A controllable nanometer-sized valve

A polycrystalline MFI zeolite layer consisting of zeolite crystals with 0.6 nm zeolite pores acts as a chemically-activated and chemically-specific controllable nanometer-sized valve. Controlled addition of n-hexane allow separations of mixtures that have molecules of different sizes and larger than 0.6 nm. The nanostructure of the zeolite layer changes in the presence of n-hexane and acetone showing that n-hexane adsorbing in MFI pores expand the MFI crystals to shrink the lager pores to 0.6 nm. Prevaporation fluxes for binary mixtures of Dimethylbutane (DMB) with n-hexane, acetone, and benzene confirm that adsorption closes the larger pores. n-haxane exhibits a small increase in flux due to capillary condensation and this increase is 6% of the DMB increase, indicating the remaining larger pores have a selectivity of 1.5.