Flow into and through zeolite beds and compacts

Abstract

The effective differential diffusivity for isothermal flow through a bed of zeolite powder has been derived and modified to allow for evaporation barriers at exit faces of crystals. This diffusivity in transient flow for nonlinear isotherms is concentration dependent, but important exceptions arise. These are local sorption equilibrium and rectangular isotherms, local equilibrium and Henry's law isotherms, and very rapid gas-phase flow with very slow sorption. In steady flow the permeability may allow one to measure large intracrystalline diffusivities like those obtained by pulsed NMR. Some properties of diffusivities, differential and integral, and of the permeability have been quantified by using the Langmuir model, because isotherms in zeolites are normally of type 1 in Brunauer's classification. Information derivable from time lags has been considered.

Transport of n‐paraffins in zeolite T

“…(ii) Evaporation barrier (Barrer, 1987). During desorption, molecules must acquire enough energy in order to escape the interactions with the framework.…”

Slow diffusion of methane in ultra-micropores of silicon carbide-derived carbon

“…While the approach has found much support in the subsequent literature, in some studies of adsorption in activated carbon the microstructure has been divided into two types of independent micropore phases with negligible particle scale macropore resistance [29]. Subsequent work has seen modifications to the above approach to include a particle scale flux contribution from the micropores, following Barrer [30] as well as Karger [31], who propose the hopping of molecules between the microparticles through the macropore spaces. While Do and coworkers [32][33][34] incorporate this flux through an empirical surface diffusion of the adsorbed phase, Bhatia and co-workers [35,36] consider a microparticle through-flux arising from the macropore concentration variation around the microparticle surface.…”

Zeolite Membranes: From the Laboratory Scale to Technical Applications

“…born to develop zeolite membranes and the first attempts to prepare zeolite membranes were reported, the first patents were claimed. Parallel to the progress in the preparation of zeolite membranes, the theoretical fundamentals for the molecular understanding of mixture permeation through pore membranes were laid by Barrer (1987Barrer ( , 1990.…”