Bertrand Maquin

Preparation of silicalite-1/glass fiber composites by one- and two-step hydrothermal syntheses

Abstract The crystallization of silicalite-1 on glass fiber supports by one- and two-step hydrothermal synthesis procedures was investigated. One-step synthesis (130, 150 or 170 °C) provided composites with an overall specific surface area of up to 200 m 2 /g. The effect of the starting composition and synthesis parameters on the physico-chemical properties of the composite was studied. The silicalite-1 content of the composites was controlled by the composition of the starting gel, in particular the tetrapropylammonium hydroxide concentration, the temperature and duration of the synthesis. The substantial increase in the silicalite-1 content of the composites led to a deterioration of the mechanical properties of the fiber support. The application of a two-step procedure, which consists at a rapid crystallisation (150 or 170 °C) after a nucleation at low temperature (130 °C), provided composites with better mechanical properties and surface areas between 26 and 121 m 2 /g. The silicalite-1/glass fiber composites were studied by XRD, SEM, SIMS, TG/DTA and nitrogen adsorption measurements.