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Excessive emissions of greenhouse gases, particularly carbon dioxide (CO2), are the primary culprits behind the phenomenon of global warming, and reducing CO2 emissions has become the primary global concern for all countries. CO2 capture, utilization, and storage (CCUS) technology is a key strategy in achieving the goals of the dual carbon strategy, and carbon capture is one of the most critical technology links. However, the development of chemical absorbents have been hindered by these problems such as poor absorption rate, low absorption capacity, poor stability, high energy consumption for regeneration, and high recovery cost. Therefore, how to realize the development and industrial application of CO2 chemical absorbents with efficient capture and low energy consumption for regeneration is an extremely severe challenge to be broken through at present. Herein, the current research progress of chemical absorbents is summarized and discussed in depth, which focuses on the absorption mechanism, absorption performance, advantages, and disadvantages of various absorbents. Subsequently, the existing problems and corresponding solutions for the research system are pointed out. Finally, the future development direction of absorbents is prospected. [ABSTRACT FROM AUTHOR]

Poor-quality petroleum coke is often used as fuel because of its high carbon content and calorific value, but its combustion process will emit a lot of CO2. Using the petroleum coke chemical looping combustion (CLC) for power generation is an effective way to realize its clean utilization, but the process still faces the problem of low conversion rate of petroleum coke. Mixing petroleum coke with coal as fuel can significantly improve the reactivity of petroleum coke. Therefore, this study established a CLC power generation system with a mixture fuel of petroleum coke and coal at a mass ratio of 1:1 and coal as the only fuel. The amount of oxygen carrier circulation required for a full reaction of decomposed fuel in the fuel reactor and the air flow required for the regeneration of oxygen carrier in the air reactor were optimized. The novel system was compared with a petroleum coke CLC power generation system in terms of system efficiency, life cycle fossil energy consumption and greenhouse gas emissions. The results show that the optimum mass ratios of circulating oxygen carrier to fuel required in the petroleum coke-coal and coal CLC power generation systems are 26.43 and 24.19, while their optimum mass ratios of air to fuel required for regenerating oxygen carrier are 9.22 and 8.43. The energy efficiencies of the new CLC power plant are 36.77%, which are 8.96 and 2.20 percentage points higher than that of the CLC power plant using petroleum coke and coal as fuel alone. The life cycle fossil energy consumption and the greenhouse gas emissions of the petroleum-coal hybrid CLC power plant are 9.52 GJ/MWh and 302.76 kg CO2 eq/MWh, which are 2.56 and 0.27 GJ/MWh, 35.27 and 4.03 kg CO2 eq/MWh lower than that of petroleum coke and coal power plants alone. The energy efficiency of the power generation system can be significantly increased by mixing petroleum coke with coal to improve the combustion conversion rate of petroleum coke, while the life cycle fossil energy consumption and greenhouse gas emissions of the power generation system can be reduced.

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Mesoporous biochar (MC) derived from biomass is synthesized using a dual-salt template method involving ZnCl2 and KCl, followed by impregnation with polyethyleneimine (PEI) of varying average molecular weights under vacuum conditions to construct a core-membrane structure for enhancing carbon capture performance. The resulting MC exhibits a highly intricate network of micropores and abundant mesopores, along with defects in graphitic structures, effectively facilitating robust PEI loading. Among the PEI-modified samples, PEI-600@MC demonstrates the highest CO2 sorption capacity, achieving approximately 3.35 mmol/g at 0.1 MPa and 70 °C, with an amine efficiency of 0.32 mmol CO2/mmol N. The introduction of amine functional groups in PEI significantly enhances the sorption capacity compared to bare MC. Additionally, PEI with lower average molecular weights exhibits a superior sorption performance at low pressures but shows a reduced thermal stability compared to higher molecular weight counterparts. The area of sorption hysteresis loops gradually decreases with increasing temperature and average molecular weight of PEI. The equilibrium sorption isotherms are accurately modeled by the Langmuir equation, revealing a maximum sorption capacity of approximately 3.53 mmol/g at 70 °C and saturation pressure. This work highlights the potential of dual-salts templated biomass-derived MC, modified with PEI, as an effective, widely available, and cost-efficient material for CO2 capture. [ABSTRACT FROM AUTHOR]

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]

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.)

