Page 83 - Adsorption Technology & Design, Elsevier (1998)
P. 83
80 Rates of adsorption of gases and vapours by porous media
Figure 4.5 Composite pellet containing macropores, micropores and crystals.
in concentration of a continuous feed of inert carrier gas and adsorbate to an
isothermal column packed with particles of the adsorbent. The method is
outlined in Section 4.4.
A model of a composite zeolite pellet must thus be represented by a
combination of coupled equations for intracrystalline diffusion and macro-
pore diffusion. The diffusion of adsorbate within crystals was discussed in
the previous section and intracrystalline diffusion is given by equation
(4.17). Macropore diffusion for a spherical pellet of radius Rp, macropore
diffusivity Dp and porosity ep is described by
