Pore Structure of Alumina Catalyst and lntraparticle Diffusion

Abstract

For the purpose confirming the applicability of the pore structure model 1) to the mass transfer process in porous media, we have measured the e ective diffusion coe cient D, of He, Ar and N2 gases through a commercial alumina catalyst, Neobeed C-5, having the pere structure of simple cubic lattice type (SC). The diffusion was regarded as mainly volumetric, since the effective diffusion coefficient was inversely proportional to the root of molecular weight (Table1). The ratio D, ID, i. e. Oe/L, where D is the diffusion coefficient in the pore and Oe/L is the ratio of opening fraction to tortuosity fraction, was determined experimentally to be O.12 as shown in Table 2, I espective of the pretreating temperature in the range of 450-1200 C and the kind of the gases used. This observed ratio was almost identical with the calculated value of Oe/L for the SC type
These results prove the propriety of the packing model of spherical elementary particle in porous body.