Size-Dependent Properties of Nanocrystalline Silicalite Synthesized with Systematically Varied Crystal Sizes

Silicalite-1 powders with crystal sizes ranging from 20 to 1000 nm were synthesized by systematically varying synthesis gel composition, pressure, temperature, and time duration. These samples were characterized by powder X-ray diffraction, scanning electron microscopy, nitrogen adsorption isotherms, solid-state nuclear magnetic resonance, and toluene adsorption. The effect of crystal size on the physical properties of crystals is observed, including a large increase of both total and external surface area when crystal size decreases. The relationship between particle size and external surface area was modeled by assuming a cubic crystal geometry. The nanosized silicalite samples with crystal sizes less than 100 nm have a higher adsorption capacity for toluene, showing promising potential for its application in volatile organic compound removal.