Materials For CO2 Storage Research Articles

Purification of Waste-Generated Biogas Mixtures Using Covalent Organic Framework's High CO2 Selectivity.

Development of crystalline porous materials for selective CO2 adsorption and storage is in high demand to boost the carbon capture and storage (CCS) technology. In this regard, we have developed a β-keto enamine-based covalent organic framework (VM-COF) via the Schiff base polycondensation technique. The as-synthesized VM-COF exhibited excellent thermal and chemical stability along with a very high surface area (1258 m2 g-1) and a high CO2 adsorption capacity (3.58 mmol g-1) at room temperature (298 K). The CO2/CH4 and CO2/H2 selectivities by the IAST method were calculated to be 10.9 and 881.7, respectively, which were further experimentally supported by breakthrough analysis. Moreover, theoretical investigations revealed that the carbonyl-rich sites in a polymeric backbone have higher CO2 binding affinity along with very high binding energy (-39.44 KJ mol-1) compared to other aromatic carbon-rich sites. Intrigued by the best CO2 adsorption capacity and high CO2 selectivity, we have utilized the VM-COF for biogas purification produced by the biofermentation of municipal waste. Compared with the commercially available activated carbon, VM-COF exhibited much better purification ability. This opens up a new opportunity for the creation of functionalized nanoporous materials for the large-scale purification of waste-generated biogases to address the challenges associated with energy and the environment.

Kraft Lignin-Derived Microporous Nitrogen-Doped Carbon Adsorbent for Air and Water Purification.

The study presents a streamlined one-step process for producing highly porous, metal-free, N-doped activated carbon (N-AC) for CO2 capture and herbicide removal from simulated industrially polluted and real environmental systems. N-AC was prepared from kraft lignin─a carbon-rich and abundant byproduct of the pulp industry, using nitric acid as the activator and urea as the N-dopant. The reported carbonization process under a nitrogen atmosphere renders a product with a high yield of 30% even at high temperatures up to 800 °C. N-AC exhibited a substantial high N content (4-5%), the presence of aliphatic and phenolic OH groups, and a notable absence of carboxylic groups, as confirmed by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and Boehm's titration. Porosity analysis indicated that micropores constituted the majority of the pore structure, with 86% of pores having diameters less than 0.6 nm. According to BET adsorption analysis, the developed porous structure of N-AC boasted a substantial specific surface area of 1000 m2 g-1. N-AC proved to be a promising adsorbent for air and water purification. Specifically, N-AC exhibited a strong affinity for CO2, with an adsorption capacity of 1.4 mmol g-1 at 0.15 bar and 20 °C, and it demonstrated the highest selectivity over N2 from the simulated flue gas system (27.3 mmol g-1 for 15:85 v/v CO2/N2 at 20 °C) among all previously reported nitrogen-doped AC materials from kraft lignin. Moreover, N-AC displayed excellent reusability and efficient CO2 release, maintaining an adsorption capacity of 3.1 mmol g-1 (at 1 bar and 25 °C) over 10 consecutive adsorption-desorption cycles, confirming N-AC as a useful material for CO2 storage and utilization. The unique cationic nature of N-AC enhanced the adsorption of herbicides in neutral and weakly basic environments, which is relevant for real waters. It exhibited an impressive adsorption capacity for the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) at 96 ± 6 mg g-1 under pH 6 and 25 °C according to the Langmuir-Freundlich model. Notably, N-AC preserves its high adsorption capacity toward 2,4-D from simulated groundwater and runoff from tomato greenhouse, while performance in real samples from Fyris river in Uppsala, Sweden, causes a decrease of only 4-5%. Owing to the one-step process, high yield, annual abundance of kraft lignin, and use of environmentally friendly activating agents, N-AC has substantial potential for large-scale industrial applications.

