CO2 Adsorption Capacity Research Articles

Research on the adsorption capacity and mechanism of carbon dioxide by ion exchange resin loaded with metal–organic cages

AbstractMetal–organic cages (MOCs), a novel type of porous material, have shown great potential in the adsorption and separation of CO2 gas. Zirconium‐based metal–organic cages (Zr‐MOCs) have garnered special attention because of their outstanding stability and high solubility. Nevertheless, due to its powdery nature and the tendency for easy aggregation, its application in the industrial field is limited. Here, drawing inspiration from water treatment, the inexpensive and stable ionic exchange resin D001 was employed as the supporting material for loading Zr‐MOCs, and D001‐Zr‐MOC was prepared. The adsorption capacity of D001‐Zr‐MOC for CO2 from the mixed gas (15% CO2/85% N2) under diverse loads of Zr‐MOCs, various temperatures, and different gas flow rates was investigated, and its cyclic adsorption performance for CO2 was determined. The adsorption mechanism of CO2 on D001‐Zr‐MOC was probed by means of adsorption energy, adsorption isotherm, adsorption heat, and diffusion coefficient. The results showed that the maximum CO2 adsorption capacity of D001‐Zr‐MOC was 3.96 mmol/g. The adsorption capacity decreased by merely 4.62% after 10 adsorption/desorption cycles. The adsorption energy and adsorption heat of D001‐Zr‐MOC for CO2 molecules are relatively high, which indicates that D001‐Zr‐MOC has good adsorption capacity and selectivity for CO2 molecules. The adsorption of CO2 is regarded as a typical Langmuir monolayer adsorption, and it is verified that a chemical reaction occurred between CO2 and the adsorbent. CO2 possesses a higher diffusion coefficient, and the excellent cyclic adsorption capacity of D001‐Zr‐MOC is verified.

Synthesis and characterization of advanced Ad-UiO-66@NGO composite for efficient CO2 capture and CO2/N2 adsorption selectivity.

Highly effective adsorbents, with their impressive adsorption capacity and outstanding selectivity, play a pivotal role in technologies such as carbon capture and utilization in industrial flue gas applications, leading to significant reductions in greenhouse gas emissions. This study aims to synthesize advanced composites via solvothermal methods, incorporating a defective Zirconium-based MOF and amine-functionalized graphene oxide. The main objective is to enhance the CO2 adsorption capacity of the composite and improve its CO2/N2 separation selectivity. The samples were characterized using XRD, FT-IR, TGA, FE-SEM, and nitrogen adsorption and desorption analysis. The composites' gas uptake capacity toward pure CO2 and N2 adsorption were tested at various temperatures and pressure ranges of 1-9 bar. The resulting amino-defective UiO-66/NGO composite containing 15 wt.% of amine-modified GO, displayed the highest CO2 uptake capacity of 15.13 mmol/g at 298 K and 9 bar, representing a remarkable 48% increase compared to the pristine MOF. Furthermore, isotherm and kinetic modeling showed a high level of agreement between the experimental data and the Freundlich and Elovich models, as indicated by their R2 values of 0.998 and 0.973, respectively. Moreover, the thermodynamic evaluation confirmed the exothermic and the spontaneity of the reaction. Furthermore, the adsorbent's CO2/N2 selectivity was evaluated using the ideal adsorbed solution theory, revealing a remarkable selectivity value of 148. The regenerability evaluation through cyclic adsorption experiments showed that the optimized composite maintained CO2 adsorption reversibility at over 81.50% after 55 adsorption-desorption cycles.

Long-Range Metal-Sorbent Interactions Determine CO2 Capture and Conversion in Dual-Function Materials.

