MgAl-Layered Double Hydroxide Films on Muscovite Mica: Epitaxial Growth and Catalytic Activity in Acetone Self-Condensation

Abstract

A simple method for the immobilization of layered double hydroxides (LDHs) on muscovite mica via strong covalent bonding is described. The crystal structure of the LDH films attached on the substrate was studied by X-ray diffraction (XRD) and attenuated total reflectance-Fourier transform infrared (ATR-FT-IR), and the morphology of the films was investigated by scanning electron microscopy (SEM) and atomic force microscopy (AFM), which showed that half-hexagonal shaped LDH platelets grow obliquely on the substrate with a high degree of dispersion. The lattice matching between LDH and muscovite structures suggests that the LDH phase grows epitaxially on the surface of the muscovite and the mechanism of the epitaxial growth process has been analyzed in detail. After being activated by a calcination/rehydration procedure, the rehydrated LDH (RLDH) platelets remain firmly immobilized on the muscovite substrate and retain the half-hexagonal platelet morphology of the LDH precursor. The RLDH/muscovite can act as a solid catalyst and shows higher activity in the aldol condensation of acetone than the powdered RLDH analogue synthesized by the same procedure.