(548b) Transport Properties of Hierarchical Porous Materials

Ordered multiporous materials have drawn tremendous interest due to their tunable properties as compared to microporous or disorderdered mesoporous ones. Current or potential applications of hierarchical porous hosts include catalysis, drug delivery, protein separation, etc. In many processes involving porous solids, dynamic properties of the confined fluids play an important or even decisive role. As concerning dynamics, hierarchically-organized porous materials serve a few purposes. First of all, embedding mesoporous transport pathways into microporous frameworks, such as zeolites, may help to overcome transport limitations inherent to these materials by preserving, at the same time, their chemical functionality. Secondly, by the use of the confinement size-dependent properties, such as shifts of the phase transition points, an external control of the effective transport may be achieved. In materials with multiple mesoporosities, mass transfer of the confined fluids via molecular self-diffusion may, in most easy way, be tuned by changing the phase equilibria, gas-liquid or liquid-solid, depending on a particular application considered. Predicting transport in such complex systems is not  trivial because of different phenomena and transport mechanisms involved. Using pulsed field gradient techniqie of NMR and by using two different hierachically-organized multiporous materials we experimentally demonstrate different regimes of transport and their relationships with the pore space organization and external conditions.