Stable Ordered Mesoporous Silica Materials Templated by High-Temperature Stable Surfactant Micelle in Alkaline Media

摘要

Ordered hexagonal mesoporous silica material (JLU-30) has been successfully synthesized in alkaline media at high temperature (>160 ℃), using cationic (1,3-dimethyl-2-imidazolidin-2-ylidene)hexadecylmethylammonium bromide (DIHAB) as a template, and characterized with X-ray diffraction (XRD), transmission electron microscopy (TEM), nitrogen adsorption-desorption isotherms, differential thermal analysis (DTA), and thermogravimetric analysis (TG), as well as ~(27)Al and ~(29)Si nuclear magnetic resonance (NMR) spectroscopy. Mesoporous JLU-30 shows much higher hydrothermal stability than MCM-41. ~(29)Si NMR spectra indicate that the pore walls of JLU-30 samples synthesized at high temperature (160 ℃) are fully condensed, giving a Q~4/Q~3 ratio as high as 6.2. In contrast, MCM-41 synthesized at relatively low temperature (100 ℃) shows the Q~4/Q~3 + Q~2 ratio at 1.1. Such unique structural feature might be responsible for the observed highly hydrothermal stability of the mesoporous silica materials (JLU-30). Furthermore, heteroatoms such as Al and Ti species have been easily introduced into the mesoporous walls of JLU-30 by using a simple mixture of TEOS with aluminum or titanium source in the initial reaction gel.