REVEALING THE DEFINITE MORPHOLOGY OF MESOPOROUS SILICA KAUST CATALYSIS CENTER–1 (KCC-1) LEADING TO IT’S NOVEL FORMATION MECHANISM

• Main Author: Febriyanti, Erna
• Format: Theses
• Language: Indonesia
• Subjects: Kimia
• Online Access: https://digilib.itb.ac.id/gdl/view/33993
• Institution: Institut Teknologi Bandung

Unique open three-dimensional pore structure makes significant differences between KCC-1 and conventional mesoporous silica. Their distinguished morphology switch their properties and help the development of various applications in catalysis, environmental and biomedical. Among miscellaneous morphology silica particles, KCC-1 provide good accessibility of surface area. Here, we explore the morphology of KCC-1 and its rational formation mechanism by changing some synthesis parameters including the synthesis technique, temperature and time, stirring rate, and composition ratio of H2O/TEOS and CTAB/TEOS. Basically, KCC-1 with good particle size distribution was produced with a minimum stirring rate of 600 rpm, then by applying solvothermal condition at 100 – 120 °C for ± 4h. Most of the parameter changing in the synthesis of KCC-1 produce non-linear relationship between particle size and their textural properties (surface area and pore volume). These trends changed when we applied different CTAB concentration. The interpretation of morphology by SEM image and contour plot of TEM image led to a more representative term called concentric bicontinous lamellar morphology. Some simple experiments were carried out to understand this morphology. Conductometry analysis of KCC-1 emulsion identified water in oil phase in the emulsion where the cmc of CTAB reverse micelle in this ternary systems was found to be ~ 48 mM. Raman Spectroscopy analysis also supported the existencee of this condition. Modified Avrami equation was used to analyze the nucleation and growth of KCC-1. These findings are then pointed to a logical mechanism for KCC-1 formation. At beginning, silica polymerization into polysiloxane (non polar) in the water (polar) phase of reverse micelle produced irregular bicontinous structure. This structure then became denser. As time goes by, more ethanol produced by silica condensation caused a phase shifting in the water phase of reverse micelle. This phase shifting grew the silica polymerization yielding a lamellar bicontinous shape. The denser area in the core of silica made the structure become concentric just like the core-shell morphology.