Abstract

Diffusion is among the rate-controlling processes in the technological application of nano- porous materials, including separation and conversion processes. Over decades, the diffe- rent techniques of diffusion measurements yielded controversial results. The benefit of no- vel measuring techniques which, by immediate visual evidence, exemplify the self-consi- stency of the resulting diffusivities is shown.

Furthermore, by quantifying the permeabilities through the particle surfaces and by correlating the rate of molecular uptake and release with the molecular mobilities, these techniques are able to identify and to explo- re additional transport resistances which so far, though being rate-limiting in numerous cases, were outside the range of direct experimental observation.