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This study developed an energy-efficient, sustainable, and economical method for capturing carbon dioxide using landfilled coal fly ash. The innovative approach processes captured carbon dioxide with supplementary additives and alkali activators to produce a new class of hydraulic cement. A total of eight cement formulations incorporating varying proportions of landfilled coal fly ash, calcium-containing industrial byproducts, and alkali activators were produced and experimentally tested. The study achieved significant CO₂ uptakes, reaching up to 8.35% by weight of the raw materials. Up to 99.98% immobilization efficiency of heavy metal (copper) was recorded along with a significant increase in the total dissolved solids and conductivity. FTIR spectroscopy confirmed CO₂ incorporation with notable peaks at 1400 cm− 1 and 1063 cm− 1, indicating carbonate species. SEM and EDS analyses revealed varied morphologies, with dense, interconnected particle networks in some of the cement formulations. Compressive strength tests showed all formulations exceeded the EPA’s minimum requirement of 0.34 MPa, with the highest strength reaching 38 MPa at 28 days. The findings of this study point to the viability of the production of mechanochemically processed hydraulic cements in CO₂ environment with effective carbon sequestration capability, marked heavy metals immobilization characteristics, and enhanced physical and mechanical attributes. [ABSTRACT FROM AUTHOR]

Zeolites exhibit significant potential as porous materials for selective carbon dioxide (CO2) capture, leveraging their distinctive adsorption properties. However, the presence of moisture (H2O) and sulfur dioxide (SO2) in flue gas streams can significantly affect the efficiency of CO2 capture. This study investigates the CO2 adsorption characteristics of zeolites FAU 5A and LTA 13X, revealing the competitive adsorption mechanism between H2O(g), SO2, and CO2. The zeolites exhibit CO2 adsorption capacities of 93.19 mg/g and 95.80 mg/g for 5A and 13X, respectively, and demonstrate good regeneration potential. Metal cations correlated positively with CO2 adsorption. H2O(g), SO2, and CO2 exhibit a competitive adsorption relationship, with H2O(g) having the highest adsorption capacity, followed by SO2 and CO2. Additionally, the synergistic effect of SO2 and H2O(g) on CO2 adsorption is elucidated. These findings provide valuable insights into the competitive adsorption behavior of moisture and SO2 for CO2 capture using zeolites LTA 5A and FAU 13X, contributing to the development of more efficient CO2 capture processes and the design of tailored adsorbents for industrial applications. [ABSTRACT FROM AUTHOR]

Activated carbon is an attractive adsorbent for capturing various environmental pollutants, including CO2. Herein, an optimal synthesis and impressive performance of activated carbon made from Balanites aegyptiaca (Desert date) seed shells is reported, which is an abundant agricultural waste in the Middle East and Africa. The synthesis route involved pretreating the biomass with KOH and heating it under a suitable temperature profile. An optimal KOH‐to‐biomass ratio and multi‐stage carbonization yielded activated carbon with a surface area above 3000 m2/g and an average pore size of nearly 4.1 nm. At 0 °C, this activated carbon exhibited CO2 uptake of 11.3 mmol g−1 that surpassed the uptake capacity of previously reported activated carbons. The selectivity towards CO2 was also found to be significantly higher compared to other gases. Thus, the present approach demonstrates an efficient conversion of agricultural waste to activated carbon for capturing CO2 and other environmental contaminants. [ABSTRACT FROM AUTHOR]

This work assessed the carbon dioxide capture performance of different aqueous amines, in comparison to standard amine monoethanolamine (MEA), the standard for the capture process, A continuous operation was implemented, and a packed column served as the scrubber to develop effective sorbents for carbon capture and separation (CCS). The impact of operating variables such as carbon dioxide loading, feed amine temperature, solvent amine weight concentration, simulated gas flow rate, carbon dioxide feed concentration, amine type, and liquid flow rate was examined. Carbon dioxide concentration; absorption efficiency and overall mass transfer coefficient measurement as an indicator for the effectiveness of the capture process. For each system, the overall amine concentration was maintained at 30 weight percent and the treating a gas mixture containing 15% carbon dioxide (by volume) mimicking a fossil-derived flue gas. according to the findings of the experimental result that the raising of the efficiency of Carbon dioxide removal rises with rising amine concentration and amine flow rate; on the other side, the efficiency of carbon dioxide removal reduced with increasing gas flow rate, lean amine temperature, and lean amine temperature. The maximal carbon dioxide removal coefficients achieved by DETA and I-BA aqueous amine solutions under ideal circumstances are 90% and 76%, respectively. Additionally, at given the experiment's operating conditions, the highest volumetric total gas-phase mass transfer coefficient was found to be 0.25 and 0.24 (kmol/m3 h kpa), respectively.

Abstract The Earth’s energy balance produced by human activity is the main factor in the complex relationship between greenhouse gases and global warming. The Taiwan Environmental Protection Agency reports that carbon dioxide makes up more than 95% of Taiwan’s most recent greenhouse gas emissions. This study used fluidized-bed homogeneous crystallization (FBHC) technology to recover carbonate in a simulated CO2-enriched flue gas. It was specifically designed to determine how carbonate removal and crystallization efficiency were affected by carbonate surface loading, the influence of the source of calcium ions, and interfering substances. Results revealed that the best surface loading at 55 kg m− 2 h− 1 achieved 93% removal and 84% crystallization efficiency. At 50 mg L− 1 of sulfate ions, the presence of more interfering compounds tends to reduce carbonate removal to 97% and 91% crystallization. Regarding X-ray diffraction data, the recovered carbonate crystals resembled calcium carbonate crystals. It has been demonstrated that carbonate can be recovered using FBHC technology as a method of CO2 capture and storage.

