Discriminative Separation of Gases by a "Molecular Trapdoor" Mechanism in Chabazite Zeolites
Jin Shang, Gang Li, Ranjeet Singh, Qinfen Gu, Kate M Nairn, Timothy J Bastow, Nikhil Medhekar, Cara M Doherty, Anita J Hill, Jefferson Z Liu, Paul A Webley
Journal of the American Chemical Society | AMER CHEMICAL SOC | Published : 2012
Separation of molecules based on molecular size in zeolites with appropriate pore aperture dimensions has given rise to the definition of "molecular sieves" and has been the basis for a variety of separation applications. We show here that for a class of chabazite zeolites, what appears to be "molecular sieving" based on dimension is actually separation based on a difference in ability of a guest molecule to induce temporary and reversible cation deviation from the center of pore apertures, allowing for exclusive admission of certain molecules. This new mechanism of discrimination permits "size-inverse" separation: we illustrate the case of admission of a larger molecule (CO) in preference t..View full abstract
Funding for this CO2CRC project is provided by the Australian Government through its CRC program. We acknowledge Monash University and the NCI National Facility at the ANU. This research was undertaken on the powder X-ray diffraction beamline at the Australian Synchrotron, Victoria, Australia. We thank Y. Yang, J. Patel, S. Wang, and N. Burke from CSIRO for help with breakthrough experiments. We are grateful to Z. Wu and P. Xiao for comments. We thank D. Kearley from ANSTO for discussions. T.J.B., C.M.D., and A.J.H. acknowledge the CSIRO OCE Science Leader Scheme for support.