DETECTION OF SURFACE-RESISTANCE IN A GAS POROUS-ADSORBENT SYSTEM BY FREQUENCY-RESPONSE METHOD

The frequency-response (FR) method for studying an X-reversable-C system (Yasuda, 1982) has been extended to an [GRAPHICS] system, where X denotes a molecule in the gas phase, A is an adspecies on the external surface of a porous adsorbent, and C is an adspecies within micropores. Based on the characteristic functions for a system derived analytically, it is shown that both rate constants for steps I and II can be determined separately from the FR data. According to actual data of CH4/5A zeolite systems, it has been confirmed that both the adsorption and desorption rate constants for step I, k(a) and k(d), respectively, and also the Fickian diffusional time constant at step II, approximately D, can be evaluated. The present method is expected to provide quantitative information concerning the existence and intensity of surface barriers of zeolite crystals.