Alternative Synthesis of MCM-41 Using Inexpensive Precursors for CO2 Capture

We explore the use of industrial sources of silicon and surfactant for obtaining low-cost MCM-41 materials and evaluate their performances as CO2 adsorbents. All of them presented a high specific surface area with different structural characteristics and textural properties. Interestingly, the MCM-41 manufactured with the most economical reagents presented a SBET of 1602 m2·g−1. The template was removed by using thermal treatments in an air atmosphere or a washing process. Preservation of silanol groups proved to be more effective under washing or mild thermal treatment conditions with the advantage of their lower cost and environmental benefit. Surface reactivity against CO2 was enhanced by anchoring APTS to silanol groups through wet grafting. All amino-functionalized materials showed a performance as CO2 adsorbents comparable to those reported in the literature, reaching values close to 30 cm3·g−1 at 25 °C and 760 mmHg. Samples with a higher concentration of silanol groups showed better performance. Our studies indicate that adsorbed CO2 is retained at least up to 50 °C, and the CO2 is chemisorbed on the silica modified with amine groups. The chemisorbed gas at very low pressures points to the potential use of these materials for CO2 storage.

Synthesis and evaluation of the Ca–Ba composite adsorbent Based on CO2 storage material for CO2 adsorption

Synthesis and evaluation of the Ca–Ba composite adsorbent Based on CO2 storage material for CO2 adsorption

Porous carbon materials for CO2 capture, storage and electrochemical conversion

Porous carbon materials for CO2 capture, storage and electrochemical conversion

A green and multi-win strategy for coal fly ash disposal by CO2 fixation and mesoporous silica synthesis

Coal combustion provides plenty of energy, along with enormous coal fly ash (CFA) and CO2 emission. CFA could be recycled for mesoporous silica synthesis, but expensive templates are usually needed. In this work, we proposed a multi-win strategy using CO2 as the precipitator and template. Mesoporous silica powders, with a maximum specific surface area of 355.45 m2/g, a pore volume of 0.73 cm3/g, and an average pore size of around 7.67 nm, were synthesized. The influences of silicon concentration, CO2 flow rate, and ultrasound were investigated. In addition, the Na2CO3 by-product was produced with a purity of over 92 %. By averagely calculating, 1 ton CFA could generate 285 kg mesoporous silica and 1.02 t crude Na2CO3. Around 433 kg of CO2 could be absorbed. Therefore, multi-goals of CFA disposal, CO2 storage, and valuable silica materials production were realized, and the study could pave the way for large-scale industrial applications.

Control of the Structural Charge Distribution and Hydration State upon Intercalation of CO2 into Expansive Clay Interlayers

Numerous experimental investigations indicated that expansive clays such as montmorillonite can intercalate CO2 preferentially into their interlayers and therefore potentially act as a material for CO2 separation, capture, and storage. However, an understanding of the energy-structure relationship during the intercalation of CO2 into clay interlayers remains elusive. Here, we use metadynamics molecular dynamics simulations to elucidate the energy landscape associated with CO2 intercalation. Our free energy calculations indicate that CO2 favorably partitions into nanoconfined water in clay interlayers from a gas phase, leading to an increase in the CO2/H2O ratio in clay interlayers as compared to that in bulk water. CO2 molecules prefer to be located at the centers of charge-neutral hydrophobic siloxane rings, whereas interlayer spaces close to structural charges tend to avoid CO2 intercalation. The structural charge distribution significantly affects the amount of CO2 intercalated in the interlayers. These results provide a mechanistic understanding of CO2 intercalation in clays for CO2 separation, capture, and storage.

Emerging concepts in intermediate carbon dioxide emplacement to support carbon dioxide removal

Evaluation of materials for reversible solid-state and chemical CO2 storage.

A novel (CaO/CeO2)@CeO2 composite adsorbent based on microinjection titration-calcination strategy for CO2 adsorption

A simultaneous titration-calcination strategy was proposed to synthesize core–shell type (CaCO3/Ce(OH)CO3)@Ce(OH)CO3 precursors by titrating Ca2+ and Ce3+ into aqueous CO2 storage material (CO2SM) solution simultaneously without adding any templating agents or surfactants. After calcination at 900 °C, the novel core–shell type (CaO/CeO2)@CeO2 composite adsorbent with the strong stability of adsorption cycle was synthesized. The effects of Ca/Ce doping ratio, CO2SM dosage, drop rate and temperature conditions on the CO2 adsorption performance on the composite adsorbent during the calcium cycle were investigated. The synthetic adsorbent with a Ca/Ce doping ratio of 24: 1 had the strongest CO2 capture performance during the calcium cycle, and it mainly consisted of CaO and CeO2. The CO2 adsorption amount still maintained at about 430 mg/g after 15 cycles under the adsorption–desorption conditions at 750 °C and 900 °C. (CaO/CeO2)@CeO2 composite adsorbent is a core–shell structure with CeO2 as the shell and CaO/CeO2 as the liner, in which CeO2 is uniformly dispersed in CaO pore channels, which gives the adsorbent a stable pore structure and enhances the anti-sintering performance of Ca-based adsorbent. Due to the special property of CeO2, it can also promote the ion migration during the carbonation process, thus maintaining the adsorption activity. Density functional theory (DFT) calculations successfully explain why CeO2 can be used as an inert dopant to promote the adsorption of CO2. After that, the synthesis mechanism of core–shell adsorbent and the reaction mechanism of CO2 adsorption are proposed in conjunction with the series characterization. This work provides a new strategy for the efficient synthesis of Ca-based adsorbents with special morphology and a new idea for CO2 capture.

