Evaluation of Microporosity, Pore Tortuosity, and Connectivity of Montmorillonite Solids Pillared with LaNiOx Binary Oxide. A Combined Application of the CPSM Model, the αs-Plot Method and a Pore Percolation−Connectivity Model

Salmas, Constantinos E.; Ladavos, Athanasios; Skaribas, S. P.; Pomonis, P.J.; Androutsopoulos, George P.

doi:10.1021/la034913t

Cited by 14 publications

(11 citation statements)

References 29 publications

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“…Many well-known adsorption methods for characterization of porous materials are applicable to PILCs (207,265,(294)(295)(296)(297)(298)(299)(300)(301)(302)(303)(304)(305), but the custom-tailored structures Control of the Porous Structure of PILC Catalysts of these materials create new challenges with respect to reliability and characterization capability and open new opportunities in the development of adsorption characterization methods. In this way, it is clear that any simple model chosen to represent a complex material such as pillared clay must be only an approximation and an accurate model would require prior knowledge of the sample structure.…”

Section: Evaluation Of the Porosity Of Pillared Claysmentioning

confidence: 99%

Recent Advances in the Control and Characterization of the Porous Structure of Pillared Clay Catalysts

2008

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Several methods have been developed and applied in recent years in the characterization of the structure of microporous materials, in general, and of pillared clays, in particular. In the present article, the latest results obtained in the control of the microstructure developed in alumina-pillared clays and various approaches used to the evaluation of the porosity of these materials are reviewed. These include the control of the microstructure developed in pillared clays by adjusting the several parameters involved in the synthesis process, and the evaluation of the porosity of pillared clays. Emphasis is given to the methods to evaluate the pore size and pore size distribution (PSD) of these materials. Two separate sections are devoted to review mathematical modeling studies and 129 Xe NMR spectroscopy of physisorbed Xe to investigate the microporous structural properties of these materials.

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Section: Evaluation Of the Porosity Of Pillared Claysmentioning

confidence: 99%

Recent Advances in the Control and Characterization of the Porous Structure of Pillared Clay Catalysts

2008

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“…The corresponding values of connectivity c are in Tables and . The parameter L expresses the characteristic pore length 11-13 and is related to the nominal pore length of the corrugated pore structure theory (CPSM), whereas the critical exponents β = 0.41 and ν = 0.88 were those used in ref .…”

Section: Methods Of Calculation and Resultsmentioning

confidence: 99%

Comparative Study of Morphometric Properties Characterizing the Complexity of Silicate Pore Networks Probed by Adsorption of Nitrogen and Methanol

Denoyel

Armatas

et al. 2006

Langmuir

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In this work, we compare the surface and morphometric properties of the pore networks in four silicas (code names Fr1428, Fr474, Fr1386, and MM1164) with different random porosities using the adsorption isotherms of two different probe adsorbents, nitrogen and methanol. The parent material Fr1428 was a pure silica 25 microm sample. The Fr474 sample was the same one with bonded electroneutral diol groups on its outer surface. Fr1386 was the parent material with bonded electroneutral diol groups on its outer surface and sulfonic groups on its inner surface, and the MM1164 sample was the original sample with external electroneutral diol groups and internal n-octadecyl groups. The properties examined were the specific surface area S(p) and the specific pore volume V(p), the pore connectivity c, the pore anisotropy b, the tortuosity tau, and the lacunarity lambda of the pore network as well as the percentage microporosity. These properties provide a complete characterization of complexity of the porous network. The surface areas of the solids were estimated via the traditional BET plots (S(BET)) and the I-point method (S(I)). The two sets of values S(BET) and S(I) were practically identical and they decrease as the size of the functional group increases. The values of percentage microporosity were also determined by the same I-point method using the variation of the C parameter of the BET equation. The total pore volume V(p) was found to be higher in the case of methanol adsorption, compared to nitrogen, which might be related to increase condensation. The networks of the pores were simulated using a dual site bond model (DSBM) and Monte Carlo (MC) techniques for achieving their proper arrangement into the solids. From the resulting simulating networks, the pore connectivity distributions (PCD) and their mean values c(mean) were estimated and favorably compared to the values of connectivity c(Seaton) determined according to the method of Seaton. Both values decrease with the size of the functional groups and are weakly affected by the adsorbent employed. From the simulation pore network, the mean values of tortuosity tau(mean) were also estimated and found to be lower when N2 was used as adsorbate compared to MeOH. The values of lacunarity lambda, estimated according to the method by Allain and Cloitre using the moving box technique in the DSBM/MC simulation matrix of the pore network, indicate that the distribution of the poreless mass into the matrix increases with the size of the functional group. Finally, the internal relationships observed between the pore anisotropy b and the percentage microporosity as well as between the tortuosity tau and the pore connectivity c are discussed.

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“…Both PC and APC samples were outgassed under a vacuum (i.e., 10 −6 mbar) at 150 • C for 10 h before the experiments. Pore structure parameters were estimated using different models, such as the CPSM model [10][11][12][13][14][15], the Brunauer-Emmet-Teller [16], the Horvath-Kawazoe model [17], and the Dubinnin-Raduskevitch model [18]. The overall pore volume was calculated via the total adsorbed nitrogen amount at P/P 0 = 0.998.…”

Section: Characterization Techniquesmentioning

confidence: 99%

Microwave Synthesis, Characterization and Perspectives of Wood Pencil-Derived Carbon

et al. 2022

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More than 14 billion pencils are manufactured and used globally every year. On average, a pencil is discarded after 60% of its original length has been depleted. In the present work we propose a simple and affordable way of converting this non-neglectable amount of waste into added value carbon product. In particular, we demonstrate the microwave synthesis of carbon from the wood pencil with and without chemical activation. This could be a process stage before the final recycling of the expensive graphite core. In the latter case, irradiation of the wood pencil in a domestic microwave oven heats up the pencil’s graphite core, thus inducing carbonization of its wood casing. The carbonized product consists of amorphous carbon nanosheets having relatively low surface area. However, if the wood pencil is soaked in 50% KOH aqueous solution prior to microwave irradiation, a significantly higher surface area of carbon is obtained, consisting of irregular-shaped porous particles. Consequently, the obtained carbon can easily decolorize a methylene blue aqueous solution, can be used to make pocket warmers or gunpowder, and lastly, serves as an excellent adsorbent towards Cr(VI) removal from water, showing a maximum adsorption capacity of 70–75 mg/g within 24 h at 23 °C, pH = 3.

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Evaluation of Microporosity, Pore Tortuosity, and Connectivity of Montmorillonite Solids Pillared with LaNiO_x Binary Oxide. A Combined Application of the CPSM Model, the α_s-Plot Method and a Pore Percolation−Connectivity Model

Cited by 14 publications

References 29 publications

Recent Advances in the Control and Characterization of the Porous Structure of Pillared Clay Catalysts

Recent Advances in the Control and Characterization of the Porous Structure of Pillared Clay Catalysts

Comparative Study of Morphometric Properties Characterizing the Complexity of Silicate Pore Networks Probed by Adsorption of Nitrogen and Methanol

Microwave Synthesis, Characterization and Perspectives of Wood Pencil-Derived Carbon

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