Preparation and properties of zirconia-pillared zirconium phosphate and phenylphosphonate Original Research Article

Zirconium-pillared layered phosphates were prepared from α-zirconium phosphate and zirconium phosphate phenylphosphonate by colloid manipulation method. The pillared α-zirconium phosphates are less thermally stable than the pillared phosphate phenylphosphonates. The latter can hold their layered structure intact until 500°C, because the phenyl groups in the interlayer region inhibit the strong interaction between the oxide pillars and the sheets. Infrared and 31P MAS-NMR spectroscopic studies show that P–O–Zr linkages are formed after calcination as a result of this strong interaction. The surface areas of the pillared materials may reach 153–183 m2/g, and their pore size distributions are narrow and centered ca. 2 nm. Surface acidity and basicity of the pillared materials were measured by infrared spectroscopy of pyridine adsorption and temperature-programmed desorption methods. They are weakly acidic, but almost non-basic. In comparison with ZrO2, they have more and stronger acid sites. The pillared materials, in particular the zirconium-pillared phosphate phenylphosphonate, are more catalytically active than ZrO2 for reactions such as dehydration of isopropanol, esterification of acetic acid with ethanol and reduction of benzaldehyde.