Evaluation of an ε-manganese (IV) oxide/manganese vanadium oxide composite catalyst enriched with oxygen vacancies for enhanced formaldehyde removal

Formaldehyde removal is vital to health, but the construction of high-performance non-precious metal catalysts still faces great challenges, in which increasing oxygen vacancies by dopant modification is an advanced strategy to enhance catalytic activity. In this work, a novel ε-MnO2/Mn2V2O7 composite catalyst with a synergistic effect was synthesized on the basis of a thermal decomposition strategy. Meanwhile, the precursor for the catalyst was synthesized from the reaction among CO2-storage material, Mn2+, and vanadate without additional template agents and surfactants. Aided by the catalyst, the degradation rate of a 20 mg/L 10 mL formaldehyde (HCHO) solution can reach 72.0% and maintain above 67% after 5 cycles at 30 °C for 1 h. Subsequently, the as-obtained synergistic catalytic mechanism showed that the high-valent V5+ may partially replace Mn4+ in the MnO2 framework, promoting the formation of enriched oxygen vacancies (V4+-□-Mn3+) on the surface of the composite catalyst via the redox coupling of Mn4+/Mn3+ and V5+/V4+. This leads to an increase in adsorbed oxygen, significantly improving the degradation performance of HCHO. This work provides a novel and advanced strategy for dopant modification to develop superior non-precious metal catalysts.

Carbon dioxide adsorption of two-dimensional Mo2C MXene

In this paper, the CO2 adsorption behaviors of Mo2C MXene were explored for the first time. Two-dimensional (2D) Mo2C MXene samples were prepared by hydrothermal etching in four different solutions (LiF, NaF, KF or NH4F with HCl). The sample made by LiF + HCl etching exhibited the highest capacity of 3.66 mmol g−1, which is consistent with theoretical calculation that Mo2CO2 decorated by Li has stronger interaction with CO2 than those of Na and K. Although Mo2C MXene has low specific surface area (SSA, 4.9–8.9 m2 g−1) as compared with those of Ti3C2 (21 m2 g−1) and V2C (9 m2 g−1) MXenes, Mo2C MXene possesses better performance on CO2 capture than Ti3C2 (1.33 mmol g−1) and V2C (0.52 mmol g−1) MXenes at 4 MPa. This is because the CO2 adsorption of Mo2C MXene is mainly physical absorption formed by the capillary condensation in mixed pores (micropores and mesopores) and slitlike pores between two Mo2C MXene flakes. Besides, the CO2 adsorption on the surface of Mo2C MXene with functional groups (O or F) shows a current of chemisorption feature. This work indicates that Mo2C MXene is a promising candidate for CO2 capture and storage material.

Controlled preparation of CaO adsorbents by microsyringe titration technology for CO 2 capture

CaCO3 precursors were prepared by a simple titration method by dropping CaCl2 solution into a CO2 storage material (CO2SM) solution using a syringe pump; afterward, the precursors were roasted at 900°C to form CaO adsorbents for CO2 adsorption at 750°C for 2 h. Subsequently, the CO2SM dosage, CaCl2 concentration, drip speed, temperature, and stirring speed were systemically optimized by designing single-factor experiments. Further, a three-factor and three-level response surface experiment was designed to investigate the interactions among the factors according to their effects on CO2 adsorption. After optimizing the preparation conditions, the CO2 adsorption capacity reached 739.6 mg/g. Fifteen adsorption cycles were conducted on the adsorbent under the optimal preparation conditions, and the adsorption performance was reduced by 52.8%. Finally, the formation mechanism of CaCO3 and the CO2 adsorption processes of CaO were discussed using a Fourier-transform infrared spectrometer (FTIR), X-ray diffractometer (XRD), scanning electron microscope (SEM), and high-resolution transmission electron microscope (HR-TEM). © 2022 Society of Chemical Industry and John Wiley & Sons, Ltd.

