THERMAL-ANALYSIS OF LAYERED MATERIALS - INFLUENCE OF CATIONS ON THERMAL-BEHAVIOR

Aluminium-free layered silicates of the metal silicate hydrate type (M -SH) comprise an interesting supplement to the well-known zeolite-like porous materials. Their specific properties allow these materials to be used as catalysts, adsorbents and ion-exchangers. Comparative X-ray diffraction and thermoanalytical investigations (TG and DSC) have sho wn that the thermoanalytical methods are useful to follow the process of structure formation of ilerite. The interlayer cations influence th e properties of the different ilerites. In particular, the hydration b ehaviour of ilerite is affected. Thus, H+- and DTMA(+)-ilerite are sta ble up to temperatures of about 800 degrees C, while the as-synthesize d Na-form loses water irreversibly at about 150 degrees C, is dehydrox ylated, and is then desomposed structurally at about 400 degrees C. Th e course of the dehydration exhibits significant differences for the v arious cation forms.