NMR imaging of mass transport and related phenomena in porous catalysts and sorbents

NMR imaging is employed to study the preparation of supported catalysts and a number of mass transport processes in porous catalysts and sorbents. It is shown that, similar to Pt, adsorbed Pd leads to the increase of the relaxation times of liquids permeating porous alumina supports. A faster penetration of adsorbed water into the sorbent is observed when water vapor sorption by selective water sorbents is carried out under vacuum as compared to the sorption from moist air. An interruption of the capillary flow of water within the monolithic catalyst is shown to lead to a non-uniform drying along the monolith channels. Flow imaging of water inflowing into the monolith has revealed a complicated flow pattern characterized by the existence of counterflows in the entrance region. (C) 2001 Elsevier Science Inc. All rights reserved.