Dynamics of gas transport in porous solids: the influence of non-isobaric transport and concentration

✍ Scribed by Daniel Arnošt; Petr Schneider

• Publisher: Elsevier Science
• Year: 1994
• Tongue: English
• Weight: 689 KB
• Volume: 20
• Category: Article
• ISSN: 0920-5861
• DOI: 10.1016/0920-5861(94)80133-9

✦ Synopsis

The dynamics of the binary transport of non-adsorbable gases (hydrogen. helium, nitrogen, argon) through porous solids were studied by means of the dynamic version of the Wicke-Kallenbach diffusion cell. Six samples of a-alumina pellets were used which were prepared under different compressing pressures and calcination temperatures with pore structures resembling commercial catalysts/earners.

Responses to concentration pulses and step changes at one face of the cylindrical pellets were followed at the other face of the pellets. Two types of description were used for evaluation of the transport parameters of the porous structures from the experimental responses by time-domain fitting: a mean transport pore model ( MTPM ) and a homogeneous pore model with Bosanquet formula for effective dlffusivity ( HPM ). MTPM takes into account the induced permeation flow and the Influence of the gas mixture composition whilst HPM neglects these effects. It was shown that the permeation contribution m the dynamic version of the Wlcke-Kallenbach cell can be neglected. The Influence of the gas mixture composition is neghgible for the cases with pulse disturbances whilst for step changes such a slmplitication, inherent in HPM. IS not permissible. For evaluation of transport parameters from pulse-response experiments the moment method can be used.