Carbon Dioxide Adsorption Research Articles

Research on comprehensive characterization of deep coal full aperture structure and burial depth effect

With the increasing depletion of shallow mineral resources, deep mining has become important; however, basic research on deep resource development remains insufficient, and basic laws are unclear. In particular, comprehensive research on the pore structure characteristics of deep coal bodies at different scales is needed, and how burial depth affects pore structure characteristics should be investigated. Herein, this study performed mercury intrusion porosimetry, liquid nitrogen method, and low-temperature carbon dioxide adsorption method to systematically determine the pore structure characteristics of deep coal and comprehensively analyze coal pore complexity based on the Menger Sponge, Frenkel–Halsey–Hill (FHH), and density function models. The influence of depth on coal pore structure was also discussed. In the study zone, the stage pore volume was mainly concentrated in the macroporous (43.6–83.4%) and mesoporous Sect. (16.3–54.7%) and sparsely distributed in the microporous Sect. (0.3–2.1%). The accumulated pore volume decreased with an increase in coal sample burial depth, with a gentle curve in the micropore section and obvious fluctuations in the mesopore and macropore sections. The main distribution of stage surface area was in the mesoporous Sect. (79.5–91.8%), followed by the microporous (7.8–19.8%) and macroporous Sect. (0.3–0.6%). The accumulated surface area curve fluctuated greatly in the mesoporous and microporous sections, and that in the macroporous section was relatively flat with limited distribution. According to the Menger Sponge model, the fractal dimensions of the macroporous (Dmac) and mesoporous (Dmes) sections ranged from 2.4 to 2.8 and 3.7–3.9, respectively, with obvious fractal characteristics; Dmes was higher than Dmac, indicating that the structure of small and medium-sized micropores is more complex and irregular. The fractal dimension in the high-pressure zone of the FHH model (DHP) ranged from 2.8 to 2.9, and that in the low-pressure zone (DLP) ranged from 2.1 to 2.4, indicating that coal pore structure under low-pressure conditions is relatively simple. The fractal dimension of the density functional model ranged from 2.5 to 3.0, closer to 3, indicating that the pores are relatively complex and rough. A single-variable analysis revealed a strong correlation between burial depth and aperture parameters. This is the first study to reveal the relationship between burial depth and aperture parameters. Moreover, characterization of critical depth based on aperture structure was performed, providing a feasible method for quantifying “critical depth.” Our results enrich our understanding of the structure of deep coal bodies and serve as a reference for deep mining engineering.

Polyethylene Polyamine-Modified Chitosan Aerogels: Enhanced CO2 Adsorbents with Lamellar Porous Structures

Due to the continuous growth of global carbon dioxide emissions, the development of cost-effective carbon dioxide capture technology has attracted extensive attention. Amino-modified chitosan aerogels with lamellar porous structures are good candidates as carbon dioxide adsorbents because of their degradable properties and low energy consumption. Polyethylene polyamine-modified chitosan aerogels (PEPA-CSs) were prepared through a process of crosslinking and freeze-drying using a chitosan solution, polyethylene polyamine (PEPA), and epichlorohydrin (ECH) as raw materials. The amino group of PEPA was proven to be successfully grafted on the chitosan surface by FITR and XPS. The SEM and TEM analysis showed a rich three-dimensional porous structure and a good rigidity and bearing capacity of the PEPA-CS. The adsorption capacity was significantly increased by PEPA grafting with a maximum value of 1.59 mmol/g at 25 °C and 1 bar through both physical and chemical interactions, which indicates a potential for broad application prospects in industrial CO2-capture applications.

Phenolic Resin-type Microporous Organic Polymers for High-Performance Carbon Dioxide Adsorption.

