(447b) Microscopic Diffusion Studies of Pure and Mixed Methane and Carbon Dioxide in ZIF-11 By NMR
Fundamental understanding of gas diffusion in ZIFs is of crucial importance for their potential applications in separations. Here we report microscopic studies of diffusion of CO2, CH4, and a CO2/CH4 mixture inside ZIF-11 particles. These gases are commonly found in natural and coal bed gases, where CO2 is an impurity. Diffusion measurements were performed using 1H and 13C pulsed field gradient (PFG) NMR utilizing a high field (17.6 T) and high field gradients (up to 30 T/m) to obtain diffusivities for the length scales of displacements in the range of about 1-20 mm. The diffusivities for one component gases are correlated with those in the corresponding gas mixture. The role of particle external surface in the measured transport properties is discussed.