Bidispersed structured sorbents

The FR measurements have been carried out for several systems using bidispersed structured sorbents [64,76,77]. All the spectra, however, indicate that either micropore diffusion or macropore diffusion, with or without a surface resistance, was the rate-controlUng step for these systems. 

Do, D.D., Hierarchy of rate models for adsorption and desorption in bidispersed structured sorbents,... 

Crystals of microporous materials must be formed into pellets of siutable dimensions, porosity and mechanical strength, or be formed into a membrane on the surface of support materials when used in practice. Such composite pellets or membranes offer a bidispersed porous structure, with macro-or mesopores between the crystals and micropores permeating the crystals. The overall rate of the transport in such systems depends on the interplay of various processes occurring within the pellets or membranes. Jordi and Do [24,46] have developed a general theoretical model and seven relevant degenerate models to analyse the frequency response spectra of a system containing bidispersed pore structure materials for slab, cylindrical and spherical macro- and micropore geometry. Sun et al. [47] also reported the theoretical models of the FR for non-isothermal adsorption in biporous sorbents. 

---