Three new types of Si-centered porous organic polymer (Si-POPs) were successfully prepared using phenolic resin-type chemistry to form C-C bonds. This new family of microporous Si-POPs manifests as uniform, microporous, spherical particles with a high specific surface area. Notably, Si-POPs were engineered to possess varying numbers of hydroxyl (-OH) groups by altering the monomer in the synthetic process. Among these materials, the variant with the highest number of hydroxyl groups exhibited ultra-high CO2 adsorption capacity, reaching up to 4.3 mmol g-1 at 273 K and 1.0 bar, which surpasses the performance of most porous polymers. Furthermore, Si-POPs also demonstrated remarkable selectivity adsorption for carbon dioxide over nitrogen (17-50, IAST at 273 K and 1.0 bar). This study not only highlighted the superior CO2 adsorption properties of Si-POPs but also explored their potential application in selective gas adsorption.

Efficacy of zirconium hydroxide and cerium hydroxide for carbon dioxide adsorption and subsequent ethylene urea synthesis

Efficacy of zirconium hydroxide and cerium hydroxide for carbon dioxide adsorption and subsequent ethylene urea synthesis

Dual spatial region flexible chlorine based ionic hypercrosslinked polymer synergistically adsorb formaldehyde and carbon dioxide

Efficient adsorption and purification of low concentration volatile organic compounds (VOCs) and carbon dioxide (CO2) mixture in high-humidity environments remain a daunting challenge for researchers. In this study, a dual spatial region synergistic adsorption strategy was proposed to achieve synchronous and efficient capture of formaldehyde and CO2 on flexible chlorine (Cl) based ionic hypercross-linked polymer (Cl-IHCP). Through the ordered self-assembly of ionic monomers, the array-distributed free Cl, terminal Cl, and pyrrole nitrogen (N) sites were integrated into the skeletal network of Cl-IHCP and formed ultra-microporous environment with two different adsorption regions. Different adsorption regions exhibited varying adsorption affinities for formaldehyde and CO2 molecules on three sites, thereby weakening their competitive adsorption and achieving high adsorption for both. Besides, the strong binding force of formaldehyde and CO2 molecules in different regions makes the skeleton-responsive swelling of Cl-IHCP, and created new adsorption microenvironments for the other adsorbate. This manner considerably enhanced the adsorption capacity of Cl-IHCP for formaldehyde and CO2 in mixed-component, increasing by approximately 45% and 70% respectively compared to single component formaldehyde and CO2. These fascinating properties enabled Cl-IHCP to synergistically adsorb formaldehyde and CO2 mixtures in high humidity environments. This study innovatively proposed a simple and cost-effective strategy for removing VOCs and CO2 under high humidity, providing a feasible solution for green air purification technology.

Enhanced capacity in cellulose aerogel for carbon dioxide capture through modified by metal-organic framework.

Microporous metal-organic frameworks (MOF) exhibit excellent carbon dioxide (CO2) adsorption performance and selectivity for CO2/N2 separation. However, the challenges associate with the recycling and reuse of MOF powders hinder their practical applications. To address these limitations, a flexible and stable MOF-based composite material was designed by immobilizing UiO-66(Zr)-(OH)2 onto cellulose nanofibers (CNFs) aerogels (MOF-CNFs), which featured high porosity. Experimental results showed that MOF-CNFs exhibited sensitivity to CO2 adsorption at low pressure and achieved a CO2 adsorption capacity of 1.8 mmol/g at 0.15 bar under the 298 K. This represented an 8.8 % improvement compared to the MOF. Ideal adsorbed solution theory (IAST) calculations indicated selectivity for CO2/N2 mixtures (molar ratio 15:85) as high as 66. After eight adsorption-desorption cycles, the CO2 adsorption capacity retained 97 % of its initial value. These results highlighted the significant potential of MOF-CNFs as reusable and highly efficient CO2 separation adsorbents for practical applications, such as flue gas capture.

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.

Microporous metal-organic framework of Gd-PTC as efficient carbon dioxide adsorbent

Microporous metal-organic framework of Gd-PTC as efficient carbon dioxide adsorbent

Experimental Investigation of the Effect of Microstructure on Coalbed Methane Adsorption Characteristics Affected by Chemical Solvents.

