Hydrolysis in polyol: New route for hybrid-layered double hydroxides preparation

A new route has been investigated for layered double hydroxides (LDH) preparation using hydrolysis of metal salt precursors in polyol medium (ethylene glycol and diethylene glycol) under reflux. It constitutes a simple way to prepare hybrid LDH in soft chemistry conditions. The process of LDH formation rests on progressive extraction of aluminum from an insoluble complex, which is conditioned by water addition and presence of divalent metallic cations. We focused on the preparation of LDH with cation compositions NiAl and CoAl. Many advantages are demonstrated over the standard coprecipitation method, in terms of phase purity and morphology. Indeed, this method avoids the use of any other precipitation reagents and pH or atmosphere control. The formation of LDH and presence of acetate in the interlayer region was confirmed by X-ray data, IR spectroscopy, and ionic chromatography. Moreover, controlled calcinations of as-prepared LDH allow preparing mixed oxides with enhanced specific surface area properties (up to 250 m(2)/g) and narrow pore range distributions in the mesoporous region of interest for catalytic applications.