Application of IR Spectroscopy, IR Microscopy, and Optical Interference Microscopy to Diffusion in Zeolites

Infrared spectroscopic methodsfor the measurement of adsorption and adsorption kinetics of some aromatics (benzene, ethylbenzene,

p

-xylene), pyridine, and paraffins in solid microporous materials such as zeolites (MOR, ZSM-5, silicalite-1) are described as well as the evaluation of the spectroscopically obtained data. The adsorption isotherms are of the Langmuir–Freundlich type. Isosteric heats of adsorption, transport diffusivities, and activation energies of diffusion as deduced from the spectroscopic measurements are compared with literature data as far as available, and they are found to be in reasonable agreement with results provided by independent techniques. Special attention is paid to sorption and sorption kinetics of binary mixtures, especially the problems of co- and counter-diffusion .

The design and application of a very promising novel technique for the measurement of sorbate transport in porous materials, viz. diffusion interference microscopy, is presented and pertinent results obtained by this technique are reported.