Chemical Engineering Science, Vol.54, No.20, 4423-4436, 1999
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 range 300-773 K. By modeling these pulse responses it is possible to simultaneously determine the equilibrium constant for adsorption, the absolute rate constants for adsorption and desorption, as well as the diffusivity inside micropores. The pulse-response measurements are very reproducible and the calculated parameters are in good agreement with values reported in literature. A unique characteristic of this method is the possibility to accurately determine all adsorption and diffusion parameters from one single measurement. Furthermore, this macroscopic method is the first technique that yields diffusivity values which are in good agreement with those determined using microscopic methods, such as Pulse-Field-Gradient NMR. The technique is demonstrated for the adsorption and diffusion in MFI-type zeolites and microporous carbon.