In situ growth of layered double hydroxide films on anodic aluminum oxide/aluminum and its catalytic feature in aldol condensation of acetone

Mg/Al layered double hydroxide (LDH) films were fabricated in situ with anodic aluminum oxide (AAO)/aluminum as both the substrate and the sole aluminum source by means of urea hydrolysis. The structure and morphology of the LDH films were investigated by X-ray diffraction (XRD), attenuated total reflectance-Fourier transform infrared (ATR-FT-IR) and scanning electron microscopy (SEM), which show that hexagonal plate-shaped LDH crystallites grow perpendicularly on the substrate via a strong chemical interaction. After being activated by a calcination/rehydration procedure, the rehydrated LDH (RLDH) platelets remain firmly immobilized on the AAO/aluminum substrate and retain the hexagonal platelet morphology of the LDH precursor. The catalytic activity of the resulting material was tested by using aldol condensation of acetone as a probe reaction, showing that the RLDH/AAO is superior in catalytic performance to the powdered RLDH analogue. The kinetic feature of this catalytic reaction was also analyzed, which suggests that it obeys the D1D1 kinetic model, a one-dimensional diffusion-controlled mechanism.