Coalbed methane (CBM) reservoir modification based on chemical solvent treatment could change the coal microstructure, which further affects the adsorption capacity and flow characteristics of this clean energy. Coal samples were extracted by tetrahydrofuran (THF), carbon disulfide (CS2), and hydrochloric acid (HCl). Low-pressure nitrogen adsorption, carbon dioxide adsorption, Fourier transform infrared spectroscopy, and methane isothermal adsorption test were adopted. The variations of pore structure and chemical composition in coal were evaluated by density functional theory, Barrett-Joyner-Halenda model, and peak fitting method, and their impacts on methane adsorption characteristics were studied. Results show that (1) the micropores less than 2 nm show a bimodal distribution. After acidification, micropore specific surface areas of coal samples I and II increase by 16.79% and 11.72%, respectively, while that of coal sample III-HCl decreases by 4.29% closely related to carbonate and silicate minerals in coal. Microporous specific surface areas of sample II-CS2 and III-CS2 affected by solvent rise by 4.28% and 4.17%, respectively. (2) Among the three original coal samples, the highest level of OH-OH hydrogen bonds content is observed. Solvents have a tendency to interact with -CH2 groups, which shorten the length of fat chains and increase the number of branched chains. THF tends to dissolve C-O-C groups and carbonyl C═O groups. Following CS2 treatment, samples II and III show 38.42% and 47.76% decrease in aromatic C═C area, respectively. (3) The methane adsorption capability in three coal samples is I > III > II. Except for sample I-HCl and sample III-THF, other coal samples have a lower methane adsorption capability than raw coal. Methane adsorption is reduced not just by a decrease in the number of micropores but also by aliphatic groups, aromatic structures, and oxygen-containing structures. Relevant results could deliver guiding significance for understanding methane adsorption and flow characteristics in coal after chemical solvent modification.

Preparation of a Novel ACS/CS/EDTA Composite from Sugarcane Bagasse for Enhanced Adsorption of Carbon Dioxide

This study presents a simple method for the production of activated carbon (ACS) from sugarcane bagasse. To increase the CO2 adsorption efficiency, the ACS/CS/EDTA composite was prepared by modifying ACS with ethylenediaminetetraacetic acid (EDTA) and chitosan (CS). The as-prepared materials were characterized by X-ray Diffraction (XRD), Field Emission Scanning Electron Microscope (FE-SEM), Energy Dispersive X-ray Spectroscopy (EDS), High Resolution – Transmission Electron Microscope (HR-TEM), Fourier Transform Infra-Red (FT-IR), and N2 adsorption/desorption isotherms. The obtained ACS is an amorphous and porous material and contains both micropores and mesopores. The micropore volume, mesopore volume, Brunauer–Emmett–Teller (BET) surface area and average pore width of the ACS are 0.112 cm3/g, 0.193 cm3/g, 354.8 m2/g and 55.7 Å, respectively. The dispersion of EDTA and CS on the activated carbon leads to a deterioration of the structural properties while it increases the aggregation of the ACS/CS/EDTA composite. The performance of the materials was evaluated by CO2 adsorption at ambient pressure. The effects of EDTA, adsorption temperature and gas composition were also investigated in detail. In addition, the durability of the composite was evaluated through the adsorption and desorption cycle. Copyright © 2024 by Authors, Published by BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Numerical Analysis of the Influence of Air Flow Rate on the Development of the Porous Structure of Activated Carbons Prepared from Macadamia Nut Shells.

This paper presents the numerical analysis of the influence of air flow rate on the porous structure development of activated carbons prepared from macadamia nut shells. The analyses based on nitrogen and carbon dioxide isotherms were carried out by the new numerical clustering-based adsorption analysis method. Therefore, it was possible to evaluate the porous structure with high precision and reliability. In particular, the results obtained showed that activated carbon prepared at an air flow rate of 700 cm3/min has the highest adsorption capacity with respect to this adsorbate, but with surface heterogeneity. On the other hand, numerical analysis based on carbon dioxide adsorption isotherms showed that the activated carbon with the highest adsorption capacity towards carbon dioxide is the sample obtained at an air flow rate of 500 cm3/min. The analyses conducted have shown that too high an air flow rate causes a violent oxidation reaction, leading to uncontrolled burning of the carbonaceous substance and destruction of the structure of the smallest micropores.

