CO2 Adsorption Properties Research Articles

Influence of Monomer Size on CO2 Adsorption and Mechanical Properties in Microporous Cyanate Ester Resins

Molecular simulations offer valuable insights into thermosetting polymers’ microstructures and interactions with small molecules, aiding in the development of advanced materials. In this study, we design two cyanate resin models featuring monomers of different sizes and employ a previously developed method to generate crosslinked structures. We then analyze their crosslinking processes and physicochemical properties. Using quantum chemistry calculations and a GCMC/MD approach, we investigate CO2 adsorption. Our results show that monomer size does not significantly affect the crosslinking process and provides a degree of polymerization as 83.8 ± 0.3% vs. 76.7 ± 1.4%, but it does influence key properties, such as the glass transition temperature (520 K vs. 420 K) and Young’s modulus (2.32 GPa vs. 1.77 GPa). Moreover, CO2 adsorption differs between the two models: the introduction of propyl ether moieties lowers by around 70% CO2 uptake, indicating that specific adsorption sites impact gas adsorption. This study demonstrates a promising strategy for designing and optimizing thermosetting polymers with controllable gas separation and storage capabilities.

Methanation of carbon dioxide over zirconium-tin oxide-based catalyst

An advanced catalyst, Ni/ZrSn[Formula: see text]Ce[Formula: see text]O4/[Formula: see text]-Al2O3, was synthesized for the methanation of CO2 under moderate conditions of atmospheric pressure and low H2 concentration (4 vol%). The use of scrutinyite-type ZrSn[Formula: see text]Ce[Formula: see text]O4 improved the catalytic activity, likely because of abundant oxygen vacancies for CO2 adsorption and good redox properties for cleavage of the C-O bond of adsorbed CO2. The CH4 yield of 18 wt.% Ni/20 wt.% ZrSn[Formula: see text]Ce[Formula: see text]O4/[Formula: see text]-Al2O3 reached 61.0% with high CO2 conversion (58.4%) at [Formula: see text]C using 1 vol% CO2-4vol% H2-95 vol% Ar at atmospheric pressure.

Enhanced CO2 adsorption properties with bimetallic ZnCe-MOF prepared using a microchannel reactor

Enhanced CO2 adsorption properties with bimetallic ZnCe-MOF prepared using a microchannel reactor

Structurally Asymmetric Ni−O−Mn Node in Metal–Organic Layers on Carbon Nitride Support for CO2 Photoreduction

AbstractThe Jahn–Teller (J–T) effect‐induced lattice distortion presents an advantageous approach to tailor the electronic structure and CO2 adsorption properties of catalytic centers, consequently conferring desirable photocatalytic CO2 reduction activity and selectivity. Nevertheless, achieving precise J–T distortion control over catalytic sites to enhance CO2 adsorption/activation and target‐product desorption remains a formidable challenge. In this work, we successfully induced J–T lattice distortion in neighboring Ni sites by exchanging high‐spin Mn2+ into Ni−O−Ni nodes. EXAFS results and DFT simulations revealed that the highly asymmetric Ni−O−Mn nodes induced structural contraction (shortened Ni−O bonds) in the adjacent Ni−O lattice. The magnetic hysteresis loop (M−H) confirmed that the introduction of Mn2+ increased the number of spin electrons, thereby increasing the magnetization intensity. The spin mismatch between photogenerated electrons and holes suppressed charge recombination. Significantly, the d orbitals of the Ni sites in the Ni−O−Mn nodes exhibited strong orbital hybridization with the p orbitals of CO2, as evidenced by the enhanced d‐p orbital overlap, facilitating rapid CO2 adsorption and activation. Consequently, the sample featuring lattice‐mismatched Ni−O−Mn nodes exhibited an 8.79‐fold enhancement in CO production rate compared to the Ni−O−Ni nodes, in the absence of cocatalysts and sacrificial reagents.

Structurally Asymmetric Ni-O-Mn Node in Metal-Organic Layers on Carbon Nitride Support for CO2 Photoreduction.

