Preparation and characterization of mesoporous zirconium phosphates from alkyl phosphates

Zirconium alkyl phosphates (ZrAP) were prepared by the reaction of ZrOCl2 · 8H2O with a mixture of aqueous phosphoric acid solution and monoalkyl phosphates (alkyl = decyl, stearyl) synthesized in the laboratory. All of the ZrAP samples showed X-ray diffraction peaks at diffraction angles below 2θ = 8°. The calcined powders were mesoporous containing POH groups which were stable at high temperatures, and were crystallized into ZrP2O7 by heating them at temperatures over 960 °C. The pores could be classified into wedge-shaped pores and spaces between parallel plates using small angle X-ray scattering and high-resolution transmission electron microscopy, and the specific surface area was found to be 130–308 m2/g by N2 sorption measurements. A comparison of the materials synthesized under different conditions revealed that the ZrP layers supported by the neighboring particles maintained their layer structure during the calcination procedure performed to remove the alkyl chains.