Mass Transfer Measurements

Fairly simple models of the porous structure which, however, take into account the most significant features of transport (Knudsen diffusion, bulk diffusion, Knudsen permeation, viscous flow, slip flow contribution) are used to describe the pore mass transfer. Using such models, material parameters of the porous solid are determined by matching of theory to experimental results obtained for simple transport processes.

The following transport processes are applied:

  • binary counter-current gas diffusion
  • multicomponent counter-current gas diffusion
  • gas diffusion under dynamic conditions (chromatography with single-pellet-string column SPSC)
  • (pseudo)steady-state permeation of pure gases
  • permeation of pure gases under dynamic conditions
  • combined diffusion and permeation of gas mixtures

In all cases inert gases are used in order to suppress the (possible) surface transport of adsorbed species. These processes are experimentally performed using dedicated home-developed instruments.