Numerical analysis of the micropore structure of activated carbons focusing on optimum CO2 adsorption

Kwiatkowski, Mirosław; Kalderis, Dimitrios; Tono, Wataru; Tsubota, Toshiki

doi:10.1016/j.jcou.2022.101996

Cited by 8 publications

(9 citation statements)

References 41 publications

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“…Due to the increasing demands placed on adsorbents, technologies for their manufacture are being improved, which, however, requires a precise assessment of the porous structure taking into account surface heterogeneities, which is not fully provided by the BET, t—plot, and BJH methods used in previous studies 17 . Therefore, a concept was developed to analyse the adsorption process and porous structure of spherical activated carbons using advanced analysis methods taking into account, among other things, surface heterogeneity and pore geometry, i.e., the numerical clustering-based adsorption analysis method (LBET) 22 – 24 and the quenched solid density functional theory method (QSDFT) 26 , 26 .…”

Section: Methodsmentioning

confidence: 99%

“…The LBET method, the theoretical foundations for the LBET models and their derivation, and the numerical fast multivariate procedure of adsorption system identification, were described in detail in earlier publications 22 – 24 . The LBET models have five adjusted parameters: V hA [cm 3 /g], Q A [J/mol] , α , β and B C, which can be adjusted by fitting LBET equation to the adsorption isotherm, with a chosen variant of the surface energy distribution function [38–40].…”

Section: Methodsmentioning

confidence: 99%

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Numerical analysis of the porous structure of spherical activated carbons obtained from ion-exchange resins

Kwiatkowski,

He,

Valtchev

2024

Sci Rep

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This paper presents the results of an analysis of the porous structure of spherical activated carbons obtained from cation-exchange resin beads subjected to ion exchange prior to activation. The study investigated the effects of the type of cation exchange resin, the concentration of potassium cations in the resin beads and the temperature of the activation process on the adsorption properties of the resulting spherical activated carbons. The numerical clustering-based adsorption analysis method and the quenched solid density functional theory were used to analyse the porous structure of spherical activated carbons. Based on original calculations and unique analyses, complex relationships between preparation conditions and the porous structure properties of the obtained spherical activated carbons were demonstrated. The results of the study indicated the need for simultaneous analyses using advanced methods for the analysis of porous structures, i.e., the numerical clustering-based adsorption analysis method and the quenched solid density functional theory. This approach allows a reliable and precise determination of the adsorption properties of the materials analysed, including, among other things, surface heterogeneities, and thus an appropriate selection of production conditions to obtain materials with the expected adsorption properties required for a given industrial process.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Numerical analysis of the porous structure of spherical activated carbons obtained from ion-exchange resins

Kwiatkowski,

He,

Valtchev

2024

Sci Rep

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“…Consequently, various attempts have been made to develop reliable methods to define the process taking place during adsorption. One such method is a unique proprietary method for the analysis of cluster-based multilayer adsorption processes on heterogeneous surfaces (LBET), together with an advanced fast numerical method for multi-variant identification of adsorption systems [32][33][34].…”

Section: Methodsmentioning

confidence: 99%

“…The LBET method is based on a group of 30 or, in an extended version, 48 models and a unique universal adsorption theory developed by the team, which is a significant extension of the BET model. In addition, adsorption in ultramicropores is described by the equation of Langmuir, thence the abbreviation LBET is used for the newly proposed group of mathematical models of the adsorption process [32][33][34]. In contrast to the BET model, the LBET model was developed to consider the heterogeneity of the surface and the possibility of separating groups of adsorbate molecules, as well as geometrical and energetic constraints on the formation of groups of molecules from the adsorbate [32][33][34].…”

Section: Methodsmentioning

confidence: 99%

Numerical Analysis of the Porous Structure of Activated Carbons Derived from Synthetic Polymers

Kwiatkowski,

Cansado,

Mourão

2024

Materials

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This paper presents original results from the unique analysis of the porous structure of activated carbons (ACs) produced through the chemical activation of polyethylene terephthalate (PET) and polyacrylonitrile (PAN), as well as from a physical mixture of both polymers. An advanced method of adsorbent surface analysis—more specifically, the new method of numerical clustering-based adsorption analysis regarding the surface heterogeneity, pore geometry and adsorption energy distribution parameters—allowed us to obtain information about the porous structure of the ACs from the synthetic polymers mentioned above. As the results showed, ACs obtained with PAN were characterised by a first adsorbed layer with the highest volume. When the surface heterogeneity, highly desirable in most advanced adsorption processes, is taken into account, the materials with the best surface properties in both potassium carbonate (K2CO3) and potassium hydroxide (KOH) activation processes were the ACs obtained with a mass proportion of PET to PAN of 1:3, which were characterised by a low degree of surface heterogeneity and a first adsorbed layer presenting a relatively large volume.

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“…The most relevant adsorbents used in carbon sequestration technologies have proven to be activated carbons derived from biomass [13][14][15][16][17][18][19][20][21][22][23][24]. This is due to the widespread availability of raw materials for their production and their renewability, significant strength, high adsorption capacity, stability, and ease of regeneration [13][14][15][16][17][18][19][20][21][22][23][24].…”

Section: Introductionmentioning

confidence: 99%

Analysis of the Influence of Activated Carbons’ Production Conditions on the Porous Structure Formation on the Basis of Carbon Dioxide Adsorption Isotherms

Kwiatkowski

Pastuszyński

2022

Materials

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The results of a study of the impact of activation temperature and the mass ratio of the activator to the carbonised precursor on the porous structure of nitrogen-doped activated carbons obtained from lotus leaves by carbonisation and chemical activation with sodium amide (NaNH2) are presented. The analyses were carried out via the new numerical clustering-based adsorption analysis, the Brunauer–Emmett–Teller, the Dubinin–Raduskevich, and the density functional theory methods applied to carbon dioxide adsorption isotherms. Carbon dioxide adsorption isotherms’ analysis provided much more detailed and reliable information about the pore structure analysed. The analyses showed that the surface area of the analysed activated carbons is strongly heterogeneous, but the analysed activated carbons are characterised by a bimodal pore structure, i.e., peaks are clearly visible, first in the range of pore size from about 0.6 to 2.0 nm and second in the range from about 2.0 to 4.0 nm. This pore structure provides optimal adsorption performance of carbon dioxide molecules in the pore structure both for adsorption at atmospheric pressure, which requires the presence of narrow pores for the highest packing density, as well as for adsorption at higher pressures, which requires the presence of large micropores and small mesopores. However, there are no micropores smaller than 0.5 nm in the analysed activated carbons, which precludes their use for carbon dioxide adsorption for processes conducted at pressures less than 0.01 MPa.

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Numerical analysis of the micropore structure of activated carbons focusing on optimum CO2 adsorption

Cited by 8 publications

References 41 publications

Numerical analysis of the porous structure of spherical activated carbons obtained from ion-exchange resins

Numerical analysis of the porous structure of spherical activated carbons obtained from ion-exchange resins

Numerical Analysis of the Porous Structure of Activated Carbons Derived from Synthetic Polymers

Analysis of the Influence of Activated Carbons’ Production Conditions on the Porous Structure Formation on the Basis of Carbon Dioxide Adsorption Isotherms

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