Carbon-capture technologies are extremely abundant, yet they have not been applied extensively worldwide due to their high cost and technological complexities. This research studies the ability of polymerized fly ash to capture carbon dioxide (CO2) under low-pressure and low-temperature conditions via physical adsorption. The research also studies the ability to desorb CO2 due to the high demand for CO2 in different industries. The adsorption–desorption hysteresis was measured using infrared-sensor detection apparatus. The impact of the CO2 injection rate for adsorption, helium injection rate for desorption, temperature, and fly ash contact surface area on the adsorption–desorption hysteresis was investigated. The results showed that change in the CO2 injection rate had little impact on the variation in the adsorption capacity; for all CO2 rate experiments, the adsorption reached more than 90% of the total available adsorption sites. Increasing the temperature caused the polymerized fly ash to expand, thus increasing the available adsorption sites, thus increasing the overall adsorption volume. At low helium rates, desorption was extremely lengthy which resulted in a delayed hysteresis response. This is not favorable since it has a negative impact on the adsorption–desorption cyclic rate. Based on the results, the polymerized fly ash proved to have a high CO2 capture capability and thus can be applied for carbon-capture applications.

Wood-based substrates decorated with metal–organic frameworks (MOFs) postcarboxylation have garnered significant attention for CO2 capture. However, the practical applicability of composites synthesized via this method is constrained by modification difficulty, low binding strength, and environmentally unfriendly processes. In this work, we introduce an innovative approach that involves the oxidation of hydroxyl groups on wood cellulose C2 and C3 to aldehyde groups, producing a dialdehyde wood sponge (DWS). Subsequently, Cu-BTC MOFs (HKUST-1) were grown in situ in the 3D framework of the wood sponge through chelation. This strategy enhances the affinity between the MOFs and the wood-derived skeleton, significantly increasing the micropore surface area to 402 m2/g, with the micropores primarily concentrated at 0.71 nm. Benefiting from its high MOF load and abundant microporous structure, HKUST-1/DWS achieved a CO2 capture capacity of 2.34 mmol/g (273 K, 1 bar), remarkably surpassing that of HKUST-1/TWS (carboxylated wood sponge by 2,2,6,6-tetramethylpiperidinooxy), which exhibited a capacity of 1.59 mmol/g. Additionally, the synthesized solid adsorbent demonstrated high CO2/N2 adsorption selectivity (47.95), indicating the potential for efficient CO2 separation. This method of constructing MOF/wood-based CO2 sorbents enables chemical modification and facilitates efficient and sustainable carbon dioxide capture. [ABSTRACT FROM AUTHOR]

The Earth's energy balance produced by human activity is the main factor in the complex relationship between greenhouse gases and global warming. The Taiwan Environmental Protection Agency reports that carbon dioxide makes up more than 95% of Taiwan's most recent greenhouse gas emissions. This study used fluidized-bed homogeneous crystallization (FBHC) technology to recover carbonate in a simulated CO2-enriched flue gas. It was specifically designed to determine how carbonate removal and crystallization efficiency were affected by carbonate surface loading, the influence of the source of calcium ions, and interfering substances. Results revealed that the best surface loading at 55 kg m− 2 h− 1 achieved 93% removal and 84% crystallization efficiency. At 50 mg L− 1 of sulfate ions, the presence of more interfering compounds tends to reduce carbonate removal to 97% and 91% crystallization. Regarding X-ray diffraction data, the recovered carbonate crystals resembled calcium carbonate crystals. It has been demonstrated that carbonate can be recovered using FBHC technology as a method of CO2 capture and storage. [ABSTRACT FROM AUTHOR]

Non-aqueous absorbents (NAAs) have attracted increasing attention for CO 2 capture because of their great energy-saving potential. Primary diamines which can provide high CO 2 absorption loading are promising candidates for formulating NAAs but suffer disadvantages in regenerability. In this study, a promising strategy that using tertiary amines (TAs) as proton-transfer mediators was proposed to enhance the regenerability of an aminoethylethanolamine (AEEA, diamine)/dimethyl sulfoxide (DMSO) (A/D) NAA. Surprisingly, some employed TAs such as N,N -diethylaminoethanol (DEEA), N,N,N',N'',N'' -pentamethyldiethylenetriamine (PMDETA), 3-dimethylamino-1-propanol (3DMA1P), and N,N -dimethylethanolamine (DMEA) enhanced not only the regenerability of the A/D NAA but also the CO 2 absorption performance. Specifically, the CO 2 absorption loading and cyclic loading were increased by about 12.7% and 15.5%–22.7%, respectively. The TA-enhanced CO 2 capture mechanism was comprehensively explored via nuclear magnetic resonance technique and quantum chemical calculations. During CO 2 absorption, the TA acted as an ultimate proton acceptor for AEEA-zwitterion and enabled more AEEA to form carbamate species (AEEACOO−) to store CO 2 , thus enhancing CO 2 absorption. For CO 2 desorption, the TA first provided protons directly to AEEACOO− as a proton donor; moreover, it functioned as a proton carrier and facilitated the low-energy step-wise proton transfer from protonated AEEA to AEEACOO−. Consequently, the presence of TA made it easier for AEEACOO− to obtain protons to decompose, resulting in enhanced CO 2 desorption. In a word, introducing the TA as a proton-transfer mediator into the A/D NAA enhanced both the CO 2 absorption performance and the regenerability, which was an efficient way to "kill two birds with one stone". [Display omitted] [ABSTRACT FROM AUTHOR]

