A range of nanosize alkaline-free gallosilicate mesoporous molecular sieves (GaMMS) were synthesized using microwave hydrothermal method and various analytical and spectroscopic techniques were employed to systematically investigate the structure, coordination geometry of gallium, acidic properties and catalytic activity. These nanosize GaMMSs exhibit high surface area (240~720 m 2 /g), pore volume (1.06~1.49 m 3 /g), narrow pore size distribution and nano-particle size between 20 and 100 nm and four-coordinated gallium site mainly, which were characterized by XRD, N 2 adsorption/desorption, TEM, 71 Ga MAS-NMR and ICP-AES. Mesoporosity, mesostructure and nanosize can be controlled simply by microwave irradiation time and temperature. Pyridine-IR result reveals the coexistence of Lewis and Brönstead acid sites in these nanosize GaMMS while NH 3 -TPD profiles suggest nanosize one has stronger acid site and contains more acid sites than the conventional one. Catalytic performance was evaluated using the catalytic cumene cracking test. The result indicates that the nanosize GaMMS shows a much higher activity than that of conventional GaMCM-41, probably due to higher concentrations of H-form sites, external surface and fast diffusion.
Key indicators: single-crystal X-ray study; T = 297 K; mean (C-C) = 0.002 Å; R factor = 0.043; wR factor = 0.126; data-to-parameter ratio = 12.8.The title molecule, C 12 H 10 N 4 O 2 , located about an inversion centre, is roughly planar, with an r.m.s. deviation from the least-squares plane of all non-H atoms of 0.019 Å . In the crystal, N-HÁ Á ÁN hydrogen bonds between the amide N-H group and the pyridine N atom connect the molecules into a corrugated layer parallel to (101).
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Data collectionBruker SMART 1000 diffractometer Absorption correction: multi-scan (SADABS; Bruker, 1997) T min = 1.000, T max = 1.000 2997 measured reflections 1050 independent reflections 768 reflections with I > 2(I) R int = 0.034
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