The Jahn-Teller (J-T) effect-induced lattice distortion presents an advantageous approach to tailor the electronic structure and CO2 adsorption properties of catalytic centers, consequently conferring desirable photocatalytic CO2 reduction activity and selectivity. Nevertheless, achieving precise J-T distortion control over catalytic sites to enhance CO2 adsorption/activation and target-product desorption remains a formidable challenge. In this work, we successfully induced J-T lattice distortion in neighboring Ni sites by exchanging high-spin Mn2+ into Ni-O-Ni nodes. EXAFS results and DFT simulations revealed that the highly asymmetric Ni-O-Mn nodes induced structural contraction (shortened Ni-O bonds) in the adjacent Ni-O lattice. The magnetic hysteresis loop (M-H) confirmed that the introduction of Mn2+ increased the number of spin electrons, thereby increasing the magnetization intensity. The spin mismatch between photogenerated electrons and holes suppressed charge recombination. Significantly, the d orbitals of the Ni sites in the Ni-O-Mn nodes exhibited strong orbital hybridization with the p orbitals of CO2, as evidenced by the enhanced d-p orbital overlap, facilitating rapid CO2 adsorption and activation. Consequently, the sample featuring lattice-mismatched Ni-O-Mn nodes exhibited an 8.79-fold enhancement in CO production rate compared to the Ni-O-Ni nodes, in the absence of cocatalysts and sacrificial reagents.

Scalable MOF-based mixed matrix membranes with enhanced permeation processes facilitate the scale application of membrane-based carbon capture technologies

Mixed-matrix membranes (MMMs) leverage the processability of polymers and selectivity of Metal-Organic Frameworks (MOFs). However, they still suffer from poor interfacial compatibility and limited scalability in preparation. In certain polymers, MOFs can bridge the pores within the polymer membrane, enhancing the CO2 adsorption and solubility properties, thus selectively boosting the CO2 permeability. In this study, high-performance MMMs were prepared using scalable CALF-20 in combination with PIM-1. MMMs with a 5% doping level achieved CO2 permeability up to 8003 barrer with 25% improvement in CO2/N2 selectivity. This enhancement was attributed to well-designed MMMs, where MOFs matched the abundant non-interconnecting pores in the PIM-1 membrane. This study represents a significant advancement towards scaling up the preparation of high-performance MOF-based MMMs for carbon capture applications.

Effect of porous structure on Ni-CaO bifunctional catalysts for the integrated CO2 capture and methanation process

Integrated CO2 capture and in-situ methanation technology (ICCU-M) is a promising approach for directly capturing and simultaneously converting CO2 into CH4 in a single process. The bifunctional catalyst that combines CO2 adsorption and catalytic properties into one particle is an ideal choice for ICCU-M process. In this work, we demonstrate that pore structure of bifunctional catalysts plays a pivotal role in their ICCU-M performance. The characterization results indicate that the presence of porosity weakens the encapsulation of Ni nanoparticles by the formed CaCO3 layer due to the volume expansion caused by the larger molar volume of CaCO3 compared to CaO (36.1 cm3/mol vs 16.9 cm3/mol). The ICCU-M performance shows that 5Ni-CaO-C1:1 has a lower CH4 formation temperature of 325 °C than 425 °C of 5Ni-CaO-w due to its abundant pores retaining more Ni sites, thus providing higher methanation activity. Meanwhile, 5Ni-CaO-C1:1 also exhibits higher CH4 selectivity than 5Ni-CaO-w (93.5 % vs 40 %) at 525 °C. Our results show that the volume expansion process of bifunctional catalysts has a significant impact on ICCU-M performance, which needs to be considered when designing efficient bifunctional catalysts for ICCU processes.

Investigating adsorption properties of CO2 and CH4 in subbituminous coals from Mamu and Nsukka formations: a molecular simulation approach

