Crystal-size effect on the kinetics of CO2 adsorption in metal organic frameworks studied by NMR.

Abstract

We study the dynamics and the exchange of carbon dioxide (CO2) adsorbed in a metal organic framework (MOF) by 13C NMR for various sizes of the host crystal ranging from micrometers to millimeters. We found that the guest CO2 molecules adsorbed in [Zn2(1,4-NDC)2(dabco)]n MOF undergo exchange at a rate that depends on the size of the host crystal, revealing that the smaller the host crystals are, the faster the exchange becomes. Such a trend can be explained by the size-dependent surface-to-volume ratio.