Measurement and modeling of the transient adsorption, desorption and diffusion processes in microporous materials

Using pulse-response experiments the adsorption and diffusion behavior of a number of gases in microporous materials was measured in the temperature r ange 300-773 K. By modeling these pulse responses it is possible to simulta neously determine the equilibrium constant for adsorption, the absolute rat e constants for adsorption and desorption, as well as the diffusivity insid e micropores. The pulse-response measurements are very reproducible and the calculated parameters are in good agreement with values reported in litera ture. A unique characteristic of this method is the possibility to accurate ly determine all adsorption and diffusion parameters from one single measur ement. Furthermore, this macroscopic method is the first technique that yie lds diffusivity values which are in good agreement with those determined us ing microscopic methods, such as Pulse-Field-Gradient NMR. The technique is demonstrated for the adsorption and diffusion in MFI-type zeolites and mic roporous carbon. (C) 1999 Elsevier Science Ltd. All rights reserved.