Molecular separation plays a key role in energy and environmental technologies. Here we present our recent discovery of a new "active" molecular sieving mechanism – "molecular trapdoor" – in a class of chabazite zeolites through combined experimental and atomistic simulation works. These trapdoor chabazite absorbents have their eight-membered-ring (8MR) aperture (the only possible gas passage) blocked by some extraframework cations. Some specific gas molecules can interact with the aperture-keeping cations to induce temporary and reversible cation deviation from the center of 8MR aperture, allowing for the gas admission. The different chemical/physical interaction capability of various gas molecules with the aperture-keeping cations endows a selective gas admission, which is in striking contrast to conventional sieving mechanism where the molecular size plays a decisive role. A novel absorption model is developed to quantitatively describe the isobar adsorption curves (i.e., adsorption amount as a function of temperature) for our "active" trapdoor chabazites.

Dr. Jin Shang obtained his Bachelor (2007) and Master (2009) degrees both in Environmental Engineering at Northeastern University in China. He completed his PhD in Chemical Engineering at the University of Melbourne in 2013. His PhD thesis was on the separation of carbon dioxide from flue gas and natural gas streams using porous adsorbent materials. After his PhD, he worked as research fellow on an Australian Research Council Discovery Project focusing on developing advanced adsorbents in Paul Webley Group at the University of Melbourne. Since 2015, as Co-chief Investigator of Australian Research Council Training Centre for Liquefied Natural Gas Futures, he has been actively participated in research along with major industry partners in oil and gas field. He then moved to Georgia Institute of Technology and worked as a postdoctoral fellow funded by ExxonMobil focusing on restricted gas diffusion in zeolites by advanced molecular simulation in David Sholl Group, prior to joining the City University of Hong Kong as an assistant professor in the School of Energy and Environment in September 2016.