolyzed at 700 °C and 900 °C to produce high surface area nitrogen-doped porous carbons (NPCs) with different N/C ratios. The resulting NPCs showed good BET surface areas reaching 900 m2 g-1. Owing to the nitrogen-enriched skeleton and the micropore nature of the prepared NPCs, they exhibited CO2 uptake capacities as high as 60 cm3 g-1 at 273 K and 1 bar with significant CO2/N2 selectivity. The materials showed excellent and stable performance over five adsorption/desorption cycles in the dynamic separation of the ternary mixture of N2/CO2/H2O. The method developed in this work and the synthesized NPCs' performance towards CO2 capture highlight the unique properties of POPs as precursors for synthesizing nitrogen-doped porous carbons with a high nitrogen content and high yield.

Azo-Linked Porous Organic Polymers for Selective Carbon Dioxide Capture and Metal Ion Removal

The facile and environmentally friendly synthesis of porous organic polymers with designed polar functionalities decorating the interior frameworks as an excellent adsorbent for selective carbon dioxide capture and metal ion removal is a target worth pursuing for environmental applications. In this regard, two azo-linked porous organic polymers denoted man-Azo-P1 and man-Azo-P2 were synthesized in water by the azo-linking of 4,4′-diaminobiphenyl (benzidine) and 4,4′-methylenedianiline, respectively, with 1,3,5-trihydroxybenzene. The resulting polymers showed good BET surface areas of 290 and 78 m2 g–1 for man-Azo-P1 and man-Azo-P2, respectively. Due to the enriched core functionality of the azo (−N=N−) and hydroxyl groups along with the porous frameworks, man-Azo-P1 exhibited a good CO2 uptake capacity of 32 cm3 g–1 at 273 K and 1 bar, in addition to the remarkable removal of lead (Pd), chromium (Cr), arsenic (As), nickel (Ni), copper (Cu), and mercury (Hg) ions. This performance of the synthesized man-Azo-P1 and man-Azo-P2 in the dual application of CO2 capture and heavy metal ion removal highlights the unique properties of azo-linked POPs as excellent and stable sorbent materials for the current challenging environmental applications.

Wet flue gas CO2 capture and utilization using one-dimensional metal-organic chains.

Herein, we describe the use of an ultramicroporous metal-organic framework (MOF) with a composition of [Ni3(pzdc)2(ade)2(H2O)1.5]·(H2O)1.3 (pzdc: 3,5-pyrazole dicarboxylic acid; ade: adenine), for the selective capture of carbon dioxide (CO2) from wet flue gas followed by its conversion to value-added products. This MOF is comprised of one-dimensional Ni(II)-pyrazole dicarboxylate-adenine chains; through pi-pi stacking and H-bonding interactions, these one-dimensional chains stack into a three-dimensional supramolecular structure with a one-dimensional pore network. Upon heating, our MOF undergoes a color change from light blue to lavender, indicating a change in the coordination geometry of Ni(II). Variable temperature ultraviolet-visible (UV/vis) spectroscopy data revealed a blue shift of the d-d transitions, suggesting a change in the Ni-coordination geometry from octahedral to a mixture of square planar and square pyramidal. The removal of the water molecules coordinated to Ni(II) leads to the generation of a MOF with open Ni(II) sites. Nitrogen isotherms collected at 77 K and 1 bar revealed that this MOF is microporous with a pore volume of 0.130 cm3 g-1. Carbon dioxide isotherms show a step in the uptake at low pressure, after which the CO2 uptake is saturated. The step in the CO2 uptake is likely attributable to the rearrangement of the three-dimensional supramolecular structure to accommodate CO2 within its pores. The affinity of this MOF for CO2 is 35.5 kJ mol-1 at low loadings, and it increases to 41.9 kJ mol-1 at high loadings. While our MOF is porous to CO2 and water (H2O) at 298 K, it is not porous to N2, and the CO2/N2 selectivity increases from 28.5 to 31.5 as a function of pressure. Breakthrough experiments reveal that this MOF can capture CO2 from dry and wet flue gas with uptake capacities of 1.48 ± 0.01 and 1.14 ± 0.06 mmol g-1, respectively. The MOF can be regenerated and reused at least three times, demonstrating consistent CO2 uptake capacities. Upon understanding the sorption behavior of this MOF, catalysis experiments show that the MOF is catalytically active in the fixation of CO2 into an epoxide ring for the formation of a cyclic carbonate. The turnover frequency for this reaction is 21.95 ± 0.03 h-1. The MOF showed no catalytic deterioration after two cycles and maintained comparable catalytic activity when dry and wet CO2/N2 mixtures were used. This highlights that both N2 and H2O do not dramatically affect the catalytic activity of our MOF toward CO2 fixation.