This work studied the low-temperature sorption of carbon dioxide on impregnated silica gel. An impregnating agent was used polyethyleneimine. The content of the impregnating agent in the silica gel matrix was 33.4 wt.%. Material properties such as the Brunauer–Emmett–Teller (BET) surface area, pore distribution, total pore volume, and thermal stability of the impregnated material were determined for the sample. During the measurement of the adsorption–desorption cycles, the loss of the impregnating agent in the material matrix was also determined. Due to the decrease in the content of polyethyleneimine, the sorption capacity of the adsorbent for CO2 also decreased. It was found that after the 20th adsorption–desorption cycle, the content of the impregnating agent in the adsorbent dropped by 3.15 wt.%, and, as a result, the adsorption capacity for CO2 dropped to almost half. [ABSTRACT FROM AUTHOR]

Carbon-capture technologies are extremely abundant, yet they have not been applied extensively worldwide due to their high cost and technological complexities. This research studies the ability of polymerized fly ash to capture carbon dioxide (CO2) under low-pressure and low-temperature conditions via physical adsorption. The research also studies the ability to desorb CO2 due to the high demand for CO2 in different industries. The adsorption–desorption hysteresis was measured using infrared-sensor detection apparatus. The impact of the CO2 injection rate for adsorption, helium injection rate for desorption, temperature, and fly ash contact surface area on the adsorption–desorption hysteresis was investigated. The results showed that change in the CO2 injection rate had little impact on the variation in the adsorption capacity; for all CO2 rate experiments, the adsorption reached more than 90% of the total available adsorption sites. Increasing the temperature caused the polymerized fly ash to expand, thus increasing the available adsorption sites, thus increasing the overall adsorption volume. At low helium rates, desorption was extremely lengthy which resulted in a delayed hysteresis response. This is not favorable since it has a negative impact on the adsorption–desorption cyclic rate. Based on the results, the polymerized fly ash proved to have a high CO2 capture capability and thus can be applied for carbon-capture applications. [ABSTRACT FROM AUTHOR]

Natural minerals, such as kaolinite, halloysite, montmorillonite, attapulgite, bentonite, sepiolite, forsterite, and wollastonite, have considerable potential for use in CO2 capture and mineralization due to their abundant reserves, low cost, excellent mechanical properties, and chemical stability. Over the past decades, various methods, such as those involving heat, acid, alkali, organic amine, amino silane, and ionic liquid, have been employed to enhance the CO2 capture performance of natural minerals to attain high specific surface area, a large number of pore structures, and rich active sites. Future research on CO2 capture by natural minerals will focus on the full utilization of the properties of natural minerals, adoption of suitable modification methods, and preparation of composite materials with high specific surface area and rich active sites. In addition, we provide a summary of the principle and technical route of direct and indirect mineralization of CO2 by natural minerals. This process uses minerals with high calcium and magnesium contents, such as forsterite (Mg2SiO4), serpentine [Mg3Si2O(OH)4], and wollastonite (CaSiO3). The research status of indirect mineralization of CO2 using hydrochloric acid, acetic acid, molten salt, and ammonium salt as media is also introduced in detail. The recovery of additives and high-value-added products during the mineralization process to increase economic benefits is another focus of future research on CO2 mineralization by natural minerals. [ABSTRACT FROM AUTHOR]

Copyright of Inorganic Chemicals Industry is the property of Editorial Office of Inorganic Chemicals Industry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Covalent organic frameworks are a novel class of crystalline porous polymers that enable molecular design of extended polygonal skeletons to attain well‐defined porous structures. However, construction of a framework that allows remote control of pores remains a challenge. Here we report a strategy that merges covalent, noncovalent, and photo chemistries to design photoresponsive frameworks with reversibly and remotely controllable pores. We developed a topology‐guided multicomponent polycondensation system that integrates protruded tetrafluoroazobenzene units as photoresponsive sites on pore walls at predesigned densities, so that a series of crystalline porous frameworks with the same backbone can be constructed to develop a broad spectrum of pores ranging from mesopores to micropores. Distinct from conventional azobenzene‐based systems, the tetrafluoroazobenzene frameworks are highly sensitive to visible lights to undergo high‐rate isomerization. The photoisomerization exerts profound effects on pore size, shape, number, and environment, as well as molecular uptake and release, rendering the system able to convert and switch pores reversibly and remotely with visible lights. Our results open a way to a novel class of smart porous materials with pore structures and functions that are convertible and manageable with visible lights. [ABSTRACT FROM AUTHOR]

The development of an environmentally friendly CO2 absorbent with significant energy utilization which can be an alternative to CO2 capture by an ethanolamine solution is presently an obligatory issue. In this work, binary and ternary deep eutectic solvents (DESs) were prepared according to their CO2 absorption/desorption performances. A series of DESs comprise different hydrogen bonding donor (HBD)- acceptor (HBA) pairs as CO2 capturing solvents; HBAs include choline chloride (ChCl) and tetrabutylammonium bromide (TBAB), and selected amines are represented as HBDs and include monoethanolamine (MEA), diethanolamine (DEA), and triethanolamine (TEA). Binary DESs synthesized of ChCl/MEA, ChCl/DEA, ChCl/TEA, TBAB/MEA, TBAB/DEA, and TBAB/TEA in a CO2 absorption cell at a mole ratio of 1:4. While selected amidines were represented as super-based (SB) and included 1,5-Diazabicyclo [4.3.0] non-5-ene (DBN) and 1,8-Diazabicyclo [5.4.0] undec-7-ene (DBU). The ternary DESs were prepared by adding DBN or DBU to the binary DESs system in a (1:4:3) molar ratio. CO2 absorption experiments were attained at atmospheric pressure and a temperature of 30 °C using 15 vol.% CO2 with 85 vol.% N2. On the other hand, the regeneration process for DESs was conducted at 90 oC. Binary DES synthesized from ChCl/MEA gives a higher absorption rate of CO2 of 0.0177 mole/kg. min, CO2 absorption loading of 2.9092 mole CO2/kg solvent, cyclic loading of 2.0001 mole CO2/kg solvent, and a regeneration efficiency of 68.75%. The synthesis DESs showed a better performance compare with a common Ionic liquids.

