10.1002/cctc.201901728
ChemCatChem
FULL PAPER
materials in xylene (0.5 M concentration by metal), followed by filtration
using a glass filter. Then, the FSP precursor solutions were applied in the
FSP process as described previously.33 In brief, the precursor solutions
were pumped through a capillary at a rate of 5 mL/min, and nebulized in 5
L/min O2. The resulting spray was ignited by an annular supporting
methane/oxygen flame (1.5/0.9 L/min). Particles were collected on a
cooled Whatman GF6 filter (257 mm diameter). A Busch SV 1040C
vacuum pump aided in particle recovery. The synthesized silica-alumina
powders are designated as SA/Xx, where X is 5, 10, 30 and 70,
representing the atom% of Al in the precursor and x indicates the use of
xylene as solvent to distinguish from the methanol/acetic acid (denoted as
SA/X) used in the earlier work.[33]
(%) = 100 × (i) / [(glyceraldehyde)0-(glyceraldehyde)], where (i) is the molar
concentration of the product and (glyceraldehyde)0 and (glyceraldehyde)
correspond to the molar concentration of glyceraldehyde before and after
the reaction, respectively.
Acknowledgments
This work was supported by the Australian Research Council
Discovery Projects (DP150103842) and Discovery Earlier Career
Research Project (DE190101618), and SOAR fellowship from the
University of Sydney.
Solid-state NMR investigations. Before the 1H and 27Al MAS NMR
experiments, the samples filled into glass tubes were dehydrated at 723 K
for 12 h at a pressure of less than 10-2 bar. These dehydrated samples
were sealed in glass tubes or directly loaded with ammonia on a vacuum
line. Subsequently, the loaded samples were evacuated at 383 K for 1 h
to remove weakly physisorbed molecules. Then, the samples were
transferred into the MAS NMR rotors under dry nitrogen gas inside a glove
box. 1H and 27Al MAS NMR investigations were performed on a Bruker
Avance III 400 WB spectrometer with a 9.4 Tesla superconducting magnet
operating at resonance frequencies of 400.1 and 104.3 MHz, respectively,
with a sample-spinning rate of 8 kHz using 4 mm MAS rotors. 1H MAS
NMR spectra were recorded after single-pulse /2 excitation with a
repetition time of 20 s. 27Al MAS NMR spectra were recorded after single-
pulse /6 excitation with a repetition time of 0.5 s.
Keywords: silica-alumina • acidity • solid-state NMR •
cyclohexane dehydration • glyceraldehyde conversion
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