Evaluation of thermal effects on carbon dioxide breakthrough curve for biogas upgrading using pressure swing adsorption

Selective carbon dioxide capture using pressure swing adsorption can transform raw biogas into high energy content biomethane and subsequently sequestration of CO2. In this work, the PSA technology for biogas upgrading is modelled and evaluated using one-dimensional binary mixture adsorption, heat and mass transfer model using Aspen Adsorption™ version 10. This model is validated using experimental data reported previously on zeolite NaUSY, since the CO2 breakthrough curve depicts reasonable agreement. This work considers two heat transfer conditions (gas and gas/solid conductions) to compare their effects on CO2 breakthrough and temperature responses at different positions along the adsorption bed. Three different biogas mixtures are charged over zeolite NaUSY bed to evaluate CO2 concentration on breakthrough curve and bed temperature profile. The influence of axial mass dispersion coefficient on breakthrough characteristics and temperature distribution along adsorption bed is examined. In addition, the effects of cooling outside column wall on CO2 breakthrough curve and bed temperature distribution is also explored. The findings indicate that the heat generated during adsorption possesses influences the adsorption performance rather significantly. Reducing this heat restrains the thermal effects on the breakthrough curves, thereby improving the methane purity and recovery.

Selective capture of carbon dioxide from humid gases over a wide temperature range using a robust metal–organic framework

Physisorption presents as a promising energy-saving technique for carbon dioxide (CO2) sequestration, which is crucial for processing various industrially important gases (e.g. natural gas and flue gas). However, to target desirable porous materials that simultaneously combine high CO2 selectivity and moderate adsorption enthalpy especially under humid and wide-temperature environment is challenging. Herein, we report the capture of CO2 from humid gas with a novel ultramicroporous metal–organic framework ZU-301 that features one-dimensional robust pore channel decorated by high-density oxalate anions and hydrophobic methyls. The rigid framework coupled with fine-tuned aperture size permits CO2 trapping while sets a barrier for CH4, leading to excellent separation selectivity (90–111) in a wide temperature range (298–323 K). The introduced oxalate anions and methyls synergistically grasp CO2via mild interactions, giving rise to moderate adsorption enthalpy (38 kJ mol−1), as evidenced by single-crystal X-ray diffraction analysis performed on CO2-loaded ZU-301, meanwhile render ZU-301 low affinity to moisture with the CO2/H2O uptake ratio outperforming many benchmark materials. Additionally, ZU-301 exhibits good chemical stability, which even can be soaked in strong acid or base solutions (pH = 2–12) without losing CO2 capture ability. Breakthrough experiments confirmed the high efficiency of ZU-301 for CO2/CH4 and CO2/N2 separation under elevated temperature and humid conditions, which is of important scientific and industrial value.

Capsules of Reactive Ionic Liquids for Selective Capture of Carbon Dioxide at Low Concentrations.

