Bacterial templating of zeolite fibres with hierarchical structure

Hierarchically structured meso-macroporous aluminosilicates with high tetrahedral aluminium content in acid catalysed esterification of fatty acids

“…This method combined with elemental analysis (Table 2) yields the silicon to aluminium ratios (Si/Al) and silicon to tetrahedral aluminium ratio (Si/Al T ). All the 27 Al MAS-NMR spectra of the aluminosilicate materials exhibit a more intense peak at 55-60 ppm and another one around 0-6 ppm, corresponding respectively to tetrahedrally co-ordinated intra-framework aluminium species and octahedrally extra-framework aluminium species. The more intense peak at 55-60 ppm suggests that most of the aluminium atoms are located inside the inorganic porous framework on tetrahedral sites with the Si atoms, establishing Al-O-Si linkages.…”

“…The morphology as well as the macroporous array was studied using a Philips XL-20 scanning electron microscope (SEM) and a JEOL JSM 7500 field emission scanning electron microscope (FE-SEM) with conventional sample preparation and imaging techniques. The environments of the Al and Si atoms were studied via 27 Al MAS NMR and 29 Si MAS NMR respectively, with a Bruker Avance 500 spectrometer and the Si/Al ratio was investigated with the help of a Philips PU9200X atomic absorption spectrometer. Na + ions exchange process was observed by 23 Na MAS-NMR (Bruker Avance 500 spectrometer) and the generation of NH þ 4 ions was studied by FTIR with KBr pellets loaded with 1 wt.% of material, using a Perkin-Elmer Spectrum 2000 spectrometer.…”

“…The co-ordination environments of Al atoms in the samples were characterised by 27 Al MAS-NMR (Fig. 5).…”

“…5 and in Table 2, 27 Al MAS-NMR spectra of aluminosilicate materials synthesised at pH of 13.0 (Fig. 5A) and 13.5 ( Fig.…”

“…These strategies can be summarised into two categories. One concerns the use of templates such as polymeric beads and silica opals [14][15][16], soft sacrificial template [17], foam [18,19], emulsions [20,21], ice crystals [22], natural structures [23] such as bacterial threads [24] with the combination of amphiphilic molecules or zeolite crystal seeds [25][26][27][28]. Other one is related to post-synthesis treatments [29].…”