Zr K-edge XAS study on ZrO2-pillared aluminosilicate

The ZrO2-pillared clay with high acidic property has been prepared by reacting 1 wt% colloidal suspension of Na+-montmorillonite with 1 N aqueous solution of ZrOCl2·8H2O and by subsequent heating. The evolution of local structure around zirconium of the intercalant stabilized in-between aluminosilicate layers upon intercalating, drying, and pillaring condition has been systematically studied by X-ray absorption spectroscopy, and compared to those of reference compounds such as ZrO2, and ZrOCl2 · 8H2O and its 1 N aqueous solution. The intercalated zirconium species was identified as the Zr-tetramer, [Zr4(OH)14(H2O)10]2+, with an average molecular volume of 10 × 10 Å2 and a thickness of 4.5 Å. Also it becomes more condensed upon drying and eventually transforms to a zirconium oxide pillar upon calcination.