The task-specific ionic liquid (IL), 1-ethyl-3-methylimidazolium 2-cyanopyrolide ([EMIM][2-CNpyr]), was encapsulated with polyurea (PU) and graphene oxide (GO) sheets via a one-pot Pickering emulsion, and these capsules were used to scrub CO2 (0-5000 ppm) from moist air. Up to 60 wt % of IL was achieved in the synthesized capsules, and we demonstrated comparable gravimetric CO2 capacities to zeolites and enhanced absorption rates compared to those of bulk IL due to the increased gas/liquid surface-to-volume area. The reactive IL capsules show recyclability upon mild temperature increase compared to zeolites that are the conventional absorber materials for CO2 scrubbing. The measured breakthrough curves in a fixed bed under 100% relative humidity establish the utility of reactive IL capsules as moisture-stable scrubber materials to separate CO2 from air, outperforming zeolites owing to their higher selectivity. It is shown that thermal stability, CO2 absorption capacity, and rate of uptake by IL capsules can be further modulated by incorporating low-viscosity and nonreactive ILs to the capsule core. This study demonstrates an alternative and facile approach for CO2 scrubbing, where separation from gas mixtures with extremely low partial pressures of CO2 is required.

Constructing Hierarchical Porous Carbons With Interconnected Micro-mesopores for Enhanced CO2 Adsorption.

A high cost-performance carbon dioxide sorbent based on hierarchical porous carbons (HPCs) was easily prepared by carbonization of raw sugar using commercially available nano-CaCO3 as a double-acting template. The effects of the initial composition and carbonization temperature on the micro-mesoporous structure and adsorption performance were examined. Also, the importance of post-activation behavior in the development of micropores and synthesis route for the formation of the interconnected micro-mesoporous structure were investigated. The results revealed excellent carbon dioxide uptake reaching up 2.84 mmol/g (25oC, 1 bar), with micropore surface area of 786 m2/g, micropore volume of 0.320 cm3/g and mesopore volume of 0.233 cm3/g. We found that high carbon dioxide uptake was ascribed to the developed micropores and interconnected micro-mesoporous structure. As an expectation, the optimized HPCs offers a promising new support for the high selective capture of carbon dioxide in the future.

Adsorption-induced clustering of CO2 on graphene.

Utilization of graphene-based materials for selective carbon dioxide capture has been demonstrated recently as a promising technological approach. In this study we report results from density functional theory calculations and molecular dynamics simulations on the adsorption of CO2, N2, and CH4 gases on a graphene sheet. We calculate adsorption isotherms of ternary and binary mixtures of these gases and reproduce the larger selectivity of CO2 to graphene relative to the other two gases. Furthermore it is shown that the confinement to two-dimensions, associated with adsorbing the CO2 gas molecules on the plane of graphene, increases their propensity to form clusters on the surface. Above a critical surface coverage (or partial pressure) of the gas, these CO2-CO2 interactions augment the effective adsorption energy to graphene, and, in part, contribute to the high selectivity of carbon dioxide with respect to nitrogen and methane. The origin of the attractive interaction between the CO2 molecules adsorbed on the surface is of electric quadrupole-quadrupole nature, in which the positively-charged carbon of one molecule interacts with the negatively-charged oxygen of another molecule. The energy of attraction of forming a CO2 dimer is predicted to be around 5-6 kJ mol-1, much higher than the corresponding values calculated for N2 and CH4. We also evaluated the adsorption energies of these gases to a graphene sheet and found that the attractions obtained using the classical force-fields might be over-exaggerated. Nevertheless, even when the magnitudes of these (classical force-field) graphene-gas interactions are scaled-down sufficiently, the tendency of CO2 molecules to cluster on the surface is still observed.

Bio-based Micro-/Meso-/Macroporous Hybrid Foams with Ultrahigh Zeolite Loadings for Selective Capture of Carbon Dioxide.

Microporous (<2 nm) crystalline aluminosilicates in the form of zeolites offer a great potential as efficient adsorbents for atmospheric CO2 in the eminent battle against global warming and climate change. The processability of conventional zeolite powders is, however, poor, which limits their implementation in many applications, such as in gas filtration industrial systems. In this work, we overcome this issue through the preparation of hybrid foams using mesoporous/macroporous supporting materials based on the strong network properties of gelatin/nanocellulose, which can support ultrahigh loadings of silicalite-1, used as a model sorbent nanomaterial. We achieved up to 90 wt % of zeolite content and a microporous/mesoporous/macroporous hybrid material. The application of hybrid foams for selective CO2 sorption exhibits a linear relationship between the zeolite content and CO2 adsorption capacity and high selectivity over N2, where the gelatin/nanocellulose foam efficiently supports the zeolite crystals without apparently blocking their pores.

