Self-diffusion studies of binary mixtures in NaX zeolites using pulsed field gradient NMR and a Maxwell-Stefan model.
Intracrystalline self-diffusion coefficients were measured by pulsed field gradient (PFG) NMR for single components and binary mixtures of CF(4) and various hydrocarbons in large-crystal NaX zeolites. A short-time diffusion model was used to obtain the unrestricted intracrystalline self-diffusivities by extrapolating to zero diffusion time, when no molecules can leave the crystal during the measurement. The results were used to test a theoretical model from Skoulidas, Sholl, and Krishna for predicting diffusion coefficients of mixtures in zeolites from single-component data. The predicted binary self-diffusivities are consistent with those directly measured in PFG NMR mixture experiments, thus providing an experimental validation of the model.
Department of Chemical and Biological Engineering and Institute for Catalysis in Energy Processes, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, USA.
Qi
Q
Zhao
Randall Q
RQ
Snurr