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Oxidative Dehydrogenation and Ammoxidation of Propane in the Presence of N2O over CoH-BEA Catalysts

Autoři: Novoveská Kateřina | Bulánek Roman | Wichterlová Blanka | Dědeček Jiří

Rok: 2003

Druh publikace: ostatní - přednáška nebo poster

Název zdroje: EuropaCat-VI

Název nakladatele: University of Innsbruck

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Jazyk	Název	Abstrakt	Klíčová slova
cze			xxx
eng	Oxidative Dehydrogenation and Ammoxidation of Propane in the Presence of N2O over CoH-BEA Catalysts	Nitrous oxide exhibits different oxidizing properties compared to molecular oxygen as by its decomposition atomic oxygen is formed. This has been manifested in selective oxidation of benzene to phenol and oxidative coupling of methane. The contribution deals with the effect of addition of N2O to propane/O2 and propane/O2/NH3 streams during oxidative dehydrogenation and ammoxidation over Co-beta zeolite catalysts.Co-BEA zeolite was prepared by ion exchange from cobalt acetate solutions. Co-BEA activity in propane oxidative dehydrogenation and ammoxidation was investigated in a fixed-bed micro-reactor at propane/oxygen 5.0/6.5 vol. % and propane/O2/NH3 5.0/6.5/10 vol. % depending on temperature and N2O/O2 concentrations. UV-Vis spectra of Co ions were monitored in reflectance mode on Perkin-Elmer 19 equipped with high-temperature cell. Addition of nitrous oxide into the propane/O2 stream caused a substantial increase in propane conversion (ca 3-4 x) and propylene yield. Using only N2O without oxygen resulted in low propane conversion comparable to that one in oxygen. These results imply a synergic effect of N2O and O2 on the selective oxidation of propane to propylene. In contrast to oxidative dehydrogenation, with the ammoxidation reaction no positive effect of N2O was found. UV-Vis spectra of Co-Beta zeolite monitored at the conditions of catalytic reaction (in-situ experiment) provided information on the Co ion siting in the Co-beta zeolite (cf. Ref. 1), and strong bonding of ammonia on all Co ions at the temperature of ammoxidation reaction (450oC). These findings indicate that the presence of ammonia blocks the Co ions on which, on the other hand, at the propane oxidative dehydrogenation atomic oxygen, formed from N2O, can be supposed to be bonded.	propane, oxidative dehydrogenation, ammoxidatioin, CoH-BEA catalysts

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