The study aimed to investigate the adsorption properties of methane (CH4) and carbon dioxide (CO2) in subbituminous coals from the Mamu and Nsukka formations, focusing on the CO2-Enhanced Coalbed Methane (ECBM) method. Proximate, ultimate, and FT-IR analyses determined the quality, age, and functional categories of these coals, confirming their subbituminous nature. Using molecular dynamics (MD) simulations, a unique amorphous subbituminous coal model was developed to study adsorption phenomena. Isosteric heat and adsorption isotherms for pure CO2 and CH4 were analyzed, alongside Grand Canonical Monte Carlo (GCMC) simulations to assess CO2 adsorption selectivity in a binary CO2 and CH4 mixture. Results showed that CO2 required more isosteric heat than CH4 in single-component scenarios and demonstrated stronger electrostatic interactions with heteroatom groups in the coal model, explaining its higher adsorption preference. In binary adsorption experiments, CO2 exhibited a higher affinity under specific conditions, particularly influenced by pressure variations. At lower pressures, CO2 selectivity decreased rapidly with increasing temperature, while at higher pressures, the influence of temperature diminished. These findings have established a theoretical and practical basis for optimizing CO2-ECBM extraction in Nigeria, highlighting the preferential adsorption of CO2 over CH4 in subbituminous coals from the Mamu and Nsukka formations under varying pressure and temperature conditions. Implementing CO2-ECBM extraction and storage in Nigeria could boost economic viability and help achieve net-zero goals, using insights from this study to guide policy development.Graphical

Tuning the Electronic Properties of CumAgn Bimetallic Clusters for Enhanced CO2 Activation.

The urgent demand for efficient CO2 reduction technologies has driven enormous studies into the enhancement of advanced catalysts. Here, we investigate the electronic properties and CO2 adsorption properties of CumAgn bimetallic clusters, particularly Cu4Ag1, Cu1Ag4, Cu3Ag2, and Cu2Ag3, using generalized gradient approximation (GGA)/density functional theory (DFT). Our results show that the atomic arrangement within these clusters drastically affects their stability, charge transfer, and catalytic performance. The Cu4Ag1 bimetallic cluster emerges as the most stable structure, revealing superior charge transfer and effective chemisorption of CO2, which promotes effective activation of the CO2 molecule. In contrast, the Cu1Ag4 bimetallic cluster, in spite of comparable adsorption energy, indicates insignificant charge transfer, resulting in less pronounced CO2 activation. The Cu3Ag2 and Cu2Ag3 bimetallic clusters also display high adsorption energies with remarkable charge transfer mechanisms, emphasizing the crucial role of metal composition in tuning catalytic characteristics. This thorough examination provides constructive insights into the design of bimetallic clusters for boosted CO2 reduction. These findings could pave the way for the development of cost-effective and efficient catalysts for industrial CO2 reduction, contributing to global efforts in carbon management and climate change mitigation.

Enhancement of CO2 adsorption and oxygen transfer properties on γ-Al2O3 support through surface modification with MgO-ZrO2 for coke suppression over Ni catalyst in CO2 reforming of methane

This work focuses on employing commercial γ-Al2O3 for surface modification with MgO-ZrO2 mixed oxide to enhance the potential of CO2 adsorption and oxygen mobility. This enhancement facilitates its application as a support in catalysts for CO2 utilization such as CO2 reforming of methane (CRM). To achieve this perspective, γ-Al2O3 was modified with 10 wt.% of various MgO and ZrO2 contents (MgO:ZrO2= 10:0, 9:1,7:3, 5:5, 3:7, 1:9 and 0:10) using the impregnation method. All samples including unmodified γ-Al2O3 (Al) were characterized. Due to the increase in basicity and oxygen transfer around the surface, the improvement of the CO2 adsorption was observed on γ-Al2O3 modified with 9 wt.% MgO-1 wt.% ZrO2 (9Mg1ZrAl) and 10 wt.% MgO (10MgAl), respectively. An application of these two superior samples as a support of 10 wt.% Ni (10Ni) catalysts for CRM was investigated and compared with an unmodified γ-Al2O3. Characterization results suggest the formation of NiO-MgO solid solution at the surface due to the decrease in metal-support interaction and the increase in metal dispersion. The Ni catalysts with the surface-modified support show higher CO2 activity that raises carbon deposition resistance. The greatest coke prevention was observed on 10Ni/9Mg1ZrAl that lowers the coke deposition by 42 % compared to 10Ni/Al. It indicates that the composition of this modification allowed very low ZrO2 portion to merge with MgO and MgO to form solid solution with NiO. This enables the 10Ni/9Mg1ZrAl catalyst to generate labile oxygens which can be conveyed to the Ni metal sites on the catalyst.

Luminescence Changeable CO2-Storage Cylinder: Triple-Stranded Helical Eu(III)/Tb(III) Fluorinated MOFs with Amide Linkers.

