FTIR Spectroscopic Study of Low Temperature NO Adsorption and NO + O2 Coadsorption on H−ZSM-5

Autor:	Konstantin Hadjiivanov, Mihail Mihaylov, Lavalley Jc, Marco Daturi, Anna Penkova, Jacques Saussey
Rok vydání:	2004
Předmět:	Chemistry Inorganic chemistry Cationic polymerization chemistry.chemical_element Surfaces and Interfaces Condensed Matter Physics Oxygen Spectral line Adsorption Electrochemistry Molecule Physical chemistry General Materials Science ZSM-5 Fourier transform infrared spectroscopy Zeolite Spectroscopy
Zdroj:	Langmuir. 20:5425-5431
ISSN:	1520-5827 0743-7463
DOI:	10.1021/la0496643
Popis:	Adsorption of NO and coadsorption of NO and O2 on H-ZSM-5 have been studied at low and room temperature by means of FTIR spectroscopy. For better interpretation of the spectra, experiments involving isotopic labeled molecules have been performed. Low temperature adsorption of NO on H-ZSM-5 results initially in formation of NO which is H-bonded to the zeolite acidic hydroxyls. A second NO molecule is inserted into the OH-NO species at higher coverages, thus forming OH(NO)2 complexes. Different kinds of NO dimers are also formed. Negligible amounts of oxygenated compounds have been detected. In the presence of oxygen, the (di)nitrosyl species are oxidized very fast even at 100 K to N2O3, NO+, NO2, and N2O4. Different kinds of adsorbed N2O3 species have been evidenced. With increasing temperature, NO+ migrates and occupies cationic positions. The latter species interacts with NO at low temperature to give an [ONNO]+ complex. This reaction is used to prove that the different bands in the 2206-2180 cm(-1) region are also due to NO+ species.
Databáze:	OpenAIRE
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