Carbon capture and utilization involve multiple energy- and cost-intensive steps. Dual-function materials (DFMs) can reduce these demands by coupling CO2 adsorption and conversion into a single material with two functionalities: a sorbent phase and a metal for catalytic CO2 conversion. The role of metal catalysts in the conversion process seems salient from previous work, but the underlying mechanisms remain elusive and deserve deeper investigation to achieve maximum utilization of the two phases. Here, preformed colloidal Ru nanoparticles were deposited onto a "NaOx"/Al2O3 sorbent to prepare prototypical DFMs with controlled phases for CO2 capture and hydrogenation to CH4. Ru addition was found to double the high-temperature CO2 adsorption capacity by activating the "NaOx"/Al2O3 sorbent phase during a reductive pretreatment step. Most importantly, low Ru loadings were sufficient to ensure maximum CO2 adsorption and conversion. This was attributed to the key role of the metal-sorbent interactions, wherein Ru was required to hydrogenate strongly bound CO2 on the "NaOx"/Al2O3 sorbent to CH4 via the H2 activated on Ru. This interaction facilitated rate-determining carbonate migration and subsequent hydrogenation at the metal-sorbent interface. Overall, Ru controlled the CO2 hydrogenation reaction rate, while the "NaOx"/Al2O3 sorbent dictated the CO2 uptake capacity. By controlling metal-sorbent interactions at the molecular level, we demonstrate the critical role of the two phases and their synergy, facilitating the design of DFMs with maximum CO2 capture and conversion efficiency.

The Inhibition Effect of CO2-N2 Composite Gas on Spontaneous Combustion of Coal and the Law of Competitive Adsorption in Coal

ABSTRACT The purpose of this study is to study the effect of CO2-N2 composite gas on coal spontaneous combustion index gas and the mechanism of inhibiting coal spontaneous combustion through a competitive adsorption process and to provide theoretical guidance for adopting inert injection fire prevention and control technology in goaf to prevent coal spontaneous combustion. The programmed temperature experiment and gas chromatography were used to analyze the indicator gas after injecting different mixed ratios of CO2 and N2 inert gas. In the whole oxidation heating process (25–300 ℃), the generation of indicator gas and the peak point of gas ratio showed an apparent “Hysteresis phenomenon” and the more significant the proportion of CO2 in the composite inert gas, the more pronounced the “Hysteresis phenomenon.” Even in the CO2-dry air environment, the peak point disappears, indicating that with the injection of N2 and CO2, the coal body is in a more complex gas atmosphere, and a variety of gases are in the process of adsorption and desorption on the inner and outer surfaces of the coal body. The characteristics of the evolution of the spontaneous combustion oxidation process of coal are more complex, directly affecting the coal-oxygen interaction, thus affecting the intuitive combustion oxidation process. Molecular simulation studies the characteristics of coal molecules on CO2, N2, and O2. The results show that the adsorption capacity and adsorption energy of coal molecules on CO2 molecules are more significant than O2 and N2, and there is a competitive adsorption relationship between CO2 and N2 molecules and O2 molecules, and the competitive adsorption capacity of CO2 is more significant than N2. It shows that the composite inert gas can inhibit the coal-oxygen adsorption by competitive adsorption to displace oxygen and achieve the combustion inhibition effect. The experimental and theoretical basis for developing and improving inert gas fire extinguishing technology is provided by studying the index gas after CO2-N2 composite inert gas action and the adsorption capacity and energy in the competitive adsorption process.

Optimizing the micro/mesoporous structure of hierarchical graphene aerogel for CO2 capture by controlling the oxygen functional groups of graphene oxide

