Open-framework and microporous vanadium silicates

A series of novel vanadium silicates with open-framework and microporous structures has been synthesized under mild hydrothermal conditions. Ten distinct framework types have been identified that all have structures based on cross-linking single silicate sheets with square pyramidal (VO5)-O-IV units to give compounds with the general formula A(r)[(VO)(s)(Si2O5)(p)(SiO2)(q)].tH(2)O, where A is Na, K, Rb, Cs, or a combination. The vanadosilicate (VSH-n) structures have free channel diameters up to 6.5 Angstrom and show good thermal stability, absorption, and ion-exchange properties, suggesting their potential for technological applications as molecular sieves or in catalysis.