DIFFUSIVITIES OF BENZENE IN HZSM-5, SILICALITE-1, AND NAX DETERMINED BY FREQUENCY-RESPONSE TECHNIQUES

The single-step frequency-response technique, a recent development from our laboratory, and the full frequency-response method have been used to follow the diffusion of benzene in HZSM-5, silicalite-I, and NaX zeolites. Diffusivities of benzene in HZSM-5 was found to be a factor of 2-3 smaller than in silicalite-I. Both diffusivities at 400 K were in close agreement with some previously published diffusivities of approximately 10(-13) m2/s. In the more open channel structure of NaX, the diffusivity of benzene at 450 K was approximately 10(-10) m2/s, i.e., three orders of magnitude larger than in the pentasils.