INSITU PORE STRUCTURE CHARACTERIZATION DURING SOL-GEL SYNTHESIS OF CONTROLLED POROSITY MATERIALS

Using NMR relaxation measurements of pore fluid, the pore volume, surface area, and pore size distribution of wet materials may be measured in-situ. In this manner, changes in pore structure may be directly observed during various aging steps (i.e., temporal, thermal, solvent exchange, pH) of sol-gel derived porous solids. By combining these relaxation measurements with Nuclear Magnetic Resonance imaging (NMRI), the spatial variation of pore structure may be observed. In addition to how the surface area, porosity, and pore size distribution vary at different points within the sample, the change of sample physical dimensions during processing can be measured. This enables the study of catalyst-related problems such as "skin" effects and catalyst supports with spatially-varied structure in order to minimize mass transfer limitations.