Formation of chromium interlayers in α-zirconium phosphate

Abstract

Interlayered materials with basal spacings 15–26 Å, obtained when the half-sodium-exchanged form of α-zirconium bis(hydrogenphosphate) is refluxed with solutions of chromium(III) acetate, have been studied by thermal analysis, X-ray powder diffraction, electron microscopy, e.s.r. and i.r spectroscopy; surface areas were also determined. The reaction causes expansion of the interlayer spacing, to a degree depending on the initial chromium content of the solution and the temperature. The results are interpreted in terms of the formation of a hydrous chromium acetate interlayer species which decomposes on heating between 300 and 400 °C. The surface area of the α-zirconium phosphate does not change appreciably on reaction with chromium(III) acetate indicating that interlayer crowding effects play a dominant role.