BackgroundGraphene aerogels as solid porous adsorbents are great candidates for CO2 adsorption based on their tunable hierarchical pore structure and oxygenated groups on graphene oxide can control the self-assembly and pore structure of graphene aerogels. MethodsModified Hummer's method was used to synthesize graphene oxides by using various levels of H2SO4, KMnO4, and H2O2 and 3D graphene aerogels were synthesized via the hydrothermal and freeze-drying method. FTIR, RAMAN, XRD, FE-SEM, and BET analysis were used for characterizations. Significance findingsThe effect of graphite oxidation conditions on the hierarchical porous structure of graphene aerogel for CO2 adsorption was investigated. The graphene aerogel with the high meso and micro surface areas and the highest Sm/ST value (micro surface area/total micro and meso surface area) of 33% and also, the adequate macropores was achieved using high dosage of H2SO4 in the graphene oxidation process led to the highest CO2 adsorption capacity of 1.72 mmol/g. increasing the H2O2 dosages increased the macropores in the aerogel structure and improved the value of Sm/ST leading to an increase in the CO2 adsorption capacity. The high content of KMnO4 led to low Sm/ST value and fewer macropores and decreased the CO2 adsorption capacity (1.04 mmol/g).

Effect of Aluminium Source and Water Content in the Precursor Suspensions Used for the Synthesis of Nanosized Zeolite Y on CO₂ Adsorption Capacity

Effect of Aluminium Source and Water Content in the Precursor Suspensions Used for the Synthesis of Nanosized Zeolite Y on CO₂ Adsorption Capacity

Impact of partial regeneration method on the reduction of CO2 desorption energy

Amine-functionalized solid materials have shown efficacy for low-concentration CO2 environments; however, their regeneration is often hindered by slow desorption kinetics at low temperatures. To address this, an innovative approach termed “The Partial Regeneration Method” is introduced as a driving method to enable low-temperature regeneration of CO2 adsorbents at low concentration levels. Analysis of desorption kinetics mechanisms reveal that at low temperatures, CO2 molecules exhibit reduced kinetic energy and intraparticle diffusion coefficients. Furthermore, as it approaches chemical equilibrium temperature, the re-adsorption reaction rate increases. The partial regeneration method which selectively targets CO2 molecules with low re-adsorption rates could be more effective in a such low temperature conditions. This method involves intentionally halting regeneration midway and proceeding to the next adsorption process. Experimental application of specific energy requirements and scenario analysis demonstrated a 50.7% decrease in energy consumption compared to the conventional methods. By optimizing amine loading to reduce excessive re-adsorption, the shortened cycle period compensates for the decreased adsorption per cycle. Increasing the number of cycles led to a 97.5% improvement in CO2 adsorption capacity over a one-month period. Thus, when faced with unavoidable inefficient low-temperature regeneration conditions, the proposed partial regeneration method emerges as a promising solution for minimizing energy consumption.

Hollow core-shell heterojunction TAPB-COF@ZnIn2S4 as highly efficient photocatalysts for carbon dioxide reduction.

The conversion of carbon dioxide (CO2) into carbon-neutral fuels using solar energy is crucial for achieving energy sustainability. However, the high carrier charge recombination and low CO2 adsorption capacity of the photocatalysts present significant challenges. In this paper, a TAPB-COF@ZnIn2S4-30 (TAPB-COFZ-30) heterojunction photocatalyst was constructed by in situ growth of ZnIn2S4 (ZIS) on a hollow covalent organic framework (HCOF) with a hollow core-shell structure for CO2 to CO conversion. Both experimental studies and theoretical calculations indicate that the construction of heterojunctions improves the efficiency of carrier separation and utilisation in photocatalysis. The yield of photoreduction of CO2 to CO by the TAPB-COFZ-30 heterojunction photocatalyst reached 2895.94 μmol g-1 with high selectivity (95.75%). This study provides a feasible strategy for constructing highly active core-shell composite photocatalysts to optimize CO2 reduction.

