en-us-Διάλεξη: Macroscopic Measurement of Diffusion in Nanoporous Materials

In many applications mass transport in porous solids plays an important role in the overall performance of adsorption and catalytic processes. The lecture will cover the definitions of diffusion coefficients in nanoporous materials from micropores to macropores, according to the IUPAC definition. Particular attention will be given to different mechanisms and how to distinguish them experimentally. 

A brief historical perspective of diffusion measurement is zeolites will introduce both microscopic techniques, which typically measure the root mean squared displacement of molecules in the absence of gradient, and macroscopic techniques, which typically measure the net flux at the surface of the material in the presence of concentration gradients. 

The final part of the talk will be consist of examples from the zero length column (flow system) and volumetric (closed system) apparatuses, which will be used to highlight advantages and limitations of different techniques. Particular emphasis will be given to the experimental checks that should be performed to distinguish between macropore and micropore control and at the micropore scale between diffusion and surface barrier mechanisms. The relevant theory will be discussed as it forms an essential basis to understand how do develop an experimental strategy.