Preparation of M0 metal/alumina-pillared mica composites (M = Cu, Ni) by in situ reduction of interlayer M2+ ions of alumina-pillared fluorine micas

Alumina-pillared fluorine micas form micropores in the interlayer region and exhibit cation exchangeability. Reduction of 3d transition metal cations (Cu2+ and Ni2+) in the interlayer regions of the cation exchanged alumina-pillared micas was attempted using ethylene glycol or diethylene glycol. The Cu2+-exchanged pillared mica led to the formation of a pillared mica composite containing interlayer zero-valence Cu0 metal clusters along with Cu0 metal fine particles on external surfaces of pillared mica flakes when refluxed in either ethylene glycol or diethylene glycol. Ni2+ cations in the interlayer region were also found to be reducible by refluxing in diethylene glycol. The zero-valence metal contained in the refluxed products occurs in three forms: M0 clusters in the interlayer region, elongated fine particles sandwiched between silicate layers, and submicron spherical particles on external surfaces of mica crystals. The zero-valence metal/alumina-pillared mica composites thus obtained largely retained the micropore properties of the alumina-pillared micas.