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Gallium-containing zeolites: characterization of catalytic role of gallium species in converting light paraffins to aromatics

“…69 Ga of higher quadrupole moment reveals less sensitivity and less resolution on NMR than for 71 Ga. 71 Ga MAS NMR has been employed to characterize the Ga species, the resonance at $0 ppm is assigned to octahedral Ga 3+ present in Ga 2 O 3 [17], and the resonances at 140 ppm is related to tetrahedral Ga 3+ of Ga(OH) 2 + attached to the Brønsted site of zeolite framework, while that at 174 ppm is related to Ga 3+ O 4 of Ga 2 O 3 . Although both species are in tetrahedral coordination, they are still the extra-framework species and are present in a dry gel of Ga 2 O 3 and H-BEA zeolite after water vapor treatment [9].…”

Recent Trends in Operando and In Situ Characterization: Techniques for Rational Design of Catalysts

“…In situ 13 C MAS NMR spectroscopy under flow conditions has supported the presence of a hydrocarbon pool mechanism and elucidated the species involved in this pool for H-ZSM-5 zeolites [135,136]. Under methanol feed at temperatures ≥250 • C, H-ZSM-5 produced mainly ethylene and propylene as evidenced by gas chromatography-mass spectrometry (GC-MS).…”

Methanol‐to‐Hydrocarbons

“…10. Today, the importance of direct C − C bond formation is considered to be minor and the hydrocarbon pool mechanism is gaining general acceptance [33][34][35].…”