Measurement of intracrystalline diffusion by the frequency response method: analysis and interpretation of bimodal response curves

Diffusion of aromatic hydrocarbons in silicalite/HZSM-5

“…This is contrary to the results of the single crystal membrane measurements which show that diffusion in the z-direction is only slower by a factor of about 3 compared with the x or y directions. Sun and Bourdin showed that a bimodal response may also be produced by other mechanisms (Sun and Bourdin 1993), notably the combination of mass transfer (or diffusional) resistance and heat transfer. However, in such a model the mass transfer peak always corresponds to the faster process.…”

Thermal frequency response method for the study of mass‐transfer kinetics in adsorbents

“…As a result, its maximum occurs at low frequency and it decreases when frequency increases. The out-of-phase function may present one or two maxima, depending on thermal and mass-transfer effects, and it may be rather difficult to distinguish between these two effects (Sun and Bourdin, 1993).…”

A model for sound propagation between two adsorbing microporous plates

“…(g) At the solid surface the sorbate concentration is at equilibrium (Sun and Meunier, 1993) with the fluid phase…”

“…In the batch system the pressure response of a closed sorption system subjected to a periodic volume change is measured, while in the open flow the concentration at the inlet of a packed bed, C(t) in is varied sinusoidally and the response is obtained from the data of C(t) out at the exit. The original apparati were severely limited in the maximum obtainable frequency, which was close to 1 Hz (Yasuda and Sugasawa, 1982;Sun and Meunier, 1993), which results in a measurable time constant corresponding to approximately 0.1 to 0.3 Hz. Van-Den-Begin and Rees (1989) significantly improved the original design of Yasuda and reached an upper limit in the frequency of 10 Hz using bellows actuated by electromagnets to modulate the volume and generate the pressure fluctuation.…”