Diffusion of linear and branched C6 hydrocarbons in silicalite studied by the wall-coated capillary chromatographic method

Jama, Mohamed; Delmas, Marc P.F.; Ruthven, Douglas M.

doi:10.1016/s0144-2449(96)00135-2

Cited by 24 publications

(18 citation statements)

References 4 publications

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“…Gravimetric measurements on large crystals ð220 mÞ gave the corrected activation energy equal to 58 kJ/mol [34], partial pressure conditions were not specified. Twotimes lower activation energy (29 kJ/mol) was found by the wall-coated capillary chromatographic method on small crystals ð2 mÞ [27]. Inverse Chromatography experiments performed on small crystals ð2 mÞ provided the activation energy of diffusion at zero occupancy of 56 kJ/mol [26], which is slightly higher than measured in this study.…”

Section: Activation Energy Of Diffusion 421 Influence Of the Loadingcontrasting

confidence: 58%

“…The heat of adsorption obtained experimentally by different techniques are of the same value: 66.4 (inverse chromatography technique [26]), 60 (wall-coated capillary chromatographic method [27]), and 62.7 kJ/mol (gravimetric sorption uptake method [25]). Theoretical calculations from June et al [28] provided the value of 63 kJ/ mol, which also supports the experimental data of this study.…”

Section: Influence Of the Concentration On The Diffusivitymentioning

confidence: 95%

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Positron Emission Profiling Study of the Diffusion of 3-Methylpentane in Silicalite-1

Koriabkina

Schuring

Jong

et al. 2003

Topics in Catalysis

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Section: Activation Energy Of Diffusion 421 Influence Of the Loadingcontrasting

confidence: 58%

Section: Influence Of the Concentration On The Diffusivitymentioning

confidence: 95%

Positron Emission Profiling Study of the Diffusion of 3-Methylpentane in Silicalite-1

Koriabkina

Schuring

Jong

et al. 2003

Topics in Catalysis

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“…In addition to this, several measurement methods, including microscopic (Pulse field gradient NMR (Jobic et al, 1989), quasi-elastic neutron scattering (Xial and Wei, 1992)) and macroscopic methods (the gravimetric method (Shah et al, 1995), the constant volumetric method (Song and Rees, 1996), and Zero-length column technique (Jama et al, 1997)) have been proposed.…”

Section: Introductionmentioning

confidence: 99%

Liquid-phase diffusivity of benzene within mesoporous materials measured by a laser Raman technique

Nakasaka

Tago

Yano

et al. 2010

Chemical Engineering Science

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The intracrystalline diffusivities of benzene within a series of porous materials in the liquid phase (cyclohexane was used as solvent) were measured by a constant volumetric method using Raman spectroscopy at a temperature range from 323 to 393 K.Silicalite-1, mono-dispersed mesoporous silica spheres (MMSS), Silica Gel, -Al 2 O 3 , and SiO 2 -Al 2 O 3 were used as adsorbents. The intracrystalline diffusivity was calculated by parameter fitting using theoretical equations and the experimental transient change of benzene concentrations with time in response to the adsorption. The intracrystalline diffusivities of benzene within mesoporous silicas were almost the same as that within the micropore of silicalite-1, though the pore diameters of silicalite-1 and mesoporous silicas were different from each other. It is considered that the pore walls as well as the solvent molecules of cyclohexane affect the diffusion of benzene molecules in the meso pore region.3

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“…Experimental methods for measuring the diffusion constant D and activation energy for diffusion E a of molecules in framework structures exist , and have been applied to a variety of molecules and structures. − For the same guest molecule and host structure, order of magnitude differences between diffusion constants have been reported. , A compilation of representative experimental data and discussion of such discrepancies has been presented previously. − The lower values of D were typically obtained by experimental methods which probe more macroscopic features of mass transport and not the molecular motion itself . These methods, such as uptake rate measurements, are considered macroscopic diffusion measurements.…”

Section: Introductionmentioning

confidence: 99%

Intracrystalline Diffusion of Linear and Branched Alkanes in the Zeolites TON, EUO, and MFI

1999

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Diffusion constants D and activation energies for diffusion E a were obtained for linear and branched alkanes inside the zeolites TON, EUO, and MFI via molecular dynamics simulations. Molecules with carbon numbers in the range n = 7−30 were studied in the dilute limit. The zeolites used have channels formed by 10-member silicate rings, but the diameter and connectivity of the channels differ between zeolites. Because the zeolites' channel features are different, it was observed that the influences of channel structure on molecular transport, or lattice effects, were also different between zeolites. For linear alkanes in the relatively uniform channels of TON, lattice effects were least pronounced so the highest values for D were observed and D scaled as 1/n. Furthermore, E a ≈ 1 kcal/mol at small n and decreased to nearly zero for large n. The features of the channels in EUO and MFI were such that lattice effects were observed for linear alkanes. Generally, D was lower than in TON and decreased faster than 1/n; in EUO, E a increased with n, while in MFI the dependence of E a on n was anisotropic. Monomethyl-branched alkanes diffused slower than their linear counterparts. Branched molecules are effectively bulkier making interactions with the channel walls more influential. Lattice effects were observed for branched molecules in all the zeolites; especially in the trends of D with branch position.

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Diffusion of linear and branched C6 hydrocarbons in silicalite studied by the wall-coated capillary chromatographic method

Cited by 24 publications

References 4 publications

Positron Emission Profiling Study of the Diffusion of 3-Methylpentane in Silicalite-1

Positron Emission Profiling Study of the Diffusion of 3-Methylpentane in Silicalite-1

Liquid-phase diffusivity of benzene within mesoporous materials measured by a laser Raman technique

Intracrystalline Diffusion of Linear and Branched Alkanes in the Zeolites TON, EUO, and MFI

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