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.

High-Pressure Gas Adsorption on Covalent Organic Framework CTF-1

Triazine-based covalent organic framework CTF-1 was synthesized via polymerization of 1,4-dicyanobenzene in the presence of zinc chloride. Two different methods of the post-synthesis treatment of the obtained material were compared. It was demonstrated that ultrasonication effectively removes impurities from CTF-1. Adsorption of hydrocarbon gases (methane and ethane) and carbon dioxide was measured at 298 K in a wide pressure range for the first time. Ideal selectivity and IAST values for methane/ethane and methane/CO2 pairs were calculated from the obtained isotherms.

Advancements and Challenges in Adsorption-Based Carbon Capture Technology: From Fundamentals to Deployment.

Carbon dioxide (CO2) adsorption on solid sorbents represents a promising technology for separating carbon from different sources and mitigating anthropogenic emissions. The complete integration of carbon capture technologies in various industrial sectors will be crucial for a sustainable, low-carbon future. Despite developing new sorbents, a comprehensive strategy is essential to realize the full potential and widespread adoption of CO2 capture technologies, including different engineering aspects. This study discusses the pathway for deploying adsorption-based carbon capture technology in fundamental material science aspects, thermo-physical properties behavior at the molecular level, and industrial pilot scale demonstrations. When integrated with process simulation and economic evaluations, these techniques are instrumental in enhancing the efficiency and cost-effectiveness of the capturing processes. While advancements in adsorption-based carbon capture technologies have been notable, their deployment still encounters significant hurdles, including technical, economic, and environmental challenges. Leveraging hybrid systems, renewable energy integration, and the strategic application of emerging machine learning techniques appear promising to address global warming effectively and will consequently be discussed in this investigation.

Synergistic Interaction-regulated selective carbon dioxide adsorption of amino-functionalized porous organic polymers

Synergistic Interaction-regulated selective carbon dioxide adsorption of amino-functionalized porous organic polymers

Synthesis of activated carbon/MgO monolith using Astragalus material for carbon dioxide adsorption

ABSTRACT Adsorption technology has emerged as a viable approach to reducing CO2 emissions. Generally, activated carbons-based adsorbents, in particular, are promising due to their abundant availability, tunable physicochemical properties, and suitability over a wide temperature range. In this study, activated carbons (ACC) modified with magnesium oxide (MgO) was evaluated for carbon dioxide capture in an adsorption process. ACC, the feedstock, was produced using the fast pyrolysis of Astragalus. The availability and cheapness of the Astragalus material next to MgO led to the synthesis of a new compound called ACC/MgO. The aim of this new synthetic compound was to achieve a cost-effective approach to carbon dioxide adsorption. This approach somehow shows the innovation of the work. Another innovation is adsorbent moulding (monolith) and its industrialisation. The synthetic material underwent various analyses, including FTIR, XRD, SEM, BET, and EDX. Fifteen experiments were designed using the response surface methodology-Box-Behnken (RSM-BBD) design to determine the maximum carbon dioxide adsorption capacity (ADC). One of the optimal points, with the highest carbon dioxide ADC (1.355 mmol/g), was determined at an initial MgO loading of 13.26 wt.%, an average ACC particle size of 0.58 mm, and a Polyvinyl alcohol (PVA) content of 6.34 wt.%. Kinetic models and isotherm models were employed to analyse the adsorption data. The findings indicated that the entire adsorption range could be described by employing the fractional-order model. Investigation into the diffusion mechanism revealed that both film diffusion and intraparticle diffusion predominantly governed the rate-limiting steps. The adsorbent exhibited favourable regeneration at lower temperatures and demonstrated consistent regenerability following seven cycles of adsorption and regeneration. This research demonstrated that ACC modified with MgO is a suitable adsorbent due to its high capacity and efficiency in carbon dioxide capture.

Gas Adsorption on the Co2Te3 Monolayer: Density Functional Theory Study.