Abstract This study focuses on CO2 capture by pressure swing adsorption (PSA), with modified clinoptilolite as the adsorbent. Natural clinoptilolite is modified by roasting, by acid pickling, by a combination of acid pickling and roasting, and by ion exchange. Modification by acid pickling–roasting and by ion exchange are found to give the highest CO2 adsorption capacities, of 730 mL/g and 876.7 mL/g, respectively. It is found that regeneration of clinoptilolite by a combination of vacuum desorption and heating enables recovery of as much as 89% of its previous CO2 adsorption capacity. To examine the CO2 adsorption capacity of clinoptilolite when applied to mixed gas, a simulated coking exhaust containing 12% CO2 and 4% O2 is used, and it is found that ion exchange modified clinoptilolite achieves a CO2 removal efficiency of 92.5%. A BET test reveals that acid pickling–roasting and Na+ modification enhance the porosity of clinoptilolite, thereby improving its adsorption capacity. This work demonstrates the feasibility of applying modified clinoptilolite as an effective adsorbent for CO2 capture, providing a promising tool for dealing with greenhouse gases.

Superbase‐derived ionic liquids (SILs) are promising sorbents to tackle the carbon challenge featured by tunable interaction strength with CO2 via structural engineering, particularly the oxygenate‐derived counterparts (e. g., phenolate). However, for the widely deployed phenolate‐derived SILs, unsolved stability issues severely limited their applications leading to unfavorable and diminished CO2 chemisorption performance caused by ylide formation‐involved side reactions and the phenolate‐quinone transformation via auto‐oxidation. In this work, robust pyrazolonate‐derived SILs possessing anti‐oxidation nature were developed by introducing aza‐fused rings in the oxygenate‐derived anions, which delivered promising and tunable CO2 uptake capacity surpassing the phenolate‐based SIL via a carbonate formation pathway (O−C bond formation), as illustrated by detailed spectroscopy studies. Further theoretical calculations and experimental comparisons demonstrated the more favorable reaction enthalpy and improved anti‐oxidation properties of the pyrazolonate‐derived SILs compared with phenolate anions. The achievements being made in this work provides a promising approach to achieve efficient carbon capture by combining the benefits of strong interaction strength of oxygenate species with CO2 and the stability improvement enabled by aza‐fused rings introduction. [ABSTRACT FROM AUTHOR]

This study focuses on CO2 capture by pressure swing adsorption (PSA), with modified clinoptilolite as the adsorbent. Natural clinoptilolite is modified by roasting, by acid pickling, by a combination of acid pickling and roasting, and by ion exchange. Modification by acid pickling–roasting and by ion exchange are found to give the highest CO2 adsorption capacities, of 730 mL/g and 876.7 mL/g, respectively. It is found that regeneration of clinoptilolite by a combination of vacuum desorption and heating enables recovery of as much as 89% of its previous CO2 adsorption capacity. To examine the CO2 adsorption capacity of clinoptilolite when applied to mixed gas, a simulated coking exhaust containing 12% CO2 and 4% O2 is used, and it is found that ion exchange modified clinoptilolite achieves a CO2 removal efficiency of 92.5%. A BET test reveals that acid pickling–roasting and Na+ modification enhance the porosity of clinoptilolite, thereby improving its adsorption capacity. This work demonstrates the feasibility of applying modified clinoptilolite as an effective adsorbent for CO2 capture, providing a promising tool for dealing with greenhouse gases. [ABSTRACT FROM AUTHOR]

Polysulfone membranes, used as contactors for CO2 capture, are blended with two different hyperbranched polyethyleneimines modified with benzoyl chloride (Additive 1) and phenyl isocyanate (Additive 2) in different percentages. Fourier‐transformed infrared spectra evidence the presence of urea and amide groups, whereas the field emission scanning electron microscopy images show differences in the microstructure of the blended membranes. Dielectric spectra determine the motions of the side and backbone chains, which can facilitate the diffusion of CO2. The spectra consist of six dielectric processes; three of them are due to the polysulfone (γPSf, βPSf, and αPSf), whereas the rest are characteristic of the additive (γHPEI, βHPEI, and αHPEI). The benzoyl chloride and phenyl isocyanate functional groups introduce variations in molecular mobility and modify the relaxations associated with the hyperbranched polyethyleneimine (HPEI). The additives also increase the conductivity of the blended membranes, which can compromise the performance of the membranes, specifically in the case of Additive 1. Ion hopping is found to be the prevailing charge transport mechanism while both relaxations, αHPEI and αPSf, are actives. These results, together with the final morphology of the membranes, may explain the greater absorption capacity of the membranes prepared with the hyperbranched polyethyleneimine modified with Additive 2. [ABSTRACT FROM AUTHOR]

Condensation of 3,3′‐diamino‐2,2′‐ethylene‐bridged azobenzene with 1,2,4,5‐tetrakis‐(4‐formylphenyl) benzene produces a visible light responsive porous 2D covalent organic framework, COF‐bAzo‐TFPB, with a large surface area, good crystallinity, and thermal and chemical stability. The results demonstrate that the elaborated designed linker can make azo unit on the COF‐bAzo‐TFPB skeleton undergo reversible photoisomerization. This work expands the application scope of covalent organic frameworks in photo‐controlled release, uptake of guest molecules, dynamic photoswitching, and UV‐sensitive functions. [ABSTRACT FROM AUTHOR]

