Preparation and properties of zirconia-pillared zirconium phosphate and phenylphosphonate

Zirconium-pillared layered phosphates were prepared from a-zirconium phosph ate and zirconium phosphate phenylphosphonate by colloid manipulation metho d. The pillared a-zirconium phosphates are less thermally stable than the p illared phosphate phenylphosphonates. The latter can hold their layered str ucture intact until 500 degrees C, because the phenyl groups in the interla yer region inhibit the strong interaction between the oxide pillars and the sheets. Infrared and P-31 MAS-NMR spectroscopic studies show that P-O-Zr l inkages are formed after calcination as a result of this strong interaction . The surface areas of the pillared materials may reach 153-183 m(2)/g, and their pore size distributions are narrow and centered ca. 2 nm. Surface ac idity and basicity of the pillared materials were measured by infrared spec troscopy of pyridine adsorption and temperature-programmed desorption metho ds. They are weakly acidic, but almost non-basic. In comparison with ZrO2, they have more and stronger acid sites. The pillared materials, in particul ar the zirconium-pillared phosphate phenylphosphonate, are more catalytical ly active than ZrO2 for reactions such as dehydration of isopropanol, ester ification of acetic acid with ethanol and reduction of benzaldehyde. (C) 19 99 Elsevier Science B.V. All rights reserved.