CHARACTERIZATION OF STRUCTURAL INHOMOGENEITIES IN POROUS-MEDIA

Recent studies have demonstrated that spatial heterogeneities in voida ge and pore size, over lengthscales of 0.1-1 mm, significantly affect the transport of liquids within a given porous medium. Nuclear magneti c resonance imaging is used to probe the structure of porous catalyst support pellets, and four image analysis techniques characterize the d egree and nature of heterogeneities observed in the spin-lattice relax ation-time images of six pellets taken from the same batch. Power-spec trum, cluster-size, and percolation analysis reveal significant differ ences in spatial correlations and topological characteristics of the s ir images. The fractal dimension of all the images, however, is the sa me suggesting that this quantity characterizes the intrinsic heterogen eities associated with the particular batch of porous pellets studied in this work. The results suggest that structural models of such pelle ts should account for these macroscopic variations in pellet structure , as characterized here.