(583ed) Diffusion of Carbon Dioxide in Samaria Aerogel Catalyst Using High-Field Pulsed Field Gradient NMR

Aerogels containing rare-earth metal oxides represent a promising class of porous catalysts exhibiting high porosity and high surface area.  In these materials, active catalytic sites are integrated directly into the porous framework. The catalyst can be easily formed into macroscopic monoliths or in the beds of particles. This work focuses on exploring gas diffusion in both types of packings of the same material. We will present selected experimental results of self-diffusion studies of a product gas species, carbon dioxide, in alumina supported aerogel catalyst prepared as macroscopic monoliths and as beds of particles with sizes around 200 microns. This investigation was enabled by a ¹³C pulsed field gradient (PFG) NMR technique employing a high magnetic field of 17.6 T. The high field allowed obtaining sufficiently large signal-to noise ratios for carbon dioxide under our measurement conditions. The reported diffusion data are described using a commonly used two-domain exchange model developed for zeolites.