Next Article in Journal
Kinetics of Holographic Recording and Spontaneous Erasure Processes in Light-Sensitive Liquid Crystal Elastomers
Next Article in Special Issue
“Pore-Like” Effects of Super-Molecular Self-Assembly on Molecular Diffusion of Poly(Ethylene Oxide)-Poly(Propylene Oxide)-Poly(Ethylene Oxide) in Water
Previous Article in Journal / Special Issue
Exploring Mass Transfer in Mesoporous Zeolites by NMR Diffusometry
Article Menu

Export Article

Open AccessReview
Materials 2012, 5(4), 721-740; doi:10.3390/ma5040721

Micro-Imaging by Interference Microscopy: A Case Study of Orientation-Dependent Guest Diffusion in MFI-Type Zeolite Host Crystals

Department of Interface Physics, University of Leipzig, Leipzig 04109, Germany
Department of Chemical and Biological Engineering, University of Maine, Orono, ME 04473, USA
Author to whom correspondence should be addressed.
Received: 28 February 2012 / Revised: 10 April 2012 / Accepted: 13 April 2012 / Published: 24 April 2012
(This article belongs to the Special Issue Diffusion in Micropores)
View Full-Text   |   Download PDF [1649 KB, uploaded 24 April 2012]   |  


Because of the small particle size, orientation-dependent diffusion measurements in microporous materials remains a challenging task. We highlight here the potential of micro-imaging by interference microscopy in a case study with MFI-type crystals in which, although with different accuracies, transient concentration profiles in all three directions can be observed. The measurements, which were performed with “rounded-boat” shaped crystals, reproduce the evolution patterns of the guest profiles recorded in previous studies with the more common “coffin-shaped” MFI crystals. The uptake and release patterns through the four principal faces (which in the coffin-shaped crystals extend in the longitudinal direction) are essentially coincident and there is no perceptible mass transfer in the direction of the long axis. The surface resistances of the four crystal faces through which mass transfer occurs are relatively small and have only a minor effect on the mass transfer rate. As a result of the pore structure, diffusion in the crystallographic c direction (which corresponds to the direction of the long axis) is expected to be much slower than in the transverse directions. This could explain the very low rate of mass transfer observed in the direction of the long axis, but it is also possible that the small end faces of the crystal may have high surface resistance. It is not possible to distinguish unequivocally between these two possibilities. All guest molecules studied (methyl-butane, benzene and 4-methyl-2-pentyne) show the same orientation dependence of mass transfer. The long 4-methyl-2-pentyne molecules would be expected to propagate at very different rates through the straight and sinusoidal channels. The coinciding patterns for uptake through the mutually perpendicular crystal faces therefore provide clear evidence that both the coffin shaped crystals and the rounded-boat-shaped crystals considered in this study, must be intergrowths rather than pure single crystals. View Full-Text
Keywords: MFI (mordenite framework inverted); diffusion; anisotropy; surface resistance; interference microscopy MFI (mordenite framework inverted); diffusion; anisotropy; surface resistance; interference microscopy

Figure 1

This is an open access article distributed under the Creative Commons Attribution License (CC BY 3.0).

Scifeed alert for new publications

Never miss any articles matching your research from any publisher
  • Get alerts for new papers matching your research
  • Find out the new papers from selected authors
  • Updated daily for 49'000+ journals and 6000+ publishers
  • Define your Scifeed now

SciFeed Share & Cite This Article

MDPI and ACS Style

Gueudré, L.; Binder, T.; Chmelik, C.; Hibbe, F.; Ruthven, D.M.; Kärger, J. Micro-Imaging by Interference Microscopy: A Case Study of Orientation-Dependent Guest Diffusion in MFI-Type Zeolite Host Crystals. Materials 2012, 5, 721-740.

Show more citation formats Show less citations formats

Related Articles

Article Metrics

Article Access Statistics



[Return to top]
Materials EISSN 1996-1944 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
Back to Top