Triple-stranded helical lanthanide MOFs with CO2 adsorption properties were investigated. Lanthanide MOFs ([Eu0.1Tb0.9(hfa)3(dpa)]n) are composed of lanthanide luminophores (Eu(III) and/or Tb(III) ions), fluorinated antenna ligands (hfa: hexafluoroacetylacetonate), and polyamide-type linker ligands (dpa: 4-(diphenylphosphoryl)-N-(4-(diphenylphosphoryl)phenyl)benzamide). The cylindrical structure was characterized by single-crystal X-ray analysis, thermogravimetric analysis, and gas adsorption measurements. The inner surfaces of the cylindrical channels were covered with the fluorine atoms of the hfa ligands. The emission intensity ratio (IEu/ITb) in [Eu0.1Tb0.9(hfa)3(dpa)]n is affected by the CO2 gas adsorption behavior. The change in IEu/ITb value was caused by the intermolecular interactions between the CO2 gas molecules and the fluorinated ligands, resulting in an electronic structural change of the lowest triplet excited state in the photosensitized hfa ligands.

Synthesis of porous hypercrosslinked polymers from waste polystyrene for efficient CO2 separation

A series of porous hypercrosslinked polymers (HCP-x) were synthesized from waste polystyrene foam via Fridel-Crafts alkylation reaction, aiming to optimize the utilization of waste plastics. The impact of various crosslinkers on the structural characteristics and CO2 adsorption properties of HCP-x was investigated. The results indicated that HCP-x polymers possess high specific surface areas spanning 830–1182 m2 g−1, abundant narrow micropores, and exceptional thermal stability. Notably, HCP-2 exhibited the highest CO2 adsorption capacity of 2.77 mmol g−1 at 273 K and 1.0 bar. These hypercrosslinked polymers also demonstrated a favorable CO2/N2 ideal selectivity and robust cyclic adsorption performance. Breakthrough experiments confirmed the selective adsorption of CO2 from simulated flue gas containing CO2/N2 (15/85). Additionally, the mechanism underlying CO2 adsorption on HCP-x was elucidated by analyzing adsorption thermodynamics and diffusion kinetics. This study not only introduces an innovative method for recycling waste polystyrene foam but also underscores the potential of HCP-x as an effective adsorbent for CO2 capture.

Preparation of porous carbon from hydrothermal treatment products of modified antibiotic mycelial residues and its use in CO2 capture

Antibiotic mycorrhizal residues (AMR) are valuable organic wastes but have become a significant environmental and economic challenge due to their potentially hazardous nature and high treatment costs. In this study, an environmentally friendly and low-cost in situ nitrogen-doped porous carbon material was successfully prepared by hydrothermal carbonisation combined with KOH activation for efficient CO2 capture. The obtained material was systematically characterized and tested, and its physical and chemical properties were analyzed. By adjusting the activation temperature from 600 to 800 °C, the prepared porous carbon materials exhibited different specific surface areas (648.41–1712.72 m²/g), pore volumes (0.310–0.879 cm³/g), and the nitrogen was uniformly distributed in the carbon skeleton. The optimal N-doped porous carbon demonstrated the adsorption capacities of 3.99 mmol g−1 at 25 ℃ and 5.35 mmol g−1 at 0 ℃ under 1 bar. In addition, the prepared adsorbents exhibited excellent CO2/N2 selectivity, high isosteric heat, and good cyclic stability. These excellent CO2 adsorption properties were attributed to the highly developed microporous structure of the materials and the uniformly distributed nitrogen functional groups in the carbon skeleton. Overall, the results highlight the great potential of this class of heteroatom-doped novel carbon materials as selective CO2 adsorbents, providing a practical way to seek efficient CO2 abatement solutions.

Metal clusters modified hexagonal boron nitride for adsorption and sensing of lithium batteries thermal runaway gases

Developing efficient gas sensing materials for monitoring lithium batteries thermal runaway gases is essential for human safety. In this study, a detailed examination of the CH4, CO2, CO, and H2 adsorption property for the h-BN with metal clusters modification was conducted utilizing density functional theory. The incorporation of metal clusters (Pd4, Rh4, and Ru4) significantly improved the adsorption energy and charge transfer of h-BN towards gases compared to the unmodified h-BN. The Ru4/h-BN system demonstrated the highest adsorption capacity across all four gases, while the Pd4/h-BN system displayed remarkable recovery ability at room temperature (298 K). Furthermore, studying the adsorption mechanism via DOS revealed enhanced gas adsorption due to orbital hybridization. The work offers reliable theoretical foundation for the detection and prevention of thermal runaway gases in lithium batteries through the use of h-BN modified with metal clusters.