Performance of activated carbon derived from tea twigs for carbon dioxide adsorption

Activated carbon from agro-industrial waste, namely tea twigs derived from the processing of Camellia Sinensis branches, using a potassium hydroxide activator for CO2 adsorption has been conducted in this study. Various carbonization temperatures (4000C and 5000C) and heating times of 1 hour and 3 hours were used in this study. The concentration of potassium hydroxide (40% and 60%) and the ratios of activator solutions to carbon precursor made from pyrolysis of tea twigs (2:1 and 4:1) were varied for the chemical activation process. The effectiveness results of the obtained activated carbon were characterized through using Brunauer-Emmett-Teller analyzer and Temperature Programme Desorption-CO2 to determine the surface area and capacity maximum of CO2 adsorption. The optimum condition for the synthesis of activated carbon that produces high surface area was obtained at sample CCS 400/1 A2B1 where biochar carbonized at temperature of 400°C kept for 1 hour with a ratio of activator solution and precursor 4:1 using KOH concentration of 40%. The highest surface area was obtained 1,403 m2 g-1 with pore volume 0.9 m2 g-1 and pore size 1.11 nm and proved the presence of microporous areas in produced activated carbon. The maximum CO2 adsorption capacity obtained in this study was 5.1573 mmol g-1. This result could be related to the higher amount of microporous present in the activated carbon that facilitates the access of CO2 to the active sites at the pores of activated carbon.

Carbon dioxide capture using functionalized multi-wall carbon nanotubes by EDA

Carbon dioxide (CO2) is the primary factor considered to be responsible for global warming. CO2 capture technology has been considered an important issue to decrease greenhouse gas emissions. The current research investigates the functionalization of Multi-Wall Carbon nanotubes (MWCNTs) by Ethylenediamine (EDA) solution which is used for CO2 capture at various operating conditions. Surface functionality groups and morphology of MWCNTs and physical properties were analyzed by X-ray diffraction (XRD), Fourier Transforms Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), surface area Brunauer Emmett and Teller (BET). The physical and chemical properties of CNTs have changed after the functionalization process, which enhances MWCNTs adsorption for CO2 gas. According to the study's results, during the functionalization process, amine groups bound to carbonaceous surfaces created CO2 adsorption sites on multi-walled CNTs, increasing the adsorption capacity of MWCNTs. The CO2 adsorption capacity was determined by volumetric technique at temperatures from 309 to 333 °K and a pressure of 1 to 7 bar. The exothermic nature of the adsorption process was indicated by the decreasing of CO2 adsorption capabilities via MWCNTs and MWCNTs-EDA with temperature rising. The results showed that the MWCNTs-EDA are a potential low-temperature adsorbent for CO2 capture. In addition, 0.6968 mmol g−1 of CO2 was adsorbed by MWCNT-EDA at 309 °K, while raw MWCNT adsorbed only 0.3428 mmol g−1 at the same condition. Both the Freundlich and Langmuir adsorption isotherms were used to model the experimental data, with the conclusion being that the Freundlich model fits the data well.

Building a Co-Salen-Immobilized Porous Organic Polymer Catalyst for CO2 Cycloaddition.

The CO2-epoxide addition to cyclic carbonate is of great significance but usually requires high temperatures and CO2 pressures. Herein, a spirobifluorene-based porous organic polymer catalyst is designed with a Co-salen complex immobilized on the backbone (ST-CoSalen-POP) to enable CO2 fixation under mild conditions. ST-CoSalen-POP possesses a high Co-loading content (9.35 wt%), a large pore volume, and high CO2 adsorption capacity. This catalyst achieves a 96% yield in the cycloaddition of CO2 with epoxides at 25°C and 0.1MPa CO2 pressures. Moreover, ST-CoSalen-POP also offers the advantages of wide adaptability over epoxide substrates and high structural stability for three consecutive cycles. This study presents a novel catalytic approach for promoting CO2 fixation, offering a significant advancement in the efficient synthesis of fine chemicals.

Relationship Between Electronegativity of the Extra-Framework Cations and Adsorption Capacity for CO2 Gas on Mordenite Framework.