This work reports an efficient method for facile synthesis of hierarchically porous carbon (WB‐AC) utilizing wheat bran waste. Obtained carbon showed 2.47 mmol g−1 CO2 capture capacity with good CO2/N2 selectivity and 27.35 to 29.90 kJ mol−1 isosteric heat of adsorption. Rapid removal of MO dye was observed with a capacity of ~555 mg g−1. Moreover, WB‐AC demonstrated a good OER activity with 0.35 V low overpotential at 5 mA cm−2 and a Tafel slope of 115 mV dec−1. It also exhibited high electrocatalytic HER activity with 57 mV overpotential at 10 mA cm−2 and a Tafel slope of 82.6 mV dec−1. The large SSA (757 m2 g−1) and total pore volume (0.3696 cm3 g−1) result from N2 activation contributing to selective CO2 uptake, high and rapid dye removal capacity and superior electrochemical activity (OER/HER), suggesting the use of WB‐AC as cost effective adsorbent and metal free electrocatalyst. [ABSTRACT FROM AUTHOR]

Herein, a post‐synthetic modification strategy is used to covalently graft polyamines, including ethylenediamine (ED), diethylenetriamine (DETA), tris(2‐aminoethyl)amine (TAEA), and polyethyleneimine (PEI) to the amino‐ligand inside of a Cr‐MOF, NH2‐Cr‐BDC, for post‐combustion carbon capture applications. X‐ray absorption spectroscopy (XAS), X‐ray photoelectron spectroscopy (XPS), and ion chromatography (IC) reveal that ≈45% of the MOF ligands are grafted with polyamines. Next, assessment of CO2 uptake, CO2/N2 selectivity, isosteric heats of CO2 adsorption, separation performance during humid CO2/N2 (15/85) breakthrough experiments, and cyclability, reveals an enhanced performance for the polyamine‐containing composites and the following performance trend: NH2‐Cr‐BDC

Modern requirements for the production of hydrogen with a minimum carbon footprint, the possibility of using polygenerating systems for production of electricity, heat, or useful products, and chemical-looping technologies for producing hydrogen combined with capture of carbon dioxide are considered. A new system has been developed that integrates the use of biomass as a fuel, chemical looping, and syngas production in a polygenerating system of interconnected reactors, which is very promising in maximizing the effectiveness of hydrogen production without a carbon footprint (or with a negative carbon footprint). A procedure and results of calculations of the composition and consumption of generator gas, material balance of a chemical looping system, heat values of chemical reactions in a system of interconnected reactors, heat balance and temperatures in individual reactors, and heat and material balances in exhaust gas heat recovery units are presented. The effect of the main operating conditions of a chemical looping system on temperatures in the reactors was determined on the basis of the calculated and material balances. The calculated efficiency in terms of hydrogen production (75.93%) is given. This value fits well into the broad outline of the results obtained in simulation of similar systems for chemical looping hydrogen production from metal oxides and can be considered as a guideline when developing engineering solutions within the scope of the proposed process flow diagram. Potential directions of further studies are set. [ABSTRACT FROM AUTHOR]

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The implacable rise of carbon dioxide (CO2) concentration in the atmosphere and acute water stress are one of the central challenges of our time. Present‐day chemistry is strongly inclined towards more sustainable solutions. Covalent organic frameworks (COFs), attributable to their structural designability with atomic precision, functionalizable chemical environment and robust extended architectures, have demonstrated promising performances in CO2 trapping and water harvesting from air. In this Review, we discuss the major developments in this field as well as sketch out the opportunities and shortcomings that remain over large‐scale COF synthesis, device engineering, and long‐term performance in real environments. [ABSTRACT FROM AUTHOR]

Copyright of Low-Carbon Chemistry & Chemical Engineering is the property of Low-Carbon Chemistry & Chemical Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

CO2 capture is one of the key technologies for dealing with the global warming and implementing low-carbon development strategy. The emergence of ionic metal-organic frameworks (I-MOFs) has diversified the field of porous materials, which have been extensively applied for gas adsorption and separation. In this work, amino-functionalized imidazolium ionic liquid as organic monodentate ligand was used for one step synthesis microporous Cu based I-MOFs. Precise tuning of the adsorption properties was obtained by incorporating aromatic anions, such as phenoxy, benzene carboxyl, and benzene sulfonic acid group into the I-MOFs via a facile ion exchange method. The new I-MOFs showed high thermal stability and high capacity of 5.4 mmol·g−1 under atmospheric conditions for selective adsorption of CO2. The active sites of microporous Cu-MOF are the ion basic center and unsaturated metal, and electrostatic attraction and hydroxyl bonding between CO2 and modified functional sulfonic groups are responsible for the adsorption. This work provides a feasible strategy for the design of I-MOF for functional gas capture. [ABSTRACT FROM AUTHOR]

Microenvironments tailored by multifunctional secondary coordination sphere groups can enhance catalytic performance at primary metal active sites in natural systems. Here, we capture this biological concept in synthetic systems by developing a family of iron porphyrins decorated with imidazolium (im) pendants for the electrochemical CO2 reduction reaction (CO2 RR), which promotes multiple synergistic effects to enhance CO2 RR and enables the disentangling of second-sphere contributions that stem from each type of interaction. Fe-ortho-im(H), which poises imidazolium units featuring both positive charge and hydrogen-bond capabilities proximal to the active iron center, increases CO2 binding affinity by 25-fold and CO2 RR activity by 2000-fold relative to the parent Fe tetraphenylporphyrin (Fe-TPP). Comparison with monofunctional analogs reveals that through-space charge effects have a greater impact on catalytic CO2 RR performance compared to hydrogen bonding in this context.