Highly effective removal of formaldehyde from aqueous solution using mesoporous ɛ-MnO2 crystals at room temperature

Without additional templating agent or surfactant, porous and sparse MnCO3 was synthesized hydrothermally from Mn2+ with a CO2-storage material (CO2SM). Through thermal decomposition of the as-synthesized MnCO3, ɛ-MnO2 crystals with good catalytic performance and stability in HCHO degradation were prepared. The optimum preparation conditions were determined by tuning the preparation conditions and carrying out response surface studies, and the resulting ɛ-MnO2 crystals could degrade 66.1% of a 10 ml 10 mg l−1 HCHO solution. After the HCHO degradation conditions were optimized, the thermodynamic data could be fitted with the Langmuir isotherm and quasi-secondary kinetic models at T = 25–50°C. The degradation mechanism of HCHO is discussed. This work provides a new strategy for the degradation of HCHO at room temperature.

Pyrolysis of rice husk using CO2 for enhanced energy production and soil amendment

Anthropogenic CO2 generations from use of fossil resources has led to catastrophic climate problems. Biochar is a promising material for CO2 capture and storage in soil, because it does not require additional storage space. To produce biochar, pyrolysis is required in an oxygen-limited condition. In an attempt to offer more environmentally benign route for biochar formation, this study introduced CO2 as a reaction agent. Using rice husk as a model compound, biochars were produced under CO2 and N2 condition. Porosity of rice husk biochars (RHBs) were enhanced under CO2 condition, because CO2 affected to formation of nano-sized pores. pH and moisture retention capacity of garden soil was controlled with an addition of RHBs. Mixtures of garden soil and RHB were also used as cultivation media for growth of barley grass, and plant growth in the mixtures was improved by 20% comparing to garden soil. Moreover, CO2 contributed to enhanced syngas generation during biochar production through gas phase reactions between CO2 and volatile compounds. Thus, this study proved that CO2 is a useful reactant for pyrolysis of biomass waste.

Coating all-boron B38 fullerene with Ca and Al atoms for enhancing CO2 capture: a DFT study

It is widely recognised that capturing and storing CO2 on porous materials is an efficient approach for lowering the concentration of this greenhouse gas in the atmosphere. The current work investigates the ability of Ca and Al decorated all-boron B38 fullerene to capture and store CO2 using dispersion-corrected density functional theory calculations. The results showed that Ca and Al atoms can both firmly attach to the boron atoms in the hexagon cavity of B38. This eliminates the clustering issue and may ensure the stability of the decorated B38 fullerenes. According to the findings, the B38 fullerene decorated with four Ca or Al atoms may retain up to 16 CO2 molecules, corresponding to a maximum gravimetric density of about 55 wt%. The adsorption energy per CO2 in the Ca and Al decorated systems is about −0.70 eV, which is within the range proposed for effective CO2 storage (−0.40 to −0.80 eV). As a result, Ca and Al decorated B38 fullerenes are efficient and promising materials for high-capacity CO2 storage.

Sc-functionalized porphyrin-like porous fullerene for CO2 storage and separation: A first-principles evaluation

In recent years, there has been a lot of interest in capturing and storing carbon dioxide (CO2) on porous materials as an efficient method for decreasing the adverse effects of this greenhouse gas on the environment and climate change. The current work introduces a Sc-decorated porphyrin-like porous fullerene (Sc6@C24N24) as an efficient material for CO2 capture, storage, and separation using density functional theory calculations. While CO2 is physisorbed over pristine C24N24, the addition of Sc atoms on the N4 sites of C24N24 greatly enhances CO2 adsorption energy. Each Sc atom in Sc6@C24N24 may adsorb up to three CO2 molecules, resulting in a gravimetric density of 48%. Moreover, temperature may be used to modulate CO2 adsorption/desorption over the substrate. The Sc-decorated C24N24 fullerene exhibits a lower affinity for adsorbing N2, CH4, and H2 molecules than CO2. As a consequence, this material might be considered for purifying CO2 molecules from CO2/N2, CO2/CH4, and CO2/H2 mixtures. This study also sheds light on the nature of the Sc-CO2 interaction as well as the underlying mechanism of selective CO2 adsorption on Sc decorated C24N24.

