Nanoparticle silicalite-1 crystallization as monitored by nitrogen adsorption

• Published in: Microporous and mesoporous materials Vol. 131; no. 1; pp. 230 - 237
• Main Authors: Tokay, Begüm, Karvan, Oğuz, Erdem-Şenatalar, Ayşe
• Format: Journal Article
• Language: English
• Published: San Diego, CA Elsevier Inc 01.06.2010; Elsevier
• Subjects: Adsorption; Chemistry; Colloidal state and disperse state; Crystallization; Exact sciences and technology; General and physical chemistry; Ion-exchange; Nanomaterials; Nanoparticles; Nanostructure; Nitrogen adsorption; Nucleation; Physical and chemical studies. Granulometry. Electrokinetic phenomena; Pore size; Porous materials; Silicalite-1; Surface chemistry; Surface physical chemistry; Synthesis; Zeolites: preparations and properties; Nanoparticles; Nucleation; Nitrogen adsorption; Silicalite-1; Crystallization; Crystal growth; Micropore; Nanoparticle; Porous material; Molecular sieve; Solid; Aggregation; Particle; Pore size; Synthesis; Diameter; Zeolite; Nitrogen; Mesoporosity; Functional theory; Microporosity; Density functional; Adsorption; Isotherm; Surface area
• ISSN: 1387-1811; 1873-3093
• DOI: 10.1016/j.micromeso.2009.12.028

Nanoparticle silicalite-1 crystallization from clear solutions was followed by nitrogen adsorption at 77 K, applied to the products collected from the synthesis solution at different times. Isotherm data were analyzed by t-plot/BET, density functional theory (DFT), and Saito–Foley methods. Variation in the micropore and mesopore/external areas and volumes of the products with time, were in strong agreement with a recent study, which indicated that nucleation that took place after an induction time, was accompanied by an aggregation of a population of smaller particles. A sharp decrease in external surface area was observed parallel to a significant increase in the micropore area of the solid product at this stage of synthesis, when a sudden jump in the effective diameter of the nanoparticles in solution was recorded. Although earlier appearance in the solid products, of small amounts of particles/regions with pore sizes in a range including the pore sizes of silicalite-1, was indicated by both the DFT and Saito–Foley analyses, variation of the Saito–Foley median diameter with synthesis time provided a clear evidence of the significance of this “induction time”, after which particles could grow at a constant linear rate. Nitrogen adsorption at 77 K was shown to be a useful tool to monitor the nucleation and crystal growth of silicalite-1 nanoparticles.