Greenhouse gases (GHGs) cause global warming and climate change, making their emission and synthesis a global issue. Employing a pilot-scale scrubber packed with a Rashing ring randomly, where experimentally examined the absorption performance of carbon dioxide capturing by using an aqueous solvent of primary and poly alkanol amines; the investigations on carbon dioxide capturing were carried out at atmospheric pressure (1 atm.), using simulated feed gas of carbon dioxide balanced with nitrogen. Monoethanolamine, Triethylenetetramine, and Diethylenetriamine are the primary and poly alkanol amine absorbents examined for this work. The impact of operating conditions, including amine inlet concentrations, liquid flow rates, gas flow rate, lean amine loading, inlet carbon dioxide concentration, absorbent temperature, and alkanol amine type, were examined according to the two-film concept. Regarding the removal of carbon dioxide efficiency and volumetric mass transfer coefficient based on the gas side, the absorption performance was presented. A lab-scale investigation revealed that employing DETA absorbent possesses a higher carbon dioxide removal efficiency of up to 28.9% and a higher coefficient of mass transfer of up to 165.7% in comparison to conventional MEA absorbent while employing TETA absorbent possesses a higher carbon dioxide removal efficiency of up to 18.86% and a higher coefficient of mass transfer of up to 69.64% in comparison to the conventional MEA absorbent. Based on these findings, it is reasonable to assume that DETA would serve as an efficient chemical absorbent for the removal of carbon dioxide.

A series of porous core‐membrane microstructured nanomaterials, constructed of a deep eutectic solvent (DES) membrane and porous MOF‐808 core via liquid surface tensions and electrostatic interactions, are introduced for carbon dioxide capture with the sorption mechanism coupling diffusion, physisorption, and chemisorption. MOF‐808 as the porous core considerably improves the diffusion interactions for DES membranes, hence significantly enhancing the sorption performance of DESs. Although the DES consisted by monoethanolamine and tetrapropylammonium chloride (MEA‐TPAC‐7) has the highest sorption capacity among all DESs, it is only 4.39 mmol g−1 at 2.4 bar and further attenuates by fastidious diffusion interactions when increasing viscosity or dose. The sorption capacities of DES@MOF‐120 are 5.18 mmol g−1 at 3.0 bar and 4.78 mmol g−1 at 2.4 bar without apparent sorption hysteresis in pressure swing sorption, which are substantially improved contrasted to MEA‐TPAC‐7. The sorption isotherms are reconstructed via Sips models considering surface heterogeneity with regression correlation coefficients over 0.9454 to forecast maximum sorption capacity over 6.33 mmol g−1. [ABSTRACT FROM AUTHOR]

Metal–organic frameworks (MOFs) are a class of material made up of metal ions or clusters and organic linkers. Cyclodextrin-based MOFs (CD-MOFs) are gaining popularity among MOFs due to their unique features, such as high porosity, permanent porosity, and biocompatibility. This paper focuses on recent advances in synthesizing CD-MOFs and their water stability. We highlight the difficulties involved in CD-MOF synthesis and the strategies explored to increase water stability. The advances in CD-MOF synthesis and characterization open new avenues for tailoring crystal growth processes and properties, with potential applications spanning areas such as catalysis, drug delivery, and environmental remediation. The combination of innovative synthesis techniques, systematic parameter exploration, and functionalization strategies heralds a promising era for crystal growth research and applications. Finally, we discuss the current research gaps and the future outlook of CD-MOF research. Overcoming obstacles in the synthesis and water stability of CD-MOFs is crucial for their practical applications. [ABSTRACT FROM AUTHOR]

Carbon dioxide (CO2) capture and separation constitute an important field of research as we seek to reduce the effects of climate change. Because of their porosity, resilient crystallinity, high adsorption capacity, and affinity for CO2, cyclodextrin-based metal-organic frameworks (CD-MOFs) have emerged as attractive materials for carbon capture. This paper gives an overview of CD-MOFs and their applications in CO2 capture and separation. Several studies have been conducted to synthesize and characterize CD-MOFs for CO2 capture. The causes of the high binding affinity of CO2 in CD-MOFs were discovered through mechanistic studies on CO2 adsorption. Furthermore, CD-MOF modifications have been carried out to improve the sorption capacity and selectivity of CO2 adsorption. Meanwhile, several researchers have reported using CD-MOFs for gaseous CO2 membrane separation. This paper also highlights the current gaps in CD-MOF research and future outlooks in carbon capture and separation using CD-MOFs. [ABSTRACT FROM AUTHOR]

Hydrogen (H 2) production via steam methane reforming is a mature and cost-effective technology. However, carbon capture and storage is required to decrease its carbon dioxide (CO 2) emissions. The adoption of molten carbonate fuel cells as means to capture CO 2 from flue gases is attracting scientific interest thanks to their inherent thermodynamic advantage of separating CO 2 while producing electricity. This study investigates and benchmarks the performance of an H 2 production plant equipped with molten carbonate fuel cell for post-combustion CO 2 capture, by proposing a novel configuration where the cell anode is fed with the carbon-rich off-gas from the H 2 separation unit. It emerges that the process can achieve higher capture rates than the reference solvent-based plant: 85–90% with single cell, 95% with two-stage cell. Moreover, recycling the carbon-rich off gas to the anode allows for smaller cell area, and potentially lower H 2 production costs compared to the benchmark. • CO 2 capture from steam methane reforming with molten carbonate fuel cell is studied. • A novel process based on off-gas anode feed and 2-stage cell is proposed. • Novel process achieves 90–95% CO 2 capture, against 85% natural gas fed anode process. • Novel process has smaller cell area and H 2 production cost than natural gas feed. • Novel process has comparable H 2 production cost with conventional MEA CO 2 capture. [ABSTRACT FROM AUTHOR]