Selective Carbon Dioxide Capture in Antifouling Indole-based Microporous Organic Polymers

Intermolecular synergistic adsorption of indole and carbonyl groups induced by intermolecular hydrogen bonding makes microporous organic polymer (PTICBL) exhibit high CO2 uptake capacity (5.3 mmol·g−1 at 273 K) and selectivities (CO2/CH4 = 53, CO2/N2 = 107 at 273 K). In addition, we find that indole units in the PTICBL networks inhibit the attachment of bacteria (E. coil and S. aureus) on the surface of PTICBL and extend its service life in CO2 capture.

Recent advances in carbon-based renewable adsorbent for selective carbon dioxide capture and separation-A review

Abstract In terms of net intensification in the greenhouse effect ie., rise of global temperature which has triggered melting of glacier thus increasing sea level and acidification of sea, carbon dioxide alone contributes approximately three-fourth of the net greenhouse radiative forcing by man-made (anthropogenic) greenhouse gases emissions. Carbon dioxide capture and storage (CCS) technology; a promising strategy for capturing of carbon dioxide from point sources before its release to atmosphere by using various sorbents is gaining global interest. In this study, the established carbon capture technologies with methods of carbon dioxide separation along there pros and cons are discussed. Carbon-based adsorbents are considered as the most versatile adsorbents for carbon dioxide due to their extraordinary physical and chemical properties. In this manuscript, recent developments on carbonaceous adsorbents (biochar, activated carbons, and graphene-based adsorbents) and their role in carbon dioxide capture during different combustion processes and conditions have been comprehensively focused.

Highly Selective Carbon Dioxide Capture and Cooperative Catalysis of a Water‐Stable Acylamide‐Functionalized Metal–Organic Framework

Incorporation of specific functionalities within the framework offers a significant opportunity to produce high‐performance gas storage/separation and catalysis MOF materials. In this work, multifunctionalities, including hydrophobic methoxy groups, polar acylamide functionalities, and open copper(II) sites, have been successfully integrated into a twofold interpenetrated microporous MOF (HNUST‐6, HNUST represents Hunan University of Science and Technology). HNUST‐6 possesses permanent porosity, with a moderate BET surface area of 1093 m2 g–1 and high CO2 adsorption capacity (111 cm3 g–1 at 1 bar), with good selectivity for CO2 over CH4 (6.6) and N2 (30.3) at 273 K. Remarkably, this MOF material exhibits excellent water stability and its framework structure is retained after being immersed in boiling water. In addition, HNUST‐6 demonstrates efficient catalytic activity as a cooperative catalyst in a tandem one‐pot deacetalization Knoevenagel condensation reaction.

High and Selective Carbon Dioxide Capture in Nitrogen-Containing Aerogels via Synergistic Effects of Electrostatic In-Plane and Dispersive π-π-Stacking Interactions.

A new strategy for CO2 capture is reported based on the synergistic effect of electrostatic in-plane and dispersive π-π-stacking interactions of amide and indole with CO2. Density functional theory illustrated that the amide group can have an increased ability to capture CO2 molecules that were just desorbed from an adjacent indole unit. We used this strategy to fabricate a microporous aerogel that exhibited a superior CO2 capture performance in both dry and wet conditions. The proposed synergistic effect is expected to be a new rationale for the design of CO2 capture materials.

High-throughput screening of metal-porphyrin-like graphenes for selective capture of carbon dioxide.

Nanostructured materials, such as zeolites and metal-organic frameworks, have been considered to capture CO2. However, their application has been limited largely because they exhibit poor selectivity for flue gases and low capture capacity under low pressures. We perform a high-throughput screening for selective CO2 capture from flue gases by using first principles thermodynamics. We find that elements with empty d orbitals selectively attract CO2 from gaseous mixtures under low CO2 pressures (~10−3 bar) at 300 K and release it at ~450 K. CO2 binding to elements involves hybridization of the metal d orbitals with the CO2 π orbitals and CO2-transition metal complexes were observed in experiments. This result allows us to perform high-throughput screening to discover novel promising CO2 capture materials with empty d orbitals (e.g., Sc– or V–porphyrin-like graphene) and predict their capture performance under various conditions. Moreover, these findings provide physical insights into selective CO2 capture and open a new path to explore CO2 capture materials.

