Consequence of distributed properties on effective diffusivities in porous solids

✍ Scribed by C.L. Cui; J.R. Authelin; D. Schweich; J. Villermaux

• Publisher: Elsevier Science
• Year: 1990
• Tongue: English
• Weight: 588 KB
• Volume: 45
• Category: Article
• ISSN: 0009-2509
• DOI: 10.1016/0009-2509(90)80149-9

✦ Synopsis

Effective diffusivities

in porous solids are global parameters which lump a complicated geomeuical structure together with the diffusion process. Lumping is different depending on the measurement method and this may lead to strongly biased coefficients.

Three geometrical effects are studied -Effect of pore size distribution on apparent diffusivities measured by Wicke-Kallenbach method, chromatographic method and diffusion limitation of a first order catalytic reaction -Influence of external porosity distribution in a packed bed -Effect of crystal size distribution in zeolite based catalysts. These three examples show that raw effective diffusivities have to, and can be corrected for geometrical effects.