Multicomponent counter-current gas diffusion: determination of transport parameters Original Research Article

The method based on the validity of Graham’s law was applied on eight industrial and laboratory prepared porous catalysts. The counter-current diffusion through catalysts was determined in a version of the Wicke–Kallenbach diffusion cell (Graham’s cell). The binary and ternary inert gas systems (consisting of hydrogen, helium, nitrogen, argon) was used. The obtained net diffusion fluxes were fitted to the mean transport-pore model (MTPM) that provides transport parameters. Transport parameters (〈r〉ψ, ψ) characterize the pore structure relevant to gas transport and are independent of the gas kind/composition and measurement conditions; 〈r〉 is the mean transport-pore radius and ψ stands for effective transport-pore porosity (porosity/tortuosity). The evaluated mean transport-pore radii were compared with pore-size distribution (PSD) obtained from mercury porosimetry measurements. Confidence regions of obtained transport parameters for all catalysts were quite narrow. The prevailing diffusion mechanism could be indicated from their shape.