Hydrothermal synthesis and characterization of a layered zirconium silicate

A layered zirconosilicate composed of SiO4 tetrahedra and ZrO6 octahedra was hydrothermally synthesized in the presence of tetramethylammonium hydroxide. The layered material with a nominal composition Na2ZrSi4O11·xH2O was further characterized by XRD, SEM, thermogravimetric analysis, UV-Raman spectroscopy and single- and triple-quantum 23Na and 29Si MAS NMR spectroscopy. There are no Zr–O–Zr chains in the framework structure implying that the ZrO6 octahedra are isolated by SiO4 tetrahedra. 23Na MAS NMR indicates at least two different Na sites in the framework of SZS and the Na located in the interlayer can be exchanged by TMAOH, leading to an increase of the interlayer spacing. The layered zirconosilicate SZS has a high activity in the isomerization of glucose to fructose in water and can be reused.status: publishe