Delaminated layered materials

Abstract

The delamination and subsequent modification of a synthetic hectorite clay, laponite, has been investigated as a route to new supports and catalysts possessing exposed crystalline surfaces. Delamination was carrier out by freeze drying aqueous suspensions of laponite. The resulting low density materials was shown by scanning electron microscopy to consist of sheet-like structures made up from many individual clay sheets. Although the material obtained is sensitive towards collapse in solvents, triiron dodecacarbonyl was added by chemical vapor deposition. Fourier transform infrared analysis indicated that the iron complex had attached to the edge surface of the delaminated clay sheets. As an alternative to using chemical vapor deposition for the introduction of metals, the original freeze-dried clay was first stabilized towards solvents and then ion exchanged. Stabilization was carried out by treating the freeze-dried clay with gas phase tetramethly orthosilicate. This reaction is suggested to involve crosslinking by silicon of adjacent clay sheet through edge surface hydroxyls. Palladium was subsequently introduced onto the crosslinked material by ion exchange using tetramminepalladium (II) chloride. © 1989.