Reversed Mg-Based Smectites: A New Approach for CO2 Adsorption

Addressing climate change requires transitioning to cleaner energy sources and adopting advanced CO2 capture techniques. Clay minerals are effective in CO2 adsorption due to their regenerative properties. Recent advancements in nanotechnology further improve their efficiency and potential for use in carbon capture and storage. This study examines the CO2 adsorption properties of montmorillonite and saponite, which are subjected to a novel microwave-assisted acid treatment to enhance their adsorption capacity. While montmorillonite shows minimal changes, saponite undergoes significant alterations. Furthermore, the addition of silica pillars to smectites results in a new nanomaterial with a higher surface area (653 m2 g−1), denoted as reversed smectite, with enhanced CO2 adsorption capabilities, potentially useful for electrochemical devices for converting captured CO2 into value-added products.

Hierarchically porous MgO/biochar composites for efficient CO2 capture: Structure, performance and mechanism

For enhancing the CO2 uptake performance of MgO-based materials, hierarchically porous MgO/biochar composites were prepared using a microwave-assisted hydrothermal method. The CO2 adsorption properties was investigated in detail and the adsorption mechanism was revealed by considering structure − function relationships and performing density functional theory calculations. The MgO/biochar-1 had hierarchical pore structure and high specific surface area (1453 m2·g−1) with abundant narrow micropores (<1.0 nm), facilitating the adsorption of CO2. The results demonstrated that MgO/biochar-1 exhibited the highest CO2 capture capacity of 6.65 mol⋅kg−1 (273 K, 1 bar) and excellent selectivity for CO2/N2 (96.70 at CO2/N2 = 15:85, v/v). After 3 cycles, the adsorption capacity of MgO/biochar-1 still remained at 5.70 mol⋅kg−1 (273 K, 1 bar), suggesting the well cycling performance. The results of density functional theory calculation indicated that the oxygen-containing functional groups and MgO particles substantially enhanced the CO2 capture performance due to the enhanced interactions between MgO/biochar and CO2. This study provides novel insights for the construction of efficient and cheap solid adsorbents for CO2 capture.

Cu promoted Ni-Ca dual functional materials for integrated CO2 capture and utilization in O2-containing flue gas: Eliminating the delay in the utilization stage

Integrating CO2 capture and utilization by dry reforming methane (ICCU-DRM) technology is promising in concentrating and utilizing diluted CO2 from flue gas, which depends on developing Dual Functional Materials (DFMs) with adsorption and catalytic sites. Ni-Ca materials are widely applied in ICCU-DRM due to their excellent catalytic and CO2 adsorption properties. Nevertheless, the challenge remains that oxygen in the actual flue gas would oxidize the active Ni, leading to a delay in the DRM stage. In this work, Cu-promoted, ZrO2-stabilized Ni-Ca based DFMs were developed, which suppressed the delay and enhanced the performance of the DRM reaction. Attribute to the excellent reducing properties, Cu could be rapidly reduced in the CH4 atmosphere and further promote the reduction of NiO to the catalytically active Ni monomers by activating methane to generate reactive hydrogen (H*). What’s more, attributed to the disappearance of delay times, it is accompanied by a satisfying yield distribution with a 0.11 decrease in H2/CO ratio and an improvement in conversion, especially CH4 conversion with an increase of more than 10%. In addition, the bifunctional material also exhibits favorable cycling stability due to the stabilizers.