The zwitterions resulting from the covalent attachment of 3‐ or 4‐hydroxy benzene to the 1,3‐dimethylimidazolium cation represent basic compounds (pKa of 8.68 and 8.99 in aqueous solutions, respectively) that chemisorb in aqueous solutions 0.58 mol/mol of carbon dioxide at 1.3 bar (absolute) and 40 °C. Equimolar amounts of chemisorbed CO2 in these solutions are obtained at 10 bar and 40 °C. Chemisorption takes place through the formation of bicarbonate in the aqueous solution using imidazolium‐containing phenolate. CO2 is liberated by simple pressure relief and heating, regenerating the base. The enthalpy of absorption was estimated to be −38 kJ/mol, which is about 30 % lower than the enthalpy of industrially employed aqueous solutions of MDEA (estimated at −53 kJ/mol using the same experimental apparatus). The physisorption of CO2 becomes relevant at higher pressures (>10 bar) in these aqueous solutions. Combined physio‐ and chemisorption of up to 1.3 mol/mol at 40 bar and 40 °C can be attained with these aqueous zwitterionic solutions that are thermally stable and can be recycled at least 20 times. [ABSTRACT FROM AUTHOR]

Supercapacitive swing adsorption (SSA) is a newly discovered electrochemically driven carbon dioxide capture method using the principle of electric double‐layer capacitor, which achieves the purpose of adsorption and desorption of CO2 by charging and discharging the supercapacitive electrodes. Based on this method, gas separation devices were designed which could adsorb CO2 from a mixture of carbon dioxide and nitrogen, and a series of factors affecting the CO2 adsorption capacity were explored. This review briefly introduces the SSA mechanism and the structural design of SSA modules, and analyzes the factors influencing the performance of SSA from multiple aspects, with emphasis on electrode materials, in order to find ways to improve the CO2 adsorption capacity of SSA modules. [ABSTRACT FROM AUTHOR]

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Greenhouse gases (GHGs) cause global warming and climate change, making their emission and synthesis a global issue. Employing a pilot-scale scrubber packed with a Rashing ring randomly, where experimentally examined the absorption performance of carbon dioxide capturing by using an aqueous solvent of primary and poly alkanol amines; the investigations on carbon dioxide capturing were carried out at atmospheric pressure (1 atm), using simulated feed gas of carbon dioxide balanced with nitrogen. Monoethanolamine, Triethylenetetramine, and Diethylenetriamine are the primary and poly alkanol amine absorbents examined for this work. The impact of operating conditions, including amine inlet concentrations, liquid flow rates, gas flow rate, lean amine loading, inlet carbon dioxide concentration, absorbent temperature, and alkanol amine type, were examined according to the two-film concept. Regarding the removal of carbon dioxide efficiency and volumetric mass transfer coefficient based on the gas side, the absorption performance was presented. A lab-scale investigation revealed that employing DETA absorbent possesses higher carbon dioxide removal efficiency of up to 28.9% and a higher coefficient of mass transfer of up to 165.7% in comparison to conventional MEA absorbent while employing TETA absorbent possesses higher carbon dioxide removal efficiency of up to 18.86% and higher coefficient of mass transfer of up to 69.64% in comparison to the conventional MEA absorbent. Based on these findings, it is reasonable to assume that DETA would serve as an efficient chemical absorbent for the removal of carbon dioxide. [ABSTRACT FROM AUTHOR]

Algal cultivation is a sustainable approach which can be used not only for carbon dioxide sequestration but also for making useful products in many industries. To facilitate the widespread adoption of this approach, the current research studies the stable control of closed photobioreactors (PBRs) cultivating microalgae. More specifically, a proportional–integral (PI) controller is employed for the tracking of the microalgal concentration to a desired reference corresponding to a required amount of sequestrated carbon dioxide. In the presence of the practically positive and bounded constraints of the dilution rate, the stability and reference tracking of the closed-loop PBR system needs to be assessed. This work then derives conditions under which a unique equilibrium point exists and the closed-loop PBR system is asymptotically stable around such an equilibrium point. The derived theoretical results are validated and illustrated through numerical simulations for PBRs of the microalgae Chlorella vulgaris. [ABSTRACT FROM AUTHOR]

Steelmaking industry faces urgent demands for both steel slag utilization and CO2 abatement. Ca and Mg of steel slag can be extracted by acid solution and used to prepare sorbents for CO2 capture. In this work, the calcium-based sorbents were prepared from stainless steel slag leachate by co-precipitation, and the initial CO2 chemisorption capacity of the calcium-based sorbent prepared from steel slag with the Ca and Mg molar ratio of 3.64:1 was 0.40 g/g. Moreover, the effect of Ca/Mg molar ratio on the morphology, structure, and CO2 chemisorption capacity of the calcium-based sorbents were investigated. The results show that the optimal Ca/Mg molar ratio of sorbent for CO2 capture was 4.2:1, and the skeleton support effect of MgO in calcium-based sorbents was determined. Meanwhile, the chemisorption kinetics of the sorbents was studied using the Avrami-Erofeev model. There were two processes of CO2 chemisorption, and the activation energy of the first stage (reaction control) was found to be lower than that of the second stage (diffusion control). [ABSTRACT FROM AUTHOR]

