PROBING THE STRUCTURE OF POROUS PELLETS - AN NMR-STUDY OF DRYING

Partially saturated porous catalyst support pellets have been studied using NMR relaxation, PGSE, and imaging techniques. Spatially nonresol ved PGSE data were acquired as a function of the fractional saturation of the pellets during drying. Combination of these data with an estim ate of the width of the pore-size distribution, as determined by mercu ry porosimetry, and the results of numerical simulations of diffusion in a random pore network enabled predictions of the connectivity of th e pore structure to be determined. NMR imaging was shown to be effecti ve in discriminating between different models of drying; even when the bulk drying curves ate similar, significantly different moisture redi stribution phenomena are seen to occur.