Adsorption-based characterization of hierarchical metal–organic frameworks

Vincent, François; Galarneau, Anne; Coasne, Benoît

doi:10.1007/s10450-013-9583-7

Cited by 8 publications

(13 citation statements)

References 37 publications

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“…But as shown by computational studies for pure microporous or micro-/mesoporous materials, t-plots underestimate micropore volumes 15 and overestimate surface areas. 13 The underestimation of micropore volume by the t-plot method has been demonstrated experimentally for materials containing more than 10% micropore volume. 12 For dealuminated FAU-Y, it is also difficult to measure exactly the micropore volume by t-plot as a few small mesopores (2−4 nm) arise in the material through dealumination, leading to additional volume.…”

Section: ■ Results and Discussionmentioning

confidence: 91%

“…As said previously, for micro-/mesoporous materials, it has been shown by modeling that the t-plot method overestimates surface areas. 13 To experimentally verify this conclusion, mechanical mixtures with different weighted portions of FAU-Y and MCM-41 with known micropore and mesopore surfaces, respectively, have been prepared by simple powder mixing without grinding and analyzed by nitrogen adsorption at 77 K. The micropore and mesopore surface areas of the mixtures have been calculated independently by linear combination and compared to the results of the t-plot analysis (Figures 3, S3).…”

Section: ■ Results and Discussionmentioning

confidence: 93%

“…By modeling, it also was highlighted that the t-plot method overestimates the surface areas of hierarchical microporous/mesoporous materials, such as mesoporous MOF structures (CuBTC). 13 One goal of the present study is to verify experimentally this observation of overestimation of surface area by t-plot analysis.…”

Section: Introductionmentioning

confidence: 75%

“…There are two main tools to calculate specific surface areas from adsorption measurements: the Brunauer–Emmett–Teller (BET) equation and the t -plot method, both being subject to controversy for materials containing micropores. − The t -plot method is a widely used procedure to estimate the total surface area and the external surface area of materials. In this method, the average thickness of an adsorbed film is first determined for a reference material containing no porosity, or only macroporosity, and having the same surface chemistry as the studied porous material.…”

Section: Introductionmentioning

confidence: 99%

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Specific Surface Area Determination for Microporous/Mesoporous Materials: The Case of Mesoporous FAU-Y Zeolites

et al. 2018

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Rouquerol criterion and the BET equation is in accord with the geometrical surface determined by the chord length distribution method. Therefore BET surface area (S BET) is well representative of micropore surface areas of microporous materials and of total surface area of microporous/mesoporous materials. Mechanical mixtures of mesoporous MCM-41 and microporous FAU-Y powders of known surface areas were used to calculate the respective surface areas by weighted linear combination and the results were compared to the values obtained by the t-plot method. The first slope of the t-plot determined the mesopore + external surface areas (S mes+ext). The linear fit of the first slope is in general in the range 0.01 < p/p 0 < 0.17 and contains the volumes and relative pressures at which all micropores are filled (p/p 0 > 0.10). Overestimation of S mes+ext values was evident and appropriate corrections were provided. External surface areas (S ext) were obtained from the second slope of the t-plot, without noting an overestimation of S ext , thus allowing the determination of mesopore surface areas (S mes) by difference. Micropore surface areas were calculated by subtracting S mes+ext from the total surface area, S BET. As an example, this methodology was applied to the characterization a family of hierarchical microporous/mesoporous FAU-Y (FAUmes) synthesized from H-FAU-Y (H-Y, Si/Al = 15) using C18TAB as surfactant and different NaOH/Si ratio (0.05 < NaOH/Si < 0.25). By increasing the NaOH/Si ratio in synthesis of FAUmes, it was shown that as the micropore surface area decreases, the mesopore surface area increases, while the micropore + mesopore surface area remains constant. This methodology allows accurate characterization of the surface areas of microporous/mesoporous materials.

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Section: ■ Results and Discussionmentioning

confidence: 91%

Section: ■ Results and Discussionmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 75%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Specific Surface Area Determination for Microporous/Mesoporous Materials: The Case of Mesoporous FAU-Y Zeolites

et al. 2018

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“…The basis of t-plots and a s -plots is detailed in the literature [1][2][3] and their validity in various situations was discussed by several authors [11][12][13]. Briefly, to apply these methodologies the adsorption isotherm is replotted, keeping the adsorbed amounts (or volumes) on the material under study in ordinate and the abscissa is now a normalized unit [1] (t or a s ).…”

Section: Introductionmentioning

confidence: 99%

Microporous Volumes from Nitrogen Adsorption at 77 K: When to Use a Different Standard Isotherm?

et al. 2021

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This work reviews the application of various standard isotherms to evaluate the micropore volume in a range of microporous materials. The selected materials have quite different surface chemistry, and are relevant due to their properties for adsorption and catalysis: zeolites, activated carbons, clay-based materials and MOFs. Some cases were analysed before and after being used as supports in the heterogenization of homogeneous catalysts. The discussion is centred, but not limited, to the three standard isotherms that are mostly employed in the literature (t-curve, non-porous carbon and non-porous hydroxylated silica) for the assessment of the micropore volume. For a given material the values of the micropore volumes from the different standard isotherms were compared, particularly against the values from the largely used t-curve. The cases where major discrepancies were found could normally be ascribed to samples that have a broad micropore size distribution.

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Determination of Microporous and Mesoporous Surface Areas and Volumes of Mesoporous Zeolites by Corrected t‐Plot Analysis

et al. 2022

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Zeolites are well-known microporous catalysts involved in many industrial applications. Their microporosity yet impedes diffusion of bulky molecules. To overcome this drawback, zeolites with hierarchical bimodal porosity, e. g. micropores and mesopores, are developed. In this context, it is important to develop/use methods able to evaluate accurately the textural properties of mesoporous zeolites. t-Plot can be in theory used for determining the micro-and mesopore surface areas and pore volumes. However, classical t-plot analysis overestimates the mesopore surface areas and underestimates the micropore volumes for hierarchical micro-/mesoporous materials. Measurements performed with mechanical mixtures of FAU-Y and MCM-41 allows to provide corrections, which are up to date limited to mesoporous FAU-Y. The present work describes specific corrections of the t-plot for a broader series of zeolites including MFI, *BEA and MOR, based on a set of mechanical mixtures of zeolites and MCM-41. Minor correction factors are required for MOR, whilst for MFI and *BEA similar corrections as for the FAU-Y are inferred for the micropore volume. As far as the surface area is concerned higher correction factors are required for MFI compared to *BEA. This corrected t-plot analysis is applied to characterize a great variety of mesoporous zeolites prepared by micelle-templating.

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Adsorption-based characterization of hierarchical metal–organic frameworks

Cited by 8 publications

References 37 publications

Specific Surface Area Determination for Microporous/Mesoporous Materials: The Case of Mesoporous FAU-Y Zeolites

Specific Surface Area Determination for Microporous/Mesoporous Materials: The Case of Mesoporous FAU-Y Zeolites

Microporous Volumes from Nitrogen Adsorption at 77 K: When to Use a Different Standard Isotherm?

Determination of Microporous and Mesoporous Surface Areas and Volumes of Mesoporous Zeolites by Corrected t‐Plot Analysis

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