A new view of diffusion in nanoporous materials

Diffusion is among the rate-controlling processes in the technological application of nanoporous materials, including separation and conversion processes. Over decades, the different techniques of diffusion measurements yielded controversial results. The benefit of novel measuring techniques which, by immediate visual evidence, exemplify the self-consistency 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 explore additional transport resistances which so far, though being rate-limiting in numerous cases, were outside the range of direct experimental observation.