In Situ Neutron Diffraction of Zn-MOF-74 Reveals Nanoconfinement-Induced Effects on Adsorbed Propene

Even though confinement was identified as a common element
of selective
catalysis and simulations predicted enhanced properties of adsorbates
within microporous materials, experimental results on the characterization
of the adsorbed phase are still rare. In this study, we provide experimental
evidence of the increase of propene density in the channels of Zn-MOF-74
by 16(2)% compared to the liquid phase. The ordered propene molecules
adsorbed within the pores of the MOF have been localized by in situ
neutron powder diffraction, and the results are supported by adsorption
studies. The formation of a second adsorbate layer, paired with nanoconfinement-induced
short intermolecular distances, causes the efficient packing of the
propene molecules and results in an increase of olefin density.