Synthetic mordenite is widely used as a molecular sieve, adsorbent, and catalyst. To enhance these functionalities, it is crucial to understand the ion-exchange properties and cation-exchange sites of the zeolite. In this study, we analyzed the structural changes in fully Cs-, Sr-, Cd-, and Pb-exchanged mordenite by using synchrotron X-ray powder diffraction under ambient conditions. Rietveld structure refinement revealed that the Cs+ cation is predominantly located near the 8-membered ring (8MR) due to its low electronegativity and hydration energy. In contrast, divalent cations such as Sr2+ and Cd2+ cations, with higher hydration energies compared to monovalent cations, are present as hydrated ions at the center of the 12-membered ring along the c-axis (12MRc). Pb2+ ions, due to their higher electronegativity than the framework atoms, exhibit a strong affinity for the electron cloud of framework oxygen atoms, which positions them close to the wall of the 12MRc. The observed differences in the locations of the extra-framework cations are attributed to electrostatic and hydration effects. Furthermore, the CO2 adsorption capacity was assessed based on the type and site of exchangeable cations. The findings indicate that an increase in the CO2 adsorption capacity correlates with the number of cations that can effectively interact with CO2.

Photo‐triggered modulation of cuprous active sites in metal–organic frameworks for manipulable carbon monoxide capture

AbstractPhotoresponsive adsorbents have garnered widespread interest on account of their customizable performance under light exposure. However, reported adsorbents of this kind are predominantly engineered to modulate weak interactions between adsorbates and adsorbents via steric hindrance or structural changes. The development of smart adsorbents possessing strong yet adjustable active sites for controllable gas capture presents a significant challenge. Here, we introduced strong active Cu+ sites into an azobenzene‐modified MOF‐808 metal–organic framework to create a smart π‐complexation adsorbent. The Cu+ sites can selectively interact with CO through π‐complexation. This design enables controlled CO capture through light‐regulated interactions between the active sites and the azobenzene groups, achieving up to a 31% variation in CO adsorption capacity. Density functional theory calculations indicate that the transformation of azobenzene from the trans to the cis configuration adjusts the surface electrostatic potential near CuCl, reducing Cu+ activity. This approach paves the way for target‐specific smart adsorption materials.

Improving CO2 Fixation with Epoxides by Replacing Zirconium by Hafnium in UiO66 MOFs

AbstractThe impact of replacing Zr4+ with Hf⁴⁺ as the metal site on CO₂ adsorption and catalytic activity in CO₂ fixation reaction with epoxide under mild conditions was investigated in UiO66‐NH₂ grafted with carbodiimides N,N′‐dicyclohexylcarbodiimide (DCC) and N,N′‐diisopropylcarbodiimide (DIC) (UiO66(M)‐DCCBr and UiO66(M)‐DICBr; M = Zr and Hf). Leveraging on Hf⁴⁺’s greater oxophilicity and stronger M—O bonds, Hf‐based UiO66‐NH2 materials exhibited increased CO₂ adsorption capacity, influencing the catalytic performance in CO₂ fixation with epoxides. The materials were characterized by multiple techniques such as PXRD, FTIR, TGA, SEM, elemental analysis, as well as N₂ and CO₂ adsorption equilibrium measurements. UiO66(Hf)‐DCCBr and UiO66(Hf)‐DICBr demonstrated superior activity compared to their Zr‐based counterparts with high yield and TOF (14.6 and 11.9 h⁻¹, respectively) under milder conditions (0.1 MPa, 90 °C, 16 h, co‐catalyst‐free and solvent‐free). These findings underscore the pivotal role of unsaturated metal sites in enhancing the catalytic efficacy of guanidinium ionic UiO66‐NH₂ materials. Moreover, these catalysts exhibit excellent thermal stability and can be recycled and reused at least five times without a noticeable reduction in their catalytic efficiency.