Sc functionalized boron-rich C60 fullerene for efficient storage and separation of CO2 molecules: A DFT investigation

CO2 capture and storage on active porous materials have been widely proposed in recent years as an efficient solution to adverse effects of this greenhouse gas. However, finding suitable materials capable of capturing CO2 under normal conditions remains a significant issue. In this study, density functional theory calculations are used to examine Sc decorated boron-rich C60 fullerene (Sc@C48B12) as a potential material for CO2 storage and separation. While CO2 is physisorbed on the C60 or C48B12, it can be captured effectively by the Sc@C48B12 due to charge-transfer and polarization effects. Each Sc in Sc@C48B12 may store up to four CO2, resulting the adsorption of totally 24 CO2 which corresponds to a gravimetric density of 52%. Moreover, the adsorption of the CO2 onto the Sc@C48B12 is found to be reversible at ambient temperature. Sc@C48B12 can be also used as an efficient material for CO2 separation from CO2/H2, CO2/CH4, and CO2/N2 mixtures.

Ca coated B40 fullerene: A promising material for CO2 storage and separation

Density functional theory calculations were used to investigate the adsorption behavior of Ca coated B40 fullerene toward CO2 molecules. It was found that Ca atoms are unlikely to form clusters on B40. CO2 molecules can be effectively adsorbed on the Ca coated B40, as evidenced by large negative adsorption energies and significant charge transfer effects. Each Ca atom on B40 may adsorb four CO2, with an average adsorption energy of −0.54 eV which falls within the range proposed for an ideal CO2 adsorbent. Furthermore, Ca coated B40 exhibits high selectivity for CO2 from CO2/N2, CO2/H2, and CO2/CH4 gas mixtures.

Porous Metal-Organic Framework Liquids for Enhanced CO2 Adsorption and Catalytic Conversion.

The unique applications of porous metal-organic framework (MOF) liquids with permanent porosity and fluidity have attracted significant attention. However, fabrication of porous MOF liquids remains challenging because of the easy intermolecular self-filling of the cavity or the rapid settlement of porous hosts in hindered solvents that cannot enter their pores. Herein, we report a facile strategy for the fabrication of a MOF liquid (Im-UiO-PL) by surface ionization of an imidazolium-functionalized framework with a sterically hindered poly(ethylene glycol) sulfonate (PEGS) canopy. The Im-UiO-PL obtained in this way has a CO2 adsorption approximately 14 times larger than that of pure PEGS. Distinct from a porous MOF solid counterpart, the stored CO2 in Im-UiO-PL can be slowly released and efficiently utilized to synthesize cyclic carbonates in the atmosphere. This is the first example of the use of a porous MOF liquid as a CO2 storage material for catalysis. It offers a new method for the fabrication of unique porous liquid MOFs with functional behaviors in various fields of gas adsorption and catalysis.

Porous Metal–Organic Framework Liquids for Enhanced CO2 Adsorption and Catalytic Conversion

AbstractThe unique applications of porous metal–organic framework (MOF) liquids with permanent porosity and fluidity have attracted significant attention. However, fabrication of porous MOF liquids remains challenging because of the easy intermolecular self‐filling of the cavity or the rapid settlement of porous hosts in hindered solvents that cannot enter their pores. Herein, we report a facile strategy for the fabrication of a MOF liquid (Im‐UiO‐PL) by surface ionization of an imidazolium‐functionalized framework with a sterically hindered poly(ethylene glycol) sulfonate (PEGS) canopy. The Im‐UiO‐PL obtained in this way has a CO2 adsorption approximately 14 times larger than that of pure PEGS. Distinct from a porous MOF solid counterpart, the stored CO2 in Im‐UiO‐PL can be slowly released and efficiently utilized to synthesize cyclic carbonates in the atmosphere. This is the first example of the use of a porous MOF liquid as a CO2 storage material for catalysis. It offers a new method for the fabrication of unique porous liquid MOFs with functional behaviors in various fields of gas adsorption and catalysis.