| dc.description.abstract | The thesis is divided into two parts. Studies on fluorination of zeolites HY and
amine functionalization of mesoporous materials.
First, HY samples treated with NH4F (FNH4F/AlHY = 3) at 80oC, 27Al NMR
revealed that tetrahedral aluminum was at 60 ppm from the zeolitic framework and
some extraframework aluminum was also observed. The corresponding 19F NMR
showed a dominant peak at -173 ppm with a shoulder at -182 ppm. Interestingly,
these fluorinated species were associated with tetrahedral framework Al at 50 ppm,
as revealed by 27Al/19F 2D HETCOR NMR for the first time. This observation
implies that these fluorinated species are possibly due to the framework Al-F species.
For HY samples treated with NH4F at 100oC, on the other hand, a broad powder
pattern spreading from -20 ppm to -70 ppm due to the NH4AlF4 crystalline phase is
observed for the cases of FNH4F/AlHY ≥ 2. The NH4AlF4 crystalline phase observed
exhibited two 19F resonance peaks at -151 ppm and -166 ppm, which are assigned to
the fluorine atoms in the terminal Al-F and bridging Al-F-Al group, respectively.
Different aluminum fluoro-complexes after dealumination were detected. First, for
NH4F treated HY, that tetrahedral aluminum was expelled from the zeolitic
framework, resulting in the formation of (NH4)3AlF6, which was evident from the
peak at -1 ppm in the 27Al MAS NMR and at -141 ppm in the 19F MAS NMR.
In the second part of thesis, direct synthesis of well-ordered cubic mesoporous
silicas SBA-1 with amino functionality group were direct-synthesized of containing
simultaneously tetrathoxysilane (TEOS) and 3-aminopropyltrimethoxsilane (APTMS)
and has been synthesized by cetyltriethylammonium bromide (CTEABr) under
strongly acidic conditions.
The materials obtained were characterized by variety of techniques including
power X-ray diffraction (XRD),nitrogen sorption measurements, scanning electron
microscopy (SEM), and thernmogravimetric analysis (TGA). Qualitative evidence of
present of chemically atteched amino group moieties was provided by solid-state 13C
and 29Si MAS NMR. | en_US |