CO2 absorption has been driven by the need for efficient and environmentally sustainable CO2 capture technologies. The development in the synthesis of ionic liquids (ILs) has attracted immense attention due to the possibility of obtaining compounds with designated properties. This allows ILs to be used in various applications including, but not limited to, biomass pretreatment, catalysis, additive in lubricants and dye-sensitive solar cell (DSSC). The utilization of ILs to capture carbon dioxide (CO2) is one of the most well-known processes in an effort to improve the quality of natural gas and to reduce the green gases emission. One of the key advantages of ILs relies on their low vapor pressure and high thermal stability properties. Unlike any other traditional solvents, ILs exhibit high solubility and selectivity towards CO2. Frequently studied ILs for CO2 absorption include imidazolium-based ILs such as [HMIM][Tf2N] and [BMIM][OAc], as well as ILs containing amine groups such as [Cho][Gly] and [C1ImPA][Gly]. Though ILs are being considered as alternative solvents for CO2 capture, their full potential is limited by their main drawback, namely, high viscosity. Therefore, the hybridization of ILs has been introduced as a means of optimizing the performance of ILs, given their promising potential in capturing CO2. The resulting hybrid materials are expected to exhibit various ranges of chemical and physical characteristics. This review presents the works on the hybridization of ILs with numerous materials including activated carbon (AC), cellulose, metal-organic framework (MOF) and commercial amines. The primary focus of this review is to present the latest innovative solutions aimed at tackling the challenges associated with IL viscosity and to explore the influences of ILs hybridization toward CO2 capture. In addition, the development and performance of ILs for CO2 capture were explored and discussed. Lastly, the challenges in ILs hybridization were also being addressed. [ABSTRACT FROM AUTHOR]

In the face of escalating global climate challenges, effective carbon dioxide (CO₂) capture techniques remain at the forefront of mitigating anthropogenic greenhouse gas emissions. This comprehensive review elucidates the latest advancements in CO₂ capture, emphasizing two predominant methodologies: absorption and adsorption. We delve into the mechanisms underlying each process, highlighting the novel materials and technologies that have emerged over recent years. For absorption, the focus is placed on the material design strategy, and identifying new materials in the class of amines, ionic liquids (ILs) and nanofluids for enhanced CO2 capture capacities and reduced energy requirements. In the realm of adsorption, the synthesis of innovative adsorbents, such as metal organic framework (MOF), organic polymers, inorganic adsorbents, silicon-based adsorbents, and biochar and byproducts from biomass with superior selectivity and stability, is explored. Additionally, the review addresses the challenges associated with each method, offering insights into potential avenues for further research. By providing a holistic overview of the current landscape of CO₂ capture, this article serves as a pivotal resource for researchers and industry professionals aiming to advance sustainable solutions to combat climate change.

The urgent need for sustainable energy solutions and greenhouse gas mitigation has driven extensive research into advanced materials and technologies. This review provides an overview of the recent developments and advancements in the synthesis and application of carbon nanotubes for the integrated hydrogen production process with carbon dioxide capture and conversion. This work highlights the key methods employed for the synthesis of carbon nanotubes, including chemical vapor deposition, arc discharge, and laser ablation methods. The structural and morphological characteristics of these nanocomposites are explored, emphasizing their influence on catalytic activity, selectivity, and stability in hydrogen production reactions. Furthermore, the role of carbon nanotubes in carbon dioxide capture and conversion is discussed. These materials serve as efficient sorbents for CO2 capture due to their high surface area and tunable surface chemistry. Moreover, carbon nanotube-based catalysts integrated into nanocomposites facilitate the conversion of captured CO2 into value-added products, such as hydrocarbons of different functionalities. The challenges and opportunities associated with hydrogen production and CO2 capture and conversion are thoroughly addressed using carbon nanotubes. In summary, these multifunctional materials hold great promise in contributing to a sustainable and clean energy future while mitigating the effects of climate change.

Direct air capture (DAC) offers a powerful strategy to counteract climate change by reducing the carbon dioxide levels in the air. Developing sorbent materials capable of sucking carbon dioxide gas continuously emitted into our atmosphere is critical. In this work, we present a functionalization strategy for a metal-organic framework (UiO-66), intending to increase the uptake and selectivity for capturing carbon dioxide at its ppm levels from the multi-component mixture of air. (3-Aminopropyl)triethoxysilane (APTES) was used to chemically modify the hydroxyl analog of UiO-66 (UiO-66-(OH)2) framework to form UiO-66-APTES. The developed UiO-66-APTES fully characterized using several analytical techniques, such as Fourier Transform Infrared spectroscopy (FTIR), Powder X-ray diffraction (PXRD), and X-ray photoelectron microscopy (XPS). The calculated BET surface areas of UiO-66-(OH)2 and UiO-66-APTES were 752 m2 g−1 and 381 m2 g−1, respectively. Although the surface area decreased, adding several aliphatic amine groups enhanced the CO2 adsorption capacity, at 298 K and 1 bar, from 42.7 cm3 g−1 to 65.6 cm3 g−1, exhibiting a ∼150 % improvement over the unfunctionalized sample. Not only was the material proven to be selective for CO2 within a CO2/N2 gas mixture with a high selectivity of 160, but it also showed a mere marginal reduction in performance (i.e., CO2 uptake capacity) after 15 cycles. Moreover, the UiO-66-APTES system was used for the dynamic separation of CO2 from air mixture, revealing its potential as an attractive adsorbent for direct air capture.