Preparation of mannitol-based ketal-linked porous organic polymers and their application for selective capture of carbon dioxide

Four kinds of mannitol-based ketal-linked porous organic polymers (MKPOPs) were successfully synthesized through condensation reaction between aromatic acetyl monomers and mannitol, catalyzed by p-toluenesulfonic acid. The structure of resulting polymers was confirmed by Fourier transform infrared and solid-state 13C nuclear magnetic resonance spectrum measurements. The porosities of MKPOPs were investigated by gas adsorption experiments and the results indicate high carbon dioxide uptake (up to 11.5 wt% at 273 K and 1.0 bar) for MKPOPs due to the predominant microporous and hydroxyl-rich structures. Remarkably, MKPOPs exhibit excellent selective adsorption performances for carbon dioxide over methane (9.9–14.2, IAST at 273 K and 1.0 bar). These studies are of significant importance for MKPOPs and their potential application in selective gas adsorption.

Calcium-decorated carbon nanostructures for the selective capture of carbon dioxide.

The development of advanced materials for CO2 capture is of great importance for mitigating climate change. In this paper, we outline our discovery that calcium-decorated carbon nanostructures, i.e., zigzag graphene nanoribbons (ZGNRs), carbyne, and graphyne, have great potential for selective CO2 capture, as demonstrated via first-principles calculations. Our findings show that Ca-decorated ZGNRs can bind up to three CO2 molecules at each Ca atom site with an adsorption energy of ∼-0.8 eV per CO2, making them suitable for reversible CO2 capture. They adsorb CO2 molecules preferentially, compared with other gas molecules such as H2, N2, and CH4. Moreover, based on equilibrium thermodynamical simulations, we confirm that Ca-decorated ZGNRs can capture CO2 selectively from a gas mixture with a capacity of ∼4.5 mmol g-1 under ambient conditions. Similar results have been found in other carbon nanomaterials, indicating the generality of carbon based nanostructures for selective CO2 capture under ambient conditions.

The role of the internal molecular free volume in defining organic porous copolymer properties: tunable porosity and highly selective CO₂ adsorption.

A series of novel azo-functionalized copolymerized networks (simply known as NOP-34 series) with tunable permanent microporosity and highly selective carbon dioxide capture are disclosed. The synthesis was accomplished by Zn-induced reductive cross-coupling copolymerization of two nitrobenzene-like building blocks with different 'internal molecular free volumes' (IMFVs), i.e., 2,7,14-trinitrotriptycene and 2,2',7,7'-tetranitro-9,9'-spirobifluorene, with different molar ratios. Increasing the content of spirobifluorene (SBF) segments with a smaller IMFV relative to that of triptycene leads to an unconventional rise-fall pattern in porosity. Unlike most reported porous copolymers whose surface area lies between the corresponding homopolymers, the copolymer NOP-34@7030 with 30% SBF segments unprecedentedly shows the largest Brunauer-Emmett-Teller specific surface area (up to 823 m(2) g(-1)) as well as promoted CO2 uptake abilities (from 2.31 to 3.22 mmol g(-1), at 273 K/1.0 bar). The 100% triptycene(TPC)-derived homopolymer (NOP-34@1000) with a moderate surface area shows the highest CO2/N2 IAST selectivity of 109 (273 K) among the five samples, surpassing most known nanoporous organic polymers. This may contribute significantly to our understanding of the relationship of IMFVs with the properties of copolymerized materials.

Mannitol-based acetal-linked porous organic polymers for selective capture of carbon dioxide over methane

Synthesis of mannitol-based acetal-linked porous organic polymers with considerable CO2/CH4 selectivity is reported.