Diffusion Measurements Through Embedded Zeolite Crystals
For the first time, a macroscopic method was used to measure directly diffusivity of fast diffusing species such as methane in silicalite. A form of Wicke–Kallenbach technique was applied to measure intracrystalline diffusivity. The technique uses a single embedded zeolite crystal as a membrane and a mass-selective detector to determine the transient mass response and hence the diffusion flux passing through the membrane. A concentration-difference driving force is used rather than a pressure-difference driving force. The diffusivities calculated from both adsorption and desorption transients were in excellent agreement, thus providing a check for the self-consistency of the data. The diffusivities of carbon dioxide, methane, ethane, propane and butane in silicalite between 30 and 70°C have been compared with those from the literature. The diffusivities reported here are between those measured with microscopic methods and those measured with other macroscopic methods.
Sun, Matthew S.; Talu, Orhan; and Shah, Dhananjai B., "Diffusion Measurements Through Embedded Zeolite Crystals" (1996). Chemical & Biomedical Engineering Faculty Publications. 96.
Sun, M. S., Talu, O. & Shah, D. B. (1996), Diffusion measurements through embedded zeolite crystals. AIChE J., 42, 11, 3001–3007. doi: 10.1002/aic.690421102