This work assessed the carbon dioxide capture performance by 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) procedures. 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% CO2 (by volume) mimicking a fossil-derived flue gas. according to the findings of the experimental result show the raising of the operating temperature had no appreciable impact on the effectiveness of CO2 removal in either combination. On the other hand, the efficiency of CO2 removal rises with rising amine concentration, volume percentage of amine in the solvent, and liquid flow rate; on the other hand, the efficiency of CO2 removal falls sharply with increasing gas flow rate. The maximal CO2 removal coefficients achieved by MEA + DEA and MEA + TEAM aqueous solutions under ideal circumstances are 97.9% and 91.9%, respectively. Additionally, given the experiment's operating conditions, the highest volumetric total gas-phase mass transfer coefficient was found to be 110 and 67.5 (kmol/m³ h kpa), respectively. [ABSTRACT FROM AUTHOR]

The regular increase in carbon dioxide (CO2) concentration in the atmosphere is one of the major environmental issues nowadays. In this essence, establishing some promising stratagem including CO2 capture, storage, and utilization (CCSU) is one of the options to alleviate CO2 emissions from the energy zone. CCSUs are promising techniques to capture human-generated greenhouse gases (GHGs) by controlling their release into the atmosphere. The key aspect triggers significant developments in novice materials to perform the separations. In this regard, the burgeoning class of superb porous materials (Metal–Organic Frameworks, MOFs), aiming to solve this worldwide issue, is mainly emphasized. MOFs are widely explored in carbon dioxide capturing techniques owing to their exceptional features such as crystallinity, tunable functionality, high surface area, high porosity, and superior design flexibility. The influence of functionalization, such as amine, hydroxyl, carboxylate, sulfone, and nitro, onto the surfaces of MOFs on the CO2 capture performance was also extensively overviewed. Moreover, this article provides comprehensive investigations emphasizing the different methodologies adopted for CO2 capture. [ABSTRACT FROM AUTHOR]

Copyright of Petroleum Refinery Engineering is the property of Petroleum Refinery 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.)

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]

Background and Objective: One of the major challenges in the calcium looping process is the loss of CO2 capture capacity of calcium-based sorbents during consecutive cycles due to increased sintering mechanism. This article aims to improve the performance of carbonation conversion in different cycles by employing hydration and acidification methods. Materials and Methods: Following the preparation of both CaO-based and modified sorbents, scanning electron microscopy, X-ray diffraction, and Brunauer-Emmett-Teller analyses were employed to verify the proper preparation of the sorbents and examine their structures. Subsequently, the adsorption performance of different samples was assessed using a thermogravimetric analyzer device . Results: The results of the carbonation reaction showed that the effective conversion rates for the raw and modified sorbents, employing acidification and hydration methods, at the end of the first cycle were 75%, 86%, and 73%, respectively. By the twentieth cycle, these rates decreased to 24%, 38%, and 26%, respectively. This decline indicates an improvement in the sorbent's capture capacity, attributed to the formation of calcium acetate, resulting in a more stable and porous structure. The findings from utilizing raw limestone sorbents and their modified versions through acidification and hydration techniques demonstrated a decrease in sorbent capture capacity by 69, 58, and 67% across twenty cycles. This highlights the enhanced sorbent stability achieved with the acidification method. Conclusion: Based on obtained results, acidification method can be considered as one of the most efficient approaches for improving the performance of calcium oxide sorbents. [ABSTRACT FROM AUTHOR]