We report a numerical investigation of the chemical adsorption of acetone and carbon dioxide gases by a cobalt telluride (III) 2D layer. Calculations were performed using first principles calculations within the density functional theory to evaluate the adsorbed gas impact on the material's conductivity. The adsorption of carbon dioxide was found to significantly affect the Co2Te3 monolayer electronic structure and its electrical conductivity, which is not observed in the case of acetone. This letter demonstrates that the calculated bond formation energy for carbon dioxide is approximately 2 times higher than that for the acetone. It proved that the quasi-2D cobalt telluride (III) could be introduced as a selective electrochemical sensor for carbon dioxide in quick medical diagnoses and other technological applications.

Characteristic Analysis of Indonesian Low and Medium Rank Coals and Their Influence on Carbon Dioxide Adsorption Capacity

Indonesia has great deep-seated coal potential , such as Lakat coal and Muaraenim coal, which can be utilized as a medium for Carbon Capture and Storage (CCS). These coals vary in characteristic which affects their ability to adsorb or store carbon dioxide gas (CO2). The moisture content of the Lakat coal is less than that of the Muaraenim coal, while the ash content of Lakat coal is 4-5 times higher than the Muaraenim coal. Lakat coal contains more vitrinite content than Muaraenim coal, while Muaraenim coal contains more inertinite content than Lakat coal. The CO2 gas adsorption capacity of Muaraenim coal is 37.62 cc/g which higher than Lakat coal (31.56 cc/g) on dry ash-free basis. The adsorbed CO2 is negatively correlated with vitrinite reflectance, ash content, and moisture content in both coals. The correlation between maceral composition (vitrinite and inertinite content) and adsorbed CO2 content differs between these coals. These analyses will support the CCS/CCUS study in deep seated coal seams by providing the information of CO2 maximum holding capacity in coal and their relationship to its chemical and organic composition.

Shining a Light on Osmotic Energy: Innovating Power Generation with Light-Responsive Covalent Organic Frameworks

The growth of global demand for energy has been increasing, making the energy crisis a worldwide issue. Osmotic energy, characterized by its utilization of an ionic concentration gradient to generate power through an ion-selective membrane, has emerged as a promising avenue. However, the osmotic energy harvesting performance typically suffers from ab imbalance between ion selectivity and permeability. Here, we report a promising light-responsive covalent-organic framework (COF)-based ion-selective membrane for light-enhanced osmotic energy harvesting. We show that benefiting from rich sub-2 nm ion channels, the membrane can generate a high osmotic power density than the commercial benchmark (5 W/m2). Furthermore, the power can be further improved significantly through UV light radiation. We also demonstrate that the membrane can extract energy existing in a concentration gradient created by carbon dioxide (CO2) adsorption, and the performance can be remarkably enhanced by light exposure. This work triggers the hopes for practical osmotic energy conversion from seawater/river water and CO2 adsorption using novel light-responsive COF-based membranes.

Regulating the Performance of CO2 Adsorbents Based on the Pyrolysis Mechanism of Self-Sacrificial Templating Agents.

Previous research has proven that the pore shape and nitrogen group content of adsorbents play essential roles in determining their carbon dioxide (CO2) adsorption performance. In this article, a series of nitrogen-doped porous carbon materials were prepared for CO2 adsorption by varying the proportion of carbon nitride, the pyrolysis temperature, and the activation ratio of KOH, using chitosan as the carbon source, carbon nitride (g-C3N4 and g-C3N5) as self-sacrificing templating agents, and KOH as the activator. Among the prepared materials, T6-850-1 has the highest specific surface area (SBET) of 2336 m2/g, and T6-750-1 has the highest microporous area (Smicro) and CO2 adsorption capacity (1 bar, 298 K) of 1969 m2/g and 3.49 mmol/g, respectively. The thermal decomposition temperature and products of carbon nitride templates were characterized and tested by thermogravimetric infrared gas chromatography-mass spectrometry (TG-IR-GC-MS), and the thermal decomposition mechanisms of the two carbon nitride templates were investigated. We found that the thermal stability of the template directly affects the pore structure of the final sample as well as the type and quantity of nitrogen species.