The effect of adsorbent shaping on the equilibrium and kinetic CO2 adsorption properties of ZIF-8

To be used at scale, adsorbents must be shaped into macroscopic objects, e.g. pellets, granules, and monoliths. Shaping may involve various processing steps and additives that collectively contribute to the final equilibrium and kinetic sorption properties of the adsorbent. Understanding the fundamental links between these processing steps and the resulting sorption performance is needed to rationalise the design of shaped adsorbents. Our study aims to advance the state of knowledge in this area. By focusing on ZIF-8, a prototypical metal organic framework (MOF), and CO2, a common small gas adsorbate, we compared a commercial binderless ZIF-8 extrudate and two purpose-made ZIF-8 pellets shaped with a blend of binders. We used analytical, spectroscopic, and imaging techniques to characterise the samples’ chemical, textural, and morphological properties. In addition, we collected equilibrium and kinetic CO2 adsorption data at 283, 293, and 303 K and up to 1 bar. The binderless ZIF-8 extrudate exhibited a homogeneous structure with BET area, micro- and meso-porosity only slightly reduced compared to ZIF-8 powder. The ZIF-8 pellets also maintained the overall BET area of the ZIF-8 powder, but displayed enhanced macroporosity and skeletal density as well as reduced microporosity – features that likely result from the pressure-induced strains of pelletisation. The extrudates are much less mechanically robust than the pellets. All samples displayed CO2 adsorption capacity in line with the CO2 uptake of their respective components. The CO2 kinetics measurements reveal clear distinctions between binderless ZIF-8 extrudate and ZIF-8 pellets, the latter indicating a behaviour associated with the additional presence of macropores. Our study presents quantifiable evidence for the effect of adsorbent shaping on gas adsorption equilibria and kinetics, providing a valuable resource for preliminary process design.

Preparation of isoreticular MIL-101(Cr) based on pre- and post-synthetic strategy and study for carbon dioxide capture

The functionalization of MIL-101(Cr) presents a formidable challenge when employing covalent bonds, due to the inherent difficulty of incorporating reactive organic groups into its structure. In this work, we have successfully synthesized MIL-101-CHO tagged with formyl by adopting a pre-synthetic strategy, utilizing 3‑hydroxy-1-oxo-1,3-dihydroisobenzofuran-5-carboxylic acid as the key ligand. Then the integrity of the formyl group and the phase purity of the resulting MIL-101-CHO were rigorously confirmed through FT-IR and 1H NMR characterization. Employing post-synthetic strategy, four amine-MOFs were prepared through cascade reaction of Schiff-base condensation and NaBH4 reduction. The CO2 adsorption properties of all isoreticular MIL-101(Cr) materials were thoroughly investigated. Notably, MIL-101-TAEA demonstrated exceptional performance, with the highest Qst 70.1 kJ/mol at low coverage, the best adsorption capability 2.34 mmol/g at 298 K under 1 bar CO2, and the selectivity 172 for CO2/N2. Furthermore, the good regenerability of MIL-101-TAEA was proved by the CO2 temperature swing adsorption tests. Ultimately, MIL-101-TAEA maintain 60 % performance for trace CO2 capture after 16 cycles under the mimic atmosphere conditions, showing its potential for practical applications in gas separation and capture technologies.

Fabrication of self-N-doped porous biochar by synergistic pyrolysis activation for efficient tetracycline and CO2 adsorption

The development of green and economical adsorption materials with high pollutant adsorption performance is of great significance to meet environmental challenges. Herein, self N-doped porous carbon materials with excellent tetracycline and CO2 adsorption properties are successfully prepared by synergistic pyrolysis activation of corn stalk and Chlorella mixture. The addition of N-riched Chlorella significantly affects the nanopore and surface chemical structure of biochar, forming rich micro-mesopores, changing the intrinsic N doping form and surface oxygen-containing functional groups. An ultra-high tetracycline adsorption capacity of 1159.7 mg/g can be achieved by using the prepared KBC-3:1 as an adsorbent. A series of kinetic isothermal adsorption models, thermodynamic calculations, as well as comparative characterization analysis show that multiple adsorption mechanisms coexist. The pore filling of micro-mesopores (1.5–3 nm), π-π interactions of CC bonds, H bonding interactions of CO and the strong electrophilicity of pyrrolic N contribute to the excellent tetracycline adsorption performance of KBC-3:1. Furthermore, the material shows great resistance to cationic (K+, Mg2+, Cu2+) interference and excellent cycling performance. In addition, KBC-3:1 also exhibits excellent adsorption capacity for CO2, and the adsorption capacity of 5.21 mmol/g can be achieved at 273 K and 1 bar, which could be attributed to the synergistic activation effect leading to KBC-3:1 having the most abundant pyrrolic and pyridinic N species as well as the rich microporous structure. This work can provide guidance for the development of green and economical high performance carbon materials based on the intrinsic characteristics of biomass.