Effect of H2–O2 pre-treatments on the state of gallium in Ga/H-ZSM-5 propane aromatisation catalysts
作者： I Nowak
DOI: 10.1016/S0926-860X(03)00299-0
关键词: Oxidation state 、 Bifunctional 、 Catalysis 、 Molecular sieve 、 Inorganic chemistry 、 Zeolite 、 Calcination 、 ZSM-5 、 Gallium 、 Chemistry
摘要: Abstract The state and local environment of gallium species in Ga/H-ZSM-5 zeolites prepared by ion-exchange have been identified various techniques. Small GaO(OH) particles (diameter ∼4–5 nm) were present after synthesis at the outer surface zeolite crystals together with some isolated large (needles 0.5–1.5 μm long 0.1–0.2 μm wide) Ga 2 O 3 . Upon calcination 823 K both transformed into small ∼4–5 nm), still crystals, while needles disappeared almost completely. Reducing–oxidising cycles enable migration these zeolite, most likely as ion-exchanged species. latter enhance bifunctional (dehydrogenating acidic) catalytic properties Ga-modified for aromatisation propane it appears that maintaining those I oxidation may aromatic yield.
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