To tackle the prevalent challenges encountered with polyamine-based non-aqueous absorbents (NAAs), particularly the formation of viscous products and inferior regeneration performance, this study proposed an innovative synergistic regulation strategy that integrated 2-amino-2-methyl-1-propanol (AMP) and n-propanol (NPA). Accordingly, a novel tertiary tetraethylenepentamine (TEPA)-AMP-NPA (T-A-N) NAA was devised. The optimized T-A-N maintained complete homogeneity throughout the entire CO2 absorption process and achieved an impressive CO2 loading of 1.15 mol·mol−1 while maintaining a low viscosity of merely 22.47 mPa·s. Remarkably, its absorption capacity showed little decrement after four consecutive absorption-desorption cycles, underscoring its exceptional recyclability. Within the T-A-N system, AMP underwent a reaction with CO2, yielding AMP-carbamate and protonated AMP, while TEPA engaged in CO2 absorption to form zwitterionic carbamates. During the desorption process, NPA served as a regeneration activator, facilitating the conversion of stable TEPA-carbamates into less stable alkyl carbonate intermediates, thereby enhancing the T-A-N's regeneration performance. Moreover, the T-A-N system addressed the issue of TEPA-carbamate self-aggregation into insoluble gelatinous substances by leveraging the synergistic enhancement effects between AMP derivatives and NPA. Specifically, these components effectively bound TEPA-carbamate species via robust electrostatic affinity and intermolecular hydrogen-bond interactions, inhibiting their self-aggregation and preventing the formation of insoluble products. Furthermore, T-A-N exhibited a significant reduction in both sensible and latent heat requirements, by 67 % and 82 % respectively, compared to 30 wt% MEA, highlighting its advantageous energy-saving potential for CO2 capture. Overall, harnessing the synergistic enhancement effects of AMP and NPA was conducive to the development of polyamine-based NAAs that offered superior CO2 capture reversibility, low energy consumption, and resistance to insoluble product formation.

Carbon Capture and Storage (CCS) is recognized as a potent strategy for managing the accumulation of human-generated CO2 in the atmosphere, helping to alleviate climate change’s effects. The CO2 gas is captured from the point source through methods such as pre-treating fossil fuels, oxy-fuel combustion, or post-combustion capture; thereafter; it is transported to a storage location and injected into geological formations. This article provides an overview of carbon dioxide capture and sequestration, focusing on its key principles, technologies, associated risks, and challenges. Direct Air Capture (DAC) and Scalable Modelling, Artificial intelligence (Al), Rapid Theoretical calculations SMART technologies are detailed as emerging and promising approaches to CO2 capture. Numerous pilot and commercial projects commissioned to manage carbon dioxide emissions are presented. Additionally, the paper explores approaches combining geological, geophysical, geochemical, and environmental monitoring techniques to ensure the secure and sustainable storage of CO2 underground. These are essential to address uncertainties, minimize risks, and build public confidence in CCS as a viable climate mitigation strategy. The successful deployment of these technologies on a global scale will require continued innovation, particularly in the areas of monitoring, risk management, and public engagement. Emerging technologies such as AI and SMART systems could play a crucial role in enhancing the efficiency and safety of CCS operations. However, the integration of these advancements with existing infrastructure and regulatory frameworks remains a challenge. Ultimately, a multi-disciplinary approach, combining technological, economic, and regulatory perspectives, will be vital to realizing the full potential of CCS in combating climate change.

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.

This article elaborates on the current development status of the petrochemical and new energy industries both domestically and internationally, analyzes the challenges faced by traditional petrochemical enterprises. It takes a large integrated refining and chemical enterprise as an example to propose green and low-carbon transformation by increasing the proportion of clean energy, exploring hydrogen electricity coupling applications, optimizing energy consumption structure, co-firing biomass fuels, expanding green and low-carbon products, promoting carbon dioxide capture technology, and researching plastic recycling technology. This provides a reference for the green and low-carbon transformation and development of related refining and chemical enterprises. [ABSTRACT FROM AUTHOR]

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]

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]

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]

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]

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.

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.

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.