Marathe R P, Farooq S, Srinivasan M P
Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, Singapore 117576.
J Phys Chem B. 2005 Mar 3;109(8):3257-61. doi: 10.1021/jp0461192.
Strontium-exchanged titanium silicate, Sr-ETS-4, is a new molecular sieve with promises for exciting applications in gas separation. The literature mentions poor thermal stability and low adsorption capacity as the drawbacks of the as-synthesized Na-ETS-4 and therefore the need for cation exchange. Upon ion exchange, Sr-ETS-4 shows appreciable kinetic selectivity between methane and nitrogen, which can be improved further by controlled dehydration. In this study, we trace the changes at the molecular level behind this improvement. By combining distributed information in the literature, it is shown that the governing factors are changes in pore geometry with progressive dehydration, changes in ion occupancy, and relocation of cations due to Sr exchange.