Preparation of Graphene Using Rice Husk via Pyrolysis Technique for CO<sub>2</sub> Adsorption

Graphene is the only carbon allotrope in which every carbon atom is densely connected to its neighbours by an electronic cloud, raising various quantum physics concerns. In recent years, many researchers have focused their efforts on developing more efficient methods for synthesizing graphene. However, only few methods can simultaneously synthesize mass-produced, cost-effective, and high-quality graphene. In this study, we are emphasizing the use of rice husk (RH) as the raw material to prepare graphene by using two-step pyrolysis. Zinc chloride (ZnCl2) is an example of an activating agent that is used to improve the efficiency of the synthesis of graphene from rice husk. After conducting pre-treatment of rice husk, the first stage of pyrolysis was conducted by varying the ratio of ZnCl2 to the RH (1:1, 2:1, 3:1) at a carbonization temperature of 500 °C for 1 hour, followed by second-stage pyrolysis under 900 °C for 90 minutes and post-treatment. The findings of the characterizations, which included yield analysis, scanning electron microscopy (SEM) and Raman spectroscopy, Brunauer-Emmett-Teller (BET), and CO2 adsorption analysis, revealed the impacts of the ZnCl2 as activating agent, on the yield and graphitic structure of graphene and the potential application of graphene as a CO2 adsorbent. Raman spectroscopy confirmed the graphitic properties of graphene synthesized in all samples with RH1:1 produced the best quality of graphene due to its low ID/IG intensity ratio (0.8913) and the highest I2D/IG intensity at 0.24. In addition, RH1:1 exhibited the highest surface area, whereby the highest total pore and micropore volume is contributing to the highest CO2 adsorption capacity of 8.73 mmol/g. This proves that the activating agent ratio has significant effects on the graphene quality produced from rice husk as well as the adsorption performance.

Preparation of MgAl‐LDH/halloysite composite materials for efficient CO2 adsorption

AbstractBackgroundCO2 emissions have had negative impacts on various aspects of life and the environment, making the development of materials with high CO2 adsorption performance crucial.ResultIn this study, halloysite nanotubes (HNTs) were used as a carrier to prepare MgAl layered double hydroxide (LDH) via a convenient coprecipitation method, resulting in MgAl‐LDH/HNT composite material, which was then evaluated for its CO2 adsorption performance. The physicochemical properties of the composite material were characterized using various methods. Results showed that the 1:1 ratio MgAl‐LDH/HNT composite exhibited superior material structure, with a specific surface area reaching 178.24 m2 g−1. In CO2 adsorption performance tests, the 1:1 MgAl‐LDH/HNT composite showed the best adsorption performance, with a CO2 adsorption capacity of 3.91 mmol g−1. This adsorption process includes physical adsorption and chemical adsorption. Kinetic analysis results indicate that the adsorption process is mainly dominated by physical adsorption. The material also demonstrated good performance in cyclic stability tests, maintaining a regeneration efficiency of over 94% after six cycles.ConclusionThe MgAl‐LDH/HNT material has good properties and stability. This provides an effective pathway and direction for the development of new adsorbents with higher CO2 adsorption performance. © 2024 Society of Chemical Industry (SCI).

Synthesis of Waste-Derived Geopolymer–Zeolite Composite with Enhanced CO2 Adsorption Capacity

Carbon dioxide levels in the atmosphere are related to global warming and climate change. Materials to be used for CO2 capture are an important factor in assisting humanity in overcoming this challenge. The goals of this study are to look into the synthesis of adsorbents from red mud (RM), fly ash (FA), and metakaolin (MK). The initial composition was chosen to induce in situ crystallization of zeolites dispersed together with a geopolymer matrix. Two aging steps were used, which combined temperature (25; 95 °C) and atmosphere (air; water). The MK + FA system crystallized zeolite sites dispersed throughout the geopolymer matrix. These crystals were identified as faujasite-Na. They were responsible for the surface area ranging from 23.2 to 238.4 m2.g−1, and CO2 adsorption from 0.83 to 2.32 mmol.g−1 at 35 °C and 1 atm. The best results were obtained by first aging at 95 °C for 120 h, followed by water aging at 25 °C for 120 h.

