USE OF LIQUID-PHASE DIFFUSION FOR STUDYING POROUS CATALYSTS .1. MATHEMATICAL APPARATUS

Equations are reported for describing liquid-phase diffusion in a porous solid applied to steady-state diffusion through an infinite plate and nonstationary diffusion from a semi-infinite solid, an infinite plate, an infinite round cylinder, a sphere, and a finite round cylinder, isotropic and anisotropic. The equations permit calculating the effective diffusion coefficient E and the parameter h, characterizing a compact layer on the surface of a solid, from the experimental data on the diffusion rate. The diffusion permeability-xi = E/D (D is the real diffusion coefficient) and parameter h are not functions of either the nature of the diffusing substance or the medium in which diffusion occurs, and for this reason, they can be used for determining the efficiency factor of catalysts.