Dehydration and lithium ion-exchange of the open framework vanadium silicate VSH-16Na

Accessibility of Lithium Cations in VSH‐2 Zeotype: Structural Effects and Formation of Protonated Water Clusters

“…The exclusion of small Li + cations at specific exchange sites is compensated by the presence of larger hydronium H 3 O + species, interacting with their environment exclusively through hydrogen bonds, to maintain the framework electroneutrality. [16] To further investigate Li + exchange and interactions with VSH frameworks, we selected VSH-2Cs of composition Cs 2 (VO)Si 6 O 14 • 3H 2 O, which is a prospective material for sizeselective adsorption of molecules and ion-exchange. [17] This material is a small-pore zeotype, whose channels have a width defined by 8-membered rings (8MR) and a free aperture of 3.0×3.6 Å.…”

“…In Li‐exchanged VSH‐12Cs, one of the three Li extraframework positions appears to be strongly underbonded with Li−O distances too long for the coordination requirement of Li cations, suggesting an incomplete exchange reaction. Similarly in VSH‐16Na, only 2/3 of the Na + ions could be substituted by Li + , leading to the formation of an alkali deficient framework [16] . Differences in the position and bond energy of the cationic sites seems to strongly affect the extent and kinetics of the cation exchange in VSH‐16Na.…”

“…Differences in the position and bond energy of the cationic sites seems to strongly affect the extent and kinetics of the cation exchange in VSH‐16Na. The exclusion of small Li + cations at specific exchange sites is compensated by the presence of larger hydronium H 3 O + species, interacting with their environment exclusively through hydrogen bonds, to maintain the framework electroneutrality [16] …”