Covalently Grafting of Ethylenediamine onto a 2D Sub‐stoichiometric COF for Enhanced CO2/N2 Separation†

Comprehensive SummaryThe post‐synthetic modification of two‐dimensional sub‐stoichiometric covalent organic frameworks (COFs) for gas separation, particularly for the efficient removal of CO2 from CO2/N2 mixtures, is an area of growing interest yet remains relatively unexplored. In this study, we report the precise tuning of functional groups in sub‐stoichiometric COFs to enhance CO2 capture performance. A sub‐stoichiometric COF with free aldehyde groups (HPCOF) was designed and synthesized, followed by covalent modification via ethylenediamine (EDA) grafting, yielding HPCOF‐EDA. This post‐modification strategy significantly increased CO2 adsorption capacity (55.7 cm3·g–1 at 298 K and 1 bar) and CO2/N2 selectivity (58), primarily attributed to the formation of additional N—H···O interactions. These findings demonstrate the potential of functional engineering to broaden the application prospects of sub‐stoichiometric COFs in gas adsorption and separation technologies.

Preparation of an Adsorbent Derived from Canola Hull by Slow Pyrolysis for Effective Carbon Dioxide Adsorption

Canola hull was proposed as a valuable precursor for activated carbon production, due to its abundance, low cost, and economic viability. This study aimed to develop a waste-based biosorbent from canola hulls by slow pyrolysis for effective CO2 capture. The biochar was synthesized from the canola hull using a fixed-bed tubular reactor through slow pyrolysis at various temperatures. The optimum biochar was activated using KOH as a chemical activating agent at different impregnation ratios. The biochar and activated carbon were characterized by elemental analysis, thermogravimetric analysis, surface textural analysis and FT-IR analysis. All the activated carbon samples with impregnation ratios of 0, 0.2, and 0.4 were screened at a total inlet mass flow rate of 100 mL/min (15% CO2 + 85% N2). Activated carbon prepared with an impregnation ratio of 0.4 (0.4AC) with a specific surface area of 1112 m2/g exhibited the highest adsorption capacity of CO2 (2.9 mmol/g) at 25°C under ambient pressure when the feed gas was 15% CO2). 0.4AC was chosen for further study at different feed compositions. The breakthrough curves were analyzed for the compositions 5%, 15% and 25% CO2 in feed, and the effects of adsorption parameters were discussed. The maximum CO2 uptake of the canola hull based activated carbon (0.4AC) is 13.0 mmol/g at ambient pressure and 25°C, with 100% CO2 inlet. Adsorption isotherm and kinetic were studied on the 0.4AC adsorbent. The canola hull based adsorbent with desirable physiochemical and surface textural properties can work as an effective adsorbent for CO2 capture.

Advanced Solid Amine Adsorbents with Exceptional Oxidative Stability for Efficient Capture of Low-concentration CO2.

Solid amine adsorbents designed for capturing trace amounts of carbon dioxide (CO2) offer a promising approach. However, developing solid amine adsorbents that concurrently exhibit high oxidative stability and superior CO2 adsorption capacity remains a significant challenge. Here, ED-PEI/PEG@FS-TBP, an innovative and highly stable CO2 adsorbent is introduced. This material involves the functionalization of polyethyleneimine (PEI) with 1,2-epoxydodecane (ED), effectively transforming primary amines into secondary amines, thereby mitigating urea formation. Furthermore, the chelator embedded within the fumed silica (FS) supports sequestering metallic impurities that would otherwise catalyze oxidation reactions. The integration of polyethylene glycol (PEG) forms hydrogen bonds with PEI, effectively barricading oxygen access and safeguarding against PEI oxidation. ED-PEI/PEG@FS-TBP achieves an outstanding CO2 adsorption capacity of 1.49mmolg-1 at 298 K and 0.0004bar. Notably, after 20 days of oxidative aging in an environment with 75% relative humidity and 383 K, ED-PEI/PEG@FS-TBP exhibits remarkable oxidative stability, with a deactivation rate constant (kdeact) 93% lower than that of PEI@FS. Its excellent oxidative stability, cycling stability, and high thermal stability, underscore its unparalleled potential for the capture of low-concentration CO2.