Plugged Hexagonal Templated Silica (PHTS):  An In-Depth Study of the Structural Characteristics

• Published in: The journal of physical chemistry. B 2004-04, Vol.108 (17), p.5263-5268
• Main Authors: Van Bavel, Ellen, Cool, Pegie, Aerts, Katrien, Vansant, Etienne F
• Format: Article
• Language: English
• ISSN: 1520-6106; 1520-5207
• DOI: 10.1021/jp049815a

Hexagonal mesoporous silica materials (PHTS) are synthesized with a high TEOS/EO20PO70EO20 ratio containing microporous nanocapsules or plugs inside the mesoporous channels. This PHTS material exhibits a tunable amount of open and plugged pores, has a high micropore volume (up to 0.24 mL/g), and is more stable than conventional micellar templated structures known so far. This study focuses on a thourough investigation of the influence of the amount of TEOS, the stirring temperature, the aging temperature, and the stirring time on the material characteristics using N2 sorption, X-ray diffraction, and scanning electron microscopy. PHTS materials with different amounts of TEOS were synthesized at stirring temperatures between 60 and 100 °C. At 60 °C, materials synthesized with a molar ratio TEOS/P123 of 125 proved to have a more rigid silicate framework than materials synthesized with lower amounts of TEOS resulting in PHTSs with a smaller diameter. The amount of TEOS and the stirring temperatures proved to play an important role in the material formed. Unlike SBA-15, the micropore volume of PHTS tended to increase with increasing temperature where the maximum value was found for the highest amount of TEOS used (TEOS/P123 = 125). The influence of the aging temperature on the structural characteristics of PHTS is the same as that of the stirring temperature but less pronounced. An aging temperature of 80 °C improved the structural characteristics greatly and also enlarged the particle size, whereas 4 h was shown as the minimum stirring time required.