Molecular Diffusion in Hierarchical Zeolites with Ordered Mesoporosity: Pulsed Field Gradient Nuclear Magnetic Resonance Combined with Thermodynamic Modeling

The dynamics of fluids confined in hierarchical porous materials is gaining increasing attention. Here, using pulsed field gradient nuclear magnetic resonance, we report an experimental study the self-diffusivity cyclohexane at different temperatures bi-porous structure faujasite zeolites (i.e., combining intrinsic zeolite microporosity < 2 nm diameter and ordered MCM-41-like mesoporosity 4 diameter). For mesoporous volumes, consider chemical potentials where porosity either totally or only partially filled (in latter case, completely filled, while surface covered by a molecular thin film). On one hand, materials, as expected, effective found to increase volume increases. Moreover, this regime, follows Arrhenius behavior with activation energy that close to─although slightly smaller than─that for bulk cyclohexane. other striking observed measured decreases upon loading remains nearly constant temperature. We propose here such can be rationalized considering (1) population redistribution between (including gas phase mesopores) (2) number molecules contribute spin echo attenuation In particular, diffuse faster overall temperature, show our measurements rely each temperature on slower (therefore leading unexpected variations).