IN-SITU NMR IMAGING STUDIES OF THE DRYING KINETICS OF POROUS CATALYSTSUPPORT PELLETS

The proton NMR imaging (microscopy) technique is employed to study the process of drying of alumina and titania porous catalyst support pell ets impregnated with various liquids. Despite the short spin-spin rela xation times usually exhibited by liquids that permeate porous solids, the possibility to monitor their evaporation in real time by detectin g one-dimensional liquid concentration profiles along the diameter of a cylindrical sample is demonstrated. Ln the qualitative discussion of the results, it is shown that the experiment is sensitive to the fine details of the drying process, such as the efficiency of liquid trans port and peculiar profile shape transformations in the course of dryin g. A simple experiment is proposed that yields an empirical relation b etween the detected profile intensity and the actual liquid content, w hich allows one to correct the detected profiles for the inevitable T- 2-weighting effects.