Evaluation of the BET Method for Determining Surface Areas of MOFs and Zeolites that Contain Ultra-Micropores

Bae, Youn‐Sang; Yazaydın, A. Özgür; Snurr, Randall Q.

doi:10.1021/la100449z

Cited by 280 publications

(223 citation statements)

References 24 publications

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“…Their theoretical BET surface areas deduced from experimental isotherms (360 and 429 m 2 g À1 , respectively) are much more reliable than the accessible surface areas (0 and 149 m 2 g À1 ) and fit well the experimental value. This result can be related to previous studies [29] which have emphasized that the side pockets of the mordenite type zeolite cannot be probed using the geometric method. Thus, the geometric approach is not suitable for adsorbents with a pore size comparable to those of N 2 .…”

supporting

confidence: 86%

A Series of Isoreticular, Highly Stable, Porous Zirconium Oxide Based Metal–Organic Frameworks

et al. 2012

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supporting

confidence: 86%

A Series of Isoreticular, Highly Stable, Porous Zirconium Oxide Based Metal–Organic Frameworks

et al. 2012

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“…The N 2 adsorption and desorption isotherms of the obtained materials were measured (BEL Japan, Inc., Belsorp mini), and the total surface area, external surface area and micropore volume were calculated using the BET and t-methods [28].…”

Section: Characterization Of Zeolitementioning

confidence: 99%

Selective synthesis for light olefins from acetone over ZSM-5 zeolites with nano- and macro-crystal sizes

Tago

Konno

Sakamoto

et al. 2011

Applied Catalysis A: General

117

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Production of light olefins such as ethylene, propylene and isobutylene from acetone was examined over ZSM-5 zeolites. These light olefins are produced from acetone over the acid sites of the zeolite via a series of consecutive reactions where olefins such as ethylene and propylene are obtained by cracking of isobutylene produced from aldol condensation products of acetone. Macro-and nano-sized ZSM-5 zeolites were prepared by conventional hydrothermal and emulsion methods, respectively, and the ZSM-5 zeolites with nearly the same acidity and BET surface area were obtained regardless of the crystal sizes. From SEM observations, the crystal sizes of the zeolites were approximately 2000 nm and 30-40 nm.These zeolites with different crystal sizes were applied to light olefins synthesis from acetone, and the effect of crystal size on catalytic activity and stability was investigated. As compared with the macro-seized zeolite, the nano-sized zeolite exhibited a high activity over a long lifetime. However, because the nano-sized zeolite possesses a large external surface area, undesirable reactions to form aromatics from the produced light olefins occurred on the acid sites located near the external surface. To inhibit aromatics formation, selective deactivation of the acid sites located near the outer surface of the zeolite was achieved via the catalytic cracking of silane (CCS) method using diphenyl silane (DP-silane). The CCS method was effective in deactivating the acid sites located near the external surface of the ZSM-5 zeolite.Moreover, the nano-size zeolite after the CCS treatment using DP-silane exhibited high olefins and low aromatics yields under high acetone conversion conditions.

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“…It has been often reported that Ar should be used over N 2 for the analysis of microporous materials particularly zeolites because of the validity of the monolayer capacity. However, Bae et al [19] used both gases to determine the surface areas for ultramicroporous materials and found results to be in good agreement.…”

Section: Bet and Sem Analysismentioning

confidence: 99%

Adsorption of dimethyl ether (DME) on zeolite molecular sieves

Lad

Makkawi

2014

Chemical Engineering Journal

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In recent years there has been growing interest in the use of dimethyl ether (DME) as an alternative fuel. In this study, the adsorption of DME on molecular sieves 4 Å (Mol4A) and 5 Å (Mol5A) has been experimentally investigated using the volumetric adsorption method. Data on the adsorption isotherms, heats of adsorption, and adsorption kinetic have been obtained and used to draw conclusions and compare the performance of the two adsorpents. Within the conditions considered, the adsorption capacity of Mol5A was found to be around eight times higher than the capacity of Mol4A. Low temperature adsorption and thermal pre-treatment of the adsorbents in vacuum were observed to be favourable for increased adsorption capacity. The adsorption isotherms for both adsoprbent were fitted to the Freundlich model and the corresponding model parameters are proposed.The adsoprtion kinetic analysis suggest that the DME adsorption on Mol5A is controlled by intracrystalline diffusion resistance, while on Mol4A it is mainly controlled by surface layering resistance with the diffusion only taking place at the start of adsorption and for a very limited short time. The heats of adsorption were calculated by a calorimetric method based on direct temperature measurements inside the adsorption cell. Isosteric heats, calculated by the thermodynamic approach (Clasius-Clapeyron equation), have consistently shown lower values. The maximum heat of adsorption was found to be 25.9 kJ mol -1 and 20.1 kJ mol -1 on Mol4A and Mol5A, respectively; thus indicating a physisorption type of interactions.

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Evaluation of the BET Method for Determining Surface Areas of MOFs and Zeolites that Contain Ultra-Micropores

Cited by 280 publications

References 24 publications

A Series of Isoreticular, Highly Stable, Porous Zirconium Oxide Based Metal–Organic Frameworks

A Series of Isoreticular, Highly Stable, Porous Zirconium Oxide Based Metal–Organic Frameworks

Selective synthesis for light olefins from acetone over ZSM-5 zeolites with nano- and macro-crystal sizes

Adsorption of dimethyl ether (DME) on zeolite molecular sieves

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